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Droughts have been implicated as the main driver behind recent vegetation die‐off and are projected to drive greater mortality under future climate change. Understanding the coupling relationship between vegetation and drought has been of great global interest. Currently, the coupling relationship between vegetation and drought is mainly evaluated by correlation coefficients or regression slopes. However, the optimal drought timescale of vegetation response to drought, as a key indicator reflecting vegetation sensitivity to drought, has largely been ignored. Here, we apply the optimal drought timescale identification method to examine the change in coupling between vegetation and drought over the past three decades (1982–2015) with long‐term satellite‐derived Normalized Difference Vegetation Index and Standardized Precipitation‐Evapotranspiration Index data. We find substantial increasing response of vegetation to drought timescales globally, and the correlation coefficient between vegetation and drought under optimal drought timescale overall declines between 1982 and 2015. This decrease in vegetation–drought coupling is mainly observed in regions with water deficit, although its initial correlation is relatively high. However, vegetation in water‐surplus regions, with low coupling in earlier stages, is prone to show an increasing trend. The observed changes may be driven by the increasing trend of atmospheric CO2. Our findings highlight more pressing drought risk in water‐surplus regions than in water‐deficit regions, which advances our understanding of the long‐term vegetation–drought relationship and provides essential insights for mapping future vegetation sensitivity to drought under changing climate conditions. [ABSTRACT FROM AUTHOR]

Desert expansion can cause tremendous damage to human wellbeing. However, the process of shifting from the non‐desert state to the desert state, a representation of a system regime shift, remains unclear on a global scale. Clarifying the underpinning patterns, predictors and signals of this process is of great value in advancing our understanding of both ecosystem resilience and sustainable development. Here, we combine the climate classification map and long‐term observational land cover data to assess the global desert distribution and its changes from 2000 to 2019. The identified desert areas covered approximately 7.53% of the global land in the past two decades. Only approximately 16.03% of these deserts showed expanding trends, especially in countries such as Tunisia, Tajikistan, and Peru. After assessing 26 climatic, ecological, and socioeconomic factors that could potentially influence desert expansion rates, vegetation cover diversity was identified as the strongest predictor in both hot and cold deserts, followed by cattle density in hot deserts and desert size in cold deserts. In addition, we also found that pronouncedly high fluctuations in vegetation productivity could serve as a possible signal for desert conversion. Our results provide not only a long‐term overview of current global desert changing patterns but also possible guidance for constraining desert expansion. [ABSTRACT FROM AUTHOR]

It is a great challenge to refine precious metals from e‐wastes under mild conditions without hazardous reagents. Herein, black phosphorus (BP) was covalently functionalized with poly(N‐isopropylacrylamide) (PNIPAM) to obtain thermo/near‐infrared (NIR)‐responsive BP−P for precious metal recovery. Precious metals (Au, Ag, and Pd) with higher redox potentials than BP−P could be efficiently recovered by reduction‐driven enrichment. Taking Au as an example, the recovery process presented fast kinetics (<15 min), excellent selectivity, and high efficiency (≈98 %). Remote operation with NIR light could generate heat by BP, which induced the hydrophilic‐to‐hydrophobic transition of PNIPAM, allowing the spontaneous gathering, facile collection, and practical recycle of BP−P following Au extraction. Thanks to the unique features of BP−P, not only could high‐quality Au nanoparticles (20–30 nm) be economically extracted (cost: $0.731–1.222 g−1 Au nanoparticles; 5–6 orders of magnitude lower than the market price), but also the formed BP−P‐Au nanocomposites have potential application in hydrogen evolution reaction. [ABSTRACT FROM AUTHOR]

A photochromic film based on an inorganic‐organic hybrid, Na3H(H2O)2[β‐Mo8O26](C12H8N4O2)2·19H2O (1), is developed for the first time. Compound 1 was in situ synthesized and structurally characterized by single‐crystal X‐ray crystallography, and a dimerization reaction of isoniazid can be directly observed during the synthesis process. Together with the polymolybdate, the azo bond in the dimerization product N,N'‐bis(isonicotinamide) hydrazide showed photochromic properties under illumination, widening the light absorption range of polymolybdate. Irradiation experiments of the prepared film indicated an excellent waterproof and recyclable layered material, which demonstrated a distinctive way of extending the application of polyoxometalate based hybrid inorganic‐organic functional materials in the field of photocatalysis. [ABSTRACT FROM AUTHOR]

Abstract: Climate change has far‐reaching impacts on ecosystems. Recent attempts to quantify such impacts focus on measuring exposure to climate change but largely ignore ecosystem resistance and resilience, which may also affect the vulnerability outcomes. In this study, the relative vulnerability of global terrestrial ecosystems to short‐term climate variability was assessed by simultaneously integrating exposure, sensitivity, and resilience at a high spatial resolution (0.05°). The results show that vulnerable areas are currently distributed primarily in plains. Responses to climate change vary among ecosystems and deserts and xeric shrublands are the most vulnerable biomes. Global vulnerability patterns are determined largely by exposure, while ecosystem sensitivity and resilience may exacerbate or alleviate external climate pressures at local scales; there is a highly significant negative correlation between exposure and sensitivity. Globally, 61.31% of the terrestrial vegetated area is capable of mitigating climate change impacts and those areas are concentrated in polar regions, boreal forests, tropical rainforests, and intact forests. Under current sensitivity and resilience conditions, vulnerable areas are projected to develop in high Northern Hemisphere latitudes in the future. The results suggest that integrating all three aspects of vulnerability (exposure, sensitivity, and resilience) may offer more comprehensive and spatially explicit adaptation strategies to reduce the impacts of climate change on terrestrial ecosystems. [ABSTRACT FROM AUTHOR]

Using first‐principles calculations, the effect of cation vacancies on the electronic structures and optical characters of KSr2Nb5O15 (KSN) lead‐free ferroelectrics are investigated. The calculated dielectric properties are demonstrated by the experimental results. The cation vacancies involve K+ vacancies (KSN‐K), Sr2+ vacancies (KSN‐Sr), and coexisting K+ and Sr2+ vacancies (KSN‐K&Sr). When these cation vacancies exist in KSN, the unit cell volumes decrease, leading to phase transition from tetragonal to orthorhombic, and the cation vacancies show strong effects on the band gap of KSN, declining by 1.46%‐9.46%. The optical properties including the static dielectric constants, refraction, and extinction coefficient of KSN‐K, KSN‐Sr, and KSN‐K&Sr increase more than those of KSN without vacancies, but the reflectivity and loss function decrease. All structures with cation vacancies are mainly refractive in the 0‐4 eV photon energy range and are reflective at 5‐8 eV. The refractivity increases and reflectivity decreases after vacancies occur. KSN‐Sr has the largest static dielectric constant while KSN‐K&Sr has the smallest values. The dielectric constant can be adjusted in the range of 25% by controlling the cation vacancies. The calculated dielectric properties are in good agreement with the experimental results. The results pave the way to regulate the optical and dielectric properties of lead‐free ferroelectrics by controlling different cation vacancies. [ABSTRACT FROM AUTHOR]

Abstract: Isochamaejasmin, neochamaejasmin A and daphnoretin derived from Stellera chamaejasme L. are important because of their reported anticancer properties. In this study, a sensitive UPLC‐MS/MS method for the determination of isochamaejasmin, neochamaejasmin A and daphnoretin in rat plasma was developed. The analyte and IS were separated on an Acquity UPLC HSS T3 column (100 × 2.1 mm, 1.8 μm) using gradient elution with the mobile phase of aqueous solution (methanol–water, 1:99, v/v, containing 1 m m formic acid) and organic solution (methanol–water, 99:1, v/v, containing 1 m m formic acid) at a flow rate of 0.3 mL/min. Multiple reaction monitoring mode with negative electrospray ionization interface was carried out to detect the components. The method was validated in terms of specificity, linearity, accuracy, precision, stability, etc. Excellent linear behavior was observed over the certain concentration ranges with the correlation coefficient values >0.99. Intra‐ and inter‐day precisions (RSD) were <6.7% and accuracy (RE) ranged from −7.0 to 12.0%. The validated method was successfully applied to investigate the pharmacokinetics of three chemical ingredients after oral administration of S. chamaejasme L. extract to rats. [ABSTRACT FROM AUTHOR]

Conductive‐bridging random access memory (CBRAM), dominated by conductive filament (CF) formation/rupture, has received much attention due to its simple structure and outstanding performances for nonvolatile memory, neuromorphic computing, digital logic, and analog circuit. However, the negative‐SET behavior can degrade device reliability and parameter uniformity. And large RESET current increases power consumption for memory applications. By inserting 2D material, molybdenum disulfide (MoS2), for interface engineering with the device configuration of Ag/ZrO2/MoS2/Pt, the negative‐SET behavior is eliminated, and the RESET current is reduced simultaneously. With the ion barrier property of MoS2, the CF can probably not penetrate the MoS2 layer, thus eliminating the negative‐SET behavior. And with the low thermal conductivity of MoS2, the internal temperature of the device would be relatively high at RESET, accelerating probably redox reactions. As a result, the RESET current is reduced by an order of magnitude. This interface engineering opens up a way in improving the resistive switching performances of CBRAM, and can be of great benefit to the potential applications of MoS2 in next‐generation data storage. By the insertion of molybdenum disulfide (MoS2) at the ZrO2/Pt interface, Ag/ZrO2/MoS2/Pt devices show reduced RESET current, and the negative‐SET behavior is eliminated. The reduction of the RESET current probably results from the low thermal conductivity of MoS2. And the elimination of the negative‐SET behavior is probably due to the ion barrier effect of MoS2. [ABSTRACT FROM AUTHOR]