Comparison of chemical and enzymatic emulsion polymerization of styrene

For the reasonable comparison of chemical and enzymatic polymerization, manganese(III) acetate and manganese peroxidase (MnP)‐catalyzed synthesis of polystyrenes were chosen and studied with respect to the yield and the polydispersity of polymer particles. MnP allowed the production of polystyrene in a higher yield and higher polydispersity (82.34% and 2.61) than manganese(III) acetate (77.90% and 1.75). This is believed to be due to a gradual supply of initiator radicals via a catalytic cycle in MnP‐catalyzed polymerization, whereas radicals are generated all at once in Mn(III)‐mediated polymerization. NMR spectroscopy revealed that atactic polystyrene was produced by emulsion polymerization using Mn(III) or MnP. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Residual stresses in press-braked stainless steel sections,II: Press-braking operations

The manufacturing process of cold-formed thin-walled steel members induces cold work which can be characterized by the co-existent residual stresses and equivalent plastic strains and has a significant effect on their structural behaviour and strength. The present paper and the companion paper are concerned with the prediction of residual stresses and co-existent equivalent plastic strains in stainless steel sections formed by the press-braking method. This manufacturing process consists of the following two distinct stages: (i) coiling and uncoiling of the sheets, and (ii) press-braking operations. This paper first presents an analytical solution for the residual stresses and the co-existent equivalent plastic strains that arise from the second stage while a corresponding analytical solution for the first stage is presented in the companion paper. In both solutions, plane strain pure bending is assumed and the effect of material anisotropy is taken into account. On the basis of these two analytical solutions, an analytical model is presented to predict residual stresses and equivalent plastic strains in press-braked stainless sections. The predictions of the analytical model are shown to be in close agreement with results from a finite element-based method, demonstrating the validity and accuracy of the analytical model. The analytical model provides a much simpler method for the accurate prediction of residual stresses and equivalent plastic strains in different parts of a press-braked stainless steel section than a finite element-based method.     

Continuous-Wave Laser Patterning of Three-Dimensional Microstructure in Glasses Containing Silver Nanoparticles

A method is reported that uses visible continuous-wave laser to directly fabricate micropatterns in glasses containing silver (Ag) nanoparticles. Ag nanoparticles were formed in the glass using thermal treatment. Upon laser irradiation, Ag nanoparticles with their surface plasmon in resonance with the laser beam were partially melted and decreased in size due to the temperature increase induced by the excited Ag nanoparticles. Three-dimensional patterns were achieved by scanning the laser beam through the thickness of the glass.     

A Fully Integrated 10-Gb/s Receiver With Adaptive Optical Dispersion Equalizer in 0.13-μm CMOS

A 10 Gb/s receiver, containing an adaptive equalizer, a clock and data recovery, and a de-multiplexer, is implemented in 0.13-mum CMOS. The chip is intended for long-haul optical fiber links where chromatic and polarization mode dispersions are reach-limiting factors. The equalization is performed by a continuous time filter and a two-tap decision feedback equalizer while automatic threshold and phase adjustments are embedded in the CDR. Use of an analog equalizer with digital adaptation garners total power dissipation of 950 mW. Error-free operation over 200 km of single mode fiber is demonstrated. With 140 km of single mode fiber, optical signal to noise ratio penalty is only 2dB. Differential group delay of 100 ps can also be tolerated     

Synthesis and Characterization of Positive‐Charge Functionalized Mesoporous Silica Nanoparticles for Oral Drug Delivery of an Anti‐Inflammatory Drug

We synthesized mesoporous silica nanoparticles (MSN) with different densities of surface positive charges. The positive surface charge was generated by incorporating trimethylammonium (TA) functional groups into the framework of MSN (MSN–TA) via direct co‐condensation of a TA‐silane and tetraethoxysilane (TEOS) in the presence of a base as a catalyst. These MSN–TA samples have well‐defined hexagonal structures with an average particle diameter of 100 nm, pore size of 2.7 nm, and surface area of about 1000 m² g^?1. Anionic drug molecules, Orange II (a fluorescent tracing molecule), and sulfasalazine (an anti‐inflammatory prodrug used for bowel disease), were effectively loaded into these MSN–TA samples and remained inside of the MSN–TA under acidic environment (pH 2–5). The amounts of loading of both Orange II and sulfasalazine were increased with increasing positive charge densities resulting from the increasing number of TA groups. When these drug‐loaded MSN–TA nanoparticles were placed in physiological buffer solution (pH 7.4), a partial negative surface charge on the MSN–TA was generated due to the deprotonation of silanol groups, and the strong electrostatic repulsion triggered a sustained release of the loaded molecules. MSN–TA as a nanovehicle for pH‐dependent loading and controllable release of anionic drug molecules can be used as an oral delivery drug systems targeting at intestine. These drugs can be remained trapped in the nanovehicle when passing through the stomach's acidic environment and be released in intestine where the environmental pH is close to neutral.     

A time-dependent technique for carrier recombination and generation lifetime measurement in SOI MOSFET

A time-dependent technique is developed for carrier recombination–generation (R–G) lifetimes measurement in the silicon-on-insulator (SOI) metal-oxide-semiconductor field-effect transistor (MOSFET). One gate is kept in strong accumulation, and the other gate is kept in strong inversion. A ramp voltage is applied to the accumulated gate, and the drain current transients are monitored for both carrier R–G lifetimes extraction. The time-dependent technique shows an extensive applicability, and its credibility is proved by simulation.     

Gate-level dual-threshold static power optimization methodology (GDSPOM) using path-based static timing analysis (STA) technique for SOC application

This paper describes a novel gate-level dual-threshold static power optimization methodology (GDSPOM), which is based on the static timing analysis (STA) technique for designing high-speed low-power SOC applications using 90 nm multi-threshold complementory metal oxide semiconductor (MTCMOS) technology. The cell libraries come in fixed threshold—high V_th for good standby power and low V_th for high speed. Based on this optimization technique using two cell libraries with different threshold voltages, a 16-bit multiplier using the dual-threshold cells meeting the speed requirement has been designed to have a 50% less leakage power consumption when compared to the one using only the low-threshold cell library.     

Fusing Loop Detector and Probe Vehicle Data to Estimate Travel Time Statistics on Signalized Urban Networks

Abstract: This article presents a methodology that integrates cumulative plots with probe vehicle data for estimation of travel time statistics (average, quartile) on urban networks. The integration reduces relative deviation among the cumulative plots so that the classical analytical procedure of defining the area between the plots as the total travel time can be applied. For quartile estimation, a slicing technique is proposed. The methodology is validated with real data from Lucerne, Switzerland and it is concluded that the travel time estimates from the proposed methodology are statistically equivalent to the observed values.