Poly(ε-L-lysine): Synthesis and conformation

The synthesis of poly(ε-L -lysine) is described. This is a poly(ε-amino acid) in which the ε-amino group of lysine is condensed with the α-carboxyl group to produce a chain backbone that is a variant of the usual one seen in proteins and the side chain is the α-amino group. Conformational studies of poly(ε-L -lysine) and its t-butyloxycarbonyl derivative suggest the likelihood of a chain order that is formally similar to the antiparallel pleated-sheet conformation of proteins.     

Quorum sensing inhibition as a promising method to control biofilm growth in metalworking fluids

Journal of Industrial Microbiology & Biotechnology - Microbial contamination in metalworking systems is a critical problem. This study determined the microbial communities in metalworking...     

Origins of life: conformational energy calculations on primitive tRNA nestling an amino acid

We report conformational energy calculations on our proposal of a molecular interaction theory for the origin of the nucleic acid-directed, adaptor-mediated synthesis of proteins that links the phenomena of chemical and biological evolution. A particular conformation of a pentanucleotide turns out to be a double-sided template for a primitive decoding system. It is able to neatly nestle an amino acid via hydrogen bonds, and this complex is found to be an energetically favourable conformation. The total potential energy of the complex is calculated using semi-empirical potential energy functions. A local-minimum conformation is obtained and its features are reported. The template conformation of the pentanucleotide is found to have an energy value far lower than a regular helical conformation. When the amino acid is nestled in the cleft of the template-conformation through specific hydrogen bonds, the energy is further lowered. A D-amino acid nestled into the PIT (Primitive tRNA) is found to be less stable than its L counterpart, as revealed by energy calculations.     

Montmorillonite K-10 clay-catalyzed Ferrier rearrangement of 2-C-hydroxymethyl-d-glycals, 3,4,6-tri-O-alkyl-d-glycals, and 3,4-(dihydro-2H-pyran-5-yl)methanol: a few unexpected domino transformations

Montmorillonite K-10 clay-catalyzed substitution reactions of 3,4,6-tri-O-alkyl-2-C-hydroxymethyl-d-glycals, 3,4,6-tri-O-acetyl-d-glycals, 3,4,6-tri-O-alkyl-d-glycals, and 3,4-(dihydro-2H-pyran-5-yl)methanol with a few alcohols and phenols are described. The reactions of 2-C-hydroxymethyl-d-glycals with phenols were similar to those of 2-C-acetoxymethyl-d-glycals and afforded pyrano[2,3-b]benzopyrans. This montmorillonite K-10 clay-catalyzed transformation is facile both under ambient (Method 1) and microwave conditions (Method 2). Ferrier rearrangement of 3,4-(dihydro-2H-pyran-5-yl)methanol with p-cresol, 2,6-xylenol, and ethanol led to totally unexpected transformations. Reaction of 2-C-hydroxymethyl-d-galactal with 2,6-dimethylphenol in the presence of montmorillonite K-10 led to a novel domino transformation affording 4-(5′,6′-dihydro-4H-pyran-3′-ylmethyl)-2,6-dimethylphenol. In contrast, 3,4,6-tri-O-acetyl-d-glucal furnished the Ferrier rearrangement product, 2,6-dimethylphenyl 4,6-di-O-acetyl-2,3-dideoxy-α-d-erythro-hex-2-enopyranoside. Also, isomerization of 3,4,6-tri-O-alkyl-d-glycals to products of allylic rearrangement, 2,3-unsaturated-O-glycosides in good yields is reported.     

The identity and distribution of striped bagrid catfish,Mystus tengara (Hamilton 1822) revealed through integrative taxonomy

Molecular Biology Reports - The taxonomic status and geographical distribution of M. tengara are vague. No genetic diversity and phylogenetic study have been done till now to resolve its identity...     

Luminescence characteristics and X-ray-induced defects in BaFBr:Eu2+ storage phosphor

Three different approaches used to synthesize a sensitive BaFBr:Eu²⁺ X-ray storage photostimulated luminescence (PSL) phosphor at 850°C for 1 h in a reducing atmosphere are reported. The effects of F/Br and Eu concentration on photoluminescence (PL) and PSL sensitivities synthesized by the three approaches were compared. In the first recipe, BaFBr:Eu²⁺ prepared using a BaF₂, BaBr₂ and EuF₃ mixture using solid-state diffusion (Recipe I), even in a reducing atmosphere, yielded a low PL and PSL intensity due to oxygen contamination that acted as competing hole traps. When BaFBr:Eu²⁺ was prepared using ammonium bromide and ammonium fluoride by two different recipes (Recipes II and III), oxygen contamination was eliminated, resulting in enhanced PSL efficiency. The proposed PSL process in BaFBr:Eu²⁺ was consistent with the experimental results. Increased F/Br molar ratios would incorporate fluorine ion interstitials that act as hole traps accompanied by bromine ion vacancies that act as electron traps. Although two types of F centres, F(Br⁻) and F(F⁻) are possible, F(Br⁻) centres formed during X-irradiation are only vital for the PSL process. Structural, morphology, and thermoluminescence (TL) properties of the samples were also examined using XRD, field emission scanning electron microscope (FESEM), energy-dispersive X-ray spectroscopy (EDAX), and TL studies.