Slight Fluctuation Research Articles

Atomic-Scale Surface Engineering for Giant Thermal Transport Enhancement Across 2D/3D van der Waals Interfaces.

Heat dissipation in two-dimensional (2D) material-based electronic devices is a critical issue for their applications. The bottleneck for this thermal issue is inefficient for heat removal across the van der Waals (vdW) interface between the 2D material and its supporting three-dimensional (3D) substrate. In this work, we demonstrate that an atomic-scale thin amorphous layer atop the substrate surface can remarkably enhance the interfacial thermal conductance (ITC) of the 2D-MoS2/3D-GaN vdW interface by a factor of 4 compared to that of the untreated crystalline substrate surface. Meanwhile, the ITC can be broadly manipulated through adjusting substrate surface roughness. Phonon dynamic and heat flux spectrum analyses show that this giant enhancement is attributed to the increased phonon densities and channels at the interfaces and enhanced phonon coupling. The slight surface fluctuation in MoS2 and the increased diffuse interfacial scattering facilitate energy transfer from MoS2's in-plane phonons to its out-of-plane phonons and then to the substrate. In addition, it is further found that the substrate and its surface topology can dramatically influence the thermal conductivity of MoS2 due to the reduction of phonon relaxation time, especially for low-frequency acoustic phonons. This study elucidates the effects of the amorphous surface of the substrate on thermal transport across 2D/3D vdW interfaces and provides a new dimension to aid in the heat dissipation of 2D-based electronic devices via atomic-scale surface engineering.

THE SUB-ACUTE TOXICITY OF THE DISINFECTIOUS PREPARATION "IODOPOVIDONE"

The results of a preclinical study of the subacute toxicity of the disinfectant "Iodopovidone" are presented. The purpose of the experiment reflected in the article was to continue a series of preclinical studies of the disinfectant Iodopovidone on laboratory animals by examining subacute toxicity, to confirm good animal tolerance and the drug belongs to the 4th toxicity class – low-toxic substances. The experiment was carried out on laboratory white rats, which were kept in the vivarium of the Faculty of Veterinary Medicine of the National University of Life and Environmental Sciences of Ukraine in compliance with the requirements of the European Convention for the Protection of Vertebrate Animals used for scientific experiments or for other scientific purposes and the Law of Ukraine "On the Protection of Animals". The subacute toxicity of the disinfectant "Iodopovidone" was studied using dermal application. The effect of the drug was evaluated by analyzing the change in biochemical parameters of blood serum and hematological parameters of the blood of laboratory animals in dynamics after 6, 24 and 48 hours. The results of determining the parameters of subacute toxicity when applied to the skin indicate the absence of an irritating effect of the drug on the skin. Under the influence of the drug on the organism of animals for six hours, a slight fluctuation in hematological and biochemical blood parameters was revealed, which approached those of the control group of animals within 48 hours, except for the level of glucose, but this did not affect the general condition of the animals. The use of the drug at a dose of 2900 mg/kg of body weight does not cause the death of animals, which confirms the low toxicity of the drug and belonging to the 4th class of toxicity according to the current sanitary and hygienic standards, which is promising for use in poultry farming and requires further studies of chronic toxicity and toxicity in inhalation use.

Features of operation and hydraulic calculations

Issues related to the design and hydraulic calculations of the transit part of a closed tubular water supply structure of the siphon type are considered. The operating conditions of a siphon with rectangular pipes in the transition mode are estimated. Due to the formation of a hydraulic jump, the inlet section of the siphon pipes experiences increased hydrodynamic loads, leading to certain defects and destruction. The design of the siphon with two breaks along the length with a portal and a smooth inlet head or without it was modeled. As a result of modeling studies, the absence of a noticeable effect of the inlet head of the culvert on the length of the free-flow inlet section was established. It was revealed that the conditions of formation, the features of the hydraulic operation of the siphon, and the loads it experiences in the transient mode are largely determined by its design solutions. With the flooding of the inlet head, the flow of air into the pipe is hindered, and a transition mode of the second type is formed with a slight fluctuation in the water level in front of the structure upstream. The dependence of the location of the flow separation point with a decrease in the throughput of water on its value was revealed, which made it possible to obtain a graph of the dependence of the relative length of the free-flow section on the square root of the Froude number. A comparison was made with the results of studies by other authors, which showed an increase in the relative length in tubular structures of the siphon type in sections with reverse slopes at the same Froude numbers. Recommendations are given on the methodology for carrying out hydraulic calculation of tubular culverts for various purposes with minimal flow rates, and ways for further multifactorial studies of siphons on the reclamation network are indicated.

Higher Risk of Sarcopenia in Older Adults with Type 2 Diabetes: NHANES 1999–2018

Introduction: Recent studies suggested that sarcopenia may be a significant comorbidity of diabetes mellitus (DM). Nonetheless, studies with nationally representative data are scarce, and the changing trend of sarcopenia prevalence over time is largely unknown. Therefore, we aimed to estimate and compare the prevalence of sarcopenia in diabetic and nondiabetic US older population, and to explore the potential predictors of sarcopenia as well as the trend of sarcopenia prevalent in the past decades. Methods: Data were retrieved from the National Health and Nutrition Examination Survey (NHANES). Sarcopenia and DM were defined according to corresponding diagnosis criteria. Weighted prevalence was calculated and compared between diabetic and nondiabetic participants. The differences among age and ethnicity groups were explored. Results: A total of 6,381 US adults (>50 years) were involved. The overall prevalence of sarcopenia was 17.8% for US elders, and the prevalence was higher (27.9% vs. 15.7%) in those with diabetes ones than those without. Stepwise regression revealed that sarcopenia was significantly associated with DM (adjusted odds ratio = 1.37, 95% CI: 1.08–1.22; p < 0.05) after controlling for potential confounders including gender, age, ethnicity, educational level, BMI, and muscle strengthening activity. A slight fluctuation but overall increasing trend of sarcopenia prevalence was observed among diabetic elders, while no obvious changing trend was observed in their counterparts in recent decades. Conclusion: Diabetic US older adults face significantly higher risk of sarcopenia when compared with their nondiabetic counterparts. Gender, age, ethnicity, educational level, and obesity were important influencing factors of sarcopenia development.

Status of springs in the mid-hills of Khotang district Nepal, (A case study from Diktel Rupakot Majhuwagadhi and Halesi Tuwachung Municipality)

The study was conducted in Buipa (ward no.14) of Diktel Rupakot Majhuwagadhi municipality and Durchim (ward no.5) of Halesi Tuwachung municipality in Khotang district, Nepal. A total of 45 springs were mapped. The study showed 62.2% of the springs to be open springs, and the rest were modified into concrete structures. Seventy-seven percent of the springs were found to be drying up. The study showed 20% of the springs had dried up already and 17.7% were on the verge of drying. Most of the springs found were depression springs. At Durchim of Halesi Tuwachung, 16 out of 18 springs had discharge rates less than 0.05 l/s. Twelve of these had dried already. Thirty-seven per cent of the springs were located farther than 1km, of which 6.67% were also in a drying condition and more than 51% were farther than 500m. People used springs on various occasions and local festivals. Forty per cent of springs were drying due to landslides and road construction. In the Koshi basin, 78% of annual rainfall occurred during the monsoon and only 2.8% during the dry period. Springs are fully monsoon-dependent and slight fluctuation in the rainfall patterns could greatly affect the discharge in the springs

INFLUENCE OF PATERNAL ORIGIN ON THE MANIFESTATION OF ECONOMIC USEFUL TRAITS IN THEIR DAUGHTERS IN ORGANIC AND CONVENTIONAL MILK PRODUCTION

INFLUENCE OF PATERNAL ORIGIN ON THE MANIFESTATION OF ECONOMIC USEFUL TRAITS IN THEIR DAUGHTERS IN ORGANIC AND CONVENTIONAL MILK PRODUCTION

Biomechanical properties of honeybee abdominal muscles during stretch activation

The mechanical properties of the honeybee's abdominal muscles endow its abdomen with movement flexibility to perform various activities. However, the biomechanical properties of abdominal muscles during stretch activation remain unclear. To clarify this issue, we observed the microstructures of the abdominal muscles to obtain structural information. The similarity and symmetry of abdominal muscle distribution contribute to the ability to drive abdominal movement. Combined with the segmented structure characteristics, an experimental device to measure muscle stretch measurement of honeybees was developed to investigate the mechanical properties of the abdominal muscles. During measurement, the muscles were kept in a solution to maintain a physiological environment. The mechanical properties of abdominal muscles included phases: the ascending phase with proportional increase, stable phase with slight fluctuation, and decay phase with parabolic decline. These findings indicate that the nonlinear and rate-sensitive mechanical properties of the abdominal muscles enable them to rapidly adapt to environmental changes. The stretch force and stiffness coefficient reached 0.660 ± 0.139 mN and 14.364 ± 2.961 N/m, respectively. A simplified biomechanical model of the muscle fiber considering the hierarchical microstructure was introduced, in which the mechanical properties were consistent with the experimental data. Further analysis of the effects of the activation probability and the effective range of binding sites on the mechanical properties demonstrated the critical role in force generation, revealing the mechanism of underlying muscle stretch activation in the honeybee abdomen. The findings can provide a new reference for studying the biomechanical properties of the muscles of other arthropod insects.

Study of thyroid function among COVID-19-affected and non-affected people during pre and post-vaccination.

The novel coronavirus COVID-19 has caused a global pandemic with many long-ranging effects on the physiological balance of the human body. The impact of COVID-19 on the thyroid axis remains uncertain. Our aim was to assess the long-term consequences of COVID-19 infection and its vaccination with thyroid hormones. Thirty laboratory-confirmed COVID-19-positive patients with no vaccination record, thirty COVID-19-negative patients with vaccination records, and ten healthy subjects were retrospectively, and cross-sectionally enrolled in this study. An ELISA assay was performed to evaluate thyroid function tests, including the total triiodothyronine (TT3), total thyroxine (TT4), and thyroid stimulating hormone (TSH). We found decreased levels of TT3, average or low plasma T4 levels, and standard or slightly decreased TSH levels in unvaccinated COVID-19-positive patients than in the healthy group, while the vaccinated COVID-19-negative group had normal thyroid hormone levels compared to controls. The correlation between TT3 and TSH levels gradually shifted from no association to a negative pattern in the unvaccinated COVID-19-positive group. Again, a highly significant negative correlation between TSH and TT3 was observed on days above 150, although a slight fluctuation was noted on day 90. This pilot study from Bangladesh shows that abnormalities in thyroid function can be observed during COVID-19 infection and after vaccination, which gradually recovers over time.

Breast cancer detection using volatile compound profiles in exhaled breath via selected ion-flow tube mass spectrometry

This study aimed to evaluate volatile compounds in exhaled breath as a non-invasive screening method to detect breast neoplasms. Exhaled breath samples were collected from patients with breast cancer (BC; n = 45) and non-breast cancer (NBC; n = 51) controls. Selected ion-flow tube mass spectrometry was used to quantify the volatile compounds. A multiple logistic regression (MLR) model was developed by combining multiple compounds to discriminate between BC and NBC samples. Amongst the 672 quantified peaks, 17 showed significant differences between BC and NBC samples (P < 0.05 corrected by false discovery rate). Pathway analysis revealed a significant difference in glycerophospholipid metabolism. The MLR model showed an area under the receiver operating characteristic curve (AUC) of 0.719 (95% confidence interval: 0.615–0.822, P < 0.0002). Cross-validation under various conditions resulted in a slight fluctuation in the AUC values, indicating the high generalizability of the MLR model. The model showed a higher BC probability for advanced-stage subjects and higher Ki67 (⩾30) for BC subjects. This study suggests the potential of volatile compounds in exhaled breath as a noninvasive screening method for BC.

MonoEF: Extrinsic Parameter Free Monocular 3D Object Detection

Monocular 3D object detection is an important task in autonomous driving. It can be easily intractable where there exists ego-car pose change w.r.t. ground plane. This is common due to the slight fluctuation of road smoothness and slope. Due to the lack of insight in industrial application, existing methods on open datasets neglect the camera pose information, which inevitably results in the detector being susceptible to camera extrinsic parameters. The perturbation of objects is very popular in most autonomous driving cases for industrial products. To this end, we propose a novel method to capture camera pose to formulate the detector free from extrinsic perturbation. Specifically, the proposed framework predicts camera extrinsic parameters by detecting vanishing point and horizon change. A converter is designed to rectify perturbative features in the latent space. By doing so, our 3D detector works independent of the extrinsic parameter variations and produces accurate results in realistic cases, e.g., potholed and uneven roads, where almost all existing monocular detectors fail to handle. Experiments demonstrate our method yields the best performance compared with the other state-of-the-arts by a large margin on both KITTI 3D and nuScenes datasets.

The role of surface activity on the amyloid fibrillation pathway of bovine serum albumin upon interaction with glyphosate

As an active ingredient in its derivative products, glyphosate has emerged as the most widespread herbicide in recent decades. Bovine serum albumin (BSA) as a carrier protein may be adversely affected by structural changes due to binding affinity with glyphosate, which may lead to dysfunctionality or metabolic disorders. This study aimed to investigate the interaction of glyphosate with BSA and its thermal fibrillation pathway employing techniques such as dynamic surface tension, fluorescence quenching, ThT binding, circular dichroism spectroscopy, and reactive oxygen species (ROS) measurement, as well as molecular dynamics (MD) studies. The adsorption dynamic analysis suggested hydrophobic moiety at higher concentrations of glyphosate upon interaction with BSA. MD results suggested a slight fluctuation due to glyphosate interaction with protein molecules. The carboxy group presented in glyphosate made a hydrogen bond with the hydroxyl group of TYR147. The fluorescence quenching and diffusion studies approved BSA's increased unfolding and hydrophobicity resulting from glyphosate interaction, which would induce fibrillation/aggregation, according to our fibrillation kinetics data. The surface activity of glyphosate at higher concentrations and its approved involvement in structural changes of BSA through hydrogen bonding may raise concerns about its potential side effect on farm animals and the food cycle.

The influence of boundary conditions on simulation of pressure wave reflection in a pipe

Previous studies have demonstrated that the flow characteristics of pressure waves in hydraulic experiments show two types of reflected waves: those with the same type pressure vibration trend and those with the opposite vibration trend, with the pressure amplitude equal to that of the original wave. Reflection characteristics in a simulation must be consistent with those found experimentally. To determine reasonable boundary conditions (BCs), the focus of this work was the simulation of pressure wave reflection under five combinations of BCs using computational fluid dynamics. Three three-dimensional simulation models were developed based on the k–ε turbulence model. Reflection characteristics were obtained under the different BCs. The results showed that the pressure boundary in the pipe simulated the reflected waves correctly. The reservoir was found to be more accurate than the pressure boundary, which reflected the slight fluctuation in the reflected wave. Both the wall boundary and the velocity boundary could be used to simulate valve operation. However, if intercepting part of the pipeline, the reflected wave showed phase advance and pressure amplitude attenuation compared with that at the same position in the original pipeline. This study is helpful for setting reasonable BCs in pressure wave simulations.

The Evolution and Global Spatiotemporal Dynamics of Senecavirus A.

Recurrent outbreaks of senecavirus A (SVA)-associated vesicular disease have led to a large number of infected pigs being culled and has caused considerable economic losses to the swine industry. Although SVA was discovered 2 decades ago, knowledge about the evolutionary and transmission histories of SVA remains unclear. Herein, we performed an integrated analysis of the recombination, phylogeny, selection, and spatiotemporal dynamics of SVA. Phylogenetic analysis demonstrated that SVA diverged into two main branches, clade I (pre-2007 strains) and clade II (post-2007 strains). Importantly, analysis of selective strength showed that clade II was evolving under relaxed selection compared with clade I. Positive selection analysis identified 27 positive selective sites, most of which are located on the outer surface of capsid protomer or on the important functional domains of nonstructure proteins. Bayesian phylodynamics suggested that the estimated time to the most recent common ancestor of SVA was around 1986, and the estimated substitution rate of SVA was 3.3522 × 10-3 nucleotide substitutions/site/year. Demographic history analysis revealed that the effective population size of SVA has experienced a gradually increasing trend with slight fluctuation until 2017 followed by a sharp decline. Notably, Bayesian phylogeographic analysis inferred that Brazil might be the source of SVA's global transmission since 2015. In summary, these data illustrated that the ongoing evolution of SVA drove the lineage-specific innovation and potentially phenotypically important variation. Our study sheds new light on the fundamental understanding of SVA evolution and spread history. IMPORTANCE Recurrent outbreaks and global epidemics of senecavirus A-associated vesicular disease have caused heavy economic losses and have threatened the development of the pig industry. However, the question of where the virus comes from has been one of the biggest puzzles due to the stealthy nature of the virus. Consequently, tracing the source, evolution, and transmission pattern of SVA is a very challenging task. Based on the most comprehensive analysis, we revealed the origin time, rapid evolution, epidemic dynamics, and selection of SVA. We observed two main genetic branches, clade I (pre-2007 strains) and clade II (post-2007 strains), and described the epidemiological patterns of SVA in different countries. We also first identified Brazil as the source of SVA's global transmission since 2015. Findings in this study provide important implications for the control and prevention of the virus.

Morphology-controlled synthesis of Cu2O encapsulated phase change materials: Photothermal conversion and storage performance in visible light regime

Microencapsulated phase change materials (MPCMs) are usually limited in photothermal conversion due to their poor visible light absorbability and low thermal conductivity. Owing to a direct band gap of 2.0–2.2 eV, the semiconductor cuprous oxide (Cu2O) has attracted intense interest in solar energy harvest. Shape-dependent optical properties of Cu2O semiconductors are mainly focused on crystals enclosed by three low-index facets ({1 0 0}, {1 1 0} and {1 1 1}). Here, we successfully design and fabricate the Cu2O encapsulated MPCMs from cube, truncated cube, 26-hedron, and truncated octahedron to octahedron under precise control of NaOH. A possible growth mechanism to explore the correlation between selective adsorption of OH− on Cu2O facets and MPCMs shape evolution is suggested based on density functional theory calculations. The thermal analysis shows that the octahedral MPCMs enclosed by {1 1 1} facets possess latent heat of 148.9 J/g and photothermal conversion efficiency of 82.65 % under irradiation of visible light. Differential scanning calorimeter (DSC) profiles of the MPCMs maintain good coincidence with only a slight fluctuation of phase transition temperatures and the associated enthalpies during the 200-cyclic scans, demonstrating excellent phase change reversibility and thermal durability. Our studies unambiguously provide a strategy for tailoring the optical properties of MPCMs to greatly harvest solar energy for green building materials, anti-ice coating etc. in the future.

Experimental investigation on the cuttings formation process and its relationship with cutting force in single PDC cutter tests

The single polycrystalline diamond compact (PDC) cutter test is widely used to investigate the mechanism of rock-breaking. The generated cuttings and cutting force are important indexes reflecting the rock failure process. However, they were treated as two separate parameters in previous publications. In this study, through a series of rock block cutting tests, the relationship between them was investigated to obtain an in-depth understanding of the formation of cuttings. In addition, to validate the standpoints obtained in the aforementioned experiments, rock sheet cutting tests were conducted and the rock failure process was monitored by a high-speed camera frame by frame. The cutting force was recorded with the same sampling rate as the camera. By this design, every sampled point of cutting force can match a picture captured by the camera, which reflects the interaction between the rock and the cutter. The results indicate that the increase in cutting depth results in a transition of rock failure modes. At shallow cutting depth, ductile failure dominates and all the cuttings are produced by the compression of the cutter. The corresponding cutting force fluctuates slightly. However, beyond the critical depth, brittle failure occurs and chunk-like cuttings appear, which leads to a sharp decrease in cutting force. After that, the generation of new surface results in a significant decrease in actual cutting depth, a parameter proposed to reflect the interaction between the rock and the cutter. Consequently, ductile failure dominates again and a slight fluctuation of cutting force can be detected. As the cutter moves to the rock, the actual cutting depth gradually increases, which results in the subsequent generation of chunk-like cuttings. It is accompanied by an obvious cutting force drop. That is, ductile failure and brittle failure, one following another, present at large cutting depth. The transition of rock failure mode can be correlated with the variation of cutting force. Based on the results of this paper, the real-time monitoring of torque may be helpful to determine the efficiency of PDC bits in the downhole.

Genetic Mechanism of Tissue-Specific Expression of PPAR Genes in Turbot (Scophthalmus maximus) at Different Temperatures.

In this study, we used PCR to measure the levels of the peroxisome proliferator activated receptor genes PPARα1, PPARα2, PPARβ, and PPARγ in the intestine, liver, gill, heart, kidney, brain, muscle, spleen, skin, and stomach of turbot (Scophthalmus maximus) cultured under different temperature conditions (14, 20, 23, 25, and 28 °C). We used split-split-plot (SSP) analysis of variance, additive main effects and multiplicative interaction (AMMI) analysis, and genotype main effects and genotype × environment interaction (GGE) biplot analysis to evaluate the genotype × tissue interaction effects on gene expression. The results of the SSP analysis of variance showed that temperature and tissue × gene have highly significant (p < 0.01) effect on the expression of S. maximus PPAR genes. The AMMI analysis results revealed that the expression of PPAR genes at the appropriate temperature (14 °C) mainly depended on genotype × tissue interaction and tissue effects. Under stress temperatures, genotype effects, tissue effects, and genotype × tissue interaction, all had significant effects on the expression of PPAR genes. The contribution of the genotype effect slowly increased with increasing temperature; it increased faster at 20 °C and then slowly declined at 25 °C. The contribution of the tissue effect slowly increased from 14 to 20 °C, where it sharply decreased, and then it stabilized after a slight fluctuation. The contribution of the genotype × tissue interaction effect showed a fluctuating upward trend throughout the experiment, and it had a significant impact on PPAR gene expression. The key temperature at which the three effects changed was 20 °C, indicating that it is the limit temperature for active lipid metabolism under high-temperature stress. The GGE biplot analysis results showed that under suitable water temperature, the expression difference of PPAR genes in the liver was the largest; at 20 and 23 °C, the expression difference in the gill was the largest; and at 25 and 28 °C, the expression difference in the brain was the largest. Overall, our results suggest that the mechanism responsible for PPAR gene expression under the three high temperatures (23, 25, and 28 °C) was relatively consistent, but it differed from that at 20 °C.

Visualization of Global Research Output on Disruptive Innovation in Health Care

ABSTRACT The outbreak of COVID-19 has raised concerns about the availability of health care facilities globally. Disruptive innovations in health care may impact a new system that provides a continuum of treatment tailored to each patient’s specific requirements. In light of this evolution, this study aimed to visualize global research output on disruptive innovation in health care between 2001 to 2021 as indexed in the Scopus database. The dataset was extracted on January 10, 2022, and 204 records were identified for data analysis. Various bibliometric indicators were used to identify publication trends. VOSviewer visualization software was also used to analyze data. The findings revealed the increasing pattern of publication growth with slight fluctuation over time. M. Friebe was the most prolific author having contributed four publications. The Harvard Medical School was the most productive institution with eight publications and the United States was the most productive country with 84 publications on disruptive innovation in health care. Furthermore, human, health care, and disruptive innovation were the top keywords in this field. These findings are expected to be useful to academics and administrators all across the world. This study also gives readers insight into this domain and will allow them to begin their research by selecting a topic of their choice.

Coupling Amorphous Ni Hydroxide Nanoparticles with Single-Atom Rh on Cu Nanowire Arrays for Highly Efficient Alkaline Seawater Electrolysis.

Exploring efficient catalysts for alkaline seawater electrolysis is highly desired yet challenging. Herein, coupling single-atom rhodium with amorphous nickel hydroxide nanoparticles on copper nanowire arrays is designed as a new active catalyst for the highly efficient alkaline seawater electrolysis. We found that an amorphous Ni(OH)2 nanoparticle is an effective catalyst to accelerate the water dissociation step. In contrast, the single-atom rhodium is an active site for adsorbed hydrogen recombination to generate H2. The NiRh-Cu NA/CF catalyst shows superior electrocatalytic activity toward HER, surpassing a benchmark Pt@C. In detail, the NiRh-Cu NA/CF catalyst exhibits HER overpotentials as low as 12 and 21 mV with a current density of 10 mA cm-2 in fresh water and seawater, respectively. At high current density, the NiRh-Cu NA/CF catalyst also exhibits an outstanding performance, where 300 mA cm-2 can be obtained at an overpotential of 155 mV and shows a slight fluctuation in the current density over 30 h.

Microscopic Response of Limestone Physical Deterioration under Water-Rock Alternation in the Acidic Environment

In order to investigate the microscopic response mechanism of limestone deterioration under alternating water-rock action in the acidic environment, the porosity, water absorption, mass loss characteristic, and microcrack propagation characteristic were analyzed by laboratory wetting-drying cyclic tests. The results show that, with increasing the number of cycles, the porosity, water absorption, and mass deterioration of the limestone specimens showed an overall increasing trend; moreover, at the beginning of the cycles, the physical deterioration of the specimen was significantly affected by the wetting-drying cycles, and at the end of the cycles, the physical deterioration of the specimen tended to be stable. The porosity deterioration degree reached 30.324% at the beginning of the cycles; there is a slight fluctuation in 20 cycles and then decreases as the number of cycles increases. The growth rate of water absorption increases slowly in 5~15 cycles and reaches the peak value in 20 cycles, and the growth rate decreases rapidly in the latter stages of the cycles. The increase rate of mass deterioration degree decreases with the increase of cycle number, the maximum average value can reach 61.887% at the beginning of cycles and is relatively stable at 20~25 cycles, and the average value at the end of cycle is obviously reduced by 3.167%. The nuclear magnetic resonance (NMR) test shows that the number and size of pores in the rock gradually increase with the increase of the number of wetting-drying cycles, and the wetting-drying cycles aggravate the internal damage of the rock. The number of shear cracks and fragmentation of the specimens increase as the increase of the number of cycles, and the failure of the specimens is mainly in the form of shear damage in the uniaxial compression test.

Изменения некоторых показателей жироотложения и компонентов состава тела в процессе полового созревания у подростков Архангельского региона и г. Москвы

Introduction. This work is devoted to the study of changes in some indicators of subcutaneous fat deposition and body mass components depending on the rate of puberty in adolescents of the Arkhangelsk region and Moscow. Materials and methods. The analysis used data from 1 516 people aged 12 to 16 years in the case of boys and 11 to 15 years in the case of girls. The anthropometric examination, the analysis of the body composition and the assessment of the puberty stage were carried out according to the standard methodology in compliance with bioethical recommendations. Probit analysis was used to determine the timing of pubertal stages. Results and discussion. According to the results obtained, adolescents of all three groups have the usual sequence of appearance of secondary sexual characteristics. In addition, standard patterns are observed: urban schoolchildren go through the stages of puberty earlier than their rural peers. As for the change in anthropometric characteristics depending on the stage of puberty, in this case, the consistency of the changes occurring with the maturation of the mammary glands in girls and the appearance of pubic hair in boys is confirmed. In the former, the amount of body weight and its fat component, as well as the thickness of the skinfolds, are more dependent on the stage of puberty; in the latter, the girth dimensions. Regardless of sex, the examined signs in their absolute magnitude show a tendency to increase, while the relative body fat mass decreases with breast development in girls. In young men, the alternation of the processes of its increase and decrease was recorded as the development of pubic envelopment progressed from stage to stage. The exception is Muscovites, in whom, with the appearance of this sign, there is a sharp significant increase in body fat mass with a further slight fluctuation during puberty. Conclusion. The dependence of the parameters of fat deposition on biological age is more clearly manifested in groups of girls, since for male individuals the degree of maturation is more correlated with the muscular component. In this case, the characteristics of the fat component begin to show a coherent picture at the final stages of puberty.