Measurement and correlation of mutual diffusion coefficients for styrene-butadiene rubber(SBR)-n-nonane systems

The mutual diffusion coefficients for styrene-butadiene rubber(SBR)-n-nonane systems were measured using a sorption apparatus with a quartz spring at 100 and 130°C for mass fractions of n-nonane ranging from 0 to 0.16. The mutual diffusion coefficients were correlated with good agreement by the free-volume theory.     

Giant room-temperature magnetoresistance in single-crystal Fe/MgO/Fe magnetic tunnel junctions

The tunnel magnetoresistance (TMR) effect in magnetic tunnel junctions (MTJs) is the key to developing magnetoresistive random-access-memory (MRAM), magnetic sensors and novel programmable logic devices. Conventional MTJs with an amorphous aluminium oxide tunnel barrier, which have been extensively studied for device applications, exhibit a magnetoresistance ratio up to 70% at room temperature. This low magnetoresistance seriously limits the feasibility of spintronics devices. Here, we report a giant MR ratio up to 180% at room temperature in single-crystal Fe/MgO/Fe MTJs. The origin of this enormous TMR effect is coherent spin-polarized tunnelling, where the symmetry of electron wave functions plays an important role. Moreover, we observed that their tunnel magnetoresistance oscillates as a function of tunnel barrier thickness, indicating that coherency of wave functions is conserved across the tunnel barrier. The coherent TMR effect is a key to making spintronic devices with novel quantum-mechanical functions, and to developing gigabit-scale MRAM.     

Rate of emulsion polymerization of styrene

In emulsion polymerization, the Smith and Ewart theory gives about two or three times the number of polymer particles obtained by experiment. In this paper, a reaction model is proposed which, from the standpoint of reactor design, can give an adequate explanation of the whole course of an emulsion polymerization of monomer highly insoluble in water. Among other things, the generating process of polymer particles is examined in detail. It is demonstrated experimentally that a new parameter proposed here, which represents the degree of difficulty of monomer initiation in micelles, is indispensable in explaining that process. Also confirmed is that monomer initiation takes place more easily in polymer particles than in micelles. According to the new model, the progress of polymerization, i.e., monomer conversion, the number of the polymer particles, and properties of polymer thus produced can be estimated with satisfactory accuracy. Furthermore, approximate equations are derived for easier estimation.     

Real Space Imaging of the Electronic States in Underdoped Ca2−x Na x CuO2Cl2 Single Crystals

Scanning tunneling microscopy (STM) has been performed on underdoped Ca_2–x Na _x CuO₂Cl₂ (Na-CCOC) single crystals to investigate the electronic states of doped Mott insulators near the metal-insulator transition. STM images taken at 7 K show patch-like or river-like irregular features superposed on the atomic corrugations. The irregular structure has a characteristic length scale of 20 Å, which is unchanged in different samples and at different doping levels studied (0.08<x<0.12). Bias voltage dependence of the STM image suggests that Na-CCOC consists of two distinct phases with different electronic states.     

Specific Heat of the Surface Layers on the Amorphous Substrate in Solid and Liquid 3He

We have observed an excess heat capacity in liquid and bcc solid ³He at low temperatures. The heat capacity in the normal fluid is found to be the sum of the heat capacity of bulk normal fluid and a temperature-independent heat capacity C due to amorphous solid layers on the silver sinter surface, where C=7.3±6.8 JK^–1m^–2 corresponds to 1.6±0.6 amorphous solid layers. The heat capacity for bcc solid ³He is the sum of the heat capacity originating from the multiple-exchange interaction and a temperature independent heat capacity. The excess heat capacity C=12.1±3.1 JK^–1m^–2 for bcc solid corresponds to 1.9±0.3 amorphous solid layers. Our result indicates that the amorphous solid layers on an amorphous substrate yield a universal C in unit area throughout liquid, solid and adsorbed ³He.     

Retardation‐controlling color filter with two directly stacked retardation layers

Abstract— A polymerizable liquid crystal (PLC), the orientation of which can be frozen, is useful for making retardation layers. In this paper, a new color filter (CF) with retardation‐controlling layers made of PLC is reported. It has a positive A‐plate and a negative C‐plate, both directly stacked on a color‐filter layer. These two retardation layers exhibit good orientation ability, and function well as retarders, even when they are only 1/10 or less as thick as ordinary retardation films. The new CF also has excellent thermal stability. The change in retardation after heat treatment at 200°C for 30 min is around 5%, and there is no observable peeling. A prototype VA‐LCD made with our new CF provides good optical compensation, with the light leakage being extremely low in all azimuthal directions. This technology is very useful for making thin, highly reliable color filters for LCDs, even with other modes.     

High‐efficiency light‐collection optics for lamp‐based projection TV

Abstract— A new light‐collection optics has been developed that enhances the luminance of projection TV which use lamps as the light source. The conventional optical system consists of an elliptical reflector and a flat‐surface front glass, but these systems cannot sufficiently collect the beams coming from the light source, and they cause loss in the coupling with the light pipe. To solve this problem, we devised a new optical system through a structure of an aspherical reflector and an aspherical front glass. This new optical system concentrates the beams coming from the light source to a smaller point which improves the coupling efficiency. Thus, we have successfully increased the luminance of the projection TV by approximately 10%. This paper reports the design principles of the new optical system and the results of a prototype experiment.     

Nonlinear repetitive control with application to trajectory control of manipulators

In this article, a new control scheme named repetitive control is proposed for a class of nonlinear systems described by x(t) = Ax(t) + Bu(t) + n(x(t)) and y(t) = Cx(t), in which the controlled variables follow periodic reference commands. The stability condition is derived by applying the passivity theorem. We show how to apply the repetitive control scheme to the trajectory control of a manipulator. A simple repetitive control scheme is developed for the trajectory control of a manipulator by using nonlinear compensation and feedbacks of position and velocity signals. Experimental results for a three link manipulator verify that the proposed repetitive control reduces the tracking error to a very low level.