电荷束团非均匀密度分布引起的发射度增长

直线加速器中电荷束团的非线性效应是导致束流发射度增长的一个重要原因。文中给出了直线加速器中几种常见的非均匀密度分布的有限长空间电荷束团所具有的非线性自场能，即纵向非均匀电荷密度分布分别为水袋型，抛物线型，而横向密度分布为均匀型，水袋型，抛物线型及高期型等各种组合非均匀密度分布的自场能公式，并得到了由束团非线性的均匀电荷密度分布引起的束流发射度增长。     

矿热炉把持器的传热分析

以矿热炉电极把持器的传热计算为核心,研究把持器的结构设计和参数选用。通过对冷却水流量、壁面厚度、水垢厚度、烟气温度等影响因素的研究,结合把持器传热边界条件,分析了在不同参数条件下传热变化趋势,为电极把持器的设计和应用提供了参考依据。     

Role of ERAB/L-3-hydroxyacyl-coenzyme A dehydrogenase type II activity in Abeta-induced cytotoxicity

Endoplasmic reticulum-associated amyloid beta-peptide (Abeta)-binding protein (ERAB)/L-3-hydroxyacyl-CoA dehydrogenase type II (HADH II) is expressed at high levels in Alzheimer's disease (AD)-affected brain, binds Abeta, and contributes to Abeta-induced cytotoxicity. Purified recombinant ERAB/HADH II catalyzed the NADH-dependent reduction of S-acetoacetyl-CoA with a Km of approximately 68 microM and a Vmax of approximately 430 micromol/min/mg. The contribution of ERAB/HADH II enzymatic activity to Abeta-mediated cellular dysfunction was studied by site-directed mutagenesis in the catalytic domain (Y168G/K172G). Although COS cells cotransfected to overexpress wild-type ERAB/HADH II and variant beta-amyloid precursor protein (betaAPP(V717G)) showed DNA fragmentation, cotransfection with Y168G/K172G-altered ERAB and betaAPP(V717G) was without effect. We thus asked whether the enzyme might recognize alcohol substrates of which the aldehyde products could be cytotoxic; ERAB/HADH II catalyzed oxidation of a variety of simple alcohols (C2-C10) to their respective aldehydes in the presence of NAD+ and NAD-dependent oxidation of 17beta-estradiol. Addition of micromolar levels of synthetic Abeta(1-40) to purified ERAB/HADH II inhibited, in parallel, reduction of S-acetoacetyl-CoA (Ki approximately 1.6 microM), as well as oxidation of 17beta-estradiol (Ki approximately 3.2 microM) and (-)-2-octanol (Ki approximately 2.6 microM). Because micromolar levels of Abeta were required to inhibit ERAB/HADH II activity, whereas Abeta binding to ERAB/HADH II occurred at much lower concentrations (Km approximately 40-70 nM), the latter more closely simulating Abeta levels within cells, Abeta perturbation of ERAB/HADH II was likely to result from mechanisms other than the direct modulation of enzymatic activity. Cells cotransfected to overexpress ERAB/HADH II and betaAPP(V717G) generated malondialdehyde-protein and 4-hydroxynonenal-protein epitopes, which were detectable only at the lowest levels in cells overexpressing either ERAB/HADH II or betaAPP(V717G) alone. Generation of such toxic aldehydes was not observed in cells contransfected to overexpress Y168G/K172G-altered ERAB and betaAPP(V717G). We conclude that the generalized alcohol dehydrogenase activity of ERAB/HADH II is central to the cytotoxicity observed in an Abeta-rich environment.     

吉林延边金谷山金矿床地球化学特征

以金谷山金矿床的成矿地质特征为基础, 研究了区域地球化学场及异常特征、岩(矿)石微量元素地球化学特征.矿床位于金及其它成矿元素的高背景场中,与成矿有关的元素组合为Au-Sb-As,异常强度高,分带性明显;地层、岩浆岩、构造等地质单元的地球化学特征表明,成岩作用、构造作用与成矿作用关系密切.     

空气污染排放视角下中国核电的健康效益

核电在改善空气质量方面具有重要的作用。本文对比了核电与煤电的空气污染物排放系数,根据空气污染物引起的死亡率与人均燃煤发电量的负指数幂关系,评估了中国通过发展核电在改善空气质量方面对居民的健康效益,并对未来的健康效益进行了分析。结果显示,发展核电能够避免的死亡人数在增加。据估算,1995—2018年,中国核电累计可避免约4.7万人因空气污染物死亡,可避免约22.6万人因空气污染物患病。2020—2030年,预计会避免8.3万~9.4万人死亡,避免39.7万~45.1万人患病。     

Nitrogen utilization and transformation in red soil fertilized with urea and ryegrass

The influence of fertilization with urea and ryegrass on nitrogen utilization and transformation in red soil has been studied by using ^15N tracer method.When urea and ryegrass were applied alone or in combination,the percentage of N uptaken by ryegrass from labelled urea was 3 and 1.7 times that from labelled ryegrass for the application rate of 200mgN.kg^-1 and 100mgN.kg^-1,respectively;combining application of ryegrass and ureareduced uptake of urea N and increased uptake of ryegrass N by ryegrass plant,but the percentage of N residued in soil increased for urea and decreased for ryegrass.when urea and ryegrass were applied alone,the percentage of N residued in soil from labelled ryegrass was more than 69% while that from labelled urea was less than 25%,and much more ryegrass N was incorporated into humus than urea N.     

基于MPSoC的轻量化汽车检测系统及硬件加速 平台设计与优化

针对车辆分类检测在精度和实时性方面存在的挑战,提出了一项改进方案,以优化YOLOv5s 模型,旨在实现轻量化 的汽车检测。通过在MPSoC硬件架构的现场可编程门阵列(FPGA) 上设计系统,成功打造了一个具备高精度、快速检测和低 能耗的解决方案。为了使得模型更适合嵌入式设备部署,采用了MobileNetv3 Small 替代YOLOv5s 的主干网络,并引入卷积 块注意力模块(CBAM) 注意力机制和Inner-IoU Loss 优化方法,使模型在轻量化的同时提升了检测精度和速度。改进后的模 型相较于原始Yolov5s模型,平均精度均值(mAP) 提升了14.8%,参数量减少了49.7%,模型体积减小了40.7%,计算量减 少了48.9%,在NVIDIA 3060上,改进后的检测速度提升了48.8%,达到了82 fps。此外,还利用FPGA 对YOLOv5s 进行了 硬件加速。经过优化的系统达到了45fps 的检测帧率,并保持了较高的精度和速度,这一系统易于部署,适用于智能交通系 统,满足其高效实时监测的需求。     

高铁混凝土简支预应力箱梁施工技术研究

结合我国某高铁预应力混凝土简支箱梁采用后张法施工的过程,简要论述三项关键工序、高性能混凝土耐久性指标的保证措施、减小箱梁后期徐变的相关施工措施及注意要点,以确保满足高速铁路运营的安全性、高速度、高平顺性和舒适度.     

除盐水制备技术进展

介绍了几种水除盐技术(蒸馏、离子交换、电渗析、反渗透、电去离子和电吸附)的原理、发展及应用现状,分析了水除盐技术发展的整体脉络,并预测了发展前景.