Weights of elementary representations in SU(5)-SO(10)-E6 chain

For Dynkin labels of weights in 5 and 10 of SU(5), 10 and 16 of SO(10) and 27 ofE, we find it instructive to (a) explōit the Cartan decom position into a nonsemi simple symmetric subalgebra and coset space, (b) introduce a set of annihilation and creation operators, that may act on an invariant 10>, to represent suitably the shift-action and weight-vectors.     

High temperature superconductivity in Bi-Sr-Ca-Cu-O oxide system

Stable, reproducible high temperature superconductivity with onset temperatures of 90 K and above is confirmed in the oxide system with nominal metal ion composition BiSrCaCu₂O _x . The onset is nearly the same, but zero-resistance temperatures depend on the heat treatment. Sample quenched from 850 C in air (close to melting) to liquid nitrogen temperature is non-superconducting. BiSr_0.5Ca_1.5Cu₂O _x is also found to be superconducting in which a two-step drop in resistance is observed, one starting around 118 K and the other around 80 K.     

Study of crystal texture in pvc gels by x-ray diffraction and infrared dichroism

An enquiry is presented into the nature and origin of thermoreversible gelation of poly(vinyl chloride) (PVC). In line with a previous paper it is demonstrated by direct x-ray diffraction evidence that the origin of the gelation is crystallization, and that this crystallinity can be conspicuously apparent even for the usual technological polymer. In addition some unusual diffraction effects become apparent such as do not obviously follow from existing notions of the PVC structure. Combined infrared dichroism and x-ray studies revealed that these new effects are attributable to a two-component nature of the crystallinity where the components are distinguished by their orientation behavior, lateral extension, and possibly morphology of the crystallites. Some of the crystals orient with their a axes (type A crystals) and some with their c axes (type B crystals) along the stretch direction. Other more complex orientability differences are also manifest during film formation. Crystals B are smaller, and are believed to correspond to the network forming junctions, hence to fringed micellar crystals. Crystals A have a less evident connection with the network and are hypothesized to be of lamellar character, the behavior of which is closely simulated by lamellar crystal additives (stabilizer crystals). High-temperature x-ray work revealed no melting of crystals even in the temperature range where endotherms appear in the thermograms.     

Cellulases: Classification,Methods of Determination and Industrial Applications

Microbial cellulases have been receiving worldwide attention, as they have enormous potential to process the most abundant cellulosic biomass on this planet and transform it into sustainable biofuels and other value added products. The synergistic action of endoglucanases, exoglucanases, and β-glucosidases is required for the depolymerization of cellulose to fermentable sugars for transformation in to useful products using suitable microorganisms. The lack of a better understanding of the mechanisms of individual cellulases and their synergistic actions is the major hurdles yet to be overcome for large-scale commercial applications of cellulases. We have reviewed various microbial cellulases with a focus on their classification with mechanistic aspects of cellulase hydrolytic action, insights into novel approaches for determining cellulase activity, and potential industrial applications of cellulases.     

Removal of unsaturated aliphatic carboxylic acid from aqueous effluent using quaternary amine

Maleic acid, present in the effluent from organic intermediate producing industries, is an industrially important raw material. Its use in manufacture of alkyd and polyester resins, surface coatings, lubricant additives, plasticizers, co-polymers and agricultural chemicals, makes it necessary to explore for best possible techniques to recover it from aqueous solutions. The present work investigates the recovery of maleic acid from aqueous solution at ambient temperature. N–Methyl–n, n–dioctyloctan–1–ammonium chloride, (commercially known as Aliquat 336) is used as an extractant with three different diluents, belonging to different chemical classes: an aromatic hydrocarbon, a ketone, and an acetate. The chemical extraction results are reported in the terms of distribution coefficient, degree of extraction, and loading ratios. The results were modeled by mass action equilibria model as well as differential evolution technique. Differential evolution algorithm has been prepared. The model and experimental observations were compared and fairly good agreement was observed.     

Isolation of sporopollenin-like biopolymer from <Emphasis Type="Italic">Aspergillus niger</Emphasis> and its characterisation

The study sought to isolate asporopollenin-like biopolymer from Aspergillus niger (A. niger) spore. The spore exine (Sp-exine) from A. niger was isolated using four different methods. The highest isolation efficiency (9.32 %) was found for the method based on H₂SO₄ treatment. Optical microscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images showed that the isolated Sp-exine had a spherical shape with a spun morphology and was highly uniform in size. The elemental compositions of the bodies of the Sp-exine materials, as well as their surfaces, were observed by means of CHN combustion analysis and SEM with energy-dispersive X-ray spectroscopy (SEM-EDX), respectively. The result demonstrates C, H and O to be the main structural elements in all the Sp-exine samples. Fourier-transform infrared (FTIR) spectroscopy coupled with solid state ¹³C nuclear magnetic resonance (solid state ¹³C NMR) spectroscopy and UV-Vis spectroscopy were used to compare the changes in the functional groups of the Sp-exine samples isolated using the different methods. A thermogravimetric analysis (TGA) study demonstrated all the Sp-exine samples showed high thermal stability. Among all tested methods, the treatment with H₂SO₄ and alcoholic potassium hydroxide exhibited the best results in removing cellular and other contents with minimal drastic effect on the structure and morphology and is proposed as the best method for isolating Sp-exine since it required minimal isolation time and showed good isolation efficiency.