The fabrication and characterization of boron-doped diamond microelectrodes for use in electrochemical detection coupled with capillary electrophoresis (CE-EC) is discussed. They exhibited low and stable background currents and sigmoidally shaped voltammetric curves for cysteine, cystine and Fe(CN)63-/4- . Evaluation of the CE-EC system and the electrode performance were accomplished using a 10 mM borate buffer, pH 8.8, run buffer, and a 70-cm-long fused-silica capillary (10-mm i.d.) with seven sulfur-containing amino acids (methionine, cysteine, cystine, homocysyeine, homocystine, glutathionine, glutathionine disulfide) as test analytes. Reproducible separation (elution time) and detection (peak current) of seven sulfur-containing amino acids were observed with response precisions of 5% or less.

Thesis (M.S.P.H.)--University of Michigan, 1941.

Thesis (M.S.P.H.)--University of Michigan, 1941.

Diss. (sammanfattning) Göteborg : Göteborgs universitet, 2010. / Härtill 3 uppsatser.

Dissertation (PhD)--University of Stellenbosch, 2007. / Bibliography. Also available via the Internet.

Abstract Liquid containing tanks (LCTs) are used in water distribution systems and in the industry for storing water, toxic and flammable liquids and are expected to be functional after severe earthquakes. The failure of a large tank during seismic excitation has implications far beyond the economic value of the tanks and their contents. Then seismic design becomes a high necessity for this type of structure. However, tanks differ from buildings in two ways: first, during seismic excitation, the liquid inside the tank exerts a hydrodynamic force on tank walls, base, and roof in addition to the hydrostatic forces. Second, LCTs are generally required to remain watertight. Many current standards and guidelines such as ACI 350.3-06, ACI 371R-08, ASCE7, API650, EUROCODE8 and NZSEE 1986 code, cover seismic designs which are based primarily on theoretical analysis. This analysis is still not enough to fully describe the behavior of this structure under seismic oscillation noting that the theoretical analysis is based on a linear model and two dimensional spaces. So the focus of this study is to measure two important dynamic parameters which are the natural period and the maximum sloshing height of the water under harmonic motion by conducting an experimental investigation and computational fluid dynamic (CFD) simulation. Open-foam is the numerical tool chosen in this study. There is currently no study done with this tool to measure the behavior of the water inside a square tank neither under seismic motion nor harmonic oscillation.Finally, a comparison between the experimental, the analytical and the numerical results will be presented to confirm the level of validity of each method. Then a conclusion is made to summarize this research and to propose future works.

Most pharmaceutically relevant proteins and many extracellular proteins contain disulfide bonds. Formation of the correct disulfide bonds is essential for stability in almost all cases. Disulfide containing proteins can be rapidly and inexpensively overexpressed in bacteria. However, the overexpressed proteins usually form aggregates inside the bacteria, called inclusion bodies, which contains inactive and non-native protein. To obtain native protein, inclusion bodies need to be isolated and resolubilized, and then the resulting protein refolded in vitro. In vitro protein folding is aided by the addition of a redox buffer, which is composed of a small molecule disulfide and/or a small molecule thiol. The most commonly used redox buffer contains reduced and oxidized glutathione. Recently, aliphatic dithiols and aromatic monothiols have been employed as redox buffers. Aliphatic dithiols improved the yield of native protein as compared to the aliphatic thiol, glutathione. Dithiols mimic the in vivo protein folding catalyst, protein disulfide isomerase, which has two thiols per active site. Furthermore, aromatic monothiols increased the folding rate and yield of lysozyme and RNase A relative to glutathione. By combining the beneficial properties of aliphatic dithiols and aromatic monothiols, aromatic dithiols were designed and were expected to increase in vitro protein folding rates and yields. Aromatic monothiols (1-4) and their corresponding disulfides (5-8), two series of ortho- and para-substituted ethylene glycol dithiols (9-15), and a series of aromatic quaternary ammonium salt dithiols (16-17) were synthesized on a multigram scale. Monothiols and disulfides (1-8) were utilized to fold lysozyme and bovine pancreatic trypsin inhibitor. Dithiols (11-17) were tested for their ability to fold lysozyme. At pH 7.0 and pH 8.0, and high protein concentration (1 mg/mL), aromatic dithiols (16, 17) and a monothiol (3) significantly enhanced the in vitro folding rate and yield of lysozyme relative to the aliphatic thiol, glutathione. Additionally, aromatic dithiols (16, 17) significantly enhance the folding yield as compared to the corresponding aromatic monothiol (3). Thus, the folding rate and yield enhancements achieved in in vitro protein folding at high protein concentration will decrease the volume of renaturation solution required for large scale processes and consequently reduce processing time and cost.

No description available.

In sea urchin development, cell fate specification appears by the 60-cell stage embryo when several embryonic territories are recognized: the small micromeres, the large micromeres which will generate primary mesenchyme cells, the vegetal2 layer that will give rise to pigment cells, immunocytes, and muscle cells, the vegetal1 layer, as well as the oral and aboral ectoderm. A Delta-Notch signaling event is required for the differential specification of mesodermal cells that will give rise to secondary mesenchyme cells (SMCs). SMCs produce four cell types: pigment cells, blastocoelar cells, circumesophageal muscle cells, and coelomic pouch cells. Pigment cells are the first to be specified. During primary invagination at the gastrula stage, eight pigment cell progenitors delaminate from the archenteron into the blastocoel. By the pluteus stage, approximately 30 pigment cells are embedded in the ectoderm. Pigment cells produce echinochrome, a napthoquinone pigment. Previously, several genes in the sea urchin embryo were isolated that are expressed specifically in pigment cell precursors during the blastula stage. The goal of this research was to characterize a subset of these genes, which are highly similar to: the polyketide synthase gene (Pks), a sulfotransferase gene (Sult), three different members of the flavin-containing monooxygenase gene family (Fmo), and the transcription factor glial cells missing (Gcm). Polyketide synthases (PKSs) are a large family of multifunctional proteins mainly found in bacteria, fungi, and plants. They are responsible for the biosynthesis of a variety of polyketide compounds including antibiotics and mycotoxins. In the sea urchin, SpPks is required for echinochrome biosynthesis. Flavin-containing monooxygenases (FMOs) are NADPH-dependent flavoproteins mainly found in bacteria, plants, and higher metazoan. They are responsible for catalyzing the oxidation of several compounds including the detoxification of xenobiotics and activation of numerous metabolites. It is known that SpFmo1 is required for echinochrome biosynthesis. Sulfotransferases are found from bacteria through higher eukaryotes. These enzymes catalyze the sulfate conjugation of several substrates resulting in either compound detoxification or bioactivation.

<p> Recent investigations by H. G. Thode, J. Macnamara and C. Collins have shown that the S^32/S^34 ratio in natural sulfur-containing compounds varies by as much as five percent. These wide-spread variations suggest that fractionation of the sulfur isotopes occurs in natural processes due to differences in the chemical properties of isotopic molecules. In order to determine the magnitude of the effects that could be expected, partition function ratios for isotopic molecules containing sulfur and equilibrium constants for many isotopic exchange reactions involving sulfur have been calculated by methods of statistical mechanics. The results of these calculations are discussed. </p> / Thesis / Master of Science (MSc)