Pineapple juice of low acid content was prepared by removal of acids by using weakly basic anion exchange resin, IRA-93. The changes in the contents of titratable acid, pH and total soluble solids of model solutions that contained the principal constituents of pineapple juice (citric acid, citrate salt and sucrose) were investigated. The adsorption of individual acids and changes in composition of juice after a de-acidification process were explored. The adsorbed acids were recovered as solutions by some eluants, and studies on colour development in the recovered solutions carried out. The solutions of adsorbed acids recovered by NaOH from the resin, which had been treated by model solutions, were brown in colour. The brown colour was also found immediately when NaOH was added to the resin treated with pineapple juice but it was not found in the treated juice during acid removal treatment when its pH rose to 10. A greater amount of the dark colour was observed in the desorbed solution from the resin that had been treated with pineapple juice. The use of sulphuric acid, sodium chloride, sodium sulphate, sodium bicarbonate and phosphate buffer solution to desorb the acids from pineapple juice-treated resins reduced the intensity of the colour, measured at pH 3.5, of desorbed acid solutions. The colours of the desorbed solutions were pH dependent. Either solution of sulphuric acid or sodium chloride has a comparable desorbing power to a solution of sodium hydroxide whereas the rest has a lower desorbing power / Master of Science (Hons) (Food Science)

Monocytes/macrophages play very important roles in innate and adaptive immunity. Ion channels are small molecules embedded in the cell membrane and they play fundamental roles in cell function. Both topics have been extensively studied in isolation, however the role of ion channels in macrophage function is far less understood. In this thesis, the functional and molecular aspects of two ion channels expressed in macrophages, Kor, a potassium channel, and CLIC1, a chloride channel were studied. The biological function of Kor and CLIC1 in activated human macrophages was examined using ion channel blockers. In addition, the role of CLIC1 in the cell cycling of CHO-K1 cells was also investigated. The in vitro studies showed that Kor and CLIC1 are involved in cytokine production by PMA-activated human macrophages and that CLIC1 is also involved in the cell cycling of CHO-K1 cells. Despite providing interesting data, the results of the in vitro studies were difficult to interpret due to the uncertain specificities of the Cl- channel blockers. Therefore, to understand the biological role of CLIC1 in vivo, a gene targeting experiment was performed to create a CLIC1 knock-out (KO) mouse. This involved cloning the mouse CLIC1 gene, making a targeting vector, producing targeted ES cells, and generating a CLIC1 knock-in (KI) mouse which carries a flag tag at the N-terminal and three loxP sites in the targeted locus. Crossing the CLIC1 KI mouse with the TNAP-Cre mouse, a strain over expressing Cre recombinase under a TNAP promoter, a CLIC1 KO mouse was generated. The initial phenotype analysis showed no major development or growth abnormality in the CLIC1 KO mouse. Instead, hyperplasia of megakaryocytes and possible erythroid cells in the spleen and bone marrow was observed suggesting some degree of abnormality in the haematopoeitic system. Furthermore, a comparison of wild type mice with the CLIC1 KO mouse showed that CLIC1 protein expresses at high levels in monocytes, lymphocytes, platelets, and tissue macrophages of normal animals tissues, such as spleen, kidney (mesangial cell), and liver (kupffer cells). This further indicates that CLIC1 may play a significant role in regulating functions of platelets, lymphocytes, and specially tissue macrophages. More extensive studies can now be performed on the CLIC1 KO mouse to clarify the biological function of CLIC1. In summary, the generation of the CLIC1 KO mouse provides a valuable model to study the biological function of CLIC1 both in vivo and in vitro.

Graduation date: 1998

Thesis (Ph. D.)--Oregon Graduate Center, 1976.

Ph.D. / Applied Physics / This work was undertaken to determine the feasibility of using a field ionization (FI) source to produce fine focus ion beams. Operating parameters for a FI source have been measured and a source sensitivity of ~ 5 x 10[superscript-5] A sr[superscript -1] torr[superscript -1] was found for both H[subscript 2] and Ar at 77 K. The source is gas phase, differentially pumped with typical operating pressures of 1 - 30 x 10[superscript -3] torr at 77 K, resulting in a maximum source brightness ≈ 10[superscript 8] A cm[superscript -2] sr[superscript -1] and angular intensity of ≈ 10[superscript -6] A sr[superscript -1] with beam energies of 10 - 20 keV. Angular distributions were measured and found to be uniform near θ = 0°, with the beam confined to ±20°. A scanning ion microscope (SIM) was built to further evaluate the source. The SIM has been operated with currents on the specimen of 10[superscript -11] – 10[superscript -10 amperes in the secondary electron mode with contrast provided primarily by the sec (θ) dependence of the secondary electron yield, where θ is the angle between the beam and the specimen normal. Secondary electrons are detected and amplified with a channeltron multiplier and images generated as with a conventional SEM. All electrostatic optics are used in a doublet arrangement, and with this configuration current is independent of working distance which is 3 - 4 cm. A current of 5 x 10[superscript -11] A was focused into a spot of ≈ 6500 Å with H[subscript 2] gas, the resolution being limited by chromatic aberration caused by the ≈ 4 eV energy spread of the two component (H[superscript +] H[superscript +, subscript 2]) beam. Signal to noise ratio measurements on the source made at the specimen position show that the bulk of the noise power spectrum falls below f = 30 Hz.

The divalent Ca2+ metal ion acts as a universal second messenger in virtually all eukaryotic cells from fungi to plants to mammals. In mammals, Ca2+ signaling is vital to a variety of physiological processes including fertilization, cell proliferation, secretion, and muscular contraction. In electrochemically non-excitable tissues, the release of Ca2+ from intracellular stores such as the endoplasmic reticulum is tightly regulated by the inositol 1,4,5-trisphosphate receptor (IP3R). The IP3R Ca2+ release channel is activated by the binding of the small molecule inositol 1,4,5-trisphosphate (IP3) in response to extracellular stimuli such as hormones, growth factors, and neurotransmitters. The conformational changes accompanying IP3 binding were investigated using a biophysical approach. A specific focus of this work is to decipher how signals of ligand binding are transmitted from the N-terminal IP3-binding core to the C-terminal channel domain. To such end, biophysical studies of the ligand-induced conformational changes within the N-terminal domain of IP3R (a.a. 1 – 604) were performed. The results implicated the presence of two flexible linkers which join stably folded domains. This prompted the proposal of a model in which an equilibrium mixture of conformational substrates containing compact and more extended structures co-exist. Determinants within the N- and C-terminal regions of IP3R have previously been reported to be critical to channel function. Employing nuclear magnetic resonance (NMR) as well as biochemical methods, an intermolecular interaction between the S4-S5 linker, the cytoplasmic loop between the fourth and fifth transmembrane helices of IP3R, and the suppressor domain was identified. The determination of the crystal structure of the suppressor domain from isoform type 3 IP3R (IP3R3SUP) allowed us to map the residues involved in this interaction to one face of the molecule. The characterization of this interaction provides insight into the N- and C-terminal determinants essential to the IP3R channel gating mechanism.

The divalent Ca2+ metal ion acts as a universal second messenger in virtually all eukaryotic cells from fungi to plants to mammals. In mammals, Ca2+ signaling is vital to a variety of physiological processes including fertilization, cell proliferation, secretion, and muscular contraction. In electrochemically non-excitable tissues, the release of Ca2+ from intracellular stores such as the endoplasmic reticulum is tightly regulated by the inositol 1,4,5-trisphosphate receptor (IP3R). The IP3R Ca2+ release channel is activated by the binding of the small molecule inositol 1,4,5-trisphosphate (IP3) in response to extracellular stimuli such as hormones, growth factors, and neurotransmitters. The conformational changes accompanying IP3 binding were investigated using a biophysical approach. A specific focus of this work is to decipher how signals of ligand binding are transmitted from the N-terminal IP3-binding core to the C-terminal channel domain. To such end, biophysical studies of the ligand-induced conformational changes within the N-terminal domain of IP3R (a.a. 1 – 604) were performed. The results implicated the presence of two flexible linkers which join stably folded domains. This prompted the proposal of a model in which an equilibrium mixture of conformational substrates containing compact and more extended structures co-exist. Determinants within the N- and C-terminal regions of IP3R have previously been reported to be critical to channel function. Employing nuclear magnetic resonance (NMR) as well as biochemical methods, an intermolecular interaction between the S4-S5 linker, the cytoplasmic loop between the fourth and fifth transmembrane helices of IP3R, and the suppressor domain was identified. The determination of the crystal structure of the suppressor domain from isoform type 3 IP3R (IP3R3SUP) allowed us to map the residues involved in this interaction to one face of the molecule. The characterization of this interaction provides insight into the N- and C-terminal determinants essential to the IP3R channel gating mechanism.

High energy neutron and proton radiation can induce serious damage in structural metals, including void swelling and embrittlement. Hence the design of advanced metallic materials with significantly enhanced radiation tolerance is critical for the application of advanced nuclear energy systems. The goals of this dissertation are to examine the fundamental physical mechanisms that determine the responses of certain metallic multilayers, with ultra-high density interface structures, to plastic deformation and high fluence He ion irradiation conditions. This dissertation focuses on the investigation of mechanical and radiation responses of Al/Nb and Fe/W multilayers. Radiation induced microstructural evolution in Cu and Cu/Mo multilayer films are briefly investigated for comparisons. Al/Nb multilayer films were synthesized by magnetron sputtering at room temperature. The interface is of Kurdjumov-Sachs orientation relationship. In situ nanoindentation inside a transmission electron microscope (TEM) reveal that interfaces act as strong barriers for dislocation transmission and dislocations climb along the Al/Nb interfaces at a much higher velocity than in bulk. The evolution of microstructure and mechanical properties of Al/Nb multilayers has been investigated after helium ion irradiations: 100 keV He+ ions with a dose of 6x10^16/cm2. When layer thickness, h, is greater than 25 nm, hardness barely changes, whereas radiation hardening is more significant at smaller h. This study shows that miscible fcc/bcc interface with large positive heat of mixing is not stable during ion irradiation. In parallel we investigate sputtered Fe/W multilayers. Film hardness increases with decreasing h, and approaches a maximum of 12.5 GPa when h = 1 nm. After radiation, radiation hardening is observed in specimens when h >/= 5 nm, however, hardness barely changes in irradiated Fe/W 1 nm specimens due to intermixing. In comparison, Cu/Mo 5 nm multilayers with immiscible interface has also been investigated after helium ion irradiations. Interfaces exhibit significantly higher helium solubility than bulk. He/vacancy ratio affects the formation and distribution of He bubbles. The greater diameter of He bubbles in Cu than Mo originates from the ease of bubble growth in Cu via punching of interstitial loops. Finally, helium bubble migration and growth mechanisms were investigated in irradiated Cu (100) single crystal films via in situ heating inside a TEM. The activation energy for bubble growth is ~ 0.02 eV at low temperature. At higher temperatures, the activation energy for bubble coalescence is ~ 0.22 eV inside crystal, and 0.34 eV close to surface. The migration mechanisms of helium bubbles involve continuous as well as Brownian movement.

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Surfaces can be probed with a variant of secondary ion mass spectrometry (SIMS) where the bombardment is with a sequence of single keV projectiles, each resolved in time and space, coupled with the separate record of the secondary ions (SIs) ejected from each projectile impact. The goal of this study was to demonstrate an efficient mode of SIMS where one obtains valid analytical information with a minimum of projectiles and hence a minimum of sample consumption. An inspection of the ejected SIs from individual bombardment events will reveal ??super efficient?? collision cascades i.e., events, where two or more secondary ions were emitted simultaneously. It has been shown that these coincidental emissions can provide information about the chemical composition of nano-domains. Previous studies using coincidence counting mass spectrometry (CCMS) indicated an enhancement of identifying correlations between SIs which share a common origin. This variant of SIMS requires an individual projectile impact thus causing SI emission from a surface area of ~5 nm in radius. Thus, in an event where two or moreSIs are ejected from a single projectile impact, they must originate from atoms and molecules co-located within the same nano-domain. Au nanorods covered by a 16-mercaptohexadecanoic acid (MHDA) monolayer were analyzed using this methodology. A coincidence ion mass spectrum was obtained for the MHDA monolayer covered Au nanorods which yielded a peak for a Au adduct. Similar results were obtained for a sample with a MHDA monolayer on a Au coated Si wafer. A series of samples consisting of Cu aggregates and AuCu alloys were investigated by SIMS to demonstrate that this technique is appropriate for characterizing nanoparticles. The mass spectra of these samples indicated that Au200 4+ is an effective projectile to investigate the surface of the target because it was able to penetrate through the poly(vinylpyrrolidone) (PVP) stabilizer that coated the surface of these nanoparticles. Coincidence mass spectra of the Cu aggregates yielded molecules colocated within the same nano-domain. Finally, this methodology was used to investigate surface structural effects on the occurrence of ??super-efficient?? events. The results indicated that it is possible to distinguish between two phases of ??-ZrP compounds although the stoichiometry remains the same.