QUANTIFICATION OF SHEAR DAMAGE EVOLUTION IN ALUMINIUM ALLOY 2024T3

Shear damage may occur in the process of metal machining such as blanking and cutting, where localized shear deformation is developed. Experimental findings indicate that microscopic shear damage evolution in aluminium alloy 2024T3 (A1 2024T3) is a multi-stage mechanism, including particle cracking, micro-shear banding, matrix microcracking and coalescence of microcracks. This study is an attempt to use a set of equations to describe the multi-stage shear damage evolution in Al 2024T3. The shear damage variables in terms of multi-couple parameters of a power-law hardening material have been defined. An evolution curve of shearing damage has been calculated from experimental data. The values of the shear damage variable at different stages of damage have also been calculated. By making use of the findings, the relation between the microscopic shear damage evolution and the macroscopic shear response of the material has been discussed.     

橡胶门尼粘度标准物质的研制

介绍橡胶门尼粘度标准物质的研制过程。该标准物质的均匀性、稳定性良好,定值准确可靠,符合JJG1006－94的要求。     

应力波和动光弹等差条纹的分析与判读

介绍了动光弹的基本原理，并从理论上回答了动光弹应用中的一些问题，如惯性力可否忽略等．并在总结回顾动光弹等差条纹级次判读方法的基础上，提出了把应力波理论与等差条纹分析判读相结合的方法，这样不仅使条纹判读的概念更清晰，而且可提高条纹分析和级次判读的准确性．     

Enabling drug discovery project decisions with integrated computational chemistry and informatics

Computational chemistry/informatics scientists and software engineers in Genentech Small Molecule Drug Discovery collaborate with experimental scientists in a therapeutic project-centric environment. Our mission is to enable and improve pre-clinical drug discovery design and decisions. Our goal is to deliver timely data, analysis, and modeling to our therapeutic project teams using best-in-class software tools. We describe our strategy, the organization of our group, and our approaches to reach this goal. We conclude with a summary of the interdisciplinary skills required for computational scientists and recommendations for their training.     

Experimental and theoretical analysis of bias ionization by?α-particles in a nitrogen laser

Nitrogen laser performance with TE configuration and wedge electrodes is analyzed with background ionization in the laser discharge channel by α particles at a low exposition rate. With the bias ionization, the laser power presents two peaks as a function of gas pressure, with one at the normal low pressure, without bias ionization, and the other at high pressure generated by bias ionization. A simple theoretical model has been developed in a trial to understand this behavior. This model was first tested in later results for a TE configuration nitrogen laser, with flat electrodes, without and with bias ionization. It has been observed that due to the competition between electrode shielding by positively charged α particles and bulk ionization by impact, the laser energy is suppressed with pressure below 50 Torr and enhanced above it.     

Dicarboxylic acid promoted immortal copolymerization for controllable synthesis of low‐molecular weight oligo(carbonate‐ether) diols with tunable carbonate unit content

Low‐molecular weight oligo(carbonate‐ether) diols are important raw materials for polyurethane formation, which with tunable carbonate unit content (CU) may endow new thermal and mechanical performances to polyurethane. Herein, facile synthesis of oligo(carbonate‐ether) diols with number average molecular weight (M_n) below 2000 g mol^?1 and CU tunable between 40% and 75% are realized in high activity by immortal copolymerization of CO₂/propylene oxide (PO) using zinc‐cobalt double metal cyanide complex (Zn‐Co‐DMCC) in the presence of sebacic acid (SA). M_n of the oligomer is in good linear relationship to the mole ratio of PO and SA (PO/SA) and hence can be precisely controlled by adjusting PO/SA. Besides, the molecular weight distribution is quite narrow due to the rapid reversible chain transfer in the immortal copolymerization. High pressure and low temperature are favorable for raising CU. In all the reactions, the weight fraction of propylene carbonate (W_PC) can even be controlled as low as 2.0 wt %, and the catalytic activity of Zn‐Co‐DMCC is above 1.0 kgg^?1 cat. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Self-organization of a carbide superlattice during deposition of carbon on Mo

Formation and evolution of a carbide superlattice (SL) during C deposition on Mo have been studied using molecular beam epitaxy techniques. The ordering of the SL is energetically driven, such that the interplay between strain and surface energies determines the length scale of the SL. Surface precipitation of C occurs within a narrow range of SL spacing that appears to control the size and spacing of the precipitates leading to a possible mechanism for nucleation of single-walled carbon nanotubes.     

Left ventricular 4D echocardiogram motion and shape analysis

The article describes the methodology and the processes of modeling the function and the motion of left ventricle using transesophageal echocardiograph. The parameters can be used in studying the functionality of left ventricle, the status of abnormality of myocardial, and the geometric and morphological of left ventricle in shape analysis. The parameters describes the motion of left ventricle are the left ventricular (LV) floating long axis, the morphological parameters. The LV morphological parameters describe the wall motion, the LV chamber cavity variation, the effective R-ratio of endomyocardial chamber of LV, the area surface curvature, and the global surface curvature circularity. The parameters such as stroke volume, ejection fraction used in evaluation of LV functions are also extracted.     

Experimental observation of a striking similarity between quantum hall transport coefficients

The derivative of the Quantum Hall resistance, ρ_xy, with respect to the carrier density, n, has been measured for a two-dimensional electron gas in a GaAs-Al_xGa_1?xAs heterostructure, as a function of magnetic field. dρ_xy/dn exhibits a remarkable similarity to the diagonal resistivity, ρ_xy, to the extent that one is almost directly proportional to the other. Our result suggests the possibility of a fundamental connection between the two quantities.