Synthesis, Characterization and Catalytic Activity of Melamine-Based Dendrimer Encapsulated Pd/Cu Bimetallic Nanoparticles
A melamine-based dendrimer was used to prepare a new class of heterogeneous Pd/Cu bimetallic nanoparticles (NPs). The physicochemical characteristics of Pd/Cu bimetallic NPS were studied with the aid of SEM, EDX, XRD, TG& DSC techniques. Leafs shape surface morphology and the presence of required palladium and copper ion were observed from SEM and EDX analysis respectively while TG& DSC showed good thermal stability, as well as XRD, revealed nano-shape FCC structure. The recycling ability of the catalyst was examined for five successive runs without any noteworthy loss of activity. The synthesized Pd/Cu bimetallic NPS exhibited high catalytic activity in the synthesis of ynone in which synthetic route was phosphine ligand-free.
Synthesis of Diazine-Based Dendrimer Supported Pd/Co Bimetallic Nanoparticles and Catalytic Activity for Sonogashira Coupling Reactions
A moisture-stable diazine-based dendrimer assisted heterogeneous bimetallic Pd/Co nanoparticles (NPs) was synthesized which showed a simple, profitable and environmentally sustainable operation for the Sonogashira reactions under copper and solvent-free conditions with regained easily and recycled four times without substantial activity loss. Furthermore, the dendrimer was analyzed by IR, 1H NMR, 13C NMR, and elemental analysis whereas the Pd/Co bimetallic NPs was characterized by EDX, TGA & DSC, and XRD techniques.
MHD Mixed Convection Flow of Casson Nanofluid past a Stretching Sheet in the Presence of Viscous Dissipation, Chemical Reaction and Heat Source/Sink
This paper focuses on the effect of MHD mixed convection flow of casson nanofluid past a stretching sheet in the presence of viscous dissipation, first order chemical reaction and heat source/sink. The profiles for the velocity, temperature and nanoparticle concentration depends on the parameters Casson fluid parameter β, concentration buoyancy parameter N, Hartman number M, radiation parameter R, Prandtl number Pr, the Schmidt number Sc, Brownian motion Nb, thermophoresis parameter Nt, Eckert number Ec, chemical reaction parameter γ the heat transfer Biot number γ1 and the mass transfer Biot number γ2. The constitute governing partial differential equation of flow, heat and mass transfer on considered flow are converted into nonlinear ordinary differential equations by employing suitable transformations and these transformed equations were solved by the Adam’s Moultan fourth order method with shooting technique. The various numerical tables are calculated and tabulated. Our results have been compared with the results of a previous study and found to be in an excellent agreement.
Synthesis of Punica Granatum Fruit Peel Extract Based Silver Nanoparticles and Evaluation of it’s Antimicrobial Activity
The main objective of the present work was to prepare pomegranate peel extract based nano particles by chemical complexation method. Ethanolic extracts of pomegranate peel were prepared by using Soxhlet apparatus and evaluated for phyto-chemical constituents. Qualitative analysis showed that pomegranate peel extract showed positive results for alkaloids, anthraquinones, saponins and terpenoids. The percentage moisture content and pH of the extract was found to be 72% and 3.6 respectively. A zeta potential and particle size of prepared nanoparticles was found in the range of -24.6 to– 34.5 mV and 118.6 nm to 231.7 nm, respectively. These range confirms that obtained particles were in nano range, i.e.
Composite materials get an importance in value as an advance materials such as automotive, aerospace, aircraft, defense, medical, marine, sports, recreation and various engineering applications due to their high strength-to-weight ratio, good cast ability and better tribological properties. Al-base 2024 alloy reinforced with SiC micron and nano particles were developed using stir casting technique due to low cast, ease in fabrication, recyclability and isotropic characteristics. The development of Aluminum metal matrix nano composites (AMMNCs) is most considered material for high temperature applications because of their excellent mechanical properties, increase performance and weight saving for more reduction of fuel consumption. The results indicate that Al-SiC composite has improved physical and mechanical properties such as tensile strength, charpy impact strength, brinell hardness, density and porosity percentage. Samples with micron particles and nano particles were developed to compare the properties of both. Microstructures of the samples were studied by means of X-Ray Diffraction and Scanning Electron Microscopy. The elemental composition was also analyzed through Energy Dispersive Spectroscopy. It was found that composites of Al-SiC have better and improved physical properties in nano dimensions.
Synthesis of Biocompatible carboxylic acid functionalized Graphene Oxide as a stimulator of bacterial growth
Researchers have shown great interest towards Graphene and its potential applications in various fields such as electronics, energy, materials and biomedical areas. The effects of Graphene, graphene oxide (GO) and its derivatives on bacteria activities is still controversial. Thus, how graphene and its derivatives interact with microorganisms and the mechanisms of their interactions are important issues for nanotechnology which need proper exploration. In the present investigation, graphene oxide (GO) has been synthesized and functionalized by the chemical method. The GO and COOH-functionalized GO have been characterized by Fourier transforms infrared spectroscopy; Raman spectroscopy and SEM analysis. Further, haemocompatibility study has been performed to check the biocompatibility of functionalized graphene oxide. The effect of GO and COOH-GO on the bacterial growth has been observed. The FTIR, Raman and SEM data confirm the successfully functionalization of GO with carboxyl (-COOH) group. The haemolysis test shows that GO and GO-COOH are highly hemocompatible. Interestingly, functionalized graphene oxide, can significantly stimulate bacterial growth for gram positive and gram negative bacteria, whereas as-made GO shows no effect. It can be concluded that carboxylic acid functionalized GO may act as a new, positive regulator for the growth of bacterial cells.
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.