Abstract: This paper presents the experimental investigations on magnetic field assisted abrasive finishing of SS304L flat work material. The experiments are designed using Taguchi design of experiments method. The results indicate that process parameters such as voltage and machining gap are significant on improvement of surface finish (∆Ra). The surface roughness value as low as 0.09 µm is achieved at optimum conditions. The surface topography of the work material is analyzed by means of the surface roughness profile, optical and atomic force micrographs.
Abstract: In the present study, calculated amount of polyvinylidene fluoride (PVDF) was added to a mixture of two different polar solvents and maintained under continuous stirring for overnight. The PVDF solution thus obtained was spin-coated over divergent substrates like KBr and gold coated glass substrates at 80 oC. The spin-coated samples were further exposed to varying thermal conditions such as as-cast (AC), annealed at 130 °C (AN) and melt (200 °C)-slow cooled (MSC) for a period of time. FTIR spectroscopic data obtained from this study was found to be quite useful in analyzing the changes in absorption intensity of crystalline phase changes as a function of varying substrate and heat treatment conditions. Aβ,γ,α/A1073 ratio was observed to be favorable for AN samples when compared to that of AC and MSC samples, and among the substrates, gold is more preferable due to its real-time usage as a substrate in electronic device applications.
Abstract: Thin films of polyvinylidene (PVDF) and its copolymers containing 50 to 30 mole % of trifluoroethylene (TrFE) demonstrate rapid reversal of polarization under applied electric field, and can be used as ferroelectric materials in non-volatile memory devices. In this study, Fourier-transform infrared transmission (FTIR-TS) and grazing incident reflection absorption (FTIR-GIRAS) spectroscopy techniques were used to examine the changes in Curie transition temperature (Tc), chain and dipole orientation in selected VDF copolymer spun-cast films as a subjected to a reversible thermal-cycling treatment. A reversible solid-to-solid β-crystalline phase transition with thermal hysteresis and a favorable C-F dipole orientation along the electric field direction were observed for the sample subjected to thermal-cycling below its melting point (Tm). An irreversible β-crystalline phase transition with unfavorable C-F dipole orientation was observed for the sample treated to heating-cooling cycle above Tm. The results are reported in detail here.
Abstract: Abstract. Neodymium doped sodium bismuth borate (Na2O-Bi2O3-B2O3) glasses were prepared by melt quenching method. Amorphous nature of the glass is confirmed through the X-ray diffraction study. Density of the investigated glasses increases systematically with Bi2O3 concentration. Glass transition temperature decrease slightly with increase of Bi2O3 content and could be due to increase in the number of weaker Bi-O linkages by stronger Nd-O linkages. Fourier Transform - Infrared (FTIR) spectroscopy has been carried out. The IR spectra of the glasses reveal that the strong network consisting of diborate units and is unaffected by the variation of Nd3+ concentration. UV-Visible absorption studies have been performed on these glasses to examine the optical spectra and the optical band gap energy has been calculated. The intensity of the absorption band increases with the increase of Nd3+ concentration. This is due to the formation of non-bridging oxygens (NBO’s) in the structure.
Abstract: In the recent years, significant developments have been achieved with chitosan and hydroxyapatite (HAp) scaffolds for bone tissue engineering. In the present study, chitosan/nanostructured hydroxyapatite (Chitosan/nHAp) has been prepared and subsequently characterized physicochemically for bone graft substitution. The nano sized HAp particles were uniformly distributed in the chitosan matrix which was confirmed by Fourier Transform Infrared Spectroscopy, Thermal Gravimetric Analysis, X-Ray Diffraction and Scanning Electron Microscopy analysis. The pore size of the chitosan/nHAp scaffold was found to be 18-372 µm which is suitable for cell attachment and nutrient supplement. Thus, we are suggesting that Chitosan/nHAp could be promising biomaterials for bone tissue engineering.
Abstract: Hexagonal-phase LaF3: Ce3+, Pr3+, and Sm3+ doped (LCPS) nano-crystals have been synthesized by keeping same molarities of rare earth elements using aqueous route. The samples have been synthesized in conventional microwave on low power range in about an hour’s time. The phase formation has been verified by powder X-ray diffraction (XRD).Hexagonal geometry of the LCPS nano-crystals has been observed with an average particle size of 20 nm by TEM analysis. The JCPDS Card No. (32-0483) and selected area electron diffraction (SAED) pattern has been used for identification of crystal structure. The UV- VIS spectra indicated band gap of 5.00eV. The FTIR spectrums have been used for assignment of fundamental vibrations. Blue fluorescence observed with exciting wavelengths of 254 nm respectively. The presence of rare-earth elements in LCPS nano-crystals have been verified by the EDAX spectra.
Abstract: The effect of physical scaling on one dimensional (1-D) conducting polypyrrole (Ppy) nanowire device has been successfully studied. The synthesis, electrical characterization and ammonia gas sensing with 1-D Ppy nanowire device have been carried out in the present investigation. Ppy nanowires having ~80 to ~200 nm in diameter were synthesized by electrochemical polymerization in alumina template and 1.77 to 3 µm Ppy nanowire length were maintain by varying the distance between electrodes gap. We further demonstrated that gas sensors based on 1-D Ppy nanowire having high aspect ratio (length to diameter ratio, L:D) exhibits good sensitivity towards ammonia, and provided a reliable detection at concentration as low as approximately 1 ppm based on principal of physical scaling co-related to response resistance.
Abstract: MWCNT supported Pt, Ru, and Pt–Ru catalysts were prepared and reduced at two different temperatures, 375°C (LTR) and 675°C (HTR) for the selective hydrogenation of citral to the corresponding unsaturated alcohols (geraniol and nerol). The catalysts were characterized by BET Surface area measurement, TPD, SEM, EDAX, TEM, XRD and XPS. It was found that the XRD of Pt and Ru shows fcc and hcp crystalline structure respectively, which is uniformly dispersed with an average particles size of 3.5 nm and zero valence metallic state. The removal of acidic oxygen surface group is observed when heat- treatments in a inert atmosphere at 675°C were performed. The bimetallic catalyst of Pt-Ru/MWCNT (HTR) was found to afford remarkably high conversion levels (85%) and high selectivity (95%) provided that a thermal pretreatment was performed on the catalyst. These results can be rationalized in terms of electron transfer from the support to the metal. The catalysts are environment friendly and can be recycled for more than eight times.
Abstract: Zinc oxide (ZnO) nanostructures have attracted great attention as a promising functional material with unique properties suitable for applications in UV lasers, light emitting diodes, field emission devices, sensors, field effect transistors, and solar cells. In recent years, there has been a growing interest among the researchers to incorporate metal nanoparticles into polymer matrix. In the present work, the biopolymer chitin was deacetylated using zinc chloride and sodium hydroxide. The formed zinc oxide is blended with chitosan and the final product has been obtained as nano composite. The prepared material was characterized using FTIR spectroscopy with functional groups of amine (-NH2) for chitosan and ZnO stretching vibration. The crystallite size of materials was confirmed by X-ray diffractometry (XRD).The absorbance of chitosan-ZnO nanocomposite was confirmed by UV-vis Spectroscopy. The surface morphology of prepared materials was analysed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The above characterization studies was confirmed the presence of chitosan-ZnO nanocomposite.
Abstract: La0.67Ba0.33MnO3 powders were successfully prepared by a standard solid state reaction method, and systematically investigated the influence of the sintering temperature on the structural, microstructure, composition properties. The XRD pattern showed that the as prepared LBMO material was in single-phase with rhombohedral structure. From the scanning electron micrographs, it was observed that the grain size increased with sintering temperature and the average grain size was ~40nm.The surface roughness was measured by atomic force microscope and the RMS roughness of samples was in the range 48 to 85 nm. The as prepared samples exhibited nearly the same composition of the base material.