ARTICLE | doi:10.20944/preprints202306.0764.v1
Subject: Engineering, Bioengineering Keywords: type 2 diabetes mellitus; functional near-infrared spectroscopy; muscle near-infrared spectroscopy; cognitive impairment; operational modal analysis
Online: 12 June 2023 (05:03:09 CEST)
The Global Burden of Disease Study (GBD 2019 Diseases and Injuries Collaborators) found that diabetes significantly increases the overall burden of disease, leading to a 24.4% increase in disability-adjusted life years. Persistently high glucose levels in diabetes can cause structural and functional changes in proteins throughout the body, and the accumulation of protein aggregates in the brain is associated with the progression of Alzheimer's Disease (AD).To address this burden of type 2 diabetes mellitus (T2DM), a combined aerobic and resistance exercise program was developed based on the recommendations of the American College of Sports Medicine. The prospectively registered clinical trials (https://www.clinicaltrials.gov/ct2/show/NCT04626453, https://www.clinicaltrials.gov/ct2/show/NCT04812288) involved two groups: an Intervention group of older sedentary adults with T2DM and a Control group of healthy older adults who could be either active or sedentary. The completion rate for the 2-month exercise program was high, with participants completing on an average of 89.14% of the exercise sessions. This indicated that the program was practical, feasible, and well-tolerated, even during the COVID pandemic. It was also safe, requiring minimal equipment and no supervision. The exercise instructions were easy to understand, making them suitable for older adults with cognitive decline.The near-infrared spectroscopy (NIRS) based brain and muscle oxygenation study provided evidence on brain overactivation among older adults with T2DM, supporting the compensatory theory. It also demonstrated that the 2-month combined exercise intervention effectively reduced brain overactivation and contributed to improved cognitive function. Operational modal analysis showed an exercise-related effect on the very low-frequency hemodynamic oscillations cluster, which may be associated with better vascular muscle and/or perivascular neurogenic regulation. Furthermore, we personalized the exercise duration and interval based on muscle oxygenation during physical tasks, leading to improvements in muscle oxidative capacity within just two months. This finding has practical implications for physical therapists, as they can target muscle oxygenation changes during physical tests to prescribe appropriate exercise doses for enhancing physical performance.
ARTICLE | doi:10.20944/preprints201904.0088.v1
Subject: Biology And Life Sciences, Biology And Biotechnology Keywords: Near Infrared Spectroscopy (NIRS); oxygen consumption; hemoglobin; myoglobin; skeletal muscle
Online: 8 April 2019 (11:28:43 CEST)
NIRS uses the relative absorption of light at 850nm and 760nm, to determine skeletal muscle oxygen saturation. Previous studies have used the ratio of both signals to report muscle oxygen saturation. Purpose: To evaluate the different approaches used to represent muscle oxygen saturation, and to evaluate the pulsations of the O2heme and Heme signal. Method: Twelve participants, ages 20-29years were tested on the forearm flexor muscles using continuous wave NIRS at rest. Measurements were taken during 2-3mins rest, during physiological calibration (5-minuts Ischemia) and during reperfusion. Results: There was a significant difference in pulse size between O2heme and Heme signal at the three locations (p < 0.05). Resting oxygen saturation was 58.8+9.2%, 69.6+3.9%, and 89.2+6.9% when calibrated using O2heme, TSI, and Heme, respectively. Conclusion: The difference in magnitude of O2heme and Heme pulse with each heartbeat might suggest different anatomical locations of these signals, which propose calibrating with just one of the signals instead of the ratio of both. Calculations of physiological calibration must account for increased blood volume in the tissue, because of the changes in blood volume which appear to be primarily from the O2heme signal. Resting oxygen levels calibrated with Heme agrees with theoretical oxygen saturation.
ARTICLE | doi:10.20944/preprints201904.0314.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: near infrared spectroscopy; NIRS; skeletal muscle; muscle metabolism; electrical stimulation
Online: 28 April 2019 (11:27:52 CEST)
Near-Infrared Spectroscopy (NIRS) has been used to measure muscle mitochondrial capacity. The current method requires as many as 22 short ischemic occlusions to generate a recovery curve for mitochondrial capacity. PURPOSE: To determine the effectiveness of using a 6-occlusion analysis protocol to study muscle mitochondrial capacity. METHOD: Two independent, unidentified data sets were analyzed (bicep n=48, forearm n=41) from previous studies using a NIRS device (Artinis, Ltd.). Both data sets had two recovery tests that included 22 ischemic occlusions. A recovery rate used to indicate mitochondrial capacity was calculated two different ways (simultaneously). Each sample was analyzed with a MATLAB program; with a curve-fit for the 22 ischemic occlusions and curve matching for the first six ischemic cuffs and an end resting value. The two resulting rate constants were compared using correlations, both for the two data sets, good and bad fitting data, using the best 5 of 6 points for the 6 cuff approach. RESULTS: The rate constants were not significantly different between the 22 cmuff and 6 cuff for the total data sets: bicep (1.43+0.32min-1, 1.44+0.35min-1, p=0.56), forearm (1.94+0.42min-1, 1.95+0.44min-1, p=0.76). The average bicep rate constants, when compared to each other, had an equation of y=1.07x-0.09, R2=0.90. The average forearm rate constants, when compared to each other, had an equation of 0.98x+0.02, R2=0.93. CONCLUSIONS: The 6-Cuff analysis provided the same results as the longer 22-cuff. The 6-cuff approach is both shorter in time and uses less ischemic occlusion periods, increasing the practicality of the NIRS mitochondrial capacity test.
ARTICLE | doi:10.20944/preprints202306.1741.v1
Subject: Biology And Life Sciences, Agricultural Science And Agronomy Keywords: 'Huangguan' pear; phosphorus; near-infrared spectroscopy; modelling; content prediction
Online: 26 June 2023 (05:11:34 CEST)
'Huangguan' pear has significant social and economic value, and phosphorus, as one of the three main mineral elements of plants, has an irreplaceable effect on the normal growth of 'Huangguan' pear trees. The objective of this study was to predict the content of phosphorus in the pulp and peel of ‘Huangguan’ pears nondestructively and conveniently by using near-infrared spectroscopy (900–1700 nm) technology. First, twelve algorithms are used to preprocess the original spectral data, and the partial least squares regression algorithm and the gradient boosting regression tree algorithm are used to build a full-band prediction model based on the original spectral data and the processed spectral data. The characteristic wavelengths were extracted using genetic algorithms, followed by establishing a characteristic wavelength prediction model. The prediction accuracy of the models was evaluated according to the coefficient of determination R² and the relative analysis error RPD. The study found that the best prediction model for predicting phosphorus content in the pulp of 'Huangguan' pear was MSC-GA-PLSR, which had R²=0.843 and RPD=1.857 in the modelling set and R²=0.989 and RPD=7.041 in the prediction set. The best prediction model for predicting phosphorus content in the peel of ‘Huangguan’ pear was SG+SNV+FD-GA-PLSR, which had R²=0.991 and RPD=7.470 in the modelling set and R²=0.974 and RPD=4.414 in the prediction set, and the effect was good and met expectations. The results demonstrated that near-infrared spectroscopy could successfully achieve nondestructive detection of phosphorus content in the pulp and peel of 'Huangguan' pears.
ARTICLE | doi:10.20944/preprints201704.0166.v1
Subject: Medicine And Pharmacology, Other Keywords: optoelectronic sensor; near-infrared spectroscopy; thrombus diagnosis; shock monitoring; fatigue evaluation
Online: 26 April 2017 (06:05:07 CEST)
We attempted to apply the optoelectronic sensor entitled 'OPT101' in intensive care unit clinics, based on its optoelectronic response characteristics in near-infrared wavelength range and near-infrared spectroscopy principle. The successful novel applications in our lab include early-diagnosis and therapeutic effect tracking of thrombus, noninvasive monitoring of patients' shock severity, and fatigue evaluation. This study also expects further improvements of the detector in noninvasive clinical applications.
ARTICLE | doi:10.20944/preprints202109.0487.v1
Subject: Physical Sciences, Applied Physics Keywords: near-infrared spectroscopy; brain; BOLD signal; breath holding; cytochrome C oxidase
Online: 29 September 2021 (10:50:12 CEST)
A major limitation of near-infrared spectroscopy (NIRS) is its high sensitivity to the scalp and low sensitivity to the brain of adult humans. In the present work we use multi-distance hyperspectral NIRS (hNIRS) to investigate the optimal source-detector distances, range of wavelengths, and analysis techniques to separate cerebral responses to 30-s breath holds (BHs) from the responses in the superficial tissue layer in healthy adult humans. We observed significant responses to BHs in the scalp hemodynamics. Cerebral responses to BHs were detected in the cytochrome C oxidase redox (rCCO) at 4 cm without using data from the short-distance channel. Using the data from the 1 cm channel in the two-layer regression algorithm showed that hemodynamic and rCCO responses also occurred at 3cm. We found that the waveband 700-900 nm was optimal for the detection of cerebral responses to BHs in adults.
Subject: Physical Sciences, Acoustics Keywords: Single-pixel; spectroscopy; near-infrared; DMD; multiplexing; spectral coding; sub-millisecond; compressive measurement
Online: 31 July 2021 (15:10:23 CEST)
In this contribution, we present a high-speed multiplex grating spectrometer based on a spectral coding approach that is founded on principles of compressive sensing. The spectrometer employs a single-pixel InGaAs detector to measure the signals encoded by an amplitude spatial light modulator (digital micromirror device, DMD). This approach leads to a speed advantage and multiplex sensitivity advantage atypical for standard dispersive systems. Exploiting the 18.2 kHz pattern rate of the DMD, we demonstrate 4.2 ms acquisition times for full spectra with a bandwidth of 450 nm (5250 cm-1 – 4300 cm-1; 1.9 µm – 2.33 µm). Due to the programmability of the DMD, spectral regions of interest can be chosen freely, thus reducing acquisition times further, down to the sub-millisecond regime. The adjustable resolving power of the system accessed by means of computer simulations is discussed, quantified for different measurement modes, and verified by comparison with a state-of-the-art Fourier-transform infrared spectrometer. We show measurements of characteristic polymer absorption bands in different operation regimes of the spectrometer. The theoretical multiplex advantage of 8 was experimentally verified by comparison of the noise behavior of the spectral coding approach and a standard line-scan approach.
ARTICLE | doi:10.20944/preprints201709.0099.v1
Subject: Biology And Life Sciences, Forestry Keywords: near-infrared spectroscopy; multivariate analysis; partial least-squares regression; floor litter; optimal wavelength selection
Online: 21 September 2017 (04:36:21 CEST)
Near-infrared spectroscopy (NIRS) was implemented to monitor the moisture content of broadleaf litters. Partial least-squares regression (PLSR) models, incorporating optimal wavelength selection techniques, have been proposed to better predict the litter moisture of forest floor. Three broadleaf litters were used to sample the reflection spectra corresponding the different degrees of litter moisture. Maximum normalization preprocessing technique was successfully applied to remove unwanted noise from the reflectance spectra of litters. Four variable selection methods were also employed to extract the optimal subset of measured spectra for establishing the best prediction model. The results showed that the PLSR model with the peak of beta coefficients method was the best predictor among all candidate models. The proposed NIRS procedure is thought to be a suitable technique for on-the-spot evaluation of litter moisture.
ARTICLE | doi:10.20944/preprints201807.0433.v1
Subject: Biology And Life Sciences, Plant Sciences Keywords: Near infrared reflectance spectroscopy; Camellia seeds kernel; Oil content; Moisture content
Online: 23 July 2018 (21:12:39 CEST)
A fast and effective determination method of different species of vegetable seeds oil is vital in the plant oil industry. The near-infrared reflectance spectroscopy (NIRS) method was developed in this study to massively analyze the oil and moisture contents of Camellia gauchowensis Chang and C. semiserrata Chi seeds kernels. In the prediction models of NIRS, the levels of accuracy obtained were sufficient for C. gauchowensis Chang and C. semiserrata Chi, the correlation coefficient of which oil were 0.983 and 0.962, respectively, while which of moisture were 0.937 and 0.907, respectively. The near infrared spectrum of crush seeds kernels was more precise compared to intact kernels. Based on the calibration models of the two Camellia species, the NIRS predictive oil contents of C. gauchowensis Chang and C. semiserrata Chi seeds kernels were 48.71 ± 8.94% and 31.71 ± 7.39%, respectively, and the NIRS predictive moisture contents were 4.39 ± 1.08% and 3.49 ± 0.71%, respectively. Compared with the traditional chemical measurement, the rapid, precise measurement of oil and moisture of C. gauchowensis Chang and C. semiserrata Chi seeds kernels can be actualized by NIRS method.
ARTICLE | doi:10.20944/preprints202306.0811.v1
Subject: Engineering, Bioengineering Keywords: Higher heating value; Ultimate analysis; Spectral multi-preprocessing method; Near-infrared spectroscopy; Partial least squares regression
Online: 12 June 2023 (09:27:45 CEST)
In this study, the partial least squares regression (PLSR) models were developed using no pre-processing, traditional preprocessing, multi-preprocessing 5 range, multi-preprocessing 3 range, genetic algorithm (GA), and successive projection algorithm (SPA) to assess the higher heating value (HHV) and ultimate analysis of grounded biomass for energy usage employing near-infrared (NIR) spectroscopy. A novel approach was utilized based on the assumption that using multiple pretreatment methods across different sections in the entire NIR wavenumber range would enhance the performance of the model. The performance of the model obtained from 200 biomass samples for HHV and 120 samples for ultimate analysis was compared, and the best model was selected based on the coefficient of determination of validation set, root mean square error of prediction, and the ratio of prediction to deviation values. Based on model performance results, the proposed HHV model from GA-PLSR, and the N and O models from the mul-ti-preprocessing PLSR 5 range method could be used for most applications, including research, whereas the C and H models from GA-PLSR performance is fair and applicable only for rough screening. The overall findings highlight that the multi-preprocessing 5-range method, which was attempted as a novel approach in this study to develop the PLSR model, demonstrated better accuracy for HHV, C, N, and O, improving by 4.1839%, 8.1842%, 3.7587%, and 35.9404%, respec-tively. Therefore, it can be considered a reliable and non-destructive alternative method for rap-idly assessing biomass properties for energy usage and can also be used effectively in biomass trading. However, due to the smaller number of samples used in the model development, more samples are needed to update the model for a robust application.
ARTICLE | doi:10.20944/preprints202312.0295.v1
Subject: Engineering, Energy And Fuel Technology Keywords: biomass; ultimate analysis; near-infrared spectroscopy; partial least squares regression; wood; non-wood; scatter plot analysis
Online: 6 December 2023 (09:45:02 CET)
The ultimate analysis parameters including carbon (C), hydrogen (H), nitrogen (N), and oxygen (O) content in biomass was rarely found to be predicted by nondestructive tests until to date. In this research, we developed partial least squares regression (PLSR) models to predict the ultimate analysis parameters of chip biomass using near infrared (NIR) raw spectra of non-wood and wood samples from fast growing tree and agricultural residue and nine different traditional spectral preprocessing techniques. These techniques include first derivative (sd1), second derivative (sd2), constant offset, standard normal variate (SNV), multiplicative scatter correction (MSC), vector normalization, min-max normalization, mean centering, sd1 + vector normalization, and sd1 + MSC. Additionally, we employed a genetic algorithm (GA), successive projection algorithm (SPA), multi-preprocessing (MP) 5−range, and MP 3−range to develop a PLSR model for rapid prediction. A dataset consisting of 120 chip biomass samples was utilized for model development in which the samples was non-wood samples of 65-67% and wood samples was 33-35%, and the model performance were evaluated and compared. The selection of the optimum performing model was mainly based on criteria such as the coefficient of determination in the prediction set (R2P), root mean square error of the prediction set (RMSEP), and the ratio of prediction to deviation values (RPD). The optimal model for weight percentage (wt.%) of C was obtained using GA−PLSR, yielding R2P, RMSEP, and RPD values of 0.6954, 1.1252 wt.%, and 1.8, respectively. Similarly, for wt.% of O, the most effective model was obtained using the multi-preprocessing PLSR−5 range method with R2P of 0.7150, RMSEP of 1.3088 wt.%, and RPD of 1.9. For wt.% of N, the optimal model was obtained using the MP PLSR−3 range method, resulting in R2P, RMSEP, and RPD values of 0.6073, 0.1008 wt.%, and 1.6, respectively. However, wt.% of H model provided R2P, RMSEP, and RPD values of 0.5162, 0.2322 wt.%, and 1.5, respectively. Notably, the limit of quantification (LOQ) values for C, H, and O were lower than the minimum reference values used during model development, indicating a high level of sensitivity. However, the LOQ for N, exceeded the minimum reference value, implying the samples to be predicted by the model must be in the range of reference range in calibration set. By scatter plot analysis, the effect of combined non-wood and wood spectra of biomass chips on rapid prediction of ultimate analysis parameters using NIR spectroscopy was investigated. To include different species in a model, the species have to be not only in the different values of the constituents to make a wider range for robust model but also they must provide their trend line characteristics in the scatter plot i.e. correlation coefficient (R), slope and intercept (same slope and slope approached to 1 and intercept is same (no gap) and approached zero, high R approached to 1). The effect of the R, slope and intercept to obtain the better optimized model were studied. The results show that the different species affected model performance of each parameter prediction in a different manner and by scatter plot analysis which of these species were affecting the model negatively and how the model could be improved was indicated. This is the first time of the effect is studied by the principle of scatter plot.
COMMUNICATION | doi:10.20944/preprints202309.1032.v1
Subject: Chemistry And Materials Science, Materials Science And Technology Keywords: porous silicon; quantum dots; near-infrared
Online: 15 September 2023 (11:10:30 CEST)
porous silicon-based photodetectors have attracted more researches due to their high luminous efficiency, good stability and low cost. In this paper, a PbS quantum dots/porous silicon hybrid structure has been fabricated. The PbS quantum dots (QDs) partly infiltrated into the porous silicon (PSi) layer and partly deposited on its surface, which could increase the absorption of near-infrared wavelength range and extend the light absorption in silicon for wavelengths longer than 1100 nm. After that, A metal-semiconductor-metal (MSM) device is fabricated and its response spectrum could extend to the 1200 nm at -3 V. As a silicon-based photodetector (PD), one can envision its role for operation from visible light to short-wavelength infrared range.
ARTICLE | doi:10.20944/preprints201809.0572.v1
Subject: Physical Sciences, Applied Physics Keywords: silicon; near-infrared; photodetectors, internal photoemission; erbium.
Online: 28 September 2018 (16:14:09 CEST)
This paper presents the design, fabrication and characterization of Schottky erbium/silicon photodetectors working at 1.55 µm. These erbium/silicon junctions are carefully characterized using both electric and optical measurements at room temperature. A Schottky barrier ΦB of ~673 meV is extrapolated; the photodetectors show external responsivity of 0.55 mA/W at room temperature under a 8 V of reverse bias applied. In addition, the device performance is discussed in terms of normalized noise and noise equivalent power. To the best of our knowledge, these are the first Er/Si photodetectors designed for operation in free space at 1.55 µm. The proposed devices will pave the way towards development of Er-based photodetectors and light sources to be monolithically integrated in the same silicon substrate and both operating at 1.55 µm.
ARTICLE | doi:10.20944/preprints201810.0546.v1
Subject: Engineering, Electrical And Electronic Engineering Keywords: mid-infrared light sources; near-infrared light sources; rare earth-doped fibers
Online: 23 October 2018 (16:32:22 CEST)
Modeling and design of fiber lasers facilitate the process of their practical realization. Of particular interest during the last few years is the development of lanthanide ion-doped fiber lasers which operate at wavelengths exceeding 2000 nm. There are two main host glass materials considered for this purpose, namely fluoride and chalcogenide glasses. Therefore, this study concerns comparative modeling of fiber lasers operating within the infrared wavelength region beyond 2000 nm. In particular, the convergence properties of selected algorithms, implemented within various software environments, are studied with a specific focus on the central processing unit (CPU) time and calculation residual. Two representative fiber laser cavities are considered: one is based on a chalcogenide-selenide glass step-index fiber doped with trivalent dysprosium ions whilst the other is a fluoride step-index fiber doped with trivalent erbium ions. The practical calculation accuracy is also assessed by comparing directly the results obtained from the different models.
ARTICLE | doi:10.20944/preprints201809.0432.v1
Subject: Chemistry And Materials Science, Food Chemistry Keywords: infrared spectroscopy; diffuse reflectance infrared Fourier transform spectroscopy; ion-exchange resin; drinking water
Online: 21 September 2018 (08:29:11 CEST)
Infrared spectroscopy is an effective method for the determination of compositions and concentrations of liquids, with advantages of fast response, no-sampling, flexible in use and is able for on-line monitoring. However, for trace substances in drinking water, such as nitrates and heavy metals, infrared spectroscopy is not sensitive enough for the quantitative and qualitative measurement. In this study, we improved the sensitivity of infrared spectroscopy for nitrite determination by developing an ion-exchange-enhanced diffuse reflectance spectroscopy, which consist of an accessory based on ion-exchange resin for enrichment and a FTIR spectrometer for measurement. Using this method, the limit of detection for nitrate is 1.7 mg/L, which is enough for drinking water sensing. We also verified the quantitative measurement ability of the method. Furthermore, the limit of detection and quantitative measuring range could be adjusted by changing the mass of resin and adsorption time. This study demonstrated the method can be used to detect trace nitrites in drinking water, can be applied in the field, and is sensitive, rapid, and inexpensive with a wide dynamic range.
ARTICLE | doi:10.20944/preprints202106.0630.v1
Subject: Medicine And Pharmacology, Immunology And Allergy Keywords: Exercise; Runners; Near-infrared spectroscopy; Respiratory muscles; Respiration.
Online: 28 June 2021 (09:44:55 CEST)
The study aimed to evaluate the association between the changes in ventilatory variables (tidal volume (Vt), respiratory rate (RR), and lung ventilation (VE)) and deoxygenation of m.intescostales (∆SmO2-m.intercostales) during a maximal incremental exercise in nineteen male competitive marathon runners. The ventilatory variables and oxygen-consumption (VO2) were recorded breath-by-breath by exhaled gas analysis. A near-infrared spectroscopy device (MOXY) located in the right-hemithorax allowed recording SmO2-m.intercostales. To explore changes in oxygen levels in muscles with high demand during exercise, a second MOXY records SmO2-m.vastus laterallis. The triphasic model of exercise intensity was used for evaluating changes in SmO2 in both muscle groups. We found that ∆SmO2-m.intercostales correlated with VO2-peak (r=0.65; p=0.002) and the increase of VE (r=0.78; p=0.001), RR (r=0.54; p=0.001), but not Vt (p=0.210). The interaction of factors (muscles X exercise-phases) in SmO2 expressed as an arbitrary unit (a.u) was significant (p=0.005). At VT1 were no difference (p=0.177), but SmO2-m.intercostales was higher at VT1 (p<0.001) and VO2-peak (p<0.001). In competitive marathon runners, the m.intercostales deoxygenation during incremental exercise is directly associated with the aerobic capacity and increased lung ventilation and respiratory rate, but not tidal volume. Besides, it shows less deoxygenation than m.vastus laterallis at intensities above the aerobic ventilatory threshold.
Subject: Physical Sciences, Acoustics Keywords: graphene; silicon; photodetectors; internal photoemission effect; near-infrared
Online: 5 March 2021 (10:49:26 CET)
In this work we theoretically investigate the responsivity/noise equivalent power (NEP) trade-off in graphene/semiconductor Schottky photodetectors (PDs) operating in the near-infrared regime and working at room temperature. Our analysis shows as the responsivity/NEP ratio is strongly dependent on the Schottky barrier height (SBH) of the junction and we derive a closed analytical formula for maximizing it. In addition, we theoretically discuss as the SBH is linked to the bias applied to the junction in order to show how these devices could be optimized in practice for different semiconductors. We discover that graphene/n-silicon (Si) Schottky PDs could be optimized at 1550nm showing a responsivity and NEP of 133mA/W and 500fW/Hz, respectively, by a low reverse bias of only 0.66V. Moreover, we show that graphene/n-germanium (Ge) Schottky PDs optimized in term of responsivity/NEP ratio could be employed at 2000nm with a responsivity and NEP of 233mA/W and 31pW/Hz, respectively. We believe that our insights are of great importance in the field of silicon photonics for the realization of Si-based PDs to be employed in power monitoring, lab-on-chip and environment monitoring applications.
ARTICLE | doi:10.20944/preprints202207.0060.v1
Subject: Physical Sciences, Optics And Photonics Keywords: perfect absorber; ultra-broadband; visible region; near infrared region
Online: 5 July 2022 (05:15:18 CEST)
As solar energy is a low-cost and clean energy source, there has been a great deal of interest in how to harvest it. To absorb solar energy efficiently, we have designed a broadband metamaterial absorber based on the principle of Fabry–Pérot (FP) cavity and surface plasmon resonances (SPRs). We propose a broadband perfect absorber consisting of a four-layer structure of silica-tungsten-silica-titanium (SiO2-W-SiO2-Ti) for the incident light wavelength range of 300–2500 nm. The structure achieves perfect absorption of incident light in the wavelength range of 351.8–2465.0 nm (absorption >90%), with an average absorption of 96.3%. The advantage of our proposed structure is that it combines the characteristics of both high and broadband absorption and has a high overall absorption efficiency for solar radiation. It is also independent of polarization and insensitive to incident angle. We investigated how absorption was affected by different structures, materials, geometrical parameters, and refractive indices for different dielectric materials, and we explored the reasons for high absorption. This structure is refractory and ultra-thin, and it offers a good trade-off between bandwidth and absorption. It therefore has premium application prospects and value.
COMMUNICATION | doi:10.20944/preprints201809.0589.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: squaraine dye; near infrared; fluorescence; chloroquine; malaria; Plasmodium falciparium
Online: 29 September 2018 (10:15:33 CEST)
Chloroquine was among the first of several effective drug treatments against malaria until the onset of chloroquine resistance. In light of diminished clinical efficacy of chloroquine as an antimalarial therapeutic, there is potential in efforts to adapt chloroquine for other clinical applications, such as in combination therapies and in diagnostics. In this context, we designed and synthesized a novel asymmetrical squaraine dye coupled with chloroquine (SQR1-CQ). In this study, SQR1-CQ was used to label live Plasmodium falciparum (P. falciparum) parasite cultures of varying sensitivities towards chloroquine. SQR1-CQ positively stained ring, mature trophozoite and schizont stages of both chloroquine–sensitive and chloroquine–resistant P. falciparum strains. In addition, SQR1-CQ exhibited significantly higher fluorescence, when compared to a chloroquine-BODIPY (borondipyrromethene) conjugate. We also achieved successful SQR1-CQ labelling of P. falciparum directly on thin blood smear preparations. Drug efficacy experiments measuring half-maximal inhibitory concentration (IC50) showed lower concentration of effective inhibition against resistant strain K1 by SQR1-CQ compared to conventional chloroquine. Taken together, the versatile and highly fluorescent labelling capability of SQR1-CQ and promising preliminary IC50 findings potentiates it to be further developed as a promising diagnostic bioimaging tool with drug efficacy against chloroquine-resistant P. falciparum.
ARTICLE | doi:10.20944/preprints201703.0054.v1
Subject: Physical Sciences, Applied Physics Keywords: plasmonics; infrared detector; MEMS; gas sensing
Online: 10 March 2017 (10:21:40 CET)
A lead zirconate titanate [PZT;Pb(Zr0.52Ti0.48)O3] layer embedded infrared (IR) detector decorated with wavelength-selective plasmonic crystals has been investigated for high-performance non-dispersive infrared (NDIR) spectroscopy. A plasmonic IR detector with an enhanced IR absorption band has been designed based on numerical simulations, fabricated by conventional microfabrication techniques, and characterized with a broadly tunable quantum cascade laser. The enhanced responsivity of the plasmonic IR detector at specific wavelength band has improved the performance of NDIR spectroscopy and pushed the limit of detection (LOD) by an order of magnitude. In this paper, a 13 fold enhancement in the LOD of a methane gas sensing using NDIR spectroscopy is demonstrated with the plasmonic IR detector.
COMMUNICATION | doi:10.20944/preprints202304.0213.v1
Subject: Medicine And Pharmacology, Surgery Keywords: indocyanine green; icg; near infrared light; liver; surgery; colorectal metastasis
Online: 11 April 2023 (08:33:57 CEST)
Introduction: Successful R0 resection is crucial for the survival of patients with primary liver cancer (PLC) or liver metastases. Up to date, surgical resection lacks a sensitive, real-time intraoperative imaging modality to determine R0 resection. Real-time intraoperative visualization with near-infrared light fluorescence (NIRF) using indocyanine green (ICG) may have the potential to meet this demand. This study evaluates the value of ICG visualization in PLC and liver metastases surgery regarding R0 resection rates. Materials and Methods Patients with PLC or liver metastases were included in this prospective cohort study. ICG 10mg was administered intravenously 24 hours before surgery. Real-time intraoperative NIRF visualization was made with the SpectrumTM Fluorescence Imaging Camera System. First, all liver segments were inspected with the fluorescence imaging system and intraoperative ultrasound for identification of the known tumor as well as additional lesions, compared to preoperative MRI. PLC, liver metastases, and additional lesions were then resected according to oncological principles. Of all resected specimens the resection margins were analyzed with the fluorescence imaging system for ICG positive spots right after resection. Histology of additional detected lesions as well as ICG fluorescence compared to histological resection margins were assessed. Results Of the 66 included patients median age was 65.5 years (IQR 58.7 - 73.9), 27 (40.9%) were female and 18 (27.3%) were operated laparoscopically. Additional ICG positive lesions were detected in 23 (35.4%) patients of which nine (29%) were malignant. In patients with no fluorescent signal at the resection margin, R0 rate was 93.9%, R1 rate was 6.1%, and R2 rate was 0% compared to a ICG positive resection margin with a R0 rate of 64.3%, R1 rate of 21.4%, and R2 rate of 14.3% (p=0.005). One and two year overall survival were 95.2% and 88.4%, respectively. Conclusion The here presented study provides significant evidence that ICG NIRF guidance helps to identify R0 resection intraoperatively. This offers a true potential to verify radical resection and improve patients´ outcome. Furthermore, implementation of NIRF guided imaging in liver tumor surgery allows to detect a considerable amount of additional malignant lesions.
ARTICLE | doi:10.20944/preprints202212.0187.v1
Subject: Medicine And Pharmacology, Other Keywords: near-infrared; spectroscopy; tissue; medical imaging; diffuse optical tomography; fNIRS
Online: 12 December 2022 (03:26:45 CET)
The optical properties and physiology of biological tissue, as well as how near-infrared (NIR) light interacts with the tissue, both play a significant role in interpreting the tissue probing optical measurements, and in solving the inverse problem of near-infrared spectroscopy (NIRS)-based medical imaging modalities such as diffuse optical tomography and functional near-infrared spectroscopy. This paper discusses the optical properties of tissue, specifically in the NIR wavelength range, which influence NIRS measurements in NIRS-based medical imaging. There is an easy-to-understand explanation given in this paper of the NIR light-tissue interaction phenomenon. The mathematical explanation, the processes involved in the interaction, and the rationale for a few approximations are described. Various types of chromophores present in the tissue, their composition in the tissue, and how these chromophores overall affect the scattering and absorption of NIR light are presented. The absorption spectra of these chromophores are shown. Finally, the paper concludes with the author’s perspective on two NIRS-based medical imaging modalities, diffuse optical tomography, and functional near-infrared spectroscopy.
ARTICLE | doi:10.20944/preprints202102.0414.v1
Subject: Physical Sciences, Optics And Photonics Keywords: Skin hydration; Optical sensor; near infrared spectroscopy; Monte Carlo Simulation
Online: 18 February 2021 (12:07:29 CET)
Dermal water content is an important biophysical parameter in preserving skin integrity and preventing skin damage. Traditional electrical-based and open-chamber evaporimeters have several well-known limitations. In particular, such devices are costly, sizeable, and only provide arbitrary outputs. They also do not permit continuous and non-invasive monitoring of dermal water content, which can be beneficial for various consumer, clinical and cosmetic purposes. We report here on the design and development of a digital multi-wavelength optical sensor that performs continuous and non-invasive measurement of dermal water content. In-silico investigation on porcine skin was carried out using the Monte Carlo modelling strategy to evaluate the feasibility and characterise the sensor. Subsequently, an in-vitro experiment was carried out to evaluate the performance of the sensor and benchmark its accuracy against a high-end, broad band spectrophotometer. Reference measurements were made against gravimetric analysis. The results demonstrate that the developed sensor can deliver accurate, continuous, and non-invasive measurement of skin hydration through measurement of dermal water content. Remarkably, the novel design of the sensor exceeded the performance of the high-end spectrophotometer due to the important denoising effects of temporal averaging. The authors believe, in addition to wellbeing and skin health monitoring, the designed sensor can particularly facilitate disease management in patients presenting diabetes mellitus, hypothyroidism, malnutrition, and atopic dermatitis.
ARTICLE | doi:10.20944/preprints202308.0324.v1
Subject: Chemistry And Materials Science, Biomaterials Keywords: Golgi apparatus; carbon nanodots; polymer dots; Near infrared fluorescence; High photostability
Online: 4 August 2023 (11:11:48 CEST)
As an important organelle in eukaryotic cells, Golgi apparatus is responsible for processing and transporting proteins and lipids in cells. Precise monitoring the status of Golgi apparatus by targeting fluorescence imaging technology is of enormous importance but remains an attractive yet dramatically challenging task. In this study, we report the construction of the first Golgi apparatus targeted sensor with bright near-infrared fluorescence, termed as Golgi-Pdots. As a start point of our investigation, hydrophobic CDs with bright NIR fluorescence at 674 nm (fluorescence quantum yield : 12.18%), narrow emission band of 23 nm, and excellent stability were facilely prepared from Magnolia Denudata flowers through an ultrasonic method. Incorporating the CDs into a polymer matrix modified with Golgi-targeting molecules can produce the water-soluble Golgi-Pdots, which showed high colloidal stability and similar optical properties as compared to CDs. Further studies revealed that the Golgi-Pdots showed good biocompatibility and Golgi-targeting ability. Based on these fascinating properties, Golgi-Pdots have been successfully used for long term bioimaging of Golgi apparatus inside live cells.
ARTICLE | doi:10.20944/preprints202212.0239.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: plasmonics; plasmonics photodetector; focused ion beam; silicon photodiode; near-infrared; LiDar.)
Online: 13 December 2022 (11:01:47 CET)
Recently, the interest in silicon-based detectors capable of detecting single photons in the near-infrared is growing mainly due to LiDAR applications, autonomous driving in particular. Silicon single-photon avalanche diodes are one of the most interesting single-photon NIR technology available on the market, nevertheless, their efficiency is hindered by the low absorption coefficient of Si in the NIR. The idea is the integration of CMOS-compatible nanostructures, specifically, silver grating array supporting Surface Plasmons Polaritons (SPPs), to confine superficially the incoming NIR photons and therefore increase photons probability to generate an electron-hole pair. The plasmonic silver array is geometrically fine-tuned using time domain simulation software to achieve maximum detector performance at 950 nm. Then, the plasmonic silver array is integrated by means of the focused ion beam technique on the detector. Finally, the integrated detector is electro-optically characterized, demonstrating a quantum efficiency of 13 at 950 nm, 2,2 times more than the reference detector. This result suggests the production of a device capable of detecting single NIR photons, at a very low cost and compatible with CMOS, thus integrable on existing technology platforms.
ARTICLE | doi:10.20944/preprints202103.0599.v1
Subject: Physical Sciences, Acoustics Keywords: upconversion nanoparticles; near-infrared-II; excitation mechanisms; luminescence quenching; microscopic imaging
Online: 24 March 2021 (16:18:36 CET)
Lanthanide-doped upconversion nanoparticles (UCNPs) are promising bioimaging nanoprobes due to their excellent photostability. As one of the most commonly-used lanthanide activators, Tm3+ ions have perfect ladder-type electron configuration and can be directly excited by bio-friendly near-infrared-II (NIR-II) wavelengths. Here, the emission characteristics of Tm3+-doped nanoparticles under laser excitations of different near-infrared-II wavelengths were systematically investigated. The 1064 nm, 1150 nm and 1208 nm lasers are proposed to be three excitation strategies with different response spectra of Tm3+ ions. Particularly we found that 1150 nm laser excitation enables intense three-photon 475 nm emission, which is nearly 100 times stronger than that excited by 1064 nm excitation. We further optimized the luminescence brightness after investigating the luminescence quenching mechanism of bare NaYF4:Tm (1.75%) core. After growing inert shell, ten-fold increase of emission intensity was achieved. Combining the advantages of NIR-II wavelength and the higher-order nonlinear excitation, a promising facile excitation strategy was developed for the application of thulium-doped upconversion nanoparticles in single nanoparticle imaging and cancer cell microscopic imaging.
REVIEW | doi:10.20944/preprints201906.0306.v1
Subject: Physical Sciences, Applied Physics Keywords: silicon; graphene; internal photoemission; field-effect transistor; photodetector; near-infrared; waveguide
Online: 29 June 2019 (10:41:17 CEST)
In recent years graphene has attracted much interest due to its unique properties of flexibility, strong light-matter interaction, high carrier mobility and broadband absorption. In addition, graphene can be deposited on many substrates including silicon with which is able to form Schottky junctions opening the path to the realization of near-infrared silicon photodetectors based on the internal photoemission effect where graphene play the role of the metal. In this work, we review the very recent progress of the near-infrared photodetectors based on Schottky junctions involving graphene. This new family of device promises to overcome the limitations of the Schottky photodetectors based on metals showing the potentialities to compare favorably with germanium photodetectors currently employed in silicon photonics.
REVIEW | doi:10.20944/preprints201808.0295.v1
Subject: Medicine And Pharmacology, Pediatrics, Perinatology And Child Health Keywords: NICU; Physio-features; Neonatal imaging; Infrared thermography; Optical coherence tomography; Tissue optics; Near-infrared imaging; Short-wave infrared imaging; Visible light imaging
Online: 17 August 2018 (02:27:17 CEST)
The monitoring of sick newborns is a challenging task that health care providers in Neonatal Intensive Care Units (NICU) must contend with each day. Conventionally, newborns are monitored via probes that are affixed to their skin and attached to processing monitors (Fig.1). However, an alternative exists in contactless imaging to record such physiological signals (Physio-Markers), surface changes and internal structures which can be used independently of, or in conjunction with conventional monitors. Advantages of contactless monitoring methods include: i) quick data generation; ii) lack of contact with skin, which reduces skin breakdown and decreases risk of infection; and iii) minimizing the number of probes and monitors affixed to the skin, which allows greater body surface-area for other care. This paper is an attempt to build a foundation for and to provide a vision of the potential neonatal clinical applications of technologies that use non-contact modalities such as Visible Light Imaging (VLI), Near InfraRed Spectrum (NIRS), and Thermal Imaging (TI) using InfraRed Spectrum (IRS).
ARTICLE | doi:10.20944/preprints202309.0785.v1
Subject: Computer Science And Mathematics, Artificial Intelligence And Machine Learning Keywords: Nondestructive Instrumentation; Near-Infrared Spectrometry; parameter estimation; optimization algorithm; Fuzzy-Cognitive-Maps
Online: 15 September 2023 (03:49:29 CEST)
The flour milling industry, a vital component of global food production, is undergoing a transformative phase driven by the integration of smart devices and advanced technologies. This transition promises improved efficiency, quality, and sustainability in flour production. Accurate estimation of protein, moisture and ash content in wheat grains and flour is of paramount importance due to their direct impact on product quality and compliance with industry standards. This paper explores the application of Near-Infrared (NIR) spectroscopy as a non-destructive, efficient, and cost-effective method for measuring the aforementioned essential parameters in wheat and flour, by investigating the effectiveness of a low-cost handle NIR spectrometer. Furthermore, a novel approach using Fuzzy Cognitive Maps (FCMs) is proposed to estimate protein, moisture and ash content in grain seeds and flour, marking the first known application of FCMs in this context. Our study includes an experimental setup that assesses different types of wheat seeds and flour samples and evaluates three NIR pre-processing techniques to enhance parameter estimation accuracy. The results indicate that low-cost NIR equipment can contribute to the estimation of the under-study parameters.
ARTICLE | doi:10.20944/preprints202307.0624.v1
Subject: Engineering, Electrical And Electronic Engineering Keywords: Agrifood quality control; Digital Micromirror Device (DMD); Forage; Near-Infrared Spectroscopy (NIRS).
Online: 10 July 2023 (11:35:24 CEST)
Food safety and quality are the first steps in the food chain. This work reports a low-cost and easy-to-use optoelectronic measurement system for improving feed chain quality and safety, based on near-infrared spectrometry (NIRS) technology. This is a significant challenge for dairy farm technicians and producers who need rapid and reliable knowledge of forage quality on their farms. In most cases, instrumentation suitable for these specifications is expensive and difficult to operate. The core of the measurement system is Texas Instruments´ NIRscan Nano Evaluation Module (EVM) spectrometer. This module has a large sensing area and high resolution suitable for forage samples. To evaluate the feasibility of the prototype to analyze agrifood samples, different ways of presenting the sample, intact or ground, were tested. The final objective of the research is not just to check the efficiency of the proposed system. It is also to determine the measurement system characteristics and how to improve them.
ARTICLE | doi:10.20944/preprints202307.0481.v1
Subject: Medicine And Pharmacology, Emergency Medicine Keywords: out-of-hospital cardiac arrest; physiological monitoring; blood pressure; near-infrared spectroscopy
Online: 7 July 2023 (09:44:44 CEST)
Background: In recent years, the assessment and guidance of cardiopulmonary resuscitation (CPR) quality using noninvasive and invasive monitoring techniques have been increasingly recommended. In this study, we introduce a new physiological monitoring system that simultaneously measures arterial pressure (AP), venous pressure (VP), and cerebral tissue oxygen saturation (SctO2) during CPR. Methods: This prospective observational study was conducted at a single center (Kagoshima City Hospital). Adult out-of-hospital patients aged ≥18 years with an intravenous femoral arterial line, venous line, and SctO2 monitor were included. We measured femoral arterial pressure (FAP) and femoral venous pressure (FVP) invasively if catheters were immediately inserted into the femoral artery and vein for potential candidates who require interventions such as extracorporeal cardiopulmonary resuscitation but did not receive such interventions as a result. Results: We observed several representative cases that provided the following insights: We presented several cases, including two patients with significant increases in FVP and low SctO2 values, and in both cases, return of spontaneous circulation (ROSC) was not achieved. In contrast, we also presented two cases in which CPR resulted in higher FAP compared to FVP and an upward trend in SctO2 values was observed, and both instances achieved ROSC. Conclusion: We presented a simultaneous physiological monitoring system that can monitor AP, VP, and SctO2 during CPR. Further case accumulations will be necessary to assess the variations in hemodynamic status during CPR and the association between each hemodynamic status and outcomes after cardiac arrest.
ARTICLE | doi:10.20944/preprints202305.2080.v1
Subject: Engineering, Bioengineering Keywords: hypoxic-ischemic encephalopathy; electroencephalogram; near-infrared spectroscopy; neurovascular coupling; experimental modal analysis
Online: 30 May 2023 (08:12:44 CEST)
Hypoxic-ischemic encephalopathy (HIE) secondary to perinatal asphyxia occurs when the brain does not receive enough oxygen and blood. A surrogate marker for ‘intact survival’ is necessary for the successful management of HIE. The severity of HIE can be classified based on clinical presentation, including presence of seizures, using a clinical classification scale called Sarnat staging; however, Sarnat staging is subjective and the score changes over time. Furthermore, seizures are difficult to detect clinically and are associated with a poor prognosis. Therefore, a tool for continuous monitoring on the cot side is necessary, for example, electroencephalogram (EEG) that non-invasively measures the electrical activity of the brain from the scalp. Then, multimodal brain imaging, when combined with functional near-infrared spectroscopy (fNIRS), can capture the neurovascular coupling (NVC) status. In this study, we first tested the feasibility of a low-cost EEG-fNIRS imaging system to differentiate between normal, hypoxic, and ictal states in a perinatal ovine hypoxia model. Here, the objective was to evaluate a portable cot side device and autoregressive (ARX) modelling to capture the perinatal ovine brain states during a simulated HIE injury. So, ARX parameters were tested with a linear classifier using a single differential channel EEG, with varying states of tissue oxygenation detected using fNIRS, to label simulated HIE states in a perinatal ovine hypoxia model. Then, we showed the technical feasibility of the low-cost EEG-fNIRS device and ARX modeling with support vector machine classification for a human HIE case series with and without sepsis. The classifier trained with the ovine hypoxia data labelled ten severe HIE human cases (with and without sepsis) as “hypoxia” group and the four moderate HIE human cases as the “control” group. Furthermore, we showed the feasibility of experimental modal analysis (EMA) based on the ARX model to investigate the NVC dynamics using EEG-fNIRS joint-imaging data that differentiated six severe HIE human cases without sepsis from four severe HIE human cases with sepsis. In conclusion, our study showed the technical feasibility of EEG-fNIRS imaging, ARX modeling of NVC for HIE classification, and EMA that may provide a biomarker to detect sepsis effects on the NVC in HIE.
CONCEPT PAPER | doi:10.20944/preprints202212.0373.v1
Subject: Physical Sciences, Applied Physics Keywords: Diffuse Optical Tomography, Near-infrared, Inverse problem, Spectroscopy, Medical Imaging, fNIRS, Tissue
Online: 21 December 2022 (02:21:42 CET)
Diffuse optical tomography (DOT) is an optical medical imaging method that can assess the structural properties of tissues and their functional characteristics, such as hemoglobin concentration, water content, as well as lipid concentration, via three-dimensional image reconstruction. This paper presents the theoretical basis and working principle of diffuse optical tomography. The paper explains how the optical properties of tissue can be imaged by photon migration techniques based on diffusion theory. The author presents the reasoning for near-infrared (NIR) imaging as the most effective technique in terms of quantitative recovery of spectroscopic optical parameters. This work also listed various advantages, applications, and challenges of DOT. The paper also briefly discusses current progress in near-infrared medical imaging and its future direction.
Subject: Chemistry And Materials Science, Medicinal Chemistry Keywords: high-frequency near-infrared diode laser; osteoarthritis; inflammation; matrix metalloproteinase; human chondrocyte
Online: 9 January 2020 (12:22:18 CET)
High-frequency near-infrared diode laser provides high peak output, low heat accumulation, and efficient biostimulation. Although these characteristics are considered suitable for osteoarthritis (OA) treatment, the effect of high-frequency near-infrared diode laser in in vitro or in vivo OA models has not yet been reported. Therefore, we aimed to assess the biological effects of high-frequency near-infrared diode laser irradiation on IL-1β-induced chondrocyte inflammation in an in vitro OA model. Normal Human Articular Chondrocyte-Knee (NHAC-Kn) cells were stimulated with human recombinant IL-1β and irradiated with high-frequency near-infrared diode laser (910 nm, 4 or 8 J/cm2). The mRNA and protein expression of relevant inflammation- and cartilage destruction-related proteins was analyzed. IL-1β treatment significantly increased the mRNA levels of IL-1β, IL-6, TNF-α, MMP-1, MMP-3, and MMP-13. High-frequency near-infrared diode laser irradiation significantly reduced the IL-1β-induced expression of IL-1β, IL-6, TNF-α, MMP-1, and MMP-3. Similarly, high-frequency near-infrared diode laser irradiation decreased the IL-1β-induced increase in protein expression and secreted levels of MMP-1 and MMP-3. These results highlight the therapeutic potential of high-frequency near-infrared diode laser in OA.
ARTICLE | doi:10.20944/preprints202304.0730.v1
Subject: Physical Sciences, Optics And Photonics Keywords: Near infrared emission; Aza-Bodipy derivatives; Saturable absorption; Nonlinear refraction; Two-photon absorption
Online: 23 April 2023 (02:41:33 CEST)
The near-infrared (NIR) organic dyes with strong ultrafast nonlinear optical (NLO) activities are of importance for various applications. However, such kinds of dyes are still scarce. In this work, we have compared the NLO properties of two NIR Aza-BODIPY derivatives, in which the strong electron-donating groups, namely 4-(N, N-dimethylamino) phenyl and 1-ethyl-1,2,3,4-tetrahydroquinoline groups, are connected with the cores of Aza-BODIPY. Z-Scan experimental results show that two Aza-BODIPY derivatives exhibit strong saturation absorption and large modulation depth under the excitation of femtosecond pulses at 800 nm. Under 1300 nm excitation, two derivatives exhibit strong nonlinear refraction. In addition, the Aza-BODIPY derivatives also display effective two-photon excited fluorescence emission in the wavelength range of 1200-1600 nm. Based on the experimental results, it is found that 1-ethyl-1,2,3,4-tetrahydroquinoline group can more effectively enhance the NLO properties of Aza-BODIPY derivatives compared with the 4-(N, N-dimethylamino) phenyl group, thus providing new possibilities for the design and development of NIR NLO materials.
ARTICLE | doi:10.20944/preprints202208.0123.v1
Subject: Medicine And Pharmacology, Neuroscience And Neurology Keywords: systems analysis; model predictive control; transcranial electrical stimulation; functional near infrared spectroscopy; pupillometry
Online: 5 August 2022 (14:26:00 CEST)
Individual differences in the responsiveness of the brain to transcranial electrical stimulation (tES) is increasingly demonstrated in large variability in the tES effects. Anatomically detailed computational brain models have been developed to address this variability; however, static brain models are not ‘realistic’ in accounting for the dynamic state of the brain. Therefore, human-in-the-loop optimization is proposed in this perspective article based on an extensive systems analysis of the tES neurovascular effects. First, modal analysis was conducted using a physiologically detailed neurovascular model that found stable modes in the 0 Hz to 0.05 Hz range for the pathway for vessel response through the smooth muscle cells, measured with functional near-infrared spectroscopy (fNIRS). tES effects in the 0 Hz to 0.05 Hz range can also be measured with functional magnetic resonance imaging (fMRI)-tDCS data with a maximum TR=10sec. Therefore, we investigated an open-source fMRI-tDCS dataset that used a TR=3.36sec. We found that both the anodal tDCS condition and sham tDCS condition had similar Finite Impulse Response at the region of interest underlying the anode and a remote location, which indicated a global hemodynamic effect of sham tDCS beyond the intended transient sensations. Here, transient sensations can have arousal effects on the hemodynamics so we conducted a healthy case series for black box modeling of fNIRS-pupillometry of short-duration tDCS effects. The block exogeneity test rejected the claim that tDCS is not a 1-step Granger-cause of the fNIRS total hemoglobin changes (HbT) and pupil dilation changes (p<0.05). Also, grey-box modeling using fNIRS of the tDCS effects in chronic stroke showed HbT response to be significantly different (paired-sample t-test, p<0.05) between the ipsilesional and the contralesional hemisphere for primary motor cortex tDCS and cerebellar tDCS which was subserved by the smooth muscle cells. Here, our perspective is that various physiological pathways subserving tES effects can lead to state-trait variability that can be challenging for clinical translation. Therefore, we conducted a case study on human-in-the-loop optimization using our reduced dimension model and a stochastic, derivative-free Covariance Matrix Adaptation Evolution Strategy. Future studies need to investigate human-in-the-loop optimization of tES for reducing inter-subject and intra-subject variability in tES effects.
Subject: Chemistry And Materials Science, Analytical Chemistry Keywords: Peroxy radicals, near-infrared spectroscopy, Ã←X electronic transition, cavity ring down spectroscopy
Online: 21 July 2021 (16:19:16 CEST)
The absolute absorption cross section of the ethyl peroxy radical, C2H5O2, in the Ã←X ̃ electronic transition with the peak wavelength at 7596 cm-1, has been determined by the method of dual wavelengths time resolved continuous wave cavity ring down spectroscopy. C2H5O2 radicals were generated from pulsed 351 nm photolysis of C2H6/Cl2 mixture in presence of O2 and detected on one of the CRDS paths. Two methods have been applied for the determination of the C2H5O2 absorption cross section: (i) based on Cl-atoms being converted alternatively to either C2H5O2 by adding C2H6 or to hydro peroxy radicals, HO2, by adding CH3OH to the mixture, whereby HO2 was reliably quantified on the second CRDS path in the 21 vibrational overtone at 6638.2 cm-1 (ii) based on the reaction of C2H5O2 with HO2, measured under either excess HO2 or under excess C2H5O2 concentration. Both methods lead to the same peak absorption cross section of C2H5O2,7596 cm-1 = (1.0±0.2) × 10-20 cm2. The rate constant for the cross reaction between of C2H5O2 and HO2 has been measured to be (6.5±1.6) × 10-12 cm3 molecule-1 s-1.
ARTICLE | doi:10.20944/preprints202009.0047.v1
Subject: Medicine And Pharmacology, Pharmacy Keywords: silk fibroin; nanoparticles; drug loading content; quantification; infrared spectroscopy; FTIR spectroscopy.; nanotechnology; nanomedicine; drug delivery; controlled release
Online: 3 September 2020 (03:56:19 CEST)
Nanotechnology has enabled the development of novel therapeutic strategies such as targeted nanodrug delivery systems, control and stimulus-responsive release mechanisms, and the production of theranostic agents. As a prerequisite for the use of nanoparticles as drug delivery systems, the amount of loaded drug must be precisely quantified, a task for which two approaches are currently used. However, both approaches suffer from the inefficiencies of drug extraction and of the solid-liquid separation process, as well as from dilution errors. This work describes a new, reliable, and simple method for direct drug quantification in polymeric nanoparticles using attenuated total reflection Fourier transform infrared spectroscopy, which can be adapted for a wide variety of drug delivery systems. Silk fibroin nanoparticles and naringenin were used as model polymeric nanoparticle carrier and drug, respectively. The specificity, linearity, detection limit, precision and accuracy of the spectroscopic approach were determined in order to validate the method. A good linear relation was observed within 0.00 to 7.89 % of naringenin relative mass with an R2 of 0.973. The accuracy was determined by the spike and recovery method. Results showed an average 104% recovery. The limit of detection and limit of quantification of the drug loading content were determined to be 0.3 and 1.0 %, respectively. The method's robustness is demonstrated by the notable similarities between the calibrations carried out in two different equipment and institutions.
ARTICLE | doi:10.20944/preprints202202.0335.v1
Subject: Biology And Life Sciences, Agricultural Science And Agronomy Keywords: Cereals; Grain protein; Near Infrared Spectroscopy (NIRS)-based sensors; Prediction algorithms; FOSS; Hone Lab
Online: 25 February 2022 (11:21:57 CET)
Achieving global goals on sustainable nutrition, health, and wellbeing will depend on delivering enhanced diets to humankind. This will require, among others, instantaneous access to information on food quality at key points within agri-food systems. Although stationary methods are usually used to quantify grain quality (wet-lab chemistry, benchtop NIR spectrometer); these do not suit many required user-cases, such as stakeholders in decentralized agri-food-chains that are typical for emerging economies. Therefore, we explored new technologies and models that might aid these particular user-cases. For this purpose, we generated the NIR spectra of 328 grain samples from multiple cereals (finger millet, foxtail millet, maize, pearl millet, sorghum) with a standard benchtop NIR Spectrometer (DS2500, FOSS) and a novel mobile NIR-based sensor (HL-EVT5, Hone). We explored a range of classical deterministic and novel machine learning (ML)-driven models to build calibrations out of the NIR spectra. We were able to build relevant calibrations out of both types of spectra. At the same time, ML-based methods enhanced the prediction capacity of calibration models compared to classical deterministic methods. We also documented that the prediction of grain protein content based on NIR spectra generated by a mobile sensor (HL-EVT5, Hone) was highly relevant for quantitative protein predictions (R2 = 0.91, RMSE = 0.97, RPD = 3.48). Thus, the findings of this study lay the foundations on which to expand the utilization of NIR spectroscopy applications for agricultural research and development.
REVIEW | doi:10.20944/preprints202309.0726.v1
Subject: Medicine And Pharmacology, Pediatrics, Perinatology And Child Health Keywords: bronchopulmonary dysplasia; post-prematurity respiratory disease; preterm infants; noninvasive monitoring; lung oxygenation; near-infrared spectroscopy
Online: 12 September 2023 (08:49:15 CEST)
Definitions of bronchopulmonary dysplasia (BPD) or post-prematurity respiratory disease (PPRD) aim to stratify the risk of mortality and morbidity, with an emphasis on long-term respiratory outcomes. There is no univocal classification of BPD, due to its complex multifactorial nature and the substantial heterogeneity of clinical presentation. Currently, there is no definitive cure available for extremely premature very-low-birth-weight infants with BPD, and challenges in finding targeted preventive therapies persist. However, innovative stem cells-based postnatal therapies targeting BPD-free survival are emerging, which are likely to be offered in the first few days of life to higher-risk subpopulations of premature infants. Hence the need for easy-to-use noninvasive tools for a standardized, precise and reliable BPD assessment at a very early stage, to support clinical decision-making and to predict the response to treatment. In this non-systematic review, we present an overview of strategies for monitoring preterm infants with early and evolving BPD-PPRD, and make some remarks on future prospects, with a focus on near-infrared spectroscopy (NIRS).
COMMUNICATION | doi:10.20944/preprints202307.0546.v1
Subject: Engineering, Electrical And Electronic Engineering Keywords: Near-infrared photodetectors; van der Waals Schottky photodiode; Si micro-holes array; photoplethysmography; PdS QDs
Online: 10 July 2023 (05:18:29 CEST)
Near-infrared (NIR) photodetectors (PDs) have attracted much attention in noninvasive medical diagnosis and treatment. Especially, the self-filtered NIR PDs are highly demandable for tremendous biomedical application due to their strong ability in wavelength discrimination. In this work, we designed and then fabricated a Si micro-holes array/Graphene (Si MHA/Gr) van der Waals (vdW) Schottky NIR photodiode by using PbS quantum dots (QDs) coating. The device exhibits a unique self-filtered NIR response with a responsivity of 0.7 A/W at -1 V and a response time of 61 μs, which are higher than that without PbS QDs coating and even most of previous Si/Gr Schottky photodiodes. The light trapping of the Si MHA and the PbS QDs coating can be attributed to the high responsivity of the vdW photodiode. Furthermore, the presented NIR photodiode can also be integrated in photoplethysmography (PPG) for real-time heart-rate (HR) monitoring. The extracted HR is in great accord with the value measured with the patient monitor by analyzing the Fourier transform of the stable and reliable fingertip PPG waveform, suggesting its potential for practical applications.
ARTICLE | doi:10.20944/preprints202311.0770.v1
Subject: Biology And Life Sciences, Food Science And Technology Keywords: germinated brown rice; hardness; toughness; texture; near infrared spectroscopy; partial least squares regression; artificial neural network
Online: 13 November 2023 (08:57:36 CET)
The models of partial least squares (PLS) regression and artificial neural network (ANN) for evaluation of texture properties of cooked germinated brown rice (GBR) using the Fourier transform near infrared (NIR) spectra of uncooked whole grain combined with data separation methods, spectral pretreatment methods were investigated in this study. The ANN was outperformed in evaluation of hardness by back extrusion test of cooked GBR using the smoothing combined with standard normal variate pretreated NIR spectra in the range of 12,500-4,000 cm−1 of 188 whole grain samples where the calibration sample set was separated from prediction set by Kennard-Stone method where the best ANN model for hardness from hidden layers of 25 and 8 iteration time provided R2, r2, RMSEC, RMSEP, Bias and RPD of 0.9987, 0.9447, 0.1021 N, 0.7699 N, 0.0216 N and 4.3 respectively. The PLS regression of 64 sample KDML GBR group and 64 sample various variety GBR group, provided models for the hardness of the former and the toughness of the latter which developed by using 7506−5446.3, 4605.4−4242.9 cm−1 which included the amylose vibration band of 6834 cm−1 while toughness model was from 9403.8-6094.3 cm−1 where included 6834 and 8316 cm−1 vibration bands of amylose which influenced the texture of cooked rice. The PLS regression models for hardness and toughness were with the r2 of 0.85 and 0.82, and the RPD of 2.9 and 2.4, respectively. The ANN model for hardness of cooked GBR should be implemented to the practical use in GBR production factories for the quality assurance and further updating using more samples and several brands to obtain the robust models.
ARTICLE | doi:10.20944/preprints202306.0844.v1
Subject: Biology And Life Sciences, Food Science And Technology Keywords: Process integration; In-line measurement; Capacitive moisture measurement; Near-infrared spectroscopy; Fluidized bed agglomeration; Spray drying
Online: 12 June 2023 (13:36:33 CEST)
The integration of spray drying and agglomeration offers significant advantages, such us continuous production with lower energy consumption. However, it is a knife-edge process with a narrow operating window and limited degrees of freedom that decide between successful agglomeration and fluidized bed blockage due to excessive moisture. In this contribution, factors influencing the spray-through agglomeration process of skim milk powder as a model system were investigated via a design of experiments. Three in-line monitoring methods were applied and tested to observe the most important parameters in the agglomeration process: product moisture and particle size distribution. Regarding the moisture content, a capacitive moisture sensor was calibrated with linear regression and a near-infrared sensor with partial least squares regression. Near-infrared spectroscopy was found to be the suitable method for determining moisture content, while the capacitive moisture sensor mainly provides information on the bulk density, the filling level or fluidization state in the fluidized bed. Additionally, particle size distribution data was extracted from the spectral data using in-line data of a spatial filter velocimetry probe in the fluidized bed. This opens the potential to monitor both parameters in real-time with a single non-invasive sensor.
COMMUNICATION | doi:10.20944/preprints202210.0257.v1
Subject: Physical Sciences, Optics And Photonics Keywords: Phase imaging, bioimaging; synchrotron; near infrared beam; holography; incoherent optics; chemical imaging; phase retrieval; 3D imaging.
Online: 18 October 2022 (08:28:25 CEST)
Phase imaging of biochemical samples has been demonstrated for the first time at the Infrared Microspectroscopy (IRM) beamline of the Australian Synchrotron using the usually discarded Near-IR (NIR) region of the synchrotron-IR beam. The synchrotron-IR beam at the Australian Synchrotron IRM beamline has a unique fork shaped intensity distribution as a result of the gold coated extraction mirror shape, which includes a central slit for rejection of the intense X-ray beam. The resulting beam configuration makes any imaging task challenging. For intensity imaging, the fork shaped beam is usually tightly focused to a point on the sample plane followed by a pixel-by-pixel scanning approach to record the image. In this study, a pinhole was aligned with one of the lobes of the fork shaped beam and the Airy diffraction pattern was used to illuminate biochemical samples. The diffracted light from the samples was captured using a NIR sensitive lensless camera. A rapid phase-retrieval algorithm was applied to the recorded intensity distributions to reconstruct the phase information corresponding to different planes. The preliminary results are promising to develop multimodal imaging capabilities at the IRM beamline of the Australian Synchrotron.
ARTICLE | doi:10.20944/preprints202202.0090.v1
Subject: Medicine And Pharmacology, Oncology And Oncogenics Keywords: Gastroenteropancreatic neuroendocrine neoplasms; patient-derived xenograft; tumor spheroids; somatostatin receptor-2; Near infrared-labelled octreotide analog
Online: 7 February 2022 (13:12:50 CET)
Gastroenteropancreatic neuroendocrine neoplasms (GEP NENs) are rare cancers consisting of neuroendocrine carcinomas (NECs) and neuroendocrine tumors (NETs), which have been increasing in incidence in recent years. Few cell lines and pre-clinical models exist for the study of GEP NECs and NETs, limiting the ability to discover novel imaging and treatment modalities. To address this gap, we isolated tumor cells from cryopreserved patient GEP NECs and NETs and injected them into the flanks of immunocompromised mice to establish patient-derived xenograft (PDX) models. Two of 6 mice developed tumors (NEC913 and NEC1452). Over 90% of NEC913 and NEC1452 tumor cells stained positive for Ki67. NEC913 PDX tumors expressed neuroendocrine markers such as chromogranin A (CgA), synaptophysin (SYP), and somatostatin receptor-2 (SSTR2) whereas NEC1452 PDX tumors do not express SSTR2. Exome sequencing revealed loss of p53 and RB1 in both tumors. To demonstrate an application of these novel NEC PDX models for SSTR2-targeted peptide imaging, the NEC913 and NEC1452 cells were bilaterally injected into mice. Near infrared-labelled octreotide was administered and fluorescent signal was specifically observed for the NEC913 SSTR2 positive tumors. These 2 GEP NEC PDX models serve as valuable resource for GEP NEN therapy testing.
ARTICLE | doi:10.20944/preprints202201.0008.v1
Subject: Social Sciences, Behavior Sciences Keywords: functional near-infrared spectroscopy; electroencephalogram; cortico-cerebello-thalamo-cortical loop; transcranial electrical stimulation; transcranial magnetic stimulation
Online: 4 January 2022 (14:47:00 CET)
Background: Maladaptive neuroplasticity related learned response in substance use disorder (SUD) can be ameliorated using non-invasive brain stimulation (NIBS); however, inter-individual variability needs to be addressed for clinical translation. Objective: Our first objective was to develop a hypothesis for NIBS for learned response in SUD based on competing neurobehavioral decision systems model. Next objective was to conduct computational simulation of NIBS of cortico-cerebello-thalamo-cortical (CCTC) loop in cannabis use disorder (CUD) related dysfunctional “cue-reactivity” – a closely related construct of “craving” that is a core symptom. Our third objective was to test the feasibility of our neuroimaging guided rational NIBS approach in healthy humans. Methods: “Cue-reactivity” can be measured using behavioral paradigms and portable neuroimaging, including functional near-infrared spectroscopy (fNIRS) and electroencephalogram (EEG), metrics of sensorimotor gating. Therefore, we conducted computational simulation of NIBS, including transcranial direct current stimulation(tDCS) and transcranial alternating current stimulation(tACS) of the cerebellar cortex and deep cerebellar nuclei(DCN), of the CCTC loop for its postulated effects on fNIRS and EEG metrics. We also developed a rational neuroimaging guided NIBS approach for cerebellar lobule (VII) and prefrontal cortex based on healthy human study. Results: Simulation study of cerebellar tDCS induced gamma oscillations in the cerebral cortex while tTIS induced gamma-to-beta frequency shift. Experimental fNIRS study found that 2mA cerebellar tDCS evoked similar oxyhemoglobin(HbO) response in-the-range of 5x10-6M across cerebellum and PFC brain regions (=0.01); however, infra-slow (0.01–0.10 Hz) prefrontal cortex HbO driven(phase-amplitude-coupling, PAC) 4Hz, ±2mA (max.) cerebellar tACS evoked HbO in-the-range of 10-7M that was statistically different (=0.01) across those brain regions. Conclusion: Our healthy human study showed the feasibility of fNIRS of cerebellum and PFC as well as fNIRS-driven ctACS at 4Hz that may facilitate cerebellar cognitive function via the frontoparietal network. Future work needs to combine fNIRS with EEG for multi-modal imaging.
ARTICLE | doi:10.20944/preprints202111.0041.v1
Subject: Medicine And Pharmacology, Other Keywords: Obstructive sleep apnea; Continuous positive airways pressure therapy; Near-infrared spectroscopy; Oxygen desaturation; Arm; Pulse oximeter
Online: 2 November 2021 (10:52:45 CET)
Obstructive sleep apnea (OSA) is a common sleep disorder, and continuous positive airways pressure (CPAP) is the most effective treatment. Poor adherence is one of the major challenges in CPAP therapy. The recent boom of wearable optical sensors measuring oxygen saturation makes the at-home multiple-night CPAP titrations possible, which may essentially improve the adherence of CPAP therapy by optimizing its pressure in a real-life setting economically. We tested whether the oxygen desaturations (OD) measured in the arm muscle (arm_OD) by gold-standard frequency-domain multi-distance near-infrared spectroscopy (FDMD-NIRS) changes with titrated CPAP pressures in OSA patients together with polysomnography. We found that the arm_OD (2.08 ± 1.23%, mean ± standard deviation) was significantly smaller (P-value <0.0001) than the fingertip OD (finger_OD) (4.46 ± 2.37%) measured by polysomnography pulse oximeter. Linear mixed-effects models suggested that CPAP pressure was a significant predictor for finger_OD but not for arm_OD. Since FDMD-NIRS measures a mixture of arterial and venous OD, whereas fingertip pulse oximeter measures arterial OD, our results of no association between arm_OD and finger_OD indicate that the arm_OD mainly represented venous desaturation. Arm_OD measured by near-infrared optical sensors may be not a suitable indicator of the effectiveness of CPAP titration.
ARTICLE | doi:10.20944/preprints202105.0061.v1
Subject: Medicine And Pharmacology, Neuroscience And Neurology Keywords: Working memory performance; workload stress; affective states; functional near infrared spectroscopy (fNIRS); haemodynamic activity; prefrontal cortex (PFC)
Online: 5 May 2021 (13:18:34 CEST)
The effect of stress on task performance is complex, too much or too little negatively affects performance; and there exists an optimal level of stress to drive optimal performance. Task difficulty and external affective factors are distinct stressors that impact cognitive performance. Neuroimaging studies showed that mood affects working memory performance and the correlates are changes in haemodynamic activity in the prefrontal cortex (PFC). We investigate the interactive effects of affective states and working memory load (WML) on working memory task performance and haemodynamic activity using functional near-infrared spectroscopy (fNIRS) neuroimaging on the PFC of healthy participants. We seek to understand if haemodynamic responses could tell apart workload related stress from situational stress arising from external affective distraction. We found that the haemodynamic changes towards affective stressor and workload related stress were more dominant in the medial and lateral PFC respectively. Our study reveals distinct affective state-dependent modulations of haemodynamic activity with increasing WML in n-back tasks, which correlate with decreasing performance. The influence of negative affect on performance is greater at higher WML, and haemodynamic activity showed evident changes in temporal, and both spatial and strength of activation differently with WML.
ARTICLE | doi:10.20944/preprints202009.0397.v1
Subject: Physical Sciences, Atomic And Molecular Physics Keywords: dual frequency comb spectroscopy; mid-infrared absorption and dispersion spectroscopy; electrical discharge plasma; time-resolved plasma kinetics
Online: 17 September 2020 (11:03:42 CEST)
Conventional mechanical Fourier Transform Spectrometers (FTS) are able to simultaneously measure absorption and dispersion spectra of gas-phase samples. However, they usually need very long measurement times to achieve time-resolved spectra with a good spectral and temporal resolution. Here, we present a mid-infrared dual-comb-based FTS in an asymmetric configuration, providing broadband absorption and dispersion spectra with a spectral resolution of 5 GHz, a temporal resolution of 20 μs, and a total measurement time of a few minutes. We used the dual-comb spectrometer to monitor the reaction dynamics of methane and ethane in an electrical plasma discharge. We observed ethane/methane formation as a recombination reaction of hydrocarbon radicals in the discharge in various static and dynamic conditions. The results demonstrate a new analytical approach for measuring fast molecular absorption and dispersion changes and monitoring fast dynamics of chemical reactions, which can be interesting for chemical kinetic research and particularly for the combustion and plasma analysis community.
ARTICLE | doi:10.20944/preprints202304.0021.v1
Subject: Chemistry And Materials Science, Food Chemistry Keywords: Hass avocado dry matter gradient; near infrared spectroscopy; Hass avocado harvest; fruit quality; multivariate data analysis; root mean squares
Online: 3 April 2023 (10:22:00 CEST)
Knowing, with reasonable accuracy, the dry matter (DM) content of Hass avocado fruit will help determine when the fruit must be harvested. The reliability of predictive models based on near infrared spectra for DM quantification depends on the ability of the spectra to be representative of the DM gradient within a whole fruit. The aim of this work was to develop a methodology to determine the optimum number of spectra to develop a robust model for DM content quantification. Three spectra were recorded for each zone of the intact fruit: peduncle, equator, and base. Each scanning point was sampled, and the DM content was determined using oven drying. Two-way ANOVA confirmed the DM gradient within the whole fruit. This gradient was observed within spectra using the RMS (root mean square) criterion and PCA. The PLS models showed that at least one spectrum per zone could be enough to construct an efficient and robust model for dry matter quantification.
ARTICLE | doi:10.20944/preprints202308.1869.v1
Subject: Engineering, Bioengineering Keywords: Age difference in prefrontal cortex; mitochondrial and hemodynamic coupling; prefrontal cortical connectivity; resting state functional connectivity; broadband near-infrared spectroscopy
Online: 29 August 2023 (03:45:30 CEST)
A recent study demonstrated that noninvasive measurements of cortical hemodynamics and metabolism in the resting human prefrontal cortex can facilitate quantitative metrics of unilateral mitochondrial-hemodynamic coupling and bilateral connectivity in infraslow oscillation (ISO) frequencies in young adults (YA). The ISO includes three distinct vasomotions with endogenic (E), neurogenic (N), and myogenic (M) frequency bands. The goal of this study was to prove the hypothesis that there are significant differences between young and older adults (OA) in the unilateral coupling (uCOP) and bilateral connectivity (bCON) in the prefrontal cortex. Accordingly, we performed measurements from 24 OA (67.2 ± 5.9 years of age) using the same 2-channel broadband near-infrared spectroscopy (bbNIRS) setup and resting-state experimental protocol as those in the recent study (Shahdadian et al, Cerebral Cortex Communications, 2022). After quantification of uCOP and bCON in three E/N/M frequencies and statistical analysis, we demonstrated that OA had significantly weaker bilateral hemodynamic connectivity but significantly stronger bilateral metabolic connectivity than YA in the M band. Furthermore, OA exhibited significantly stronger unilateral coupling on both prefrontal sides in all E/N/M bands, particularly with a very large effect size in the M band (> 1.9). These age-related results clearly support our hypothesis and were well interpreted following neurophysiological principles. The key finding of this paper is that the neurophysiological metrics of uCOP and bCON are highly associated with age and may have the potential to become meaningful features for human brain health and be translatable for future clinical applications, such as early detection of Alzheimer’s disease.
Subject: Biology And Life Sciences, Biophysics Keywords: consciousness 1; subjective experience 2; will 3; agency 4; self 5; psychopathology 6; treatment 7; transcranial near infrared light 8; biophotomodulation 9
Online: 25 May 2021 (08:44:47 CEST)
In this paper I will address Dr. Sonne’s questions about will, agency, choice, consciousness, relevant brain regions, impacts of disorders and their therapeutics, and I will do this by referring to my theory, Dual-brain Psychology, which posits that within most of us there exist two mental agencies with different experiences, wills, choices, and behaviors. Each of these agencies is associated as a trait with one brain hemisphere (either left or right) and its composite regions. One of these agencies is more adversely affected by past traumas and is more immature and more symptomatic while the other is more mature and healthier. The theory has extensive experimental support through 17 peer-reviewed publications with clinical and non-clinical research. I will discuss how this theory relates to the questions that Dr. Sonne presented and will discuss also my published theory on the physical nature of subjective experience and its relation to the brain and how that theory interacts with DBP, and how the 2 theories relate to subjective experience, will, behavior, psychopathology and its treatment.
ARTICLE | doi:10.20944/preprints202310.0734.v1
Subject: Chemistry And Materials Science, Surfaces, Coatings And Films Keywords: infrared reflection; infrared reflective pigments and coatings; total solar reflection; infrared solar reflection; refractive index; chromatic properties; heat reflection
Online: 11 October 2023 (12:50:30 CEST)
The adsorption of surfaces exposed to sunlight results in increased temperature that can cause physical damage and increase in energy consumption. The infrared reflective coatings that keep objects cooler have significant benefits in a wide variety of application by reflecting the infrared lights, reducing the operating costs, improving energy efficiency of buildings and vehicles (roofs, walls and windows), extend the objects’ lifespan. Our research focused on the elaboration of coatings with minimum adsorption in the infrared wavelength range. This was achieved by production of coatings that have infrared transparent and infrared reflective ability. The infrared reflection and surface warm up was investigated in the function of concentration and composition of pigments in the coatings. With investigation of different coating compositions the pigments and the binding systems were optimized. The coatings with different compositions were characterized by total solar reflection in the UV, visible and infrared wavelength range as well as by infrared reflection. Different coatings were produced in RAL7016 anthracite green color but with much better infrared reflectance, transparency as well as with heat reflectance.
ARTICLE | doi:10.20944/preprints201905.0210.v1
Online: 16 May 2019 (10:44:55 CEST)
We propose a method for the estimation of the spectral response of a photodetector, using only the variation of the temperature of a black body source without the need of an expensive monochromator or a circular filter. The proposed method is suitable especially for infrared detectors in which the cut – off wavelength and the responsivity vs. wavelength is not exactly known. The method provides a rough estimation of the curve S(l) solving a Fredholm integral equation of the first kind. The precision of this technique depends on the number of temperatures at which the detector output is measured. Some example is given in order to better explain the proposed technique.
ARTICLE | doi:10.20944/preprints201912.0085.v1
Subject: Physical Sciences, Applied Physics Keywords: beam profiler; bolometer; laser spot-size; infrared; infrared spectroscopy; time-resolved spectroscopy
Online: 7 December 2019 (00:11:31 CET)
Knowledge of a lasers beam’s profile throughout a laser system and experiment can help immensely in diagnosing laser problems and assisting in beam alignment and focusing at a sample. Obtaining such profiles is a trivial task in the ultraviolet-visible wavelength range but more challenging with near-infrared to infrared beams. Scientific grade bolometer arrays, suitable for such a task, do exist but are extremely costly, relatively large and have a large pixel size, of the order of 80 μm, which is adequate for profiling larger beams but poses an issue when trying to profile sub 100 μm beams for example at a focal point. This communication identifies a micro-bolometer array for near- to mid-infrared laser beam profiling, which is extremely low cost. In addition, the device is very compact, enabling use in confined spaces, and has a small, 12 μm, pixel size permitting the profiling of focused laser beams. The best scientific grade device identified has a pixel size of 17 μm. This device is a powerful tool for infrared laser spectroscopists, reducing the time required to measure the spot size of beams and to achieve spatial overlap of multiple infrared beams as used in two-dimensional infrared spectroscopy, saving many hours of setup time. The use of the bolometer array as a spectrographic detector and probe of long-term beam drifts is also demonstrated.
ARTICLE | doi:10.20944/preprints201702.0050.v1
Subject: Engineering, Electrical And Electronic Engineering Keywords: Digital Lock-in Amplifier (DLIA); Field Programmable Gate Array (FPGA); Near Infrared Spectroscopy (NIRS); Hardware Description Language (HDL); Light Emitting Diode (LED); Silicon Photomultiplier (SiPM); Microprocessors
Online: 14 February 2017 (09:11:38 CET)
Functional Near Infrared Spectroscopy (fNIRS) systems for e-health applications usually suffer of poor signal detection mainly due to a low end-to-end signal to noise ratio of the electronics chain. Lock-In Amplifiers (LIA) historically represent a powerful technique helping to improve performances in such circumstances. In this work it has been designed and implemented a digital LIA system, based on a Zynq® Field Programmable Gate Array (FPGA), trying to explore if this technique might improve fNIRS system performances. More broadly, FPGA based solution flexibility has been investigated, with particular emphasis applied to digital filter parameters, needed in the digital LIA, and it has been evaluated its impact on the final signal detection and noise rejection capability. The realized architecture was a mixed solution between VHDL hardware modules and software ones, running within a softcore microprocessor. Experimental results have shown the goodness of the proposed solutions and comparative details among different implementation will be detailed. Finally a key aspect taken into account throughout the design was its modularity, allowing an ease increase of the input channels while avoiding the growth of the design cost of the electronics system.
COMMUNICATION | doi:10.20944/preprints202306.0297.v1
Subject: Physical Sciences, Theoretical Physics Keywords: Tunable deflection; epsilon-near-zero; metamaterial.
Online: 5 June 2023 (10:07:51 CEST)
Epsilon-near-zero nanoantennas can be used to tune the far-field radiation pattern due to their exceptionally large intensity-dependent refractive index. Here, we propose hybrid optical antenna based on indium tin oxide (ITO) to optically tune the deflection of radiation. In particular, a hybrid structure antenna of ITO and dielectric material, which makes the deflection angle changes 17 ∘ as incident intensities increases. Finally, the array of ITO or hybrid nanodisks can enhance the unidirectionality to be needle-like, with the angular beam width α< 8∘ of main lobe. The deflection angle of radiation pattern response with needle-like lobe pave the way for further studies and applications in beam steering and optical modulation where dynamic control of the nanoantennas is highly desirable.
ARTICLE | doi:10.20944/preprints202304.0348.v1
Subject: Environmental And Earth Sciences, Atmospheric Science And Meteorology Keywords: tourism; Romania; climate information; near future
Online: 14 April 2023 (04:25:54 CEST)
The study presents an assessment of climate suitability for outdoor leisure activities in Romania using the Holliday Climate Index (HCI) for the near future (2021-2040), focusing on unfavorable and good climate conditions. The analysis employs data from an ensemble model in the context of RCP45 and RCP85 climate change scenarios. The results indicate that the number of days with low weather suitability is decreasing in almost the entire country, especially during the warm season, while during the winter and spring extended regions may be characterized by a higher number of days favorable for outdoor activities than during the current climate. An estimation of the impact of climate changes on tourism flux in Romania is further carried out, suggesting that the increasing attractivity of climate conditions may lead to an increased number of tourist overnights in the near future, more pronounced in rural destinations.
ARTICLE | doi:10.20944/preprints202106.0042.v1
Subject: Engineering, Control And Systems Engineering Keywords: near miss modelling; sustainability; Machine Learning.
Online: 1 June 2021 (15:10:12 CEST)
In European Seveso Legislation for the control of the hazard of major accidents (Directive 2015/12/UE), the Safety Management System SMS is an essential obligation for managers and the authorities are required to periodically verify its adequateness through periodical inspections at Seveso sites. One of the pillars of the SMS is the collection and analysis of documents on accidents, near misses and possibly anomalies, in order to identify weaknesses and implement continuous improvement. In Italy, for a few years, the documents, gathered from all Italian Seveso sites by the inspectors, have been archived and used for research purposes. The archive currently contains some 4000 reports, collected in five years by some 100 inspectors throughout Italy. The paper discusses in the detail the challenges faced to extract the knowledge hidden in the documents and make it usable through the design of a robust model. For this aim, Machine Learning techniques have been used as a preprocessing of the reports for extracting the concepts and their relations, organized into an entity-relation model. The effectiveness of this methodology and its potentiality are pointed out by investigating a few hot topics, exploiting the information contained in the repository.
ARTICLE | doi:10.20944/preprints202210.0417.v1
Subject: Public Health And Healthcare, Other Keywords: Sock; infrared thermography; temperature; comfort
Online: 27 October 2022 (02:13:40 CEST)
Socks with the same three-dimensional plantar design, but with different compositions in the separation of their weaves could have different thermoregulatory effects. The objective of this study was therefore to evaluate the temperatures on the sole of the foot after a 10-km run, using two models of socks with different weave separations. In a sample of 20 individuals (14 men and 6 women), plantar temperatures were analysed using a Flir E60bx® (Flir Systems) thermographic camera before and after a run of 10 km wearing two models of socks that had different separations between the fabric weaves (5 mm versus 3 mm). After the post-exercise thermographic analysis, the participants responded to a Likert type survey to evaluate the physiological characteristics of the two models of socks. There was a significant increase in temperature in the areas of interest (p<0.001) after the 10-km run with both models of sock. The temperature under the 1st metatarsal head was higher with the AWC 2.1 model than with the AWC 1 (33.6±2.0°C vs 33.2±2.1°C) (p = 0.014). No significant differences were found in the scores on the physiological characteristics comfort survey (p>0.05 in all cases. The two models presented similar thermoregulatory effects on the soles of the feet, although the model with the narrowest weave separation generated greater temperatures (+0.4°C) under the first metatarsal head.
ARTICLE | doi:10.20944/preprints201903.0083.v1
Online: 7 March 2019 (06:43:58 CET)
Waste heat dissipated in the exhaust system in a combustion engine represents a major source of energy to be recovered and converted into useful work. A waste heat recovery system (WHRS) based on an Organic Rankine Cycle (ORC) is a promising approach, and has gained interest in the last few years in an automotive industry interested in reducing fuel consumption and exhaust emissions. Understanding the thermodynamic response of the boiler employed in an ORC plays an important role in steam cycle performance prediction and control system design. The aim of this study is therefore to present a methodology to study these devices by means of pattern recognition with infrared thermography. In addition, the experimental test bench and its operating conditions are described. The methodology proposed identifies the wall coordinates, traces paths, and tracks wall temperature along them in a way that can be exported for subsequent post-processing and analysis. As for the results, through the wall temperature paths on both sides (exhaust gas and working fluid) it was possible to quantitatively estimate the temperature evolution along the boiler and, in particular, the beginning and end of evaporation.
ARTICLE | doi:10.20944/preprints201703.0061.v1
Subject: Engineering, Control And Systems Engineering Keywords: cross-spectral; descriptor; infrared; CNN
Online: 13 March 2017 (08:31:22 CET)
This paper presents a novel CNN-based architecture, referred to as Q-Net, to learn local feature descriptors that are useful for matching image patches from two different spectral bands. Given correctly matched and non-matching cross-spectral image pairs, a quadruplet network is trained to map input image patches to a common Euclidean space, regardless of the input spectral band. Our approach is inspired by the recent success of triplet networks in the visible spectrum, but adapted for cross-spectral scenarios, where for each matching pair there are always two possible non-matching patches; one for each spectrum. Experimental evaluations on a public cross-spectral VIS-NIR dataset shows that the proposed approach improves the state-of-the-art. Moreover, the proposed technique can also be used in mono-spectral settings, obtaining a similar performance to triplet network descriptors, but requiring less training data.
ARTICLE | doi:10.20944/preprints202312.0075.v1
Subject: Physical Sciences, Astronomy And Astrophysics Keywords: radar; near-Earth Objects; asteroids; planetary defense
Online: 4 December 2023 (08:27:04 CET)
In this work, we present preliminary results of radar observations of near-Earth Objects (NEOs) carried out by European radio telescopes in the framework of the European Space Agency (ESA) project “NEO observation concepts for radar systems”, which was aimed to derive the functional requirements of a radar system, evaluate the available European assets to perform NEO radar observations and carry out test radar campaigns. In the first part of the project, we carried out the performance analysis of a possible European planetary radar system. Instrumental features, as much as issues like the impact of weather conditions on signal propagation at different radio frequencies, were considered. This paper is focused on the test campaigns, performed in the years 2021-22 in collaboration with the Jet Propulsion Laboratory (JPL), which led to the observation of several asteroids including 2021 AF8, (4660) Nereus and 2005 LW3, which allowed us to derive astrometric measurements, as well as to measure physical properties, such as rotation periods, and detect an asteroid’s satellite. The obtained results demonstrate that European radio astronomical dishes, although employed only as receivers (in bistatic or multistatic configurations) and for a limited amount of time, are able to provide a significant contribution to the constitution of a European network to increase the opportunities for NEO monitoring and studies, if a transmitting antenna - equipped with a suitable high-power transmitter - were made available.
ARTICLE | doi:10.20944/preprints202307.1187.v1
Subject: Environmental And Earth Sciences, Oceanography Keywords: ODYSEA; Near Inertial Oscillation; NIO; surface current
Online: 18 July 2023 (09:49:09 CEST)
Near Inertial Oscillations (NIOs) are ocean oscillations forced by intermittent winds. They are most energetic at mid-latitudes, particularly in regions of atmospheric storm tracks. Wind-driven, large-scale NIOs are quickly scattered by ocean mesoscale eddies (with sizes ranging from 100 to 400 km), causing a significant portion of the NIO energy to propagate into the ocean interior. This kinetic energy pathway illustrates that the wind energy input to NIO, estimated at 5 TeraWatts, is critical for maintaining deep ocean stratification and thus closing the total kinetic energy budget, as emphasized by numerous modelling studies. However, this wind energy input to NIO remains poorly observed on a global scale. A remote sensing approach, which observes winds and ocean currents co-located in time and space with high resolution, is necessary to capture the intermittent air-sea coupling. The current satellite observations do not meet these requirements. This study assesses the potential of a new satellite mission concept, Ocean DYnamics and Surface Exchange with the Atmosphere (ODYSEA), to recover wind-forced NIOs from co-located winds and currents. To do this, we use an Observation System Simulation Experiment (OSSE) based on hourly observations of ocean surface currents and surface winds from five surface moorings covering latitudes from 15∘ to 50∘. ODYSEA wind and current observations are expected to have a spatial resolution of 10 km with about 12-hour sampling frequency in mid-latitudes. Results show that NIOs can be recovered with high accuracy using the ODYSEA spatial and temporal resolution, only if observations are made in a wide-swath of 1,800 km. A narrower swath (1,000 km) may lead to significant aliasing.
ARTICLE | doi:10.20944/preprints202301.0428.v1
Subject: Engineering, Civil Engineering Keywords: Near field; dilution; submarine outfall, waves effects
Online: 24 January 2023 (10:21:37 CET)
The initial dilution generated by the final disposal of untreated wastewater through a submarine outfall in Santa Marta was examined with a near-field dilution model. Northward and eastward seawater velocity, salinity, and temperature profiles from a 3D hydrodynamic model were used to provide the oceanic conditions to calculate the dilution. At the wastewater discharge site, the upwelling phenomenon occurs two times a year, the major from December to March and the minor in July, eliminating the stratification condition of seawater. The results of the dilution model showed that in these periods the plume reaches the water surface achieving dilutions greater than 100. In addition, the external wave effect on the initial dilution of submarine outfall discharge in Santa Marta was determined. Surface waves increase dilution during the dry period of the year when trade winds increase the surge and start the upwelling phenomenon. The Dilution with/without waves factor is up to 1.90 for the center of the plume on the water column.
ARTICLE | doi:10.20944/preprints202306.0896.v1
Subject: Chemistry And Materials Science, Analytical Chemistry Keywords: Phenols; triterpenes; drying; infrared; microwaves; lyophilization.
Online: 13 June 2023 (08:23:29 CEST)
Olive tree vegetal materials are considered a powerful source for isolation of bioactive compounds, mainly, phenols and triterpenic acids. However, the high humidity content of them reduces their preservation and extractability to a liquid solvent. Accordingly, a drying step is crucial to homogenize the material and to obtain an efficiency extraction. We studied the influence of the drying process on the extraction efficiency of bioactive compounds from olive vegetal material. For this purpose, we evaluated the effects of four drying processes on the solid–liquid extraction of bioactive compounds from two by-products, olive leaves and pomace, and olive fruits harvested from two cultivars, Alfafara and Koroneiki. Infrared-assisted drying (IAD) was the most suited approach to obtain extracts enriched in oleuropein from leaves. In the case of pomace, lyophilization and microwaves-assisted drying led to extracts concentrated in oleacein and oleuropein aglycone, whereas IAD and oven-drying led to extracts with enhanced content in hydroxytyrosol glucoside and hydroxytyrosol, respectively. The drying process affected considerably to the chemical composition of extracts obtained from fruits. Changes in the composition of extracts were explained essentially by the drying process conditions using auxiliary energies, temperature and time, which promoted chemical alterations and increased the extractability of compounds.
ARTICLE | doi:10.20944/preprints202107.0528.v1
Subject: Physical Sciences, Acoustics Keywords: Infrared sensors; calibration model; Online monitoring
Online: 23 July 2021 (08:08:45 CEST)
Infrared sensors are applied more and more widely in industrial production applications. Based on the theory of thermal radiation, this paper discusses the system design principle, temperature calibration method and thermal image analysis method in detail. The system has passed the measurement unit certification, showing that the field of view is 180°, the number of scanning points is 2048, the linear velocity is 10-100Hz, the spatial resolution is 2.5mrad, and the precision is ±1℃. On-line monitoring test has been done in the steelmaking plant of Bao Steel. The results show that the system has strong anti-interference ability, stability and reliability, and meets the application requirements of online monitoring.
ARTICLE | doi:10.20944/preprints202003.0358.v1
Subject: Physical Sciences, Optics And Photonics Keywords: metasurface; mid infrared absorption; perfect absorption
Online: 27 March 2020 (12:32:57 CET)
The realization of a perfect absorber A = 1 with transmittance and reflectance T=R=0 by a thin metasurface is one of the hot topics in recent nanophotonics prompted by energy harvesting and sensor applications (A + R + T =1 is the energy conservation). Here we tested optical properties of over 400 structures of metal-insulator-metal (MIM) metasurfaces for a range of variation in thickness of insulator, the diameter of a disc and intra-disc distance experimentally and numerically. Conditions of a near-perfect absorption A > 95% with simultaneously occurring anti-reflection property (R < 5%) were experimentally determined. Differences between the bulk vs. nano-thin film properties at mid-IR of the used materials can be of interest for plasmonic multi-metal alloys and high entropy metals.
ARTICLE | doi:10.20944/preprints202008.0689.v1
Subject: Environmental And Earth Sciences, Environmental Science Keywords: Inhibitive assay; mercury; ficin; RSM; near real-time
Online: 31 August 2020 (03:53:15 CEST)
Heavy metals pollution in the Straits of Malacca warrants the development of rapid, simple and sensitive assays. Enzyme-based assays are excellent preliminary screening tool with near real-time potential. The heavy-metal assay based on the protease ficin was optimized for mercury detection using Response Surface Methodology. The inhibitive assay is based on ficin action on the substrate casein and residual casein is determined using the Coomassie dye-binding assay. Heavy metals strongly inhibit the hydrolysis. A Central Composite Design (CCD) was utilized to optimize detection. The results show a marked improvement for the concentration causing 50% inhibition (IC50) for mercury, silver and copper. Compared to One-factor-at-a-time (OFAT) optimization, RSM gave an improvement of IC50 from 0.060 (95% CI, 0.0300.080) to 0.017 (95% CI, 0.0160.019), from 0.098 (95% CI, 0.0770.127) to 0.028 (95% CI, 0.0220.037) and from 0.040 (95% CI, 0.035.045) to 0.023 (95% CI, 0.0200.027), for mercury, silver and copper, respectively. A near real-time monitoring of mercury concentration in the Straits of Malacca at one location in Port Klang was carried out over a 4-h interval for a total of 24 h and validated by instrumental analysis with the result revealing an absence of mercury pollution in the sampling site.
ARTICLE | doi:10.20944/preprints201912.0313.v1
Subject: Physical Sciences, Condensed Matter Physics Keywords: near-room-temperature superconductivity; hydride superconductors; yttrium superhydrides
Online: 24 December 2019 (08:47:09 CET)
Recently, Troyan et al (2019 arXiv:1908.01534) and Kong et al (2019 arXiv:1909.10482) extended near-room-temperature superconductors family by new yttrium superhydride polymorphs, YHn (n = 4,6,7,9), which exhibit superconducting transition temperatures in the range of Tc = 210-243 K at pressure of P = 160-255 GPa. In this paper, temperature dependent upper critical field data, Bc2(T), for highly-compressed mixture of YH4+YH6 phases (reported by Kong et al 2019 arXiv:1909.10482) is analysed to deduce the ratio of Tc to the Fermi temperature, TF. Our analysis shows that in all considered scenarios the YH4+YH6 mixture has the ratio 0.01 ≤ Tc/TF ≤ 0.04. As the result, YH4+YH6 falls in the unconventional superconductors band in the Uemura plot. It is also found that the characteristic temperature of the order parameter amplitude fluctuations, Tfluc, in the YH4+YH6 mixture is only several percent above observed Tc, and thus the superconducting transition in yttrium superhydride polymorphs is fundamentally limited by thermodynamics fluctuations.
ARTICLE | doi:10.20944/preprints201804.0368.v1
Subject: Medicine And Pharmacology, Obstetrics And Gynaecology Keywords: proportion; near-misses; morbidity; mortality; public health institution
Online: 28 April 2018 (11:56:04 CEST)
Background: Maternal near-miss refers to a situation where a woman who nearly died but survived from severe life-threatening obstetric complications that occurred during pregnancy, childbirth or within 42 days of termination of pregnancy. It has been estimated that up to 9 million women survive obstetric complications every year. According to studies done around the world most mothers suffer from Near Miss due to the factors which includes, low socioeconomic status, patient related, health provider related, and health related and health institution related issues. Objectives: The objective of the study was to determine the proportion of maternal near misses and its associated factors in Selected Public Health Institutions of Keffa, Bench-Maji and Sheka Zones of South Nations Nationalities and Peoples Regional state, South West Ethiopia, 2017. Methodology: Hospital based cross-sectional study design was employed and simple random sampling techniques (Lottery Method) was used to select the study institution and Systematic sampling technique was used to select 845 study participants every 5th interval. Information was collected by using pre-tested and structured interviewer administered questioner. Using SPSS version 21 software, descriptive statistics and bivariate logistic regression analysis was done and variables with p-value <0.2 were transferred to multivariate analysis and during Multivariate logistic regression analysis Variables with P-value < 0.05 were considered as statistically significant and AOR with 95% CI were used to control for possible confounders and to interpret the result. The results were summarized by tables, graphs and charts. Result: There were 5530 Live Births, 227 Sever Acute Maternal Morbidity cases of this 210 were Maternal Near-Misses cases and 17 were maternal deaths, 364 Maternal Near-Misses Events. The overall Maternal Near-Misses Proportion is 24.85%. The maternal Near-Misses outcome ratio was 41 cases/1,000 live births (LB); mortality ratio was 12.35cases/1 maternal death and 74.8/1000LB of mortality index. Parity, residence, distance of living place from hospital, ANC Follow up, duration of labor, and administrative related problems were found to have statistically significant associations. Conclusion: The proportion of Maternal Near-Misses is relatively high when compared to other regional studies and efforts should be done to lower the near-misses.
ARTICLE | doi:10.20944/preprints201610.0070.v1
Subject: Environmental And Earth Sciences, Atmospheric Science And Meteorology Keywords: coastal; experiment; lidar; near-shore; offshore; wind resources
Online: 18 October 2016 (07:51:46 CEST)
We present a comprehensive database of near-shore wind observations that were carried out during the experimental campaign of the RUNE project. RUNE aims at reducing the uncertainty of the near-shore wind resource estimates from model outputs by using lidar, ocean, and satellite observations. Here we concentrate in describing the lidar measurements. The campaign was conducted from November 2015 to February 2016 at the west coast of Denmark and comprises measurements from eight lidars, an ocean buoy and three types of satellites. The wind speed was estimated based on measurements from a scanning lidar performing PPIs, two scanning lidars performing dual synchronized scans, and five vertical profiling lidars, of which one was operating offshore on a floating platform. The availability of measurements is highest for the profiling lidars, followed by the lidar performing PPIs, those peforming the dual setup, and the lidar buoy. Analysis of the lidar measurements reveals good agreement between the estimated 10-m wind speeds, although the instruments used different scanning strategies and measured different volumes in the atmosphere. The campaign is characterized by strong westerlies with occasional storms.
REVIEW | doi:10.20944/preprints202306.0019.v1
Subject: Engineering, Energy And Fuel Technology Keywords: sustainable agriculture; greenhouse; innovative heating; infrared; microwaves
Online: 1 June 2023 (03:47:05 CEST)
For the agricultural sector to develop sustainably in the future, progress toward more environmentally friendly technologies and methods is crucial. It is necessary to increase output while reducing the demand for energy, agrochemicals, and water resources. Although greenhouses can be utilized successfully for this purpose, significant technical advancements are required, especially when it comes to heating, to lower the use of fossil fuels and boost energy efficiency. Infrared waves and microwaves, for instance, can warm plants without having to heat the entire greenhouse volume, which takes a significant amount of energy to compensate for heat loss to the outdoor environment. In this paper, through a thorough examination of the state of the art, a general overview of novel greenhouse heating systems based on radiation is reported. First, infrared heating of greenhouses is analyzed, then the strengths and weaknesses of microwave and dielectric heating are discussed, and finally the use of microwaves for soil sterilization is examined. All outcomes suggest these irradiation-based technologies can contribute significantly to an agriculture that is energetically sustainable.
REVIEW | doi:10.20944/preprints202007.0034.v1
Subject: Biology And Life Sciences, Biophysics Keywords: hydrogen; biocatalysis; hydride chemistry; photochemistry; infrared spectroscopy
Online: 3 July 2020 (12:12:12 CEST)
Hydrogenases are iron-sulfur enzymes that catalyze proton reduction and H2 oxidation with outstanding efficiency. They are considered blueprints for the design of transition metal complexes, e.g. as heterogenous catalysts in the context of H2 production from water. Moreover, hydrogenases are biological model systems for metal hydride chemistry and proton-coupled electron transfer. Depending on the composition of the active site cofactor, [NiFe]-hydrogenases are distinguished from [FeFe]-hydrogenases. The former binds a hetero bimetallic nickel/iron site, embedded in the protein by four cysteine ligands. The later, by contrast, carries a homo bimetallic iron/iron site attached to the protein by only a single cysteine. Carbon monoxide and cyanide ligands (CO/CN) at the active site facilitated detailed investigations of hydrogenase catalysis by infrared spectroscopy, owing to strong signals and redox-dependent frequency shifts. However, the details of proton transfer have not been addressed experimentally.We found that specific redox state transitions in [NiFe]- and [FeFe]-hydrogenase can be triggered by visible light to record extremely sensitive ‘light-minus-dark’ infrared difference spectra monitoring key amino acid residues as shown in the ToC figure. As these transitions are coupled to protonation changes, our data allowed investigating dynamic hydrogen-bonding changes that go well beyond the resolution of protein crystallography. In [NiFe]-hydrogenase, photolysis of the bridging hydride ligand in the ‘Ni-C’ state was followed by rapid accumulation of the ‘Ni-SIa’ state and/or ‘Ni-L’ state. Infrared difference spectra in various isotopic media clearly indicated the formation of a protonated cysteine residue as well as hydrogen-bonding changes involving the COOH group of a glutamic acid residue and a ‘dangling water’ molecule. These findings are in excellent agreement with crystallographic analyses of [NiFe]-hydrogenase in the Ni-R state and allowed devising a molecular precise model of catalytic proton transfer. In [FeFe]-hydrogenase, an external redox dye was used to accumulate the ‘Hred’ state over the oxidized resting state ‘Hox’. Infrared difference spectra of wild-type enzyme and numerous amino acid variants indicated hydrogen-bonding changes involving the COOH groups of two glutamic acid residues. Moreover, we noted the deprotonation of an arginine residue. Crystallographic analyses of [FeFe]-hydrogenase in the Hox state failed to explain the rapid proton transfer due to a ‘breach’ in the succession of residues. To this end, our findings facilitated a molecular precise model of ‘discontinued’ proton transfer.The comparison of catalytic proton transfer in bimetallic hydrogenases emphasizes the role of the outer coordination sphere. We suggest that the stable protonation of a nickel-ligating cysteine in [NiFe]-hydrogenase has a crucial influence on the preferred direction of proton flow and catalysis (i.e., H2 oxidation). On the contrary, proton transfer in [FeFe]-hydrogenase involves an adjacent cysteine as a relay group that promotes both proton release and proton uptake. We presume that this causes the notable bidirectionality of [FeFe]-hydrogenase. These observations must guide the design of biomimetic compounds for the production or consumption of H2.
ARTICLE | doi:10.20944/preprints201905.0343.v1
Subject: Engineering, Electrical And Electronic Engineering Keywords: infrared sensors; cameras; indoor positioning; sensor fusion
Online: 29 May 2019 (04:45:00 CEST)
A method for infrared and cameras sensor fusion, applied to indoor positioning in intelligent spaces, is proposed in this work. The fused position is obtained with a maximum likelihood estimator from infrared and camera independent observations. Specific models are proposed for variance propagation from infrared and camera observations (phase shifts and image respectively) to their respective position estimates and to the final fused estimation. Model simulations are compared with real measurements in a setup designed to validate the system. The difference between theoretical prediction and real measurements is between 0.4 cm (fusion) and 2.5 cm (camera), within a 95% confidence margin. The positioning precision is in the cm level (sub-cm level can be achieved at most tested positions) in a 4x3 m locating cell with 5 infrared detectors on the ceiling and one single camera, at distances from target up to 5 m and 7 m respectively. Due to the low cost system design and the results observed, the system is expected to be feasible and scalable to large real spaces.
ARTICLE | doi:10.20944/preprints201803.0015.v1
Subject: Physical Sciences, Optics And Photonics Keywords: Casimir effect, dispersion, ultraviolet divergences, infrared divergences
Online: 1 March 2018 (16:58:15 CET)
It is familiar that the Casimir self-energy of a homogeneous dielectric ball is divergent, although a finite self-energy can be extracted through second order in the deviation of the permittivity from the vacuum value. The exception occurs when the speed of light inside the spherical boundary is the same as that outside, so the self-energy of a perfectly conducting spherical shell is finite, as is the energy of a dielectric-diamagnetic sphere with $\varepsilon\mu=1$, a so-called isorefractive or diaphanous ball. Here we re-examine that example, and attempt to extend it to an electromagnetic $\delta$-function sphere, where the electric and magnetic couplings are equal and opposite. Unfortunately, although the energy expression is superficially ultraviolet finite, additional divergences appear that render it difficult to extract a meaningful result in general, but some limited results are presented.
REVIEW | doi:10.20944/preprints201610.0011.v1
Subject: Environmental And Earth Sciences, Remote Sensing Keywords: infrared remote sensing; volcanoes; earth observation, satellites
Online: 5 October 2016 (11:54:54 CEST)
Volcanic activity essentially consists of the transfer of heat from the Earth’ interior to the surface. The precise signature of this heat transfer relates directly to the processes underway at and within a particular volcano and this can be observed, at a safe distance, remotely, using infrared sensors that are present on Earth-orbiting satellites. For over 50 years, scientists have perfected this art using sensors intended for other purposes, and they are now in a position to determine the particular sort of activity that characterizes different volcanoes. This review will describe the theoretical basis of the discipline and then discuss the sensors available for the task and the history of their use. Challenges and opportunities for future development in the discipline are then discussed.
ARTICLE | doi:10.20944/preprints202306.0307.v1
Subject: Engineering, Electrical And Electronic Engineering Keywords: SMD inductor; loss tangent; effective permeability; Near-field coupling
Online: 5 June 2023 (10:30:01 CEST)
In this paper, we propose a methodology for analyzing the near-field coupling between two surface mount device (SMD) inductors using a 3-dimensional electromagnetic (3D-EM) model. To develop the 3D-EM model, we first extract the effective permeability of core magnetic material in the SMD using the loss tangent in the equivalent circuit model. Then the effective permeability is used in the magnetic material for the 3D-EM modeling of SMD inductor. The validity of the proposed 3D-EM model is confirmed by comparing the impedance and S-parameters obtained from both measured and EM-simulated values for the two near-field coupled SMDs. Finally, the near-field coupling effects between the two adjacent SMD inductors are visualized in terms of magnetic coupling path visualization (CPV) using the proposed 3D-EM model, which demonstrates its usefulness for near-field coupling analysis.
ARTICLE | doi:10.20944/preprints202304.0690.v1
Subject: Engineering, Electrical And Electronic Engineering Keywords: near space; Joule heat; solar radiation; aerodynamic; temperature correction
Online: 21 April 2023 (08:32:51 CEST)
Near space environment is the airspace at an altitude of 20 km-100 km, where complex conditions such as low temperature, low pressure, high wind speed and solar radiation exist. As one of the important meteorological parameters, temperature is crucial for space activities, but the influence of the complex environment makes the error of conventional temperature measurement methods large. Therefore, a new microbridge temperature sensor was designed that can reduce solar radiation and achieve a fast response. And through simulation analysis, the three factors influencing the temperature errors of Joule heat, solar radiation heat and aerodynamic heat were investigated. And the influence of temperature error is reduced by optimizing the installation position of the sensor. Through the temperature error model, the error value in the actual measurement value is removed, to realize the high accuracy detection of near-space temperature.
ARTICLE | doi:10.20944/preprints202207.0077.v1
Subject: Environmental And Earth Sciences, Atmospheric Science And Meteorology Keywords: near-surface humidity; remote sensing; deep learning; China Seas
Online: 5 July 2022 (13:46:55 CEST)
Near-surface humidity (Qa) is a key parameter that modulates oceanic evaporation and influences the global water cycle. Remote sensing observations act as feasible sources for long-term and large-scale Qa monitoring. However, existing satellite Qa retrieval models are subject to apparent uncertainties due to model errors and insufficient training data. Based on in situ observations collected over the China Seas over the last two decades, a deep learning approach named Ensemble Mean of Target deep neural networks (EMTnet) was proposed to improve the satellite Qa retrieval over the China Seas for the first time. The EMTnet model outperforms five representative existing models by nearly eliminating the mean bias and significantly reducing the root-mean-square error in satellite Qa retrieval. According to its target deep neural networks selection process, the EMTnet model can obtain more objective learning results when the observational data are divergent. The EMTnet model was subsequently applied to produce a 30-year monthly gridded Qa data over the China Seas. It indicates that the climbing rate of Qa over the China Seas under the background of global warming are probably underestimated by current products.
ARTICLE | doi:10.20944/preprints202203.0163.v1
Subject: Social Sciences, Safety Research Keywords: Optimal Forager Theory; Near-Repeat Theory; Burglary; Crime; Policing
Online: 11 March 2022 (08:31:34 CET)
The use of crime mapping has been used by the police to inform deployment of resources for many decades. Such approaches are commonly used to underpin crime control strategies designed to prevent or reduce acquisitive crimes such as domestic burglary. In recent decades there has been a shift away from simple hot spot identification to more complex geospatial mapping methodologies, such as near repeat analysis which was developed through research regarding burglary victimisation. One of these newly emerging methodologies is built upon the ecological, optimal forager theory (OFT). Research using this theory to examine domestic burglary offending intimated potential for positive results in predicting areas at risk of future crime. This led to a number of police services using crime analysis methodologies built upon OFT to underpin their deployment of resources in an effort to prevent or reduce domestic burglary through increased capable guardianship. However, to date, there has been no detailed examination of how the police services implemented such approaches. As such, this study seeks to fill this gap by examining OFT strategies implemented within 5 police services. By interviewing participants directly involved in the programs the study gathers views and perspectives of its relative success. As a result, we identify that participants felt the strategies produced limited impact on recorded burglary crime. We discuss how despite some positive by-products of the strategies, failure to comprehensively apply the theoretical foundations of OFT, and a variety of implementation failures have undermined the various programs, ultimately impacting their effectiveness.
ARTICLE | doi:10.20944/preprints202010.0549.v1
Subject: Engineering, Automotive Engineering Keywords: Near-bank patch; Deformed bed topography; Flow adjustment; Hydrodynamics
Online: 27 October 2020 (11:39:40 CET)
Understanding how the deformed bed topography induced by near-bank vegetation impacts the hydrodynamics is significant for understanding the maintenance condition of bed morphology and further fluvial evolution. This issue has rarely been addressed by current studies. This study with a 2D hydro-morphological model investigates the hydrodynamics over flat and deformed beds with a near-bank vegetation patch. By varying the patch density, the generalized results show that the hydrodynamics for the deformed bed differs a lot from those for the flat bed. It is found that deformed bed topography leads to an apparent decrease in longitudinal velocity and bed shear stress in the open region and longitudinal surface gradient for the entire vegetated reach. However, the transverse flow motion and transverse surface gradient in the region of the leading edge and trailing edge is enhanced or maintained, suggesting the strengthening of secondary flows. Interestingly, the deformed bed topography tends to alleviate the turbulent effect caused by the junction-interface horizontal coherent vortices, indicating that the turbulence-induced flow mixing is highly inhibited by the deformed bed. Alternatively, the enhanced secondary flows might provide compensation for the flow mixing for the deformed bed, confirmed by a faster recovery of the redistributed water discharge for the vegetated and open regions to the normal value (50%). The interior flow adjustment through the patch for the deformed bed requires a shorter distance, which links the vegetative drag length with a logarithmic relation. The tilting bed topographic effect in the open region to accelerate the flow may account for the faster flow adjustment.
ARTICLE | doi:10.20944/preprints202311.1911.v1
Subject: Medicine And Pharmacology, Pediatrics, Perinatology And Child Health Keywords: infrared thermal imaging; toddler’s fracture; bone fracture screening; infrared thermal image processing and analysis; artificial intelligence; emergency medicine; orthopaedics
Online: 29 November 2023 (16:40:58 CET)
The purpose of this study was to explore and develop high-resolution infrared thermal (HRIT) imaging for screening toddler’s fracture. A Toddler’s fracture is a common tibial fracture of children younger than 6 years old. Initial x-ray radiographs may not show the fracture and another x-ray during a follow-on visit is usually required. The study included 39 participants admitted to an emergency department with a suspected toddler’s fracture. X-ray confirmed 8 cases with a toddler’s fracture (20.5%). Infrared images of participants were recorded on their index visit, focusing on region-of-interests on the injured and the contralateral (uninjured) legs. The uninjured leg acted as a thermal reference. Nine statistical measures were extracted from the images: maximum, mini-mum, mean, standard deviation, median, mode, interquartile range, skewness, and kurtosis. Wilcoxon rank sum test indicated that maximum, mean, standard deviation, median, and inter quartile range temperature measures were significantly different (p<0.05) when comparing fractured and non-fractured legs. Principal component analysis of these measures highlighted distinct separation of toddler’s fracture and non-fracture cases. Similarly, plots of the statistical measures further confirmed clustering of toddler’s fracture cases. The study demonstrated that HRIT imaging can be a valuable tool for screening for toddler’s fracture.
ARTICLE | doi:10.20944/preprints202308.0028.v1
Subject: Chemistry And Materials Science, Surfaces, Coatings And Films Keywords: Composite coating; Infrared emissivity; Hydrophobic property; Mechanical property
Online: 1 August 2023 (09:50:57 CEST)
In order to further reduce the emissivity of the hydrophobic low infrared emissivity composite coating and improve the mechanical properties of the coating, the dispersant, adhesion enhancer, and defoamer were used to improve the dispersion state of the fillers, the interface structure, and the surface state of the hydrogen silicone oil modified polyurethane/Al composite coating. The effects of dispersant, adhesion enhancer, and defoamer on the micro-structure, emissivity, glossiness, hydrophobic property, and mechanical properties of the coating were systematically studied. The results show that the polycarboxylate anionic dispersant can obviously improve the dispersion state of flake Al powder and nano-SiO2 in the coating, so that the infrared emissivity of the coating can be reduced, and the coating can have higher hydrophobic and mechanical properties. The bonding strength between the resin matrix and the metal substrate of the coating can be significantly improved by the adhesion enhancer through the bridging action, so that the adhesion strength and impact strength of the coating can be significantly improved. The defoamer can significantly reduce the pores in the coating, so that the surface state of the coating can be significantly improved, and the mechanical properties of the coating can be significantly improved. The coating has the best emissivity (0.527), glossiness (4.3), adhesion strength (grade 1), impact strength (40 kg.cm), and hydrophobic property (water contact angle (WCA) is 140o) when the amount of dispersant, adhesion enhancer, and defoamer is 5 wt%, 4 wt%, and 1 wt%, respectively.
ARTICLE | doi:10.20944/preprints202307.1422.v1
Subject: Engineering, Electrical And Electronic Engineering Keywords: MEMS; positioning system; pyroelectric infrared sensors; zinc oxide
Online: 20 July 2023 (11:22:58 CEST)
Infrared sensors incorporating suspended zinc oxide (ZnO) pyroelectric films and thermally-insulated silicon substrates are fabricated using conventional MEMS-based thin-film deposition, photolithography, and etching techniques. The responsivity of the pyroelectric film is improved through annealing at 500℃ for 4 h. The voltage response of the fabricated sensors is evaluated experimentally for a substrate thickness of 1 µm over a sensing range of 30 cm. The results show that the voltage signal varies as an inverse exponential function of the distance. A positioning system based on three infrared sensors is implemented in LabVIEW. It is shown that the position estimates obtained using the proposed system are in excellent agreement with the actual locations. In general, the results presented in this study provide a useful source of reference for the further development of MEMS-based pyroelectric infrared sensors.
COMMUNICATION | doi:10.20944/preprints202104.0119.v1
Subject: Engineering, Electrical And Electronic Engineering Keywords: MoS2; photodetector; Raman; drop casting; infrared; thin film
Online: 5 April 2021 (12:21:57 CEST)
In this work, a highly efficient, molybdenum disulfide (MoS2) based near infrared (NIR) heterojunction photodetector is fabricated on a Si substrate using a cost-effective and simple drop casting method. A non-stoichiometric and inhomogeneous MoS2 layer with a S/Mo ratio of 2.02 is detected using energy dispersive X-ray spectroscopy and field emission scanning electron microscope analysis. Raman shifts are noticed at 382.42 cm-1 and 407.97 cm-1, validating MoS2 thin film growth with a direct bandgap of 2.01 eV. The fabricated n-MoS2/p-Si photodetector is illuminated with a 785 nm laser at different intensities, and demonstrate the ability of the photodetector to work in both regions, the forward biased and reverse biased from above 1.5 V and less than -1.0 V. The highest responsivity, R is calculated to be 0.52 A/W while the detectivity D* is 4.08 x 10^10 Jones for an incident light intensity of 9.57 mW/cm2. The minimum rise and fall times are calculated as 1.77 ms and 1.31 ms for an incident laser power of 9.57 mW/cm^2 and 6.99 mW/cm^2 respectively at a direct current bias voltage of 10 V. The demonstrated results are promising for the low-cost fabrication of a thin MoS2 film for photonics and optoelectronic device applications.
ARTICLE | doi:10.20944/preprints202007.0655.v1
Subject: Chemistry And Materials Science, Biomaterials Keywords: dialysis membrane; ectosomes; exosomes; FTIR; infrared spectroscopy; purification
Online: 27 July 2020 (00:46:38 CEST)
Recent years brought great focus in the field of development of extracellular vesicles (EVs) based drug-delivery systems. Considering possible applications of EVs as a drug carriers the isolation process is a crucial step. To solve problems related with EV isolation, we created and validated a new EVs isolation method – Low Vacuum Filtration (LVF) and compared it with two commonly applied procedures - differential centrifugation (DC) and ultracentrifugation (UC). EVs isolated from endothelial cells culture media have been characterized by a) transmission electron microscopy (TEM) b) nanoparticle tracking analysis (NTA), c) western blot and d) Fourier-Transform Infrared Spectroscopy (FTIR). Additionally, the membrane surface have been imaged with Environmental Scanning Electron Microscopy (ESEM). We showed that LVF is reproducible and efficient method for EVs isolation form conditioned media. Additionally, we observed correlation between ATR-FTIR spectra quality and the EVs and proteins concentration. ESEM imaging confirmed that actual pore diameter are close to the values calculated theoretically. LVF method is an easy, fast and inexpensive EVs isolation method which allows for isolation of both ectosomes and exosomes from high volume sources with good repeatability. We think that it could be an efficient alternative for commonly applied methods.
ARTICLE | doi:10.20944/preprints201903.0018.v1
Subject: Physical Sciences, Optics And Photonics Keywords: Fast Forward Model, Infrared, Emissivity Spectrum, Satellite, Validation
Online: 4 March 2019 (08:42:15 CET)
Timely processing of observations from hyper-spectral imagers, such as SEVIRI (Spinning Enhanced Visible and Infrared Imager), largely depends on fast radiative transfer calculations. This paper mostly concerns the development and implementation of a new forward model for SEVIRI to be applied to real time processing of infrared radiances for the physical retrieval of surface temperature and emissivity. The new radiative transfer model improves computational time by a factor of ≈ 7 compared to the previous versions and makes it possible to process SEVIRI data at nearly real time. The new forward model has been applied for the simultaneous retrieval of surface temperature and emissivity in three infrared channels (8.7, 10.8, 12 μm). The inverse scheme relies on a Kalman filter approach, which allows us to exploit a sequential processing of SEVIRI observations. Based on the new forward model, the paper also presents a validation retrieval performed with in situ observations acquired during a field experiment carried out in 2017 at Gobabeb (Namib desert) validation station. Furthermore, a comparison with IASI (Infrared Atmospheric Sounder Interferometer) emissivity retrievals has been performed as well. It has been found that the retrieved emissivities are in good agreement with each other and with in situ observations, i.e. average differences are generally well below 0.01.
ARTICLE | doi:10.20944/preprints202309.1205.v1
Subject: Computer Science And Mathematics, Analysis Keywords: Fuzzy near best approximation; Direct sum; Tensor product; Fuzzy norm
Online: 19 September 2023 (08:15:15 CEST)
Given a fuzzy normed space $ \left( X,N \right) $, we will introduce the notion of fuzzy near best approximation within a relative distance $ \rho \geq 0 $. Some basic properties are characterized and also many examples for illustration are presented.
ARTICLE | doi:10.20944/preprints202305.1629.v1
Subject: Engineering, Aerospace Engineering Keywords: Earth’s near space; Biological Samples Exposure; Mars; Venus; atmosphere; astrobiology
Online: 23 May 2023 (08:47:39 CEST)
Earth’s near space is a region between 20 and 100 km above sea level, which is characterized by low temperature, low atmospheric pressure, harsh radiation, and extreme dryness. These conditions are analogous to the surface of Mars and the atmosphere of Venus, and thus make it a unique natural lab for astrobiologists. To address the important astrobiological questions of the effects of the near space environmental conditions on biology and of the survival strategies of representative organisms in this planetary analog, teams from the Chinese Academy of Sciences have developed a scientific balloon platform named the Chinese Academy of Sciences Balloon-Borne Astrobiology Platform (CAS-BAP) and carried out a series of experiments in lower near space since 2019. Here, we describe the Biological Samples Exposure Payload (BIOSEP) loaded on CAS-BAP with respect to its structure and function. The primary role of BIOSEP is to expose biological/chemical samples to the planetary analog environments of Earth’s lower near space. Exposed samples will be returned to laboratories for morphological, physiological, chemical, and genetic analyses. The development of BIOSEP and associated biological exposure experiments will improve our understanding of the livelihood of potential Mars lives and the potential habitability of the atmosphere regions of other planets in the Solar System and beyond.
ARTICLE | doi:10.20944/preprints201807.0109.v1
Subject: Physical Sciences, Optics And Photonics Keywords: photonic crystal; nanocomposite; epsilon near zero material; Tamm plasmon polariton
Online: 6 July 2018 (08:18:21 CEST)
The spectral properties of a one-dimensional photonic crystal bounded by a resonant absorbing nanocomposite layer with the near-zero permittivity have been studied. The problem of calculating the transmittance, reflectance, and absorptance spectra of such structures at the normal and oblique incidence of light has been solved. It is shown that, depending on the permittivity sign near zero, the nanocomposite is characterized by either metallic or dielectric properties. For the first time, the possibility of simultaneous formation of the Tamm plasmon polariton at the photonic crystal/metallic nanocomposite interface and the localized state similar to the defect mode with the field intensity maximum inside the dielectric nanocomposite layer is demonstrated. Specific features of field localization at the Tamm plasmon polariton and defect mode frequencies are analyzed.
ARTICLE | doi:10.20944/preprints201804.0039.v1
Subject: Engineering, Electrical And Electronic Engineering Keywords: inverted F antenna; near field; radiation pattern; parasitic element; multiband
Online: 3 April 2018 (15:56:01 CEST)
The Inverted F Antenna (IFA) with the parasitic element on a finite conducting plane is proposed in the range frequency of 0.1 to 5.5 GHz and its characteristics are analyzed numerically. In this research, the parasitic element and the main IFA are investigated to obtain the resonance frequency for multiband operation purposes. The parasitic element is placed beneath adjusted to the main IFA to derive more frequency bands. The distance between the parasitic element and main horizontal element extremely affects the performance of the IFA. It is found that when the parasitic element is located closer to the conducting plane, this element is coupled by the current on the conducting plane. Consequently, the return loss bandwidth becomes narrower. Therefore, the gain of the proposed IFA becomes a bit higher. The antenna gain is about 8.21 dB at band #3 (λ1.747), 7.43 dB at band #5 (λ2.967) and 8.82 dB at band #6 (λ4.023). This occurs when the calculation condition is antenna height h1 = 23 mm, h2 = 21 mm, horizontal antenna elements L = 173.2 mm, L1 = 140.9 mm and Lp = 152 mm, shorted element Ls = 30.7 mm, the distance between parasitic element and shorted element pyl = 5 mm. While the size of conducting plane is considered pxp+pxm by pyp+pym as 57.5+57.5 mm by 200+50 mm. In the numerical analysis, the electromagnetic simulator WIPL-D based on Method of Moment is used. The results show that the proposed IFA has UHF and SHF channel receiver which are suitable for advanced wireless service (band #3), mobile phones, Bluetooth, maritime service, radiolocation service (band #5) and radars, mobile phones, commercial wireless LAN (band #6).
ARTICLE | doi:10.20944/preprints202305.0985.v1
Subject: Chemistry And Materials Science, Biomaterials Keywords: gold nanoparticles; phospholipids; biomedical applications; membrane fluidity; infrared spectroscopy
Online: 15 May 2023 (07:09:52 CEST)
Gold nanoparticles (AuNPs) are promising candidates in various biomedical applications such as sensors, imaging, and cancer therapy. Understanding the influence of AuNPs on lipid membranes is important to assure their safety in the biological environment and to improve their scope in nanomedicine. In this regard, the present study aims to analyze the effects of different concentrations (0.5, 1, and 2 w %) of dodecanethiol functionalized hydrophobic AuNPs on the structure and fluidity of zwitterionic 1-stearoyl-2-oleoyl-sn-glycerol-3-phosphocholine (SOPC) lipid bilayer membranes using Fourier transform infrared (FTIR) spectroscopy and fluorescent spectroscopy. The size of AuNPs was found to be 2.2 ± 1.1 nm using transmission electron microscopy. FTIR results have shown that the AuNPs induced a slight shift in methylene stretching bands, while the band positions of carbonyl and phosphate group stretching were unaffected. Temperature-dependent fluorescent anisotropy measurements have shown that the incorporation of AuNPs up to 2 w % did not affect the lipid order in membranes. Overall, these results indicate that the hydrophobic AuNPs in the studied concentration did not cause any significant alterations in the structure and membrane fluidity, which suggests the suitability of these particles to form liposome-AuNP hybrids for diverse biomedical applications including drug delivery and therapy.
ARTICLE | doi:10.20944/preprints202305.0100.v1
Subject: Computer Science And Mathematics, Computer Vision And Graphics Keywords: Infrared small targets; Counter-drones; Progressive fusion; Lightweight network
Online: 3 May 2023 (05:49:13 CEST)
The rampant misuse of drones poses a serious threat to national security and human life. Currently, the CNN method has been widely used in drone detection. However, there is a challenge that traditional CNN cannot cope with, which is small drone targets often have reduced amplitude or even lost features in infrared images. This paper proposes a Progressive Feature Fusion Network (PFFNet) that gradually increases the response amplitude of the target in the deep network. The Feature Selection Model (FSM) is designed to improve the utilisation of the output coding graph and enhance the feature representation of the target in the network. A lightweight segmentation head is also designed to achieve progressive feature fusion with multi-layer outputs. Experimental results show that the proposed algorithm can achieve low duration and high accuracy in drone target detection. On the public dataset, the IoU is improved by 2.53% and the detection time is reduced by 81.03%.
ARTICLE | doi:10.20944/preprints202304.0598.v1
Subject: Engineering, Electrical And Electronic Engineering Keywords: short wave infrared; LiDAR; photodetector array; dark current detection
Online: 20 April 2023 (03:09:20 CEST)
The shortwave infrared Ge-Si photodetector will become the core device of the LiDAR optical receiver. In order to meet the urgent demand for photodetectors in the LiDAR field, we have designed and produced a 32×32 pixel Ge-Si photodetector array proposed and developed to meet the performance requirements of the detector array. A dark current detection system for fast scanning and detecting large-scale Ge-Si detector arrays is proposed and developed to achieve rapid detection of dark current in each pixel of the detector. The system was used to validate the main performance indicators of the detector array we designed, achieving rapid discrimination of array performance and rapid localization of damaged pixels. The scanning test results show that the average dark current of the detector array chip we designed is at the nano ampere level, and the proportion of bad points is less than 1%. The consistency of the array chip is high, which can meet the requirements of light detection at the receiving end of the LiDAR. This work laid the foundation for our subsequent development of a LiDAR prototype system.
ARTICLE | doi:10.20944/preprints202201.0262.v1
Subject: Environmental And Earth Sciences, Atmospheric Science And Meteorology Keywords: Stereo winds; midwave infrared; weather satellite; atmospheric motion vectors
Online: 18 January 2022 (15:15:47 CET)
The Compact Midwave Imaging System (CMIS) is a wide field of view, multi-angle, multi-spectral pushframe imager that relies on the forward motion of the satellite to create a two-dimensional (2D) image swath. An airborne demonstration of CMIS was successfully completed in January-February 2021 on the NASA Langley Research Center Gulfstream III. The primary objective of the four-flight campaign was to demonstrate the capability of this unique instrument to perform stereo observations of clouds and other particulates (e.g. smoke) in the atmosphere. It is shown that the midwave infrared (MWIR) spectral bands of CMIS provide a unique 24/7 capability with high resolution for accurate stereo sensing. The instrument relies on new focal plane array (FPA) technology, which provides excellent sensitivity at much warmer detector temperatures than traditional technologies. This capability enabled a compact, low-cost design that can provide atmospheric motion vectors and cloud heights to support requirements for atmospheric winds in the 2017-2027 Earth Science Decadal Survey. Applications include day/night observations of the planetary boundary layer, severe weather, and wildfires. A comparison with current space-based earth science instruments demonstrates that the SWIR/MWIR multi-spectral capability of CMIS is competitive with larger, more expensive instrumentation. Imagery obtained over a controlled burn and operating nuclear power plant demonstrated the sensitivity of the instrument to temperature variations. The system relies on a mature stereoscopic imaging technique applied to the same scene from two independent platforms to unambiguously retrieve atmospheric motion vectors (AMVs) with accurate height assignment. This capability has been successfully applied to geostationary and low-earth orbit satellites to achieve excellent accuracy. When applied to a ground-point validation case, the accuracy for the CMIS aircraft observations was 20 m and 0.3 m/s for cloud heights and motion vectors, respectively. This result was confirmed by a detailed error analysis with analytical and covariance models. The results for CMIS cases with underflights of Aeolus, CALIPSO and Aqua provided a good validation of expected accuracies. The paper also showed the feasibility of accommodating CMIS on CubeSats to enable multiple instruments to be flown in a leader-follower mode.
COMMUNICATION | doi:10.20944/preprints202012.0405.v1
Subject: Engineering, Automotive Engineering Keywords: infrared spectroscopy; visible image; support vector machine; olive quality.
Online: 16 December 2020 (11:18:07 CET)
The color and NIR spectrum are key to build an oil estimation model, thus it requires individual olives clustering before the Sohlext oil extraction method can be applied. The objective was to analyze an OC estimation model of individual olives, based on cluster of similar color and NIR spectrum in different combination of the first and/or the second season. This study was performed with Chilean Arbequina olives in 2016 and 2017. The descriptor of the cluster consisted of the 3 color channels of c1, c2, c3 color model plus 11 reflectance points between 1710 and 1735 nm of each olive, normalized with the Z-score index. Clusters of similar color and NIR spectrum were formed with the k-means++ algorithm, leaving a sufficient amount of olives to be able to perform the Sohlext analysis of OC, as reference value. The estimation models were based on the Support Vector Machine. The test was carried out with the Leave One-Out Cross Validation in different training-testing combinations. The best model predicted the OC with 6% and 13%deviation respect to the real value in one season by itself and when one season tested with another season, respectively. The use of clustering in estimation model is discussed.
ARTICLE | doi:10.20944/preprints202008.0337.v1
Subject: Medicine And Pharmacology, Medicine And Pharmacology Keywords: thermal sensation; ageing; infrared thermography; frailty; assessment; comfort; extremities
Online: 15 August 2020 (04:56:17 CEST)
The temperature of the indoor environment is important for health and wellbeing especially at the extremes of age. The study aim was to undertsand the relationship between self-reported thermal sensation and extremity skin temperature in care home residents with and without dementia. The Abbreviated Mental Test (AMT) was used to discriminate residents to two categories, those with and those without dementia. After acclimatisation, measurements included: tympanic membrane temperature, thermal sensation rating followed by infrared thermal mapping of non-dominant hand and forearm. Sixty-nine afebrile adults (60-101 years of age) were studied in groups of two to five, in mean ambient temperatures of 21.4oC-26.6oC (median 23.6oC). Significant differences were observed between groups; thermal sensation rating (p=0.02), tympanic temperature (p=0.01), fingertip skin temperature (p=0.01) and temperature gradients; fingertip-wrist p=0.001 and fingertip-distal forearm, p=0.001.
ARTICLE | doi:10.20944/preprints202003.0172.v1
Subject: Physical Sciences, Astronomy And Astrophysics Keywords: molecular biosignatures; Mars; UV irradiation; infrared spectroscopy; life detection
Online: 10 March 2020 (14:10:19 CET)
The search for molecular biosignatures at the surface of Mars is complicated by an intense irradiation in the mid- and near- ultraviolet (UV) spectral range for several reasons: (i) many astrobiologically relevant molecules are electronically excited by efficient absorption of UV radiation and rapidly undergo photochemical reactions; (ii) even though the penetration depth of UV radiation is limited, aeolian erosion continually exposes fresh material to radiation; and (iii) UV irradiation generates strong oxidants such as perchlorates that can penetrate deep into soils and cause subsurface oxidative degradation of organics.As a consequence, it is crucial to investigate the effects of UV radiation on organic molecules embedded in mineral matrices mimicking the martian soil, in order to validate hypotheses about the nature of the organic compounds detected so far at the surface of Mars by the Curiosity rover, as well as organics that will be possibly found by the next rover missions Mars 2020 and ExoMars 2020. In addition, studying the alteration of possible molecular biosignatures in the martian environment will help to redefine the molecular targets for life detection missions and devise suitable detection methods.Here we report the results of mid-UV irradiation experiments of Mars soil analog samples obtained adsorbing relevant organic molecules on a clay mineral that is quite common on Mars, i.e. montmorillonite, doped with 1 wt% of magnesium perchlorate. Specifically, we chose to investigate the photostability of a plausible precursor of the chlorohydrocarbons detected on Mars by the Curiosity rover, namely phthalic acid, along with the biomarkers of extant life L-phenylalanine and L-glutamic acid, which are proteomic amino acids, and adenosine 5’-monophosphate, which is a nucleic acid component.We monitored the degradation of these molecules adsorbed on montmorillonite through in situ spectroscopic analysis, investigating the reflectance properties of the samples in the Near InfraRed (NIR) spectral region. Such spectroscopic characterization of molecular alteration products provides support for two upcoming robotic missions to Mars that will employ NIR spectroscopy to look for molecular biosignatures, through the instruments SuperCam on board Mars 2020, ISEM, Ma_Miss and MicrOmega on board ExoMars 2020.
BRIEF REPORT | doi:10.20944/preprints202002.0332.v1
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: nucleic acids; airborne microorganisms; far infrared radiation; RNA virus
Online: 23 February 2020 (15:51:12 CET)
Emergence of zoonotic-human pathogens is proven to be a lethal threat to public health, and RNA virus including influenza viruses, severe acute respiratory syndrome coronavirus, middle east respiratory syndrome coronavirus, Wuhan coronavirus (COVID-19), plays a pivotal role. As those viruses as airborne microorganisms spread mainly by tiny airborne particles, it is important to de-active those airborne particles before their entry into human bodies. In this study, we investigated the effect of far infrared (FIR) radiation on inhibition of airborne microorganisms. The result confirmed that double stand DNA from airborne microorganisms were stable under mild FIR radiation. However, single strand RNA from them was found to be sensitive to FIR radiation, indicating that RNA virus in airborne particles is instable under FIR radiation. Based on this observation, two models on usage of FIR radiation to prevent RNA virus transmission and cure RNA virus infection were proposed, implying that FIR radiation might be a cheap, convenient, and efficient method in clinic to treat RNA virus.