Activity performance and kinetics for glycerol carbonylation with urea over Zn-Co mixed metal oxide catalyst

Efficient carbonylation of glycerol using urea with Zn-Co mixed metal oxide (MMO) catalyst has been achieved. Various methods of catalyst preparation were explored for glycerol carbonate (GC) synthesis. The optimized method of catalyst preparation was found to be co-precipitation (CP) with a Zn:Co ratio of 70:30, achieving 81% glycerol conversion with 97% GC selectivity. X-ray diffraction (XRD) studies revealed the formation of ZnO, Co₃ O₄, and spinel ZnCo₂O₄ phases. Thermal treatment given to the catalyst allows insertion of Zn cations into Co₃O₄ lattice forming ZnCo₂O₄ phase which was also evidenced in X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. Herein, for the first time, reaction kinetics was studied to propose the rate equation, based on which a plausible reaction pathway is proposed involving two-site adsorption of glycerol (basic site) and urea (acidic site), which undergo carbonylation followed by cyclization into GC. A recycle study and hot filtration test have proven the reusability of the catalyst.     

White-light emission from a blend of CdSeS nanocrystals of different Se:S ratio

CdSeS nanocrystals with different bandgap energies have been synthesized by the colloidal method. The solution blend of blue-, green-?and red-emitting CdSeS nanocrystals, in appropriate proportions, showed strong white emission of different shades on excitation with a UV source. We observed that the CIE coordinate of the spectrum of a particular blend is independent of excitation wavelength. We also observed that the contribution of self-absorption in energy loss in the blend of CdSeS nanocrystals is not very significant. A white-light-emitting LED has been fabricated by coating a blend mixed with polymethylmethacrylate on a commercial UV-LED.     

Lamotrigine‐loaded polyacrylate nanoparticles synthesized through emulsion polymerization

A series of copolymeric nanoparticles of the partially water‐soluble monomer ethyl methacrylate and the water‐soluble monomer 2‐hydroxyl ethyl methacrylate were synthesized from emulsions containing sodium dodecyl sulfate via free‐radical polymerization. Lamotrigine, as a model drug, was loaded in nanoparticles during in situ polymerization. A stable and transparent poly(ethyl methacrylate‐co‐hydroxyl ethyl methacrylate) nanolatex was produced for all compositions and characterized for particle size by dynamic light scattering and transmission electron microscopy. Particles were found to be smaller than 50 nm in size. Structural characterization of copolymers was done by infrared spectrometry, gel permeation chromatography, and NMR spectroscopy. Drug encapsulation efficiency was determined by ultraviolet (UV)–visible spectrometry and was found to be 26–62% for copolymers with different compositions. UV data suggest molecular‐level dispersion of the drug in the nanoparticles. In vitro drug‐release studies showed the controlled release of lamotrigine. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Optimal demultiplexer unit design and energy estimation using quantum dot cellular automata

The Journal of Supercomputing - Quantum dot cellular automata (QCA)-based demultiplexer or DeMUX is a basic module of nanocommunication and nanocomputation, like a multiplexer. However, the design...     

Static hazard elimination for a logical circuit using quantum dot cellular automata

Microsystem Technologies - Quantum dot cellular automata (QCA) is an upcoming nano-technology for its high speed and low power operation in the field of nano-science and nano-electronics. As QCA...     

Dynamic data driven transportation systems

Multimedia Tools and Applications - Congestion-induced delays and pollution in modern transportation systems remain formidable impediments to the sustainable growth of our cities. Next generation...     

Design and energy dissipation analysis of simple QCA multiplexer for nanocomputing

The Journal of Supercomputing - The multiplexer is an integral design component of the conventional CMOS technology and modern QCA nanotechnology. It is also an elementary building block of...     

An uncalibrated lightfield acquisition system

Acquisition of image data for lightfield usually requires an expensive, complex and bulky setup. In this paper, we describe a simple method of acquiring the image data set. The method requires a normal handheld video camera, which is taken around the object to be rendered. We employ homography from the viewing/camera plane to the lightfield plane for obtaining the ray intersections with the lightfield planes. The computations involved are simple and make the method suitable for online lightfield acquisition.     

Synthesis of CdSe nanocrystals in a noncoordinating solvent: effect of reaction temperature on size and optical properties

Colloidal synthesis of high quality CdSe nanocrystals with controllable size and tunable properties have been one of the most important topics of research over the last decade, in view of its huge technological potentials. CdSe is one of the most studied nanocrystals of this category because of its photoluminescence tunability across the visible spectrum. We have synthesized CdSe nanocrystals using CdO precursor in a noncoordinating solvent and studied the effect of the reaction temperature on the size and optical properties of the nanocrystals. The size of the nanocrystals could be varied systematically in the range of 3.5 to 6.6 nm diameter with a remarkably narrow size distribution by controlling only the reaction temperature, without any need for a post-synthesis processing. The band gap and the corresponding band edge emission could be tuned across the entire visible range by tuning the size of the nanocrystals. The narrow width of the photoluminescence emissions of different colours (blue to red) make these nanocrystals a potential candidate for different optical and optoelectronic devices.     

Preparation and characterization of venlafaxine hydrochloride‐loaded chitosan nanoparticles and in vitro release of drug

The venlafaxine hydrochloride (VHL)‐loaded chitosan nanoparticles were prepared by ionic gelation of chitosan (CS) using tripolyphosphate (TPP). The nanoparticles were characterized using FTIR, differential scanning calorimetry, X‐ray diffraction, dynamic light scattering, transmission electron microscopy, and X‐ray photoelectron spectroscopy. The effect of concentration of CS, polyethylene glycol (PEG), VHL and CS/TPP mass ratio on the particle size and zeta potential of nanoparticles was examined. The particle size of CS/TPP nanoparticles and VHL‐loaded CS/TPP nanoparticles was within the range of 200–400 nm with positive surface charge. In the case of VHL‐loaded nanoparticles and PEG‐coated CS/TPP nanoparticles, the particle size increases and surface charge decreases with increasing concentration of VHL and PEG. Both placebo and VHL‐loaded CS/TPP nanoparticles were observed to be spherical in nature. PEG coating on the surface of CS/TPP nanoparticles was confirmed by XPS analysis. Maximum drug entrapment efficiency (70%) was observed at 0.6 mg/mL drug concentration. In vitro drug release study at 37°C ± 0.5°C and pH 7.4 exhibited initial burst release followed by a steady release. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009