Plastic macrodeformation of polycrystalline and submicrocrystalline titanium for biomedical applications

The deformation behavior of commercially pure submicrocrystalline and coarse-grained titanium was studied at the macroscopic level. Stress-strain curves of the materials were analyzed. Time-space distributions of local strains were studied at all stages of strain hardening using speckle interferometry. The life time of test specimens of the materials and the coordinates of the fracture region were calculated theoretically and confirmed experimentally. The motion of the zones of localized plasticity was studied. The prefracture stage was shown to involve “condensation” of the zones of localized plasticity and migration of deformation to the fracture neck. __________ Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 49, No. 3, pp. 164–172, May–June, 2008.     

Applications of the ergodic iteration theorem

I prove several natural preservation theorems for the countable support iteration. This solves a question of Ros?anowski regarding the preservation of localization properties and greatly simplifies the proofs in the area (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

NaCl胁迫下对刺槐叶片质膜H+~ATPase的影响

本文以二倍体刺槐和四倍体刺槐为试验材料，利用电子显微镜细胞化学方法对H+~ATPase进行定位，电镜下观察的黑色铅沉淀量与H+~ATPase的活性成正相关，结果表明：NaCl胁迫显著地提高了两种刺槐质膜的H+~ATPase活性，随着盐胁迫时间的延长，二倍体刺槐的质膜H+~ATPase活性呈现先上升再降低的趋势，而四倍体刺槐质膜H+~ATPase活性在整个实验过程中均呈现上升趋势，因此质膜H+~ATPase可能在四倍体刺槐的抗盐胁迫过程中起着重要作用。     

基于压缩感知的无线传感器网络节点定位算法

为了得到有效的、通用的定位算法,提出了两种新的定位算法——基于压缩感知的无线传感器网络节点定位算法（NLCS）及其改进算法（INLCS）.NLCS算法利用压缩感知和加权质心算法进行节点位置估计.提出了伪跳数以改进NLCS算法,提升了算法的定位性能.这两种算法解决定位问题必须满足3个条件,使其更适合于实际应用.仿真结果表明,相对于LSRC和LSVM定位算法,这两种算法有更好的定位性能.     

驾驶员疲劳检测中的眼睛定位与状态分析

针对驾驶员头部多角度变化时眼睛定位困难的现状,提出了基于肤色检测和纹理特征的驾驶员眼睛定位算法.该算法采用肤色检测定位出人脸图像;根据眼睛灰度范围与其他部位的差异进行人脸图像二值化和形态学图像处理,确定眼睛候选区域;通过比较各候选区域纹理特征向量值的不同,确定眼睛位置,并基于黑斑拟合椭圆性质进行眼睛验证和睁开程度计算.计算结果表明,头部角度变化时各候选区域的纹理特征值差别仍较大.因此,该算法不受驾驶员头部角度的影响,眼睛定位准确率较高,且算法简单,计算速度快.     

Localization in Spatially Disordered Systems: Screening and Band Structure Effects at the EMA Level

Abstract

An analysis is given of Anderson localization in a one-band tight-binding model with off-diagonal disorder characteristic of a quenched liquid-like structure. We extend a localization criterion due to Logan and Wolynes, based on a self-consistent determination of the most probable value of the imaginary part of the site self-energy, to include screening arising from many-body terms in the renormalized perturbation series. Liquid state methods are used to examine screening, as embodied in an effective energy and density dependent transfer matrix element, at the level of the effective medium approximation. It is shown that this effective transfer matrix element is screened in high energy regions and anti-screened in low energy regions, so that extended states tend to occur in the low energy low density of states regime. Theoretical predictions for the mobility edge trajectories are found to be in reasonable agreement with recent computer simulations. The effects of the short-ranged structure of the system are also examined.     

Electronic fluxes during diels‐alder reactions involving 1,2‐benzoquinones: mechanistic insights from the analysis of electron localization function and catastrophe theory

By means of the joint use of electron localization function (ELF) and Thom's catastrophe theory, a theoretical analysis of the energy profile for the hetero‐Diels‐Alder reaction of 4‐methoxy‐1,2‐benzoquinone 1 and methoxyethylene 2 has been carried out. The 12 different structural stability domains obtained by the bonding evolution theory have been identified as well as the bifurcation catastrophes (fold and cusp) responsible for the changes in the topology of the system. This analysis permits finding a relationship between the ELF topology and the evolution of the bond breaking/forming processes and electron pair rearrangements through the reaction progress in terms of the different ways of pairing up the electrons. The reaction mechanism corresponds to an asynchronous electronic flux; first, the O1? C5 bond is formed by the nucleophilic attack of the C5 carbon of the electron rich ethylene 2 on the most electrophilically activated carbonyl O1 oxygen of 1 , and once the σ bond has been completed, the formation process of the second O4? C6 bond takes place. In addition, the values of the local electrophilicity and local nucleophilcity indices in the framework of conceptual density functional theory accounts for the asychronicity of the process as well as for the observed regioselectivity. © 2012 Wiley Periodicals, Inc.     

Radical Localization in a Series of Symmetric NiII Complexes with Oxidized Salen Ligands

Square‐planar nickel(II) complexes of salen ligands, N,N′‐bis(3‐tert‐butyl‐(5R)‐salicylidene)‐1,2‐cyclohexanediamine), in which R=tert‐butyl ( 1 ), OMe ( 2 ), and NMe₂ ( 3 ), were prepared and the electronic structure of the one‐electron‐oxidized species [ 1 – 3 ]^+. was investigated in solution. Cyclic voltammograms of [ 1 – 3 ] showed two quasi‐reversible redox waves that were assigned to the oxidation of the phenolate moieties to phenoxyl radicals. From the difference between the first and second redox potentials, the trend of electronic delocalization 1 ^+.> 2 ^+.> 3 ^+. was obtained. The cations [ 1 – 3 ]^+. exhibited isotropic g tensors of 2.045, 2.023, and 2.005, respectively, reflecting a lower metal character of the singly occupied molecular orbital (SOMO) for systems that involve strongly electron‐donating substituents. Pulsed‐EPR spectroscopy showed a single population of equivalent imino nitrogen atoms for 1 ^+., whereas two distinct populations were observed for 2 ^+.. The resonance Raman spectra of 2 ^+. and 3 ^+. displayed the ν_8a band of the phenoxyl radicals at 1612 cm^?1, as well as the ν_8a bands of the phenolates. In contrast, the Raman spectrum of 1 ^+. exhibited the ν_8a band at 1602 cm^?1, without any evidence of the phenolate peak. Previous work showed an intense near‐infrared (NIR) electronic transition for 1 ^+. (Δν_1/2=660 cm^?1, ε=21 700 M ^?1 cm^?1), indicating that the electron hole is fully delocalized over the ligand. The broader and moderately intense NIR transition of 2 ^+. (Δν_1/2=1250 cm^?1, ε=12 800 M ^?1 cm^?1) suggests a certain degree of ligand‐radical localization, whereas the very broad NIR transition of 3 ^+. (Δν_1/2=8630 cm^?1, ε=2550 M ^?1 cm^?1) indicates significant localization of the ligand radical on a single ring. Therefore, 1 ^+. is a Class III mixed‐valence complex, 2 ^+. is Class II/III borderline complex, and 3 ^+. is a Class II complex according to the Robin–Day classification method. By employing the Coulomb‐attenuated method (CAM‐B3LYP) we were able to predict the electron‐hole localization and NIR transitions in the series, and show that the energy match between the redox‐active ligand and the metal d orbitals is crucial for delocalization of the radical SOMO.     

基于均布荷载面曲率的板类结构损伤定位研究

基于均布荷载面曲率方法对不同工况下的板类结构进行了损伤定位.该方法仅需要板结构损伤前和损伤后的前三阶模态频率和模态振型就可准确定位损伤位置.采用中心差分法构造了x和y方向的均布荷载面曲率,并成功地运用到板类结构的损伤定位中.数值模拟讨论了固定支承和三边固支时3种损伤情况下均布荷载面曲率方法的定位效果.研究发现:固定支承板中度面损伤时,均布荷载面曲率方法仅用第一阶模态数据就能有效定位损伤;而且均布荷载面曲率差值随着参与模态阶数的增加收敛得很快;轻度点损伤和多处损伤能够大致定位.