Overview no. 113 surface motion by surface diffusion

Geometry growth laws for morphological change are developed and examined for the class of dynamic problems where surface diffusion is the only transport mechanism and hence volume is conserved, attachment kinetics is treated, and the only driving force for surface motion is the reduction in total surface free energy. The two limiting laws in the isotropic case are: motion by the Laplacian of mean curvature as originally derived by Mullins, and motion by the difference between mean curvature and the average of mean curvature. A general law linking these limiting laws is formulated, and derived both from a physical model and from gradient flows. Anisotropic laws are given. We survey possible mathematical techniques for studying interface motion under all these laws. Among these are possible applications of modified phase field methods.     

挤压表面致密化和滚压表面致密化工艺对比

选择表面致密化工艺主要包括挤压致密化和滚压致密化,本文基于表面致密化零件的生产,从零件性能检测方面对比分析挤压致密化和滚压致密化工艺的差异性。试验结果表明：两种工艺制备出的零件在齿廓处均能形成一层均匀的表面致密层,零件的表面强度和表面硬度均得到较大提高;挤压致密化工艺会导致烧结件端面翻边,容易造成后续烧结件外观质量问题,而滚压致密化工艺则不会产生类似外观质量问题;挤压致密化工艺中零件挤压进给量取决于模具尺寸,挤压进给量无法随意调整,并且随着模具径向尺寸的磨损,挤压进给量会变化且不可控,而滚压致密化工艺通过调节两副滚轮模具中心轴的距离,可以快速调整零件滚压进给量,制备出符合要求的表面致密层。因此,滚压致密化工艺优于挤压致密化工艺。     

Efficacy of various surface disinfectants on an irregular surface

Skin contact electrodes require electrolyte gels between the skin and the electrode in order to ensure good electrical contact. The effect of different types of electrolyte gel on skin impedance was studied. The main types of gels used were wet gels, karaya-gum based hydrogels and synthetic copolymer-based hydrogels [2-acrylamide-2-methylpropanesulfonic acid-N,N'-methylenebis(acrylamide) copolymers]. The effect of variation in gel composition on the impedance of the skin was investigated.     

Ti-TiNi-HfNi-Hf Liquidus surface

Physical and chemical analysis methods are used for the first time to examine the Ti-TiNi-HfNi-Hf alloys in the melting-crystallization region. The liquidus surface is shown to consist of six fields of primary phase crystallization: λ₁, η, δ, θ, β, and α. The largest fields are of δ-and β-phases. The λ₁ ternary phase is formed by peritectic reaction l + δ → λ₁. There are five invariant equilibria involving liquid on the Ti-TiNi-HfNi-Hf solidus surface. The liquidus surface, vertical sections, and alloy crystallization scheme are constructed.     

表面波等离子体暴露下铜表面的氧化特性

Surface wave plasma(SWP) is a kind of low temperature plasma which can be utilized for material development.In this research,argon and oxygen were used as a working gas for an SWP experiment and the influence of the plasma irradiation on a copper surface was examined.Particular,relation between the spatial characteristics of SWP and wetting characteristics was examined.As a result,it was found that spatial characteristics of the SWP affected the wetting characteristics and the oxidation characteristics.     

Effect of surface topography of titanium on surface chemistry and cellular response

A number of aryl semicarbazones had been shown previously to possess significant anticonvulsant properties. The principal objective of the present investigation was to determine the importance of the primary amino group in this series of compounds by replacing it with other substituents. The results indicate that the amino group was not essential for anticonvulsant activity. However its replacement by an aryl ring generally abolished activity while a terminal phenylamino function was better tolerated. Thus both the size of the group and its hydrogen bonding capabilities appear to influence bioactivity. Alteration of the oxygen atom of the semicarbazones by isosteres did not enhance anticonvulsant properties.     

Binocular visual surface perception

Binocular disparity, the differential angular separation between pairs of image points in the two eyes, is the well-recognized basis for binocular distance perception. Without denying disparity's role in perceiving depth, we describe two perceptual phenomena, which indicate that a wider view of binocular vision is warranted. First, we show that disparity can play a critical role in two-dimensional perception by determining whether separate image fragments should be grouped as part of a single surface or segregated as parts of separate surfaces. Second, we show that stereoscopic vision is not limited to the registration and interpretation of binocular disparity but that it relies on half-occluded points, visible to one eye and not the other, to determine the layout and transparency of surfaces. Because these half-visible points are coded by neurons carrying eye-of-origin information, we suggest that the perception of these surface properties depends on neural activity available at visual cortical area V1.