Accurate models and nutritional strategies for specific oxidative stress factors: Does the dose matter in swine production?

Oxidative stress has been associated with a number of physiological problems in swine,including reduced production efficiency.Recently,although there has been increased research into regulatory mechanisms and antioxidant strategies in relation to oxidative stress-induced pig production,it remains so far largely unsuccessful to develop accurate models and nutritional strategies for specific oxidative stress factors.Here,we discuss the dose and dose intensity of the causes of oxidative stress involving physiological,environmental and dietary factors,recent research models and the antioxidant strategies to provide theoretical guidance for future oxidative stress research in swine.

Economic Stress, Precariousness and Risk of High Blood Pressure: A Descriptive Survey of Life Models within Households of the Central Region of Cameroon

Context/Objective: High blood pressure (HBP) currently represents the most widespread chronic non-communicable disease in Cameroon. The increase in its prevalence in the country is the result of multiple factors including economic stress imposed by precariousness, poor living conditions, sources of anxiety, anguish, depression and other behavioral disorders. Economic stress is a globalizing concept that integrates into a purely hermeneutic approach, a particular functioning of the nervous system of an individual who faces employment problems and precarious remuneration conditions. The non-satisfaction by an individual of his basic needs due to insufficient financial means can cause him to become irritable, aggressive, and socially and symbolically isolated, thereby increasing the desire to resort to morbid life models such as excessive consumption of narcotics and other psychoactive substances often associated with high blood pressure. The fight against the emergence of BPH is a complex, multifaceted and multifactorial reality that requires taking into account economic stress. The main objective of this survey is to describe the situation of economic stress within the Cameroonian population, which imposes precariousness and life models at risk of high blood pressure. Specifically, we determined the level of household income and the sources of income. Methods: A cross-sectional survey with a descriptive aim among five hundred households in the Central Region of Cameroon was conducted. A probabilistic technique called simple randomness was used. The number of households to be surveyed was determined indirectly using the Cochrane formula. Data collection in face-to-face mode using a physical questionnaire took place from July 1 to August 31, 2023, after obtaining ethical clearance from the Regional Health Research Ethics Committee, Human from the Center and an administrative authorization for data collection. Regarding their processing, the data was grouped during processing in Excel sheets. Normality and reliability tests of the collected data were carried out. For this, the Chi-square test was used for data with a qualitative value and that of Kolmogorov-Sminorf for data with a quantitative value. Descriptive analysis was possible using R software version 3.2, SPSS version 25.0, XLSTAT 2016, PAST and EXCEL programs from Microsoft Office 2013. Results: The main results highlight economic stress, with 45.60% of households surveyed earning less than US$154 per month;55% of household heads were women in single-parent families;14% of household heads were unemployed, 22% worked in the private sector and 19% were self-employed. This general economic situation leads to precarious living conditions, thereby increasing the risk of high blood pressure among the Cameroonian population.

U-Net Models for Representing Wind Stress Anomalies over the Tropical Pacific and Their Integrations with an Intermediate Coupled Model for ENSO Studies

El Niño-Southern Oscillation(ENSO)is the strongest interannual climate mode influencing the coupled ocean-atmosphere system in the tropical Pacific,and numerous dynamical and statistical models have been developed to simulate and predict it.In some simplified coupled ocean-atmosphere models,the relationship between sea surface temperature(SST)anomalies and wind stress(τ)anomalies can be constructed by statistical methods,such as singular value decomposition(SVD).In recent years,the applications of artificial intelligence(AI)to climate modeling have shown promising prospects,and the integrations of AI-based models with dynamical models are active areas of research.This study constructs U-Net models for representing the relationship between SSTAs andτanomalies in the tropical Pacific;the UNet-derivedτmodel,denoted asτUNet,is then used to replace the original SVD-basedτmodel of an intermediate coupled model(ICM),forming a newly AI-integrated ICM,referred to as ICM-UNet.The simulation results obtained from ICM-UNet demonstrate their ability to represent the spatiotemporal variability of oceanic and atmospheric anomaly fields in the equatorial Pacific.In the ocean-only case study,theτUNet-derived wind stress anomaly fields are used to force the ocean component of the ICM,the results of which also indicate reasonable simulations of typical ENSO events.These results demonstrate the feasibility of integrating an AI-derived model with a physics-based dynamical model for ENSO modeling studies.Furthermore,the successful integration of the dynamical ocean models with the AI-based atmospheric wind model provides a novel approach to ocean-atmosphere interaction modeling studies.

Stress wave analysis of high-voltage pulse discharge rock fragmentation based on plasma channel impedance model

High-voltage pulse discharge(HVPD)rock fragmentation controls a plasma channel forming inside the rock by adjusting the electrical parameters,electrode type,etc.In this work,an HVPD rock fragmentation test platform was built and the test waveforms were measured.Considering the effects of temperature,channel expansion and electromagnetic radiation,the impedance model of the plasma channel in the rock was established.The parameters and initial values of the model were determined by an iterative computational process.The model calculation results can reasonably characterize the development of the plasma channel in the rock and estimate the shock wave characteristics.Based on the plasma channel impedance model,the temporal and spatial distribution characteristics of the radial stress and tangential stress in the rock were calculated,and the rock fragmentation effect of the HVPD was analyzed.

Numerical modeling of destress blasting for strata separation

Destress blasting(DB)implemented along the perimeter of safety pillars is a special application of destressing in coal longwall mining.The goal is to separate relatively more deformed mined areas from safety pillars,such as shaft pillars or cross-cut pillars,to reduce the transfer of high stresses to the protective pillar.This case study aims to numerically simulate selected destress blasts in the Czech part of the Upper Silesian Coal Basin and examine its impact on stress transfer to the safety pillar area.To separate the area between the protective pillar and the longwall(LW),two fans of five 93-mm blast holes(length of 93e100 m)were drilled from the gate roads into the overburden strata.Each set of blast holes was fired separately in two stages without time delay.The explosive charge(gelatin-type of explosive)of each stage is 3450 kg.The two DB stages were fired when the longwall face was approximately 158 m and 152 m away from the blast.A 3D mine-wide model is built and validated with in situ stress measured with hydrofracturing.Mining and destressing in three 5-m thick coal seams are simulated in the region.Numerical modeling of DB is successfully conducted using a rock fragmentation factor a of 0.05 and a stress reduction/dissipation factor β of 0.95.Buffering of transfer of additional stress from the mining area into the safety pillar is evaluated by comparison of yielding volume before and after DB.It is shown that yielding volume drops after DB by nearly 80%in the area of the destressing panel and near the safety shaft pillar.

Strength Model of Soda Residue Soil Considering Consolidation Stress and Structural Influence

Soda residue(SR)is a type of industrial waste produced in the soda process with the ammonia-soda method.Applying SR to backfilling solves the land occupation and environmental pollution problems in coastal areas and saves material costs for foundation engineering.The strength characteristics of soda residue soil(SRS)under different consolidation conditions are the key points to be solved in the engineering application of SRS.Triaxial compression tests were performed on the undisturbed SRS of Tianjin Port.The shear properties of SRS under different consolidation conditions were then discussed.Meanwhile,a structural strength model(SSM)based on Mohr-Coulomb theory was proposed.SSM reflects the influence of soil structure on undrained strength(Cu)and divides the Cu into the following two parts:friction strength(C_(uf))and original structural strength(C_(u0)).C_(uf)characterizes the magnitude of friction between soil particles,which is related to the consolidation stress.Meanwhile,C_(u0)represents the structural effect on soil strength,which is related to the soil deposition and consolidation processes.SSM was validated by the test data of undisturbed soils.Results reveal that the undisturbed soil generally had a certain C_(u0).Therefore,the SRS strength model was established by combining the experimental law of SRS with SSM.Error analysis shows that the SRS strength model can effectively predict the Cu of undisturbed SRS in Tianjin Port under different consolidation conditions.

Stiffness and Shear Stress Distribution of Glulam Beams in Elastic-Plastic Stage:Theory,Experiments and Numerical Modelling

Traditional methods focus on the ultimate bending moment of glulam beams and the fracture failure of materials with defects,which usually depends on empirical parameters.There is no systematic theoretical method to predict the stiffness and shear distribution of glulam beams in elastic-plastic stage,and consequently,the failure of such glulam beams cannot be predicted effectively.To address these issues,an analytical method considering material nonlinearity was proposed for glulam beams,and the calculating equations of deflection and shear stress distribution for different failure modes were established.The proposed method was verified by experiments and numerical models under the corresponding conditions.Results showed that the theoretical calculations were in good agreement with experimental and numerical results,indicating that the equations proposed in this paper were reliable and accurate for such glulam beams with wood material in the elastic-plastic stage ignoring the influence of mechanic properties in radial and tangential directions of wood.Furthermore,the experimental results reported by the previous studies indicated that the method was applicable and could be used as a theoretical reference for predicting the failure of glulam beams.

Micro sliding friction model considering periodic variation stress distribution of contact surface and experimental verification

Micro sliding phenomenon widely exists in the operation process of mechanical systems,and the micro sliding friction mechanism is always a research hotspot.In this work,based on the total reflection method,a measuring device for interface contact behavior under two-dimensional(2D)vibration is built.The stress distribution is characterized by the light intensity distribution of the contact image,and the interface contact behavior in the 2D vibration process is studied.It is found that the vibration angle of the normal direction of the contact surface and its fluctuation affect the interface friction coefficient,the tangential stiffness,and the fluctuation amplitude of the stress distribution.Then they will affect the change of friction state and energy dissipation in the process of micro sliding.Further,an improved micro sliding friction model is proposed based on the experimental analysis,with the nonlinear change of contact parameters caused by the normal contact stress distribution fluctuation taken into account.This model considers the interface tangential stiffness fluctuation,friction coefficient hysteresis,and stress distribution fluctuation,whose simulation results are consistent well with the experimental results.It is found that considering the nonlinear effect of a certain contact parameter alone may bring a greater error to the prediction of friction behavior.Only by integrating multiple contact parameters can the accuracy of friction prediction is improved.

Mechanical stress and deformation analyses of pressurized cylindrical shells based on a higher-order modeling

In this research,mechanical stress,static strain and deformation analyses of a cylindrical pressure vessel subjected to mechanical loads are presented.The kinematic relations are developed based on higherorder sinusoidal shear deformation theory.Thickness stretching formulation is accounted for more accurate analysis.The total transverse deflection is divided into bending,shear and thickness stretching parts in which the third term is responsible for change of deflection along the thickness direction.The axisymmetric formulations are derived through principle of virtual work.A parametric study is presented to investigate variation of stress and strain components along the thickness and longitudinal directions.To explore effect of thickness stretching model on the static results,a comparison between the present results with the available results of literature is presented.As an important output,effect of micro-scale parameter is studied on the static stress and strain distribution.

Triaxial creep damage characteristics of sandstone under high crustal stress and its constitutive model for engineering application

The creep characteristics of rock under high crustal stress are of important influence on the long‐term stability of deep rock engineering.To study the creep characteristics and engineering application of sandstone under high crustal stress,this study constructed nonlinear creep damage(NCD)constitutive mode based on the triaxial graded loading‒unloading creep test of sandstone in the Yuezhishan Tunnel.A numerical NCD constitutive model and a breakable lining(BL)model were developed based on FLAC3D and then applied to the stability analysis of the Yuezhishan Tunnel.Based on the creep test results of sandstone,a power function of creep rate and stress level was constructed,by which the long‐term strength was solved.The results show that the long‐term strength of the red sandstone based on the related function of the steady‐state creep rate and stress level is close to the measured stress value in engineering.The NCD model considering damage factors reflects the instantaneous and viscoelastic plasticity deformation characteristics of the red sandstone.The numerical NCD constitutive model and the BL model can reflect surrounding rock deformation characteristics and lining failure characteristics in practical engineering.The research results provide theoretical references for long‐term stability analysis of rock engineering and the deformation control of surrounding rock under high crustal stress.

Brain region-specific roles of brain-derived neurotrophic factor in social stress-induced depressive-like behavior

Brain-derived neurotrophic factor is a key factor in stress adaptation and avoidance of a social stress behavioral response.Recent studies have shown that brain-derived neurotrophic factor expression in stressed mice is brain region–specific,particularly involving the corticolimbic system,including the ventral tegmental area,nucleus accumbens,prefrontal cortex,amygdala,and hippocampus.Determining how brain-derived neurotrophic factor participates in stress processing in different brain regions will deepen our understanding of social stress psychopathology.In this review,we discuss the expression and regulation of brain-derived neurotrophic factor in stress-sensitive brain regions closely related to the pathophysiology of depression.We focused on associated molecular pathways and neural circuits,with special attention to the brain-derived neurotrophic factor–tropomyosin receptor kinase B signaling pathway and the ventral tegmental area–nucleus accumbens dopamine circuit.We determined that stress-induced alterations in brain-derived neurotrophic factor levels are likely related to the nature,severity,and duration of stress,especially in the above-mentioned brain regions of the corticolimbic system.Therefore,BDNF might be a biological indicator regulating stress-related processes in various brain regions.

Nonlinear constitutive models of rock structural plane and their applications

Structural planes play an important role in controlling the stability of rock engineering,and the influence of structural planes should be considered in the design and construction process of rock engineering.In this paper,mechanical properties,constitutive theory,and numerical application of structural plane are studied by a combination method of laboratory tests,theoretical derivation,and program development.The test results reveal the change laws of various mechanical parameters under different roughness and normal stress.At the pre-peak stage,a non-stationary model of shear stiffness is established,and threedimensional empirical prediction models for initial shear stiffness and residual stage roughness are proposed.The nonlinear constitutive models are established based on elasto-plastic mechanics,and the algorithms of the models are developed based on the return mapping algorithm.According to a large number of statistical analysis results,empirical prediction models are proposed for model parameters expressed by structural plane characteristic parameters.Finally,the discrete element method(DEM)is chosen to embed the constitutive models for practical application.The running programs of the constitutive models have been compiled into the discrete element model library.The comparison results between the proposed model and the Mohr-Coulomb slip model show that the proposed model can better describe nonlinear changes at different stages,and the predicted shear strength,peak strain and shear stiffness are closer to the test results.The research results of the paper are conducive to the accurate evaluation of structural plane in rock engineering.

Bayesian partial pooling to reduce uncertainty in overcoring rock stress estimation

The state of in situ stress is a crucial parameter in subsurface engineering,especially for critical projects like nuclear waste repository.As one of the two ISRM suggested methods,the overcoring(OC)method is widely used to estimate the full stress tensors in rocks by independent regression analysis of the data from each OC test.However,such customary independent analysis of individual OC tests,known as no pooling,is liable to yield unreliable test-specific stress estimates due to various uncertainty sources involved in the OC method.To address this problem,a practical and no-cost solution is considered by incorporating into OC data analysis additional information implied within adjacent OC tests,which are usually available in OC measurement campaigns.Hence,this paper presents a Bayesian partial pooling(hierarchical)model for combined analysis of adjacent OC tests.We performed five case studies using OC test data made at a nuclear waste repository research site of Sweden.The results demonstrate that partial pooling of adjacent OC tests indeed allows borrowing of information across adjacent tests,and yields improved stress tensor estimates with reduced uncertainties simultaneously for all individual tests than they are independently analysed as no pooling,particularly for those unreliable no pooling stress estimates.A further model comparison shows that the partial pooling model also gives better predictive performance,and thus confirms that the information borrowed across adjacent OC tests is relevant and effective.

An Innovative Finite Element Geometric Modeling of Single-Layer Multi-Bead WAAMed Part

Finite element (FE) coupled thermal-mechanical analysis is widely used to predict the deformation and residualstress of wire arc additive manufacturing (WAAM) parts. In this study, an innovative single-layermulti-bead profilegeometric modeling method through the isosceles trapezoid function is proposed to build the FE model of theWAAMprocess. Firstly, a straight-line model for overlapping beads based on the parabola function was establishedto calculate the optimal center distance. Then, the isosceles trapezoid-based profile was employed to replace theparabola profiles of the parabola-based overlapping model to establish an innovative isosceles trapezoid-basedmulti-bead overlapping geometric model. The rationality of the isosceles trapezoid-based overlapping model wasconfirmed by comparing the geometric deviation and the heat dissipation performance index of the two overlappingmodels. In addition, the FE-coupled thermal-mechanical analysis, as well as a comparative experiment of thesingle-layer eight-bead deposition process show that the simulation results of the above two models agree with theexperimental results. At the same time, the proposed isosceles trapezoid-based overlappingmodels are all straightlineprofiles, which can be divided into high-quality FE elements. It can improve the modeling efficiency andshorten the simulation calculation time. The innovative modeling method proposed in this study can provide anefficient and high-precision geometricmodelingmethod forWAAMpart FE coupled thermal-mechanical analysis.

Experimental and simulation study on shear stress-induced erythrocyte damage based on vortex oscillator

Background:Shear stress-induced erythrocyte damage,namely hemolysis,is an important problem in the development of blood-contacting medical devices such as mechanical circulatory support devices.Computational fluid dynamics simulation combined with hemolysis prediction models have been widely used to predict hemolysis.With the development of hemolysis prediction models,the new hemolysis prediction model requires more experimental data to verify.In addition,the difference of in vitro blood-shearing device also affect the accuracy of hemolysis prediction.Methods:To address these problems,a new in vitro blood-shearing device(vortex oscillator)was used to further verify the accuracy of the hemolysis prediction models,and to guide the optimal design of blood-contacting medical devices such as mechanical circulatory support devices.Firstly,the flow field information such as wall stress and velocity of the vortex oscillator under different speeds was analyzed.Secondly,different hemolysis prediction models were used to calculate hemolysis,and the predicted data was compared with the experimental data.Results and Conclusion:In this study,the flow field information inside the vortex oscillator at high rotational speeds was systematically investigated,and the prediction of hemolysis was carried out.The results showed that the predicted data of hemolysis was significantly different from the experimental data,which indicated that it was urgent to establish a standardized in vitro blood-shearing platform to provide a reference for accurate hemolysis prediction.

Simulation on Residual Stress of Shot Peening Based on a Symmetrical Cell Model

The symmetrical cell model is widely used to study the residual stress induced by shot peening. However, the correlation between the predicted residual stresses and the shot peening coverage, which is a big challenge for the researchers of the symmetrical cell model, is still not established. Based on the dynamic stresses and the residual stresses outputted from the symmetrical cell model, the residual stresses corresponding to full coverage are evalu- ated by normal distribution analysis. The predicted nodal dynamic stresses with respect to four corner points indicate that the equi-biaxial stress state exists only for the first shot impact. Along with the increase of shot number, the interactions of multiple shot impacts make the fluctuation of the nodal dynamic stresses about an almost identical value more and more obvious. The mean values and standard deviations of the residual stresses gradually tend to be stable with the increase of the number of shot peening series. The mean values at each corner point are almost the same after the third peening series, which means that an equi-biaxial stress state corresponding to the full coverage of shot peening is achieved. Therefore, the mean values of the nodal residual stresses with respect to a specific transverse cross-section below the peened surface can be used to correlate the measured data by X-ray. The predicted residual stress profile agrees with the experimental results very well under 200% peening coverage. An effective correlation method is proposed for the nodal residual stresses predicted by the symmetrical cell model and the shot peening coverage.

Numerical simulation of residual stress field in green power metallurgy compacts by modified Drucker-Prager Cap model

基于修正的Drucker-Prager Cap模型建立弹塑性本构模型,采用三维有限元模型对粉末压制过程及压制脱模后压坯的残余应力进行仿真分析。利用几个典型的力学性能测试实验确定粉末Distaloy AE的模型参数。模型通过用户子程序USDFLD实现,对粉末Distaloy AE的模压过程及脱模后压坯(d20 mm×5 mm)的残余应力进行预测分析。有限元分析结果与模压实验和X衍射实验结果基本吻合,验证了模型的有效性。结果表明,压坯的侧表面存在一层显著的残余压应力,而压坯上表面和下表面的残余应力值则很小。

A FLOW STRESS MODEL FOR AZ61 MAGNESIUM ALLOY

The flow stress behaviors of AZ61 alloy has been investigated at temperature rangefrom 523 to 673K with the strain rates of 0.001-1s^(-1). It is found that the averageactivation energy, strain rate sensitive exponent and stress exponent are different atvarious deformation conditions changing from 143.6 to 176.3kJ/mol, 0.125 to 0.167and 6 to 8 respectively. A flow stress model for AZ61 alloy is derived by analyzingthe stress data based on hot compression test. It is demonstrated that the flow stressmodel including strain hardening exponent and strain softening exponent is suitableto predicate the flow stress. The prediction of the flow stress of AZ61 alloy has shownto be good agreement with the test data. The maximum differences of the peak stressescalculated by the model and obtained by experiment is less than 8%.

Physical modeling and visualization of soil liquefaction under high confining stress

The mechanisms of seismically-induced liquefaction of granular soils underhigh confining stresses are still not fully understood. Evaluation of these mechanisms is generallybased on extrapolation of observed behavior at shallow depths. Three centrifuge model tests wereconducted at RPI's experimental facility to investigate the effects of confining stresses on thedynamic response of a deep horizontal deposit of saturated sand. Liquefaction was observed at highconfining stresses in each of the tests. A system identification procedure was used to estimate theassociated shear strain and stress time histories. These histories revealed a response marked byshear strength degradation and dilative patterns. The recorded accelerations and pore pressures wereemployed to generate visual animations of the models. These visualizations revealed a liquefactionfront traveling downward and leading to large shear strains and isolation of upper soil layers.

Protective effects of Ecklonia cava extract on the toxicity and oxidative stress induced by hair dye in in-vitro and in-vivo models

Oxidative hair dyes containingρ-phenylenediamine(PPD)are reported to induce an allergic reaction by promoting oxidative stress when absorbed through the skin.Despite the associated risk,these hair dyes remain popular owing to their convenience and sharpness of color.This makes it important to minimize the cytotoxicity and oxidative stress induced by PPD-containing hair dyes.Ecklonia cava extract has been evaluated in different studies for its protective effects against external stress in fibroblasts and keratinocytes.Our study was aimed at using in-vitro and in-vivo models to investigate the extract’s effects on cytotoxicity of and oxidative stress induced by PPD-containing hair dyes.Analysis of CIEL*a*b*Color space was first used to determine the range of E.cava extract that would not interfere with the coloring ability of the dye upon addition.Subsequently,the set ranges of E.cava extract(5% and 7%)were added to the hair dye and their toxicity assessed by evaluating the viability of fibroblasts and keratinocytes.The effects on developmental phenotypes and induction of oxidative stress by hair dye were evaluated and compared with those of hair dyes containing different contents of E.cava extract using an in-vivo zebrafish model.Our results showed that E.cava extract in hair dye could significantly decrease the cytotoxicity and levels of oxidative stress caused by hair dyes containing PPD in both in-vitro and in-vivo models.These results suggest that the addition of 7% E.cava extract to 250μg/mL hair dye does not interfere with the coloring ability of the dye while showing significant protective eff ects against the hair dye.The study proposes that the use of E.cava extract as an adduct to hair dyes containing PPD reduces the cytotoxicity and oxidative stress induced by these hair dyes.