Crystallogeny fundamentals of the cholesterol gallstone

The nucleation mechanism and crystal growth process of the cholesterol gallstone are studied and a systematic theory expounded by crystallogeny is proposed. Normal feed and stone-forming feed were used to raise guinea pigs in the control and stone-causing groups respectively. The state and transformation of liquid crystal vesicles, the appearance of crystal nuclei, and the formation of microcrystal grains were observed under a polarizing microscope during the experimental period. It was found that the liquid crystal vesicles in the bile of the control group were small, scattered, and always existed as single forms, and no shaped gallstone crystals were formed. While in the stone-causing group, liquid crystal vesicles grew to larger ones, and then aggregated to form large liquid crystal cells. Solid crystal growth along the edge of these liquid crystal cells formed microcrystal grains. These demonstrated that bile liquid crystal vesicles form the basic nuclei of cholesterol gallstone. Heterogeneous nucleation is the common process in the formation of crystal nuclei and crystal growth.     

钢液非均质形核触媒效用的点阵错配度理论

对钢液凝固温度下各种化合物基底与钢液凝固形核相(δ-Fe和γ-Fe)的二维错配度进行了计算,并对点阵错配度与钢液非均质形核触媒效用的关系进行了分析和讨论.结果表明:基底与形核相的错配度δ越小,越有利于非均质形核.凝固过冷度的对数与基底和形核相的二维错配度近似呈线性关系.基底与形核相的错配度δ<8%,非均质形核效用显著.     

液晶用羊毛脂胆固醇制备影响因素研究

主要研究了液晶用羊毛脂胆固醇的制备和纯化方法,通过分析料醇比、乙醇浓度、加碱量和反应温度对羊毛脂皂化率的影响,结晶溶剂的选择和加入量对产品质量的影响,以及碱洗pH值和酸洗pH值对产品纯度的影响,确定了影响羊毛脂胆固醇制备和纯化的各种因素及其最佳工艺条件,采用此工艺羊毛脂胆固醇的纯度可达99.0%以上,其纯度和各种杂质含量均达到了液晶用羊毛脂胆固醇的标准要求.     

心理干预对胆结石病人术前焦虑的影响

目的：探讨心理干预对胆结石病人术前焦虑及并发症的影响．方法：80例胆结石病人随机编入实验组（按受研究者制定的心理干预）和对照组,并测定其术前焦虑、心率、收缩压．结果：实验组术后心率、收缩压、焦虑水平显著低于对照组（P〈0．05）．结论：心理干预可显著降低其焦虑水平．     

胆囊结石并2型糖尿病腹腔镜胆囊切除术围手术期治疗

目的探讨胆囊结石并2型糖尿病手术治疗风险、手术方式的选择和围手术期处理。方法回顾性分析成功完成胆囊结石并2型糖尿病患者腹腔镜胆囊切除术（LC）72例（合并症28例）围手术期治疗。结果择期LC术65例,急诊LC术7例,全部病例治愈,术后并发症13例。结论胆囊结石并2型糖尿病由于其特殊及风险,术前应全面评估脏器功能,腹腔镜胆囊切除术以其创伤小、恢复快、腹腔干扰小等特点为首选术式,围手术期处理除需控制好血糖,改善代谢紊乱,还应积极治疗合并症,提高手术耐受性。     

Rapid solidification of undercooled Al-Cu-Si eutectic alloys

Under the conventional solidification condition, a liquid aluminium alloy can be hardly undercooled because of oxidation. In this work, rapid solidification of an undercooled liquid Al_80.4Cu_13.6Si₆ ternary eutectic alloy was realized by the glass fluxing method combined with recycled superheating. The relationship between superheating and undercooling was investigated at a certain cooling rate of the alloy melt. The maximum undercooling is 147 K (0.18T _E). The undercooled ternary eutectic is composed of α(Al) solid solution, (Si) semiconductor and θ(CuAl₂) intermetallic compound. In the (Al+Si+θ) ternary eutectic, (Si) faceted phase grows independently, while (Al) and θ non-faceted phases grow cooperatively in the lamellar mode. When undercooling is small, only (Al) solid solution forms as the leading phase. Once undercooling exceeds 73 K, (Si) phase nucleates firstly and grows as the primary phase. The alloy microstructure consists of primary (Al) dendrite, (Al+θ) pseudobinary eutectic and (Al+Si+θ) ternary eutectic at small undercooling, while at large undercooling primary (Si) block, (Al+θ) pseudobinary eutectic and (Al+Si+θ) ternary eutectic coexist. As undercooling increases, the volume fraction of primary (Al) dendrite decreases and that of primary (Si) block increases. Supported by the National Natural Science Foundation of China (Grant Nos. 50121101, 50395105) and the Doctorate Foundation of Northwestern Polytechnical University (Grant No. CX200419)     

Effect of manganese sulfide on the precipitation behavior of tin in steel

Tramp elements such as tin are considered harmful to steel because of hot brittleness they induce at high temperatures. Because tramp elements retained in steel scrap will be enriched in new steel due to the difficultly of their removal, studies on the precipitation behavior of tin are essential. In this study, the effects of different inclusions on the precipitation behavior of tin in steel were studied. The results show that the tin-rich phase precipitates at austenite grain boundaries in an Fe-5%Sn alloy without MnS precipitates, whereas Sn precipitates at the boundaries of MnS inclusions in steel that contains MnS precipitates. MnS is more effective than silicon dioxide or aluminum oxide as a nucleation site for the precipitation of the tin phase, which is consistent with the disregistry between the lattice parameters of the tin phase and those of the inclusions.     

用非均相形核法制备Cu包裹MoSi2复合粉体

采用非均相形核法制备铜包裹MoSi2的复合粉体.利用场发射扫描电镜、X射线衍射仪、电子探针等分析手段对复合粉体进行表征,并讨论包裹结构的形成机制和影响因素.结果表明,采用非均相形核法可以制备出MoSi2颗粒表面被细小的铜微晶包裹的复合粉体;用壬基酚聚氧乙烯醚作为分散剂有助于提高纳米铜的稳定性,并能有效防止复合粉体的团聚,MoSi2颗粒的分散性得到显著改善,包裹效果较好;MoSi2颗粒大小和形状对复合粉体的包裹情况有较大影响;包裹结构取决于铜在MoSi2颗粒表面的沉积以及对复合粉体团聚的控制.     

磁场对CaCO3结晶过程的影响

研究了磁化对ＣａＣＯ３结晶过程的影响。发现磁处理掏了晶体的成核过程但加速了晶体的生长，生成晶粒数量少，体积大。磁场对ＣａＣＯ３结晶过程的影响主要是通过成垢阴离子起作用。磁记忆效应至少可持续７２ｈ。     

支持向量机在胆固醇测定中的应用

支持向量机(SVM)在非线性回归估计中具有很好的学习性能。本文针对医学上三类血浆脂蛋白(VLDL、LDL、HDL)样本中胆固醇含量测定的问题,提出了利用SVM进行回归估计的方法,并与BP网络方法进行了比较。实验表明SVM在稳定性上优于BP网络,而且在对极低密度脂蛋白(VLDL)类别回归估计的精确度上也比BP网络要好。     

Effect of vanadium carbide on commercial pure aluminum

The effect of vanadium carbide (VC) on the grain size of commercial pure aluminum was experimentally investigated by varying the content of VC, the holding time, and casting temperature. The refining efficiencies of VC and Al5Ti1B were also compared. The refined samples of commercial pure aluminum were examined using optical microscopy, scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). The results suggest that VC is a good refiner of commercial pure aluminum. The addition of only 0.3wt% VC can decrease the grain size of aluminum to 102 μm, whereas the casting temperature and holding time have little effect on the grain size. The refining efficiency of VC is better than that of Al5Ti1B. The VC particles in molten aluminum act as nuclei and the grain refinement of aluminum alloys by VC particles is achieved via heterogeneous nucleation.     

奥氏体钢非平衡凝固异质核心触媒效用的价电子判据

利用界面共格对应理论无法解释奥氏体钢非平衡凝固过程中TiC、CaS为奥氏体枝晶有效异质核心的现象．利用余氏固体与分子经验电子理论以及程氏改进的TFD（Thomas-Fermi-Dirac）模型计算表明,界面共格对应并不是有效触媒基底的本质要求．在Tillen异质形核静电作用理论基础上,建立了奥氏体钢非平衡凝固异质形核价电子模型,该模型由三层组成：γ-Fe晶胞杂化状态稳定层、（γ-Fe）-核心双重晶格电子层以及核心晶胞杂化状态稳定层,并给出了评价异质核心触媒效用的价电子判据．据此考察了VC、NbC、TiC、TaC、ZrC、CaS等颗粒的触媒效用,与实际较为吻合．     

载毒死蜱液晶系形成影响因素研究

为探讨载毒死蜱液晶体系形成规律,研究了有机溶剂种类、温度、正构醇碳数及无机盐对液晶相形成规律的影响。结果表明:苯(毒死蜱溶剂)环上取代基,有利于液晶“骨架”的形成及维持;高温导致液晶相形成及消失时,体系含水量均上升;随醇链的增长,体系形成液晶相所需最低含水量增加缓慢,而液晶相消失时的最高含水量则先上升后下降;添加无机盐,体系液晶相消失时所需最高含水量随阳离子水合半径降低而降低,说明液晶相结构易于破坏。     

Y掺杂工艺对Y-BT陶瓷性质的影响

本文用非均匀形核表面包覆法（表面包覆法）和化学混合法分别制备了钇掺杂纳米晶钛酸钡（Y-BT）粉体。用DSC和TG热分析方法研究了Y(OH)3表面包覆层的热分解和所形成的Y2O3的形核和晶化现象,用电感耦合等离子发射光谱分析了不同制备方法对Y-BT粉体组分分布均匀性和化学组成的化学计量偏离现象,详细讨论了材料的组成、相结构和微结构对材料室温电阻率的影响。实验表明：采用表面包覆法能够得到Y 组分分布更均匀和化学组成化学计量比更准确的陶瓷粉体,从而使其陶瓷烧结体在更低的温度下达到更低的室温电阻率。     

蚯蚓冻干粉对高血脂小鼠胆固醇逆转运相关基因的调节作用

以高脂饲料饲喂昆明种小鼠构建高血脂小鼠模型,灌胃给予高、中、低剂量(0.4,0.2,0.1g/kg)蚯蚓冻干粉,每天1次,同时饲喂高脂饲料,以仅饲喂高脂饲料组小鼠为对照,共饲养10周.提取小鼠肝脏总RNA,应用半定量RT-PCR技术检测实验组与对照组小鼠胆固醇逆转运相关基因卵磷脂胆固醇酰基转移酶(lecithin cholesterol acyltransferase,LCAT)和脂蛋白酯酶(lipoprotein lipase,LPL)mRNA表达水平.结果表明,蚯蚓冻干粉极显著提高实验组小鼠LCAT mRNA表达水平(P0.01),显著提高LPL mRNA表达水平(P0.05),提示这是蚯蚓冻干粉能够降低高血脂小鼠血浆胆固醇水平的原因之一.     

反应性单体改性PP/PS共混物的增容作用

制备了聚丙烯/聚苯乙烯(PP/PS)共混物和反应性单体苯乙烯(St)、丙烯酸(AA)及其混合单体改性PP/PS共混物,用扫描电镜(SEM)、偏光显微镜(POM)和动态黏弹谱仪(DMA)研究了反应性单体改性PP/PS共混物的相形态与动态力学行为.结果表明反应性单体St存在增容作用,促进PS在PP中的分散,使分散相PS的粒子尺寸减小.反应性单体AA存在明显的异相成核作用,使PP的球晶尺寸降低.St改性共混物的增容作用比AA改性共混物的明显,而AA改性共混物的异相成核作用比St改性的大.     

Synthesis and Properties of Some Novel Liquid Crystals: Chiral 4′-(4-alkoxy-2,3-difluorobenzoyloxy)-4-biphenyl Carboxylates

Introduction　　Mostpreviouslyreportedchiralliquidcrystalswerelaterallyunsubstitutedormono-substituted[1].Certainlaterallydifluoro-substitutedsystems(ondifferentrings)haveanS*CAphase[2].TheS*CSAS*AN*IsequencediscoveredinaTGBAsystembyBouchta[3]wasduetolateralfluoro-substituents,whichsuggeststhatlateralfluoro-substitutentsdonotsimplylowerthemeltingpointsandcompresstheformationoftheunderlyingsmecticphases,butinfluencethemesomorphiccharactertoagreaterextent.Amongthesechiralliquidcrystals,th…     

硅上液晶微型显示器工作原理

硅上铁电液晶显示器是以Flos空间光调制器为光引擎的微显示系统,空间光调节器的工作原理与表面稳定型铁电液晶器件相同。硅上铁电液晶微显示器运行时,图像信号被编码后经由空间光调制器加载到光波前,再通过光学系统解码读出,灰度和色彩则可通过时序编码方法来产生。     

热致液晶聚酰胺的合成和液晶行为

为了降低聚酰胺的熔融温度，运用分子设计的方法，采用芳香族和脂肪族两类二元胺共缩聚，成功地合成了三个系列的热致液晶聚酰胺。这些共聚酰胺具有３００℃以下的熔融温度１００℃以上液晶温度范围和稳定的液晶相。通过偏光显微镜、Ｘ光衍射分析和ＤＳＣ分析等手段，确认上述热致共聚酰胺液晶为向列型液晶。     

基于小润湿角下脉冲磁场的凝固形核模型

基于Ma形核模型,理论分析了异质形核基底小润湿角下脉冲磁场金属凝固的异质形核过程,建立了凝固形核模型.考察脉冲磁场磁感应强度对金属凝固临界形核半径及临界形核过冷度的影响.结果表明:该模型中体系Gibbs自由能与异质形核基底形状系数无关.在低过冷度金属凝固条件下,当脉冲磁场磁压力功与金属熔体固液自由能差在同一数量级时,脉冲磁场可有效减小凝固形核的临界半径;在大过冷度(大于20℃)金属凝固条件下,脉冲磁场对金属凝固临界形核半径的影响可忽略.金属凝固异质形核基底粒径较大时,临界形核过冷度随脉冲磁场磁感应强度增大而有效减小.