(1) Background: this study deals with design of an automated laboratory facility based on a servo-hydraulic testing machine for estimating parameters of mechanical hysteresis loops by means of the ...digital image correlation (DIC) method. (2) Methods: the paper presents a description of the testing facility, describes the grounds for calculating the elastic modulus, the offset yield strength (OYS) and the parameters of the mechanical hysteresis loops by the DIC method. (3) Results: the developed hardware-software facility was tested by studying the fatigue process in neat polyimide (PI) under various amplitude tension-tension loadings. It was found that the damage accumulation was accompanied by the decrease in the loop areas, while failure occurred when it reduced by at least ~5 kJ/m3. (4) Conclusions: it was shown that lowering the loop area along with changing the secant modulus value makes it possible to estimate the level of the scattered damage accumulation (mainly at the stresses above the OYS level). It was revealed that fractography data, namely the pattern and sizes of the fatigue crack initiation and propagation zones, did not correlate well with the dependences of the parameters of the hysteresis loops.
Abstract
The paper proposes a method and its realization for stabilizing the characteristics of a multichannel position-sensitive spectrometer. The device uses a new design of the semiconductor strip ...detector, which allows a simultaneous injection of stable in time electric charges on all strips. This solution enables the electronics to track changes in the conversion characteristics of all electronic channels including detectors strips, and correct them during the spectrometer operation. In addition, the proposed detector design makes it possible to control the signal propagation along the strips, thus providing an on-line check of the integrity of strips metallization and the quality of their connection with the readout electronics.
The investigation is focused on the defects in silicon p+-n-n + detectors irradiated with the 53.4 MeV 40Ar ions, which generate a nonuniform defect distribution including a heavily damaged region ...inside the Bragg peak. The dependences of the bulk generation current and of the capacitance on bias voltage and the spectra of radiation-induced defects demonstrate new features: a step in the current rise, a region with a practically constant capacitance, and abnormal dependence of the peak amplitudes of vacancy-related defects on fluence. The changes of the DLTS spectra are assigned to the influence of silicon properties inside the Bragg peak region acting as a highly compensated insulating layer.
This study introduces a novel method for detecting the post-COVID state using ECG data. By leveraging a convolutional neural network, we identify "cardiospikes" present in the ECG data of individuals ...who have experienced a COVID-19 infection. With a test sample, we achieve an 87 percent accuracy in detecting these cardiospikes. Importantly, our research demonstrates that these observed cardiospikes are not artifacts of hardware-software signal distortions, but rather possess an inherent nature, indicating their potential as markers for COVID-specific modes of heart rhythm regulation. Additionally, we conduct blood parameter measurements on recovered COVID-19 patients and construct corresponding profiles. These findings contribute to the field of remote screening using mobile devices and heart rate telemetry for diagnosing and monitoring COVID-19.
A method and unit for dynamic control of conversion characteristics of spectrometric paths of multichannel charged particle registration systems based on specialized microchip with a large degree of ...integration similar to IDE1140 in structure is proposed. The conversion characteristics are controlled during operation of the device by auto-adjusting the offset and gain of the scaling amplifier. The proposed method allows to use the entire dynamic range of the analog-to-digital converter and adjust the temperature drift for each channel at the hardware level during operation of the device.
The present work focuses on the structural, thermo-mechanical and electrical properties of La2–xCaxNiO4 + δ with different calcium content (x=0–0.4) and the electrochemical performance of the ...electrodes on their base in contact with a Ce0.8Sm0.2O1.9 electrolyte. It was shown that the introduction of even a small amount of calcium (x=0.1) stabilized the crystal structure in the tetragonal syngony across the whole temperature range 25–800°C. Dilatometric study of the compact samples in the entire concentration range of Ca showed no phase transitions up to 800°C. The total electrical conductivity, measured by a dc four-probe technique, increased with an increase in calcium content. However, electrochemical activity of the La2–xCaxNiO4 + δ – based electrodes, contrarily, drastically decreased. The polarization resistance Rη, derived from the impedance spectroscopy data, increased from 0.18Ω·cm2 (x=0) to 1.24Ω·cm2 (x=0.3) at 800°C. The coefficients of oxygen surface exchange (k⁎) and oxygen tracer diffusion (D⁎) calculated from the oxygen isotope exchange data for La2NiO4+δ were considerably higher than those for La1.7Ca0.3NiO4+δ (4.54∙10−7cm∙s−1 and 3.02·10−8cm2∙s−1 (x=0); 2.91∙10−8cm∙s−1 and 5.82·10−10cm2∙s−1 (x=0.3) at 800°C, respectively). It was found that for La1.7Ca0.3NiO4+δ the rate-determining stage of oxygen surface exchange is incorporation of oxygen, while for La2NiO4+δ it is oxygen dissociative adsorption.
•La2-xCaxNiO4+δ was synthesized by the solid state reaction method•The electrical conductivity increases with an increase in Ca content•The electrochemical activity of La2-xCaxNiO4+δ-based cathodes decreases•Oxygen surface exchange and tracer diffusion coefficients decreases with Ca content•Lanthanum nickelate doped and undoped by Ca show different rate-determing stages
The fatigue properties of neat polyimide and the “polyimide + 10 wt.% milled carbon fibers + 10 wt.% polytetrafluoroethylene” composite were investigated under various cyclic loading conditions. In ...contrast to most of the reported studies, constructing of hysteresis loops was performed through the strain assessment using the non-contact 2D Digital Image Correlation method. The accumulation of cyclic damage was analyzed by calculating parameters of mechanical hysteresis loops. They were: (i) the energy losses (hysteresis loop area), (ii) the dynamic modulus (proportional to the compliance/stiffness of the material) and (iii) the damping capacity (calculated through the dissipated and total mechanical energies). On average, the reduction in energy losses reached 10–18% at the onset of fracture, whereas the modulus variation did not exceed 2.5% of the nominal value. The energy losses decreased from 20 down to 18 J/m3 (10%) for the composite, whereas they reduced from 30 down to 25 J/m3 (17%) for neat PI in the low-cycle fatigue mode. For high-cycle fatigue, energy losses decreased from 10 to 9 J/m3 (10%) and from 17 to 14 J/m3 (18%) for neat PI and composite, respectively. For this reason, the changes of the energy losses due to hysteresis are of prospects for the characterization of both neat PI and the reinforced PI-based composites.
The article analyses the possible impact of economy robotisation on the unemployment rate. Structurally, the article consists of four parts. The first part describes the threats to employment, ...associated with robotisation. The second part is devoted to the analysis of the dynamics of the unemployment rate for countries — leaders of the economy robotisation. The results of the study allow us to conclude that at the current stage the robotisation of the economies of the countries leading at this process is accompanied by the creation of new jobs and a shortage of labour resources. The third part of the article explains the results of the analysis. It is substantiated that the growth in the number of jobs in developed countries as a result of robotisation has been achieved by reducing the number of jobs in developing countries. This process is the first wave of the results of economy robotisation. The fourth part of the article describes the spread of the second wave of economy robotisation. The characteristic of its possible negative impact on the economy of developed countries is given, the reasons for this influence are described, possible options for further development of the situation are analyzed.
The serotonin 5-HT
receptor is one of the most abundant and widely distributed brain serotonin (5-HT) receptors that play a major role in the modulation of emotions and behavior. The 5-HT
receptor ...gene (
) is under the control of transcription factor Freud-1 (also known as
). Here, using adeno-associated virus (AAV) constructs in vivo, we investigated effects of a
in the hippocampus of C57BL/6J mice on behavior, the brain 5-HT system, and brain-derived neurotrophic factor (BDNF). AAV particles carrying the pAAV_H1-2_shRNA-Freud-1_Syn_EGFP plasmid encoding a short-hairpin RNA targeting mouse
mRNA had an antidepressant effect in the forced swim test 5 weeks after virus injection. The knockdown impaired spatiotemporal memory as assessed in the Morris water maze. pAAV_H1-2_shRNA-Freud-1_Syn_EGFP decreased
mRNA and protein levels. Furthermore, the
upregulated 5-HT and its metabolite 5-hydroxyindoleacetic acid but not their ratio. The
failed to increase mRNA and protein levels of
but diminished a 5-HT
receptor functional response. Meanwhile, the
reduced
mRNA expression and CREB phosphorylation and upregulated
mRNA. The knockdown enhanced the expression of a BDNF precursor (proBDNF protein), which is known to play a crucial part in neuroplasticity. Our data indicate that transcription factor
is implicated in the pathogenesis of depressive disorders not only via the 5-HT
receptor and transcription factor CREB but also through an influence on BDNF.
Oxygen surface exchange kinetics and diffusion have been studied by the isotope exchange method with gas phase equilibration using a static circulation experimental rig in the temperature range of ...600-800 °C and oxygen pressure range of 0.13-2.5 kPa. A novel model which takes into account distributions of the dissociative adsorption and incorporation rates has been developed. The rates of the elementary stages have been calculated. The rate-determining stages for a La
2
NiO
4±
δ
polycrystalline specimen have been discussed. The diffusion activation energies calculated using the gas phase equilibration method (1.4 eV) differ significantly from those calculated using isotope exchange depth profiling (0.5-0.8 eV), which was attributed to the influence of different oxygen diffusion pathways.
Oxygen surface exchange kinetics and diffusion have been studied by the isotope exchange method with gas phase equilibration using a static circulation experimental rig in the temperature range of 600-800 °C and oxygen pressure range of 0.13-2.5 kPa.
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