A facile and highly diastereoselective synthesis of carbocyclic spiro-pyrazolones via DABCO catalyzed Michael-Michael domino reaction

An efficient domino Michael-Michael reaction of ω- and δ-nitro α,β-unsaturated esters with alkylidenepyrazolones has been accomplished using DABCO as the organocatalyst under mild reaction conditions. Under the present organocatalytic method, a wide range of carbocyclic spiro-pyrazolones with three tertiary stereogenic centers and a quaternary stereocenter has been prepared in high yields and excellent diastereoselectivities. An ester and nitro groups present in the spiro-pyrazolones have been utilized for further structural transformations.     

Study of the polymer concentration and polymer/crosslinker ratio effect on gelation time of a novel grafted polymer gel for water shutoff using a central composite design method

In this research article, a hydrogel was prepared by crosslinking of carboxymethyl cellulose‐g‐polyacrylamide copolymer aqueous solution with chromium(III) acetate for the purpose of a water shutoff job in the oil reservoir. The experiments were conducted to investigate the main effects of copolymer concentration and crosslinker/copolymer ratio on gelation time of the hydrogel system. Then the effects of these two factors and their interactions on the gelation time were determined by using a central composite design (CCD) of the response surface method. CCD was used to generate the quadratic mathematical model for the gelation time response as a function of copolymer concentration, crosslinker/copolymer ratio, and their interaction. Furthermore, the analysis of variance (ANOVA) was used to evaluate the quality of the quadratic model. The ANOVA result of the developed model showed that the model was highly significant. The result also showed that the crosslinker/polymer ratio had more effects on the gelation time than did the polymer concentration and their interaction. A response surface method provides an optimum gel formulation. Core flooding experiments reveal that a significant permeability reduction on the sand pack cores can be achieved at reservoir conditions, when it is treated with an optimum gel formulation. Hence, this gel system may be suitable in the water shutoff job required for enhanced oil recovery from the oil fields. Copyright © 2015 John Wiley & Sons, Ltd.     

X-rayK-absorption edge interpretation and energy determination

The low energy features of XANES (X-ray absorption near edge structure) in the X-rayK-absorption edge of transition metal systems have long been detected and attempts have been made to explain their origin. Only recently have some theoretical approaches based upon multiple scattering (MS) effects been applied in explaining the shape of theK-edge features. But the pre-edge shoulder, often labelled asB, has hitherto defied satisfactory explanation for its origin. The present work is an attempt in explaining the possible origin of this feature by using MS-theory to theK-edge XANES of some first row transition metal systems. The calculated energies using MS-formalism were found to be closer to the experimentally observed values for some systems of cobalt and copper. Using these results, theK-edge featuresA,B,C have been assigned to be originating from the resonance effects of scattering of the ejected photo-electron with the molecular potential set up by the central absorbing atom and its near neighbours.     

Plasmon energy, bulk modulus, electronic polarisability of AIBIIIC2VI and AIIBIVC2V ternary chalcopyrite semiconductors

A simple relation between the bulk modulus, plasmon energy, electronic polarisability are given for ternary chalcopyrite semiconductors. Bulk modulus has been evaluated from plasmon energy by proposing a linear relation between them. From bulk modulus electronic polarisability has been evaluated. The estimated values are in good agreement with the experimental values and earlier researchers.     

Fabrication and Cytocompatibility Evaluation of Psyllium Husk (Isabgol)/Gelatin Composite Scaffolds

Psyllium husk or isabgol contains xylan backbone linked with arabinose, rhamnose, and galacturonic acid units (arabinoxylans). In this study, we demonstrate the fabrication and characterization of a macroporous three-dimensional (3D) composite scaffold by mixing psyllium husk powder (PH) and gelatin (G) in different ratios, viz.100 PH, 75/25 PH/G, and 50/50 PH/G (w/w), using an EDC-NHS coupling reaction followed by freeze-drying method. The reaction was performed in aqueous as well as in alcoholic media to determine the most appropriate solvent system for this purpose. The mechanical strength of the scaffold system was improved from 151 to 438 kPa. The fabricated scaffolds exhibited enhanced structural stability, remarkable swelling capacity, and escalated cell growth and proliferation. ATR-FTIR analysis showed the presence of amide and ester bonds indicating covalent crosslinking. SEM micrographs revealed the porous nature of the scaffolds with pores ranging from 30 to 150 μm, and further pore size distribution curve indicated that 75/25 PH/G (w/w%) EDC-NHS-alcohol scaffold exhibited the best fit to the Gaussian distribution. Swelling capacity of the 100 PH EDC-NHS-alcohol scaffolds was found to be nearly 40% from its original weight in 48 h. MTT assay using fibroblast cells revealed ~ 80% cellular proliferation by 6th day within the fabricated scaffolds in comparison to control.

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Photonic band gap effect in one-dimensional plasma dielectric photonic crystals

Propagation of electromagnetic waves in one-dimensional plasma dielectric photonic crystals, the superlattice structure consisting of alternating plasma and dielectric materials, is studied theoretically using transfer matrix method. Numerical calculation is presented for plasma-air finite and infinite periodic structures. The results of photonic band gap characteristics are discussed in terms of plasma density, plasma width, and number of unit cells (N).