ARTICLE | doi:10.20944/preprints202107.0683.v1
Subject: Engineering, Electrical And Electronic Engineering Keywords: micro-actuators; micro-systems; micro-manipulators; levitation; mutual inductance
Online: 30 July 2021 (09:14:36 CEST)
This work presents the results of the experimental and theoretical study of the static pull-in of tilting actuation executed by a hybrid levitation micro-actuator (HLMA) based on the combination of inductive levitation and electrostatic actuation. A semi-analytical model to study such the pull-in phenomenon is developed, for the first time, as a result of using the qualitative technique based on the Lagrangian approach to analyze inductive contactless suspensions presented in work and a recent progress in the calculation of mutual inductance and force between two circular filaments. The obtained non-linear model, accounting for two degrees of freedom of the actuator, allows us to predict accurately the static pull-in displacement and voltage. The results of modelling were verified experimentally and agree well with measurements.
ARTICLE | doi:10.20944/preprints201811.0462.v1
Subject: Engineering, Mechanical Engineering Keywords: micro-fluidics; micro-mixer; entropy generation; micro-turbulence; electrokinetic mixer
Online: 19 November 2018 (11:50:29 CET)
While laminar flow heat transfer and mixing in microfluidic geometries has been investigated experimentally, as has the effect of geometry-induced turbulence in microfluidic flow (it is well documented that turbulence increases convective heat transfer in macrofluidic flow), little literature exists investigating the effect of electrokinetically-induced turbulence on heat transfer at the micro scale. Using recently observed experimental data, this work employed computational fluid dynamics coupled with electromagnetic simulations to determine if electrokinetically-forced, low-Reynolds number turbulence could be observed in a rectangular microchannel with using Newtonian fluids. Analysis of the results was done via comparison to the experimental criteria defined for turbulent flow. This work shows that, even with a simplified simulation setup, computational fluid dynamics (CFD) software can produce results comparable to experimental observations of low-Reynolds turbulence in microchannels using Newtonian fluids. In addition to comparing simulated velocities and turbulent energies to experimental data this work also presents initial data on the effects of electrokinetic forcing on microfluidic flow based on entropy generation rates.
REVIEW | doi:10.20944/preprints201808.0266.v1
Subject: Biology And Life Sciences, Biology And Biotechnology Keywords: microchannel; micro-array; microstructure; biofilms; polydimethylsiloxane; Micro-PCR; reynolds number; micro electro mechanical systems
Online: 15 August 2018 (05:37:59 CEST)
Micro-technology has played a substantial role in bioscience, biomedical and biotechnological research due to its core advantages in modern science and engineering. It has created unique development in various sectors of bio-research and upsurges the efficacy of research at the molecular level in recent years. Microfluidic technology makes it possible to manipulate sample volumes at the micro- and nano-level (called nanofluidics) with terrific control outside in vivo cellular microenvironment, enabling the reduction of discrepancies between in vivo and in vitro environments as well as reducing reaction time and cost. In this review, we discuss various effective integrations of microfluidic technologies into biotechnology and its paradigmatic significance in bio-research, supporting mechanical and chemical in vitro cellular micro-environment. Specific innovations relating to the application of microfluidics to advance microbial life, solitary and co-cultures along with a multiple-type cell culturing, cellular communications, cellular interactions and population dynamics are discussed.
ARTICLE | doi:10.20944/preprints202210.0089.v1
Subject: Engineering, Industrial And Manufacturing Engineering Keywords: micro surface structures; mask electrolyte jet machining; electrochemical micro machining
Online: 8 October 2022 (03:11:36 CEST)
The controllability and consistency in the fabrication of micro-textures on large-scale remains a challenge for existing production processes. Mask electrolyte jet machining (MEJM) is an alternative to Jet-ECM for controllable and high-throughput surface microfabrication with more consistency of dimensional tolerances. This hybrid configuration combines the high-throughput of masked-ECM and the adjustable flow-field of jet-ECM. In this work, a duckbill jet nozzle was introduced to make MEJM more capable of batch micro-structuring. A multiphysics model was built to simulate the distribution of electrochemical reaction ions, the cur- rent density distribution and the evolution of the shape of the machined cavity. Experimental investigations are presented showing the influence of the machining voltage and nozzle moving speed on the micro cavity. Several 35 ×35 micro cavity arrays with a diameter of 24.92 − 11.73 µm and depth of 15.86 − 7.24 µm are generated on 304 stainless steel.
ARTICLE | doi:10.20944/preprints202011.0180.v1
Subject: Physical Sciences, Optics And Photonics Keywords: microwave photonics; RF channelizer; micro-ring resonators; Kerr micro-combs
Online: 4 November 2020 (09:25:43 CET)
We report a 92 channel RF channelizer based on a 48.9 GHz integrated micro-comb that operates via soliton crystals, together with a passive high-Q ring resonator that acts as a periodic filter with an optical 3dB bandwidth of 121.4 MHz. We obtain an instant RF bandwidth of 8.08 GHz and 17.55 GHz achieved through temperature tuning. These results represent a major advance to achieving fully integrated photonic RF spectrum channelizers with reduced low complexity, size, and high performance for digital-compatible signal detection and broadband analog signal processing.
ARTICLE | doi:10.20944/preprints201811.0175.v1
Subject: Engineering, Mechanical Engineering Keywords: vibration-induced flow; micro-pillar; numerical analysis; micro-PIV; acoustofluidics
Online: 7 November 2018 (14:57:56 CET)
The steady streaming (SS) phenomenon is gaining increased attention in the microfluidics community, because it can generate net mass flow from the zero-mean vibration. We developed numerical simulation and experimental measurement tools to analyze this vibration induced flow, which has been challenging due to its unsteady nature. Validity of these analysis methods is confirmed by comparing the three-dimensional (3D) flow field induced around a cylindrical micropillar under circular vibration. In the numerical modeling, we directly solved the flow in the Lagrangian frame so that the substrate with a micropillar becomes stationary, and the result was converted to the Eulerian frame to compare them with the experimental results. The present approach enables to avoid the introduction of moving boundary or small perturbation approximation. The flow field obtained by the micro particle image velocimetry (PIV) measurement supported the three-dimensionality observed in the numerical results, which could be important for controlling the mass transport and manipulating particulate objects in the microfluidic systems.
ARTICLE | doi:10.20944/preprints202305.2098.v1
Subject: Engineering, Control And Systems Engineering Keywords: Resistograph; wood density; micro drill resistance; linear model; micro destructive measurement
Online: 30 May 2023 (09:35:40 CEST)
To improve the measurement accuracy of wood density and study the linear correlation between the drill feed resistance and wood density, a new micro drill instrument that can can simultaneously measure the rotation resistance and feed resistance of the drill needle was designed. The test wood samples included hardwood, softwood and conifer. The absolute dry density of each wood sample was measured. The drill resistance data was tested by using self-developed micro drill instrument and Resistogaph 650-SC. 4 linear models between drill resistance and the absolute dry density of wood . The results showed that: the statistical indicators of each model of the self-made micro drill resistance in-strument were better than the corresponding indicators of Resistogaph 650-SC; the coefficient of determination of the linear regression model between the feed resistance of the self-made micro drill resistance instrument and the absolute dry density of wood was 0.946; the statistical indicators of model including rotation resistance and feed resistance, were better than those of the model only including rotation resistance. Therefor, the design proposed in the article is reasonable, and increasing the feed resistance can improve the measurement accuracy of the micro drill resistance instrument for measuring wood density.
ARTICLE | doi:10.20944/preprints201711.0154.v1
Subject: Physical Sciences, Applied Physics Keywords: micro fluidic channel; micro particles; fluid flow rate; lab-on-a-chip; waveguide
Online: 23 November 2017 (11:13:24 CET)
In this work modeling and analysis of an integrated opto-fluidic sensor, with a focus on achievement of single mode optical confinement and continuous flow of micro particles in the microfluidic channel for Lab-on-a Chip (LOC) sensing application is presented. This sensor consists of integrated optical waveguides, microfluidic channel among other integrated optical components. A continuous flow of micro particles in a narrow fluidic channel is achieved by maintaining the two sealed chambers at different temperatures and by maintaining a constant pressure of 1Pa at the centroid of narrow fluidic channel geometry. The analysis of silicon on insulator (SOI) integrated optical waveguide at an infrared wavelength of 1550nm for single mode sensing operation is presented. The optical loss is found to be 0.0005719dB/cm with an effective index of 2.2963. The model presented in this work can be effectively used to detect the nature of micro particles and continuous monitoring of pathological parameters for sensing applications.
REVIEW | doi:10.20944/preprints202212.0443.v1
Subject: Computer Science And Mathematics, Other Keywords: Expressions; Lie detection; Emotions; Micro expressions
Online: 23 December 2022 (04:20:53 CET)
In our day-to-day life, Lie detection has a significant concern. We human beings are very much inaccurate while detecting the liars and We believe in what we are told. Lie detection is important in today’s life, because Concealing the information or faking it can sometimes take you to huge problems. In any areas like airport management, criminal investigations, counterterrorism, etc this concept has great importance. It is an evergreen challenging and changing topic. This paper presents the common technique which was followed up till now and why it was not considered effective and a review of Robust solutions to detection of deception. People generally do not always believe on what someone says but also try to visualize their facial expressions. While in Robust solution these facial micro-expressions are identified, which are tiny, natural expressions seen on the individual’s face, when they try to conceal or suppress emotions. In addition, the article also provides the year-wise assessment and analysis of research articles published in the area of Lie detection from 2011 to 2022. In the end, our proposed framework for lie detection system is also presented. This paper cover up current issues as well as challenges that could be helpful to resolve in future research works. The review paper closes up by supporting future directions.
ARTICLE | doi:10.20944/preprints201904.0136.v1
Subject: Chemistry And Materials Science, Metals, Alloys And Metallurgy Keywords: Sn58Bi; Ag; micro-alloy; mechanical; reliability
Online: 11 April 2019 (08:52:43 CEST)
Abstract: Microstructural and mechanical properties of the eutectic Sn58Bi and micro-alloyed Sn57.6Bi0.4Ag solder alloys were compared. With the addition of Ag micro-alloy, the tensile strength was improved and this is attributed to a combination of microstructure refinement and an Ag3Sn precipitation hardening mechanism. However, ductility is slightly deteriorated due to the brittle nature of the Ag3Sn intermetallic compounds (IMCs). Additionally, a board level reliability study of Ag micro-alloyed Sn58Bi solder joints produced utilising a surface-mount technology (SMT) process, were assessed under accelerated temperature cycling (ATC) conditions. Results reveal that micro-alloyed Sn57.6Bi0.4Ag has a higher characteristic lifetime with a narrower failure distribution. This enhanced reliability corresponds with improved bulk mechanical properties. It is postulated that Ag3Sn IMCs are located at the Sn-Bi phase boundaries and suppress the solder microstructure from coarsening during the temperature cycling, hereby extending the time to failure.
REVIEW | doi:10.20944/preprints201807.0434.v1
Subject: Biology And Life Sciences, Immunology And Microbiology Keywords: Gut micro milieu, immunity and microRNAs
Online: 23 July 2018 (21:33:29 CEST)
The tissue micro environment or milieu consists of a highly dynamic population of cellular and non-cellular components which constitute a complex regulatory network aimed at maintaining the organ homeostasis. In the modern medicine the discovery of miRNAs is undoubtedly a promising field of research and they are essential in orchestrating immune system logic and their release in the gut micro milieu can directly affect bacterial gene expression. Here, we brieﬂy review the role of microRNAs, focuses on their role on immune system components in physiological and pathophysiological gut micro milieu.
ARTICLE | doi:10.20944/preprints201908.0143.v1
Subject: Medicine And Pharmacology, Orthopedics And Sports Medicine Keywords: acid-etching; micro-rough; bone regeneration; sub-micro-rough; bone integration; osseointegration; dental implants; orthopedic implants
Online: 12 August 2019 (12:35:48 CEST)
Titanium micro-scale topography results in excellent osteoconductivity and bone-implant integration. However, the biological effects of sub-micron topography are unknown. We compared osteoblastic phenotypes and in vivo bone and implant integration abilities between titanium surfaces with micro- (1–5 µm) and sub-micro-scale (0.1–0.5 µm) topographies and machined titanium. Average roughness was 12.5 ± 0.65 nm, 123 ± 6.15 nm, and 24 ± 1.2 nm for machined, micro-rough, and sub-micro-rough surfaces, respectively. The micro-rough surface showed the fewest cells attaching during the initial stage and the lowest proliferation. Calcium deposition and expression of osteoblastic genes were highest on the sub-micro-rough surface and lowest on the machined surface. Bone-to-implant integration was strongest for the micro-rough surface, consistent with it having the greatest ability to retain cells in vitro. Thus, the biological effects of titanium surfaces are not necessarily proportional to the degree of roughness in osteoblastic cultures or in vivo. Sub-micro-rough titanium ameliorates the disadvantage of micro-rough titanium by restoring cell attachment and proliferation and enhances the rate of osteoblastic differentiation over that of micro-rough titanium; however, bone integration and the ability to retain cells are compromised due to its lower interfacial mechanical locking compared to that of micro-rough titanium.
ARTICLE | doi:10.20944/preprints202309.0176.v1
Subject: Environmental And Earth Sciences, Atmospheric Science And Meteorology Keywords: water vapour; micro-pulse laser; Raman lidar
Online: 5 September 2023 (02:45:44 CEST)
It was for long time believed that lidar systems based on the use of high-repetition micro-pulse lasers could be effectively used to only stimulate atmospheric elastic backscatter echoes, and thus only exploited in elastic backscatter lidar systems. Their application to stimulate rotational and roto-vibrational Raman echoes, and consequently their exploitation in atmospheric thermodynamic profiling, was considered not feasible based on the technical specifications possessed by these laser sources until a few years ago. However, recent technological advances in the design and development of micro-pulse lasers, presently achieving high UV average powers (1-5 W) and small divergences (0.3-0.5 mrad), in combination with the use of large aperture telescopes (0.3-0.4 m diameter primary mirrors), allow to presently develop micro-pulse laser-based Raman lidars capable to measure the vertical profiles of atmospheric thermodynamic parameters, namely water vapour and temperature, both in daytime and nighttime. This paper is aimed at demonstrating the feasibility of these measurements and at illustrating and discussing the high achievable performance level, with a specific focus on water vapour profile measurements. The technical solutions identified in the design of the lidar system and their technological implementation within the experimental setup of the lidar prototype are also carefully illustrated and discussed.
ARTICLE | doi:10.20944/preprints202210.0269.v1
Subject: Chemistry And Materials Science, Metals, Alloys And Metallurgy Keywords: mass transfer; micro-scale flow; diffusion; convection
Online: 19 October 2022 (07:00:10 CEST)
Mass transfer is often the rate determining step for solid-liquid chemical reactions. Decrease of the concentration boundary layer thickness is essential to intensify the chemical reaction. Because the concentration boundary layer exists in the velocity boundary layer, force imposition in the concentration boundary layer by superimposing an electrical current and a magnetic field was proposed. Through, flow can be directly excited in the concentration boundary layer. The previous result indicates that by superimposing a DC current and a gradient magnetic field, the development of the concentration boundary layer was suppressed, because of a macro-scale flow excitation in the whole vessel. And by superimposing the gradient magnetic field with a modulate current, the development of the concentration boundary layer was further suppressed. This is because of the macro-scale flow enhancement and the excitation of a micro-scale flow near the solid-liquid interface. However, the mechanism for the micro-scale flow excitation has not been clarified. To clarify this, a uniform magnetic field was superimposed with the DC current or the modulate current. By this means, only the micro-scale flow was excited near the anode surface. The results found that the non-unform electromagnetic force distribution is the main reason for the micro-scale flow excitation.
ARTICLE | doi:10.20944/preprints202207.0446.v1
Subject: Environmental And Earth Sciences, Waste Management And Disposal Keywords: sustainable; decentralized; wastewater; treatment; micro-nanobubbles; biomedia
Online: 29 July 2022 (03:42:31 CEST)
As the scarcity of potable water increases, recycling of treated wastewater is increasing. Small-scale, decentralized treatment can be implemented to serve local populations by keeping water within their boundaries and within reach for reuse, particularly in less dense, non-urban communities. Availability of cellular networks and high-speed internet connectivity, along with significant reduction in cost, allows ongoing monitoring of decentralized treatment systems at a central location. In this paper a decentralized treatment system using micro nanobubble aeration, moving media and membranes is able to produce reusable water with low energy consumption, thereby allowing the use of solar energy in places with unreliable electrical supply. The treatment system, which uses no external chemicals, is able to operate unattended and deliver clear, disinfected water with non-detect suspended solids, BOD5 less than 10 mg/L and nutrients below 5 mg/L.
ARTICLE | doi:10.20944/preprints202207.0308.v1
Subject: Computer Science And Mathematics, Computer Science Keywords: micro-video classification; 3D CNN; multi-modal
Online: 21 July 2022 (03:09:34 CEST)
Along with the popularity of the Internet, people are exposed to more and more ways of micro-videos, and a huge amount of micro-video data has emerged. micro-videos have gradually become the Internet content preferred by the public, and a large number of micro-video apps have also emerged, such as Tiktok and Kwai. Intelligent classification and mining of micro-videos can greatly enhance user experience, improve business operation efficiency and enhance user experience. Through deep intelligent analysis and mining of micro-videos, important information in micro-videos can be extracted to provide an important basis for beautifying videos, content appreciation, video recommendation, content search, etc. In the past, content understanding for short videos often used human work annotation, but in recent years, with the great success of deep convolutional neural networks in image recognition, short video content understanding based on this method has gradually developed. Nowadays, most recognition algorithms extract the feature representation of each frame independently and then fuse them. However, while extracting the feature representation, some low-level semantic features are lost, which makes the algorithm unable to accurately distinguish the category of the video. At present, the algorithm of micro-video recognition based on deep learning has surpassed the iDT algorithm, making these traditional methods fade out of people’s view. In this paper according to the micro-video classification task, a new network model is proposed to concatenate features of each modality into the overall features of various modalities through the network, and then fuse the various modal features with the attention mechanism to obtain the whole micro-video features, which will be used for classification. In order to verify the effectiveness of the algorithm proposed in this paper, experiments are conducted in the public dataset, and it is shown the effectiveness of our model.
Subject: Engineering, Electrical And Electronic Engineering Keywords: integrator; Kerr micro-comb; RF signal processing
Online: 12 March 2020 (04:05:22 CET)
We demonstrate a photonic RF integrator based on an integrated soliton crystal micro-comb source. By multicasting and progressively delaying the input RF signal using a transversal structure, the input RF signal is integrated discretely. Up to 81 wavelengths are provided by the microcomb source, which enable a large integration time window of ~6.8 ns, together with a time resolution as fast as ~84 ps. We perform signal integration of a diverse range of input RF signals including Gaussian pulses with varying time widths, dual pulses with varying time intervals and a square waveform. The experimental results show good agreement with theory. These results verify our microcomb-based integrator as a competitive approach for RF signal integration with high performance and potentially lower cost and footprint.
ARTICLE | doi:10.20944/preprints202311.1844.v1
Subject: Biology And Life Sciences, Toxicology Keywords: CREB; PMMA; micro-plastics; confocal microscopy; nano-plastics
Online: 29 November 2023 (11:06:17 CET)
Both the use of plastic and its decomposition products lead to the distribution of plastic all over the earth and finally to the uptake by all kind of living beings including humans. Still, it is widely unknown what risks harbor the widespread uptake of plastics for human health, espe-cially regarding contributing factors like size, shape and surface composition. We assessed the uptake of polymethylmethacrylate (PMMA)-nano- and microbeads for HEK293-, A549- and MRC5 cells. Via confocal microscopy, we localized multiple PMMA-beads inside the cytosol of cells. Uptake of PMMA-beads did not alter cell growth and cell division, implying no short-term toxicity towards human cells. Further, we used a cAMP response element binding protein (CREB)-mediated reporter assay to assess whether internalized PMMA-nanobeads alter cell-signaling pathways. In contrast to the in vitro transcription, where the addition of PMMA-nanobeads abolished the transcription, no changes regarding CREB-mediated cell sig-naling are given in HEK293-cells. Our data led to the assumption that PMMA-nano-and mi-crobeads are internalized via endocytosis and end up as lysosomes within the cells cytosol. Therefore, we concluded differences regarding the surface composition of the PMMA-nanobeads mainly affect its potential to alter cell signaling. These findings emphasize the key role the sur-face composition plays regarding microplastic and its risks for human health.
ARTICLE | doi:10.20944/preprints202310.0448.v1
Subject: Engineering, Civil Engineering Keywords: concrete; micro-quartz; permeability; porosity; silica fume; strength
Online: 9 October 2023 (08:36:53 CEST)
This study aims to formulate binary cementitious systems containing silica fume (SF) and micro quartz (MQ) to improve cementitious concrete's durability and mechanical properties. In this investigation, we examined the effects of different essential variables, such as the level of SF and MQ replacement and the ratio of the water-binder (w/b). In this study, the w/b ratios were 0.25, 0.3, 0.35, and 0.4. Replacement levels for SF were 8, 10, and 12%, while replacement levels for MQ were 5, 8, 10, 15, 25, and 35%. The porosity and permeability decreased with an increase in replacement levels, regardless of the type of fine material used or the amount of replacement. Meanwhile, the strength increased markedly with SF replacement, reaching its maximum MQ of 25% at the SF level. The strength of the SF mixing was the highest in all mixes, and it remained the highest until 15% of MQ was replaced. The ultrafine size of MQ particles contributes to the improvement of compressive strength, porosity, and permeability in a similar way to SF particles, despite their high crystalline structure. Furthermore, in this study, analysis of variance (ANOVA) was employed to verify the influence of each variable on the studied response.
ARTICLE | doi:10.20944/preprints202308.1897.v1
Subject: Biology And Life Sciences, Neuroscience And Neurology Keywords: Glioma; Prognostic markers; Autophagy; Micro-RNA; Overall Survival
Online: 29 August 2023 (03:33:04 CEST)
Abstract: Autophagy has a dual role in gliomagenesis in a microRNA-modulated environment. We investigated the potential relevance of autophagy in glioma development and survival by exploring the association of autophagy-associated genes and microRNAs in low- and high-grade gliomas. Real-time PCR (qPCR) was used to determine the expression of genes and microRNAs in 50 fresh glioma tissues while Formalin-fixed paraf-fin-embedded tissues of the same patients were used for immunohistochemistry. The Mann-Whitney U-test test, Spearman correlation test, and Kaplan-Meier survival analysis were performed to evaluate the expression, association, and overall survival in patients respectively. The expression of LC3, AKT, and miR-21 was increased in high-grade glioma compared to low-grade glioma while ULK2 expression was decreased in high-grade glioma. A strong positive correlation was observed for ULK2 with UVRAG, PTEN, miR-7, and miR-100, while the moderate correlation with mTOR, Beclin1, miR-30, miR-204, miR-374, miR-21 and miR-126 in low-grade glioma, while a moderate positive correlation between ULK2 and PI3K, PTEN, ULK1, VPS34, mTOR, Beclin1, UVRAG, AKT and miR-374, and between AKT and ULK1, VPS34, UVRAG, and miR-7 in high-grade gliomas. The low ULK2 and LC3 expression group was significantly associated with better overall survival in gliomas while miR-21 overexpression showed a poor prognosis in glioma patients. Therefore, miR-21, ULK2, and LC3 may serve as prognostic biomarkers for survival outcomes in glioblastoma.
ARTICLE | doi:10.20944/preprints202308.1397.v1
Subject: Engineering, Mechanical Engineering Keywords: sound absorption; micro-perforates; panels vibration; global optimization
Online: 21 August 2023 (09:49:57 CEST)
Broadband noise reduction over the low-mid frequency range in the building and transportation sectors requires compact lightweight sound absorbers of typical sub-wavelength size. The use of multi-layered closely-spaced (micro-)perforated membranes or panels, if suitably optimized, contribute to these objectives. However, their elasticity or modal behaviors often impede the final acoustical performance of the partition. The objective of this study is to get insights into the vibrational effects induced by elastic limp membranes or panels volumetric modes on the optimized sound absorption properties of acoustic fishnets and functionally-graded partitions (FGP). Cost-efficient global optimization of the partition total frequency-averaged dissipation is achieved from simulated annealing with vibrational effects included through an impedance translation method. Critical coupling analysis reveals how the membranes or panels vibrations redistribute the locations of the Hole-Cavity resonances as well as their cross-coupling with the panels first volumetric mode. It is found that elastic limp micro-perforated membranes broaden the first pass-band of acoustic fishnets while smoothing out the dissipation ripples over the FGP optimiza-tion bandwidth. Moreover, the resonance frequency of the first panels mode sets an upper limit to the broadband optimization of FGPs, up to which high dissipation, low reflection and low trans-mission can be achieved.
ARTICLE | doi:10.20944/preprints202305.1953.v1
Subject: Biology And Life Sciences, Biology And Biotechnology Keywords: micro-nano bioglass; 3D printing; osteogenesis; angiogenesis; immunomodulation
Online: 29 May 2023 (03:30:12 CEST)
Magnesium ions play an important immune-regulatory role during bone repair. For this study, we prepared micro-nano bioactive glass containing magnesium, which can release magnesium, silicon, and calcium ions and has a positive impact on osteogenic differentiation and vascular regeneration. In this study, MgMNBG was compounded and combined with PLGA and PCL for 3D printing. Afterwards, the physicochemical properties and bone repair performance of the scaffolds were evaluated through in vitro and in vivo experiments. We also investigated the effects of MgMNBG on osteogenic differentiation, immune regulation, and vascular regeneration. The results showed that MgMNBG can inhibit inflammation and promote osteogenesis and angiogenesis by regulating macrophages. PLGA/PCL/MgMNBG scaffolds have good osteogenic and angiogenic effects, and the composite scaffolds have excellent bone repair performance and potential application value.
ARTICLE | doi:10.20944/preprints202304.0531.v1
Subject: Engineering, Industrial And Manufacturing Engineering Keywords: stamping without die; precision positioning; micro-hole array
Online: 19 April 2023 (03:34:27 CEST)
Aluminum alloy (Al6061) sheet micro-hole processing is extensively used in smartphones, tablet PC, and smart wearable devices. The micro-hole processing is commonly performed using laser, micro drilling, microstamping, micro discharge, and chemical etching technologies. Micro-stamping technology is characterized by precision and rapid processing, but the precision positioning of the punch head and lower die is one of the major difficulties in micro-hole stamping, especially in manufacturing array micro-holes. This study used stamping without die technology. This technology uses an array punch head to punch the lower die holes on the base, then performs array micro-hole stamping. The experimental results show that a micro-hole array with 37 micro-holes were successfully manufactured and can be reproduced many times. Tapered array micro-holes with a high aspect ratio can be manufactured using this stamping without die technology; the micro-hole depth can be 260μm, the inlet diameter is 116μm, and the outlet diameter is 25μm. This study has successfully developed the feasibility of array micro-hole stamping technology.
ARTICLE | doi:10.20944/preprints202209.0352.v1
Subject: Chemistry And Materials Science, Biomaterials Keywords: bioreactor; secondary caries; caries model; DCPD; micro-CT
Online: 23 September 2022 (03:00:11 CEST)
This study evaluated the efficacy of experimental TEGDMA-functionalized dicalcium phosphate dihydrate (T-DCPD) filler-based resin-based composites (RBC) in preventing caries lesions around the restoration margins (secondary caries”, SC). Standardized Class-II cavities were made in sound molars having the cervical margin in dentin. Cavities were filled with a commercial resin-modified glass-ionomer cement (RMGIC) or experimental RBCs containing a BisGMA-TEGDMA resin blend and one of the following inorganic fractions: 60 wt.% Ba glass (RBC-0); 40 wt.% Ba glass, 20 wt.% T-DCPD (RBC-20); 20 wt.% Ba glass, 40 wt.% T-DCPD (RBC-40). An open-system bioreactor produced S. mutans biofilm-driven SC. Specimens were scanned using micro-CT to evaluate demineralization depths. Scanning Electron Microscopy and Energy-dispersive X-ray Spectroscopy characterized the specimens’ surfaces, while antimicrobial activity, buffering effect, and ion uptake by the biofilms were also evaluated. ANOVA and Tukey’s test were applied at p<0.05. RBC-0 and RBC-20 showed SC development in dentin, while RBC-40 and RMGIC significantly reduced the lesion depth at the restoration margin (p<0.0001). Initial enamel demineralization could be observed only around RBC-0 and RBC-20 restorations. A direct antibiofilm activity could explain SC reduction by RMGIC, while a buffering effect on biofilm’s acidogenicity explained the behavior of RBC-40. Experimental RBC with CaP-releasing functionalized T-DCPD filler could prevent SC with the same efficacy as F-releasing materials.
ARTICLE | doi:10.20944/preprints202208.0187.v1
Subject: Business, Economics And Management, Finance Keywords: associativity; self-management; autonomy; solidarity; micro-credits; sustainability
Online: 10 August 2022 (03:50:20 CEST)
This research was carried out with the objective of analyzing the principles of social and solidarity economy in the community funds of the rural sector of Pichincha, Ecuador. Small organizations promote microcredits for local, social and economic development, representing an alternative to those managed by traditional banks. The research was descriptive, non-experimental field research. The population analyzed consisted of 220 community funds, and the size of the representative sample was 49 community organizations that practice solidarity finance. The data were collected through online questionnaires using a Likert scale, and the validity of this approach was judged by experts; the reliability of the instrument obtained was 0.95 using the Cronbach’s alpha method. The results highlight that in these organizations, the following traits prevail: associativity, self-management and organization. However, autonomy and solidarity have a negative valuation, which shows that strategies must be rethought to achieve the empowerment of the financial service. This will allow them to be sustainable and to expand with more benefits that promulgate financial activity and promote structures in rural community networks that promote local development and strengthen deficient principles as a basis for generating a greater benefit to the partners.
ARTICLE | doi:10.20944/preprints202112.0341.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: microfoming; energy field assisted micro/nanoforming; ultrasonic vibration
Online: 21 December 2021 (13:53:15 CET)
Excitation of the acoustic field leading to the Blaha effect affects the plasticity of the material significantly in ultrasonic vibration-assisted forming. In a micro-forming field, the effects are more significant in the deformation in surface of materials -, in which reduction of the surface roughness based on the increasing of plastic deformation of surface asperity was effective . On the other hand, the effect on deformation behavior of the bulk region indicted reduction in the yield stress of materials, and not only acoustic effect , but also impact effect is found to generate a large amount of dislocation and produce plastic deformation . However, the effect on the bulk is more significant as that on the surface. Differences in the effect on the surface and the bulk are not clarified. In this study, the mechanism of the deformation in the surface of the material with ultrasonic vibration assistance is investigated and compared with that in the bulk. Forging tests using a newly developed ultrasonic vibrator were carried out on pure Cu foils with various process conditions. The longitudinal vibration frequency of the ultrasonic transducer is 60∓2kHz, and the vibration amplitude is in an adjustable range of 0~10μm. Forging test was carried out at different initial stress, specimen size and amplitude. The difference in acoustic softening and impact effects on the surface and the bulk was discussed.
ARTICLE | doi:10.20944/preprints202106.0380.v2
Subject: Engineering, Electrical And Electronic Engineering Keywords: Micro-Datacenters; information and communications technology (ICT); Efficiency
Online: 6 October 2021 (15:59:04 CEST)
The rapid growth of the Information and Communications Technology (ICT) sector requires additional infrastructure, such as more micro-datacenters and telecom stations, to support the higher internet speeds and low latency requirements of 5G net-works. The increased power requirements of the new ICT technologies necessitate the proposal of new power supplies in an attempt to retain the increase in energy demand and running costs. This work provides an in-depth theoretical analysis on the losses of the individual stages of commercially available PSU and proposes a new multicell PSU, Buck-PFC converter, which offers a higher overall efficiency at varying load levels. The theoretical results are verified using simulation results, via PSIM Thermal Module, and using experimental data. The results indicate that multi-cell structures can improve the overall PSU ef-ficiency by 1.2% at 50% rated power and more than 2.1% at full power. Finally, taking into consideration the economic implica-tions of this study, it is shown that the proposed multicell structure may increase the PSU costs by 10.78% but the payback pe-riod is in the order of just 3.3 years.
ARTICLE | doi:10.20944/preprints202105.0271.v1
Subject: Engineering, Control And Systems Engineering Keywords: Micro-mobility; Ride-sharing; Agent-based modelling; Crowdsourcing
Online: 12 May 2021 (13:48:39 CEST)
Substantial research is required to ensure that micro-mobility ride sharing provides a better fulfillment of user needs. This study proposes a novel crowdsourcing model for the ride-sharing system where light vehicles such as scooters and bikes are crowdsourced. The proposed model consists of three entities: suppliers, customers, and a management party responsible for receiving, renting, booking, and demand matching with offered resources. It can allow suppliers to define the location of their private e-scooters/e-bikes and the period of time they are available for rent. Using a dataset of over 9 million e-scooter trips in Austin, Texas, we ran an agent-based simulation six times using three maximum battery ranges (i.e., 35, 45, and 60 km) and different numbers of e-scooters (e.g., 50 and 100) at each origin. Computational results show that the proposed model is promising and might be advantageous to shift the charging and maintenance efforts to a crowd of suppliers.
ARTICLE | doi:10.20944/preprints202104.0030.v1
Subject: Environmental And Earth Sciences, Soil Science Keywords: micro minerals, selenium, deficiency, soil-plant relationship, Kosovo
Online: 1 April 2021 (16:17:35 CEST)
Minerals play many important functions in plant and animal metabolism. Therefore, we investigated the concentration of Se and other minerals and their relationships in soils and fodder plants in Kosovo. Seventy-three samples of each soil and fodder plants (grass, maize, and wheat) from 30 farms were collected. Both soil and plant samples, after processing and digestion, were analyzed for mineral concentration by ICP-MS. Mineral concentrations in soil and fodder crops, and the best predicting/explanatory models for micro minerals concentration, achieved by stepwise linear regression, are presented. Results showed very low concentration of Se in most of the soil and all fodder samples. In addition, the concentration of Co, Zn and Fe was not sufficient to satisfy requirements for all categories of farm animals. Plant Se concentration showed a positive relationship with Se concentration in soils. Plant Zn, Mo, Mn, Fe and Pb, in general, showed no significant relationship with their concentration in soil, while plant Co and Cd showed positive relationship only in maize, and Cu in wheat grain. Among the soil properties, pH had the highest effect on the concentrations of Co, Mo, Mn, Cd and Pb in fodder crops.
ARTICLE | doi:10.20944/preprints202101.0229.v1
Subject: Chemistry And Materials Science, Analytical Chemistry Keywords: Steel, Conversion coating; Self-healing; Micro-structural characteristics
Online: 12 January 2021 (15:47:40 CET)
A phosphate/molybdate and cerium-modified phosphate/molybdate conversion coatings were deposited on a carbon steel surface and their protective and self-healing abilities were evaluated. Surface morphology and inner structure of the coatings were examined using FE-SEM-FIB and TEM techniques, chemical composition and element distribution depth profiles in conversion layers were determined using EDX measurements, whereas XPS was applied for the analysis of Mo and Ce oxidation states. Voltammetric measurements and EIS were performed to assess the corrosion behavior of the samples. The higher protective and stronger self-healing abilities were found for phosphate/molybdate/cerium conversion coating deposited in a sulphate-containing solution. This was attributed to higher values of both: total cerium and Ce(IV) content in the conversion layer as well as to lower number of structural defects in the coating. It was demonstrated that the micro-structural characteristics of protective coatings are also important in determining self-healing abilities.
ARTICLE | doi:10.20944/preprints202012.0520.v1
Subject: Engineering, Automotive Engineering Keywords: Micro-dissection; Ultrasonic vibration; Flexure-guided; Tissue section
Online: 21 December 2020 (12:06:42 CET)
Biological micro-dissection has a wide range of applications in the field of molecular pathology. The current laser-assisted dissection technology is expensive, and laser radiation can lead to sample contamination. As an economical and pollution-free micro-dissection method, piezoelectric ultrasonic micro-dissection has a wide application prospect. However, the performance of the current piezoelectric ultrasonic micro-dissection technology is unsatisfactory. In this paper, a novel piezoelectric ultrasonic micro-dissection device based on a flexure mechanism is proposed in order to solve the problems of low dissecting precision and excessive wear of the dissecting needle caused by the harmful lateral vibration of the current piezoelectric ultrasonic micro-dissection device. By analyzing the flexibility of flexure hinge, the type of flexure beam and the optimal design parameters are determined. Through comparing the harmonic response simulation analysis of the micro-dissection device based on a flexure mechanism and the traditional micro-dissection device without the flexure mechanism, the newly designed micro-dissection device achieves the best vibration effect when the driving frequency is 28kHz, compared with the traditional micro-dissection device, the lateral vibration suppression effect is improved by 68%. Then, based on the 3D printing technology, a prototype of a novel micro-dissection device was produced, and its performance was tested. It was found that the flexure mechanism did indeed suppress the lateral vibration of the needle tip. Finally, the experiments of 5μm thick paraffin-embedded rat liver sections were carried out, and the effects of different dissecting parameters on the dissecting effect were analyzed, and the optimal dissecting parameters were obtained. By comparing the dissecting effects of the tissue sample and the wear condition of the needle tip between the novel micro-dissection device and the traditional micro-dissection device under their optimal dissecting parameters, it is proved that the suppression of harmful lateral vibration not only significantly improves the dissecting effect, but also improves the service life and durability of the dissecting needle, which is beneficial to reduce the equipment costs.
ARTICLE | doi:10.20944/preprints202010.0188.v1
Subject: Business, Economics And Management, Accounting And Taxation Keywords: partial flipped classroom; active learning pedagogies; micro lectures
Online: 9 October 2020 (08:49:50 CEST)
The flipped classroom is gaining prominence as an active learning pedagogy to engage a new generation of students. However, all courses do not lend themselves to a fully flipped design and instructors are often reluctant to flip lectures. In this study, I experimented with a “partial” flipped classroom design in a first-year undergraduate economics course. In this partial flipped format, traditional lectures were substituted with micro-lectures and the remaining class time was devoted to activities like quizzes, group work and student presentations. The full lectures were panopto recorded and put up on the e-learning site, Blackboard. This format enabled me to combine the benefits of a traditional lecture with a flipped classroom design. In order to evaluate the effectiveness of the partial flipped classroom format, I compared the final exam scores of students in the partial flipped classroom with those in the control group, which followed a traditional lecture-based approach. The key results from the analysis revealed that students in the partial flipped classroom performed better in the final exams vis-à-vis students in the traditional classroom format. Furthermore, the partial flipped classroom format was associated with lower odds of students failing in the module. This format also resulted in better student engagement, more flexibility and enhanced student-tutor interaction within the classroom.
REVIEW | doi:10.20944/preprints202007.0608.v1
Subject: Biology And Life Sciences, Ecology, Evolution, Behavior And Systematics Keywords: Biogeography; Ecology; Environmental samples; Micro-organisms; Soil biodiversity
Online: 25 July 2020 (11:54:02 CEST)
The Neotropical region is one of the most diverse regions of the globe in terms of macro-organismic species. Regarding the microbial world, however, little is known about the diversity and biogeography patterns of micro-organisms in the Neotropics. In this context, the study of several microbial taxonomic groups is still missing and/or incomplete, such as the protists. Our goal here was to summarize the available information of Neotropical protists, focusing on molecular data from environmental continental samples, to explore what these data evidence on their ecology and biogeography. For this, we reviewed the findings from all articles that focused on or included the terrestrial protists using metabarcoding approach and identified the gaps and future perspectives in this research field. We found that Neotropical protists diversity patterns seem to be, at least in part, congruent with that of macro-organisms and, different than plants and bacteria, just weakly explained by environmental variables. We argue that studies with standardized protocols including different biomes are necessary to fully characterize the ecology and biogeography on Neotropical protists. Furthermore, dismember evolutionary lineages and functional guilds of protists are important to better understand the relationship between diversity, dispersal abilities and functionality of particular taxa of protists in their habitats.
ARTICLE | doi:10.20944/preprints202005.0185.v1
Subject: Chemistry And Materials Science, Materials Science And Technology Keywords: severe plastic deformation; iron hardness; micro/nano-structure
Online: 11 May 2020 (03:33:40 CEST)
The evolution of metals micro/nano-structure upon severe plastic deformation (SPD) is still far to be theoretically explained, while experimental datasets are persistently growing for several decades. Major problem associated with understanding of SPD is related to a fact that the latter is a synergetic product of several competing physical effects which alter the material micro/nano-structure. In attempt to find deformational boundaries, where predominantly one mechanism determines the micro/nano-structure, in this paper we propose a continuous piecewise model for the analysis of experiments on material hardness vs strain of SPD processed materials. The novelty of this approach lies in its ability to find, as free-fitting parameters, the strain breakpoints which separate different micro/nano-structure modes generated upon SPD process. The model is applied to analyse experimental data for polycrystalline samples of pure iron and two distinctive strain breakpoints are revealed with good accuracies. This finding is in a good agreement with our earlier results on TEM microscopy studies on pure iron polycrystals after SPD treatment.
Subject: Medicine And Pharmacology, Dentistry And Oral Surgery Keywords: Insertion torque; Pullout strength; Gripping volume; Micro-implant
Online: 10 February 2020 (11:32:53 CET)
This study evaluated the mechanical strengths of three types of orthodontic micro-implants by analyzing their structural configurations. Thirty micro-implants of three types (diameter 1.5 mm, Types A, B, C) were assessed. All micro-implants were manually driven into artificial bones at an 8-mm depth. The insertion torque (IT), pullout strength (PS), and gripping volume (GV) of each type were measured. Intergroup comparisons and intragroup correlation were investigated by statistical analysis. Type B had the greatest inner–outer diameter ratio (0.67), and Type A had the smallest (0.53). The IT of Type A (5.26 Ncm) was significantly (p = 0.038) lower than that of Type C (8.8 Ncm). There was no significant difference in the pullout strength (p = 0.868). The GV of Type A (9.7 mm3) was significant (p < 0.01) greater than Type C (8.4 mm3). Type C was significant (p < 0.01) greater than Type B (7.2 mm3). Spearman’s rho rank correlation test showed that PS of Type B was correlated significantly with GV. In conclusion, the design of thread and its GV were the important factors on the mechanical strengths of micro-implant.
ARTICLE | doi:10.20944/preprints201910.0285.v1
Subject: Chemistry And Materials Science, Biomaterials Keywords: additive manufacturing; biyomedikal alloy; micro structure; mechanical properties.
Online: 25 October 2019 (11:24:36 CEST)
The Wolfram (W), Silicium (Si) and Molybdenum (Mo) doped Co-Cr biomedical alloy were fabricated by additive manufacturing method, which is part of powder metadology. The mixture of Wolfram (W), Silicium (Si), Chrome (Cr) and Cobalt (Co) alloy is known good wear and corrosion resistance among of biomedical applications. By addition of Molybdenum (Mo) into the structure of alloy, the structure become more stbale also increase the corrosion and wear resistance. In addition, the effects of secondary annealing process on the alloy were investigated. The microstructure of the produced alloy was analyzed by X-ray diffraction method XRD, Energy Dispersive X-Ray Analysis EDX and scanning electron microscope SEM. Moreover, Electrochemical corrosion test, micro hardness and density measurements were performed to investigate the mechanical properties of the alloy. As a result of the analyzes, the effects of Molydenum (Mo) doped and secondary annealing on the microstructure and mechanical properties of bioalloying were determined.
ARTICLE | doi:10.20944/preprints201811.0576.v1
Subject: Physical Sciences, Optics And Photonics Keywords: OMAG method; flow rate measurement; micro flow rate
Online: 26 November 2018 (08:37:55 CET)
Optical micro-angiography (OMAG) is a new method of detecting flow rate and widely used for in vivo imaging. Although OMAG can distinguish between flowing and stationary parts, it cannot obtain accurate flow rate information. This study proposed a range formula for OMAG and the ultrahigh-sensitivity OMAG (UHS-OMAG) method to quantify the measurement range of an entire system. The parameters of the angle between beam scanning and flow directions, the angular velocity of the galvanometer, and the offset of incident light were introduced, and a formula for calculating the range was derived. Experiments were conducted to measure fine and ultra-fine flow rates by using OMAG and UHS-OMAG methods. The minimum measured flow rate was approximately 30 μm/s, and the maximum measured flow rate was approximately 8 mm/s. Experimental results are in good agreement with the preset results.
ARTICLE | doi:10.20944/preprints201708.0071.v1
Subject: Engineering, Control And Systems Engineering Keywords: micro seismic events; fuzzy logic; seismic event detection
Online: 21 August 2017 (09:55:55 CEST)
Natural events such as floods, fires, tsunamis, earthquakes and others have nowadays caused serious damage to human beings and nature. The precise detection of these natural events and especially the earthquake has nowadays become the focus of many computer and geoscientific researchers. Computer science and machine learning algorithms have revolutionized early detection and prediction of these events. Hence, a fuzzy method has been initially used in this article to enhance the authenticity of data based on application of effective variables and then combination of neural network algorithms of the MLP perceptron and radial network of RBF in form of a collective learning system in order to more accurately identify seismic events on a small scale. It was observed after simulating the proposed method that the proposed method has significantly improved based on actual error and root-mean-square error (RMSE) criteria compared to basic methods.
REVIEW | doi:10.20944/preprints201703.0072.v1
Subject: Chemistry And Materials Science, Biomaterials Keywords: micro-arc oxidation; antibacterial ability; Ag; Cu; Zn
Online: 14 March 2017 (07:49:40 CET)
Ti and its alloys are the most commonly used materials for biomedical applications. However, bacterial infection after implant placement is still one of the significant rising complications. Therefore, the application of the antimicrobial agents into implant surfaces to prevent implant-associated infection has attracted lots of attention. Scientific papers have shown that inorganic antibacterial metal element (e.g. Ag, Cu, Zn) can be introduced to implant surfaces with the addition of metal nanoparticles or metallic compounds into electrolyte via micro-arc oxidation (MAO) technology. In this review, the effects of the composition and concentration of electrolyte and process parameters (e.g. voltage, current density, oxidation time) on morphological characteristics (e.g. surface morphology, bonding strength), antibacterial ability and biocompatibility of MAO antimicrobial coating were discussed in detail. Anti-infection and osseo-integration can be simultaneously accomplished with the selection of the proper antibacterial elements and operating parameters. Besides, MAO assisted by magnetron sputtering (MS) to endow Ti-based implant materials with superior antibacterial ability and biocompatibility was also discussed. Finally, the development trend of MAO technology in the future was forecasted.
ARTICLE | doi:10.20944/preprints201608.0233.v1
Subject: Engineering, Electrical And Electronic Engineering Keywords: micro-Doppler; FMCW radar; through-the-wall; classification
Online: 31 August 2016 (09:02:32 CEST)
The ability to detect the presence as well as classify the activities of individuals behind visually obscuring structures is of significant benefit to police, security and emergency services in many situations. This paper presents the analysis from a series of experimental results generated using a through-the-wall (TTW) Frequency Modulated Continuous Wave (FMCW) C-Band radar system named Soprano. The objective of this analysis was to classify whether an individual was carrying an item in both hands or not using micro-Doppler information from a FMCW sensor. The radar was deployed at a standoff distance, of approximately 0.5 m, outside a residential building and used to detect multiple people walking within a room. Through the application of digital filtering, it was shown that significant suppression of the primary wall reflection is possible, significantly enhancing the target signal to clutter ratio. Singular Value Decomposition (SVD) signal processing techniques were then applied to the micro-Doppler signatures from different individuals. Features from the SVD information have been used to classify whether the person was carrying an item or walking free handed. Excellent performance of the classifier was achieved in this challenging scenario with accuracies up to 94%, suggesting that future through wall radar sensors may have the ability to reliably recognize many different types of activities in TTW scenarios using these techniques.
ARTICLE | doi:10.20944/preprints202310.1017.v1
Subject: Medicine And Pharmacology, Hematology Keywords: roxadustat; rhEPO; blood pressure; micro-inflammatory state; lipid metabolism
Online: 17 October 2023 (08:29:21 CEST)
Objective To observe the effect of roxadustat on blood pressure and micro-inflammatory response in patients with hemodialysis anemia, and to provide a viable technique for the treatment of hemodialysis anemia patients. Methods A total of 100 hemodialysis anemia patients admitted to the Nephrology Department of our hospital from July 2020 to July 2021 were enrolled and randomly divided into an observation group (roxadustat) and a control group (human recombinant erythropoietin (rhEPO). The clinical efficacy, blood lipid metabolism, inflammatory factor levels, iron metabolism-related indicators, blood biochemical indicators, anemia indicators, adverse reactions and blood pressure were recorded and compared. Results There was no significant difference in baseline data and serum indicators (P>0.05). The study group demonstrated superior performance to the control group in terms of clinical efficacy, blood lipid metabolism, inflammatory factor levels, iron metabolism-related indicators, blood biochemical indicators, anemia indicators, adverse reactions and blood pressure (all P<0.05). Conclusion Compared with rhEPO treatment, roxadustat exhibits a promising outcome in treating anemia and has slight impact on blood pressure of patients.
ARTICLE | doi:10.20944/preprints202310.0445.v1
Subject: Engineering, Telecommunications Keywords: Micro-gyroscopes; optomechanical; photonic crystal; angular vibration; dual-frame
Online: 8 October 2023 (10:38:41 CEST)
Micro-gyroscopes based on the Coriolis principle are widely employed in inertial navigation, motion control, and vibration analysis applications. This paper presents our main contributions which include a novel dual-frame optomechanical gyroscope, a unique photonic crystal cavity design, and advanced numerical simulation and optimization methods. The proposed design utilizes an optical cavity formed between dual oscillating frames, whereby input rotation induces a measurable phase shift via optomechanical coupling. Actuation of the frames is achieved electrostatically via an interdigitated comb-drive design. Through theoretical modeling based on cavity optomechanics and finite element simulation, the operating principle and performance parameters are evaluated in detail. Results indicate an expected angular rate sensitivity of 22.8 mV/°/s and angle random walk of 7.1×10-5 °/h1/2, representing superior precision than to existing micro-electromechanical systems gyroscopes of comparable scale. Detailed analysis of the optomechanical transduction mechanism suggests this dual-frame approach could enable angular vibration detection with resolution exceeding state-of-the-art solutions.
ARTICLE | doi:10.20944/preprints202310.0131.v1
Subject: Engineering, Industrial And Manufacturing Engineering Keywords: grind process; micro-scale friction; modeling; collision; surface topography
Online: 4 October 2023 (03:18:50 CEST)
The grinding process by friction at the micro-scale in a mill with stones is considered a variable combination of contacts: with two-body (the asperities of lower millstone in direct contact with the asperities of upper millstone) and the three-body (micro-particles of ground seeds trapped between the asperities of lower and the upper stones of the mill). Three elements are described: (1) the mechanic contact of the asperities of the lower and upper millstone, to predict pressures on asperities, by modeling; (2) tests on a millstone sample covered with grinding particles, and (3) tests on a wafer sample formed by the millstones with the grinding particles between them. The paper highlights the combined effects of the micro-scale friction by individual measurements and to sum these effects an analytical model was used, and to validate the model, several experiments were performed. A suitable grind by friction assumes the grain’s movement and the interaction between the seeds and solid surfaces and is highlighted through theoretical and experimental studies. Topography analysis of the surface of the millstones revealed the model of microscopic frictional force. Endpoint measurements (the traces of the surface topography evolution), enable model verification in the grinding process.
ARTICLE | doi:10.20944/preprints202309.0811.v1
Subject: Engineering, Transportation Science And Technology Keywords: Active travel; mode choice; micro-mobility; shared mobility; walking
Online: 13 September 2023 (16:09:05 CEST)
Active transportation, such as walking, cycling, and micro-mobility modes, has received a lot of attention in recent years due to its potential benefits to urban residents, such as less traffic, better air quality, more opportunities to get exercise, and an overall higher quality of life. In this study, we used Classification and Regression Trees (CART) to compare and contrast three mobility options: shared micro-mobility, individual micro-mobility, and walking. We surveyed 219 people living in Budapest, Hungary, to learn more about their travel habits and investigate the demographic elements that influence people's mode choice, such as age, gender, ownership of micro-mobility modes, education, job, and income. Results showed that ownership of personal micro-mobility modes, and age as important predictors of active travel mode choice. Males seem to prioritize cost and weather conditions when choosing shared micromobility modes, while females value safety and weather conditions. Our findings can guide policy decisions and urban planning initiatives by identifying the most significant predictors of mode choice and evaluating the possible benefits and drawbacks of each mode.
ARTICLE | doi:10.20944/preprints202307.0997.v1
Subject: Engineering, Transportation Science And Technology Keywords: micro-mobility; bike crashes; spatial analysis; accidents; safety; cycling
Online: 14 July 2023 (08:54:49 CEST)
This manuscript presents a study on the spatial relationships between bike accidents, the built environment, land use, and transportation network characteristics in Budapest, Hungary using Geographic Weighted Regression (GWR). The sample period included bike crash data between 2017 and 2022. The findings provide insights into the spatial distribution of bike crashes and their severity, which can be useful for designing targeted interventions to improve bike safety in Budapest and be useful for policymakers and city planners in developing effective strategies to reduce the severity of bike crashes in urban areas. The study reveals that the built environment features, such as traffic signals, road crossings, and bus stops, are positively correlated with the bike crashes index, particularly in the inner areas of the city. However, traffic signals have a negative correlation with the bike crash index in the suburbs, where they may contribute to making roads safer for cyclists. The study also shows that commercial activity and PT stops have a higher impact on bike crashes in the northern and western districts. The GWR analysis further suggests that one-way roads and higher speed limits are associated with more severe bike crashes, while green and recreational areas are generally safer for cyclists. Future research should be focused on the traffic volume and bikes trips’ effects on the severity index.
ARTICLE | doi:10.20944/preprints202305.1146.v1
Subject: Chemistry And Materials Science, Food Chemistry Keywords: denomination of origin; micro-environments; parent trees; phenolic compounds
Online: 16 May 2023 (09:56:21 CEST)
About 90% of the Ataulfo mango (Mangifera indica L.) crops in Mexico are in the south of the country. This variety has significant amounts of antioxidant compounds. All the trees come from a small group of parents, however, the possible intravarietal variations and the micro-environments where it is grown can influence the compounds that contribute to the antioxidant capacity. The objective of this study was to quantify the antioxidant compounds of Ataulfo mango fruits of trees grown in Soconusco, Chiapas, Mexico (origin denomination), as well as fruits of the parent trees. In addition, possible associations between the contents of these compounds and the micro-environmental conditions collected were sought. In total, 465 fruits from 155 trees planted in 13 municipalities (locations) were analyzed. Fruits were collected at physiological maturity and stored at 25 °C until reaching commercial maturity. The contents of total phenolic compounds (TPC), antioxidant capacity (AC by DPPH, ABTS and FRAP methods), total anthocyanins (TA) and ascorbic acid (AA) were determined. The fruits from Huehuetán, presented the highest contents of PC (0.89 mg GAE g-1); however, the highest AC was found in the fruits harvested in Frontera Hidalgo, with 128.29 µmol TE g-1 (ABTS). The fruits obtained from the parents are within the average range of total TPC and AC, without significant differences between their fruits and those cultivated. The micro-environments where the Ataulfo mango trees are grown do not have a significant effect on antioxidant compounds (TPC, AC, TA and AA) and the only variables that allow segregation by localities are relative humidity, environmental temperature and altitude.
ARTICLE | doi:10.20944/preprints202305.0533.v1
Subject: Medicine And Pharmacology, Pulmonary And Respiratory Medicine Keywords: Respiratory syncytial virus; Nrf2; collagen; micro-CT; airway remodeling
Online: 8 May 2023 (11:21:24 CEST)
Severe respiratory syncytial virus (RSV) infections in early life have been linked to the development of chronic airway disease. RSV is a potent inducer of reactive oxygen species (ROS) which contributes to inflammation and enhanced clinical disease. NF-E2-related factor 2 (Nrf2) is an evolutionary conserved redox-responsive protein that helps to protect cells and whole organisms from oxidative stress and injury. The role of Nrf2 in the context of viral-mediated chronic lung injury is not known. Herein, we show that RSV experimental infection of adult Nrf2 deficient BALB/c mice (Nrf2-/-; Nrf2 KO) is characterized by enhanced disease, increased inflammatory cell recruitment to the bronchoalveolar compartment, and a more robust upregulation of innate and inflammatory genes and proteins, compared to wild type Nrf2+/+ competent mice (WT). These events that occur at very early time points, lead to increased peak RSV replication in Nrf2 KO compared to WT mice (day 5). To evaluate longitudinal changes of the lung architecture, mice were scanned weekly by high-resolution micro-computed tomography (micro-CT) imaging up to 28 days after initial viral inoculation. Based on micro-CT qualitative 2D imaging and quantitative reconstructed histogram-based analysis of lung volume and density, we found that RSV infected Nrf2 KO mice developed significantly greater and prolonged fibrosis compared to WT mice. Results of this study underscore the critical role of Nrf2-mediated protection from oxidative injury not only in acute pathogenesis of RSV infection, but also in its long-term consequences of chronic airway injury.
REVIEW | doi:10.20944/preprints202304.0764.v1
Subject: Engineering, Electrical And Electronic Engineering Keywords: GaN; micro-LED; non-radiative recombination; EQE; size effect
Online: 23 April 2023 (04:20:54 CEST)
GaN-based micro-size light-emitting diodes (µLEDs) have a number of appealing and distinctive benefits for display, visible-light communication (VLC), and other novel applications. The smaller size of LEDs affords them the benefits of enhanced current expansion, less self-heating effects, and higher current density bearing capacity. Low external quantum efficiency (EQE) resulting from non-radiative recombination and quantum confined stark effect (QCSE) is the serious barrier for applications of µLEDs. In this work, the reasons for the poor EQE of µLEDs are reviewed, as well as the optimization techniques for improving the EQE of µLEDs.
ARTICLE | doi:10.20944/preprints202304.0711.v1
Subject: Chemistry And Materials Science, Other Keywords: methane dehydroaromatization; zeolite ZSM-5; micro-mesoporous structure; benzene
Online: 21 April 2023 (10:05:20 CEST)
Dehydroaromatization of methane (MDA) is of great interest as a promising process for processing natural and associated petroleum gases, the main component of which is methane. The rapid loss of catalyst activity because of coke formation hinders the introduction of the DHA methane process into industry. Therefore, the aim of the research was to find ways to improve Mo/ZSM-5 catalysts for MDA. The paper presents the results of the synthesis of high-silica zeolites of the ZSM-5 type with a microporous and micro-mesoporous structure, the preparation of Mo/ZSM-5 catalysts based on them, and the study of the physicochemical and catalytic properties of the obtained samples during the non-oxidative conversion of methane into aromatic hydrocarbons. Zeolite catalysts were investigated by IR spectroscopy, X-ray diffraction, TPD-NH3, SEM, HR-TEM, N2-adsorption. It was found that the addition of carbon black at the stage of synthesis of zeolite type ZSM-5 does not lead to structural changes, the obtained samples have a crystallinity equal to 100%. The creation of the micro-mesoporous structure in Mo/ZSM-5 catalysts lead to an increase in their activity and stability in the process of methane dehydroaromatization. The highest conversion of methane is observed on a 4.0%Mo/ZSM-5 catalyst prepared based on of zeolite synthesized using 1.0% carbon black, and is 13.0% in 20 minutes of reaction, while the benzene yield reaches 7.0%. It has been shown by HR-TEM that a more uniform distribution of the active metal component is observed in a zeolite catalyst with a micro-mesoporous structure than in a microporous zeolite.
ARTICLE | doi:10.20944/preprints202209.0392.v1
Subject: Chemistry And Materials Science, Surfaces, Coatings And Films Keywords: Laser induced forward transfer; high entropy alloys; micro-particles
Online: 26 September 2022 (10:32:29 CEST)
Controlled deposition of CoCrFeNiMo0.2 high entropy alloy (HEA) micro-particles was achieved using laser induced forward transfer (LIFT). Ultra-short laser pulses, 230 fs of 515 nm wavelength, were tightly focused into ∼ 2.4 μm focal spots on the ∼50 nm thick plasma-sputtered films of CoCrFeNiMo0.2. The HTA films were transferred onto glass substrates by magnetron sputtering in vacuum (10−8 atm) from the thermal spray coated substrates. The absorption coefficient of CoCrFeNiMo0.2 α ≈ 6 × 105 cm−1 was determined at 600 nm wavelength. The real and imaginary parts of refractive index (n + iκ) of HEA were determined from reflectance and transmittance using nano-films.
ARTICLE | doi:10.20944/preprints202104.0708.v1
Subject: Engineering, Automotive Engineering Keywords: Micro-grid, Rural Electrification, HOMER, Control strategy, Sensitivity analysis
Online: 27 April 2021 (12:27:25 CEST)
Around 14% of the global population does not have access to electricity. About 95% of those are living in rural Sub-Saharan Africa. Often in these regions, diesel generators are the only source of electricity. The operating cost of these diesel generators is high. However, solar and wind energy are available in most of African countries. This study presents the analysis of designing an off-grid hybrid system with a wind turbine, PV, diesel generator, and battery to power a hospital, school, and 200 household village in four locations across Somalia. The research investigated the availability of wind-solar resources in selected locations. Designing of the system and economic-technical calculations were performed using HOMER. The selection of the optimum design was based on the Cost of Electricity and Net Present Cost. The results show that for Kabaal and Ceel Buur, a WT-PV-DG-Battery is the optimal system as the wind resource in these regions is high. For Saakov and Baki, a PV-DG-Battery system proves to be optimum as the wind resource is limited here. The study also evaluated the control strategy and proved that combined dispatch was the most cost-effective for these locations. The study concluded that hybrid systems are more economical than diesel systems.
ARTICLE | doi:10.20944/preprints202104.0563.v1
Subject: Physical Sciences, Acoustics Keywords: Single crystal diamond; micro-water jet guided laser; microchannel
Online: 21 April 2021 (09:05:14 CEST)
Two types of trenches cross-section in conventional vertical and brand new reverse-V-shape have fabricated on SCD substrate by micro-jet water-assist laser, the epitaxial lateral overgrowth technique has applied by microwave plasma chemical vapor deposition system in forming multiple micrometer-size channels. Raman and SEM techniques have applied in analyze both types growth layer characterization. Optical microscope has used to test microchannels hollowness. As a result, with the brand new reverse-V-shape trench, epitaxial lateral overgrowth layer reaches higher SCD surface morphology and crystal quality.
ARTICLE | doi:10.20944/preprints202101.0154.v1
Subject: Environmental And Earth Sciences, Geochemistry And Petrology Keywords: Garnierite, Phase transformation, TGA/DSC, XRD, micro Raman spectroscopy
Online: 8 January 2021 (12:59:34 CET)
This study deals with vibrational and crystallographic aspects of the thermally induced transformation of serpentine-like garnierite into quartz, forsterite, and enstatite occurring at about 620 °C. Powder specimens of garnierite have been annealed in static air between room temperature and 1000 °C. The resulting products from the transformations detected based on thermogravimetric and differential thermal analysis, have been extensively characterized via microRaman spectroscopy, and X-ray diffraction. Our study shows that serpentine-like garnierite consists of a mixture of different mineral species. Furthermore, these garnierites and their composition can provide details based on the mineralogy and the crystalline phases resulting from the thermal treatment.
Subject: Engineering, Automotive Engineering Keywords: microcombs; microwave photonics; micro-ring resonators; RF sideband generation
Online: 10 November 2020 (11:52:59 CET)
We review recent work on narrowband orthogonally polarized optical RF single sideband generators as well as dual-channel equalization, both based on high-Q integrated ring resonators. The devices operate in the optical telecommunications C-band and enable RF operation over a range of either fixed or thermally tuneable frequencies. They operate via TE/TM mode birefringence in the resonator. We achieve a very large dynamic tuning range of over 55 dB for both the optical carrier-to-sideband ratio and the dual-channel RF equalization for both the fixed and tunable devices.
ARTICLE | doi:10.20944/preprints202003.0079.v1
Subject: Engineering, Control And Systems Engineering Keywords: micro segmented genetic algorithm; multicore embedded system; parallel processing
Online: 5 March 2020 (03:23:59 CET)
This paper presents a novel micro-segmented genetic algorithm (μsGA) to identify the best solution for the locomotion of a quadruped robot designed on a rectangular ABS plastic platform. We compare our algorithm with three similar algorithms found in the specialized literature: a standard genetic algorithm (GA), a micro-genetic algorithm (μGA), and a micro artificial immune system (μAIS). The quadruped robot prototype guarantees the same conditions for each test. The platform was developed using 3D printing for the structure and can accommodate the mechanisms, sensors, servomechanisms as actuators. It also has an internal battery and a multicore embedded system (mES) to process and control the robot locomotion. This research proposes a μsGA that segments the individual into specific bytes. μGA techniques are applied to each segment to reduce the processing time; the same benefits as the GA are obtained, while the use of a computer and the high computational resources characteristic of the GA are avoided. This is the reason why some research in robot locomotion is limited to simulation. The results show that the performance of μsGA is better than the three other algorithms (GA, μGA and AIS). The processing time was reduced using a mES architecture that enables parallel processing, meaning that the requirements for resources and memory were reduced. This research solves the problem of continuous locomotion of a quadruped robot, and gives a feasible solution with real performance parameters using a μsGA bio-micro algorithm and a mES architecture.
ARTICLE | doi:10.20944/preprints201812.0186.v1
Subject: Physical Sciences, Applied Physics Keywords: TSV, nanoindentation, FIB, micro-cantilever beam, mixed-mode, fracture
Online: 17 December 2018 (10:01:04 CET)
In-situ nanoindentation experiment has been widely adopted to characterize material behaviors of microelectronic devices. This work introduces the latest developments of nanoindentation experiment in characterizing nonlinear material properties of 3D integrated microelectronic devices with through-silicon-vias (TSVs). The elastic, plastic, and interfacial fracture behavior of the copper via and matrix-via interface have been characterized using small scale specimens prepared with focused-ion-beam (FIB) and nanoindentation experiment. A brittle interfacial fracture was found at the Cu/Si interface under mixed-mode loading with a phase angle ranging from 16.7 to 83.7 degrees. The mixed-mode fracture strengths were extracted using the linear elastic fracture mechanics (LEFM) analysis and a fracture criterion was obtained by fitting the extracted data with the power-law function. The vectorial interfacial strength and toughness were found to be independent with mode-mix.
ARTICLE | doi:10.20944/preprints201807.0133.v1
Subject: Physical Sciences, Optics And Photonics Keywords: microfluidics; micro-injection-moulding; femtosecond laser micromachining; optical manipulation.
Online: 9 July 2018 (11:47:29 CEST)
Micro Injection molding combined with the use of removable inserts is one of the most promising manufacturing process for microfluidic devices, such as Lab-on-a-chip, that have the potential to revolutionize the healthcare and diagnosis system. In this work we have designed, fabricated and tested a compact and disposable plastic optical stretcher. To produce the mould inserts, two micro manufacturing technologies have been used. Micro Electro Discharge machining was used to reproduce the inverse of the capillary tube connection characterized by high aspect ratio. Thanks to the high accuracy of femtosecond laser machining, instead, we manufactured insert with perfectly aligned microfluidic channels and fiber slots, facilitating the final composition of the optical manipulation device. The optical stretcher operation is tested using microbeads and red blood cells solutions. The prototype presented in this work demonstrates the feasibility of this approach that should guarantee a real mass production of ready-to-use- Lab-on-a-chip.
ARTICLE | doi:10.20944/preprints201803.0200.v1
Subject: Chemistry And Materials Science, Surfaces, Coatings And Films Keywords: Plasma Electrolytic Oxidation (PEO); Micro Arc Oxidation (MAO); Titanium
Online: 23 March 2018 (15:16:33 CET)
In the paper, the effect of voltage increasing (from 500 VDC up to 650 VDC) on the structure and chemical composition of porous coating on titanium made by Plasma Electrolytic Oxidation, is presented. In the present paper, phosphates based coatings enriched with calcium, magnesium, zinc and copper in electrolyte based on 1 L of 85% concentrated H3PO4 with additions of Ca(NO3)2·4H2O, and Mg(NO3)2∙6H2O, and Zn(NO3)2∙6H2O, and Cu(NO3)2∙3H2O, are described. The morphology, chemical and phase composition, are evaluated using SEM, EDS, XRD, XPS, GDOES. Based on all the analyses, it was found out that the PEO coatings are porous and enriched with calcium, magnesium, zinc and copper. They consist mainly of the amorphous phase, which is more visible for higher voltages, and it is correlated with the increasing of the total PEO coating thickness (the higher the voltage, the thicker the PEO coating). However, for 650 VDC an amorphous phase and titanium substrate was also recorded with a signal from Ti2P2O7 crystalline, that was not observed for lower voltages. It was also found out that all the obtained coatings may be divided in three sub-layers, i.e. porous, semiporous, and transition one.
ARTICLE | doi:10.20944/preprints201708.0072.v1
Subject: Engineering, Control And Systems Engineering Keywords: seismic events; seismic classification; boost learning; micro seismic detection
Online: 21 August 2017 (10:08:19 CEST)
Various natural disasters such as floods, fires, earthquakes, etc. have affected human life. Detection and classification of large and small earthquakes caused by natural or abnormal events have been always important to Earth scientist. One of the most important research challenges in this field is the lack of an effective method for identifying and categorizing various types of seismic events at less important and important levels. Based on latest achievements of Data Mining international institutions such as Rexer-KDnugget-Gartner and also newest authentic articles, SVM, KNN, C4.5, MLP are from most important and popular and leading classifiers in data world.Therefor in present study, a boost learning system consisting support vector machine algorithms with linear regression, MLP Neural Network ، C4.5 decision tree and KNN near neighborhood have been utilized in a combined form to detect and categorize micro seismic events. In general, the steps involved in the proposed method are: 1) performing artificial seismic tests, 2) data gathering and analysis, 3) conducting preprocessing and separating training and testing samples, 4) generating relevant models with training samples and detecting and categorizing test samples and 5) extracting a cluster with the maximum candidate using boost learning. After simulations, it was observed that the accuracy of proposed boost method to the best answer was about 6.1% higher compare to other methods and the error rate was 0.082% of recalling. Accuracy of detection and classification to the best answer were also improved compare to other methods up to 2.31% and 6.34%, respectively.
ARTICLE | doi:10.20944/preprints201611.0004.v1
Subject: Chemistry And Materials Science, Materials Science And Technology Keywords: thin film nitinol; carotid artery; micro mesh stent; micropatterning
Online: 1 November 2016 (06:54:40 CET)
Stenting is an alternative to endarterectomy for the treatment of carotid artery stenosis. However, stenting is associated with a higher risk of procedural stroke secondary to distal thromboembolism. Hybrid stents with a micromesh layer have been proposed to address this complication. We developed a micropatterned thin film nitinol (M-TFN) covered stent designed to prevent thromboembolism during carotid intervention. This innovation may obviate the need or work synergistically with embolic protection devices. The proposed double layered stent is low-profile, thromboresistant, and covered with a M-TFN that can be fabricated with fenestrations of varying geometries and sizes. The M-TFN was created in multiple geometries, dimensions, and porosities by sputter deposition. The efficiency of various M-TFN to capture embolic particles was evaluated in different atherosclerotic carotid stenotic conditions through in vitro tests. The covered stent prevented emboli dislodgement in the range of 70-96% during 30min duration tests. In vitro vascular cell growth study results showed that endothelial cell elongation, alignment and growth behaviour silhouettes significantly enhance specifically on the diamond-shape M-TFN with the dimensions of 145µm×20µm and a porosity of 32%. Future studies will require in-vivo testing. Our results demonstrate that M-TFN has a promising potential for carotid artery stenting.
ARTICLE | doi:10.20944/preprints202307.0463.v1
Subject: Biology And Life Sciences, Biology And Biotechnology Keywords: lung disease; cystic fibrosis; pulmonary emphysema; image analysis; artificial intelligence; X-ray tomographic microscopy; micro-computed X-ray tomography / micro-CT; stereology.
Online: 7 July 2023 (07:12:13 CEST)
(1) Background: Stereological estimations significantly contributed to our anatomical and physiological understanding of the lung by providing an average distribution of measured parameters over the entire lung parenchyma. However, most structural lung diseases show a very inhomogeneous pattern of alterations. (2) Methods: We developed a novel protocol for the analysis of all pulmonary airspaces. Our pipeline starts with high-resolution synchrotron radiation-based X-ray tomographic microscopy (SRXTM) and consists of (i) image segmentation with the combination of the free machine-learning tool Ilastik and ImageJ and (ii) calculation of the airspace diameter distribution of an entire lung using a diameter map function. To evaluate the new pipeline, lungs from adult mice with cystic fibrosis (CF)-like lung disease (ENaC-transgenic mice) or mice with elastase-induced emphysema were compared to healthy controls. (3) Results: We were able to show the distribution of airspace diameters throughout the entire lung, as well as separately for the conducting airways and the gas-exchange area. In the pathobiological context, we observed an irregular widening of parenchymal airspaces in mice with CF-like lung disease and elastase-induced emphysema. Comparable results were obtained when analyzing lungs imaged with μCT, suggesting that our pipeline is applicable to different kinds of imaging modalities. (4) Conclusions: We conclude that the airspace diameter map is well suited for a detailed analysis of unevenly distributed structural alterations in chronic muco-obstructive lung diseases such as cystic fibrosis and COPD.
ARTICLE | doi:10.20944/preprints202108.0025.v1
Subject: Business, Economics And Management, Marketing Keywords: Cross border electroniceletronic commerce(CBEC); Export Marketing Strategy(EMS); Marketing Mix; Micro, Small and Medium sized enterprise(MSMEs); Aid for Trade; Micro Entrepreneur
Online: 2 August 2021 (12:07:48 CEST)
Cross-border e-commerce is an opportunity for micro, small and medium sized enterprise (MSMEs) in developing countries. Based on a resource-based approach, this research studied how to support resource lacking enterprises with export marketing strategy. It dealt with actual business cases of Mongolian entrepreneurs trying to export Mongolian products to Korean market. Multiple source data including interviews, internal documents, and group discussions, were matched with theories to come up with strategies and validated by supporting organizations in Mongolia and Korea. The research suggests that MSMEs should rely on third party digital platforms rather than setting up their own. For product strtategy of the marketing mix, sellecting competitive product categories and supporting them adjusting to foreign markets and quality assurance is needed. For price strategy, loccally high priced products should use a price penetration strategy with a lower price compared to competing foreign products. For place strategy, supporting organizations should partner with exporters for collective delivery. For promotion strategy, they need to support the capacity of MSMEs enabling them to use digital marketing tools effectivly. These strategies were validated and adopted by supporting organizations in Monglia and Korea.
ARTICLE | doi:10.20944/preprints202311.1290.v1
Subject: Biology And Life Sciences, Biophysics Keywords: fraxicon; micro-optics; RGB; SZ2080™ resist; direct-laser-writing
Online: 21 November 2023 (10:42:14 CET)
Emerging applications of optical technologies are driving the development of miniaturised light sources, which in turn require the fabrication of matching micro-optical elements with sub-1 mm cross sections and high optical quality. This is particularly challenging for spatially-constrained biomedical applications where reduced dimensionality is required, such as endoscopy, optogenetics, or optical implants. Planarisation of a lens by the Fresnel lens approach was adapted for a conical lens (axicon) and was made by direct femtosecond 780 nm/100 fs laser writing in SZ2080™polymer with photo-initiator. Optical characterisation of the positive and negative fraxicons is presented. Numerical modeling of fraxicon optical performance under illumination by incoherent and spatially extended light sources is compared with the ideal case of plane wave illumination. Considering the potential for rapid replication in soft polymers and resists, this approach holds great promise for the most demanding technological applications.
ARTICLE | doi:10.20944/preprints202309.2140.v1
Subject: Engineering, Civil Engineering Keywords: production workshop; environmental vibration; micro-vibration; road traffic; precision instruments
Online: 30 September 2023 (08:47:27 CEST)
Road traffic transportation has flourished in the process of urbanization by its advantages, but it also produces harmful environmental vibrations. The vibration problem is especially significant for production workshops with precision instruments. A field measurement was conducted to analyze the source characteristics and propagation laws of traffic-induced vibrations. Off the northern side of an urban highway lies a microelectronics workshop. When a large truck passes by, both the vibration responses on the ground and in the workshop considerably increase. Greater vibration is produced in the vertical direction than in the X and Y axes. The predominant frequency band of the vibration response caused by road traffic vehicles is lower than 20 Hz. The vertical vibration responses of the first and second floors in the workshop greatly exceed the VC-C limit because of the high daily traffic flow. Attribute to the excitation of the operation of the manufacturing equipment on the second floor, the vertical vibration level of the second floor is essentially higher than that of the first floor. Therefore, it is impossible to disregard the micro-vibration in the workplace produced by the manufacturing machinery as well as the ex-citement of the road traffic. The measured data can be used to test potential numerical models for forecasting vibrations caused by traffic on roads as well as to guide vibration assessment work throughout the planning and design stages of roads.
ARTICLE | doi:10.20944/preprints202309.1440.v1
Subject: Engineering, Aerospace Engineering Keywords: Micro gas turbine, fuel supply nozzle, combustion chamber, fuel distribution.
Online: 21 September 2023 (08:53:30 CEST)
The present distribution examines the effects of nozzle diameter, inlet mass rate, and channel geometry on the fuel distribution in annular combustion chambers of micro gas turbines, taking into account the importance of more uniform fuel distribution in the nozzles connected to the fuel supply channels. A comparison has been made between the numerically calculated pressure drop between the inlet and outlet of the fuel supply nozzle and the experimental value obtained. All fuel supply nozzles with a diameter of 500 micrometers are considered for the micro gas turbine. A more uniform distribution results in better combustion and higher efficiency. A geometrical change in the design of the fuel supply nozzle improved the uniformity of the flow distribution without increasing the pressure drop.
ARTICLE | doi:10.20944/preprints202308.1501.v1
Subject: Engineering, Civil Engineering Keywords: strengthening; micro-reinforced concrete; ferrocement; RC beams; flexure; numerical simulation
Online: 22 August 2023 (07:27:06 CEST)
The practical necessity of strengthening of reinforced concrete structure elements requires a choice of a method which would provide cost-effectiveness, simplicity of construction and durability of the chosen solution. One of the ways is strengthening using the material belonging to the group of micro-reinforced concretes called ferrocement. The paper presents the comparative analysis of some of the results of RC beams exposed mainly to flexure, strengthened with ferrocement elements (strips) applied by gluing on the on the tensed side of RC beams. The results are obtained using the experimental, analytical and numerical research on the adequate models. Strengthening of the beams was performed in the form of four types of ferrocement strips (four different strip widths and four different numbers of wire mesh layers). The numerical non-linear analysis using finite elements method (FEM) was employed, with the introduction of the corresponding characteristics of constitutive material obtained by the experiments on the test specimens. The analytical researches were performed using known analytical calculation methods in order to formulate the model for the calculation of the ultimate and serviceability limit states of the strengthened cross-section. The results presented in the paper, through their comparative compatibility, confirmed the applicability of this strengthening method.
COMMUNICATION | doi:10.20944/preprints202308.1124.v1
Subject: Physical Sciences, Optics And Photonics Keywords: respiratory carbon dioxide; absorption theory; micro-nano fiber; optical sensor
Online: 16 August 2023 (08:54:07 CEST)
In the field of clinical medicine, the real-time monitoring of carbon dioxide gas exhaled by the human body is of great significance. At present, the detection devices in the market are mainly detected by sucking a small amount of gas in the nasal cavity to the detection device, and there are some problems such as too long sampling tubes, easy blockage or distortion, and abnormal gas dispersion. In this paper, a micro-nano optical fiber sensor that can directly detect the concentration of end-tidal carbon dioxide is proposed. The measurement is achieved by using the principle of high evanescent field absorption, and the operating band is 2.004 μm. The sensor uses micro-nano optical fiber as the sensing area, and then detects the presence of carbon dioxide gas exhaled by human body through optical power attenuation. The function of micro-nano fiber is to realize the transmission of signal light and also serve as the absorption medium of the gas to be measured. In addition, the variation of light power also reflects the respiratory cycle of the human body. The sensor can realize rapid real-time response to carbon dioxide gas detection, with small size, low cost, and easy to replace. It has great application potential in clinical scenarios such as Gastrointestinal Endoscopes that require real-time monitoring of human respiration.
ARTICLE | doi:10.20944/preprints202308.0850.v1
Subject: Computer Science And Mathematics, Computer Vision And Graphics Keywords: Image recognition; Micro AR marker; Camera parameter control; Iterative recognition
Online: 11 August 2023 (02:53:04 CEST)
This paper presents a novel dynamic camera parameter control method for position and posture estimation of highly miniaturized AR markers (micro AR markers) using a low cost general camera. The proposed method performs iterative calculation of the marker’s position and posture to converge them to specified accuracy with dynamically updating the camera’s zoom, focus and other parameter values based on the detected marker’s depth distances. For a 10 mm square micro AR marker, the proposed system demonstrated recognition accuracy of better than ±1.0% for depth distance and 2.5∘ for posture angle with a maximum recognition range of 1.0 m. In addition, the iterative calculation time was at most 0.7 seconds in an initial detection of the marker. These experimental results suggest that the proposed method and system can be applied to a robotic precise handling of small objects with low cost.
REVIEW | doi:10.20944/preprints202306.2187.v1
Subject: Biology And Life Sciences, Plant Sciences Keywords: Eucalyptus; tissue culture; F1 hybrids; clonal propagation; micro-propagation; germplasm.
Online: 30 June 2023 (10:09:13 CEST)
The genus Eucalyptus is a globally captivated source of hardwood and is well known for its medicinal uses. The hybrid and wild species of Eucalyptus are widely used as exotic plantations due to their renowned potential of adapting to various systems and sites, furthermore, making the species the most extensively propagated. Despite unquestionable progression in biotechnological and tissue culture approaches, the productivity of plantations is still limited often due to the low efficiency of clonal propagation from cuttings. The obtained F1 hybrids yield high biomass and High-quality low-cost raw material for large-scale production, however, the development of hybrid, clonal multiplication, proliferation, and post-developmental studies are still major concerns. This riveting review describes the problems concerned with in-vitro and clonal propagation of Eucalypt plantation; recent advances in biotechnological and tissue culture practices for massive and rapid micro-propagation of Eucalyptus; as well, highlights the Eucalypt germplasm preservation techniques.
ARTICLE | doi:10.20944/preprints202306.2018.v1
Subject: Engineering, Mechanical Engineering Keywords: Energy harvesting; micro-channel flow; CFD; piezoelectric phenomenon; bluff body.
Online: 28 June 2023 (11:37:13 CEST)
A micro energy harvesting device proposed in the literature, is numerically studied. It consists of two bluff bodies in a micro-channel and a flexible diaphragm at its upper wall. Vortex shedding behind bodies induces pressure fluctuation causing vibration of the diaphragm that converts me-chanical energy to electrical by means of a piezoelectric membrane. Research on enhancing vortex shedding is justified due to the low power output of the device. Amplitude and frequency of un-steady pressure fluctuation on the diaphragm center are numerically predicted. Vortex shedding severity is mainly assessed in terms of pressure amplitude. The CFD model set-up is described in detail and appropriate metrics to assess energy harvesting potential are defined. Several cases are simulated to study the effect of inlet Reynolds number and channel blockage ratio on the prospec-tive performance of the device. Furthermore, the critical blockage ratio leading to vortex shedding suppression is sought. Higher inlet velocity for a constant blockage ratio is found to enhance vor-tex shedding and pressure drop. Great blockage ratio values, but lower than the critical one, seem to provide great pressure amplitudes in the expense of moderate pressure drop. There is evidence that the field is fruitful for research and relevant directions are provided.
REVIEW | doi:10.20944/preprints202203.0273.v1
Subject: Medicine And Pharmacology, Urology And Nephrology Keywords: prostate cancer; ultrasonography; biopsy; micro-ultrasound; elastography; contrast-enhanced ultrasound
Online: 21 March 2022 (04:26:46 CET)
The purpose of this review is to present the current role of ultrasound-based techniques in the diagnostic pathway of prostate cancer (PCa). With overdiagnosis and overtreatment of a clinically insignificant PCa over the past years, multiparametric magnetic resonance imaging (mpMRI) became recommended for every patient suspected of PCa before performing a biopsy. It enabled targeted sampling of the suspicious prostate regions, improving the accuracy of the traditional systematic biopsy. However, mpMRI is associated with high costs, relatively low availability, long and separate procedure or exposure to the contrast agent. The novel ultrasound modalities such as shear wave elastography (SWE), contrast-enhanced ultrasound (CEUS) or high frequency micro-ultrasound (MicroUS) may be capable of maintaining the performance of mpMRI without its limitations. Moreover, the real-time lesion visualization during biopsy would significantly simplify the diagnostic process. Another value of these new techniques is the ability to enhance the performance of mpMRI by creating the image fusion of multiple modalities. Such models might be further analyzed by artificial intelligence to mark the regions of interest for investigators and help to decide about the biopsy indications. The dynamic development and promising results of new ultrasound-based techniques should encourage researchers to thoroughly study their utilization in prostate imaging.
Subject: Chemistry And Materials Science, Biomaterials Keywords: Biodegradable labeling; Decomposition; Fibre; Micro plastic; PVAL; PHA; Shotgun wad
Online: 10 May 2021 (15:35:36 CEST)
Parts of shotgun cartridges are a significant source of plastic litter in the marine environment. Empty cartridge shells may not be picked up by the hunter who fired them, and plastic wads that serve to separate the propellant from the shot load, are lost down-range when a shot is fired. Such litter items constitute a cosmetic and aesthetic problem on coastlines and may cause harm to marine animals and in the later stages of decomposition break down into harmful micro plastic particles. There exists no reliable estimate of the global exposure of marine ecosystems to this plastic source. However, in some countries it has been subject to closer examination, including for example, Denmark where the annual contribution of plastic wads into marine systems was estimated to 600,000 pieces (c2 tonnes), and the accumulated density of washed-up items (both wads and shells) was 3.7 items per 100 m coastline. Increasing awareness of this problem has caused scientists, hunters’ communities and governments to suggest altered practice including transition to the use of biodegradable cartridge components, first and foremost wads as this item is invariable lost during hunting. Several manufacturers provide shotgun cartridges containing biodegradable wads based on different types of materials, including fibers and various types of plastics, for example PVAL (poly(vinyl alcohol)) and PHA (polyhydroxyalkanoate). In this paper, we review the most recent literature on the amounts and related environmental hazards of plastic dispersed from hunting ammunition into marine ecosystems. We summarize the market availability of shotgun cartridges with biodegradable wads and discuss chemical, technical, economical and legal aspects of a transition to the use of such products.
BRIEF REPORT | doi:10.20944/preprints202101.0093.v1
Subject: Medicine And Pharmacology, Immunology And Allergy Keywords: ST-elevation myocardial infarction; Thrombus; Thrombus aspiration; Micro-CT; ceramides
Online: 5 January 2021 (13:43:37 CET)
ST-elevation myocardial infarction (STEMI) remains one of the leading causes of morbidity and mortality worldwide. The identification of novel metabolic and imaging biomarkers could unveil key pathophysiological mechanisms at the molecular level and promote personalized care in patients with acute coronary syndromes. We studied 38 patients with STEMI who underwent primary percutaneous coronary intervention and thrombus aspiration. We sought to correlate serum ceramide levels with micro-CT quantified aspirated thrombus volume and relevant angiographic outcomes, including modified TIMI thrombus grade and pre- or post-procedural TIMI flow. Higher ceramide C16:0 levels were significantly, but weakly correlated with larger aspirated thrombus volume (Spearman r=0.326, p=0.046), larger intracoronary thrombus burden (Nagelkerke R2=0.236, p=0.030) and worse pre- and post-procedural TIMI flow (Nagelkerke R2=0.210; p=0.049 and Nagelkerke R2=0.277; p=0.039, respectively). Ceramides C24:0 and C24:1 were also significantly associated with larger intracoronary thrombus burden (Nagelkerke R2=0.311; p=0.008 and Nagelkerke R2=0.423; p=0.001, respectively). In conclusion, serum ceramide levels (mainly C16:0 and C24:1) were higher among patients with larger intracoronary and aspirated thrombus burden. This suggests that quantification of serum ceramides might improve risk-stratification of patients with STEMI and facilitate a more individualized approach in everyday clinical practice.
ARTICLE | doi:10.20944/preprints202011.0188.v1
Subject: Biology And Life Sciences, Anatomy And Physiology Keywords: Plant biomechanics; turgor pressure; micro-compression; AFM; Arabidopsis thaliana; differentiation
Online: 4 November 2020 (10:42:19 CET)
Individual plant cells are the building blocks for all plantae and artificially constructed plant biomaterials, like biocomposites. Secondary cell walls (SCWs) are a key component for mediating mechanical strength and stiffness in both living vascular plants and biocomposite materials. In this paper, we study the structure and biomechanics of cultured plant cells during the cellular developmental stages associated with SCW formation. We use a model culture system that induces transdifferentiation of Arabidopsis thaliana cells to xylem vessel elements, upon treatment with dexamethasone (DEX). We group the transdifferentiation process into three distinct stages, based on morphological observations of the cell walls. The first stage includes cells with only a primary cell wall (PCW), the second covers cells that have formed a SCW, and the third stage includes cells with a ruptured tonoplast and partially or fully degraded PCW. We adopt a multi-scale approach to study the mechanical properties of cells in these three stages. We perform large-scale indentations with a micro-compression system and nanoscale indentations through atomic force microscopy (AFM), in three different osmotic conditions. We introduce a spring-based model to deconvolve the competing stiffness contributions from turgor pressure, PCW, SCW and cytoplasm in the stiffness of differentiating cells. Prior to triggering differentiation, cells in hypotonic pressure conditions are significantly stiffer than cells in isotonic or hypertonic conditions, highlighting the dominant role of turgor pressure. Plasmolyzed cells with a SCW reach similar levels of stiffness as cells with maximum turgor pressure. The stiffness of the PCW in all of these conditions is lower than the stiffness of the fully-formed SCW. Our results provide the first experimental characterization of the mechanics of SCW formation at single cell level.
ARTICLE | doi:10.20944/preprints202006.0047.v1
Subject: Engineering, Mechanical Engineering Keywords: horn design; ultrasonic welding; nonwoven fabric; micro-structure; tensile strength
Online: 5 June 2020 (14:01:01 CEST)
Nonwoven fabrics have been widely used in textile manufacturing industry as a sheet or web structure because of soft, water-repellent, recycle, ecological and resilient functions. Ultrasonic welding method has been applied for bonding nonwoven fabrics due to clean, fast and reliable approach. In this work, the ultrasonic stepped horn is designed to generate uniform amplitudes on the working surface by using finite element analysis (FEA) simulation. Chromium carbon steels are utilized to produce ultrasonic horns due to high wear resistant and hardness. Isotactic polypropylene nonwoven fabrics fabricated by spunbond process were bonded by continuous ultrasonic sewing machine. Ultrasonic horn with 70 mm in diameter working at 20 kHz, polypropylene (PP) nonwoven density of 80 gsm and various design of welding joints were applied. A typical image in the case of number one was investigated by the scanning electron microscope (SEM) images of inter-facial micro-structure. However, welding joints of totally eight roller patterns was test the tensile strength of the ultrasonic welding joints on PP nonwoven fabrics. The tensile strength of the welding joints is proportional to the area ratio between the welding area and cycling area. The results showed that the melted zone without welding defects such as crack or blowhole can be seen. Furthermore, the tensile strength of welding joints in eight cases of roller patterns (No.1-No.8) was described in details. The ultrasonic welding joints with brick structures give higher tensile strength while the solid line in the pattern gave less strength.
ARTICLE | doi:10.20944/preprints202002.0320.v1
Subject: Chemistry And Materials Science, Materials Science And Technology 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.
Subject: Environmental And Earth Sciences, Geophysics And Geology Keywords: viscoelasticity; anelasticity; creep function; forced-oscillation methods; micro creep methods
Online: 13 October 2019 (16:55:05 CEST)
There is an important complementarity between experimental methods for the study of high-temperature viscoelasticity in the time and frequency domains, that has not always been fully exploited. Here we show that parallel processing of forced-oscillation data and microcreep records, involving consistent use of either Andrade or extended Burgers creep-function models, yields a robust composite modulus-dissipation dataset spanning a broader range of periods than either technique alone. In fitting this dataset, the alternative Andrade and extended Burgers models differ in their partitioning of strain between the anelastic and viscous contributions. The extended Burgers model is preferred because it involves a finite range of anelastic relaxation times, and accordingly a well-defined anelastic relaxation strength. The new strategy offers the prospect of better constraining the transition between transient and steady-state creep, or equivalently, between anelastic and viscous behaviour.
ARTICLE | doi:10.20944/preprints201910.0052.v1
Subject: Physical Sciences, Optics And Photonics Keywords: 3D laser lithography; laser induced damage threshold; micro-optics; photonics
Online: 4 October 2019 (11:56:36 CEST)
Direct laser writing based on non-linear 3D nanolithography (also known as 3D laser lithography, 3DLL) is a powerful technology to manufacture polymeric micro-optical components. However, practical applications of these elements are limited due to the lack of knowledge of their optical resilience and durability. In this work, we employ 3DLL for the fabrication of bulk (i.e. fully filled) and woodpile structures out of different photopolymers. We then characterize them using S-on-1 laser induced damage threshold (LIDT) measurements. In this way, quantitative data of LIDT values can be collected. Furthermore, this method permits to gather damage morphologies. The results presented in this work demonstrate that LIDT values depend on the material and the geometry of the structure. Bulk non-photosensitized hybrid organic-inorganic photopolymer SZ2080 structures are found to be the most resilient with a damage threshold being of 169±15 mJ/cm2.
ARTICLE | doi:10.20944/preprints201710.0115.v1
Subject: Engineering, Electrical And Electronic Engineering Keywords: fall detection; vital signs monitoring; ultra-wideband radar; micro-Doppler
Online: 17 October 2017 (11:45:13 CEST)
Continuous in-home monitoring of older adults living alone aims to improve their quality of life and independence, by detecting early signs of illness and functional decline or emergency conditions. To meet requirements for technology acceptance by seniors (unobtrusiveness, non-intrusiveness, privacy-preservation), this study presents and discusses a new smart sensor system for the detection of abnormalities during daily activities, based on ultra-wideband radar providing rich, not privacy-sensitive, information useful for sensing both cardiorespiratory and body movements, regardless of ambient lighting conditions and physical obstructions (through-wall sensing). The radar sensing is a very promising technology, enabling the measurement of vital signs and body movements at a distance, and thus meeting both requirements of unobtrusiveness and accuracy. In particular, impulse-radio ultra-wideband radar has attracted considerable attention in recent years thanks to many properties that make it useful for assisted living purposes. The proposed sensing system, evaluated in meaningful assisted living scenarios by involving 30 participants, exhibited the ability to detect vital signs, to discriminate among dangerous situations and activities of daily living, and to accommodate individual physical characteristics and habits. The reported results show that vital signs can be detected also while carrying out daily activities or after a fall event (post-fall phase), with accuracy varying according to the level of movements, reaching up to 95% and 91% in detecting respiration and heart rates, respectively. Similarly, good results were achieved in fall detection by using the micro-motion signature and unsupervised learning, with sensitivity and specificity greater than 97% and 90%, respectively.
ARTICLE | doi:10.20944/preprints202311.1486.v1
Subject: Engineering, Metallurgy And Metallurgical Engineering Keywords: ingot; macro- and micro-inhomogeneity; slab; rolled sheet metal; defectl; structure
Online: 23 November 2023 (07:12:54 CET)
The results of a study of the processes of formation of macro- and micro-inhomogeneity of ingots and rolled sheets are presented. To study the nature and sources of surface defects in rolled sheets, a comparative method of structural-concentration analysis of metal at the end-to-end metallurgical process of ingot - slab - sheet metal has been developed, based on the metallographic method of studying the structure and qualitative analysis of non-metallic inclusions. The research results showed that the quality of the surface of rolled sheets is determined mainly by the physical heterogeneity of the crust zone of the ingots, and the internal defects of thin rolled sheets largely depend on the contamination of the metal with non-metallic inclusions and off-axis segregation. A mechanism for transforming defects in the casting cortical zone into surface and internal defects in rolled sheets is proposed.
REVIEW | doi:10.20944/preprints202311.1092.v1
Subject: Biology And Life Sciences, Aquatic Science Keywords: Micro-plastics; routes of MPs; eco-toxicology; aquatic organisms; human exposure
Online: 17 November 2023 (02:27:47 CET)
Micro-plastics (MPs) become significantly important to society since their commercial manufacture began in the 1950s because of their low production costs, stability, light weight, and adaptability. Plastic was produced in 400 million tons worldwide in 2020, compared to 1.5 million tons just 60 years earlier. Scientists predict that by 2050, plastic production would increase to 33 billion tons. MPs are a rising scientific and societal issue in the environment as a new type of contaminant that is widely disseminated in aquatic ecosystems and organisms. Aquatic species that come into contact with MPs for an extended period of time experience ecotoxicity, which includes oxidative stress, genotoxicity, neurotoxicity, and reproductive issues. In aquatic environments, MPs not only transport chemicals within animals but also serve as mediators for chemicals or other contaminants. As a result of co-exposure of MPs and chemical contaminants, various toxicity incidences involving aquatic organisms have been reported. The final exposure of MPs occurs in humans through biomagnification of aquatic edible products. This study presents an important overview of the literature on MP ingestion by aquatic biota. It covers topics such as the present scenario of plastic pollution worldwide, the pathways that MPs take to reach humans and aquatic species, the eco-toxicological impacts of MPs on aquatic species, the relation between MPs and other environmental pollution and the ensuing effects on aquatic organisms, and the MP pollution status in Bangladesh.
ARTICLE | doi:10.20944/preprints202310.0853.v1
Subject: Biology And Life Sciences, Biology And Biotechnology Keywords: Azerbaijani chestnut; nutrient medium; hormones; micro-shoots in vitro; root induction
Online: 13 October 2023 (07:55:20 CEST)
Castanea sativa Mill., an indigenous species of the mountainous Gabala region of Azerbaijan, where its local variety is now facing the danger of extinction. The preservation of this variety of European chestnut requires the development of effective strategies for reliable in vitro regeneration systems as an alternative to traditional methods, which has become the main objective of this study. In solving this problem, the generally accepted technique of micro-multiplication of axillary shoots was mainly used. First, a phased sterilization of was carried out using liquid soap, Previkur fungicide and mercury (II) chloride. DKW (Driver and Kuniyuki Walnut) nutrient medium was used for germination of explants, into which growth stimulants BAP (Benzilamunapurine), IBA (Indole - 3 butyric acid), IAA (Indole Acetic acid), NAA (Naphthalene Acetic Acid) and GA3 (Gibberelic acid) were introduced in various combinations and quantities. The test of the above-mentioned sterilization model revealed significant shortcomings in terms of the acceptability of the results obtained (16-77%). It was also found that the germination of explants takes 14 days and it is better to conduct it in a DKW environment containing hormones BAP (0.6 mg), IBA (0.1 mg) and GA3 (0.1 mg) / 1 L DKW. A mixture of BAP (0.1mg) + IBA (0.35 mg) is more suitable for the reproduction of grown explants + GA3 (0.2 mg) / 1 l DKW (the result is 3 new micro-plants for each explant), and for good root formation (it takes 30 days) – a mixture of IBA 1.0 mg + NAA 0.5 mg + IAA 0.5 mg / l L DKW. After the shoots have acquired a certain length (at least 1.5 cm), it is required to transfer them for 22 days to a DKW medium containing IBA (1 mg), IAA (0.5 mg) and NAA(0.5 mg) / l L DKW so that the root splitting process begins and ends.
REVIEW | doi:10.20944/preprints202306.1737.v1
Subject: Environmental And Earth Sciences, Environmental Science Keywords: CO2 storage; Pore scale; CT scanning; Complex pore structures; Micro-flow
Online: 26 June 2023 (05:08:27 CEST)
To prevent CO2 leakage and ensure the safety of long-term CO2 storage, it is essential to investigate the flow mechanism of CO2 in complex pore structures at the pore scale. This study focuses on reviewing the experimental, theoretical, and numerical simulation studies on the microscopic flow of CO2 in complex pore structures during the last decade. For example, advanced imaging techniques, such as X-ray computed tomography (CT) and nuclear magnetic resonance (NMR), are used to reconstruct the complex pore structures of rocks. Mathematical methods, such as Darcy's law, Young–Laplace’s law, and the Navier-Stokes equation, are used to describe the microscopic flow of CO2. Numerical methods, such as the lattice Boltzmann method (LBM) and pore network (PN) model, are used for numerical simulation. The application of these experimental and theoretical models and numerical simulation studies is discussed, considering the effect of complex pore structures. Finally, future research is suggested to focus on: (1) Conducting real-time CT scanning experiments of CO2 displacement combined with the developed real-time CT scanning clamping device to realize real-time visualization and provide quantitative description of the flow behavior of CO2 in complex pore structures; (2) The effect of pore structures change on the CO2 flow mechanism caused by the chemical reaction between CO2 and the pore surface, the flow theory of CO2 considering wettability and damage theory in a complex pore structures; (3) The flow mechanism of multi-phase CO2 in complex pore structures; (4) The flow mechanism of CO2 in the pore structures at multiscale and the scale upgrade from microscopic to mesoscopic to macroscopic. Generally, this study focuses on reviewing the research progress of CO2 flow mechanisms in complex pore structures at the pore scale and affords an overview of potential advanced developments to enhance the current understanding of CO2 microscopic flow mechanisms.
ARTICLE | doi:10.20944/preprints202306.1722.v1
Subject: Chemistry And Materials Science, Ceramics And Composites Keywords: Zirconia; CAD/CAM; ultrasonic scaling; SEM; surface micro topography; microbial biofilm;
Online: 25 June 2023 (07:13:11 CEST)
Objective: The purpose of this study was to evaluate the surface texture and biofilm adhesion of veneered or CAD/CAM milled zirconia (partially stabilized with yttrium) after professional oral hygiene procedures. Samples (4x4 mm, thickness 2 mm; n = 72) were separated from zirconia blanks (3Y-TZP-LA). One group was veenired with ceramics and the other group of samples was CAD/CAM milled. Each group had 2 subgroups: polished and glazed. The samples were subjected to simulated strokes of professional brushing using abrasive paste and ultrasonic scaling. Parameters of surface micromorphology and receptivity to biofilm were calculated before and after simulating the given methods of professional maintenance of oral hygiene. The characteristics of zirconia surface were evaluated by scanning electron microscopy (SEM). Microbial bacterial/fungal species (Staphylococcus aureus, Streptococcus sanguinis and Candida albicans) were used and cultured on the respective sterilized zirconia surfaces. The amount of biofilm formation on zirconia surface was quantified by colony forming unit (CFU) counts. Results: SEM analysis showed the greatest change in surface microtopography after the use of ultrasonic scaling, in glazed zirconia samples. Less formation of colonies on the surface CAD/CAM milled zirconia restorations was observed. Conclusion: Routine methods of professional maintenance of oral hygiene can damage the surface of glazed zirconia restorations.
ARTICLE | doi:10.20944/preprints202306.0245.v1
Subject: Environmental And Earth Sciences, Geophysics And Geology Keywords: fracture-induced electromagnetic radiation (FEMR); FEMR field measurements; micro-fracturing, earthquakes
Online: 5 June 2023 (05:35:03 CEST)
This paper deals with the quantitative analysis of measured fracture-induced electromagnetic radiation (FEMR) in the vicinity of the Dead Sea Transform using the Angel-M1 instrument, which enables the recording of FEMR signals in a 3D manner. Results show both the possibility of estimating the sizes of micro-fractures that are the sources of the radiation, and of assessing the direction of their location to the measuring device and the range of magnitude Mw of the impending "events" (EQ's) associated with the present FEMR measurements. Moreover, the relation between the measured FEMR activity (the number of FEMR hits per unit time) and the FEMR event magnitudes shows consistency with the Gutenberg-Richter relationship for the region. Such measurements could therefore constitute a preliminary 'field reinforcement' towards an EMR valid method for a real earthquake forecast, which would provide much earlier warnings than the seismic ones. Obviously, the present observed FEMR measurements can only be used as an assessment of the stress concentration and micro-fracturing in the region since they relate to the very initial nucleation phase of a "virtual" (extremely low Richter scale value) earthquake, but they do provide the necessary feasibility test for a prediction method since all lab-measured FEMR features were confirmed also in the field.
ARTICLE | doi:10.20944/preprints202305.2110.v1
Subject: Engineering, Control And Systems Engineering Keywords: Constant Pressure Regulation; Micro droplet Digital PCR; Fluorescence Detection; Quantitative Detection
Online: 30 May 2023 (10:31:02 CEST)
The device and method in accordance with the constant pressure regulation of micro droplet PCR in microfluidic chips are developed to explore the optimization way for the micro droplet movement, fragmentation, and bubble generation in microfluidic chips in existing digital PCR technology. In the developed device, an air source device is adopted to regulate the pressure in the chip, such that micro droplet generation and PCR amplification without bubbles can be achieved. In 3 min, the sample in 20ul will be distributed into nearly 50,000 water-in-oil droplets exhibiting a diameter of about 87μm, and the micro droplet will be subjected to a close arrangement in the chip without air bubbles. The device and chip are adopted to quantitatively detect the human gene . As indicated by the experimental results, a good linear relationship exists between detection signal and DNA concentration ranging from 101~ 105 copies /μL (R2=0.999). The micro droplet PCR devices based on constant pressure regulation chips exhibit a wide variety of advantages (e.g., achieving high pollution resistance, micro droplet fragmentation and integration avoidance, reducing human interference, and standardizing results). Thus, micro droplet PCR devices based on constant pressure regulation chips have promising applications in nucleic acid quantification.
ARTICLE | doi:10.20944/preprints202305.2006.v1
Subject: Social Sciences, Education Keywords: AI Literacy; AI Expertise; Subject-linked; Pre-service Teacher; Micro-teaching
Online: 29 May 2023 (10:51:09 CEST)
Artificial intelligence, a key technological tool in the era of the 4th Industrial Revolution, is being actively applied to education beyond industry, economy, and culture. In the future society, understanding and using artificial intelligence technology will be considered an essential skill for everyone, and the professionalism of AI education for pre-service teachers nurturing future talents is also important. This study verifies the effectiveness of pre-service teachers after undergoing a 15-week extension program consisting of AI Literacy Education (10 weeks), AI-Linked Subjet Education (3 weeks), and Micro-teaching (2 weeks) which was designed to enhance the AI education professionalism of pre-service teachers. The AI Literacy Education section consisted of understanding AI, AI ethics, and basic programming, and the education was conducted through both experience and practice. After that, the pre-service teachers analyzed the curriculum of the 5th and 6th grades of an elementary school, and developed a subject-related education program using AI tools in three stages. Using the developed program, micro-teaching classes were conducted twice. The study results are as follows. First, there was a change in the positive perception of AI (p<.05). Second, the understanding of AI educational technology tools was improved and the recognition of the usefulness of developing a curriculum-related program was expanded. Third, the importance of teacher competency development was learned through the micro-teaching, and the students' understanding of the learning process was expanded.
ARTICLE | doi:10.20944/preprints202305.0084.v1
Subject: Social Sciences, Urban Studies And Planning Keywords: Dark Store; Micro-Fulfillment Center; Case Study; Online Shopping, COVID-19
Online: 2 May 2023 (10:58:28 CEST)
This study examines the negative impacts of dark stores on the urban environment from three perspectives: land use, transportation, and streetscape. It is conducted on B-Mart, a representative dark store in South Korea. First, in terms of land use, we find that dark stores that function as logistics facilities conflict with the surrounding land use. Second, by analyzing the location of dark stores and the hourly traffic volume of delivery vehicles, we find that the impact on the surrounding transportation infrastructure and pedestrian traffic is not as significant as previously claimed. However, during the transportation and loading process of the dark store, several problems such as traffic violations, illegal parking, and illegal loading were observed, posing a risk to nearby vehicles and pedestrians. Third, in terms of streetscapes, the location of dark stores on the ground floor of buildings can harm streetscapes. The current urban planning system in South Korea does not clearly define the status and function of dark stores, making it unclear how to manage them. Therefore, it is necessary to clarify their legal definition and introduce urban planning and design guidelines that are consistent with their appropriate location and appearance.
ARTICLE | doi:10.20944/preprints202304.1016.v1
Subject: Physical Sciences, Applied Physics Keywords: micro scale pipe viscometer; dynamic viscosity; traceable calibration; laminar flow regime
Online: 27 April 2023 (03:42:04 CEST)
Calibration of flow devices is important in several areas of pharmaceutical, flow chemistry and microfluidic applications where dosage of process liquids or accurate measurement of the flow rate is important. The process-oriented liquid itself might influence the performance of the flow device and the simultaneous determination of the dynamic viscosity under flow conditions might be a valuable information for the process parameters. To offer the simultaneous calibration of the dynamic viscosity of the process-oriented liquid at the corresponding flowrate, METAS has built a pipe viscometer for the traceable in-line measurement of the dynamic viscosity in the current flow facilities for low flow rates from 1 L/min to 150 mL/min and pressure drops up to 10 bar. The traceability of all the measuring quantities as well as the geometrical dimensions of the micro tube guarantee the traceability of the pipe viscometer to SI units. The most challenging part is the traceable determination of the inner diameter of the micro tube. This can be achieved by measuring the pressure drop as a function of flow rate with the pipe viscometer and applying the law of Hagen-Poiseuille with a traceable dynamic viscosity of a reference liquid (water) or perform the measurements with the micro-CT at METAS, which determines the inner diameter by x-ray diffraction. The validation of the stated measurement uncertainty of the pipe viscometer has been performed by means of calibration of the dynamic viscosity of several reference liquids with traceable density and kinematic viscosity. The setup of the facility, the traceability as well as the uncertainty calculation of the pipe viscometer for the in-line measurement of the dynamic viscosity are discussed in this paper.
ARTICLE | doi:10.20944/preprints202211.0488.v1
Subject: Computer Science And Mathematics, Artificial Intelligence And Machine Learning Keywords: Capsule network; differential features; deep learning; micro-expression recognition; spatiotemporal features
Online: 28 November 2022 (03:12:12 CET)
Micro-expression (ME) is one of the key psychological stress reactions. It is a modest, spontaneous facial mechanism. ME has significant applicability in a variety of psychologically-related sectors because to its precision and unpredictability with regard to psychological manifestations. Nevertheless, the current Micro-expression recognition (MER) algorithms have poor accuracy and a limited quantity of ME data, and this study issue has not been thoroughly investigated. Therefore, we present an approach for deep learning based on a Spatio-temporal capsule network (STCP-Net). STCP-Net has four components: a jitter reduction module, a differential feature extraction module, an STCP module, and a fully linked layer. The first two modules are aimed to extract diversifying differential features more precisely and to limit the influence of head jitter. The STCP module is used to extract Spatio-temporal features layer by layer, taking the temporal and geographical connection between features into account. This research runs sufficient trials using the Leave One Subject Out (LOSO) methodology for cross-validation using the CASMEII dataset. The conclusion and analysis demonstrate that the algorithm is innovative and efficient.
REVIEW | doi:10.20944/preprints202207.0353.v1
Subject: Biology And Life Sciences, Cell And Developmental Biology Keywords: cancer stem cells; competing endogenous RNAs; ceRNA; lncRNA; micro-RNA; miRNA
Online: 25 July 2022 (06:18:30 CEST)
Cancer stem cells (CSCs) are one of the cell types that account for cancer heterogeneity. They arrest in the G0 phase and generate non-CSC progeny by self-renewing and pluripotency activity, resulting in tumor recurrence, metastasis, and chemoresistance. One CSC can stimulate tumor relapse and can re-grow a metastatic tumor. So, CSC is a promising target for eradicating tumors, and developing an anti-CSC method has become a top priority in cancer therapy. In recent years competing endogenous RNA (ceRNA) have emerged as an important class of post-transcriptional regulators that affect gene expression via competition for microRNA (miRNA) binding. Furthermore, aberrant ceRNA expression is associated with tumor progression. To overcome therapeutic resistance due to CSCs, we need to improve our existing understanding of the mechanisms by which ceRNAs are implicated in CSC-related relapse. Thus, this review was designed in order to discuss the role of ceRNAs in CSCs function. We reviewed the role of ceRNAs in acquiring CSCs characteristics in the form of different pathways including Rho GTPase/F-actin_ Yes-associated protein (YAP)/transcriptional co-activator with PDZ-binding motif (TAZ) (Hippo), Wnt/β-catenin pathway, transforming growth factor (TGF)-b–urothelial carcinoma-associated 1 (UCA1)–Slug pathway, etc. Finally, considering the comprehensive impacts of the ceRNA network on different pathways, a treatment strategy driving the ceRNA network might be effective. Targeting ceRNAs may open the path for new cancer therapeutic targets and can be used in clinical research.
Subject: Biology And Life Sciences, Biochemistry And Molecular Biology Keywords: Wheat; yield; triple-super-phosphate; sulfur; nitrogen; micro-dosing, precision-farming
Online: 21 July 2021 (08:22:32 CEST)
This research was specifically aimed at assessing the influence of sulfur in triple-super phosphate (TSP) on wheat yield. From the results, wheat showed response to sulfur (S) from gypsum (in 67%); and nitrogen (N) from urea in about 100% (of 24 sites). Based on this N was found to be the most limiting element to wheat production followed by sulfur, and then by phosphorus. TSP is tested to contain agronomically up to 2-6% by weight of S. However, wheat didn’t show response to S impurity supplied in the form of TSP. Though, not statistically significant, it is observed that there have always been yield increments by certain percent due to S from TSP in 8 out of 10 target sites, which is depicted in the increasing trends of yield response curves. From this it is learnt that, the benefits of the accidental/incidental application of such high analysis fertilizers can be many-folds in the quality attributes of wheat, if the soils of such investigation at the same time would contain significant amount of organic matter (OM). Indeed, such analysis would be vital in varietal specific nutrient requirement studies in precision-farming and/or in categorizing soils into fertility gradients and fertilizer recommendation domains.
ARTICLE | doi:10.20944/preprints202107.0234.v1
Subject: Engineering, Automotive Engineering Keywords: Pervious pavement; Polyurethane binder; Micro-CT analysis; Mechanical properties; Microscopic characteristics
Online: 12 July 2021 (08:01:39 CEST)
Conventional pervious pavement materials (PPM) consist of cement and aggregate materials and are known for poor durability due to their brittle behavior. Herein, we fabricated polymeric PPMs from durable and abundant polyurethane (PU) to enhance the durability of the material and undertook mechanical and microscopic characterizations. PU-based PPM samples with varying aggregate sizes were produced and the compressive strength and water permeability of each were examined. The pore and tortuosity characteristics of the specimens were analyzed using X-ray micro-computed tomography (micro-CT). Through the micro-CT analysis, the morphological characteristics of the internal structures of PPM were identified and the correlations between the pore size distribution, connectivity, and tortuosity within the specimen were quantitatively analyzed. The microstructures derived from micro-CT were generated as a finite element model and the stress distribution generated inside was numerically determined.
ARTICLE | doi:10.20944/preprints202102.0199.v1
Subject: Physical Sciences, Acoustics Keywords: Microfluidics; Micro-Jet; Sub-millisecond mixing; Simulation; Sample delivery for XFEL
Online: 8 February 2021 (12:12:47 CET)
Microfluidic devices which integrate both rapid mixing and liquid jetting for sample delivery are an emerging solution for studying molecular dynamics via X-ray diffraction. Here we use finite element modelling to investigate the efficiency and time-resolution achievable using microfluidic mixers within the parameter range required for producing stable liquid jets. Three-dimensional simulations, validated by experimental data, are used to determine the velocity and concentration distribution within these devices. The results show that by adopting a serpentine geometry, it is possible to induce chaotic mixing, which effectively reduces the time required to achieve a homogeneous mixture for sample delivery. Further, we investigate the effect of flow rate and the mixer microchannel size on the mixing efficiency and minimum time required for complete mixing of the two solutions whilst maintaining a stable jet. In general, we find that the smaller the cross-sectional area of the mixer microchannel, the shorter the time needed to achieve homogeneous mixing for a given flow rate. The results of these simulations will form the basis for optimised designs enabling the study of molecular dynamics occurring on millisecond timescales using integrated mix-and-inject microfluidic devices.
Subject: Physical Sciences, Optics And Photonics Keywords: Kerr micro-combs; microwave photonics; signal channelization; integrated optical frequency combs
Online: 12 November 2020 (08:53:59 CET)
We review recent work on broadband RF channelizers based on integrated optical frequency Kerr micro-combs combined with passive micro-ring resonator filters, with microcombs having channel spacings of 200GHz and 49GHz. This approach to realizing RF channelizers offers reduced complexity, size, and potential cost for a wide range of applications to microwave signal detection.
ARTICLE | doi:10.20944/preprints202010.0459.v1
Subject: Computer Science And Mathematics, Algebra And Number Theory Keywords: Simulated annealing; Unit commitment; Micro grid; Smart Area; fuzzy number; Optimization
Online: 22 October 2020 (10:46:56 CEST)
The optimization problem of two or more special-purpose functions of the energy system is subjected to an analysis. Based on experience of our research and general knowledge of partial solutions of energy system optimization at the level of control of production and power energy supply by energy companies in the Czech Republic, a special-purpose (cost) function has been defined. By analysing the special-purpose function, penalty and limitations have been defined. Using the fuzzy logic, a set of suitable solutions for the special-purpose function is accepted. An optimum of the special-purpose function is looked for using the simulated annealing method. The history of electricity consumption is sorted by day and by hour, representing the multidimensional data. When using the cluster analysis, type daytime diagrams of consumption are defined. Type daytime diagrams form prototypes of identified clusters. The so-called self-organizing neural network with Kohonen map attached is used to perform the cluster analysis. The result of our research is presented by an experiment.
ARTICLE | doi:10.20944/preprints202009.0447.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: nano- and micro-sized TiO2; photocatalytic efficiency; photoelectrochemical characterization; environmental remediation
Online: 19 September 2020 (05:11:43 CEST)
The size of TiO2 (either nanometric or micrometric) can significantly affect both its photocatalytic and photoelectrochemical properties, thus altering the photooxidation of organic pollutants in air or water. The purpose of this work is to give an account of the photoelectrochemical and photocatalytic features of some nano- and micro-sized TiO2 commercial powders towards a model reaction, the photooxidation of acetone. Cyclic voltammograms (CV) of TiO2 particulated electrodes under UV illumination experiments were carried out in either saturated O2 or N2 solutions for a direct correlation with the photocatalytic process. In addition, the effect of different reaction conditions on the photocatalytic efficiency under UV light in both aqueous and gaseous phases was also investigated. CV curves with the addition of acetone under UV light showed a negative shift of the photocurrent onset, confirming the efficient transfer of photoproduced reactive oxygen species (ROSs), e.g., hydroxyl radicals, or holes to acetone molecules. The photocatalytic experiments showed that the two nano-sized samples exhibit the best photocatalytic performance. The different photoactivity of the micro-sized samples is probably attributed to their morphological differences, affecting both the amount and distribution of free ROSs involved in the photooxidation reaction.
CASE REPORT | doi:10.20944/preprints202006.0195.v1
Subject: Medicine And Pharmacology, Neuroscience And Neurology Keywords: Hypereosinophilic Syndrome; PDGFR-A; Balínt Syndrome; micro-emboli; chronic eosinophilic leukaemia
Online: 15 June 2020 (13:22:06 CEST)
Balínt Syndrome is an acquired disorder manifesting in the inability to recognize several objects at once (simultagnosia), inaccurate visually guided limb movements despite intact motor function (optic ataxia) and the inability to make accurate voluntary saccades to visual targets despite demonstrating unrestricted range of eye movements (ocular motor apraxia). Here we report the first case of a patient presenting with Balínt Syndrome caused by a platelet-derived growth factor receptor A mutation (PDGFRA)-induced Hypereosinophilic Syndrome (HES).
ARTICLE | doi:10.20944/preprints201905.0267.v1
Subject: Engineering, Electrical And Electronic Engineering Keywords: Fully-autonomous; AC micro-grid; AC/DC/AC converter; Seamless switching
Online: 22 May 2019 (08:44:26 CEST)
This paper proposes a novel micro-grid structure, which can operate fully-autonomously with inherent seamless switching. It can operate independently in both grid-connected and islanded mode as a self-governed entity without relying on the utility grid. An AC/DC/AC converter is employed as the interface between the micro-grid and the utility grid, which enables the two entities to have different voltages in grid-connected mode. Seamless switching between operation modes can be achieved naturally. The micro-grid is regulated to exchange predefined amount of power with the utility grid in grid-connected mode. This will benefit the power dispatching algorithm of the power system. The predefined power is estimated based on power forecasting of local renewable generations and loads with consideration of the Sate of Charge (SOC) of the battery, and is updated and broadcasted every certain period. A small scale AC micro-grid with a rotating generator, battery storage and solar arrays etc. is built for investigation. Matlab/Simulink results are provided to validate the robustness and flexibility of proposed micro-grid and its operation strategy.
ARTICLE | doi:10.20944/preprints202011.0074.v4
Subject: Biology And Life Sciences, Immunology And Microbiology Keywords: Hybrid phosphite; X-Ray crystal structure; FTIR; Thermal behavior; Biological activities; Antimi-crobial; micro-organisms
Online: 22 November 2021 (08:43:49 CET)
A novel hybrid cobalt phosphite, (H2DAB)[Co(H2PO3)4]·2H2O, has been synthesized by using slow evaporation method, in the presence of cobalt nitrate, phosphorous acid and 1,4- dia-minobutane (DAB= 1,4- diaminobutane) as a structure-directing agent. Single crystal X-ray diffraction analysis showed that the compound crystallizes in the P-1(n.2) triclinic space group, with the following unit cell parameters (Å, °) a = 5.4814 (3), b = 7.5515 (4), c = 10.8548 (6), α = 88.001 (4), β = 88.707 (5), γ = 85.126 (5), and V= 447.33 (4) Å3. The crystal structure was built up from cor-ner-sharing [CoO6] octahedra, forming chains parallel to , which are interconnected by H2PO3 pseudo-tetrahedral units. The deprotonated cations, residing between the parallel chains, interacted with the inorganic moiety via hydrogen bonds leading thus to the formation of the 3D crystal structure. The Fourier transform infrared spectrum showed characteristic bands corresponding to the phosphite group and the organic amine. The thermal behavior of the compound consisted mainly of the loss of its organic moiety and the water molecules. The biological tests exhibited significant activity against Candida albicans and Escherichia coli strains in all used concentrations, while less inhibitory activity was pronounced against Staphylococcus epidermidis and Saccharomyces cerevisiae, and in the case of multi-cellular organisms, no activity against the nematode model Steinernema feltiae was detected.