Monte Carlo simulations and experimental observations of templated grain growth in thin platinum films

Monte Carlo (MC) simulations were used to model microstructural evolution in Pt thin films with epitaxial seed grains buried in a polycrystalline matrix. The key to achieving purely epitaxial films via templated grain growth in such materials is the lateral coalescence of the seeds into a single epitaxial grain. The primary factors in determining whether this event takes place, for a given set of interfacial mobility/energy functions, are the relative initial sizes of the seed grains and polycrystalline matrix grains, and the initial degree of surface coverage of the epitaxial seeds. These characteristics are evaluated by varying the films’ initial microstructural parameters, including seed grain size, seed number density, seed surface coverage and polycrystalline matrix grain size. Additional simulations were carried out to investigate the effect of varying the energy and the mobility of seed–matrix interfaces. The critical values of seed–matrix grain size depend on the energy/mobility used, though seed coalescence remains the key criterion for epitaxial grain growth.     

Ru籽晶层对CoCrPt-SiO_2垂直记录层形貌及结构的影响

采用磁控溅射方法,制备了以不同厚度Ru薄膜为籽晶层的CoCrPt-SiO2垂直磁记录薄膜。利用原子力显微镜(AFM)、透射电镜(TEM)分析Ru薄膜的结构和形貌,并研究了其结构对CoCrPt-SiO2薄膜表面形貌、粗糙度及结构的影响。结果表明,CoCrPt-SiO2记录层的晶粒尺寸和粗糙度均随着Ru籽晶层厚度的增加而增加,薄而粗糙的籽晶层适合于高密度磁记录介质。对于CoCrPt-SiO2记录层晶粒的优化,厚度为70nm的Ru籽晶层有利于记录层薄膜晶粒的完全隔离,从而提高了磁记录性能。     

Growth and optical properties of ZnO nanorods prepared through hydrothermal growth followed by chemical vapor deposition

We report on the synthesis of high-quality ZnO nanorods by combining hydrothermal growth (HG) and chemical vapor deposition (CVD) processes. Vertically aligned and closely packed ZnO nanorods were grown by HG on a sputtered ZnO seed layer on a SiO₂/Si (0 0 1) substrate. The top surface of the HG-prepared ZnO nanorods showed very flat surfaces compared with that of the sputtered ZnO seed layer. Therefore, the HG-prepared ZnO nanorods were used as a new alternative seed material for the CVD growth of the ZnO nanorods. Vertical ZnO nanorods were grown by CVD on both the new HG-prepared nanorod seed material and the sputtered ZnO seed layer. The CVD-prepared ZnO nanorods on new HG-prepared nanorod seed material showed better crystalline quality and superior optical properties than the CVD-prepared ZnO nanorods on sputtered seed layer. The former showed negligible deep-level emissions at room temperature photoluminescence measurements. The intensity ratio of near-band-edge emissions to deep-level emissions from the former was about 910, but that from the latter was about 151. This implies that the HG-prepared ZnO nanorods can be used as a promising new seed material for nanostructure synthesis.     

基于多尺度几何分析的区域分割算法研究

针对逆向工程基于种子增长区域分割法中种子区域选择和种子增长问题,提出了一种将多尺度理论与区域增长法相结合的点云自动分割方法.采用曲率尺度空间实现多尺度几何分析和特征检测;以多尺度特征检测中大尺度下特征检测作为初始种子区域;基于多尺度特征检测结果之间的相关性,提出按照多尺度特征检测结果进行种子增长;利用转角作为种子是否增长的度量标准;通过特征融合实现特征分割的优化.用多尺度几何分析代替传统单一尺度分析,保证了种子区域选择的稳定性和种子增长方式的可靠性.激光扫描曲面点云分割实例表明:提出的方法可以有效地实现逆向工程特征分割.     

稳定种分玛瑙氢氧化铝粒度的研究

本文研究种分分解制度对氢氧化铝粒度的影响.连续种分生产的氢氧化铝粒度呈周期性波动;采用两种子连续种分分解获得粒度稳定的种分玛瑙氢氧化铝.得到的最佳工艺条件如下:种子加入量:循环种子300g/l,细种子8g/l;温度:45℃～75℃;时间24h.     

Feasibility of integrated seed making and directional solidification of TiAl alloy using cold crucible

A new seed making method with cold crucible by power off technique was proposed. The cold crucible quenched seed with columnar structure has a similar cross-section shape as that of the cold crucible, and can be directly used for the directional solidification processes. The proposed method can significantly simplify the seeded directional solidification process and avoid the contamination from the seed machining.     

取种盘吸种微孔的高速数控加工及优化

为满足用气吸式排种器的取种盘播种小粒径种子的要求,根据其结构特点采用高速数控加工,就加工难点提出解决方案并编写了数控加工程序,对取种盘加工超差进行分析后得出吸种微孔加工超差率与吸种微孔数的数学回归模型。通过在JPS-12型试验台上进行吸种试验,得出吸种微孔加工超差率与种子破损率和合格率的数学关系,进而得出孔数为72的取种盘,因其种子破损率较低,合格率较高,可以满足小粒种子的精量播种要求的结论。     

强化铝酸钠溶液晶种分解过程的研究

用醋酸、磷酸等酸类对工业日程进行处理得到的活性晶种、并通过分解试验检验了日程的活性,对活性日程的作用机理也进行了初步探讨。     

The effectiveness of jarosite species for precipitating sodium jarosite

The precipitation of jarosite-type compounds [e.g., NaFe₃(SO₄)₂(OH)₆] is commonly used in the zinc industry to remove iron solubilized in the processing circuit. The precipitation reaction is greatly accelerated by the presence of jarosite seed, and the rate increases in a nearly linear manner with increasing seed additions. As shown in this study, sodium jarosite, potassium jarosite, silver jarosite, and lead jarosite are equally effective as seed for the precipitation of sodium jarosite. By extension, any jarosite-type compound would likely be an effective seed for the precipitation of any other jarosite species. The implication is that the zinc industry can readily convert from one jarosite species to another without concerns about the efficiency of the seed used. For more information, contact J.E. Dutrizac, CANMET, 555 Booth Street, Ottawa, Ontario, Canada K1A OG1; (613) 995-4823; fax (613) 996-9041.     

Effects of various metal seed layers on the surface morphology and structural composition of the electroplated copper layer

This study examined the effects of depositing a seed layer on the surface morphology and the electric characteristics of an electrodeposited copper foil. Pt, Pd, a Pt-17Pd alloy and gold were used as the seed metals. The morphology, crystal structure, and electric characteristics of the electrodeposited copper foil were examined by scanning electron microscopy, X-ray diffraction, atomic force microscopy, and a four-point probe, respectively. The surface roughness, crystal growth orientation, and resistivity were controlled using various seed layers. Large particles were observed on the surface of the copper layer electroplated onto the Pd seed layer. However, a uniform surface was obtained when a Pt seed layer was used.     

荔枝核皂苷对老年痴呆大鼠的干预作用研究

目的: 建立老年痴呆(Alzheimer's disease, AD)大鼠模型,探讨荔枝核皂苷对AD大鼠的治疗作用及其机制。方法: 50只SD大鼠分为:对照组、模型对照组和低、中、高剂量荔枝核皂苷治疗组,共5组,每组10只;Morris水迷宫实验检测各组大鼠的逃避潜伏时间和平台跨越次数;Western blot实验检测各组脑组织β淀粉样蛋白(β-amyloid protein,Aβ)的表达变化;流式细胞仪检测各组脑组织活性氧(ROS)表达的改变。结果: AD大鼠模型组与对照组比较,逃避潜伏时间出现显著性地延长(P<0.01),平台跨越次数显著性地减少(P<0.01)。荔枝核皂苷治疗后AD大鼠的逃避潜伏时间和平台跨越次数得到显著性地改善(P<0.05)。AD大鼠脑组织Aβ的表达水平显著高于正常对照组,高、中、低剂量荔枝核皂苷治疗组可以剂量依赖性地降低模型鼠脑组织中Aβ的表达水平。对照组、模型对照组、低剂量荔枝核皂苷治疗组、中剂量荔枝核皂苷治疗组、高剂量荔枝核皂苷治疗组ROS表达水平的相对值分别为 6.12±0.61、9.54±1.42、8.33±1.26、7.68±1.14、7.23±0.73,模型组显著高于对照组(P<0.01),荔枝核皂苷治疗可以显著降低模型组脑组织中ROS的表达水平(P<0.05)。结论: 荔枝核皂苷具有抗AD大鼠痴呆的活性,减少AD大鼠脑组织Aβ和ROS的生成是其主要的作用机制。     

种分附聚微观机理探讨

用二段工业细晶种和实验室制备细粒于进行了附聚试验研究，借助于颗粒计数仪、扫描电子显微镜等大型检测手段对附聚产物进行了系统分析。探讨了铝酸钠溶液种分附聚微观机理。     

The effect of seed layer on morphology of ZnO nanorod arrays grown by hydrothermal method

Well-aligned ZnO nanorod arrays were synthesized by hydrothermal method on Si substrates that were covered with pre-deposited ZnO films as seed layers. The ZnO seed layers were deposited by RF magnetron sputtering. It is found that the seed layers prepared under different oxygen partial pressure sputtering parameters and annealing treatment have a great influence on the morphology of the ZnO nanorod arrays grown subsequently on them. Furthermore, growth positions of nanorod/microrod arrays were selectively controlled on the lithography-assist ZnO seed layer.     

The use of gold for fabrication of nanowire structures

A common application of nanometer-sized gold particles is as seed particles for growth of semiconductor nanowires, which are believed to act as highly promising building blocks in future electronic devices. In a majority of the reports of successful nanowire growth, gold has been the seed particle material of choice. In this review article we identify the different types of gold particles used to initiate nanowire growth, namely gold particles made from thin films, gold particles defined by lithographic methods, colloidal gold particles and aerosol-generated gold particles. The production and deposition methods are described and the advantages and disadvantages of the particle types are discussed. In addition we discuss different properties that seem to make gold the most universal material for nanowire seed particles.     

常压混合脱硅工艺生产种分精液

本文介绍了碳分、种分工艺对精液硅量指数A/S的不同要求,认为种分精液单独生产是很有必要的.本文从理论上分析了目前所应用的脱硅工艺,提出了一种常压生产种分精液的方法-常压混合脱硅工艺,并对某厂采用此工艺进行种分精液生产的情况进行了简单的介绍.     

Roughness analysis of CVD Cu films on different substrates by AFM imaging

The roughness analysis of chemical vapor deposition (CVD) of copper (Cu) thin films on various substrates with and without seed layers was studied using atomic force microscopy (AFM). The effect of the seed layers on the film morphology was investigated, and none of the seed layers on the substrates improved the film morphology compared with TiN.     

Atomistic simulation of hillock growth

This paper explores the mechanisms of hillock and whisker growth in stressed polycrystalline films by molecular dynamics simulations. The initial geometry consists of three grains with a triple line aligned perpendicular to a free surface, plus a fourth pyramidal-shaped grain implanted between the triple line and the surface. This simulated grain geometry corresponds to that observed in experiments during hillock and whisker growth, with the fourth grain serving as a seed for hillock growth. The simulations, performed under an applied in-plane biaxial compression, reveal an upward motion and growth of the seed grain. The growth occurs by stress-driven grain boundary diffusion from below the seed grain onto some of its internal faces. Accretion of atoms to those faces pushes the seed grain upwards and sideways. The different diffusion and accretion rates at different boundaries also give rise to internal stresses, which can be partially accommodated by grain boundary motion coupled to shear deformation. The hillock growth is countered by surface diffusion, which can slow the growth or even suppress it completely. Other mechanisms involved in hillock growth are also discussed.     

超细氢氧化铝晶种制备技术研究

用一种含Al2O3的非晶质浆液与烧结法铝酸钠精制液以一定比例混合，使溶液具有极大的过饱和度，从而自发分解产出平均拉径在0．5μm以下、高分散性、其具有极为发达表面和甚多活性点的超细氢氧化铝晶种，以此超细氢氧化铝作晶种用种分制取粒度和化学组成都符合指标要求的超细氢氧化铝。     

中华猕猴桃果仁非饱和脂肪酸（果王素）在大鼠放射性肺损伤中的防治作用及其机制探索

目的：观察中华猕猴桃果仁非饱和脂肪酸（果王素）在大鼠放射性肺损伤中的防治作用,并通过检测肺组织超氧化物歧化酶（SOD）、谷胱甘肽过氧化物酶（GSH-Px）、髓过氧化物酶（MPO）和转化生长因子-β1（TGF-β1）探讨其机制。方法：将90只Sprague-Dawley大鼠按随机数字表法分为空白组、模型组、果王素组（60、120、240 mg/kg）,每组18只。除空白组外,其余组大鼠予以6MV-X线全胸部放射（3Gy/次,2次/周,总剂量18Gy）构建放射性肺损伤大鼠模型,各果王素组在放射前一周分别按60、120、240 mg/kg果王素剂量加入0.9%氯化钠1 mL每日灌胃1次,空白组、模型组在同一时间予以0.9%氯化钠1 mL灌胃1次。各组分别于放射后14 d、28 d、56 d随机处死动物6只,取肺组织行HE染色、Masson染色观察病理学改变,并检测肺组织SOD、GSH-Px、MPO含量及TGF-β1的表达。结果：与模型组相比,60、120、240 mg/kg果王素可显著减轻肺泡炎和放射性肺纤维化程度,降低肺组织羟脯氨酸（HYP）含量,增加抗氧化酶SOD、GSH-Px含量及减少氧化酶MPO含量,下调TGF-β1的表达,且剂量越高效果越明显。 结论：果王素对放射性肺损伤具有防治作用,其机制可能与减少氧化应激损伤、下调TGF-β1表达有关。     

硅铁等杂质在超声强化铝酸钠溶液种分过程中行为

对比考察了超声强化与不加超声强化时铝酸钠溶液晶种分解过程中硅、铁等杂质在种分溶液中的浓度变化，以及硅、铁和钠在种分过程晶种中的含量变化。实验表明超声强化相比一般种分，种分溶液中杂质浓度没有明显变化，也并没有显著增加晶种与产品中的硅、铁和钠等的杂质含量,仍可得到一级品的氧化铝。