6H-SiC单晶表面ZnO薄膜的制备及其结构表征

利用脉冲激光淀积(PLD)技术在6H-SiC单晶衬底上制备了ZnO薄膜. 利用X射线衍射(XRD), 反射式高能电子衍射(RHEED)和同步辐射掠入射X射线衍射(SRGID)φ扫描等实验技术研究了ZnO薄膜的结构. 结果表明:在单晶6H-SiC衬底上制备的ZnO薄膜已经达到单晶水平, 不同入射角的SRGID结果, 显示了ZnO薄膜内部不同深度处a方向的晶格弛豫是不一致的, 从接近衬底界面处到薄膜的中间部分再到薄膜的表面处, a方向的晶格常数分别为0.3264、0.3272和0.3223nm. 通过计算得到ZnO薄膜的泊松比为0.504, ZnO薄膜与单晶6H-SiC衬底在平行于衬底表面a轴方向的实际晶格失配度为5.84%.     

Vitamin E analogues as anticancer agents: lessons from studies with alpha-tocopheryl succinate

The new millennium has witnessed considerable decrease in a number of previously fatal pathologies, largely due to the advancement in molecular medicine and modern approaches to treatment. In spite of this success, neoplastic disease remains a serious problem due to several reasons. These include an exceedingly high variability of cancer cells even within the same type of tumour. Cancer cells, albeit of clonal origin, mutate so that they escape established treatments, resulting in the fatal outcome of current therapies. Moreover, there are types of cancer, such as mesotheliomas, that cannot be treated at present. A novel group of clinically interesting anticancer drugs has been a recent focus in the literature that hold substantial promise as selective anticancer drugs. These compounds, epitomised by alpha-tocopheryl succinate, comprise redox-silent analogues of vitamin E that have been shown to suppress several types of cancer in animal models, including breast, colon and lung cancer as well as mesotheliomas and melanomas, while being nontoxic to normal cells and tissues. It is now proven that the strong anticancer effect of vitamin E analogues stems from their propensity to induce selective apoptosis in malignant cells. The results point to the novel group of vitamin E analogues as promising agents applicable to different types of tumours.     

Montmorillonite adsorbs urea and accelerates urea excretion from the intestine

Hyperuraemia is one of the causes of uremia and renal failure. Decreasing serum urea level is an effective therapeutic method for patients with uremia and renal failure. Montmorillonite has very high affinity to various natural or synthetic toxins and has been widely used in biomedicine and clinical therapy. However, its effects on urea adsorption and excretion have not been fully explored. In the present studies, we systematically investigated the effects of montmorillonite on urea adsorption and excretion from the intestine. In vitro studies showed that montmorillonite concentration- and time-dependently adsorbed urea with high affinity. In vivo infusing urea into the blood vessel increased the urea concentration in the intestine, indicating that urea diffused from the blood vessels to the intestine. Infusing urea into the intestine increased the urea concentration in blood indicating that urea was absorbed in the intestine. Administrating montmorillonite in rat intestine significantly increased urea diffusion from the blood to the intestine and decreased urea absorption in the intestine. Orally administrating montmorillonite in normal mice as well as two types of model mice with acute hyperuraemia induced by orally administrating or intraperitoneally injecting urea, respectively, decreased blood urea levels. Our studies demonstrated that administrating montmorillonite has therapeutic potentials in patients with uremia.     

黄芩苷对错配修复基因缺失LoVo细胞的抑制作用及其机制

目的:探讨黄芩苷诱导LoVo细胞凋亡的作用及机制.方法:将黄岑苷40 mg溶于19.8 mL生理盐水 100 μL HCI 100 μL NaOH,阿斯匹林1.8 g溶于2 mL乙腈 4 mLNaOH 2 mLHCl,分别处理LoVo细胞,1 g/L乙腈溶液为对照.采用体外培养技术、TUNEL法观察细胞凋亡率,变性凝胶电泳检测微卫星标志BAT-25、D2S123状况.结果:黄芩苷和阿斯匹林均能诱导LoVo细胞凋亡,在各时间点与对照组比较统计学差异有显著意义(P=0.0000);黄芩对结肠LoVo细胞的诱导凋亡作用明显强于阿司匹林,24 h两差异无统计学意义,96 h和1 wk两者差异统计学有显著意义(93.33％ vs 44.23％,63.29％ vs23.20％,均P=0.0000),其作用时间在96 h达到高峰,与时间不呈依赖关系.黄芩苷和阿司匹林均未影响LoVo细胞的BAT-25、D2S123微卫星状态.结论:黄芩苷具有较强诱导LoVo细胞凋亡的作用.但对LoVo细胞的BAT-25、D2S123微卫星状态无影响,其诱导LoVo细胞凋亡可能是通过其它作用途径.     

髓过氧化物酶与冠状动脉慢血流的相关性

目的探讨髓过氧化物酶(MPO)与冠状动脉慢血流(CSF)之间的相关性。方法采用校正的TIMI血流帧数(CTFC)将随机入选600例经冠状动脉造影(CAG)确诊无冠状动脉狭窄病变并筛查出冠状动脉慢血流的52例患者作为研究对象,随机选择另外无冠状动脉慢血流的52例患者作为对照组。收集两组患者临床指标并测定血浆髓过氧化物酶及血液生化指标,分析两组之间差异,采用Logistic回归法筛选冠状动脉慢血流的危险因素。结果两组基线值相似;冠状动脉慢血流组血浆髓过氧化物酶浓度明显高于对照组(93.70±37.75μg/L比26.76±6.20μg/L,P0.001),差异有统计学意义;Logistic回归分析表明血浆髓过氧化物酶水平升高与冠状动脉慢血流有独立相关性(OR=1.23,P=0.001)。结论血浆髓过氧化物酶水平与冠状动脉慢血流发生密切相关,可以作为影响冠状动脉慢血流的重要血液生物化学指标。     

白花蛇舌草多糖对Bel7402细胞基因表达的影响

目的探讨白花蛇舌草多糖（HDP）对体外培养的人肝癌Bel7402细胞诱导凋亡的作用及可能的作用机制。方法人肝癌Bel7402细胞常规体外培养，设空白对照组、5-氟尿嘧啶（5-FU）凋亡对照组、HDP组。观察细胞形态变化，采用MTT法检测抑制率。RT—PCR法检测bel-xl、p53基因mRNA表达的变化。结果HDP抑制人肝癌Bel7402细胞生长、促进细胞凋亡，与空白对照组相比有显著差异（P〈0．01）；上调p53基因mRNA表达，降低bcl-xl基因mRNA表达，与空白对照组相比有显著差异（均P〈0．01）。结论HDP抑制人肝癌Bel7402细胞增长，诱导细胞凋亡，其分子机制可能与激活抑癌基因p53、抑制原癌基因bcl-xl表达有关。     

Solute diffusion in the γ′ phase of Ni based alloys

We systematically investigate the diffusion mechanisms of 3d (Ti–Cu), 4d (Zr–Ag) and 5d (Hf–Au) transition metal solutes in γ′-Ni₃Al phase using first-principles calculations. The results reveal that the diffusion of Ni-substituting solute is mainly controlled by the sublattice diffusion mechanism via Ni vacancies and the diffusion of Al-substituting solute is mostly governed by the formation of the anti-structure defects on the Ni sublattice with negligible contribution of the anti-structure bridge mechanism. The elements which occupy both the Al and Ni sites show a diffusion behavior similar to that of the Ni-substituting solutes. Our calculations show that larger atoms can move much faster than smaller atoms, which disprove the traditional view that larger atoms move slower than smaller atoms.     

地形图点状符号的自动提取和识别

针对扫描地形图的点状符号, 提出了一种基于距离变换进行提取和识别的新方法. 首先优化分版图的提取结果, 根据弯曲密度和线划密度过滤掉非点状符号的线划, 利用加壳变换和蜕皮变换进行点状符号的图文分离. 然后根据加权距离函数来度量符号的全局特征, 由骨架线的一致性来度量符号的几何形状特征, 并结合这两个特征来识别点状符号. 最后, 提出了错切文字注记和线状要素注记的识别方法.