No description available.

<p> A fluorometric method using lumogallion has been shown to be adequate to measure the degree and rate of complexation of aluminum at low concentrations, (1.85 xl0^-6 M), by other ligands such as fluoride and citrate, at a pH of 5.2.</p> <p> The species H2PO4 -, H4SiO4 and SO4 2- do not compete with lumogallion for aluminum at this pH for concentration ratios of less than 100, (competing ion: lumogallion). </p> <p> A rate law for the destruction of the lumogallion complex by fluoride ion has been determined as -r = (-dC/dt)A = ((4.3 x 10^3)[F^-1]^1.8 CA)/(1 - (1.0 x 10^3)[F^-1]^-0.7 CA) where CA is the corrected concentration of the fluorescent complex at any time.</p> <p> This method is proposed to measure aluminum complexes in natural waters.</p> / Thesis / Bachelor of Science (BSc)

Several commonly used concentration measures are defined and discussed. The Grossack Model of Permanent Industrial Concentration and its three concentration indices are explained. Monte Carlo Techniques are used to generate synthetic data which is then used to compute theoretical values of the Grossack Model Indices. Values of other commonly used concentration indices are computed for comparison purposed. The Grossack Model Indices are then subjected to a variety of statistical tests. The results of these tests are presented and evaluated and a conclusion is drawn.

In this thesis photoluminescence measurements were made on ZnS:Mn thin-films with different concentration of Mn in order to observe the phenomenon of concentration quenching. A mathematical model, based on migration of energy among Mn centres and subsequent transfer to traps, is proposed to explain it. Probability of energy transfer to traps is considered independent of Mn concentration. It is consistent with experimental evidence reported in literature. Using this model we can give physical interpretation to the empirical decay-law for luminescence of Mn centres n(t) =n(0)exp[ - (t/r)a ] , where j and a change with Mn concentration. We are able to quantify the probability of energy loss to traps using Dexter's equation for dipole-dipole transfer. It is suggested that energy loss to the traps can be influenced by growth technique. / Thesis / Master of Engineering (ME)

The study of mixing processes in supersonic flow has a great interest for a number of applications including scramjet developments. However, the usual tools employed are very limited. Sampling probes generally have a poor frequency response, and that makes measurements of fluctuating concentration problematic. The goal of this study is to design, build and test a probe capable of measuring concentration fluctuations of at least 1 kHz. This study shows the design of such a probe and how a high frequency response was achieved. A prototype was built and tested. The tests consist of a calibration phase and experiments inside a hypersonic wind tunnel. These last tests served two purposes. The first one was to verify that the measurements made with the probe gave the correct value of the concentration. The second purpose was to assess the frequency response of the probe by putting it through a concentration step change. Tests were conducted with various known mixtures of Helium and air from 0% to 100% flowing at Mach 2.0 with T_t=300 °K and P_t=4.4 atm. The probe proved capable of measuring concentration fluctuations up to approximately 2.5 kHz while also giving the adequate accuracy for values of mean concentration. / Master of Science

This thesis investigates the architecture of perceived boundaries, formed by architectural and phenomenological elements of concentration and dispersion. Inspiring this investigation was a site located on the property of the US National Arboretum in Washington, DC. This was the site of the historic United Brick Corporation, where the grass grows and the snow falls on the ruins of once-active brick kilns. This thesis investigation culminates in the design of a structure, which houses a now-active ceramic studio and facilities for viewing the brick kilns and interpreting the brick making process that once occurred on the site. In the past, select elements of nature -clay, water and fire- came together to make bricks. When the bricks were sent to their final destination, they were stacked to form a wall, which is a creation greater than the sum of its parts. Currently, elements of nature -soil, grass, trees, light and wind- come together to create the unique landscape surrounding the brick kilns; a landscape also much greater than the sum of its parts. Similarly, select elements -columns, beams, glass and bricks- come together to make Architecture, which again strives to be greater than the sum of its parts. However, it is only when these elements are considered uniquely, that the phenomenon of concentration and dispersion can be investigated. The intent of this thesis is to bring distinct elements together, forming the Architecture of Concentration and Dispersion. / Master of Architecture

Although advances in microfluidic technology have enabled increasingly sophisticated biosensing and bioassay operations to be performed at the microscale, many of these applications employ such small amounts of charged biomolecules (DNA, proteins, peptides) that they must first be pre-concentrated to a detectable level. Efficient strategies for precisely handling minute quantities of biomolecules in microchannel geometries are critically needed, however it has proven challenging to achieve simultaneous concentration, focusing, and metering capabilities with currentgeneration sample injection technology. Using microfluidic chips incorporating arrays of individually addressable microfabricated electrodes, we demonstrate that DNA can be sequentially concentrated, focused into a narrow zone, metered, and injected into an analysis channel. The technique used in this research transports charged biomolecules between active electrodes upon application of a small potential difference (1 V), and is capable of achieving orders of magnitude concentration increases within a small device footprint. The collected samples are highly focused, with sample zone size and shape defined solely by electrode geometry. In addition to achieving the objectives of the research project, this setup was found to provide added functionality as a label-free biomolecule detection technique due to the formation of light scattering phases of charged biomolecules on top of the capture electrode.

Diss.--Berlin--Techn. Univ., 1996. / Bibliogr. p. 329-338.

No description available.

Thesis (M.S.)--University of Michigan, 1968.