Enhanced tortuosity for electrolytes in microwave irradiated self-organized carbon-doped Ni/Co hydroxide nanocomposite electrodes with higher Ni/Co atomic ratio and rate capability for an asymmetric supercapacitor.

We demonstrate a green, facile and rapid microwave-mediated process for fabricating carbon black (CB) incorporated Ni/Co hydroxide porous nanocomposites and study the effect of various mass loading of CB on supercapacitor performance. The structure and interactions between CB and Ni/Co hydroxide are characterized by using x-ray diffraction, Fourier-transform infrared spectroscopy and x-ray photoelectron spectroscopy, which suggest the miniaturization of the single-phase Ni/Co hydroxide formation time. A morphology study reveals that the addition of CB into Ni/Co hydroxide develops a loose network structure with well-defined architectural pores. In addition, the nanocomposites demonstrate noticeable improvements in porosity and atomic ratio of Ni/Co with an increasing percentage of carbon, which results in a higher diffusion of electrolytes, and hence electrical conduction. The developed electrode materials exhibit a maximum specific capacitance value of 1526 Fg-1 at current density 1 Ag-1 with excellent cyclic stability (92% retention at 5000 cycles), energy density (76 Wh Kg-1), power density (250 W Kg-1) and rate capability. A solid state asymmetric supercapacitor device is fabricated and utilized to brighten a commercial LED effectively for validating real usage.

Single-layer graphene-assembled 3D porous carbon composites with PVA and Fe3O4 nano-fillers: an interface-mediated superior dielectric and EMI shielding performance.

In this study, a novel composite of Fe3O4 nanofiller-decorated single-layer graphene-assembled porous carbon (SLGAPC) with polyvinyl alcohol (PVA) having flexibility and a density of 0.75 g cm(-3) is explored for its dielectric and electromagnetic interference (EMI) response properties. The composite is prepared by the solution casting method and its constituents are optimized as 15 wt% SLGAPC and 20 wt% Fe3O4 through a novel solvent relaxation nuclear magnetic resonance experiment. The PVA-SLGAPC-Fe3O4 composite shows high dielectric permittivity in the range of 1 Hz-10 MHz, enhanced by a factor of 4 as compared to that of the PVA-SLGAPC composite, with a reduced loss by a factor of 2. The temperature dependent dielectric properties reveal the activation energy behaviour with reference to the glass transition temperature (80 °C) of PVA. The dielectric hysteresis with the temperature cycle reveals a remnant polarization. The enhanced dielectric properties are suggested to be the result of improvement in the localized polarization of the integrated interface system (Maxwell-Wagner-Sillars (MWS) polarization) formed by the uniform adsorption of Fe3O4 on the surface of SLGAPC conjugated with PVA. The EMI shielding property of the composite with a low thickness of 0.3 mm in the X-band (8.2-12.4 GHz) shows a very impressive shielding efficiency of ∼15 dB and a specific shielding effectiveness of 20 dB (g cm(-3))(-1), indicating the promising character of this material for flexible EMI shielding applications.

Lithium niobate nanoparticle-coated Y-coupler optical fiber for enhanced electro-optic sensitivity.

Single crystals of lithium niobate (LiNbO3), possessing high birefringence and anisotropic properties have been explored, for a long time, to harness their excellent electro-optic properties. However, their nanoforms are comparatively less explored. In this context, dielectric constant and polarization (P) versus electric-field (E) characteristics of LiNbO3 nanomaterials have been studied. A nonideal P-E loop and a dielectric constant of 20 at the onset of 1 kHz were seen. The electro-optic sensitivity was found to be 4 times as compared to the bulk LiNbO3 crystals. The results are attributed to oxygen vacancies, antisite defects, and grain boundary effects in an already congruent structural matrix of LiNbO3.

In-vitro release kinetics and stability of anticardiovascular drugs-intercalated layered double hydroxide nanohybrids.

We report the intercalation and characterization of pravastatin and fluvastatin drugs in Mg(II)/Al(III) layered double hydroxides (LDHs) to form novel nanohybrid hydroxides through the coprecipitation technique. powder X-ray diffraction, Fourier transform infrared spectroscopy, and thermal analysis techniques reveal that the drugs are accommodated within the brucite layers. Structural characterization, computed results, and atomic force microscopy image analysis demonstrate that the fluvastatin anions are attached with the brucite as a monolayer, whereas the pravastatin anions form a multilayer. The shift in the stretching frequency of carboxylate anion of statin drugs provides evidence that the drugs are electrostatically bonded to LDHs. X-ray diffraction and thermal analysis studies performed after keeping the nanohybrid particles at 75 +/- 10% relative humidity atmosphere, indicate their physical stability due to proper confinement of drugs within the layers. In-vitro release study of developed nanohybrid particles suggests that the significant reduction in release rate of fluvastatin anions from fluvastatin intercalated LDHs is due to its hydrophobic nature and it can be further controlled by varying the concentration in physiological medium. After release, the data were fitted to the dissolution-diffusion kinetic model. The mechanism of drugs diffusion in hydrophobic nanohybrid is probably due to heterogeneous diffusion via anion exchange, while in a hydrophilic nanohybrid, it is due to intraparticle diffusion via anion exchange with the anions in the physiological medium.

Shape and size control of nano dispersed Mg/Al layered double hydroxide.

Controlling the shape and size of the layered inorganic-organic hybrid particles is a challenge with conventional methods of synthesis. The co-precipitation method has been modified to synthesize Mg/Al Layered double hydroxide by controlling the particle growth using ultrasonic wave at the time of nucleation. In this project, magnesium and aluminum ions were considered as model systems with carbonate anion as intercalating agent. The resulting particles are compared with those of LDHs produced by conventional co-precipitation method at constant pH. Powder X-ray diffraction confirmed formation of the layered double hydroxide phases having crystallite size 19-20 nm in both 'a' and 'c' crystallographic directions. Transmission electron microscope and dynamic light scattering revealed nano disperse hexagonal platelets with narrow size distribution and average size was around 48 nm. The modified method reduces the particle size, increases the surface charge, narrows down the size distribution and also reduces the aspect ratio of the particles. Therefore, it is suggested that low amplitude ultrasonic wave prevents the aggregation of the nuclei, thus restricting the particle growth and results in uniform size particles.