Ge掺杂碳化硅晶体的生长缺陷

采用物理气相传输法(PVT)制备了2英寸Ge掺杂和非掺SiC晶体, 并使用二次离子质谱仪(SIMS)、显微拉曼光谱(Raman spectra)仪、体式显微镜、激光共聚焦显微镜(LEXT)和高分辨X射线衍射(HRXRD)仪等测试手段对其进行了表征。结果表明, Ge元素可以有效地掺入SiC晶体材料中, 且掺杂浓度达到2.52×10¹⁸/cm³, 伴随生长过程中Ge组份的消耗和泄漏, 掺杂浓度逐渐降低; 生长初期高浓度Ge掺杂会促使6H-SiC向15R-SiC晶型转化, 并随着生长过程中Ge浓度的降低快速地转回6H-SiC稳定生长。用LEXT显微镜观察发现, 生长初期过高的Ge掺杂导致空洞明显增多, 位错密度增加, 掺杂晶体中位错密度较非掺晶体增大一倍。HRXRD分析表明掺Ge能增大SiC晶格常数, 这将有利于提高与外延III族氮化物材料适配度, 并改善器件的性能。     

钌镧氧化物涂层析氯反应动力学比较研究

通过热分解法制备了Ti/RuO₂和Ti/Ru-La-O氧化物涂层, 利用微分电容和极化曲线等实验方法对涂层Clˉ特性吸附、La对RuO₂涂层析氯反应过程的影响及反应机理进行了研究。结果表明, 在NaCl溶液中, 涂层表面存在Clˉ的特性吸附, 这种特性吸附对析氯反应的动力学产生了影响, 导致Tafel斜率上升, 反应级数下降, 加入La使氧化钌涂层的过电位下降, 交换电流密度增大, 有利于析氯反应的进行。本文对涂层存在的两种可能反应机理进行了比较分析, 认为在中性NaCl溶液中析氯反应是由过程控制的。     

新疆维汉两民族冠心病患者载脂蛋白E基因的多态性

目的探讨新疆乌鲁木齐地区维汉两民族冠心病患者载脂蛋白E基因多态性与冠心病的关系.方法用酚氯仿抽提核酸法从凝血块中分离DNA, 用聚合酶链反应-限制片长多态性方法对新疆乌鲁木齐地区维汉两民族124例冠心病患者和70例对照组人群进行载脂蛋白E基因多态性(由ε2、ε3和ε4决定的E2/2、E3/3、E4/4、E4/2、E4/3 和 E3/2)HhaI酶切研究.结果 (1)维吾尔族中载脂蛋白E ε2、ε3 和ε4等位基因频率分别为0.155±0.300、 0.648±0.342 和 0.197±0.246, 与汉族(0.081±0.196、 0.772±0.315 和 0.146±0.237)比较,ε2明显增高(P<0.05), ε3 和ε4虽有减低但无显著差别(P>0.05).(2)载脂蛋白E ε2、ε3和ε4等位基因频率在冠心病组的分布分别为0.060±0.198、 0.758±0.302 和 0.182±0.250, 与对照组(0.193±0.286、0.671±0.370 和 0.136±0.224)比较,ε2明显减低(P<0.01),维吾尔族中更明显(0.050±0.221对0.290±0.336,P<0.05), ε3 和ε4虽有升高但无显著差别(P>0.05).(3)由ε2到ε4 低密度脂蛋白胆固醇、总胆固醇和甘油三酯逐渐升高.将等位基因与冠心病其它危险因子一起作Logistic回归分析发现,ε2缺失(危险比RR=4.38,P<0.05)为冠心病的危险因子之一.结论新疆乌鲁木齐地区维汉两民族人群中(1)维族和汉族人群中载脂蛋白E基因型分布有非常显著性差异(P<0.01);维族人群中ε2 等位基因频率明显高于汉族.(2)冠心病患者载脂蛋白E ε2等位基因频率明显降低,其中维族更明显, ε3 和ε4 有所升高;从ε2到ε4,LDL、TG 和TC有升高趋势.(3)载脂蛋白E基因多态性(ε2等位基因缺失)为冠心病的危险因子之一,亦即ε2与冠心病呈负相关.     

A case of primary malignant fibrous histiocytoma of the pancreas： CT and MRI findings

Primary malignant fibrous histiocytoma （MFH） of the pancreas is rare and a distinct clinical entity. We report a case of recurrence of pancreatic MFH with computed tomography （CT） and magnetic resonance imaging （MRI） findings. A 67-year-old man presented with a history of decreased body weight over the past 6 mo. Abdominal CT revealed a large, multilocular cystic mass in the head of the pancreas with obvious atrophy in the body and tail of the pancreas. After 6 mo postoperatively, MRI demonstrated a recurrent large mass in the primary area of the head of the pancreas. The lesion was heterogeneous, hypointense to the liver on T1-weighted imaging, and heterogeneously hyperintense to the liver with a hypointense area in the central part of the tumor on fat-saturated T2-weighted imaging. Contrastenhanced T1-weighted imaging demonstrated a large multilocular cystic mass with a cystic wall, fibrous septa and enhancement of solid components. To the best of our knowledge, this is the first report on recurrence of primary MFH of the pancreas, and the first with MRI findings.     

肠出血性大肠杆菌O157:H7的分子生物学检测及PCR检测

大肠杆菌一些特殊的血清型具有致病性,肠出血性大肠杆菌是大肠杆菌的一个亚型,主要致病菌株为O157:H7,可引起感染性腹泻,因能引起人类的出血性肠炎而得名。本文综述了分子生物学检测肠出血性大肠杆菌O157:H7的研究进展。分子生物学检测是利用抗原抗体特异性结合反应检测各种物质的分析方法,主要包括酶联免疫吸附法(ELISA)、胶体免疫金层析法以及免疫磁珠分离法(IMS)。PCR技术检测肠出血性大肠杆菌O157:H7,主要包括常规PCR检测、多重PCR检测以及实时荧光定量PCR检测。这两种方法灵敏度高、特异性强、操作简便、结果准确等优点,是检测肠出血性大肠杆菌O157:H7的常用方法。     

Mechanism of cryopreserved porcine hepatocyte xenotransplantation in treating acute hepatic failure

AIM: To study the effect of hypothermia on structure of membrane proteins of pig hepatocytes and the mechanism of transplantation of cryopreserved porcine hepatocytes in treating acute hepatic failure in Wistar rats. METHODS: Isolated porcine hepatocytes were cryopreserved in liquid nitrogen for 150 d and then transplanted to the rat abdominal cavity. Three days later, 80% of rat liver by weight was resected. Conformation of membrane proteins of the porcine hepatocytes, liver function and weight of the remaining liver in the rats were measured. RESULTS: Viability of the cryopreserved hepatocytes was 78%. Light and electron microscopy showed that the hepatocytes were morphologically intact. The cells were rich in glycogen and glucose-6-phosphatase. The α-helix content in the membrane proteins of fresh cells was 48%. After freezing the cells, the content was increased to 59.5%. Survival rate of rats in the transplanted group was 16/17, significantly higher than 3/9 in the control group (P = 0.0022). However, there were no significant differences in the weight of the remaining liver or indices of liver function between the two groups. CONCLUSION: Transplant of frozen porcine hepatocytes is effective in treating acute hepatic failure. The mechanism is suggested to be a result of multiple effects. Hypothermia could increase α-helix content in the cellular membrane proteins, which might be related to the report that hypothermia was able to reduce the immunogenicity of the transplanted tissues and cells.     

豇豆干制技术总结

豇豆是我国人民喜食的蔬菜之一。但由于种植、收获集中于夏菜上市旺季,往往造成鲜品老化、变质与霉烂现象。为均衡蔬菜的全年供应,调济市场,我们在原民间传统方法的基础上研制了一套豇豆干制的方法。     

4种常见抗氧化剂对山桐子油氧化稳定性的影响比对分析

目的 对比分析4种不同抗氧化剂对山桐子油的抗氧化效果，筛选山桐子油脂抗氧化剂。方法 通过电感耦合等离子体质谱法和气相色谱法分析山桐子油的矿物质元素及脂肪酸组成，了解山桐子油的主要成分，采用Schaal烘箱加速氧化法以过氧化值(peroxide value，POV)、P-茴香胺值(P-anisidine value，PAV)、2-硫代巴比妥酸值(2-thiobarbituric acid value，TBA)为指标，对比分析不同抗氧化剂对山桐子油脂抗氧化效果的影响。结果 山桐子油的矿物质元素含量分别为：51.0392 mg/kg钙、39.7858 mg/kg镁、24.9281 mg/kg铁、16.5453 mg/kg钠、0.8787 mg/kg钾、0.7916 μg/kg铜、0.5765 μg/kg锰、0.2269 μg/kg锌；脂肪酸比例为：饱和脂肪酸16.75%（以棕榈酸为主），单不饱和脂肪酸9.56%（以油酸为主），多不饱和脂肪酸73.69%（以亚油酸为主）。没食子酸丙脂(propyl gallate，PG)和茶多酚（tea polyphenols，TP）在单抗氧化剂组中的抗氧化效果最好，而复配抗氧化剂抗氧化效果高于单一抗氧化剂。结论 在Schaal烘箱加速氧化中复配抗氧化剂组前期与单抗氧化剂组抗氧化效果相似，后期差异显著油脂氧化减缓，复配抗氧化剂可有效减缓山桐子油的氧化。复配氧化剂TG3（TP: 0.15 g/kg, PG: 0.0375 g/kg）抑制山桐子油脂氧化效果最佳，且均高于单一抗氧化剂样品。