Reconstructable Carbon Monolayer-MoS2 Intercalated Heterostructure Enabled by Atomic Layers-Confined Topotactic Transformation for Ultrafast Lithium Storage.

The intercalation structure of two-dimensional materials with expanded interlayer distance can facilitate mass transport, which is promising in fast-charging lithium-ion batteries (LIBs). However, the designed intercalation structures will be pulverized and destroyed under tough working conditions, causing overall performance deterioration of the batteries. Here, we present that an intercalated heterostructure made of the typical layered material of MoS2 intercalated by N-doped graphene-like carbon monolayer (MoS2/g-CM) through a polymer intercalation strategy exhibits a unique behavior of reversible reconstructability as an LIB anode during cycling. A mechanism of "carbon monolayers-confined topotactic transformation" is proposed, which is evidenced by substantial in/ex situ characterizations. The intercalated heterostructure of MoS2/g-CM featuring a reconstructable property and efficient interlayer electron/ion transport exhibits an unprecedented rate capability up to 50 A g-1 and outstanding long cyclability. Moreover, the proposed strategy based on g-CM intercalation has been extended to the MoSe2 system, also realizing reconstructability of the intercalated heterostructure and improved LIB performance, demonstrating its versatility and great potential in applications.

Scalable Nanotrap Matrix Enhanced Electroporation for Intracellular Recording of Action Potential.

Electrophysiological recording, as a long-sought objective, plays a crucial role in fundamental biomedical research and practical clinical applications. The challenge in developing electrophysiological detection platforms is to combine simplicity, stability, and sensitivity in the same device. In this study, we develop a nanotrapped microelectrode based on a porous PET membrane, which is compatible with large-scale microtechnologies. The nanotraps can promote the protrusion of the local cell membrane in the hollow center and offer a unique nanoedge structure for tight sealing and effective electroporation. We demonstrate that scalable nanotraps can enhance cell-electrode coupling and perform high-quality intracellular recording. Further, the nanoedge-enhanced electroporation and minimally invasive nanotrapped recordings afford much longer intracellular access of over 100 min and permit consecutive electroporation events in a short period of time. This study suggests that the geometry-regulating strategy of the cell-electrode nanointerface could significantly improve the intracellular recording performance of a nanopatterned electrode.

Space-Confined Atomic Clusters Catalyze Superassembly of Silicon Nanodots within Carbon Frameworks for Use in Lithium-Ion Batteries.

Incorporating nanoscale Si into a carbon matrix with high dispersity is desirable for the preparation of lithium-ion batteries (LIBs) but remains challenging. A space-confined catalytic strategy is proposed for direct superassembly of Si nanodots within a carbon (Si NDs⊂C) framework by copyrolysis of triphenyltin hydride (TPT) and diphenylsilane (DPS), where Sn atomic clusters created from TPT pyrolysis serve as the catalyst for DPS pyrolysis and Si catalytic growth. The use of Sn atomic cluster catalysts alters the reaction pathway to avoid SiC generation and enable formation of Si NDs with reduced dimensions. A typical Si NDs⊂C framework demonstrates a remarkable comprehensive performance comparable to other Si-based high-performance half LIBs, and higher energy densities compared to commercial full LIBs, as a consequence of the high dispersity of Si NDs with low lithiation stress. Supported by mechanic simulations, this study paves the way for construction of Si/C composites suitable for applications in future energy technologies.

Covalent Assembly of MoS2 Nanosheets with SnS Nanodots as Linkages for Lithium/Sodium-Ion Batteries.

Weak van der Waals interactions between interlayers of two-dimensional layered materials result in disabled across-interlayer electron transfer and poor layered structural stability, seriously deteriorating their performance in energy applications. Herein, we propose a novel covalent assembly strategy for MoS2 nanosheets to realize unique MoS2 /SnS hollow superassemblies (HSs) by using SnS nanodots as covalent linkages. The covalent assembly based on all-inorganic and carbon-free concept enables effective across-interlayer electron transfer, facilitated ion diffusion kinetics, and outstanding mechanical stability, which are evidenced by experimental characterization, DFT calculations, and mechanical simulations. Consequently, the MoS2 /SnS HSs exhibit superb rate performance and long cycling stability in lithium-ion batteries, representing the best comprehensive performance in carbon-free MoS2 -based anodes to date. Moreover, the MoS2 /SnS HSs also show excellent sodium storage performance in sodium-ion batteries.

Direct Superassemblies of Freestanding Metal-Carbon Frameworks Featuring Reversible Crystalline-Phase Transformation for Electrochemical Sodium Storage.

High-power sodium-ion batteries (SIBs) with long-term cycling attract increasing attention for large-scale energy storage. However, traditional SIBs toward practical applications still suffer from low rate capability and poor cycle induced by pulverization and amorphorization of anodes at high rate (over 5 C) during the fast ion insertion/extraction process. The present work demonstrates a robust strategy for a variety of (Sb-C, Bi-C, Sn-C, Ge-C, Sb-Bi-C) freestanding metal-carbon framework thin films via a space-confined superassembly (SCSA) strategy. The sodium-ion battery employing the Sb-C framework exhibits an unprecedented performance with a high specific capacity of 246 mAh g-1, long life cycle (5000 cycles), and superb capacity retention (almost 100%) at a high rate of 7.5 C (3.51A g-1). Further investigation indicates that the unique framework structure enables unusual reversible crystalline-phase transformation, guaranteeing the fast and long-cyclability sodium storage. This study may open an avenue to developing long-cycle-life and high-power SIBs for practical energy applications.

Microcrack monitoring and fracture evolution of coal and rock using integrated acoustic emission and digital image correlation techniques.

The mechanical properties of a coal-rock body were examined through uniaxial compression tests, and the rupture process of the coal-rock body was monitored in real time using a combined acoustic emission (AE) monitoring system and a digital image correlation (DIC) full-field strain measurement system. From a comparison of the mechanical properties of coal and sandstone, clear differences are apparent regarding the uniaxial compressive strength, deformation characteristics, and damage mode; the brittle failure characteristics of the coal samples are also more evident. The change in AE energy reflects the accumulation and release of elastic energy during the rupture process, and the evolution of AE localization points under different stress levels can effectively reflect rupture propagation. Further, the DIC full-field strain measurement method can quantitatively monitor the evolution of the displacement and strain fields at the marking point and surface simultaneously, thereby overcoming the limitations of traditional empirical and qualitative rupture processes. During monitoring, the AE focuses on the internal rupture of the specimen and the DIC focuses on the surface deformation. These complement each other and reflect the rupture process more comprehensively.

Progress, Challenge, and Prospect of LiMnO2 : An Adventure toward High-Energy and Low-Cost Li-Ion Batteries.

Lithium manganese oxides are considered as promising cathodes for lithium-ion batteries due to their low cost and available resources. Layered LiMnO2 with orthorhombic or monoclinic structure has attracted tremendous interest thanks to its ultrahigh theoretical capacity (285 mAh g-1 ) that almost doubles that of commercialized spinel LiMn2 O4 (148 mAh g-1 ). However, LiMnO2 undergoes phase transition to spinel upon cycling cause by the Jahn-Teller effect of the high-spin Mn3+ . In addition, soluble Mn2+ generates from the disproportionation of Mn3+ and oxygen release during electrochemical processes may cause poor cycle performance. To address the critical issues, tremendous efforts have been made. This paper provides a general review of layered LiMnO2 materials including their crystal structures, synthesis methods, structural/elemental modifications, and electrochemical performance. In brief, first the crystal structures of LiMnO2 and synthetic methods have been summarized. Subsequently, modification strategies for improving electrochemical performance are comprehensively reviewed, including element doping to suppress its phase transition, surface coating to resist manganese dissolution into the electrolyte and impede surface reactions, designing LiMnO2 composites to improve electronic conductivity and Li+ diffusion, and finding compatible electrolytes to enhance safety. At last, future efforts on the research frontier and practical application of LiMnO2 have been discussed.

Kinetic-Thermodynamic Promotion Engineering toward High-Density Hierarchical and Zn-Doping Activity-Enhancing ZnNiO@CF for High-Capacity Desalination.

Despite the promising potential of transition metal oxides (TMOs) as capacitive deionization (CDI) electrodes, the actual capacity of TMOs electrodes for sodium storage is significantly lower than the theoretical capacity, posing a major obstacle. Herein, we prepared the kinetically favorable ZnxNi1 - xO electrode in situ growth on carbon felt (ZnxNi1 - xO@CF) through constraining the rate of OH- generation in the hydrothermal method. ZnxNi1 - xO@CF exhibited a high-density hierarchical nanosheet structure with three-dimensional open pores, benefitting the ion transport/electron transfer. And tuning the moderate amount of redox-inert Zn-doping can enhance surface electroactive sites, actual activity of redox-active Ni species, and lower adsorption energy, promoting the adsorption kinetic and thermodynamic of the Zn0.2Ni0.8O@CF. Benefitting from the kinetic-thermodynamic facilitation mechanism, Zn0.2Ni0.8O@CF achieved ultrahigh desalination capacity (128.9 mgNaCl g-1), ultra-low energy consumption (0.164 kW h kgNaCl-1), high salt removal rate (1.21 mgNaCl g-1 min-1), and good cyclability. The thermodynamic facilitation and Na+ intercalation mechanism of Zn0.2Ni0.8O@CF are identified by the density functional theory calculations and electrochemical quartz crystal microbalance with dissipation monitoring, respectively. This research provides new insights into controlling electrochemically favorable morphology and demonstrates that Zn-doping, which is redox-inert, is essential for enhancing the electrochemical performance of CDI electrodes.

A Ternary (P, Se, S) Covalent Inorganic Framework as a Shuttle Effect-Free Cathode for Li-S Batteries.

Developing new cathode materials to avoid shuttle effect of Li-S batteries at source is crucial for practical high-energy applications, which, however, remains a great challenge. Herein, a new class of sulfur-containing ternary covalent inorganic framework (CIF), P4 Se6 S40 , is explored, by simply comelting powders of P, S, and Se. The P4 Se6 S40 CIF with open framework enables all active sites available during electrochemical reactions, giving a high capacity delivery. Moreover, introducing Se atoms can improve intrinsic electronic conductivity of S chains yet without remarkably compromising the capacity because Se is also electrochemical active to lithium storage. More importantly, Se atoms in S-Se chains can serve as a heteroatom barrier to block the bonding of S atoms around, effectively avoiding the formation of long-chain polysulfides during cycling. Besides, stable Li3 PS4 with a tetrahedral configuration formed after lithiation works as not only a good ionic conductor to promote Li ion diffusion, but a three-dimensional spatial barrier and chemical anchor to suppress the dissolution and diffusion of lithium polysulfides (LiPS), further inhibiting the shuttle effect. Consequently, the P4 Se6 S40 cathode delivers high capacity and excellent capacity retention with even a high loading of 10.5 mg cm-2 which far surpasses the requirement for commercial applications.

Multiband superconductivity of heavy electrons in a TlNi2Se2 single crystal.

We have made the first observation of superconductivity in TlNi2Se2 at T(C)=3.7 K, and it appears to involve heavy electrons with an effective mass m*=(14-20)m(b), as inferred from the normal-state electronic specific heat and the upper critical field, H(C2)(T). We found that the zero-field electronic specific-heat data, C(es)(T) (0.5 K≤T<3.7 K) in the superconducting state can be fitted with a two-gap BCS model, indicating that TlNi2Se2 seems to be a multiband superconductor, which is consistent with the band calculation for the isostructural KNi2S2. It is also found that the electronic specific-heat coefficient in the mixed state γN(H) exhibits a H(1/2) behavior, which is considered as a common feature of the d-wave superconductors. TlNi2Se2, as a d-electron system with heavy electron superconductivity, may be a bridge between cuprate- or iron-based and conventional heavy-fermion superconductors.

Ti3 C2 -MXene Partially Derived Hierarchical 1D/2D TiO2 /Ti3 C2 Heterostructure Electrode for High-Performance Capacitive Deionization.

Constructing faradaic electrode with superior desalination performance is important for expanding the applications of capacitive deionization (CDI). Herein, a simple one-step alkalized treatment for in situ synthesis of 1D TiO2 nanowires on the surface of 2D Ti3 C2 nanosheets, forming a Ti3 C2 -MXene partially derived hierarchical 1D/2D TiO2 /Ti3 C2 heterostructure as the cathode electrode is reported. Cross-linked TiO2 nanowires on the surface help avoid layer stacking while acting as the protective layer against contact of internal Ti3 C2 with dissolved oxygen in water. The inner Ti3 C2 MXene nanosheets cross over the TiO2 nanowires can provide abundant active adsorption sites and short ion/electron diffusion pathways. . Density functional theory calculations demonstrated that Ti3 C2 can consecutively inject electrons into TiO2 , indicating the high electrochemical activity of the TiO2 /Ti3 C2 . Benefiting from the 1D/2D hierarchical structure and synergistic effect of TiO2 and Ti3 C2 , TiO2 /Ti3 C2 heterostructure presents a favorable hybrid CDI performance, with a superior desalination capacity (75.62 mg g-1 ), fast salt adsorption rate (1.3 mg g-1 min-1 ), and satisfactory cycling stability, which is better than that of most published MXene-based electrodes. This study provides a feasible partial derivative strategy for construction of a hierarchical 1D/2D heterostructure to overcome the restrictions of 2D MXene nanosheets in CDI.

Predicting the Sauter Mean Diameter of Swirl Cup Airblast Fuel Injector Based on Backpropagation (BP) Neural Network Model.

This study was dedicated to introducing a new method for predicting the Sauter mean diameter (SMD) buildup in the swirl cup airblast fuel injector. There have been considerable difficulties with predicting SMD mainly because of complicated flow characteristics in a spray. Therefore, the backpropagation (BP) neural network-based machine learning was applied for the prediction of SMD as a function of geometry, condition parameters, and axial distance such as primary swirl number, secondary swirl number, venturi angle, mass flow rate of fuel, and relative air pressure. SMD was measured by a phase Doppler particle analyzer (PDPA). The results show that the prediction accuracy of the trained BP neural network was excellent with a coefficient of determination (R2) score of 0.9599, root mean square error (RMSE) score of 1.4613, and overall relative error within 20%. Through sensitivity analysis, the relative air pressure drop and primary swirl number were the largest and smallest factors affecting the value of SMD, respectively. Finally, the prediction accuracy of the BP neural network model is far greater than the current prediction correlations. Moreover, for the predicting target in the present study, the BP neural network shows the advantages of a simple structure and short running time compared with PSO-BP and GRNN. All these prove that the BP neural network is a novel and effective way to predict the SMD of droplets generated by a swirl cup airblast fuel injector.

A smart tablet-phone-based system using dynamic light modulation for highly sensitive colorimetric biosensing.

Facile, efficient, and inexpensive biosensing systems are in high demand for biomedical test. In recent years, numerous smartphone-based biosensing systems have been developed to match demand for biomedical test in source-limited environment. However, application of these smartphone-based biosensing systems was limited because of performance gap between the smartphone-based systems and commercial plate readers. In this study, we have developed a smart tablet-phone-based colorimetric plate reader (STPCPR) with intelligent and dynamic light modulation for broad-range colorimetric assays. The STPCPR allows controllable modulation of exciting light in three different color channels that is lack in conventional smartphone-based system. Using optimized exciting modulation, the STPCPR shows higher sensitivities, lower detection limits, and broader detection ranges in test of pigments, proteins, and cells when compared to conventional plate readers and smartphone-based system. Therefore, the developed STPCPR can serve as an ideal next-generation smartphone-based biosensing system for point-of-care colorimetric test in diverse biomedical applications in source-limited environment.

Changing characteristics of ecosystem and water storage under the background of warming and humidification in the Qilian Mountains, China.

The Qilian Mountains provide an ecological security barrier, and the region is an important river runoff area in China. Water resources play an essential role in the natural environment of Northwest China. This study used daily temperature and precipitation data from meteorological stations in the Qilian Mountains from 2003 to 2019, Gravity Recovery and Climate Experiment, and Moderate Resolution Imaging Spectroradiometer satellite data. Additionally, we used the Gravity Recovery and Climate Experiment satellite's monthly gravity field model data. Furthermore, we analyzed the characteristics of climate warming and humidification in the eastern, central, and western sections of the Qilian Mountains based on spatial precipitation interpolation and linear trend analysis. Finally, we examined the relationship between water storage changes and precipitation and its impact on vegetation ecology. The results revealed a significant warming and humidification trend in the western Qilian Mountains. The temperature increased significantly, and the increased precipitation rate in summer reached 1.5-3.1 mm/10a. Water storage in the Qilian Mountains displayed an increasing trend, with an increase of approximately 14.3 × 108 m3 over the 17 years study period, averaging an increase of 8.4 mm/year. The spatial distribution of water storage in the Qilian Mountains increased from north to south and east to west. There were noticeable seasonal differences, with the largest surplus occurring in the western Qilian Mountains (71.2 mm in summer). The fractional vegetation coverage in 95.2 % of the western Qilian Mountains and net primary productivity in 90.4 % of the area displayed an increasing trend, and vegetation ecology improved significantly. This study aims to investigate the characteristics of ecosystem and water storage changes in the Qilian Mountain area under the background of climate warming and humidification. The results obtained from this study provided an assessment of the vulnerability of alpine ecosystems and helped in making spatially explicit decisions for the rational utilization of water resources.

Pressure- and composition-induced structural quantum phase transition in the cubic superconductor (Sr, Ca)3Ir4Sn13.

We show that the quasi-skutterudite superconductor Sr(3)Ir(4)Sn(13) undergoes a structural transition from a simple cubic parent structure, the I phase, to a superlattice variant, the I' phase, which has a lattice parameter twice that of the high temperature phase. We argue that the superlattice distortion is associated with a charge density wave transition of the conduction electron system and demonstrate that the superlattice transition temperature T(*) can be suppressed to zero by combining chemical and physical pressure. This enables the first comprehensive investigation of a superlattice quantum phase transition and its interplay with superconductivity in a cubic charge density wave system.

Zero-Strain High-Capacity Silicon/Carbon Anode Enabled by a MOF-Derived Space-Confined Single-Atom Catalytic Strategy for Lithium-Ion Batteries.

Developing zero-strain electrode materials with high capacity is crucial for lithium-ion batteries (LIBs). Here, a new zero-strain composite material made of ultrasmall Si nanodots (NDs) within metal organic framework-derived nanoreactors (Si NDs⊂MDN) through a novel space-confined catalytic strategy is reported. The unique Si NDs⊂MDN anode features a low strain (<3%) and a high theoretical lithium storage capacity (1524 mAh g-1 ) which far surpasses the traditional single-crystal counterparts that suffer from a low capacity delivery. The zero-strain property is evidenced by substantial characterizations including ex/in situ transmission electron microscopy and mechanical simulations. The Si NDs⊂MDN exhibits superior cycling stability and high reversible capacity (1327 mAh g-1 at 0.1 A g-1 after 100 cycles) in half-cells and high energy density (366 Wh kg-1 after 300 cycles) in a full cell. This study reports a new catalog of zero-strain electrode material with significantly improved capacity beyond the traditional single-crystal zero-strain materials.

An Improved Automated High-Throughput Efficient Microplate Reader for Rapid Colorimetric Biosensing.

A high-throughput instrument to measure the full spectral properties of biochemical agents is necessary for fast screening in fields such as medical tests, environmental monitoring, and food analysis. However, this need has currently not been fully met by the commercial microplate reader (CMR). In this study, we have developed an automated high-throughput efficient microplate reader (AHTEMR) platform by combining a spectrometer and high-precision ball screw two-dimensional motion slide together, for high-throughput and full-spectrum-required biochemical assays. A two-dimensional slide working on a ball screw was driven by a stepper motor with a custom-designed master control circuit and used as a motion system of the AHTEMR platform to achieve precise positioning and fast movement of the microplate during measurements. A compact spectrometer was coupled with an in-house designed optical pathway system and used to achieve rapid capture of the full spectral properties of biochemical agents. In a performance test, the AHTEMR platform successfully measured the full spectral absorbance of bovine serum albumin (BSA) and glucose solution in multiple wells of the microplate within several minutes and presented the real-time full spectral absorbance of BSA and glucose solution. Compared with the CMR, the AHTEMR is 79 times faster in full-spectrum measurements and 2.38 times more sensitive at the optimal wavelength of 562 nm. The rapid measurement also demonstrated the great capacity of the AHTEMR platform for screening out the best colorimetric wavelengths for tests of BSA and glucose development, which will provide a promising approach to achieving high-throughput and full-spectrum-required biochemical assays.

CoPSe: A New Ternary Anode Material for Stable and High-Rate Sodium/Potassium-Ion Batteries.

The exploration of ideal electrode materials overcoming the critical problems of large electrode volume changes and sluggish redox kinetics induced by large ionic radius of Na+ /K+ ions is highly desirable for sodium/potassium-ion batteries (SIBs/PIBs) toward large-scale applications. The present work demonstrates that single-phase ternary cobalt phosphoselenide (CoPSe) in the form of nanoparticles embedded in a layered metal-organic framework (MOF)-derived N-doped carbon matrix (CoPSe/NC) represents an ultrastable and high-rate anode material for SIBs/PIBs. The CoPSe/NC is fabricated by using the MOF as both a template and precursor, coupled with in situ synchronous phosphorization/selenization reactions. The CoPSe anode holds a set of intrinsic merits such as lower mechanical stress, enhanced reaction kinetics, as well as higher theoretical capacity and lower discharge voltage relative to its counterpart of CoSe2 , and suppressed shuttle effect with higher intrinsic electrical conductivity relative to CoPS. The involved mechanisms are evidenced by substantial characterizations and density functional theory (DFT) calculations. Consequently, the CoPSe/NC anode shows an outstanding long-cycle stability and rate performance for SIBs and PIBs. Moreover, the CoPSe/NC-based Na-ion full cell can achieve a higher energy density of 274 Wh kg-1 , surpassing that based on CoSe2 /NC and most state-of-the-art Na-ion full cells based on P-, Se-, or S-containing binary/ternary anodes to date.

Armoring Black Phosphorus Anode with Stable Metal-Organic-Framework Layer for Hybrid K-Ion Capacitors.

Potassium-ion capacitors (KICs) are promising for sustainable and eco-friendly energy storage technologies, yet their slow reaction kinetics and poor cyclability induced by large K-ion size are a major obstacle toward practical applications. Herein, by employing black phosphorus nanosheets (BPNSs) as a typical high-capacity anode material, we report that BPNS anodes armored with an ultrathin oriented-grown metal-organic-framework (MOF) interphase layer (BPNS@MOF) exhibit regulated potassium storage behavior for high-performance KICs. The MOF interphase layers as protective layer with ordered pores and high chemical/mechanical stability facilitate K ion diffusion and accommodate the volume change of electrode, beneficial for improved reaction kinetics and enhanced cyclability, as evidenced by substantial characterizations, kinetics analysis and DFT calculations. Consequently, the BPNS@MOF electrode as KIC anodes exhibits outstanding cycle performance outperforming most of the reported state-of-art KICs so far.

Co(OH)3 nanobelts: synthesis, characterization and shape-preserved transformation to pseudo-single-crystalline Co3O4 nanobelts.

In this paper, we demonstrated a facile hydrothermal route leading to the generation of a new cobalt hydroxide, Co(OH)(3), nanobelt. This new product of Co(OH)(3) nanobelts was well characterized and identified by SEM, TEM, XRD, EDX, XPS, EXAFS, Raman, TGA and SQUID. Additionally, through systematic investigations on morphological evolution, it was found that the size and shape of Co(OH)(3) nanobelts were adjustable in large scale, e.g. from 50 to 1.5 microm in length and 5 microm to 20 nm in width, by means of fine experimental parameter control. Furthermore, the unique pseudo-single-crystalline Co(3)O(4) nanobelts were produced from Co(OH)(3) precursors via heating treatment. This is the first synthesis of Co(OH)(3) with tunable shapes and sizes, which may find important applications as gas sensors, catalysts, and electrode materials, owing to the specific large surface-to-volume ratio and other unique properties endowed by typical 1D nanobelts.