Neutron irradiation-induced effects on the reliability performance of electrochemical metallization memory devices

In this work,electrochemical metallization memory(ECM)devices with an Ag/AgInSbTe(AIST)/amorphous carbon(a-C)/Pt structure were irradiated with 14 MeV neutrons.The switching reliability performance before and after neutron irradiation was compared and analyzed in detail.The results show that the irradiated memory cells functioned properly,and the initial resistance,the resistance at the low-resistance state(LRS),the RESET voltage and the data retention performance showed little degradation even when the total neutron fluence was as high as 2.5×1011 n/cm2.Other switching characteristics such as the forming voltage,the resistance at the high-resistance state(HRS),and the SET voltage were also studied,all of which merely showed a slight parameter drift.Irradiation-induced Ag ions doping of the a-C layer is proposed to explain the damaging effects of neutron irradiation.The excellent hard characteristics of these Ag/AIST/a-C/Pt-based ECM devices suggest potential beneficial applications in the aerospace and nuclear industries.

Functional outcomes after home-based rehabilitation for heroin-induced spongiform leukoencephalopathy

A 22-year-old man with a 2-year history of heroin vapor inhalation developed spongiform leukoencephalopathy and underwent clinical and home-based rehabilitative treatments. Activities of daily living were measured using the Functional Independence Measure at discharge and at 6, 12, and 24 months after discharge. His neurological symptoms gradually disappeared with rehabilitative treatment, and the functional scale scores increased from 55 on admission to 105 at 24 months after discharge. These results suggest that home-based rehabilitation was effective in ameliorating the pathology and improving activities of daily living in this patient with heroin-induced spongiform leukoencephalopathy.

Effect of laser focus in two-color synthesized waveform on generation of soft x-ray high harmonics

Synthesis of multi-color laser pulses has been developed as a promising way to improve low conversion efficiency of high-order harmonic generation(HHG). Here we systematically study the effect of laser focus in a two-color waveform on generation of macroscopic HHG in soft x-rays. We find that the dependence of HHG yields on laser focus at low or high gas pressure is sensitive to the characteristics of single-atom harmonic response, in which “short”-or “long”-trajectory emissions can be selectively controlled by changing the waveform of two-color synthesized laser pulse. We uncover the phase-matching mechanism of HHG in the gas medium by examining the propagation of the two-color waveform and the evolution of time-frequency emissions of high-harmonic field. We further reveal that the nonlinear effects, such as geometric phase, atomic dispersion, and plasma defocusing, are responsible for modification of two-color waveform upon propagation. This work can be used to find better macroscopic conditions for generating soft x-ray HHG by employing two-color optimized waveforms.

Dynamic changes of beta-amyloid protein deposition in hippocampus of female ovariectomized rats

BACKGROUND： To evaluate and summarize the effects of cerebral perfusion and vascular reserve on the treatment of SICAS. Recently, research on β-amyloid protein has focused on the regulatory effects of estrogen or phytoestrogen on its deposition. However, there have been only a few reports on dynamic changes of β -amyloid protein deposition in hippocampus of ovariectomized rats. OBJECTIVE： To measure β -amyloid protein deposition in the hippocampal formation of ovariectomized rats by using immunohistochemistry; to observe time-dependent dynamic changes. DESIGN： Randomized controlled animal study. SETTING： Third Xiangya Hospital of Central South University. MATERIALS： The experiment was carried out in the Central Laboratory of the Third Xiangya Hospital of Central South University from November 2005 to December 2006. Fifty healthy female Sprague Dawley （SD） rats, weighing （293 ± 10） g, were provided by the Animal Laboratory of Xiangya Medical College, Central South University. All rats had neither a childbearing history nor hepatic or renal disease, or skeletal deformity. β-amyloid protein immunohistochemical kit was provided by Wuhan Boster Company. The experiment was in accordance with animal ethics standards. METHODS： All rats were randomly divided into five groups, including normal control group （n = 10）, sham operation group （n = 10）, and ovariectomized group （n = 30）. After anesthesia in the ovariectomized group, the bilateral ovaries were separated and resected. The same volume of fat was resected in the sham operation group. Rats from the normal control group, however, did not receive any surgical treatments. Rats in the normal control group and sham operation group were sacrificed by anesthesia 7 weeks after surgery. Every ten rats from the ovariectomized group was respectively sacrificed at 7, 15, and 30 weeks after surgery. lmmunohistochemistry was used to detect β-amyloid protein deposition in hippocampal sections. Cell counting and gray value measurements served to record the dynamic changes in β-amyloid protein deposition. MAIN OUTCOME MEASURES： （1） Morphological changes. （2） Positive cell counts from β -amyloid protein stainings and gray value measurements. RESULTS： All 50 rats were involved in the final analysis. （1） Morphological changes. β -amyloid-positive cells were detected in the hippocampus of all rats. Biebrich scarlet stained neurites with a swollen cytoplasm. A few β -amyloid-positive cells were observed in all groups 7 weeks after surgery, and plasma and neurites were slightly stained. By 15 weeks after surgery, a number of β -amyloid-positive cells were observed in the ovariectomized group, and plasma and neurites were also slightly stained. By 30 weeks after surgery, however, many β-amyloid-positive cells were observed in the ovariectomized group. These cells were partially aggregated and darkly stained. （2） Positive cell counts and gray value of β-amyloid protein in hippocampus. At 7 weeks after surgery, cell counts and gray value measurements were not significantly different in the ovariectomized group compared to the sham operation group and normal control group （P 〉 0.05）. Cell counts and gray value measurements were higher in the ovariectomized group by 15 weeks compared to those by 7 weeks in the normal control group, sham operation group and ovariectomized group （P 〈 0.05）. At 30 weeks after surgery, cell counts and gray value measurements were higher in the ovariectomized group compared to the normal control group. In addition, there were significant differences between sham operation group and ovariectomized group, at 7 and 15 weeks after operation （P 〈 0.05-0.01 ）. Cell counts and gray value measurements increased in all groups over time. CONCLUSION： Extended estrogen deficiency in rats can increase β-amyloid protein deposition in the hippocampus and the deposition increases over time.

Growth of centimeter scale Nb_(1−x)W_(x)Se_(2) monolayer film by promoter assisted liquid phase chemical vapor deposition

Two-dimensional(2D)transition-metal dichalcogenide materials(TMDs)alloys have a wide range of applications in the field of optoelectronics due to their capacity to achieve wide modulation of the band gap with fully tunable compositions.However,it is still a challenge for growing alloys with uniform components and large lateral size due to the random distribution of the crystal nucleus locations.Here,we applied a simple but effective promoter assisted liquid phase chemical vapor deposition(CVD)method,in which the quantity ratio of promoter to metal precursor can be controlled precisely,leading to tiny amounts of transition metal oxide precursors deposition onto the substrates in a highly uniform and reproducible manner,which can effectively control the uniform distribution of element components and nucleation sites.By this method,a series of monolayer Nb_(1−x)W_(x)Se_(2)alloy films with fully tunable compositions and centimeter scale have been successfully synthesized on sapphire substrates.This controllable approach opens a new way to produce large area and uniform 2D alloy film,which has the potential for the construction of optoelectronic devices with tailored spectral responses.

Modification of laser-induced state in atomic attosecond transient absorption by the XUV pulse pair

Attosecond transient absorption(ATA)has been developed as an all-optical technique for probing electron dynamics in matter.Here we present a scheme that can modify the laserinduced state and the corresponding ATA spectrum via excitation by a pair of XUV attosecond pulses and by a time-delayed mid-infrared(MIR)laser probe.Different from the scheme of the electronic excitation by a single XUV attosecond pulse,the application of a pair of XUV pulses provides extra degrees of freedom,such as the time delay and the intensity ratio between two XUV pulses,which make it possible to adjust the pump process,resulting in the modification of the ATA spectrum.We show that by varying the time delay between the two XUV pulses,the population of the dark state and the ATA spectrum of the laser-induced state have periodic modulations.We also demonstrate that the peak of the ATA spectrum of the laser-induced state appears at a fixed time delay between the XUV pair and the MIR laser when the intensity ratio is large,and it changes with the time delay when the intensity ratio is small,which can be related to either one of two peaks in the population of the dark state.

小微企业普惠性减税政策效应分析

本文选取了《关于实施小微企业普惠性税收减免政策的通知》(财税〔2019〕13号)来研究税收政策对小微企业的影响,提出普惠性减税政策能降低小微企业整体税负、提升小微企业盈利能力、促进小微企业投资、推动小微企业技术进步四个假设。本文基于全国3010家企业样本在政策实施前后四期即2018年第三、四季度和2019年第一、二季度的财务和税收数据,通过双重差分法,分析小微企业在政策前后相关指标的差异,发现本轮政策取得了积极成效,对降低小微企业税收负担、提高盈利能力、促进投资和技术进步等方面均有显著正向作用。在此基础上,本文提出应继续降低小微企业税费负担、简化办税流程、优化营商环境等建议,以助力小微企业进一步发展。

数字经济背景下剩余利润分配方法的发展趋势及其影响

剩余利润的分配方法一直是跨国企业税收研究关注的重点。2020年10月12日,OECD发布《数字化带来的税收挑战——支柱一蓝图》,旨在通过建立不同于传统独立交易原则的公式化利润分配方法,将更多的剩余利润分配至市场或用户所在地。《支柱一蓝图》是"三段式分配机制"向"两段式分配机制"的迭代革新,同时在增强税收的确定性及便利性的基础上增加剩余利润分配的技术细节。本文基于《支柱一蓝图》的剩余利润分配方法,分析其对国际税收规则的影响,并针对我国的相关税法及征管改革提出相应的建议。

“一带一路”倡议背景下关税减免制度的国际协调研究

在“一带一路”倡议背景下,沿线国家商品和服务贸易的规模不断扩大,各国呈现出降低或取消对有关商品或服务征收关税的趋势。本文分析了我国现行的关税减免制度和国际协调现状,总结“一带一路”沿线国家(地区)在关税减免制度国际协调中存在的问题,通过借鉴欧盟、北美自由贸易区、中国—东盟自由贸易区和非洲大陆自由贸易区等区域组织在关税减免制度的国际协调方面的成功经验,提出完善建议。

CRS规则下报送账户的识别及影响

按照我国的CRS实施进度要求,目前金融机构已完成所有数据报送工作,意味着中国正式进入CRS涉税信息收集和接收的实操阶段。账户识别作为实施CRS的基础,决定了信息的报送范围。研究CRS规则下报送账户的识别规则,就其对金融机构、高净值群体及跨国公司的现实影响进行分析,有助于完善我国的账户识别工作。

促进个人境外投资的税收政策研究

随着我国经济对外开放程度的提高,越来越多的个人走出国门进行相应的境外投资。2018年我国修订了个人所得税法,对于个人境外投资的抵免及反避税作了相关的规定。本文在此基础上,总结我国现行的境外投资个人所得税政策,并借鉴美国、英国、日本等国家的成功经验,提出促进我国个人境外投资的税收政策及管理建议,具体包括:加快税收协定的谈签;加强国际税收协调;保持一定的资本输出中性;建立完善的纳税服务体系。