Background The powders of Ni-Cr Nano ferrites were synthesized with the chemical formula, NiCrXFe2−XO4 (Where X = 0.1, 0.3, 0.5, 0.7, 0.9 and 1.0) by using citrate-gel auto combustion technique. The structural characterization was investigated by X-Ray Diffractomerter (XRD). X-ray analysis shows that the samples are cubic spinel structure (single phase) without any impurity peak and average crystallite size was in the range of 8.5-10.5nm. The dielectric measurements were carried out as a function of frequency and composition (X) at room temperature in the range of 20Hz-2MHz. The real part of dielectric constant (ε’) and dielectric loss factor (tan δ) showed a decreasing trend with increasing field frequency. The ac conductivity (σac) is calculated from the dielectric measurements and it is increased with the increase of frequency. The composition dependent dielectric parameters are reported.
Synthesis & Structural Characteristics of ZnBi2O4 Nanoparticles Prepared by Citrate-Gel Auto Combustion Method
Zinc Bismuth nanoparticles with chemical composition of ZnBi2O4 is prepared by chemical citrate gel auto combustion method by using citric acid as fuel. The synthesized nano particles are sintered at different temperatures like 300OC, 400OC, 500OC, & 600OC for 4 hours in air medium. The single phase cubic structure is confirmed by X-ray diffraction, the average crystallite sizes of these samples are found to be in the order of 34 nm to 60 nm. The surface morphology of the samples is studied by using Scanning Electron Microscopy. The EDS spectrum confirms the presence of Bismuth, Zinc and Oxygen without any precipitating cations. FT-IR spectroscopy confirms the formation of spinel structure, the average particle sizes of the samples are measured by using DLS technique.
Processing and Characterization of Vacuum-Free CuInSe2 Thin Films from Nanoparticle-Precursors using Novel Temperature Treatment Techniques
The objective of this work is the processing and characterization of a dense CuInSe2 solar-cell-absorber-layer based on nanoparticulate precursors. Bimetallic copper-indium- and elemental selenium-nanoparticles were synthesized by wet-chemical processes and then dispersed in organic solvents as nano-inks. These inks were then printed into different layer-stacks on a molybdenum coated float-glass-substrate via doctor-blading. The temperature treatment to transform these layer-stacks into dense CISe thin films was investigated, using a face-to-face technique and mechanically applied pressure or the repetition of coating and annealing. All absorber layers were characterized with SEM, EDX and XRD. Dense, coarse grained CuInSe2 layers with a thickness ≈ 7 µm were formed and the application of mechanical pressure shows potential to reduce thickness and sinter together the nanoparticles to large grains of ca. 3 µm in size. The face-to-face-annealing ensured keeping a stoichiometric ratio of (Cu+In) / Se ≈ 1, and can help reducing the content of oxides, even when the annealing is performed in ambient atmosphere. With a repetition of coating and annealing, dense CISe layers could be produced at low temperature of only 350 °C.
Chitosan microspheres (CS) prepared by water-in-oil emulsion/glutaraldehyde cross-linking-evaporation and simple coacervation/cross-linking with sodium tripolyphosphate were covalently linked to diosgenin hemiesters. The diosgenin content found using elemental analysis was ca. 6 to 42 wt-% and it showed dependence on the type of diosgenin hemiesters and on the method of preparation of the CS microspheres. Fourier transform infrared spectroscopy confirmed the hydrophobic functionalization of CS with the diosgenin hemiesters by amide bond formation. The effect of CS modification with diosgenin on the thermal properties was also studied using differential scanning calorimetry. Microsphere sizes determined using optical microscopy ranged from 60 to 700 um, while scanning electron microscopy depicted morphology dependent on the selected method to obtain CS microspheres. In vitro release studies performed in aqueous medium indicated a drug release dependence on the diosgenin hemiester linkers, the steroid content and the acidity of the solution. Sustained diosgenin release in acidic aqueous solution (pH 6.0) reached from 34 to 81% after 48 h.
Tin dioxide (SnO2) nanostructures have been synthesized successfully via solution phase growth technique. Effect of reaction temperature, time and surfactant on morphology, size and bandgap of nanomaterials has been studied. The rods, flowers and spheres like morphologies of SnO2 have been observed using Scanning Electron Microscope (SEM). Structural analysis of synthesized SnO2 has been carried out by X-ray Diffraction (XRD). XRD peaks revealed the tetragonal structure of SnO2 nanocrystals. The increase in grain size was observed with increase in reaction time and reaction temperature of synthesis process. Fourier Transform Infrared spectroscopy (FTIR) has been employed to study the vibrational modes. Optical properties of the SnO2 nanostructures have also been studied by UV-vis spectroscopy. The energy bandgap of the as prepared SnO2 nanocrystals was estimated between 3.76 eV and 4.05 eV. It has been observed that the bandgap of the synthesized SnO2 samples decreased with increase in particle size. This phenomenon can be attributed to the quantum confinement effect at smaller particle size.
Caco-2 cells were used as in vitro models to assess the cell viability characteristics of the carriers Soluplus®, Gelucire 50/13 and PVP K25 and the nanoformulations of Naproxen and Piroxicam. The assessment of cell viability was done using the tetrazolium salt based MTT assay. Gelucire 50/13 and its NFs were observed to have slightly higher cytotoxicity than PVP and Soluplus® and their respective NFs. All the NFs were observed to follow the cytotoxicity trend of the polymers. Our results show that no significant decrease in cell viability was seen until 0.01% concentration of Gelucire 50/13 for 12-h exposure. The NFs as well as the polymers alone had no significant effect on the viability of Caco-2 cells below 0.01% concentrations. The intestine has a protective mucous layer, whereas the cell culture monolayers do not. The intestinal tissues also have more capacity to recover from trauma than the cultured cells. Hence the present NFs can be expected to show lesser cytotoxicity when subjected to in vivo studies