First synthetic approach towards K-259-2, a unique calmodulin antagonist

K-259-2, a unique calmodulin antagonist, is an allyl chain containing anthraquinone natural product. A regiospecific synthetic approach towards K-259-2 is herein represented. The study also showcases a protocol for synthesizing heavily substituted bromo naphthoate which was found to be suitable for fabricating the K-259-2 motif.     

Studies on potential utilization of rice husk char in blend with lignite for cocombustion application

Combustion behavior of Indian lignite sample blended with rice husk chars (prepared at low temperature) has been examined in this study through simultaneous differential scanning calorimetry (DSC) and thermogravimetric analysis (TG) technique. Range of inputs obtainable by characteristic TG–DSC parameters has been utilized to arrive at important conclusions and observations in respect of ideal selection of blend proportion, proper utilization of the blend combination, etc. Deviations of experimental mass loss pattern (TG) and of rate curve (DTG) from corresponding expected theoretically calculated pattern have also been noted for different blends to examine possible advantageous or disadvantageous effects. As per the observations recorded, use of biomass char in blends (with lignite) was found to be very much beneficial and its proportion in the blends may be restricted to a level of 40 % by mass to extract maximum benefits in burning performance. This paper also focuses specific advantages of use of rice husk char in place of raw rice husk for cocombustion applications. Moreover, the importance of heat release pattern to assess compatibility of a fuel mix with existing boiler design and also to workout fresh boiler design for cocombustion application has been discussed in this paper.     

Dynamics of solid-melt front migration from a reaction–diffusion model

Using physical experiments we investigated the evolution of thermally driven melt patterns in a semi-infinite solid crystalline phase subjected to uniform heating from one side, maintaining melting temperature. We treat the melt initiation phenomenon theoretically in the perspective of two-phase interactions on the microscopic level, and propose a new reaction–diffusion model based on the prey–predator dynamics. This model predicts the fractal behavior of melt fronts observed in the experiments.     

Palladium based heterogeneous catalyst by evaporation-induced self-assembly: use of biopolymer as a surface functionalizing and reducing agent

Palladium-based composites are widely used as a heterogeneous catalyst in carbon–carbon coupling reactions and in catalytic converters used in the car industry. In this work, we demonstrate a simple, green and scalable synthesis procedure to obtain palladium (Pd) based heterogeneous catalyst. Surface functionalized silica microparticles were obtained in one-step by spray-drying a colloidal suspension of silica nanoparticles and gum arabic, an environmental-friendly biopolymer. Subsequently, palladium nanoparticles were reduced and attached to the substrate by gum arabic. The as-synthesized composite was characterized by field-emission scanning electron microscopy (FESEM), energy-dispersive x-ray spectroscopy (EDS), x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), small angle x-ray scattering (SAXS), and high-resolution transmission electron microscopy (HR-TEM). The Pd@SiO₂ composite was used as a catalyst in the reduction reaction of 4-nitrophenol by sodium borohydride. The catalyst showed good recycling properties. The present environmental-friendly approach for fabrication of Pd-based heterogeneous catalyst circumvents various complex chemical steps involved in conventional chemical methods and could be generalized for the production of ceramic or magnetite-based Pd composites.     

Thermosolutal Convection in a Rectangular Concentric Annulus: A Comprehensive Study

This investigation presents numerical treatment of governing equations pertaining to thermosolutal flow within an annulus and an application of a model describing the important physical phenomenon as found in muffle furnace. The inner side of the annulus is exposed to high temperature and high solute concentration while the outer side of the annulus is maintained at low temperature and low solute concentration. Darcy-Brinkman-Forchheimer model is used to study the flow, heat and solute transfer in a non-Darcian saturated porous media. The solution is obtained upon application of control volume integration. Modified MAC method is used for the numerical solution of governing equations. Gradient dependent consistent hybrid upwind scheme of second order (GDCHUSSO) is used for discretization of the convective terms. The parameters such as Rayleigh-Darcy number, Darcy number, buoyancy ratio and width ratio, that govern the flow phenomenon have been identified and their effects are critically examined. The fluid flow pattern in the annular space and the associated heat and mass transfer are conceptualized from the obtained isoconcentration, isotherm and flowline contour maps.     

Length-scale dependent superconductor-insulator quantum phase transitions in one dimension

We study the dissipation physics of a one dimensional mesoscopic superconducting quantum interference device array using the field-theoretical renormalization group method. We observe length scale dependent, superconductor-insulator quantum phase transition at very low temperature and also observe the dual behavior of the system for higher and lower values of magnetic field. At a critical magnetic field, we also observe a critical behavior where the resistance is independent of length.