织构对Cu-Al-Mn系形状记忆合金内耗的影响

In-situ observations on α/γ phase transformation were made to study the effects of grain boundary microstructures on the formation of a new phase and the migration of α/γ interphase boundary in an iron4. 2%Cr alloy. It was found that triple junctions with more random boundaries could be the primary nucleation sites for a new phase, while triple junctions with low angle or low ∑ coincidence boundaries did not play any role as preferential sites. The migration of α/γ interphase boundary during heating over the transformation temperature range showed the two stage behaviour characterized by a stage with a migration velocity of 0. 33-0. 75 mm/s and secondly by a stage with 3. 7-7. 6 mm/s. It was also found that abnormal grain growth and a high density of ∑3 coincidence boundaries could occur in a phase with bcc structure after cycling of α/γ phase transformation. A new mechanism of nucleation and growth of a new phase in α/γ phase transformation is proposed on the basis of roles of plane-matching interphase boundaries, as previously discussed on the origin of anisotropy of grain growth due to the migration of {110} plane-matching boundaries in Fe-3z%Si alloy. The most recent theoretical work on the distribution of plane-matching boundaries in solids with different crystal structures was found to be useful for the understanding of nucleation and growth during α/γ phase transformation.     

Mobility moment analysis of molecular interactions by capillary electrophoresis

A new method for the quantitative evaluation of molecular interactions that are observed in electrophoresis is described. One component taking part in the interaction is labeled with a fluorescent dye and is subjected to capillary zone electrophoresis with fluorescence detection in the presence or absence of an unlabeled interacting component. Fluorescence signals are collected at constant time intervals, and the electropherograms are converted to represent the fluorescence signal against mobility. After baseline subtraction, the first statistical moment of fluorescence signals on the mobility axis is calculated. This moment represents the average mobility of a labeled component. The change in the mobility moment in the presence and absence of the unlabeled component is used to evaluate the degree of saturation of the binding site of a labeled molecule with an unlabeled molecule. Mixtures of fluorescence-labeled protein (Fab' fragment of antibody or concanavalin A) and its unlabeled interacting partner (alpha(1)-antitrypsin or succinylated ovalbumin, respectively) at various concentrations were injected into a bare-silica capillary, and zone electrophoresis was carried out. The change in the mobility moment of the fluorescence-labeled molecules was used to determine the dissociation constants of the complexes. The determined constants are comparable to those obtained by a well-established method, that is, an analysis based on the peak height of the complex. Since the mobility moment analysis is not affected by the total intensity of the signals, it should be advantageous in analyses in which multiple capillaries are used, in which the injection volume and the sensitivity of detection might be more difficult to control at constant values. The mobility moment analysis also has advantages for the analysis of heterogeneous samples, since the identification of peaks is not necessarily required.     

Synthesis of continuous silicon carbide fibre

The structure of polycarbosilane is represented by three structural elements, but their quantification is difficult. Polycarbosilanes were synthesized by three methods and the respective molecular structures were examined by measurements of the molecular weight and the intrinsic viscosity, infrared, ultraviolet,¹H-,¹³C- and²⁹Si-NMR spectral measurements, and chemical analysis. The three structural elements (SiC₄, SiC₃H, SiC _x Si_4–x ) in the polycarbosilane molecule were determined quantitatively. By the comparison between¹H-NMR spectral data and calculation assuming a linear chain structure, the number of linkages in the unit consisting of ten silicon atoms was estimated to be 3 to 4. This result is in agreement with the result from the intrinsic viscosity; it was found that the shape of the polycarbosilane molecule is planar.     

淬火温度对Co40.5Ni34Al25.5合金相变和磁性的影响

用金相显微分析、DSC和VSM方法研究了Co40.5Ni34Al25.5合金马氏体相变和Curie点随淬火温度的变化,通过三点弯曲试验研究其形状记忆效果.结果发现该合金马氏体相变温度和Curie点与淬火温度成正比关系.马氏体相变的4种温度,即Ms,Mf,As和Af基本平行变化,淬火温度每升高10℃,马氏体相变温度和Curie点升高8℃～9℃.β相中Al的含量随淬火温度升高而降低,因而使马氏体相变温度和Curie点升高.1320℃淬火的Co40.5Ni34Al25.5合金的弯曲强度约为450 MPa,弯曲试验表明Co40.5Ni34Al25.5合金有双向形状记忆特性.     

Response of human epithelial cells to culture surfaces with varied roughnesses prepared by immobilizing dendrimers with/without D-glucose display

To investigate the response of human epithelial cells to substrates with nanoscale modifications, dendrimer-immobilized surfaces were prepared with or without D-glucose displayed as a terminal ligand, giving topographic structures with mean roughnesses (R(a)) of 1.8-11.0 nm. With an increase in the R(a) value up to 4.0 nm, the epithelial cells cultured on naked dendrimer surface without D-glucose display were somewhat stretched in their morphology compared with those on a nonmodified plain surface. However, for the R(a) values higher than 4.0 nm, such cell stretching was inhibited, resulting in the predominant existence of round-shaped cells. The change in cell morphology was appreciable on the surfaces with D-glucose-displayed dendrimers. When the R(a) value increased up to 4.5 nm on these surfaces, in particular, the enhancement of cell stretching was recognized, and fluorescence microscopic observation supported the hypothesis that the glucose-transporter-mediated adhesion of cells to the surface encouraged the development of filopodia and stress fibers, thereby improving focal contact with the surface. Our results suggest that the combination of displaying D-glucose and modulating roughness can promote cytoskeletal formation accompanied by marked cell elongation on culture surfaces.