Effect Of Local Environment Research Articles

Long-Lived Magnetization in an Atomic Spin Chain Tuned to a Diabolic Point.

Scaling magnets down to where quantum size effects become prominent triggers quantum tunneling of magnetization (QTM), profoundly influencing magnetization dynamics. Measuring magnetization switching in an Fe atomic chain under a carefully tuned transverse magnetic field, we observe a nonmonotonic variation of magnetization lifetimes around a level crossing, known as the diabolic point (DP). Near DPs, local environment effects causing QTM are efficiently suppressed, enhancing lifetimes by three orders of magnitude. Adjusting interatomic interactions further facilitates multiple DPs. Our Letter provides a deeper understanding of quantum dynamics near DPs and enhances our ability to engineer a quantum magnet.

Bimetallic Cu11Ag3 Nanotips for Ultrahigh Yield Rate of Nitrate-to-Ammonium.

Electrochemical reduction of nitrate to ammonia (NRA) offers a sustainable approach for NH3 production and NO3 - removal but suffers from low NH3 yield rate (<1.20 mmol h-1 cm-2). We present bimetallic Cu11Ag3 nanotips with tailored local environment, which achieve an ultrahigh NH3 yield rate of 2.36 mmol h-1 cm-2 at a low applied potential of -0.33 V vs. RHE, a high Faradaic efficiency (FE) of 98.8 %, and long-term operation stability at 1800 mg-N L-1 NO3 -, outperforming most of the recently reported catalysts. At a NO3 - concentration as low as 15 mg-N L-1, it still delivers a high FE of 86.9 % and an NH3 selectivity of 93.8 %. Finite-element method and density functional theory calculations reveal that the Cu11Ag3 exhibits reduced adsorption energy barrier of *N intermediates, favorable water dissociation for *H generation and high energy barrier for H2 formation, while its tip-enhanced enrichment promoting NO3 - accumulation.

Exploring the Local Environment Effect on Properties of all-Trans-Retinal by Two-Dimensional Correlation Resonance Raman Spectroscopy

Exploring the Local Environment Effect on Properties of all-Trans-Retinal by Two-Dimensional Correlation Resonance Raman Spectroscopy

Kids’ Environment and Health Cohort

This presentation discusses Kids’ Environment and Health Cohort (KEHC), a bespoke Administrative Data Research UK (ADR UK) funded linkage project. KEHC will be a comprehensive and yearly updated dataset for children born in England from 2006 onwards, integrating health, education, pregnancy, and environmental data. This integrates data from different administrative systems including the Office for National Statistics, the National Health Service, and the Department for Education as well as open environmental data. This presentation will outline the deterministic and probabilistic linkage methods utilised and the quality assurance undertaken through clerical review and bias analysis. Additionally, we will delve into the challenges encountered in the process of data ingest, linkage, and delivery due to the diverse origins and purposes of the collected data, as well as temporal disparities. In navigating the intricacies of multiple linkages, we will discuss our unique methods, including plans to use an indexing first approach. The first cohort of approximately 10 million children has been created to form the spine and further linkages to the 2011 and 2021 UK census data have been concluded. Linkages between address histories and open environmental data is ongoing. Linkage results have been promising, with high match rate and excellent quality. KEHC is a powerful example of how integrated data can be used for research for the public good. KEHC will provide a unique opportunity for academic researchers investigating the longitudinal effects of local environments on children’s health and educational outcomes and will become one of ADR UK’s flagship Research Ready Datasets.

Influence of local cation order on the electronic structure and optical properties of cation-disordered semiconductor AgBiS2

Abstract Site disorder exists in some practical semiconductors and can significantly impact their intrinsic properties both beneficially and detrimentally. However, the uncertain local order and structure poses a challenge for both experimental and theoretical research. Especially, it hinders the investigation of the effects of the diverse local atomic environments resulting from the site disorder. In this study, we employ the special quasi-random structure method to perform first-principles research on the connection between local site disorder and electronic/optical properties, using the cation-disordered AgBiS2 (rock salt phase) as an example. We predict that cation-disordered AgBiS2 has a bandgap ranging from 0.6 to 0.8 eV without spin-orbit coupling and that spin-orbit coupling reduces this by approximately 0.3 eV. We observe the effects of local structural features in the disordered lattice, such as the one-dimensional chain-like aggregation of cations that results in the formation of doping energy bands near the band edges, the formation and broadening of band-tail states, and the disturbance in the local electrostatic potential, which significantly reduces the bandgap and stability. The influence of these ordered features on the optical properties is confined to alterations in the bandgap and does not markedly affect the joint density of states or optical absorption. Our study provides a research roadmap for exploring the electronic structure of site-disordered semiconductor materials, suggests that the ordered chain-like aggregation of cations is an effective way to regulate the bandgap of AgBiS2, and provides insight into how variations in local order associated with processing can affect properties.

Nature's Catalyst: Investigating the Mechanisms behind Nitrogenase's N2rr Activity

Electrochemical nitrogen reduction reaction (eNRR), one of the most studied problems in catalysis, has the potential to replace the century-old Haber-Bosch process for ammonia synthesis. However, a low-cost, highly selective and efficient catalyst for eNRR is yet to be discovered. Nitrogenase, a naturally occurring biocatalyst responsible for nitrogen conversion to ammonia under ambient conditions, is the most efficient catalyst for eNRR. The Iron-Molybdenum cofactor (FeMo-co) in the enzyme is identified as the catalytic part with bridging irons being active sites. Despite decades of work the exact mechanism of its operation and various intermediates along the pathway are still debated. We revisit eNRR on FeMo-co and decipher the key mechanisms at play.Most studies on FeMo-co tend to ignore the magnetic nature of transition metals (TMs) in the cofactor. Proper treatment of these TMs (Fe and Mo) is necessary to pinpoint the intermediates and potential limiting step along the eNRR pathway. We start with an iterative optimization of the Hubbard U parameter to capture the correct magnetic structure of the cofactor. We also explore the effect of local chemical environment including, H-coverage and various ligands attached to the cofactor, on its activity and selectivity. The potential limiting step is found to be sensitive to the magnetic orientation of the TMs in the cofactor and it is thus imperative to provide the U correction to capture the true bottleneck of eNRR. The cofactor also shows an affinity towards a medium H-coverage under eNRR operating conditions. These findings provide a comprehensive and elaborate view of nitrogen reduction on FeMo-co and insights from this study paves the path towards designing heterogeneous counterparts to the catalyst.Acknowledgments:This work was supported by the U.S. Department of Energy, via Grant DE-FOA-0002676 to the SUNCAT Center for Interface Science and Catalysis.

Effect of B and Hf doping on vacancy defects in AlCrMoNbZr high entropy alloy: A first principles study

The AlCrMoNbZr high entropy alloy (HEA) has potential applications as a high-performance cladding coating material. Here, we report the results about the vacancy defects in AlCrMoNbZr HEA using first-principle calculations. We have explored the variations in bulk and vacancy defect properties due to different local chemical environments in AlCrMoNbZr HEA with and without B/Hf doping, using both supercell and special quasi-random structures (SQS) techniques. Vacancy formation energy (VFE) is analyzed in accordance with the statistical distribution across three systems. The VFE exhibits a broad range of values and is characterized by a normal distribution. It is also significantly influenced by the type of doping atoms and the type of vacancy. Specifically, B doping substantially reduces the vacancy formation energy, thereby facilitating the formation of vacancies. Furthermore, the doping of B and Hf exerts a considerable impact on the formation of Zr vacancies (Zr_Vac) and Mo vacancies (Mo_Vac). In addition, Al vacancies (Al_Vac) are most readily formed in the AlCrMoNbZr HEA, while Mo vacancies (Mo_Vac) are most easily formed following the introduction of B and Hf dopants. The VFE in AlCrMoNbZr HEA with and without Hf dopant increases with the increase of the number of Cr and Mo atoms in the local chemical environment, and decreases with the increase of the number of Zr atoms. In conclusion, B doping promotes the formation of vacancy, which is not conducive to the improvement of initial irradiation resistance performance. Fortunately, one can infer from the results of the effect of local chemical environment on VFE that it is rewarding in improving the initial irradiation resistance by increasing the occurrence of Mo–Mo and Zr–Zr arrangement in AlCrMoNbZr HEA.

Constructing unsaturated coordination Co−M (M = P, S, Se, Te) bonds modified metallic Co for efficient alkaline hydrogen evolution

Alkaline hydrogen evolution reaction (HER) provides a promising approach for producing green hydrogen, but designing high-efficiency transition metal nanocatalysts is rather challenging. Herein, unsaturated coordination Co−M (M = P, S, Se, Te) bonds modified metallic Co are designed on Ni foam (M-Co/NF) through a facile electrodeposition strategy. The constructed Co−M bonds not only alter the local coordination condition and electron structure, but also provide an electron transfer channel, and significantly enhance the intrinsic activities. Consequently, the P-Co/NF displays an ultralow overpotential of 23 mV at 10 mA cm−2 with excellent stability. X-ray absorption spectroscopy verifies the formation of extremely unsaturated coordination Co−P bonds, which adjusts the charge redistribution. Density functional theory calculations prove the unsaturated coordination Co−P bonds can optimize the adsorption of H2O and H adsorption. This work provides novel insight into the effects of local coordination environment on activity and the rational design of efficient transition metal nanocatalysts.

Revealing ringed galaxies in group environments

Aims. We explore galaxies with ringed structures inhabiting poor and rich groups with the aim of assessing the effects of local density environments on ringed galaxy properties. Methods. We identified galaxies with inner, outer, nuclear, inner+outer (inner and outer rings combined), and partial rings that reside in groups by cross-correlating a sample of ringed galaxies with a group catalog obtained from Sloan Digital Sky Survey (SDSS). The resulting sample was divided based on group richness, with groups having 3 ≤ Nrich ≤ 10 members classified as poor, while groups having 11 ≤ Nrich ≤ 50 were classified as rich. To quantify the effects of rings and the role of local density environment on galaxy properties, we constructed a suitable control sample for each catalog of ringed galaxies in poor and rich groups, consisting of non-ringed galaxies with similar values for the redshift, magnitude, morphology, group masses, and environmental density distributions as those of ringed ones. We explored the occurrence of ringed galaxies in poor and rich groups and analyzed several galaxy properties, such as star formation activity, stellar populations, and colors, with respect to the corresponding comparison samples. Results. We obtained a sample of 637 ringed galaxies residing in groups. We found that about 76% of these galaxies inhabit poor groups, whereas only about 24% are present in rich groups. Inner rings are prevalent in both rich and poor groups, while nuclear rings are the least common in both groups. Regarding the control sample, about 81% galaxies are found in poor groups and about 19% in rich ones. We find that the percentages of ringed galaxies with bar structures are similar, regardless of whether the group is rich or poor. In addition, ringed galaxies inhabiting groups display a reduction in their star formation activity and aged stellar populations, compared to non-ringed ones in the corresponding control samples. However, the star formation rate is higher for nuclear rings in poor groups than for other types. This disparity may stem from the environmental influence on the internal processes of galaxies, either enhancing or diminishing star formation. Ringed galaxies also show an excess of red colors and tend to populate the green valley and the red sequence of color-magnitude and color-color diagrams, with a surplus of galaxies in the red sequence, while non-ringed galaxies are found in the green valley and the blue region. These trends are more significant in galaxies with ringed structures residing in rich groups. Our findings provide valuable insights into the relationship between ringed structures and their surrounding environments, paving the way for further explorations in this area of study.

Unraveling the effect of local dopant environment on NiO6 octahedron perturbation for enhanced oxygen evolution activity

The oxygen evolution reaction (OER) performance in cation-doped materials often exhibits a volcano-like relationship with dopant concentration. However, the influence of dopant content with its associated local environment on the electronic states of electrocatalysts remains unclear. Herein, V is incorporated into Ni(OH)2 to study the underlying mechanism. It is revealed that evenly distributed V can effectively perturb the NiO6 octahedron, leading to strong eg * band broadening and more electronic states around the Fermi level. This phenomenon significantly enhances the electron transfer from electrocatalysts to external circuits. Conversely, the aggregation of V at higher dopant concentration exerts weaker influence on perturbing the NiO6 octahedron. As a result of balance between V doping and aggregation, Ni0.95V0.05OOH, with the strongest NiO6 octahedron distortion, effectuating a remarkably low overpotential of 258 mV at 10 mA cm−2. Furthermore, such a structure-activity relationship is also extended to Fe-doped Ni(OH)2, affirming the universality of the proposed mechanism.

Chemodiversity of riverine dissolved organic matter: Effects of local environments and watershed characteristics

Riverine dissolved organic matter (DOM) is crucial to global carbon cycling and aquatic ecosystems. However, the geographical patterns and environmental drivers of DOM chemodiversity remain elusive especially in the waters and sediments of continental rivers. Here, we systematically analyzed DOM molecular diversity and composition in surface waters and sediments across 97 broadly distributed rivers using data from the Worldwide Hydrobiogeochemistry Observation Network for Dynamic River Systems (WHONDRS) consortium. We further examined the associations of molecular richness and composition with geographical, climatic, physicochemical variables, as well as the watershed characteristics. We found that molecular richness significantly decreased toward higher latitudes, but only in sediments (r = -0.24, p < 0.001). The environmental variables like precipitation and non-purgeable organic carbon showed strong associations with DOM molecular richness and composition. Interestingly, we identified that less-documented factors like watershed characteristics were also related to DOM molecular richness and composition. For instance, DOM molecular richness was positively correlated with the soil sand fraction for waters, while with the percentage of forest for sediments. Importantly, the effects of watershed characteristics on DOM molecular richness and composition were generally stronger in waters than sediments. This phenomenon was further supported by the fact that 11 out of 13 watershed characteristics (e.g., the percentages of impervious area and cropland) showed more positive than negative correlations with molecular abundance especially in waters. As the percentage of forest increased, there was a continuous accumulation of the compounds with higher molecular weight, aromaticity, and degree of unsaturation. In contrast, human activities accumulated the compounds with lower molecular weight and oxygenation, and higher bioavailability. Our findings imply that it may be possible to use a small set of broadly available data types to predict DOM molecular richness and composition across diverse river systems. Elucidation of mechanisms underlying these relationships will provide further enhancements to such predictions, especially when extrapolating to unsampled systems.

Disentangling pH Effects on Electrocatalytic Reactions

Electrocatalysis is the key discipline to enable breakthrough advances in electrochemical energy technology and in the conversion of CO2 into renewable fuels and value-added chemicals. However, crucial electrocatalytic reactions are afflicted with sluggish kinetics and low selectivity. The electrolyte plays a vital role for the course of an electrocatalytic reactions and, in this realm, understanding the impact of the local pH is crucial for electrocatalyst development and design. The high interest in this topic in the research community is well-reflected in the recent literature, cf., e.g., Science 2022, 375 (6579). Explanations of pH effects remain controversial, even for the simplest model reactions, i.e., the hydrogen evolution/oxidation reaction and the formic acid oxidation reaction (FAOR), since a complex interplay of multiple interacting factors, centered around the local reaction environment and kinetic effects, must be disentangled. Theory and modeling are indispensable in this context. We will present a hierarchical framework that self-consistently couples the impacts of the microkinetics, mass transport and double layer charging effects (going beyond Frumkin corrections).1,2 In our modelling work, we will assess the role of distinct phenomena and parameters at play in a step-by-step fashion. The developed framework will be demonstrated for the FAOR and other electrocatalytic reactions.

The Effects of Local Environment on a Probe Signal Absorption and Resonance Fluorescence for Quantum Emitters in Transparent Media

The Effects of Local Environment on a Probe Signal Absorption and Resonance Fluorescence for Quantum Emitters in Transparent Media

Density Functional Theory Study of Local Environment Effects on Oxygen Vacancy Properties in Magnetite

Density Functional Theory Study of Local Environment Effects on Oxygen Vacancy Properties in Magnetite

On the Effects of Local Environment on Active Galactic Nucleus (AGN) in the Horizon Run 5 Simulation

We use the Horizon Run 5 cosmological simulation to study the effect of galaxy intrinsic properties and the local environment on active galactic nuclei (AGNs) characterized by their threshold of the accretion rate. We select galaxies in the stellar mass range in the snapshot at redshift z = 0.625. Among various intrinsic properties, we find that the star formation rate of the host galaxy is most correlated to the AGN activity. To quantify the environment, we use background galaxy number density (large-scale environment) and distance and morphological type of the nearest neighbors (small-scale environment), and study their relative effects on the AGN properties. We find that, compared to the background density, the nearest neighbor environment is the dominant quantity determining the bolometric luminosity, star formation rate, and kinematic properties of AGNs and better dictates the gas mass of the host galaxy. We show that the cold gas content in the host galaxies is crucial in triggering AGN activity. However, when the nearest neighbor environment effects start to act at the neighbor distance of less than about half the virial radius of the neighbor, the neighbor environmental effects are the most dominant factor for quasar activity.

Elastic modelling of lattice distortions in concentrated random alloys

Lattice distortions, i.e. small atomic displacements away from the average lattice, are linked to a number of functional and mechanical properties of concentrated metallic alloys, particularly their yield strength. Here we develop an elastic model of lattice distortions where every atom is modeled as an Eshelby inclusion in a homogeneous elastic matrix. Local environment effects are included by considering fluctuating anisotropic eigenstrain tensors associated to the inclusions. The model is tested on several concentrated alloys, face-centered cubic (FCC) AlMg and FeNiCr alloys, as well as a fictitious body-centered cubic (BCC) binary alloy to study systematically and independently the effects of a size and an elastic modulus mismatch between the constituents. The elastic model predicts lattice distortions well when the size and elastic modulus mismatches are typically less than 5% and 25%, respectively. Interestingly, we find that when the size mismatch is small, as in FeNiCr alloys, the lattice distortion is dominated by the fluctuations of the dilatational eigenstrains rather than their average value as often assumed in elastic models of concentrated alloys. Moreover, models usually assume homogeneous elastic constants, while the limit obtained here of 25% is often exceeded in concentrated alloys, particularly with a BCC structure.

Novel AMoO4:Eu3+ (A = Ca and Ba) optical thermometer: Investigation of effect of local ionic coordination environment on optical performance and temperature measurement sensitivity

A range of Eu3+-doped AMoO4 (A = Ca and Ba) phosphors were successfully synthetized, and their crystal structures, optical performance, and temperature measurement sensitivities were investigated in detail. Peak doping concentration of CaMoO4:Eu3+ phosphor was 0.18, while peak doping concentration of BaMoO4:Eu3+ phosphor may be greater than 0.18. Then, temperature-dependent photoluminescence emission spectra of representative CaMoO4:0.09Eu3+ and BaMoO4:0.03Eu3+ phosphors were recorded. CaMoO4:0.09Eu3+ phosphor exhibited abnormal thermal quenching, which was attributed to defects caused by heterovalent substitution of ions and increase in the temperature, and good thermal stability. Finally, the possibility of using both phosphors as optical thermometers was discussed, which exhibited good temperature sensitivity. However, CaMoO4:0.09Eu3+ phosphor exhibited two peak absolute (Sa, 1.28 %K−1 and 1.39 %K−1) and relative sensitivities (Sr, 1.21 %K−1 and 1.20 %K−1). In addition, variation trend of Sr value with temperature was considerably peculiar. Two optimum Sa and Sr values were attributed to abnormal thermal quenching of CaMoO4:0.09Eu3+ phosphor. Peak Sa and Sr values of BaMoO4:0.03Eu3+ phosphor was 12.39 %K−1 and 0.89 %K−1, respectively. In addition, Sa of AMoO4:Eu3+ phosphor was negatively related to Eu3+ central asymmetry, while peak Sr value was more inclined to appropriate ionic central asymmetry.

The effects of local environment towards yield and selectivity on photocatalytic CO2 reduction catalyzed by metal-organic framework

The CO2 photoconversion is sensitive to the local reaction environment, of which activity and selectivity can be regulated by the change of reaction systems. This paper focuses on investigating the photocatalytic CO2 reduction behaviors of MOFs with the involvement of water under different reaction modes, including gas-solid and liquid-solid systems. The CO2 photoreduction in a liquid-solid system shows high performance in generating HCOOH with the selectivity of 100%. In contrast, the gas-solid system referring to the synergistic interaction of MOFs and H2O vapor benefits to the formation of gas-phase products, such as CO and CH4. The possible mechanisms of photocatalytic CO2 reaction in two modes were investigated by in-situ Fourier-transform infrared spectroscopy, which indicates that the distinction in reaction consequence may result from the difference in CO2 chemisorbed modes and the proton provision. The choice of reaction system plays an important role in the achievement of high efficiency and selectivity for photocatalytic CO2 reduction, which is of great practical value in real-world applications.

Effect of local chemical environment on the point defects in AlNbTiZr refractory high entropy alloys

The effect of local chemical environment (i.e., type and content of atom neighboring to defects) on the point defect properties has been thoroughly investigated in bcc AlNbTiZr refractory high-entropy alloys (HEAs). It has been shown that the randomness of local chemical environments in AlNbTiZr HEAs leads to a wide distribution of vacancy and interstitial formation energy rather than to definitive values. One interesting aside here is that the number of Al and Nb atoms locating at the first-nearest neighbor (1nn) of vacancy drives the evolution of vacancy formation energy (VFE) in AlNbTiZr system, as vacancies preferred Al-rich and Nb-poor environments. What another worth noticing is that the most stable interstitial defects are in the form of dumbbells. What's more, the Al-Al dumbbell is the easiest interstitial defect while the Zr-Zr dumbbell is the least according to the lowest formation energy and electronic characteristics. Along with the results of vacancies preferred Al-rich environments, Al in AlNbTiZr can stabilize the single vacancy and inhibit its migration and diffusion to form large-size vacancy clusters. Therefore, the initial irradiation resistance can be improved by adjusting the concentration and distribution of Al in AlNbTiZr. One can infer from the results obtained present that it is beneficial in improving the irradiation resistance by controlling different processing experimentally methods to increase the occurrence of Al-Al arrangement in AlNbTiZr high-entropy alloys.

Sponge diversification in marine lakes: Implications for phylogeography and population genomic studies on sponges.

The relative influence of geography, currents, and environment on gene flow within sessile marine species remains an open question. Detecting subtle genetic differentiation at small scales is challenging in benthic populations due to large effective population sizes, general lack of resolution in genetic markers, and because barriers to dispersal often remain elusive. Marine lakes can circumvent confounding factors by providing discrete and replicated ecosystems. Using high-resolution double digest restriction-site-associated DNA sequencing (4826 Single Nucleotide Polymorphisms, SNPs), we genotyped populations of the sponge Suberites diversicolor (n = 125) to test the relative importance of spatial scales (1-1400 km), local environmental conditions, and permeability of seascape barriers in shaping population genomic structure. With the SNP dataset, we show strong intralineage population structure, even at scales <10 km (average F ST = 0.63), which was not detected previously using single markers. Most variation was explained by differentiation between populations (AMOVA: 48.8%) with signatures of population size declines and bottlenecks per lake. Although the populations were strongly structured, we did not detect significant effects of geographic distance, local environments, or degree of connection to the sea on population structure, suggesting mechanisms such as founder events with subsequent priority effects may be at play. We show that the inclusion of morphologically cryptic lineages that can be detected with the COI marker can reduce the obtained SNP set by around 90%. Future work on sponge genomics should confirm that only one lineage is included. Our results call for a reassessment of poorly dispersing benthic organisms that were previously assumed to be highly connected based on low-resolution markers.