Hydrolytic reactions of esters and amides of thiosulphurous acid in a homogeneous medium

The hydrolytic reactions of esters and amides of thiosulphurous acid are investigated in a homogeneous medium. The esters are hydrolysed by alkali to give sulphide, sulphite and thiosulphate whereas the amides are resistant towards alkali. Both the esters and amides are hydrolysed by acids giving hydrogen sulphide, sulphur dioxide, polythionates and elemental sulphur. The hydrolysis of these esters and amides in presence of sulphurous acid and thiosulphuric acid gives tetrathionate and hexathionate, respectively.     

Scaling dynamical correlation energy from density functional theory correlation functionals

The scaling of dynamical correlation energy in molecules obtained by the correlation functionals of density functional theory (DFT) is examined. The approach taken is very similar to the scaled external correlation method of Brown and Truhlar but is based on the observation that DFT correlation functionals, especially the LYP, appear to represent the dynamical portion of the correlation energy in molecules. We examine whether higher accuracy in atomization energies can be gained by scaling without significant deterioration of the structural and spectroscopic properties of the molecules using four DFT functionals (BLYP, OLYP, B3LYP, and O3LYP) on 19 molecules including the six molecule AE6 database, the latter being representative of a much larger, 109 molecule training set. We show that, with molecule specific scale factors, nearly perfect agreement with experiment can be achieved in atomization energies without increasing the average errors in other molecular properties relative to the DFT calculation. We further show that it is possible to find optimal scale factors which reduce the mean unsigned error per bond to levels comparable to those of some multilevel multicoefficient methods.     

X-ray attenuation around <Emphasis Type="Italic">K</Emphasis>-edge of Zr,Nb, Mo and Pd: A comparative study using proton-induced X-ray emission and <Superscript>241</Superscript>Am gamma rays

Mass attenuation coefficients (μ/ρ) for Zr, Nb, Mo and Pd elements around their K-edges are measured at 14 energies in the range 15.744–28.564 keV using secondary excitation from thin Zr, Nb, Mo, Rh, Pd, Cd and Sn foils. The measurements were carried out at the K _α and K _β energy values of the target elements by two techniques: (1) Proton-induced X-ray emission (PIXE) and (2) ²⁴¹Am (300 mCi) source. In PIXE, 2 MeV proton-excited X-rays were detected by a Si(Li) detector. In the second case, X-rays excited by 59.54 keV photons from the targets were counted by an HPGe detector under a narrow beam good geometry set-up with sufficient shielding. The results are consistent with theoretical values derived from the XCOM package and indicate that the PIXE data have better statistical accuracy.     

Calcium Alginate Bead-mediated Enhancement of the Selective Recovery of a Lead Novel Antifungal Bacillomycin Variant

In the pursuit of new antifungal compounds, five coproduced lipopeptide variants (AF₁ to AF₅) from wild-type Bacillus subtilis RLID 12.1 were identified in our previous study. Out of five, AF₄ was identified as a novel lead molecule belonging to the bacillomycin family showing less cytotoxicity at its respective minimum inhibitory concentrations (MIC) evaluated against 81 strains of Candida and Cryptococcus species (including clinical isolates); besides this, AF₄ purified in the present study exhibited encouraging MIC values against 10 clinical mycelial fungi. Aiming for a selective production augmentation of AF₄ lipopeptide variant, a new fermentation media comprising malt extract (1.01%), dextrose (0.55%), peptone (1.79%), MnSO₄ (2 mM), and NaCl (0.5%) was formulated. Maximum production of 954.8?±?10.8 mg/L was achieved with 44% selectivity at 30 °C compared to unoptimized conditions (186.4?±?6.1 mg/L). Use of calcium alginate beads in the formulated media during the onset of lipopeptide production resulted in an augmentation in the selectivity of the most efficacious AF₄ variant to about 72% presumably due to attenuation of other coproduced lipopeptide variants AF₁ and AF₂. Difference in yield of lipopeptides varied with bead size, bead preparation ratios, and sodium alginate concentrations. Use of Ca-alginate beads in the upstream production process of the lead AF₄ variant may be considered as a novel strategy to address the potential challenge that may arise during the scale-up and downstream processing steps. Another significant finding derived from the study is that the proportion of bacillomycin variants of B. subtilis RLID 12.1 could be controlled by temperature and metal ions under static and shaking conditions.     

Direct,high-yielding,one-step synthesis of vic-diols from aryl alkynes

An unprecedented, high yielding, direct, one-step synthesis of vic-diols from alkynes has been developed via metal-free, open-to-air dihydroboration with ammonia borane. The electronics of the alkyne and the reaction stoichiometry are critical for obtaining optimal yields of the 1,2-diol.     

Synthesis of highly functionalized strained bicyclic dilactam derivatives

An efficient and modest protocol has been utilized for the synthesis of bicyclic dilactam derivatives through one-pot multicomponent domino reaction starting from various cyclic ketones under mild condition. The synthesized motif shows four stereogenic centers with two quaternary amine functionalities and such molecular arrangements are very fascinating and rare to obtain. We propose a mechanism for the formation of bicyclic dilactams through aldol condensation/condensation of cyanoacetamides/cyclization of condensed intermediate.