Anisotropic Galvanomagnetic Effects in Single Cubic Crystals: A Theory and Its Verification.

A theory of anisotropic galvanomagnetic effects in single cubic crystals and its experimental verifications are presented for the current in the (001) plane. In contrast to the general belief that galvanomagnetic effects in single crystals are highly sensitive to many internal and external effects and have no universal features, the theory predicts universal angular dependencies of longitudinal and transverse resistivity and various characteristics when magnetization rotates in the (001) plane, the plane perpendicular to the current, and the plane containing the current and [001] direction. The universal angular dependencies are verified by experiments on Fe_{30}Co_{70} single cubic crystal film. The findings provide new avenues for fundamental research and applications of galvanomagnetic effects, because single crystals offer advantages over polycrystalline materials for band structure and crystallographic orientation engineering.

Incommensurate Spin Density Wave in Antiferromagnetic RuO_{2} Evinced by Abnormal Spin Splitting Torque.

Since the discovery of antiferromagnetism, metallic oxide RuO_{2} has exhibited numerous intriguing spintronics properties such as the anomalous Hall effect and anisotropic spin splitting effect. However, the microscopic origin of its antiferromagnetism remains unclear. By investigating the spin splitting torque in RuO_{2}/Py, we found that metallic RuO_{2} exhibits a spatially periodic spin structure which interacts with the spin waves in Py through interfacial exchange coupling. The wavelength of such structure is evaluated within 14-20 nm depending on the temperature, which is evidence of an incommensurate spin density wave state in RuO_{2}. Our work not only provides a dynamics approach to characterize the antiferromagnetic ordering in RuO_{2}, but also offers fundamental insights into the spin current generation due to anisotropic spin splitting effect associated with spin density wave.

Significant Change of Metal Cations in Geometric Sites by Magnetic-Field Annealing FeCo2 O4 for Enhanced Oxygen Catalytic Activity.

The application of magnetic fields in the oxygen reduction/evolution reaction (ORR/OER) testing for electrocatalysts has attracted increasing interest, but it is difficult to characterize on-site surface reconstruction. Here, a strategy is developed for annealing-treated FeCo2 O4 nanofibers at a magnetic field of 2500 Oe, named FeCo2 O4 -M, showing a right-shifted half-wave potential of 20 mV for the ORR and a left-shifted overpotential of 60 mV at 10 mV cm-2 for the OER as compared with its counterpart. Magnetic characterizations indicate that FeCo2 O4 -M shows the spin-state transition of cations from a low-spin state to an intermediate-spin state compared with FeCo2 O4 . Mössbauer spectra show that the Fe3+ ion in the octahedral site (0.76) of FeCo2 O4 -M is more than that of FeCo2 O4 (0.71), indicating the effective stimulus of metal cations in geometric sites by magnetic-field annealing. Furthermore, theoretical calculations demonstrate that the d-band centers (εd ) of Co 3d and Fe 3d in the tetrahedral and octahedral sites of the FeCo2 O4 -M nanofibers shift close to the Fermi level, revealing the enhanced mechanism of the ORR/OER activity.

Observation of the antiferromagnetic spin Hall effect.

The discovery of the spin Hall effect1 enabled the efficient generation and manipulation of the spin current. More recently, the magnetic spin Hall effect2,3 was observed in non-collinear antiferromagnets, where the spin conservation is broken due to the non-collinear spin configuration. This provides a unique opportunity to control the spin current and relevant device performance with controllable magnetization. Here, we report a magnetic spin Hall effect in a collinear antiferromagnet, Mn2Au. The spin currents are generated at two spin sublattices with broken spatial symmetry, and the antiparallel antiferromagnetic moments play an important role. Therefore, we term this effect the 'antiferromagnetic spin Hall effect'. The out-of-plane spins from the antiferromagnetic spin Hall effect are favourable for the efficient switching of perpendicular magnetized devices, which is required for high-density applications. The antiferromagnetic spin Hall effect adds another twist to the atomic-level control of spin currents via the antiferromagnetic spin structure.

Cr cation-anchored carbon nanosheets: synthesis, paramagnetism and ferromagnetism.

Since the successfully synthesis of monolayer graphene, carbon-based materials have attracted wide and extensive attentions from researches. Due to the excellent transport capacity and conductivity, they are promising to be applied in electronic devices, even substituting the silicon-based electronic devices, optoelectronics and spintronics. Nevertheless, due to the non magnetic feature, many efforts have been devoted to endow carbon materials magnetism to apply them in the spintronic devices fabrication. Herein, a strategy of Cr cation solely anchored on two-dimensional carbon nanosheets by Cr-N bonds is developed, which introduces magnetism in carbon nanosheets. By extended x-ray absorption fine structure characterization, Cr cations are demonstrated to be atomically dispersed with Cr-N3coordination. And after Cr-N3anchored, carbon nanosheets exhibit ferromagnetic features with paramagnetic background. The magnetization varies with Cr content and reaches the maximum (Cr: 2.0%, 0.86 emu g-1) under 3 T at 50 K. The x-ray magnetic circular dichroism and first-principle calculations indicate that the magnetism is caused by the Cr3+component of the anchored Cr cations. This study sets a single cation anchoring carbon as a suitable candidate for future spintronics.

Effect of Rainfall and Temperature on Perithecium Production of Botryosphaeria dothidea on Cankered Apple Branches.

Botryosphaeria dothidea is a fungal pathogen causing canker, dieback, and fruit rot of apple trees worldwide. Ascospores are an important source of inoculum of Botryosphaeria canker in China. Experiments were conducted under both controlled and natural conditions to study perithecium formation in relation to environmental conditions. Perithecia of B. dothidea were detected on cankered lesions throughout the apple growing season except in July and in some years including August under natural conditions. On newly formed canker lesions, the first perithecium was detected as early as August, about 1 week after rainfall. Perithecia matured successively, lasting from early August to June of the next year, with a peak in late September or early October. Temperature and rainfall are two key environmental factors affecting perithecium formation. Under controlled conditions, perithecia were produced only on cankered shoots incubated at test temperatures of 20 and 25°C and wetted by >3 days of simulated rainfall per week. The number of perithecia produced on canker lesions increased with the increase in rainfall duration. Perithecia were formed on canker shoots exposed to rainfall only in June, July, and August but not in September. Rainfall of >3 days per week can be used to predict the initial formation of perithecia in the main apple production areas in China to assist disease management.

Co and CeO2 co-decorated N-doping carbon nanofibers for rechargeable Zn-air batteries.

The heterogeneous Co and CeO2 co-decorated N-doping carbon nanofibers (Co-CeO2-N-C) were synthesized via the electrospinning technique. As the bifunctional electrocatalyst, Co-CeO2-N-C nanofibers show excellent oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) performance, owing to the higher degree of graphitization of carbon, the N-doping, and the formation of an interface between Co and CeO2. The liquid Zn-air battery based on Co-CeO2-N-C nanofibers displays excellent specific capacities (815.9 mA h g-1 at 5 mA cm-2), higher open circuit voltages (1.47 V), and good cycling stability (113 h). The corresponding flexible solid state Zn-air battery shows excellent cycling stability (11 h), and good flexibility. Our finding suggests that Co-CeO2-N-C nanofibers could serve as a new group of bifunctional electrocatalysts for OER and ORR with excellent performance, and make them promising for use in future electric vehicles, off-grid power sources, and portable electronics.

Exploring the links between population density, lifestyle, and being overweight: secondary data analyses of middle-aged and older Chinese adults.

BACKGROUND: The increasing prevalence of obesity across all age groups has become a major health concern in China. Previous studies have found strong links between population density, sedentary lifestyle, and the risk of being overweight among adults and adolescents in Western countries. However, little research has been conducted to disentangle this relationship in China, which is rapidly urbanizing and densely populated. Compared to other age groups, middle-aged and older adults tend to have a higher risk of being overweight, which increases their risk of diabetes, high blood pressure, and other weight-related chronic diseases. In addition, they are especially sensitive to neighbourhood environmental factors such as population density. Therefore, we aimed to unravel the link between population density and the risk of being overweight among Chinese middle-aged and older adults, with a particular focus on the mediating role of lifestyle choices. METHODS: Data from the 2011 China Health and Retirement Longitudinal Study were analysed. Individuals (N = 5285) were sampled from 405 neighbourhoods nested within 150 cities. Body Mass Index (BMI) was calculated based on self-reported body weight and height (being overweight was defined as a BMI ≥ 24 kg/m2). Multilevel regression and mediation analyses were applied to explore associations between population density, a sedentary lifestyle, and the risk of being overweight. RESULTS: Middle-aged and older adults who lived in densely populated neighbourhoods had higher odds of being overweight. Further, this link was mediated by residents' mode of travel and physical exercise; specifically, these residents had higher odds of owning a car and spending lesser time on weekly physical exercise, thereby increasing their risk of being overweight. Furthermore, the association between car ownership and the odds of being overweight varied by neighbourhood population density. CONCLUSIONS: There was a positive association between neighbourhood population density and middle-aged and older adults' risk of being overweight. This relationship may exist because people who live in densely populated neighbourhoods tend to lead a sedentary lifestyle. Our findings also suggest that, in rapidly urbanizing countries, a sedentary lifestyle may be especially harmful to middle-aged and older adults who live in densely populated neighbourhoods.

Depressive symptoms among Chinese residents: how are the natural, built, and social environments correlated?

BACKGROUND: Depression has become a severe societal problem in China. Although many studies have analyzed how environmental characteristics within neighborhoods affect depression, only a few have dealt with developing countries, and even fewer have considered built, natural, and social environments concurrently. METHODS: Based on a sample of 20,533 Chinese residents assessed in 2016, the present study examined associations between depressive symptoms and respondents' built, natural, and social environments. Depressive symptoms were measured using the Center for Epidemiologic Studies Depression Scale (CES-D), and multilevel regression models were fitted accounting for potential covariates. RESULTS: Results indicated that living in neighborhoods with more green spaces and a higher population density were negatively associated with CES-D scores. Living in neighborhoods with more social capital was protective against depression. Furthermore, results showed that the social environment moderated the association between the built environment and depression. CONCLUSIONS: Social environments moderate the relationship between the built environment and depression. As environments seem to interact with each other, we advise against relying on a single environment when examining associations with depressive symptoms.

Dual-Native Vacancy Activated Basal Plane and Conductivity of MoSe2 with High-Efficiency Hydrogen Evolution Reaction.

Although transition metal dichalcogenide MoSe2 is recognized as one of the low-cost and efficient electrocatalysts for the hydrogen evolution reaction (HER), its thermodynamically stable basal plane and semiconducting property still hamper the electrocatalytic activity. Here, it is demonstrated that the basal plane and edges of 2H-MoSe2 toward HER can be activated by introducing dual-native vacancy. The first-principle calculations indicate that both the Se and Mo vacancies together activate the electrocatalytic sites in the basal plane and edges of MoSe2 with the optimal hydrogen adsorption free energy (ΔGH* ) of 0 eV. Experimentally, 2D MoSe2 nanosheet arrays with a large amount of dual-native vacancies are fabricated as a catalytic working electrode, which possesses an overpotential of 126 mV at a current density of 100 mV cm-2 , a Tafel slope of 38 mV dec-1 , and an excellent long-term durability. The findings pave a rational pathway to trigger the activity of inert MoSe2 toward HER and also can be extended to other layered dichalcogenide.

The relationship between urbanization and depression in China: the mediating role of neighborhood social capital.

BACKGROUND: Previous studies in developed countries have found that living in rapidly urbanizing areas is associated with higher risk of mental illness and that social capital had a protective effect on individual mental health. However, the literature is missing empirical studies of the relationship between urbanization, neighborhood social capital and mental health in rapidly urbanizing countries. To bridge this knowledge gap, this study investigated the effects of urbanization on depressive symptoms in China, with an emphasis on the mediating role of neighborhood social capital in the relationship between urbanization and individual-level depressive symptoms. METHODS: Nationally representative survey data from the 2016 wave of China's Labor-force Dynamics Survey were used. A sample of 20,861 individuals was obtained from 401 neighborhoods in 158 prefecture-level divisions of 29 provinces. Depressive symptoms were measured using CES-D scores. Neighborhood social capital was assessed by three individual-level variables aggregated to the neighborhood level: perceptions of neighborly trust, the extent of neighborly reciprocity, and membership to neighborhood social groups. Multilevel linear regression and mediation analyses were used to estimate the statistical relationships. RESULTS: The multilevel linear regression analyses found negative relationships between urbanization rate and CES-D score. The mediation analysis found that neighborhood-level social capital was an inconsistent mediator in the relationship between urbanization rate and CES-D score. Interaction terms between urbanization rate and two measures of neighborhood-level social capital were statistically significant, indicating that the protective effects of neighborly reciprocity and membership to neighborhood social groups on CES-D scores (negative relationships) were stronger in the relatively more urbanized areas. CONCLUSION: Urbanization supports mental health in the Chinese context, although it might undermine residents' mental health by reducing neighborhood social capital. The protective effect of neighborhood-level reciprocity and social group membership on mental health increased with urbanization.

Magnetization switching through domain wall motion in Pt/Co/Cr racetracks with the assistance of the accompanying Joule heating effect.

Heavy metal/ferromagnetic layers with perpendicular magnetic anisotropy (PMA) have potential applications for high-density information storage in racetrack memories and nonvolatile magnetic random access memories. In these devices, deterministic magnetization switching has been achieved via electric current induced spin orbital torques (SOTs) with the assistance of a current directional external in-plane bias field, which causes technological obstacles for the real application of SOT based spintronic devices. Here, we report that reversible field-free magnetization switching could be achieved via current-driven domain wall motion (DWM) in Pt/Co/Cr micro-sized racetracks with PMA owing to the preformation of the homochiral Néel-type domain wall, in which an in-plane inherent Dzyaloshinskii-Moriya interaction field was generated acting as the external in-plane bias field to break the symmetry. A full magnetization switching can be realized in this device based on the enhanced SOTs from a dedicated design of Pt/Co/Cr structures with Pt and Cr showing opposite signs of spin Hall angles. Therefore, the generated spin currents are expected to work in concert to improve the SOTs. We also demonstrated that the simultaneously accompanying Joule heating effect also plays a key role in the field-free magnetization switching process, including the propagation field as well as the domain wall motion velocity.

Urbanization, economic development and health: evidence from China's labor-force dynamic survey.

BACKGROUND: The frequent outbreak of environmental threats in China has resulted in increased criticism regarding the health effects of China's urbanization. Urbanization is a double-edged sword with regard to health in China. Although great efforts have been made to investigate the mechanisms through which urbanization influences health, the effect of both economic development and urbanization on health in China is still unclear, and how urbanization-health (or development-health) relationships vary among different income groups remain poorly understood. To bridge these gaps, the present study investigates the impact of both urbanization and economic development on individuals' self-rated health and its underlying mechanisms in China. METHODS: We use data from the national scale of the 2014 China Labor-force Dynamics Survey to analyze the impact of China's urbanization and economic development on health. A total of 14,791 individuals were sampled from 401 neighborhoods within 124 prefecture-level cities. Multilevel ordered logistic models were applied. RESULTS: Model results showed an inverted U-shaped relationship between individuals' self-rated health and urbanization rates (with a turning point of urbanization rate at 42.0%) and a positive linear relationship between their self-rated health and economic development. Model results also suggested that the urbanization-health relationship was inverted U-shaped for high- and middle-income people (with a turning point of urbanization rate at 0.0% and 49.2%, respectively), and the development-health relationship was inverted U-shaped for high- and low-income people (with turning points of GDP per capita at 93,462 yuan and 71,333 yuan, respectively) and linear for middle-income people. CONCLUSION: The impact of urbanization and economic development on health in China is complicated. Careful assessments are needed to understand the health impact of China's rapid urbanization. Social and environmental problems arising from rapid urbanization and economic growth should be addressed. Equitable provision of health services are needed to improve low-income groups' health in highly urbanized cities.

Engineering magnetic anisotropy and magnetization switching in multilayers by strain.

The effect of the strain on the magnetic properties of metallic multilayers has been investigated by ab initio studies. Our results indicate that the magnetic anisotropy energy (MAE) of an Fe(001) surface can be drastically enhanced by capping with 5d elements. By choosing Ir-Fe multilayers as a model system, we demonstrate that the MAE which depends on the composition and the structure of the multilayers can be tuned in a large range by strain. Furthermore, our results show that not only the amplitude of the MAE but also the easy axis of Pt-Fe multilayers can be engineered by strain. Magnetization switching by strain is also investigated.

Structural Phase Transition Effect on Resistive Switching Behavior of MoS2 -Polyvinylpyrrolidone Nanocomposites Films for Flexible Memory Devices.

The 2H phase and 1T phase coexisting in the same molybdenum disulfide (MoS2 ) nanosheets can influence the electronic properties of the materials. The 1T phase of MoS2 is introduced into the 2H-MoS2 nanosheets by two-step hydrothermal synthetic methods. Two types of nonvolatile memory effects, namely write-once read-many times memory and rewritable memory effect, are observed in the flexible memory devices with the configuration of Al/1T@2H-MoS2 -polyvinylpyrrolidone (PVP)/indium tin oxide (ITO)/polyethylene terephthalate (PET) and Al/2H-MoS2 -PVP/ITO/PET, respectively. It is observed that structural phase transition in MoS2 nanosheets plays an important role on the resistive switching behaviors of the MoS2 -based device. It is hoped that our results can offer a general route for the preparation of various promising nanocomposites based on 2D nanosheets of layered transition metal dichalcogenides for fabricating the high performance and flexible nonvolatile memory devices through regulating the phase structure in the 2D nanosheets.

Tuning magnetic properties of antiferromagnetic chains by exchange interactions: ab initio studies.

The possibility of using exchange interactions to manipulate the spin state of an antiferromagnetic nanostructure is explored using ab initio calculations. By considering M (M = Mn, Fe, Co) mono-atomic chains supported on Cu2N islands on a Cu(001) surface as a model system, it is demonstrated that two indistinguishable Néel states of an antiferromagnetic chain can be tailored into a preferred state by the exchange interaction with a magnetic STM tip. The magnitude and direction of the anisotropy for antiferromagnetic chains can also be tuned by exchange coupling upon varying the tip-chain separation.

Co@Co3O4 core-shell three-dimensional nano-network for high-performance electrochemical energy storage.

An alternative routine is presented by constructing a novel architecture, conductive metal/transition oxide (Co@Co3O4) core-shell three-dimensional nano-network (3DN) by surface oxidating Co 3DN in situ, for high-performance electrochemical capacitors. It is found that the Co@Co3O4 core-shell 3DN consists of petal-like nanosheets with thickness of <10 nm interconnected forming a 3D porous nanostructure, which preserves the original morphology of Co 3DN well. X-ray photoelectron spectroscopy by polishing the specimen layer by layer reveals that the Co@Co3O4 nano-network is core-shell-like structure. In the application of electrochemical capacitors, the electrodes exhibit a high specific capacitance of 1049 F g(-1) at scan rate of 2 mV/s with capacitance retention of ~52.05% (546 F g(-1) at scan rate of 100 mV) and relative high areal mass density of 850 F g(-1) at areal mass of 3.52 mg/cm(2). It is believed that the good electrochemical behaviors mainly originate from its extremely high specific surface area and underneath core-Co "conductive network". The high specific surface area enables more electroactive sites for efficient Faradaic redox reactions and thus enhances ion and electron diffusion. The underneath core-Co "conductive network" enables an ultrafast electron transport.

Nanoscale characterization of 1D Sn-3.5Ag nanosolders and their application into nanowelding at the nanoscale.

One-dimensional Sn-3.5Ag alloy nanosolders have been successfully fabricated by a dc electrodeposition technique into nanoporous templates, and their soldering quality has been demonstrated in nanoscale electrical welding for the first time, which indicates that they can easily form remarkably reliable conductive joints. The electrical measurement shows that individual 1D Sn-3.5Ag nanosolders have a resistivity of 28.9 µΩ·cm. The morphology, crystal structure and chemistry of these nanosolders have been characterized at the nanoscale. It is found that individual 1D Sn-3.5Ag alloy nanosolders have a continuous morphology and smooth surface. XPS confirms the presence of tin and silver with a mass ratio of 96.54:3.46, and EDX elemental mappings clearly reveal that the Sn and Ag elements have a uniform distribution. Coveragent beam electron diffractions verify that the crystal phases of individual 1D Sn-3.5Ag alloy nanosolders consist of matrix ß-Sn and the intermetallic compound Ag3Sn. The reflow experiments reveal that the eutectic composition of the 1D Sn-Ag alloy nanowire is shifted to the Sn rich corner. This work may contribute one of the most important tin-based alloy nanosolders for future nanoscale welding techniques, which are believed to have broad applications in nanotechnology and the future nano-industry.

Intrinsic ferromagnetism in hexagonal boron nitride nanosheets.

Understanding the mechanism of ferromagnetism in hexagonal boron nitride nanosheets, which possess only s and p electrons in comparison with normal ferromagnets based on localized d or f electrons, is a current challenge. In this work, we report an experimental finding that the ferromagnetic coupling is an intrinsic property of hexagonal boron nitride nanosheets, which has never been reported before. Moreover, we further confirm it from ab initio calculations. We show that the measured ferromagnetism should be attributed to the localized π states at edges, where the electron-electron interaction plays the role in this ferromagnetic ordering. More importantly, we demonstrate such edge-induced ferromagnetism causes a high Curie temperature well above room temperature. Our systematical work, including experimental measurements and theoretical confirmation, proves that such unusual room temperature ferromagnetism in hexagonal boron nitride nanosheets is edge-dependent, similar to widely reported graphene-based materials. It is believed that this work will open new perspectives for hexagonal boron nitride spintronic devices.

Critical behaviors of van der Waals itinerant ferromagnet Fe3.8GaTe2.

The critical behavior of the van der Waals ferromagnet Fe3.8GaTe2was systematically studied through measurements of isothermal magnetization, with the magnetic field applied along thec-axis. Fe3.8GaTe2undergoes a non-continuous paramagnetic to ferromagnetic phase transition at the Curie temperatureTc∼ 355 K. A comprehensive analysis of isotherms aroundTcutilizing the modified Arrott diagram, the Kouvel-Fisher method, the Widom scaling law, and the critical isotherm analysis yielded the critical exponent ofß= 0.411,γ= 1.246, andδ= 3.99. These critical exponents are found to be self-consistent and align well with the scaling equation at high magnetic fields, underscoring the reliability and intrinsic nature of these parameters. However, the low-field data deviates from the scaling relation, exhibiting a vertical trend whenT