<p> The standard technique of ellipsometry allows the determination of the optical constants of a substrate material provided either the surface is free of an oxide film or the oxide film thickness and optical constants of this oxide film are known. The majority of ellipsometric measurements performed on materials known to grow natural oxides is done by removing the natural oxide (either by cleaving or etching) and performing the measurements at one angle of incidence in vacuo. These processes perturb the surface and the reported values of optical constants may be questionable. </p> <p> The technique to be presented here assumes the material to be studied has a naturally-occurring oxide. Measurements are performed at several angles of incidence and the optical equations are solved for a self-consistent oxide film thickness until the best fit substrate optical constants have been found. The optical constants of the oxide film are then determined. </p> / Thesis / Master of Science (MSc)

No description available.

The observed constraints on the variability of the proton to electron mass ratio and the fine structure constant are used to establish constraints on the variability of the Quantum Chromodynamic Scale and a combination of the Higgs Vacuum Expectation Value and the Yukawa couplings. Further model dependent assumptions provide constraints on the Higgs VEV and the Yukawa couplings separately. A primary conclusion is that limits on the variability of dimensionless fundamental constants such as and provide important constraints on the parameter space of new physics and cosmologies.

Reliable measurements of the thermodynamics of the carbonate system are needed to better understand the CO2 system in natural waters. New measurements of the carbonic acid pK1* and pK2* in seawater have been made over a wide range of temperatures (1 to 50°C) and salinities. The commonly used CO2 constants of Mehrbach et al., (1973) were limited to salinities (19 to 43) and temperatures (2 to 35°C). They cannot be used to study estuarine or fresh waters. The results of these measured pK1* and pK2* values are in good agreement with those determined using the Miami Pitzer equations (Millero and Pierrot, 1998). The results in this dissertation can be demonstrates the validity of the model that can be used to study the carbonate system in most natural waters. The so called Miami model is presently being used to examine the effect of ocean acidification on natural waters. The boric acid effect on the dissociation constants in seawater and NaCl solutions was tested. The addition of boric acid has little or no effect on pK1* values. However, the values of pK2*, decreases with the addition of small amounts of boric acid to ASW in agreement with the work of Mojica-Prieto and Millero, (2002). The addition of larger concentrations of boric acid cause the values of pK2* to increase. These effects have been attributed to the interactions of boric acid with the carbonate ion (CO32-) in seawater (Mojica-Prieto and Millero, 2002). The addition of boric acid to NaCl solutions in contrast, caused the values of pK1* and pK2* to decrease. This has been attributed to the interactions of borate ions with Mg2+ and Ca2+ in seawater. Further measurements in Na-Mg-Cl and Na-Ca-Cl solutions are needed to prove that this is the case. The boric acid effect on the carbonate constants indicate that an increase in boric acid has no affect on pK1*, but does change the values of pK2*. At low concentrations of boric acid, pK*2 decreases, and at higher concentrations it increases. These results indicate that boric acid has some ionic interactions with the carbonate ion. Similar studies in NaCl indicate that both pK1* and pK2* decrease when boric acid is added. The differences between seawater and NaCl may be related to the interactions of Mg2+ and Ca2+ with borate anions. Further studies of NaCl with additions of MgCl2 and CaCl2 are needed to examine the effects in detail. Preliminary studies on the effect of DOC on the carbonate constants are not definitive. The change of the DOC concentration from 50 to 100 µmol kg-1 has little effect on the values of pK1* and pK2*. Dilutions of seawater with artificial seawater are complicated by changes in the concentration of boric acid. Earlier studies indicated that DOC may cause the 8 mu-mol kg-1 increase in total alkalinity of seawater needed to balance the thermodynamics of the system (Millero et al., 2002). This may be partially due to the new values for the B/Cl ratio in seawater found by Lee et al., (2010) that increases the TA by ~ 6 µmol kg-1. Further studies are needed to examine the effect of humic compounds in estuarine waters on the carbonate system. Measurements of pH or pCO2 along with TA and TCO2 can be used to separate the effect of organic ligands on TA. If DOC measurements are also made, one can relate the effect to organic ligands that can accept a proton. The cruises in the Little Bahama Banks show for the first time the active precipitation of CaCO3 (Bustos-Serrano et al., 2009). This causes measured decreases of TA, TCO2 and pH and increases in pCO2 in the whitings. This is in contrast to earlier studies on the Grand Bahama Banks where no active precipitation of CaCO3 was every found (Morse et al., 2003; Millero et al., 2005). The differences appear to be due to the movement of fresh saturated seawater from the Gulf Stream into the LBB. The Gulf Stream water enters the GBB in the winter, and the precipitation occurs on the suspended sediment over the year. Observations are needed on the Grand Bahama Banks in the winter and throughout the year to prove that this is the case.

No description available.

The acidities of 37 amino-substituted heterocyclic compounds have been determined using measurements of degree of ionization in DMSO/ water/0.011 M hydroxide ion and recently developed extrapolative procedures which are based on the Bunnett-Olseh (B.O.) and the Marziano-Cimino-Passerini (M.C.P.) methods. The compounds studied include 19 aminopyridines and pyrimidines and 18 derivatives of the biologically important nucleotide bases, cytosine, adenine and guanine. The UV/vis spectra of the neutral and anionic forms of the amino-pyridines and pyrimidines are well separated so that in evaluating the ionization ratios, changes of the spectra with medium composition were accounted for by measuring at the wavelength of maximum anionic absorption in each solution and by assuming that eA- and eHA vary linearly with HN . For the majority of the nucleotide derivatives, the neutral and anionic spectra were closely overlapping although different in shape. The ionization ratios were best evaluated by using the area under the spectral curve; spectral changes with solvent composition were accounted for by an adaptation of the method described above. Ionization ratios evaluated by the area method agreed well with those calculated by other methods as long as the anionic area was at least one and one-half times as great as the neutral area (or vice versa). The aminopyrimidines and purines define a new acidity function Hp . This function covers the range from water to 87.6 mole % DMSO and was established using 15 aminopyrimidines and purines. When Hp plotted against mole % DMSO, it rises less steeply than HN. This has been attributed to less extensive derealization of charge in the aminopyrimidine anion relative to that of an aniline (usually a nitroaniline) ionizing at the same solvent composition. The B.O. pKHA values of unsubstituted 2- and 4-aminopyridine, 2- and 4-aminopyrimidine and 2-amino-s-triazine, ranging from 23.50 to 14.91 are well-correlated by a Hammett plot using a values recently established for aza substituents and assuming the additivity of aza substituent effects, p. 4.99. The B.O. pKHA values of five substituted anilines, ranging from 25.50 to 23.13, fall close to this plot. All ten compounds are accommodated by a straight line, p value 5.10, which suggests that the aminoheterocycles may be considered to be aza-substituted anilines. It appears that the sensitivity of aniline and diphenylamine acidity to substituent effects is greater than previously believed. The findings in this work suggest that transmission of substituent effects through a heterocyclic and a benzene nucleus are equal and that an aza group may be regarded as a normal ring substituent. From the acidities of substituted aminopyridines and pyrimidines it appears that, to a first approximation, aza groups do not perturb the effects of other substituents on the same nucleus, although there may be a small resonance interaction between a +R group, such as chloro, and an aza group lying para to it. The same conclusion was reached from examination of the basicities of these compounds. / Science, Faculty of / Chemistry, Department of / Graduate

With a large number of carbon-carbon spin-spin coupling constants now determined and the dihedral angle dependence of vicinal coupling constants reported, application of this coupling constants data was attempted to a conformational study.

Due to the complexity of electro-elastic coupling characteristics in piezoelectric material, some of the elastic, dielectric and piezoelectric parameters are difficult to be measured. Usually, these parameters are determined by assuming that all offer parameters are remained constant during the measurement. However, the interactive effect between material properties makes this assumption be not always true. In this study, the measured natural frequencies of the specified circular piezoelectric plate are used to extract these parameters simultaneously. In other words, all these parameters are determined with considering the interactive electro-elastic coupling effect. The analytic model of free-free circular piezoceramic plate was derived and solved to establish the relationship between natural frequencies and its material parameters, to cover most all the parameters, the out-of-plane(non-symmetric transverse) and in-plane(symmetric extensional) modes are considered. The genetic algorithm is employed to determine most all elastic, dielectric and piezoelectric parameters from a least square error between the calculated and measured natural frequencies. Numerical results derived from the parameters proposed in this work reveal a good agreement with the measured data. In other words, the proposed method to extract the piezoelectric parameters is feasible and effective.

The correlation between the carbon-proton and proton-proton coupling constants have been studied in various 13 systems. Isocrotonic acid-carboxyl-3C, crotonic acid- 13 13 carboxyl-3C, and 5-norbornene-2-carboxylic acid-carboxyl-3C- 1,5,6,7,7-hexachloro were synthesized and their carbonproton coupling constants were analyzed. Nmr studies showed the magnitudes of the carbon-proton coupling constants to correlate well with analogous protonproton coupling constants, although the values of the couplings were larger than expected. The geminal olefinic couplings were considerably larger than all other couplings, but they were self-consistent. The signs of the carbon-proton coupling constants also were in agreement without exception with the signs of analogous proton-proton coupling constants.

<p>Studies of binding reactions are of highest importance in a vast number of areas of biomedicine and biotechnology. A demand for fast and accurate small-volume measurements grows stronger, partly due to the development of therapeutic antibodies. In this report, a novel method for studies of binding reactions of antibodies is described. The use of a microfluidic platform shows promising results in determination of affinity binding constants.</p><p>Affinities between 1E-09 and 1E-11 M have been determined for four TSH antibodies. Reproducibility tests give a CV below 10%, using different Gyrolab instruments and microfluidic CD:s. The method carries the advantages of using solution-based measurements of unmodified molecules. Also an initial proof-of-concept for measurement of binding reaction rate constants shows further usage of the method. The kinetic association rate constant has been determined to 2E+06 M-1s-1 for one antibody. The possibility of using this method for screening of antibody libraries is also discussed.</p>