Piezo-Acoustic Resistive Switching Behaviors in High-Performance Organic-Inorganic Hybrid Perovskite Memristors.

Memristors are regarded as promising candidates for breaking the problems including high off-chip memory access delays and the hash rate cost of frequent data moving induced by algorithms for data-intensive applications of existing computational systems. Recently, organic-inorganic halide perovskites (OIHPs) have been recognized as exceptionally favorable materials for memristors due to ease of preparation, excellent electrical conductivity, and structural flexibility. However, research on OIHP-based memristors focuses on modulating resistive switching (RS) performance through electric fields, resulting in difficulties in moving away from complex external circuits and wire connections. Here, a multilayer memristor has been constructed with eutectic gallium and indium (EGaIn)/ MAPbI3 /poly(3,4-ethylenedioxythiophene): poly(4-styrenesulphonate) (PEDOT: PSS)/indium tin oxide (ITO) structure, which exhibits reproducible and reliable bipolar RS with low SET/RESET voltages, stable endurance, ultrahigh average ON/OFF ratio, and excellent retention. Importantly, based on ion migration activated by sound-driven piezoelectric effects, the device exhibits a stable acoustic response with an average ON/OFF ratio greater than 103 , thus realizing non-contact, multi-signal, and far-field control in RS modulation. This study provides a single-structure multifunctional memristor as an integrated architecture for sensing, data storage, and computing.

Growth and High-Performance Photodetectors of CsPbBr3 Single Crystals.

Organic-inorganic hybrid perovskites have demonstrated exceptional photovoltaic properties, making them highly promising for solar cells and photodetectors (PDs). However, the organic components of these materials are vulnerable to heat and strong light illumination, limiting their application prospects. All-inorganic cesium-based perovskite PDs, on the other hand, possess enhanced thermal tolerance and stability, making them ideal for perovskite applications. The utilization of a ternary mixture solvent and additives in combination with single crystal (SC) growth has enabled the production of highly crystalline SCs with a defect density of 3.79 × 109 cm-3. The performance of the SC PDs had been evaluated using metal-semiconductor-metal devices, which demonstrated excellent results with a dark current as low as 0.198 µA at 10 V bias, on-off ratios exceeding 103, and a response time of shorter than 1 ms.

Construction of Bi-Enzyme Self-Assembly Clusters Based on SpyCatcher/SpyTag for the Efficient Biosynthesis of (R)-Ethyl 2-hydroxy-4-phenylbutyrate.

Cascade reactions catalyzed by multi-enzyme systems are important in science and industry and can be used to synthesize drugs and nutrients. In this study, two types of macromolecules of bi-enzyme self-assembly clusters (BESCs) consisting of carbonyl reductase (CpCR) and glucose dehydrogenase (GDH) were examined. Stereoselective CpCR and GDH were successfully fused with SpyCatcher and SpyTag, respectively, to obtain four enzyme modules, namely: SpyCatcher-CpCR, SpyCatcher-GDH, SpyTag-CpCR, and SpyTag-GDH, which were covalently coupled in vitro to form two types of hydrogel-like BESCs: CpCR-SpyCatcher-SpyTag-GDH and GDH-SpyCatcher-SpyTag-CpCR. CpCR-SpyCatcher-SpyTag-GDH showed a better activity and efficiently converted ethyl 2-oxo-4-phenylbutyrate (OPBE) to ethyl(R)2-hydroxy-4-phenylbutanoate ((R)-HPBE), while regenerating NADPH. At 30 °C and pH 7, the conversion rate of OPBE with CpCR-SpyCatcher-SpyTag-GDH as a catalyst reached 99.9%, with the ee% of (R)-HPBE reaching above 99.9%. This conversion rate was 2.4 times higher than that obtained with the free bi-enzyme. The pH tolerance and temperature stability of the BESCs were also improved compared with those of the free enzymes. In conclusion, bi-enzyme assemblies were docked using SpyCatcher/SpyTag to produce BESCs with a special structure and excellent catalytic activity, improving the catalytic efficiency of the enzyme.

Simulation on a dispersion-managed 4H-SiC on insulator waveguide for infrared supercontinuum generation.

We demonstrate infrared supercontinuum generation in 4H-SiC on insulator slab waveguides. The effect of waveguide geometry parameters on dispersion is investigated to switch the zero-dispersion wavelength close to the pump wavelength. The 1 cm long 4H-SiC waveguide is pumped by 100 fs pulses at 1550 nm with 2000 W peak power, and the generated supercontinuum extends from ∼1000 to ∼3560n m (at 20 dB level). This work shows that 4H-SiC has significant potential as on-chip photonic sources for spectroscopic applications in infrared wavelengths.

Efficient Synthesis of Key Chiral Intermediate in Painkillers (R)-1-[3,5-Bis(trifluoromethyl)phenyl]ethanamine by Bienzyme Cascade System with R-ω-Transaminase and Alcohol Dehydrogenase Functions.

(R)-1-[3,5-bis(trifluoromethyl)phenyl]ethanamine, a key chiral intermediate of selective tetrodotoxin-sensitive blockers, was efficiently synthesized by a bienzyme cascade system formed by with R-ω-transaminase (ATA117) and an alcohol dehydrogenase (ADH) co-expression system. Herein, we report that the use of ATA117 as the biocatalyst for the amination of 3,5-bistrifluoromethylacetophenone led to the highest efficiency in product performance (enantiomeric excess > 99.9%). Moreover, to further improve the product yield, ADH was introduced into the reaction system to promote an equilibrium shift. Additionally, bienzyme cascade system was constructed by five different expression systems, including two tandem expression recombinant plasmids (pETDuet-ATA117-ADH and pACYCDuet-ATA117-ADH) and three co-expressed dual-plasmids (pETDuet-ATA117/pET28a-ADH, pACYCDuet-ATA117/pET28a-ADH, and pACYCDuet-ATA117/pETDuet-ADH), utilizing recombinant engineered bacteria. Subsequent studies revealed that as compared with ATA117 single enzyme, the substrate handling capacity of BL21(DE3)/pETDuet-ATA117-ADH (0.25 g wet weight) developed for bienzyme cascade system was increased by 1.50 folds under the condition of 40 °C, 180 rpm, 0.1 M pH9 Tris-HCl for 24 h. To the best of our knowledge, ours is the first report demonstrating the production of (R)-1-[3,5-bis(trifluoromethyl)phenyl]ethanamine using a bienzyme cascade system, thus providing valuable insights into the biosynthesis of chiral amines.

High Temperature CsPbBrxI3-x Memristors Based on Hybrid Electrical and Optical Resistive Switching Effects.

The emergence of perovskite-based memristors associated with the migration of ions has attracted attention for use in overcoming the limitations of the von Neumann computing architecture and removing the bottleneck of storage density. However, systematic research on the temperature dependence of halide perovskite-based memristors is still required due to the unavoidable thermal stability limits. In this work, mixed halide CsPbBrxI3-x-based (X = 0, 1, 2) memristors with unique electrical and optical resistive switching properties in an ambient atmosphere from room temperature to a 240 °C maximum have been successfully achieved. At room temperature, the CsPbBrxI3-x-based memristors exhibit outstanding resistive switching behaviors such as ultralow operating voltage (∼0.81, ∼0.64, and ∼0.54 V for different devices, respectively), moderate ON/OFF ratio (∼102), stable endurance (103 cycles), and long retention time (104 s). The CsPbBrxI3-x-based memristors maintain excellent repeatability and stability at high temperature. Endurance failures of CsPbI3, CsPbBrI2, and CsPbBr2I memristors occur at 90, 150, and 270 °C, respectively. Finally, nonvolatile imaging employing CsPbBr2I-based memristor arrays based on the electrical-write and optical-erase operation at 100 °C has been demonstrated. This study provides utilization potentiality in the high temperature scenarios for perovskite wearable and large-scale information devices.

Asymmetric Domino Heck/Dearomatization Reaction of ß-Naphthols to Construct Indole-Terpenoid Frameworks.

A palladium-catalyzed enantioselective Heck cyclization/dearomatization cascade via capturing the cyclized Heck π-allylpalladium intermediate by ß-naphthols is reported, which provides a new strategy for the construction of chiral indole-terpenoid frameworks. This method affords indole-functionalized ß-naphthalenone compounds bearing an all-carbon-substituted quaternary chiral center in excellent yields (up to 92%) and enantioselectivities (up to 94% ee). In addition, the utility of this method is showcased by the gram-scale syntheses and diverse transformations of the dearomatized products.

High-Performance Flexible Asymmetric Supercapacitor Based on CoAl-LDH and rGO Electrodes.

A flexible asymmetric supercapacitor (ASC) based on a CoAl-layered double hydroxide (CoAl-LDH) electrode and a reduced graphene oxide (rGO) electrode was successfully fabricated. The CoAl-LDH electrode as a positive electrode was synthesized by directly growing CoAl-LDH nanosheet arrays on a carbon cloth (CC) through a facile hydrothermal method, and it delivered a specific capacitance of 616.9 F g-1 at a current density of 1 A g-1. The rGO electrode as a negative electrode was synthesized by coating rGO on the CC via a simple dip-coating method and revealed a specific capacitance of 110.0 F g-1 at a current density of 2 A g-1. Ultimately, the advanced ASC offered a broad voltage window (1.7 V) and exhibited a high superficial capacitance of 1.77 F cm-2 at 2 mA cm-2 and a high energy density of 0.71 mWh cm-2 at a power density of 17.05 mW cm-2, along with an excellent cycle stability (92.9% capacitance retention over 8000 charge-discharge cycles).

Metal-free N-doped carbon nanofibers as an efficient catalyst for oxygen reduction reactions in alkaline and acid media.

The development of metal-free catalysts to replace the use of Pt has played an important role in relation to its application to fuel cells. We report N-doped carbon nanofibers as the catalyst of an oxygen reduction reaction, which were synthesized via carbonizing bacterial cellulose-polypyrrole composites. The as-prepared material exhibited remarkable catalytic activity toward the oxygen reduction reaction with comparable onset potential and the ability to limit the current density of commercial Pt/C catalysts in both alkaline and acid media due to the unique porous three-dimensional network structure and the doped nitrogen atoms. The effect of N functionalities on catalytic behavior was systematically investigated. The results demonstrated that pyridinic-N was the dominating factor for catalytic performance toward the oxygen reduction reaction. Additionally, N-doped carbon nanofibers also demonstrated excellent cycling stability (93.2% and 89.4% retention of current density after chronoamperometry 20 000 s in alkaline and media, respectively), obviously superior to Pt/C.

Large Scale Synthesis of NiCo Layered Double Hydroxides for Superior Asymmetric Electrochemical Capacitor.

We report a new environmentally-friendly synthetic strategy for large-scale preparation of 16 nm-ultrathin NiCo based layered double hydroxides (LDH). The Ni50Co50-LDH electrode exhibited excellent specific capacitance of 1537 F g(-1) at 0.5 A g(-1) and 1181 F g(-1) even at current density as high as 10 A g(-1), which 50% cobalt doped enhances the electrical conductivity and porous and ultrathin structure is helpful with electrolyte diffusion to improve the material utilization. An asymmetric ultracapacitor was assembled with the N-doped graphitic ordered mesoporous carbon as negative electrode and the NiCo LDH as positive electrode. The device achieves a high energy density of 33.7 Wh kg(-1) (at power density of 551 W kg(-1)) with a 1.5 V operating voltage.