AN INVESTIGATION ON SECONDARY EMISSION PROPERTIES OF IMPREGNATED BARIUM SCANDATE DISPENSER CATHODE

A scanning electron probe is used to study the secondary emission properties of the im-pregnated barium scandate dispenser cathode, the influence of the activation on the secondary emis-sion property, the secondary emission image and the secondary emission distribution over the surfaceof the cathode. At optimal activation, δm=3.56 (Epm=700eV). The activation has a larger effect onδ when the activation temperature is higher than 1100℃. The distribution over the surface of thecathode is non-uniform. The half-peak width of the distribution curve over the surface is 0.4. Theexperimental phenomena are discussed in relation to surface analysis of the cathode. The theoreticallyderived binomial distribution curves over the surface fit much better with the experimental results.

A combined airfoil with secondary feather inspired by the golden eagle and its influences on the aerodynamics

Bird flight is a remarkable adaption that has allowed thousands of species to colonize all terrestrial habitats. A golden eagle has impressive flying abilities, such as hovering, perching, preying and attacking. To reveal the flying abilities, avian geometry of a golden eagle was extracted based on noncontact surface measurements using a ROMBER three-dimensional laser scanner. Distributions of a camber line, thickness and a secondary feather line of the extracted point cloud were fitted using convenient analytical expressions. A traditional airfoil was established with the camber line and thickness, then a combined airfoil was constructed by combining the traditional airfoil with a secondary feather. Oscillations of an airfoil as well as rapid pitch up were simplified as a sine wave around the quarter chord axis. Thereafter, both steady and unsteady aerodynamic performances of the airfoil are computed, the influences of the secondary feather on the steady and unsteady aerodynamics were further studied.

Study on Purifying Technology of Andrographolide by Supercritical CO_(2) Secondary Gradient Crystallization

The effects of the secondary gradient crystallizing pressure, temperature and time on the purity and crystallization ratio of andrographolide were investigated via single factor experiments. The shape of crystal was observed with scanning electron microscopy (SEM). The purity of andrographolide was determined by high pressure liquid chromatography (HPLC). It was found that the optimized parameters were pressure 14 MPa, temperature 55℃, time 60 min, and CO2 flow rate 15 L min-1, under these conditions the particle of andrographolide was much smaller, the crystal of andrographolide was distributed in floccule on crystal board,with the purity of andrographolide 92.5%, the crystallization ratio 48.9%.

A double toroidal analyzer for scanning probe electron energy spectrometer

An ultra-high vacuum （UHV） compatible electron spectrometer employing a double toroidal analyzer has been de- veloped. It is designed to be combined with a custom-made scanning tunneling microscope （STM） to study the spatially localized electron energy spectrum on a surface. A tip-sample system composed of a piezo-driven field-emission tungsten tip and a sample of highly ordered pyrolytic graphite （HOPG） is employed to test the performance of the spectrometer. Two-dimensional images of the energy-resolved and angle-dispersed electrons backscattered from the surface of HOPG are obtained, the performance is optimized and the spectrometer is calibrated. A complete electron energy loss spectrum covering the elastic peak to the secondary electron peaks for the HOPG surface, acquired at a tip voltage of -140 V and a sample current of 0.5 pA, is presented, demonstrating the viability of the spectrometer.

Secondary electron emission yield from vertical graphene nanosheets by helicon plasma deposition

The secondary electron emission yields of materials depend on the geometries of their surface structures.In this paper,a method of depositing vertical graphene nanosheet(VGN)on the surface of the material is proposed,and the secondary electron emission(SEE)characteristics for the VGN structure are studied.The COMSOL simulation and the scanning electron microscope(SEM)image analysis are carried out to study the secondary electron yield(SEY).The effect of aspect ratio and packing density of VGN on SEY under normal incident condition are studied.The results show that the VGN structure has a good effect on suppressing SEE.

Identification of Secondary Structure of Extracellular Signal Regulated Kinase (ERK) Interacting Proteins and Their Domain: An in Silico Study

ERK is involved in multiple cell signaling pathways through its interacting proteins. By in silico analysis, earlier we have identified 22 putative ERK interacting proteins namely;ephrin type-B receptor 2 isoform 2 precursor (EPHB2), mitogen-activated protein kinase 1 (MAPK1), interleukin-17 receptor D precursor (IL17RD), WD repeat domain containing 83 (WDR83), tescalcin (Tesc), mitogen-activated protein kinase kinase kinase 4 (MAPP3K4), kinase suppressor of Ras2 (KSR2), mitogen-activated protein kinase kinase 6 (MAP3K6), UL16 binding protein 2 (ULBP2), UL16 binding protein 1 (ULBP1), dual specificity phosphatase 14 (DUSP14), dual specificity phosphatase 6 (DUSP6), hyaluronan-mediated motility receptor (RHAMM), kinase D interacting substrate of 220 kDa (KININS220), membrane-associated guanylate kinase (MAGI3), phosphoprotein enriched in astrocytes 15 (PEA15), typtophenyl-tRNA synthetase, cytoplasmic (WARS), dual specificity phosphatase 9 (DUSP9), mitogen-activated protein kinase kinase kinase 1 (MAP3K1), UL16 binding protein 3 (ULBP3), SLAM family member 7 isoform a precursor (SLAMMF7) and mitogen activated protein kinase kinase kinase 11 (MAP3K11) (Table 1). However, prediction of secondary structure and domain/motif present in aforementioned ERK interacting proteins is not studied. In this paper, in silico prediction of secondary structure of ERK interacting proteins was done by SOPMA and motif/domain identification using motif search. Briefly, SOPMA predicted higher random coil and alpha helix percentage in these proteins (Table 2) and motif scan predicted serine/threonine kinases active site signature and protein kinase ATP binding region in majority of ERK interacting proteins. Moreover, few have commonly dual specificity protein phosphatase family and tyrosine specific protein phosphatase domains (Table 3). Such study may be helpful to design engineered molecules for regulating ERK dependent pathways in disease condition.

青海虎头崖铅锌多金属矿床物化探综合找矿方法研究

虎头崖矿床位于青海省祁漫塔格地区东部,区内矿产丰富、矿种多样、组合复杂,找矿潜力巨大。本研究针对该区域高寒山区的特殊地质条件,聚焦解决隐伏有色金属矿产勘探难题,以期高效、准确地识别并定位高寒环境下隐伏矿体的空间分布。设计并实施了基于物化探综合找矿方法的试验研究,采用双频激电扫面技术,结合高频大地电磁测深方法,以获取深部地质结构的电性特征,有效区分矿化与非矿化异常。同时,结合原生晕和次生晕地球化学找矿手段,通过多元素地球化学异常分析,进一步预测矿化作用的空间分布。上述综合探测技术的应用,在青海虎头崖地区取得了较好的试验效果,圈定了潜在矿化带,探索了适用于高寒山区的隐伏有色金属矿产的找矿技术方法,该工作方法可为周边勘查区及高寒山区隐伏地层找矿工作提供借鉴。

现代分析技术在破伤风类毒素的结构表征中的应用

目的采用现代分析技术对破伤风类毒素(TT)的结构进行表征。方法采用圆二色谱法(CD)对TT的二级结构进行考察,差示扫描量热法(DSC)对TT的变性温度进行考察,并对不同批次样品的测定结果进行比较。结果9批次TT的α-螺旋比例为25.4%~26.2%,反向平行为12.3%~14.9%,平行为6.4%~7.0%,β-转角为21.7%~24.0%,无规卷曲为31.8%~33.9%,熔解温度为89.19℃~90.47℃,结果重复性、批间一致性均良好。结论圆二色谱法和差示扫描量热法可用于破伤风类毒素的结构表征,为该类产品在生产过程中的稳定性和一致性提供技术支持。

基于Revit二次开发实现快速铺砖的插件及应用

为解决人工手动绘制铺砖方案低下的问题,本文基于Revit2022软件,采用C#语言编码,编码过程中通过调用RevitAPI文档,融入扫描线算法,使用VistualStudio2022编译平台编译代码,进行软件打包安装,研发出自动布置铺砖生成功能插件。在Revit中实现了给出边界条件便自动给出自动铺砖解决方案,快速完成装饰深化模型中的铺砖。并开发了自动编码参数赋值功能,实现了每块瓷砖唯一的编码赋值;开发的数据导出功能打通了Revit软件与Excel数据的连接,消除了BIM模型数据孤岛,将明细工单信息流转至Excel。应用表明Revit二次开发的自动铺砖功能生成工字铺、井字铺、错缝铺铺砖方案,在10000m2的地板上生成铺装方案最快1s内完成,速度快、效果更好。铺砖方案信息制成工单显著提升设计师工作效率的同时,也助力减少后期施工返工,指导采购节约材料,有效发挥出BIM模型的信息价值。研究成果可为BIM模型在深化设计比选方案、施工阶段落地应用上提供新思路。

扫描电子显微镜成像信号分析

介绍了扫描电子显微镜 (SEM)的基本工作原理 ,着重分析了在 SEM初始电子束作用下 ,各种成像信号产生的方式及其特点 ,确定二次电子信号因成像分辨率高、携带成像信息丰富而成为 SEM的最终信号源。针对此信号在实际应用中暴露出的缺陷 ,介绍了解决办法 ,从而使 SEM的成像性能得以大幅提高 。

场发射扫描电镜荷电现象的研究及参数优化

扫描电子显微镜主要用于样品显微结构的表征分析,在科研和实际工作中应用广泛。荷电现象是最常见的严重影响到SEM图像质量的现象之一,它会造成图像的反差异常、形变等,在导电性不好或很差的样品形貌表征中极为常见。文中以几种导电性较差样品,如陶瓷、倍他环糊精、Si O2、细菌等为对象,通过实验比对后发现,通过加速电压、探头选择、信号选择、图像采集方式等参数的调节能够有效减轻SEM图像的荷电现象,从而提高了图像质量,获得了更为真实的显微结构信息。

分形维数与D6AC钢的韧性

本文研究了超高强度钢Ｄ６Ａｃ的断裂韧性、冲击韧性和拉伸面缩率与断口分形维数的关系。分别用二次电子线扫描和数字图象法测定断裂韧性试样的断口分形维数，得出试样的韧性与分形维数Ｄｓｅ、Ｄ_Ｈ和Ｄ_Ｌ成正比关系，即韧性随分形维数增大而增加。试样断口的粗糙度由夹杂物引起的差异小于金相组织不同引起的差异时，使用数字图象法测得的分形维数与韧性的线性关系优于二次电子线扫描的结果。

AutoCAD中动态浏览谷歌卫星地图的方法与应用

谷歌卫星地图免费且分辨率高,是不可多得的卫星影像数据,在AutoCAD中动态浏览谷歌卫星地图,有助于提高在AutoCAD平台上进行设计与规划的效率.文中对实现该方法所涉及的关键技术进行了深入剖析,在Visual Studio 2010平台下采用C#语言进行AutoCAD二次开发,最后实现了一个可以动态浏览谷歌卫星地图的插件,该插件允许用户浏览任意区域的谷歌卫星地图,并可将指定区域的卫星图片插入到AutoCAD中,以便进一步应用.将该插件应用于赣州市某工业园GPS控制网的布设中,取得了较好的效果.

环境扫描电镜在法庭科学中的应用

介绍了环境扫描电镜中二次电子成像的原理及在非导电样品、含水含油样品、植物及生物样品中的应用.

高强铝合金6061和7075在模拟海洋大气环境中的腐蚀行为

目前,有关铝合金的腐蚀研究多集中于腐蚀溶液中,对于其在大气中的腐蚀报道较少。采用扫描电化学显微镜(SECM)研究了6061和7075铝合金在模拟海洋大气环境中的腐蚀电化学行为,利用扫描电镜(SEM)观察了腐蚀表面形貌,采用能谱仪分析了腐蚀产物的成分。结果表明:6061和7075铝合金在模拟海洋大气环境中表面不同区域活性溶解程度不同,且表面的氧化电流峰分布呈无规则状;2种铝合金中第二相腐蚀电位的不同造成了其腐蚀机理的差异;试样表面的腐蚀产物数量较少,分布不均匀,腐蚀点主要呈圆形。

三维激光扫描技术在米仓山特长隧道施工中的可行性应用研究

巴陕高速米仓山特长隧道为我国目前在建最长公路隧道,全长约13.8 km。利用三维激光扫描技术高速率、高精度获取对象表面三维坐标的优势,对米仓山隧道LJ2标段右线施工过程中的超欠挖、二衬厚度、掘进面爆破效果进行了检测,并对开挖断面围岩周边收敛和拱顶下沉进行了变形监测。结果表明,检测段隧道超挖区域比例占到81%,其中超挖0~20 cm的占62%,欠挖0~10 cm的为14%;二衬厚度选取不同里程、相同位置121个位置进行分析,最大厚度0.662 m,最小0.456 m,平均厚度0.564 m;掘进面爆破深度约为3.048 m,爆破方量为254.065 m3;K54+030断面围岩周边收敛6 d最大收敛变形量为9.5 mm,拱顶下沉监测点6 d最大变形量为5 mm。

像方扫描技术研究

基于显微摄影的成像原理,研究了像方扫描以扩大视场的途径,并建立了一个二次成像的设计模型,包括一个大视场的固定前置物镜组和一个运动轨迹为球面的中继透镜组。物镜组所成的一次像面优化了场曲,中继透镜组则根据该场曲进行运动,对一次像面不同区域成像,并采用光学被动消热差以保证不同温度的像质。该模型的相对孔径1∶3,波长3.7μm～4.8μm,焦距90mm,瞬时凝视视场为±4°,扫描视场达±24°,采用7片透镜3个非球面,在全视场范围内具有接近衍射限的像质。

基于边界扫描技术的板级测试分析

随着支持IEEE1149.1标准的边界扫描芯片的广泛应用,传统的电路板测试方法如使用万用表、示波器"探针",已不能满足板级测试的需求,相反一种基于板级测试的边界扫描技术得到了迅速发展。对边界扫描测试技术的原理进行了剖析,根据边界扫描测试系统的使用规则对板级测试方法进行了分析、提出了整体测试流程,最后在通用测试的基础上进行了二次开发,提出了提高电路板测试覆盖率的方法。

环境扫描电子显微镜工作原理及实现

系统介绍了环境扫描电子显微镜(ESEM)的研制历程和采用的关键技术。从常规扫描电子显微镜(SEM)的基本工作原理出发,列出了SEM成像信号产生的方式及特点。针对SEM在实际应用中暴露出的缺陷,ESEM提出了解决问题的措施。多重狭缝的采用,使样品室内压强可以大幅提高;而气体二次电子探头(GSED)的发明,使作为成像信号的二次电子信号得到加强。

InP/In_xGa_(1-x)As异质结构中Zn元素的扩散机制

采用闭管扩散方式实现了Zn元素在晶格匹配InP/In0.53Ga0.47As及晶格失配InP/In0.82Ga0.18As两种异质结构材料中的P型掺杂,利用二次离子质谱(SIMS)以及扫描电容显微技术(SCM)对Zn在两种材料中的扩散机制进行了研究。SIMS测试表明:Zn元素在晶格失配材料中的扩散速度远大于在晶格匹配材料中的扩散速度,而SCM测试表明:两种材料中的实际PN结深度与SIMS测得的Zn扩散深度之间存在一定的差值,这是由于扩散进入材料中的Zn元素并没有被完全激活,而晶格失配材料中Zn的激活效率相对更低,使得晶格失配材料中Zn元素扩散深度与PN结深度的差值更大。SCM法是一种新颖快捷的半导体结深测试法,对于半导体器件工艺研究具有重要的指导意义。