Macro Meso Response and Stress Wave Propagation Characteristics of MCT High-Voltage Switch Under Shock load

In order to study the dynamic and electrical coupling response characteristics of Metal Oxide Semiconductor Controlled Thyristor(MCT)high-voltage switch under the synergic action of mechanical load and high voltage,the separated Hopkinson pressure bar(SHPB)test system was used to simulate different impact load environments,and combined with the multi-layer high-voltage ceramic capacitor charging and discharging system,the instantaneous electrical signals of MCT high-voltage switch were collected.Combined with numerical simulation and theoretical analysis,the failure mode and stress wave propagation characteristics of MCT high voltage switch were determined.The mechanical and electrical coupling response characteristics and failure mechanism of MCT high voltage switch under dynamic load were revealed from macroscopic and microscopic levels.The results show that the damage modes of MCT high-voltage switches can be divided into non-functional damage,recoverable functional damage,non-recoverable damage and structural damage.Due to the gap between the metal gate and the oxide layer,the insulating oxide layer was charged.After placing for a period of time,the elastic deformation of the metal gate partially recovered and the accumulated charge disappeared,which induced the recoverable functional damage failure of the device.In addition,obvious cracks appeared on both sides of the monocrystalline silicon inside the MCT high-voltage switch,leading to unrecoverable damage of the device.

Effects of minocycline on apoptosis and angiogenesis-related protein expression in a rat model of intracerebral hemorrhage

In the present study, a rat model of non-traumatic intracerebral hemorrhage was established by type IV collagenase injection into the right globus pallidus. Bax and Bcl-2 expression in tissues surrounding hematomas was significantly increased within 14 days after injury, and it then gradually decreased. Vascular endothelial growth factor, Flk-1 and Flt-1 mRNA expression gradually increased over time. After intraperitoneal injection with minocycline, Bax expression was decreased 1 day after intracerebral hemorrhage. Flk-1 and Flt-1 mRNA expression was decreased after minocycline injection, but Bcl-2 expression was increased, and vascular endothelial growth factor mRNA expression was decreased between 4-14 days. These results indicated that protective effects of minocycline on nerve tissues were associated with increased Bcl-2 expression and decreased Bax expression in the early stage after intracerebral hemorrhage. In the late stage, minocycline downregulated vascular endothelial growth factor and its receptor expression to inhibit brain tissue self-repair.

Preparation,Characterization and Application of Mesoporous Carbon Materials Derived from MgO Template for Removal of Heavy Metals

Mesoporous carbon adsorbents were prepared for the adsorption of Cu(Ⅱ)and Pb(Ⅱ)by calcination with gelatin,chitosan and sucrose as carbon precursor respectively,and magnesium citrate as MgO template precursor under high temperature argon atmosphere.The effects of the mass ratio of carbon precursor/magnesium citrate and calcination temperature on the adsorption performance of Cu(Ⅱ)and Pb(Ⅱ)ions were investigated.The results showed that the optimum preparation process of adsorbent was obtained as follows:gelatin was carbon precursor,and gelatin and magnesium citrate were calcined at a mass ratio of 5∶5 under argon atmosphere of 600℃for 2 h.The adsorbent exhibited mesostructure with a pore size of about 5.1 nm and a high specific surface area of 783 m^2/g.The as-synthesized adsorbent exhibited high adsorption capacity for Cu(Ⅱ)(8.3 mg/g)and Pb(Ⅱ)(28 mg/g).

千瓦级铝空电池用含Ti阳极材料的研究

随着科学技术的发展,现代工业与社会发展对电力能源的依赖程度越来越高,先进高效的能源转换技术是发展的关键,新型大功率燃料电池(如铝空气电池)因其具有能量密度高(理论能量密度8100 Wh/kg)、储量丰富、生产成本低、环保无毒等优点而受到众多学者的青睐。本工作通过对千瓦级铝空电池用含Ti阳极材料的系统研究,探明了不同Ti含量(0.03wt%,0.05wt%,0.08wt%和0.10wt%)对千瓦级铝空电池用Al-Mg-In阳极材料微观组织、腐蚀行为、电化学行为和放电行为的影响规律。结果表明,随Ti含量增加,Al-Mg-In阳极中纤维状晶粒逐渐细化,晶粒组织逐渐均匀,晶界数目增多,可以为铝空电池提供更多的反应面积。阳极材料的放电反应通道较多,放电活性也随之升高,有助于铝阳极工作电压提升。当Ti添加量超过0.05wt%时会导致Al-Mg-In阳极板材中第二相颗粒数目增多,第二相与基体之间形成“原电池”,加速合金腐蚀,晶界局部溶解从而造成合金耐蚀性能下降,放电性能降低。因此,添加0.05wt%Ti的Al-Mg-In合金具有最佳的耐蚀性和电池放电性能,说明适量的Ti可以优化铝空气电池的性能。

Retina-Inspired Organic Heterojunction-Based Optoelectronic Synapses for Artificial Visual Systems

For the realization of retina-inspired neuromorphic visual systems which simulate basic functions of human visual systems,optoelectronic synapses capable of combining perceiving,processing,and memorizing in a single device have attracted immense interests.Here,optoelectronic synaptic transistors based on tris(2-phenylpyridine)iridium(Ir(ppy)_(3))and poly(3,3-didodecylquarterthiophene)(PQT-12)heterojunction structure are presented.The organic heterojunction serves as a basis for distinctive synaptic characteristics under different wavelengths of light.Furthermore,synaptic transistor arrays are fabricated to demonstrate their optical perception efficiency and color recognition capability under multiple illuminating conditions.The wavelength-tunability of synaptic behaviors further enables the mimicry of mood-modulated visual learning and memorizing processes of humans.More significantly,the computational dynamics of neurons of synaptic outputs including associated learning and optical logic functions can be successfully demonstrated on the presented devices.This work may locate the stage for future studies on optoelectronic synaptic devices toward the implementation of artificial visual systems.

Spectrum-dependent photonic synapses based on 2D imine polymers for power-efficient neuromorphic computing

2D polymers(2DPs)have attracted increasing interests in sensors,catalysis,and gas storage applications.Furthermore,2DPs with unique band structure and tunable photophysical properties also have immense potential for application in photonic neuromorphic computing.Here,photonic synaptic transistors based on 2DPs as the light-tunable charge-trapping medium are developed for the first time.The resulted organic transistors can successfully emulate common synaptic functions,including excitatory postsynaptic current,pair-pulse facilitation,the transition of short-term memory to long-term memory,and dynamic filtering.Benefitting from the high photosensitivity of the 2DP,the devices can be operated under a low operating voltage of0.1 V,and achieve an ultralow energy consumption of~0.29 pJ per event.In addition,the heterostructure formed between the 2DP and organic semiconductor enables spectrum-dependent synaptic responses,which facilitates the simulation of visual learning and memory processes in distinct emotional states.The underlying mechanism of spectrum-dependent synaptic-like behaviors is systematically validated with in situ atomic force microscopy based electrical techniques.The spectrum-enabled tunability of synaptic behaviors further promotes the realization of optical logic functions and associative learning.This work inspires the new application of 2DPs in photonic synapses for future neuromorphic computing.

Evanescent-wave pumped single-mode microcavity laser from fiber of 125 μm diameter

A microcavity laser based on evanescent-wave-coupled gain is formed using a silica fiber with a diameter of 125 μm in a rhodamine 6G ethanol solution. When the fiber is sticking to the cuvette wall by capillary force,using the excitation of a 532 nm nanosecond pulsed laser, single-mode laser emission is observed. While increasing the distance between the fiber and the cuvette wall, the typical multi-peak whispering-gallery-mode(WGM)laser emission can also be demonstrated. On the other hand, while increasing the refractive index of the solution by mixing ethanol and ethylene glycol with different ratios as a solvent, the single-mode emission would evolve to multi-peak WGM laser emission controllably.

Lung ultrasound:a valuable tool for assessing COVID-19 patients with different severity

To the Editor:Lung ultrasound(LUS)may be a promising technique to assess lung injury from coronavirus disease 2019(COVID-19).However,the LUS characteristics and their assessment value have not been well described.We aimed to explore the LUS characteristics and their assessment value in COVID-19 patients with different levels of disease severity.