This thesis is a research conducted to find out if the specific absorption rate (SAR), imposed on the human head from cellular phones, can be reduced without having an significant impact on the overall performance and reception of the phone. The SAR values are influenced by various different variables like, type and size of the antenna, position of the antenna relative to human head, radiated power from the antenna, distance and angle from human head and finally the material covering the phone. The methodologies that will be used are to investigate three different approaches to SAR reduction. First approach is to investigate if the size and type of the material shielding the human head have significant impact on the SAR radiation, second approach is to investigate if the angle of the phone in relation to human head have significant impact and as the third approach is to investigate if it is possible to change the composition of the material which would ultimately lead to SAR reduction. Electric properties of the material are described by two variables conductivity and permittivity, and in the third part of the thesis I will change these two variables and then investigate how the SAR values change. Result will be presented as a 3D graph and it will directly present how SAR values relate to the material used as a phone casing. The distance and antenna variations will not be investigated. The distance values will be fixed to 2.5 cm from the human head and the antenna length will be quarter of the 900 MHz wave length. The investigations will be performed in a simulation program called FEMLAB and the results will be showed in text and figures.

No description available.

Elemental carbon reduces Fe3+ to Fe2+ in aqueous solutions. This process has potential implications in the adverse health effects of fine particles in air pollution, because both elemental carbon and iron are major components in atmospheric particulate matter. In this study we measured the time-dependent release of iron from laboratory flames and standard reference soot particles that contained iron, and the reduction of Fe3+ to Fe2+ in an acid extraction process. The concentration of Fe3+ and Fe2+ ions in the extraction solutions was measured by a spectrophotometric method. The results showed that while Fe3+ was the dominant valence state in the dry soot particles, significant fraction of iron was reduced to Fe2+ in the aqueous solution. Further investigation is needed to assess the significance of this phenomenon in the biological effects of particles that contain iron and elemental carbon.

No description available.

Thesis (M.S.)--Youngstown State University, 1997. / Includes bibliographical references (leaves 51-52).

Thesis (Ph. D.)--Columbia University, 1932. / Vita.

Thesis (M.S.)--Virginia Polytechnic Institute, 1935. / Includes bibliographical references (leaves 64-66). Also available via the Internet.

Thesis (M.S.)--University of Wisconsin--Madison, 1981. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 107-108).

The kinetics of the carbon monoxide reduction of silver perchlorate in sodium acetate - acetic acid buffered aqueous solution were studied between 60 and 110°C by following the pressure decrease in a closed system. The reduction occurs homogeneously in the liquid phase by two parallel reaction paths, one of which is independent of pH. The second path is favoured by increased pH and has both an acetate-independent and an acetate-dependent component. The observed kinetics are consistent with the formation of intermediate complexes by the insertion of a carbon monoxide molecule between a silver ion and a co-ordinated oxygen-donating base (e.g. OAc[superscript -], H₂O) according to the following mechanism: [Chemical formulae omitted] Silver-acetate complexes are about a factor of three more reactive than hydrated silver ions in the pH-dependent reaction. This enhanced reactivity is attributed to stabilization by the basic acetate anion of the proton released in the reduction process. The effect of increased pH on the reduction rate is much greater than the specific effects associated with silver-acetate complexing. / Applied Science, Faculty of / Materials Engineering, Department of / Graduate

The kinetics of the reduction of silver amine complexes in aqueous solution by carbon monoxide were investigated. For a number of amines including ethyl-, methyl-, diethyl- ethanol-, diethanolamine and some primary diamines, the rate law was found to be of the form: [formula omitted] (1) where L denotes the amine. These kinetics were interpreted in terms of the following mechanism. AgL₂⁺ + H₂O ⇌ L-Ag-OH + LH⁺ (Rapid) (2) L-Ag-OH + CO [symbol omitted] L-Ag-COOH (Rate-determining) (3) L-Ag-COOH + Ag(I) → Products (Rapid) (4) The rate constant of the rate-determining step (3) was found to be nearly independent of the nature of the amine molecule, L, coordinated to silver ion, using the basicity constants of the amines and dissociation constants of the corresponding silver amine complexes. The actual overall rate of the reaction varied with the nature of amine but this was attributable only to the different equilibrium concentrations of L-Ag-OH. The rate of this rate-determining bimolecular process was found to be surprisingly fast; k₂₅。= 5x10² mole ⁻¹. sec.⁻¹, ΔH*~ 9 Kcal. mole⁻¹ and ΔS*~ -15 e.u. The reduction of silver ion by CO in acidic or neutral media is known to be very slow and this can now be attributed to the base catalyzed nature of the reaction. Silver complexes of primary diamines (ethylenediamine, 1,3-diaminopropane, etc.) were reduced more slowly; this was attributed to the stabilization of mono-complexed silver (I) species by chelate formation. In the case of ammonia normal kinetics were observed at higher pH but at Lower pH the rate became second order in (Ag(I))and inversely second order in (NH₄⁺). This was attributed to competition between decomposition of the intermediate complex and its further reaction with another Ag(I) species to give metallic silver and carbon dioxide. Evidence for similar competition was found with two tertiary amines, i.e., triethylamine and triethanolamine. / Science, Faculty of / Chemistry, Department of / Graduate