Electrochemical polymerization of chiral pyrrole derivatives in electrolytes containing chiral camphor sulfonic acid

N‐Substituted pyrrole derivatives with chiral side groups have been synthesized and electrochemically polymerized in acetonitrile containing tetrabutylammonium perchlorate (TBAClO₄) and (S)‐(+)‐camphor‐10‐sulfonic acid ((S)‐(+)‐CSA) or (R)‐(?)‐camphor‐10‐sulfonic acid ((R)‐(?)‐CSA). The resulting N‐substituted polypyrrole films were characterized by cyclic voltammetry, infrared, Raman and X‐ray photoelectron (XPS) spectroscopies. XPS results demonstrated that the as‐grown polymer films are preferably doped by CSA anions when the monomer and the CSA anion have the same optical rotation dispersion (ORD). Furthermore, the conductivities of the polymers synthesized in the media containing CSA with the same ORD of the corresponding monomers were measured to be about 2–10 times higher than those of polymers obtained from electrolytes without CSA. Copyright © 2004 Society of Chemical Industry     

A novel dynamic survivable routing in WDM optical networks with/without sparse wavelength conversion

In this paper, we study the dynamic survivable routing problem, both in optical networks without wavelength conversion and in optical networks with sparse wavelength conversion, and propose a novel hybrid algorithm for it based on the combination of mobile agents technique and genetic algorithms (GA). By keeping a suitable number of mobile agents in the network to cooperatively explore the network states and continuously report cycles (that are formed by two disjoint-link routes) into the routing tables, our new hybrid algorithm can promptly determine the first population of cycles for a new request based on the routing table of its source node, without the time consuming process associated with current GA-based lightpath protection schemes. We further improve the performance of our algorithm by introducing a more advanced fitness function that is suitable for both the above networks. Extensive simulation studies on the ns-2 network simulator show that our hybrid algorithm achieves a significantly lower blocking probability than the conventional survivable routing algorithms for all the cases we studied.     

The stability of children's physical activity as measured by accelerometry and self-report

The Computer Science Application (CSA) accelerometer uses integrated circuitry and memory to provide a continuous recording of minute-by-minute movement counts. It has been previously validated as an objective monitor of children's physical activity in field and laboratory settings. Our purpose was to derive accelerometry summary variables reflective of different physical activity intensity levels, evaluate the stability of these summary variables, and define the number of days needed to adequately measure usual physical activity. A secondary study purpose was to compare three self-report questionnaires to accelerometry. Thirty children (7-15 yr) wore accelerometers for 12 h.d-1 for 6 d. Daily summary variables of average movement count (total physical activity) and daily frequency of sedentary through vigorous activity were constructed. Intraclass correlation coefficients (R) and 95% confidence intervals (CI) were used to analyze the data. Accelerometry stability using 1 monitored day to represent usual physical activity was R = 0.42-0.47. When 6 d were used, stability increased to R = 0.81-0.84. Acceptable intraclass correlations and CI were achieved with 4 d of monitoring (R = 0.75-0.78, CI = 0.60-0.88). The self-report questionnaires were poorly to moderately correlated to accelerometry variables (r = -0.03-0.51). Data indicate that in field settings: 1) accelerometry can be used to assess the intensity of children's activity and 2) 4 or more days of activity monitoring are needed to achieve satisfactory reliability.     

Magnetic Nanocrystals Aligned on Mesoscopic Scale: Collective Properties and Their Use

Magnetic nanocrystals organized in chain-like structures behave as nanowires with a shape anisotropy induced by the structuration of the sample. This is valid for various types of magnetic nanomaterials. Furthermore, the coating of nanocrystals plays a major role in the mesoscopic structure of the film. γ-Fe₂O₃ nanocrystals are used as a mask to reproduce the mesoscopic structure on a silicon wafer.     

Simple approaches towards the design of an attached-growth sponge bioreactor (AGSB) for wastewater treatment and reuse.

Wastewater treatment and reuse is being emphasized due to the shortage of water sources and the continuous deterioration of the aquatic environment. In this study, a novel sponge bioreactor was studied as a low cost, high efficiency alternative for an attached growth biological system. This was designed by combining of number of sponge trays. This emerging technology has many beneficial properties in wastewater treatment and reuse. The approaches towards the conditions for system design were: (i) selection of sponge types; (ii) selection of sponge shapes; and (iii) selection of designated slope of sponge tray. They were determined through a series of experiments using a laboratory-scale unit with synthetic wastewater. It was then tested with a pilot-scale unit at the predetermined optimum conditions. The results indicate that the highest biomass growth was found at the sponge type with a cell count of 70-90 cells/in(2) (6.45 cm(2)) The relationship between biomass growth and biological oxygen consumption was well established. The prism-shaped sponge (triangular polyurethane sponge of 70-90 cells/in(2) with designated slope of sponge tray at 10 degrees) led to the best performance in terms of both organic and nutrient removal efficiency.     

Low Frequency Pulsed Resonant Converter for Energy Harvesting

A pulsed-resonant ac-dc converter and an integrated circuit (IC) controller have been designed, fabricated, and tested for harvesting energy from low-voltage (1.2V), low-power (1-100muW) energy transducers with output frequency in the 10-Hz-1-kHz range. Simulations using foundry models suggest that the silicon loss could be as low as 0.6muW, and the efficiency could reach 70%. With the IC experimentally packaged, the measured efficiency is between 50% and 70%, depending on the size and the loss in the resonant inductor     

Analysis of linearly tapered fiber Bragg grating for dispersion slope compensation

We demonstrate that linearly tapered fiber Bragg gratings (FBGs) display nonlinear group delay under strain or stress. The nonlinear group delay of the tapered FBG is analyzed theoretically. Experimental results show a good agreement with the analysis. We are the first to find that linearly tapered FBGs can be used in dispersion slope compensation.     

Improved method to extract the short-circuit parameters of the BECM

The current method for extracting the short-circuit broadband extended cantilever model (BECM) parameters requires measurement of short-circuit currents, and is problematic over a wide frequency range, prohibiting each short-circuit parameter to be directly measured. The improved method presented herein eliminates the measurements of short-circuit currents. Each short-circuit BECM parameter is directly found from two measurements, an open-circuit voltage gain and a short-circuit admittance. The method is demonstrated for a published five-winding BECM.     

品牌换标启示录

近几年国内外许多大品牌纷纷更换自己的标志，从柯达、富士到英特尔，从中国联通到腾讯网，从联想到创维，再到华为等，那么导致品牌换标的原因是什么？标志的再设计在其中起到一个怎样的作用？     

Biofilter in water and wastewater treatment

Biofilter is one of the most important separation processes that can be employed to remove organic pollutants from air, water, and wastewater. Even though, it has been used over a century, it is still difficult to explain theoretically all the biological processes occurring in a biofilter. In this paper, the fundamental of biological processes involved in the biofilter is critically reviewed together with the mathematical modeling approach. The important operating and design parameters are discussed in detail with the typical values used for different applications. The most important parameter which governs this process is the biomass attached to the medium. The relative merits of different methods adopted in the measurement of the biomass are discussed. The laboratory-and full-scale applications of the biofilter in water and wastewater treatment are also presented. Their performances in terms of specific pollutant removal are highlighted.