Optical absorption investigations for efficient crystal violet dye removal from wastewater via carbon nanotubes:Montmorillonite-based nanocomposite.

The current study reports a facile method to fabricate functionalized multi-walled carbon nanotubes and montmorillonite clay mineral-based nanocomposite matrix and its detailed characterization using spectroscopic and morphological techniques. The nanocomposites have been studied for their potential applications in the treatment of contaminated water using batch adsorption studies. The investigations conducted using optical absorption spectroscopic measurements for the adsorption process indicate that the nanocomposite matrix can effectively remove almost 98% of the dye from aqueous solution. The nanocomposites have showed fast and strong adsorption behaviour for the dye with the maximum adsorption capacity (qm ) of ~467.3 mg g-1 in 25 min. The experimental data at equilibrium were also correlated with the theoretical adsorption isotherm and kinetic models. The results demonstrate that the experimental data fits well to the Freundlich adsorption isotherm model and conforms to second-order kinetics. Furthermore, the nanocomposite exhibits good recyclability without any marked decrease in the adsorption performance even after five adsorption cycles of usage which indicates its potential application as reusable adsorbent for the efficient removal of hazardous dyes from contaminated water.

Synthesis and characterization of sol-gel derived PZT nano powder.

Single phase nanocrystalline lead zirconate titanate (PZT) powder of composition Pb(Zr(0.52)Ti(0.48))O3 has been prepared by sol-gel process by using lead acetate trihydrate, zirconium propoxide and titanium propoxide as lead, zirconium and titanium precursor materials respectively. XRD, FTIR and TGA/DTA techniques are used to characterize structural, vibrational and thermal changes involved during the formation of PZT nanocrystalline powder with tetragonal phase. XRD pattern exhibits the polycrystalline nature of the powder heat treated at 800 degrees C with preferential orientation of (110) plane. Simultaneous TGA/DTA studies of the gel powder show endothermic and exothermic peaks corresponding to weight loss at different temperatures and increase in weight between 750 degrees C and 800 degrees C which confirms the improvement in crystallization. IR transmittance spectra of the powders heat treated at 650 degrees C and 750 degrees C show the coexistence of rhombohedral and teragonal phases and above this temperature only teragonal phase exists.

EPR and optical absorption studies on VO2+ ions in L-asparagine monohydrate single crystals.

X-Band electron paramagnetic resonance (EPR) studies of VO(2+) ions in l-asparagine monohydrate single crystals have been done at room temperature. Detailed EPR analysis indicates the presence of two magnetically inequivalent VO(2+) sites. Both the vanadyl complexes are found to take up interstitial position. The angular variation of the EPR spectra in three planes ab, bc and ca are used to determine principal g and A tensors. For the two sites the spin Hamiltonian parameters are, site I: g(x)=1.9633, g(y)=2.0274, g(z)=1.9797, A(x)=88, A(y)=61, A(z)=161x10(-4)cm(-1); site II: g(x)=1.9627, g(y)=1.9880, g(z)=1.9425, A(x)=90, A(y)=66, A(z)=167x10(-4)cm(-1). The optical absorption study is also carried out at room temperature and absorption bands are assigned to various transitions. The theoretical band positions are obtained using energy expressions and a good agreement is found with the experimental values. By correlating EPR and optical data different molecular orbital coefficients are evaluated and the nature of bonding in the crystal is discussed.

Effect of Variable Oxidation States of Vanadium on the Structural, Optical, and Dielectric Properties of B2O3-Li2O-ZnO-V2O5 Glasses.

In the present study, the effect of variable vanadium oxidation states on the structural, optical, and dielectric properties of vanadium oxide containing lithium borate glasses has been investigated. Electron paramagnetic resonance studies indicate that vanadium in these glasses is mostly in the V4+ state, having a tetragonal symmetry. As the glass composition of V2O5 increases, tetragonality also increases at the cost of octahedral symmetry. The photoluminescence (PL) spectra of these glasses are dominated by zinc oxide transition, whereas the peaks pertaining to the vanadyl group are not visible in the PL spectra. The optical absorption spectra show a single wide absorption band, which is attributed to V4+ ions in these glasses. The ac conductivity of the glasses increases with an increase in vanadium content. The highest electrical conductivity observed is ∼10-5 S cm-1 at 250 °C for the glass with 2.5 mol % V2O5. Electrical conductivity is dominated by electron conduction, as indicated by the activation energy calculation.

High permittivity polyaniline-barium titanate nanocomposites with excellent electromagnetic interference shielding response.

Organic conductive polymers are at the forefront of materials science research because of their diverse applications built around their interesting and unique properties. This work reports for the first time a correlation between the structural, electrical, and electromagnetic properties of polyaniline (PANI)-tetragonal BaTiO3 (TBT) nanocomposites prepared by in-situ emulsion polymerization. XRD studies and HRTEM micrographs of these nanocomposites clearly revealed the incorporation of TBT nanoparticles in the conducting PANI matrix. EPR and XPS measurements reveal that increase in loading level of BaTiO3 results in a reduction of the doping level of PANI. The Ku-Band (12.4-18 GHz) network analysis of these composites shows exceptional microwave shielding response with absorption dominated total shielding effectiveness (SET) value of -71.5 dB (blockage of more than 99.99999% of incident radiation) which is the highest value reported in the literature. Such a high attenuation level, which critically depends on the fraction of BaTiO3 is attributed to optimized dielectric and electrical attributes. This demonstrates the possibility of using these materials in stealth technology and for making futuristic radar absorbing materials (RAMs).

Unique case of successful twin pregnancy after spontaneous conception in a patient with uterus bicornis unicollis.

INTRODUCTION: Abnormal fusion of the mullerian ducts or failure of absorption of the septum causes varying degrees of congenital uterine malformation. Twin gestation in a case of bicornuate uterus is extremely rare. We are reporting this case because of its extremely rare presentation, where twins have managed to reach term after spontaneous conception. CASE REPORT: A 28-year-old second gravida, para one was initially diagnosed to have diamniotic dichorionic twins on ultrasound. At term, she was referred to us with severe preeclamptic toxaemia. On examination, she was found to have a bicornuate uterus with one fetus in each horn. Both siblings were successfully delivered by caesarean section. So far, only one similar case has been reported following in vitro fertilisation. CONCLUSION: Although poor reproductive performance has been documented in previous reports of bicornuate uterus with twin gestation, our patient managed to reach term with delivery of healthy siblings by caesarean section.