Critical Value Research Articles

Heat exchange under the longitudinal movement of wet steam in finning heat exchangers

The paper is devoted to the study on hydrodynamics and heat exchange of two-phase medium. While designing technological equipment, when the wet steam is used as the operating medium, the features of the interaction between liquid drops and the heat exchange surface are not considered in most cases. In full, this applies to steam turbines operating on the wet steam whose moisture content depends on the primary and secondary removal of liquid drops from the separation blocks. Purpose. Improving the method of calculation of recuperative heat exchangers, if wet steam is used as the operating medium. Methodology. It is based on the analysis of the physical model of moving the two-phase medium in the heat and mass exchange conditions, considering the design characteristics of the heat transfer surface. Findings. The correlation of critical values of two-phase flow parameters was obtained to determine the lower boundary of the process of plucking the drops from the liquid film depending on the irrigation density, geometric characteristics of the channel and physical properties of the liquid and gas. Correlations were obtained for pipes with longitudinal finning as the Π-shaped profile, based on which we recommend optimizing the geometric characteristics of longitudinal finning. Originality. Determining the limit modes of secondary removal formation during the movement of a two-phase medium in separation devices and the features of heat and mass transfer of wet steam in finning recuperative heat exchangers. Practical value. The presented results make it possible to optimize the design of recuperative heat exchangers with longitudinal Π-shaped finning.

Propagation of collisional among multi-soliton, multi-singular solition and rogue wave around the critical values in an unmagetized plasma

Progress in understanding the propagation characteristics of (i) collisional acoustic among multi-soliton and multi-singular soliton around the critical values and their corresponding phase shifts and (ii) collision between two rogue waves (RWs) propagating toward each in a plasma environment is presented. The considered plasma environment consists of mobile cold positrons, immobile positive ions and (r, q)-distributed hot positrons, and electrons. To accomplish our goal, the coupled modified Korteweg–de Vries equations (mKdVEs) and nonlinear Schrödinger equations (NLSEs) are derived from the considered plasma environment. Based on the concept of Hirota's bilinear method, the multi-soliton and multi-singular soliton solutions of the coupled mKdVEs are determined directly. In addition, the analytical unstable RWs solutions of the coupled NLSEs are determined. With the impact of physical parameters, (i) the trajectories are described for double, triple, quadruple and quintuple positron acoustic bi-directional multi-soliton and (ii) the variation of collisional RWs profiles are displayed with physical interpretation. The results described by the coupled mKdVEs also show that the scattered double-, triple-, quadruple-, and quintuple-soliton are elastic and preserved their original features oppositely after the collision around the critical value of any specific plasma parameter.

Improving the technology for constructing a software tool to determine the similarity of raster graphic images

The object of research is the process of searching and analyzing images of raster graphics. In the context of this work, the problem of the lack of an effective and fast procedure for determining the similarity of images was solved. The technology for improving the construction of a software tool for determining the similarity of raster graphics images by devising a procedure for determining the similarity of images using a hash code that corresponds to all variants of the image, regardless of size and aspect ratio, is reported. The image features of raster graphics were systematized. A procedure for determining the similarity of images using a hash code is proposed. This procedure makes it possible to process all possible variants of the image, regardless of the size and aspect ratio. The resulting indicator of the proposed procedure is the value of the hash codes. It is proposed to use the mathematical apparatus of fuzzy logic by introducing linguistic variables to estimate the similarity index. A comparison of the numerical values of similarity, obtained on the basis of the use of information systems, and the linguistic values revealed in the survey process was carried out. Threshold values were obtained that make it possible to assess the degree of similarity of the images. Based on the proposed algorithm, a prototype of the information system for determining the similarity of images of raster graphics has been designed. As a result of the calculation of the numerical characteristics of the improvement of the technology of constructing a software tool for determining the similarity of images of raster graphics, the value of the precision indicators was approximately 0.89 and the completeness was 0.8. The advantage of the proposed technology for determining the similarity of images over known analog technologies is illustrated by the amount of RAM of the developed software, which is 210 MB

Psychometric properties of a Saudi Arabian version of the Birth Satisfaction Scale-Revised (BSS-R).

Maternal outcomes are closely associated with birth satisfaction, and the Birth Satisfaction Scale-Revised (BSS-R), a concise, multidimensional self-report measure, has undergone translation and validation internationally. However, research on birth satisfaction in Saudi Arabia is scarce. The absence of valid Arabic-language tools for the Saudi population may impede critical research on this topic, necessitating the translation and use of psychometrically sound instruments for measuring birth satisfaction in Saudi women. This study aimed to translate and evaluate the psychometric properties of the Saudi Arabian version of the BSS-R (SA-BSS-R). A total of 218 Saudi women participated in the study, and psychometric analysis of the translated SA-BSS-R involved confirmatory factor analysis, divergent validity analysis, and known-group discriminant validity assessment within a cross-sectional study design. The three-factor BSS-R measurement model displayed poor fit, and internal consistency fell below the threshold value. Additionally, it was observed that women undergoing an episiotomy had significantly lower overall SA-BSS-R scores. The SA-BSS-R manifested atypical measurement properties in this population. Despite insightful observations related to episiotomy, the identified measurement shortcomings highlight the need for a more robust and culturally sensitive translation to enhance measurement characteristics.

Performance assessment of a new G12/A1 antibody-based rapid ELISA using commercially available and gluten-spiked food samples.

Food products with <20 mg/kg gluten can be labeled 'gluten-free' according to international regulations. Several antibodies-based ELISAs have been develop to track gluten traces in food products. Among them, R5 and G12 antibody-based ELISAs are the frequently used methods. However, these antibodies have certain limitations. We evaluated the accuracy of G12/A1 antibody-based 'Glutentox ELISA Rapid G12' and compared the results with the current reference method i.e., R5 antibody-based 'Ridascreen R5 ELISA'. In the first step, the performance of Glutentox ELISA Rapid G12 kit was inspected by determination of the threshold value i.e., > or <20 mg/kg gluten in different food products. In the second step, quantification accuracy was assessed by quantification of gluten in gluten-free food products spiked with gliadin reference material. In total 47 food products (naturally and labeled gluten-free, and food with traces of gluten) were included. Of them, 29 products were quantified with <20 mg/kg, and 18 with a low level of gluten by both the kits. Six out of 29 gluten-free products were used for the recovery test at different spike levels. Gluten concentration and mean recovery rates of individual kits showed consistency. GlutenTox Rapid G12 ELISA could be an appropriate choice for detecting gluten in food products but needs more in-house validation and collaborative tests.

Heat and cold waves on the Crimean Peninsula and their impact on population health

BACKGROUND: Climate change has a significant impact on the population health including morbidity and mortality. The studies presented in this paper present characteristics of heat and cold waves on the Crimean Peninsula.&#x0D; AIM: To assess the heat and cold wave characteristics, identify differences in the wave characteristics depending on the coastal and mainland location of climatotherapeutic centers on the Crimean Peninsula.&#x0D; MATERIAL AND METHODS: In our research we used standard statistical data treatment methods. Moreover, data visualization techniques allowed identifying zones of maximum temperature values. Heat and cold waves were defined using the 3rd and the 97th percentiles of the average daily air temperatures. This approach allows considering the intensity and duration of the events under study. Measurements of the surface air temperature included eight observations per day at 19 stations on the Crimean Peninsula for the period from 2006 to 2021. Distribution of the permanently residing population in the Crimea and the city of Sevastopol by age and gender was analyzed using the Rosstat data.&#x0D; RESULTS: As many as 43.5% of the population of the Crimean Peninsula have increased risk of exposure to extreme air temperatures. Having applied the threshold values of the 3rd and the 97th percentiles of the temperature, we identified the periods of heat and cold waves at each station. Even though the Crimean Peninsula has a warm and humid climate, 1 to 4 cold and heat waves have been observed at each station per year. At the same time, the total intensity of cold waves was more than twice the total intensity of heat waves.&#x0D; CONCLUSION: The presented assessment of heat and cold wave characteristics on the Crimean Peninsula, using 3% and 97% percentiles of the distribution of the average daily air temperature over several years, provides the evidence for developing the measures to reduce the negative impact of extreme temperatures on human health on the Crimean Peninsula.

A Study on the Establishment of Alternative Verification Standard of Ballistic Ttest for Armored Steel Arc Welding Procedure

The final goal of this study is to secure the basis for establishing a domestic test standard such that the H-plate ballistic test for weld verification required by TACOM Drawing 12479550 can be replaced with the Charpy impact test. The core of this study is to prove the correlation between the ballistic test and the impact test. As a result of ballistic test specimens manufactured with various welding parameters, the generated crack length showed a correlation of approximately 78% with impact toughness. In addition, cracks occurred at the weld toe and propagated along the fusion line irrespective of any variables. Therefore, the notch location of the impact test specimen was determined by the fusion line. Moreover, experiments proved that impact toughness did not change significantly when changing non-essential welding variables. The impact toughness of the fusion line critical values of MIL-A-12560 and MIL-A-46100 materials used in this study were 50 J and 22 J, respectively. This value exceeded the impact toughness management standard for the base material. Therefore, the passing threshold value was ultimately determined to be above the impact toughness threshold of the base material.

Shelf Life and Functional Quality of Almond Bagasse Powders as Influenced by Dehydration and Storing Conditions.

Almond bagasse resulting after the production of almond-based drinks represents a promising by-product with potential for use as a functional ingredient. To facilitate its utilization, the stability of this material can be achieved through dehydration processes such as hot air drying or freeze-drying. Nevertheless, owing to its high fat content, almond bagasse is prone to lipid oxidation, which could result in undesirable quality. Therefore, the objective of this work was to assess the impact of dehydration (by hot air drying at 60 and 70 °C and by freeze-drying) and storage (at room temperature and in accelerated conditions) on the functional quality and stability of almond bagasse powder. Throughout the dehydration process, it was observed that antioxidant compounds were preserved without significant differences among dehydration treatments. These compounds increased over the storage period, especially in the samples treated with hot air. Regarding antiradical capacity, the hot-air-dried samples showed higher values than the freeze-dried ones, although in all cases, it increased during storage. For total phenols in samples air-dried at 70 °C, increases of more than 50% were observed. The acidity and peroxide index were increased in the extended storage period, although they did not reach critical values. Samples stored for 180 days showed peroxide values ranging from 10 to 12.8 meq O2/kg dry matter for samples stored at room temperature and from 14.7 to 23 meq O2/kg dry matter for samples subjected to accelerated storage.

Study on the dynamic thermal response of phase change material integrated wall under indoor-outdoor dual thermal disturbances

The study mainly explored the dynamic thermal response of phase change material integrated wall (PCMW) under indoor-outdoor dual thermal disturbances (IODTD). A dual wave thermal disturbance dynamic boundary condition was proposed for PCMW based on the outdoor meteorological data and typical solar energy building analytical models of Lhasa, Yinchuan and Xi'an in China. The influence of different construction modes on the thermal performance of PCMW was numerically investigated by the sensible heat capacity method under IODTD. Then determined the crucial thermophysical parameters of PCM and analyzed the variation characteristics of temperature and heat flux fields of PCMW. The heat transfer frequency responses of different walls to outdoor thermal disturbances were calculated by the harmonic response method. The results indicated that the optimal location of PCM was on the interior side of the wall, and the critical values of phase change temperature and latent heat were 16 °C and 120 kJ/kg, respectively. It presented the maximum temperature and heat flux were 10 % and 36.2 % greater than ordinary walls (OW). Compared with OW, the attenuation and delay time of PCMW on outdoor sol-air temperature wave performed significantly, which plotted a higher decrement factor and longer time lag under external disturbances of different orders.

Effect of waste dumpsite on the surface and groundwater supplies using water quality index in Afikpo south local government area, Ebonyi state

The research examined the effect of waste dumpsite on the surface and groundwater supplies using water quality index (WQI) in Afikpo South Local Government Area of Ebonyi State. Fifteen samples were drawn from fifteen locations. The samples were analyzed using standard methods. The results of the analyses were compared with the World Health Organization (WHO) drinking water standard. The WQI of the water samples were calculated and compared with the classification of water quality status. The results showed that the pH of the water samples ranged 4.6±0.047 – 6.70±0.090, EC 7.26±1.63 – 2450±4.32, Turbidity 0.50±0.082 – 2.00±0.094, TDS 23.10±0.047 - 1830±17.00, Alkalinity 45±0.47 - 2080±4.71, Total Hardness 4±0.47 – 170±0.94, DO 5.07±0.012 – 7.72±0.016, BOD 0.4±0.047 – 12.8±0.082, NO3 - 1.14±0.009 – 32.69±0.047 and 0.09±0.00 – 15.6±0.028. The results showed that the pH, Turbidity, Total Hardness, NO3 - were all below the WHO drinking water standard. All the locations of the water samples showed some levels of acidity. Apart from location MB that recorded high levels of TDS and Alkalinity every other location was below the WHO permissible limit of drinking water standard. The results of the analysis also revealed that the WQI value of the water was 57.92 and this was below the critical value of 100. From the findings, all the water samples need to be treated with alkali to reduce the low pH while the water samples generally need to be given comprehensive treatment before usage.

Analysis of the Effect of an Open Hole on the Buckling of a Compressed Composite Plate.

This paper investigates the effect of an open hole on the stability of a compressed laminated composite plate. The study was carried out in two ways: using experimental tests and numerical analysis. As a result of the experiment, the buckling form and path of the plate were recorded. The form of buckling was determined using the ARAMIS non-contact measurement system. The critical load value was determined from the working path using the approximation method. The experimental results were verified by numerical analysis based on the finite element method. FEM investigations were carried out in terms of a linear eigenproblem analysis. This allowed the bifurcation load and the corresponding buckling form of the numerical model of the plate to be determined. Investigating the effect of the hole in the compressed plate at a critical state showed high agreement between the proposed test methods. No clear effect of the hole size on the buckling of the plate was observed. In contrast, a clear effect of the hole on the critical load value was determined. The maximum decrease in the critical load value was 14%. The same decrease was observed for the stiffness of the post-critical characteristics. It was shown that the [45|-45|90|0]s composite plate had more than three times lower strength compared to [0|-45|45|90]s and [0|90|0|90]s. The novelty of this article is the development of a research methodology based on new interdisciplinary research methods for describing the influence of the central hole on the stability of compressed composite plates. The ABAQUS system was used for the numerical analysis.

Endocrine disrupting chemicals in Italian drinking water systems: Insights from a three-year investigation combining chemical and effect-based tools

Drinking water quality can be compromised by endocrine-disrupting chemicals (EDCs). Three phenolic compounds [bisphenol A (BPA), nonylphenol (NP), and 4-octylphenol (OP)] and three hormones [17β-estradiol (E2), estrone (E1), and 17α-ethinylestradiol (EE2)] were analyzed as EDCs potentially occurring in source and drinking water from three full-scale drinking water treatment plants (DWTPs) in the Romagna area (Italy) by a combined approach of HPLC-MS/MS target analysis and effect-based tests for estrogenicity and genotoxicity. The EDC removal efficiency was evaluated at different steps along the treatment process in the most advanced DWTP. NP prevailed in all samples, followed by BPA. Sporadic contamination by OP and E1/E2 appeared only in the source waters; EE2 was never detected. No estrogenic or genotoxic activity was found, except for two samples showing estrogenicity well below the effect-based trigger value suggested for drinking water safety (0.9 ng/L EEQ). BPA and NP levels were largely below the threshold value; however, increases were observed after the intermediate steps of the treatment chain. The good quality of the water relied on the last step, i.e. the activated carbon filtration. DWTPs may represent an extra source of EDCs and monitoring chemical occurrence at all steps of the process is advisable to improve efficiency.

Surface Degradation of Ion-releasing Restorative Materials With Cariogenic Challenge.

This study examined the influence of cariogenic environments on the surface roughness of ion-releasing restorative materials (IRMs). Custom-made stainless steel molds with holes of 5 mm × 2mm were used to fabricate 60 disc-shaped specimens of each of the following materials: Activa Bioactive (AV), Beautifil Bulk Restorative (BB), Cention N (Bulk-fill) (CN), and Filtek Z350XT (FZ) (Control). Baseline surface roughness (Ra) measurements were obtained using an optical 3D measurement machine (Alicona Imaging GmbH, Graz, Austria). The specimens were then randomly divided into five subgroups (n=12) and exposed to 10 ml of the following mediums at 37°C: distilled water (DW), demineralization solution (DM), remineralization solution (RM), pH cycling (PC) and air (AR) (control). Ra measurements were again recorded after one week and one month, followed by statistical evaluations with two-way analysis of variance (ANOVA) to determine interactions between materials and mediums. One-way ANOVA and post hoc Games Howell tests were performed for intergroup comparisons at a significance level of 0.05. Mean Ra values ranged from 0.085 ± 0.004 (µm) to 0.198 ± 0.001 µm for the various material-medium combinations. All IRMs showed significant differences in Ra values after exposure to the aqueous mediums. The smoothest surfaces were observed in the AR for all materials. When comparing materials, AV presented the roughest surfaces for all mediums. All IRM materials showed increased surface roughness over time in all cariogenic environments but were below the threshold value for bacterial adhesion, except for AV 1-month post immersion with pH cycling. Therefore, besides AV, the surface roughness of IRMs did not deteriorate to an extent that it is clinically relevant.

Analisa Kebisingan Pada Alat Berat Wheel Loader Wa-350 Berdasarkan Perbandingan Jarak 50, 100, 150 Cm Dan Kapasitas

Wheel loader is a tool that facilitates work by using hydraulic energy. Wheel loader testing is carried out by looking for noise data arising in the combustion chamber. There are several stages that must be done, namely the first step is to prepare a sound level meter as a noise detection device for heavy equipment, wheel loader, then take measurements with several variations in the distance between the combustion chamber and the sound level meter. In the next step we can find out the noise level read at the sound level meter with ideal, medium, and maximum rotation on the WA-350 wheel loader. So that the Noise Threshold Value according to Permenaker No. per-51 / MEN / 1999, ACGIH, 2008 and SNI 16-7063-2004 is 85 dB. So the noise produced by the Wheel Loader above the NAB Permenaker 104.7dB can cause tingling, unwell, hearing saturation, stomach pain, and circulatory problems. It is recommended that workers are required to use earmuffs or ear muffs.

Diagnostic utility of point-of-care ultrasound and optical coherence tomography for papilloedema in children: a prospective pilot study

Background/AimsPapilloedema is an important sign of serious neurological disease, but it can be difficult to detect on funduscopy. The purpose of this study was to determine the diagnostic accuracy of...

Derivation and validation of a quantitative risk prediction model for weaning and extubation in neurocritical patients.

Patients with severe neurological conditions are at high risk during withdrawal and extubation, so it is important to establish a model that can quantitatively predict the risk of this procedure. By analyzing the data of patients with traumatic brain injury and tracheal intubation in the ICU of the affiliated hospital of Hangzhou Normal University, a total of 200 patients were included, of which 140 were in the modeling group and 60 were in the validation group. Through binary logistic regression analysis, 8 independent risk factors closely related to the success of extubation were screened out, including age ≥ 65 years old, APACHE II score ≥ 15 points, combined chronic pulmonary disease, GCS score < 8 points, oxygenation index <300, cough reflex, sputum suction frequency, and swallowing function. Based on these factors, a risk prediction scoring model for extubation was constructed with a critical value of 18 points. The AUC of the model was 0.832, the overall prediction accuracy was 81.5%, the specificity was 81.6%, and the sensitivity was 84.1%. The data of the validation group showed that the AUC of the model was 0.763, the overall prediction accuracy was 79.8%, the specificity was 84.8%, and the sensitivity was 64.0%. These results suggest that the extubation risk prediction model constructed through quantitative scoring has good predictive accuracy and can provide a scientific basis for clinical practice, helping to assess and predict extubation risk, thereby improving the success rate of extubation and improving patient prognosis.

Shift in the quantitative relationship between sedimentary records and catchment floods influenced by dam construction

Interpretation of sedimentary records is a crucial method for studying paleo-floods. However, the response intensity of sedimentary records to floods may be altered by reservoir storage. Therefore, depicting flood intensity in sedimentary records and alterations in the response relationship is the primary challenge in paleo-flood reconstruction. This study used the Yalu River catchment–estuary–coast as the research area and quantitatively reconstructed the response relationship between sediment grain size composition and flood intensity. This was conducted through a combination of forward simulation of the HYDROTREND hydrological model and reconstruction of sedimentary records, as well as evaluating the impact of reservoir regulation on the quantitative relationship. The findings showed that the lower Yalu River channel and tidal flat were both efficient at preserving flood records. However, there were significant differences in the response of different geomorphic units to floods. The river channel showed a significant increase in the coarse-sensitive component, whereas the tidal flat exhibited a substantial increase in the fine-sensitive component. Further study showed that there was a significant logarithmic relationship between the content of the fine-sensitive fraction and flood intensity. The sensitivity of the fine-sensitive fraction towards small floods was much higher than that toward extreme floods. In addition, reservoir construction caused a significant shift in the relationship between flood intensity and flood-related sensitive sediment fractions. Consequently, the reconstructed flood intensities of the pre-dam construction showed diverse levels of magnification based on the quantitative relationship between the sedimentary record and flood intensity of the post-dam. Meanwhile, this shift led to an increase in flood intensity corresponding to the critical value of the flood record that could be detected: from floods with a return period exceeding two years before dam construction to floods with a return period exceeding five years after dam construction. This study has quantitatively reconstructed the relationship between sediment grain size fractions and flood intensity and assessed the impact of reservoir construction on the quantitative relationship. It has also provided new ideas for more accurate reconstruction of paleo-flood intensity changes in the future.

COVID-19 and multiple sclerosis: is there a connection?

Multiple sclerosis (MS) is a chronic immune-mediated disease of the central nervous system, which is based on inflammatory demyelination and neurodegeneration. Over the course of the COVID-19 pandemic, there has been a perception that the virus has an effect on the course of immune processes. The questions of whether the frequency of autoimmune diseases, including the nervous system, and their course has changed have been discussed. Aim of the study was to assess the clinical and epidemiological characteristics of MS during the COVID-19 pandemic from 01.01.2020 to 01.01.2023 in Novosibirsk. In the course of our work, we studied the incidence of MS and the features of the clinical picture of the debut of MS associated with COVID-19 infection. Material and methods. The study included 628 patients with MS living in Novosibirsk with the onset of the disease in the period before the pandemic from 01.01.2017 to 12/31/2019 (341 patients) and during the pandemic from 01.01.2020 to 01.1.2023 (287 patients). Results. The incidence rates of MS in Novosibirsk were calculated, it was 7.1 7.6 6.4 7.38 6.92 and 3.2 per 100 thousand population in 2017, 2018, 2019, 2020, 2021 and 2020, respectively. The average incidence of MS in the study period before the pandemic was 7.03 per 100 thousand population, during the pandemic – 5.83 per 100 thousand population (critical value of the Student’s t-test = 1.972, with a significance level of a = 0.05). When analyzing the association of clinical manifestations of the onset of MS with COVID-19, it was found that coordination disorders were observed in patients with moderate infection more often than in patients with mild infection (p &lt; 0.05; odds ratio 0.410, 95% confidence interval 0.162–1.035). No statistically significant correlation of clinical manifestations with the severity of infection was shown for patients with primary progressive MS, however, the predominance of the multi-focal nature of disease after a more severe course of COVID-19 was noted (40 %). After the first clinical demyelinating episode in the group of patients with relapsing-remitting MS, the chances of complete recovery in patients with mild infection are 2.8 times higher than in patients with moderate infection (p &lt; 0.05). Conclusions. Thus, as a result of the conducted study, the effect of COVID-19 on the change in the incidence of MS was not revealed. In the process of analyzing the clinical features of MS during the pandemic, it was found that COVID-19 infection can contribute to an unfavorable course of MS with worse recovery of neurological deficits after episodes of exacerbations, which leads to the accumulation of disability of patients.

Pulmonary Venous Index as Additional Diagnostic Criteria for Fontan Palliation

Backgroud. The results of the Fontan operation, depending on the anatomy of the pulmonary arteries, have been studied quite well. Various indices have been proposed to assess the degree of hypoplasia of the pulmonary arterial bed (Nakata, Reddy, and McGoon indexes). At the same time, an obstruction of pulmonary venous blood return may be considered as a contraindication to Fontan operation. Aim of the Study. To present an optimal method for pulmonary venous index (PVI) calculation based on computed tomography angiography (CTA) enhancement of the heart data in patients with a functional single ventricle. Materials and Methods. 63 patients with a functional single ventricle (SV) underwent CTА (Philips, Brilliance iCT) before the Fontan operation. Axial sections were reconstructed to a thickness of 0.75–3 mm using soft tissue and lung filters, followed by postprocessing of the data (Horos and OsiriX software) and construction of multiplanar and 3D images. The diagnoses were presented by various types of SV of the heart. The age of the patients ranged from 3 to 30 years (median 7 years). Comparison of PVI was carried out in patients of two groups: those who survived the intervention (n = 55 patients) and those who died (n = 8). The evaluation of the pulmonary veins (PV) and the calculation of the pulmonary venous index (PVI) were carried out based on the measurement of each pulmonary vein at 2 levels (at the level of the orifices and bifurcation). The calculation of the PVI was carried out according to the formula: the sum of the cross-sectional area of the main pulmonary veins, related to the body surface area. 3 variants of PVI calculation were compared: taking into account the values of the PV areas at the level of the orifices, the bifurcation, and the sum of the minimum areas of each of the PVs. Results. In the group of survived patients, the median PVI at the level of the PV orifices was 292 mm/m2, and in the group of deceased, it was 242 mm/m2p=0.0326; at the level of PV bifurcation in the group of survivors, it was 299 mm/m2, and in the group of dead patients, it was 281 mm/m2p=0.0776; the minimum PVI was 257 mm/m2 in the survivor group and 218 mm/m2 in the deceased group p=0.006. An ROC analysis performed to determine the critical value of the minimum PVI affecting survival after Fontan operation revealed that PVI measured taking into account the minimum dimensions of the areas of the PV is a significant risk factor for death after Fontan operation p=0.00015, with its value (cutoff) &lt;233.5 mm2/m2. Conclusion. The value of the minimum PVI can be an important morphological indicator of the state of PV blood return and serve as an additional criterion in determining indications for the Fontan operation.

Mechanical properties of Q355 hot-rolled steel during the entire fire process

This study conducts steady-state tests to comprehensively examines the mechanical properties of Q355 hot-rolled steel throughout the entire fire process, including the cooling stage. Results show that the mechanical properties at the fire-cooling stage are influenced by both the peak heating temperature (Tp) and the tensile test temperature (Tt). Within a specific threshold value of Tp, the mechanical properties at the cooling stage of fire resemble those observed in the heating stage. However, when Tp surpasses this threshold value, notable disparities emerge between the mechanical properties of steel at the cooling and heating stages. The threshold temperatures for elastic modulus, ultimate strength, and ultimate strain are all 600 °C, while that for the yield strength f0.2 is 400 °C. A cooling stage influence coefficient is used to quantitatively portray the variance in mechanical properties between the cooling and heating stages of fire. Calculation formulas for the fire cooling stage influence coefficients were provided for the elastic modulus, yield strength f0.2, ultimate strength, and ultimate strain, respectively. Finally, a constitutive model for the entire fire process of Q355 steel was established.