Modelling of Supercapacitors: Factors Influencing Performance

The utilizable capacitance of Electrochemical Double Layer Capacitors (EDLCs) is a function of the frequency at which they are operated and this is strongly dependent on the construction and physical parameters of the device. We simulate the dynamic behavior of an EDLC using a spatially resolved model based on the porous electrode theory. The model of Verbrugge and Liu (J. Electrochem. Soc. 152, D79 (2005)) was extended with a dimension describing the transport into the carbon particle pores. Our results show a large influence of the electrode thickness (Le), separator thickness (Ls) and electrolyte conductivity (κ) on the performance of EDLCs. In agreement with experimental data, the time constant was an increasing function of Le and Ls and a decreasing function of κ. The main limitation was found to be on the scale of the whole cell, while transport into the particles became a limiting factor only if the particle size was unrealistically large. The results were generalized into a simplified relation allowing for a quick evaluation of performance for the design of new devices. This work provides an insight into the performance limitation of EDLCs and identifies the critical parameters to consider for both systems engineers and material scientists

Analyses of zonal atmospheric excitation functions and their correlation with polar motion excitation functions

International audienceThe atmospheric influence on the Earth's, rotation can be described by the effective atmospheric angular momentum (EAAM) functions. In this study we focus on the analysis of short period variations of the equatorial components of the zonal EAAM excitation functions ?1 and ?2 and their influence on similar variations of polar motion. The global objective analysis data of the Japanese Meteorological Agency for the period 1986?1992 were used to compute the EAAM excitation functions in different latitude belts. Time- and latitude-variable amplitude spectra of variations of these functions with periods shorter than 150 days, containing pressure, pressure with the inverted barometric correction, and wind terms were computed. The spectra show distinct latitude and time variations of the prograde and retrograde oscillations which reach their maxima mainly in mid-latitudes. Prograde and retrograde oscillations with periods of about 40?60 days and about 110?120 days are seen in the spectra of pressure terms of the equatorial components of the zonal EAAM excitation functions. Additionally, correlation coefficients and cross-spectra between variations of the geodetic polar motion and equatorial components of the zonal EAAM excitation functions were computed to identify the latitude belts of the globe over which atmospheric circulation changes are correlated mostly with short period variations of the polar motion excitation functions. The correlation coefficients vary in time and latitude and reach maximum values in the northern latitudes from 50°N to 60°N. In the cross-spectra between the polar motion excitation functions and pressure terms of the zonal EAAM excitation functions there are peaks of common prograde oscillations with the periods around 20, 30, 40?50, 60 and 80?150 days and of common retrograde oscillations around 20, 30, 40 and 50?70 days

Closed-Loop Multitarget Optimization for Discovery of New Emulsion Polymerization Recipes

Self-optimization of chemical reactions enables faster optimization of reaction conditions or discovery of molecules with required target properties. The technology of self-optimization has been expanded to discovery of new process recipes for manufacture of complex functional products. A new machine-learning algorithm, specifically designed for multiobjective target optimization with an explicit aim to minimize the number of “expensive” experiments, guides the discovery process. This “black-box” approach assumes no a priori knowledge of chemical system and hence particularly suited to rapid development of processes to manufacture specialist low-volume, high-value products. The approach was demonstrated in discovery of process recipes for a semibatch emulsion copolymerization, targeting a specific particle size and full conversion.The research leading to these results has received funding from the European Research Council under the European Union’s Seventh Framework Programme (EC FP7) Grant Agreement no. [NMP2-SL-2012-280827] and EPSRC project “Closed Loop Optimization for Sustainable Chemical Manufacture” [EP/L003309/1]

Rhinosporidium seeberi: a human pathogen from a novel group of aquatic protistan parasites.

Rhinosporidium seeberi, a microorganism that can infect the mucosal surfaces of humans and animals, has been classified as a fungus on the basis of morphologic and histochemical characteristics. Using consensus polymerase chain reaction (PCR), we amplified a portion of the R. seeberi 18S rRNA gene directly from infected tissue. Analysis of the aligned sequence and inference of phylogenetic relationships showed that R. seeberi is a protist from a novel clade of parasites that infect fish and amphibians. Fluorescence in situ hybridization and R. seeberi- specific PCR showed that this unique 18S rRNA sequence is also present in other tissues infected with R. seeberi. Our data support the R. seeberi phylogeny recently suggested by another group. R. seeberi is not a classic fungus, but rather the first known human pathogen from the DRIPs clade, a novel clade of aquatic protistan parasites (Ichthyosporea)

Shigellosis: An Old Disease in New Clothes?

Sansonetti discusses a "landmark" study of the epidemiology of shigellosis, involving over 600,000 people of all ages in six Asian countries

Comparative Nephrotoxicity of Cisplatin and Nedaplatin: Mechanisms and Histopathological Characteristics

The antineoplastic platinum complexes cisplatin and its analogues are widely used in the chemotherapy of a variety of human malignancies, and are especially active against several types of cancers. Nedaplatin is a second-generation platinum complex with reduced nephrotoxicity. However, their use commonly causes nephrotoxicity due to a lack of tumor tissue selectivity. Several recent studies have provided significant insights into the molecular and histopathological events associated with nedaplatin nephrotoxicity. In this review, we summarize findings concerning the renal histopathology and molecular pathogenesis induced by antineoplastic platinum complexes, with a particular focus on the comparative nephrotoxicity of cisplatin and nedaplatin in rats

Electrical properties of a-antimony selenide

This paper reports conduction mechanism in a-\sbse over a wide range of temperature (238K to 338K) and frequency (5Hz to 100kHz). The d.c. conductivity measured as a function of temperature shows semiconducting behaviour with activation energy $\Delta$E= 0.42 eV. Thermally induced changes in the electrical and dielectric properties of a-\sbse have been examined. The a.c. conductivity in the material has been explained using modified CBH model. The band conduction and single polaron hopping is dominant above room temperature. However, in the lower temperature range the bipolaron hopping dominates.Comment: 9 pages (RevTeX, LaTeX2e), 9 psfigures, also at http://pu.chd.nic.in/ftp/pub/san16 e-mail: gautam%[email protected]