Optical properties of polystyrene and polyarylate block copolymer and their control by morphology generation

Relationship between phase morphology and optical properties of polystyrene and polyarylate (PS‐PAr) block copolymers synthesized from telechelic polystyrene has been investigated. In the PS‐PAr block copolymers, the PAr domains with higher melt viscosity were dispersed in the PS phase matrix with lower melt viscosity over the wide range of their composition from PS/PAr = 25/75 to 75/25 (wt ratio). The PAr domain size was dependent on the reactive ratio of PAr determined analogously by the mole fraction of the fed telechelic polystyrene. By controlling the mole fraction of the telechelic polystyrene more than 0.016 in synthesizing the PS‐PAr block copolymer, the size of PAr domains could be reduced to the microscopic scale (smaller than 100 nm). Then, the PS‐PAr block copolymers exhibited almost the same transparency as PAr in spite of the large difference in the refractive index between the PS and the PAr phase. Birefringence free condition for the PS‐PAr block copolymers was determined by not only the PS/PAr composition but also the balance in the degree of molecular orientation of these chains. The latter factor suggests that PS and PAr chains undergo inhomogeneous stress and relaxation history during the injection process. By controlling Mn (number average molecular weight) and weight fraction of the fed OH‐PS‐OH around 20 000 and 55 wt %, respectively, in the synthesis of the PS‐PAr block copolymer, the PS‐PAr block copolymer exhibited almost zero birefringence without any sacrifice of transparency. Because in the PS‐PAr block copolymer low birefringence and high transparency can coexist by controlling the adequate feeding condition in the synthesis process, the PS‐PAr block copolymer would be a promising material for optical applications, such as a substrate of optical disks or optical lenses. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 953–961, 2000     

Reversible cross-linking reactions of alkoxyamine-appended polymers under bulk conditions for transition between flow and rubber-like states

Reversible cross-linking reactions of alkoxyamine-appended polymers with low glass transition temperature (T_g) were successfully carried out under bulk conditions. The low-T_g polymers with alkoxyamine units in the side chains were synthesised by radical copolymerisation of 2-ethylhexyl acrylate and two kinds of alkoxyamine-containing acrylate monomers. By heating the low-T_g polymers under bulk conditions at 100 °C, cross-linked polymers were formed by radical exchange reactions between alkoxyamine units, and a transition from a liquid-like flowable polymer state to a rubber-like polymer state was confirmed. A de-cross-linking reaction was also accomplished by radical exchange reactions between the cross-linked polymers and an added alkoxyamine-containing small molecule or stable nitroxyl radical, which resulted in transition to the flowable state again. The structural transition between low-T_g linear polymers and cross-linked polymers were characterised by ¹H and ¹³C NMR spectroscopy, Fourier transform infrared spectroscopy, rheology measurement, swelling experiment, and gel permeation chromatography measurement.     

Structure-activity relationship of 3,3'-dihydroxy-alpha,beta-diethyldiphenylethane and its related compounds

3,3'-Dihydroxy-alpha,beta-diethyldiphenylethane (I), 3,3'-dihydroxy-alpha,beta-diethylstilbene (II), hexestrol (III) and diethylstilbestrol (IV) have already been reported to show hypotensive effects on rats and exhibit phytogrowth-inhibitory activities. We have proposed that two phenolic hydroxyl groups in these compounds are necessary for the biological activities, and a structure-activity relationship for I-related compounds was accomplished using molecular-mechanics (MM) calculations. As a result, the following three findings were obtained; 1) the minimized conformational energy obtained from MM calculations, which is a parameter expressing the molecular stability, showed a relatively high correlation with the biological activities, 2) as results of quantitative structure-activity relationship (QSAR) analyses, the combination of the distance between two phenolic hydroxyl oxygens led to the regression equations with high correlation values, and 3) the idealized molecular model of the most active compound (I) showed the highest stability and had a particular conformation which differed from the other compounds (II-IV).     

Interfacial tension of phase-separated3He−4He mixtures at saturated vapor pressure

The interfacial tension of³He−⁴He mixtures at saturated vapor pressure has been measured precisely down to 0.15 K by means of the resonance of the interfacial wave. We found that the decrease of the interfacial tension from the value at absolute zero can be described as 56.8T ² mdyne/cm up to about 0.4 K and that the extrapolated value at absolute zero is 23.9±1.0 mdyne/cm. The large temperature dependence in the low temperature region may be explained by the effect of the change in density difference between the two phases.     

Stability Analysis and Experimental Validation of a Motion-Copying System

This paper examines the stability of our proposed motion-copying system in the case that the environmental mechanical impedance is changed. The system preserves and reproduces the motion of the human operator. The examination of this paper derives the transfer function of the motion-loading system considering the environmental impedance and investigates displacement of the poles with the transition of the environment. Moreover, the experiment with respect to environmental changing is carried out. These results confirm theoretically and experimentally that the motion-copying system is stable even if the environment is changed. The haptic informational processing technique by the motion-copying system is useful for industrial applications and medical engineering.     

Robust damping control of power oscillation incorporating parametric resonance

In this paper we consider a damping control of low‐frequency oscillations in an electric power system. On the basis of the hypothesis that an auto‐parametric resonance model can explain a power oscillation, we propose a new model for a robust damping control, by which the system maintains stability even if some auto‐parametric resonance happens. With this model, we can express a parametric variation of a principal oscillation mode and a class of uncertainties which cover neglected dynamics. Since the model has a certain structure of uncertain parameters, we design a robust controller via µ‐synthesis. The robust controller which can be obtained from the presented design strategy has the property that the control performances are more sophisticated in comparison to controllers designed with other existing methods based on the H_∞ control. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 142(1): 42–49, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10069     

DPM2 regulates biosynthesis of dolichol phosphate-mannose in mammalian cells: correct subcellular localization and stabilization of DPM1, and binding of dolichol phosphate

Biosynthesis of glycosylphosphatidylinositol and N-glycan precursor is dependent upon a mannosyl donor, dolichol phosphate-mannose (DPM). The Thy-1negative class E mutant of mouse lymphoma and Lec15 mutant Chinese hamster ovary (CHO) cells are incapable of DPM synthesis. The class E mutant is defective in the DPM1 gene which encodes a mammalian homologue of Saccharomyces cerevisiae Dpm1p that is a DPM synthase, whereas Lec15 is a different mutant, indicating that mammalian DPM1 is not sufficient for DPM synthesis. Here we report expression cloning of a new gene, DPM2, which is defective in Lec15 cells. DPM2, an 84 amino acid membrane protein expressed in the endoplasmic reticulum (ER), makes a complex with DPM1 that is essential for the ER localization and stable expression of DPM1. Moreover, DPM2 enhances binding of dolichol phosphate, a substrate of DPM synthase. Mammalian DPM1 is catalytic because a fusion protein of DPM1 that was stably expressed in the ER synthesized DPM without DPM2. Therefore, biosynthesis of DPM in mammalian cells is regulated by DPM2.     

Clinical evaluation of CEA in patients with urologic cancer (author''s transl)]

This study examines the role of 1) personal job-related needs and 2) certain organizational characteristics in affecting overall job satisfaction for a sample of 259 laboratory professionals, primarily medical technologists. Specific individual needs and specific organizational characteristics were found to be related to three measures of overall job satisfaction. Additional comparisons were made for administrators versus non-administrators and for differences associated with different sized organizations. Implications for the managers of medical technologists and other laboratory professionals are discussed.     

1480-1510 nm band Tm-doped fibre amplifier with high powerconversion efficiency of 42%

The highest reported overall power conversion efficiency of 42% using a high Tm³⁺ concentration-doped fluoride fibre amplifier (TDFA) with one colour 1.4 μm pumping and a double pass configuration for S-band amplification has been achieved. This TDFA was used for a successful 8×10 Gbit/s WDM transmission     

Tracking control for industrial robot using notch filtering system with little phase error

This paper proposes a new method for generation of a position reference that has both vibration suppression performance and fast tracking performance for industrial robots. It is important for industrial robots to drive at high speed and with high accuracy. In such cases, vibration is generated. Conventionally, the notch filter is used in order to reduce vibration. It is able to eliminate the natural frequency component, but a reference phase error is generated. The reference phase error causes locus error in the robot. Therefore, the accuracy of the robot is degraded by using a notch filter. The proposed method overcomes this problem by using the compensation gain. The proposed compensation gain is used in order to calculate the reference phase error. Compensation of the reference phase error is attained by feedforward input. Numerical and the experimental results confirm that the proposed method is valid for reducing vibration phenomena and that it decreases the phase error. © 2011 Wiley Periodicals, Inc. Electr Eng Jpn, 175(1): 53–63, 2011; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.20931