Subject: Engineering, Biomedical & Chemical Engineering Keywords: pulse wave analysis; mental stress; harmonic analysis; Eastern pulse reading
Online: 10 September 2019 (05:19:15 CEST)
Background: This research presents the use of photoplethsmography combined with Traditional Tibetan Pulse reading for the estimation of the three energies of a person: Activity, Transformation and Stability. The growing interest to revive traditional finger pulse reading attests of the need to find alternative ways to approach complex multi-source diseases as well as individualised diagnostic wearable or portable cost effective systems. Method: Our work is presented in two studies. The first study presents the development of the technique of photoplethsmography to classify the three energies. The second study presents a validation of this methodology on mental stress and relaxation. Results: Energies classification achieved a sensitivity above 85% and specificity above 72%. Mental stress and relaxation could be significantly discriminated from baseline condition. Harmonic analysis gave further insights into the dynamic of the pulse wave under stress/relaxation. Conclusion: The photoplethsmogram contains information pertaining to the mental and physiological state of a person as interpreted with the Eastern energies concepts. The implication of this work points towards a holistic understanding and impact of human activities, health and its environment.
ARTICLE | doi:10.20944/preprints201804.0195.v1
Subject: Earth Sciences, Atmospheric Science Keywords: lightning flash; return stroke; K change; chaotic pulse train; regular pulse train
Online: 16 April 2018 (08:11:25 CEST)
General characteristics of K changes together with their fine structure associated with ground flashes in Sri Lanka in the tropics are presented. It is found that on average there are about 2 K changes associated with each return stroke. Analysis of the fine structure of the K changes shows that the K change is a chaotic pulse burst. Some of these chaotic pulse bursts start and the others end as a regular pulse bursts. Sometimes the chaotic part occurs in between two regular pulse bursts. This is in agreement with the recent published results that claim that chaotic pulse bursts are a random superposition of regular pulse bursts. The results show that the small step fields identified in the literature as K changes are the static fields associated with these pulse bursts.
ARTICLE | doi:10.20944/preprints202012.0192.v1
Subject: Physical Sciences, Optics Keywords: nonlinear Schrödinger equation system; few-mode propagation; Kerr effect; Raman scattering; dispersion; implicit/explicit Crank–Nicolson scheme; pulse chirping, second-order dispersion, third-order dispersion, chirp pulse, optical pulse compression, pulse collapse
Online: 8 December 2020 (09:57:12 CET)
This paper discusses approaches to the numerical integration of the coupled nonlinear Schrödinger equations system in case of few-mode wave propagation. The wave propagation assumes the propagation of up to nine modes of light in an optical fiber. In this case, the light propagation is described by the non-linear coupled Schrödinger equation system, where propagation of each mode is described by own Schrödinger equation with other modes interactions. In this case, the non-linear coupled Schrödinger equation system solving becomes increasingly complex, because each mode affects the propagation of other modes. The suggested solution is based on the direct numerical integration approach, which is based on a finite-difference integration scheme. The well-known explicit finite-difference integration scheme approach fails, due to the non-stability of the computing scheme. Due to this fact, the combined explicit/implicit finite-difference integration scheme, based on the implicit Crank–Nicolson finite-difference scheme, is used. It allows ensuring the stability of the computing scheme. Moreover, this approach allows separating the whole equation system on the independent equation system for each wave mode at each integration step. Additionally, the algorithm of numerical solution refining at each step and the integration method with automatic integration step selection are used. The suggested approach has performance gains (or resolutions) up to three or more orders of magnitude in comparison with the split-step Fourier method due to the fact that there is no need to produce direct and inverse Fourier transforms at each integration step. The main advantage of the proposed method is the ability to calculate the propagation of an arbitrary number of modes in the fiber.
ARTICLE | doi:10.20944/preprints201808.0417.v1
Subject: Materials Science, Polymers & Plastics Keywords: CFRP; pulse ultrasonic method; cure monitoring
Online: 23 August 2018 (15:10:16 CEST)
This article discusses the results of a series of experiments on pulse ultrasonic cure monitoring of carbon fiber reinforced plastics applied to the pultrusion process. The aim of this study is to validate the hypothesis that pulse ultrasonic cure monitoring can be applied a) for profiles having small cross sections such as 7x0.5 mm and b) within the environment of the pultrusion process. Ultrasonic transducers are adhesively bonded to the pultrusion tool as actuators and sensors. The time-of-flight and the amplitude of an ultrasonic wave are analyzed to deduce the current curing state of the epoxy matrix. The experimental results show that ultrasonic cure monitoring is indeed applicable even to very thin cross sections. However, significant challenges can be reported when the techniques are used during the pultrusion process.
ARTICLE | doi:10.20944/preprints201903.0061.v2
Subject: Physical Sciences, General & Theoretical Physics Keywords: Fluid Mechanic, Pulse Energy Tensor, General Relativity
Online: 17 June 2019 (09:35:44 CEST)
This paper is to summarize the involvement of the stress energy tensor in the study of fluid mechanics. In the first part we will see the implication that carries the stress energy tensor in the framework of general relativity. In the second part, we will study the stress energy tensor under the mechanics of perfect fluids, allowing us to lead third party in the case of Newtonian fluids, and in the last part we will see that it is possible to define space-time as a no-Newtonian fluids.
ARTICLE | doi:10.20944/preprints201901.0191.v1
Subject: Physical Sciences, Optics Keywords: ultrashort pulses; dispersion; pulse distortion; optical communications
Online: 20 January 2019 (09:17:07 CET)
Ultrashort pulses are severely distorted even by low dispersive media. While the mathematical analysis of dispersion is well known, the technical literature focuses on pulses, which keep their shape: Gaussian and Airy pulses. However, the cases where the shape of the pulse is unaffected by dispersion is the exception rather than the norm. It is the object of this chapter to present a variety of pulses profiles, which have analytical expressions but can simulate real-physical pulses with greater accuracy. In particular, the dynamics of smooth rectangular pulses, physical Nyquist-Sinc pulses, and slowly rising but sharply decaying ones (and vice-versa) are presented. Besides the usage of this chapter as a handbook of analytical expressions for pulses' propagations in a dispersive medium, there are several new findings. The main ones are: Analytical expressions for the propagation of chirped rectangular pulses, which converge to extremely short pulses; analytical approximation for the propagation of Super-Gaussian pulses; the propagation of Nyquist Sinc Pulse with smooth spectral boundaries and an analytical expression for a physical realization of an attenuation compensating Airy pulse.
ARTICLE | doi:10.20944/preprints201810.0471.v1
Subject: Engineering, Electrical & Electronic Engineering Keywords: corona discharge; Trichel pulse; multi-needle; EM radiation
Online: 22 October 2018 (05:38:30 CEST)
Negative corona discharges occur widely in high voltage transmission lines and charged aircraft, which can cause strong electromagnetic interference. Negative corona discharge is typically performed simultaneously at multiple discharge points. In this study, the current and its EM radiation characteristics of single-needle and multi-needle negative corona discharge in different conditions were tested. The current and electromagnetic radiation characteristics of the two discharge structures were compared. The dipole radiation model was established to analyze the EM radiation characteristics of the negative corona discharge.The results show that, It is only when the voltage reaches a certain threshold that the current and electromagnetic radiation fields of the multi-needle discharge structure will be superimposed and their amplitudes will increase significantly. The frequency of electromagnetic radiation signal does not change with the number of needles, cathode geometry and applied voltage, but only depends on ambient pressure. It provides a basis for detecting corona discharge sources under different conditions.
ARTICLE | doi:10.20944/preprints201809.0308.v1
Subject: Engineering, Automotive Engineering Keywords: PLC programming, hydraulic pulse system, state machine programming,
Online: 17 September 2018 (12:19:56 CEST)
In the paper is described the control electronics for an industrial pneumatic – hydraulic system based on a low-cost PLC. The developed system is a hydraulic pulse system and it generates series of high pressure hydraulic pulses (max. 200 bar). We describe requirements, an overall concept of the embedded control system, user interface, security features and network connectivity. In the description of the software solution we describe implementation of hierarchical ordered program threads (multithreaded program) and main control state machine. At the conclusion, we describe the calibration method of the system and calibration curves and we present the schematic diagram and a photo of a functional prototype of the system.
ARTICLE | doi:10.20944/preprints202301.0496.v1
Subject: Chemistry, Analytical Chemistry Keywords: Heavy metal; Differential pulse voltammograms; Cyclic Voltammetry; Bismuth; Nanoparticle
Online: 27 January 2023 (06:51:20 CET)
Bismuth oxides are well-known electro-catalysts in fuel cells systems; they are usually used as anodic materials for the oxidation of low molecular weight alcohols. The utilization of BiO2 and MnO2 as catalysts in the pharmaceutical analysis is analytical method for the determination of heavy metal antibacterial agents in Pharmaceutical Dosage form is developed. The method is based on the voltammetric determination of heavy metal using Bidified platinum electrode by Bismuth oxide. The two components are oxidized at the Bidified electrode surface with the development of current that is linearly proportional to their concentrations in the range of 7.04*10-7- 1*10-3 M heavy metal. The oxidation reaction of the two components is pH-dependent, in which the buffer used is Britton-Robinson at pH = 7.00 where maximum peak current and maximum peak separation is obtained. The regression factors obtained from the calibration curves are 0.9812. The method of analysis was validated, where the limit of detection (LOD) and the limit of quantitation (LOQ) were calculated to be 1.44*10-4 M, 4.36*10-4 M and 1.27*10-4 M, 3.84*10-4 M respectively, the percentage recovery of both components was also calculated to 77 % for heavy metal.
CASE REPORT | doi:10.20944/preprints202006.0260.v1
Subject: Medicine & Pharmacology, Other Keywords: SARS-CoV-2; COVID-19; pulse therapy; corticosteroids; immunoglobulin
Online: 21 June 2020 (11:06:08 CEST)
Three patients with severe life-threatening COVID-19 who failed to achieve substantial improvement on tocilizumab, received pulse therapy with corticosteroids (methylprednisolone, 1000 mg/day IV for three consecutive days) and intravenous immunoglobulin (20 g/day IV). This was associated with a prompt resolution of respiratory failure, elimination of cytokine release syndrome, and reversal of pulmonary CT changes. The treatment was generally safe and well tolerated. There was no evidence of protracted persistence of the virus in the patients who received pulse therapy. Randomized controlled trials are necessary to specify the efficacy and safety of high-dose methylprednisolone and intravenous immunoglobulin in the treatment of severe life-threatening COVID-19 separately or in combination.
ARTICLE | doi:10.20944/preprints202006.0177.v1
Subject: Chemistry, Analytical Chemistry Keywords: Hydrochlorothiazide; Differential pulse voltammograms; Cyclic Voltammetry; Molybdenum; Modified electrode
Online: 14 June 2020 (14:40:00 CEST)
Molybdenum oxides is well-known electro-catalysts in fuel cells systems, they are usually used as anodic materials for the oxidation of low molecular weight alcohols. The utilization of Mo as catalysts in the pharmaceutical analysis is not common yet. In this study, bare glassy carbon electrodes were modified by the oxides by means of electrochemical deposition and the modified electrodes were used as catalysts for the electrochemical oxidation of hydrochlorothiazide (HCT). Well-resolved anodic peaks were reported for the analyzed pharmaceuticals when the Mo/GCE was utilized for the analysis of HCT. Analytical performance of the modified electrodes was evaluated based on the following statistical parameters; linearity ranges, correlation coefficients, limits of detection and quantitation, and recovery values. The prepared electrodes were used for the determination of the active ingredients in their pharmaceutical formulations and the reported activity was correlated to influence of the utilized pH on both structures of the used electrodes and the detected analytes.
ARTICLE | doi:10.20944/preprints202103.0745.v1
Subject: Life Sciences, Biochemistry Keywords: abdominal aortic aneurysm; pulse wave analysis; one-dimensional modelling; in silico pulse waves; machine learning; recurrent neural network; long short-term memory
Online: 30 March 2021 (14:05:44 CEST)
An abdominal aortic aneurysm (AAA) is usually asymptomatic until rupture, which is associated with extremely high mortality. Consequently, early detection of AAAs is of paramount importance in reducing mortality; however, most AAAs are detected by medical imaging incidentally. The aim of this study was to investigate the feasibility of machine learning-based pulse wave (PW) analysis for the early detection of AAAs using a database of in silico PWs. PWs in the large systemic arteries were simulated using one-dimensional blood flow modelling. A database of in silico PWs representative of subjects (aged 55, 65 and 75 years) with different AAA sizes was created by varying the AAA-related parameters with major impacts on PWs – identified by parameter sensitivity analysis – in an existing database of in silico PWs representative of subjects without AAA. Then, a machine learning architecture for early detection of AAAs was proposed, which was trained and tested using the new in silico PW database. The parameter sensitivity analysis revealed that the AAA maximum diameter and stiffness of the large systemic arteries were the dominant AAA-related biophysical properties that significantly influence the PW. The simulated PW indexes extracted from the database showed that the PW was not only influenced by the presence of an AAA but was also significantly affected by multiple cardiovascular parameters that compromised the detection of AAAs by using individual PW indexes. Alternatively, the trained machine learning model performed well in classifying normal and AAA conditions using digital photoplethysmogram PWs from the database. These findings suggest that machine learning-based PW analysis is a promising approach for AAA screening using PW signals acquired by wearable devices.
Subject: Physical Sciences, Acoustics Keywords: Photonic crystal waveguide; Pulse acceleration; Self-steepening; Self-phase modulation
Online: 28 June 2021 (11:44:55 CEST)
Based on the sensitive sum frequency generation cross-correlation frequency-resolved optical gating (SFG-XFROG) measurement setup, besides the pulse broadening, blue shift, red shift and obvious pulse acceleration, we observed the soliton evolution when the low energy soliton pulse with wavelength of 1555nm transmit through the Si photonic crystal waveguide. The measurements were nicely matched with the simulation results, which are achieved with an optimized nonlinear Schrödinger equation (NLSE) modeling. The effects of various parameters of the silicon photonic crystal waveguides and the incident pulses on the pulse transmission were also analyzed, including the nonlinear effects and dispersion such as the self-phase modulation (SPM), self-steepening (SS) and intra-pulse Raman scattering(IRS). The results help us understand further the ultra-fast nonlinear dynamics of soliton in silicon-based waveguides, and even open a novel way for soliton-based functional elements in CMOS-compatible platforms.
ARTICLE | doi:10.20944/preprints201905.0111.v1
Subject: Materials Science, Metallurgy Keywords: pulse volume; signal noise ratio; automated ultrasonic testing; simulation software
Online: 9 May 2019 (12:47:50 CEST)
Titanium’s accelerating usage in global markets is attributable to its distinctive combination of physical and metallurgical properties. The key to best utilizing titanium is to exploit these characteristics, especially as they complement one another in a given application, rather than to just directly substitute titanium for another metal. Titanium alloy are extensively used in aerospace applications such as components in aero-engines and space shuttles, mainly due to their superior strength to weight ratio. For these demanding applications functionality and reliability of components are of great importance. To increase flight safety, higher sensitivity inspections are sought for rotating parts. Increased sensitivity can be applied at the billet stage, the forging stage, or both. Inspection of the forging geometry affords the opportunity to apply the highest sensitivity due to the shorter material paths when compared to those required for billet inspections. Forging inspection is typically performed for titanium (Ti) rotating parts with immersion inspection and fixed-focus, single-element transducers. Increased gain is required with depth because the ultrasonic beam attenuates with distance and diverges beyond the focus position that is placed near the surface. The higher gain that is applied with depth has the effect of increasing the UT noise with depth. The relationships between the UT noise, selection of the examination technique and the smallest detectable defect are presented in this material.
CASE REPORT | doi:10.20944/preprints201810.0169.v2
Subject: Medicine & Pharmacology, Pediatrics Keywords: bird fancier’s lung (BFL); hypersensitivity pneumonitis (HP); child; pulse steroid
Online: 11 October 2018 (05:08:41 CEST)
Bird Fancier’s Syndrome is a rare, non-atopic immunologic response to repeated or intense inhalation of avian (bird) proteins/antigens found in the feathers or droppings of many species of birds, which leads to an immune mediated inflammatory reaction in the respiratory system. Although this is the most common type of hypersensitivity pneumonitis reported in adults, it is one of the classification of a rare subtype of interstitial lung disease that occurs in the pediatric age group of which few case reports are available in the literature. The pathophysiology of hypersensitivity pneumonitis is complex; numerous organic and inorganic antigens can cause immune dysregulation, leading to an immune related antigen-antibody response (immunoglobulin G–IgG- against the offending antigen). Diagnosing Bird Fancier’s disease in the pediatric age group is challenging, history of exposure is usually missed by health care providers, symptoms and clinical findings in such cases are nonspecific and often misdiagnosed during the acute illness with other common diseases such asthma, or acute viral lower respiratory tract infection, and the lack of standardization of criteria for diagnosing such condition, or sensitive radiological or laboratory test. Treatment, on the other hand, is also controversial. Avoidance of the offending antigen could be the sole or most important part of treatment, particularly in acute mild and moderate cases. Untreated cases can result in irreversible lung fibrosis. In this case report, we highlight how children presenting with an acute viral lower respiratory tract infection can overlap with hypersensitivity pneumonitis. Early intervention with pulse steroids markedly improves the patient’s clinical course.
ARTICLE | doi:10.20944/preprints201808.0206.v1
Subject: Medicine & Pharmacology, Other Keywords: cardiovascular variability; heart-rate variability; peripheral arterial disease; photoplethysmography; pulse
Online: 10 August 2018 (13:43:45 CEST)
Photoplethysmography (PPG) is a simple-to-perform vascular optics measurement technique that can detect changes in blood volume in the microvascular tissue bed. Beat-to-beat analysis of the PPG waveform enables the study of the variability of pulse features such as amplitude and pulse arrival time (PAT), and when quantified in the time and frequency domains, has considerable potential to shed light on perfusion changes associated with peripheral arterial disease (PAD). In this pilot study innovative multi-site bilateral finger and toe PPG recordings from 43 healthy control subjects and 31 PAD subjects were compared (recordings each at least 5 minutes, collected in a warm temperature-controlled room). Beat-to-beat normalized amplitude and PAT variability was then quantified in the time-domain using SD and IQR measures and in the frequency-domain bilaterally using Magnitude Squared Coherence (MSC). Significantly reduced normalized amplitude variability (healthy control 0.0384 (IQR 0.0217-0.0744) vs PAD 0.0160 (0.0080-0.0338) (p<0.001) and significantly increased PAT variability (healthy control 0.0063 (0.0052-0.0086) vs PAD 0.0093 (0.0078-0.0144) (p<0.001) was demonstrated in PAD using the time-domain analysis. Frequency-domain analysis demonstrated significantly lower MSC values across a range of frequency bands for PAD patients. These changes suggest a loss of right-to-left body side coherence and cardiovascular control in PAD. This study has also demonstrated the feasibility of using these measurement and analysis methods in studies investigating multi-site PPG variability for a wide range of cardiac and vascular patient groups.
ARTICLE | doi:10.20944/preprints201710.0137.v1
Subject: Medicine & Pharmacology, General Medical Research Keywords: influenza; pulse waves; incubation period; rapid diagnostic tests; coincidence analysis
Online: 20 October 2017 (09:54:02 CEST)
Viral infections have long been the biggest threat to human survival, and from a medical perspective, the development of noninvasive high-throughput screening methods that target the incubation period to either treat diseases or limit viral spread would be strikingly effective. Using this technology to target viral incubation periods would also be inexpensive to perform. The current study proposes to transform pulse signals into a rapid diagnostic test using “coincidence analysis” in the hope of preventing or reducing the symptoms of viral infections. The heart plays a critical role in calculating and supplying the needs of all tissues of the body. Pulse waves are pressurized signals in response to heart’s calculations and include all phases of the cardiac cycle, which maintains life and provides energy needed to perform tasks. Any small movement gives a corresponding signal to pulse waves. The current study investigated conclusive data on self-limiting infections, such as common cold. We used pulse wave, coincidence analysis technology to capture signals from individuals with common cold during the incubation period and investigated if particular characteristic signals could be applied to influenza during the incubation period. Preliminary work demonstrated that pulse waves could generate signals using this technology that would be worthwhile for future research. A small amount of analytical data from common cold existed previously. The data structure is based on the idea that a single pulse wave at differing physiological conditions would have slight modifications that would be amplified and presented by various geometrical shapes after extensive data are accumulated. These geometric shapes can then be sliced vertically or horizontally to extract data during different illness stages. The significance of these findings are impressive; from a personal or a public hygiene perspective, this analytical technology provides many benefits, such as rapid and precise decision-making that can be directly visualized or can be analyzed using software programs. Also, this technology also uses futuristic wearable technology that brings practical problem solving to physiology.
ARTICLE | doi:10.20944/preprints201704.0017.v1
Subject: Physical Sciences, Condensed Matter Physics Keywords: ZnO, pulse laser ablation (PLA), laser pulses, laser energy, nanoparticle
Online: 4 April 2017 (09:10:48 CEST)
In this work, zinc oxide (ZnO) thin film has been fabricated on glass substrate using pulse laser ablation (PLA) technique. The effect of laser pulses of 1000, 1500, 2000 pulses at laser energy 700 mJ as well as, laser energy of 600, 700, and 800 mJ at fixed laser pulses of 1500 pulse, with methanol as a solvent on the structural properties of prepared films using XRD, SEM and EDX. XRD results revealed that the ZnO thin films have hexagonal structure with polycrystalline in nature with preferred orientation of (002). Crystalline size was increased with the increasing of the pulses and at energy of 700 mJ and pulse of 1500 pulse seemed nanostructure like tree leaf. In addition, narrow FWHM and no phase change have been observed in all cases. SEM images showed that for all cases the films were homogenous with some island and cluster then cracking started to obtain with the increasing of increase the pulse number. EDX analysis showed that the prepared films were free of defects and contaminations.
ARTICLE | doi:10.20944/preprints202206.0299.v1
Subject: Medicine & Pharmacology, Cardiology Keywords: cardiovascular risk; lipids; NMR spectroscopy; pulse wave velocity; retinal vessel diameters
Online: 22 June 2022 (03:37:53 CEST)
Lipoproteins are important cardiovascular (CV) risk biomarkers. This study aimed to investigate the associations of lipoprotein subclasses with micro- and macrovascular biomarkers to better understand how these subclasses relate to atherosclerotic CV diseases. One hundred fifty-eight serum samples from the EXAMIN AGE study, consisting of healthy individuals and CV risk patients, were analyzed by nuclear magnetic resonance (NMR) spectroscopy to quantify lipoprotein subclasses. Microvascular health was quantified by measuring retinal arteriolar and venular diameters. Macrovascular health was quantified by measuring carotid-to-femoral pulse wave velocity (PWV). Nineteen lipoprotein subclasses showed statistically significant associations with retinal vessel diameters and nine with PWV. These lipoprotein subclasses together explained up to 26% of variation (R2=0.26, F(29,121)=2.80, p<0.001) in micro- and 12% (R2=0.12, F(29,124)=1.70, p=0.025) of variation in macrovascular health. High-density (HDL-C) and low-density lipoprotein cholesterol (LDL-C) as well as triglycerides together explained up to 13% (R2=0.13, F(3,143)=8.42, p<0.001) of micro and 8% (R2=0.08, F(3,145)=5.46, p=0.001) of macrovascular variation. Lipoprotein subclasses seem to reflect micro- and macrovascular end organ damage more precisely as compared to only measuring HDL-C, LDL-C and triglycerides. Further studies are needed to analyse how the additional quantification of lipoprotein subclasses can improve CV risk stratification and CV disease prediction.
CASE REPORT | doi:10.20944/preprints202205.0329.v1
Subject: Medicine & Pharmacology, Cardiology Keywords: Apple Watch; wearable sensor; pulse rate; arrhythmia; atrial fibrillation; case report
Online: 24 May 2022 (09:49:08 CEST)
Consumer rhythm-monitoring devices, such as the Apple Watch, are becoming more readily available. Irregular pulses can be detected using an optical sensor built into the wearable device. The Apple Watch (Apple Inc., Cupertino, CA, USA) is a class II medical device with pulse rate and electrocardiography (ECG) monitoring capabilities. Here we report a case in which an arrhythmia that was conventionally perceived but undiagnosed was identified as atrial fibrillation by self-acquisition of ECG data using an Apple Watch.
ARTICLE | doi:10.20944/preprints202011.0021.v1
Subject: Physical Sciences, Astronomy & Astrophysics Keywords: cosmic singularity; super repulsion; arche-conjugation; holographic unification; arche-pulse dynamics
Online: 2 November 2020 (10:53:29 CET)
To solve a series of major problems, such as the singularity before the Big Bang, the inflation of the early universe and the accelerating expansion of the present universe, this series of studies start with super gravity, dark energy and dark matter, go beyond the surface of a lot of observation data, and systematically reveal the arche-internal mechanism of all things, to establish the arche-unity of physics, and give a natural and reasonable explanation. At present, there are at least three basic pathways that are leading our research field to repulsion against gravitation, quantum repulsion against quantum gravitation and high-dimensional superrepulsion against high-dimensional supergravity, that is, the research on the accelerating expansion mechanism of the current universe, the research on the dynamic mechanism of the early cosmic inflation, and the research on the rebound mechanism near the singularity before the Big Bang. In this series of studies, the arche problem of everything is always placed under the extreme environmental conditions of the initial universe, the starting point of scientific logic is closely combined with the starting point of the universe history, the pseudo vacuum energy considered by the inflationary universe model, the Higgs field predicted by the standard physical model and the dark energy speculated by the observational cosmology are reduced to the positive energy system with strong negative pressure, and they are reduced to the repulsion (all the resistance to gravity) that forms a conjugate relation with gravity. In our opinion, dark energy and dark matter are essentially at the level of quantum gravity and quantum repulsion. Therefore, we not only consider the conventional quantum effect and non commutative quantum effect, but also further consider the arche-conjugate effect and the cluster resonance-at-cofrenquence effect. For noncommutative space-time, we put forth the ultimate supersymmetry, the arche-conjugation and the cluster resonance-at-cofrenquence. A relatively complete natural mechanism forms such an important inference: the closer they get to Planck scale, the stronger the conventional quantum effect, non commutative quantum effect, arche-conjugate effect and co-frequency resonance effect are. In the high-dimensional space-time (the 11 dimensional hyperspace compactly reduced to M 4 × N r ), corresponding to the introduction of supergravity with the supersymmetry between the graviton and the gravitino, we put forth the superrepulsion with the supersymmetry between the repulsion and the repulsitino, and establish the arche-conjugate relationship between the high-dimensional supergravity and the high-dimensional superrepulsion. Therefrom, we propose a basic inference that can be promoted to the principle of hyperholography of high-dimensional universe (or multiuniverse): in a parallel universe formed by mutual coupling and holographic correspondence between the P universe dominated by negative pressure (high-dimensional superrepulsion and quantum repulsion of accumulating positive energy, mainly composed of dark energy) and the N universe dominated by positive pressure (high-dimensional supergravity and quantum gravity of accumulating negative energy, mainly composed of dark matter), there is a correspondence between the small-scale physics (ultraviolet cutoff) of the P universe and the large-scale physics (infrared cutoff) of the N universe, while there is a correspondence between the large-scale physics (ultraviolet cutoff) of the P universe and the small-scale physics (infrared cutoff) of the N universe. In the new research paradigms set in this series, the arche-conjugation between the high-dimensional supergravity and the high-dimensional super repulsion, as well as between the quantum gravity and the quantum repulsion, is higher than the supersymmetry, so it becomes the core concept of the new theory. The arhce-unity of physics is a super unity that transcends the grand unification of four basic interaction, which is formed between high-dimensional supergravity (related to dark matter) and high-dimensional superrepulsion (related to dark energy), between quantum gravity (related to dark matter) and quantum repulsion (related to dark energy). From the basic component point of view, before or after the big bang, the gravitons and repulsons are coupled together, the negative energy contraction dominated by the positive pressure and the positive energy expansion dominated by the negative pressure work alternately, forming the arche-conjugate pulsaton of neither the point particle nor the linear superstring. Under the big unified framework of quantum gravitational field and quantum repulsive field, this series of work comprehensively expands the general relativity and loop quantum ring gravitation theory, sets up the quantum repulsive field equation corresponding to the quantum gravitational field equation, and then establishes the quantum hedge-unified field equation describing the interaction of quantum gravitational field and quantum repulsive field; On this basis, the quantum repulsive universe equation corresponding to the quantum gravitational universe equation is established, thus a set of new equations describing the expansive universe with quantum hedge-unified field are established. On the one hand, scalar disturbance is considered as the exhibition of repulsive effect, on the other hand, tensor disturbance is considered as the exhibition of gravitational effect. In the initial stage of the big ripping, due to the mutual restraint of quantum repulsion and quantum gravity, the scalar and tensor perturbations are not obvious. However, at the end of the big ripping, the scalar and tensor perturbations are very significant, and there is a large power spectral exponential run. Between particle physics and cosmology, we improve and expand the path integral of quantum gravity, create the path integral of quantum hedge-unified field, and set up the basic equation of quantum cosmic-synergetic dynamics, and then establish the basic equation of quantum-cosmic paradigm dynamics. Thus we put up the operator distribution function and its dynamic equation of the quantum arche- pulsaton, and finally use the Wigner-Ville distribution as a non-linear time-frequency distribution to establish the Wigner joint-distribution of quantum-conjuagted pulsation function, so as to analyze the arche of all things with three evolutionary forms: quantum chaotic-pulsaton, quantum quasi-spherical pulsaton and quantum spherical-pulsaton. In this series of work, the mechanism to avoid the singularity of the universe is put forward fundamentally, and the dark energy and dark matter are explained through new mechanisms and effects at the level of quantum gravity. Between particle physics and cosmology, we improve and expand the path integral of quantum gravity, establish the path integral of quantum hedge-unified field, thus establish the basic equation of quantum cosmic-synergy dynamics, and then establish the basic equation of quantum cosmic-paradigm dynamics. Thus the covariant gravitational mass and the covariant inertial mass formed by the ultra-synergy between particles and the universe are presented, and the equivalence hypothesis on the covariant non-inertial system which can be elevated to the basic principle, is presented. Based on this hypothesis, a systematic calculation and analysis of binary stars composed of neutron stars and black holes are made. The master equation, variance and Fokker-Planck equation for the birth-death and migration of a large number of particles are established between binary stars composed of neutron stars and black holes.
ARTICLE | doi:10.20944/preprints201711.0074.v1
Subject: Engineering, Biomedical & Chemical Engineering Keywords: cuprous oxide; non-enzymatic glucose sensor; alkaline solution; differential pulse voltammetry
Online: 13 November 2017 (03:15:30 CET)
A cuprous oxide (Cu2O) thin layer served as the base for a non-enzymatic glucose sensor in an alkaline medium, 0.1 NaOH solution, with a linear range of 50-200 mg/dL using differential pulse voltammetry (DPV) measurement. An X-ray photoelectron spectroscopy (XPS) study confirmed the formation of the cuprous oxide layer on the thin gold film sensor prototype. Quantitative detection of glucose in both phosphate-buffered saline (PBS) and undiluted human serum were carried out. Neither ascorbic acid nor uric acid even at a relatively high concentration level of 100mg/dL in serum interfered with the glucose detection, demonstrating the excellent selectivity of this non-enzymatic cuprous oxide thin layer based glucose sensor. Chronoamperometry (CA) and single potential amperometric voltammetry were used to verify the measurements obtained by differential pulse voltammetry (DPV), and the positive results validated that the detection of glucose in a 0.1 M NaOH alkaline medium by DPV measurement was effective. Nickel, platinum and copper are commonly used metals for non-enzymatic glucose detection. The performance of these metal-based sensors for glucose detection using DPV were also evaluated. Cuprous oxide (Cu2O) thin layer based sensor showed the best sensitivity for glucose detection among the sensors evaluated.
ARTICLE | doi:10.20944/preprints202209.0478.v1
Subject: Physical Sciences, Optics Keywords: gain-switching; semiconductor laser; quantum-dot; homogeneous-broadening; inhomogeneous-broadening; pulse generation
Online: 30 September 2022 (08:02:06 CEST)
For the first time the gain switching properties of an InAs-InP (113)B quantum dot laser are examined theoretically in detail to generate shorter pulses with the application of a Gaussian pulse beam to the laser excited state. The multi population rate equations considering nonlinear gain are solved by the Runge –Kutta method. The numerical results demonstrated that as the homogeneous and the inhomogeneous broadening increase, the differential gain, the gain compression factor and the threshold current of excited state decrease, while threshold current of ground state increases. It was also observed that the contribution of the excited state to gain-switched output pulses depends on not only the value of the inhomogeneous broadening but also the magnitude of the applied current. Finally it was shown that without an optical beam, output pulse has long pulse width due to ground state emission, whereas with an optical beam, narrow pulses having high peak power owing to the excited state emission are generated even though at low currents.
ARTICLE | doi:10.20944/preprints202209.0468.v1
Subject: Physical Sciences, Radiation & Radiography Keywords: Diamond; NV centre; ultrashort pulse; scattering; scattering spectra; X-ray diffraction analysis
Online: 29 September 2022 (11:04:56 CEST)
Scattering of ultrashort X-ray pulses (USP) is an important component of the diffraction analysis of matter using modern USP sources. Usually, the specific scattering of such USPs is not taken into account to determine the structure of a substance. Taking into account the specifics of scattering on complex structures will give more accurate results when deciphering complex structures. In this work, it is shown that when X-ray USPs are scattered on diamond with NV centers, it is necessary to take into account the pulse duration. The results obtained can be very different from the widely used theory of diffraction analysis, which confirms the need to take into account the specifics of USP scattering when diagnosing complex structures. It is also shown that scattering spectra are quite sensitive to the concentration of NV centres in the diamond structure and this can be used in diffraction analysis.
ARTICLE | doi:10.20944/preprints201904.0030.v1
Subject: Medicine & Pharmacology, Anesthesiology Keywords: Brody effect; electrocardiographic variation; R-wave amplitude; hemodynamic monitoring; pulse pressure variation
Online: 2 April 2019 (12:19:31 CEST)
The aim of this study was to analyze whether the respiratory variation in ECG standard lead II R-wave amplitude (ΔRDII) could be used to assess intravascular volume status following inferior vena cava (IVC) clamping. This clamping causes an acute decrease in cardiac output during liver transplantation (LT). We retrospectively compared ΔRDII and related variables before and after IVC clamping in 34 recipients. Receiver operating characteristic (ROC) curve and area under the curve (AUC) analyses were used to derive a cutoff value of ΔRDII for predicting pulse pressure variation (PPV). After IVC clamping, cardiac output significantly decreased while ΔRDII significantly increased (P = 0.002). The cutoff value of ΔRDII for predicting a PPV >13% was 16.9% (AUC: 0.685) with a sensitivity of 57.9% and specificity of 77.6% (95% confidence interval 0.561 – 0.793, P = 0.015). Frequency analysis of ECG also significantly increased in the respiratory frequency band (P = 0.016). Although significant changes in ΔRDII during vena cava clamping were found at norepinephrine doses < 0.1 μg/kg/min (P = 0.014), such changes were not significant at norepinephrine doses > 0.1 μg/kg/minP = 0.093). ΔRDII could be a noninvasive dynamic parameter in LT recipients presenting with hemodynamic fluctuation. Based on our data, we recommended cautious interpretation of ΔRDII may be requisite according to vasopressor administration status.
ARTICLE | doi:10.20944/preprints201805.0249.v1
Subject: Engineering, Energy & Fuel Technology Keywords: well testing; detrending; harmonic pulse testing; well performance monitoring; underground gas storage
Online: 17 May 2018 (13:01:50 CEST)
In reservoir engineering, one of the main sources of information for the characterization of reservoir and well parameters is well testing. Among the unconventional well testing methodologies, Harmonic Well Testing (HPT) is appealing from an economic standpoint because it could provide well performance and reservoir behavior monitoring without having to interrupt field production. Recorded pressure analysis is performed in the frequency domain by adopting a derivative approach similar to conventional well testing. To this end, pressure and rate data must be decomposed into harmonic components. Test interpretability can be significantly improved if pressure data are detrended prior to interpretation, filtering out non periodic events such as discontinuous production from neighboring wells and flow regime variations which did not respect the designed test periodicity. Therefore, detrending offers the possibility of overcoming the limitation of HPT applicability due to the difficulty of imposing a regularly pulsing rate for the whole test duration (typically lasting several days). This makes HPT attractive for well performance monitoring, especially in gas storage fields. In this paper, the application of different detrending methodologies to synthetic HPT pressure data generated in different reservoir and operational scenarios is presented and discussed. Moreover, a real case application is also presented.
ARTICLE | doi:10.20944/preprints202106.0592.v1
Subject: Medicine & Pharmacology, Allergology Keywords: arterial stiffness; brachial-ankle pulse wave velocity; left ventricular mass index; echocardiography; hypertension
Online: 24 June 2021 (08:39:17 CEST)
Background: Brachial-ankle pulse wave velocity (baPWV) is widely used as a marker of arterial stiffness. It has been suggested as a simple method for detecting arterial loads that can trigger left ventricular hypertrophy in the heart. Increased left ventricular hypertrophy in hypertensive patients is a predictor that will have an impact on increasing morbidity and mortality. Objective: This study aimed to evaluate the correlation between the baPWV and the left ventricular mass index (LVMI) in hypertensive patients. Methods: This cross-sectional study was conducted by collecting secondary data from hypertensive patients at the Heart Outpatient Clinic, with inclusion: aged more than 40 years old, suffering hypertension more than one year, and had baPWV and echocardiography data. Correlation between baPWV and LVMI was evaluated using the Pearson correlation test. Results: A total of 40 hypertensive patients were enrolled in this study. 60% were women. The mean age was 52.92 ± 9.50 years. Mean LVMI was 107.20 + 21.01 gram/m2. LVMI showed a significant association with age and systolic blood pressure (p=0.001 and 0.019, respectively). Mean baPWV was 1832.90 + 336.22 cm/sec. A significant association was found between baPWV and age and systolic blood pressure (p=0.000 and 0.049, respectively). There was a significant positive correlation between baPWV and LVMI (r=0.493, p=0.001); and between baPWV and Relative Wall Thickness (RWT) (r=0.404, p=0.01). Conclusion: This study shows that elevated baPWV is an indicator of increased LVMI in hypertensive patients. Examination of baPWV should be carried out routinely to detect earlier arterial stiffness as a morbidity and mortality prevention strategy in hypertensive patients.
ARTICLE | doi:10.20944/preprints201805.0283.v1
Subject: Engineering, Electrical & Electronic Engineering Keywords: venturini method; matrix converter; unbalanced voltage conditions; carrier-based pulse width modulation (PWM)
Online: 22 May 2018 (05:05:38 CEST)
Based on Venturini method, it is in favor of the modulation technique for controlling the matrix converter due to only use of the comparison between the duty cycles in time domain and the triangular carrier wave for generating the gating signals and the achievable voltage ratio between fundamental output magnitude and fundamental input magnitude to 0.866. However, even with simple modulation method and achieving maximum fundamental output magnitude, the possible input voltage unbalance conditions accordingly influence on the output performances (more reduction and distortion). Thus, a modified Venturini modulation method is presented in this paper, in order to solve the problems of unbalanced input voltage conditions on the matrix converter performances. The proposed strategy is to satisfy the desirable feature of the duty cycle modulating waves, as generated in the event of normal situation. Up to this approach, it can support either single-phase condition or two-phase condition. Performance of the proposed control strategy was verified by the simulated implementation in the MATLAB/Simulink software with showing good steady-state and dynamic operations.
ARTICLE | doi:10.20944/preprints201706.0060.v1
Subject: Materials Science, Biomaterials Keywords: β-amyloid 42; differential pulse voltammetry; Neuro-degenerative disorders; ferrocyanide/ferricyanide redox couple
Online: 13 June 2017 (18:14:57 CEST)
A simple in vitro biosensor for the detection of β-amyloid 42 in phosphate-buffer saline (PBS) and undiluted human serum was fabricated and tested based on our platform sensor technology. The bio-recognition mechanism of this biosensor was based on the effect of the interaction between antibody and antigen of β-amyloid 42 to the redox couple probe of K4Fe (CN) 6 and K3Fe (CN) 6. Differential pulse voltammetry (DPV) served as the transduction mechanism measuring the current output derived from the redox coupling reaction. The biosensor was a three-electrode electrochemical system, and the working and counter electrodes were 50 nm thin gold film deposited by sputtering technique. The reference electrode was a thick-film printed Ag/AgCl electrode. Laser ablation technique was used to define the size and structure of the biosensor. Cost-effective roll-to-roll manufacturing process was employed in the fabrication of the biosensor making it simple and relatively inexpensive. Self-assembled monolayers (SAM) of 3-Mercaptopropionic acid (MPA) was employed to covalently immobilize the thiol group on the gold working electrode. A carbodiimide conjugation approach using N-(3-dimethylaminopropyl)-N’-ethylcarbodiimide hydrochloride (EDC) and N–hydroxysuccinimide (NHS) was undertaken for cross-linking antibody of β-amyloid 42 to the carboxylic groups on one end of the MPA. The antibody concentration of β-amyloid 42 used was 18.75µg/mL. The concentration range of β-amyloid 42 in this study was from 0.0675µg/mL to 0.5µg/mL for both PBS and undiluted human serum. DPV measurements showed excellent response in this antigen concentration range. Interference study of this biosensor was carried out in the presence of Tau protein antigen. Excellent specificity of this β-amyloid 42 biosensor was demonstrated without interference by other species such as T-tau protein.
ARTICLE | doi:10.20944/preprints202209.0030.v2
Subject: Engineering, Civil Engineering Keywords: base-isolated building, irregularity, angle of seismic incidence, pulse-like ground motion, energy input
Online: 29 September 2022 (03:20:20 CEST)
In general, isolators and dampers used in seismically isolated buildings are designed to be isotropic in any horizontal direction. However, in the case of buildings with plan irregularities, their nonlinear responses depend on the direction of seismic loading. To discuss the influence of the angle of seismic incidence (ASI) on the nonlinear response of irregular building structures, it is important to define the angle of the critical axis of the horizontal ground motion. One possible choice is the “principal axis of ground motion” proposed by Arias (1970). However, because this principal axis is independent of the natural period of a structure, it could be complicated to use for seismically isolated structures with long natural periods. In this study, the influence of the ASI of long-period pulse-like seismic input on an irregular base-isolated building is investigated. First, the angle of the principal axis of ground motion is defined in terms of the cumulative energy input. Then, a nonlinear time-history analysis of a five-story irregular base-isolated building is performed using 10 long-period pulse-like ground motion records considering various ASIs. The results show that, compared with the principal axis of ground motion proposed by Arias, defining the principal axis of ground motion in terms of the cumulative energy input is more suitable for discussions concerning the influence of the ASI on the response of an irregular base-isolated building.
CASE REPORT | doi:10.20944/preprints202111.0331.v1
Subject: Medicine & Pharmacology, Oncology & Oncogenics Keywords: wearable sensor; pulse oximetry; sleep disturbance; blood oxygenation; haptic feedback; home care; oxygen concentration
Online: 18 November 2021 (14:32:09 CET)
The study reports about a case of a lung cancer patient with increasing difficulties in falling asleep and frequent periods of wakefulness. Severe dyspnea related to pneumonitis caused as a side effect of immunotherapy worsened the situation. Eventually, fear of falling asleep developed, including panic attacks and anxiety of choking, which was shown to lead to nights of complete wakefulness. The patient did not only sleep poorly; he did not sleep at all at night for several days, as evidenced by the notes he made during the night. Polygraphy showed no evidence of sleep-disordered breathing, but frequent periods of wakefulness and reduced basal saturation around 90% during sleep due to lung changes such as extensive functional failure of the left upper lobe with position-dependent shunts. The authors hypothesized that the symptoms described were causally related to a drop in oxygen saturation in the patient's blood. Therefore, they pursued the goal of finding a measurement technique that is as inexpensive as possible and that the patient can operate without outside assistance and great effort. So the patient started using a low-cost wearable device that allows simultaneous measurements of blood oxygen content, pulse rate and movement intensity. It consists of a finger ring with pulse oximetry sensor and a wristband with the control unit containing a vibration motor. The described device reliably warned of disturbances in oxygen concentration in the blood during the night with its vibration alarm. By use of that device during the whole night at home, the events of reduced oxygen saturation and the anxiety symptoms were reduced. Sleep disturbances with sudden awakenings did not occur when using the device. The patient benefited from the security gained in this way and slept much more peacefully, and he could spend nights without waking up again. In conclusion, wearable oximeters with vibration alarm can be recommended for patients’ home care in lung cancer patients.
ARTICLE | doi:10.20944/preprints202101.0382.v1
Subject: Chemistry, Analytical Chemistry Keywords: Chromium (VI); thin gold film; glassy carbon electrode and differential pulse anodic stripping voltammetry
Online: 19 January 2021 (13:52:45 CET)
A gold nanostructured film modified glassy carbon electrode (Aufilm/GCE) was developed for the determination of chromium (VI) in water sample. GCE was immersed into HAuCl4 solution (10-3M) and electrodeposition of thin gold layer was conducted at –0.4 V (vs Ag/AgCl) for 10 min. The strong affinity between Au and Cr species resulted with increasing of Cr (VI) signal, compared with the bare glassy carbon electrode. The electrodepositing time, type of supporting electrolyte, pH, the scan rate, modulation amplitude, and modulation time were optimized using differential pulse anodic stripping voltammetry (DP-ASV). The calibration graph using accumulation time of 120 s was linear from 10 to 120 µgL-1 with a sensitivity 1.3 x 10-2 µA/µgL-1. Under optimum experimental conditions, a good correlation coefficient R2=0.9971, and a low detection limit 5.5 µg/L Cr (VI) was obtained. The signal was reproducible with a relative standard deviation ±4.5 %. The developed Aufilm/GCE sensor was applied for the Cr (VI) determination of in sewage water samples.
ARTICLE | doi:10.20944/preprints202003.0116.v1
Subject: Medicine & Pharmacology, Anesthesiology Keywords: continuous epidural infusion; dexamethasone; dexamethasone pulse therapy; inflammation; local anesthetics; neuropathic pain; postherpetic neuralgia
Online: 7 March 2020 (03:22:47 CET)
The most common complication of herpes zoster is postherpetic neuralgia (PHN), which is accompanied by severe pain that lowers patients’ quality of life. Although epidural injection of local anesthetics and steroids is effective in controlling neuropathic pain resulting from herpes zoster, few studies report the efficacy and safety of epidural steroid administration in PHN patients. We randomly assigned 42 patients with severe PHN pain (visual analog scale (VAS) score ≥7) to receive continuous epidural infusion of local anesthetics with either a one-time bolus of 5 mg dexamethasone or dexamethasone pulse therapy. VAS scores significantly decreased over time for all patients, but the reduction in VAS scores and likelihood of achieving complete remission were significantly greater among patients who received dexamethasone pulse therapy, without any adverse effects. These results show that continuous epidural infusion of local anesthetics with dexamethasone is effective and safe for reducing PHN pain and promoting complete remission and that more pronounced beneficial effects are associated with more intense epidural steroid administration.
ARTICLE | doi:10.20944/preprints202002.0356.v1
Subject: Medicine & Pharmacology, Pediatrics Keywords: pulse oximetry; congenital heart disease; neonate; hypoxemia; Latin America; Ibero-American Society of Neonatology
Online: 24 February 2020 (14:08:22 CET)
Congenital heart disease (CHD) is among the 4 more common causes of infant mortality in Latin America. Pulse oximetry screening (POS) is useful for early diagnosis and improved outcomes of critical CHD. We describe POS implementation efforts in Latin American countries guided and/or coordinated by the Ibero American Society of Neonatology (SIBEN) as well as the unique challenges that are faced for universal implementation. SIBEN collaborates to improve neonatal quality of care and outcomes. A few years ago, a Clinical Consensus on POS was finalized. Since then, we participated in 12 Latin American countries to educate neonatal nurses and neonatologists on POS and to help with its implementation. The findings reveal that despite wide disparities in care that exist between and within countries, and the difficulties and challenges for implementing POS, significant progress was made. We conclude that universal POS is not easy to implement in Latin America but, when executed, not only it has been of significant value for babies with CHD but also for many with other hypoxemic conditions. The successful and universal implementation of POS in the future is essential to reduce the mortality associated with CHD and other hypoxemic conditions and will ultimately lead to the survival of many more Latin American babies. POS saves newborns’ lives in Latin America.
ARTICLE | doi:10.20944/preprints202210.0344.v1
Subject: Physical Sciences, Other Keywords: X-ray scattering; DNA; RNA; X-ray diffraction; ultrashort pulse; trinucleotides; CCG; CGG; CAG; CUG
Online: 24 October 2022 (03:08:05 CEST)
X-ray diffraction (XRD) analysis of complex poly-atomic systems, especially of biomolecules, using ultra-short laser pulses (USP), is currently one of the most important fields of modern physics. The basis for interpreting and "deciphering" experimental data is the well-known theory of X-ray scattering, where the main parameter of USPs - its duration - is not taken into account. In the present work it is shown that for scattering of attosecond USPs on DNA and RNA trinucleotides the pulse length is the most important scattering parameter. In this case the diffraction pattern significantly changes with respect to the previously known scattering theory. The results obtained are extremely important in XRD when using attosecond pulses to study trinucleotides of DNA and RNA because using the previously known scattering theory which does not take into account the duration of USPs one can not correctly interpret and therefore "decode" DNA and RNA structures.
ARTICLE | doi:10.20944/preprints202112.0390.v1
Subject: Biology, Ecology Keywords: Aerial laser scanning; Canopy structural complexity; Forest structure; National Ecological Observatory Network (NEON); Pulse density
Online: 23 December 2021 (11:59:27 CET)
Recent expansion in data sharing has created unprecedented opportunities to explore structure-function linkages in ecosystems across spatial and temporal scales. However, characteristics of the same data product, such as resolution, can change over time or spatial locations, as protocols are adapted to new technology or conditions, which may impact the data’s potential utility and accuracy for addressing end user scientific questions. The National Ecological Observatory Network (NEON) provides data products for users from 81 sites and over a planned 30-year time frame, including discrete return Light Detection and Range (LiDAR) from an airborne observatory platform. LiDAR is a well-established and increasingly available remote sensing technology for measuring three-dimensional (3D) characteristics of ecosystem and landscape structure, including forest structural diversity. The LiDAR product that NEON provides can vary in point density from 2 – 25+ points/m2 depending on instrument and acquisition date. We used NEON LiDAR from five forested sites to (1) identify the minimum point density at which structural diversity metrics can be robustly estimated across forested sites from different ecoclimatic zones in the USA and (2) to test the effects of variable point density on the estimation of a suite of structural diversity metrics and multivariate structural complexity types within and across forested sites. Twelve out of sixteen structural diversity metrics were sensitive to LiDAR point density in at least one of the five NEON forested sites. The minimum point density to reliably estimate the metrics ranged from 2.0 to 7.5 pt/m2, but our results indicate that point densities above 7-8 pt/m2 should provide robust measurements of structural diversity in forests for temporal or spatial comparisons. The delineation of multivariate structural complexity types from a suite of 16 structural diversity metrics was robust within sites and across forest types for a LiDAR point density of 4 pt/m2 and above. This study shows that different metrics of structural diversity can vary in their sensitivity to the resolution of LiDAR data and users of these open-source data products should consider the point density of their data and use caution in metric selection when making spatial or temporal comparisons from these datasets.
ARTICLE | doi:10.20944/preprints202009.0023.v1
Subject: Engineering, Civil Engineering Keywords: near field; pulse like ground motions; bridge, non-linear static analysis; non-linear dynamic analysis
Online: 2 September 2020 (04:51:43 CEST)
Near-fault ground motions can cause severe damage to civil structures, including bridges. Safety assessment of these structures for near fault ground motion is usually performed through Non-Linear Dynamic Analyses, while faster methods are often used. IMPAb (Incremental Modal Pushover Analysis for Bridges) permits to investigate the seismic response of a bridge by considering the effects of higher modes, which are often relevant for bridges. In this work, IMPAb is applied to a bridge case study considering near-fault pulse-like ground motion records. The records were analyzed and selected from the European Strong Motion Database and the pulse parameters were evaluated. In the paper results from standard pushover procedures and IMPAb are compared with nonlinear Response-History Analysis (NRHA), considering also the vertical component of the motion, as benchmark solutions and incremental dynamic analysis (IDA). Results from the case study demonstrate that the vertical seismic action has a minor influence on the structural response of the bridge. Therefore IMPAb, which can be applied considering vertical motion, remains very effective conserving the original formulation of the procedure, and can be considered a well performing procedure also for near-fault events.
ARTICLE | doi:10.20944/preprints201810.0578.v1
Subject: Engineering, Electrical & Electronic Engineering Keywords: Oxygen Saturation (SpO2); Green and Orange Illuminations; Optoelectronic Patch; Sensor (mOEPS); Pulse Oximetry; Physical Movement.
Online: 24 October 2018 (14:12:21 CEST)
Photoplethysmography (PPG) based pulse oximetry devices normally use red and infrared illuminations to obtain oxygen saturation (SpO2) readings. In addition, the presence of motion artefacts severely restricts the utility of pulse oximetry physiological measurements. In the current study, a combination of green and orange illuminations from a multi-wavelength optoelectronic patch sensor (mOEPS) was investigated in order to improve robustness to subjects’ movements in the extraction of SpO2 measurement. Two experimental protocols with 31 healthy subjects were designed to determine SpO2 measurement. The datasets for the first protocol were collected from 15 subjects at rest, with the subjects free to move their hands. The datasets for the second protocol with 16 subjects were collected during cycling and running exercises. The results showed good agreements with SpO2 measurements (r = 0.98) in the both protocols. The outcomes promise a robust and cost-effective approach of physiological monitoring with the prospect of providing health monitoring that does not restrict user physical movements.
REVIEW | doi:10.20944/preprints201704.0109.v1
Subject: Engineering, Other Keywords: fiber ring laser; hybrid mode locking; passive mode locking; rational harmonic mode locking; pulse compression
Online: 18 April 2017 (05:14:55 CEST)
Mode locked pulse generation has been reported using both active and passive mode locking schemes. Active mode locking technique has been proven to be an effective way to generate high-repetition-rate pulses by incorporating a modulator inside the laser cavity. Compared to actively mode locked lasers, passively mode locked lasers can generate pulse train at ultrashort pulse width but with relatively lower repetition rate. Thus, it is a brilliant idea to build a hybrid mode locked system combining both active and passive mode lockers. In this review, several hybrid mode locked fiber ring laser systems are discussed and summarized. Hybrid mode locking is a promising method to generate high speed ultrashort optical pulses for fiber-optic telecommunication system.
ARTICLE | doi:10.20944/preprints201701.0091.v1
Subject: Engineering, Mechanical Engineering Keywords: fault diagnosis; shock pulse index; maximum correlated kurtosis deconvolution; teager energy operator; rolling element bearings
Online: 20 January 2017 (04:12:25 CET)
Properties of time domain parameters of the vibration signal have been extensively studied for the fault diagnosis of rolling element bearings (REB). Parameters like kurtosis and Envelope Harmonic-to-Noise Ratio are most widely applied in this field and some important progress has been made. However, since only one-sided information is contained in these parameters respectively, problems still exist in practice when the signals collected are of complicated structure and/or contaminated by strong background noises. A new parameter, named Shock pulse index (SPI), is proposed in this paper. It integrates the mutual advantage of both parameters above and can help effectively identify fault related impulse components under the interference of strong background noises, unrelated harmonic components and random impulses. The SPI optimizes the parameters of Maximum Correlated Kurtosis Deconvolution (MCKD), which is used to filter the signals under consideration. Finally, the interested transient information contained in the filtered signal can be highlighted through demodulation with Teager Energy Operator (TEO). Fault related impulse components can therefore be extracted accurately. Simulations and experiment analyses verify the effectiveness and correctness of the SPI.
ARTICLE | doi:10.20944/preprints202111.0041.v1
Subject: Engineering, Biomedical & Chemical Engineering 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/preprints202103.0017.v1
Subject: Medicine & Pharmacology, Allergology Keywords: dry eye disease; meibomian gland; tear stability; tear film lipid layer; interferometry; OSDI; intense pulse light; IPL
Online: 1 March 2021 (13:45:51 CET)
Background: Inadequate meibomian glands (MGs) secretion can lead to dry eye signs and symptoms. Tear film lipid layer (TFLL) secreted by MGs protects and prevents rapid evaporation of tear film. Our purpose was to assess TFLL alteration and function in patients with evaporative dry eye (EDE) using tear interferometry after optimal pulse light technology (OPT) intense pulsed light (IPL). Methods: This prospective randomized examiner-masked sham- controlled study included 86 participants (142 eyes) with DED. IPL or sham procedure was performed on day 0, 21, and 42. Ocular Surface Disease Index (OSDI), non-invasive breakup time (NITBUT), interferometric fringe pattern determined TFLL quality, fluorescein staining (FS), and meibum gland (MG) were assessed at day 0, 21, 42 and 3-month. Results: At 3-month, TFLL, NITBUT, MG drop-out, MG quality, MG expressibility, FS and OSDI improved significantly (P<0.05) in the IPL group, while the sham group had no significant improvements. All DE parameters significantly correlated with the improvement in TFLL following IPL treatment. Additionally, artificial tears usage was significantly less in the IPL group from D-42 onwards. Conclusion: IPL treatment demonstrated the ability to improve TFLL quality and clinically reduced sign and symptoms of DED thereby reducing the frequency of artificial tears usage.
ARTICLE | doi:10.20944/preprints201901.0270.v1
Subject: Engineering, Civil Engineering Keywords: Non-Destructive Tests, Structural Health Monitoring, Ultrasonic Pulse Velocity, Rebound Hammer, Surface Hardness, Compressive Strength, Linear regression
Online: 28 January 2019 (09:43:18 CET)
This work investigates the use of Non-destructive tests as a tool for monitoring the structural performance of concrete structures. The investigation encompassed four phases; the first of which involved the use of destructive and non-destructive mechanisms to assess concrete strength on cube specimens. The second phase research focused on site assessment for a twin engineering theatre located at the Faculty of Engineering, University of Lagos using rebound hammer and ultrasonic pulse velocity tester. The third phase was the use of linear regression analysis model with MATLAB to establish a relationship between calibrated strength as well as ultrasonic pulse velocities with their corresponding compressive strength values on cubes and values obtained from existing structures. Results show that the root-mean squared-R2 values for rebound hammer ranged between 0.275 and 0.742 while ultrasonic pulse velocity R2 values were in the range of 0.649 and 0.952 for air curing and water curing systems respectively. It initially appeared that the Ultrasonic pulse velocity was more suitable for predicting concrete strength than rebound hammer but further investigations showed that the latter was adequate for early age concrete while the former was more suited for aging concrete. Hence, a combined use is recommended in this work.
ARTICLE | doi:10.20944/preprints202107.0290.v1
Subject: Engineering, Automotive Engineering Keywords: permanent magnet synchronous motor; sideband harmonic component; space vector pulse-width modulation; carrier frequency modulation; vibro-acoustic responses.
Online: 13 July 2021 (10:45:49 CEST)
In the permanent magnet synchronous motor (PMSM) drive system, the unwilling and ear-piercing vibro-acoustics caused by high-frequency sideband harmonics becomes unacceptable in the electric vehicle application. In this paper, a modified space vector pulse-width modulation (SVPWM) technique implemented with hybrid carrier frequency modulation (HCFM) is provided to reduce the sideband current harmonic components and vibro-acoustic responses. The principle and implementation of the proposed HCFM technique are firstly presented, in which the fixed carrier frequency is improved with the sawtooth and random signal-based coupling modulation based on the rotor position. For verification, the experiment tests are carried out on a prototype 12/10 PMSM and microcontroller unit. The effectiveness of the HCFM technique can hence be confirmed, in which the sideband vibro-acoustics reduction shows more effectively than that in conventional random PWM. The proposed approach may provide a new route in noise-cancelling and electromagnetic compatibility for the electric drive powertrain.
Subject: Chemistry, Analytical Chemistry Keywords: screen printed electrodes; Ag nanoparticles; drop-casting; spin-coating; nanoprisms; heavy metals; Differential pulse anodic stripping voltammetric; electrocatalysis
Online: 5 August 2019 (04:55:05 CEST)
The screen-printed carbon nanofibers electrodes (SPCNFE) represent an alternative with great acceptance due to their results, as well as their low impact for the environment. In order to improve their performance, in the present work they were modified with silver nanoparticles (Ag-NPs) and electrochemically characterized by using anodic stripping voltammetry. From the Ag-NPs synthesis, silver seeds (Ag-NS) and silver nanoprisms (Ag-NPr) were obtained. The Ag-NPs formation was confirmed by micrographs where Ag-NPs with diameters of 12.20±0.04 nm for Ag-NS, and 20.40±0.09 nm for Ag-NPr were observed. The electrodes were modified by using three different deposition methods: drop-casting, spin-coating and in-situ approaches. It was observed that the last methodology showed a low amount of Ag-NS deposited on the electrode surface and a deep alteration of this surface. Those facts suggested that the in situ synthesis methodology were not appropriate for the determination of heavy metals and it was discarded. The incorporation of the nanoparticles by spin-coating and drop-casting strategies showed different spatial distribution on the electrode surface as proved by scanning electron microscopy. The electrodes modified by these strategies, were evaluated for the cadmium(II) and lead(II) detection using differential pulse anodic stripping voltammetry, obtaining detection limit values of 2.1 and 2.8 µg L-1, respectively. The overall results showed that the incorporation route does not change directly the electrocatalytic effect of the nanoparticles, but the shape of these nanoparticles (spherical for seeds and triangular for prisms) has a preferential electrocatalytical enhancement over Cd(II) or Pb(II).
ARTICLE | doi:10.20944/preprints202004.0454.v1
Subject: Medicine & Pharmacology, Nutrition Keywords: casein hydrolysate; Val-Pro-Pro; Ile-Pro-Pro; brachial ankle pulse wave velocity; advanced glycation end products; facial pigmentation
Online: 25 April 2020 (02:42:35 CEST)
Casein hydrolysate improves arterial stiffness, as estimated by brachial ankle pulse wave velocity (baPWV), in untreated hypertensive subjects. Facial pigmentation is a useful biomarker for arterial stiffness. This trial evaluated whether casein hydrolysate improves facial pigmentation in association with changes in arterial stiffness. A randomized, double-blind, placebo-controlled trial was conducted in 80 non-hypertensive Japanese participants randomly assigned to receive either active tablets containing casein hydrolysate or placebo for 48 weeks. Facial pigmentation and baPWV were measured at baseline and at the end of the intervention. Other biochemical atherosclerosis-related parameters were also measured, including advanced glycation end products (AGEs). Changes in facial pigmentation showed a significant difference between the groups. Change in baPWV was significantly better in the active than in the placebo group. In contrast, no significant association was seen between changes in facial pigmentation and those in baPWV. Among other atherosclerosis-related factors, changes in advanced glycation products (AGEs) were significantly decreased in the active compared to the placebo group. Further, changes in facial pigmentation were positively correlated with those in AGEs. Changes in AGEs were independently associated with changes in facial pigmentation. Casein hydrolysate improves facial pigmentation in non-hypertensive participants. Casein hydrolysate may have beneficial effects on glycation stress.
ARTICLE | doi:10.20944/preprints202210.0260.v1
Subject: Engineering, Electrical & Electronic Engineering Keywords: induction generator; Direct Field Oriented Control (DFOC), three-level inverter; sinusoidal pulse width modulator (SPWM), maximum power point tracking (MPPT)
Online: 18 October 2022 (10:33:31 CEST)
The article presents an induction generator connected to the power grid using the AC / DC / AC converter and LCL coupling filter. In the converter, both from the generator side and from the power grid side, three-level inverters were used. The algorithm realizing Pulse Width Modulation (PWM) in inverters has been simplified to the maximum. Control of the induction generator was based on the Direct Field Oriented Control (DFOC) method. At the same time, voltage control has been used for this solution. The MPPT algorithm has been extended to include the variable pitch range of the wind turbine blades. The active voltage balancing circuit has been used in the inverter DC voltage circuit. In the control system of the grid converter with an LCL filter, the number of measurements was limited to the measurement of power grid currents and voltages. Synchronization of control from the power grid side is ensured by the use of a PLL loop with the system of preliminary suppression of undesired harmonics (CDSC).
ARTICLE | doi:10.20944/preprints201811.0273.v1
Subject: Engineering, Electrical & Electronic Engineering Keywords: optical communications; optical spatial modulation; free-space optical communication; multiple-input-multiple-output (MIMO) systems; pulse position modulation; atmospheric turbulence
Online: 12 November 2018 (09:26:34 CET)
In this paper, spatial pulse position modulation (SPPM) is used as a case study to investigate the performance of the optical spatial modulation (SM) technique in outdoor atmospheric turbulence (AT). A closed-form expression for the upper bound on the asymptotic symbol error rate (SER) of SPPM in AT is derived and validated by closely-matching simulation results. The error performance is evaluated in weak to strong AT conditions. As the AT strength increases from the weak to strong, the channel fading coefficients become more dispersed and differentiable. Thus, a better error performance is observed under moderate-to-strong AT compared to weak AT. The performance in weak AT can be improved by applying unequal power allocation to make FSO links more distinguishable at the receiver. Receive diversity is considered to mitigate irradiance fluctuation and improve the robustness of the system to turbulence-induced channel fading. The diversity order is computed as half of the number of detectors. Performance comparisons, in terms of energy and spectral efficiencies, are drawn between the SPPM scheme and conventional MIMO schemes such as repetition coding and spatial multiplexing.
ARTICLE | doi:10.20944/preprints202012.0392.v1
Subject: Earth Sciences, Geophysics Keywords: Earth’s natural pulse electromagnetic field; stress-strain state of rock mass; magnetic field strength; magnetic induction; pipeline; measurement; accident; civil communication
Online: 15 December 2020 (19:52:19 CET)
The paper presents an analysis of the method of recording the magnetic component of the Earth’s natural pulse electromagnetic field in an urban environment. This method of recording has already proved itself to be a method that allocates the stressed sections of rock mass at mining and, therefore, authors suppose its effectiveness for allocating active tectonic disturbances and forecasting accidents at underground utilities, what will help reduce the potential environmental hazard of these objects.
ARTICLE | doi:10.20944/preprints201805.0284.v1
Subject: Engineering, Electrical & Electronic Engineering Keywords: dual two-level voltage source inverter; common-mode voltage; discontinuous space vector modulation schemes; centralizing pulse width modulation; open-end load
Online: 22 May 2018 (05:11:06 CEST)
The popular motor drive systems with a single two-level voltage source inverter (VSI) have one main problem that is the occurrence of the common-mode voltage (CMV), which is an effect of the electromagnetic interference, shaft voltage, bearing currents, leakage current. These cause the high stress, increasung temperature and early mechanical failure in machine. To overcome this problem, the technology of the dual two-level VSI fed open-end three-phase ac loads is now available to eliminate the CMV at the ac/induction motor load with the 120-degree modulation technique for controlling each inverter. In this paper, the discontinuous space vector modulation (DSVM) schemes are proposed and applied for the dual two-level VSI fed open-end load. It is based on the 120-degree modulation technique by using only 12 active voltage vectors and the 10 zero voltage vectors from the total 64 voltage vectors along with the different five-segment swicthing sequence designs with centralizing pulse width modulation technqiue in order to not only cancel the CMV in the ac load, but also reduce the switching number/switching loss of the conversion system. Among the various DSVM schemes, their performances are compared in this paper, such as the number of the switching, the step and peak value of the CMV in each inverter, and the quality of the output waveform, etc. The details of the verfication and comparison are carried out by simulation using Matlab/Simulink software.
REVIEW | doi:10.20944/preprints201609.0050.v1
Subject: Engineering, Biomedical & Chemical Engineering Keywords: DCMS, DCMSP, and sputtering; highly ionized pulse plasma magnetron sputtering (HIPIMS); bacterial inactivation kinetics; Cu and TiO2 synergic effects; interfacial charge transfer
Online: 16 September 2016 (13:31:00 CEST)
This review focuses on Cu/TiO2 sequentially and Cu-TiO2 co-sputtered catalytic/photocatalytic surfaces leading to bacterial inactivation discussing their stability, synthesis, adhesion and antibacterial kinetics. The intervention of TiO2, Cu and the synergic effect of Cu and TiO2 on films prepared by a colloidal approach and other techniques is also reviewed leading to bacterial inactivation. Processes in aerobic media and anaerobic media leading to bacterial loss of viability on multidrug resistant (MDR) pathogens, Gram-negative (-) and Gram-positive(+) bacteria are described. Insight is provided for the interfacial charge transfer mechanism under solar irradiation occurring between TiO2 and Cu. surface properties of 2D TiO2/Cu and TiO2-Cu films are correlated with the bacterial inactivation kinetics observed in the dark and under light. The intervention of these antibacterial sputtered surfaces in health-care facilities leading to MRSA-isolates is described in the dark and under the actinic light. The synergic intervention of the Cu and TiO2 films leading to bacterial inactivation prepared by direct current magnetron sputtering (DCMS), pulsed direct current magnetron sputtering (DCMSP) and highly ionized pulse plasma magnetron sputtering (HIPIMS) is reported in a detailed way.
ARTICLE | doi:10.20944/preprints202210.0481.v1
Subject: Mathematics & Computer Science, Applied Mathematics Keywords: Controlled Elitism Non-Dominated Sorting Genetic Algorithm; CENSGA; NSGA-II; Variable-length chromosome (VLC); metaheuristic; multi-objective optimization; Pulse vaccination; allocation; scheduling; planning
Online: 31 October 2022 (10:16:41 CET)
: Seasonal influenza (a.k.a flu) is responsible for considerable morbidity and mortality across the globe. The three recognized pathogens that cause epidemics during the winter season are influenza A, B and C. The influenza virus is particularly dangerous due to its mutability. Vaccines are an effective tool in preventing seasonal influenza, and their formulas are updated yearly according to WHO recommendations. However, in order to facilitate decision-making in the planning of the intervention, policymakers need information on the projected costs and quantities related to introducing the influenza vaccine, in order to help governments obtain an optimal allocation of the vaccine each year. In this paper, an approach based on a Controlled Elitism Non-Dominated Sorting Genetic Algorithm (CENSGA) model is introduced to optimize the allocation of influenza vaccination. A bi-objective model is formulated to control the infection volume, and reduce the unit cost of the vaccination campaign. An SIR (Susceptible–Infected–Recovered) model is employed for representing a potential epidemic. The model constraints are based on the epidemiological model, time management, and vaccine quantity. A two-phase optimization process is proposed: guardian control followed by contingent controls. The proposed approach is an evolutionary metaheuristic multi-objective optimization algorithm with a local search procedure based on a hash table. Moreover, in order to optimize the scheduling of a set of policies over a predetermined time to form a complete campaign, an extended CENSGA is introduced with a variable-length chromosome (VLC) along with mutation and crossover operations. To validate the applicability of the proposed CENSGA, it is compared with the classical Non-Dominated Sorting Genetic Algorithm (NSGA-II). The results are analyzed using graphical and statistical comparisons in terms of cardinality, convergence, distribution and spread quality metrics, illustrating that the proposed CENSGA is effective and useful for determining the optimal vaccination allocation campaigns.
ARTICLE | doi:10.20944/preprints202201.0398.v1
Subject: Physical Sciences, Atomic & Molecular Physics Keywords: B-spline R-matrix; R-matrix with time dependence; intense short-pulse extreme ultra14 violet radiation; time-dependent Schrdinger equation; Arnoldi-Lanczos propagation
Online: 26 January 2022 (13:01:07 CET)
Since its initial development in the 1970’s by Phil Burke and his collaborators, the R-matrix theory and associated computer codes have become the de facto approach for the calculation of accurate data for general electron-atom/ion/molecule collision and photoionization processes. The use of a non-orthonormal set of orbitals based on B-splines, now called the B-spline R-matrix (BSR) approach, was pioneered by Zatsarinny. It has considerably extended the flexibility of the approach and improved particularly the treatment of complex many-electron atomic and ionic targets, for which accurate data are needed in many modelling applications for processes involving low-temperature plasmas. Both the original R-matrix approach and the BSR method have been extended to the interaction of short, intense electromagnetic (EM) radiation with atoms and molecules. Here we provide an overview of the theoretical tools that were required to facilitate the extension of the theory to the time domain. As an example of a practical application, we show results for two-photon ionization of argon by intense short-pulse extreme ultraviolet radiation
ARTICLE | doi:10.20944/preprints202103.0403.v1
Subject: Engineering, Biomedical & Chemical Engineering Keywords: non-canonical branched chain amino acids; scale-down; strain screening; mixed-acid fermentation; pyruvate pulse; norvaline; norleucine; fed-batch cultivation; bioreactor; Enpresso; Enbase
Online: 16 March 2021 (09:11:34 CET)
Insufficient mixing in large-scale bioreactors, provokes gradient zones of substrate, dissolved oxygen, pH and other parameters. E. coli responds to a high glucose, low oxygen feeding zone with the accumulation of mixed acid fermentation products, especially formate, but also with the synthesis of non-canonical amino acids, such as norvaline, norleucine and -methyl-norleucine. These amino acids can be mis-incorporated into recombinant products, which causes a problem for pharmaceutical production whose solution is not trivial. While these effects can also be observed in scale down bioreactor systems, these are challenging to operate. Especially the high-throughput screening of clone libraries is not easy, as fed-batch cultivations would need to be controlled via repeated glucose pulses with simultaneous oxygen limitation, as has been demonstrated in well controlled robotic systems. Here we show that not only glucose pulses in combination with oxygen limitation can provoke the synthesis of these non-canonical branched-chain amino acids, but also that pyruvate pulses produce the same effect. Therefore we combined the enzyme based glucose delivery method Enbase® in a PALL24 mini-bioreactor system and combined repeated pyruvate pulses with simultaneous reduction of the aeration rate. These cultivation conditions, produced an increase in the non-canonical branched chain amino acids norvaline and norleucine in both the intracellular soluble protein and inclusion body fractions with mini-proinsulin as an example product, and this effect was verified in a 15 L stirred tank bioreactor. To our opinion this cultivation strategy is easy to apply for the screening of strain libraries under standard laboratory conditions if no complex robotic and well controlled parallel cultivation devices are available.
ARTICLE | doi:10.20944/preprints201907.0295.v1
Subject: Engineering, Control & Systems Engineering Keywords: decoupled controller; ferrite material; proportional integral (PI); solid state transformer (SST); space vector pulse width modulation (SVPWM); voltage source converter (VSC); voltage source inverter (VSI)
Online: 26 July 2019 (01:02:25 CEST)
This paper presents a symmetrical topology for the design of solid-state transformer, made up of power switching converters, to replace conventional bulky transformers. The proposed circuitry not only reduces the overall size but also provides power flow control with the ability to be interfaced with renewable energy resources (RESs) to fulfill the future grid requirements at consumer end. Solid state transformer provides bidirectional power flow with variable voltage and frequency operation and has the ability to maintain unity power factor, and current total harmonic distortion (THD) for any type of load within defined limits of IEEE standard. Solid State Transformer offers much smaller size as compared to that of the conventional iron core transformer. MATLAB/Simulink platform is adopted to test the validity of the proposed circuit for different scenarios by providing the simulation results evaluated at 25 kHz switching frequency.
ARTICLE | doi:10.20944/preprints202106.0409.v1
Subject: Engineering, Electrical & Electronic Engineering Keywords: DC-link current; harmonic mitigation; voltage source inverters; multi-converter systems; carrier wave interleaving scheme; DC-grid; phase-shifting; capacitor current ripple; unipolar sinusoidal pulse width modulation
Online: 15 June 2021 (14:26:57 CEST)
DC-connected parallel inverter systems are gaining popularity in industrial applications. However, such parallel systems generate excess current ripple (harmonics) at the DC-link due to harmonic interactions between the inverters in addition to the harmonics from the PWM switching. These DC-link harmonics cause the failure of fragile components such as DC-link capacitors. This paper proposes an interleaving scheme to minimize the current harmonics induced in the DC-link of such a system. The results show that when the carrier waves of the two inverters are phase-shifted by 90° angle, the maximum high-frequency harmonic ripple cancellation occurs, which reduces the overall RMS value of the DC-capacitor current.The outcome of this proposed solution is a cost-effective DC-harmonics mitigating strategy for the industrial designers to practically configuring multi-inverter systems, even when most of the drives are not operating at rated power levels. Experimental and simulation results presented in this paper verify the effectiveness of the proposed carrier-based phase-shifting scheme for two different configurations of common DC connected multi-converter systems.