Memristive switching in the surface of a charge-density-wave topological semimetal.

Owing to the outstanding properties provided by nontrivial band topology, topological phases of matter are considered as a promising platform towards low-dissipation electronics, efficient spin-charge conversion, and topological quantum computation. Achieving ferroelectricity in topological materials enables the non-volatile control of the quantum states, which could greatly facilitate topological electronic research. However, ferroelectricity is generally incompatible with systems featuring metallicity due to the screening effect of free carriers. In this study, we report the observation of memristive switching based on the ferroelectric surface state of a topological semimetal (TaSe4)2I. We find that the surface state of (TaSe4)2I presents out-of-plane ferroelectric polarization due to surface reconstruction. With the combination of ferroelectric surface and charge-density-wave-gapped bulk states, an electric-switchable barrier height can be achieved in (TaSe4)2I-metal contact. By employing a multi-terminal-grounding design, we manage to construct a prototype ferroelectric memristor based on (TaSe4)2I with on/off ratio up to 103, endurance over 103 cycles, and good retention characteristics. The origin of the ferroelectric surface state is further investigated by first-principles calculations, which reveals an interplay between ferroelectricity and band topology. The emergence of ferroelectricity in (TaSe4)2I not only demonstrates it as a rare but essential case of ferroelectric topological materials, but also opens new routes towards the implementation of topological materials in functional electronic devices.

Spatial evolution of the proton-coupled Mott transition in correlated oxides for neuromorphic computing.

The proton-electron coupling effect induces rich spectrums of electronic states in correlated oxides, opening tempting opportunities for exploring novel devices with multifunctions. Here, via modest Pt-aided hydrogen spillover at room temperature, amounts of protons are introduced into SmNiO3-based devices. In situ structural characterizations together with first-principles calculation reveal that the local Mott transition is reversibly driven by migration and redistribution of the predoped protons. The accompanying giant resistance change results in excellent memristive behaviors under ultralow electric fields. Hierarchical tree-like memory states, an instinct displayed in bio-synapses, are further realized in the devices by spatially varying the proton concentration with electric pulses, showing great promise in artificial neural networks for solving intricate problems. Our research demonstrates the direct and effective control of proton evolution using extremely low electric field, offering an alternative pathway for modifying the functionalities of correlated oxides and constructing low-power consumption intelligent devices and neural network circuits.

Engineering Nano-Sized Silicon Anodes with Conductive Networks toward a High Average Coulombic Efficiency of 90.2% via Plasma-Assisted Milling.

Si-based anode is considered one of the ideal anodes for high energy density lithium-ion batteries due to its high theoretical capacity of 4200 mAh g-1. To accelerate the commercial progress of Si material, the multi-issue of extreme volume expansion and low intrinsic electronic conductivity needs to be settled. Herein, a series of nano-sized Si particles with conductive networks are synthesized via the dielectric barrier discharge plasma (DBDP) assisted milling. The p-milling method can effectively refine the particle sizes of pristine Si without destroying its crystal structure, resulting in large Brunauer-Emmett-Teller (BET) values with more active sites for Li+ ions. Due to their unique structure and flexibility, CNTs can be uniformly distributed among the Si particles and the prepared Si electrodes exhibit better structural stability during the continuous lithiation/de-lithiation process. Moreover, the CNT network accelerates the transport of ions and electrons in the Si particles. As a result, the nano-sized Si anodes with CNTs conductive network can deliver an extremely high average initial Coulombic efficiency (ICE) reach of 90.2% with enhanced cyclic property and rate capability. The C-PMSi-50:1 anode presents 615 mAh g-1 after 100 cycles and 979 mAh g-1 under the current density of 5 A g-1. Moreover, the manufactured Si||LiNi0.8Co0.1Mn0.1O2 pouch cell maintains a high ICE of >85%. This work may supply a new insight for designing the nano-sized Si and further promoting its commercial applications.

Ratiometric SERS quantification of SO2 vapor based on Au@Ag-Au with Raman reporter as internal standard.

Practical gas sensing application requires sensors to quantify target analytes with high sensitivity and reproducibility. However, conventional surface enhanced Raman scattering (SERS) sensor lacks reproducibility and quantification arising from variations of "hot spot" distribution and measurement conditions. Here, a ratio-dependent SERS sensor was developed for quantitative label-free gas sensing. Au@Ag-Au nanoparticles (NPs) were filtered onto anodic aluminum oxide (AAO) forming Au@Ag-Au@AAO SERS substrate. 4-MBA was encapsulated in the gap of Au@Ag-Au and served as the internal standard (IS) to calibrate SERS signal fluctuation for improved quantification ability. Combined with headspace sampling method, SO2 residue in traditional Chinese medicine (TCM) can be extracted and captured on the immediate vicinity of Au@Ag-Au surface. The intensity ratio I613 cm-1/I1078 cm-1 showed excellent linearity within the range of 0.5 mg/kg-500 mg/kg, demonstrating superior quantification performance for SO2 detection. Signals for concentration as low as 0.05 mg/kg of SO2 could be effectively collected, much lower than the strictest limit 10 mg/kg in Chinese Pharmacopoeia. Combined with a handheld Raman spectrometer, handy and quantitative TCM quality evaluation in aspect of SO2 residue was realized. This ratiometric SERS sensor functioned well in rapid on-site SO2 quantification, exhibiting excellent sensitivity and simple operability.

Soft-Hard Janus Nanoparticles Triggered Hierarchical Conductors with Large Stretchability, High Sensitivity, and Superior Mechanical Properties.

There is a long-standing conflict between the large stretchability and high sensitivity for strain sensors, a strategy of decoupling the mechanical/electrical module by constructing the hierarchical conductor has been developed in this study. The hierarchical conductor, consisting of a mechanically stretchable layer, a conductive network layer, and a strongly bonded interface, can be produced in a simple one-step process with the aid of soft-hard Janus nanoparticles (JNPs). The introduction of JNPs in the stretchable layer can evenly distribute stress and dissipate energy due to forming the rigid-flexible homogeneous networks. Specifically, JNPs can drive graphene nanosheets (GNS) to fold or curl, creating the unique JNPs-GNS building block that can further construct the conductive network. Due to its excellent deformability to hinder crack propagation, the flexible conductive network could be stretched continuously and the local conductive pathways could be reconstructed. Consequently, the hierarchical conductor could detect both subtle strain of 0-2% and large strain of up to 370%, with a gauge factor (GF) from 66.37 to 971.70, demonstrating outstanding stretchability and sensitivity. And it also owns large tensile strength (5.28 MPa) and high deformation stability. This hierarchical design will give graphene-based sensors a major boost in emerging applications.

A ferroelectric fin diode for robust non-volatile memory.

Among today's nonvolatile memories, ferroelectric-based capacitors, tunnel junctions and field-effect transistors (FET) are already industrially integrated and/or intensively investigated to improve their performances. Concurrently, because of the tremendous development of artificial intelligence and big-data issues, there is an urgent need to realize high-density crossbar arrays, a prerequisite for the future of memories and emerging computing algorithms. Here, a two-terminal ferroelectric fin diode (FFD) in which a ferroelectric capacitor and a fin-like semiconductor channel are combined to share both top and bottom electrodes is designed. Such a device not only shows both digital and analog memory functionalities but is also robust and universal as it works using two very different ferroelectric materials. When compared to all current nonvolatile memories, it cumulatively demonstrates an endurance up to 1010 cycles, an ON/OFF ratio of ~102, a feature size of 30 nm, an operating energy of ~20 fJ and an operation speed of 100 ns. Beyond these superior performances, the simple two-terminal structure and their self-rectifying ratio of ~ 104 permit to consider them as new electronic building blocks for designing passive crossbar arrays which are crucial for the future in-memory computing.

Guided anisotropic oxygen transport in vacancy ordered oxides.

Anisotropic and efficient transport of ions under external stimuli governs the operation and failure mechanisms of energy-conversion systems and microelectronics devices. However, fundamental understanding of ion hopping processes is impeded by the lack of atomically precise materials and probes that allow for the monitoring and control at the appropriate time- and length- scales. In this work, using in-situ transmission electron microscopy, we directly show that oxygen ion migration in vacancy ordered, semiconducting SrFeO2.5 epitaxial thin films can be guided to proceed through two distinctly different diffusion pathways, each resulting in different polymorphs of SrFeO2.75 with different ground electronic properties before reaching a fully oxidized, metallic SrFeO3 phase. The diffusion steps and reaction intermediates are revealed by means of ab-initio calculations. The principles of controlling oxygen diffusion pathways and reaction intermediates demonstrated here may advance the rational design of structurally ordered oxides for tailored applications and provide insights for developing devices with multiple states of regulation.

Janus Composite Particles and Interfacial Catalysis Thereby.

Janus composite particles (JPs) with distinct compartmentalization of varied components thus performances and anisotropic shape display a variety of properties and have demonstrated great potentials in diversify practical applications. Especially, the catalytic JPs are advantageous for multi-phase catalysis with much easier separation of products and recycling the catalysts. In the first section of this review, typical methods to synthesize the JPs with varied morphologies are briefly surveyed in the category of polymeric, inorganic and polymer/inorganic composite. In the main section, recent progresses of the JPs in emulsion interfacial catalysis are summarized covering organic synthesis, hydrogenation, dye degradation, and environmental chemistry. The review will end by calling more efforts toward precision synthesis of catalytic JPs at large scale to meet the stringent requirements in practical applications such as catalytic diagnosis and therapy by the functional JPs.

Effect of Dl-3-n-butylphthalide on mitochondrial Cox7c in models of cerebral ischemia/reperfusion injury.

Several studies have demonstrated the protective effect of dl-3-n-Butylphthalide (NBP) against cerebral ischemia, which may be related to the attenuation of mitochondrial dysfunction. However, the specific mechanism and targets of NBP in cerebral ischemia/reperfusion remains unclear. In this study, we used a chemical proteomics approach to search for targets of NBP and identified cytochrome C oxidase 7c (Cox7c) as a key interacting target of NBP. Our findings indicated that NBP inhibits mitochondrial apoptosis and reactive oxygen species (ROS) release and increases ATP production through upregulation of Cox7c. Subsequently, mitochondrial respiratory capacity was improved and the HIF-1α/VEGF pathway was upregulated, which contributed to the maintenance of mitochondrial membrane potential and blood brain barrier integrity and promoting angiogenesis. Therefore, our findings provided a novel insight into the mechanisms underlying the neuroprotective effects of NBP, and also proposed for the first time that Cox7c exerts a critical role by protecting mitochondrial function.

Interface synergism and engineering of Pd/Co@N-C for direct ethanol fuel cells.

Direct ethanol fuel cells have been widely investigated as nontoxic and low-corrosive energy conversion devices with high energy and power densities. It is still challenging to develop high-activity and durable catalysts for a complete ethanol oxidation reaction on the anode and accelerated oxygen reduction reaction on the cathode. The materials' physics and chemistry at the catalytic interface play a vital role in determining the overall performance of the catalysts. Herein, we propose a Pd/Co@N-C catalyst that can be used as a model system to study the synergism and engineering at the solid-solid interface. Particularly, the transformation of amorphous carbon to highly graphitic carbon promoted by cobalt nanoparticles helps achieve the spatial confinement effect, which prevents structural degradation of the catalysts. The strong catalyst-support and electronic effects at the interface between palladium and Co@N-C endow the electron-deficient state of palladium, which enhances the electron transfer and improved activity/durability. The Pd/Co@N-C delivers a maximum power density of 438 mW cm-2 in direct ethanol fuel cells and can be operated stably for more than 1000 hours. This work presents a strategy for the ingenious catalyst structural design that will promote the development of fuel cells and other sustainable energy-related technologies.

Injectable Double-Network Hydrogel-Based Three-Dimensional Cell Culture Systems for Regenerating Dental Pulp.

The regeneration of dental pulp tissue is very important, but difficult, in dentistry. The biocompatibility, water content, and viscoelastic properties of pulp-like tissue must be optimized to achieve the efficient transfer of metabolites and nutrients, a suitable degradation rate, distribution of encapsulated cells, injectability, and gelation in situ under physiological conditions. As promising materials for pulp regeneration, hydrogel scaffolds have been produced to simulate the extracellular matrix and transmit signaling molecules. It is imperative to develop hydrogels to effectively regenerate pulp tissue for clinical application. Here, two injectable double-network (DN) hydrogel-based three-dimensional (3D) cell culture systems were developed for regenerating dental pulp. The microstructure, mechanical property, rheology property, and degradation behavior of the injectable DN glycol chitosan-based hydrogels in a simulated root canal model were characterized and compared to a single-network (SN) glycol chitosan-based hydrogel. Human dental pulp stem cells (hDPSCs) were then encapsulated into the GC-based hydrogels for the regeneration of pulp tissue, and the biological performance was investigated both in vitro and in vivo. The results showed that the DN hydrogels had ideal injectability under physiological conditions due to the dynamic nature of the crosslinks. Besides, the DN hydrogels exhibited better mechanical properties and longer degradation duration than the corresponding SN hydrogel. As a 3D cell culture system, the characteristics of the DN hydrogel facilitated odontogenic differentiation and mineralization of hDPSCs in vitro. Further in vivo analysis confirmed that the chemical composition, matrix stiffness, and degradation rate of the DN hydrogel matched those of pulp-like fibrous connective tissue, which might be related to Smad3 activation. These findings demonstrate that DN glycol chitosan-based hydrogels are suitable for the regeneration of pulp tissue.

Supramolecular nanofibers via protrusion budding interfacial membrane.

We have proposed an approach to achieve nanofibers or composite nanofibers with functional nanoparticles via the protrusion of the budding interfacial membrane in an oil-water emulsion droplet stabilized with copolymers. The nanofibers were formed by the wrapping of the monolayer of the copolymers. The length is tunable with the copolymer concentration and water/oil ratio of the emulsion.

Orientation-Controlled Ultralong Assembly of Janus Particles Induced by Bubble-Driven Instant Quasi-1D Interfaces.

Constructing precisely oriented assemblies and exploring their orientation-dependent properties remain a challenge for Janus nanoparticles (JNPs) due to their asymmetric characteristics. Herein, we propose a bubble-driven instant quasi-1D interfacial strategy for the oriented assembly of JNP chains in a highly controllable manner. It is found that the rapid formation of templated bubbles can promote the interfacial orientation of JNPs kinetically, while the confined quasi-1D interface in the curved liquid bridge can constrain the disordered rotation of the particles, yielding well-oriented JNP chains in a long range. During the evaporation process, the interfacial orientation of the JNPs can be transferred to the assembled chains. By regulating the amphiphilicity of the JNPs, both heteraxial and coaxial JNP assemblies are obtained, which show different polarization dependences on light scattering, and the related colorimetric logic behaviors are demonstrated. This work demonstrates the great potential of patterned interfacial assembly with a manageable orientation and shows the broad prospect of asymmetric JNP assembly in constructing novel optoelectronic devices.

Tingli Dazao Decoction pretreatment ameliorates mitochondrial damage induced by oxidative stress in cardiomyocytes.

ETHNOPHARMACOLOGICAL RELEVANCE: Tingli Dazao Decoction (TLDZD) recorded in "Synopsis of Prescriptions of the Golden Chamber" is a classical prescription used for the treatment of heart failure nowadays. The studies of TLDZD were mainly focused on clinical practice where the formula was usually combined with other medicinal herbs. Chemical composition and cardiovascular pharmacological research of TLDZD were still insufficient. AIM OF THE STUDY: This study aimed to investigate the chemical constituents of TLDZD, evaluate the effects of TLDZD on mitochondria of myocardial cells under oxidative stress, and identify its potential cardioprotective components. MATERIALS AND METHODS: Chemical composition analysis of TLDZD was performed by ultra-performance liquid chromatography-quadrupole-time of flight-mass spectrometry. An in vitro oxidative stress model of cardiomyocytes was established by treating H9c2 cells with tert-butyl hydroperoxide (tBHP). The impact of TLDZD and its components on the production of cellular reactive oxygen species (ROS) and mitochondrial ROS (mROS), the level of malonaldehyde as well as the structure and function of mitochondria were evaluated. The effect of TLDZD on AKT/Nrf2/HO-1 signaling pathway in cardiomyocytes under oxidative stress were observed. RESULTS: Seventy-eight compounds were characterized from TLDZD, among which flavonoids, glucosinolates and phenylpropanoids were abundant, and a small number of cardiac glycosides and alkaloids also existed in TLDZD. Pretreatment with TLDZD significantly attenuated cell death, accompanied by decreased ROS and mROS production, reduced malonaldehyde level, lower mitochondrial membrane potential and adenosine triphosphate content in H9c2 cells stimulated with tBHP. The active components were mainly flavonoids of TLZ represented by quercetin-3-O-ß-D-glucose-7-O-ß-D-gentiobioside. In mechanism, the cardioprotective effect of TLDZD was proved to be associated with the activation of the AKT/Nrf2/HO-1 signaling pathway. CONCLUSIONS: The chemical profile of TLDZD was comprehensively investigated. Flavonoids with quercetin-3-O-ß-D-glucose-7-O-ß-D-gentiobioside as the representative, were the main component in TLDZD responsible for attenuating mitochondrial oxidative damage in cardiomyocytes.

Research and Development of Hydrogen-Fueled Internal Combustion Engines in China.

Energy shortages and environmental problems have brought many challenges to China's development. In the field of transport, hydrogen energy has become a new type of energy that people pay attention to due to its easy production and nonpolluting generation. The use of hydrogen as a fuel in internal combustion engines can be a good way to make a low-cost and clean conversion of the current internal combustion engine, thus realizing the application of hydrogen energy in vehicles. In this study, hydrogen-fueled internal combustion engines (HICEs) are the focus. A review and analysis of the topical issues encountered in the developmental research of HICE is presented, such as the optimization control method of the combustion process, mechanism and suppression method of abnormal combustion (preignition, backfire, knock, and high pressure rise rate in early stages of combustion), influence regularity of hydrogen injection parameters and hydrogen injection modes on the formation and combustion performance of H2-air mixture, emissions and control of NOx, formation of H2-air mixture, and combustion cycle variation, among others. Multiyear studies in the hydrogen-fueled engines clearly show that abnormal combustion, as preignition, backfire, and the blockage of intake pipe, is likely to occur at high load, and the H2 injection parameters and the injection modes possess a prominent effect on the engine's performance and the blockage of the intake pipe, which has an important impact on the preignition and backfire, and the optimal control of the combustion process is a valuable method for resolving the contradictions among inhibiting abnormal combustion, the blockage of the intake pipe, and enhancing hydrogen-fueled engine power.

Flask-like Janus Colloidal Motors with Explicit Direction and Tunable Speed.

Nanoparticles with an anisotropic morphology and composition are flourishing in various scientific fields. Their morphology has a great impact on their functions, but the precise regulation of their growth and final morphology is still challenging. Here, flask-like Janus particles (FJPs) with different compositions segmented on the inner and outer surfaces were fabricated via a sol-gel process using different silane precursors. The neck length of the flask-like particles can be controllably regulated by employing different silane precursors. The Pt catalyst was selectively loaded in their cavities, and as-formed FJPs@Pt are employed as colloidal motors. Due to the adjustable neck length, the Janus colloidal motors have explicit directionality and tunable speeds (max diffusion coefficient is 18.2 µm2 s-1).

Screening of anti-heart failure active compounds from fangjihuangqi decoction in verapamil-induced zebrafish model by anti-heart failure index approach.

Heart failure is the end stage of various cardiovascular diseases. Fangjihuangqi Decoction (FJHQD) is a famous traditional Chinese medicine (TCM) formula, which is clinically effective in the treatment of chronic heart failure. However, the anti-heart failure ingredients of FJHQD have not been clarified, and the related mechanisms of action are rarely studied. In the present study, through quantification analysis of heart rate and ventricular area changes, a heart failure model and cardiac function evaluation system in cardiomyocytes-labelled Tg (cmlc2: eGFP) transgenic zebrafish larvae were constructed, and the anti-heart failure index (AHFI) that can comprehensively evaluate the cardiac function of zebrafish was proposed. Based on this model, FJHQD, its mainly botanical drugs, components and ingredients were evaluated for the anti-heart failure effects. The results showed that FJHQD and its botanical drugs exhibited potent anti-heart failure activity. Furthermore, total alkaloids from Stephania tetrandra S. Moore, total flavonoids from Astragalus mongholicus Bunge and total flavonoids from Glycyrrhiza uralensis Fisch. ex DC. were identified to be the main components exerting the anti-heart failure activity of FJHQD. Then, we screened the main ingredients of these components, and glycyrrhizic acid, licochalcone A and calycosin were found to exhibit excellent cardioprotective effects. Finally, we found that FJHQD, glycyrrhizic acid, licochalcone A and calycosin may improve cardiac function in zebrafish by regulating oxidative stress, inflammatory response and apoptosis-related pathways. Taken together, our findings offer biological evidences toward the anti-heart failure effect of FJHQD, and provide guidance for the clinical application of FJHQD.

Single-Hole Janus Hollow Sphere.

Cross-linked epoxy resin (EP) single-hole Janus hollow spheres are prepared by cross-linking induced phase separation within an emulsion droplet and selective modification. The droplet is composed of an EP oligomer, toluene, and hexadecane. 2-Ethyl-4-methylimidazole is used as the cross-linker added to the aqueous phase. During the cross-linking, hexadecane forms an eccentric core in the cross-linked EP sphere. A single hole forms across the shell after dissolving the solvents, and a single-hole hollow sphere is achieved. The hole and cavity size are controlled by adjusting the solvent content and cross-linker concentration. Furthermore, frozen wax is used as the core material instead of hexadecane to effectively protect the sphere's interior surface. Selective modification of the exterior and interior surfaces is thus permitted. As an example, a responsive single-hole Janus hollow sphere is prepared by the favorable growth of a silica-polyoxyethylene composite layer onto the exterior surface and a selective grafting of poly(2-diethylaminoethyl methacrylate) (PDEAEMA) by atom-transfer radical polymerization (ATRP) onto the interior. The Janus sphere is water-dispersible and controllably captures and releases oil from the aqueous environment as triggered by the pH value.

Efficient Tuning of the Spin-Orbit Torque via the Magnetic Phase Transition of FeRh.

The understanding and control of the spin-orbit torque (SOT) are central to antiferromagnetic spintronics. Despite the fact that a giant SOT efficiency has been achieved in numerous materials, its efficient tuning in a given material has not been established. Materials with magnetic phase transitions (MPTs) offer a new perspective, as the SOT efficiency may vary significantly for the different magnetic orderings across the transition, and the transition itself can be readily tuned by various control parameters. This work reports that the SOT efficiency of a FeRh-based perpendicular magnetized heterostructure can be significantly tuned by varying the temperature across the MPT. The SOT efficiency exhibits a temperature hysteresis associated with the first-order nature of the MPT, and its value in the ferromagnetic phase is seen to be enhanced by ∼450%, simply by a lowering of temperature to drive FeRh into the antiferromagnetic phase. Furthermore, current-induced magnetization switching can be achieved without an assistant magnetic field for both ferromagnetic and antiferromagnetic FeRh, with a low critical switching current density for the latter. These results not only directly establish FeRh as an efficient spin generator but also present a strategy to dynamically tune SOT via varying the temperature across MPTs.

Spontaneous Lithiation of Binary Oxides during Epitaxial Growth on LiCoO2.

Epitaxial growth is a powerful tool for synthesizing heterostructures and integrating multiple functionalities. However, interfacial mixing can readily occur and significantly modify the properties of layered structures, particularly for those containing energy storage materials with smaller cations. Here, we show a two-step sequence involving the growth of an epitaxial LiCoO2 cathode layer followed by the deposition of a binary transition metal oxide. Orientation-controlled epitaxial synthesis of the model solid-state-electrolyte Li2WO4 and anode material Li4Ti5O12 occurs as WO3 and TiO2 nucleate and react with Li ions from the underlying cathode. We demonstrate that this lithiation-assisted epitaxy approach can be used for energy materials discovery and exploring different combinations of epitaxial interfaces that can serve as well-defined model systems for mechanistic studies of energy storage and conversion processes.