Segregation Effects Research Articles

Prolonged Phase Segregation of Mixed-Halide Perovskite Nanocrystals in the Dark.

A critical issue hindering the potential applications of semiconductor mixed-halide perovskites is the phase segregation effect, wherein localized regions enriched with one type of halide anions would be formed upon continuous photogeneration of the excited-state charge carriers. These unexpected phases are capable of remixing again in the dark under the entropic driving force, the process of which is now being exclusively studied after the mixed-halide perovskites have arrived at the final stage of complete phase segregation. Here, we show that after the removal of laser excitation from a solid film of the mixed-halide perovskite nanocrystals (NCs) with partial phase segregation, the iodide- and bromide-rich regions can continuously grow in the dark for a prolonged time period of several minutes. We propose that this dark phase segregation is sustained by the local electric fields from the surface-trapped charge carriers, whose slow dissipation out of the mixed-halide perovskite NCs causes a delayed occurrence of the reversal phase remixing process.

The Effect of Solute Elements Co-Segregation on Grain Boundary Energy and the Mechanical Properties of Aluminum by First-Principles Calculation

The segregation of solute atoms at grain boundary (GB) has an important effect on the GB characteristics and the properties of materials. The study of multielement co-segregation in GBs is still in progress and deserves further research at the atomic scale. In this work, first-principles calculations were carried out to investigate the effect of Mg and Cu co-segregation on the energetic and mechanical properties of the Al Σ5(210) GB. The segregation tendency of Mg at the GB in the presence of Cu is characterized, indicating a preference for substitutional segregation far away from Cu atoms. Cu segregation can facilitate the segregation of Mg due to their mutual attractive energy. The GB energy results show that Mg and Cu co-segregation significantly decreases GB energy and thus enhances the stability of the Al Σ5(210) GB. First-principles tensile test calculations indicate that Cu effectively counteracts the weakening effect of Mg segregation in the GB, particularly with the high concentration of Cu segregation. The phenomenon of Cu compensating the strength of the GB is attributed to an increase of charge density and the formation of newly formed Cu-Al bonds. Conversely, Mg segregation weakens the strengthening effect of Cu on the GB, but it can increase the strength of the GB when high concentrations of Cu atoms are present in the GB. The ICOHP and Bader charge analysis exhibits that the strengthening effect of Mg is attributed to charge transfer with surrounding Al and Cu, which enhances the Cu-Al and Al-Al bonds. The results provide a further understanding of the interplay between co-segregated elements and its influence on the energetic and mechanical properties of grain boundary.

Gender occupational segregation: a new approach to quantifying the effect of educational segregation

ABSTRACT This article analyses the impact of educational segregation on the gender gap in the probability of working in a gendered or gender-balanced occupation, which is our measure of occupational segregation. Specifically, our methodology allows quantifying two different effects of education on this gap: one due to girls and boys choosing different educational options (presorting), and the other due to men and women with the same education entering the same or different occupations (postsorting). Using a sample of university graduates from Spain, a country with a highly segregated labour market, we conclude that the gender composition of education and occupation are strongly related. However, the greater presence of women in female-dominated jobs is not only due to them choosing female-dominated degrees, but also due to many women from gender-balanced, and even some from male-dominated programmes, working in female-dominated occupations. Thus, reducing educational segregation does not seem to be enough to fight against occupational segregation. It is also necessary to guarantee that men and women enjoy the same opportunities in the labour market, removing discrimination practices, and to ensure that both, workers and employers, do not make decisions based on gender role expectations or stereotypes.

Effect of chemical segregation on accuracy of local lattice distortions determination by pair distribution functions

Local lattice distortion (LLD) is a salient feature of bcc-structured refractory high-entropy alloys (RHEAs), closely associated with their mechanical properties. To quantify the extent of LLDs in RHEAs, the pair distribution function (PDF) analysis has been identified as a promising approach. However, the commonly observed chemical segregation within these alloys introduces challenges in accurately determining LLDs. In this study, the effect of chemical segregation on LLD quantification was investigated through fitting simulated two-phase composite PDFs, representing segregated microstructures, with a single-phase model and evaluating the errors to assess the accuracy and reliability of small-box analysis in this context. The results show that the errors introduced by chemical segregation increase with increasing lattice parameter difference, and the fitting quality gradually deteriorates to a point where it no longer adequately describes the data. We found that the lattice parameter difference should be below 1% for precise and reliable LLD measurements in bcc-structured RHEAs. Additionally, we observed that while the scattering length variation due to segregation does affect LLD quantification, its effect is comparatively minor.

Immigrants' clusters and unequal access to healthcare treatments

We focus on caesarean sections (C-sections) to examine access to appropriate medical care for immigrants in the Italian tax-funded universal National Health Service. We use a detailed micro-dataset to analyse whether non-native women receive different treatments compared to natives and whether there are differences between groups of non-natives defined by citizenship. For identification, we control for hospital fixed effects and maternal characteristics, and we compare the different groups by exploiting the clustering of non-natives of different nationalities in different urban areas. We find no significant differences between natives and non-natives in terms of C-sections and inappropriate C-sections. However, we do find significant differences between different groups of immigrants. In addition, we find that linguistic and socio-cultural distances are significant drivers of inequalities among non-native women. As language, habits, traditions, and beliefs can affect communication between the woman and the medical staff in many ways, we interpret our findings in terms of the ability to process and understand information between the two parties. In support of this interpretation, we find evidence of a “segregation effect”: women linguistically and socio-culturally more distant from Italy experience the greatest difficulties in accessing appropriate care when living in urban areas characterized by the presence of large immigrant communities of the same nationality. Moreover, we find that the role of linguistic and socio-cultural barriers is stronger for first-time mothers and women with non-native partners.

Progress in elemental segregation and solute drag effect at the austenite/ferrite interface

Progress in elemental segregation and solute drag effect at the austenite/ferrite interface

A matter of measurement? Segregation and all-cause mortality in Sweden’s three metropolitan regions

Abstract Background Residential segregation can be operationalized and measured in many ways, along distinct dimensions. There are multiple mechanisms through which segregation and health mutually affect each other. Consequently, contextual health effects of segregation may vary depending on how segregation is measured. Methods We used longitudinal Swedish register data to compare associations between local measures of residential segregation (migrant density, migrant isolation, and the mutual information index) and all-cause mortality among the adult migrant and native-born populations in Sweden’s three largest metropolitan regions between 2004-2016. Results Among migrants, modest positive mortality gradients were observed across measures of migrant density and isolation, where a higher level of segregation was associated with higher risks of all-cause mortality (Q5 RR ranged from 1.08-1.20 across cities and measures). However, these effects were largely attenuated by individual-level socioeconomic factors, and reversed when further controlling for neighborhood economic deprivation (Q5 RR ranged from 0.74-0.87). Among the native-born, a positive gradient for mortality was found (Q5 RR ranged from 1.31-1.45), although this was reduced when accounting for neighborhood deprivation (Q5 RR ranged from 1.01 -1.11). For both migrants and the native-born, the mutual information index showed no clear association with mortality, although a mortality advantage is observed for migrants in the most segregated areas after individual and neighborhood level adjustments (Q5 RR ranged from 0.73-0.86). Conclusions Our findings show that the manner in which residential segregation is conceptualized and operationalized alters associations with health. However, individual and other contextual level confounders are important determinants which influences the patterns. Much of the negative health effects of residential segregation can be perceived through the lack of economic opportunities. Key messages • Associations between segregation and all-cause mortality depends on how segregation is conceptualized and measured. • The mortality disadvantage observed in local areas with high migrant density may be attributed to the lack of economic opportunities in the neighborhood.

Thermally-induced diffusion and structural phase transitions in Pt/Mn and Pt/Mn/Pt thin films

We demonstrate the possibility of diffusion formation of the chemically ordered L1 0-MnPt phase through the vacuum annealing of Pt(24 nm)/Mn(20 nm) and Pt(12 nm)/Mn(20 nm)/Pt(12 nm) layered stacks at 400 °C for 30 min. For the bi-layered stack annealed at 400 °C, the effect of Pt atoms segregation at the film/substrate interface was detected, which remained after annealing even at higher temperatures (500 °C and 600 °C) and prevented the whole homogenization of the chemical composition through the film depth. By contrast, for the tri-layered stack annealed at 400 °C, the presence of the additional Pt bottom layer enabled to change the rate and mechanism of reactive diffusion, leading to homogeneous distribution of components and enhanced crystallinity of the ordered L1 0-MnPt phase compared to the bi-layered sample. An explanation of the obtained experimental data is provided based on the fundamentals of mass transfer theory and its quantitative parameters (e.g. activation energy and diffusion coefficients).

Probing degradation at solid-state battery interfaces using machine-learning interatomic potential

Solid-state batteries featuring fast ion-conducting solid electrolytes are promising next-generation energy storage technologies, yet challenges remain for practical deployment due to electro-chemo-mechanical instabilities at solid-solid interfaces. These interfaces, which include homogeneous/internal interfaces such as grain boundaries (GBs) and heterogeneous/external interfaces between solid-electrolyte and electrode materials, can impede Li-ion transport, deteriorate performance, and eventually lead to cell failure. Here we leverage large-scale molecular simulations, enabled by validated machine-learning interatomic potentials, to directly probe the onset of interfacial degradation at the garnet Li7La3Zr2O12 (LLZO) solid-electrolyte/LiCoO2 (LCO) cathode interface. By surveying different interfacial geometries and compositions, it is found that Li-deficient interfaces can lead to severe interfacial disordering with cation mixing and Co interdiffusion from LCO into LLZO. By contrast, Li-sufficient interfaces are less disordered, although elemental segregation with local ordering is observed. As a consequence of Co interdiffusion, Co-rich regions are formed at the GBs of LLZO due to cation segregation and trapping effects. This behavior is independent of the GB tilting axis, degree of disorder at the GBs, and Co concentration, which implies Co clustering at GBs is a general phenomenon in polycrystalline LLZO and can dictate its overall transport and mechanical properties. Our findings elucidate the underlying fundamental mechanisms that give rise to experimentally observed physicochemical properties and provide guidelines for interface design that can mitigate interfacial degradation and improve cycling performance.

A Statistical, Photometric, and SED Analysis to Characterize the BSS Populations in Old Open Cluster: Berkeley 39

ABSTRACT We present a statistical, photometric, and spectral energy distribution (SED) analysis to characterize the blue straggler stars (BSSs) populations in the Galactic old open cluster Berkeley 39. Berkeley 39 is a 6.16 Gyr old open cluster located at a distance of 3.99 Kpc.Gaia DR3 astrometry data have been used to estimate the membership probabilities using ensemble-based unsupervised machine learning techniques. We identified 21 BSS candidates on the colour–magnitude diagram, with 19 of them being detected in the Swift/UVOT UVW2 filter. We analysed the radial surface density profile and examined the cluster dynamical states and mass segregation effect. The SEDs of 19 BSSs are constructed using multiwavelength data covering UV to IR wavelengths. A single-component SED is fitted successfully for 14 BSS candidates. We discovered hot companions in five BSS candidates. These hot companions have temperatures of approximately 14 000 to 23 000 K, radii ranging from 0.04 to 0.13 R$_{\odot }$, and luminosities ranging from 0.16 to 2.91 L$_{\odot }$. Among these, three are most likely extremely low-mass white dwarfs (WDs) with masses around 0.17 to 0.18 M$_{\odot }$, and two are low-mass WDs with masses around 0.18 to 0.39 M$_{\odot }$. This confirms that they are post-mass transfer (Case A or Case B) systems. We also investigated the variable characteristics of BSSs by analysing their light curves using data from TESS. Our analysis confirms that two BSSs identified as eclipsing binaries in Gaia DR3 are indeed eclipsing binaries. Additionally, one of the two eclipsing binary BSSs shows evidence of having hot companions, as indicated by the multiwavelength SEDs.

Effects of microstructure and phosphorus segregation on tensile properties of friction stir welded high phosphorus weathering steel

Defect-free sound joints of high-phosphorus (0.094 wt%) weathering steel (SPA-H) were successfully fabricated using friction stir welding (FSW). This study examines the microstructural evolution and mechanical properties of joints produced at different FSW parameters. Tensile tests of the joints revealed that fractures occurred in the base metal (BM) region, indicating almost 100 % welding efficiency. Furthermore, the stir zones (SZ) demonstrated a marked improvement in tensile properties. Particularly, at the rotation rate of 80 rpm and axial load of 45 kN condition (below A1), the microstructure featured ultra-fine ferrite and cementite, resulting in high hardness (270 HV) and tensile strength (704 MPa) in steel with just 0.08 wt% C, while maintaining nearly 80 % of the total elongation of BM. However, the SZ at 80 rpm exhibited an unusual decrease in local elongation despite the fine ferrite grain size and cementite presence. Electron probe microanalysis (EPMA) and nano-hardness revealed pronounced phosphorus segregation in the ferrite region and significant localized hardness disparities induced by the segregation behavior. The strain concentration at the interfaces between these regions during the tensile process leads to crack initiation and rapid propagation. The negative factor caused by the phosphorus segregation accelerates the failure of the specimen during the necking stage and ultimately shows decreased local elongation.

Growth of single crystalline GeSn alloy epilayer on Gd2O3/Si (111) engineered insulating substrate using RF sputtering and solid phase epitaxy

The article showcases a low-cost, low-temperature deposition andHVMtechnique to develop single crystalline GeSn alloy epilayers on Gd2O3/Si (111) substrate. First, GeSn alloy amorphous layer is deposited on the insulating substrates using an Radio Frequency (RF) sputtering apparatus. Subsequently, an inductively coupled plasma-assisted chemical vapor deposition (ICP-CVD) process is used to deposit a SiO2 capping layer to protect against Sn out-diffusion during heat treatment. The samples are then subjected to solid phase epitaxy (SPE) at 450 °C, 550 °C, and 650 °C. Sample processed for SPE at 450 °C has weak crystallinity and only shows Type-A stacking. Those processed for SPE at 550 °C and 650 °C, on the other hand, have revealed formation of the single-crystalline GeSn alloy epilayer with Type-A and Type-B stacking. However, SPE at 650 °C revealed tin out-diffusion and segregation effects. This work is significant for enabling the preparation of high-Sn-content GeSn alloy epilayers on insulating Gd2O3/Si (111) substrates, as it requires the initial deposition of a GeSn amorphous alloy epilayer using RF sputtering. This advancement promises benefits which includes advantages such as lower operating voltage, reduced leakage current, and minimized parasitic and short-channel effects, making it ideal for advancing RF technology.

Ride-hailing technology mitigates effects of driver racial discrimination, but effects of residential segregation persist

We assess racial disparities in the service quality of app-based ride-hailing services, like Uber and Lyft, by simulating their operations in the city of Chicago using empirical data. To generate driver cancellation rate disparities consistent with controlled experiments (up to twice as large for Black riders as for White riders), we estimate that more than 3% of drivers discriminate by race. We find that the capabilities of ride-hailing technology to rapidly rematch after a cancellation and prioritize long-waiting customers heavily mitigates the effects of driver discrimination on rider wait times, reducing average discrimination-induced disparities to less than 1 min-an order of magnitude less than traditional taxis. However, our results suggest that even in the absence of direct driver discrimination, Black riders in Chicago wait about 50% longer, on average, than White riders because of historically informed geographic residential patterns. We estimate that if Black riders in the city had the same wait times as White riders, the collective travel time saved would be worth $4.2 million to $7.0 million per year.

Martensite size and morphology influence on strain distribution and micro-damage evolution in dual-phase steels; comparing segregation-neutralised and banded grades

A change in strain partitioning and microscale failure mechanisms in dual-phase (DP) steel was found when both the morphology and distribution of martensite were altered compared to a banded DP steel grade benchmarked against a specific commercial DP grade. To achieve a DP microstructure with equiaxed and well-dispersed martensite, the concept of segregation neutralisation was utilised, where the ratio of Mn to Si elements was decreased (from 7.4 to 0.3) to neutralise the effect of Mn segregation on generating the banded martensite. A combination of micromechanical modelling simulations and in-situ notch tensile testing (within an SEM) was employed to compare the micro strain field and void formation rate between the segregation-neutralised and the benchmark grades. The benchmark grade showed extensive void coalescence along the direction of shear bands in the tensile sample after the average tensile strain of 30%. In contrast, no void coalescence was observed in the segregation-neutralised DP steel even at the average tensile strain of 80% just before failure. As a result, post-uniform elongation in the segregation-neutralised grade increased to 63.3%, compared to 30.1% in the benchmark grade.

Abstract A040: Effects of food environment, income inequality, and racial segregation on obesity- related cancer mortality

Abstract BACKGROUND: Rural areas experience 7-12% higher risk of obesity-related cancer mortality compared to their urban counterparts. Complex interactions between social and structural factors in rural areas, combined with limited access to healthy foods and lower income, warrant further study to understand drivers of this disparity. Methods: County-level rates of age-adjusted obesity-related cancer mortality per 100,000 (2009-2020 were obtained from the Centers for Disease Control and Prevention’s Wide-Ranging ONline Data for Epidemiologic Research database. Based on data from the Food Environment Atlas, we calculated food swamp using the modified Retail Food Environment Index (mRFEI) as the ratio of fast-food restaurants and convenience stores to grocery and specialized food stores, supercenters, and farmers markets. Food swamp scores were then divided into quartiles. Next, we used Global G and local Gi statistics to identify the presence of spatial autocorrelation in food swamp and subsequently calculated a spatial moving average (SMA) across counties. Measures of economic segregation, racial segregation, and racialized economic segregation were calculated using the Index of Concentration at the Extremes (ICE) using population and demographic estimates from the 2005- 2009 American Community Survey. Larger values reflect concentrated extremes of disadvantage. Poisson regression was used to assess the impact of food swamp, urban-rural status, economic segregation, racial segregation, and racialized economic segregation on rates of obesity-related cancer mortality. Results: Among the 3014 counties included, median food swamp score was 3.6 (interquartile range=2.6-4.9), and counties in the 2nd, 3rd, and 4th quartiles for food swamp had 2%, 4%, and 6% higher rates (respectively) of obesity-related cancer mortality than those in the 1st quartile. Incidence rate ratios for the association of food swamp quartile with obesity-related cancer mortality were 1-3% smaller after control for food swamp SMA and for racialized economic Urban-rural differences in obesity-related cancer mortality varied with all ICE measures. Rural counties had 5% higher rates of obesity-related cancer mortality (IRR=1.05, 95%CI=1.04-1.06), even after controlling for food swamp and food swamp SMA, but there was no longer an association after controlling for economic segregation (IRR=0.99, 95%CI=0.98-1.00). Rural counties had 5% higher rates of obesity-related cancer mortality (IRR=1.05, 95%CI=1.04-1.07) when controlling for racial segregation and 2% higher rates when controlling for racialized economic segregation (IRR=1.02, 95%CI=1.01-1.03). Thus, we stratified our models by urban-rural status and found that each ICE measure had larger effects on obesity-related cancer mortality in rural counties than in urban. CONCLUSION: While food swamp is important, the socioeconomic environment of a county has a larger impact on obesity- related cancer mortality. Individuals may have access to healthy food stores, but whether they can afford the healthy food is more important. Citation Format: Elizabeth S. Davis, Sara Myers, Jeffrey A. Franks, Michael R. Poulson, Julie R. Palmer, Kelly M. Kenzik. Effects of food environment, income inequality, and racial segregation on obesity- related cancer mortality [abstract]. In: Proceedings of the 17th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2024 Sep 21-24; Los Angeles, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2024;33(9 Suppl):Abstract nr A040.

Abstract A051: Association of residential economic and racial segregation with pediatric cancer survival

Abstract Purpose: Studies have linked residential segregation to inferior outcomes in adult-onset cancers. However, its association with pediatric cancer outcomes remains poorly understood. Racial and ethnic disparities in pediatric cancer outcomes are well-documented, and residential segregation may contribute, at least in part, to these disparities. This study examines the association between residential economic and racial segregation and survival in a statewide, population-based cohort of pediatric oncology patients. Methods: We studied a cohort of children diagnosed with their initial cancer between 2009 and 2016 at age 21 or younger, who were treated at Children’s Healthcare of Atlanta. The Index of Concentration at the Extremes (ICE) was mapped to the ZIP Codes of patient residence at diagnosis to measure economic and racial segregation. ICE was calculated by the difference between the number of non-Hispanic White people with >80th percentile household income and non-Hispanic Black people with <20th percentile household income, divided by the total number of people in the ZIP Code. ICE tertiles were categorized from the most deprived/segregated (tertile 1) to the most privileged/least segregated (tertile 3). We used the Cox proportional hazards model to estimate 5-, 3-, and 1-year overall survival from diagnosis by ICE tertiles, or by ICE tertiles and patient race. All models adjusted for sociodemographic (age at diagnosis, sex, health insurance, rurality) and clinical factors (cancer type, year of diagnosis). Results: Of our cohort (N=2,790), a higher proportion of non-Hispanic Black patients (50.8% vs. 13.4%) and publicly insured patients (62.3% vs. 30.8%) was found in tertile 1 compared to tertile 3. Patients living in tertile 1 consistently exhibited a higher risk of death at 5 years (adjusted hazard ratio [aHR]=1.32, 95% confidence interval [CI]=1.03-1.69, p=0.026), 3 years (aHR=1.35, 95% CI=1.04-1.75, p=0.026), and 1 year (aHR=1.38, 95% CI=0.94-2.03, p=0.099) post diagnosis, compared to those in tertile 3. In addition, compared to non-Hispanic White patients living in ICE tertiles 2-3 (more privileged areas), no survival difference was found among non-Hispanic Black children living in the same tertiles, while non- Hispanic Black children living in ICE tertile 1 had a significantly higher risk of death at 5 years (aHR=1.46, 95% CI=1.11-1.90, p=0.006), 3 years (aHR=1.56, 95% CI=1.17-2.07, p=0.002), and 1 year (aHR=1.65, 95% CI=1.11-2.45, p=0.014) post diagnosis. Conclusion: Our data indicate that residence in more racially segregated and economically deprived neighborhoods is associated with poorer overall survival among children diagnosed with cancer. Further research should explore the mediation and moderation effects of residential segregation on racial disparities in pediatric cancer-specific survival. Citation Format: Xu Ji, Lu Zhang, Xuesong Han, Heeju Sohn, Kinsey Meggett, Rebecca Williamson Lewis, Sharon M Castellino. Association of residential economic and racial segregation with pediatric cancer survival [abstract]. In: Proceedings of the 17th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2024 Sep 21-24; Los Angeles, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2024;33(9 Suppl):Abstract nr A051.

Large-scale brain connectivity changes following the administration of lysergic acid diethylamide, d-amphetamine, and 3,4-methylenedioxyamphetamine.

Psychedelics have recently attracted significant attention for their potential to mitigate symptoms associated with various psychiatric disorders. However, the precise neurobiological mechanisms responsible for these effects remain incompletely understood. A valuable approach to gaining insights into the specific mechanisms of action involves comparing psychedelics with substances that have partially overlapping neurophysiological effects, i.e., modulating the same neurotransmitter systems. Imaging data were obtained from the clinical trial NCT03019822, which explored the acute effects of lysergic acid diethylamide (LSD), d-amphetamine, and 3,4-methylenedioxymethamphetamine (MDMA) in 28 healthy volunteers. The clinical trial employed a double-blind, placebo-controlled, crossover design. Herein, various resting-state connectivity measures were examined, including within-network connectivity (integrity), between-network connectivity (segregation), seed-based connectivity of resting-state networks, and global connectivity. Differences between placebo and the active conditions were assessed using repeated-measures ANOVA, followed by post-hoc pairwise t-tests. Changes in voxel-wise seed-based connectivity were correlated with serotonin 2 A receptor density maps. Compared to placebo, all substances reduced integrity in several networks, indicating both common and unique effects. While LSD uniquely reduced integrity in the default-mode network (DMN), the amphetamines, in contrast to our expectations, reduced integrity in more networks than LSD. However, LSD exhibited more pronounced segregation effects, characterized solely by decreases, in contrast to the amphetamines, which also induced increases. Across all substances, seed-based connectivity mostly increased between networks, with LSD demonstrating more pronounced effects than both amphetamines. Finally, while all substances decreased global connectivity in visual areas, compared to placebo, LSD specifically increased global connectivity in the basal ganglia and thalamus. These findings advance our understanding of the distinctive neurobiological effects of psychedelics, prompting further exploration of their therapeutic potential.

Altering tensile and crack initiation behavior in a metastable β titanium alloy via designing grain size and precipitates

Microstructure can play a vital role in defining mechanical properties of metallic materials. To elucidate this correlation in the case of Ti–15Mo–3Nb–3Al-0.2Si (TB8) alloy, herein, we designed various microstructures via heat treatment exploring the effects of grain size, precipitates and segregation on crack initiation behavior during tensile tests in metastable β-Ti alloy. After solution treatment at 830 °C, the TB8 alloy with equiaxed β grain displayed a good fracture elongation of 30.2 ± 0.63%. The adiabatic shearing band and β→α phase transformation were activated to increase the compatible deformation capability during tensile testing; however, the phase transformation caused the stress concentration in the boundary, resulting in crack initiation. For the samples prepared using solution and low aging at 440 °C, large grain, elements segregation at grain boundary and incomplete precipitates induced a slight reduction in ultimate tensile strength and elongation. After solution and aging at 520 °C, the short-rod or/and lamellar α phase precipitated in β grain effectively enhancing ultimate tensile strength (1398.71 ± 15.6 MPa). The increased boundaries provided the interface or precipitation strengthening effect, but high-density dislocations were also accumulated at the β/α interface, causing unstable deformation and crack initiation. These findings advance our understanding of the correlation between microstructure and crack initiation, and provide a basis for designing and customizing the mechanical properties of metastable β-Ti alloy.

Effect of transition metal segregation on strength of Cu Σ5 [001](210) symmetrical tilt grain boundary: Insight from DFT calculation

The performance of metals in service is significantly influenced by grain boundaries(GBs). This study utilizes density functional theory and employs first-principles calculations to systematically look into the effects of 27 transition metal elements on copper's Σ5 [001](210) grain boundaries. Additionally, first-principles tensile methods are employed to quantitatively assess how alloying elements influence grain boundary strength. The fundamental reason behind the alloy atoms' influence on grain boundary(GB) strength is elucidated from the perspective of charge density variations. This research contributes to a deeper understanding of the behavior of transition metal elements at the Σ5[001](210) grain boundary on an electronic scale, consequently providing a theoretical framework for enhancing the strength of copper.

Legacy effects of housing segregation on urban mammal communities in Washington, D.C., USA

Racist public policies in the US, like redlining, segregated many communities of color to resource poor and impoverished areas, and codified how resources were distributed to communities based on race. Redlining, a historic discriminatory housing policy used to value city neighborhoods by race has codified segregation in cities today. Research has shown how the practice of redlining has shaped the economic and social fabric of modern U.S. cities, but only recently have researchers explored how these discriminatory policies have influenced the ecology in cities. Here, we used camera trap data collected in the Washington, D.C. region to assess if historic redlining impacts medium-sized mammal diversity in present day. We found no significant difference in species richness or community composition among historic neighborhood classifications. We did find that urbanization alone had a significant negative correlation with the persistence of raccoon and occupancy of Virginia opossum, but these variables did not vary significantly between housing classifications for any species. Our study adds to a growing body of knowledge on how historic land use decisions affect biodiversity in cities, allowing managers to better understand where conservation and habitat improvements should be made to reduce nature inequalities.