Total and subcellular distribution of trace elements in the liver of a mother-fetus pair of Dall's porpoises (Phocoenoides dalli)

Total and subcellular hepatic Zn, Cu, Se, Mn, V, Hg, Cd, and Ag were determined in a mother-fetus pair of Dall's porpoises (Phocoenoides dalli). Except for higher fetal Cu concentration, all maternal elements were higher. Elements existed mostly in the cytosol of both animals except in the case of maternal Ag in the microsome and fetal Cu and Ag in the nuclei and mitochondria. In the maternal cytosol, Zn, Mn, Hg, and Ag were present in the high-molecular-weight substances (HMW); Se and V were present in the low-molecular-weight substances (LMW); Cu and Cd were mostly sequestered by metallothionein (MT). In the fetal cytosol, Zn, Se, Mn, Hg, Cd, and Ag were present in the HMW and V in the LMW, while Cu and Ag were mostly associated with MT. MT isoforms were characterized using the HPLC/ICP-MS. Two and four obvious peaks appeared in the maternal and fetal MT fractions, respectively. The highest elemental ion intensities were at a retention time of 7.8 min for the mother, and for the fetus the peak elemental ion intensities occurred at a retention time of 4.3 min, suggesting that different MT isoforms may be involved in elemental accumulation in maternal and fetal hepatocytosols. (C) 2003 Elsevier Ltd. All rights reserved.

Double proton transfer and one-electron oxidation behaviors in double H-bonded glycinamide-formamidine complex and comparison with biological base pair

The behaviors of double proton transfer (DPT) occurring in a representative glycinamide-formamidine complex have been investigated employing the B3LYP/6-311++G** level of theory. Computational results suggest that the participation of a formamidine molecule favors the proceeding of the proton transfer (PT) for glycinamide compared with that without mediator-assisted case. The DPT process proceeds with a concerted mechanism rather than a stepwise one since no zwitterionic complexes have been located during the DPT process. The barrier heights are 14.4 and 3.9 kcal/mol for the forward and reverse directions, respectively. However, both of them have been reduced by 3.1 and 2.9 kcal/mol to 11.3 and 1.0 kcal/mol with further inclusion of zero-point vibrational energy (ZPVE) corrections, where the lower reverse barrier height implies that the reverse reaction should proceed easily at any temperature of biological importance. Additionally, the one-electron oxidation process for the double H-bonded glycinamide-formamidine complex has also been investigated. The oxidated product is characterized by a distonic radical cation due to the fact that one-electron oxidation takes place on glycinamide fragment and a proton has been transferred from glycinamide to formamidine fragment spontaneously. As a result, the vertical and adiabatic ionization potentials for the neutral double H-bonded complex have been determined to be about 8.46 and 7.73 eV, respectively, where both of them have been reduced by about 0.79 and 0.87 eV relative to those of isolated glycinamide due to the formation of the intermolecular H-bond with formamidine. Finally, the differences between model system and adenine-thymine base pair have been discussed briefly.

Self-assembly of a polymer pair through poly(lactide) stereocomplexation

A polymer pair composed of poly( N-isopropylacrylamide-co-2-hydroxyethyl methacrylate terminated oligo( L-lactide)) ( poly( NIPAAm-co-HEMAOLLA)) graft random copolymer and poly( D-lactide) ( PDLA) homopolymer was self-assembled into micelles with a diameter around 100 nm through the stereocomplexation between the OLLA branches of the graft copolymer and the PDLA homopolymer. The specific intermolecular stereocomplexation was considered as the powerful ordered aggregation force in the micelle cores. The shell's component of poly( NIPAAm-co-HEMA) and its thermosensitivity were proved by H-1 nuclear magnetic resonance ( NMR) and dynamic light scattering ( DLS), respectively. The incorporation of PDLA homopolymer into the graft copolymer affected the micelle size and the critical micelle concentration ( CMC). The incorporation of even a small quantity ( 11 wt%) of PDLA into the graft copolymer micelles resulted in a great decrease of the micelle size. For the graft copolymer with low per cent grafting of 18%, the size of the corresponding micelles decreased slightly even if the PDLA content increased up to 33 wt%. For the graft copolymer with high per cent grafting of 58%, with the further increase of PDLA content, the size of the corresponding micelles at first decreased further and then began to increase. The molecular weight of the PDLA did not significantly affect the micelle size.

Ab initio pair potentials at metal-ceramic interfaces

A systematic approach is proposed to obtain the interfacial interatomic potentials. By inverting ab initio adhesive energy curves for the metal-MgO ceramic interfaces, We derive interfacial potentials between Ag and O2-, Ag and Mg2+, Al and O2-, Al and Mg2+. The interfacial potentials, obtained from this method, demonstrate general features of bondings between metal atoms and ceramic ions.

Molecular dynamics simulation of hydrogen enhancing dislocation emission

The interactive pair potential between Al and H is obtained based on the ab initio calculation and the Chen-Mobius 3D lattice inversion formula. By utilizing the pair potentials calculated, the effects of hydrogen on the dislocation emission from crack tip have been studied. The simulated result shows that hydrogen can reduce the cohesive strength for Al single crystal, and then the critical stress intensity factor for partial dislocation emission decreases from 0.11 MPa root m (C-H = 0) to 0.075 MPa root m (C-H=0.72%) and 0.06 MPa root m (C-H = 1.44%). This indicates thar hydrogen can enhance the dislocation emission. The simulation also shows that atoms of hydrogen can gather and turn into small bubbles, resulting in enhancement of the equilibrium vacancy concentration.

The W-11-4A platform comprehensive strength monitoring system

A comprehensive strength monitoring system used on a fixed jacket platform is presented in this paper. The long-term monitoring of W-11-4A platform achieved. Structural responses (strain and acceleration) at selected locations, as well as associated environmental parameters, have been obtained. The emphasis of the paper is placed on the system design, and the instrumentation and operation methodology employed in the monitoring of the structural responses. The performance of the system and the characteristic results obtained during its 13-month operation are also summarized.

涠11-4平台结构动态响应监测结果分析(涠11-4平台原位监测研究之二)

本文总结了针对涠１１－４平台一年多时间的应变和加速度监测数据的处理分析工作，详细介绍了所用的数据处理方法，给出了应变数据的统计结果及长期分布规律。通过对应变和加速度信号进行频谱分析，揭示了平台在多种环境条件下的振动特性。

涠11-4平台综合强度监测技术及实施运行系统(涠11-4平台结构原位监测研究之一)

本文介绍了一种固定式导管架平台综合强度监测系统，它用于对涠１１－４平台关键部位的应力、加速度及与结构响应相关的环境参数进行长期监测。讨论的重点内容是结构响应的测量方案、设备及实施方法，并对运行结果作了说明

Molecular dynamics studies on the local disordering of σ3 and σ11 grain boundaries in aluminium bicrystal

Molecular dynamics (MD) simulations using Morse interaction potential are performed in studies of [110] symmetrical tilt grain boundary (GB) structures with mis-orientation angles 50.5 degrees(Sigma 11), 129.5 degrees(Sigma 11), 70.5 degrees(Sigma 3) and 109.5 degrees(Sigma 3) at various tempratures. The GB structures are found to start local disordering at about 0.5T(m)(T-m is the melting point of aluminium) for 50.5 degrees(Sigma 11), 0.32T(m) for 129.5 degrees(Sigma 11) and 0.38T(m) for 70.5 degrees(Sigma 3), respectively. These results agree with conclusions deduced from the anelastic measurements. But, for twin-boundary structure 109.5 degrees(Sigma 3), this disordering has not been found even when temperature increases up to 0.9T(m).

TiC原位增强块状Cu_(47)Ti_(34)Zr_(11)Ni_8非晶合金复合材料

在电弧炉中利用吸铸法制备了直径1-4 mm的原位生成TiC和β-Ti枝晶联合增强的块状Cu47Ti34Zr11Ni8非晶合金复合材料.DSC热分析结果表明,原位生成TiC颗粒的引入,没有影响基体合金的非晶形成能力.用OM,XRD,SEM,EDS等方法研究了复合材料的相组成、微观组织以及成分分布,结果表明,TiC颗粒作为异质形核中心促进了β-Ti枝晶的形成,形成了TiC颗粒和β-Ti枝晶联合增强的块状Cu47Ti34Zr11Ni8非晶合金复合材料,而且β-Ti枝晶的尺寸和数量与TiC颗粒的多少以及试样的尺寸有关.室温压缩试验表明,同单相非晶合金相比,块状Cu47Ti34Zr11Ni8非晶合金复合材料提高了抗压强度及塑性.

第11届国际快淬和亚稳材料会议简介

第11届国际快淬和亚稳材料会议于2002年8月24~30日在英国牛津大学召开，本次会议由牛津大学材料系承办． 200多名来自欧洲、美国、加拿大、日本、韩国、印度、巴西、澳大利亚、新西兰、中国等29个国家的代表参加了本次大会．会议宣读口头报告244篇，张贴论文117篇，其中包括大会报告11篇，邀请报告31篇．会议论文经严格评审后由Materials Science and Engineering A杂志选择收录．下届会议将于2005年在韩国举行．

涠11-平台结构强度全尺度原位监测研究

以力学为主线而进行的多学科综合的研究。主要工作包括平台结构应力、加速度和风、浪、流环境的监测与分析,疲劳分析和寿命估算,极端环境条件下平台人员工作安全性评估,以及数据的采集和处理技术。研究结果给定了与海洋平台结构设计和运行安全密切相关的力学规律和重要资料,为平台结构的强度设计与评估提供了实用依据。