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The tail probability of a function of a multivariate random variable is not easy to estimate by the crude Monte Carlo simulation. When the occurrence of the function value over a threshold is rare, the accurate estimation of the corresponding probability requires a huge number of samples. When the explicit form of the cumulative distribution function of each component of the variable is known, the inverse transform likelihood ratio method is directly applicable scheme to estimate the tail probability efficiently. The method is a type of the importance sampling and its efficiency depends on the selection of the importance sampling distribution. When the cumulative distribution of the multivariate random variable is represented by a copula and its marginal distributions, we develop an iterative algorithm to find the optimal importance sampling distribution, and show the convergence of the algorithm. The performance of the proposed scheme is compared with the crude Monte Carlo simulation numerically. [ABSTRACT FROM AUTHOR]

Finding suitable electrode materials is one of the challenges for the commercialization of a sodium ion battery due to its pulverization accompanied by high volume expansion upon sodiation. Here, copper sulfide is suggested as a superior electrode material with high capacity, high rate, and long-term cyclability owing to its unique conversion reaction mechanism that is pulverization-tolerant and thus induces the capacity recovery. Such a desirable consequence comes from the combined effect among formation of stable grain boundaries, semi-coherent boundaries, and solid-electrolyte interphase layers. The characteristics enable high cyclic stability of a copper sulfide electrode without any need of size and morphological optimization. This work provides a key finding on high-performance conversion reaction based electrode materials for sodium ion batteries. [ABSTRACT FROM AUTHOR]

Sodium ion batteries have been considered a promising alternative to lithium ion batteries for large-scale energy storage owing to their low cost and high natural abundance. However, the commercialization of this device is hindered by the lack of suitable anodes with an optimized morphology that ensure high capacity and cycling stability of a battery. Here, we not only demonstrate that copper sulfide nanoplates exhibit close-to-theoretical capacity (~560 mAh g–1) and long-term cyclability, but also reveal that their sodiation follows a non-equilibrium reaction route, which involves successive crystallographic tuning. By employing in situ transmission electron microscopy, we examine the atomic structures of four distinct sodiation phases of copper sulfide nanoplates including a metastable phase and discover that the discharge profile of copper sulfide directly reflects the observed phase evolutions. Our work provides detailed insight into the sodiation process of the high-performance intercalation–conversion anode material. [ABSTRACT FROM AUTHOR]

This paper provides a concise review on the recent development of nanoscale hybrid systems based on carbon nanotubes (CNTs) for biological sensing and control. CNT-based hybrid systems have been intensively studied for versatile applications of biological interfaces such as sensing, cell therapy and tissue regeneration. Recent advances in nanobiotechnology not only enable the fabrication of highly sensitive biosensors at nanoscale but also allow the applications in the controls of cell growth and differentiation. This review describes the fabrication methods of such CNT-based hybrid systems and their applications in biosensing and cell controls. [ABSTRACT FROM AUTHOR]

We developed a magnetically-refreshable receptor platform structure which can be integrated with quite versatile nano-biosensor structures to build reusable nano-biosensor chips. This structure allows one to easily remove used receptor molecules from a biosensor surface and reuse the biosensor for repeated sensing operations. Using this structure, we demonstrated reusable immunofluorescence biosensors. Significantly, since our method allows one to place receptor molecules very close to a nano-biosensor surface, it can be utilized to build reusable carbon nanotube transistor-based biosensors which require receptor molecules within a Debye length from the sensor surface. Furthermore, we also show that a single sensor chip can be utilized to detect two different target molecules simply by replacing receptor molecules using our method. Since this method does not rely on any chemical reaction to refresh sensor chips, it can be utilized for versatile biosensor structures and virtually-general receptor molecular species. [ABSTRACT FROM AUTHOR]

Thus, constant-voltage step should be avoided unless a sufficient voltage margin is maintained for high-nickel cathode materials. Mechanism of Degradation of Capacity and Charge/Discharge Voltages of High-Ni Cathode During Fast Long-Term Cycling Without Voltage Margin (Adv. Cation mixing, electrode potential, high-nickel cathodes, lithium-ion batteries, overpotential, STEM. [Extracted from the article]

The authors reveal the mechanisms of degradation of capacity, charge voltage, and discharge voltage of commercially‐available high‐nickel cathode material when it is cycled without a voltage margin by two different charge protocols: constant‐current charging and constant‐current, constant‐voltage charging. With repeated constant‐current charging, the cathode material changes to a non‐periodic cation‐mixed state, which causes a relatively low voltage degradation, whereas during constant‐current, constant‐voltage charging, the cathode material changes from a layered structure to a periodic cation‐mixed spinel‐like phase, with consequent severe voltage decay. This decay results from a reduction in the equilibrium electrode potential and an increase of overpotential which are aggravated in a periodic cation‐mixed state. The findings provide insights into the use of excess Li without charge‐voltage margin in high‐Ni cathode materials. [ABSTRACT FROM AUTHOR]

A new class of artificial receptor underlying surfacedominated switching dynamics successfully mimics key parameters of the biological receptor, including short-latency, selective response, and tunability. B Artificial Adaptive and Maladaptive Sensory Receptors b In article number 2103484, Chong-Yun Kang, Jung Ho Yoon, and co-workers implement artificial adaptive and maladaptive sensory receptors using a diffusive memristor as a biological counterpart of the somatosensory system in all vertebrates. Artificial Adaptive and Maladaptive Sensory Receptors Based on a Surface-Dominated Diffusive Memristor (Adv. Sci. 4/2022). [Extracted from the article]

B Artificial Adaptive and Maladaptive Sensory Receptors b In article number 2103484, Chong-Yun Kang, Jung Ho Yoon, and co-workers implement artificial adaptive and maladaptive sensory receptors using a diffusive memristor as a biological counterpart of the somatosensory system in all vertebrates. Artificial Adaptive and Maladaptive Sensory Receptors Based on a Surface-Dominated Diffusive Memristor (Adv. Sci. 4/2022) A new class of artificial receptor underlying surfacedominated switching dynamics successfully mimics key parameters of the biological receptor, including short-latency, selective response, and tunability. [Extracted from the article]

Artificial Adaptive and Maladaptive Sensory Receptors Based on a Surface-Dominated Diffusive Memristor (Adv. Sci. 4/2022) A new class of artificial receptor underlying surfacedominated switching dynamics successfully mimics key parameters of the biological receptor, including short-latency, selective response, and tunability. B Artificial Adaptive and Maladaptive Sensory Receptors b In article number 2103484, Chong-Yun Kang, Jung Ho Yoon, and co-workers implement artificial adaptive and maladaptive sensory receptors using a diffusive memristor as a biological counterpart of the somatosensory system in all vertebrates. [Extracted from the article]

A biological receptor serves as sensory transduction from an external stimulus to an electrical signal. It allows humans to better match the environment by filtering out repetitive innocuous information and recognize potentially damaging stimuli through key features, including adaptive and maladaptive behaviors. Herein, for the first time, the authors develop substantial artificial receptors involving both adaptive and maladaptive behaviors using diffusive memristor. Metal‐oxide nanorods (NR) as a switching matrix enable the electromigration of an active metal along the surface of the NRs under electrical stimulation, resulting in unique surface‐dominated switching dynamics with the advantage of fast Ag migration and fine controllability of the conductive filament. To experimentally demonstrate its potential application, a thermoreceptor system is constructed using memristive artificial receptors. The proposed surface‐dominated diffusive memristor allows the direct emulation of the biological receptors, which represents an advance in the bioinspired technology adopted in creating artificial intelligence systems. [ABSTRACT FROM AUTHOR]

A biological receptor serves as sensory transduction from an external stimulus to an electrical signal. It allows humans to better match the environment by filtering out repetitive innocuous information and recognize potentially damaging stimuli through key features, including adaptive and maladaptive behaviors. Herein, for the first time, the authors develop substantial artificial receptors involving both adaptive and maladaptive behaviors using diffusive memristor. Metal‐oxide nanorods (NR) as a switching matrix enable the electromigration of an active metal along the surface of the NRs under electrical stimulation, resulting in unique surface‐dominated switching dynamics with the advantage of fast Ag migration and fine controllability of the conductive filament. To experimentally demonstrate its potential application, a thermoreceptor system is constructed using memristive artificial receptors. The proposed surface‐dominated diffusive memristor allows the direct emulation of the biological receptors, which represents an advance in the bioinspired technology adopted in creating artificial intelligence systems. [ABSTRACT FROM AUTHOR]

A biological receptor serves as sensory transduction from an external stimulus to an electrical signal. It allows humans to better match the environment by filtering out repetitive innocuous information and recognize potentially damaging stimuli through key features, including adaptive and maladaptive behaviors. Herein, for the first time, the authors develop substantial artificial receptors involving both adaptive and maladaptive behaviors using diffusive memristor. Metal‐oxide nanorods (NR) as a switching matrix enable the electromigration of an active metal along the surface of the NRs under electrical stimulation, resulting in unique surface‐dominated switching dynamics with the advantage of fast Ag migration and fine controllability of the conductive filament. To experimentally demonstrate its potential application, a thermoreceptor system is constructed using memristive artificial receptors. The proposed surface‐dominated diffusive memristor allows the direct emulation of the biological receptors, which represents an advance in the bioinspired technology adopted in creating artificial intelligence systems. [ABSTRACT FROM AUTHOR]

Spin-orbit coupling effect in structures with broken inversion symmetry, known as the Rashba effect, facilitates spin-orbit torques (SOTs) in heavy metal/ferromagnet/oxide structures, along with the spin Hall effect. Electric-field control of the Rashba effect is established for semiconductor interfaces, but it is challenging in structures involving metals owing to the screening effect. Here, we report that the Rashba effect in Pt/Co/AlOx structures is laterally modulated by electric voltages, generating out-of-plane SOTs. This enables field-free switching of the perpendicular magnetization and electrical control of the switching polarity. Changing the gate oxide reverses the sign of out-of-plane SOT while maintaining the same sign of voltage-controlled magnetic anisotropy, which confirms the Rashba effect at the Co/oxide interface is a key ingredient of the electric-field modulation. The electrical control of SOT switching polarity in a reversible and non-volatile manner can be utilized for programmable logic operations in spintronic logic-in-memory devices. A major challenge for spin based electronics is the electrical control of magnetization. Here, Kang et al demonstrate how electric field control of the Rashba effect in a Pt/Co/AlOx can enable control of the spin-orbit torque and allow for field free switching of the magnetization. [ABSTRACT FROM AUTHOR]

The development of high-tap density electrode materials that can simultaneously achieve stable electrochemical performance at high charge/discharge rates is critically in demand. Herein, we propose an innovative material design that can offer high tap density and excellent rate capabilities by using Co3O4 nanograin-interconnected secondary particles (Co3O4 NISPs). By taking advantage of a conversion reaction that forms Co from Co3O4, we demonstrate that Co3O4 NISPs are capable of creating a number of metallic Co sites along with a number of vacant sites in-between nanograins. Electrochemical tests that reveal reduced internal cell resistance and more accessible Li diffusion are achieved for Co3O4 NISPs compared with Co3O4 nanoparticles (NPs). Additionally, in situ X-ray diffraction (XRD) analyses, electron energy loss spectroscopy (EELS), and density functional theory (DFT) calculations reveal that the insulating intermediate product (CoO) is formed less on the Co3O4 NISPs, which can enhance the charge transport. Attributed to the combinatorial effects of Co3O4 nanograins that form metallic Co upon conversion and secondary particles that enable high tap density, Co3O4 NISPs show the most outstanding volumetric capacity (2167.3 mA h cm−3 at a current density of 500 mA g−1) among spinel-type metal oxide electrode materials researched so far. [ABSTRACT FROM AUTHOR]

The development of high performance and cost-effective electrode materials is the main challenge for the commercialization of sodium ion batteries. Here, we suggest a substantial iron-doped sodium vanadium fluorophosphate and sodium vanadium phosphate composite as a promising cathode. Iron substitution enhances ionic diffusivity and lowers the bandgap, and, thus, improves sodium storage performance. The origin of the enhanced performance is investigated employing in situ X-ray diffraction, ex situ X-ray photoelectron spectroscopy, density functional theory calculation, and electrochemical characterization. Moreover, we demonstrate its full cell configuration with earth-abundant element-based copper sulfide anodes. The suggested cathode and sodium ion battery full cell exhibits well-balanced sodium storage performance in terms of energy density, C-rate capability, cycling stability, and low cost. The low cost and high performance of the full cell make it an attractive choice for energy storage systems and high power applications to support lithium ion batteries. [ABSTRACT FROM AUTHOR]

Graphene liquid cell transmission electron microscopy allows in situ observation of nanomaterial dynamics in a liquid environment. However, this method suffers from both random formation and small size of liquid pockets. Here, we introduce facile and mass-producible graphene-sealed well-type liquid cells with rational designs. The developed liquid cell structure and its formation mechanism depending on hole diameter (d)/spacer thickness (h) ratio are systematically analyzed. Finally, we show its high-resolution imaging and chemical analysis capability for nanoparticles and biomaterial applications. This work will provide an enhanced liquid cell platform for diverse liquid environmental studies. [ABSTRACT FROM AUTHOR]

Demand for pragmatic alternatives to carbon-intensive fossil fuels is growing more strident. Hydrogen represents an ideal zero-carbon clean energy carrier with high energy density. For hydrogen fuel to compete with alternatives, safe and high capacity storage materials that are readily cycled are imperative. Here, development of such a material, comprised of nickel-doped Mg nanocrystals encapsulated by molecular-sieving reduced graphene oxide (rGO) layers, is reported. While most work on advanced hydrogen storage composites to date endeavor to explore either nanosizing or addition of carbon materials as secondary additives individually, methods to enable both are pioneered: 'dual-channel' doping combines the benefits of two different modalities of enhancement. Specifically, both external (rGO strain) and internal (Ni doping) mechanisms are used to efficiently promote both hydriding and dehydriding processes of Mg nanocrystals, simultaneously achieving high hydrogen storage capacity (6.5 wt% in the total composite) and excellent kinetics while maintaining robustness. Furthermore, hydrogen uptake is remarkably accomplished at room temperature and also under 1 bar-as observed during in situ measurements-which is a substantial advance for a reversible metal hydride material. The realization of three complementary functional components in one material breaks new ground in metal hydrides and makes solid-state materials viable candidates for hydrogen-fueled applications. [ABSTRACT FROM AUTHOR]

Herein, the dynamics of oxidative etching of Ag nanoparticles in an ionic liquid is monitored in situ via graphene liquid cell transmission electron microscopy. The results reveal that hollow nanosphere formation occurs via a stepwise process involving shell formation and hollowing of the nanoparticle. In addition, we describe the different etching kinetics in each step. [ABSTRACT FROM AUTHOR]

The practical application of piezoelectric ceramics is applied not only under low electric fields. Therefore, an examination for characteristics of piezoelectric ceramics under high electric fields can contribute to reducing the susceptibility of multifarious applications and to facilitating production of control circuits. These contributions can lead to the expansion of industrial applications. In this research, we fabricated disk-type piezoelectric ceramic samples using conventional methods, measured the resonance characteristics of these samples from low to high voltages driving conditions, and calculated the piezoelectric constants. Resonance frequency and voltage reduction ratio decreased steeply in the specific input voltage sections in PZT-PMNS ceramics. [ABSTRACT FROM AUTHOR]

The stress inevitably imposed during electrochemical reactions is expected to fundamentally affect the electrochemistry, phase behavior and morphology of electrodes in service. Here, we show a strong stress-composition coupling in lithium binary alloys during the lithiation of tin-tin oxide core-shell nanoparticles. Using in situ graphene liquid cell electron microscopy imaging, we visualise the generation of a non-uniform composition field in the nanoparticles during lithiation. Stress models based on density functional theory calculations show that the composition gradient is proportional to the applied stress. Based on this coupling, we demonstrate that we can directionally control the lithium distribution by applying different stresses to lithium alloy materials. Our results provide insights into stress-lithium electrochemistry coupling at the nanoscale and suggest potential applications of lithium alloy nanoparticles. Electrochemical reactions can generate stresses that detrimentally affect battery electrodes. Here, the authors directly image the lithiation of core-shell tin-based nanoparticles and show that lithium can be redistributed by applying stress and change the nanoparticle composition. [ABSTRACT FROM AUTHOR]