Polyethylene (PE) is widely used in pipeline transportation owing to its excellent corrosion resistance, good stability, and ease of processing. As organic polymer materials, PE pipes inevitably undergo different degrees of aging during long-term use. In this study, terahertz time-domain spectroscopy was used to study the spectral characteristics of PE pipes with different degrees of photothermal aging, and the variation in the absorption coefficient with aging time was obtained. The absorption coefficient spectrum was extracted using uninformative variable elimination (UVE), successive projections algorithm (SPA), competitive adaptive reweighted sampling (CARS), and random frog RF spectral screening algorithms, and the spectral slope characteristics of the aging-sensitive band were selected as the evaluation indices of the degree of PE aging. Based on this, a partial least squares aging characterization model was established to predict white PE80, white PE100 and black PE100 pipes with different aging degrees. The results showed that the prediction accuracy of the absorption coefficient spectral slope feature prediction model for the aging degree of different types of pipes was greater than 93.16% and the verification set error was within 13.5 h. Polyethylene (PE) is a type of high polymer material with corrosion resistance, high toughness, long life, and stable properties, and is widely used in medium- and low-pressure gas pipelines, water supply, and drainage pipelines in cities and towns. In the course of its use, PE is often affected by light, temperature, oxygen, humidity, pressure, and other factors, resulting in a decline in the mechanical properties and the polyethylene molecular chain breaks of aging pipes, gas leakage, and accidents, causing serious economic losses ,2,3. CurAt the end of the 20th century with the development of optical devices, spectral detection research has been broadened to the terahertz (THz) field . Chang eIn this study, the characterization and prediction of the photothermal aging degree of PE pipes for outdoor use were studied based on terahertz time-domain spectroscopy ,14. Firs2, a black standard temperature of 65 ± 3 °C, and a relative humidity of 65% ± 10%. The dry-wet cycle was 102 min of drying and 18 min of spraying [PE pipes used for gas pipes and water pipes are mainly PE80 and PE100, which can maintain the minimum strength of 8.0 MPa and 10.0 MPa after 50 years of use at 20 °C. To better simulate the aging of PE pipes in the practical application of perennial exposure to outdoor use, white PE80, white PE100, and black PE100 pipes were selected for comparative experiments with a length and width of 20 × 100 mm and a thickness of 3 mm. According to the national standard GB/T 16422.2-2022, the PE pipes were subjected to accelerated aging in a xenon lamp aging test chamber. An imported air-cooled Xe arc light source was used in the test chambers. The spectral wavelength ranged from 280 to 800 nm. The experimental conditions were irradiance of 50 W/mspraying . The nozThe terahertz time-domain spectroscopy system used in this study was an Advantest model TAS7500SP spectrometer, as shown in Assuming that the thickness of the sample is According to the Fresnel coefficient, the transfer function of the material is:The equations for calculating the refractive index, extinction coefficient, and absorption coefficient of the samples are as follows ,17:(2)n1−1, and the absorption peak of black PE100 was larger, approximately 4 cm−1, indicating that the density of the PE pipe had little effect on the absorption coefficient, and the effect was greater after adding carbon black masterbatch. The frequency domain waveform after the absorption peak decreased with an increasing aging time, and the absorption coefficients of some aging times overlapped. In the same artificial aging environment, the absorption coefficient of white PE80 was more evident than that of white PE100, indicating that the aging resistance of white PE100 was stronger owing to the high density of PE. The absorption coefficient of black PE100 was significantly lower than that of white PE100, confirming that black PE100 containing a carbon black masterbatch can effectively prevent the PE molecular chain from being damaged by ultraviolet light and is not easy to age.Equation (4) was used to calculate the absorption coefficients of the three types of PE pipe samples with different aging times. Because of the internal electrical noise and background stray light of the spectrometer, the absorption coefficient was SG-smoothed before imaging analysis to eliminate the influence of curve fluctuations on the results in the selected interval . ConsideThe influence of more THz spectral data band points and a large amount of data may affect the subsequent modeling and prediction effects. Wavelength screening is typically used to eliminate redundant information in the THz spectrum to extract effective features, thereby improving the modeling efficiency and reducing the amount of calculation. In this study, four spectral band screening methods—uninformative variable elimination (UVE) , successThe spectral sensitivity range of the PE pipe was 1.5–4 THz, resolution was 0.0075 THz, and number of bands was 329. As shown in Most of the wavelengths of the three types of pipes after screening were in the range of 2.5–4 THz. The wavelengths of UVE, SPA, CARS, and RF of white PE100 were in the range of 2.5–4 THz and accounted for 86%, 90%, 83%, and 75%, respectively, and the wavelengths of the other two PE pipes accounted for more than 75%. Therefore, this paper used polynomial fitting method to fit the absorption coefficient curves of three PE pipes in the range of 2.5–4 THz with 0.25 THz as the interval. The slope change curve after fitting is shown in The slope of the three PE pipes decreased with the increase of aging time in the range of 2.5–4 THz, and the slope of the aging absorption coefficient of white PE80 in 2.5–2.75 THz and 2.75–3 THz was linear with the aging time. The aging absorption coefficient slope of white PE100 at 2.5–3 THz and 3–3.25 THz was linear with the aging time. The slope of aging absorption coefficient of black PE1000 in 2.5–2.75 THz, 2.75–3 THz and 3–3.25 THz was linear with aging time. The proportions of the filtered wavelengths in the linear range are shown in It can be seen that the average wavelength of 64.7% after spectral-feature band screening coincided with the linear relationship interval of the spectral slope. A band with a linear relationship interval of the spectral slope can be defined as an aging-sensitive band, and the feasibility of the spectral slope feature can be further verified by partial least-squares modeling.In this paper, two sets of aging experiments are carried out for three kinds of aging samples to form a data set, one set of data is used for training verification, one set of data is tested, and the specific data set is composed as shown in In order to avoid the influence of the detection environment and the detection equipment on the spectral results, this paper selects all samples to carry out centralized detection at the same time after the aging experiment, so as to ensure the consistency of the detection data and the spectral accuracy.n, the independent variable matrix is denoted by X, and the dependent variable matrix is denoted by Y, then let Partial least-squares (PLS) regression is a new multivariate statistical analysis method that integrates multiple linear regressions, canonical correlations, and a principal component analysis . Supposi(1)(2)The correlation between If the regression effect meets the preset requirements, the PLS regression process is terminated; otherwise, it is necessary to use the information remaining after X is interpreted by were met .R) and root mean square error (RMSE) were used as evaluation indices for the model performance. R was used to measure the degree of correlation of the model, and RMSE was used to evaluate the quality and predict the ability of the quantitative analysis model. The calculation equations are as follows [In this study, the correlation coefficient ( follows :(5)R=1−∑R is to 1 and RMSE is to 0, the better the prediction performance of the model [In the above equation, he model .The slope of the aging-sensitive band was selected as the feature for PLS modeling, and the feasibility of the spectral slope feature for predicting the degree of aging of the PE pipe was verified based on the modeling results. The modeling effects are listed in It can be seen from The PLS aging prediction model was established using the spectral slope as the spectral feature, and the absorption coefficient data of 20 groups of aging samples  were predicted. As shown in The accuracies of the white PE80 training set and verification sets were 3.38% and 5.62%, respectively. The accuracies of the white PE100 training and verification set were 3.27% and 5.73%, respectively. The accuracies of the black PE100 training and verification set were 3.14% and 6.84%, respectively. The training set errors for the three materials were less than 9.8 h, whereas the verification set errors were less than 13.2 h. The error of the three material test sets is shown in Among them, the minimum error of the white PE80 test sets is 4.08 h. The minimum error of the white PE100 prediction sets is 5.9 h. The minimum error of the black PE100 prediction sets is 3.9 h, and the error in the three pipe test sets were within 13.5 h. It was confirmed that the THz spectral characteristics can be used to characterize and predict the aging degree of PE pipes.RMSEc and RMSEcv of the model for the three pipes were less than 0.0615 and 0.0753, respectively. Rc and Rcv were above 0.98 and 0.966, respectively. The prediction accuracy of three different aging degrees of white PE80, white PE100 and black PE100 was 94.38%, 94.27% and 93.16% verification set error was within 13.5 h. The slope of the absorption spectrum not only simplified the model but also improved the prediction accuracy, proving that the optical parameter characteristics of the THz band can be used to characterize the degree of aging of PE pipes.In this study, the characterization and prediction of the degree of photothermal aging of PE pipes for outdoor use were studied based on terahertz time-domain spectroscopy. Firstly, the terahertz spectrometer was used to extract the optical parameters of the artificial white PE80, white PE100 and black PE100 photothermally aged samples, and the absorption coefficient spectrum was analyzed. With increasing aging time, the absorption coefficient spectra of the three materials show a downward trend. Secondly, the UVE, SPA, CARS, and RF spectral screening algorithms were used to screen the wavelength characteristics of the absorption coefficient spectrum, and the spectral slope characteristics of the aging-sensitive band were selected as an evaluation index of the degree of PE aging. Finally, a PLS aging characterization model was established to characterize and predict the three types of PE pipes with different degrees of aging. The


The aim of this study was to investigate the relationship between air temperature and the risk of hospitalization for genitourinary disorders.Distributed lag non-linear models (DLNM) were used to estimate the association between air temperature and the risk of hospitalization for genitourinary disorders, with subgroup analysis by gender and age to identify the susceptible population of temperature-sensitive genitourinary system diseases.Low mean temperature (MT) , high MT  and low diurnal temperature range (DTR)  were all associated with the increased risk of hospitalization for genitourinary disorders in the total population analysis, and the high MT effect was stronger than the low MT effect. Subgroup analysis found that high MT was more strongly correlated in male  and those <65 years , and low DTR was more strongly correlated in female  and those <65 years .The effect of high MT on the risk of hospitalization for genitourinary disorders is more significant than that of low MT. DTR was independently associated with the risk of hospitalization for genitourinary disorders. The Sixth Assessment Report of the United Nations Intergovernmental Panel on Climate Change points to growing evidence that climate change is already causing many weather and climate extremes in all regions of the world, that extreme weather events such as heat waves are being observed, and that some 3.3–3.6 billion people are living in environments that are highly vulnerable to climate change . Global A study of different regions in Korea found that low temperatures led to an increased risk of acute kidney injury admissions in older male , that thLanzhou also has unique climatic characteristics compared to other Chinese cities. The spring and summer boundaries are indistinct, with short, high temperatures in summer, rapid cooling in autumn, long, cold winters, stable atmospheric formations, severe inversions and the heat island effect of urbanization. As Lanzhou is deep inland in the northwest, it is not easily accessible by oceanic warm and humid air currents and has few opportunities for rainfall. The climate in most areas is dry, with a very continental temperate monsoon climate, so the relationship between air temperature and genitourinary disorders in Lanzhou needs to be studied.This study was conducted by collecting inpatient treatment data and meteorological data concerning genitourinary system disorders from all hospitals in four main urban districts of China city of Lanzhou  from 2014 to 2020. The effect of MT and DTR on the overall risk of hospitalization for genitourinary system disorders was first analyzed. Subgroup analysis was then performed based on gender and age to identify potential genitourinary diseases sensitive to air temperature.Lanzhou City of China is located at mid-latitude , the geometric center of China’s geography, in the middle of Gansu Province, a belt-shaped basin city narrows from north to south and long from east to west. The city is surrounded by mountains to the north and south, and the Yellow River meanders through the city from east to west for more than 100 miles. Lanzhou is the only provincial capital city where the Yellow River passes through the center of the city, and the city’s unique and beautiful urban landscape is formed by the mountains and the water, which are still and moving. 2022 saw the city’s resident population reach 4,415,300 with a total geographical area of 13,100 square kilometers and an urban area of 1,631.6 square kilometers. The total area of the city is 1100 square kilometers Composed of four main urban districts  with a population of 3.8 million people.The four main urban districts are conveniently located in the center of Lanzhou City and are surrounded by densely populated residential areas. At the same time the urban hospitals have well-established medical departments and strong technical capabilities to provide medical services to all residents of the city. And >80% of local residents are willing to seek treatment at these hospitals . TherefoDaily inpatient data from 1 January 2014 to 31 December 2020 were obtained from all hospitals in the four main urban districts of Lanzhou and then classified according to the World Health Organization International Classification of Diseases (ICD-10), based on codes (N00-N99) for inpatient attendance information, including age, gender and date of admission. This study conducted in accordance with the Declaration of Helsinki, collected hospitalization data without identifiable personal information. The Institutional Review Board (IRB) of the School of Public Health, Lanzhou University, exempted the study from ethics approval and consent, considering the absence of identifiable participant information. The researchers ensured the privacy and confidentiality of the data throughout the study, adhering to the guidelines and regulations stipulated in the Declaration of Helsinki.10, SO2 and NO2 were calculated using 24-hour average concentrations. Neither meteorological data nor pollutant data were missing.The meteorological data for this study were obtained from the Lanzhou Meteorological Bureau and consisted mainly of MT, daily maximum temperature, daily minimum temperature and daily mean relative humidity (RH). DTR was obtained by subtracting the daily maximum temperature from the daily minimum temperature. Meteorological data were collected at the national meteorological monitoring station (Lanzhou Station) with professional meteorological observation instruments that had been certified by China Metrology, and professional meteorological observers were responsible for data quality audit and control to ensure that the observation data were complete and accurate. We used air temperatures from only one national meteorological monitoring station for the reason that using air temperatures from one station is equivalent to using spatial and temporal modelling of space temperature to assess the impact of assessing city-wide temperature on hospitalization risk . Air polDescriptive statistics were calculated by SPSS 26 and included minimum, maximum, mean, standard deviation (SD), 5th, 25th, 50th, 75th and 95th percentiles for air pollutants, meteorological variables and hospital admissions. Spearman’s correlation analysis was also performed on daily meteorological data for Lanzhou (2014–2020) using SPSS 26.2.5 and PM10 cannot be included in the model at the same time. At the same time, the relevant literatures were selected PM10, SO2 and NO2 into the model, so we chose PM10, SO2 and NO2 [10, SO2 and NO2. And in order to control the potential effect of multicollinearity, the Spearman’s correlation coefficients for each meteorological factor and pollutant were examined, and only factors with the Spearman’s correlation coefficient <0.7 were entered into the model  and the "dlnm" package. The model is based on the following equations:Yt is the number of genitourinary disorder admissions on day t; α denotes the intercept; t denotes the day of visit; and ∑cb is a two-dimensional cross basis function of lag days and MT and DTR. As suggested by previous studies [ns denotes the natural cubic spline, with 4 df being used to adjust for RH, PM10, SO2 and NO2; ns is 7 df per year to control for long-term trends and seasonality; Dow is a categorical variable representing the day of the week effect; Holiday is a categorical variable representing the holiday effect. To identify potentially susceptible populations, further subgroup analyses were conducted according to gender  and age (<65 and ≥65 years). In this study we have not explored air temperature at a deeper level of analysis, but have only classified low and high levels. Referring to related studies [Previous studies have shown that the impact of meteorological factors on human health is often delayed and has a lag effect. In order to fully capture the effect of MT and DTR on the risk of hospitalization for genitourinary disorders, we used a distributed lag non-linear models (DLNM) based on a quasi-Poisson distribution. The DLNM is based on a "cross-base" function that allows simultaneous estimation of the non-linear effects of each delay, and it shows the relationship between MT, DTR and the risk of hospitalization for genitourinary disorders at each meteorological factor value point and lag point . Althoughe model . The deghe model . We also studies , in the Yt is the number of genitourinary disorder admissions on day t; t denotes the day of visit; α denotes the intercept; ∑cb is the air pollutant  cross-base matrix, l is the number of days lagged. The relationship for the air pollutant-genitourinary disease dimension was fitted with a natural cubic spline function with df of 3. The lag dimension was also fitted with a natural cubic spline function with df of 3. And ns denotes the natural cubic spline, with 3 df being used to adjust for MT and Rh with previous studies [MT is the mean temperature on day t; Rh is the relative humidity on day t. In the current study, we chose 7 lag days as our model. We examined the effects of single day lags (from lag0 to lag7) and cumulative lags (lag0-1 to lag0-7) of air pollutants  on total genitourinary disorder admissions. The results of the analysis were expressed as RR and its 95% CI in association with 10 μg/m3 increase in each pollutant.In addition, we also used the following models to study the relationship between air pollutants and the risk of hospitalization for genitourinary diseases: studies ; MT is tTo assess the stability of the model, sensitivity analyses were conducted by varying the degrees of freedom of the time variables , the maximum lag days , and the degrees of freedom of air pollutants, MT and RH  in the DLNM. The model was considered stable if the overall cumulative exposure-response relationship pattern and risk distribution for the risk of hospitalization for genitourinary disorders remained similar over time after varying the df and lag period. All results in this study were considered statistically significantly correlated at a two-tailed p-value of less than 0.05.10, SO2, and NO2 was 112.0 μg/m3, 20.6μg/m3, 48.2μg/m3, respectively.The 3D plot shows the exposure-lag response association between MT and DTR and genitourinary disorders at 0–21 lag days . There i95) and low (P5) levels on the risk of hospitalization for genitourinary disorders are shown in The cumulative lagged effects of MT and DTR at high  and low (P5) levels on the risk of hospitalization for genitourinary disorders by gender and age are shown in The cumulative lagged effects of MT and DTR at high . The high MT cumulative lag showed the dangerous effect at lag0-4 lasting until lag0-21 and the effect was strongest at lag0-21 . The cumulative lag effect of low DTR showed the hazard effect from lag0-1 to lag0-21, with the strongest effect at lag0-17 . For those aged ≥65 years, low MT cumulative lag showed the dangerous effect from lag0-1 to lag0-21, and the strongest effect at lag0-21 . The high MT cumulative lag showed the dangerous effect at lag0-9 lasting until lag0-21 and the effect was strongest at lag0-21 . The cumulative lag effect of low DTR showed the hazard effect from lag0-1 to lag0-21, with the strongest effect at lag0-16 .3 increase of PM10, SO2 and NO2 concentration under different lag days are presented in 2 in single-day lag and NO2 in cumulative lag increased the risk of hospitalization for genitourinary disorders.The RR and 95%CI of the risk of hospitalization for genitourinary disorders associated with each 10 μg/mIn the sensitivity analysis, the associations between MT and DTR and the risk of hospitalization for genitourinary disorders remained stable when changing the degrees of freedom of the time variables in the model , the maximum lag days , the degrees of freedom for air pollutants , and the degrees of freedom for MT and RH  –S4 Figs.2 and NO2 had a significant impact on the risk of hospitalization for genitourinary disorders. The Taiwan cohort study found that exposure to higher concentrations of SO2 increased the risk of idiopathic nephrotic syndrome [2 can increase the risk of acute kidney injury admission [10 was not associated with chronic kidney disease at lag0 [2 and NO2 leading to genitourinary disorders, including systemic inflammation, endothelial injury, atherosclerosis, oxidative stress and so on. However, long-term exposure to PM10 increases the risk of chronic kidney disease in Taipei [2 exposure and outpatient visits for menstrual disorders [The development of the disease is not only related to the patient’s own qualities, but can also be influenced by changes in temperature. As far as is known from previous surveys, this study is the first to examine the impact of MT and DTR on inpatient treatment of genitourinary disorders in Lanzhou with gender and age subgroup analysis. In the present study, we found that low MT, high MT and low DTR were significantly associated with an increased risk of hospitalization for genitourinary disorders. Although the harmful effects of MT have been demonstrated, the effect of DTR on the risk of hospitalization for genitourinary disorders is relatively new to researchers. This study provides evidence that the effect of DTR is associated with the risk of hospitalization for genitourinary disorders, suggesting that low DTR is an independent risk factor for the risk of hospitalization for genitourinary disorders. The results of this study show some interesting aspects, some of which confirm the results of the literature, and some are compared. Both SOsyndrome . A retrodmission . The Swe at lag0 . The mecn Taipei . A 6-yeaisorders . These cPrevious studies have shown that air temperature-morbidity curves worldwide are almost V-shaped or J-shaped , 26. It For some specific respiratory cardiovascular diseases, it is true that there are studies that show an increased risk of seizures and a relatively long lag time in cold temperatures, and a decreased risk of seizures and a relatively short lag time in hot temperatures . HoweverA global study in 2019 found that both the cold and heat effects were most pronounced in China . Both loIn the gender subgroup analysis, different levels of MT and low DTR had an effect on both male and female, suggesting that air temperature affects both genders. High MT was more strongly correlated in male and low DTR was more strongly correlated in female. Possible explanations for female sensitivity to low DTR include, on the one hand, the fact that the female thermoregulatory system is more sensitive to changes in air temperature and is more likely to perceive low DTR. On the other hand, the influence of estrogen and the physiological cycle can make female more sensitive to low DTR . In the This study provides evidence that the risk of hospitalization for genitourinary diseases is related to air temperature. We found that both low MT and high MT increased the risk of hospitalization for genitourinary disorders in Lanzhou residents, and the effect of high MT was more significant. At the same time, we also found that DTR was independently associated with the risk of hospitalization for genitourinary disorders, especially low DTR. In view of the general trend of global warming, this study has important implications for the prevention and treatment of temperature-related genitourinary diseases, and measures should be taken for different sensitive groups to reduce the impact of air temperature on people’s health.S1 Fig(TIF)Click here for additional data file.S2 Fig(TIF)Click here for additional data file.S3 Fig(TIF)Click here for additional data file.S4 Fig(TIF)Click here for additional data file.S1 Table(DOCX)Click here for additional data file.S2 Table(DOCX)Click here for additional data file.S3 Table(DOCX)Click here for additional data file.


Due to its property of actual physical process simulation, the Monte Carlo method was adopted to establish the model of the 16N monitoring system and design a structure-functionally integrated shield to realize neutron-gamma mixed radiation shielding. First, the optimal shielding layer with a thickness of 4 cm was determined in this working environment, which had a significant shielding effect on the background radiation and improved the measurement of the characteristic energy spectrum and the shielding effect on neutrons was better than gamma shielding with the increase in the shield thickness. Then, functional fillers such as B, Gd, W, and Pb were added to the matrix to compare the shielding rates of three matrix materials of polyethylene, epoxy resin, and 6061 aluminum alloy at 1 MeV neutron and gamma energy. The shielding performance of epoxy resin as the matrix material was better than that of the aluminum alloy and polyethylene, and the shielding rate of boron-containing epoxy resin was 44.8%. The γ-ray mass attenuation coefficients of lead and tungsten in the three matrix materials were simulated to determine the best material for the gamma shielding performance. Finally, the optimal materials for neutron shielding and gamma shielding were combined, and the shielding performance of single-layer shielding and double-layer shielding in mixed radiation field was compared. The optimal shielding material-boron-containing epoxy resin was determined as the shielding layer of the 16N monitoring system to realize the integration of structure and function, which provides a theoretical basis for the selection of shielding materials in a special working environment.The  However, in practical applications, a lead layer of only 5 mm does not block the background radiation of neutron gamma in harsh environments [2O3-Sm2O3 glass against gamma, neutrons, and protons, and concluded that the increase in the lead monoxide improved the radiation shielding performance of the glass samples. Akn [2O–V2O5–MoO3–TeO2 as a radiation shielding material and the bioconcrete shielding usability of the material, respectively. In recent years, more and more studies have shown that composite shielding materials are more effective than traditional single shielding materials [In order to ensure the safe operation of nuclear power plants, multiple real-time monitoring barriers have been set up. In the decades since the successful development of the e NaI Tl+41Am, whisolution . The higsolution . To reduronments , thereforonments ,9. El-Saronments  investigronments  studied les. Akn  used Geaaterials ,14,15,16aterials ,18, gadoaterials , tungsteaterials , and lea16N radiation monitoring system, improve the response speed and effectively determine the amount of leakage.In this paper, Monte Carlo simulations were used to compare the shielding performance between different thicknesses and elements to facilitate the selection of shielding elements for a mixed irradiation environment. Among the commonly used neutron-gamma integrated shielding materials, polyethylene and epoxy resins have the advantages of good shielding, stable chemical properties, light weight, and small size as polymeric materials often used in the field of radiation protection; aluminum alloys are stronger and can easier meet the mechanical properties of the material, in addition to good corrosion resistance, heat resistance, and low density. The shielding rates of polyethylene, epoxy resin, and 6061 aluminum alloy matrix materials doped with boron, gadolinium, tungsten, and lead were compared to determine the appropriate thicknesses and optimize effective shielding body materials that can reach both neutron and gamma rays to achieve structural/functional integration, reduce the background interference in the complex radiation environment of the 16N with energies of 7.12 MeV (5%) and 6.13 MeV (69%), respectively. Under normal operating conditions, it is only possible to measure the radionuclide 16N in the primary system. If the heat transfer tube is damaged, 16N will leak out into the secondary circuit with the coolant and mix with the pipeline steam. Therefore, the greater the γ-ray count rate generated by 16N decay in the main steam pipeline, the higher the leakage rate of the heat transfer tube of the steam generator. In practical applications, the 16N radioactivity level (γ count rate) in the main steam is frequently detected directly, and the damage of the heat transfer tube is determined by formula conversion [During normal operation of a nuclear power plant, the oxygen atoms in the primary coolant are irradiated by fast neutrons above 10 MeV, producing an intrinsic activation product nversion ,22,23,24The composition and thickness of the shielding material of the detector ,26,27,28As shown in 16N radionuclides in the main steam pipe. The length of the main steam pipeline is 400 cm, the inner radius of the pipeline is 36.83 cm, the outer radius of the pipeline is 43.53 cm, and the thickness of the steam pipeline is 4.47 cm considering the weakening effect of the three-layer shielding of steam, the pipe wall, and insulation material outside the pipe wall on the source term.The source term is the steam containing The structure of the detector is shown in In the application of nuclear technology, according to the situation of different radiation sources passing through the material, a special structure and specific shielding radiation shielding materials are used to protect the human body and equipment ,32. NeutRPE) [I and 0I are the dose after passing through the shielding material and the dose before passing through the shielding material, respectively, and the shielding material outgoing surface I and incoming surface 0I are obtained by Monte Carlo simulation. The better shielding efficiency of the material indicates greater shielding of the incident particles and therefore better radiation protection. The larger the RPE value, the better the protective effect of the material, and vice versa.The shielding performance of the shielding material for neutron and gamma rays can be expressed by the radiation protection efficiency (RPE) :(1)RPE=1I and 0I are the shielding material outgoing surface and incoming surface above-mentioned, respectively; x are the linear attenuation coefficient and thickness of the shielding material, respectively. For a compound or mixture, its mass attenuation coefficient can be expressed as:i and i th element or mineral, respectively.The mass attenuation coefficient (tion (2) .(2)I=I016N monitoring system, the distance between the detection device and the steam pipe was only about 4 cm. The model of the NaI detector to detect the leakage of the steam generator heat transfer tube was established, and the energy spectrum measurement without the shielding layer and with a 4 cm shielding layer was compared.As shown in −2 cps/Bq and 3.006 × 10−2 cps/Bq, respectively. It can be concluded that the tungsten shield with a thickness of 4.0 cm had an obvious shielding effect on the background radiation in the working environment. In other studies conducted in [16N radiation monitoring system, reducing the external interference, and improving the stability of the system.ucted in ,36, simiNeutrons can be slowed down by inelastic collisions with heavy elements. After reducing to a certain energy, inelastic scattering will no longer occur, mainly through elastic scattering with hydrogen elements to lose energy ,38,39. TRPE values of lead and tungsten with different thicknesses for neutron and gamma rays were different. With the increase in the thickness, the radiation protection efficiency of the material started to increase at a faster rate and then slowed down, because the thicker material caused more collisions between the incident particles and the nucleus when passing through the shielding material, which decayed exponentially with the depth of incidence. However, as the shield thickness increased, the radiation protection efficiency against gamma tended to be more and more similar to that of neutron radiation protection, which verified Zhao Sheng’s [3 greater than that of lead at 11.34 g/cm3, which has a larger cross-sectional action with incident particles and more collisions. The RPE values of both increase as the thickness of the shielding material increases  [ Sheng’s  study onrticles) ,42. At aTraditional neutron shielding materials such as boron, water, polyethylene, gadolinium ,45,46,47RPE) of composite polyethylene materials with different proportions of B, Gd, W, and Pb functional fillers in the gamma radiation field, neutron radiation field, and neutron–gamma mixed radiation field. The horizontal coordinate is the content of the functional filler in the matrix and the vertical coordinate indicates the radiation protection efficiency (RPE) of the material. The RPE when the share ratio is 0 corresponds to the shielding rate of the pure matrix material. Where y = 0.25” in RPE of the composite polyethylene materials to gamma particles also showed different upward trends. As the content increased, the polyethylene composites doped with lead and tungsten had a greater effect on the gamma particle shielding performance than the polyethylene composites doped with gadolinium and boron. The RPE of W and Pb was always greater than that of B and Gd. 4C) [2BO3) [ Gd. 4C) , boric a) [2BO3) , boron n) [2BO3) , or boroRPE) of four fillers with 50% incorporation in polyethylene, epoxy resin, and 6061 aluminum alloy matrix materials were compared in the neutron radiation field. Among them, pure epoxy resin RPE > pure 6061 aluminum alloy RPE > pure polyethylene RPE; after adding four kinds of functional fillers, the shielding performance of the composite shielding material with 50% B element was better than that of the composite shielding material composed of the other three elements. The shielding rates of boron-containing polyethylene, boron-containing epoxy resin, and boron-containing aluminum alloy were 37.5%, 44.8%, and 40.5%, respectively. Therefore, the composite material composed of epoxy resin as the matrix in the neutron radiation field can be better shielded, and the incorporation of boron can better shield neutrons.As shown in To determine the best gamma shielding material, the transmission calculation models of lead, tungsten, lead/polyethylene, tungsten/polyethylene, lead/epoxy resin, tungsten/epoxy resin, lead aluminum alloy, and tungsten aluminum alloy to γ-ray were established. The mass attenuation coefficients of different shielding materials were calculated under 0.2 MeV, 0.5 MeV, 1.0 MeV, 1.5 MeV, 2.0 MeV, 3.0 MeV, 4.0 MeV, 5.0 MeV, and 6.0 MeV gamma energy.According to Formula (3) and the proportion and density of each material, the influence of Pb and W shielding particles on the mass attenuation coefficient of shielding materials in By calculating the neutron and gamma ray shielding properties of the three kinds of matrices and four kinds of functional shielding fillers, the material designed with epoxy resin as the matrix and 50% B element as the shielding filler can be selected as the neutron shielding composite. When the gamma photon energy was less than 1 MeV, the mass attenuation coefficient of the lead and lead-containing composites was higher than that of the tungsten and tungsten-containing composites, and the relationship between the single-layer shielding composites and double-layer shielding composites and shielding properties was further studied.The variation in the shielding rate of single-layer shielding and double-layer shielding materials with the material composition is shown in 16N monitoring system.In this paper, the working environment of the detector was affected by neutron–gamma mixed radiation, which affects the sensitivity of the monitoring equipment. A shielding material with an appropriate thickness was designed to ensure the detection efficiency and stability of the detection system by reducing the background interference rays in the environment to reduce the failure probability of the 16N monitoring system was established by the Monte Carlo method, by comparing the energy spectra measured without and with the addition of a 4 cm tungsten shield, and spectral smoothing of the energy spectra revealed the detection efficiencies of 2.748 × 10−2 cps/Bq and 3.006 × 10−2 cps/Bq for the 6.13 MeV full energy peak, respectively. Therefore an appropriate shield thickness was chosen to reduce the contribution of secondary gamma to the energy spectrum measurements, and the optimal shielding layer of 4 cm thickness was determined, which had an obvious shielding effect on the background radiation and improved the measurement of the characteristic energy spectrum. Comparing the shielding rate of lead and tungsten with the thickness of a 0–4 cm shielding layer, when the thickness was 4 cm, the shielding rate of the neutron and gamma rays could reach about 30%.The model of the Comparing the polyethylene matrix with different contents of boron, gadolinium, tungsten, and lead, the results demonstrate that in the gamma environment, with the increase in the filler content, the polyethylene composites doped with lead and tungsten had a greater effect on the shielding performance of gamma particles than the polyethylene composites doped with gadolinium and boron; in the neutron environment, the increase in the functional fillers does not imply an enhancement in their shielding performance, and the increase in gadolinium, tungsten, and lead instead weakened the neutron gamma shielding effect of the composites; only the increase in the boron element enhanced the shielding effect of the polyethylene containing boron.16N monitoring system under the 1 MeV neutron gamma mixed radiation field.Comparing the three matrix materials of polyethylene, epoxy resin, and the 6061 aluminum alloy, the neutron shielding performance of epoxy resin was better than that of the aluminum alloy and polyethylene. Comparing the mass attenuation coefficients single lead and tungsten in the three matrix materials against γ-rays, it was determined that the shielding performance of the material containing lead was optimal at a gamma energy of 1 MeV. The relationship between the single-layer shielding composites and double-layer shielding composites and the shielding performance was investigated. The results demonstrate that at a neutron energy of 1 MeV, the shielding rate of single-layer shielding composites was much greater than that of the double-layer shielding composites, and it can be concluded that the radiation protection efficiency of the epoxy resin composite doped with boron and lead elements was 44.8%, and its shielding performance was better than that of the double-layer shielding materials of which it was composed. Therefore, the optimal shielding material-boron-containing epoxy resin can be used as the shielding layer of


H2 generation from formic acid (FA) decomposition occurred in a batch and a packed-bed flow reactor, in mild conditions, using a 2% Pd6Zn4/HHT (high heated treated) catalyst synthesised via the sol-immobilisation method. Experimental and theoretical studies took place, and the results showed that in the batch system, the conversion was enhanced with increasing reaction temperature, while in the continuous flow system, the conversion was found to decrease due to the deactivation of the catalyst resulting from the generation of the poisoning CO. Computational fluid dynamics (CFD) studies were developed to predict the conversion profiles, which demonstrated great validation with the experimental results. The model can accurately predict the decomposition of FA as well as the deactivation that occurs in the continuous flow system. Of significance was the performance of the packed-bed flow reactor, which showed improved FA conversion in comparison to the batch reactor, potentially leading to the utilisation of continuous flow systems for future fuel cell applications for on-site H2 production.The need to replace conventional fuels with renewable sources is a great challenge for the science community. H Liquid H2 is the most desirable form of H2 for storage, which involves a complex process and high cost [2 in other molecules that can be easily transported and utilised is the most dominant option, with formic acid  gaining the interest from scientists as it offers high H2 content [2 may operate under mild conditions with the reactant having low toxicity [2, implying significant positive effects on the climate [2 and CO2 and the second one the generation of CO and H2O. The production of CO is undesirable as it poisons the catalyst, so it must be eliminated [Our dependence on non-renewable energy sources, with their exhaustion in the near future and their effect on the environment, are very crucial factors and challenges that this world needs to consider and face. Hydrogen  catalyst was synthesised through a different preparation method, aiming to improve the overall performance of the catalyst compared to the previous one. The importance of the work was represented by its combination of experimental work with computational simulation in batch and continuous flow reactors, as well as the implementation of the continuous flow system for the constant production of a H2 stream for fuel cell applications. CFD modelling studies provide a better understanding of parameter behaviour as it offers the opportunity to study specific terms in the governing equations [In a previous work reported by our group , processquations ,32,33,346Zn4 supported on HHT-CNFs was synthesised via sol-immobilisation in an inert atmosphere for the prevention of Zn oxidation. The morphology and structure of the synthesised catalyst were determined via transmission electron microscopy (TEM) from Thermo Fisher Scientific, Waltham, MA, USA and X-ray photoelectron spectroscopy (XPS) from Thermo Fisher Scientific, Breda, The Netherlands. The details of the materials used, the synthesis of the catalyst and the experimental procedure concerning the characterisation of the catalyst are available in the The PdThe catalytic tests were performed in a batch and a home-made packed-bed reactor where the effects of temperature and FA flow rate were studied, respectively. In both cases, the conversion of FA was evaluated using high-performance liquid chromatography (HPLC). Details of the experimental set up are provided in the For this study, COMSOL Multiphysics 5.6 was used in order to couple the mass balance equations and the conservation along with the boundary conditions. All the equations used are presented in the 6Zn4/HHT bimetallic catalyst was prepared via the sol-immobilisation method using polyvinyl alcohol (PVA) as a protective agent and NaBH4 as a reducing agent [The Pdng agent . The catA). The activation energy for 2% Pd6Zn4 was found to be around 22 kJ/mol for the batch reactor system. The great overall performance of the catalyst can be attributed to the Pd-enriched surface of the bimetallic catalyst, as confirmed via XPS analysis . The comparison between the two PdZn catalysts highlights the beneficial effect of the presence of polyvinyl alcohol on the surface of PdZn in terms of selectivity.A targeted comparison among the experimental and computational studies using the Pd2 generation; therefore, we focused on investigating the reaction temperature only at 30 °C. From 2 generation, as well as the deactivation profile. The continuous flow reactors, due to the fact that they can operate and handle higher concentrations when compared to the batch systems, are more preferred, especially for large-scale processes [The dehydrogenation of FA was also studied in a packed-bed reactor under mild operating conditions. Usually, temperatures above 60 °C are not investigated due to their incapability to be utilised in portable devices like fuel cells for on-site Hrocesses . CompariThe designed model includes the solid catalyst, and the internal and external mass transfer limitations within the packed-bed reactor can be determined. The study of mass transfer resistances can display the parameters that lead the reaction to be diffusion- or mass-limited. Additionally, mass transfer limitations in the bulk were also investigated. The decomposition of FA involves the diffusion and mass transfer of FA to the area of catalyst particles. The concentration of FA surrounding the catalyst particle was compared to the concentration on the surface of the particle in order to define the external mass transfer limitations. Non-isothermal conditions were also investigated in order to define any heat transfer limitations. Even though the packed-bed reactor operates isothermally at 30 °C, an energy balance was included for this investigation. The inlet flow rate of FA was also investigated (0.1–0.5 mL/min) both experimentally and computationally with a steady reaction temperature of 30 °C. As depicted in 6Zn4@HHT catalyst. The studies included the correlation of experimental and CFD studies, which were performed for validation, showing the validity of the experimental results. The results showed that in the batch reactor system, the conversion increases with the reaction temperature, exceeding 80% at 60 °C. The conversion in the continuous flow system was found to be higher at lower inlet FA flow rates, and the activity of the catalyst was significantly decreased after 60 min of reaction time, attributed to the formation of CO, which promotes the poisoning of the active sites of the catalyst. Lastly, switching from a batch reactor to a continuous flow system offers the opportunity to obtain higher FA conversions and potential utilisation for the constant generation of H2 in fuel cell applications. The improvement in the activity of the catalyst, since the generated CO promotes its deactivation, is a challenge to overcome in future work. Also, CFD simulations can be utilised for the investigation of different parameters considering the configuration of the reactor.Batch and packed-bed configurations were utilised for the decomposition of FA utilising a 2% Pd


They did not differ in the subsequent days of the preterm neonates’ lives. The ROC curve for TFF3/cr. in the preterm and term neonates showed AUC = 0.751 . Conclusions: Prematurity is associated with higher urinary excretion of TFF3. Male gender is associated with an increased urinary TFF3 excretion in term neonates.Background: Distinguishing between a pathologic state and renal development is important in neonatology. Because the assessment of serum creatinine in neonates is not reliable, better biomarkers are needed. Trefoil factor 3 (TFF3) is proposed as a biomarker of kidney injury. The study aimed to assess its urinary concentration in healthy term and stable preterm neonates. Material and methods: The study included 80 term and 20 preterm neonates born in the Department of Perinatology of the University Clinical Hospital in Bialystok. Urine was obtained from the term neonates on the 1st day of life and from the preterm neonates on the 1st, 8th, 15th and 22nd day of life. The urinary concentration of TFF3 was determined using a commercially available immunoassay and was normalized for the urinary creatinine concentration (cr.). Results: The values of TFF3/cr. were higher in the preterm than in the term neonates ( The prematurity of neonates’ kidneys, especially in preterm neonates, whose kidneys are in an active nephrogenesis, makes them especially prone to the negative effects of the extra-uterine environment. These effects may lead to their failure . Only eaSimilarly, it is difficult to answer the diagnostic question: is it a pathology or is it still an adaptation. The process of nephrogenesis is complete in full-term neonates, but functional adaptive changes continue as the infant matures . HoweverMany biomarkers of kidney injury, such as NGAL, KIM-1, Cystatin C and others, have already been studied. However, many candidate biomarkers did not prove their sufficient sensitivity and specificity for routine clinical use. The possible explanation of this phenomenon is the insufficient understanding of their biological role. In this case, new potential biomarkers are studied to eventually find one with good clinical sensitivity and specificity and to improve the prediction, detection and diagnosis of kidney injury . One of TFF3, a member of the trefoil factor family, is a small peptide (molecular weight: 7 kDa) secreted by cells producing mucous and involved in both the maintenance and repair of the mucosal surface . TFF3 isThe aim of this study was to analyze the excretion of the TFF3 after birth in healthy full-term and stable preterm infants, and to analyze the fluctuations of the TFF3 excretion during the first weeks of the neonates’ lives.This prospective study was conducted in the Department of Neonatology and Neonatal Intensive Care at the Medical University of Bialystok. The study was conducted according to the guidelines of the Declaration of Helsinki. The study protocol was approved by the Local Bioethics Committee of the Medical University of Bialystok . Written, informed consents were obtained from the parents of all the neonates prior to the study. The parents were informed of the aim, the method and the proceedings after receiving the results.Overall, 100 neonates were included in the study. The neonates were born in the Department of Perinatology and then hospitalized in the Department of Neonatology and Neonatal Intensive Care of the University Clinical Hospital in Bialystok between 1 January 2022 and 31 January 2023.The children were divided into 2 groups: the group comprising 80 term neonates (born between 37 weeks and 42 weeks of pregnancy) and the group comprising 20 preterm neonates (born between 23 and completed 36 weeks of pregnancy). The aim of the study was the assessment of the values of TFF3 in healthy newborns; strict inclusion criteria were used. All prenatal and postnatal factors that might influence the function of the kidneys had to be excluded. The main inclusion criteria were: birth in the Department of Perinatology of the University Clinical Hospital in Bialystok, the parents’ written consent, appropriate gestational age (23–36 week of pregnancy for preterm neonates and 37–42 weeks of pregnancy of term neonates).The general exclusion criteria concerning the neonatal factors were congenital abnormalities, genetic disorders and congenital infections. The general exclusion criteria concerning the perinatal factors were abnormal prenatal examination. The general exclusion criteria concerning maternal factors were diseases during the pregnancy The specific exclusion criteria in the group of neonates born between 23 and 36 weeks of pregnancy (the examined group) were: 1st minute Apgar score < 4, severe general condition, mechanical ventilation, abnormal ultrasound examination of the central nervous system , abnormal ultrasound examination of the abdominal cavity, urinary tract defects , intrauterine growth retardation, abnormalities in the laboratory tests , administration of drugs other than mandatory , against tuberculosis , vitamin K , vitamin D3  and other than parenteral nutrition , methylxanthines , supplementation of micro and macro elements under the standards, exposure to nephrotoxic agents.The specific exclusion criteria in the group of neonates born between 37 and 42 weeks of pregnancy (the reference group) were: 1st minute Apgar score < 7, average and severe general condition, administration of drugs other than mandatory , against tuberculosis , vitamin K , vitamin D3 ).The conditions for terminating the study were: nosocomial infection of the neonate, deterioration of the general condition, withdrawal of the parental consent for the study.The algorithm of the patients’ screening and the creation of the final number of patients included in the study are presented in the The samples of the term neonates’ urine were collected once on the 1st day of life. The samples of the preterm neonates were collected four times, on the 1st, 8th, 15th and 22nd day of life. The collection of the urine was conducted noninvasively, using single-use, sterile bags . The centrifugate urine samples were kept in the refrigerator at 4 °C; then, after no more than 2 h, they were frozen at −80 °C. The samples were stored at −80 °C for no longer than 4 months and were not frozen and thawed multiple times.The samples of the preterm neonates’ blood were collected during the 1st or 2nd day of the child’s life to S-Monovette 1.2 mL, Clotting Activator/Serum test tubes  for venous blood. The collection of venous blood was part of a routine practice in the department. The blood morphology and biochemistry tests were conducted immediately after obtaining the samples.2).The estimated GFR (eGFR) was calculated using the Schwartz formula appropriate for preterm neonates (The concentrations of creatinine in the serum and urine were measured using Jaffé’s method and expressed in milligrams per deciliter (mg/dL).The blood morphology and biochemistry tests were performed in the Department of Laboratory Diagnostics at the University Clinical Hospital in Bialystok during the routine practice in the laboratory. The blood morphology tests were conducted using the Sysmex xn-1500 analyzer . The blood biochemistry tests were conducted using the Abbott Alinity analyzer .The concentrations of TFF3 in the urine were measured using a commercially available immunoassay for kidney toxicology research—Bio-Plex Pro™ RBM Human Kidney Toxicity Panel 2 . The assay’s working range was (lower limit of quantification (LLOQ)-upper limit of quantification (ULOQ)): 0.075–98 ng/mL. The assay’s sensitivity  was 0.036 ng/mL. The intra-assay and inter-assay coefficients of variation (%CV) were, respectively, 2% and 6%. The concentration of TFF3 was expressed in nanograms per milliliter (ng/mL).Because urinary dilution may have a potentially confounding effect, the concentration of TFF3 was normalized for the urinary concentration of creatinine. The TFF3/cr. ratio was expressed in nanograms per milligram of creatinine (ng/mg cr.).The determination of the concentration of TFF3 was conducted in the Department of Hygiene, Epidemiology and Ergonomics of the Medical University of Bialystok.p < 0.05.The statistical analysis of the data was performed using the Statistica 13.3 package . The discrete variables were expressed as counts . The continuous variables were expressed as median, 1st quartile and 3rd quartile (Median (Q1–Q3)). The type of distribution was checked using the Shapiro-Wilk test. Because the data were not normally distributed, the intergroup comparison of the continuous variables was performed using the Mann-Whitney U test. To determine whether the proportions of one nominal variable were different depending on the value of the other nominal variable, the Fisher’s exact test of independence was used. The correlations between both the concentration of TFF3 and the value of the TFF3/cr. ratio, and other variables, were established using the Spearman’s rank correlation coefficients. The direction and power of the associations were determined. The comparison of the values of the two dependent groups was performed using the Wilcoxon signed-rank test. The value of the significance level was α = 0.05. The results were statistically significant when In the group of term neonates, a 95% confidence interval was determined in order to estimate the range of values likely to include a population value with a 95% confidence.The ROC curve (receiver operating characteristic) and the AUC (area under the ROC curve) were used to assess the capability of TFF3 to distinguish between term and preterm neonates . The following parameters were also calculated for the TFF3/cr ratio: the sensitivity and specificity of the test, the positive and negative predictive values There were some missing data on the parameters of blood biochemistry. The missing data were classified as MCAR (missing completely at random) and replaced with the average value calculated based on the known values (Mean Imputation). There were no missing data for the concentration of TFF3 and the value of the TFF3/cr. ratio.p > 0.05).100 healthy neonates were included in the study. The group comprised 80 healthy term neonates and 20 stable preterm neonates. In total, 40 boys and 40 girls formed the group of term neonates. The group of preterm children comprised 8 boys and 12 girls. Both groups were sex-matched  and in good condition (1st minute Apgar score ≥ 8). No significant differences were found between the term boys and girls in the following parameters: gestational age, type of delivery, birth weight, length and head circuit.p < 0.05). The proportion of vaginal-born and cesarean-born children did not differ between the male and female neonates (p > 0.05). The predominance of cesarean-born children was found in both groups. The female preterm children had significantly lower birth weights than the male neonates (p < 0.05). The length and head circuit did not differ between the boys and girls (p > 0.05).The analysis of the basic characteristics of the preterm neonates showed that the gestational age of the boys was significantly higher than the gestational age of the girls (N = 13) of the preterm children and moderately or late preterm children accounted for 35.55% (N = 5). The proportion of the above-mentioned groups did not differ between the boys and girls (p < 0.05).The group of preterm neonates was divided into two subgroups based on the children’s gestational age: very preterm neonates (born at less than 32 weeks of pregnancy) and moderately and late preterm neonates (born between 32 and 36 completed weeks of pregnancy). Very preterm children accounted for 65.00% (p < 0.05). A significantly higher ratio of VLBW/LBW characterized the group of female children.The group of preterm neonates was also divided into two subgroups based on the children’s birth weight: low birth weight neonates  and very low birth weight neonates . One girl weighed 840 g and was classified as an extremely low birth weight neonate (ELBW). The LBW children accounted for 55.00% of all the preterm neonates. The proportion of the above-mentioned groups differed between the boys and girls  and the blood biochemistry . The analysis of the above-mentioned tests did not show any significant differences between the boys and girls. All of the results were within the normal range, according to the reference values of the Department of Laboratory Diagnostics at the University Clinical Hospital in Bialystok.p > 0.05). Also, the eGFR did not show a significant difference between the male and female neonates (p > 0.05).All of the preterm neonates had normal parameters of renal function . The concentrations of the serum and urine creatinine did not differ between the boys and girls (p < 0.01 in both cases). In the group of preterm neonates, no significant differences in the above-mentioned parameters were found between the boys and girls (p > 0.05 in both cases).The statistical analysis showed that in the group of term neonates, both the concentrations of TFF3 in the urine and the values of the TFF3/cr. ratio were significantly higher in the boys than in the girls . In the group comprising preterm neonates, no significant differences in the above-mentioned parameters were found between the LBW and VLBW neonates (p > 0.05 in both cases)The concentrations of TFF3 and the values of the TFF/cr. ratio were compared between the neonates with different body weights. In the group comprising the term neonates, no significant differences were found in these parameters between the children born with a body weight between the 10th and 50th percentile and between the 51st and 90th percentile (p > 0.05 in both cases).The concentrations of TFF3 and the values of the TFF/cr. ratio were compared between the preterm neonates with different gestational ages. No significant differences in the above-mentioned parameters were found between the very preterm and moderately + late preterm neonates  for the mean of a normal population were estimated in the group of term neonates. In addition, 95% CI for the concentration of TFF was 229.15–427.88 ng/mL and the 95% CI for the value of the TFF3/cr. ratio was 436.33–1079.67 ng/mg cr.p < 0.01). No significant correlations were found between the concentration of TFF3 and the other examined variables.In the group of term neonates, a negative correlation was found between the value of the TFF3/cr. ratio and the gestational age  and the concentration of potassium in the plasma . Also, the value of TFF3/cr. correlated positively with the platelet count .In the group of preterm neonates, a positive correlation was found between the concentration of TFF3 and the platelet count in the blood , on the 15th day than on the 8th day (p < 0.01) and on the 22nd day than on the 15th day (p < 0.01).The values of the eGFR, measured on the following days of the child’s life, showed a rising trend, being statistically higher on the 8th day than on the 1st day (p < 0.01). The PPV was 58.82% and the NPV was 87.18%. The ROC curves were presented in the The ROC curve for the TFF3/cr. ratio in the preterm and term neonates showed AUC = 0.751 (95% CI 0.61–0.89) at a cut-off value of 1684.25 ng/mg cr. The sensitivity and specificity of the TFF3/cr. ratio to distinguish between the preterm and term neonates at the cut-off value were 50.00% and 90.70%, respectively  and transcription factors , HIF-1α (hypoxia-inducible factor-1α), C/EBPβ (CCAAT/enhancer binding protein), Sp1 (specificity protein 1), ETS (E26 transformation-specific) transcription factor) .TFF3 acts as a mitogen, enabling cell migration and epithelial restitution. It separates the cell–cell and cell–substratum contacts and promotes the elongation of the epithelial cells and their migration to the injured, exfoliated surface. As the cell–cell contacts are mediated by E-cadherin (an adhesion molecule) binding to beta-catenin, the disruption in the complex comprising the above-mentioned molecules results in the loss of these contacts. To destroy the cell–cell adhesion, the phosphorylation of beta-catenin tyrosine is needed and TFF3 can induce this phosphorylation and promote the migration of the epithelial cells ,20. TFF3The epithelial cells are especially vulnerable to anoikis, the induction of apoptosis following the loss of the attachment to other cells and the extracellular matrix. For this reason, the antiapoptotic functions of TFF3 are important in the restitution of the epithelia . TFF3 caTFF3 can promote cells’ proliferation through the regulation of the signaling pathways involved in regulating the cell cycle . Its proThe angiogenic functions of TFF3 are based on its ability to upregulate HIF-1α (hypoxia-inducible factor-1α) and hypoxia-induced VEGF  synthesis, leading to neovascularization . Also, tThe effects of TFF3 on the immune responses are still unclear. However, it was proven that TFF3 has anti-inflammatory activity, which depends on the protease activated receptor 2 (PAR-2) and the following signaling pathways: TLR (toll-like receptor)/NF-κB, PI3K/AKT, ERK /Twist .In the Nephrogenesis is a complex process that includes the interaction between the metanephric mesenchyme and the branching ureteric bud. The nephron progenitor differentiate and self-renew to form the nephron’s structures from the glomerulus to the collecting duct. The new nephrons are formed by the progenitor cells until 32–36 weeks of gestation. In preterm neonates, the nephrogenesis continues after birth . VariousA study on mouse embryos showed the presence of TFF3 peptide in the developing kidney tubules during the later stages of kidney development. The TFF3 immunostaining was mostly visible in the cortical tubules, morphologically corresponding to both the proximal and distal convoluted tubules. It was also present in the medullary tubules, corresponding to the collecting loops and the thick limb of the Henle’s loop. Importantly, the glomeruli was negative for TFF3. The fact that TFF3 occurs in the later stages of kidney development suggests that it plays a role in the functional maturation of tubular cells and may be used as a marker of the maturation of the epithelium .We still find many gaps in the roles of TFF3 in the kidneys. However, based on its properties, TFF3’s functions in the kidneys might be similar to its functions in the gastrointestinal tract and in the airways. It might take part in the repair of the renal tubular epithelium and its regeneration after the action of a damaging factor . BecauseIn the This study showed that neonates excrete TFF3 in their urine. The value of the TFF3/cr. ratio in the preterm neonates was significantly higher than in the term neonates (median (Q1–Q3): 317.29 (68.07–671.40) and 1486.85 (614.92–3559.18) ng/mg cr., respectively). Unfortunately, in the literature, there are only a few studies concerning the urinary concentration of TFF3, and their results are inconsistent ,38,39,40Yamanari et al. also studied adult patients with CDK. They analyzed the values of the TFF/cr. ratio in patients with early and late CDK ((median (Q1–Q3)): 45.6 (28.6–62.8) and 356.6 237.4–462.7) ng/mg cr., respectively) .4–462.7 . CompariIn contrast, Askenazi et al., assessing a group of 111 neonates with birth weight ≤ 1200 g and/or gestational age ≤ 31 weeks, showed lower values of the TFF3/cr. ratio in both the group of neonates without AKI and the group with AKI. These values were (median (Q1–Q3)): 102 (69.9–249) and 100 (58.4–162) ng/mg cr., respectively .Preterm neonates were also assessed by Correa et al. They showed that the urinary concentration of TFF3 in preterm neonates measured at 72 h of life was (median (Q1–Q3)): 0.022 (0.002–2.417) and at 3 weeks of life: 0.206 (0.003–26.388) ng/mL. These findings are very divergent and were unfortunately not normalized with the urinary creatinine concentration .Much higher values of the TFF3/cr. ratio were shown by Brott et al. They examined 20 male and 19 female healthy adults aged 18–70 years and estimated a 95% CI for the value of TFF3/cr. to be 90.00–9060.00 ng/mg cr. . The 95%No significant differences in both the concentrations of TFF3 and the values of the TFF3/cr. ratio were found between the subsequent days of the preterm neonates’ lives. An explanation of this phenomenon may be that in preterm neonates, nephrogenesis can continue during the first 40 days of life, and TFF3 may be engaged in proliferation and angiogenesis. An additional explanation may be related to the fact that, during this time, the kidneys are highly vulnerable to injury and TFF3 takes part in the processes of repair ,44.In the group of term neonates, both the concentrations of TFF3 in the urine and the values of the TFF3/cr. ratio were significantly higher in boys than in girls. However, the explanation of this phenomenon is not known. In the group of preterm neonates, no significant differences in the above-mentioned parameters were found between the boys and girls. It is possible that the number of preterm neonates was too small to assess these differences.The study has a relatively small number of patients, especially in the group of preterm neonates. The small number of preterm neonates resulted from the strict inclusion criteria . The child had to be hospitalized for at least four weeks and had to have four urine samples collected in the subsequent days of life. Because of the small size of the group comprising preterm neonates, it was difficult to determine the actual impact of the gestational age (very preterm vs moderately and late preterm) and the birth weight (low and very low birth weight) on the concentration of TFF3 in the urine of the preterm neonates. The obtained data showed no significant difference in the concentration of TFF3 and the value of the TFF/cr. ratio between the above-mentioned subgroups of preterm children. However, studies on larger groups of children would be valuable to confirm this observation.The eGFR values were not calculated in the term neonates. The routine practice in the department does not require taking blood samples from healthy neonates and measuring the serum concentration of creatinine.The study was concentrated on the urinary levels of TFF3. It may also be valuable to measure the urinary concentration of TFF3 in parallel with assessing the serum levels of TFF3. This would provide a better understanding of TFF3 handling in the human body.We conducted the study on samples. To make the sample representative for the population of healthy term neonates or the population of stable preterm neonates, we assessed all of the children who were born during the study and who met the inclusion criteria without meeting the exclusion criteria. However, taking into consideration the small number of children who were assessed and the strict criteria used to make the study group, the results cannot be generalized to other populations. It was a preliminary study and the observed associations and observations should be explored in other, larger studies. It would be valuable to conduct similar studies considering term and preterm neonates in different clinical conditions. Extending the study would provide a better understanding of both the secretion and excretion of TFF3. This would be valuable for future biomarker qualification steps. Moreover, it would answer the question of whether the findings could be generalized to patients with different characteristics than the characteristic included in our study.Prematurity is associated with increased urinary excretion of TFF3. The excretion of TFF3 on the 1st day of life was significantly higher in the preterm neonates than in the term neonates. In the premature neonates, the urinary excretion of TFF3 did not change significantly during the first 4 weeks of the neonate’s life. Male gender is associated with an increased urinary TFF3 excretion in term neonates.


The liquid water in the membrane electrode assembly could be easily removed because of the larger gas velocity and capillary pressure, resulting in a higher oxygen concentration in the GDL and the catalyst layer. Therefore, the cell performance increased. The voltage in Case 1 increased by 8% and 71% compared to Cases 2 and 3, respectively. In addition, this could ameliorate the distribution uniformity of the dissolved water and the current density in the membrane along the channel direction, which was beneficial for the durability of the PEMFC. The distribution of the GDL porosity at lower current densities had a less significant effect on the cell performance. The findings of this study may provide significant guidance for the design and optimization of the GDL in PEMFCs.The gas diffusion layer (GDL) is an important component of proton exchange membrane fuel cells (PEMFCs), and its porosity distribution has considerable effects on the transport properties and durability of PEMFCs. A 3-D two-phase flow computation fluid dynamics model was developed in this study, to numerically investigate the effects of three different porosity distributions in a cathode GDL: gradient-increasing (Case 1), gradient-decreasing (Case 3), and uniform constant (Case 2), on the gas–liquid transport and performance of PEMFCs; the novelty lies in the porosity gradient being along the channel direction, and the physical properties of the GDL related to porosity were modified accordingly. The results showed that at a high current density (2400 mA·cm Currently, reducing environmental pollution and achieving clean and efficient energy utilization are imperative global issues. A proton exchange membrane fuel cell (PEMFC) can convert the chemical energy stored in reactants into electrical energy. It has many advantages, such as high energy conversion efficiency and power density, rapid start-up, and environmental friendliness. Therefore, it is regarded as one of the most promising new energy conversion devices to replace traditional energy sources ,2,3.As the operating temperature of a PEMFC is lower than other types of fuel cell, the water generated in the catalytic layer (CL) may exist in liquid form. Water is essential for PEMFCs, because protons can only efficiently cross the membrane when it is sufficiently hydrated . HoweverMany in-depth studies have been conducted to improve the efficiency of reactant transport and water management ability, by optimizing the structure of key components and the operating conditions of PEMFCs, including the effects of channel size and shape ,7, the fMoreover, the gradient distribution of porosity, PTFE, etc., in the through-plane direction of porous materials in a MEA has a significant impact on PEMFC performance, hence attracting much attention. Lim et al.  combinedIn fact, a non-uniform porosity distribution of GDL in the in-plane direction also has a significant effect on gas–liquid transport and cell performance, and there have been a few studies in recent years analyzing the effects of a porosity gradient distribution in the GDL along the channel direction. Kanchan et al. ,28 invesThese few studies, however, did not consider the correction of relevant parameters due to the change of porosity, such as the liquid water permeability, effective gas diffusion coefficient, etc. The mechanism and effect of the porosity gradient distribution in a GDL along the channel direction were not clearly explained, due to the complexity of multi-physical field coupling; and because of the varied operating conditions, some of the conclusions drawn are inconsistent with each other. Therefore, a 3-D two-phase model was built herein, to compare and analyze the effects of GDL gradient porosity distributions, including an increasing gradient, decreasing gradient, and uniform porosity along the channel direction, on the gas–liquid transport and cell performance. Transport parameters such as permeability and gas diffusion coefficients were corrected accordingly. This article is organized as follows: In this study, a 3-D, multi-component, two-phase PEMFC model was developed. The geometric domain is illustrated in (1)The system works at a steady state.(2)The reaction gas is considered an incompressible ideal gas.(3)The reactant is set to laminar flow, owing to the low gas-flow velocity and Reynolds number  .(4)Ionomer water is generated by the electrochemical reaction in the CL ,33.(5)The temperatures of the walls and inlet channels are constant.(6)All the components in the PEMFC are isotropic except for the cathode GDL.(7)Contact resistance between components is ignored .(8)The effect of gravity is ignored .To simplify the complexity of the calculation and improve the efficiency, the following reasonable assumptions were made for this model:The basic governing equations have been widely used ,40,41,42ρ is the density, ε is the volume fraction of open pores, which can be expressed as s is the liquid saturation, The mass conservation equation in this model is described as:=ε0(1−s) ; ε0 is tThe momenturm conservation equation in this model is described as:The energy conservation equation in this model is described as:ith species, and The species conservation equation in this model is described as:−3·s−1) for F is the Faraday constant; and A is the specific active surface area, because of the liquid coverage, and is modeled as: γ is the exponent of concentration; α is the transfer coefficient; “an” and “ca” represent the anode and cathode; η is the overpotential, which in the anode is The volumetric source terms  and the membrane, whose generation and transportation are described in :(13)∇⋅Sed as in :(16)λeq=The liquid water in the cathode and anode CLs, MPLs, and GDLs is driven by capillary pressure.−1) [ressions ,44:(19)SMoreover, as parameters such as the permeability and gas diffusivity of GDL vary with the porosity, the relevant parameters are corrected as follows :(20)K=ε0The gas phase species diffusivity is expressed as follows :(21)Dief−6, and the other equations used 10−3. The porosity gradient distribution in GDL was realized using the UDF function, and the relevant parameters were also modified.The model in this study was solved using computational fluid dynamics (CFD) software (ANSYS Fluent 2022 R1). Based on the finite volume method, the above control equations were solved with double precision. The SIMPLE algorithm was used to deal with the velocity-pressure coupling in the momentum equation. The first-order headwind method was used as the interpolation function. In order to ensure convergence stability, an appropriate relaxation factor was applied to each variable. The convergence iteration standard of the energy equation was 10The effects of three different gradient porosities in the cathode GDL in the flow channel direction on the PEMFC performance were investigated in this study. The porosity distribution in the cathode GDL is shown in The gas-counter flow was set in the channels of the cathode and anode, which was the same as the actual working conditions of the experiments. As the voltage was calculated in the constant current mode, the anode potential was set to be ground, and the cathode was set to a prescribed current density. The anode and cathode inlet were set with a constant mass flow and the outlet was set with a constant pressure outlet. The temperature of the anode and cathode current collector was set to 353.15 K, and the rest of the external boundaries were set as walls without slippage. The values of the main electrochemical parameters are listed in Hexahedral meshes were used for all computational domains. To exclude the effect of mesh size and quantity on the calculated results, five mesh cases were considered. The voltage and calculation times were determined under the same conditions, and the results are shown in 2, the GDL with micro-pore layer was made of Toray carbon paper, and the CCM was made of a Gore membrane, whose catalyst loads were 0.1 and 0.4 mg cm−2 in the anode and cathode, respectively. The porosity of the GDL was 0.6, which was the same as that of Case 2 shown in To validate the reliability of the mathematical model, the polarization curves obtained through experiment and simulation were compared at an operating temperature of 353.15 K, anode/cathode relative humidities (RH) of 50% and 50%, stoichiometric ratios of 1.5 and 2.0, and pressures of 150 kPa and 150 kPa, respectively. The experimental single cell was self-assembled, composed of two graphite polar plates with single serpentine flow channels. The MEA was prepared by Wuhan Technology New Energy Co., Ltd. , its active area was 25 cmThe polarization curves are shown in −2, the cell voltage of Case 1 increased by 8% and 71% compared to Cases 2 and 3, respectively. This indicated that the GDL gradient porosity distribution mainly affected the mass overpotential at high current densities. The causes were analyzed in detail with the characteristics of the multi-physical field distribution inside the MEA.The polarization curves of the three different gradient porosity distributions in the cathode GDL are shown in −2, T = 353.15 K, P = 251 kPa, ξan = 1.5, and ξca = 2.0.The effects of the above mentioned three gradient porosity distributions in the cathode GDL on the gas–liquid transport were analyzed under the operating conditions of 2400 mA cm−1, and that in Case 3 was the lowest, being approximately zero.To quantify the effects of GDL porosity gradient distribution on the oxygen concentration and gas flow, the GDL cross-section was divided into 10 regions of equal area along the channel direction, and the physical quantities in each region were averaged for further quantitative analysis. Therefore, the gradient-decreasing porosity distribution of the GDL in Case 1 increased the gas velocity in the GDL, which increased the oxygen concentration. Compared with Cases 2 and 3, the porosity distribution in Case 1 could effectively enhance the gas transport efficiency.In addition, it was observed that the water molar concentration in the GDL and CL of Case 1 was lower than that of Case 3. On the one hand, this was because the GDL of Case 1 had a greater gas velocity along the flow channel direction, and the water produced by the electrochemical reaction was more easily expelled from the PEMFC under the purging effect of the gas flow, which resulted in the lowest water molar concentration. Therefore, the oxygen had more transport paths, which explains the higher oxygen concentration in Case 1. On the other hand, the water molar concentration is also related to temperature. As explained above, the GDL of Case 1 had the highest gas velocity along the channel direction, which discharged the liquid water in the GDL more easily. Meanwhile, capillary pressure is also conducive to the removal of liquid water in a MEA. It can be concluded that the GDL porosity had an important effect on the uniformity of the current density of the PEMFC. An appropriate porosity distribution can allow reasonable distribution of the reactant and change the water content distribution in the membrane, to produce a more uniform current density distribution, which can ultimately improve the durability of the PEMFC  Compared−2, with no humidification of either the anode or cathode. It can be observed from To comprehensively analyze the effects of the different GDL gradient porosity distributions under a lower current density, this section further investigates the different physical field distributions in the cell at a low current density of 1000 mA·cmThe GDL porosity distribution had less effect on the cell performance at low current density. As having less liquid water had a lesser effect on the transport of reactants. However, more liquid water was generated and occupied the pores of the GDL at a high current density, which increased the reactant transport resistance and mass overpotential of the cell. The GDL with a gradient-decreasing porosity distribution could effectively improve the water management capability, enhancing the efficiency of the reactant transport and the performance of PEMFCs.In this study, the effects of the porosity distribution of the cathode GDL, including gradient increasing, gradient decreasing, and uniformity along the channel direction, on the gas–liquid transport and performance of PEMFCs were numerically investigated. The main conclusions are as follows:−1 along the channel direction. The gas flow velocities in the other two GDLs with increasing and uniform gradient distributions were significantly smaller than those in Case 1. The liquid water in the GDL of Case1 could be removed more effectively owing to the greater gas velocity and capillary pressure. Therefore, it had a higher oxygen concentration, and the performance of PEMFC was improved. At a high current density (2400 mA·cm−2), the voltage in Case 1 increased by 8% and 71% compared to Cases 2 and 3, respectively. At a low current density, the gradient distribution of GDL porosity had less effect on the cell performance. The PEMFC with a decreasing porosity gradient in the cathode GDL along the flow channel direction, together with a anode/cathode gas counter-flow arrangement, enhanced the distribution of water content in the membrane, thus improving the uniformity of the current density distribution in the membrane along the channel direction. These conclusions not only can be used to optimize the design of a GDL but also, possibly, to enhance the durability of the PEMFC.The GDL with a decreasing porosity gradient along the channel direction resulted in a GDL gas velocity of up to 0.5 cm·sThe effects of the gradient coordination variation of the porosity, Pt/C loading, etc., in the CL, MPL, and GDL, both along the thickness direction and flow channel direction, on the transport and the performance of the cell were much more significant, and worthy of further study in the future.