Atomic-scale insights into microscopic mechanisms of grain boundary segregation in Al−Cu alloys

This study aims to clarify the mechanisms for the grain boundary(GB)segregation through investigating the absorption of excess solute atoms at GBs in Al−Cu alloys by using the hybrid molecular dynamics/Monte Carlo simulations.Two segregation mechanisms,substitutional and interstitial mechanisms,are observed.The intergranular defects,including dislocations,steps and vacancies,and the intervals in structural units are conductive to the prevalence of interstitial mechanism.And substitutional mechanism is favored by the highly ordered twin GBs.Furthermore,the two mechanisms affect the GB structure differently.It is quantified that interstitial mechanism is less destructive to GB structure than substitutional one,and often leads to a segregation level being up to about 6 times higher than the latter.These findings contribute to atomic scale insights into the microscopic mechanisms about how solute atoms are absorbed by GB structures,and clarify the correlation among intergranular structures,segregation mechanisms and kinetics.

SOCIAL POLARIZATION AND SEGREGATION IN BEIJING

The biggest change in Beijing during the last decade has been in its social structure. This transition is changing the existing situation of social "equality", and leads to polarization both in individual communities and in society as a whole. As a result, social variations and conflicting interest are growing, and some new social groups are emerging. In this paper we seek to exPlore a new urban Phenomenon in post-1984 Beijing: social polarization and segregation. At first, we will discuss some.elements explaining social polarization. The elements and the processes can be traced back to two main aspects of the economic reforms, namely the internal reforms unleashing a huge rural exodus and the open door policy. Special attention will be paid to the new lower end of the social ladder, which is made up largely by rural migrantsthat make up the so-called floating population. Finally we will explore how these social changes translate into urban segregation, with some consideration for future developments.

Effect of granular shape on radial segregation in a two-dimensional drum

Granular segregation is widely observed in nature and industry.Most research has focused on segregation caused by differences in the size and density of spherical grains.However,due to the fact that grains typically have different shapes,the focus is shifting towards shape segregation.In this study,experiments are conducted by mixing cubic and spherical grains.The results indicate that spherical grains gather at the center and cubic grains are distributed around them,and the degree of segregation is low.Through experiments,a structured analysis of local regions is conducted to explain the inability to form stable segregation patterns with obviously different geometric shapes.Further,through simulations,the reasons for the central and peripheral distributions are explained by comparing velocities and the number of collisions of the grains in the flow layer.

Effect of casting process on the inner-wall band segregation of high-strength antisulfur pipes

Controlling inner-wall band segregation is one of the difficulties in the production of high-strength antisulfur pipes.Comparative tests were carried out on different casting processes(superheat,mold electromagnetic stirring,end electromagnetic stirring,casting speed and soft reduction)for the smelting of high-strength antisulfur pipes.The microstructures of continuous-casting billets and hot-rolled or tempered pipes were analyzed using a metallographic microscope and scanning electron microscope.The mechanism and evolution law regarding the inner-wall band segregation of high-strength antisulfur pipes were studied,and the influence of different casting processes was explored.

Segregation of Mg-6Gd alloy under natural convection:From macro solute distribution to micro dendrite growth

Segregation is a serious defect in alloy ingots which severely deteriorates materials performance.The segregation defect in Mg-6Gd alloy is studied by coupling macro thermal-solutal-convection transport and micro dendrite growth.The macroscopic fluid dynamics and mass transfer equations are resolved to forecast the segregation behavior under conditions of continuous temperature variation during the solidification process.The numerical model is validated by testing double-diffusive natural convection in a closed square cavity.A phase field model is then applied to simulate the micro dendrite growth,using macro undercooling and liquid flow velocity as boundary conditions.Results show that the multiscale segregation behavior,including macro solute distribution and micro dendritic morphology,is strongly dependent on the temperature condition and the liquid convection,which provides guidance for reducing and eliminating the segregation defect.

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.

Towards designing high mechanical performance low-alloyed wrought magnesium alloys via grain boundary segregation strategy:A review

Low-alloyed magnesium(Mg)alloys have emerged as one of the most promising candidates for lightweight materials.However,their further application potential has been hampered by limitations such as low strength,poor plasticity at room temperature,and unsatisfactory formability.To address these challenges,grain refinement and grain structure control have been identified as crucial factors to achieving high performance in low-alloyed Mg alloys.An effective way for regulating grain structure is through grain boundary(GB)segregation.This review presents a comprehensive summary of the distribution criteria of segregated atoms and the effects of solute segregation on grain size and growth in Mg alloys.The analysis encompasses both single element segregation and multi-element co-segregation behavior,considering coherent interfaces and incoherent interfaces.Furthermore,we introduce the high mechanical performance low-alloyed wrought Mg alloys that utilize GB segregation and analyze the potential impact mechanisms through which GB segregation influences materials properties.Drawing upon these studies,we propose strategies for the design of high mechanical performance Mg alloys with desirable properties,including high strength,excellent ductility,and good formability,achieved through the implementation of GB segregation.The findings of this review contribute to advancing the understanding of grain boundary engineering in Mg alloys and provide valuable insights for future alloy design and optimization.

Solute atom segregation to I1 stacking fault and its bounding partial dislocations in a Mg–Bi alloy

Stacking faults(SFs)and the interaction between solute atoms and SFs in a Mg–Bi alloy are investigated using aberration-corrected scanning transmission electron microscopy.It is found that abundant I_(1)SFs are generated after cold rolling and are mainly distributed inside{1012}twins.After aging treatment,the formation of single-layer and three-layer Bi atom segregation in the vicinity of I_(1)fault are clearly observed.Bi segregation also occurs at the 1/6<2203>bounding Frank partial dislocation cores.The segregation behaviors in I_(1)fault and Frank dislocations are discussed and rationalized using first-principles calculations.

The occurrence,inheritance,and segregation of complex genomic structural variation in synthetic Brassica napus

"Synthetic"allopolyploids recreated by interspecific hybridization play an important role in providing novel genomic variation for crop improvement.Such synthetic allopolyploids often undergo rapid genomic structural variation(SV).However,how such SV arises,is inherited and fixed,and how it affects important traits,has rarely been comprehensively and quantitively studied in advanced generation synthetic lines.A better understanding of these processes will aid breeders in knowing how to best utilize synthetic allopolyploids in breeding programs.Here,we analyzed three genetic mapping populations(735 DH lines)derived from crosses between advanced synthetic and conventional Brassica napus(rapeseed)lines,using whole-genome sequencing to determine genome composition.We observed high tolerance of large structural variants,particularly toward the telomeres,and preferential selection for balanced homoeologous exchanges(duplication/deletion events between the A and C genomes resulting in retention of gene/chromosome dosage between homoeologous chromosome pairs),including stable events involving whole chromosomes("pseudoeuploidy").Given the experimental design(all three populations shared a common parent),we were able to observe that parental SV was regularly inherited,showed genetic hitchhiking effects on segregation,and was one of the major factors inducing adjacent novel and larger SV.Surprisingly,novel SV occurred at low frequencies with no significant impacts on observed fertility and yield-related traits in the advanced generation synthetic lines.However,incorporating genome-wide SV in linkage mapping explained significantly more genetic variance for traits.Our results provide a framework for detecting and understanding the occurrence and inheritance of genomic SV in breeding programs,and support the use of synthetic parents as an important source of novel trait variation.

No basalt accumulation and segregation atop the 660-km discontinuity beneath the Sea of Okhotsk

Recent seismic evidence shows that basalt accumulation is widespread in the mantle transition zone(MTZ),yet its ubiquity or sporadic nature remains uncertain.To investigate this phenomenon further,we characterized the velocity structure across the 660-km discontinuity that separates the upper mantle from the lower mantle beneath the Sea of Okhotsk by modeling the waveform of the S660P phase,a downgoing S wave converting into a P wave at the 660-km interface.These waves were excited by two regional>410-km-deep events and were recorded by stations in central Asia.Our findings showed no need to introduce velocity anomalies at the base of the MTZ to explain the S660P waveforms because the IASP91 model adequately reproduced the waveforms.This finding indicates that the basalt accumulation has not affected the bottom of the MTZ in the study area.Instead,this discontinuity is primarily controlled by temperature or water content variations,or both.Thus,we argue that the basalt accumulation at the base of the MTZ is sporadic,not ubiquitous,reflecting its heterogeneous distribution.

Realizing impressive superplasticity in a low-alloyed Mg-Zn-Ca-Al-Mn alloy:The roles of grain boundary segregation and denseβ-Mn particles

Achieving impressive superplasticity is an important strategy to manufacture Mg alloy products with complex shapes.In the present study,we report that an excellent superplastic deformation with elongation larger than 500%can be achieved at 623 K and 1.0×10^(−3)s^(−1)in a Mg-1.51Zn-0.59Ca-0.59Al-0.70Mn(wt.%,ZXAM2111)alloy fabricated by equal-channel angular pressing.The superplastic deformation is mainly carried by grain boundary sliding(GBS),accompanied by a grain size growth from∼3.0μm to∼6.0μm after deformation.Before deformation,the ZXAM2111 alloy is mainly characterized by a strong co-segregation of Zn and Ca atoms at grain boundaries and uniformly distributedβ-Mn particles.With deformation proceeding,theβ-Mn particles further dynamically precipitate along grain boundaries that parallel the tensile axis,leading to improved resistance to grain coarsening.Although the enhanced stabilizing effects decrease the strain rate sensitivity value,the resulting impressive microstructure stability provides a cornerstone of the active operation of GBS,facilitating the achievement of superplastic deformation.The present work could provide insight into developing low-alloyed Mg alloys with high microstructure thermal stability to achieve superplasticity.

First-principles study on the interfacial bonding strength and segregation at Mg/MgZn_(2)matrix interface

To understand the interface characteristics between the precipitateβ2and the Mg matrix,and thus guide the development of new Mg-Zn alloys,we investigated the atomic interface structure,work of adhesion(Wad),and interfacial energy(γ)of Mg(0001)/β2’(MgZn_(2))(0001)interface,as well as the effect of segregation behavior of the introduced transition metal atoms(3d,4d and 5d)on interfacial bonding strength.The calculated works of adhesion and interfacial energies dementated that the Zn2-terminated MT+HCP configuration is the most stable structure for all considered models.Take the Zn2-MT+HCP interface as the research object,estimated segregated energies(Eseg)reveal that added transition metal atoms prefer to segregate at Mg-I and Mg-II sites.The predicted Wad and charge density difference results reveal that the segregation of alloying additives employed may all strengthen Mg(0001)/MgZn_(2)(0001)interface,with the enhancement effect of Os,Re,Tc,W,and Ru at the Mg-II site being the most pronounced.

Photoinduced phase segregation in wide-bandgap mixed-halide perovskite solar cells

Wide-bandgap(WB)mixed-halide perovskite solar cells(PSCs)play a crucial role in perovskite-based tandem solar cells(TSCs),enabling them to exceed the Shockley-Queisser limits of single-junction solar cells.Nonetheless,the lack of stability in WB perovskite films due to photoinduced phase segregation undermines the stability of WB PSCs and their TSCs,thus impeding the commercialization of perovskite-based TSCs.Many efforts have been made to suppress photoinduced phase segregation in WB perovskite films and significant progresses have been obtained.In this review,we elaborate the mechanisms behind photoinduced phase segregation and its impact on the photovoltaic performance and stability of devices.The importance role of advanced characterization techniques in confirming the photoinduced phase segregation are comprehensively summarized.Beyond that,the effective strategies to alleviate photoinduced phase segregation in WB mixed halide PSCs are systematically assessed.Finally,the prospects for developing highly efficient and stable WB PSCs in tandem application are also presented.

Correlation between anxiety, depression, and social stress in young patients with thoracolumbar spine fractures

BACKGROUND Traumatic injuries,such as falling,car accidents,and crushing mostly cause spinal fractures in young and middle-aged people,and>50%of them are thoracolumbar fractures.This kind of fracture is easily combined with serious injuries to peripheral nerves and soft tissues,which causes paralysis of the lower limbs if there is no timely rehabilitation treatment.Young patients with thoracolumbar fractures find it difficult to recover after the operation,and they are prone to depression,low self-esteem,and other negative emotions.AIM To investigate the association between anxiety,depression,and social stress in young patients with thoracolumbar spine fractures and the effect on rehabilitation outcomes.METHODS This study retrospectively analyzed 100 patients admitted to the orthopedic department of Honghui Hospital,Xi’an Jiaotong University who underwent thoracolumbar spine fracture surgery from January 2022 to June 2023.The general data of the patients were assessed with the Hamilton anxiety scale(HAMA),Hamilton depression scale(HAMD),life events scale,and social support rating scale(SSRS)to identify the correlation between anxiety,depression scores,and social stress and social support.The Japanese Orthopedic Association(JOA)was utilized to evaluate the rehabilitation outcomes of the patients and to analyze the effects of anxiety and depression scores on rehabilitation.RESULTS According to the scores of HAMD and HAMA in all patients,the prevalence of depression in patients was 39%(39/100),and the prevalence of anxiety was 49%(49/100).Patients were categorized into non-depression(n=61)and depression(n=39),non-anxiety(n=51),and anxiety(n=49)groups.Statistically significant differences in gender,occupation,Pittsburgh Sleep Quality Index(PSQI)score,and monthly family income were observed between the non-depression and depression groups(P<0.05).A significant difference in occupation and PSQI score was found between the non-anxiety and anxiety groups.Both depression(r=0.207,P=0.038)and anxiety scores(r=0.473,P<0.001)were significantly and positively correlated with negative life events.The difference in negative life event scores as well as SSRS total and item scores was statist-ically significant between patients in the non-depression and depression groups(P<0.05).The difference between the non-anxiety and anxiety groups was statistically significant(P<0.05)in the negative life event scores as well as the total SSRS scores.Additionally,JOA scores were significantly lower in both anxious and depressed patients.CONCLUSION Young patients with thoracolumbar fractures are prone to anxiety and depression.Patients’anxiety and depression are closely associated with social pressure,which reduces the life pressure of young patients with thoracolumbar fractures,enhances social support,and improves the psychology of anxiety and depression.,which affects patients’recovery.

Mediating role of health literacy in the relationship between social isolation and psychological distress among pre-frail older adults

BACKGROUND Frailty has become a significant public health issue.The recent increase in the number of frail older adults has led to increased attention being paid to psycho-logical care services in communities.The social isolation of pre-frail older adults can impact their psychological distress.AIM To explore the mediating effect of health literacy between social isolation and psychological distress among communitydwelling older adults with pre-frailty.METHODS This descriptive cross-sectional study was conducted with 254 pre-frail older individuals aged 60 years and over.Social isolation,health literacy,and psycholo-gical distress were comprehensively measured using the Lubben Social Network Scale-6,12-item Short-Form Health Literacy Questionnaire,and the Kessler Psy-chological Distress Scale-10.Data were evaluated using the SPSS 27.0 package program and the PROCESS macro tool.Descriptive statistical analyses,correlation analyses,and bootstrap mediation tests were used to assess associations between the variables.RESULTS The results showed that social isolation had an effect on health literacy among pre-frail older adults(β=0.240,P<0.001),social isolation impact on psycho-logical distress pre-frail older adults(β=-0.415,P<0.001);health literacy was identified effect on psychological distress among pre-frail older persons(β=-0.307,P<0.001).Health literacy partially mediated the relationship between social isolation and psychological distress among community-dwelling older adults with pre-frailty,with a mediation effect of-0.074,accounting for 17.83%of the total effect.

Social function scores and influencing factors in patients with residual depressive symptoms

BACKGROUND At present,the influencing factors of social function in patients with residual depressive symptoms are still unclear.Residual depressive symptoms are highly harmful,leading to low mood in patients,affecting work and interpersonal communication,increasing the risk of recurrence,and adding to the burden on families.Studying the influencing factors of their social function is of great significance.AIM To explore the social function score and its influencing factors in patients with residual depressive symptoms.METHODS This observational study surveyed patients with residual depressive symptoms(case group)and healthy patients undergoing physical examinations(control group).Participants were admitted between January 2022 and December 2023.Social functioning was assessed using the Sheehan Disability Scale(SDS),and scores were compared between groups.Factors influencing SDS scores in patients with residual depressive symptoms were analyzed by applying multiple linear regression while using the receiver operating characteristic curve,and these RESULTS The SDS scores of the 158 patients with depressive symptoms were 11.48±3.26.Compared with the control group,the SDS scores and all items in the case group were higher.SDS scores were higher in patients with relapse,discon-tinuous medication,drug therapy alone,severe somatic symptoms,obvious residual symptoms,and anxiety scores≥8.Disease history,medication compliance,therapy method,and residual symptoms correlated positively with SDS scores(r=0.354,0.414,0.602,and 0.456,respectively).Independent influencing factors included disease history,medication compliance,therapy method,somatic symptoms,residual symptoms,and anxiety scores(P<0.05).The areas under the curve for predicting social functional impairment using these factors were 0.713,0.559,0.684,0.729,0.668,and 0.628,respectively,with sensitivities of 79.2%,61.8%,76.8%,81.7%,63.6%,and 65.5%and specificities of 83.3%,87.5%,82.6%,83.3%,86.7%,and 92.1%,respectively.CONCLUSION The social function scores of patients with residual symptoms of depression are high.They are affected by disease history,medication compliance,therapy method,degree of somatic symptoms,residual symptoms,and anxiety.

The Philosophy of Social Segregation in Israel＇s Democratic Schools

Democratic private schools in Israel are a part of the neo-liberal discourse. They champion the dialogic philosophy associated with its most prominent advocates--Martin Buber, Emmanuel Levinas---together with Paulo Freire＇s critical pedagogy, the humanistic psychology propounded by Carl Rogers, Nel Noddings＇s pedagogy of care and concern, and even Gadamer＇s integrative hermeneutic perspective. Democratic schools form one of the greatest challenges to State education and most vocal and active critique of the focus conservative education places on exams and achievement. This article describes the dual discourse connected to the schools. The first is the inner dialogical, which is devoted to student freedom and progress, the child being placed at the center. The second is the exterior discourse, which represents the school as a place of counter-education that provides personal and group development and comprises a site of liberty and choice. The schools in Israel are described as test case and indicating the existence of a sophisticated form of deception via the use of alluring terminology. The democratic private schools should be recognized for what they really are--agents of commodification that undermine democracy rather than enhance it.

Addressing social function in the treatment of depression:A call for holistic approaches

This article discusses the importance of addressing social functioning impairment in patients with residual depressive symptoms,as highlighted in the study by Liao et al.The authors showed that social dysfunction persists in many patients despite symptom remission.This observation calls for a shift in depression treatment strategies,with an emphasis on integrating social functioning as a key treatment goal.This article suggests targeted interventions that focus on both symptomatic relief and the restoration of social function.

Perceived Social Support and Symptoms of Depression and Anxiety among Chinese Adolescents:A Moderated Chain Mediation Model

Background:Although previous studies indicate that perceived social support might be associated with adolescent psychological problems,the specific mechanism has not been thoroughly discussed.Based on theoretical and empirical research on problematic Internet use(PIU)and sleep quality,this study explored whether they play a mediating role between perceived social support and symptoms of depression and anxiety among adolescents.Furthermore,we investigated whether these relationships varied by place of residence.Methods:A sample of 2115 Chinese adolescents was included,and analyzed data related to perceived social support,PIU,sleep quality,symptoms of depression and anxiety,and sociodemographic variables.Correlation analysis,mediation,and moderation analysis were mainly used.Results:Perceived social support was negatively correlated with depressive symptoms(r=−0.22,p<0.001)and anxiety symptoms(r=−0.20,p<0.001)among adolescents.PIU and sleep quality played a chain mediating role in the relationship between perceived social support and symptoms of depression and anxiety in adolescents.Additionally,the place of residence moderated the relationships between perceived social support and PIU and symptoms of depression and anxiety.Perceived social support was a significant negative predictor of PIU and symptoms of depression and anxiety among adolescents in urban areas but not in rural areas.Conclusion:The findings suggest that low levels of perceived social support may lead to more PIU and poorer sleep quality,which may further increase the risk of symptoms of depression and anxiety in adolescents,especially in urban areas.

Correlation between psychological,family social support,and home nursing quality for an implanted venous access port

BACKGROUND Cancer patients with an implanted venous access port(IVAP)often manage their care at home during chemotherapy intervals,including maintaining the device,monitoring complications,and following medication instructions.Home care ensures continued support after discharge.However,due to factors such as age,gender,culture,psychological status,and family support,the quality of home care varies significantly.Understanding these factors can help provide targeted guidance to improve the care of cancer patients.AIM To explore IVAP chemotherapy on home care quality and its association with mental health and family support for cancer patients.METHODS This investigative study was based on a medical records system.It investigated the relationship between psychological status,family support,and home care quality in 180 patients with cancer undergoing IVAP chemotherapy.Psychological status was assessed using the State Anxiety Inventory(S-AI);family support was assessed using the Perceived Social Support Scale(PSSS),and home care quality was evaluated using the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire(EORTC QLQ-C30).Pearson’s correlation and Structural Equation Modeling were used to analyze the interplay between these factors.RESULTS The average S-AI score was 47.52±14.47,PSSS was 52.48±12.64,and EORTC QLQ-C30 was 70.09±17.32.A substantial inverse relationship was observed between the EORTC QLQ-C30 and S-AI scores(r=-0.712).A significant positive correlation was found between the EORTC QLQ-C30 and the PSSS,with a correlation coefficient of(r=0.744).The multiple linear regression analysis indicated that family social support,psychological status,and average monthly family income were the main factors influencing the variation in the quality of home care,explaining 71.9%of the variation.The Structural Equation Modeling results indicated that psychological status acted as a partial mediator in the association between family social support and home care quality of life,explaining 32.78%of the mediation effect.CONCLUSION Psychological status and family social support positively impacted cancer patients’home care quality,with psychology partially mediating this effect.