Search

The climactic Los Chocoyos (LCY) eruption from Atitlán caldera (Guatemala) is a key chronostratigraphic marker for the Quaternary period given the extensive distribution of its deposits that reached both the Pacific and Atlantic Oceans. Despite LCY tephra being an important marker horizon, a radioisotopic age for this eruption has remained elusive. Using zircon (U–Th)/He geochronology, we present the first radioisotopically determined eruption age for the LCY of 75 ± 2 ka. Additionally, the youngest zircon crystallization 238U–230Th rim ages in their respective samples constrain eruption age maxima for two other tephra units that erupted from Atitlán caldera, W‐Fall (130 +16/−14 ka) and I‐Fall eruptions (56 +8.2/−7.7 ka), which under‐ and overlie LCY tephra, respectively. Moreover, rim and interior zircon dating and glass chemistry suggest that before eruption silicic magma was stored for >80 kyr, with magma accumulation peaking within ca. 35 kyr before the LCY eruption during which the system may have developed into a vertically zoned magma chamber. Based on an updated distribution of LCY pyroclastic deposits, a new conservatively estimated volume of ~1220 ± 150 km3 is obtained (volcanic explosivity index VEI > 8), which confirms the LCY eruption as the first‐ever recognized supereruption in Central America., Deutsche Forschungsgemeinschaft SCH 2521/6‐1

In this work, a novel approach to rapidly densify ceramic matrix composite was developed by combining ceramic and composite processing. Cf preform, which was injected and impregnated with slurries containing ZrSi2 and phenolic resin, was consolidated by spark plasma sintering at 1550 °C/50 MPa for 5 min. During densification, ZrSi2 and resin carbon converted to ZrC and SiC, newly formed particles were incorporated in the preform preferentially in the fiber randomly orientated layer. Although all the composites exhibit non-brittle fracture manner, their flexural strength and toughness only reach maximum in the sample with a carbon to ZrSi2 molar ratio of 3:1.

The growth of Zn dendrites and self-corrosion reaction during electrochemical cycling is a long-standing issue impeding the practical application of zinc-ion batteries. Although various surface engineering strategies have shown great promise in suppressing zinc dendrites, the protective layers unavoidably hinder Zn2+ diffusion, resulting in increased internal impedance/polarization. Therefore, constructing smart interface protective layers with fast Zn2+ transfer kinetics is highly desirable but remains a key challenge. Here, an Mg-Al layered double hydroxide (LDH)-based artificial solid electrolyte interface (SEI) with Zn-ion diffusion channels is proposed. The well-aligned interlayer channels in the Mg-Al LDH skeleton is proved to efficiently engineer the distribution of Zn2+ ions and facilitate Zn2+ diffusion between the electrode/electrolyte interface, thus giving rise to stable Zn deposition. Moreover, the mechanically robust Mg-Al LDH artificial SEI acts as an interfacial layer to constrain H2O-induced corrosion and hydrogen evolution reaction. Consequently, the Mg-Al LDH artificial SEI improves the Coulombic efficiency to 99.2% for more than 2000 cycles, and an ultralong lifespan of 1400 h has been achieved at 0.5 mA cm−2. Notably, the zinc-ion capacitors by pairing the Zn@LDH anode and high-loading active carbon cathode deliver outstanding cycling stability with a high capacity retention of 93.7% up to 10000 cycles at the high areal current density of 37.5 mA cm−2, portending the feasibility of practical applications.

Sr(Ti0·3Fe0.7)O3-δ (STF) materials with satisfactory stability and no rare-metal elements have attracted increasing research interest as oxygen electrodes of solid oxide electrochemical cells. However, STF-based electrodes are still limited by their modest catalytic activities at low temperatures. This can be improved by A-site deficiency of STF-based materials; however, data related to the influence of A-site deficiency of perovskite-oxide-based materials on sintering behavior and electrochemical performance are still lacking. Herein, porous electrodes with different Srx (Ti0·3Fe0.7)O3-δ compositions (x = 0.85–1) were prepared. The effects of A-site cation deficiency ratios and sintering temperatures on the microstructures and electrochemical performance of the as-obtained STF electrodes were investigated. Electrochemical performance was improved for A-site deficient Srx (Ti0·3Fe0.7)O3-δ. For Sr0·9(Ti0·3Fe0.7)3-δ electrode material sintered at 1050 °C, the lowest polarization resistance measured at 700 °C was ~0.14 Ω⸳cm2 but increased at higher x values. At sintering temperatures above 1050 °C, the sintering diffusion occurred, where the electrolyte diffused through the deficient electrodes to form a dense layer at the electrode/electrolyte interface. On the other hand, although the presence of such diffused dense layer did not have significant effect on the electrochemical performance of the cells, it could be prevented by using lower sintering temperatures (≤1000 °C) to avoid possible negative effects on comprehensive performance. For the electrode obtained at x = 0.9 and sintered at 1000 °C, the overall polarization resistance was recorded as 0.099 Ω⸳cm2 at 700 °C. In sum, these findings look promising for future research.

The structure, surface topography and magnetic properties of LaCoO3 (LCO) thin films deposited epitaxially on the SrTiO3 substrates have been investigated in detail. The LCO thin films show a typical ferromagnetic-paramagnetic (FM-PM) phase transition at 78 K. Based on the measurements of isothermal magnetization around the Curie point, the magnetic entropy change (ΔSM) of LCO thin films under various applied magnetic fields were obtained. By utilizing scaling theory, all of the ΔSM curves can be re-scaled, confirming that the FM-PM phase transition is second-order magnetic phase transition. Moreover, the magnetic entropy change -ΔSM features a maximum around TC, whereas, power law fitting of - Δ S M max with H gives n = 0.9704, which is obviously deviating from the standard value n = 2/3 for the Landau mean field model. This indicates that the mean field theory cannot be used to explain the critical behavior of LCO thin films which implies that the critical behavior of LCO thin films may involve complex magnetic interactions. These interactions are correlated with a long-term puzzling finding in this system why its Curie point is always around 80 K regardless of the different fabrication methods and conditions used in the film growth.

Transparent laser ceramics are the attractive gain medium for solid-state lasers. However, they have not been applied to the fiber lasers due to the difficulty of forming green fibers by traditional methods. In this study, a novel route combined aqueous gelcasting with capillary glass tube was designed to prepare Yb:YAG transparent ceramic fiber with a diameter of 1.0 mm and 43.0 mm in length for the first time. The slurry with high solid loading and low viscosity was smartly inhaled into the capillary glass tube to conquer the difficulty of casting. The green fibers without cracks and deformation had highly dense microstructure. The in-line transmittance of highly doped 15.0 at.% Yb:YAG transparent ceramic disc prepared from the same preparation conditions of Yb:YAG ceramic fiber was 80.0 % at 1064 nm. This study provides a novel route to prepare transparent ceramic fiber differing from extrusion processing, promoting the development of fiber laser.

Ti3C2 is the first member of two-dimensional (2D) transition metal carbide or carbonitride (MXene) with excellent photothermal effect in disease treatment on an animal model, which shows a potential prospect on clinical application. However, in-depth details on the biosafety of MXene were insufficient. Metabolomics approach has offered an excellent alternative with numerous bioinformation, which can demonstrate the response of an organism to external stimuli at the molecular level. In this study, two different concentrations (100 and 500 mg/L) of MXene were used to treat human umbilical vein endothelial cells (HUVECs), and under both conditions, no obvious acute cytotoxicity was observed by cell proliferation and apoptosis measurement. We used a platform combining LC-MS/MS, GC-MS, and bioinformatics to analyze the changes of HUVECs metabolome after treatment with different concentrations of MXene, and the results indicated that —high concentrations (500 mg/L) of MXene can cause significant changes in the energy metabolism of HUVECs, showing obvious inhibition of tricarboxylic acid (TCA) cycle with the enhancement of glycolysis, fatty acid biosynthesis, and lipid accumulation, which are closely related to the functional disorder of mitochondria. The metabolomics results of the novel MXene-cell system extend the knowledge on the biological effect of MXene, possibly enabling technological innovations and material modifications.

Due to the low chemical activity and large detonation cell size, methane-air continuous rotating detonation (CRD) is hard to be realized in a traditional small annular chamber without extra additives. In order to investigate the characteristics of methane-air CRD wave in a small chamber, three hollow chambers with Laval nozzles are adopted in this research. The methane-air CRD can be realized in a quite small chamber (diameter of 80 mm) under very particular condition. The operating range enlarges with the increase of chamber diameter. The CRD wave propagation frequencies vary apparently with chamber diameter while the propagation velocities stay in a quite narrow range of 1744–1812 m/s, and the relative deviation is within 4%. The CRD wave propagation process is very stable, and the propagation velocity accounts for 99% of the theoretical C-J velocity in the chosen test. Optical observation results illustrate that the reduction in chamber diameter or increase in nozzle contraction ratio will lead to CRD deterioration. By comparing the frequencies of high-frequency pressure and optical observations, the coupling of inducing shock wave and combustion flame is proved quantitatively.

The geodynamic process from the evolution of supercontinent has distinct isotope characteristics explorable using zircon Hf isotopic composition. Since Peninsular Malaysia associates with Gondwana dispersal and Pangaea formation, analyzing the U-Pb and Hf-isotopic content of its 500–200 Ma magmatic zircon could reveal the signal left by the transitional geodynamic process between the supercontinents. We collected two groups of magmatic rocks from West Malaya: Ordovician meta-volcanics (n = 8), and Triassic Main Range granitoid province (MRGP) (n = 6); and three groups from East Malaya: Carboniferous meta-volcanics (n = 2), Permian-Triassic Eastern granite province (EGP) (n = 6), and Permian-Triassic EGP volcanics (n = 8). Difference in magmatic zircon Hf isotopic crustal model ages uphold the previous rationale which separates Peninsular into two blocks: West Malaya (part of Sibumasu terrane) magmatic zircon Hf isotopic crustal model ages (Average TDM2: 1.3 Ga) are older than East Malaya (part of Chanthaburi-Sukhothai-Lincang arc of Indochina terrane) (Average TDM2: 0.9 Ga). During the final assembly of Gondwana from 500 to 450 Ma, West Malaya and East Malaya were at the outboard of Gondwana Proto-Tethys margin. The shift of East Malaya zircon Hf array towards higher eHf(t) (external orogenic system) after ca.370 Ma may infers Paleo-Tethys ocean broadening and East Malaya separation from Gondwana. The 370–350 Ma juvenile zircon Hf isotopic composition in East Malaya is a significant improvement over radiolarian age to show the broadening and subduction of the Paleo-Tethys ocean between the two terranes. After ca.280 Ma, East Malaya zircon Hf array shifted towards lower eHf(t) (internal orogenic system). Coinciding with the Indosinian collision at ca.230 Ma, crustal reworking signal increases in both blocks, signifying the end in Peninsular Malaysia Gondwana to Pangaea transitional geodynamic process. As the Paleo-Tethys segment was completely subducted after 230 Ma, the peninsular crustal thickening starts from 230 to 218 Ma. The post-collision phase would begin at ca.215 Ma.

Two new supramolecular polyoxmetalates were synthesized from 1, 4-bis[4-nitrile-pyridine)-N-methylene]phenyldibromide (L1) and 1, 2-bis[4-nitrile-pyridine)-N-methylene]phenyldibromide (L2) and (NH4)6Mo7–O24·4H2O under hydrothermal conditions. They are named p-[C20H18N2O4][Mo8O26] 0.5·H2O (1) and o-[C20H18N2O4][Mo8O26] ċ 0.5·H2O (2) respectively. The structures have been confirmed through single-crystal X-ray diffraction analyses and further characterized by elemental analyses, IR spectra. The adsorption test of compound 1 and compound 2 in organic dyes were carried out. It was found that compound 1 had a good adsorption effect on methylene blue (MB) and rhodamine B (RhB). The adsorption effect of compound 2 on MB is stronger than that of compound 1.

In order to realize the resource and sustainable utilization of quartz sand waste discarded from the mineral processing, Mg2+-doped cobalt blue composite pigments are prepared based on quartz sand via co-precipitation method followed by high-temperature crystallization. The obtained composite pigments are characterized by X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy and magic angle spinning nuclear magnetic resonance. The results indicate that the incorporation of Mg2+ ion and quartz sand improves the color properties and decreases the production cost of composite pigments, and the color can be facilely adjusted by controlling the added amount of Mg2+. The optimal color properties are obtained as the molar ratio of Mg2+ to Co2+ is 6:4, and Mg2+ enters into the crystal lattice and occupies the tetrahedral sites of spinel cobalt blue. Therefore, this study is expected to develop feasible approach for the resource and sustainable utilization of quartz sand waste, and fabrication of low-cost bright cobalt blue composite pigments as well.

Active Lamb wave detection is an effective and simple monitoring method for structural health monitoring (SHM). Piezoelectric lead zirconate titanate (PZT) ceramics are most commonly used as transducers to excite and receive Lamb wave. However, due to their hardness, thickness and brittleness, PZT ceramics are severely limited in detecting damage on curved surface structures. Herein, we report that flexible PZT film sensor is an excellent candidate for receiving Lamb wave used in Lamb wave-based SHM of aircraft. An improved piezoelectric coefficient d33 (~130 pm V−1) is obtained in epitaxial PZT films grown on flexible inorganic mica substrates via van der Waals heteroepitaxy. Superior stable ferroelectricity and piezoelectricity retain in flexible PZT film after bending 104 cycles under a radius of 8 mm. As proven by experiment and simulation, flexible PZT film is demonstrated as an ultrasonic sensor with high sensitivity to be bonded on the curved aluminum plate for Lamb wave-based damage monitoring. Our work demonstrates that flexible PZT films have enormous potential for real-time light-weight and high-sensitivity receiver sensors for the SHM of aging aircraft.

The radionuclide, beryllium-7 (7Be) has been widely used as a nuclear trace element to study surface soil particle migration and identify sediment sources in short-term processes. In this study, we measured 7Be concentration in vegetation and its interception (7Be deposition intercepted by vegetation) and absorption from the atmosphere on the slopes of the Yangtze river delta. We report the concentrations of 7Be were highest in dry plants and lower in cultivated crops. 7Be interception amounts varied greatly among different plant species, with an average interception ratio of 7Be plant inventories to soil deposition of 13 ± 8%. There is a significant positive correlation between biomass and 7Be interception in natural and wild plants. The depositional 7Be was redistributed by the covering vegetation. This study provides an important basis for using 7Be as a tracer for soil erosion under vegetation cover.

Although metal silicates are considered as the promising electrode materials for lithium-ion batteries, metal silicate-based materials suffer from inadequate cycling performance and dimensional unreliability evoked by the large volume changes during cycling, which hinders their practical applications. In principle, the poor electrochemical kinetics during the redox reactions of metal silicates is originated from the instinct structure. Hence, the precise and delicate ability to construct hetero-layers to tailor intercalation reaction remains elusive. Herein, a facile strategy of designing and constructing heterostructure in a cobalt-copper silicates nano-architecture (CNT@CoCuSiOx) with synergistic interaction between cobalt silicate (Co2SiO4) with copper silicate (CuSiO3) on the surface of carbon nanotubes (CNTs). Moreover, Co2SiO4/CuSiO3 heterojunction with unbalanced charge distributions that rooted from in-situ generation on CNTs by a facile one-step hydrothermal process, can efficiently tailor the electrochemical activities of Cu3+/Cu2+ and Co3+/Co2+ redox reactions by elevating transfer of electrons and delivering the heterointerface effect. The tough and conductive nanostructure of CNTs basement facilitate the ion diffusion and improve the rate capability. The heterostructure-incorporated CNT@CoCuSiOx-(2/1) exhibits not only outstanding electrochemical capacity (545 mAh g−1 at 0.1 A g−1), superior ion/electron transmission efficiency but also robust cycling performance (516 mAh g−1 after 900 cycles at 0.5 A g−1 and an excellent capacity retention rate of 95%). Beyond energy storage, our delicate methodology in manipulating the electrochemical behavior of metal silicates opens up a critical insight into rational fabrication of next-generation anodes for lithium-ion battery.

Enabling materials with distinct features toward achieving high-performance energy storage devices is of huge importance but highly challenging. Commercial carbon cloth (CC), because of its appealing chemical and mechanical properties, has been proven to be an excellent conductive substrate for active electrode materials. However, its performance is notably poor when directly used as an electrode in energy storage, due to its low theoretical capacity and surface area. Herein, we successfully endow the CC with enhanced storage capacity via formation of a π-π stacking interaction by integrating electrochemically activated CC (denoted CC/ACC) with biomass-derived carbon (BMDC) (denoted π-CC/ECC@BMDC). The π-CC/ECC@BMDC electrode displays excellent storage performance with a high capacity of 2.53 mAh cm-2 under 0.2 mA cm-2 when used as anode material for lithium ion batteries (LIBs). Due to the induction energy, the negatively charged molecules of the CC/ACC functional groups interact with the BMDC during carbonization, creating the π-π stacking interaction. Based on first-principles calculations, the structural design of the tri-layer carbon enables the movement of electrons around the π-π stacking interaction, which significantly facilitates rapid transportation of electrons, creates three-dimensional (3D) ion tunnels for fast transportation of ions, and improves the electrode's mechanical and electronic properties.

Late Mesozoic igneous rocks are important for deciphering the Mesozoic tectonic setting of NE China. In this paper, we present whole-rock geochemical data, zircon U–Pb ages and Lu–Hf isotope data for Early Cretaceous volcanic rocks from the Tulihe area of the northern Great Xing’an Range (GXR), with the aim of evaluating the petrogenesis and genetic relationships of these rocks, inferring crust–mantle interactions and better constraining extension-related geodynamic processes in the GXR. Zircon U–Pb ages indicate that the rhyolites and trachytic volcanic rocks formed during late Early Cretaceous time (c. 130–126 Ma). Geochemically, the highly fractionated I-type rhyolites exhibit high-K calc-alkaline, metaluminous to weakly peraluminous characteristics. They are enriched in light rare earth elements (LREEs) and large-ion lithophile elements (LILEs) but depleted in high-field-strength elements (HFSEs), with their magmatic zircons ϵHf(t) values ranging from +4.1 to +9.0. These features suggest that the rhyolites were derived from the partial melting of a dominantly juvenile, K-rich basaltic lower crust. The trachytic volcanic rocks are high-K calc-alkaline series and exhibit metaluminous characteristics. They have a wide range of zircon ϵHf(t) values (−17.8 to +12.9), indicating that these trachytic volcanic rocks originated from a dominantly lithospheric-mantle source with the involvement of asthenospheric mantle materials, and subsequently underwent extensive assimilation and fractional crystallization processes. Combining our results and the spatiotemporal migration of the late Early Cretaceous magmatic events, we propose that intense Early Cretaceous crust–mantle interaction took place within the northern GXR, and possibly the whole of NE China, and that it was related to the upwelling of asthenospheric mantle induced by rollback of the Palaeo-Pacific flat-subducting slab.

Due to creating a passivated solid electrolyte interphase (SEI), high concentration (HC) electrolytes demonstrate peculiar physicochemical properties and outstanding electrochemical performance. However, the structures of such SEI remains far from clear. In this work, a hybrid abinitio and reactive molecular dynamics (HAIR) scheme is employed to investigate the concentration effect of SEI formation by simulating the reductive degradation reactions of lithium bis(fluorosulfonyl)imide (LiFSI) in 1,3 dioxalane (DOL) electrolytes at concentrations of 1 M, 4 M, and 10 M. The efficient HAIR scheme allows the simulations to reach 1 ns to predict electrolytes’ deep products at different concentrations. The simulation findings show that the most critical distinction between HC and its low concentration (LC) analogue is that anion decomposition in HC is much more incomplete when only S–F breaking is observed. These insights are important for the future development of advanced electrolytes by rational design of electrolytes.

The migration of arc magmatism that is a fundamental aspect of plate tectonics may reflect the complex interaction between subduction zone processes and regional tectonics. Here we report new observations on volcanic migration from northwestern Sumatra, in the westernmost Sunda arc, characterized by an oblique convergent boundary between the Indo-Australian and Eurasian plates. Our study indicates that in northwestern Sumatra, volcanism ceased at 15–10 Ma on the southern coast and reignited to form a suite of active volcanoes that erupt exclusively to the north of the trench-parallel Sumatran fault. Younger volcanic rocks from the north are markedly more enriched in K2O and other highly incompatible elements, delineating a geochemical variation over space and time similar to that in Java and reflecting an increase in the Benioff zone depth. We relate this mid-Miocene volcanic migration in northwestern Sumatra to the far-field effect of propagating extrusion tectonics driven by the India-Eurasia collision. The extrusion caused regional deformation southward through Myanmar to northwestern Sumatra and thus transformed the oblique subduction into a dextral motion–governed plate boundary. This tectonic transformation, associated with opening of the Andaman Sea, is suggested to be responsible for the volcanic migration in northwestern Sumatra.

Global warming poses a serious threat to crops. Calcium-dependent protein kinases (CDPKs)/CPKs play vital roles in plant stress responses, but their exact roles in plant thermotolerance remains elusive. Here, we explored the roles of heat-induced ZmCDPK7 in thermotolerance in maize. ZmCDPK7-overexpressing maize plants displayed higher thermotolerance, photosynthetic rates, and antioxidant enzyme activity but lower H2 O2 and malondialdehyde (MDA) contents than wild-type plants under heat stress. ZmCDPK7-knockdown plants displayed the opposite patterns. ZmCDPK7 is attached to the plasma membrane but can translocate to the cytosol under heat stress. ZmCDPK7 interacts with the small heat shock protein sHSP17.4, phosphorylates sHSP17.4 at Ser-44 and the respiratory burst oxidase homolog RBOHB at Ser-99, and upregulates their expression. Site-directed mutagenesis of sHSP17.4 to generate a Ser-44-Ala substitution reduced ZmCDPK7's enhancement of catalase activity but enhanced ZmCDPK7's suppression of MDA accumulation in heat-stressed maize protoplasts. sHSP17.4, ZmCDPK7, and RBOHB were less strongly upregulated in response to heat stress in the abscisic acid-deficient mutant vp5 versus the wild type. Pretreatment with an RBOH inhibitor suppressed sHSP17.4 and ZmCDPK7 expression. Therefore, abscisic acid-induced ZmCDPK7 functions both upstream and downstream of RBOH and participates in thermotolerance in maize by mediating the phosphorylation of sHSP17.4, which might be essential for its chaperone function.

Aerosol pollution is a significant threat to public health, and ground-based lidar can effectively monitor air pollution and regional air quality, including providing accurate observations of the vertical distribution of aerosols. Two long-distance trans-boundary aerosol episodes (named P2 and P5; P2 was the heavy pollution period (from 19:00 on January 19 to 15:00 on January 20) and P5 was the moderate pollution period (from 03:00 on January 25 to 21:00 on January 25)) occurred in the western Yangtze River Delta region, China during 17–26 January 2019, causing significant PM2.5 pollution. The ground-based lidar average value of the aerosol extinction coefficient below 0.5 km was highly correlated with surface PM2.5 concentration, and the correlation coefficient was 0.89. The regression relationship between the planetary boundary layer (PBL) height and PM2.5 concentration value was significantly exponential with a correlation coefficient of −0.59. The PBL height during P2 and P5 was below 0.5 km, relative to other periods with PBL height ranging from 0.5 to 2.0 km. Based on the backward trajectory and weather pattern analysis and surface PM2.5 observations, aerosols during P2 and P5 were mainly contributed by transported PM2.5 blown from northern China during the winter monsoon. The depolarization ratios derived from the lidar data show that the persistent pollution episode was mainly caused by strong mixing of transported and local aerosols. Relative to the P2 period, the wind speed in the P5 period was relatively strong, so transmission and diffusion took place relatively quickly and the duration of the pollution process was shorter. Our findings provide scientific evidence that transboundary air pollution were closely associated with different weather conditions and mixed aerosol sources, particularly for various PBL heights.

In this study, new geological, geochronological, geochemical, and Nd–Hf isotopic data are presented for the Melange Zone within the Zavkhan terrane, Mongolia, and the terrane structure, early Neoproterozoic continental crust growth, and microcontinent formation in the north–central part of the Central Asian Orogenic Belt (CAOB) are discussed. The Melange Zone separates high-grade complexes of the northwestern part of the Zavkhan terrane and unmetamorphosed Neoproterozoic Zavkhan Formation covered by Cryogenian–Cambrian shelf deposits of the southwestern part. Zone consist of a lower-grade association of basalts, basaltic andesites, rarely felsic volcanic rocks, trondhjemites of the Kharuul Massif and variably metamorphosed from greenschist- to upper amphibolite-facies, and high-grade metamorphic rocks including quartzite–gneisses, hornblende schists, and amphibolites with relics of eclogite and blueschist-facies metamorphism assemblages. Emplacement of trondhjemites and gabbro dykes of the Kharuul Massif occurred at about 960–930 Ma. Geochemical, Nd whole-rock, and Hf-in-zircon isotopic data indicate an oceanic island arc setting for the lower-grade association. LA-ICP-MS dating and Hf-in-zircon data for detrital zircons from the quartzite–gneisses of the Melange Zone indicate that the sources comprise Palaeoproterozoic (ca. 2.02 and 2.48 Ga), Neoarchean (ca. 2.59 and 2.67 Ga), and Mesoarchean (ca. 2.8 and 3.0 Ga) magmatic and metamorphic crustal rocks as well as 2.6–2.5 Ga juvenile complexes. High-grade amphibolites show geochemical similarity to continental arc and within-plate basalts, and were formed from enriched mantle sources. Obtained combined with published data demonstrate that the Zavkhan terrane represents composite terrane composed of ca. 960–930 Ma island arc complex, and ca. 860–800 Ma active continental margin complexes in the north and reworked at ca. 800–720 Ma early Precambrian continental crust in the south, which are separated by a Melange Zone. We speculate that formation of the latest Mesoproterozoic–early Neoproterozoic island arc and active continental margin complexes in the north–central CAOB could be related to the assembly of the Rodinia supercontinent at ca. 1.1–1.0 Ga, which initiated subduction in Mirovian Ocean and led to the development of accretionary orogens around supercontinent margins.

There is a broad consensus that subduction of the Paleo-Pacific oceanic plate has caused extensive magmatism, lithospheric deformation, and metal mineralization in the eastern margin of the Eurasia...

As an important functional thin-film material in the field of electronic information, high-purity titanium (Ti) is widely used in different industries, such as integrated circuits, flat-panel displays and solar energy, indicating the importance of further research on Ti targets. Herein, a titanium target is placed in a UDP-650 closed-field nonequilibrium magnetron sputtering ion coating machine for deep etching to form racetrack grooves, and different positions of etching grooves are analyzed to understand the target etched behavior. The sputtering-induced etching of the Ti target, from shallow to deep regions, changes from the preferential sputtering of scratches and other defects in the edge area to the surface sputtering pits, with discontinuous distribution and uneven size, to grain boundary sputtering and, finally, to closely packed grain surface sputtering. The etching behavior of different regions exhibits different characteristics, mainly showing selective sputtering. The surface roughness of the sputtered area initially increases with the increase of sputtering depth and plasma density, followed by a slight decrease. Moreover, different degrees of incomplete recrystallization occur in different sputtering areas due to the uneven distribution of plasma on the target surface. The grain size increased from the transition area between sputtering and non-sputtering (112 μm) to the deepest sputtering area (139 μm). Moreover, the relationship between the cross-sectional grain size and sputter surface roughness renders a correlation coefficient of 0.802, indicating a strong influence of grain size on surface roughness. Therefore, it is of utmost importance to refine grains and increase the sputtering yield of the target as well as reduce the surface roughness of the target after etching to obtain a high-quality thin film.

A finite element model of temperature field for plasma spraying preset MCrAlY coating during laser cladding was constructed using ANSYS parametric design language (APDL) in accordance to characteristics of preset laser cladding. Influencing laws of laser cladding parameters on temperature field were analyzed. Results show that laser power influences temperature field of cladding samples more than laser scanning speed. Experimental results agree well with simulation results, which prove the accuracy and reliability of the constructed calculation model of temperature field. Heating and cooling laws in the laser cladding process could be mastered through this calculation model. Research conclusions provide some references to optimization parameters in preparing high-performance laser cladding coatings.

Probabilistic Fault Recoverability (FR) property reveals the capability of a system to accommodate faults under admissible input energy constraints in the sense of satisfactory probability. Motivated by the idea of probabilistic control methods, a class of admissible probability density functions is designed for detailed description of fault parameters, under which several probabilistic FR conditions are established. This significantly enlarges the range of recoverable faults obtained from the deterministic FR analysis. The tradeoffs between the risk of performance degradation and this increased recoverability margin are exactly achieved by allowing a small risk of FR violation. This paper analyzes the probability FR of dynamic systems with switching and interconnection characteristics, and applies the new results to several aircraft models including single longitudinal aircraft dynamic, Highly Maneuverable Technology (HiMAT) vehicle and meta aircraft. Simulation results show the efficiency of the proposed methods based on the comparison between deterministic and probabilistic cases.

Helicopters are widely used in maritime Search and Rescue (SAR) missions. To ensure the success of SAR missions, search areas need to be carefully planned. With the development of computer technology and weather forecast technology, the survivors’ drift trajectories can be predicted more precisely, which strongly supports the planning of search areas for the rescue helicopter. However, the methods used to determine the search area based on the predicted drift trajectories are mainly derived from the continuous expansion of the area with the highest Probability of Containment (POC), which may lead to local optimal solutions and a decrease in the Probability of Success (POS), especially when there are several subareas with a high POC. To address this problem, this paper proposes a method based on a Minimum Bounding Rectangle and K-means clustering (MBRK). A silhouette coefficient is adopted to analyze the distribution of the survivors’ probable locations, which are divided into multiple clusters with K-means clustering. Then, probability maps are generated based on the minimum bounding rectangle of each cluster. By adding or subtracting one row or column of cells or shifting the planned search area, 12 search methods are used to generate the optimal search area starting from the cell with the highest POC in each probability map. Taking a real case as an example, the simulation experiment results show that the POS values obtained by the MBRK method are higher than those obtained by other methods, which proves that the MBRK method can effectively support the planning of search areas and that K-means clustering improves the POS of search plans.

The high energy density and suitable operating voltage make rechargeable lithium ion batteries (LIBs) promising candidates to replace such conventional energy storage devices as nonrechargeable batteries. However, the large-scale commercialization of LIBs is impeded significantly by the degradation of the electrolyte, which reacts with the highly reactive lithium metal anode. Future improvement of the battery performance requires a knowledge of the reaction mechanism that is responsible for the degradation and formation of the solid-electrolyte interphase (SEI). In this work, we develop a hybrid computational scheme, Hybrid ab initio molecular dynamics combined with reactive force fields, denoted HAIR, to accelerate Quantum Mechanics-based reaction dynamics (QM-MD or AIMD, for ab initio RD) simulations. The HAIR scheme extends the time scale accessible to AIMD by a factor of 10 times through interspersing reactive force field (ReaxFF) simulations between the AIMD parts. This enables simulations of the initial chemical reactions of SEI formation, which may take 1 ns, far too long for AIMD. We apply the HAIR method to the bis(trifluoromethanesulfonyl)imide (TFSI) electrolyte in 1,3-dioxolane (DOL) solvent at the Li metal electrode, demonstrating that HAIR reproduces the initial reactions of the electrolyte (decomposition of TFSI) previously observed in AIMD simulation while also capturing solvent reactions (DOL) that initiate by ring-opening to form such stable products as CO, CH2O, and C2H4, as observed experimentally. These results demonstrate that the HAIR scheme can significantly increase the time scale for reactive MD simulations while retaining the accuracy of AIMD simulations. This enables a full atomistic description of the formation and evolution of SEI.

Bifunctional hydrogen electrocatalysis (hydrogen-oxidation and hydrogen-evolution reactions) in alkaline solution is desirable but challenging. Among all available electrocatalysts, Ni-based materials are the only non-precious-metal-based candidates for alkaline hydrogen oxidation, but they generally suffer from low activity. Here, we demonstrate that properly alloying Ni with Mo could significantly promote its electrocatalytic performance. Ni4 Mo alloy nanoparticles are prepared from the reduction of molybdate-intercalated Ni(OH)2 nanosheets. The final product exhibits an apparent hydrogen-oxidation activity exceeding that of the Pt benchmark and a record-high mass-specific kinetic current of 79 A g-1 at an overpotential of 50 mV. A superior hydrogen-evolution performance is also measured in alkaline solution. These experimental data are rationalized by our theoretical simulations, which show that alloying Ni with Mo significantly weakens its hydrogen adsorption, improves the hydroxyl adsorption and decreases the reaction barrier for water formation.

Radical S-adenosyl-l-methionine (SAM) enzymes initiate biological radical reactions with the 5’-deoxyadenosyl radical (5’-dAdo•). A [4Fe-4S](+) cluster reductively cleaves SAM to form the Ω organometallic intermediate in which the 5’-deoxyadenosyl moiety is directly bound to the unique iron of the [4Fe-4S] cluster, with subsequent liberation of 5’-dAdo•. Here we present synthesis of the SAM analog S-adenosyl-l-ethionine (SAE) and show SAE is a mechanistically-equivalent SAM-alternative for HydG, both supporting enzymatic turnover of substrate tyrosine and forming the organometallic intermediate Ω. Photolysis of SAE bound to HydG forms an ethyl radical trapped in the active site. The ethyl radical withstands prolonged storage at 77 K and its EPR signal is only partially lost upon annealing at 100 K, making it significantly less reactive than the methyl radical formed by SAM photolysis. Upon annealing above 77K, the ethyl radical adds to the [4Fe-4S](2+) cluster, generating an ethyl-[4Fe-4S](3+) organometallic species termed Ω(E).

Developing advanced electrocatalysts to convert CO2 into liquid fuels such as ethanol is critical for utilizing intermittent renewable energy. The formation of ethanol, however, is generally less f...

Semiconductor photocatalysis technology is a promising method to solve the antibiotics pollution in water. Herein, a series of Sn-doped In2.77S4 (Sn-In2.77S4) hybrid photocatalysts for tetracycline degradation have been fabricated via a one-step hydrothermal process. The analytic results exhibit that doping Sn can improve the photocatalytic performance of In2.77S4 nanosheets under the visible light illumination and the doping amount obviously affects the photocatalytic performance of the samples. When the theoretical molar ratio of Sn4+ to In3+ is 0.04:1 (4%), the photocatalytic efficiency of the Sn-In2.77S4 photocatalyst exhibits the highest of 87.4% in comparison with 39.2% of pure In2.77S4 in 20 min. Moreover, its band gap energy has been reduced to 1.56 eV from 1.75 eV and the light absorption range has been broadened. The transfer rate and separation efficiency of photo-generated electron and hole pairs of the samples have also been enhanced. In addition, the holes play a leading role in the photocatalytic degradation process.

Phase Two of the Integrative Monsoon Frontal Rainfall Experiment (IMFRE-II) was conducted over the middle and lower reaches of the Yangtze River during the period 16 June to 19 July 2020. This paper provides a brief overview of the IMFRE-II field campaign, including the multiple ground-based remote sensors, aircraft probes, and their corresponding measurements during the 2020 mei-yu period, as well as how to use these numerous datasets to answer scientific questions. The highlights of IMFRE-II are: (1) to the best of our knowledge, IMFRE-II is the first field campaign in China to use ground-based, airborne, and spaceborne platforms to conduct comprehensive observations over the middle and lower reaches of the Yangtze River; and (2) seven aircraft flights were successfully carried out, and the spectra of ice particles, cloud droplets, and raindrops at different altitudes were obtained. These in-situ measurements will provide a “cloud truth” to validate the ground-based and satellite-retrieved cloud and precipitation properties and quantitatively estimate their retrieval uncertainties. They are also crucial for the development of a warm (and/or cold) rain conceptual model in order to better understand the cloud-to-rain conversion and accretion processes in mei-yu precipitation events. Through an integrative analysis of ground-based, aircraft, and satellite observations and model simulations, we can significantly improve our cloud and precipitation retrieval algorithms, investigate the microphysical properties of cloud and precipitation, understand in-depth the formation and dissipation mechanisms of mei-yu frontal systems, and improve cloud microphysics parameterization schemes and model simulations.

Seawater oxygen evolution is one of the promising energy conversion technologies for large-scale renewable energy storage. It requires efficient catalysts to accelerate the oxygen evolution reactio...

This study explored the effect of diamond content (0, 0.3, 0.6, and 0.9 wt%) onTi(C0.5,N0.5)-based cermets prepared via vacuum sintering with respect to their final mechanical properties and microstructures, characterized using X-ray diffractionand scanning electron microscopy. After liquid phase sintering, all cermets exhibited a ‘black core/grey rim'and partial ‘white core/grey rim'structure. The cermet with 0.6 wt% diamond exhibited optimal mechanical properties with a Vickers hardness of 1795 ± 32 H V, transverse rupture strength of 2026 ± 45 MPa, and plane strain fracture toughness of 12.95 ± 0.3 MPa m1/2. This is due to grain refinement and the uniformly distributed ‘white core/grey rim'grains. During the incipient liquid formation stage,a higher carbon activity arising due to diamond graphitization may shift the equilibrium towards the product, thereby yielding additional white cores due to the consumption of heavy elements in the binder. Excessive diamond introduction inhibited the dissolution of Ti(C0.5,N0.5) into the binder, resulting in fewer white cores.

Perovskite transition metal oxides with ABO3 structure are considered as potential alternative non-precious metal electrocatalysts for designing highly active and durable electrocatalysis for the oxygen evolution reaction (OER). Herein, we successfully enable LaFeO3 coated on nickel foam (denoted LFO@NF) perovskite with impressive OER activity by systematically tailoring the Fe cation sites and the introduction of oxygen vacancies. The cationic site involves dual cation modulation with Cr and Mo, which creates lattice distortions inducing strong electronic interaction, while the anionic site entails reduction via a hydrogen-treatment process, creating oxygen vacancy sites to improve the electronic conductivity of the perovskite oxide. As a result, the optimized LFO-based catalyst, specifically hydrogenated LaFe0.75Cr0.15Mo0.10O3-coated on the nickel foam (denoted H-LFCMO@NF), requires the lowest overpotential of 263 mV at 10 mA cm−2, and has superior kinetics and excellent stability, which are superior to its counterparts. Theoretical analysis also confirmed that the tailoring of the LFO@NF perovskite leads to an increase in the exposure of active sites, optimization of the adsorption energy of reaction intermediates and enhanced electronic conductivity. This work may provide a promising concept to enhance the performance of LFO-based perovskite electrocatalysts for alkaline OER and beyond.

The critical behavior of single phase Y2Fe17 melt-spun ribbons with the Th2Fe17-type crystal structure has been studied around the transition temperature (TC). This alloy undergoes a second-order ferromagnetic (FM)–paramagnetic (PM) phase transition at TC = 301 K. Various techniques, such as the modified Arrott plot, Kouvel–Fisher method, and critical isotherm analysis, were used to determine the critical exponents that were found to be β = 0.226(3), γ = 1.296(2), and δ = 6.804(5). The universality class of the critical phenomenon in the Y2Fe17 ribbons can be explained with the help of the renormalization group theory approach, in which the magnetic properties show a feature changing from three (3D)- to two-dimensional (2D) Ising model. The first-principles calculations based on density functional theory qualitatively explain the experimental results, confirming the strong correlation between lattice atoms and critical behavior in magnetic intermetallic Y2Fe17.

Facilitated transport membranes, with a uniform distribution of facilitated transport carriers, are highly desirable to reduce the separation energy barrier. Nevertheless, the disordered and random assembly of membrane building materials/blocks makes it hard to obtain the controlled uniform distribution of carriers within membranes. Covalent organic frameworks (COFs), equipped with a regular structure and tailored functionality, provide a favorable platform for the uniform distribution of carriers. Herein, we report an ion-exchange strategy to achieve a uniform distribution of facilitated transport carriers within a cationic COF membrane for efficient carbon capture. With the assistance of a small amount of flexible graphene oxide (GO), the potential defects between the junctions of cationic COF nanosheets were eliminated, and ultrathin (20–60 nm), defect-free COF membranes were obtained. By synergistically intensifying the diffusion selective and facilitated transport mechanisms within membranes, the optimized COF membrane exhibits a CO2 permeance of 164.2 GPU with a CO2/CH4 selectivity of 27, both of which exceed those of pure COF membranes in most literature studies. Our findings may stimulate further research on functionalized COF membranes and other kinds of organic framework membranes with uniformly distributed carriers for molecule separation.

Bismuth vanadate (BiVO4) is one of the most fascinating building blocks for the design and assembly of highly efficient artificial photosynthesis devices for solar water splitting. Our recent report has shown that borate treated BiVO4 (B-BiVO4) results in an improved water oxidation performance. In this study, further improvement of both the photoelectrochemical (PEC) activity and stability of B-BiVO4 was successfully achieved by introducing NiFeV LDHs as an oxygen evolution catalyst and interfacial hole transporter. Benefiting from the synergistic effect of co-catalyst and borate pretreatment, the as-prepared NiFeV/B-BiVO4 exhibited a high photocurrent density of 4.6 mA cm−2 at 1.23 VRHE and an outstanding onset potential of ∼0.2 VRHE with good long-term stability. More importantly, NiFeV was found to play a pivotal role in the critically efficient suppression of charge combination on the BiVO4 surface and acceleration of charge transfer rather than a mere electrocatalyst for water oxidation.

Co-catalysts have been widely studied to improve photocatalytic water oxidation efficiency, and the precise control of their oxidation states and minimizing particle sizes can optimize the practical performance. In this work, ultrafine cobalt oxide (CoOx) co-catalysts with specific Co valence states have been successfully synthesized, which are anchored on a tantalum oxynitride (TaON) host photocatalyst via a photochemical metal–organic deposition method. Photoelectrochemical and photoluminescence analyses prove that the Co2+ dominant CoOx co-catalyst is favorable for charge separation and transportation because of its excellent hole-capturing properties, consequently enhancing the photocatalytic water oxidation performance. The resultant TaON with the Co2+ dominant CoOx co-catalyst exhibits an outstanding O2 production rate up to 6.10 ± 0.17 mmol h−1 g−1 and possesses an excellent apparent quantum efficiency of 21.2% at 420 nm, which are among the best values of water-oxidation photocatalysts.

Among all CO2 electroreduction products, methane (CH4) and ethylene (C2H4) are two typical and valuable hydrocarbon products which are formed in two different pathways: hydrogenation and dimerization reactions of the same CO intermediate. Theoretical studies show that the adsorption configurations of CO intermediate determine the reaction pathways towards CH4/C2H4. However, it is challenging to experimentally control the CO adsorption configurations at the catalyst surface, and thus the hydrocarbon selectivity is still limited. Herein, we seek to synthesize two well-defined copper nanocatalysts with controllable surface structures. The two model catalysts exhibit a high hydrocarbon selectivity toward either CH4 (83%) or C2H4 (93%) under identical reduction conditions. Scanning transmission electron microscopy and X-ray absorption spectroscopy characterizations reveal the low-coordination Cu-0 sites and local Cu-0/Cu+ sites of the two catalysts, respectively. CO-temperature programed desorption, in-situ attenuated total reflection Fourier transform infrared spectroscopy and density functional theory studies unveil that the bridge-adsorbed CO (COB) on the low-coordination Cu-0 sites is apt to be hydrogenated to CH4, whereas the bridge-adsorbed CO plus linear-adsorbed CO (COB + COL) on the local Cu-0/Cu+ sites are apt to be coupled to C2H4. Our findings pave a new way to design catalysts with controllable CO adsorption configurations for high hydrocarbon product selectivity. (C) 2020 Science China Press. Published by Elsevier B.V. and Science China Press. All rights reserved.

Recently, hydrogel-based flexible sensors have attracted tremendous attention for use in wearable soft electronics. However, under sub-zero temperatures, common hydrogel-based flexible devices are always out of work due to their poor stability in freezing environments. To endow hydrogel-based sensors with long-term stability and anti-freezing ability as well as multi-functional abilities, we developed a polydopamine-reduced graphene oxide (PDA-rGO)/sodium alginate (SA)/polyacrylamide (PAM) composite organohydrogel with dual crosslinking networks. The excellent conductivity of the organohydrogel is due to the well-dispersed rGO endowed by mussel-inspired chemistry and ions such as Ca2+, which give the organohydrogel strain, pressure, and temperature sensing capabilities with a high gauge factor (2.09) within a broad strain range (0–250%), short response time (200 ms), and a wide temperature detection range (−20 °C to 60 °C), respectively. Moreover, the assembled sensors can also detect multiple human motions such as finger bending, facial micro-expression, and hand gesture recognition. Especially, owing to the synergistic effects of ion transportation, water–glycerol binary solvent, and the reduced graphene oxide in the composite hydrogel, the organohydrogel achieved an unprecedented thermal sensitivity of 97.60% °C−1 at sub-zero temperatures, which is the most sensitive stretchable thermistor so far reported. Therefore, this as-prepared functional organohydrogel paves the way for potential applications in human–machine interactions and personalized multi-signal monitoring in a broad temperature range.

High-quality epitaxial LaCoO3 (LCO) thin films have been deposited on SrTiO3 (STO) substrates with pulsed laser deposition (PLD). We find that the LCO films undergo a typical ferromagnetic–paramagnetic (FM–PM) phase transition at ∼80 K. To understand the nature of magnetic phase transition, various methods, including the modified Arrott plot and critical isotherm analysis, were used to determine the critical exponents, which are β = 0.754(1) with a Curie temperature TC = 79.8(8) K and γ = 1.52(2) with TC = 79.9(2) K. The reliability of these critical exponents was confirmed using the Widom scaling relation and the scaling hypothesis. Further analysis revealed that the spin coupling within the LCO films exhibits two-dimensional (2D) long-range magnetic interaction and the magnetic exchange distance decays as J(r) ∼ r−(3.46). Our critical behavior analysis may shed new light on the further understanding of the origin of FM and the relatively fixed TC in LCO thin films.

Automated detection of eye diseases using artificial intelligence techniques on optical coherence tomography (OCT) images is widely researched in the field of ophthalmology. Such detections are usually performed with the aid of computers. Using high-level simulations, this study investigates and evaluates three automated age-related macular degeneration (AMD) detection flows in terms of computation time and detection accuracy for future hardware-accelerated designs of intelligent and portable OCT systems. In this study, a block-matching and 3-Dimension filter (BM3DF), a hybrid median filter (HMF), and an adaptive wiener filter (AWF) are used to denoise the OCT images. Support vector machine (SVM), AlexNet, GoogLeNet, and Inception-ResNet are employed for AMD detection. Moreover, Local binary patterns, linear configuration patterns, and transfer learning techniques are used to extract image features. Simulation results reveal that machine-learning-based automated AMD detection realizes a high detection accuracy of 95.91% accompanied by low computation time when using the HMF rather than the BM3DF. When considering deep-learning-based automated AMD detection, the combination of HMF and Inception-ResNet achieves the highest detection accuracy of 98.64% but is accompanied by a dramatic increase in computation time. However, only AlexNet achieves a detection accuracy of 96.40%, accompanied by low computation time. In this study, the tradeoffs between the computation time and detection accuracy have been revealed by comparing the denoising methods for the distinct automated AMD detections.

The design of efficient copper-based (Cu-based) carbon dioxide reduction (CO2RR) electrocatalysts is crucial for converting CO2 to value-added liquid products. In this work, we demonstrate that the strong synergy between Cu core and ultrathin lead (Pb) shell (0.7 nm) in the Cu/Pb core/shell nanocrystals (NCs, CuPb-0.7/C) significantly boosts the electrocatalytic reduction of CO2 toward C2+ products (products with at least two carbon atoms). Specifically, when applying in a flow cell system, the Faradaic efficiency (FE) of total C2+ products and the selectivity of C2+ liquid products are as high as 81.6% and 49.5%, respectively. Moreover, the current density of C2+ liquid products reaches 196.8 mA cm-2, outperforming most of the reported Cu-based catalysts for CO2RR toward the production of C2+ liquid products. Density functional theory calculations indicate that the synergized Cu/Pb core/shell NCs reduce the formation energies of *COOH and *OCCOH intermediates, as the two critical intermediates for the reduction of CO2 to CO and the formation of C2+ products, respectively, and leads to the significant increase in the selectivity of C2+ liquid products. This study provides a efficient Cu-based catalyst for the reduction of CO2, highlighting the importance of synergistic effect for the design of electrocatalysts in catalysis.

Catalysis by canonical radical S-adenosyl-l-methionine (SAM) enzymes involves electron transfer (ET) from [4Fe-4S]+ to SAM, generating an R3S0 radical that undergoes regioselective homolytic reductive cleavage of the S-C5' bond to generate the 5'-dAdo· radical. However, cryogenic photoinduced S-C bond cleavage has regioselectively yielded either 5'-dAdo· or ·CH3, and indeed, each of the three SAM S-C bonds can be regioselectively cleaved in an RS enzyme. This diversity highlights a longstanding central question: what controls regioselective homolytic S-C bond cleavage upon SAM reduction? We here provide an unexpected answer, founded on our observation that photoinduced S-C bond cleavage in multiple canonical RS enzymes reveals two enzyme classes: in one, photolysis forms 5'-dAdo·, and in another it forms ·CH3. The identity of the cleaved S-C bond correlates with SAM ribose conformation but not with positioning and orientation of the sulfonium center relative to the [4Fe-4S] cluster. We have recognized the reduced-SAM R3S0 radical is a (2E) state with its antibonding unpaired electron in an orbital doublet, which renders R3S0 Jahn-Teller (JT)-active and therefore subject to vibronically induced distortion. Active-site forces induce a JT distortion that localizes the odd electron in a single priority S-C antibond, which undergoes regioselective cleavage. In photolytic cleavage those forces act through control of the ribose conformation and are transmitted to the sulfur via the S-C5' bond, but during catalysis thermally induced conformational changes that enable ET from a cluster iron generate dominant additional forces that specifically select S-C5' for cleavage. This motion also can explain how 5'-dAdo· subsequently forms the organometallic intermediate Ω.

Many studies reported biotic change along a continental warming gradient. However, the temporal and spatial change of tree diversity and their sensitivity to climate warming might differ from region to region. Understanding of the variation among studies with regard to the magnitude of such biotic changes is minimal, especially in montane ecosystems. Our aim is to better understand changes in spatial heterogeneity and temporal dynamics of mountain tree communities under climate warming over the past four decades. In 2017, we resurveyed and recorded all tree species from 107 long‐term monitoring plots that were first studied between 1974 and 1976. These plots were located in montane forests in the Giant Panda National Park (GPNP), China. Our results showed that spatial differences were found in tree species diversity changes response to mean annual temperature change over the past four decades. Tree species richness increased significantly under climate warming in Minshan (MS) and Xiaoxiangling (XXL) with higher warming rate than Qionglai (QLS) and Liangshan (LS). The trees species diversity in MS and XXL were more sensitive to climatic warming. MS and XXL should receive priority protection in the next conservation plan of the GPNP. The GPNP should avoid taking a “one‐size‐fits‐all” approach for diversity conservation due to spatial heterogeneity in plant community dynamics., Tree species richness and abundance of montane forests increased over time in all our study area, except Liangshan (LS), especially in XiaoXiangLing with the highest warming rate. However, beta diversity underwent a significantly higher change rate at LS than in other mountains which indicated that plant species that do not belong to these four mountains entered LS in those years. Moreover, the beta diversities of tree between sample plots in the LS regions were homogenized.

LA-ICP-MS U–Pb and Hf isotope analysis was conducted on zircons from the metamorphic unit of Omo Formation and a granodorite body of Tokunoshima in the Amami Islands, Southwest Japan. Zircons from ...

We report the synthesis of the carbon-14-labeled unnatural nucleoside islatravir, an investigational HIV drug, through a one-pot biocatalytic cascade starting from acetaldehyde-2-14C. Combining enz...

Incremental accretion of continental fragments from East Gondwana to Eurasia resulted in the growth of Asia and rise of the Tibetan Plateau, yet its detailed evolution remains uncertain. Argoland, a continental fragment that rifted from NW Australia during the Late Jurassic, played a key role in the initial opening of the Indian Ocean and the evolution of eastern Tethys. However, its present identity remains elusive, with East Java-West Sulawesi currently assumed to be the most likely option. To constrain the missing Argoland and its role in India-Asia convergence, we report new detrital zircon data from Sulawesi, Indonesia, and West Burma, Myanmar, and synthesize literature results from relevant regions in Southeast Asia, which (>15,000) reveal age profiles of West Sulawesi, the central Sulawesi metamorphic belt, and southeast Borneo comparable to that of Bird's Head, New Guinea, whereas age patterns of West Burma and East/West Java are similar to those of NW Australia. Notably, the most dominant age populations in NW Australia are rarely detected in Sulawesi and Borneo. These observations, combined with previous geological records and recent paleomagnetic data, suggest that West Burma is the mysterious Argoland, opposing the currently favored East Java-West Sulawesi model, with East Java and West Sulawesi probably having originated from NW Australia and Bird's Head, respectively. We estimate an average northward motion of ∼6–8 cm/yr for West Burma, which split from NW Australia to approach the equator during ca. 155–95 Ma, shedding new light on the reconstruction and breakup of northern East Gondwana, progressive building of Southeast Asia, and India-Asia convergence.

The hydroxyapatite (HA) coating doped with multiple ions has attracted much attention due to its potential to impart various functions (antibacterial and osteogenic activity, etc.) to plastic surgery and dental implants. In this work, novel nano fluorohydroxyapatite (FHA) coatings substituted simultaneously with Sr2+ and Ag+ (SrAgFHA) were designed and successfully synthesized by one-step electrodeposition. Ag was used to impart antibacterial ability to SrAgFHA, and Sr can balance the potential cytotoxicity of Ag, thereby improving the cell compatibility of the composite coating. The SrAgFHA coating was consisted of closely aggregated/fused hexagonal columnar nanorods of ~100–150 nm. The nano-coating has higher corrosion resistance than FHA coating and uncoated Ti. Due to the doping of F, SrAgFHA nanorods have a complete single crystal structure and exhibit low degradability, which can ensure the long-term and slow release of Sr2+ and Ag+ ions. This nanorod coating with a low roughness and zeta potential was superhydrophobic and displayed good in vitro bioactivities, such as excellent apatite forming ability, which proves the osteoconductive nature. The results of electrochemical impedance spectroscopy confirmed that by electrodepositing the SrAgFHA coating on the Ti surface, the corrosion resistance was significantly improved. SrAgFHA coating has the best antibacterial effect and osteogenesis ability, for example, the broad-spectrum antibacterial effect on E. coli and S. aureus is 96.5 and 96.8%, respectively, and it can induce osteoblast adhesion, proliferation and differentiation. The rabbit bone defect experiment showed that a large amount of new bone was formed around the SrAgFHA coated implant, and its early bone integration ability was the strongest. In summary, SrAgFHA strikes a balance between superior corrosion resistance, cytocompatibility and excellent antibacterial properties. The multi-element co-doped HA coating has huge clinical application potential in anti-infective repair.