http://localhost:8081/jspui/handle/123456789/4969 2025-07-26T23:57:29Z http://localhost:8081/jspui/handle/123456789/17949 Title: SYNTHESIS OF NiO NANOPARTICLES AND STUDY THEIR PROPERTIES Authors: Sanger, Amit Abstract: NiO nanoparticles were synthesized using simple wet chemical method. These nanoparticles were calcinated at different temperatures 300°C-1000°C (S1-S5) and their structural properties were studied using X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM) and Transmission Electron Microscopy (TEM). X-ray diffraction observations and FESEM images of the calcinated NiO samples indicate that the crystallinity and the particles size both were increasing with increase in calcination temperatures. The XRD results confirm the decrease in strain with respect to calcinated temperature. This may be due to the surface effects and defects existed in the samples. TEM results confirm the polycrystalline nature of samples by SAED pattern. The electrical properties of the NiO pellets were examined by four probe method by measuring direct current (DC) conductivities at different temperatures. The activation energy (Ea) decreases from 0.57eV to 0.33eV when pellets annealed from 300°C to 800°C. The conductivity of samples increased with increase in particle size. It is because that electrons felt low resistance during travel due to large grain size. The optical properties were examined by Photoluminescence (PL) spectroscopy. The emission band came out in the visible range. The surface effects dominated the optical characteristics. The magnetic properties were examined by SQUID. The magnetic moment values come out 3.081.tB to 8.07lB from the measurement. The Weiss constant increased with the particle size and overcome the Ned temperature which may be due to the superexchange properties of NiO samples. The samples did not show any superparamagnetic effect at room temperature which may be due to the multidomain nature of particles. 2013-06-01T00:00:00Z http://localhost:8081/jspui/handle/123456789/17832 Title: SYNTHESIS AND CHARACTERIZATION OF T102@NiO NANOSTRUCTURES Authors: Kumar, Vijayesh Abstract: A method to synthesize Ti02@NiO core shell nanostructures was developed for a number of applications such as photocatalysis, DSSC, biotechnogical fields etc. The square faced NiO nanorods were synthesized by thermal decomposition of nickel oxalate dihydrate nanorods, which was prepared by reverse micellar route. The two microemulsions contains oil phase (iso octane as non polar solvent, n-butanol as co-surfactant and CTAB surfactant) and 0.1 M salt solution as water phase reacts to form nickel oxalate dihydrate nanorods. TiO2 nanoparticles were synthesized by hydrolysis of titanium tetra isopropoxide (TT'IP). TiO2 nanoparticles were - coated on the surface of NiO nanorods by electrostatic interaction and then product was annealed at suitable temperature to get Ti02@NiO core shell nanorods. These nanorods were characterized by PXRD, FESEM, TEM, UV-Vis spectroscopy, SQUID. In another study, NiO nanoparticles were fabricated through the chemical precipitation method by using nickel nitrate, sodium hydroxide as precursor materials and CTAB as surfactant. PXRD data gives the primary characterization about the crystalline NiO nanostructures. TiO2 coating on these nanostructures was done by using titanium tetra isopropoxide as precursor and NH40H as capping agent. The shell of T102 can be analyzed by FESEM and PXRD, and so there is pre calculated amount of precursor has been used. Core shell structure reduces the surface charge recombination as TiO2 coating acts as a blocking layer for electron to reduce back recombination. Using these nanostructures, a good the photocatalytic performance is expected. 2013-06-01T00:00:00Z http://localhost:8081/jspui/handle/123456789/17830 Title: SYNTHESIS OF VARIOUS NANOCOMPOSITES AND STUDY OF THEIR BIOMEDICAL APPLICATIONS Authors: Matai, Ishita Abstract: Emergence of multi-resistant organisms (MROs) leads to ineffective treatment with the currently available medications which pose a great threat to public health and food technology sectors. In this regard, there is an urgent need to strengthen the present therapies or to look over for other potential alternatives such as use of "metal nanocomposites" and "herbal drug loaded polymeric nanofibers". Thus, the present study focuses on synthesis of silver-zinc oxide (Ag-ZnO) nanocomposites which will have a broad-spectrum antibacterial activity against Gram-positive and Gram-negative bacteria. Ag-ZnO nanocomposites of varied molar ratios were synthesized by simple microwave assisted reactions in the absence of surfactants. The crystalline behavior, composition and morphological analysis of the prepared powders were evaluated by X-ray diffraction, infrared spectroscopy, field emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray (EDX) analysis. Particle size measurements were carried out by transmission electron microscopy (TEM). Staphylococcus aureus (S. aureus) and recombinant green fluorescent protein (GFP) expressing antibiotic resistant Escherichia coil (E. coil) were selected as Gram-positive and Gram-negative 11 model systems respectively and the bactericidal activity of Ag-ZnO nanocomposite were studied. The minimum inhibitory concentration (MIC) and minimum killing concentration (MKC) of the nanocomposite against the model systems were determined by visual turbidity analysis and optical density analysis. Qualitative and quantitative assessments of its antibacterial effects were performed by fluorescent microscopy, fluorescent spectroscopy and Gram staining measurements. Excellent bactericidal activity at low concentrations of nanocomposites was observed in both A the bacterial model systems suggesting its potential application as a broad-spectrum antibacterial agent. Changes in cellular morphology were examined by atomic force microscopy (AFM), FE-SEM and TEM. Finally, on the basis of the present investigation and previously published reports, a plausible antibacterial mechanism of Ag-ZnO nanocomposites was proposed. Also, electrospinning technique was utilized to fabricate chitosan-PEO (Polyethylene oxide) nanofibers loaded with herbal drug. The morphology, homogeneity and diameter of the synthesized nanofibers were determined by FE-SEM analysis. Visual turbidity analysis and fluorescence microscopy were done to determine the MIC and MKC values of herbal drug. Further, the antibacterial activity of drug loaded nanofibers was determined by fluorescence microscopy against GFP E.coii. The fabricated nanofibers exhibited good antibacterial activity at low concentrations of herbal drug suggesting its implications in wound dressings. 2013-06-01T00:00:00Z http://localhost:8081/jspui/handle/123456789/17829 Title: SYNTHESIS OF PVP STABILIZED SILVER NANOSTRUCTURES AND STUDY OF THEIR PHYSICAL AND BIOLOGICAL PROPERTIES Authors: Kumar, Harsh Abstract: 1'he present work reports synthesis of l'VP coated silver nanostructures in a self assembled bottom-Lip approach. Their characterization carried out by XRD, FTIR, AFM, FESEM and 'l'FM. 'their optical, electrical and antibacterial activities have also been analysed. The size of Ag —PVP nanoparticles also found to be the function of concentration of seed Ag particles used for their preparation. For different seed concentration (106 rnol/dm3) at: 1.73, 2.88 and 5. 19. the particle size (nm) decreases as: 15, 7 and 2 respectively. 'Fhese particles undergo aoZ~ tol rc-1o1 a tioii to form chain like structure upon ageing. l:i.cshly prepared optimized silver nanoparticles show an absorption peak around 399 1101 which red shifted upon ageing to 409 nm along with the appearance of a new peak at 263 nm, indicating a change in there morphology as arrived by electron microscopic studies. These nanosiructures exhibit interesting fluorescing behaviour, depending upon the excitation energy. Under 450 nm excitation, emission was observed to have various characteristic bands at 468. 494, 511, 530 and 563 nm respectively. Ag-PVP nanochains were tested for antibacterial activity against E.coli and S. aureus. l'hesc particles were found to inhibit the growth of' S. aureus at 6 ig/gL. As synthesized, silver nanostructures may find applications in the field of optoelectronics, biosensing and b iotec hn o logy 2013-06-01T00:00:00Z