Methanogenesis mediated by methylotrophic mixed culture

Enrichment of methanogenic cultures on methanol from the microbial population in the anaerobic digesters operated on agricultural wastes revealed a high rate of biomethanation efficiency. Routine maintenance of this enrichment in a minimal basal medium at room temperature resulted in maximal growth in 40–50 d, and indicated pigment production toward the end of the growth phase. The cultures grown in three different media, with different substrates under light and dark conditions, were analyzed for protein, pigment, and gaseous products, and morphological studies were carried out by light, phase-contrast, fluorescence, and electron microscopy. In different media with methanol as substrate, growth and pigment production were maximal for the light-grown cells, decreasing in the order: phototrophic (PS(m)) > mineral > basal medium. Methanation and phototrophic growth were inversely correlated under lightgrown conditions. In contrast, growth in the dark was predominently methanogenic in the decreasing order: mineral > basal > PS (m). Among other growth conditions tested, utilization of phototrophic substrates under light and dark conditions indicated the following:

1. Basal and mineral media were supportive of methanogenic growth under both light and dark conditions, although methane yields under light-grown conditions were low;
2. Among the different substrates tested, methanol-grown cells gave the highest methane yield in the dark and;
3. Phototrophic growth in PS medium with succinate, malate, and pyruvate was better than that with methanol.

Absorption spectra of light-grown cells indicated the presence of bacteriochlorophyll a (Bchl a), as a doublet in the 800–0 nm region, which was absent in the dark-grown cells. Spectra of extracted pigments confirmed the presence of Bchl a with a 770-nm peak and carotenoid absorption bands in the 400–500 nm region indicative of the presence of a pigment of the spirilloxanthin type. Collective evidence for the predominant growth of a phototrophic organism under lightgrown conditions and microscopic examination under all conditions indicated the possible presence in the mixed culture of purple nonsulfur bacteria of theRhodopseudomonas type. In addition, the enrichment culture was found to contain other morphological forms, such as short and long rods, both individually and in clusters and coccoid cells. The presence of such different forms of microbial population in a methylotrophic enrichment along with phototrophic bacteria is interesting and is of ecological significance. Considering the uphill task of methanol oxidation under anaerobic conditions, the studies on the present enrichment signify metabolic partnerships in the methylotrophic biochemical mechanisms operative toward energy recovery.     

NDDO MO calculations

The Roby version of the NDDO MO method has been analysed by performing extensive calculations on several molecular systems employing a minimum basis set of STO-3G functions. The effect of using uniform scale factors and those derived from theS-expansion technique, for electron repulsion integrals has also been studied. At the all-electron level, the method, with all its refinements, does not appear promising. The all-valence NDDO MO method after correction byS-expansion, however, yields results which are in good agreement withab initio results. The performance of this scheme is comparable to that of the simplifiedab initio method of Brown and Roby.     

A Rapid Stability-Indicating LC Method for Ziprasidone Hydrochloride

A simple and rapid reversed-phase liquid chromatographic method was developed for the related substances determination and quantitative evaluation of ziprasidone hydrochloride, which is used as an antipsychotic agent. Forced degradation studies were performed on bulk sample of ziprasidone hydrochloride using acid, base, oxidative hydrolysis, thermal stress and photolytic degradation. Mild degradation of the drug substance was observed during thermal stress and considerable degradation observed during base hydrolysis. The chromatographic method was fine tuned using the samples generated from forced degradation studies. Good resolution between the peaks corresponds to synthetic impurities and degradation products from the analyte were achieved on YMC Pack Pro C18 column using the mobile phase consists of a mixture of 0.05% v/v of phosphoric acid in water and acetonitrile. The stressed test solutions were assayed against the qualified working standard of ziprasidone hydrochloride and the mass balance in each case was close to 99.7% indicating that the developed method was stability-indicating. Validation of the developed method was carried out as per ICH requirements.     

Computer extended series solution for unsteady flow in a contracting or expanding pipe

Unsteady flow in a semi-infinite contracting or expanding pipeis reinvestigated using long series analysis. The proposed seriesmethod is useful in analysing the problem for a moderately largeconstant ( = aa/, where a = a(t), the radius of the pipe isa function of time, a(t) is the velocity of the wall, and iskinematic viscosity). For positive values of (expansion ofthe pipe) accuracy of the series representing shear stress andpressure gradient is increased from = 2.89 to = 6.0 by extractingthe singularity followed by completion of the series. For negativevalues of (contraction of the pipe), we revert the series whichresults into the increase of the region of validity of the transposedseries from = -25.0 to = -2.89. Later we use Padé approximantsfor summing them. Also, the asymptotic solution for large valuesof is obtained and it agrees closely with pure numerical valuesof shear stress at the wall and pressure gradient.     

Weak Clarke epiderivative in set-valued optimization

A new notion of weak Clarke epiderivative for a set-valued map is introduced using the concept of Clarke tangent cone. The existence, characterization and properties of weak Clarke epiderivative are then studied. Finally optimality criteria are established for a constrained set-valued optimization problem in terms of weak Clarke epiderivative.     

D-branes, exceptional sheaves and quivers on Calabi–Yau manifolds: from Mukai to McKay

We present a method based on mutations of helices which leads to the construction (in the large-volume limit) of exceptional coherent sheaves associated with the (∑_al_a=0) orbits in Gepner models. This is explicitly verified for a few examples including some cases where the ambient weighted projective space has singularities not inherited by the Calabi–Yau hypersurface. The method is based on two conjectures which lead to the analog, in the general case, of the Beilinson quiver for . We discuss how one recovers the McKay quiver using the gauged linear sigma model (GLSM) near the orbifold or Gepner point in Kähler moduli space.     

Computational fragment-based design of Wee1 kinase inhibitors with tricyclic core scaffolds

Wee1 is cell cycle protein comprising a kinase domain and is a validated cancer target. We have designed molecules with variable tricyclic core scaffolds [6-6-5] system and extended them based on the chemical space available in the active site of Wee1 kinase using de novo drug design. The core scaffolds and linking fragments were extracted from pharmacophore-based virtual screening of ZINC and PubChem databases and Ludi library. These molecules bind the hinge region of kinase active site and form hydrogen bonds as confirmed from molecular docking, molecular dynamics simulations, and MM_PBSA calculations. When compared with reference inhibitors, AZD1775 and PHA-848125, the de novo designed molecules also show good docking scores and stability, retained non-covalent interactions, and high binding free energies contributed from active site residues.

     

Revisiting the reduction of indoles by hydroboranes: A combined experimental and computational study

A combined experimental and density functional computational study was used to probe the mechanism for the reduction of indoles using simple borane BH₃·DMS (DMS?=?dimethyl sulfide). Experimental and computational studies all steer to the formation of the reduced species 1-BH₂-indolines as the resting state for this reaction, as opposed to the historically presumed formation of the unreduced 1-BH₂-indoles, before the addition of a proton source to form the final product indolines. Furthermore, it was observed that molecular H₂ was generated and consumed in the reaction. Computations put forward hydroboration followed by protodeborylation as the very reasonable mechanistic route for the formation of experimentally observed major intermediate 1-BH₂ indolines. For the H₂ consumption in the reaction, computations suggest the frustrated Lewis pair-type heterolytic splitting of H₂ by a bis(3-indolinyl)borane intermediate.     

Bay Functionalized Perylenediimide with Pyridine Positional Isomers: NIR Absorption and Selective Colorimetric/Fluorescent Sensing of Fe<Superscript>3+</Superscript> and Al<Superscript>3+</Superscript> Ions

Bay functionalized perylene diimide substituted with pyridine isomers, (2-pyridine (2HMP-PDI), 3-pyridine (3-HMP-PDI) and 4-pyridine (4-HMP-PDI)) have been synthesized and explored for selective coloro/fluorimetric sensing of heavy transition metal ions. HMP-PDIs showed strong NIR absorption (760–765 nm) in DMF. The absorption and fluorescence of HMP-PDIs have been tuned by make use of pyridine isomers. Reddish-orange color was observed for 2-HMP-PDI (λ_max = 437, 551, 765 nm) whereas 4-HMP-PDI exhibited light green (λ_max = 432, 522, 765 nm). 3-HMP-PDI showed orange-yellow (λ_max = 431, 524, 762 nm). The fluorescence spectra of 2-, 3- and 4-HMP-PDI showed λ_max at 585, 538, 546 nm, respectively. Interestingly, HMP-PDI dyes showed selective color change (intense pink color) and fluorescence quenching for Fe³⁺ and Al³⁺ metal ions in DMF. Absorbance spectra revealed complete disappearance of NIR absorption and intensification/appearance of new peak at lower wavelength. The concentration dependent studies suggest that 4-HMP-PDI can detect up to 36.52 ppb of Fe³⁺ and 43.12 ppb of Al³⁺ colorimetrically. The interference studies in presence of other metal ions confirmed the good selectivity for Fe³⁺ and Al³⁺. The mechanistic studies indicate that Lewis acidic character of Fe³⁺ and Al³⁺ ions were responsible for selective color change and fluorescence quenching.