Synthesis and fluoride-promoted wittig rearrangements of alpha-alkoxysilanes

[formula: see text] Lewis acid-catalyzed reaction of allyl and benzyl trichloroacetimidates with alpha-silyl alcohols was found to be a general method for the synthesis of alpha-alkoxysilanes. Upon exposure to CsF, these alpha-alkoxysilanes could be made to undergo [2,3]-Wittig rearrangement with an efficiency similar to that realized by the analogous but inherently more toxic alpha-alkoxystannanes.     

Widely tunable, narrow-linewidth, subnanosecond pulse generation in an electronically tuned Ti:sapphire laser

Widely tunable subnanosecond Ti:sapphire laser radiation pumped with a cw Q -switched laser-diode-pumped Nd:YAG laser has been demonstrated in a simple laser system with a configuration of variable cavity length. Laser wavelengths can be continuously tuned by adjustment of the rf of an intracavity acousto-optic tunable filter with a computer through the whole range of the laser gain. During tuning of the whole spectral range, there is no need to realign any optics in the laser, except for moving the mirror to track the change of the rf. The peak powers of the output pulses at a pump level of 300 mW are comparable with those of conventional tunable picosecond Ti:sapphire lasers at a cw pump level of almost 10 W.     

基于视景仿真的航炮弹道仿真系统研究

根据航炮多体系统动力学计算结果和二维弹道数值计算方法，运用虚拟仿真技术建立了一套可完成弹道解算、仿真及射击精度分析的可视化演示平台。平台的构建过程中探索了虚拟场景中空间数字模型和碰撞模型的构建方法，用以更简洁、高效的驱动特定虚拟场景进行仿真。此平台可以引入动力学计算的结果．较为真实的仿真航炮射击实验现场，并演示炮弹飞行轨迹及结果。     

KAM tori of Hamiltonian perturbations of 1D linear beam equations

In this paper, one-dimensional (1D) nonlinear beam equations

     

New modeling method and mechanism analyses for active control of interior noise in an irregular enclosure using piezoelectric actuators

A new modeling method is developed in this paper for the active minimization of noise within a three-dimensional irregular enclosure using distributed lead zirconate titanate piezoelectric (PZT) actuators, and the control mechanisms for irregular enclosure are analyzed. The irregular enclosure is modeled with four rigid walls and two simply supported flexible panels, and PZT actuators are bound to one of the flexible panels. The process of the new modeling method is as follows. First, the modal coupling method is used to establish the motion equations, which contain important coefficients such as modal masses and modal coupling coefficients, etc., of acoustic-structural-piezoelectric coupling system. Then, the acoustic modes and the modal masses of irregular enclosure are calculated by numerical methods. Last, the modal coupling coefficients in motion equations are calculated according to the numerical results of the acoustic modes of irregular enclosure and the modes of two panels. The validity of this modeling method is verified by a regular hexahedron enclosure. Two cost functions are applied to this model. With the two cost functions, good results are obtained in minimizing the sound-pressure level (SPL) within irregular enclosure according to numerical investigations. By comparing the results obtained under controlled and uncontrolled states, the control mechanisms of the system are discussed. It is found that the control mechanisms vary with disturbance frequencies. At most disturbance frequencies, the SPL within enclosure is reduced by restructuring the modes of two panels simultaneously. When the disturbance frequency comes close to one of the natural frequencies of panel a, the dominant mode of panel a is suppressed, while the modes of panel b are reconstructed. While the disturbance frequency is near one of the natural frequencies of panel b, the modes of two panels are restructured at the same time.     

硅基微显示技术

使用硅基微显示技术制造的显示器具有尺寸小、低功耗、图像大的特点,特别适用于移动式个人显示器的投影系统。在各类硅基微显示器中,硅基液晶微显具有明显优势。本文介绍了主要微显示技术及其应用产品,同时分析了微显市场,概述了微显技术在中国的发展。     

Error of One-leg Methods for Singular Perturbation Problems with Delays

This paper is concerned with the error behaviour of one-leg methods applied to some classes of one-parameter multiple stiff singularly perturbed problems with delays. We derive the global error estimates of A-stable one-leg methods with linear interpolation procedure.     

Ferroelectrics-Electret Synergetic Organic Artificial Synapses with Single-Polarity Driven Dynamic Reconfigurable Modulation

Most current studies of artificial synapses only mimic the static plasticity, which is far from achieving the complex behaviors of the human brain. The few reported dynamic reconfigurable synapses based on ambipolar transistors switch the operating states by voltages with opposite polarity, which impedes the development of highly efficient synaptic readout circuits. To improve the efficiency, flexibility, and biocompatibility of dynamic reconfigurable synapses, here a ferroelectrics-electret synergetic organic synaptic p-type transistor (FESOST) is devised. Owing to the synergetic action of ferroelectric polarization switching and charge capture, FESOST exhibits single-polarity driven dynamic reconfigurable operating states with different synaptic behaviors (potentiation and depression) in response to the same gate pulse in different modes (excitatory and inhibitory). In addition, various single-polarity driven synaptic behaviors including short-term/long-term plasticity, paired-pulse facilitation/depression, spike-rate-dependent plasticity, and spike-number-dependent plasticity are also simulated. Finally, the reconfigurable artificial temperature perception system is simulated for the complex emotions of humans in response to different weather stimuli for people of different constitutions. The novel device architecture represents a major step forward in the development of dynamic, reconfigurable, high-efficiency, organic synapses.     

Zwitterionic Electrochemiluminescence Biointerface Contributes to Label-Free Monitoring of Exosomes Dynamics in a Fluidic Microreaction Device

The competence to construct sensing platforms capable of selective manipulation in complex biological fluids undoubtedly underpins critical future advances in healthcare. Despite the fact that electrochemiluminescence (ECL) has long been an influential technology for clinical diagnosis worldwide, ECL interface that optimizes fouling resistance has been mimicked less often, especially in an integrated platform. Herein, ECL transducer is prepared by the integration of protonated g-C₃N₄ and Ti₃C₂T_x MXene nanosheets, displaying enhanced charge injection/transfer, and inherent catalytic capacities for coreactant ECL. Mussel-bioinspired polydopamine was exploited as a thin, surface-adherent substrate to coat the solid-state transducer and further initiate secondary reactions via Michael Addition for tailing recognition element and zwitterionic segment. This architecture guarantees not only the least suppression of ECL performance but also desired antifouling properties, ensuring < 7.45% of ECL loss after 96 h of exposure to complex biological fluids. Creatively, a highly integrated platform is equipped with the established biointerface, gas diffusion electrode, and fluidic ECL microreactor, affording high-performance exosome checking and dynamics tracking in a non-label manner. Our study provides a general design strategy to obtain a robust antifouling ECL sensing interface based on zwitterionic chemistries and provides a fresh perspective in developing point-of-care and implantable ECL devices.     

Multi-Stage Porous Nickel–Iron Oxide Electrode for High Current Alkaline Water Electrolysis

Alkaline water electrolysis (AWE) is the promising technical pathway of large-scale green hydrogen production. The sluggish oxygen evolution reaction seriously hampers the water decomposition reaction kinetics for AWE, especially at high current density above 500 mA cm⁻². It is closely related with bubbles removal dynamic performance of porous electrodes. In this study, the multi-stage porous nickel–iron oxide electrode is prepared by a two-step electro-deposition method. The electrode shows good oxygen evolution reaction performance at high current densitiy of 1000 mA cm⁻², which is attributed to both the good electro-catalytic performance of NiFeO_x with nano-cone structure and good bubbles removal performance of porous Ni interlayer with the curved pore channels. Bubbles motion inside the pore channels is deeply analyzed by Lattice Boltzmann simulation of gas–liquid two-phase flows, combining with the experiments. The results indicate that bubbles motion speed is faster in curved pore channels than that in straight pore channels due to the role of bubble buoyancy. It illuminates the effects of pore channel curvature on bubbles motion for porous electrodes prepared by electro-deposition. It provides the possibility of designing porous electrodes with both good electro-catalytic performance and good bubbles removal performance by the electro-deposition method, from the view of industrial applications.