Due to the low cost, nontoxicity, chemical stability and high efficiency of TiO2, it is unquestionably one of the most considered materials in environmental treatment. In this systematic review, we reveal the outstanding potential of oxygen vacancy in photocatalysis, and discuss the contemporary advancement in the photocatalytic activities, productivity, preparation methods and oxygen vacancy of the TiO2 nano-based composite photocatalyst for environmental treatment and energy as well as wastewater treatment. This exposé is anticipated to enlighten researchers and engineers on the specific management and assessment of the environment, which warrants prospective research into developing appropriate mechanisms for energy, wastewater treatment and environmental purification.The TiO 2 nano-based composite photocatalyst is best known for application in solving the recent issues related to energy and environmental purification.The TiO For modest and cost-effective treatment, additional efficient photocatalysts are highly preferred to parallel the extensively used TiO2. The field of water photocatalysis has experienced tremendous growth, following the discovery of photocatalytic H2 production in the 1980s and the photocatalysis and hydrophilicity of TiO2 films by Honda and Fujishima in the 1990s, and other scientists in the early 70s.67–72 Further studies have revealed that industrial applications in this area have been wonderfully accomplished since the early 90s based on the outcomes from these basic research efforts.6,105–107Currently, research efforts have shifted toward semiconductor photocatalysts such as TiO2O by photogenerated holes, the second involves the reduction of an electron acceptor  by photoexcited electrons; these reactions lead to the production of a hydroxyl and superoxide radical anion, respectively.68,69,97,103,104 In the area of photocatalysis, energy saving green tools are the ultimate, in accordance with photoinduced water cleavage to TiO2 electrodes, a phenomenon discovered by the pioneers in the field.1 It is believed that TiO2 photocatalysis is currently one of the best in the recent research in nanoscience and nanotechnology.Photocatalysis is the speeding up of oxidation and reduction reactions, brought about through the activation of a catalyst consisting of a semiconductor either alone or in combination with metal/organic/organometallic promoters, through light absorption and the subsequent charge and/or energy transfer, which can lead to the transformation of a pollutant. It must be noted that during the photocatalytic reaction, two actions must occur simultaneously in order for the successful production of reactive oxidizing species to occur. Typically, the first involves the oxidation of dissociatively adsorbed H2 photocatalysts in water and environmental purification and management in the past few decades. In solving the recent issues related to energy and environmental purification, heterogeneous metal oxide semiconductor photocatalysts are best known. Due to the low-cost, nontoxicity, chemical stability and high efficiency of TiO2, it is unquestionably one of the most considered materials by researchers in the field of photocatalysis. However, the low quantum efficiency of TiO2 in photocatalytic mechanisms and the ineffective use of visible light for H2 harvesting, which mainly comes from its high recombination rate of photogenerated electron–hole pairs and wide band gap, have become problematic in prospective applications.9,73,74There have been many successful reports on the potential applications of TiO2. These strategies can be summarized as morphological modifications, such as increased surface area and porosity, or as chemical modifications, by the incorporation of additional components into the TiO2 structure. Three basic strategies have been adopted for the structural modification, namely, doping with metallic/non-metallic elements or co-doping of metallic and non-metallic elements,9,108–110 modification through the introduction of defects such as oxygen vacancies and Ti3+ in the band gap,111,112 and surface modification by treatment techniques.113–115 Currently, the attention is centered on oxygen vacancies, which occur naturally in oxides, due to the vital role they play in the physical characteristics of materials; oxygen vacancies may be positive or negative. Oxygen vacancies occur when the number of oxygens in a particular compound is less than what it is supposed to be to make a perfect crystal lattice. This results in materials such as ZnFe2O4, where ZnO and Fe2O3 are chosen as starting compounds.Scientists in the field have adopted various approaches for the improvement of the photocatalytic efficacy of TiO2 composites for energy, wastewater and environmental treatment in order to design future implementations to solve environmental problems. This is attractive for ecological uses such as water purification, purified biofuel production and wastewater treatment. Researchers in this field are doing their best in one way or the other to use these composites to solve the environmental crises. This discussion tackles the use of oxygen vacancies of TiO2 nano-based composites in photocatalysis to solve environmental concerns such as water treatment and related issues.This review is centered on the ability and effectiveness of the prospective applications of oxygen vacancies and photocatalysis using TiO2.2.1.x have been suggested by scientists in recent years for the treatment of urban pollution; thus leading to the use of photocatalytic self-cleaning and depolluting constituents. The photocatalytic properties of a thin layer of TiO2 entrenched in paints or concrete or placed at the surface of the particle influences the choice of these viable products. Photocatalysis is designed to harvest visible light (the major component of solar radiation that reaches the Earth's surface) using photocatalysts to drive chemical transformations , while the hole (or the electron vacancy) may accept an electron from an adsorbed donor (promoting its oxidation).The third step is where the photocatalytic nature of certain metal oxides plays a role despite all the steps usually found in all heterogeneous processes. Semiconductor catalysts such as TiO2 photocatalysis happens when the energy of the photons is enough to promote the electrons in the valence band to jump to the conduction band; this occurs in three steps:TiO(a) Photon absorption and electron–hole pair generation.(b) Charge separation and migration to surface reaction sites or to recombination sites.(c) Surface chemical reactions at active sites containing donor oxidation at valence-band holes and acceptor reduction at electron centers .17 can be produced by injecting charge from excited molecules into the conduction band of TiO2 , and superoxide radicals (·O2−) have been reported by many studies in photocatalysis as the main oxidative species that are found in photocatalytic processes.Significant research attention is centered on metal oxides and silicates due to their photocatalytic activities and their wide range of applications in photocatalysis.gap86–88  and 7. T92,93In instituting whether transformation or water splitting  is reall2, CO, CH4, and CH3OH related oxygenates and hydrocarbons94–96 during photocatalytic production.Photoexcited charge carriers  drive th2.1.1.55 TiO2 has low adsorption ability, specifically for nonporous compounds, which is as a result of its polar structure. The synthesis of TiO2 with adsorbents is an important factor in improving the adsorption properties of TiO2 particles; the adsorbents hold the compounds on the adsorbent support. Yu and coauthors45 reported that an increase in the photoreaction rate comes about due to the formation of high environmental concentrations of the compounds around the nonporous TiO2 particle. Consequently, numerous schemes have been established to alter the properties of TiO2, anticipating the lengthening of the lifespan of the photogenerated electron–hole pairs and a narrower band gap. To extend the optical absorption to the visible region and the lifetime of TiO2, many successful studies by researchers in the field have centered on doping metal or non-metal elements into the TiO2 lattice to generate donors or acceptors in the band gap. However, there are substantial restrictions for this approach; the reduced incident photon to electron transformation efficiency in the UV light region and improved carrier recombination centers are the most challenging. Consequently, to heighten the useful application of TiO2, it is important to decrease the recombination and then increase the visible light absorption.45 Various adsorbents such as zeolum, alumina, silica, mordenite, ferrierite, and activated carbon, have been used as the support for TiO2 and they have shown that the hybrid photocatalysts are effective in achieving high decomposition rates of propionaldehyde in the air. Ao and Lee46 used activated carbon with TiO2 as the hybrid photocatalysts in their research and they made similar conclusions to those made by Yu and colleagues.55 The photodegradation efficacy of ZnO, when synergized with activated carbon as the adsorbent, was found to be higher compared to TiO2.The concentration of chemical compounds is determined by the rate of chemical reactions as described by Yu and coauthors.2.1.2.29,49, the sol–gel method47, and vapor decomposition of titanium alkyl oxides or TiCl4 in oxygen.48Preparation methods  for nano2 nanomaterial obtained is mostly based on the conditions used in its preparation. These include the following:The TiO(1) Gas-phase method.(2) Liquid-phase method.2.1.3.2 OTDs are commonly accepted as point defects. In photocatalytic reactions, the point trap model is best used to analyze oxygen vacancies and OTD-related clusters.43 In the case of the synthesis process, lattice defects are certainly produced. These defects are thermal and preparation dependent.43 During material doping, intrinsic point defects are often observed in the lattice. These observed intrinsic point defects exist as atomic impurities, vacancies and interstitials. Studies have shown that these defects are scattered on flat surfaces as observed by STM images. The scattered distribution of these defects is noted to be the main reason for most of the increased photocatalytic activities.The idea of defects primarily lies in the solid state physics explanation of lattice distortion. Lattice distortion is usually in the form of linear defects, point defects, three-dimensional valleys or hetero-impurities and two-dimensional flaws or interfaces. Fujishima and team found that point defects are well studied by scientists in the field and this delivers the principal understanding of the properties of lattice defects, consisting of magnetic, electrical, energetic, optical, and thermal characteristics in solids.44 To simplify the study on the molecular scale, much research has been devoted to the hypothesis pertaining to well-defined particles. Consequently, there is a strong call for the understanding of the nature of photocatalytic reactions regarding the preparation of comparable standard specimens.In contrast, the presence of the coordinate and disordered defects in diverse samples makes it barely possible to exactly compare the photocatalytic properties. Under ambient conditions at room temperature, distinct particles are uncommon.2.2.2). Simply put, this involves hole doping , and electron doping . Magnetic and transport properties are mostly determined by the final material's structure, which is also dependent on its total charge/spin state. This idea is expected to be true in nanomaterials or bulk materials; however, anomalous properties are seen in nanomaterials, due to the ability of these materials to exist in new or active electronic states or environments  images.56 The concentration of oxygen vacancies was measured by X-ray photoelectron spectroscopy (XPS) and this was found to be 3% in the TiO2 lattice. There was a remarkable increase in photocatalytic activity when the oxygen vacancies introduced by hydrogenation slowed the charge recombination; this was actually revealed by the photocurrent, photoluminescence (PL) spectroscopy, and degradation of methylene blue. Fujishima and research group adopted reduction in hydrogen atmosphere coupled with an impregnation process to prepare defective TiO2 with oxygen vacancies and Cu(ii) nanocluster modification.2 There was no improvement in the visible light from the TiO2 photocatalyst samples with optimum oxygen vacancy. Conversely, the photocatalytic enactments of TiO2 samples with a greater quantity of oxygen vacancies were sharply reduced; they even demonstrated much enriched visible light absorptions. Wang and group successfully used the hydrothermal method in their experiment to prepare platinum decorated TiOx2–Nxvia a facile one-pot route by using nanotubular titanic acid as a precursor.3 They further evaluated the photocatalytic performance of Pt/TiOx2−Nx for the visible-light-induced degradation of propylene in relation to the synergistic effect among single-electron-trapped oxygen vacancies and N plus Pt dopants. It was proposed that the synergistic effect among oxygen vacancies and dopants led to the enriched photocatalytic activity of the as-synthesized Pt/TiOx2−Nx. The TiO2 photocatalyst spectral response to the visible light range is usually improved by impurity doping  analysis and X-ray diffraction (XRD) used in the analysis of the changes in the VO concentration as a function of the Co-doping level from ZnO Rietveld refinement generated the same results but X-ray photoelectron spectroscopy (XPS) confirmed a different outcome.4Recently, a novel technique involving positron annihilation lifetime spectroscopy was used to characterize oxygen vacancy associated with hydrogenation modified TiOy doping  and 3.325 on adsorption and desorption, where they used oxygen and water as probe molecules that were observed in STM images to bridge oxygen vacancies, and oxygen atoms on surface Ti atoms, reported the production of pure and reduced TiO2 surfaces. Their work further addressed the criteria to determine the cleanliness by STM imaging.5 Yang and colleagues in their research in 2010 on Chinese housing energy and environment introduced a novel technique for the characterization of oxygen vacancy associates in mostly hydrogen modified TiO2 photocatalyst using positron annihilation lifetime spectroscopy (PALS). They concluded that small neutral Ti3± oxygen vacancies (large quantity), vacancy clusters (appreciably large in size), and voids of vacancies (just a few of them) were actually in hydrogenated TiO2. In the research by Fujishima and coworkers,2 there was a remarkable improvement in the photocatalytic activity of 2% WO3–TiO2 catalysts when an appropriate oxygen vacancy was employed by using Fe3+ as an electron acceptor under UV irradiation in 12 hours.The Wendt group's experiment2 by using carbon as a doping agent.8,15 Inhibition of the charge recombination and trapping of the photoexcited electrons using these doped impurities , change the electron-transfer processes during the photocatalytic reaction as described by Vinodgopal and Kamat in the principle of photosensitization of a semiconductor.2.2.2.The quantitative analysis of oxygen vacancies has been successfully researched by many scientists in the field. Researchers have adopted the following oxygen vacancy quantitative analysis tools:(1) The maximum entropy method (MEM).(2) X-ray diffraction (XRD).Most research efforts have also proposed a method for the analysis of oxygen vacancies using conventional XRD and MEM techniques .2 catalysts18-20 with other semiconductor oxides or depositing metals or doping TiO2 photocatalysts with some other metal ions help to improve its photocatalytic activities. Studies have18 established that the photoreactivity for both oxidation and reduction significantly improved when they doped with Fe3+, Mo5+, Ru3+, Os3+, Re5+, V4+, and Rh3+ at 0.1–0.5%, but Co3+ and Al3+ doping decreased the photoreactivity.22 When the active sites on the reaction surface21 of a gas–solid photocatalyst is reduced, the activity also decreases.21 It can be concluded that the activity of catalysts depends on their lifetime, which is potentially essential to the economic process.21 Studies on toluene,23,24 ethanol25 and trichloroethylene, dimethyl sulfide, and trichloropropene22 have found out that deactivation in these compounds is really uncommon. Sauer and Ollis26 in their work stated that particle materials block pores on the photocatalysts' surfaces, hence, change the surfaces of these catalysts.27 The chemical or physical adsorption of organic substrates on the TiO2 matrix is improved when of lanthanide ions, for instance, La3+, Eu3+, Pr3+, Nd3+, and Sm3+ amalgamated into the matrix19.The efficiency of a particular photocatalyst depends strongly on the competence of electron–hole pair separation and the adsorption ability of gaseous oxygen vacancy compounds. Coupling TiO2.2.3.2 is fabricated by the conduction band and valence band. It is noted that the development of the main active sites, mostly for visible light absorption and the band gap is supported by these energy levels. Lv and group stated that the function of oxygen vacancies as the visible light response sites is due to the defective TiO2 surface during visible light irradiation.57 The influence of the energy structure of the TiO2 photocatalyst on the charge carrier migration and light absorption is very high . This calls for urgent, precise calculations of the defect state in TiO2 energy structure.2 Fujishima and group have reported that the defect states vary remarkably in the band gap. Recent work58 reported lower energy  in oxygen vacancies. It has been proven that within the band gap of TiO2, the oxygen vacancy usually forms a mid-gap electronic state and, therefore, TiO2 functions as the donor. This novel trend was supported by research performed by Eun Chang and colleagues.39 These scientists further summarized energy levels of oxygen vacancies in TiO2. The paradox of the intensely localized small polarons and the delocalized free polarons failed to be explained vividly by isolating electronic bands in many experiments and this led to hybrid function, which has been a remarkable theory. In the electronic band, it was reported that there exist two types of hybrid functions:The pristine energy structure of most outstanding nanomaterials, such as TiO(a) Between the electrons and the conduction band in the presence of delocalized free electrons.(b) Between the electrons and the oxygen vacancies in the form of oxygen vacancy complexes and the ionized shallow-donor impurities.59 It was realized from experiment59 that an occupied defect state of 0.7 eV below the bottom of the conduction band was decreased by the oxygen vacancy.7 Research on the characterization analysis of anatase, rutile, and brookite showed that anatase and brookite were made up of oxygen vacancies, which remarkably improved the photocatalytic activity. In conclusion, it is presumed that the difference in the absorptions on the surfaces of the active sites and the reactants  were due to oxygen vacancies.Considering the theoretical viewpoint, the highest occupied molecular orbital and the lowest unoccupied molecular orbital often shifts due to the influence exerted by the defect states.2.2.4.101,102 or carbon nitrides98 since electrons excited to the conduction band can be trapped at oxygen vacancies100 and carbon defects.99 The promotion from the highest occupied molecule orbitals to the lowest unoccupied molecule orbital with light irradiation causes the rapid movement of an excited single electron in response to the applied electric field; i.e., the voltage supplied by a power source or difference in potential between the energy structure of TiO2 and the redox potential of the adsorbed species  To alter the band energy structure of the pristine TiO(ii) To trap charge carriers in the migration pathways as the electron pool or recombination center.e.g., H2O, O2, CO2, and organic pollutants) as the active sites.61(iii) To power the adsorption of reactants (3.2-based composite photocatalysts with oxygen vacancies in the areas of energy, wastewater treatment and environmental purification. Nonporous TiO2 has revealed its greatness as one of the best candidates in designing and engineering advanced composite photocatalysts. There is little doubt that the considerable progress in TiO2 nano-based composites will continue in the near future. More studies are necessary in order to make full use of the excellent properties resulting from the oxygen vacancy of the nonporous TiO2 photocatalysts.This systematic review sums up the novel developments in the photocatalytic applications of TiOThe authors declare that they have no conflict of interest.


The glymphatic system is a recently discovered cerebrospinal fluid transport system and little is known about its dynamic changes after stroke. This study aimed to dynamically observe the structural and functional changes of the impaired glymphatic system in the thalamus after ischemic stroke by pathology and MRI.Ischemic stroke was induced by the middle cerebral artery occlusion (MCAO) model. A total of 20 Sprague-Dawley rats were randomly assigned into four groups: sham, MCAO 1 week, MCAO 2 week, and MCAO 2 month. All rats successively underwent neurological examination, dynamic contrast-enhanced MRI (DCE-MRI), and immunofluorescence staining. Immunofluorescence staining of glial fibrillary acidic protein (GFAP), aquaporin-4 (AQP4), ionized calcium-binding adaptor molecule 1 (Iba1), and beta-amyloid precursor protein (APP) were done in thalamus ventroposterior nucleus.P < 0.05 for all). The AQP4 polarization rates of the MCAO 2 week and 2 month groups were the lowest . Although there was no correlation between histological changes and MRI metrics in all four groups , the tendency of the APP deposition was nearly consistent with the one of the contrast agent retention in DCE-MRI.The astrocyte and microglial activation and the APP deposition in the MCAO 2 week group were the highest (The glymphatic system in the thalamus was severely impaired at 2nd week after MCAO, and may be revealed by DCE-MRI. This study may provide a relevant theoretical basis for making a thorough inquiry of the mechanism of brain injury after stroke and clinical treatment of ischemic stroke and help readers appreciate the importance of DCE-MRI. The results of this study may provide the theoretical basis for exploring new targets for ischemic stroke treatment and help readers appreciate the importance of DCE-MRI.n = 5), group of MCAO 1 week (n = 5), group of MCAO 2 week (n = 5), and group of MCAO 2 month (n = 5). The sample size was reasonable based on the law of diminishing returns and the male rats were selected based on the published papers  into the left middle cerebral artery through the left common carotid artery and internal carotid artery, to block blood flow to the left middle cerebral artery. Ninety minutes later, the filament was drawn out from the internal carotid artery to allow reperfusion. On the contrary, sham group rats with the sham operation were exposed to the internal carotid artery, external carotid artery, and common carotid artery without inserting filament. All rats successively underwent neurological examination and DCE-MRI, followed by removing the brain samples for immunofluorescence staining (in vivo Experiments).Adult male Sprague-Dawley rats (260–270 g) were obtained from Shanghai Jie Si Jie Laboratory Animal Co., Ltd. . A total of 20 rats were randomly assigned into four groups: sham group  with a 60-mm-diameter gradient coil , as previous studies . T2-weig®, China) injection was carried out as the previous study  of each rat were obtained at approximately −4.16 mm relative to the bregma, according to the Immunofluorescence sections were scanned using a Vslide scanning microscope  with a ×20 primary objective. All images were acquired using constant scanning settings, and further semi-quantitatively analyzed to characterize the expression of those above immunofluorescence staining using Image J .Equivalent regions of interest were drawn on the ipsilateral (left) and contralateral (right) thalamus ventroposterior nucleus (VPN), and mean intensity and area% of all these markers of each region of interest were measured. Besides, AQP4 polarization was calculated as described in previous studies: the ratio of immunofluorescence intensity in high threshold and low threshold . An incrpost-hoc LSD tests performed for each of the two groups. Unpaired t-tests were performed for two groups comparison. The correlations between histological changes, MRI metrics, and functional scores were assessed using the Spearman correlation analysis. In statistical tests, differences were considered significant when P < 0.05. The statistical analysis was performed using Prism, version 8.3.0 .One-way analysis of variance (ANOVA) was performed for multiple group comparisons with The GFAP levels between the ipsilateral and the contralateral thalamus VPN in MCAO 2 month group, MCAO 2 week group, and MCAO 1 week group had significant differences. Astrocyte was activated in the ipsilateral thalamic VPN at the 1st week, the 2nd week, and the 2nd month after MCAO .GFAP values of MCAO 2 month group, MCAO 2 week group and MCAO 1 week group were significantly higher than those of sham group . In addition, there were significant differences between MCAO 2 month group and MCAO 2 week group (P < 0.0001), MCAO 2 week group and MCAO 1 week group (P < 0.0001). At the 2nd week after MCAO, astrocyte activation in the ipsilateral thalamus VPN was most obvious, as shown in The R2The AQP4 staining in each group is shown in AQP4 polarization of the MCAO 2 week group and MCAO 2 month group was lower than that of the sham group . The R2AQP4 polarization of the MCAO 1 week group was lower than that of the sham group, but it was not statistically significant. The AQP4 polarization rate in the ipsilateral thalamus VPN decreased, especially at the 2nd week and the 2nd month after MCAO, as shown in The R2Ionized calcium-binding adaptor molecule 1 is a specific staining marker of microglia. The expression of Iba1 levels between the ipsilateral and the contralateral thalamus VPN in the MCAO 2 month group, MCAO 2 week group, and MCAO 1 week group had significant differences. Microglial was activated in the ipsilateral thalamus VPN at the 1st week, the 2nd week, and the 2nd month after MCAO .Iba1 values of the MCAO 2 month group, MCAO 2 week group, and MCAO 1 week group were higher than the sham group . The microglial activation in the ipsilateral thalamus VPN was obvious, especially at the 2nd week after MCAO, as shown in The R2The APP staining in the ipsilateral and contralateral thalamus VPN in each group is shown in APP value of the MCAO 1 week group was higher than the sham group, but the difference was not statistically significant. The R2APP values of the MCAO 2 month and MCAO 2 week group were significantly higher than the sham group , and the R2APP value of the MCAO 2 week group was higher than the MCAO 1 week group. The APP deposition in the ipsilateral thalamus VPN was obvious, especially at the 2nd week after MCAO, as shown in The R2Using Thioflavin S staining, no abnormal mature amyloid plaque was found in the thalamus VPN for each group after MCAO .On the 1st day after MCAO, the ischemic cores were high signal at T2-weighted MRI for MCAO 2 month group, MCAO 2 week group, and MCAO 1 week group. The ratio of T2SI of the ipsilateral thalamus VPN touched its bottom at the 1st week after MCAO and gradually recovered at the 2nd week and the 2nd month .On the 1st day and the 2nd week after MCAO, the ipsilateral thalamus VPN was almost normal at T2-weighted MRI. At the 2nd week after MCAO, the abnormal aggregation area of the contrast medium included almost all the ipsilateral thalamic VPN, which was roughly consistent with the area of astrocytes and microglia proliferation and the AQP4 depolarization. The lateral part of the ipsilateral thalamus VPN was more obvious than the central small cell part. However, for the APP deposition, small cells in the central part of the ipsilateral thalamus VPN were more obvious than in the lateral part. The tendency of the APP deposition in the ipsilateral thalamus VPN was consistent with the one of the contrast medium retention in DCE-MRI, but the location was not the same .P > 0.05 for all).There was no correlation between histological changes  and MRI metrics [the ratio of T2SI and R1(6 h)] in all four groups (P = 0.0037). The score of the MCAO 2 week group was significantly higher than the sham group (P = 0.0013), but lower than MCAO 1 week group. The score of the MCAO 2 month group was lower than MCAO 2 week group and higher than the sham group. In other words, the neurological function deteriorated most at the 1st week and the 2nd week after MCAO, and gradually recovered at the 2nd month, but it was still lower than the healthy level .There was no correlation between neurological function score and histological changes , as well as MRI metrics [the ratio of T2SI and R1(6 h)] in the MCAO 2 month group, MCAO 2 week group, and MCAO 1 week group  inserted into the middle cerebral artery in our study. The animal model in our study is more conventional. Secondly, in the Gaberel’s study, all the performed mice had two angiographies which revealed that the middle cerebral artery was repermeabilized in all mice 24 h after stroke onset, while we did not perform angiography and cannot confirm whether the middle cerebral artery was repermeabilized in all rats. It is one of the areas for improvement in our future study. Thirdly, immunofluorescence staining and analysis, including astrocyte activation, AQP4 polarization, microglial activation, and APP deposition were performed in our study, and all these histological changes were abnormal until 2 months after MCAO, so we inferred that the glymphatic system remain impaired in structure until 2 months poststroke. While only DCE-MRI was used in the Gaberel’s study and the result of “glymphatic perfusion appeared normal at 24 h after stroke onset” focused on function.Microglia in the activated state engulfs abnormal substances in the brain parenchyma. Our finding agrees with these reporters that harmful substances such as APP accumulate in the thalamus VPN, which advances the microglia activation . MicroglThe impaired glymphatic system decreases the clearance efficiency of soluble proteins in the brain parenchyma, and the persistence of glymphatic system dysfunction eventually leads to the deposition of harmful proteins in the brain parenchyma. By comprehensive comparison with the results of DCE-MRI and immunofluorescence staining at 2nd week after MCAO, we found that the abnormal aggregation of contrast medium occurred in the whole ipsilateral thalamus VPN region, and the astrocytes and microglia proliferation and the AQP4 depolarization were also in the whole ipsilateral thalamus VPN region. However, the APP deposition was more obvious in the central part of the thalamus VPN, that was, the small cell part. We speculate that the thalamus VPN small cell part is the initial concentration part of the thalamus striatum pathway fiber bundle, which is the more observable site of retrograde secondary degeneration along the axon . The APPWe found that the neurological function deteriorated most at the 1st week and the 2nd week after MCAO, and gradually recovered at the 2nd month. This performance was consistent with the tendency of the APP deposition in the thalamus. Our finding raises the possibility that the harmful substances deposition in the thalamus after ischemic stroke may have a certain effect on the neurological function. However, there was no correlation between neurological function scores and histological changes in MCAO 2 month group, MCAO 2 week group, and MCAO 1 week group statistically. Expanding the sample size may lead to positive results in future study.As for the failure of Thioflavin S staining to show mature amyloid plaques in the thalamus after MCAO in this study, it is inconsistent with the earlier studies . There min vivo two-photon imaging, angiography, and Ki-67 staining in this study. All of these are the areas for improvement in our future study.The present study has several limitations. Firstly, we did not study the functional and pathophysiological changes of the glymphatic system in the thalamus in the hyperacute stage, in the acute stage or chronic stage after MCAO, and also in the peripheral infarct. Secondly, R2 was not a fair metric to longitudinally assess the AQP4 change since it was calculated by /contralateral values and both sides changed over time. One way to confirm this assessment is to compare the change in the thalamus to other brain regions, such as the cortex. But both our previous experiments and this experiment showed that more than 2/3 of the ipsilateral cortex was also affected by ischemia. This calculation method will be improved in future experiments. Thirdly, it was reported that significant secondary neuronal loss and reactive gliosis occur in the thalamus and hippocampus after MCAO in non-human primates . Maybe aAll in all, this study investigated the structural and functional dynamic changes of the impaired glymphatic system in the thalamus, secondary degeneration area after ischemic stroke in rats by pathology and MRI. The major strength of this study was finding the glymphatic system was severely impaired at the 2nd week after MCAO. Further studies are warranted to investigate the indirect mechanism and in-depth direct mechanism of the impaired glymphatic system at the molecular level, and at the same time, to explore using the internal features of multi-modal images to predict neurological scores at the radiomics level. Our study may provide the theoretical basis for making a thorough inquiry of the mechanism of brain injury after stroke and clinical treatment, such as broadening the treatment time window to the 2nd week, exploring new targets for the treatment of secondary degenerative areas, then eventually help to improve the prognosis of ischemic stroke. Our study also helps readers appreciate the importance of DCE-MRI in animal research and prompts that DCE-MRI is a potential clinically acceptable approach that can be used to visualize and evaluate the glymphatic system.The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.This animal study was reviewed and approved by the Ethics Committee of Huashan Hospital, Fudan University.CL, LL, ZY, XF, and YY were responsible for the study concept and the design. CL, LL, CS, and XH collected the data. CL, LL, CS, XH, LY, XZ, and JT analyzed the data and conducted the statistical analysis. CL and LL wrote the manuscript. ZY, XF, and YY supervised the manuscript and provided technical or information support. All authors approved the final version of the manuscript.


This study aimed to determine the body surface puncture position and depth of the center of the intramuscular nerve dense region in the suboccipital muscle to provide morphological guidance for accurate botulinum toxin A injection to treat headaches caused by increased suboccipital muscle tension.L and PH. The percentage position of the PH and PL points on the H and L lines and the depths of the center of intramuscular nerve dense regions were identified.Twenty-four cadavers aged 66.5 ± 5.3 years were studied. The curve line connecting occipital eminence or mastoid process and spinous process of the 7th cervical vertebrae was considered the longitudinal reference line (L) and horizontal reference line (H), respectively. Sihler's staining, barium sulfate labeling, and CT were employed. The body surface projection point of the center of the intramuscular nerve dense region was designated as P. The projection of the center of the intramuscular nerve dense region was in the opposite direction across the transverse plane and was recorded as P'. The intersections of the vertical line through point P and lines L and H were designated as PH of the center of the intramuscular nerve dense region was located at 51.40, 45.55, 20.55, and 43.50%. The PL was located at 31.38, 30.08, 16.91, and 52.94%. The depth of the center of the intramuscular nerve dense region was at 22.26, 22.54, 13.14, and 27.30%. These percentage values are all the means.Sihler's staining showed one intramuscular nerve-dense region in each suboccipital muscle. The PAccurately defining the body surface position and depth of the center of intramuscular nerve dense region in suboccipital muscles will help to improve botulinum toxin A to target localization efficiency for treating tension-type headache. Suboccipital muscles coordinate and maintain the posture and stability of the head and neck and bear >50% of the rotation function of the whole head and neck , 2. In cTension-type headache is the most common primary headache, with a prevalence of 42% . HoweverBotulinum toxin A (BTX-A) intramuscular injection to the motor endplate to block the release of acetylcholine from the presynaptic membrane and inhibit muscle excitation has been proven to be an effective method for the treatment of TTH caused by increased suboccipital muscle tension , 19–21 aBased on the fact that the location of the INDR and the center of the INDR (CINDR) in suboccipital muscles have not been defined, this study intends to use Sihler's staining to show the INDR, then the CINDR is labeled with barium sulfate, spiral CT scanning and three-dimensional reconstruction are performed to accurately localize the body surface position and depth of CINDR, to provide morphological guidance for the block target localization of BTX-A injection to treat TTH caused by increased tension in the suboccipital muscles.In this study, 24 Chinese adult cadavers (12 men and 12 women) aged 30–75 (66.5 ± 5.3) years at the time of death without a history of neuromuscular diseases and head and neck deformities were collected for analysis. Of the cadavers, 12 were fixed in formalin and 12 were frozen. This study protocol was approved by the Ethics Committee of the Zunyi Medical University (No. #2020-1-006).In the 12 formalin-fixed cadavers (6 men and 6 women), a transverse incision at the level of the external occipital protuberance and a longitudinal incision from the external occipital protuberance to the spinous process of the 7th cervical spine was made. The skin and subcutaneous tissues were cut as one layer and turned to the front area of the tragus. The trapezius, splenius capitis, and splenius cervicis muscles were exposed by layer, and the fascia was carefully separated to expose the starting and ending points of the suboccipital muscles, the arrangement of muscle fibers, and the source of nerve-muscle branches. We also observed whether there were blood vessels at the location where the nerves enter the muscle. The muscle length, width, and thickness were measured with a Vernier caliper. The external occipital protuberance (point a), the mastoid process (point b), and the spinous process of the 7th cervical spine (point c) were selected as body surface markers. To describe and accurately locate the body surface position and depth of the CINDR of the suboccipital muscles, the curves between points a and c and between points b and c were set as the longitudinal (L) and horizontal (H) reference lines, respectively.The suboccipital muscles of the abovementioned 12 cadavers were completely removed and stained using Sihler's staining process as follows: the muscles were macerated in 3% potassium hydroxide and 0.4% hydrogen peroxide solution for 3–4 weeks; decalcified in Sihler I solution  for 4 weeks and in Sihler II solution  for 4 weeks. It is ideal to decolorize the Sihler I solution for 4–20 h as the muscle was light purple and the nerve branches were black. These were neutralized in 0.05% lithium carbonate solution for 3 h with continuous stirring. For transparency, glycerol gradients of 40, 60, 80, and 100% were performed for 1 week each. The distribution patterns of the intramuscular nerves were observed under an X-ray reading lamp and photographed. The pattern map was drawn and embedded into the corresponding position of the muscle.Using Photoshop cc 2019 , the dense region of intramuscular nerve branches was framed, the box selection was double-clicked, and the pop-up center point was designated as the CINDR and marked. The percentage position of the CINDR on muscle length (from the nearest origin to the farthest insertion of muscle fiber) and width  were measured.in-situ suture was performed. One syringe needle was tied at three bony body surface positions and marked as a, b, and c, respectively, and the barium sulfate-soaked silk threads were sutured on the skin to connect the curve between ac and bc, representing the L and H reference lines, respectively. With the cadaver in the prone neutral position, 64-row spiral CT scanning   and three-dimensional reconstruction were performed. According to the results of Sihler's staining, one INDR was identified in the rectus capitis posterior minor, rectus capitis posterior major, obliquus capitis superior, and obliquus capitis inferior muscles, respectively. Herein, the CINDRs were named CINDR1, CINDR2, CINDR3, and CINDR4, respectively. The CINDR was punctured with a needle perpendicular to the skin and then was rescanned under CT. The projection point of the CINDR on the body surface was named point P, which was the needle puncture point . Using the Syngo system , the length of the H and L reference lines close to the skin was measured. The intersections of the vertical line passing through point P with the H reference line and the horizontal line with the L reference line were recorded as PH  and PL . The length between point b and PH was H' , and the length between point a and PL was L' . The calculation was H'/H × 100%, L'/L × 100%. On the cross-section, the point on the opposite side skin projected from the vertical skin of point P through the extension line of the CINDR was defined as point P' . The length of P-CINDR and PP' was measured and calculated by P-CINDR/PP' × 100% and the percentage puncture depth was determined. Then, the located suboccipital muscle was removed and stained with Sihler's staining to verify whether the morphological position of INDR was consistent with that of before.The 12 frozen cadavers (6 men and 6 women) were thawed and dissected to expose the suboccipital muscle. The muscle length and width were measured. Combined with the CINDR position obtained by Sihler's staining, the corresponding position of the CINDR was identified on these suboccipital muscles. The CINDR was marked with barium sulfate , mixed with 801 glue   and a layer-by-layer t-test, and the sex comparison was tested via the t-test between two independent samples. The test level was α = 0.05; P < 0.05 was considered as statistically significant.The measured data are expressed by the percentage (mean ± SD) of each subject to eliminate the influence of individual differences. The data were processed by SPSS version 18.0 software . Based on the normal distribution of the obtained data, the comparison between the left and right sides was tested by a pairing The rectus capitis posterior major and rectus capitis posterior minor muscles were shaped like inverted triangles, while the obliquus capitis superior and obliquus capitis inferior muscles were shaped like spindles. The rectus capitis posterior minor, rectus capitis posterior major, and obliquus capitis superior muscles all received suboccipital innervation only. Of the obliquus capitis inferior muscles, 95.83% (23/24) were innervated with the suboccipital nerve and the greater occipital nerve, and the branches of the greater occipital nerve were small. Of the rectus capitis posterior minor branches, 83.3% (20/24) first passed through the superficial surface of the rectus capitis posterior major to the center of the abdominal muscle and then entered the muscle on the superolateral surface of the rectus capitis posterior minor. Of the rectus capitis posterior minor branch, 16.7% (4/24) first entered from the head to the outside and below the rectus capitis posterior major, tread on the posterior rectus major of the head, came out of the middle of the rectus capitis posterior major, inclined inward, penetrated the rectus capitis posterior major again, and entered the muscle on the outer and upper surface of the rectus capitis posterior minor muscle. The rectus capitis posterior major branch entered the muscle from the inferolateral side of the deep surface of the muscle. The obliquus capitis superior branch entered the muscle from the lower edge of the muscle. The obliquus capitis inferior branch of the head entered the muscle from approximately 1/3 of the superolateral part of the muscle surface. Blood vessels near each nerve's entry point were observed .2, named INDR1, and the center of the dense region (CINDR1) was located at 31.91 ± 1.18% of the muscle length and 55.41 ± 1.40% of the muscle width  is located at the level of 40.98 ± 1.27% of muscle length and 40.44 ± 1.16% of the muscle width. The third branch progressed toward inferomedial side and the insertion of the rectus capitis posterior major muscle, with relatively few branches  was located at 43.93 ± 1.33% of muscle length and 45.83 ± 1.46% of muscle width. The third primary branch progressed toward the inferolateral side and the insertion point of the muscle, with relatively few branches , which was located at 27.78−59.78% of the muscle length, its area was approximately 1.85 ± 0.13 cm2. The center of the nerve-dense region (CINDR4) was located at 44.22 ± 2.39% of the muscle length and 48.94 ± 2.11% of the muscle width . The medial branch was thicker, and its branches were dense in the middle and upper parts of the muscle belly. The middle branch traveled from the deep side of the muscle belly to the middle and lower parts of the muscle belly and began to branch densely. These branches communicated with the arborized branches of the medial branch and formed a rectangular INDR  (The P > 0.05) , 2. The  > 0.05) .The tension in the suboccipital muscle can be due to the anatomical relationship of the myodural bridge. When its muscle tension increases, TTH can occur , 15, 30.In addition to headaches caused by the suboccipital muscles, abnormal cervical muscle tension headaches are also associated with splenius capitis and splenius cervicis muscles. The intramuscular nerve distribution pattern of these two muscles has been revealed by Sihler's staining. The distribution of the nerve in the middle part of the muscle belly of the splenius capitis was the densest, indicating that 50% of the muscle length should be the most effective area for the administration of the BTX-A injection. The intramuscular nerve of the splenius cervicis muscle was widely distributed between 30 and 70% of the muscle length . AlthougThis experiment's results indicate that the INDR of the obliquus capitis inferior muscle is close to the middle part muscle belly and the INDR of the other three suboccipital muscles was not located in the middle part of the muscle belly. Nerve endings and muscle fibers often form motor endplates in the middle of the muscle fibers, and spindle muscles composed of isometric muscle fibers often form the motor endplate band in the middle part of the muscle belly. Therefore, the middle of the muscle belly is often the target of BTX-A injections , 33. How2 at the site of injection, whereas 2.5–5 U can diffuse to 4.5 cm2 at the site of injection  of the suboccipital muscle and the dose at each site is 15–20 U. However, the specific injection site and dose of each suboccipital muscle have not been described in detail , 37. Stunjection , 38. ComIn conclusion, Sihler's staining was used to demonstrate the intramuscular nerve distribution pattern of the suboccipital muscle. Using barium sulfate to label the center of the INDR, spiral CT scanning, and designed longitudinal and transverse reference lines, the geometric relationship between bone landmarks and the CINDR was established. The CINDR was projected onto the body surface, and its puncture position and depth data are expressed as a percentage, which can eliminate individual differences to make the clinical operation strong. Thus, the results of this study will help to improve the target localization efficiency of BTX-A in the treatment of headache caused by increased tension of the suboccipital muscle.However, this study has some limitations that should be noted. The ethnic differences of the patients were not considered and the curative effect needs to be verified by clinical application. In addition, this study was conducted in normal subjects, and not in TTH ex-sufferers. We believe that ultrasound can be used to assist in clinical localization to improve the efficiency and curative effect of the target block. Injection of deep suboccipital muscles without ultrasound guidance may be accompanied by an increased risk of injuring the vertebral artery especially if this artery is elongated in the individual.This study is the first study to systematically investigate the intramuscular nerve dense region and to define the body surface position and depth of center of the intramuscular nerve dense region in suboccipital muscles. It will help improve BTX-A target localization efficiency for treating tension-type headache.The original contributions presented in the study are included in the article/supplementary material, further inquiries can be directed to the corresponding author/s.The studies involving human participants were reviewed and approved by the Ethics Committee of Zunyi Medical University (No. #2020-1-006). The patients/participants provided their written informed consent to participate in this study.SY conceived and designed the experiments, performed the experiments, contributed to writing, reviewing, and editing the manuscript. JW conceived and designed the experiments, performed the experiments, analyzed the data, and wrote the original draft. YL and MW contributed to reagents, materials, and analysis tools. All authors contributed to the article and approved the submitted version.This study was supported by the National Natural Science Foundation of China (No. 31660294), the Guizhou Science and Technology Project (No. ZK [2021] 115), and the Guizhou Provincial Health Commission (No. gzwkj2021-277).The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.


Sow farrowing is an important part of pig breeding. The accurate and effective early warning of sow behaviors in farrowing helps breeders determine whether it is necessary to intervene with the farrowing process in a timely manner and is thus essential for increasing the survival rate of piglets and the profits of pig farms. For large pig farms, human resources and costs are important considerations in farrowing supervision. The existing method, which uses cloud computing-based deep learning to supervise sow farrowing, has a high equipment cost and requires uploading all data to a cloud data center, requiring a large network bandwidth. Thus, this paper proposes an approach for the early warning and supervision of farrowing behaviors based on the embedded artificial-intelligence computing platform (NVIDIA Jetson Nano). This lightweight deep learning method allows the rapid processing of sow farrowing video data at edge nodes, reducing the bandwidth requirement and ensuring data security in the network transmission. Experiments indicated that after the model was migrated to the Jetson Nano, its precision of sow postures and newborn piglets detection was 93.5%, with a recall rate of 92.2%, and the detection speed was increased by a factor larger than 8. The early warning of 18 approaching farrowing (5 h) sows were tested. The mean error of warning was 1.02 h. Early warnings and supervision of sow farrowing refer to alarms generated before the onset of sow farrowing to alert breeders so that they can detect and deal with related problems early on and alleviate problems such as difficult farrowing (dystocia), piglet suffocation, and excessively low temperatures during farrowing ,2. As maSows start to show obvious nest-building behavior 24 h before the onset of farrowing with higher activity levels than normal and an increased frequency of posture changes. These behaviors can often be reliable indicators of farrowing ,4. ReseaMethods of computer vision-assisted supervision have the advantages of persistence, non-invasiveness to animals , and strIn this study, video data of sows were collected from two pig farms: Fengyuan Ecological Agriculture Co., Ltd.  and the Zhengjie Pig Farm . There was a total of 35 sows, 11 of which were studied at the Fengyuan Pig Farm during the period of 24 April 2017 to 31 May 2017. The other 24 were studied at the Zhengjie Pig Farm from 9 June to 15 June, 2020. Large white sows in the perinatal period and their piglets were selected as the test subjects for both farms. The sows were randomly placed in farrowing crates (2.2 m × 1.8 m) one week before farrowing. The stalls were equipped with food troughs, drinking bowls, piglet incubators, etc. The ambient temperature in the sow farrowing rooms was maintained between 20 and 28 °C, and the temperatures of the piglet incubators were controlled within a comfortable range in accordance with that of the farrowing room. The use of piglet incubators started 1 day before the expected farrowing date and stopped when the piglets were weaned.The video capture devices consisted of cameras, a network hard disk video recorder (NVR), a switch, and a local server. The cameras were installed in the farrowing rooms, and the switch, NVR, and local server were installed in a cabinet in an information service center adjacent to the farrowing rooms. The videos recorded 1 day before and after the sow farrowing were manually screened and then processed into image data using Python and OpenCV. The labeling software was used to manually annotate and enhance the data of sow postures and newborn piglets in the 12,450 images acquired. Data enhancement was performed via cropping, translation, rotation, mirroring, changing the brightness, adding noise, and cutout. A total of 32,541 images were acquired after the data were expanded. The dataset was divided into five categories, including four sow postures  ,18 and tUsing the same algorithm to detect sows and piglets concurrently is advantageous for lightweight deep learning. Hence, an algorithm suitable for the detection of targets of various sizes was designed. In this study, the YOLOv5s-6.0 network structure was used to build a model for detecting sow postures and newborn piglets. It is an anchor-based algorithm that is primarily composed of four parts: Input, BackBone, Neck, and Prediction. A detailed diagram of its structure is presented in The loss function of the model consists of three parts: Bounding Box Loss, Class Loss, and Object Loss. Bounding Box Loss uses the generalized IoU (GIoU) loss to calculate the loss for bounding-box regression, and Class Loss and Object Loss use the loss function of binary cross-entropy (BCEloss) to calculate these losses. GIoU loss and BCEloss are calculated using Equations (1) and (2), respectively.Here, A and B represent the areas of the true box and prediction box, respectively; C represents the area of the minimum rectangle containing A and B; The algorithm for detecting sow postures and newborn piglets was deployed on the embedded artificial-intelligence (AI) computing platform of the Jetson Nano series launched by NVIDIA. TensorRT is a high-performance neural-network inference optimizer and runtime engine for Jetson Nano deployment. It was used in this study to optimize the proposed model based on the YOLOv5s algorithm. The conversion process of the model on the Jetson Nano embedded development board was pth→.wts→.engine, as shown in TP represents the number of correct predictions for positive samples, FP represents the number of false predictions for positive samples, and FN represents the number of false predictions for negative samples.The performance of different algorithms was evaluated using indices such as the precision, recall rate, and detection speed. The size of the model and its detection speed indicated whether the algorithm was suitable for migration to embedded devices, and the precision and recall rate were used to measure the algorithm’s ability to detect all categories, including four sow postures  and the newborn piglets. The calculation formulas were as follows:The model training environment was as follows: Ubuntu 18.04 operating system; Intel(R) Xeon(R) Gold 5118 @ 2.30 GHz CPU; NVIDIA Quadro P4000 GPU; 8 GB of video memory; 64 GB of memory; 2-TB hard disk; PyTorch 1.7.1 and Torchvision 0.8.2 deep-learning frameworks; CUDA version 10.1.The model deployment environment was as follows: Ubuntu 16.04 operating system for ARM; 4-core ARM A57 @ 1.43 GHz processor (CPU); 128-core Maxwell architecture GPU; 4 GB of memory; JetPack 4.5; Cuda 10.2.89; Python 3.6, TensorRT 7.1, Opencv 4.1.1, and CMake 3.21.2 deep-learning environments.The model parameters were as follows. (1) For the YOLOv5 training, the number of epochs was set as 300, the learning_rate was set as 0.0001, and the batch_size was set as 16. (2) For the TensorRT-optimized network, considering that a larger batch and higher precision require a longer processing time, the batch_size was set as 1, and fp16 precision was used.The loss function of the model indicates the degree of difference between the true value and the value predicted by the model. This difference decreased as the training process continues. The model performance is excellent when the loss value becomes stable. The change curves of the accuracy and recall of the model are shown in In addition to the YOLOv5s algorithm, we evaluated the performance of the Anchor-free target detection algorithms YOLOX-nano and NanoDet-m—both of which support image detection, local video detection, and camera detection—for the same dataset. In order to test the generalization ability and anti-interference ability of the model in this paper, the sow numbered 24 at the Zhengjie Pig Farm, which was called “new sample”, was reserved when the model was trained. A total of 410 images containing different complex scenes were selected from the new sample to test the model. The wireless network card, monitor, keyboard, mouse, and other devices were connected to the Jetson Nano. A CF-938AC wireless network card with an M.2 interface was connect to a WiFi node to realize wireless data transmission. Decoding and neural-network inference were performed for the real-time video stream of the TensorRT optimized model for the detection of sow postures and newborn piglets. The model was then successfully deployed on the embedded development board, as shown in In this study, the detection results before and after the model optimization were tested for daytime and nighttime scenarios. As shown in The GPU utilization rates on the embedded development board constrain the practical application capability of the model. f represents the sow posture transition frequency, n represents the number of posture transitions, and T represents time (unit h). The values were continuously updated during the detection process.According to the posture sequences of the sows at different moments output by the model, the sow posture transition frequency from 48 h before farrowing to 24 h after farrowing was calculated as follows:As shown in Considering the aforementioned patterns, the early-warning strategies used in this study can be summarized as follows: (1) the early warning was sent when the sows’ posture transition frequency exceeded the upper threshold of 17.5 times/h (2) and when it fell below the lower threshold of 10 times/h; (3) for minimizing the impact of daily living habits  of the sows on the warning of approaching farrowing, the upper or lower threshold had to be exceeded for more than 5 h. Tests on the 22 sows used as the experimental samples revealed that early warnings could be sent 5 h prior to the onset of farrowing, with an average error of 1.02 h between the early-warning time and the actual farrowing time.D represents the farrowing duration, i.e., the time gap from the start to the end of farrowing; startT represents the time the first piglet was born, at which the farrowing started; and endT represents the time the last piglet was born, at which the farrowing ended.Sows’ farrowing behaviors were supervised according to the result of newborn piglet detection to implement early warning of farrowing and determine the number of piglets. The following formulas were used:After the first newborn piglet was detected, the alarm for sow farrowing was triggered, prompting “Delivery Begin! Start time: ×××”. Additionally, the flashing of the light-emitting diode (LED) was controlled by varying the levels output by the General Purpose Input/Output (GPIO) pin. The breeder can quickly locate the farrowing sow by checking the flashing LED light and judge whether manual intervention is needed. The detection time of each image using the model on the embedded development board was 67.2–80.3 ms. When the detection speed was excessively high, piglets tended to be falsely detected, and the alarms were generated earlier than necessary. Hence, to reduce the number of false alarms and realize real-time detection, the approach of “three consecutive detections” was adopted before alarm generation; i.e., only when the newborn piglets were detected three times consecutively was farrowing judged to have occurred, as shown in Each time a tag-box for a piglet was detected, the number of piglets was increased by 1, and the duration of farrowing was recorded until the process ended and the number of piglets was determined. In the above equation, CA (Current Number Accuracy) is the average accuracy of the current number of piglets during sow farrowing, and DA (Detected Number Accuracy) is the average accuracy of piglet detection during sow farrowing. The overall average accuracy of the current number was 63.2% and the overall average accuracy of the detected number was 92.9% for the piglet detection during farrowing of 22 sows in the experimental sample, and the specific results of piglet detection per pen are shown in In real-world applications, cameras are installed on the embedded development board to detect newborn piglets in real time, and early warnings and alarms of approaching farrowing are sent according to the results of the detection of sow postures and piglets to communicate sows’ farrowing behaviors to breeders in a timely manner and increase the survival rate of piglets.Early warnings of approaching farrowing and supervision of sows’ farrowing behaviors in the perinatal period were implemented using an embedded development board. The following conclusions are drawn.(1)Video data of 35 sows before and after farrowing were collected and preprocessed to construct a dataset containing four types of sow postures as well as newborn piglets, and the model employed for the detection of sow postures and newborn piglets was trained and tested using Quadro P4000. An analysis of the evaluation indices of different algorithms revealed that YOLOv5 algorithms were effective for detecting sows and piglets of different sizes.(2)An inference engine that supports TensorRT was generated for the model for the detection of sow postures and newborn piglets. The accelerated model was deployed to the embedded development board, after which it ran with a higher throughput and lower latency. The precision of the model after migration to Jetson Nano reached 93.5%, with a recall rate of 92.2%, and the detection speed was increased by a factor larger than 8.(3)According to the changes in the frequency of sow posture transitions output by the model, early warnings were sent 5 h before the onset of farrowing, with an average error of 1.02 h between the warning time and the actual farrowing time. Alarms for sow farrowing were sent using the approach of “three consecutive detections” for the first newborn piglet, and the piglet number was determined according to the number of newborn piglets detected.We investigated how to automatically predict and detect the duration of sow farrowing via early warning of approaching farrowing and supervision of farrowing behaviors based on the embedded development board. Compared with the method of Steffen Küster et al. , the err


It was found that the buffer capacity of microcapsules in the presence of mono- and di-valent salts of the same ionic strength did not differ practically. Increasing the NaCl concentration to 1 M led to an increase of buffer capacity of PMCs at pH ≥ 5, and an increase in NaCl concentration above 1 M did not change buffer capacity. The study of the buffer capacity of pre-heated PMCs showed that buffer capacity decreased with increasing incubation temperature, which was possibly due to the compaction of the PMCs and an increase in the number of compensated PAH sites. The addition of 1 M sodium chloride to heated PMCs presumably reversed the process described above, since an increase in the ionic strength of the solution led to an increase of the buffer capacity of the PMCs. The effects described above confirm the hypothesis put forward that the buffer properties of microcapsules are determined by uncompensated PAH regions in their composition.Polyelectrolyte microcapsules (PMCs) are used in the development of new forms of drugs, coatings and diagnostic systems. Their buffer capacity, depending on the conditions of the medium, has not been practically studied, although it can affect the structure of both the capsule itself and the encapsulated agents. In this connection, we studied the buffer capacity of polyelectrolyte microcapsules of the composition  Polyelectrolyte microcapsules are supramolecular systems created by the layer-by-layer method . It is aDubrovskii et al. have already demonstrated differences in the behavior of the buffer capacity of polyelectrolyte microcapsules depending on the composition of the PMC shell, the presence of an encapsulated protein, and 0.5 M sodium chloride . We assuA change in the physicochemical properties of polyelectrolytes under the action of the ionic strength of the solution may be one of the possible reasons for the change in the buffer capacity of polyelectrolyte microcapsules ,16,17. IAnother reason for the change in the buffer capacity of polyelectrolyte microcapsules under the action of ionic force may be a change in the solubility of the polyelectrolyte complex (PC) ,18,19. IThe temperature of the solution can also affect the change in the buffer capacity of PMCs ,20,21. IIn addition, a number of works show changes in the PMC morphology, their cut thickness, and the migration of their polyelectrolyte layers, depending not only on the composition of the PMC shell, the presence of an encapsulated protein, or the presence of sodium chloride, but also on the ionic strength of the solution and the temperature of the medium ,31,32,33In our previous work, we revealed the presence of a buffer capacity (BC) in PMCs consisting of PAH and PSS . It was We studied BC of PMCs in the presence of 1 M sodium chloride and 0.5 M sodium sulfate, which have the same ionic strengths at these concentrations. The results of this study are presented in As can be seen from 3 on pH in the presence of various concentrations of sodium chloride.The next stage of the study was to examine the BC of PMCs in the presence of salts to assess dependence on salt concentration. As can be seen from the figure, the presence of NaCl in the solution led to an increase of BC of the PMCs at pH ≥ 5. At the same time, BC increased with an increase in NaCl concentration to 1 M, which might have been due to a decrease in the number of compensated regions of PMC polyelectrolyte complexes with an increase in the ionic strength of the solution. With an increase in salt concentration from 1 to 3 M, the BC did not change, which was presumably due to the absence of a change in the amount of unbound PAH with an increase in salt concentration above 1 M.The experiments described above confirm the hypothesis that BC of PMCs depends on the amount of unbound PAH in the composition of microcapsules, since with an increase in the ionic strength of the solution, the number of such sites of the polyelectrolyte became larger. These data could be used to preserve the properties of encapsulated substances during their encapsulation and incubation in solutions of various ionic strengths ,35.3 on pH at different temperatures of preheating.The next stage of the study was the study of BC of PMCs after 60-min incubation at temperatures of 60 and 90 °C. As shown in , when heAs can be seen from the figure, the buffer capacity in the alkaline pH range decreased with an increase in the heating temperature of the microcapsules. This was due to the fact that, at higher heating temperatures, PMCs were more strongly compressed and compacted, and, as a result, the amount of free PAH decreased.Next, we studied BC of PMCs pre-heated at 60 °C and 90 °C, followed by the addition of 1 M NaCl. The results of this study are shown in As can be seen from the figure, the addition of salt to preheated microcapsules led to an increase of BC, and an increase in the ionic strength of the solution led to the destruction of salt bridges between PAH and PSS, which were compensated by heating.The obtained results may allow the adapting of the encapsulation and decapsulation methods of substances based on heating of PMCs. It would enable the saving of the functional properties of encapsulated molecules, for example, in self-healing materials and drug delivery systems after heating ,37,38.Polyelectrolytes polystyrenesulfonate sodium (PSS) and polyallylamine hydrochloride (PAH) with a molecular mass of 70 kDa, ethylenediaminetetraacetic acid disodium salt dihydrate (EDTA) were purchased from Sigma , and sodium chloride, sodium sulfate, sodium carbonate, and calcium chloride from “Reahim”.2CO3 the 0.33 M CaCl2 was added. The stirring time was 30 s. The suspension was maintained until complete precipitation of the formed particles. The process of “ripening” of microspherulites was controlled with the help of a light microscope. Then, the supernatant was decanted, the precipitate was washed with water and used to prepare PMC. The microparticles were obtained with an average diameter of 4.5 ± 1 μm.At stirring of 0.33 M Na3 microspherulites, followed by dissolution of CaCO3. At the moment of dissolution of the CaCO3 core the inner space of the PMC was filled by inter-polyelectrolyte complex. Layer-by-layer adsorption of PAH and PSS on the CaCO3 microspherulites surface was carried out in polyelectrolyte solutions (concentration 2 mg/mL + 0.5 M NaCl). After each adsorption the CaCO3 particles with adsorbed polyelectrolytes were triple washed with a 0.5 M NaCl solution, which was necessary to remove un-adsorbed polymer molecules. The particles were separated from the supernatant by centrifugation. After applying the required number of layers, the carbonate kernels were dissolved in a 0.2 M EDTA solution for 12 h. The resulting capsules were washed three times with water to remove core decay products. The microcapsules were obtained with an average diameter of 4.5 ± 1 μm. The size and number of microcapsules was measured using the dynamic light scattering method on a Zetasizer nano ZS device .The polyelectrolyte microcapsules were obtained by layer-by-layer adsorbing the negatively or positively charged polyelectrolytes onto CaCOFor heating, the microcapsule suspensions were incubated at the respective temperature in a SONIRET thermostat for a 60 min periud.3 (6.6 × 109 microcapsules in 8 mL of water) was titrated with acid or base solutions in the pH range 4 to 9. Titration was done by manual measurement using a pH meter model Hanna pH 211. The acid or alkali (with a concentration of 0.001 M or 0.005 M) was added to the solution to change the pH of a solution by 0.02 or more. Buffering capacity was calculated from Equation (1), after estimating the slope of the titration curves at each point by the variation of the pH between previous and subsequent injections [A suspension of microcapsules (PSS/PAH)jections :(1)BC=CaBC—buffer capacityacid or alkaliC—concentration of HCl of NaOHacid or alkaliV—volume of HCl of NaOHsV—volume of solutioni—number of titrations3 depending on the concentration, and type of salt, as well as preheating of the PMCs. It was found that with an increase in the concentration of NaCl to 1 M the BC of PMCs grew at pH ≥ 5, and an increase in salt concentration above 1 M did not change the BC. Comparison of BC microcapsules in the presence of mono- and di-valent salts of the same ionic strength showed that there was no noticeable difference in almost the entire pH range studied. Only at pH below 4.7 were differences observed that were directly related to BC and the saline solutions themselves. Researching the BC of preheated PMCs showed that it fell more strongly the higher the heating temperature was. The addition of 1 M sodium chloride to heated PMCs led to an increase in the BC. The effects described above confirmed the hypothesis we put forward in our previous work that the buffer properties of microcapsules are determined by uncompensated PAH regions in their composition.In the course of this work, we studied the BC of PMCs’ composition (PSS/PAH)The obtained results are necessary regarding effective encapsulation of pH-sensitive compounds, both in terms of saving functional properties of the encapsulated molecules and for creating a buffer barrier . Furthermore, our results will allow the behavior of PMC and encapsulated substances, depending on the protonation/deprotonation level in different conditions of ionic strength and temperature, to be taken into account.


At present, there are no hardware or biochemical systems that allow to assess the severity of post-COVID syndrome in vivo. The hardware of the proposed biotechnical system is based on routine transthoracic electrical impedance rheography, which makes it possible to register the frequency characteristics of the patient's bioimpedance response to controlled stress stimulation, thereby simultaneously fixing the characteristics of his productive heart, the state of the hemomicrocirculatory bed, the efficiency of the gas transport function of his blood, and also reliably assess personal reactivity and adaptive potential. Subsequent mathematical approximation of the obtained biometric data by an original neural network makes it possible to rank the results obtained and automatically generate a program of medical rehabilitation for a particular patient, depending on the severity of his post-COVID syndrome. The study results proved two reliable physiological signs confirming the presence of latent post-COVID complications: a decrease in the base impedance value for light exercise and an increase in the length of the systolic arc of the rheocardiogram. Considering the permanent detection of new mutations of the SARS-CoV-2 coronavirus, it is safe to assume that the COVID-19 pandemic will last for several more years (from 3 to 8). And in this situation, it is not the disease itself that becomes dangerous, but its consequences described as “post-COVID syndrome” [The long-term presence of a person in post-COVID syndrome due to oxidative stress reactions that trigger the mechanisms of premature apoptosis (death) of cells will ultimately lead to the oncological diseases of organs compromised by COVID-19, with all the ensuing medical, financial and social consequences .Therefore, the development of a special comprehensive biotechnical system (BTS) for assessing the severity of post-COVID syndrome with the calculation of personal rehabilitation since no reliable biochemical markers of post-covid syndrome have been found at present ,5.The pathogenesis of the post-COVID syndrome is based on the systemic suffering of the hemomicrocirculatory bed of tissues and organs, triggered by the processes of thrombus formation due to a radical change in the hemorheological properties of blood , 7, 8. AThe hardware basis of the proposed complex biotechnical system for screening risk-oriented diagnostics of COVID-19 and the post-COVID syndrome was the method of transthoracic electrical impedance rheography (TEIRG), which allows registering the frequency characteristics of the patient's bioimpedance response to a controlled stressor effect, thereby simultaneously recording the characteristics of his productive work of the heart channel, the effectiveness of the blood gas transport function, as well as to reliably assess its reactivity and adaptive potential.The method of transthoracic electrical impedance rheography is based on measuring the modulus of electrical impedance of biological tissue  patient . The max patient .An experimental study of the heart productive work and the state of the hemomicrocirculatory bed by the TEIRG method for diagnosing post-COVID syndrome in volunteers was carried out using the original diagnostic equipment – the ReoCardioMonitor system, which has a Registration Certificate of the Ministry of Health of Russia No. FSR 2010/08720.The ReoCardioMonitor system has the following technical characteristics:Power supply - 220 V ± 10%, frequency 50 ± 0.5 Hz;Power consumption - no more than 20 W;Electrical safety - class II, B;Rheogram measurement method - tetrapolar;Measuring current - 100 kHz, 8 mA;Measurement range of base impedance - 0 – 240 Ohm;Measurement error of base impedance -± 0.2 Ohm;Measurement range of pulse impedance - ± 0.5 Ohm;Measurement error of pulse impedance - ± 0.1 mOhm;Number of channels - 2 (impedance) + 1 (ECG);ECG lead - from rheographic electrodes.In technical terms, the “ReoCardioMonitor” system represents a two-channel impedance measuring converter, a patient's cable system, and a personal computer. The first channel , which is used to calculate and register the impedance signal dZ. External electrodes are required to pass AC ~ I with high frequency and low amplitude. The change in impedance is recorded as a function of time Z(t).The amount of blood in a body segment is inversely proportional to the electrical impedance of that segment: when the volume of fluid in biological tissues increases, the electrical impedance decreases, when the volume of fluid decreases, the impedance increases. Consequently, the electrical impedance changes according to the content of the fluid volume and changes with each heartbeat .If the blood flow to biological tissues causes a proportional decrease in electrical impedance , then thInitially, the study was devoted to the development of a comprehensive biotechnological system (BTS) for determining the state of health and performance of a person against the background of arterial hypertension. The principle of operation of this BTS consists in simultaneous registration of the dynamics of changes in heart rate, respiratory rate and blood pressure by the method of transthoracic electrical impedance rheography (TEIRG) under controlled stress. This methodological approach makes it possible to determine the levels of resistance and reactivity of a biological system, and therefore to assess its adaptive capabilities.One of the tasks of this work was the validation of the mathematical calculation of blood pressure using data of the rheocardiogram systolic arc.The research group consisted of 20 volunteers, randomly selected . The distribution of volunteers by age, which is a key factor in the development of arterial hypertension, was as follows: 20-29 years old - 1; 30-39 years old - 4; 40-49 years old - 2; 50-59 years old - 2; 60-69 years old - 9; over 70 years old - 2. Moreover, the results of a study of the adaptive capabilities of a person by the method of transthoracic electrical impedance rheography in this research group never showed a drop in the value of the base impedance (BI), provided that for each volunteer, the rheogram was recorded sequentially four times under conditions of controlled physical stress. At the same time, the developed mathematical model, according to the rheogram data, perfectly calculated the values of arterial blood pressure. This was confirmed by the results of dispersion and correlation analysis when compared with blood pressure measurement data using a tonometer. This made it possible to reliably speak of a direct relationship between the rheocardiogram systolic arc length with the arterial blood pressure for adult respondents of any gender, weight, height, and age.This entire original biotechnical system did an excellent job of its diagnostic functions until repeated tests, which began in the summer of 2021 during the third coronavirus wave caused by the "omicron"-strain. Then some of our volunteers independently turned to us for diagnostic help in determining their adaptive reserves and the degree of performance in order to find out the principles and methods of rehabilitation after they suffered COVID-19.During the course of repeated tests, the developed mathematical model suddenly began to show some incredibly high values of systolic blood pressure. Moreover, this phenomenon was always recorded immediately after a stressful load and two minutes after recovery. When measured at rest, the arterial blood pressure indicators calculated according to the rheocardiogram systolic arc corresponded to the values measured by the tonometer.It was during the investigation of this paradox that the drop in the value of the base impedance (BI) at volunteers after a controlled physical stress was first recorded. This phenomenon led us to suggest about the relationship between the change in the base impedance after physical stress and post-COVID syndrome.Therefore, for carrying out the research project "Comprehensive biotechnical system for screening risk-based diagnosis of COVID-19 and post-COVID syndrome"  we used a group of 19 volunteers  who previously participated in our study of an integrated biotechnological system for determining the state of health and performance of a human against the background of arterial hypertension.1/2), the value of the base impedance .All of them were checked up by transthoracic electrical impedance rheography using the “ReoCardioMonitor” system to determine the following physiological parameters: heart rate , respiratory rate , rheocardiogram systolic arc length According to the research protocol, the first measurement point was recorded at rest in a sitting position, the second after the maximum breath-holding on inhalation, the third immediately after performing a light physical stress test in the form of squatting or jumping (at the choice of a volunteer) for one minute, and the fourth after two minutes from completing the stress test.www.healthscreens.guru to obtain a conclusion on:To elucidate the mechanisms of “post-COVID” blood circulation, the obtained results of TEIRG in volunteers of both study groups were approximated by special mathematical algorithms of the diagnostic resource The cardiac output of the left ventricle of the heart  and the cardiac output of the right ventricle of the heart ;-5) and the pulmonary vascular resistance ;The systemic vascular resistance ;Index of cardiovascular adaptation ;Index of pulmonary adaptation ;Index of endocrine-metabolic burden ;Body mass index ;The coefficient of activity of basic metabolism ;The coefficient of immediate adaptation ;The coefficient of long-term adaptation ;General desadaptative probability .These integral indicators made it possible to carry out a comprehensive assessment of the functional state of the cardiovascular, respiratory and endocrine-metabolic systems of the volunteers' bodies and their adaptive capabilities.The average time of one complete checkup  was approximately eight minutes.A sign of randomization for the formation of two study groups “Control” and “Experience” was the dynamics of the response of the base impedance value to a light physical stress test: a decrease in the BI value for the “Experience” study group and an increase (or no changes) in the BI value for the “Control” study group.As a result, the experience group included 10 volunteers (5 women and 5 men). The average age of the volunteers in the experience group was 65.3 ± 6.1 years, height - 164.0 ± 10.4 cm, weight - 75.9 ± 7.3 kg.The control group included 9 volunteers (3 women and 6 men). Their average age was 40.1 ± 14.1 years, their height was 177.2 ± 11.0 cm, and their weight was 80.7 ± 11.3 kg.In the experience group, the drop in the average value of the base impedance was from 43.4 ± 15.03 Ohm to 32.7 ± 12.8 Ohm  compared to the base impedance of the control group, where it remained stable or slightly increased: on average from 33.1 ± 5.44 Ohm to 36.4 ± 7.04 Ohm .www.covid19diagnosis.ru before TEIRG to determine this disease in the history of the volunteer within two months before the start of this study. Subsequently, the received digital diagnosis was compared with the medical documents of the volunteers .Following the study protocol, all participants underwent retrospective digital screening diagnostics for COVID-19 using the software www.covid19diagnosis.ru had been ill with COVID-19 about 12 and 18 months ago.As a result of the comparison, it turned out that all volunteers of the experience study group (100%) had COVID-19 in their two-month history, while the volunteers of the Control study group did not have this disease in the variant of retrospective digital screening diagnostics, or according to medical data has not been identified. Two volunteers of the control group were identified who, according to the resource The reason for this is most likely the massive suffering of the patency of the capillaries of the hemomicrocirculatory bed (HMCB) due to micro thrombosis caused by the new coronavirus infection SARS-CoV-2, which is confirmed by numerous pathological studies ,19. FluiConsidering the previously described randomization procedure, two representative data sets were obtained to perform a statistical comparison of the physiological parameters of volunteers who did not have COVID-19 , and volunteers who had had COVID-19 .The numerical data of these statistical samples were found to be sufficient and representative.To perform statistical analysis, nonparametric tests were used: for variance comparison - the Mann-Whitney test (u); for the correlation one - the calculation of the Spearman's rank correlation coefficient (rs).The results of comparing the average values of indicators of central hemodynamics, rheocardiogram and integral indicators of the functional state of the cardiovascular, respiratory and endocrine-metabolic systems of the body of the volunteers of the control and experimental groups with their adaptive capabilities are presented in So, the first statistically significant difference in the performance of the experimental and control groups recorded in the study was a significant drop in the base impedance in volunteers with COVID-19 against the background of their physical stress test. This condition can be characterized as a sudden accumulation of fluid at the levels of the hemomicrocirculatory bed (HMCB), caused by physical activity, which led to an increase in the electrical conductivity of biological tissues.Under normal conditions, HMCB capillaries’ function “step-by-step” 25-30% of their total number. In case of a stressful need, new “portions” of capillaries are connected to active tissue gas exchange, which contributes to the successful implementation of the increasing tension of the gas transport function of the circulatory system. After recovering from stress, the number of actively working capillaries decreases to normal [With COVID-19, the number of normally functioning capillaries progressively decreases depending on the severity of the disease, causing inhibition of tissue gas exchange and increased suffering in the gas transport function of blood. Considering the increased tropism of the SARS-CoV-2 coronavirus to vascular endothelial cells and its direct toxic effect on the red hematopoietic germ, it was surprising that there were no statistically significant differences in the total peripheral vascular resistance in both circles of blood circulation in the volunteers of the experimental and control research groups. However, an increase in the minute volume in the right ventricle of the heart and the volume of circulating blood in volunteers who had recovered from COVID-19  confirmeThis means that there are currently no specific clinical symptoms or functional signs for diagnosing the severity of the condition of patients after COVID-19 at the primary health care level . And theThis medical fact was confirmed by the absence of statistically significant differences in the mean values of the coefficient of immediate adaptation (CIA) , the coefficient longterm adaptation (CLTA)  and general adaptation probability (GAP)  in the volunteers of the “Experience” and “Control” study groups . At the A varied clinical performance, called the “post-COVID syndrome”, manifests itself in patients 2-3 months after COVID-19, when it is no longer possible to establish a causal relationship with this disease. It is for this reason that the pathogenesis and specific clinical signs of the post-COVID syndrome have not yet been differentiated .This study did not find statistically significant differences in systolic (SBP) and diastolic (DABP) arterial blood pressure, heart rate (HR) and respiratory rate (RR) between control and COVID-19 volunteers ".Thus, based on the results of this study, in addition to a significant drop in the baseline impedance to physical activity due to fluid retention at the HMCB level due to capillary microthrombosis, statistically significant differences were also found in the length of the systolic arc of the rheocardiogram in volunteers with COVID-19 , and there was also a significant increase in the cardiac output of the right ventricle of heart  and circulating blood volume  against the background of increased body mass index (BMI), index of endocrine-metabolic burden (IEMB) and coefficient of activity of basic metabolism (CABM).To study these clinical phenomena, Spearman's rank correlation analysis (rs) was used.0) are strongly inversely correlated . The respiratory rate (RR) are strongly inversely correlated with L0 .Based on its results, it became clear that in the “Control” study group, the heart rate (HR) and the length of the systolic arc of the rheocardiogram .0) is maintained at the expense of heart rate and RR, regulated by the vasculomotor and respiratory centres of the medulla oblongata.And this is a normal in vivo picture, when the effective gas exchange function of blood circulation at the level of HMCB  is that they are excited both reflexively by nerve impulses coming from the periphery, and by chemical stimuli acting directly on them .In the “Experience” study group, a radically different relationship between clinical signs was revealed.0) was strongly correlated inversely with the systolic component of blood pressure (SBP)  and heart rate (HR) . At the same time, heart rate was found to be associated with SBP , but not with the respiratory rate (RR) , which completely contradicts the fundamental basics of blood circulatory physiology.The length of the systolic arc of the rheocardiogram  remain in the normal range, creating the illusion of somatic well-being, while the biological tissues damaged by SARS-CoV-2 undergo fibrous involution with subsequent sclerotic degradation due to the previously transferred “cytokine storm” and increasing chronic tissue hypoxia caused by blocking the mechanisms of gas exchange and blood circulation at the levels of the hemomicrocirculatory bed due to microthrombosis.0), which allows the use of the method of transthoracic electrical impedance rheography (TEIRG) for the preventive diagnosis of the development of “post-COVID syndrome”.The study results proved that people who have undergone COVID-19 have two reliable physiological signs confirming the presence of latent post-COVID complications: a decrease in the base impedance (BI) value for light exercise and an increase in the length of the systolic arc of the rheocardiogram (L