Three types of metallic nanostructures comprising niobium were investigated experimentally; in all three types, electric transport at very low temperatures was governed by Coulomb blockade effects. 1. Thin film strips of niobium could be tuned into resistor strips by an electrochemical anodisation process, using microfabricated masks and in situ resistance monitoring. These resistors showed a t...

Astronomical interest in observing phenomena within the terahertz frequency spectrum has driven demand for extremely sensitive heterodyne receivers. Traditionally, niobium-based SIS tunnel junctions are used by the radio astronomy community in such receivers for observations below 700GHz. Research on novel devices for heterodyne mixing aims to extend experimental capabilities of sensitive recei...

We report on the development of an enzyme-amplified sandwich-type immunosensor based on a thin gold film sputtered on an anodic nanoporous niobium oxide (Au@Nb(2)O(5)) electrode. The electrocatalytic activity of enzymatically amplified electroactive species and a stable electrode consisting of Au@Nb(2)O(5) were used to obtain a powerful signal amplification of the electrochemical immunobiosenso...

Neutral vanadium, niobium, and tantalum oxide clusters are studied by single photon ionization employing a 26.5 eV/photon soft x-ray laser. During the ionization process the metal oxide clusters are almost free of fragmentation. The most stable neutral clusters of vanadium, niobium, and tantalum oxides are of the general form (MO2)0,1(M2O5)y. M2O5 is identified as a basic building unit for thes...

In Brazil there are many regions where the extraction mining and processing of ores containing elements of great economical importance as tin, niobium and tantalum. Some of these ores have uranium and thorium natural decay series associated. This study was carried out in a niobium mine, where is obtained concentrates of niobates-tantalates, cassiterite and zirconite. The aim of this study is th...

Recent successes with superconducting Josephson junction qubits make them prime candidates for the implementation of quantum computing. This doctoral thesis details the study of a niobium Josephson junction circuit for quantum computing applications. The thesis covers two main areas: 1) the fabrication of sub-micron niobium Josephson junction devices using a Nb/Al/AlO./Nb trilayer process and 2...

Quinolines, an important class of potentially bioactive compounds, have been synthesized by treatment of O-aminoarylketones and carbonyl compounds utilizing niobium (V) chloride / polyethylenglycole(NbCl5.PEG) and niobium(V)chloride (NbCl5) as available and inexpensive catalysts. The quinoline derivatives were prepared in glycerol, an excellent solvent in terms of environmental impact, with hig...

Pure uo2 sinters readily at temperatures below 1600°c when non-stoichiometric oxygen introduced during the presintering treatment is available for diffusion and subsequent densification. In the absence of excess oxygen sintering occurs at temperatures above 1600°C by self-diffusion of stoichiometric oxygen in uo2 • Grain growth occurs when open porosity has been eliminated and is controlled by ...

Magnetization and susceptibility data are presented for niobium rod samples in the temperature range of 1.2 to 9.2’ K. The niobium samples tested had a range of tantalum content from 700 to 4000 ppm, and all other impurities were less than 200 ppm. The samples received were in a cold-worked condition. They successively were annealed and degassed in a controlled manner in high vacuum. The anneal...

Highly ordered N-doped mesoporous niobium oxide (NMNb) was prepared via a facile solid state reaction method using urea as a nitrogen source. The mesoporous structure of niobium oxide (MNb) is beneficial to the N dopant that is effectively incorporated into the lattice of MNb, resulting in a significantly enhanced visible light response. The hydrogen generation efficiency over the optimized N-d...