Properties of reciprocity formulas for the Rogers–Ramanujan continued fractions

The Ramanujan Journal - Ramanujan recorded four reciprocity formulas for the Rogers–Ramanujan continued fractions. Two reciprocity formulas each are also associated with the...     

Metagenome Analysis: a Powerful Tool for Enzyme Bioprospecting

Microorganisms are found throughout every corner of nature, and vast number of microorganisms is difficult to cultivate by classical microbiological techniques. The advent of metagenomics has revolutionized the field of microbial biotechnology. Metagenomics allow the recovery of genetic material directly from environmental niches without any cultivation techniques. Currently, metagenomic tools are widely employed as powerful tools to isolate and identify enzymes with novel biocatalytic activities from the uncultivable component of microbial communities. The employment of next-generation sequencing techniques for metagenomics resulted in the generation of large sequence data sets derived from various environments, such as soil, the human body and ocean water. This review article describes the state-of-the-art techniques and tools in metagenomics and discusses the potential of metagenomic approaches for the bioprospecting of industrial enzymes from various environmental samples. We also describe the unusual novel enzymes discovered via metagenomic approaches and discuss the future prospects for metagenome technologies.     

The role of organoclay on the properties of Polymethylsilsesquioxane: A systematic study

In this study, an attempt is made to improve the properties of PMSQ, an organosilicone polymer which possesses distinguished properties, through an easy and facile route by the inclusion of organically modified montmorillonite clay. PMSQ-clay composites were prepared by solution blending of the components initially and then heat curing under load. The effect of clay content, varied at 5–40 wt.%, on mechanical, thermal and dynamic mechanical properties was evaluated and the optimum was obtained for 20%. Morphology investigation as well as microstructure analysis revealed intercalated to exfoliated morphology of PMSQ-clay composite. An appreciable improvement in mechanical properties of PMSQ, compressive strength and impact strength in particular, was achieved by clay inclusion up to 20%. The properties declined at ≥ 30% clay loading. The composites showed increased thermal stability compared to unmodified PMSQ up to 400 °C. Also, increase in clay content accelerated conversion to ceramic SiOC. PMSQ-clay composites exhibited good visco-elastic characteristics with higher T_g probably due to enhanced polymer-clay interactions. Thus, a simple and viable method to enhance the mechanical and thermal characteristics of PMSQ by way of preparing its composite with the reinforcing filler organoclay is demonstrated here.     

Prevalence of eNOS Glu298Asp polymorphism in healthy volunteers from a region of Northern India

OBJECTIVE: Endothelial nitric oxide synthase (eNOS) Glu298Asp polymorphisms are under extensive study worldwide due to their suggested role in cardiovascular disorders. This polymorphism had gained more attention since several reports suggest its association with hypertension and coronary artery disease (CAD). Asian Indians are highly susceptible to ischemic heart dis eases. We determined the prevalence of eNOS Glu298 Asp polymorphism in 139 healthy volunteers from Delhi and the surrounding areas. The subjects were recruited from those who willingly participated in this study in response to a publicized call and a standard questionnaire. Male to female ratio was 2.7:1 due to the larger number of male participants in this investigation. This, however, does not represent normal male to female distribution in the area. Despite the male bias, this investigation was justified. The prevalence of CAD in males is about 3 times higher in this region and no data had so far been available on the distribution of this polymorphism from India. METHOD: The eNOS Glu298Asp polymorphism was studied by PCR-RFLP. RESULTS: Distribution of genotype GG, GT and TT in the study subjects was found to be 71.22, 28.06 and 0.72%, respectively, and allele frequency was G,0.853;T,0.147. CONCLUSION: T allele had been described as susceptibility allele for CAD in several population studies. The frequency of the T allele was found to be two times higher in our subjects than that reported for Japanese and Korean populations. This study does not provide any direct evidence for eNOS gene disease associations but is the first report on the prevalence of eNOS Glu298Asp gene polymorphism in Indian subjects. Whether the observed pattern of eNOS Glu298Asp polymorphism contributes to the greater susceptibility of Asian Indians to CAD as compared to the other population groups, needs to be investigated.     

High pressure studies of sodium and silver halides

Abstract

We have investigated the structural phase transitions in sodium and silver halides theoretically under high compressions by means of first-principles self-consistent total-energy calculations within the local-density approximation using the full-potential linear-muffin-tin-orbital (FPLMTO) method. Our results confirm the recent high pressure experimental observations of crystallographic phase transformations in sodium halides (Leger et al. (1998) J. Phys.: Condens. Matter, 10, 4201) and silver halides (Hull and Keen (1999) Phys. Rev., B59, 750. The calculated transition pressures agree with the experimental data.     

Mild and efficient esterification of alkylphosphonic acids using polymer-bound triphenylphosphine

Mild and efficient esterification of alkylphosphonic acids using primary alcohols, iodine, imidazole and polymer-bound triphenylphosphine is developed.     

Effect of distributed particle magnetic moments on the magnetization of NiO nanoparticles

Magnetization of NiO nanoparticles, at different temperatures, is measured and analyzed taking into account a distribution in particle magnetic moment. We find that disregarding this distribution in the analysis is the reason for the many anomalous observations reported on this system in the literature.     

Formic Acid as a Potential Pretreatment Agent for the Conversion of Sugarcane Bagasse to Bioethanol

In recent years, growing attention has been focused on the use of lignocellulosic biomass as a feedstock for the production of ethanol, a possible renewable alternative to fossil fuels. Several pretreatment processes have been developed for decreasing the biomass recalcitrance, but only a few of them seem to be promising. In this study, effect of various organic solvents and organic acids on the pretreatment of sugarcane bagasse was studied. Among the different organic acids and organic solvents tested, formic acid was found to be effective. Optimization of process parameters for formic acid pretreatment was carried out. The structural changes before and after pretreatment was investigated by scanning electron microscopy, X-ray diffraction (XRD), and Fourier transform infrared (FTIR) analysis. The X-ray diffraction profile showed that the degree of crystallinity was more for pretreated biomass than that of untreated. The FTIR spectra shown at the stretching of hydrogen bonds of pretreated sugarcane bagasse arose at higher number. It also revealed that the cellulose content in the solid residue increased because the hemicelluloses fraction in raw materials was released by acid hydrolytic reaction.     

Synthesis of Polylactide under Inert Atmosphere and Vacuum

The ring-opening polymerization (ROP) of L- lactide was carried out in bulk using various initiators along with triphenylphosphine (PPh₃) as co-initiator. Equimolar addition of triphenylphosphine increased the molecular masses of polylactide (PLA). The polymerization was carried out at 403.15 K up to 155 hr. Different experiments were carried out over a wide range of monomer to initiator (M_o/I_o) ratios. It was found that maximum molecular weight of polylactide was observed when M_o/I_o ratio was 2500–2700. Polymerization reactions were carried out under two different environments in the reaction vessel, an inert cover and a partial vacuum. The average molecular weight of polylactide was determined by using size exclusion chromatography. The increase of polymerization time increased the weight average molecular weight but after prolonged reaction time, the molecular weight decreased gradually.