Dynamic mechanical properties and morphology of styrene-divinylbenzene copolymer/poly(vinyl chloride) systems. (II). Effect of polymerization temperature

Effect of polymerization temperature on the phase-separated structure of the composite materials [P(St-DVB)/PVC systems] prepared by copolymerization of styrene (St) and divinylbenzene (DVB) in the presence of fine poly(vinyl chloride) (PVC) powder was studied by electron microscopy and dynamic mechanical test. P(St-DVB)/PVC systems have the two-phase nature with a styrene-divinylbenzene copolymer as the continuous phase [P(St-DVB) phase) and a PSt/PVC composite as the dispersed phase (PSt-PVC phase), in which PSt penetrates into the PVC domain. The crosslinking density of the P(St-DVB) phase is larger than that estimated from the recipe in the feed, suggesting that there exists a difference of the diffusion constants of styrene and divinylbenzene into the PVC particles on the paste formation and the polymerization process. The changes of the phase-separated structure of P(St-DVB)/PVC systems polymerized at various temperatures are also explained on the basis of the difference between the diffusion behavior of styrene and that of divinylbenzene into fine PVC particles at these temperatures.     

Numerical study on an asymmetric guided-mode resonant grating with a Kerr medium for optical switching

Optical switching effects of a guided-mode resonant grating (GMRG) with a Kerr medium have been simulated with the nonlinear finite differential time domain (FDTD) method. An asymmetric waveguide grating with a large second spatial harmonic component has been proposed for the optical switch. Resonant reflection occurs at both of the band-edge wavelengths. These wavelengths are used for the pump light and the probe light. The enhanced electric field of the pump light changes the resonant wavelength for the probe light as a result of the Kerr effect. We designed the GMRG with resonant wavelengths of 1489.6 and 1630 nm, which were used for the pump light and the probe light, respectively. When the grating material has a third-order susceptibility chi(3) of 8.5 x 10(-10) esu, the transmittance of the probe light changes from 0 to 80% by increasing the intensity of the pump light from 0 to 60 kW/mm2.     

Deposition of chlorophyll-a Langmuir-Blodgett films onto an SnO2 optically transparent electrode

The deposition of chlorophyll-a monolayers onto an SnO₂ optically transparent electrode was studied in relation to the deposition ratio. The values of the deposition ratio, which were approximately 0.95 for the upward movement and very small but non-zero for the downward movement, suggest that the multilayers prepared are Z-type films containing a small fraction of the Y-type component corresponding to the non-zero value. This is consistent with the photo- electrochemical behaviour of the pigmented electrodes which is markedly dependent on the deposition ratios, indicating structural inhomogeneity or imperfection of the multilayers.     

Combustion of fuel vapor-drop-air systems: Part II—Spherical flames in a vessel

The burning characteristics of fuel vapor-drop-air systems (propane-kerosene drop-air systems) have been studied using a cylindrical combustion vessel, 58 mm deep and 148 mm in diameter, with a centrally located spark gap. As in the case of burner flames reported in the previous paper, a small amount of kerosene drops added to a propane-air mixture intensities the burning process, raising the maximum pressure for an overall fuel-air ratio and shrotening the time to reach the maximum pressure from ignition. In addition, both the burning and propagating velocities of a flame for an overall fuel-air ratio are markedly accelerated by a very small amount of kerosene drops added. The combustion-promoting effects of drops are more prominent for leaner mixtures and get less prominent as the mixture becomes richer beyond the stoichimetric. An optimum value exists in the quantity of drops added to a propane-air mixture.     

Threshold voltage of ion implanted GaAs MESFET

Threshold voltages for ion implanted GaAs MESFETs are measured and shown to have good coincidence with calculated results. The effect of implantation energy on threshold voltage is discussed. The optimum implantation energy is about 45 ~ 60 keV.     

Enhanced proliferation of fetal rat hepatocytes in primary culture induced by ritodrine

OBJECTIVE: Although ritodrine crosses the placenta, its direct effect on fetal cell proliferation has not been reported. We hypothesized that beta 2-adrenergic receptor stimulation could promote fetal liver growth. STUDY DESIGN: Ritodrine was added to serum- and hormone-free primary cultures of fetal, neonatal, or adult rat hepatocytes. We measured both tritiated thymidine incorporation into deoxyribonucleic acid and nucleus number. The effect of ritodrine on cell cycle was also analyzed with flow cytometry. RESULTS: Ritodrine enhanced the proliferation of fetal rat hepatocytes. Ritodrine remarkably stimulated deoxyribonucleic acid synthesis of fetal and neonatal but not adult hepatocytes. The effect was dose dependent and was antagonized by propranolol. Analysis of the nuclear deoxyribonucleic acid content derived from flow cytometry revealed that cells stimulated by ritodrine entered S phase. CONCLUSION: These results indicate that ritodrine may promote the proliferation of fetal hepatocytes through the stimulation of beta 2-adrenergic receptors, followed by induction of deoxyribonucleic acid synthesis.     

Removal mechanisms for endocrine disrupting compounds (EDCs) in wastewater treatment - physical means, biodegradation, and chemical advanced oxidation: a review

Endocrine disrupting compounds (EDCs) are pollutants with estrogenic or androgenic activity at very low concentrations and are emerging as a major concern for water quality. Within the past few decades, more and more target chemicals were monitored as the source of estrogenic or androgenic activity in wastewater, and great endeavors have been done on the removal of EDCs in wastewater. This article reviewed removal of EDCs from three aspects, that is, physical means, biodegradation, and chemical advanced oxidation (CAO).