Synthesis of both enantiomers of ethyl-4-chloro-3-hydroxbutanoate from a prochiral ketone using Candida parapsilosis ATCC 7330

Candida parapsilosis ATCC 7330 when grown in a medium containing glycerol reduced ethyl-4-chloro-3-oxobutanoate to (R)-ethyl-4-chloro-3-hydroxybutanote (ee >99%, yield: 94%) while glucose and sucrose grown cells yielded (S)-ethyl-4-chloro-3-hydroxybutanote (ee >99%, yield: 96%). The activity of ethyl-4-chloro-3-oxobutanoate reductase was higher in glucose-grown cells (160 U/g protein) when compared to sucrose (158 U/g protein) and glycerol (22 U/g protein). Both the enantiomers of ethyl-4-chloro-3-hydroxybutanoate (ee >99%) can thus be obtained using Candida parapsilosis ATCC 7330 by altering the carbon source in the growth medium.     

Investigation on phenylpropanoids rich Melaleuca decora (Salisb.) Britt. essential oil

The essential oil of Melaleuca decora twigs has been obtained by hydrodistillation and analysed by GC-FID, GC/MS and (1)H-, (13)C-NMR experiments. The most abundant class of compounds in M. decora twig oil was phenylpropanoids represented by methyl eugenol (92.4%) as the most exclusive constituent. In terms of molecular diversity, phenylpropanoids dominate M. decora essential oil with low terpenoid (3.9%) proportion.     

Fluorescent signal amplification of carbocyanine dyes using engineered viral nanoparticles

We report enhancement in the fluorescent signal of the carbocyanine dye Cy5 by using an engineered virus as a scaffold to attach >40 Cy5 reporter molecules at fixed locations on the viral capsid. Although cyanine dye loading is often accompanied by fluorescence quenching, our results demonstrate that organized spatial distribution of Cy5 reporter molecules on the capsid obviates this commonly encountered problem. In addition, we observe energy transfer from the virus to adducted dye molecules, resulting in a highly fluorescent viral nanoparticle. We have used this enhanced fluorescence for the detection of DNA-DNA hybridization. When compared with the most often used detection methods in a microarray-based genotyping assay for Vibrio cholerae O139, these viral nanoparticles markedly increased assay sensitivity, thus demonstrating their applicability for existing DNA microarray protocols.     

Complicity of degradable polymers in health-care applications

Polymeric biomaterials have revolutionized biomedical technology and related fields as biomaterials for health-care applications. Recent trend in polymeric medical technology has adapted a tendency to substitute degradable polymers instead of non-degradable synthetic polymers for the advancement of various health-care modalities. They have got considerable attention for their potential in various interdisciplinary arenas, which implies tissue engineering scaffolds, sustainable drug release, delivery agents, regenerative medicine, and development of life-saving devices, implants, dental products as well as in food technology. Various types of degradable polymers are been developed to date having stringent features applicable for various aspects in modern science. Thus, being the most renovative field of biomedicine and biomedical technology degradable polymers has gained substantial acceptance and appreciation recent times. This review critically underlines various degradative polymers and their subtypes, potential applications, types of degradation, and their possible effects in the biological system. Assessment of possible toxicological risks behind is an important criterion to be focused before validating any biomaterial safe for biomedical applications. Therefore various toxicological assessment strategies and their impact in biomedicine and technology were also included. In addition, the risk versus benefit assessment is also critically summarized.     

Modification in structure of La and Nd co‐doped epitaxial BiFeO3 thin films probed by micro Raman spectroscopy

The influence of La and Nd co‐substitution on structure, electric and magnetic properties of epitaxial thin films of BiFeO₃ (BFO) was examined. We demonstrate structural phase transition in co‐doped La and Nd BFO thin films using Raman spectroscopy. Based on group theoretical analysis of the number and symmetry of Raman lines, we provide strong experimental evidence that the structure has been changed from rhombohedral to monoclinic due to co‐doping in BFO. The change in structure was also reflected in morphology of these films. Room temperature magnetic hysteresis curves showed that doped films exhibit enhanced ferromagnetic properties with remnant magnetization of ~10 emu/cm³ and coercive field of 1.2 kOe. The enhanced magnetic properties highlight the potential applications of doped BLNFO thin film for smart devices. Copyright © 2015 John Wiley & Sons, Ltd.     

Ab initio study of gas phase and water-assisted tautomerization of maleimide and formamide

Maleimide serves as an important starting material in the synthesis of drugs and enzyme inhibitors. In the present paper, knowing the importance of tautomerization in maleimide for its drug action, potential energy surface of maleimide is studied and its tautomerization has been discussed and compared with tautomerization of formamide. Gas phase tautomerization of maleimide requires large amount of energy (23·21 kcal/mol) in comparison to formamide (15·05 kcal/mol) at HF/6-31+G* level. Thus making the proton transfer reaction a difficult process in gas phase. Water molecule lowers the energy barrier of tautomerization thus facilitating the tautomerization of maleimide to 5-hydroxy-pyrrol-2-one. Water assisted tautomerization of maleimide requires 19·60 kcal/mol energy at HF/6-31+G* and 17·63 kcal/mol energy at B3LYP/6-31+G* level, a decrease of 3·61 and 5·96 kcal/mol over gas phase tautomerization. Whereas, tautomerization of formamide requires 14·16 and 12·84 kcal/mol energy, a decrease of 0·89 and 2·01 kcal/mol energy over gas phase tautomerization at HF/6-31+G* and B3LYP/6-31+G* level, respectively. Water-assisted tautomerization in maleimide and formamide showed that difference in energy barrier reduces to 2·83 kcal/mol from 10·41 kcal/mol (in gas phase) at B3LYP level, which resulted that maleimide readily undergoes tautomerization in water molecule.     

Determination of Fatty Acid Based Lubricity Improver in Diesel by GC

GC/FID has been used for the determination of a fatty acid based lubricity improver in diesel fuel. The method makes use of phase transfer catalysis for the enrichment of the lubricity improver from the diesel matrix. The use of phase transfer catalysis for the simultaneous extraction, preconcentration and derivatisation of the fatty acids enables determination of concentrations of 20 mg L^?1. The method has been successfully applied to the analysis of diesel streams from various sources. The effect of the diesel matrix has also been investigated and it does not affect the recovery of the additive.     

液晶光学双稳态装置

介绍用液晶作为非线性元件构建的光学双稳态装置，该装置结构简单，使用可靠，实验内容丰富，适合教学要求。     

Variation in the volatile constituents of Artemisia annua var. CIM-Arogya during plant ontogeny

The essential oils yield and composition of the aerial parts of A. annua var. CIM-Arogya grown in Uttarakhand, India were analyzed and compared by capillary GC and GC-MS at different stages of development. The analysis led to the identification of 81 constituents forming 91.0%-97.1% of the essential oils compositions. The essential oil content of the aerial parts was found to vary from 0.3% to 0.7% at different stages of growth. A. annua crop harvested at full flowering and seed setting stage gave higher yield of essential oil (0.6%, 0.7%) than that harvested at pre flowering (0.5%), late vegetative (0.4%, 0.5%), mid vegetative (0.4%, 0.4%) and early vegetative stages (0.3%, 0.3%). The essential oils at different stages of growth showed monoterpenoids (38.5%-72.0%) and sesquiterpenoids (22.2%-48.2%) as major grouped constituents. The major constituents identified were camphor (22.8%-42.6%), 1,8-cineole (3.7%-8.4%), linalool (<0.1%-11.9%), beta-caryophyllene (2.0%-9.2%), (E)-beta-farnesene (1.3%-8.5%), germacrene D (0.5%-7.3%) and 1-epi-cubenol (0.7%-5.2%) in essential oil samples collected at different crop stages.     

Isothermal and Non-Isothermal Crystallization Kinetics and Morphology of Poly(trimethylene terephthalate)/Multiwalled Carbon Nanotube Composites

Summary: Multiwalled carbon nanotubes (MWCNTs) synthesized using chemical vapor deposition method were dispersed in poly(trimethylene terephthalate) (PTT, Mv = 88,000) by melt compounding technique using DMS microcompounder. The nanocomposites consisting of varying amounts of MWCNTs were characterized by differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), Raman spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The effect of carbon nanotubes on the crystallization behavior (under isothermal and non isothermal crystallization conditions) of PTT was studied using DSC. The presence of carbon nanotubes didn't show any significant effect on crystallization temperature of PTT matrix under non-isothermal conditions. Crystallization studies under isothermal conditions were carried out at different temperatures i.e 185, 190, 195 and 200 °C. Complete crystallization was observed within 60 sec at 185 °C whereas at 200 °C, longer time was required for complete crystallization. Crystal growth was also investigated using hot stage polarizing microscope (PLM). The effect of annealing time at 200 °C was investigated in the presence as well as in the absence of varying amounts of MWCNTs. Spherulitic growth was seen and the spherulite size in all the samples increased with annealing time. Morphological characterization using SEM and TEM showed a uniform dispersion of MWCNTs and poor compatibility with PTT matrix.