Mass Coefficients Research Articles

Analysis of shear creep damage model of slope rock mass under the influence of coupled damage effects (DBSM)

Abstract This article reveals the evolution law of shear creep damage of carbonaceous shale (weak interlayer of slope) under dynamic load from a mechanical perspective by combining indoor experiments and theoretical research. Firstly, a coupled damage variable D BSM was established for the initial damage D 0 and dynamic disturbance shear creep damage D BS of rock mass based on the theory of damage mechanics. Secondly, according to the fractional calculus operator theory and considering the influence of coupled damage variable D BSM on the viscosity coefficient of rock mass in the viscoelasticity and viscoplasticity creep stages, a shear creep damage model of rock mass was established. At the same time, combined with the shear creep test data under the influence of dynamic loads, the damage evolution law of shear creep in carbonaceous shale (weak interlayer of slope) was revealed, and the accuracy of the established shear creep damage model was verified. Finally, the damage evolution law of carbonaceous shale was quantitatively analyzed. Results show that: The shear creep damage model established in this article has unique advantages. The greater the initial damage, the more likely shear creep failure is to occur under the influence of dynamic disturbance and shear creep loads. Dynamic disturbance accelerates the damage of weak interlayers of slope. The cumulative coupling damage of carbonaceous shale (D ma ≤0.18) under dynamic disturbance and multi-stage shear creep loads exhibits an S-like evolution pattern. The shear creep damage mechanism of carbonaceous shale is characterized by obvious initial damage effect, dynamic disturbance damage effect, and stress response characteristics.

The Aerodynamic Assessment and Shot Point Position Accuracy of UAV Seismic Source

An unmanned aerial vehicle (UAV) seismic source, suitable for complex terrains due to its eco-friendly, cost-effective, and efficient nature, operates by hovering and releasing impact objects to generate seismic waves. The aerodynamic behavior of these impact objects is vital for shotpoint position accuracy and drag magnitude. Excessive drag will result in the loss of seismic source energy, whereas the deviations of the shotpoint position will disrupt the geometric structure of the observation system, significantly impacting the quality of seismic data acquisition. Through theoretical calculations, the influencing factors of air resistance and cross-wind deflection are analyzed. Air resistance increases with the increase in mass, cross-sectional area, speed, and drag coefficient. Increasing the mass and throwing height can increase the upper limit of the output, but after the air resistance and gravity are balanced, the output kinetic energy of the drone’s seismic source will no longer increase when the throwing height is increased. Using computational fluid dynamics simulations and field tests, this study examines the aerodynamics of four prevalent impact object designs. The results show that shuttle and spherical structures have the least drag during descent and are less influenced by crosswinds, thus being optimal for this application. Field measurement data are also presented for reference.

Practical 6-DoF Manoeuvring Simulation of a BB2 Submarine Near the Free Surface

It is necessary to predict the manoeuvring performance of a submarine accurately at the early design stage for its safe and effective operations. In this paper, the practical 6-DoF simulation models of an X-form stern plane submarine operating near the free surface are proposed. A 1/15 scaled model of ‘BB2 submarine’ is constructed, the captive model tests are performed in a towing tank of Korea Research Institute of Ships and Ocean Engineering (KRISO) at the full-scale depths, 30, 15.4 (snorkel depth), and 4.5 metres (surfaced depth). Resistance and propulsion tests are performed at the deepest depth, 30 metres. The vertical planar motion mechanism (PMM) tests including the forced rolling motions are also carried out at the depth of 30 metres. The horizontal PMM tests are conducted at three kinds of depths, respectively. The depth-varying horizontal plane coefficients in the model are identified, and the coefficients which are little influenced by the depths are treated as the constant values for the practical purpose. Some of velocity coupled terms are approximated by using the added mass coefficients on the assumption that the viscous components are negligible. In addition, the resistance increases, vertical suction forces and moments are measured in the straight-ahead tests with varying the submergence depths. The free surface effects are considered as the exponential function terms in the proposed models. Based on the present tests and the previous studies about the free surface effects on the submerged bodies, it is practically assumed that the free surface effects are exponentially decayed with the depths, and are already negligible when the submergence depth is 30 metres, approximately three times the hull depth. Horizontal and vertical plane manoeuvring motions as well as the neutral flights are simulated with the control plane deflections less than 15 degrees. The present simulations are in good agreements with existing free-running model test results.

Delayed effects of antibiotic therapy in endotoxinemia

BACKGROUND: Nowadays, due to the increasing number of infectious and inflammatory diseases, the problem of the use of antibacterial drugs becomes especially important. As a result of the action of toxins, inflammatory processes can affect the central nervous system with the subsequent development of neuroinflammation. Activation of neuroinflammation leads to dysregulation of many physiological functions. These negative appearances can be observed even after a long period. It is known that doxycycline is a tetracycline-type antibiotic, which is able to penetrate the blood-brain barrier and has anti-inflammatory activity. AIM: The aim of this study was to investigate the nature of delayed physiological changes in rats against the background of administration of the antibacterial drug doxycycline in the LPS-induced model of neuroinflammation. MATERIALS AND METHODS: Four groups of Wistar rats, 10 males in each group, were used in the experiment. The first group was injected once intraperitoneally with physiological solution, the second group — with lipopolysaccharide (1 mg/kg). Animals of the third and fourth groups received intragastrically doxycycline solution (25 mg/kg) daily for two weeks. On the 15th day of the experiment, rats from the fourth group were injected with lipopolysaccharide (1 mg/kg). Body weight of animals, mass coefficients of immunocompetent organs, as well as behaviour and motor activity of rats in the “Open Field” test were evaluated at several time points. RESULTS: It was shown that systemic injection of lipopolysaccharide led to an increase in the mass coefficients of spleen, kidneys and adrenal glands compared to the group of animals receiving doxycycline beforehand. These changes were noted 48 h and 2 months after the injection of endotoxin. In the “Open Field” test, animals that were injected with doxycycline and lipopolysaccharide showed no violations of motor activity and research behavior, unlike the group that received only lipopolysaccharide. CONCLUSIONS: It can be assumed that the physiological effects of doxycycline in the lipopolysaccharide-induced model of neuroinflammation revealed at early and late terms are not limited to the antibacterial effect of the drug and are mediated by anti-inflammatory and potential neuroprotective effects on the central nervous system.

Systemic manifestations of connective tissue abnormalities in patients with Mitral Valve Prolapse assessed by Cardiac Magnetic Resonance

Abstract Background Mitral valve prolapse (MVP) reflects a connective tissue abnormality of the mitral leaflets leading to myxomatous degeneration. Early echocardiography and semeiotic assessment investigations suggested that connective tissue abnormalities might be extended to heart chambers, great vessels, and the skeletal system. Cardiac Magnetic Resonance (CMR) has unique potentials in evaluating MVP, cardiac chambers, aortic dimensions, and Haller Index, an expression of the deformity of the thoracic cage, at one time. Purpose We aimed to investigate the potential phenotypic systemic expressions of connective tissue disease in patients with MVP by CMR assessment. Methods This case-control study included consecutive patients with MVP and a control group of healthy volunteers undergoing CMR at our Institution from September 2020 to November 2023. Patients with more than mild mitral or aortic regurgitation, bicuspid aortic valve, or known systemic connective diseases were excluded. The MVP, cardiac chambers, aortic dimensions, and Haller Index were assessed according to standard practice. Results 103 patients with MVP and 57 healthy volunteers (51± 17 vs. 47±18 years, p=0.2, and 5% females vs. 54.4% females, p=0.8, respectively) were enrolled. Patients with MVP showed greater left ventricular end-diastolic (91±25 vs. 78±17 ml/m2; p=0.005) and end-systolic volumes (36±12 vs. 27±6; ml/m2; p<0.001), aortic annulus (13±2 vs. 12±2 mm/m2; p<0.001), sino-tubular junction (15±3 vs. 14±3 mm/m2; p=0.03), aortic root (19±3 vs. 17±3 mm/m2; p<0.001), and descending aorta (13±2 vs. 12±2 mm/m2; p=0.03), and higher Haller Index (2.8±0.6 vs. 2.6±0.4; p=0.02) than healthy controls. No differences were found in ascending aorta (18±3 vs. 17±3 mm/m2; p=0.3), pulmonary trunk (13±2 vs. 13±2 mm/m2; p=0.5), left atrial volume (38±18 vs. 30±15 ml/m2; p=0.20), right ventricular end-diastolic-volume (86±20 vs. 81±20 ml/m2; p=0.3) were found. At ANCOVA, sex and MVP affected the Haller Index values (p = 0.005 and 0.04). The association between MVP and Haller Index persisted after controlling for sex, age, and body surface area. In multivariate regression analysis, MVP and sex had an independent impact on ventricular and aortic dimensions, with MVP and male patients showing greater values. In particular, MVP was associated with an increase in the aortic annulus (Coefficient=1.2; p< 0.001), aortic root (Coefficient=1.5, p=0.001), descending aorta (Coefficient=0.7, p = 0.026), left ventricular end-diastolic-volume (Coefficient=11.1, p=0.01) and mass (Coefficient=5.7, p=0.02) after controlling for sex, age, and body surface area. Conclusions This pivotal study assessing systemic connective tissue disorders by CMR suggests abnormalities in the aorta and the skeletal system of patients with MVP, paving the way to larger investigations exploring the clinical impact of these findings.CMR findings in the study populationBox plots showing variables distribution

Association between GDF-15 levels and cardiac morphology and function in cardiac magnetic resonance imaging: insights from UK Biobank data analysis

Abstract Background/Introduction Growth Differentiation Factor-15 (GDF-15) has emerged as a biomarker associated with cardiovascular disease and adverse cardiac outcomes. Cardiac morphology and function, assessed through cardiac magnetic resonance imaging (CMR), are critical indicators of cardiovascular pathology. Understanding the relationship between GDF-15 levels and LV characteristics could provide valuable insights into cardiac pathophysiology and disease progression. Purpose This study aims to investigate the association between GDF-15 levels and cardiac morphology and function, utilizing data from the UK Biobank and CMR. By analyzing various CMR-derived parameters, including LV strain, myocardial mass, LV mass-to-volume ratio, ventricular and atrial volumes, we seek to elucidate the impact of GDF-15 on cardiac structure and function. Methods Data from the UK Biobank, including 2,264 participants, were analyzed. The median age of the analyzed participants was 55 years, with a median BMI of 26.0. Among the participants, 53% were females and 47% were males. CMR-derived variables related to cardiac morphology and function, along with GDF-15 levels, were examined. Multiple linear regression models were constructed to assess the association between GDF-15 levels and cardiac parameters, adjusting for age, sex, and other relevant covariates. Confidence intervals (CI) and p-values were calculated to determine the significance of observed associations. Results Analysis of the UK Biobank data revealed significant associations between GDF-15 levels and specific cardiac parameters (table1). Notably, GDF-15 levels were negatively associated with LV myocardial mass (LVM)(coefficient = -1.146, p = 0.0071), LV end-diastolic volume LVEDV)(coefficient = -3.321, p < 0.0001), LV end-systolic volume (coefficient = -1.876, p < 0.0001), as well as right atrial maximum volume (coefficient = -3.025, p < 0.0001) and minimum volume (coefficient = -1.858, p = 0.0003). In addition, LVM/LVEDV was positively associated with GDF-15 level (p<0.03). However, no significant associations were observed between GDF-15 levels and LV strain parameters, ejection fraction, or left atrial volumes. Conclusion This study provides evidence of a significant association between GDF-15 levels and selected parameters of cardiac morphology and function, as assessed by CMR in the UK Biobank population. These findings suggest a potential role of GDF-15 in modulating specific aspects of cardiac structure, function and left ventricle concentric remodeling warranting further investigation.GDF 15

Roles of defects in perovskite CsPbX3 (X=I, Br, Cl): a first- principles investigation

Inorganic lead halide perovskite CsPbX3 (X=I, Br, Cl) have a promising application in optoelectronic fields due to their excellent photovoltaic properties. The defects, which have a significant impact on the performance of materials, are often introduced during the synthesis process. However, there is still a lack of systematic theoretical investigation of the effects of these defects. In this study, the effects of vacancies and H-atom interstitial point defects on the structural, electronic and optical properties of CsPbX3 are systematically investigated by using first-principles approach based on density-functional theory. The calculated results show that the introduction of different defects have significantly effect on the band gap, effective mass, semiconductor properties, ion migration and optical absorption coefficient of the perovskite materials. It is also found that VCs and VPb defects introduce shallow transition levels that do not negatively impact the optoelectronic properties. However, VX and interstitial H defects generate deep transition levels within the bandgap, which acts as non-radiative recombination centers and reduce the optoelectronic performance of the perovskite material. This study contributes to the understanding of the nature of halide chalcogenides and optimally regulating the performance of optoelectronic devices.

Некоторые особенности токсикологических свойств специфического иммунобиостимулятора «Трансфер-фактор» в доклинических испытаниях

Abstract. The purpose of the study is to evaluate some aspects of toxicological safety of a specific immunobiostimulant “Transfer factor” in laboratory animal models. Methods. The experiments were performed on mice, rats and guinea pigs. The toxicological safety assessment of the “Transfer factor” preparation included the determination of the following characteristics: chronic toxicity, assessment of specific activity, assessment of embryotoxic and teratogenic properties, assessment of allergenic properties Results. It was established that the introduction of the “Transfer factor” preparation in a chronic toxicological experiment is accompanied by the development of muscle tremor in the rodents’ body, the duration of which depends on the administered dose, route of administration and exposure time, but their body weight increases by 6.29–10.63 %. Autopsy of experimental group animals revealed no visible changes in the arrangement of internal organs and fluid accumulation in the abdominal and pleural cavities, although some pathological changes in color, consistency and size of the lungs, spleen, liver and heart were noted. The mass coefficients of these organs change with an increase in the dose of the administered drug “Transfer factor”, especially with the intraperitoneal route of administration up to 10.39 %. The tested drug in the reaction of lymphocyte blast transformation increases the number of blasts from 0.20 to 1.40 %. The totality of data allows us to state that the drug “Transfer factor” in accordance with GOST 12.1.007-76 belongs to the IV hazard class “low-hazard substances” and it can be recommended for further clinical trials, in which a dosage exceeding 6 ml/kg of live weight will not be used, when administered to laboratory animals, a complex of changes in the internal organs develops. Scientific novelty. The introduction of “Transfer factor” does not affect the condition and functions of the reproductive organs (uterus, ovaries) of pregnant rats, and the drug does not exhibit a negative embryotoxic and teratogenic effect in their body. When studying the allergenic properties of the drug, it was found that it does not cause a general anaphylaxis reaction in the body of guinea pigs, does not irritate the skin in the reaction of immune complexes and the conjunctiva of the eye in the conjunctival test.

Effects of water quality and nitrogen on wheat productivity: Experimental and modelling study using the SALTMED model

AbstractThe effects of different water qualities and nitrogen doses need to be investigated for wheat growth to determine the optimal management strategy for sustaining wheat production potential to ensure human food security. Therefore, a 2‐year study (2020–2021 to 2021–2022) was conducted on wheat irrigated with different water qualities, including canal water (Ca), tubewell water (Tu) and mixed Ca‐Tu water (Mx), each fertilized with two nitrogen doses, that is, N75 = 75 kgN.ha−1 and N100 = 100 kgN.ha−1. Ca⨯N100 performed best, with 5.12 t.ha−1 grain yield, 11.60 t.ha−1 biomass, 102.83 cm plant height and 1.32 kg.m−3 water productivity. The best values of the root mean square error (RMSE), normalized root mean square error (NRMSE), coefficient of determination (R2) and coefficient of residual mass (CRM) were 0.11, 0.12, 0.93 and −0.004, respectively, for calibration and 0.13, 0.15, 0.87 and ±0.01, respectively, for validation of the SALTMED model. The scenario simulation was performed for additional levels of water salinity (electrical conductivity [EC] = 8 and 12 dS.m−1) and nitrogen doses (50, 125, 150 and 175 kgN.ha−1). The results revealed improvements in wheat grain yield of 107%, 16% and −6% at EC = 8 dS.m−1 and 125%, 31% and 5% at EC = 12 dS.m−1, while the improvements in biomass were 113%, 22% and −2% at EC = 8 dS.m−1 and 137%, 29% and 8% at EC = 12 dS.m−1 with increasing nitrogen doses from 50–125 kg.ha−1, 125–150 kg.ha−1 and 150–175 kg.ha−1, respectively. It is recommended that high‐quality water with the lowest possible EC and nitrogen applications of up to 150 kgN.ha−1 be adopted for wheat production in semi‐arid areas of Punjab, Pakistan.

Justification of the possibility of using liquid artificial lung ventilation for the treatment of acute respiratory distress syndrome of toxic genesis

Introduction. Pulmonotoxicants are chemicals that cause bronchospasm and damage to the alveolar capillary membrane. Lesions of the respiratory system with pulmonotoxicants in industrial accidents are especially relevant at the present time. Existing methods of treatment for the defeat of pulmonotoxicants and the development of acute respiratory distress syndrome (ARDS) are becoming ineffective, therefore, one of the tasks of modern medicine is to develop new methods of treating ARDS. One of these methods may be the creation of a "therapeutic window" by using perfluorocarbon (PFC) liquids. This article will present an experimental assessment of the use of liquid artificial lung ventilation (LALV) PFC liquids on the ARDS lung model. The study aims to explore the possibility of using liquid artificial lung ventilation to create a therapeutic window in the treatment of acute respiratory distress syndrome of a chemical nature. Materials and methods. The authors conducted a study on male Wistar rats aged 4 months, weighing 180–190 g. Toxic pulmonary edema was caused by endotracheal administration of 0.1 m HCl solution. The anesthetized patients were intubated using a cannula, after which the researchers intratracheally injected 0.1 M HCl solution at a dose of 2 ml/kg, a decrease in saturation below 80 was expected. Then the experts randomized the animals by weight into groups of 6 individuals each. They connected the animals of the control group to a ventilator. The animals of the experimental group were treated with PFC liquids for an hour, then transferred to a ventilator. Perfluorodecalin was used as a PFC liquid. The scientists recorded heart rate, blood oxygen saturation, rectal temperature, life expectancy and overall survival by group. Results. In the control group, after instillation of 0.1 M HCl solution and connection to a ventilator during the first 25–30 minutes, there was a gradual decrease in SpO2 to 74.0±5.6% (background — 95.0±3.5%) and an increase in heart rate to 182.0±8.6 beats/min., (background — 278.0±14.8 beats/min.) after which there was decompensation of the animal condition. In animals of the experimental group, after connecting to the LALV device, a sharp decrease in heart rate was recorded during the first 5 minutes to 61.0±8.5 beats/min. In turn, saturation did not change significantly throughout the LALV and was in the range from 95 to 100%. As a result of the experiments, it was noted that the average survival time in the experimental group was 256.0±34.5 minutes, which was significantly (p<0.001) more than 5 times higher than this indicator in the control animals — 45.3±4.3 minutes. There were no significant changes in the study of rectal temperature in the animals of the control group. In turn, the animals of the experimental group showed a sharp decrease in rectal temperature during the first 30 minutes from the beginning of LALV, on average by 5.8±1.60°С. As a result of the pathoanatomic autopsy, differences in lung mass coefficients were revealed in different groups. Thus, in the control group and the experimental groups, it was 1.67±0.06 and 2.4±0.045%, respectively. Conclusion. On the model of ARDS caused by endotracheal administration of 0.1M hydrochloric acid solution, it was shown that living with the use of PFC of low temperature liquids, unlike conventional mechanical ventilation, allows for a long time to maintain a stable condition of animals; evacuate a significant amount of edematous fluid from the lungs and thereby increase the duration of their survival. The data presented above indicate that the use of hypothermic LALV can be used to create a "therapeutic window" for ARDS, including its most severe form — the alveolar stage of toxic pulmonary edema. Ethics. Studies involving laboratory animals were conducted in compliance with the following regulations: the Helsinki Declaration of 2000 "On humane treatment of animals", Order No. 755 of the Ministry of Health of the USSR dated 08/12/1977 "Rules for carrying out work using experimental animals", Order No. 199n of the Ministry of Health of the Russian Federation dated 04/01/2016 "On approval of the rules of laboratory practice". The protocol of the study was approved by the Ethics Committee of the Izmerov Research Institute of Occupational Health. Protocol No. 4 dated May 25, 2022.

Mass and Thermodiffusion in Non-equilibrium Fluctuating Hydrodynamics

Mass and thermodiffusion are transport phenomena in fluid mixtures important in many applications. In this paper it is argued that these transport phenomena have even become more interesting in view of some surprising discoveries from fluctuating hydrodynamics leading to possible new emerging issues in non-equilibrium thermodynamics. A short review of the history of this subject is presented. The paper then addresses the problem that the conventional mass and thermodiffusion coefficients depend on the frame of reference. A simple solution to this problem is elucidated.

Viscous effects on the hydrodynamic performance of a two-body wave energy converter with a damping plate

In this study, the hydrodynamic forces and power absorption performance of an autonomous underwater vehicle (AUV)-based two-body wave energy converter (2BWEC) are investigated. A theoretical model is developed within the framework of linear potential flow to solve for added mass, radiation damping, and wave excitation force using the matched eigenfunction expansion method (MEEM). A computational fluid dynamics (CFD) model is employed to account for vortex-shedding effects of the floater and inner cylinder with a damping plate under various excitation conditions. Empirical formulas for supplementary added mass and drag coefficients caused by flow separation are proposed based on curve-fitting the differences between CFD results and MEEM calculations. These formulas are integrated into motion equations to enhance accuracy in evaluating the power absorption of the 2BWEC. It has been found that in the context of viscous flow, both the added mass and damping coefficients are increased, particularly for the inner cylinder with a damping plate. In addition, the viscous hydrodynamic coefficients exhibit strong dependence on the Keulegan–Carpenter number, while showing insensitivity to changes in the frequency parameter β. The supplementary (viscous) added mass provides additional inertia for the AUV with a limited mass itself, which is advantageous for the power absorption of the AUV-based 2BWEC. Conversely, the presence of viscous damping from the damping plate impedes wave energy capture.

Morphofunctional changes in the internal organs of laying hens affected by chronic thiamethoxam intoxication

Insecticides play an important role in agriculture, general sanitary and veterinary practices, providing protection of the plants and yield from harmful insects and preventing the spread of arthropods which cause diseases in people and animals. Therefore, the objective of our study was to analyze the morphofunctional changes in the internal organs of laying hens affected by chronic intoxication with Actara 25 WG (thiamethoxam). Identification of the toxic action of theamethoxam was carried out in 150 day-old laying hens. The chronic intoxication with the insecticide was modeled by feeding mixed feed treated with the preparation in the doses that were calculated in mg of the active compound per 1 kg of body mass. The birds of the one group were the control and received mixed feed with no supplements. The hens of the first experimental group were given mixed feed that contained the insecticide in the dose of 360 mg/kg of body mass, and hens of the second experimental group consumed mixed feed containing the preparation in the dose of 180 mg/kg per body mass. We determined that laying hens of Experimental Group 1 had significant 1.24-fold decrease in the ventriculus and significant 1.39-fold increase in the spleen. Laying hens of Experimental Group 2 were observed to have increase in the absolute mass of the heart, measuring 1.36-fold compared with the control and 1.34-fold compared with Experimental Group 1. At the same time, the absolute masses of the spleen, liver, and ventriculus in Experimental Group 2 were 1.20, 1.46, and 1.19 times lower than in Experimental Group 1. Compared with the control, the absolute mass of the liver and ventriculus, was 1.54 and 1.48 times lower, respectively. Intake of feed with thiamethoxam by laying hens of the experimental groups led to decrease in the coefficient of relative mass of the liver and ventriculus. Those results significantly correlated with the absolute mass values of those organs, indicating the toxic impact of the insecticide on laying hens, with the digestive organs being the first to react. In Experimental Group 1 chickens, we observed dystrophic-necrotic changes in the liver, round-cell infiltration of the portal tracts; dystrophic-necrotic changes in epitheliocytes of the nephrons of the kidneys’; granular dystrophy of cardiomycetes, plethora of the capillaries, and stasis and edema of the stroma in the myocardium; pericellular edemas in the brain; mucous dystrophy, desquamation of the epithelium of the mucous membrane, decrease in lymphocytes in the lymphoid structures, and atrophy of the epithelium of the glandular structure in the stomach; hyperemia and necrosis of the villus tips, and round-cell infiltration of the crypt region in the thin intestine; and reproduction of cellular elements of the connective tissue between the crypts in the thin intestine. The insecticide in the dose of 180 mg/kg of body mass caused dystrophic-necrobiotic changes in the liver and kidneys; hyperemia and edema in the myocardium; pericellular edema, swelling, and vacuolar dystrophy of neurons in the brain; necrobiotic changes in the mucous membrane epithelioctes in the proventriculus; and deformation of the villi and edema of the mucous membrane in the small intestine.

Rapid identification of the coefficient of moisture expansion of polymer materials by the employment of plates with asymmetric concentration fields

The paper pursues the development of a novel methodology for the rapid identification of the diffuso-mechanical properties of polymer materials based on the employment of plates subject to asymmetric moisture concentration fields. The study is carried out on epoxy plate samples equipped with a thin aluminium foil on a surface exposed to the environment to promote asymmetric moisture absorption. The asymmetric moisture fields promote deformations of the plate. Mass gain and plate curvatures are measured as a function of time during conditioning. By using a weakly coupled diffuso-mechanical model: 1D Fick’s diffusion model and 2D plane stress hygroelastic model the diffuso-mechanical properties of the material can be then identified. Due to the chosen size of the experimental samples the present study allows the identification of the coefficient of moisture expansion of the epoxy material. For the material under study, the following values can be identified for saturation mass gain, water diffusivity and coefficient of moisture expansion respectively: 1.67%, 0.025 mm2.h−1, 0.1628.

Improving CO2 adsorption efficiency of an amine-modified MOF-808 through the synthesis of its graphene oxide composites

This research developed a novel composite of MOF-NH2 and graphene oxide (GO) for enhanced CO2 capture. Employing the response surface methodology-central composite design (RSM-CCD) for experiments design, various MOF-NH2/GO samples with GO loadings from 0 to 30 wt% were synthesized. The results of SEM, XRD, EDS, and BET analysis revealed that the materials maintained their MOF crystal structure, confirmed by X-ray diffraction, and exhibited unique texture, high porosity, and oxygen-enriched surface chemistry. The influence of temperature (25–65 °C) and pressure (1–9 bar) on CO2 adsorption capacity was assessed using a volumetric adsorption system. Optimum conditions were obtained at weight percent of 22.6 wt% GO, temperature of 25 °C, and pressure of 9 bar with maximum adsorption capacity of 303.61 mg/g. The incorporation of amino groups enhanced the CO2 adsorption capacity. Isotherm and kinetic analyses indicated that Freundlich and Fractional-order models best described CO2 adsorption behavior. Thermodynamic analysis showed the process was exothermic, spontaneous, and physical, with enthalpy changes of − 16.905 kJ/mol, entropy changes of − 0.030 kJ/mol K, and Gibs changes energy of − 7.904 kJ/mol. Mass transfer diffusion coefficients increased with higher GO loadings. Regenerability tests demonstrated high performance and resilience, with only a 5.79% decrease in efficiency after fifteen cycles. These findings suggest significant potential for these composites in CO2 capture technologies.

A study on the drag coefficient of emergent flexible vegetation under regular waves

The drag coefficient is a vital quantitative indicator within the field of wave attenuation by vegetation, thus receiving considerable critical attention. A systematic understanding of the drag coefficient under single flexible vegetation dynamic and emergent conditions is still insufficient. The present study aimed to quantitatively investigate the drag coefficient of emergent flexible vegetation based on a flume experiment and an emergent flexible vegetation dynamic model. Simulation results demonstrated the acceptability of constant skin friction coefficient and added mass coefficient in simulating the vegetation dynamics and determining the drag coefficient. Based on the calibration method, the obtained drag coefficients are more influenced by the Reynolds number, the Cauchy number, and the drag-to-stiffness ratio under the present investigation conditions. Vegetation flexibility can have evident influences on the drag coefficient of emergent flexible vegetation under waves. Then, a new empirical formula including the drag-to-stiffness ratio and relative vegetation length was proposed to estimate the drag coefficient. The effectiveness of the formula was demonstrated after evaluating the performance in both calculating the drag coefficient and simulating the emergent flexible vegetation dynamics. This study also provided evidence for the uncertainty in the formula establishment, and identified the uncertainty that different determination methods of characteristic wave velocity and utilizations of wave theory can lead to in the formula establishment. The findings can contribute to the understanding of the drag coefficient of emergent flexible vegetation, and highlight the potential usefulness of other parameters associated with vegetation flexibility in drag coefficient prediction.

Study on Key Parameters and Design Methods for the Density-Mix Proportion of Rubber-Foamed Concrete

Rubber-foamed concrete demonstrates exceptional toughness, a low elastic modulus, and significant sensitivity to density. It is necessary to parameterize the density mix of rubber-foaming concrete to meet engineering design requirements. Density-mix design methods for foaming concrete rely mainly on empirical knowledge or trial-and-error approaches. In this paper, with numerous parametric tests and regression analysis based on general principles for density-mix designs applicable to both foamed and rubber-foamed concretes, the key design parameters, such as volume correction coefficient, rubber size effect coefficient, and water-reducing agent effect coefficient, have been proposed in order to optimize their respective densities more accurately. The tests demonstrated an optimal water-to-cement ratio of 0.45, corresponding to a volume correction factor of 1.027. Incorporating rubber particles and water-reducing agents has a more significant effect on the cement-paste volume. Controlling fluidity in the 200 to 300 mm range is crucial when designing foamed concrete with varying densities. The regression equation accurately predicts the paste’s measured volume and wetting density by incorporating volume corrections, size, and water reduction effect coefficients. By employing a foam excess coefficient of 1.1 and a mass coefficient of 1.25, the dry and wet density error of foam concrete is less than 5%. A comprehensive framework for optimizing mix design in terms of density is provided for applications in foamed concrete and rubber-foamed concrete, facilitating researchers in designing mix ratios for additional novel mixture-based foamed-concrete applications.

On the Role of Radial Dispersion in the Behavior of a Cooled Fixed‐Bed Reactor: Numerical Investigation of Fischer–Tropsch Synthesis with a Cobalt‐Based Catalyst

AbstractThe impact of radial dispersion of both heat and mass on the behavior of cooled fixed‐bed reactors was explored using a two‐dimensional reactor model. This study accounted for dispersion through an effective radial thermal conductivity (λrad) and a radial dispersion coefficient of mass (Drad), with Fischer–Tropsch synthesis serving as an illustrative process example. Under moderate reaction conditions and hence still rather gentle radial temperature profiles, the effect of mass dispersion on reactor performance was found to be minimal, even if disregarded (Drad = 0), whereas dispersion of heat (λrad) always significantly impacts reactor behavior. Nevertheless, for precise thermal runaway predictions by a reactor model, incorporating mass dispersion by a realistic Drad value is essential.

Transport Instabilities of Hazardous Contaminants in a Microscale Soil Sample Under Thermal Flow of Supercritical CO2

This work reveals the transient dynamics of supercritical carbon dioxide (sCO2) under a joint heat and mass interactions with resident polycyclic aromatic hydrocarbons (PAHs) in sedimentary microporous media. A variant of Multiphase Color Fluid Lattice Boltzmann model is developed to simulate spatiotemporal evolution of sCO2 front with degradation of a 5 μm mass-film of resident PAHs. The injection conditions of sCO2 range from 305 K to 315 K, and from 8 MPa to 10 MPa, with a mass flow rate of 0.05–0.15 kg/min. It has been found in this study that the growth of clusters reveals a critical operating time to promote the solvation power of sCO2. However, the cluster of such contaminants is affected by a secondary degradation inside the pore throats of the microporous. The heat and mass coefficients are remarkably relied on the nature of the contaminants and their clustering/clogging processes inside the pores. Hence, the saturation amount of CO2 will jump from a prompt movement to a quick equilibrium state while facing the balanced phase of clustering/degradation of resident contaminants inside the microporous media.

Reference Intervals of Mass Coefficients and Absolute Weights of Mini Pigs’ Organs

Introduction. Measurement of weights and calculation of mass coefficients of the laboratory animals’ internal organs are the integral stages of toxicological research. However, the absence of the correct intra-laboratory reference intervals corresponding to the normal values established for the animal population of a research laboratory could hinder the analysis of the mass coefficient changes in the experiment. For example, the data on weights and mass coefficients of mini pigs’ organs is being an issue due to its insufficient availability in the open sources. At the same time, in the literature there is a lot of such kind of data referring to the industrial pig breeds. Due to the wide use of the mini pigs in the pre-clinical research and because in the pig species taxonomy they are considered to be a weight category representing the pigs with reduced mass of the body with similar morphology of the organs and body systems, we have set an objective to determine and calculate the reference intervals of mass coefficients of internal organs relative to the mass of the body and brain, as well as the absolute weights of mini pigs’ internal organs and compare the results with the data on mini and industrial pig breeds in the literature sources.Materials and Methods. The data on 29 males and 29 females of the Vietnamese lop-bellied mini pig breed aged 6 months and older, who used to be in control groups of the various experiments held at JSC “SPA “House of Pharmacy” (Leningrad region) in the period from January 2018 to March 2024, was used to calculate the reference intervals. The statistical analysis was peRussian Federationormed using Microsoft Excel and Reference Value Advisor v2.1 software in compliance with the CLSI guidelines. Calculation of the reference intervals for all parameters was carried out by a robust method, the compliance with the normal distribution law was determined by Anderson–Darling test, in case of abnormal distribution of data, calculation of the reference interval was carried out with the Box–Cox transformation.Results. The data on the absolute weights of organs and their coefficients relative to the body and brain masses were presented in the form of the lower and upper reference limits and confidence intervals for each of the limit. The reference intervals of masses of organs across all parameters in males and females had similar limits, the most comparable values were found for the heart and brain parameters. The calculated interval of the heart absolute weight in males was 28.3–253 g, that of the brain was 46.5–93.7 g; in females these intervals were 42.9–279 g and 55.5–81.8 g respectively. Upon comparing the obtained data with the literature sources, it was found that the majority of the absolute weights of all measured mini pigs’ organs had fitted in the limits of the reference values, whereas the masses of the lungs and liver were at the lower limit or below the calculated intervals. The values of the absolute weights of most of the organs of the industrial pig breeds were higher than that of mini pigs, which was due to the difference in the body size and mass of the studied animal breeds. When comparing the mass coefficients of organs in relation to the body mass, it was found that the coefficients of most organs of the industrial breeds and mini pigs, on the contrary, were within the calculated reference intervals or slightly exceeded them.Discussion and conclusion. The calculated reference intervals of the mass coefficients of some organs in relation to the body mass, as well as the absolute weights of the spleen in mini pigs are comparable with the data available in literature for the industrial meat pig breeds. At the same time, the data available in the literature sources on the absolute weights of organs and their mass coefficients relative to the body mass of mini pigs, in most cases, have fitted into the calculated intervals. To increase the prognostic value of the obtained reference intervals, the analysis of a larger size sample is necessary.