Nanoscience and Nanotechnolgy

Present work explored a room temperature, simple and low cost chemical route for the preparation of hydrophilic cobalt oxide films from alkaline cobalt chloride (CoCl 2 :6H 2 O) and double distilled water precursor solutions. As-deposited cobalt oxide films showed amorphous nature, which is one of the prime requirements for supercapacitor, as confirmed from X-ray diffraction studies. Changes in direct band gap energy and electrical resistivity of as-deposited cobalt oxide films were confirmed after annealing. Spherical grains of about 40-50 nm diameters were uniformly distributed over the substrate surface. Surface wettability studied in contact with liquid interface, showed hydrophilic nature as water contact angle was <908. Finally, presence of cobalt-oxygen covalent bond was observed from Raman shift experiment.

The goal of this project is to develop and utilize a microfluidic device to isolate and enrich tumor cells circulating in peripheral blood. Circulating tumor cells (CTCs) have been used as biomarkers for cancer diagnostics and prognosis. However, the rarity of these cells (roughly 1 in a billion) poses a technological challenge to sort and concentrate them. CTCs hold potential sources for early detection, characterization, monitoring of cancers, and development of personalized treatment. The project is currently funded by the US National Cancer Institute (NCI) of the National Institutes of Health (NIH).

In this work, we report the fabrication of sub-10 nm wide, doubly-clamped silicon carbon nitride (SiCN) resonators of up to 5 μm lengths. An existing resonator fabrication process has undergone a major improvement through the use of a single hydrogen silsesquioxane (HSQ) masking layer for SiCN patterned using electron beam lithography. Novel development strategies, comprising hot development and HF-trimming development, were also used. The crucial role of post-exposure resist processing in improving the resonator resolution and uniformity was demonstrated. Application of the optimized lithographic process has allowed us to claim the narrowest suspended bridge structures of several microns in length achieved to date.

In this study, the thin films that consist of Zinc Oxide (ZnO:F) with and without addition of Flor (F) at rates of 1%, 2% and 3% (at%) was grown on glass and p-Si with chemical spraying method. Au (Gold) and Al (Aluminum) contacts were made by thermal evaporation method for electrical measurements and Au/ZnO:F/p-Si/Al devices were fabricated according to the amount of F contain. The ideality factor (n) and barrier height (Φ) and series resistance (Rs) were calculated using current - voltage (I - V) measurements. Cheung method was used to calculate these main diode parameters. Measurements were repeated in dark and light conditions according doping rate. In the measurements made in the dark, the ideality factor (n) was found to be 2,94 and F additive ratio decreased by 2,78. In the measurements made in the light, this value decreased to 2,73. The measurements made in the dark and in the bright environment showed a photovoltaic effect on the devices when compared in the ln (I) vs.V graph. Some structural parameters were calculated by XRD analysis and it was determined that the films had hexagonal wurtzite crystal structure. AFM and SEM analyzes were used to obtain information about surface morphology of the films. With optical measurements, the band gap of ZnO thin films was found to be between 3,28 and 3,24 eV.

The Nano contrast medium of Iodine solution was used in computed tomography scanning (CT-Scan) to test the enhancement of the rabbit heart. The aim of this research is to see how well Nano iodine solution works as a contrast medium in CT scans. Iodine nanoparticles were tested on laboratory animals (rabbits) with the heart as the organ of choice to determine the influence of the Nano contrast medium.The heart was chosen to research the Nano iodine contrast media, and the findings were promising in terms of the use of nanoparticles in the field of CT-Scan imaging diagnosis. It was discovered that injecting the rabbit with iodine nanoparticles improved the rabbit's cardiac imaging by increasing the value of the Hounsfield (HU). As a result, using iodine nanoparticles solution as a safe contrast medium in a CT-scan with high resolution of the organ's image is recommended. The anti-oxidative activity of Iodine NPs in blood medium was discovered electrochemically, with only a reduction current peak appearing in the cyclic voltammogram.

Cadmium sulphide/poly(vinyl alcohol) (CdS/PVA) nanocomposite films with different concentrations of Cd2+ ions have been prepared using various -ray irradiation doses over the range of 10 to 200 kGy. The prepared nanocomposite films were characterized by ultraviolet-visible (UV-VIS) absorption spectroscopy. The UV-VIS absorption spectra revealed that the CdS/PVA films showed blue shift for the absorption peak as compared with bulk CdS indicating the formation of CdS/PVA nanocomposites. As the irradiation dose increases, a gradual red shift in the wavelength accompanying with the broadening of the absorption peak was observed. The formation of CdS nanoparticles gradually grows in PVA matrix with wider size distribution as a result of increasing irradiation dose. The prepared CdS nanocomposite films exhibit a blue shift with decreasing Cd+2:S2- molar ratio. On the other hand, a gradual blue shift was observed with increasing PVA content. The estimated optical band gap energies and the calculated CdS particle sizes of the CdS/PVA nanocomposites show corre-lation between their values and the variable parameters (irradiation dose, Cd+2:S2- molar ratio and PVA content). Transmis-sion electron microscope images illustrated that the obtained CdS/PVA nanostructures were found to be dispersed as spher-ical nanoparticles with good structural homogeneity at either lower concentration of CdCl2 or irradiation dose. Nanorod structure of CdS accompanied with small agglomeration appeared in the prepared nanocomposites at either higher CdCl2 concentration or higher irradiation dose.

Mixed culture electrochemically active biofilms (EABs) were developed on carbon paper using a sludge with mixed culture bacteria for microscopic and spectroelectrochemical studies because a naturally mixed culture bacterial strain is more applicable than a pure culture strain. EAB development was confirmed by microbial fuel cells (MFCs) by obtaining a constant increase in potential (∼0.36 V). Microscopic and spectroscopic studies showed that a mixed culture EABs formed on the support. Cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS), which are nondestructive voltammetry techniques, indicated that the EABs could be source of electrons and used effectively for various purposes. Routine in vivo analysis of electron transfer between bacterial cells and the electrode was performed, providing insight into the extracellular electron transfer (EET) to the electrode. At low scan rates, CV revealed the catalytic electron transfer ability of EAB between the cells and electrode and showed exceptional redox activities in the presence of acetate. DPV and EIS studies showed that EAB in the presence of acetate can charge the surface by producing and storing sufficient electrons, behave as a capacitor, and have features consistent with EET. Finally, microscopic and spectroelectrochemical studies confirmed the development of a mixed culture EAB and the EET kinetics of EABs. These studies suggest that mixed culture EABs can be used effectively as a biogenic reducing tool for various applications.

CoFe 2 O 4 nanomaterials have been synthesized through conventional sol-gel process by using CoCl 2 .6H 2 O and FeCl 3 as precursors and citric acid is used as a capping agent. The as synthesized nanomaterials have been investigated thoroughly using x-ray diffraction (XRD) technique, scanning electron microscopy (SEM) and an impedance analyzer. The XRD patterns indicate the formation of body centered cubic spinel CoFe 2 O 4 having cell constant 8.403 Å and the corresponding space group is Fd-3m, in which the Fe 3+ and Co 2+ ions occupied in octahedral and tetrahedral sites in the crystallographic orientations. The average crystallite size was found to be 30 nm. The SEM micrographs reveal that the synthesized nanomaterials (NMs) formed as octahedron and tetrahedron and the particles are well dispersed and contain some pores. We found 17.5% porosity of the nanomaterials that plays an important role in technological applications, e.g. water and chemical filtration related to bio-medical applications. Measurement of the AC electrical properties shows that dielectric constant increases up to 5.13 for 0.3 MHz and then it decreases with increasing applied frequency. Lower dielectric constant at high frequency region appears due to decreasing interfacial polarization and limiting grain boundary effect.

In this present work, pervoskite nanocubes of Na0. 5K0.5NbO3 ceramic have been synthesized by new method were investigated by nanoindentation with a Berkovich indenter. The development of lead free ceramics has been one of the most important issue to current researchers. Among the studied lead free ceramics, sodium potassium niobate Na0.5K0.5NbO3, alkali niobate based ceramic has been found to be the most promising candidate because of its piezoelectric, as well as good electrical properties. Much attention should be focused to the study of surface nanomechanical properties of such materials, because the success of many applications is partly determined by a precise understanding of these characteristics. Therefore, determination of the surface and mechanical properties of Na0.5K0.5NbO3 ceramic material becomes more important. Among conventional methods used for mechanical characterization, such as the bulge test and microbeam techniques, nanoindentation methods have gained widespread use because of the ease of sample preparation and the inherently simple estimation of hardness, stiffness, elasticity, etc. Nanoindentation has been established as a quantitative tool for the characterization of mechanical properties of materials on the nanoscale. Therefore, the nanoindentation test has been carried out to measure displacement produced in the sample in response to the force applied at different locations on the Na0. 5K0.5NbO3 surface using nanoindentation set up. We have conducted nanoindentation based fatigue analysis on Na0. 5K0.5NbO3 Pelletes sintered at 1000 o C for multiple cycles of load and the results are discussed in the manuscript.