REVIEW | doi:10.20944/preprints201904.0265.v1
Subject: Engineering, Biomedical & Chemical Engineering Keywords: Medical Device Regulation; wearable medical sensor; medical device; accessory
Online: 24 April 2019 (11:17:05 CEST)
Background: medical devices are designed, tested and placed on the market in a highly regulated environment. Wearable sensors are crucial components of various medical devices: design and validation of wearable sensors, if managed according to international standards, can foster innovation while respecting regulatory requirements. Material and methods: the purpose of this paper is to take into consideration the upcoming EU Medical Device Regulation 2017/245 and the current and future IEC and ISO standards that set methods for design and validation of medical devices, with a focus on wearable sensors. Risk classification according to the regulation is described. The international standards IEC 62304, IEC 60601, ISO 14971 and ISO 13485 are reviewed to define regulatory restrictions during design, pre-clinical validation and clinical validation of devices that include wearable sensors as crucial components. Results: current and future regulatory restrictions are described, and an integrated method for design planning, validation and clinical testing is described Discussion: application of this method to design wearable sensors should be evaluated in the future in order to assess its potentially positive impact to fostering innovation and to the time-to-market of the device.
CASE REPORT | doi:10.20944/preprints202301.0427.v2
Online: 29 January 2023 (09:29:03 CET)
The improvement of health and social care needs the introduction of shared solution at transnational level. The SI4CARE (Social Innovation for Integrated Health Care) project is a transnational initiative within the Adriatic-Ionian regions aiming to develop strategies to improve the current status of health and social care. The Municipality of Miglierina, a small rural town in Calabria, which is a member the project, is developing a pilot action related to the use of wearable device for monitoring people affected by dementia with the project partner Ra.Gi.. Ra.Gi. is a non-profit organization dedicated to assisting people with dementia in day care centers and so-called dementia-friendly communities. The pilot is based on the use of smart wearable devices to monitor these patients during their daily lifetime. This paper focuses on the design and implementation of the system discussing the proposed application, the strengths and weaknesses. Finally, the possibility of extending the experiment to the other Adriatic-Ionian region is presented.
CASE REPORT | doi:10.20944/preprints201808.0378.v1
Online: 21 August 2018 (13:49:34 CEST)
Aim: In a human pilot case, we used a root formed temporary prosthetical device (Intra-alveolar Device - IAD), to investigate the effect of mechanical stimulation on hard tissue clinically and radiographically. Background: The extraction of a tooth determines the resorption of the alveolar bone. This determines challenge to place an implant and to integrate the prosthesis in soft tissue. Mechanical stimulation is fundamental for bone tropism but is not understood the effect of mechanical stimulation on post-extraction site. Case presentation: A 24 years old woman was enrolled. The IAD’s were used as expected by protocol. Clinical healing was uneventfully. Vertical radiographical bone resorption measured on CBCT was -0,14mm (5,6%) while horizontal bone resorption was -0,21mm (12,36%). Conclusion: This study demonstrated the feasibility of the proposed model. We need clinical prospectical studies enrolling more patients
CONCEPT PAPER | doi:10.20944/preprints202101.0273.v1
Subject: Engineering, Automotive Engineering Keywords: context management; device classification; IoT device management; k-Means clustering; ubiquitous computing; unsupervised machine learning
Online: 14 January 2021 (13:36:31 CET)
Ubiquitous computing comprises scenarios where networks, devices within the network, and software components change frequently. Market demand and cost-effectiveness are forcing device manufacturers to introduce new-age devices. Also, the Internet of Things (IoT) is transitioning rapidly from the IoT to the Internet of Everything (IoE). Due to this enormous scale, effective management of these devices becomes vital to support trustworthy and high-quality applications. One of the key challenges of IoT device management is automatic device classification with the logically semantic type and using that as a parameter for device context management. This would enable smart security solutions. In this paper, a device classification approach is proposed for the context management of ubiquitous devices based on unsupervised machine learning. To classify unknown devices and to label them logically, a proactive device classification model is framed using a k-Means clustering algorithm. To group devices, it uses the information of network parameters such as Received Signal Strength Indicator (rssi), packet_size, number_of_nodes in the network, throughput, etc. Experimental analysis suggests that the well-formedness of clusters can be used to derive cluster labels as a logically semantic device type which would be a context for resource management and authorization of resources. This paper fulfills an identified need of proactive device classification for device management.
ARTICLE | doi:10.20944/preprints201806.0317.v1
Subject: Engineering, Electrical & Electronic Engineering Keywords: device-to-device; LTE systems; resource allocation; particle swarm optimization algorithm; genetic algorithm; system capacity
Online: 20 June 2018 (09:31:54 CEST)
In this study, the resource blocks (RB) are allocated to user equipment (UE) according to the evolutional algorithms for long term evolution (LTE) systems. Particle Swarm Optimization (PSO) algorithm is one of the evolutionary algorithms, based on the imitation of a flock of birds foraging behavior through learning and grouping the best experience. In previous work, the Simple Particle Swarm Optimization (SPSO) algorithm was proposed for RB allocation to enhance the throughput of Device-to-Device (D2D) communications and improve the system capacity performance. In simulation results, with less population size of M = 10, the SPSO can perform quickly convergence to sub-optimal solution in the 100th generation and obtained sub-optimum performance with more 2 UEs than the Rand method. Genetic algorithm (GA) is one of the evolutionary algorithms, based on Darwinian models of natural selection and evolution. Therefore, we further proposed a Refined PSO (RPSO) and a novel GA to enhance the throughput of UEs and to improve the system capacity performance. Simulation results show that the proposed GA with 100 populations, in 200 generations can converge to suboptimal solutions. Therefore, with comparing with the SPSO algorithm the proposed GA and RPSO can improve system capacity performance with 1.8 and 0.4 UEs, respectively.
CASE REPORT | doi:10.20944/preprints202205.0111.v1
Subject: Medicine & Pharmacology, Obstetrics & Gynaecology Keywords: Intrauterine device; cervical perforation; hysteroscopy; copper; strings
Online: 9 May 2022 (10:00:28 CEST)
Abstract Purpose Since their introduction, intrauterine devices (IUDs) have been associated with various complications. Avery rare complication is the perforation of the cervix by the strings of the IUD. Purpose of the current study is to present a novel case of cervical perforation by the strings of a copper IUD and to perform a systematic review of the literature. Materials and Methods The patient a 43-year-old attended the gynecology clinic in order to remove her copper IUD. Speculum examination revealed that both the strings of the IUD perforated the anterior lip of the cervix. Management options were offered, the patient opted for a hysteroscopic removal. We searched the electronic databases: MEDLINE, Cochrane Library,Google Scholar,EBSCO for similar cases. Results Electronic search yielded 1821 articles; 8 were selected for inclusion. Mean age of the women was 35,37±7,781, range (26-47) years. One woman (12.5%) was nulligravida;3 women were multigravida (37,5%). Seven women (87,5%) were asymptomatic. Three IUDs (37,5%) were LNG-IUS; 5 IUDs (62,5%) contained copper. Conclusions Cervical perforation by the strings of IUD is an extremely rare clinical entity. It is asymptomatic in general and in most cases the strings of the IUD may be returned back to the endocervical canal after surgical maneuvers.
ARTICLE | doi:10.20944/preprints202112.0019.v1
Subject: Engineering, Biomedical & Chemical Engineering Keywords: Medical device; surgery; hip arthroplasty; acoustics; vibration emissions
Online: 1 December 2021 (13:43:22 CET)
The success of total hip arthroplasty depends on the experience of the surgeon, and one of the ways the surgeon currently determines the final implant insertion depth is to listen to the change in audible pitch of the hammering sound. We investigated the use of acoustic vibration emissions as a novel method for insertion quality assessment. A non-invasive contact microphone-based measurement system for insertion depth estimation, fixation and fracture detection was developed using a simplified in vitro bone/implant (n=5). 2583 audio recordings were analysed in vitro to obtain energy spectral density functions. Out of the four main resonant peaks under in vitro conditions, broach insertion depth statistically correlates to increasing 3rd and 4th peak frequencies. Degree of fixation was also observed as higher goodness of fit (0.26-0.78 vs. 0.12-0.51 between two broach sizes, the latter undersized). Finally, however, the moment of fracture could not be predicted. A cadaver in situ pilot study suggests comparable resonant frequencies in the same order of magnitudes with the bone model. Further understanding of the signal patterns are needed for an early warning system diagnostic system for imminent fractures, bone damage, improving accuracy and quality of future procedures.
Subject: Physical Sciences, Acoustics Keywords: capillary; microfluidic device; single-molecule recycling; maximum likelihood
Online: 26 May 2021 (10:50:13 CEST)
Microfluidic devices have been extensively investigated in recent years in fields including ligand-binding analysis, chromatographic separation, molecular dynamics, and DNA sequencing. To prolong the observation of a single molecule in aqueous buffer, the solution in a sub-micron scale channel is driven by the electric field and reversed after a fixed delay following each passage, so that the molecule passes back and forth through the laser focus and the time before irreversible photobleaching is extended. However, this practice requires complex chemical treatment to the inner surface of the channel to prevent unexpected sticking to the surface and the confined space renders features, such as a higher viscosity and lower dielectric constant, which slow the Brownian motion of the molecule compared to the bulk liquid. In this paper, we have fixed a capillary microchannel with an inner diameter of 2 microns on top of a piezo stage to recycle the molecule and collected the fluorescence by a confocal microscope. The passing times of the molecule through the laser focus are calculated by a real-time control system based on an FPGA and the commands of translation are given to the piezo stage through a feedback algorithm. We have achieved a maximum number of recycles of more than 200 and developed a maximum-likelihood estimation of the diffusivity of the molecule, which attains results of the same magnitude as previous reports. This technique simplifies the overall procedure of the single-molecule recycling and could be useful for the ligand-binding studies of biomolecules.
ARTICLE | doi:10.20944/preprints202105.0591.v1
Subject: Engineering, Biomedical & Chemical Engineering Keywords: cell viability; device reliability; joule heating; eDEP devices.
Online: 25 May 2021 (08:43:36 CEST)
The application of electrode-based microfluidic devices in biological entity often imposes a problem due to joule heating. The strong applied potentials or micro channels having narrow cross sections generate undesirable temperature inside the microfluidic channels leading to strong thermal distribution inside the micro channel. When intrinsic distribution of temperature, if not fix with threshold value, causes device damage or cell loss. In this work, we investigate the effects of temperature generated due to joules heating effects and we attempt to address the design constraints for minimizing the joule heating effects in the microfluidic device for developing effective microfluidic device. The device reliability was analyzed under different parametric constraints for various types of substrate materials (PDMS, PMMA, Polyimide and glass). We also attempt to investigate the effects of cell reliability due to strong temperature gradients generated through different applied potentials on different cell types. Furthermore, the response of the device performance due to different electrode configuration and different conductivity of the medium was also studied. Our investigation will eventually provide guidelines for microfluidic researchers to fabricate efficient electrode based microfluidic device which will ultimately help to choose a critical channel dimensions, threshold potentials, and conductivity of solutions in order to avoid device damage and cell loss.
Subject: Medicine & Pharmacology, Allergology Keywords: astigmatism; glaucoma; intraocular pressure; phacotrabeculectomy; Ex-PRESS device
Online: 7 December 2020 (09:43:29 CET)
To compare surgical and refractive outcomes between phacotrabeculectomy (P-Trab) and phaco with Ex-PRESS (P-Ex-PRESS) for glaucoma at 6-month follow-up. This prospective randomized controlled trial included 81 eyes; 43 (53%) and 38 (47%) were assigned to the P-Ex-PRESS and P-Trab groups, respectively. Refraction, intraocular pressure (IOP), and best-corrected visual acuity were measured. Refractive change was described by analyzing the magnitude of the cylinder, and polar analysis assessed the change in trend of astigmatism [with-the-rule, against-the-rule (ATR), oblique] evaluating mean astigmatism in centroid form. All patients showed statistically significant postsurgical decrease in IOP (P<0.05). There were no differences neither between the groups for postoperative IOP or visual outcomes, nor in astigmatism before or after surgery (P=0.61, P=0.74). In both groups, the mean pre- and postoperative astigmatism was ATR and OBL, respectively. Pre- and postoperative centroids in the P-Ex-PRESS group were 0.44±1.32 D at 177˚ and 0.35±1 D at 8˚, respectively, (P=0.5) and in the P-Trab group, 0.16±1.5 D at 141˚ and 0.39±1.38 D at 29˚, respectively (P=0.38). Both P-Ex-PRESS and P-Trab showed comparable antihypertensive efficacy in treating open-angle glaucoma in a 6-month period. Pre- and postoperative astigmatism did not differ between groups. The groups showed comparable results for final visual acuity.
REVIEW | doi:10.20944/preprints202011.0262.v1
Subject: Engineering, Mechanical Engineering Keywords: PVDF; piezoelectric polymer; wearable device; flexible sensor; electromechanical
Online: 9 November 2020 (08:31:08 CET)
The technological development of piezoelectric materials is crucial for developing wearable and flexible electromechanical devices. There are many inorganic materials with piezoelectric effects, such as piezoelectric ceramics, aluminum nitride, and zinc oxide. They all have very high piezoelectric coefficients and large piezoelectric response ranges. The characteristics of high hardness and low tenacity make inorganic piezoelectric materials unsuitable for flexible devices that require frequent bending. Polyvinylidene fluoride (PVDF) and its derivatives are the most popular materials used in flexible electromechanical devices in recent years and have high flexibility, high sensitivity, high ductility, and a certain piezoelectric coefficient. Owing to increasing the piezoelectric coefficient of PVDF, researchers are committed to optimizing PVDF materials and enhancing their polarity by a series of means to further improve their mechanical–electrical conversion efficiency. This paper reviews the latest PVDF-related optimization materials, related processing and polarization methods, and the applications of these materials such as those in wearable functional devices, chemical sensors, biosensors, and flexible actuator devices for flexible micro-electromechanical devices. We also discuss the challenges of wearable devices based on flexible piezoelectric polymer, consider where further practical applications could be.
ARTICLE | doi:10.20944/preprints202210.0161.v1
Subject: Engineering, Other Keywords: hidden Markov model; vigilance; HRV; wearable device; PVT; VST
Online: 12 October 2022 (03:18:47 CEST)
Purpose: To construct a hidden Markov model (HMM) for vigilance assessment to improve the real-time performance and accuracy of current vigilance measurement. Methods: ECG signal was collected by sensors, while the noise and baseline drift was eliminated from the original ECG signal. 10 volunteers were randomly selected. Their heart rate variability (HRV) were measured and trained parameters of the modified Hidden Markov model for vigilance assessment. Then, these data were collected to optimize using the Baum-Welch algorithm and obtained the state transition probability matrix A ̂ and the observation probability matrix B ̂. Finally, the data of three volunteers with different transition patterns of mental state were selected randomly and used the Viterbi algorithm to find the optimal state, which compared with the actual state. Results: The constructed vigilance assessment model had a high accuracy rate the accuracy rate of data prediction for these three volunteers exceeded 80%. Conclusion: The Hidden Markov model for vigilance assessment can accurately predict the vigilance level and indicate broad application prospects.
ARTICLE | doi:10.20944/preprints202107.0640.v1
Subject: Engineering, Automotive Engineering Keywords: SARS-COV-2; Loop-mediated isothermal amplification; Portable device.
Online: 28 July 2021 (17:49:56 CEST)
This paper reports the design, development, and testing of a novel, yet simple and low-cost portable device for the rapid detection of SARS-CoV-2. The device performs loop mediated isothermal amplification (LAMP) and provides visually distinguishable images of the fluorescence emitted from the samples. The device utilises an aluminium block embedded with a cartridge heater for isothermal heating of the sample and a single-board computer and camera for fluorescence detection. The device demonstrates promising results within 20 minutes using clinically relevant starting concentrations of the synthetic template. Time-to-signal data for this device are considerably lower compared to standard qPCR machine (~10-20 minutes vs >38 minutes) for 1×105 starting template copy number. The device in its fully optimized and characterized state can potentially be used as simple to operate, rapid, sensitive, and inexpensive platform for population screening as well as point-of-need SARS-CoV-2 detection and patient management.
ARTICLE | doi:10.20944/preprints202107.0181.v1
Subject: Chemistry, Analytical Chemistry Keywords: SARS-CoV-2 detection; Immunofluorescence; Paper-based diagnostic device
Online: 7 July 2021 (13:18:33 CEST)
We report on an immunofluorescent paper-based assay for the detection of severe acute respiratory symptom coronavirus 2 (SARS-CoV-2) humanized antibody. The paper-based device was fabricated by using lamination technique for easy and optimized handling. Our approach utilises a two-step strategy that involves (i) initial coating of the paper-electrode with recombinant SARS-CoV-2 nucleocapsid antigen to capture the target SARS-CoV-2 specific antibodies, and (ii) subsequent detection of SARS-CoV-2 antibodies using fluorophore-conjugated IgG antibody. The fluorescence readout was observed with fluorescence microscopy. The images were processed and quantified using a MATLAB program. The assay can selectively detect SARS-CoV-2 humanized antibodies spiked in PBS and healthy human serum samples with the relative standard deviation of approximately 6.4% (for n = 3). It has broad dynamic ranges (1 ng to 50 ng/µL in PBS and 5 to 100 ng/µL in human serum samples) for SARS-CoV-2 humanized antibodies with the detection limits of 2 ng/µL (0.025 IU/mL) and 10 ng/µL (0.125 IU/mL) in PBS and human serum samples, respectively. We believe that our assay has the potential to be used as a simple, rapid, and inexpensive paper-based diagnostic device with a portable fluorescent reader to provide point-of-care diagnosis. This assay can be used for rapid examination of a large batch of samples toward clinical screening of SARS-CoV-2 specific antibodies as a confirmed infected active case or to evaluate the immune response to a SARS-CoV-2 vaccine.
Subject: Materials Science, Biomaterials Keywords: Metal oxide; doping; semiconductor; work function tuning; energy device
Online: 18 January 2021 (14:39:57 CET)
The wide interest in developing green energy technologies stimulates the scientific community to seek, for devices, new substitute material platforms with low environmental impact, ease of production and processing and long-term stability. The synthesis of metal oxide (MO) semiconductors fulfils these requirements and efforts are addressed at optimizing their functional properties, through improvement of charge mobility or energy level alignment. Two MOs have rising perspectives for application in light harvesting devices, mainly for the role of charge selective layers but also as light absorbers, namely MoO3 (an electron blocking layer) and Co3O4 (a small band gap semiconductor). The need to achieve better charge transport has prompted us to attempt doping strategies with vanadium (V) ions that, when combined with oxygen in V2O5, produce a high work function MO. We report on subcritical hydrothermal synthesis of V-doped mesostructures of MoO3 and of Co3O4, in which a tight control of the doping is exerted by tuning the relative amounts of reactants. We accomplished a full analytical characterization of these V-doped MOs that unambiguously demonstrates incorporation of the vanadium ions in the MO crystal lattice, as well as effects on the optical properties and work function. We foresee a promising future use of these materials as charge selective materials in energy devices based on multilayer structures.
ARTICLE | doi:10.20944/preprints202010.0506.v1
Subject: Chemistry, Analytical Chemistry Keywords: Paper-based microfluidic device; colorimetric; multiple detection; smartphone application
Online: 26 October 2020 (08:56:58 CET)
Paper-based microfluidic analysis devices (μPADs) have attracted attention as a cost-effective platform for point-of-care testing (POCT), food safety, and environmental monitoring. Recently, three-dimensional (3D)-μPADs have been developed to improve the performance of μPADs. For accurate diagnosis of diseases, however, 3D-μPADs need to be developed to simultaneously detect multiple biomarkers. Here, we report a 3D-μPADs platform for the detection of multiple biomarkers that can be analyzed and diagnosed with a smartphone. The 3D-μPADs were fabricated using a 3D digital light processing printer and consisted of a sample reservoir (300 µL) connected to 24 detection zones (of 4 mm in diameter) through 8 microchannels (of 2 mm in width). With the smartphone application, eight different biomarkers related to various diseases were detectable in concentrations ranging from normal to abnormal conditions: glucose (0–20 mmol/L), cholesterol (0–10 mmol/L), albumin (0–7 g/dL), alkaline phosphatase (0–800 U/L), creatinine (0–500 µmol/L), aspartate aminotransferase (0–800 U/L), alanine aminotransferase (0–1000 U/L), and urea nitrogen (0–7.2 mmol/L). These results suggest that 3D-µPADs can be used as a POCT platform for simultaneous detection of multiple biomarkers.
ARTICLE | doi:10.20944/preprints202008.0165.v1
Subject: Medicine & Pharmacology, Pediatrics Keywords: multiparticulates, administration device, acceptability, paediatric formulation, mouthfeel, oral syringe
Online: 6 August 2020 (12:00:05 CEST)
The popularity of multiparticulate formulations (MPs) as a paediatric dosage form continues to increase. MPs comprise of multiple small units that are easy-to-swallow. Currently, MPs are commonly manufactured into unit doses that are either swallowed whole or opened prior to administration. While this is an acceptable approach, dosing is envisioned to be optimized with a ‘standard’ paediatric device which can better harness the flexible dosing potential of MPs. We evaluated a novel oral syringe (SympfinyTM) that is being developed as a tool to dispense and administer MPs to children. Forty children, 4-12 years old, received 0.5, 1.2, and 2.0 mL doses of placebo MPs using the oral syringe with spring water or a drink of choice to complete sample intake. Acceptability was recorded as those able to completely swallow the dose and participants also rated dose acceptability on a 5-point scale. The ability to completely swallow the dose decreased as dose volume increased; the smallest dose was completely swallowed by 87.5% (35/40) children, and 69.4% (27/39) of children confirmed their willingness to take the sample as a daily medicine. Larger doses, 1.2 and 2.0 mL, gave values of 55% and 57.5% for the doses completely swallowed and 58.8% and 51.72% for willingness to take the sample as a daily medicine, respectively. Use of a drink of choice showed no increase in swallowability as compared with water. The novel oral syringe being developed is an appropriate device for dispensing doses flexibly and administering neutral tasting MPs directly to the mouth in the lower dose range without the need for a co-administration vehicle in children aged 4-12 years.
ARTICLE | doi:10.20944/preprints202005.0074.v1
Subject: Arts & Humanities, Philosophy Keywords: VR; aging effect; gender difference; control device; wayfinding strategy
Online: 5 May 2020 (11:32:12 CEST)
The application of Virtual Reality in a driving simulation is not novel, yet little is known about the use of this technology by senior populations. The effects of age, sex, control device (joystick or handlebar), and task type on wayfinding proficiency using a virtual reality (VR) driving simulation were explored. The driving experimental model involved 96 randomly recruited participants, including 48 young people and 48 seniors (split evenly by gender in each group). The experimental results and statistical analyses indicate that in a VR driving scenario task type significantly affected VR driving performance. Navigational scores were significantly higher for the straight (easy) task than for the curved (difficult) task. The aging effect was the main reason for significant and interacting effects of sex and control device. It was found that interactions between age and sex difference indicated that the young group exhibited better wayfinding performance than the senior group, and in the young group males had better performance than females. Similarly, interactions between age and control device indicated that the handlebar control device type resulted in better performance than the joystick device in the young group, but no difference was found in the senior group due to age or learning effects. Findings provide an understanding of the evaluation of the interface designs of navigational support systems, taking into consideration any effects of age, sex, control device, and task type within three-dimensional VR games and driving systems. With a VR driving simulator, seniors can test drive inaccessible products, such as electric bicycles or cars, using a computer at home.
ARTICLE | doi:10.20944/preprints201907.0060.v1
Subject: Engineering, Electrical & Electronic Engineering Keywords: IoT; wearable device; machine learning; streaming data; sleep posture
Online: 3 July 2019 (09:55:40 CEST)
Sleep postures monitoring systems in the hospital aim at transforming sensing signals into quantitative data to characterize the sleep behaviors of the patient. However, a home-care sleep posture monitoring system needs to be user friendly. In this paper, we present iSleePost - a user-friendly home-care intelligent sleep posture monitoring system. We address the labor-intensive labeling issue of traditional machine learning approaches in the training phase. Our proposed mobile health (mHealth) system leverages the communications and computation capabilities of mobile phones for provisioning a continuous sleep posture monitoring service. Our experiments show that iSleePost can achieve 90 percent accuracy in recognizing sleep postures. More importantly, iSleePost demonstrates that an easily-wear wrist sensor can accurately quantify sleep postures.
ARTICLE | doi:10.20944/preprints201806.0140.v1
Subject: Engineering, Electrical & Electronic Engineering Keywords: Silicon dioxide, Piezoelectric device, Zinc oxide, RF sputtering deposition
Online: 8 June 2018 (14:00:29 CEST)
In this paper, we present a study of various ZnO/SiO2-stacked thin film structures for flexible micro-energy harvesting devices. Two groups of micro-energy harvesting devices, SiO2/ZnO/SiO2 micro-energy generators (SZS-MGs) and ZnO/SiO2/ZnO micro-energy generators (ZSZ-MGs), were fabricated by stacking both SiO2 and ZnO thin films, and the resulting devices were characterized. With a particular interest in the fabrication of flexible devices, all the ZnO and SiO2 thin films were deposited on ITO-coated PEN substrates using an RF magnetron sputtering technique. The effects of the thickness and/or position of the SiO2 films on the device performance were investigated by observing the variations of output voltage in comparison with that of a control sample. As a result, compared to the ZnO single-layer device, all the ZSZ-MGs showed much better output voltages, while all the SZS-MG showed only slightly better output voltages. Among the ZSZ-MGs, the highest output voltages were obtained from the ZSZ-MGs where the SiO2 thin films were deposited using a deposition power of 150 W. Overall, the device performance seems to depend significantly on the position as well as the thickness of the SiO2 thin films in the ZnO/ SiO2-stacked multilayer structures, in addition to the processing conditions.
ARTICLE | doi:10.20944/preprints201610.0001.v1
Subject: Engineering, Civil Engineering Keywords: Pump station, Sump, Anti-vortex device, Flow pattern, Vortex
Online: 3 October 2016 (11:15:07 CEST)
A pump station is a very important flood control facility for mitigating inundation of urban lowland areas. It is not easy to secure a site to increase the capacity of a pump station in an urban area because of various limitations or to maximize the discharge capacity of the pump sump. Adding a facility to improve the pump capacity of a pump station may affect the flow characteristics, such as unexpected increases in the flow velocity and vorticity, and cause severe problems with operating the pump station. To solve those problems, anti-vortex devices (AVDs) have been developed and adopted for appropriate design standards. The Korean design criteria for AVDs are based on experience and foreign standards because not enough data on the AVD are available. In this study, the flow in the sump was numerically simulated at various AVD heights to collect information on improving the design and efficiency of a pump station. Consequently, an appropriate height for the AVD and changes in the flow pattern and vortex in the pump sump were determined and compared with 12 cases of inflow conditions with respect to the vertical location.
ARTICLE | doi:10.20944/preprints202210.0485.v2
Subject: Earth Sciences, Environmental Sciences Keywords: Remote sensing; Night; Light pollution; streetlight; radiometer; Lighting device inventory
Online: 3 November 2022 (08:42:55 CET)
This paper describes the use of an open source instrument called LANcube v2 to build a lighting device inventory. The LANcube v2 is and instrument having 5 color sensitive sensors, each on a face of a cube. The instrument can be mounted on a car roof in order to create a map of the artificial light at night while roaming the streets and roads. Based on the temporal variations of the detected signal on various cube’s faces, we developed a method of finding the position in 3D of each lighting device. The lamp spectral types can be determined thanks to the color balance of the raw Red (R) Green (G) Blue (B) and Clear (C) color bands. If one assumes a typical angular photometry of a lighting device with respect to its location, it is possible to estimate its luminous flux. Such information allows us to build a lighting devices inventory of a territory. One advantage of that new method is that it can provide information about the private lighting devices that are always excluded from public lighting inventories. We will compare the inventory extracted with that new methodology with an in situ lamp inventory made for two villages in Canada. This will allow us to emphasize the strengths and limitations of the method by comparing to the ground truth.
ARTICLE | doi:10.20944/preprints202207.0398.v1
Subject: Engineering, Electrical & Electronic Engineering Keywords: Scaled device; Ultra-Thin gate oxide; DIBL; Direct tunneling current
Online: 26 July 2022 (09:37:33 CEST)
With the proportional reduction of MOSFET size, the leakage-to-barrier reduction (DIBL) effect leads to a more significant increase in the tunneling current on the gate, and the appearance of the gate tunneling current also seriously affects the static characteristics of the device. In this paper, a new theoretical model of the relationship between the direct tunneling current and the thickness of the oxide layer under the DIBL effect is proposed for the MOSFET device with ultra-thin oxide layer. On this basis, the characteristics of the MOSFET device are studied in detail by using HSPICE, and their working conditions are quantitatively analyzed. The characteristic variation trend of small-size devices under the influence of gate tunneling current is predicted. The simulation results using BSIM4 model are consistent with the theoretical model. The theory and data in this paper will provide useful reference for large scale integrated circuit design.
ARTICLE | doi:10.20944/preprints202107.0651.v1
Subject: Behavioral Sciences, Applied Psychology Keywords: multiple measures synchronization; automatic device integration; open-source; PsychoPy; Unity
Online: 29 July 2021 (11:48:02 CEST)
Background: The human mind is multimodal. Yet most behavioral studies rely on century-old measures such as task accuracy and latency. To create a better understanding of human behavior and brain functionality, we should introduce other measures and analyze behavior from various aspects. However, it is technically complex and costly to design and implement the experiments that record multiple measures. To address this issue, a platform that allows synchronizing multiple measures from human behavior is needed. Method: This paper introduces an opensource platform named OpenSync, which can be used to synchronize multiple measures in neuroscience experiments. This platform helps to automatically integrate, synchronize and record physiological measures (e.g., electroencephalogram (EEG), galvanic skin response (GSR), eye-tracking, body motion, etc.), user input response (e.g., from mouse, keyboard, joystick, etc.), and task-related information (stimulus markers). In this paper, we explain the structure and details of OpenSync, provide two case studies in PsychoPy and Unity. Comparison with existing tools: Unlike proprietary systems (e.g., iMotions), OpenSync is free and it can be used inside any opensource experiment design software (e.g., PsychoPy, OpenSesame, Unity, etc., https://pypi.org/project/OpenSync/ and https://github.com/moeinrazavi/OpenSync_Unity). Results: Our experimental results show that the OpenSync platform is able to synchronize multiple measures with microsecond resolution.
ARTICLE | doi:10.20944/preprints202102.0574.v1
Subject: Social Sciences, Accounting Keywords: self-report; device-based measured; physical activity; reliability; validity; stability
Online: 25 February 2021 (10:27:24 CET)
Quantification of physical activity (PA) depends on the type of measurement and analysis method making it difficult to compare adherence to PA guidelines. Therefore, test-retest reliability, criterion validity, and stability for self-reported (i.e. questionnaire and diary) and device-based measured (i.e. accelerometry with 10/60 second epochs) PA was compared in 32 adults and 32 children from the SMARTFAMILY study to examine if differences in these measurement tools are systematic. PA was collected during two separate measurement weeks and the relationship for each quality criteria was analyzed using Spearman correlation. Results showed the highest PA values for questionnaires followed by 10-second and 60-second epochs measured by accelerometers. Levels of PA were lowest when measured by diary. Only accelerometry demonstrated reliable, valid, and stable results for the two measurement weeks, the questionnaire yielded mixed results and the diary showed only few significant correlations. Overall, higher correlations for the quality criteria were found for moderate than for vigorous PA and the results differed between children and adults. Since the differences were not found to be systematic, the choice of measurement tools should be carefully considered by anyone working with PA outcomes, especially if vigorous PA is the parameter of interest.
ARTICLE | doi:10.20944/preprints202003.0229.v1
Subject: Medicine & Pharmacology, Cardiology Keywords: heart failure; left ventricular assist device; cardiac recovery; mechanical circulation
Online: 13 March 2020 (10:11:43 CET)
In this paper, we aim to assess the electric current parameters and report the analysis of the associated degree of ventricular recovery during left ventricular assist device (LVAD) support. An assumption was made there is a linear relationship between ventricular recovery degree and the pump electric current pulsatility index (PI). The experimental study was carried out using the ViVitro Pulse Duplicator System with Sputnik 1 LVAD connected. Cardiac output (CO) and cardiac power output (CPO) were used as a measure of ventricular recovery degree. Different heart rates (HR) (59, 73, 86 bpm) and pump speeds (7600–8400 rpm in 200 rpm steps) were investigated. Ventricular stroke volumes in the range of 30–80 ml for each heart rate at certain pump speed were used. The obtained relationships of CO and CPO vs. PI was linear as the coefficients of determination for each regression curve were more than 0.8. CO vs. PI: R2=0.9218; 0.9271; 0.9172 and CPO vs. PI: R2=0.8517; 0.841; 0.8244 for HR=59 bpm; 73 bpm; 86 bpm, respectively. Study findings suggest that adequate interpretation of parameters could potentially serve as a valuable clinical tool to assess ventricular recovery based on LVAD infrastructure without requiring any special hemodynamic assessment.
ARTICLE | doi:10.20944/preprints202002.0320.v1
Subject: Materials Science, General Materials Science Keywords: diffusion bonding; Hastelloy B; corrosion; sulfuric acid; micro process device
Online: 23 February 2020 (12:00:15 CET)
Sulphuric acid is a widely used raw material in the chemical industry. Its corrosive effect on materials varies considerably, depending on impurities, temperature and water content. Accordingly, good corrosion resistance under all conditions is very difficult to achieve. This is especially an issue for micro process apparatus with very thin walls. Furthermore, such devices are often joint by diffusion bonding what may alter materials properties due to high temperatures and long dwell times. In fact, for each new material, the diffusion bonding parameters must be optimized and the impact on mechanical as well as corrosion properties must be investigated. In this paper, two high molybdenum alloys, namely Hastelloy B3 and BC-1, were evaluated. Diffusion bonding tests were performed using ten layers of sheet material in between round stock. Corrosion tests were performed in 70 % sulphuric acid at 100°C for 1000 h. Tensile tests on both alloys were carried out for different material conditions, to determine the change in mechanical strength and elongation at fracture values. In general, independent of the condition of the materials, the fracture behavior of both alloys was found to be ductile and the specimens show the typical dimple structure, in the case of diffusion bonded samples, interrupted by weak spots or rather non-bonded areas. These areas are obviously causing the onset of material failure and thus, a degradation of mechanical properties. Tensile samples, that were aged in 70% sulphuric acid at 100°C for 1000 hours showed local corrosion attacks at the grain boundaries at the circumferential surfaces and especially at the joining planes – for Hastelloy B3 much more pronounced than for Hastelloy BC-1. Accordingly, a further decrease of both, the stress- and elongation at fracture values is observed. However, the typical material parameters like 0.2 % yield strength used for dimensioning components are found to be sufficient high, even when operating the materials under such harsh conditions. When concluding the results, at least Hastelloy BC-1 reveals both sufficient good mechanical properties and an excellent corrosion resistance, regardless of the heat treatment, and could be considered for manufacturing micro-process engineering apparatuses operated in a sulphuric acid environment. This is a significant advance compared to the results obtained within a AiF project, previously carried out on four different materials to investigate the corrosion resistance in sulphuric acid.
ARTICLE | doi:10.20944/preprints201905.0047.v1
Subject: Materials Science, General Materials Science Keywords: young interferometer; depolarization measurement; modulation of depolarization; liquid crystal device
Online: 6 May 2019 (10:22:05 CEST)
In a depolarizing instrument, such as a broadband imaging spectrometer, the depolarizers are placed on the system for stabilization the optical signal. They are also used to reduce measurements offsets due to strong polarization dependence, which produce drastic deterioration of the signal to noise ratio. Dynamic depolarizer with a controllable degree of polarization is also required to study the effect of noise on quantum information. The article described a new instrument for characterization the variable depolarizer with features which make it different from a polarimetric system. The analysing system based on the simple structural design and has good stability for real-time measurement. A practical application of the described interferometer system for variable depolarizer characterization is also presented.
ARTICLE | doi:10.20944/preprints201712.0126.v1
Subject: Engineering, Mechanical Engineering Keywords: piezoresistive accelerometer; sensor design; biomechanical device; head injuries monitoring; TBI
Online: 18 December 2017 (15:42:12 CET)
This work focuses on the design improvement of a tri-axial piezoresistive accelerometer specifically designed for head injuries monitoring where medium-G impacts are common, for example in sports such as racing cars or American Football. The device requires the highest sensitivity achievable with a single proof mass approach, and a very low error (<1%) as the accuracy for these types of applications is paramount. The optimization method differs from previous work as it is based on the progressive increment of the sensor mass moment of inertia (MMI) in all three axes. The work numerically demonstrates that an increment of MMI determines an increment of device sensitivity with a simultaneous reduction of cross-talk in the particular axis under study. The final device shows a sensitivity increase of about 80% in the Z-axis and a reduction of cross-talk of 18% respect to state-of-art sensors available in the literature. Sensor design, modelling and optimization are presented, concluding the work with results, discussion and conclusion.
ARTICLE | doi:10.20944/preprints201705.0123.v1
Subject: Mathematics & Computer Science, General & Theoretical Computer Science Keywords: Mobile device threats; mobile device malware; reverse proxy server; cyber security; android security; ios security; abuse of local area network; DNS spoofing; DNS hijacking
Online: 16 May 2017 (13:23:18 CEST)
Mobile devices have become tools we spend our free time where we carry them with us every moment, they allow us to interact with the environment, we immortalize the moment when necessary. These devices which we spend most of our daily life become very common in recent years and even there are unique business areas emerged. It was announced that the number of people using smartphones is over than 2.5 billion in the first quarter of 2016. As people become more addicted to mobile technology, they become the target of malevolent people. A huge increase in the number of mobile malware is observed as the number of the users increase. Billions of users at risk day by day due to the development of the methods. We have addressed the recent methods used and the types of malware that target mobile devices in our study. We have mentioned the proxy server and reverse proxy server operation logic. We discuss the method of turning mobile devices into reverse proxy servers, risks involved and protection methods.
ARTICLE | doi:10.20944/preprints202204.0069.v2
Subject: Medicine & Pharmacology, Gastroenterology Keywords: hepatocellular carcinoma; conventional transarterial chemoembolization; emulsion; lipiodol; glass membrane emulsification device
Online: 6 June 2022 (05:53:21 CEST)
Background: Transarterial chemoembolization (TACE) is the standard treatment for BCLC-B hepatocellular carcinoma (HCC). A novel glass membrane emulsification device (GMD) produces a high percentage of water/oil emulsions with homogeneous and stable droplets. There are few reports on the efficacy of GMD-conventional-TACE (GMD-c-TACE)；therefore, we aimed to evaluate the effectiveness of GMD-c-TACE. Methods: Seventy-one patients with HCC with tumor diameter <5 cm who underwent c-TACE with and without GMD were included in this study to investigate local recurrence and hepatic functional reserve. Results: The local recurrence rates of TACE without GMD were 3.0% at 6 months, 16.7% at 12 months, and 35.0% at 18 months, around where it plateaued. Hence, the local recurrence rates in the GMD-c-TACE group were 7.7% at 14 months and 23.1% at 20 months, respectively. Thus, GMD-c-TACE had a significantly lower local recurrence. Multivariate analysis showed that GMD-c-TACE could suppress local recurrence and maintain hepatic reserve. Conclusions: GMD-c-TACE allows dense lipiodol accumulation in the tumor and attainment of good local control. Additionally, the inhibition of the release of anticancer drugs may maintain hepatic reserve. GMD-c-TACE is useful in preventing local recurrence and is expected to become the standard treatment form of c-TACE in the future.
ARTICLE | doi:10.20944/preprints202203.0189.v1
Subject: Mathematics & Computer Science, Information Technology & Data Management Keywords: Smart device; Users behavior; human computer interaction; exploratory analysis; statistical methods
Online: 14 March 2022 (12:28:44 CET)
Purpose: The use of smart devices has increased greatly in the last ten years with users reaching out to the possibility to do more with them especially in the networking front. In this context there is a need to understand the connection between users’ social demographic factors and their way to related to their smart devices. Objective: This study was designed to evaluate the senso of belonging of a community in order to evaluate intangible benefits that employees may gain from a more immerse relationship with their devices. Method: We used a dataset of 586 anonymous respondent of an existing survey designed for capturing the relationships that humans develop with their smart devices. In particular, we investigate the relationships with smart device and particular background variables of the respondents using a chi-square test. Results: The study showed that there is a significant relationship between users’ sex and smart device type and their dependency on smart device. Male tends to think that smart device (in general) enables them to connect with a larger community. At the same time, female using smart phones feels more connected more to large community than when using other smart devices. Conclusion: This study provided several significant findings that confirm and strength previous literature works on the subject. In addition, socio demographics variables (like gender) as well as the type of smart device present a correlation between the smart device users and their tendency to stay in touch with a larger community.
ARTICLE | doi:10.20944/preprints202103.0644.v1
Subject: Mathematics & Computer Science, Artificial Intelligence & Robotics Keywords: stress; wearable device; machine learning; smart watch; heart rate variability; electrocardiogram
Online: 25 March 2021 (16:24:00 CET)
Stress has been identified as one of the major causes of automobile crashes which then lead to high rates of fatalities and injuries each year. Stress can be measured via physiological measurements and in this study the focus will be based on the features that can be extracted by common wearable devices. Hence the study will be mainly focusing on the heart rate variability (HRV). This study is aimed to develop a good predictive model that can accurately classify stress levels from ECG-derived HRV features, obtained from automobile drivers, testing different machine learning methodologies such as K-Nearest Neighbor (KNN), Support Vector Machines (SVM), Multilayer Perceptron (MLP), Random Forest (RF) and Gradient Boosting (GB). Moreover, the models obtained with highest predictive power will be used as reference for the development of a machine learning model that would be used to classify stress from HRV features derived from HRV measurements obtained from wearable devices. We demonstrate that MLP was the ideal stress classifier by achieving a Recall of 80%. The proposed method can be also used on all applications in which is important to monitor the stress level e. g. in physical rehabilitation, anxiety relief or mental wellbeing.
ARTICLE | doi:10.20944/preprints201803.0228.v1
Subject: Physical Sciences, General & Theoretical Physics Keywords: Measurement-Device-Independent Quantum Key Distribution; Quantum Optics; Two-Photon Interference
Online: 27 March 2018 (15:24:03 CEST)
Measurement-Device-Independent Quantum Key Distribution (MDI-QKD) is a two-photon protocol devised to eliminate eavesdropping attacks that interrogate or control the detector in realized quantum key distribution systems. In MDI-QKD, the measurements are carried out by an untrusted third party, and the measurement results are announced openly. Knowledge or control of the measurement results gives the third party no information about the secret key. Error-free implementation of the MDI-QKD protocol requires the crypto-communicating parties, Alice and Bob, to independently prepare and transmit single photons that are physically indistinguishable, with the possible exception of their polarization states. In this paper, we apply the formalism of quantum optics and Monte Carlo simulations to quantify the impact of small errors in wavelength, bandwidth, polarization and timing between Alice's photons and Bob's photons on the MDI-QKD quantum bit error rate (QBER). Using published single-photon source characteristics from two-photon interference experiments as a test case, our simulations predict that the finite tolerances of these sources contribute (4.04+/-20/Nsifted) to the QBER in an MDI-QKD implementation generating an Nsifted-bit sifted key.
ARTICLE | doi:10.20944/preprints202106.0438.v1
Subject: Physical Sciences, Acoustics Keywords: holography; hologram; computer-generated hologram; holographic projection; time-division; digital micromirror device
Online: 16 June 2021 (10:33:00 CEST)
Holographic projection is a simple projection because it enlarges or reduces reconstructed images without using a zoom lens. However, one major problem associated with this projection is the deterioration of image quality as the reconstructed image enlarges. In this paper, we propose a time-division holographic projection, in which the original image is divided into blocks and the holograms of each block are calculated. Using a digital micromirror device (DMD), the holograms were projected at high speed to obtain the entire reconstructed image. However, the holograms on the DMD need to be binarized, thereby causing uneven brightness between the divided blocks. We correct this by controlling the displaying time of each hologram. Additionally, combining both the proposed and noise reduction methods, the image quality of the reconstructed image was improved. Results from the simulation and optical reconstructions show we obtained a full-color reconstruction image with reduced noise and uneven brightness.
Subject: Engineering, Automotive Engineering Keywords: Magnetic levitating system; Low-cost device; Semi-active control; Education for engineering
Online: 13 April 2021 (13:57:09 CEST)
This paper describes how to construct a low-cost magnetic levitation system (MagLev). The MagLev has been intensively used in the engineering education, allowing instructors and students to learn through hands-on experiments essential concepts, such as electronics, electromagnetism, and control systems. Built from scratch, the proposed MagLev depends only on simple, low-cost components readily available on the market. In addition to showing how to construct the MagLev, this paper presents a semi-active control strategy which seems novel when applied in the MagLev. Experiments performed in the laboratory have compared the proposed control scheme with the classical PID control. The corresponding real-time experiments illustrate both the effectiveness of the approach and the potential of the MagLev for education.
ARTICLE | doi:10.20944/preprints202011.0525.v1
Subject: Engineering, Automotive Engineering Keywords: flexible functional device; thin film coating; slot-die; surface tension; coating gap
Online: 20 November 2020 (07:08:12 CET)
Slot-die coatings are advantageous when used for coating large-area flexible devices; in particular, the coating width can be controlled, and simultaneous multi-layer coatings can be processed. Till date, the effects of ink widening and coating gap on the coating thickness have only been considered in a few studies. To this end, we developed two mathematical models to accurately estimate the coating width and thickness considering these two effects. We used root mean square deviation (RMSD) to experimentally verify the developed method. The coating width was seen to increase and the coating thickness was seen to decrease when the coating gap was increased. Experimental results showed that the estimation performances of the coating width and thickness models were as high as 98.46 % and 95.8 %, respectively. We believe that the developed models can be useful for determining the coating conditions according to the ink properties to coat a functional layer with user-defined widths and thicknesses in both lab- and industrial-scale roll-to-roll slot-die coating processes.
ARTICLE | doi:10.20944/preprints202011.0064.v1
Subject: Medicine & Pharmacology, Allergology Keywords: manual muscle testing; neuromuscular diagnostics; force profiles; reproducibility; Adaptive Force; handheld device
Online: 2 November 2020 (16:36:04 CET)
The manual muscle test (MMT) is a flexible diagnostic tool, which is used in many disciplines, applied in several ways. The main problem is the subjectivity of the test. The MMT in the version of a “break test” depends on the tester’s force rise and the patient’s ability to resist the applied force. As a first step, the investigation of the reproducibility of the testers’ force profiles is required for valid application. The study examined the force profiles of n=29 testers (n=9 experiences (Exp), n=8 little experienced (LitExp), n =12 beginners (Beg)). The testers performed 10 MMTs according to the test of hip flexors, but against a fixed leg to exclude the patient’s reaction. A handheld device recorded the temporal course of the applied force. The results show significant differences between Exp and Beg concerning the starting force (padj=0.029), the ratio of starting to maximum force (padj=0.005) and the normalized mean Euclidean distances between the 10 trials (padj=0.015). The slope is significantly higher in Exp vs. LitExp (p=0.006) and Beg (p=0.005). The results also indicate that experienced testers show inter-tester differences and partly even a low intra-tester reproducibility. That highlights the necessity of an objective MMT-assessment. Furthermore, an agreement on a standardized force profile is required – a suggestion is given.
ARTICLE | doi:10.20944/preprints201910.0018.v1
Subject: Biology, Ecology Keywords: allergenic pollen; ozone; automatic real-time device; image analysis; principal component analysis
Online: 2 October 2019 (06:02:31 CEST)
Alnus glutinosa is important woody plant in Lithuanian forest ecosystems. Knowledge of fluorescence properties of black alder pollen is necessary for scientific and practical purposes. By the results of the study we aimed to evaluate possibilities of identifying Alnus glutinosa pollen fluorescence properties by modeling ozone effect and applying two different fluorescence-based devices. To implement experiments, black alder pollen was collected in a typical habitat during the annual flowering period in 2018-2019. There were three groups of experimental variants, which differed in the duration of exposure to ozone, conditions of pollen storage before the start of the experiment, and the experiment start time. Data for pollen fluorescence analysis were collected using two methods. The microscopy method was used in order to evaluate the possibility of employing image analysis systems for investigation of pollen fluorescence. The second data collection method is related to the automatic device identifying pollen in real-time, which uses the fluorescence method in the pollen recognition process. Data were assessed employing image analysis and principal component analysis (PCA) methods. Digital images of ozone-exposed pollen observed under the fluorescence microscope showed the change of the dominant green colour towards the blue spectrum. Meanwhile, the automatic detector detects more pollen whose fluorescence is at the blue light spectrum. It must be noted that assessing pollen fluorescence several months after exposure to ozone, no effect of ozone on fluorescence remains.
REVIEW | doi:10.20944/preprints201812.0290.v1
Subject: Materials Science, Nanotechnology Keywords: Scanning tunneling microscopy; unimolecular electronics; molecular device; monolayer; coordination chemistry; interfaces; nanotechnology
Online: 24 December 2018 (15:39:00 CET)
The development of organic devices has been focused in their miniaturization in order to obtain denser and faster electronic circuits. The challenge is to build the devices adding atom by atom or molecule by molecule until the desired structure is achieved. To do this job, techniques able to see and manipulate matter at this scale are needed. Scanning tunneling microscopy has been the selected technique by scientists to develop smart and functional unimolecular devices. This review article compiles the latest developments in this field giving examples of supramolecular systems monitored and fabricated at molecular scale by bottom-up approaches using STM at solid/liquid interface.
ARTICLE | doi:10.20944/preprints201703.0184.v1
Subject: Engineering, Mechanical Engineering Keywords: MEMS S&A device; centrifugal insurance mechanism; nonlinear dynamic method; parametric study
Online: 24 March 2017 (10:04:55 CET)
MEMS (Micro-electromechanical Systems) becomes important increasingly due to the smarter and smaller fuze used in OICW (Objective Individual Combat Weapon). MEMS Safety and Arming (S&A) device is employed in different platforms and regions for small caliber projectile. Therefore, it is necessary to make a parametric study of the MEMS S&A device in different apply environments and explore the main sensitive factors of the MEMS S&A device to provide reference for designs. In this paper, based on the MEMS S&A device designed by our term, theory and finite element models are established, and the centrifugal insurance mechanism of the MEMS S&A device is parametric studied under the different speeds, temperature and thickness of the model by nonlinear dynamic method. By comparing the experimental and predicted results, the established FEM model is verified, and the conclusion is that the temperature and the centrifugal force are the main sensitive factors in the centrifugal insurance mechanism. In summary, we can suggest that the application environment, which the MEMS S&A device is suitable for, is the temperature equal to or slightly greater than normal temperature and the rotating speed higher than35000r/min of small caliber projectile.
ARTICLE | doi:10.20944/preprints202209.0129.v1
Subject: Engineering, Electrical & Electronic Engineering Keywords: Hardware Security; Physical Unclonable Functions; Device Authentication; Key Generation; Reconfigurable Devices; Embedded Systems
Online: 9 September 2022 (04:16:24 CEST)
Generation of unique identifiers extracted from the physical characteristics of the underlying hardware ensures the protection of electronic devices against counterfeiting and provides security to the data they store and process. This work describes the design of an efficient Physical Unclonable Function (PUF) based on the differences in the frequency of Ring Oscillators (ROs) with identical layout due to variations in technological processes involved in the manufacture of the integrated circuit. The logic resources available in the Xilinx Series-7 programmable devices are exploited in the design to make it more compact and achieve an optimal bit-per-area rate. On the other hand, the design parameters can also be adjusted to provide a high bit-per-time rate for a particular target device. The PUF has been encapsulated as a configurable Intellectual Property (IP) module, providing it with an AXI4-Lite interface to ease its incorporation into embedded systems in combination with soft- or hard-core implementations of general-purpose processors. The capability of the proposed RO-PUF to generate implementation-dependent identifiers has been extensively tested, using a series of metrics to evaluate its reliability and robustness for different configuration options. Finally, in order to demonstrate its utility to improve system security, the identifiers provided by RO-PUFs implemented on different devices have been used in a Helper Data Algorithm (HDA) to obfuscate and retrieve a secret key.
ARTICLE | doi:10.20944/preprints202110.0316.v2
Subject: Engineering, Biomedical & Chemical Engineering Keywords: cardiac surgery; bone fracture; median sternotomy; rehabilitation; ossicication; functional mobility; assistanve device; feedback
Online: 7 December 2021 (23:36:05 CET)
Patients often need the use of their arms to assist with functional activities, but after bone disruption, pushing is frequently limited to less than 4.5 kg. No method exists to measure arm weight bearing objectively in clinical settings. This project aimed to design, construct, and test a walker for patients who need to limit arm force to prevent excessive bone stress during post-fracture (iatrogenic or traumatic) ossification. First, a qualitative study was conducted to obtain critiques of a Clinical Force Measuring (CFM) walker prototype from rehabilitation professionals. Key statements and phrases were coded that allowed “themes” to emerge from transcribed interviews, which guided device revisions. Next, a second CFM Walker prototype was designed based on the qualitative data and device criteria/constraints and finally tested. The result was fabrication of a new lightweight, streamlined, and cost-effective prototype walker with a simple visual display and auditory cue with upper limit alarms. Key features included attachments for medical equipment and thin film force-sensing resistors integrated into the walker handles that progressively activated 3 LEDs and a buzzer when arm force exceeded programmed thresholds. The innovative CFM Walker will help patients with restricted arm weight bearing, especially elderly adults, recover safer and faster in the future.
ARTICLE | doi:10.20944/preprints202109.0444.v1
Subject: Engineering, Electrical & Electronic Engineering Keywords: interfacial phase change memory; phase change memory; artificial synaptic device; superlattice; neuromorphic devices
Online: 27 September 2021 (11:32:46 CEST)
Corresponding to the principles of biological synapses, an essential prerequisite for hardware neural networks using electronics devices is continuous regulation of conductance. We implemented artificial synaptic characteristics in a (GeTe/Sb2Te3)16 iPCM with a superlattice structure under optimized identical pulse trains. Based on atomically controlling the Ge switch in the phase transition that appears in the GeTe/Sb2Te3 superlattice structure, multiple conductance states were implemented by applying the appropriate electrical pulses. Furthermore, we found that the bidirectional switching behavior of a (GeTe/Sb2Te3)16 iPCM can achieve a desired resistance level using the pulse width. Therefore, we also fabricated a Ge2Sb2Te5 PCM and designed a pulse scheme based on the phase transition mechanism to compare to the (GeTe/Sb2Te3)16 iPCM. We designed an identical pulse scheme that implements linear and symmetrical LTP and LTD based on the iPCM mechanism. As a result, the (GeTe/Sb2Te3)16 iPCM showed relatively excellent synaptic characteristics by implementing gradual conductance modulation, a nonlinearity value of 0.32, and LTP/LTD 40 conductance states using identical pulses trains. Our results demonstrate the general applicability of the artificial synaptic device for potential use in neuro-inspired computing and next generation non-volatile memory.
ARTICLE | doi:10.20944/preprints202109.0106.v1
Subject: Medicine & Pharmacology, Cardiology Keywords: mechanical circulatory support; heart transplantation; survival curve; ventricular assist device; extracorporeal membrane oxygenation
Online: 6 September 2021 (14:39:13 CEST)
BACKGROUND: The number of waitlisted patients requiring mechanical circulatory support (MCS) as a bridge to heart transplantation is increasing. The data concerning the results of double-bridge strategy are limited. We sought to investigate the post-transplant outcomes across the different bridge strategies. METHODS: We retrospectively reviewed a heart transplantation database from Jan 2009 to Jan 2019. Intra-aortic balloon pump (IABP), extracorporeal membrane oxygenation (ECMO), and ventricular assist devices (VAD) were the MCS that we investigated. The pre- and post-transplant characteristics and variables of patients bridged with the different types of MCS were collected. The post-transplant survival was compared using Kaplan-Meier survival analysis. RESULTS: A total of 251 heart transplants were reviewed; 115 without MCS and 136 with MCS. The patients were divided to five groups: Group 1 (no MCS): n=115; Group 2 (IABP): n=15; Group 3 (ECMO): n=33; Group 4 (ECMO-VAD): double-bridge (n=59); Group 5 (VAD): n=29. Survival analysis demonstrated that the 3-year post-transplant survival rates were significantly different among the groups (Log-rank p < 0.001). There was no difference in survival between group 4(ECMO-VAD) and group 1(no MCS)1 (p = 0.136), or between group 4(ECMO-VAD) and group 5(VAD) (p = 0.994). Group 3(ECMO) had significantly inferior 3-year survival than group 4(ECMO-VAD) and group 5(VAD). CONCLUSION: Double bridge may not lead to worse mid-term results in patients who could receive a transplantation. Initial stabilization with ECMO for critical patients before implantation of VAD might be considered as a strategy for obtaining an optimal post-transplant outcome.
ARTICLE | doi:10.20944/preprints202109.0056.v1
Subject: Engineering, Biomedical & Chemical Engineering Keywords: Aptamer; Fluorescence Resonance Energy Transfer; Heavy Metal Ions; Graphene Oxide; Microfluidic Device; Sensor.
Online: 3 September 2021 (10:29:50 CEST)
Heavy metal contaminants have serious consequences for the environment and human health. Consequently, effective methods for detecting their presence, particularly in water and food, are urgently required. Accordingly, the present study proposes a sensor for the detection of mercury Hg(II) and lead Pb(II) ions using graphene oxide (GO) as a quenching agent and aptamer solu-tion as a reagent. In the proposed device, the aptamer sequences are labeled by FAM and HEX fluorescent dyes, respectively, and are mixed with 500 ppm GO solution in a microfluidic device. The presence of Hg(II) and Pb(II) ions is then detected by measuring the change in the fluores-cence intensity of the GO/aptamer suspension as the aptamer molecules undergo fluorescence resonance energy transfer (FRET). The experimental results show that the aptamer sensors have a linear range of 10~250 nM (i.e., 2.0~50 ppb) for Hg(II) ions and 10~100 nM (i.e., 2.1~20.7 ppb) for Pb(II) ions. Furthermore, the limit of detection is around 2 ppb for both metals, which is signifi-cantly lower than the maximum limits of 6 ppb and 10 ppb prescribed by the World Health Or-ganization (WHO) for Hg(II) and Pb(II) in drinking water, respectively.
ARTICLE | doi:10.20944/preprints202103.0616.v1
Subject: Engineering, Automotive Engineering Keywords: gait diagnosis; wearable device; graphical descriptor; real-time monitoring; tele-rehabilitation; digital biomarkers
Online: 25 March 2021 (13:52:03 CET)
The deterioration of gait can be used as a biomarker for ageing and neurological diseases. Continuous gait monitoring and analysis are essential for early deficit detection and personalized rehabilitation. The use of mobile and wearable inertial sensor systems for gait monitoring and analysis have been well explored with promising results in the literature. However, most of these studies focus on the technologies for gait characteristic assessment, few of them have considered the data acquisition bandwidth of the sensing system. Inadequate sampling frequency will sacrifice signal fidelity, thus leading to an inaccurate estimation especially for spatial gait parameters. In this work, we developed an inertial sensor based in-shoe gait analysis system for real-time gait monitoring and investigated the optimal sampling frequency to capture all the information on walking patterns. An exploratory validation study was performed using an optical motion capture system on four healthy adult subjects, where each person underwent five walking sessions, giving a total of 20 sessions. Percentage mean absolute errors (MAE%) obtained in stride time, stride length, stride velocity, and cadence while walking were 1.19%, 1.68%, 2.08%, and 1.23%, respectively. In addition, an eigen-analysis based graphical descriptor from raw gait cycle signals was proposed as a new gait metric that can be quantified by principal component analysis to differentiate gait patterns, which has great potential to be used as a powerful analytical tool for gait disorder diagnostics.
ARTICLE | doi:10.20944/preprints202103.0283.v1
Subject: Social Sciences, Accounting Keywords: Cloud Manufacturing(CMfg); 3D Printing Device Resources; HPSO; Muti-objective Optimization; Baldwin effect
Online: 10 March 2021 (13:20:59 CET)
Focusing on service control factors, rapid changes in manufacturing environments, the difficulty of resource allocation evaluation, resource optimization for 3D printing services (3DPSs) in cloud manufacturing environments and so on, an indicator evaluation framework is proposed for the cloud 3D printing (C3DP) order task execution process based on a Pareto optimal set algorithm that is optimized and evaluated for remotely distributed 3D printing equipment resources. Combined with the multi-objective method of data normalization, an optimization model for C3DP order execution based on the Pareto optimal set algorithm is constructed with these agents' dynamic autonomy and distributed processing. This model can perform functions such as automatic matching and optimization of candidate services, and it is dynamic and reliable in the C3DP order task execution process based on the Pareto optimal set algorithm. Finally, a case study is designed to test the applicability and effectiveness of the C3DP order task execution process based on the analytic hierarchy process and technique for order of preference by similarity to ideal solution (AHP-TOPSIS) optimal set algorithm and the Baldwin effect.
CONCEPT PAPER | doi:10.20944/preprints201612.0105.v5
Subject: Medicine & Pharmacology, Clinical Neurology Keywords: csf; shunt; filtration; neurodegenerative; neuroimmunology; alzheimer; parkinson; guillain-barre; device; ventriculo-peritoneal shunt
Online: 30 January 2017 (14:22:03 CET)
Liquorpheresis (CSF filtration) comprises a therapeutical approach that has been proposed to treat several neurological conditions where antibodies, inflammatory mediators or abnormal peptides are the cause or play an important role in the pathogenesis of the disease. CSF replacement may be an alternative approach not explored so far. Here, we review previous experiences in the use of liquorpheresis in autoimmune and degenerative neurological diseases. Then we describe previous developments and provide some new technical innovations in order to design bidirectional CSF shunting systems. These systems can be complemented either with a deposit of artificial CSF or with a CSF filter, allowing CSF replacement or liquorpheresis respectively. Both options would lead to mechanical dilution of the patient’s CSF.
ARTICLE | doi:10.20944/preprints202211.0504.v1
Subject: Engineering, Other Keywords: low-cost sensors; portable device; environmental monitoring; gas concentrations; dairy barn; photoacoustic infrared spectroscope
Online: 28 November 2022 (08:28:49 CET)
The increasing regulatory pressure to monitor and reduce GHG emissions and air pollutants requires cost-effective methods for their surveillance. The most common technique used for scientific investigations on gas concentration monitoring in barns are accurate but expensive and with a complex maintenance. This research study analysed the potential use of a low-cost portable measurement devices for the measurement of ammonia (NH3) and carbon dioxide (CO2) concentrations in an open dairy barn. A comparison between gas concentrations acquired at different heights from the floor by using portable devices and those acquired by a photoacoustic infrared multigas spectroscope (i.e., reference measurement) in the same sampling locations was carried out to determine the precision of the low-cost portable devices. The performance of low-cost portable devices was statistically analysed by the application of the one-way analysis of variance, correlation analysis and regression analysis. The results showed a significant difference between gas concentration values at various heights from the floor for both NH3 and CO2. The correlations between concentrations acquired by the low-cost portable device and the INNOVA were statistically significant (r=0.83; P<0.001) for gas concentrations monitored at 0.4 m from the floor. Compared with the reference measurement device, the low-cost devices were effective in the monitoring of NH3 concentrations at 0.40 m from the floor though it underestimated them in the barn at increasing of the height from the floor, whereas the device was not adequate for CO2 concentrations. In detail, the relative measurement error of the low-cost devices compared to INNOVA was reduced close to the floor during NH3 concentration measurements. Within these limitations, this device could be useful for monitoring NH3 concentration in the barn and to assess variation in NH3 concentrations mainly related to the animal occupied zone. Further efforts are needed in this field of research to identify low-cost device that could simplify emission estimation from open dairy barns.
ARTICLE | doi:10.20944/preprints202112.0489.v1
Subject: Behavioral Sciences, Applied Psychology Keywords: sleep; academic performance; grade point average; college students; wearable device; longitudinal; nighttime sleep awakening
Online: 30 December 2021 (13:45:37 CET)
Although the relations between sleep and academic performance have been extensively examined, how sleep predicts future academic performance (e.g., 2 -3 years) remains to be further investigated. Using wearable smartwatches and a self-report questionnaire, we tracked sleep activities of 45 college students over a period of approximate half a month to see whether their sleep activities predicted their academic performance, which was estimated by grade point average (GPA). Results showed that both nighttime sleep awakening frequency and its consistency in the tracking period were not significantly correlated with the GPA for the courses taken in the semester during sleep tracking (current GPA). However, both nighttime sleep awakening frequency and its consistency inversely predicted the GPA for the rest of the courses taken after that semester (future GPA). Moreover, students with more difficulty staying awake throughout the day obtained lower current and future GPAs, and students with lower inconsistency of sleep quality obtained lower future GPA. Together, these findings highlight the importance of nighttime sleep awakening frequency and consistency in predicting future academic performance and emphasize the necessity of assessing the consistency of sleep measures in future studies.
ARTICLE | doi:10.20944/preprints202104.0502.v1
Subject: Engineering, Automotive Engineering Keywords: breathalyzer; wearable; sensors; breath analysis device; health; mobile screen; alcohol; ethanol; smartphone; multimedia screen
Online: 19 April 2021 (15:11:03 CEST)
One third of fatal car accidents and so much tragedies are due to alcohol abuse. These sad numbers could be mitigated if everyone had access to a breathalyzer anytime and anywhere. Having a breathalyzer built into a phone or a wearable could be the way to get around the reluctance to carry a separate device. Towards this goal, we propose an inexpensive breathalyzer that could be integrated in the screen of mobile devices. Our technology is based on the evaporation rate of the fog produced by the breath on the phone screen, which increases as a function of the breath alcohol content. The device simply uses a photodiode placed on the side of the screen to measure the signature of the scattered light intensity from the phone display that is guided through the stress layer of the Gorilla glass screen. A part of the display light is coupled to the stress layer via the evanescent field induced at the edge of the breath microdroplets. We demonstrate that the intensity signature measured at the detector can be linked to the blood alcohol content. We fabricated a prototype in a smartphone case powered by the phone’s battery, controlled by an application software installed in the smartphone and tested it in real-world environments. Limitations and future work toward a fully operational device are discussed.
ARTICLE | doi:10.20944/preprints202011.0027.v1
Subject: Chemistry, Analytical Chemistry Keywords: Brugada syndrome; peptide nucleic acid-PNA, porous silicon; graphene oxide; optical biosensor; hybrid device
Online: 2 November 2020 (11:12:24 CET)
Peptide nucleic acid (PNA) is a synthetic DNA mimic that outperforms the properties of traditional oligonucleotides (ONs). On account of its outstanding features, such as remarkable binding affinity towards complementary DNA or RNA as well as high thermal and chemical stability, PNA has been proposed as a valuable alternative to the ON probe in gene-sensor design. In this study, a hybrid transducer made-up of graphene oxide (GO) nano-sheets covalently grafted onto a porous silicon (PSi) matrix has been investigated for the early detection of a genetic cardiac disorder, the Brugada syndrome (BS). A functionalization strategy towards the realization of a potential PNA-based device is described. A peptide nucleic acid (PNA), able to detect the SCN5A associated with the BS has been properly synthesized and used as a bioprobe for the realization of a proof-of-concept label-free optical PNA-biosensor. PSi reflectance and GO photoluminescence (PL) signals were simultaneously exploited for the monitoring of the device functionalization and response.
ARTICLE | doi:10.20944/preprints202004.0227.v3
Subject: Medicine & Pharmacology, Cardiology Keywords: global myocardial injury; BMSCs; active cardiac support device (ASD); stem cell treatment; epicardial delivery
Online: 7 September 2020 (07:30:47 CEST)
Bone marrow-derived mesenchymal stem cells (BMSCs) have been considered a promising therapeutic approach to cardiovascular disease. This study intends to compare the effect of BMSCs through a standard active cardiac support device (ASD) and intravenous injection on global myocardial injury induced by isoproterenol. BMSCs were cultured in vitro, and the transplanted cells were labeled with a fluorescent dye CM-Dil. Isoproterenol (ISO) was injected into the rats; two weeks later, the labeled cells were transplanted into ISO-induced heart-injury rats through the tail vein or ASD device for five days. The rats were sacrificed on the first day, the third day, and the fifth day after transplantation to observe the distribution of cells in the myocardium by fluorescence microscopy. The hemodynamic indexes of the left ventricle were measured before sacrificing. H&E staining and Masson’s trichrome staining were used to evaluate the cardiac histopathology. In the ASD groups, after three days of transplantation, there were many BMSCs on the epicardial surface, and after five days of transplantation, BMSCs were widely distributed in the ventricular muscle. But in the intravenous injection group, there were no labeled-BMSCs distributed. In the ASD+BMSCs-three days treated group and ASD+BMSCs -five days-treated group, left ventricular systolic pressure (LVSP), the maximum rate of left ventricular pressure rise (+dP/dt), the maximum rate of left ventricular pressure decline (-dP/dt) increased compared with model group and intravenous injection group (P<0.05). By giving BMSCs through ASD device, cells can rapidly and widely distribute in the myocardium and significantly improve heart function.
ARTICLE | doi:10.20944/preprints202006.0322.v1
Subject: Engineering, Energy & Fuel Technology Keywords: high power illumination; compact device; solar thermal simulator; light uniformity; low cost LED system
Online: 28 June 2020 (08:48:00 CEST)
Uniform illumination is a key requirement in different research fields. However, this requirement is often difficult to achieve when high intensity is required at the same time. Recent advancements in LED lamps allow nowadays for compact and economical solutions. In this work we present a suitable solution for various laboratory purposes requiring stable, uniform and high intensity illumination. The system is composed of four identical high power white LED arrays of 30 mm diameter each, placed on a supporting and cooling structure having a minimum volume of 26 cm x 26 cm x 8 cm. A numerical model has been developed, based on a ray tracing software, in order to simulate the performances. These have then been experimentally validated with measurements of the power density map, carried out with a 1% uncertainty pyranometer. Data show that the built system is very stable over time and provides an illumination uniformity higher than 98%, on a surface of 50 mm radius, which reduces to 95% on a surface of 75 mm radius. The power density can be adjusted in the 390-1360 W m-2 range, not affecting uniformity.
ARTICLE | doi:10.20944/preprints202209.0068.v1
Subject: Mathematics & Computer Science, Analysis Keywords: wearable device; physical activity; behavior; COVID-19; pandemic; exercise habits; analysis; objectively-measured physical activity
Online: 5 September 2022 (13:49:56 CEST)
The COVID-19 pandemic resulted in government restrictions that altered the lifestyle of people worldwide. Studying the impact of these restrictions on exercise behaviors will improve our understanding of environmental factors that influence individuals’ PA. We conducted a retrospective analysis using an index of government pandemic stringency developed by Oxford and a wearable device for runners to compare strictness of lockdowns and exercise habits, using digitally-logged PA data from more than 7,000 runners on a global scale. Additionally, time-of-day of PA globally and levels of PA in 14 countries are compared between the pre-pandemic year of 2019 and the first pandemic year of 2020. We found that during the pandemic the time-of-day that people exercised experienced a major shift, with significantly more activities logged during standard working hours on workdays (p<0.001) and fewer during the same time frame on weekends (p<0.001). Of the countries examined, Italy and Spain had among the most strict lockdowns and suffered the largest decreases in activity counts, whereas France experienced a minimal decrease in activity counts despite enacting a similarly strict lockdown. This study suggests that there are several factors affecting PA, including government policy, workplace policy, and cultural norms.
ARTICLE | doi:10.20944/preprints201907.0272.v1
Subject: Engineering, Electrical & Electronic Engineering Keywords: ambient human energy, piezoelectric energy harvester, RC circuit model, self-powered device, wireless PPG sensor
Online: 24 July 2019 (11:50:43 CEST)
A new circuit model of the self-powered device for heart rate measurement is presented in this paper. This device consists of piezoelectric energy harvester (PEH), power management circuit (PMC) with energy storage, microcontroller, Photoplethysmography (PPG) sensor, and Wi-Fi module. The PEH is placed under the insole to harvest the pressure energy from human foot-step to generate ac power. In our model, a PEH is represented by sine voltage source, where its parameters were taken from experiments with 20 volunteers. The PMC is simplified by a switch with gain δ placed in series with the main circuit. The model of the main circuit is RC elements in parallel, where C is the capacitance of the storage device, and R is the equivalent parallel resistance of the microcontroller, PPG sensor, and Wi-Fi modules, respectively. The value of R depends on the power and current absorbed by those modules during sleep, deep sleep, sense, and transmit modes which collected from the datasheet. Finally, the proposed circuit model of the self-powered device was built and simulated in SPICE. The simulation results were compared with the laboratory experiment using commercial devices. Based on the results, the proposed model had small gaps compared to the real self-powered devices in terms of average current, voltage, power and efficiency.
ARTICLE | doi:10.20944/preprints201812.0284.v1
Subject: Engineering, Industrial & Manufacturing Engineering Keywords: Reverse Engineering, RealSense D415, depth camera, device characterization, VDI/VDE normative, active stereo, performance comparison
Online: 24 December 2018 (15:11:39 CET)
Low-cost RGB-D cameras are increasingly used in several research fields including human-machine interaction, safety, robotics, biomedical engineering and even Reverse Engineering applications. Among the plethora of commercial devices, the Intel RealSense cameras proved to be among the best suitable devices, providing a good compromise between cost, ease of use, compactness and precision. Released on the market in January 2018, the new Intel model RealSense D415 has a wide acquisition range (i.e. ~160-10000 mm) and a narrow field of view to capture objects in rapid motion. Given the unexplored potential of this new device, especially when used as a 3D scanner, the present work aims to characterize and to provide metrological considerations on the RealSense D415. In particular, tests are carried out to assess the device performances in the near range (i.e. 100-1000 mm). Characterization is performed by integrating the guidelines of the existing standard (i.e. the German VDI/VDE 2634 part 2 normative) with a number of literature-based strategies. Performance analysis is finally compared against latest close-range sensors, thus providing a useful guidance for researchers and practitioners aiming to use RGB-D cameras in Reverse Engineering applications.
ARTICLE | doi:10.20944/preprints201806.0248.v1
Subject: Medicine & Pharmacology, Ophthalmology Keywords: short tunnel small flap; glaucoma drainage device implantation; tube exposure; STSF; Ahmed glaucoma valve; AGV
Online: 15 June 2018 (09:40:16 CEST)
Purpose: To compare the efficacy and safety of graft-free short tunnel small flap (STSF) technique with that of scleral patch graft (SPG) in Ahmed glaucoma valve (AGV) implantation. Design: Randomized clinical trial. Participants: Eighty-eyes of eighty patients with medically uncontrolled glaucoma including 41 in STSF and 39 eyes in SPG. Methods: Patients were enrolled and assigned randomly to STSF or SPG. Main Outcome Measures: tube exposure, Intraocular pressure (IOP), number of glaucoma medications, best corrected visual acuity (BCVA), surgical complications, and success rate ( defined as intraocular pressure (IOP) >5 mmHg, ≤21 mmHg, and IOP reduction ≥20% from baseline at two consecutive visits after three months, no reoperation for glaucoma). Results: only one case in SPG developed tube exposure at 1-year follow-up. The cumulative probability of success during the first year of follow-up was 70% in the STSF and 65% in SPG (P = 0.36). IOP decreased significantly from 29.6 ± 8.6 mmHg at baseline to 16.4 ± 3.6 mmHg at the final follow-up in STSF (p = 0.001). The corresponding numbers for SPG were 30.9 ± 11.2 and 15.8 ± 4.7, respectively (p = 0.001). The final IOP was comparable between both groups (p = 0.65). Mean ± standard deviation of the number of glaucoma medications was 1.8 ± 0.9 in STSF and 1.6 ± 0.9 in SPG at final follow-up (P = 0.32). Postoperative complications developed in 8 patients (19%) in STSF and 9 patients (23%) in SPG (P = 0.81). Conclusions: STSF and SPG techniques had comparable complication rate at one-year follow-up. Both techniques were comparable in terms of success rate, postoperative IOP, and glaucoma medications.
ARTICLE | doi:10.20944/preprints201702.0102.v1
Subject: Engineering, Energy & Fuel Technology Keywords: Marine Energy; Tidal turbine; horizontal-axis marine current turbine; OCT; Turbulence; Support Structure; device wake
Online: 28 February 2017 (11:55:00 CET)
Tidal stream energy is a low carbon energy source. Tidal stream turbines operate in a turbulent environment, and the effect of the structure between the turbine and seabed on this environment is not fully understood. An experimental study using 1:72 scale models based on a commercial turbine design was carried out to study the support structure influence on turbulence intensity around turbine blades. The study was conducted using the wave-current tank at LABIMA, University of Florence. A realistic flow environment (ambient turbulent intensity = 11%) was established. Turbulence intensity was measured upstream and downstream of a turbine mounted on two different support structures (one resembling a commercial design, the other the same with an additional vertical element), in order to quantify any variation in turbulence and performance between the support structures. Turbine drive power was used to calculate power generation. Acoustic Doppler Velocimetry was used to record and calculate upstream and downstream turbulence intensity. In otherwise identical conditions, performance variation of only 4% was observed between two support structures. Turbulent intensity at 1, 3 and 5 blade diameters, both upstream and downstream, showed variation up to 21% between the two cases. The additional turbulent structures generated by the additional element of the second support structure appears to cause this effect, and the upstream propagation of turbulent intensity is believed to be permitted by surface waves. This result is significant for the prediction of turbine array performance.
ARTICLE | doi:10.20944/preprints202201.0403.v2
Subject: Chemistry, Analytical Chemistry Keywords: lead biosensors; FRET; portable Pb sensor; smartphone-based device; Met-lead; tap water lead; groundwater lead
Online: 23 February 2022 (10:53:14 CET)
Most methods for measuring environmental lead (Pb) content are time consuming, expensive, hazardous, and restricted to specific analytical systems. To provide a facile, safe tool to detect Pb, we created pMet-lead, a portable fluorescence resonance energy transfer (FRET)-based Pb biosensor. pMet-lead comprises a 3D-printed frame housing a 405-nm laser diode — an excitation source for fluorescence emission images (YFP and CFP) — accompanied by optical filters, a customized sample holder with a Met-lead 1.44 M1 (the most recent version)-embedded biochip, and an optical lens aligned for smartphone compatibility. Measuring the emission ratios (Y/C) of the FRET component enables Pb detection with a dynamic range of nearly 2 (1.96), pMet-lead/Pb dissociation constant (Kd) 45.62 nM, and limit of detection 40 nM (0.832 μg/dL, 8.32 ppb). To mitigate earlier problems with lack of selectivity for Pb vs. zinc, we preincubated samples with tricine, a low-affinity zinc chelator. We validated pMet-lead measurements of characterized laboratory samples and unknown samples from six regions in Taiwan by inductively coupled plasma mass spectrometry (ICP-MS). Notably, two unknowns had Y/C ratios significantly higher than that of the control (3.48 ± 0.08 and 3.74 ± 0.12 vs. 2.79 ± 0.02), along with Pb concentrations (10.6 ppb and 15.24 ppb) above the WHO-permitted level of 10 ppb in tap water, while the rest four unknowns showing no detectable Pb upon ICP-MS. These results demonstrate that pMet-lead provides a rapid, sensitive means for on-site Pb detection in water from the environment and in living/drinking supply systems to prevent potential Pb poisoning.
ARTICLE | doi:10.20944/preprints202109.0424.v1
Subject: Engineering, Biomedical & Chemical Engineering Keywords: high frequency dielectrophoresis; glioblastoma cells; single cell manipulation; microfluidic point-of-care device; cancer stem cells
Online: 24 September 2021 (11:11:35 CEST)
Glioblastoma (GBM) is one of the most aggressive solid tumors, particularly due to the presence of cancer stem cells (CSCs). Today the characterization of this type of cells with an efficient, fast and low-cost method remains an issue. Hence, we have developed a microfluidic lab-on-a-chip based on dielectrophoresis (DEP) single cell electro-manipulation to measure the two crossover frequencies: fx01 in low frequency range (below 500 kHz) and fx02 in Ultra High Frequency range (UHF, above 50 MHz). First, in vitro conditions were investigated. U87-MG cell lines were cultured in different conditions in order to induce an undifferentiated phenotype. Then, ex vivo GBM cells from patients’ primary cell culture, were passed through the developed microfluidic system and characterized in order to reflect clinical conditions. This article demonstrates that the usual exploitation of low frequency range DEP does not allow the discrimination of the undifferentiated from the differentiated phenotypes of GBM cells. However, the presented study highlights the use of UHF-DEP as a relevant discriminant parameter. The proposed microfluidic lab-on-a-chip is able to follow the kinetic of U87-MG phenotype transformation in a CSC enrichment medium and their cancer stem cells phenotype acquirement.
ARTICLE | doi:10.20944/preprints202009.0495.v2
Subject: Mathematics & Computer Science, Information Technology & Data Management Keywords: agency; smart devices; IoT; device agency; user agency; human computer interaction; HCI; questionnaire; exploratory analysis; anova
Online: 22 September 2020 (03:45:51 CEST)
In this paper, we investigate the relationship people have with their smart devices. We use the concept of agency to capture aspects of users’ sense of mastery as they relate to their device. This study gives preliminary evidence of the existence of two independent dimensions of agency for modeling the interaction between humans and smart devices: (i) user agency and (ii) device agency. These constructs emerged from an exploratory factorial analysis conducted on a survey data collected from 587 participants. In addition, we investigate the correlation between user agency and device agency with background variables of the respondents. Finally, we argue that mapping the users’ dynamics with their device into user agency and device agency fosters a better understanding of the needs of the users and helps in designing interfaces tailored for the specific capabilities and expectations of the users.
ARTICLE | doi:10.20944/preprints201906.0069.v1
Subject: Engineering, Other Keywords: winglets; lift-induced drag; wing tip device; non-planar lifting surface; performance optimization; aircraft performance; regional aircraft
Online: 9 June 2019 (03:48:26 CEST)
An increasing number of aircraft is equipped with wing tip devices, which either are installed by the aircraft manufacturer at the production line or are retrofitted after the delivery of the aircraft to its operator. Installation of wing tip devices has not been a popular choice for regional turboprop aircraft and the novelty of the current study is to investigate the feasibility of retrofitting the British Aerospace (BAe) Jetstream 31 with an appropriate wing tip device (or winglet) to increase its cruise range performance, taking also into account the aerodynamic and structural impact of the implementation. To the best of the knowledge of the authors, no previous study exists which has attempted to assess the winglet retrofit of an existing aircraft type of similar size and operating profile. The optimal winglet design achieved a 2.38% increase of the maximum range by reducing the total drag by 1.19% at a mass penalty of 3.25%, as compared with the baseline aircraft configuration. Other designs were found to be more effective in reducing the total drag, but the structural reinforcement required for their implementation outweighed the achieved performance improvements. Since successful winglet retrofit programs for typical short to medium range narrow body aircraft report even more than 3% of block fuel improvements, undertaking the project of installing an optimal winglet design to the BAe Jetstream 31, should also consider a Direct Operating Cost (DOC) assessment on top of the aerodynamic and structural aspects of the retrofit.
ARTICLE | doi:10.20944/preprints202110.0238.v1
Subject: Engineering, Biomedical & Chemical Engineering Keywords: Median sternotomy; Ossification; Cardiac surgery; Rehabilitation; Functional mobility; Bone fracture; Assistive device; Feedback training; Sternal precautions; Instrumented walker
Online: 18 October 2021 (10:43:01 CEST)
Patients recovering from bone disruption due to trauma or surgery need to limit movement to minimize shear force, thereby protecting callus formation and osteogenesis. Patients often use their arms to assist with functional activities, but pushing is frequently limited to <10 lb (4.5 kg). With only verbal instructions, patients’ ability to accurately limit weight-bearing (WB) force is poor. A therapeutic intervention to improve patient adherence with upper extremity (UE) WB guidelines during functional mobility using an instrumented walker could be beneficial. Therefore, the purpose of this article is to describe a feedback training protocol to improve the ability to modulate weight-bearing force in older adults and then provide an overview of the efficacy of this protocol and subsequent development of a Clinical Force Measuring Walker. An instrumented walker was used to measure UE WB during functional mobility in older healthy subjects (n = 30) before, during, and after (immediately and 2 hours) a visual and auditory concurrent feedback training session. During feedback training, force was significantly reduced with all 3 sessions as compared to baseline. When using the front wheeled walker, UE WB force during the second and third feedback training trials went down compared to the first trial. During the third feedback training trial, force was greater than the two previous trials while transferring sit-to-stand and stand-to-sit. After completion of practice with feedback, UE WB force was significantly reduced and remained so 2 hours later. These findings suggest that feedback training is effective for helping patients to modulate UE WB. Use of an instrumented walker and feedback training would be beneficial in clinical practice, especially with older patients. A more intensive feedback training with additional trials and or simultaneous visual and auditory cues during whole-practice may be needed to get UE WB below a 10 lb threshold.
ARTICLE | doi:10.20944/preprints201807.0179.v1
Subject: Materials Science, Surfaces, Coatings & Films Keywords: acetylated nanofibrillated cellulose; acrylic resins ABPE-10; composite films; flexible organic light-emitting device substrate; interpenetrating polymer network
Online: 10 July 2018 (12:38:16 CEST)
The ANFC/ABPE-10 composite film was prepared by ABPE-10 impregnating into ANFC films under negative pressure. And the composite film had meted high performance FOLED substrate requirement even when ANFC dosage was high for approximately 70%, which was consistent with for low cost efficiency, recyclability, and environmentally friendly. The enhanced properties of ANFC films were mainly because of the nature of ABPE-10 itself and the IPN structure formed between ABPE-10 and ANFC film. The transparency of composite films with different ANFC dosage was significantly increased from 67% to 88% by UV-Vis analysis. The composite film inherited the properties of AFNC, obtaining low CTE characteristics and ductile compact structure. The contact angles of ANFC films increased by 102% from 49.2° to 102.9°after dipping ABPE-10. Additionally, the composite films had outstanding mechanical properties such as tensile strength 173.72 MPa, Young’s modulus 4.06 GPa, and elongation at break 5.81%.
ARTICLE | doi:10.20944/preprints201703.0185.v1
Subject: Engineering, Mechanical Engineering Keywords: MEMS S&A device; threshold-value judging mechanism; fabrication process; tensile test; theoretical, simulationand experimentalanalysis; parametric design method
Online: 24 March 2017 (10:12:13 CET)
In order to meet the military requirements of the fuze, such as precision strike, efficient mutilates ability and low collateral damages, the microminiaturization is an inevitable trend of secure system. Based on the silicon-based MEMS S&A device designed by our term, the design principles of each module and fabrication process are introduced. The average fracture strength and Young's modulus of the silicon are 726 MPa and 175 GPa from the tensile test, respectively. From Hopkinson impact experiment, we can get the threshold-value judging mechanism being safety under the impact overload of 20526 g, and this value is much more than the standard of the drop overload 12000g; the arming value under the centrifugal overload obtained from theory, simulation and experiment is at the range of 28200 g and 32000 g, it shows that the threshold-value judging mechanism can be arming compared with the value 35951g of design principle. Therefore, the threshold-value judging mechanism can meet the design requirements of overload. Furthermore, the relationship of fracture threshold-values obtained by different theories is found out through parametric design method, as shown in Figure 14, it provides the theory evidence to the follow parametric design.
ARTICLE | doi:10.20944/preprints201611.0111.v1
Subject: Engineering, Biomedical & Chemical Engineering Keywords: Y-shaped microfluidic device; wall shear stress; adenosine triphosphate (ATP) signal; combined effect; vascular endothelial cells; calcium dynamics
Online: 22 November 2016 (09:51:31 CET)
The intracellular calcium dynamics in vascular endothelial cells (VECs) in response to wall shear stress (WSS) and/or adenosine triphosphate (ATP) have been commonly regarded as an important factor in regulating VEC function and behavior including proliferation, migration and apoptosis. However, the effects of time-varying ATP signals have been usually neglected in the past investigations in the field of VEC mechanobiology. In order to investigate the combined effects of WSS and dynamic ATP signals on the intracellular calcium dynamic in VECs, a Y-shaped microfluidic device, which can provide the cultured cells on the bottom of its mixing micro-channel with stimuli of WSS signal alone and different combinations of WSS and ATP signals in one single micro-channel, is proposed. Both numerical simulation and experimental studies verify the feasibility of its application. Cellular experimental results also suggest that a combination of WSS and ATP signals rather than a WSS signal alone might play a more significant role in VEC Ca2+ signal transduction induced by blood flow.
ARTICLE | doi:10.20944/preprints202102.0382.v1
Subject: Engineering, Automotive Engineering Keywords: cultural heritage; masonry rehabilitation; seismic device; steel structure; basalt fiber; grout injections; archeological site; rubber-bearing; non-destructive testing
Online: 17 February 2021 (11:41:33 CET)
The preservation of the authenticity of a building artefact is a responsible practice. On the other side, the need to save the building artefact from the natural and anthropic degradation, to ensure the structural reliability to the different actions, to define an efficient maintenance program are big challenges, that involves the cooperation of several professionals, responsible use of innovative techniques and materials that are nowadays available. This paper focuses on a specific design approach for the rehabilitation works of ancient constructions in archaeological sites. The proposed conceptual design approach implies different steps that allow the optimization of the design at an increasing level of knowledge on the existing structures and their materials. The design procedure on historical constructions generally includes the following steps: the collection of data, the structural identification, hazard, and vulnerability analysis, damage and risk analysis, a cost-benefit analysis, so only at the end of the process, the final design is achieved. In the archaeological area, some important design aspects cannot be defined before the execution work phase, since some elements could be revealed and identified during work execution, as a consequence, the final design has been often optimized after all this information has been acquired. A studied case in the archaeological site of Pompeii is herein presented to prove the efficiency of the proposed approach.
ARTICLE | doi:10.20944/preprints202211.0498.v1
Subject: Medicine & Pharmacology, Pathology & Pathobiology Keywords: Virus-Like Particle (VLP); SARS-CoV-2; in vitro diagnostic device (IVD); Enzyme-linked Immunosorbent Assay (ELISA); Immune reaction; Antibodies
Online: 28 November 2022 (07:06:50 CET)
A key in controlling the SARS-CoV-2 pandemic is the assessment of the immune status of the population. We explored the utility of SARS-CoV-2 virus-like particles (VLPs) as antigens to detect specific humoral immune reactions in an enzyme-linked immunosorbent assay (ELISA). For this purpose, SARS-CoV-2 VLPs were produced from an engineered cell line and characterized by western blot, ELISA and nanoparticle tracking analysis. Subsequently, we collected 42 serum samples from before the pandemic (2014), 89 samples from healthy-, and 38 samples from vaccinated subjects. Seventeen samples were collected less than three weeks after infection, and 44 samples more than three weeks after infection. All serum samples were characterized for their reactivity with VLPs and the SARS-CoV-2 N- and S-protein. Finally, we compared the performance of the VLP-based ELISA with a certified in vitro diagnostic device (IVD). In the applied set of samples, we determined a sensitivity of 95.5 % and a specificity of 100 % for the certified IVD. There were 7 samples with an uncertain outcome. Our VLP-ELISA showed superior performance with a sensitivity of 97.5 %, a specificity of 100 %, and only 3 uncertain outcomes. This result warrants further research to develop a certified IVD based on SARS-CoV-2 VLPs as an antigen.
ARTICLE | doi:10.20944/preprints202104.0744.v1
Subject: Engineering, Electrical & Electronic Engineering Keywords: Aerosols; dental clinics; infection control; high-volume evacuation; extra-oral suction device; particle concentration; sensor network; dispersion modeling; exposure assessment; air quality
Online: 28 April 2021 (10:32:57 CEST)
Human exposure to infectious aerosols results a transmission of diseases, such as influenza, tuberculosis, and COVID-19. Most dental procedures generate a significant number of aerosolized particles, increasing transmission risk in dental settings. Since the generation of aerosols in dentistry is unavoidable, many clinics started using intervention strategies such as area-filtration units and extraoral evacuation equipment, especially under the relatively recent constraints of the pandemics. However, the effectiveness of these devices in dental operatories has not been studied. Therefore, the dental personnel's ability to position and operate such instruments efficiently is also limited. To address these challenges, we utilized a real-time sensor network for assessment of aerosol dynamics during dental restoration and cleaning producers with and without intervention. The strategies tested during the procedures were (i) local area high-efficiency particle air (HEPA) filters and (ii) extra-oral suction device (EOSD). The study was conducted at the University of Washington School of Dentistry using a network of thirteen fixed sensors positioned within the operatory and one wearable sensor worn by the dental operator. The sensor network provides time and space-resolved particulate matter (PM) data. Three-dimensional (3D) visualization informs aerosol persistence in the operatory. It was found that area filters did not improve the overall aerosol concentration in dental offices significantly. An average of 16% decrease in PM concentration was observed when EOSD equipment was used during the procedures. The combination of real-time sensors and 3D visualization can provide dental personnel and facility mangers with actionable feedback to effectively assess aerosol transmission in medical settings and develop evidence-based intervention strategies.
Subject: Behavioral Sciences, Applied Psychology Keywords: multimodal experiment; multisensory experiment; automatic device integration; open-source; PsychoPy; Unity; Virtual Reality (VR); Lab Streaming Layer; LabRecorder; LabRecorderCLI; Windows command line (cmd.exe)
Online: 12 October 2020 (07:06:28 CEST)
The human mind is multimodal. Yet most behavioral studies rely on century-old measures of behavior—task accuracy and latency (response time). Multimodal and multisensory analysis of human behavior creates a better understanding of how the mind works. The problem is that designing and implementing these experiments is technically complex and costly. This paper introduces versatile and economical means of developing multimodal-multisensory human experiments. We provide an experimental design framework that automatically integrates and synchronizes measures including electroencephalogram (EEG), galvanic skin response (GSR), eye-tracking, virtual reality (VR), body movement, mouse/cursor motion and response time. Unlike proprietary systems (e.g., iMotions), our system is free and open-source; it integrates PsychoPy, Unity and Lab Streaming Layer (LSL). The system embeds LSL inside PsychoPy/Unity for the synchronization of multiple sensory signals—gaze motion, electroencephalogram (EEG), galvanic skin response (GSR), mouse/cursor movement, and body motion—with low-cost consumer-grade devices in a simple behavioral task designed by PsychoPy and a virtual reality environment designed by Unity. This tutorial shows a step-by-step process by which a complex multimodal-multisensory experiment can be designed and implemented in a few hours. When conducting the experiment, all of the data synchronization and recoding of the data to disk will be done automatically.
ARTICLE | doi:10.20944/preprints202010.0043.v1
Subject: Mathematics & Computer Science, Algebra & Number Theory Keywords: digital device; finite state machine with datapath; algorithm state machine with datapath; field programmable gate array; design technique; development time; reliability; area; performance
Online: 2 October 2020 (13:54:34 CEST)
Recently, there has been, on the one hand, an increase in the complexity of digital device designs and, on the other hand, an increase in the requirements for the development time and the reliability of the designs. One of the directions of solving this problem is developing new techniques for designing digital devices.This paper proposes a new technique for designing digital devices based on finite state machines with datapath (FSMD), when the functioning of the device is described in the form of an algorithm state machine with datapath (ASMD) charts. The new technique is called ASMD-FSMD. Different digital device design techniques are compared to each other using design examples of a synchronous multiplier on field programmable gate array (FPGA). The efficiency of the ASMD-FSMD technique compared to the traditional approach in terms of area and performance was investigated. The ASMD-FSMD technique, compared to the traditional one, reduces the area from 28.6% to 39.7% and increases the speed for some designs to 17.6%. In addition, using the ASMD-FSMD technique significantly reduces design time and increases design reliability. In conclusion, recommendations for using the ASMD-FSMD technique are made.
ARTICLE | doi:10.20944/preprints202102.0586.v1
Subject: Engineering, Control & Systems Engineering Keywords: nonlinear spectrum distortions; signal exposition time; fiber Bragg grating; fiber Bragg sensors; fiber optic sensors; fiber optic interrogator; optical spectrum analyzer; charge-coupled device elements; CCD
Online: 25 February 2021 (13:50:46 CET)
Abstract: Nonlinear spectrum distortions are caused by the peculiarities of the operation of charge-coupled device elements (CCD), in which the signal exposition time (TINT) is one of the significant parameters. A change of TINT on a CCD leads to a nonlinear distortion of the resulting spectrum. Nonlinear distortion of the spectrum, in its turn, leads to errors in determining the central wavelength of Fiber Bragg Gratings (FBG) and spectrally sensitive sensors, which, in general, negatively affects the accuracy of measuring systems. The paper proposes an algorithm for correcting nonlinear distortions of the spectrum obtained on a spectrum analyzer using CCD as a receiver. It is shown that preliminary calibration of the optical spectrum analyzer with subsequent mathematical processing of the signal makes it possible to make corrections in the resulting spectrum, thereby leveling the errors caused by measurements at different TINT.
REVIEW | doi:10.20944/preprints201803.0160.v1
Subject: Engineering, Electrical & Electronic Engineering Keywords: Advanced Metering Infrastructure (AMI); Distributed Energy Resources (DER); Distribution Management System (DMS); Graph Reduction In Parallel (GRIP); Intelligent Electronic Device (IED); Intelligent Platform Management Interface (IPMI); Service Oriented Architecture (SOA); Ultra Large Scale System (ULSS)
Online: 19 March 2018 (11:42:42 CET)
Smart grid software interconnects multiple Engineering disciplines (power systems, communication, software and hardware technology, instrumentation, big data, etc.). The software architecture is an evolving concept in smart grid systems in which systematic architecture development is a challenging process. The architecture has to realize the complex legacy power grid systems and cope up with current Information and Communication Technologies (ICT). The distributed generation in smart grid environment expects the software architecture to be distributed and to enable local control. Smart grid architecture should also be modular, flexible and adaptable to technology upgrades. In this paper, the authors have made a comprehensive review on architecture for smart grids. An in depth analysis of layered and agent based architectures is presented and compared under various domains.