Growth and optical properties of peculiar ZnO tetrapods

Regular ZnO tetrapods with different morphologies have been obtained on Si(100) substrate via the chemical vapour deposition approach. Varying the growth temperature and gas rate, we have obtained different structured ZnO materials: tetrapods with a large hexagonal crown, a flat top and a small hexagonal crown. The results suggest that these tetrapods are all single crystals with a wurtzite structure that grow along the (0001) direction. However, photoluminescence spectra shows that their optical properties are quite different: for those with large hexagonal crown, the green emission overwhelms that of the near band-edge (NBE) ultraviolet (UV) peak, while others have only a strong NBE UV peak at ~386 nm.

Numerical Study Of Pile-Up In Bulk Metallic Glass During Spherical Indentation

Pile-up around indenter is usually observed during instrumented indentation tests on bulk metallic glass. Neglecting the pile-up effect may lead to errors in evaluating hardness, Young's modulus, stress-strain response, etc. Finite element analysis was employed to implement numerical simulation of spherical indentation tests on bulk metallic glass. A new model was proposed to describe the pile-up effect. By using this new model, the contact radius and hardness of Zr41.2Ti13.8Cu12.5Ni10Be22.5 bulk metallic glass were obtained under several different indenter loads with pile-up, and the results agree well with the data generated by numerical simulation.

强脉冲CO_2激光对红外材料的破坏现象

实验表明强激光对红外材料的破坏分为两种类型:烧蚀和冲击破坏。在空气中,光功率密度低于大气的光学击穿阈值时,以烧蚀为主。超过击穿阈值时,冲击破坏是主要的。在我们的实验条件下,用强激光辐照红外脆性材料的靶,靶极易产生微裂纹或粉碎性破坏,其破坏效果与激光的脉冲能量、功率密度、脉冲宽度,以及着靶面积有关。为了直观,文中给出了不少辐照损伤的照片。

Displacive To Order-Disorder Two-Step Phase Transition Model For Para-Ferroelectric Transition

Two-step phase transition model, displacive to order-disorder, is proposed. The driving forces for these two transitions are fundamentally different. The displacive phase transition is one type of the structural phase transitions. We clearly define the structural phase transition as the symmetry broking of the unit cell and the electric dipole starts to form in the unit cell. Then the dipole-dipole interaction takes place as soon as the dipoles in unit cells are formed. We believe that the dipole-dipole interaction may cause an order-disorder phase transition following the displacive phase transition. Both structural and order-disorder phase transition can be first-order or second-order or in between. We found that the structural transition temperatures can be lower or equal or higher than the order-disorder transition temperature. The para-ferroelectric phase transition is the combination of the displacive and order-disorder phase transitions. It generates a variety of transition configurations along with confusions. In this paper, we discuss all these configurations using our displacive to order-disorder two-step phase transition model and clarified all the confusions.

飞秒激光脉冲作用下氧化镁的烧蚀及其超快动力学过程

研究了双面抛光氧化镁单晶（111）表面800nm飞秒激光单脉冲烧蚀阈值和激光脉宽的依赖关系。利用泵浦-探针技术，测量不同能量和脉宽作用下飞秒激光烧蚀的时间分辨反射率的演化．通过扫描电镜观察其烧蚀形貌，发现大量的沿氧化镁[100]晶向开裂的裂纹．讨论了表面裂纹的形成机理，并解释了飞秒激光烧蚀氧化镁的超快动力学过程。

非晶状体βγ-晶状体蛋白与三叶因子蛋白复合物的细胞核转运及其选择性杀伤肿瘤细胞机制的研究

非晶状体βγ晶状体蛋白与三叶因子蛋白复合物(βγ-CAT)是从大蹼铃蟾(Bombina maxima)皮肤分泌物中分离的分子量为72 kDa的天然蛋白复合物.本研究通过激光共聚焦显微镜和Westem blot分析βγ-CAT在人脐静脉内皮细胞(HUVEC)中的细胞核转运机制,以及βγ-CAT对多株肿瘤细胞(HCT116,HT29,A375,Hela,THP-1等)的细胞毒效应.结果表明:βγ-CAT的α亚基中含有典型的GTP/ATPase的保守结构模体Walker A和Walker B,体外检测到βγ-CAT具有GTP/ATP水解酶和GTP/ATP结合活性.在细胞核转运过程中,βγ-CAT的α亚基和β亚基参与形成约150kDa含有泛素化修饰信号的大分子复合物,且泛素化修饰信号和βγ-CAT的α亚基和β亚基共定位于细胞内和融合于细胞核区域的转运囊泡小体中.βγ-CAT能够选择性的杀伤肿瘤细胞,诱导肿瘤细胞脱落和发生凋亡.上述结果为进一步深入研究阡βγ-CAT的细胞核转运和调节细胞功能的分子作用机制提供思路和线索.