The most well-known methods for diagnosing solar modules are considered; it is shown that the described diagnostic methods do not allow identifying defects that develop over a long time. The ...operation of photovoltaic cells under non-uniform illumination is analyzed. It has been shown that the operation of solar modules under non-uniform illumination can lead to thermal damage to semiconductor materials and deterioration in the module energy characteristics due to the fact that some of the photovoltaic cells located at reduced energy illumination become a parasitic load for more illuminated photovoltaic cells included in such module. An analytical equation has been obtained in explicit form for the full current-voltage characteristic of a photovoltaic cell using the Lambert W-function in forward and reverse bias, which makes it possible to study the connections of photovoltaic cells as a part of a solar module under non-uniform energy illumination, where the reverse branch of the current-voltage characteristic is important. The analytical equation makes it possible to predict the behavior of photovoltaic cells and solar modules composed of them under various operating modes, including identifying the degradation process. An electronic measuring device has been developed and manufactured that makes it possible to measure the light and dark current-voltage characteristics of a photovoltaic cell, including the negative branch, in automatic mode. This reduces measurement time and the influence of external experimental conditions when obtaining the current-voltage characteristics of the photovoltaic cell. A method for constructing solar modules from photovoltaic cells under conditions of their operation under non-uniform lighting has been proposed. As a result of such selection, reliability is increased and an increase in the efficiency of the solar module in shading mode, composed of series-connected photovoltaic cells selected in this way, is achieved.
We report an experimental study of broadband sum-frequency generation of a nonselective
Q
-switched CO laser (pulse duration, ~0.3 μs; repetition rate, ~90 Hz) in ZnGeP
2
crystals with and without an ...antireflective interference coating. The uncoated crystal surface is found to be optically damaged at a laser radiation intensity of 0.033 GW/cm
2
. Under the same conditions, no damage to the antireflection-coated surface of the crystal is observed. The maximum efficiency of broadband sum-frequency generation of the CO laser in the antireflection-coated sample is 4.8% and turns out to be two times higher than in the uncoated sample. The spectral characteristics of the radiation at sum frequencies do not change in using antireflection-coated and uncoated samples.
The monitoring principle of the solar module conditions as a part of photovoltaic power plants is considered. In the existing monitoring technology, information about the electrical parameters of ...individual solar modules being the part of linear chains gets lost. If a fault is not detected and corrected in a timely manner, energy production is reduced and the risk of local hot spot formation in the photovoltaic converters that make up the solar modules increases. The technical task is to equip the solar module with a diagnostic unit simple in design and capable to detect a violation of the normal operating mode automatically. A system for diagnosing solar modules in a remote mode has been developed, which determines the presence of current in the bypass diode circuit being the violation of the normal operation mode of the module. The current sensor (based on the Hall effect) detects the presence of current in the bypass diode circuit (i.e., current flowing bypassing a group of solar cells located at reduced illumination). This installation makes it possible to detect electric current in the bypass diode circuit, where it should not exist during normal operation, which is a consequence of the fact that the solar module group of solar cells shunted by this bypass diode has stopped generating electric current, due to the fact that the illumination of one or several PV cells in this group became lower than the PV illumination in other groups of the solar module. The diagnostic unit operates as part of a wireless sensor network. Each wireless diagnostic unit has a unique address, thanks to which it is possible to determine the coordinates of a module that is operating intermittently. The technical result is to simplify the design, increase the reliability of the solar module, and reduce the time for localizing the “problem module”.
Recently published studies suggest thatterahertz pulsed imaging will have applications inmedicine and biology, but there iscurrently very little information about the opticalproperties of human ...tissue at terahertzfrequencies. Such information would be useful forpredicting the feasibility of proposedapplications, optimising acquisition protocols,providing information about variability ofhealthy tissue and supplying data for studies of theinteraction mechanisms. Research ethicscommittee approval was obtained, andmeasurements made from samples of freshlyexcised human tissue, using a broadbandterahertz pulsed imaging system comprisingfrequencies approximately 0.5 to 2.5 THz.Refractive index and linear absorptioncoefficient were found. Reproducibility wasdetermined using blood from one volunteer,which was drawn and measured on consecutivedays. Skin, adipose tissue, striatedmuscle, vein and nerve were measured (to date, from oneindividual). Water had a higher refractiveindex (2.04 ± 0.07) than any tissue.The linear absorption coefficient was higher formuscle than adipose tissue, as expectedfrom the higher hydration of muscle. As these samples camefrom a single subject, there is currentlyinsufficient statistical power to draw firmconclusions, but results suggest that in vivo clinical imaging will be feasible in certainapplications.
The general theory of relativity was first formulated as geometrodynamics, i.e., as a theory where the space–time metric is a dynamic quantity. But it is currently obvious that from the standpoint of ...particle physics, gravity is simply the theory of a massless spin
-2
particle. We show that many important properties of gravity itself and of its possible extensions and modifications can be understood starting from the simple physical requirement that the number of physical degrees of freedom is correct and there are no nonphysical degrees of freedom
.
The article presents the results of a pilot survey
1
devoted to the behavior of young people in the public places of residential districts in St. Petersburg. These places are viewed as the spaces of ...potential interaction among the various urban publics in which the processes of self-identification and the establishment of social differences take place, and also where the foundations for the formation of solidarities are laid down.
Ferritin is a universal protein complex responsible for iron perception in almost all living organisms and has applications from fundamental biophysics to drug delivery and structure-based immunogen ...design. Different platforms based on ferritin share similar technological challenges limiting their development - control of self-assembling processes of ferritin itself as well as ferritin-based chimeric recombinant protein complexes. In our research, we studied self-assembly processes of ferritin-based protein complexes under different expression conditions. We fused a ferritin subunit with a SMT3 protein tag, a homolog of human Small Ubiquitin-like Modifier (SUMO-tag), which was taken to destabilize ferritin 3-fold channel contacts and increase ferritin-SUMO subunits solubility. We first obtained the octameric protein complex of ferritin-SUMO (8xFer-SUMO) and studied its structural organization by small-angle X-ray scattering (SAXS). Obtained SAXS data correspond well with the high-resolution models predicted by AlphaFold and CORAL software of an octameric assembly around the 4-fold channel of ferritin without formation of 3-fold channels. Interestingly, three copies of 8xFer-SUMO do not assemble into 24-meric globules. Thus, we first obtained and structurally characterized ferritin-based self-assembling oligomers in a deadlock state. Deadlock oligomeric states of ferritin extend the known scheme of its self-assembly process, being new potential tools for a number of applications. Finally, our results might open new directions for various biotechnological platforms utilizing ferritin-based tools.
We performed morphofunctional analysis of cultured rabbit buccal epithelial cells in the primary culture, during passaging, and upon interaction with collagen substrates. Three different ...morphological types were identified. It was demonstrated that precursors of rabbit buccal epithelium were characterized by high proliferative activity, retain their biological properties throughout long-term culturing, and adhere to various collagen substrates.
The aim of the research was to study the state of the bronchial mucosa epi-thelium in relation to the severity of clinical manifestations in severe uncon-trolled asthma depending on the pattern of ...inflammation and the presence of cold airway hyperresponsiveness.
In 48 patients with severe uncontrolled asthma, there were assessed asthma symptoms, clinical signs of cold airway hyperre-sponsiveness, and lung function; the samples of slides were analyzed in the cytological examination of the sputum; the degree of damage to epithelial cells and granulocytes was estimated using the total cell destruction index (CDI).
According to the analysis of sputum cytograms, the patients were divided into two groups: group I (22 patients) included persons with eosin-ophilic inflammation pattern (31.0±3.1% of eosinophils and 22.0±2.2% of neutrophils), group II (26 patients) was with mixed inflammation pattern (7.2±1.4 and 71.8±4.2%, respectively). The patients of group II had lower disease control according to Asthma Control Test (ACT; 12.1±0.7 and 17.8±0.2 points, respectively; р<0.05), a greater frequency of exacerbations (4.1±0.3 and 3.2±0.2 per year, respectively; р<0.05), greater incidence of clinical signs of cold airway hyperresponsiveness (79 and 19%, respectively; χ2=14.18; р<0.001); lower lung function (midexpiratory flow rate MEF25-75 was 14.6±1.6 and 20.7±1.9%, respectively; р<0.05); they received a higher dose of the combined medications of inhaled glucocorticosteroid in controller anti-inflammatory therapy (salmeterol/fluticasone at a dose of 705.3±19.7 and 650.7±14.8 µg/day for fluticasone propionate; р<0.05) In patients of group II the correlations of epithelial CDI with neutrophil CDI (r=0.61; p<0.01) and eosinophil CDI (r=0.48; p<0.05), as well as correlation of ACT with neutrophil CDI (r=-0.71; p<0.01) and eosinophil CDI (r=-0.53; p<0.05) were found.
The degree of destruction of the epithelium and granulocytes in the inflammatory patterns has diagnostic relevance for the assessment of the severity of the disease, clinical manifestations of the airway response to the cold trigger, and the inertia of achieving control in patients with severe un-controlled asthma.
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