Room-temperature low-threshold avalanche effect in stepwise van-der-Waals homojunction photodiodes.

Avalanche or carrier-multiplication effect, based on impact ionization processes in semiconductors, has a great potential for enhancing the performance of photodetector and solar cells. However, in practical applications, it suffers from high threshold energy, reducing the advantages of carrier multiplication. Here, we report on a low-threshold avalanche effect in a stepwise WSe2 structure, in which the combination of weak electron-phonon scattering and high electric fields leads to a low-loss carrier acceleration and multiplication. Owing to this effect, the room-temperature threshold energy approaches the fundamental limit, Ethre ≈ Eg, where Eg is the bandgap of the semiconductor. Our findings offer an alternative perspective on the design and fabrication of future avalanche and hot-carrier photovoltaic devices.

What makes residents participate in the rural toilet revolution?

•Motivation of Chinese rural residents to participate in RTR identified•Motivational model of Chinese rural resident participating in RTR is constructed•Model includes intrinsic and extrinsic factors, and impacts of RTR policy•RTR policy may influence rural residents' final decision to participate RTR.

Sesquiterpene from Artemisia argyi seed extracts: A new anti-acute peritonitis agent that suppresses the MAPK pathway and promotes autophagy.

To find novel anti-inflammatory drugs, we screened anti-inflammatory compounds from 18 different types of Artemisia argyi seed extracts. The in vitro and in vivo anti-inflammatory activities of the screened compounds and their mechanisms were characterized. We first detected the cytotoxic effect of the compounds on RAW264.7 cells and the inhibitory effect on LPS-induced NO release. It was found that sesquiterpenoids CA-2 and CA-4 had low cytotoxic and strong NO inhibitory activity with an IC50 of 4.22 ± 0.61 µM and 2.98 ± 0.23 µM for NO inhibition, respectively. Therefore, compound CA-4 was studied in depth. We found that compound CA-4 inhibited LPS-induced pro-inflammatory factor production and M1 macrophage differentiation in RAW264.7 cells. Additionally, CA-4 inhibited the expression of p-ERK1/2, p-JNK, iNOS, and COX-2 by blocking the MAPK signaling pathway. CA-4 also promoted the expression of autophagy-related proteins such as LC3 II and Beclin-1 by inhibiting activation of the PI3K/AKT/mTOR signaling pathway, and promoted the generation of autophagosomes. Finally, CA-4 significantly inhibited the degree of inflammation in mice with acute peritonitis, showing good anti-inflammatory activity in vivo. Consequently, compound CA-4 may be a promising drug for the treatment of acute inflammatory diseases and provide new ideas for the synthesis of novel anti-inflammatory compounds.

Dynamic Homogenization of Internal Strain in Multi-Principal Element Alloy via High-Concentration Doping of Oxygen with Large Mobility.

Internal strain and its distribution within the crystal lattice play crucial roles in modulating dislocation activities, thereby affecting mechanical properties of materials. Through the synergistic application of integrated differential phase contrast, in situ transmission electron microscopy characterizations, and computational simulations, a method is unveiled for homogenizing dislocation pinning in NiCoCr multi-principal element alloy (MPEA) through the introduction of a high concentration of oxygen atoms with high diffusion mobility. The doping of massive oxygen atoms creates a high density of strong local pinning points for dislocation motion. Notably, oxygen interstitials exhibit remarkable diffusion and mobility across different octahedral and tetrahedral sites within the distorted crystal lattice of NiCoCrO alloy, even at room temperature. The capability allows for the release of severe stress concentrations arising from dislocation entanglement and the establishment of new strong local pinning points at alternative locations in a uniform way, enabling the material with high strength and outstanding deformability. These findings suggest that interstitial atoms can exhibit significant mobility, even at ambient temperature, in complex MPEAs with spreading lattice distortion, opening new possibilities for dislocation engineering.

Public attitudes towards dialects: Evidence from 31 Chinese provinces.

BACKGROUND: Dialect Attitude is conceptualized as an individual's cognitive and affective evaluation of a dialect and its speakers. In the contemporary China, dialect is suffering from significant stigmatization, resulting in social inequalities, which hinder sustainable development. This study aims to reveal the Chinese public attitudes towards dialects, and clarify the potential determinants related to heterogeneous attitudes at a macro level. METHODS: We combine the crawler technology and sentiment analysis to conduct a provincial cross-sectional study. We collect 1,650,480 microblogs about public attitudes towards dialects from Microblog across 31 specific Chinese provinces. Spatial regression models are utilized to clarify the influence of macro-level determinants on differences in public attitudes. RESULTS: The present study reveals that: (1) The Chinese public generally holds positive attitudes towards dialects, with significant variation between provinces. (2) Political Resource (ß = 0.076, SD = 0.036, P<0.05), Economic Development (ß = 0.047, SD = 0.022, P<0.05), and Cultural Resource (ß = 0.054, SD = 0.021, P<0.05) promote public positive attitudes towards dialects. (3) Political Resource and Culture Resource influence more significant in the relatively advantaged regions, and Economic Development poses a higher influence in the relatively disadvantaged regions. CONCLUSIONS: Basing on the combination of crawler technology and sentiment analysis, the present study develops the most comprehensive database which takes 1,650,480 dialects-related microblogs from 31 Chinese provinces, and describes the following scenario: (1) Overall, the Chinese public shares a relatively positive attitude towards dialects with significant variations among different provinces, (2) Political Resource, Economic Development and Culture Resource pose positive effects on Chinese public attitudes towards dialects and (3) Political Resource and Culture Resource influence more significant in the relatively disadvantaged regions, and Economic Development poses a higher influence in the relatively advantaged regions.

Exploring the relationship between mental health and dialect use among Chinese older adults: a moderated mediation estimation.

Background: Mental health, conceptualized as psychological status that includes rational cognition, emotional stability, and interpersonal harmony, is highly relevant to the expected health and well-being of all humans. China is facing the dual risk of increased aging and mental health disorders in older adults, while the established studies have rarely focused on the influence of dialect on the mental health of Chinese older adults. The present study aims to capture the relationship between dialect and mental health in Chinese older adults. Methods: We use cross-sectional data from the nationally representative China Family Panel Studies, which encompasses the dialect use, mental health, and other socioeconomic features of 4,420 respondents. We construct a moderated mediation model that uses dialects and mental health as the independent and dependent variables and income inequality and subjective well-being as the mediator and moderator to reveal the relationship between dialect and mental health in Chinese older adults. Results: (1) Dialects are shown to have a negative influence on the mental health of older adults in the current study (coefficient = -0.354, 95% CI = [-0.608, -0.097]). (2) Income inequality positively mediates the correlation between dialects and mental health (coefficient = 0.019, 95% CI = [0.010, 0.045]). (3) Subjective well-being negatively moderates the potential mechanism between dialects and mental health (coefficient = -0.126, 95% CI = [-0.284, -0.010]). Conclusion: The use of dialects is associated with worse mental health outcomes in Chinese older adults, while this negative influence is positively mediated by income inequality and negatively moderated by subjective well-being, simultaneously. This study contributes to the knowledge enrichment of government workers, older adults with mental disorders, medical staff, and other stakeholders.

Configurable circular-polarization-dependent optoelectronic silent state for ultrahigh light ellipticity discrimination.

Filterless light-ellipticity-sensitive optoelectronic response generally has low discrimination, thus severely hindering the development of monolithic polarization detectors. Here, we achieve a breakthrough based on a configurable circular-polarization-dependent optoelectronic silent state created by the superposition of two photoresponses with enantiomerically opposite ellipticity dependences. The zero photocurrent and the significantly suppressed noise of the optoelectronic silent state singularly enhance the circular polarization extinction ratio (CPER) and the sensitivity to light ellipticity perturbation. The CPER of our device approaches infinity by the traditional definition. The newly established CPER taking noise into account is 3-4 orders of magnitude higher than those of ordinary integrated circular polarization detectors, and it remains high in an expanded wavelength range. The noise equivalent light ellipticity difference goes below 0.009° Hz-1/2 at modulation frequencies above 1000 Hz by a light power of 281 µW. This scheme brings a leap in developing monolithic ultracompact circular polarization detectors.

Enhanced Surface Properties of the Al0.65CoCrFeNi High-Entropy Alloy via Laser Remelting.

The laser remelting technique was applied to the surface modification of the Al0.65CoCrFeNi high-entropy alloy (HEA) to further advance its mechanical potential. The microstructure of the remelted layer was refined from coarse dendritic to submicron-scale basket weave compared with the as-cast substrate, resulting in a 1.8-time increase in Vickers microhardness. The nanoindentation tests indicated that the nanohardness of the remelted layer was higher than that of each phase in the substrate. Meanwhile, the remelted layer retained considerable plasticity, as evidenced by its high Wp/Wt ratio (0.763) and strain hardening exponent (0.302). Additionally, adhesive wear prevailed on the substrate, while only abrasive wear features were observed on the remelted layer. Accordingly, the average friction coefficient and the wear rate of the remelted layer were minimized by 23% and 80%, respectively, compared with the substrate. Our findings explored an industrialized method to enhance the surface properties of the Al0.65CoCrFeNi HEA and also provided some helpful references for its laser additive manufacturing.

Predicting future coastal land use/cover change and associated sea-level impact on habitat quality in the Northwestern Coastline of Guinea-Bissau.

The assessment of coastal land use/cover (LULC) change is one of the most precise techniques for detecting spatio-temporal change in the coastal system. This study, integrated Land Change Modeler, Habitat Quality Model, and Digital Shoreline Analysis System, to quantify spacio-temporal coastal LULC change and driving forces between 2000 and 2020. Combined the CA-Markov Model with Sea Level Affecting Marshes Model (SLAMM), merged local SLR data with future representative concentration pathway (RCP8.5) scenarios, and predicted future coastal LULC change and associated sea-level rise (SLR) impact on the coastal land use and habitat quality in short-, medium- and long-term. The study area had significant coastal LULC change between 2000 and 2020. The tidal flats, whose change was driven mainly by sea level, registered a total net gain of 57.93 km2. We also observed the significant loss of developed land whose change was influenced by tidal flat with a total loss of -75.58 km2. The tidal flat will experience a stunning net gain of 80.55 km2 between 2020 and 2060, making developed land the most negatively impacted land in the study area. The study led to the conclusion that the uncontrolled conversion of saltmarshes, mixed-forest, and mangroves into agriculture and infrastructures were the main factors affecting the coastal systems, including the faster coastal erosion and accretion observed during a 20-year period. The study also concluded that a low coastal elevation of -1 m and a slope of less than 2° have contributed to coastal change. Unprecedented changes will unavoidably pose a danger to coastal ecological services, socioeconomic growth, and food security. Timely efforts should be made by establishing sustainable mitigation methods to avoid the future impact.

Grid computing method for atmospheric environmental capacity coupled with ventilation coefficient using CALPUFF simulation and GIS spatial analysis technology.

Atmospheric environmental issues have evolved from point source pollution to regional pollution, leading to controlling specific air pollutant emissions. A-value method has been found suitable for estimating large-scale atmospheric environmental capacity rather than small-scale, resulting in the inaccuracy of developing air pollution control strategy. This study proposed a grid computing method based on the CALPUFF modelling system and GIS spatial analysis tool. The meteorological data from the MM5 model were used to simulate the spatial distribution of air pollutants. The meteorological flow field data was used to simulate the ventilation coefficient. The A value was revised with the simulated to achieve accurate results of atmospheric environment capacity. The credibility was verified by applying this method to Fengtai District, Beijing, China. The research area was divided into small partitions via the ArcGIS spatial analysis tool. The simulation results agreed well with the observation data from actual monitoring stations, even for the PM10 concentration with the most significant error (MRE: 7.05%-13.28%, RMSE: 11.62-17.89, R2: 0.84-0.90). The GIS spatial analysis tools were applied to match the underlying surface types and overcome the restrictions of administrative boundary management. The study proposed four schemes to achieve differentiated air pollutant emission reduction and develop suitable control strategies. Furthermore, this method can be applied on different scales of natural geographic boundaries and realize the precise spatial management of atmospheric environmental capacity.

Teacher Becoming Curriculum Designer: Professional Teaching and Learning in China's Early Childhood Education.

The Curriculum Design Coherence Model (CDC Model) was created as a universal curriculum design method to connect disciplinary knowledge to teachers' expertise in a bid to promote professional teaching and learning. However, research into how the CDC Model has been adopted and localized in the Chinese educational context is scarce. This article focuses on the application and impact of the CDC Model on the resulting teaching practices in China's Early Childhood Education (ECE) settings. The data collected through a focus group discussion with 21 teachers from a model kindergarten at the municipal level in China reveals that the CDC Model has increased the teachers' professionalism by promoting their curriculum initiative, forging curriculum knowledge orientation, strengthening the conceptual structure within the kindergarten-developed curriculum, and enhancing the coordination between the curricula of the different courses offered by the kindergarten. This positive influence has also helped the teachers bridge their disagreement on curriculum content and pedagogy and overcome some difficulties in using the CDC Model. The study has implications for revitalizing the value of disciplinary knowledge and for viewing ECE teachers as active professional agents in ECE curriculum design and teaching.

Pristine PN junction toward atomic layer devices.

In semiconductor manufacturing, PN junction is formed by introducing dopants to activate neighboring electron and hole conductance. To avoid structural distortion and failure, it generally requires the foreign dopants localize in the designated micro-areas. This, however, is challenging due to an inevitable interdiffusion process. Here we report a brand-new junction architecture, called "layer PN junction", that might break through such limit and help redefine the semiconductor device architecture. Different from all existing semiconductors, we find that a variety of van der Waals materials are doping themselves from n- to p-type conductance with an increasing/decreasing layer-number. It means the capability of constructing homogeneous PN junctions in monolayers' dimension/precision, with record high rectification-ratio (>105) and low cut-off current (<1 pA). More importantly, it spawns intriguing functionalities, like gate-switchable-rectification and noise-signal decoupled avalanching. Findings disclosed here might open up a path to develop novel nanodevice applications, where the geometrical size becomes the only critical factor in tuning charge-carrier distribution and thus functionality.

Non-negligible greenhouse gas emissions from non-sewered sanitation systems: A meta-analysis.

Current methods for estimating sanitation emissions underestimate the significance of methane emissions from non-sewered sanitation systems (NSSS), which are prevalent in many countries. NSSS play a vital role in the safe management of fecal sludge, accounting for approximately half of all existing sanitation provisions. We analyzed the distribution of global NSSS and used IPCC accounting methods to estimate the total methane emissions profiles from these systems. Then, we examined the literature to establish the level of uncertainty associated with this accounting estimate. The global methane emissions from NSSS in 2020 was estimated to as 377 (22-1003) Mt CO2e/year or 4.7% (0.3%-12.5%) of global anthropogenic methane emissions, which are comparable to the greenhouse gas (GHG) emissions from wastewater treatment plants. NSSS is the major option for open defecation and is expected to increase by 55 Mt CO2e/year after complete open defecation free. It is time to acknowledge the GHG emissions from the NSSS as a non-negligible source.

Photonic slide rule with metasurfaces.

As an elementary particle, a photon that carries information in frequency, polarization, phase, and amplitude, plays a crucial role in modern science and technology. However, how to retrieve the full information of unknown photons in an ultracompact manner over broad bandwidth remains a challenging task with growing importance. Here, we demonstrate a versatile photonic slide rule based on an all-silicon metasurface that enables us to reconstruct incident photons' frequency and polarization state. The underlying mechanism relies on the coherent interactions of frequency-driven phase diagrams which rotate at various angular velocities within broad bandwidth. The rotation direction and speed are determined by the topological charge and phase dispersion. Specifically, our metasurface leverages both achromatically focusing and azimuthally evolving phases with topological charges +1 and -1 to ensure the confocal annular intensity distributions. The combination of geometric phase and interference holography allows the joint manipulations of two distinct group delay coverages to realize angle-resolved in-pair spots in a transverse manner- a behavior that would disperse along longitudinal direction in conventional implementations. The spin-orbital coupling between the incident photons and vortex phases provides routing for the simultaneous identification of the photons' frequency and circular polarization state through recognizing the spots' locations. Our work provides an analog of the conventional slide rule to flexibly characterize the photons in an ultracompact and multifunctional way and may find applications in integrated optical circuits or pocketable devices.

Enhanced antibacterial behavior of a novel Cu-bearing high-entropy alloy.

Contact infection of bacteria and viruses has been a critical threat to human health. The worldwide outbreak of COVID-19 put forward urgent requirements for the research and development of the self-antibacterial materials, especially the antibacterial alloys. Based on the concept of high-entropy alloys, the present work designed and prepared a novel Co0.4FeCr0.9Cu0.3 antibacterial high-entropy alloy with superior antibacterial properties without intricate or rigorous annealing processes, which outperform the antibacterial stainless steels. The antibacterial tests presented a 99.97% antibacterial rate against Escherichia coli and a 99.96% antibacterial rate against Staphylococcus aureus after 24 h. In contrast, the classic antibacterial copper-bearing stainless steel only performed the 71.50% and 80.84% antibacterial rate, respectively. The results of the reactive oxygen species analysis indicated that the copper ion release and the immediate contact with copper-rich phase had a synergistic effect in enhancing antibacterial properties. Moreover, this alloy exhibited excellent corrosion resistance when compared with the classic antibacterial stainless steels, and the compression test indicated the yield strength of the alloy was 1015 MPa. These findings generate fresh insights into guiding the designs of structure-function-integrated antibacterial alloys.

Monolayer WS2 Lateral Homosuperlattices with Two-dimensional Periodic Localized Photoluminescence.

Homojunctions and homosuperlattices are essential structures and have been widely explored for use in advanced electronic and optoelectronic devices. However, artificially manipulating crystalline phases in two-dimensional (2D) monolayers is still challenging, especially when attempting to engineer lateral homogeneous junctions in a single monolayer of transition metal dichalcogenides (TMDs). Herein, we demonstrate a lateral homosuperlattice (MLHS) with alternating 1T and 2H domains in a 2D WS2 monolayer plane. In MLHSs, the 2H domains, which are laterally localized and isolated by potential wells, manifest junction interfaces and irradiated photoluminescence (PL) with a lateral periodic distribution in the two-dimensional plane. The studies on MLHSs here can provide further understanding of lateral homojunctions and homosuperlattices in a monolayer plane, providing an alternative route to modulate optical and electronic behaviors in TMD monolayers.

Direct observation and manipulation of hot electrons at room temperature.

In modern electronics and optoelectronics, hot electron behaviors are highly concerned, as they determine the performance limit of a device or system, like the associated thermal or power constraint of chips and the Shockley-Queisser limit for solar cell efficiency. To date, however, the manipulation of hot electrons has been mostly based on conceptual interpretations rather than a direct observation. The problem arises from a fundamental fact that energy-differential electrons are mixed up in real-space, making it hard to distinguish them from each other by standard measurements. Here we demonstrate a distinct approach to artificially (spatially) separate hot electrons from cold ones in semiconductor nanowire transistors, which thus offers a unique opportunity to observe and modulate electron occupied state, energy, mobility and even path. Such a process is accomplished through the scanning-photocurrent-microscopy measurements by activating the intervalley-scattering events and 1D charge-neutrality rule. Findings here may provide a new degree of freedom in manipulating non-equilibrium electrons for both electronic and optoelectronic applications.

Controllable Doping in 2D Layered Materials.

For each generation of semiconductors, the issue of doping techniques is always placed at the top of the priority list since it determines whether a material can be used in the electronic and optoelectronic industry or not. When it comes to 2D materials, significant challenges have been found in controllably doping 2D semiconductors into p- or n-type, let alone developing a continuous control of this process. Here, a unique self-modulated doping characteristic in 2D layered materials such as PtSSe, PtS0.8 Se1.2 , PdSe2 , and WSe2 is reported. The varying number of vertically stacked-monolayers is the critical factor for controllably tuning the same material from p-type to intrinsic, and to n-type doping. Importantly, it is found that the thickness-induced lattice deformation makes defects in PtSSe transit from Pt vacancies to anion vacancies based on dynamic and thermodynamic analyses, which leads to p- and n-type conductance, respectively. By thickness-modulated doping, WSe2 diode exhibits a high rectification ratio of 4400 and a large open-circuit voltage of 0.38 V. Meanwhile, the PtSSe detector overcomes the shortcoming of large dark-current in narrow-bandgap optoelectronic devices. All these findings provide a brand-new perspective for fundamental scientific studies and applications.

Slowing Hot-Electron Relaxation in Mix-Phase Nanowires for Hot-Carrier Photovoltaics.

Hot carrier harvest could save 30% energy loss in solar cells. So far, however, it is still unreachable as the photoexcited hot carriers are short-lived, ∼1 ps, determined by a rapid relaxation process, thus invalidating any reprocessing efforts. Here, we propose and demonstrate a feasible route to reserve hot electrons for efficient collection. It is accomplished by an intentional mix of cubic zinc-blend and hexagonal wurtzite phases in III-V semiconductor nanowires. Additional energy levels are then generated above the conduction band minimum, capturing and storing hot electrons before they cool down to the band edges. We also show the superiority of core/shell nanowire (radial heterostructure) in extracting hot electrons. The strategy disclosed here may offer a unique opportunity to modulate hot carriers for efficient solar energy harvest.

[Efficacy and safety of body-insulated acupuncture needle for electrical stimulation at rabbit scia-tic nerve trunk].

OBJECTIVE: To evaluate the efficacy and safety of electrical stimulation at the rabbit sciatic nerve trunk with the body-insulated acupuncture needle whose body is painted with insulating material. METHODS: Eighteen male New Zealand rabbits were randomized into the body-insulated acupuncture needle (BIAN), the general acupuncture needle (GAN), and the blank control groups，with 6 rabbits in each group. The rats'sciatic nerve trunks in BIAN and GAN groups were stimulated by electroacupuncture with the body-insulated acupuncture needle (only allowing the uncoated needle handle and tip to conduct electricity) and the general acupuncture needle, separately. The current intensity was recorded when regular plantarflexion reflexes (sciatic nerve effector reflexes) were observed in the rabbit's foot. The pathological changes of the sciatic nerve at the acupuncture site were observed by H.E. staining, and the ultrastructural changes of the sciatic nerve trunk were observed by transmission electron microscope. RESULTS: The intensity of the current causing the regular plantar flexion reflection in BIAN group (ï¼»0.29±0.07ï¼½ mA) was significantly lower than that in the GAN group(ï¼»0.86±0.08ï¼½ mA, P<0.01). H.E. staining revealed nerve axon degeneration, forming eosinophilic bodies, nerve fiber edema, and focal loss of myelin sheath in the GAN group. While the nerve fiber damage was not obvious, and axons were only degenerated in a few areas in the BIAN group. Transmission electron microscopy observations showed that the nerve myelin sheath structure was separated, the layers were arranged disorderly and bubbled in the GAN group. while the nerve myelin sheath structure of the BIAN group was normal, and it presents a concentric circle-like light and dark lamellar structure, with fewer myelin vacuoles and fissures, only a small part of the mitochondria, microfilaments, and microtubules of the nerve axons were abnormal, and the overall vacuole-like degeneration was significantly reduced, with few of the myelinated fibers were slightly degenerated, and axonal disease was not obvious. CONCLUSION: Insulated acupuncture needle is more accurate and safer than ordinary acupuncture needle for electrical stimulation of rabbit sciatic nerve trunk, and the required electric current intensity is smaller.