Proximity Effect Research Articles

Heterogeneous Porous Synergistic Photocatalysts for Organic Transformations.

Recent interest has surged in using heterogeneous carriers to boost synergistic photocatalysis for organic transformations. Heterogeneous catalysts not only facilitate synergistic enhancement of distinct catalytic centers compared to their homogeneous counterparts, but also allow for the easy recovery and reuse of catalysts. This mini-review summarizes recent advancements in developing heterogeneous carriers, including metal-organic frameworks, covalent-organic frameworks, porous organic polymers, and others, for synergistic catalytic reactions. The advantages of porous materials in heterogeneous catalysis originate from their ability to provide a high surface area, facilitate enhanced mass transport, offer a tunable chemical structure, ensure the stability of active species, and enable easy recovery and reuse of catalysts. Both photosensitizers and catalysts can be intricately incorporated into suitable porous carriers to create heterogeneous dual photocatalysts for organic transformations. Notably, experimental evidence from reported cases has shown that the catalytic efficacy of heterogeneous catalysts often surpasses that of their homogeneous analogues. This enhanced performance is attributed to the proximity and confinement effects provided by the porous nature of the carriers. It is expected that porous carriers will provide a versatile platform for integrating diverse catalysts, thus exhibiting superior performance across a range of organic transformations and appealing prospect for industrial applications.

Taking John Schulenberg's "long view" on successful transitions to adulthood: Associations with adult substance use.

Can positive transitions into young adulthood at age 25 prevent problematic substance use at age 31, even in the context of childhood adverse family environments, conduct problems, and adolescent substance use? We lean on John Schulenberg's developmental framework to examine this question, focusing on the potential young adult milestones of high school and college graduation, employment, residential independence, romantic partnership, and parenthood. Data came from a prospective-longitudinal multi-method study with N = 1199 participants who were first assessed at age 5 years old and followed to age 31. An accumulation of positive transitions in young adulthood (age 25) was associated with lower likelihood of age 31 problematic cannabis use. The protective effect for problematic cannabis use remained even when adjusting for childhood adverse family environments and was primarily driven by successful college graduation and/or home ownership. The accumulation of positive transitions protected individuals at modest to somewhat elevated risk due to childhood adverse family environments from experiencing age 31 cannabis use problems. However, for other individuals with very high numbers of conduct problems, or with high levels of adolescent substance use, the protective effects of accumulated positive transitions to young adulthood were less strong or nonexistent. Moreover, individuals who completed college or obtained full-time employment by 25 were more likely to report problematic age 31 alcohol use. These findings highlight the central tenets of John Schulenberg's developmental framework, including the examination of ontogenetic continuity and discontinuity, the interplay of developmentally distal and proximal effects, and the identification of developmental protective factors that may sway people toward or away from substance use.

Deconvoluting the Individual Effects of Nanoparticle Proximity and Size in Thermocatalysis.

Nanoparticle (NP) size and proximity are two physical descriptors applicable to practically all NP-supported catalysts. However, with conventional catalyst design, independent variation of these descriptors to investigate their individual effects on thermocatalysis remains challenging. Using a raspberry-colloid-templating approach, we synthesized a well-defined catalyst series comprising Pd12Au88 alloy NPs of three distinct sizes and at two different interparticle distances. We show that NP size and interparticle distance independently control activity and selectivity, respectively, in the hydrogenation of benzaldehyde to benzyl alcohol and toluene. Surface-sensitive spectroscopic analysis indicates that the surfaces of smaller NPs expose a greater fraction of reactive Pd dimers, compared to inactive Pd single atoms, thereby increasing intrinsic catalytic activity. Computational simulations reveal how a larger interparticle distance improves catalytic selectivity by diminishing the local benzyl alcohol concentration profile between NPs, thus suppressing its readsorption and consequently, undesired formation of toluene. Accordingly, benzyl alcohol yield is maximized using catalysts with smaller NPs separated by larger interparticle distances, overcoming activity-selectivity trade-offs. This work exemplifies the high suitability of the modular raspberry-colloid-templating method as a model catalyst platform to isolate individual descriptors and establish clear structure-property relationships, thereby bridging the materials gap between surface science and technical catalysts.

Dynamics and Wake Interference Mechanism of Long Flexible Circular Cylinders in Side-by-Side Arrangements

The vortex-induced vibrations of two side-by-side flexible cylinders in a uniform flow were studied using a three-dimensional direct numerical simulation at Reynolds number Re = 350 with an aspect ratio of 100, and a center-to-center spacing ratio of 2.5. A mixture of standing-traveling wave pattern was induced in the in-line (IL) vibration, while the cross-flow (CF) vibration displayed a standing-wave characteristic. The ninth vibration mode prominently occurred in both IL and CF directions, along with competition between multiple modes. Proximity effects from the neighboring cylinder caused the primary frequency to be consistent between IL and CF vibrations for each cylinder, deviating from the IL to CF ratio of 2:1 in isolated cylinder conditions. Repulsive mean lift coefficients were observed in both stationary and vibrating conditions for the two cylinders due to asymmetrical vortex shedding in this small gap. Comparatively, lift and drag coefficients were notably increased in the vibrating condition, albeit with a lower vortex shedding frequency. Positive energy transfer was predominantly excited along the span via vortex shedding from the cylinder itself and the neighboring one, leading to increasing lower-mode vibration amplitudes. The flip-flopping (FF) wake pattern was excited in the stationary and vibrating cylinders, causing spanwise vortex dislocations and wake transition over time, with the FF pattern being more regular in the stationary cylinder case.

Hypertensive Disorders of Pregnancy and Risk of Early Brain Abnormalities on Magnetic Resonance Imaging at Term among Infants Born at ≤32 Weeks’ Gestational Age

To evaluate the proximal effects of hypertensive disorders of pregnancy (HDP) on a validated measure of brain abnormalities in infants born at ≤32 weeks' gestational age (GA) using magnetic resonance imaging (MRI) at term-equivalent age. In a multisite prospective cohort study, 395 infants born at ≤32 weeks' GA, underwent 3T MRI scan between 39 through 44 weeks' postmenstrual age. A single neuroradiologist, blinded to clinical history, evaluated the standardized Kidokoro global brain abnormality score as the primary outcome. We classified infants as HDP-exposed by maternal diagnosis of chronic hypertension, gestational hypertension, preeclampsia, or eclampsia. Linear regression analysis identified the independent effects of HDP on infant brain abnormalities, adjusting for histologic chorioamnionitis, maternal smoking, antenatal steroids, magnesium sulfate, and infant sex. Mediation analyses quantified the indirect effect of HDP mediated via impaired intrauterine growth and prematurity and remaining direct effects on brain abnormalities. 170/395 infants (43%) were HDP-exposed. Adjusted multivariable analyses revealed HDP-exposed infants had 27% (95% CI 5-53%) higher brain abnormality scores than those without HDP exposure (p=0.02), primarily driven by increased white matter injury/abnormality scores (p=0.01). Mediation analyses showed HDP-induced impaired intrauterine growth significantly (p=0.02) contributed to brain abnormality scores (22% of the total effect). Maternal hypertension independently increased the risk for early brain injury and/or maturational delays in infants born at ≤32 weeks' GA with an indirect effect of 22% resulting from impaired intrauterine growth. Enhanced prevention/treatment of maternal hypertension may mitigate the risk of infant brain abnormalities and potential neurodevelopmental impairments.

CrI3/Arsenene vdW heterstructure: Outstanding physical properties and substantially enhanced magnetic stability

CrI3 monolayer has attracted much attention, but it holds a very low magnetic stability, with Curie temperature (TC) of 45 K, seriously limiting the practical applications. To find solutions for this issue, we construct CrI3/As vdW heterstructures (vdWHs). Calculations show that such vdWHs are half-semiconductor with excellent mechanical property and TC of 75.9 K, improved by 73.3 % compared with CrI3 monolayer. Due to a weak orbital hybridization and coupling occurring between As layer and Iin atom-layer upon vdW interactions, the potential well of interfacial Iin atom-layer would become shallower, which make electron flow out from Iin atoms and magnetic moments increased for Cr and Iin atoms, in turn, the ferromagnetic (FM) coupling in Cr-Iin-Cr superexchange magnetic coupling channel is strengthened. Particularly, the magnetic stability can be significantly raised by compression strain, leading TC up to 111.3 K, which is caused by super-exchange interactions of both Cr-Iin-Cr and Cr-As-Cr channels, and magnetic proximity effects increased further. For light absorption, the red-shifted absorption edge relative to CrI3 monolayer and high absorption peak appearing in visible and infrared region allow heterstructures absorbing solar energy in a wider range. Such a phenomenon can be further strengthened by compression strain.

Double ferromagnetic barriers resonant tunneling diodes (RTD) based on the surface of a topological insulator

Resonant tunneling diodes (RTDs), which are based on double barrier quantum well structures, are typically achieved by combining different materials with varying band gap sizes. However, this approach often poses challenges such as material mismatching and dislocations. In this study, we present a novel resonant tunneling diode scheme utilizing the unique properties of topological insulator materials. Specifically, we exploit the gap opening in the band structure of the topological insulator by employing perpendicular magnetization. In this proposed RTD platform, the barrier regions are formed from a ferromagnetic topological insulator through the proximity effect. By adjusting the thickness and spacing of the ferromagnetic barriers, a well region with confined states emerges between the barrier regions. Theoretical analysis reveals that by tuning the back gate voltage, the I-V characteristics exhibit two significant behaviors: negative differential resistance (NDR) and step-like behavior for Fermi energy values of EF = −3 and EF = 3, respectively. Furthermore, we observe an increase in the peak-to-valley ratio (PVR) with higher magnetization values. Notably, the PVR reaches a value of 7.13 for a magnetization value of m = 9. Additionally, we investigate the influence of the well width and barrier thickness on the transport properties of the device.

Long-range superconducting proximity effect in YBa2Cu3O7/La0.7Ca0.3MnO3 weak-link arrays

Long-range superconducting proximity effect in YBa2Cu3O7/La0.7Ca0.3MnO3 weak-link arrays

Electrostatically controlled spin polarization in Graphene-CrSBr magnetic proximity heterostructures

The magnetic proximity effect can induce a spin dependent exchange shift in the band structure of graphene. This produces a magnetization and a spin polarization of the electron/hole carriers in this material, paving the way for its use as an active component in spintronics devices. The electrostatic control of this spin polarization in graphene has however never been demonstrated so far. We show that interfacing graphene with the van der Waals antiferromagnet CrSBr results in an unconventional manifestation of the quantum Hall effect, which can be attributed to the presence of counterflowing spin-polarized edge channels originating from the spin-dependent exchange shift in graphene. We extract an exchange shift ranging from 27 – 32 meV, and show that it also produces an electrostatically tunable spin polarization of the electron/hole carriers in graphene ranging from − 50% to + 69% in the absence of a magnetic field. This proof of principle provides a starting point for the use of graphene as an electrostatically tunable source of spin current and could allow this system to generate a large magnetoresistance in gate tunable spin valve devices.

Evidence of a Proximity Effect in a (AgI)x - C(1-x) Mixture Using a Simulation Model Based on Random Variable Theory.

Silver iodide is a prototype compound of superionic conductors that allows ions to flow through its structure. It exhibits a first-order phase transition at 420 K, characterized by an abrupt change in its ionic conductivity behavior, and above this temperature, its ionic conductivity increases by more than three orders of magnitude. Introducing small concentrations of carbon into the silver iodide structure produces a new material with a mixed conductivity (ionic and electronic) that increases with increasing temperature. In this work, we report the experimental results of the ionic conductivity as a function of the reciprocal temperature for the (AgI)x - C(1-x) mixture at low carbon concentrations (x = 0.99, 0.98, and 0.97). The ionic conductivity behavior as a function of reciprocal temperature was well fitted using a phenomenological model based on a random variable theory with a probability distribution function for the carriers. The experimental data show a proximity effect between the C and AgI phases. As a consequence of this proximity behavior, carbon concentration or temperature can control the conductivity of the (AgI)x - C(1-x) mixture.

Comparative study of a high‐speed permanent magnet motor when powered by different methods

AbstractThe authors present the multi‐physical field performances comparative research for a 30 kW, 30,000 r/min high‐speed permanent magnet motor (HSPMM) when the motor is powered by the sinusoidal pulse width modulation (SPWM) voltage inverter and sinusoidal voltage source, respectively. Firstly, electromagnetic performances including torque, voltage and current of the HSPMM with different driving methods are compared and analysed by the finite element method (FEM). Considering the effects of high operation frequency, power losses of the HSPMM with different driving methods under full‐load conditions are calculated and compared with the skin effect and the proximity effect considered for HSPMM winding copper loss estimation. Based on the above analysis, a prototype driven by the SPWM voltage inverter is manufactured, with its electromagnetic and thermal performances tested and verified. In addition, several influencing factors of the HSPMM rotor eddy current loss are studied, with their effects on the HSPMM under different driving methods further analysed and compared as well. A novel equivalent power supply method is proposed to effectively save the calculation time with a negligible error. Finally, in order to further improve the heat dissipation capacity of the HSPMM, a novel cooling method is intensively studied with its influencing factors further analysed. The cooling effect of the novel cooling method and the temperature of the motor components are verified and calculated by the computational fluid dynamics (CFD) method.

The effect of retail shelf position on private-label brand evaluations

PurposeThis research examines the effects of physical proximity (close vs distant) of retailers’ private label brands (PLBs) relative to national brands (NBs) and brand display orientation (horizontal [brands occupy the same shelf] vs vertical [brands occupy different shelves]) on consumers’ PLB quality perceptions and PLB evaluations.Design/methodology/approachTwo experiments involving real brands in different product categories tested the hypotheses.FindingsA PLB positioned close (vs distant) to a NB is evaluated more favorably and this effect is mediated by increased PLB quality perceptions, but only in a horizontal brand display. In a vertical brand display, a PLB positioned close (vs distant) to a NB is evaluated less favorably and this effect is mediated by decreased PLB quality perceptions.Research limitations/implicationsThe findings suggest that to enhance consumers’ PLB quality perceptions and evaluations, PLBs be positioned next to (rather than on separate shelves) and close to (rather than distant from) NBs in the same product category.Originality/valueAlthough the literature suggests that the best shelf position for PLBs is close to NBs, there is a lack of empirical research on the effects of relative shelf positioning on consumers’ quality perceptions and subsequent PLB evaluations. This research finds that both physical proximity and brand display orientation play an important role.

Andreev Conductance in Disordered SF Junctions with Spin-Orbit Scattering

AbstractWe calculate the conductance of a junction between a disordered superconductor and a very strong half-metallic ferromagnet admitting electrons with only one spin projection. A usual mechanism of Andreev reflection is strongly suppressed in this case since Cooper pairs are composed of electrons with opposite spins. However, this obstacle can be overcome if we take into account spin-orbit scattering inside the superconductor. Spin-orbit scattering induces a fluctuational (zero on average) spin-triplet component of the superconducting condensate, which is enough to establish Andreev transport into a strong ferromagnet. This remarkably simple mechanism is quite versatile and can explain long-range triplet proximity effect in a number of experimental setups. One particular application of the suggested effect is to measure the spin-orbit scattering time $$\tau _{\text {SO}}$$ τ SO in disordered superconducting materials. The value of Andreev conductance strongly depends on the parameter $$\Delta \tau _\text {SO}$$ Δ τ SO and can be noticeable even in very disordered but relatively light metals like granular aluminum.

Chirality-Dependent Valley Polarization in Magnetic van der Waals Heterostructures via Spin-Selective Charge Transfer.

Magnetic proximity interaction provides a promising route to manipulate the spin and valley degrees of freedom in van der Waals heterostructures. Here, we report a control of valley pseudospin in the WS2/MoSe2 heterostructure by utilizing the magnetic proximity effect of few-layered CrBr3 and, for the first time, observe a substantial difference in valley polarization of intra/interlayer excitons under different circularly polarized laser excitations, referred to as chirality-dependent valley polarization. Theoretical and experimental results reveal that the spin-selective charge transfer between MoSe2 and CrBr3, as well as between MoSe2 and WS2, is mostly responsible for the chiral feature of valley polarization in comparison with the proximity exchange field. This means that a long-distance manipulation of exciton behaviors in multilayer heterostructures can be achieved through spin-selective charge transfer. This work marks a significant advancement in the control of spin and valley pseudospin in multilayer structures.

Giant impurity effect on anomalous Hall effect of Mn3Sn.

Mn3Sn is an anomalous Hall effect (AHE) antiferromagnet that exhibits the hysteretic AHE in antiferromagnetic (AFM) phase at room temperature. We report that whisker Mn3Sn crystals grown by the flux method exhibit a non-hysteretic AHE at mid-to-low temperatures when the whisker Mn3Sn is surrounded by a thin layer of ferromagnetic Mn2-xSn. These crystals exhibit a hysteretic AHE above 275K due to the spin alignment of the inverse triangular lattice, which is similar to other crystals. However, upon cooling the crystal, it exhibits a non-hysteretic AHE with a spiral AFM spin structure at 100-200K. We concluded that the non-hysteretic AHE is induced at the interface of Mn2-xSn/Mn3Sn. We believe that the scalar-spin chirality in the spiral AFM phase of Mn3Sn, modulated by Mn2-xSn through the magnetic proximity effect, produces the AHE. This discovery opens a new avenue for tailoring the AHE by magnetic layers.

Tailoring coercive fields and the Curie temperature via proximity coupling in WSe2/Fe3GeTe2 van der Waals heterostructures

Hybrid structures consisting of two-dimensional (2D) magnets and semiconductors have exhibited extensive functionalities in spintronics and opto-spintronics. In this work, we have fabricated WSe2/Fe3GeTe2 van der Waals heterostructures and investigated proximity effects on 2D magnetism. Through reflective magnetic circular dichroism, we have observed a temperature-dependent modulation of magnetic order in the heterostructure. For temperatures above 40K , WSe2-covered Fe3GeTe2 exhibits a larger coercive field than that observed in bare Fe3GeTe2, accompanied by a noticeable enhancement of the Curie temperature by 21K . This strengthening suggests an increase in magnetic anisotropy in the interfacial Fe3GeTe2 layer, which can be attributed to the spin–orbit coupling (SOC) proximity effect induced by the adjacent WSe2 layers. However, at much lower temperatures ( T<20K ), a non-monotonic modification of the coercive field is observed, showing both reduction and enhancement, which depends on the thickness of the WSe2 and Fe3GeTe2 layers. Moreover, an unconventional two-step magnetization process emerges in the heterostructure, indicating the short-range nature of SOC proximity effects. Our findings on proximity coupling may shed light on the design of future spintronic and memory devices based on 2D magnetic heterostructures.

The moderating role of the territorial research infrastructure on the geographic proximity effect in research collaborations: a regional-based view

The moderating role of the territorial research infrastructure on the geographic proximity effect in research collaborations: a regional-based view

The effect of proximity on risk perception: A systematic literature review

The use of geospatial analytical tools has recently advanced risk perception research, with growing interest in spatial dimension. Available reviews of risk perception studies usually focus on specific types of risk or look at various socio-psychological, cognitive and cultural factors, and there are no systematic reviews of empirical research analysing the effect of proximity on risk perception. This article synthesizes the evidence from 81 empirical studies that investigate the significance of proximity on subjective risk perception. The systematic review focused on summaries of research methods, samples, geographic coverage, measurements and direction of influence of proximity variables on risk perception and types and sources of risk. The majority of the studies analysed implemented quantitative research. The most popular data collection methods were face-to-face interviews and postal surveys, but only half had representative samples. Studies looking into the effect of proximity on risk perception most often analysed environmental and technological risks. Two-thirds of the empirical studies found a significant impact of proximity on risk perception; the majority of these showed a positive correlation, with respondents living closer to hazards having higher risk perceptions. Negative correlations of risk perception with proximity are more characteristic of nuclear risks. Co-occurrence analysis of sources-of-risk and objects-at-risk has identified three most frequent clusters: impact of floods on economic properties; impact of other natural hazards on economic properties and impact of industrial facilities on health and lives.

LEED certification system for green buildings in China: Examining spatial differences, temporal evolution, and spatial overflow

This paper examines the spread of green building development in China by analyzing the implementation of the LEED certification system across 31 provinces from 2006 to 2022. To investigate spatial differences, spatial-temporal evolution, and spatial spillovers of green building development in China, we employed various statistical methods, including Standard Distance Ellipse, Dagum's Gini Coefficient, Kernel Density Estimation, Markov Chain Analysis, Moran's I Exponential Analysis, and Social Network Analysis. The findings reveal the formation of a green building cluster in a northeast-southwest orientation, at the core of the Beijing-Tianjin-Hebei, Yangtze River Delta, and Pearl River Delta regions. There is compelling evidence of substantial regional disparities in green building development, primarily driven by inter-regional differences, which has resulted in a significant gap between the eastern and non-eastern regions. This study identifies the presence of “club convergence” and the “Matthew effect” in China's green building landscape, where spatial factors play a crucial role. Furthermore, a distinct and stable spatial clustering is observed, indicating a complex and multi-faceted spatial association network that goes beyond geographical proximity and neighborhood effects. This network reveals diverse positions and roles for provinces and cities. The eastern provinces and cities are found to exert strong control and dominance while also playing a significant siphoning role. On the other hand, the western provinces and cities have been marginalized, experiencing minimal dividend spillover from the development of other provinces.

Large thermoelectric transport in magnetically coupled CrI3/1T-MoS2 vdW heterostructure via spin–charge interconversion

Low-dimensional materials with prominent thermoelectric (TE) effect play a pivotal role in realizing state-of-the-art nanoscale TE devices. The fusion of TE effect with the magnetism through seamless integration of TE and magnetic materials in the 2D limit offers access to control longitudinal as well as transverse TE properties via magnetic proximity effect. Herein, we design a van der Waals (vdW) heterostructure of metallic 1T-MoS2 with promising TE properties and a layer-dependent magnetic CrI3 material. The result highlights exotic electronic and magnetic configurations of the designed monolayer-CrI3/1T-MoS2 vdW heterostructure, which show magnetically-coupled TE characteristics. The observed remarkable magnetic proximity stems from large magnetic anisotropy energy and spin polarization, which are found to be 2.21 meV Cr−1 and 12.30%, respectively. To this end, the semiconducting CrI3 layer with intrinsic magnetism leads to efficient control and tunability of the observed spin-correlated anomalous Nernst effect. Moreover, a large dimensionless figure of merit of ∼6 and a power factor of ∼3.8×1011/τ∘ Wm−1K−2s−1 near the Fermi level at 300 K endorse the rejuvenated TE effect. The strong relativistic spin–orbit coupling validates the significant correlation of TE properties with intrinsic magnetic configuration. The present study underscores the significance of the magnetic proximity-governed TE effect in vdW heterostructures to engineer low-dimensional TE devices.