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A detailed mathematical model is presented to describe the steady state behavior of a continuous multizone tubular reactor for the synthesis of aromatic polycarbonate by interfacial polycondensation mechanism. In this process, bisphenol-A dissolved in a dispersed aqueous phase reacts with phosgene dissolved in a continuous organic phase and hence, the reaction initiates at the interface of the two phases. A liquid-liquid mass transfer process is incorporated into a reaction kinetic model to calculate the reaction rates and polymer molecular weight distribution. The kinetic model has also been used in developing a steady state multizone tubular reactor model for continuous production of polycarbonate. The model simulations are compared with proprietary plant data and excellent agreement has been obtained., INTRODUCTION Aromatic polycarbonates derived from bisphenol A (BPA) are an important class of engineering polymers with a wide variety of applications such as in water bottles, food containers, optics, mobile [...]

The surface and edge emissions from dye-filled and dye-topped polycarbonate and polymethyl methacrylate luminescent solar concentrators were measured. We demonstrate that about 40-50% of the absorbed light energy (and 50-70% of the photons) is lost through the top and bottom surfaces of the filled waveguide. In most cases the escape cone losses are greater at the top than the bottom surface. OCIS codes: 350.6050, 350.5500, 310.2785, 260.2510, 230.7390, 160.5470.

Microfluidic devices have gained significant scientific interest due to the potential to develop portable, inexpensive analytical tools capable of quick analyses with low sample consumption. These qualities make microfluidic devices attractive for point-of-use measurements where traditional techniques have limited functionality. Many samples of interest in biological and environmental analysis, however, contain insoluble particles that can block microchannels, and manual filtration prior to analysis is not desirable for point-of-use applications. Similarly, some situations involve limited control of the sample volume, potentially causing unwanted hydrodynamic flow due to differential fluid heads. Here, we present the successful inclusion of track-etched polycarbonate membrane filters into the reservoirs of poly(dimethylsiloxane) capillary electrophoresis microchips. The membranes were shown to filter insoluble particles with selectivity based on the membrane pore diameter. Electrophoretic separations with membrane-containing microchips were performed on cations, anions, and amino acids and monitored using conductivity and fluorescence detection. The dependence of peak areas on head pressure in gated injection was shown to be reduced by up to 92%. Results indicate that separation performance is not hindered by the addition of membranes. Incorporating membranes into the reservoirs of microfluidic devices will allow for improved analysis of complex solutions and samples with poorly controlled volume.

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.icarus.2006.02.002 Byline: Satoru Yamamoto (a), Koji Wada (b), Norihisa Okabe (a), Takafumi Matsui (a) Keywords: Cratering; Impact processes; Collisional physics Abstract: We experimentally studied the formation and collapse processes of transient craters. Polycarbonate projectiles with mass of 0.49 g were impacted into the soda-lime glass sphere target (mean diameters of glass spheres are [approximately equal to]36, 72, and 220 [mu]m, respectively) using a single-stage light-gas gun. Impact velocity ranged from 11 to 329 mas.sup.-1. We found that the transient crater collapses even at laboratory scales. The shape (diameter and depth) of the transient crater differs from that of the final crater. The depth-rim diameter ratios of the final and transient craters are 0.11-0.14 and 0.26-0.27, respectively. The rim diameter of both the transient and final crater depends on target material properties; however, the ratio of final to transient crater diameter does not. This suggests that target material properties affect the formation process of transient craters even in the gravity regime, and must be taken into account when scaling experimental results to planetary scales. By observing impacts into glass sphere targets, we show that although the early stage of the excavation flow does not depend on the target material properties, the radial expansion of the cavity after the end of vertical expansion does. This suggests that the effect of target material properties is specifically important in the later part of the crater excavation and collapse. Author Affiliation: (a) Graduate School of Frontier Sciences, University of Tokyo, Kashiwanoha, Kashiwa, Chiba 277-8562, Japan (b) Institute of Low Temperature Science, Hokkaido University, Sapporo 060-0819, Japan Article History: Received 1 June 2005; Revised 31 January 2006

The hypervelocity impact experiments on SS400 steel with a polycarbonate projectile at velocities up to 9km/s are performed. The calculated results using the value of 13 GPa as the transition pressure showed that the duration necessary for the phase transition is about 150 ns for impact velocity of 8.8 km/s.