Strain-Induced Grain Refinement of Cobalt During Surface Mechanical Attrition Treatment

The microstructural evolution during surface mechanical attrition treatment of cobalt (a mixture of hexagonal close packed (hep) and face-centered cubic (fcc) phases) was investigated. In order to reveal the mechanism of grain refinement and strain accommodation. The microstructure was systematically characterized by both cross-sectional and planar-view transmission electron microscopy. In the hcp phase, the process of grain refinement. Accompanied by an increase in strain imposed in the surface layer. Involved: (1) the onset of 110 111 deformation twinning, (2) the operation of (1 120) 110 1 0} prismatic and (1 120) (000 1) basal slip, leading to the formation of low-angle dislocation boundaries, and (3) the successive subdivision of grains to a finer and finer scale. Ressulting in the formation of highly misoriented nanocrystalline grains. Moreover. The formation of nanocrystalliies at the grain boundary and triple junction was also observed to occur concurrently with straining. By contrast. The fec phase accommodated strain in a sequence as follows: (1) slip of dislocations by forming intersecting planar arrays of dislocations, (2) {1 1 1} deformation twinning, and (3) the gamma(fcc) --> epsilon(hcp) martensitic phase transformation. The mechanism of grain refinement was interpreted in terms of the structural subdivision of grains together with dynamic recrystallization occurring in the hep phase and the gamma --> E: martensitic transformation in the fcc phase as well.

微桥结构铜膜杨氏模量和残余应力研究

采用MEMS(MicroelectromechanicalSystems)技术研制了铜 (Cu)膜微桥结构试样 ,应用陶瓷压条为承力单元 ,并与纳米压痕仪XP系统的Berkovich三棱锥压头相结合 ,解决了较宽Cu膜微桥加载问题。测量了微桥载荷与位移的关系 ,并结合微桥力学理论模型得到了Cu膜微桥的杨氏模量及残余应力 ,其值分别为 115 .2GPa和 19.3MPa ,与应用纳米压痕仪直接测得的带有Si基底的Cu膜杨氏模量 110± 1.6 7GPa相吻合。

Ba（NO3）2晶体受激拉曼散射的角度分布和脉冲压缩(英文)

报道了利用重复频率为30HZ，波长为532nm的Nd：YAG倍频激光单次通过抽运硝酸钡（Ba（NO3）2）晶体（晶体由水溶液降温法生长，长度为48mm，横截面为10mm×10mm），获得高效率的一阶（563nm），二阶（599nm）和三阶（639nm）斯托克斯光的实验结果．硝酸钡晶体沿着[110]晶轴方向切割．观测到一、二、三阶斯托克斯光呈锥形环分布，一、二、三阶斯托克斯光的散射外边缘与抽运光轴线间的夹角大小分别为1．7°，3．5°，5．0°．同时也观测到Ba（NO3）2的SRS角度分布与抽运光强度无关．

Characterization and expression analysis of TNF-related apoptosis inducing ligand (TRAIL) in grass carp Ctenopharyngodon idella

TRAIL (Apo2 ligand) described as a type II transmembrame protein belonging to the TNF superfamily can induce apoptotic cell death in a variety of cell types. In the present study, a putative cDNA sequence encoding the 299 amino acids of TRAIL (GC-TRAIL) and its genomic organization were identified in grass carp Ctenopharyngodon idella. The predicted GC-TRAIL sequence showed 44 and 41% identities to chicken and human TRAILs, respectively. In a domain search, a tumor necrosis factor homology domain (THD) was identified in the C-terminal portion of TRAILs. The GC-TRAIL gene consists of five exons, with four intervening introns, spaced over approximately 4 kb of genomic sequence. Analysis of GC-TRAlL promoter region revealed the presence of a number of putative transcription factor binding sites, such as Sp1, NF-kappaB, AP-1, GATA, NFAT, HNF, STAT, P53 and IRFI sequences which are important for the expression of other TNF family members. Phylogenetic analysis placed GC-TRAIL and the putative zebrafish (Danio rerio) TRAIL obtained from searching the zebrafish database into one separate cluster near mammalian TRAIL genes, but apart from the reported zebrafish TRAIL-like protein, indicating that the GC-TRAIL is an authentic fish TRAIL. Expression analysis revealed that GC-TRAIL is expressed in many tissues, such as in gills, liver, trunk kidney, head kidney, intestine and spleen. (c) 2005 Elsevier B.V. All rights reserved.

六联苯超薄膜与弱取向外延生长

有机半导体薄膜的形态结构对器件性能具有非常重要的影响，近年来高质量有机半导体薄膜的制备成为有机半导体薄膜器件研究的核心内容之一。弱取向外延生长能够获得类单晶迁移率的高质量有机半导体薄膜。而制备出高取向、大尺寸、低缺陷、连续的高质量外延生长基底是获得类单晶外延薄膜的前提条件，这样就需要深入了解它们的生长行为、生长机理及薄膜相态特性。因此，高质量外延基底生长和弱取向外延生长行为及机理的研究就具有十分重要的理论价值和实用价值，是选择和扩展弱取向外延生长材料体系的基础。由此，本论文中工作主要分为两部分，第一部分工作是对外延基底六联苯超薄膜生长的研究：一方面生长出大尺寸、高取向、连续的超薄膜为弱取向外延生长提供高质量的外延基底，另一方面丰富和发展了有机半导体薄膜生长理论。第二部分工作是对酞菁化合物在六联苯超薄膜上弱取向外延生长行为和机理的研究，为弱取向外延材料体系的选择与扩展提供实验依据和理论指导。 首先，研究了六联苯超薄膜生长行为。研究结果表明：(1) 六联苯超薄膜在高温(＞60 oC)和低温(≤60 oC)的二氧化硅(SiO2)基底上生长具有不同的生长机理：高温时薄膜生长符合扩散受限凝聚生长(DLA)机理，低温时薄膜生长是由低有序薄膜经过亚稳分解后重组向团状岛转变。(2) 六联苯超薄膜的生长行为和相结构表明单层和双层薄膜是两种不同的相态：单层薄膜是高取向的具有液晶特性的薄膜相态，双层薄膜是长程有序的近似体相β-phase结构的结晶相。(3) 通过优化基底温度和生长参数，可以制备出高取向、大尺寸、连续的六联苯超薄膜，即可以为酞菁化合物的弱取向外延生长提供高质量的外延基底。 然后，以平面型自由酞菁(H2Pc)及酞菁锌(ZnPc)和非平面型酞菁氧钒(VOPc)为例，深入研究了酞菁化合物在六联苯超薄膜上的弱取向外延生长行为及机理。研究结果表明：(1) 弱取向外延生长的酞菁分子在六联苯超薄膜上立着生长，p-p共轭的方向平行于基底，同时酞菁分子在薄膜平面内具有规则的取向织构。这种高取向的酞菁化合物薄膜有利于载流子在薄膜平面内的传输，其迁移率达到了相应的单晶水平。(2) 由于六联苯双层及单层薄膜结构和相态的差别，平面型酞菁化合物表现出不同的外延生长行为：在六联苯双层薄膜上生长的酞菁化合物薄膜在薄膜平面内只有一种取向，对应于有公度外延生长(Commensurate Epitaxy)；在六联苯单层薄膜上生长的酞菁化合物薄膜在薄膜平面内有三种取向，同时兼具有公度外延生长和无公度外延生长(Incommensurate Epitaxy)。但非平面型VOPc由于分子排列方式及三斜晶体结构的本质，在六联苯单层及双层薄膜上都只表现出无公度外延生长。(3) 六联苯(001)晶面上突起的氢原子所形成的[110]、[1-10]和[010]沟道对酞菁分子具有强烈的预取向作用，从而形成取向的单分子柱晶核。然后在晶格匹配效应和基底沟道效应下，分别形成有公度外延生长和无公度外延生长。即晶格匹配关系和基底沟道效应为寻找弱取向外延生长有机半导体材料体系提供了理论指导依据。

结构参数对GaN肖特基紫外探测器性能的影响及器件设计

研究了GaN肖特基结构(n~--GaN /n~+-GaN)紫外探测器的结构参数对器件性能的影响机理.模拟计算结果表明:提高肖特基势垒高度和减小表面复合速率,不仅可以增加器件的量子效率,而且可以极大地减小器件的暗电流;适当地增加n~--GaN层厚度和载流子浓度可以提高器件的量子效率,但减小n~--GaN层的载流子浓度却有利于减小器件的暗电流.我们针对实际应用的需要,提出了一个优化器件结构参数的设计方案,特别是如果实际应用中对器件的量子效率和暗电流都有较高的要求,肖特基势垒高度应该≥0.8 eV,n~--GaN层的厚度≥200 nm,载流子浓度1×10~(1)7 cm~(-3) 左右,表面复合速率＜1×10~7 cm/s.

Sequential deprotonation of meso-(p-hydroxyphenyl)porphyrins in DMF: From hyperporphyrins to sodium porphyrin complexes

Sequential deprotonations of meso-(p-hydroxyphenyl)porphyrins (p-OHTPPH2) in DMF + H2O (V/V = 1:1) mixture have been verified to result in the appearance of hyperporphyrin spectra. However, when the deprotonations of these p-OHTPPH2 are carried out in DMF, the spectral changes differ considerably from those in the mixture mentioned above. At low [OH-], the optical spectra in the visible region are still considered to have characteristics of hyperporphyrin spectra. Further deprotonation at much higher basicity makes the optical spectra form three-banded spectra similar to those in the acidic solution. To clarify the molecular origins of these changes, UV-vis, resonance Raman (RR), proton nuclear magnetic resonance (H-1 NMR) experiments are carried out. Our data give evidence that p-OHTPPH2 in DMF can be further deprotonated of pyrrolic-H by higher concentrated NaOH, due to an aprotic medium like DMF effectively weakening the basicity of the porphyrin relative to that of the NaOH, and coordinates with two sodium ions (except the sodium ions that interact with the peripherial phenoxide anions) to form the sodium complexes of p-OHTPPH2 (Na2P, to lay a strong emphasis on the sodium ions that coordinate with the central nitrogen atom), which can be regarded as the porphyrin anions being perturbed by the sodium cations due to their highly ionic character.

氧化镧离子电极的研制

将氧化镧混合在不同母体材料中,研制出几种类型的氧化镧离子电极,并研究了电极的性能。首次发现,电化学聚合的含有氧化镧的聚吡咯薄膜可以作为镧离子选择性电极膜。还发现,虽然都用同一种活性材料,各种电极随母体材料不同其性能有所不同.最佳电极线性范围为1×10~(-1)～1×10~(-5)mol/L。内充液式和石墨为基底的镧离子选择电极,适宜的pH范围为2.8～6.1。以二次标准加入法测定已知样品,结果比较理想。

辐射法研制功能高分子膜离子选择电极活性材料

用辐射接枝工艺合成了功能高分子膜活性材料,并对其进行了表征,测定了以此为活性材料的离子选择电极性能。结果发现,硫酸根电极在10~(-1)—10~(-3)mol/L Na_2SO_4溶液中响应时间<70s,斜率为52mV/PSO_4~(2-);氯离子电极的线性范围1×10~(-1)—2×10~(-4)mol/L,检测下限为8×10~(-5)mol/L,稳定性好,寿命长,响应时间<5s,内阻<60kΩ,抗毒化能力强。从稀土离子选择电极中发现,以辐射接枝工艺合成的材料比化学法合成的好,前者斜率为53 mV/PGd,后者斜率为46 mV/PGd;预辐照接枝工艺合成的材料比共辐照接枝工艺的好些。

新型导电聚合物——聚吡咯溴离子化学传感器

本文用电化学方法把导电聚合物聚吡咯(PPy)修饰在玻碳(GC)电极上,研究了Br~-离子的掺杂效应和薄膜电极的电化学行为,研制一种新型Br~-离子选择电极,电极的响应机制是基于导电聚合物中阴离子的掺杂效应,详细研究了聚合条件对电极电位响应性能的影响,电极具有内阻小、响应快、抗毒化能力强、制备简便等优点,电极对1×10~(-1)—1×10~(-4)MBr~-呈能斯特响应,检测下限7×10~(-5)M,斜率61mV/PBr~-。本文结果是化学修饰电极技术在化学传感器方面应用的有意义的尝试。薄膜的良好导电性质使之更易于制备离子敏感电子学器件和生物电子学器件。

用ICP-AES法测定高纯氧化铥中十四种稀土杂质

本文研究了ICP-AES法测定高纯氧化铥中十四种其它稀土杂质的方法。研究了有机溶剂的影响,加热去溶效果等。确定了折衷工作条件。本方法可以测定99.99%高纯氧化铥中十四种稀土杂质,回收率为82.5-110%相对标准偏差为1.9-9.3%。

铒离子选择电极的研制

在功能高分子稀土电极研制的基础上改进活性材料制备过程,成功的试制了新型的铒电极,其线性范围1×10~(-1)M～1×l10~(-5)M,检测下限达1×10~(-5)M,在室温下斜率为59mV,内忸小于200kΩ,性能稳定,寿命在6个月以上,并能在有缓冲液存在下测量稀土。