Raman spectroscopic measurements of various hydrogen bearing clathrate hydrates have been performed under high (< 1cm-1) and low resolution (>2 cm-1) conditions. Raman bands for hydrogen in most common clathrate hydrate cavities have been assigned. Unlike most clathrate hydrate guests, the general observation is no longer valid that the larger the clathrate cavity in which a guest resides, the lower the vibrational frequency. This is rationalized by the multiple hydrogen occupancies in larger clathrate cavities. Both the roton and vibron bands for hydrogen clathrates illuminate interesting quantum dynamics of the enclathrated hydrogen molecules. At 77K, the progression from ortho to para H2 occurs over a relatively slow time period (days). The para contribution to the roton region of the spectrum exhibits the triplet splitting also observed in solid para H2. The complex vibron region of the Raman spectrum has been interpreted by observing the change in population of these bands with temperature and with isotopic substitution by deuterium. Raman spectra from H2 and D2 hydrates suggest that the occupancy patterns between the two hydrates are analogous. The Raman measurements demonstrate that this is an effective and convenient method to determine the relative occupancy of hydrogen molecules in different clathrate cavities.

Cancer is the leading cause of death worldwide and one third of its burden can be decreased with early detection. Surface enhanced Raman spectroscopic (SERS) based imaging is a promising new technique for non-invasive detection of tumours due to its ultra-sensitivity and multiplexing capabilities. For in vivo SERS molecular imaging, a biocompatible, robust and targeted nanoparticle is required to attain high sensitivity and specificity. In this thesis, a SERS capable gold nanoparticle was rationally designed by encapsulation with a phospholipid bilayer which conferred biocompatibility, colloidal stability and versatility to changing surface chemistry. Moreover, validation of this SERS probe with a specific targeting ligand for carcinoma cells was studied through the targeting of a commonly overexpressed cancer receptor, epidermal growth factor receptor. Using this phospholipid design, optimizations with differing chemistries, targeting ligand or modifications for additional functionalities can be achieved for further development as a viable in vivo molecular imaging tool.

Cancer is the leading cause of death worldwide and one third of its burden can be decreased with early detection. Surface enhanced Raman spectroscopic (SERS) based imaging is a promising new technique for non-invasive detection of tumours due to its ultra-sensitivity and multiplexing capabilities. For in vivo SERS molecular imaging, a biocompatible, robust and targeted nanoparticle is required to attain high sensitivity and specificity. In this thesis, a SERS capable gold nanoparticle was rationally designed by encapsulation with a phospholipid bilayer which conferred biocompatibility, colloidal stability and versatility to changing surface chemistry. Moreover, validation of this SERS probe with a specific targeting ligand for carcinoma cells was studied through the targeting of a commonly overexpressed cancer receptor, epidermal growth factor receptor. Using this phospholipid design, optimizations with differing chemistries, targeting ligand or modifications for additional functionalities can be achieved for further development as a viable in vivo molecular imaging tool.

The indole and phenole rings comprise the main part of tryptophan and tyrosine side chains in proteins and play an important role in the stabilization of tertiary structure, interaction with active centers in biomolecules, and electron transfer phenomena. To get better insight into the interactions of these functional groups, the artificial monomolecular structures have been constructed from the synthesized bifuncional compounds with thiol and indole or phenole ring functional groups able to form self-assembled monolayers on gold, silver and copper electrodes. Properties of these monolayers were studied by Raman, infrared, and sum-frequency generation spectroscopies. The main tasks of this work were to assess the adsorption peculiarities of the bifunctional thiols at the initial stage of the monolayer formation, to determine the influence of the electrode nature on the monolayer structure, and to establish the potential influence on the properties of the terminal functional groups. It was demonstrated for the first time that at the initial stage of monolayer formation the methylene groups interact with the metal surface. Evidence for the metal-induced lowering of the CH stretching mode frequency down to 2820 cm-1 was provided. It was demonstrated that indole ring interacts with the Ag electrode surface at sufficiently negative potentials and this interaction can be recognized from the downshift of the W16 mode from ~ 1010 cm-1 to ~ 1001 cm-1. Investigations of indole... [to full text] / Triptofano ir tirozino aminorūgščių funkcinės grupės – indolo ir fenolio žiedai, stabilizuoja baltymų tretinę struktūrą, sąveikauja su aktyviais centrais biomolekulėse, dalyvauja elektronų pernašos procesuose. Siekiant giliau suprasti kaip šios grupės sąveikauja, buvo sukonstruotos dirbtinės monosluoksninės struktūros, sudarytos iš susintetintų bifunkcinių junginių, turinčių galines tiolio ir indolo žiedo arba fenolio žiedo grupes ir gebančių formuoti savitvarkius monosluoksnius ant aukso, sidabro ir vario elektrodų. Jų savybės ištirtos Ramano, infraraudonosios ir suminio dažnio generacijos spektroskopijų metodais. Pagrindiniai darbo tikslai buvo nustatyti bifunkcinių alkantiolių struktūrą ir adsorbcijos ypatumus pradinėje monosluoksnio formavimosi stadijoje, elektrodo prigimties įtaką monosluoksnių struktūrai ir potencialo įtaką galinių funkcinių grupių savybėms. Paviršiaus sustiprintos Ramano spektroskopijos metodu pirmą kartą parodyta, kad pradinėse monosluoksnių formavimo stadijose metileno grupės sąveikauja su metalo paviršiumi. Darbe įrodyta, kad dėl sąveikos su metalu spektruose atsiranda žemesnio dažnio („minkšta“) CH juosta ties 2820 cm-1. Pirmą kartą parodyta, kad indolo žiedas sąveikauja su Ag paviršiumi, esant pakankamai neigiamiems potencialams ir tą sąveiką galima spektriškai atpažinti pagal W16 modos ties ~1010 cm-1 dažnio sumažėjimu iki ~ 1001 cm-1. Tiriant indolo žiedu terminuotus ir mišrius monosluoksnius su įterptomis oktadekantiolio molekulėmis nustatytas... [toliau žr. visą tekstą]

Triptofano ir tirozino aminorūgščių funkcinės grupės – indolo ir fenolio žiedai, stabilizuoja baltymų tretinę struktūrą, sąveikauja su aktyviais centrais biomolekulėse, dalyvauja elektronų pernašos procesuose. Siekiant giliau suprasti kaip šios grupės sąveikauja, buvo sukonstruotos dirbtinės monosluoksninės struktūros, sudarytos iš susintetintų bifunkcinių junginių, turinčių galines tiolio ir indolo žiedo arba fenolio žiedo grupes ir gebančių formuoti savitvarkius monosluoksnius ant aukso, sidabro ir vario elektrodų. Jų savybės ištirtos Ramano, infraraudonosios ir suminio dažnio generacijos spektroskopijų metodais. Pagrindiniai darbo tikslai buvo nustatyti bifunkcinių alkantiolių struktūrą ir adsorbcijos ypatumus pradinėje monosluoksnio formavimosi stadijoje, elektrodo prigimties įtaką monosluoksnių struktūrai ir potencialo įtaką galinių funkcinių grupių savybėms. Paviršiaus sustiprintos Ramano spektroskopijos metodu pirmą kartą parodyta, kad pradinėse monosluoksnių formavimo stadijose metileno grupės sąveikauja su metalo paviršiumi. Darbe įrodyta, kad dėl sąveikos su metalu spektruose atsiranda žemesnio dažnio („minkšta“) CH juosta ties 2820 cm-1. Pirmą kartą parodyta, kad indolo žiedas sąveikauja su Ag paviršiumi, esant pakankamai neigiamiems potencialams ir tą sąveiką galima spektriškai atpažinti pagal W16 modos ties ~1010 cm-1 dažnio sumažėjimu iki ~ 1001 cm-1. Tiriant indolo žiedu terminuotus ir mišrius monosluoksnius su įterptomis oktadekantiolio molekulėmis nustatytas... [toliau žr. visą tekstą] / The indole and phenole rings comprise the main part of tryptophan and tyrosine side chains in proteins and play an important role in the stabilization of tertiary structure, interaction with active centers in biomolecules, and electron transfer phenomena. To get better insight into the interactions of these functional groups, the artificial monomolecular structures have been constructed from the synthesized bifuncional compounds with thiol and indole or phenole ring functional groups able to form self-assembled monolayers on gold, silver and copper electrodes. Properties of these monolayers were studied by Raman, infrared, and sum-frequency generation spectroscopies. The main tasks of this work were to assess the adsorption peculiarities of the bifunctional thiols at the initial stage of the monolayer formation, to determine the influence of the electrode nature on the monolayer structure, and to establish the potential influence on the properties of the terminal functional groups. It was demonstrated for the first time that at the initial stage of monolayer formation the methylene groups interact with the metal surface. Evidence for the metal-induced lowering of the C−H stretching mode frequency down to 2820 cm-1 was provided. It was demonstrated that indole ring interacts with the Ag electrode surface at sufficiently negative potentials and this interaction can be recognized from the downshift of the W16 mode from ~ 1010 cm-1 to ~ 1001 cm-1. Investigations of indole ring... [to full text]

No description available.

The electronegativity of thiolate ligation in the hemeprotein nitric oxide synthase (NOS) proteins has been identified as an influence on autoinhibition in this enzyme. The mutation of a conserved tryptophan residue, which hydrogen bonds to the coordinating thiolate ligand and therefore influences its electronegativity, to either phenylalanine or tyrosine has had various effects including heme loss and dimer disruption in the inducible isoforms, while hyperactivity occurs in the neuronal isoforms. I have performed the analogous mutations in W180 of eNOSoxy, the endothelial isoform. UV/visible and resonance Raman spectroscopy have demonstrated that the mutants experienced increased basicity of the thiolate due to loss of the hydrogen bond between the mutated residue in the absence of the cofactor (6R)5,6,7,8-tetrahydrobiopterin (H4B). The mutants also displayed relative rates of NO2- production that were comparable to the nNOSoxy mutants, which is consistent with the nNOSoxy results. The presence of H4B alters porphyrin planarity, which enabled hydrogen bonding to occur in W180Y, thus restoring thiolate basicity to that of wild-type eNOSoxy. Reduced overall activities by the proteins suggest that H4B stabilizes the heme. The analogous W56 mutants of saNOS, a NOS oxygenase domain-like protein from Staphylococcus aureus (saNOS), have been previously characterized using resonance Raman spectroscopy. These mutants also exhibit increased thiolate electronegativity over wild-type. As the homodimers had already been investigated, saNOS was an ideal system in which to explore heterodimers. Heterodimers were generated through the co-expression of one wild-type and one mutated subunit, enabling the examination of each subunit individually through resonance Raman spectroscopy. The subunits of the resulting proteins were shown to have heme environments that resembled those of their corresponding homodimers. The activity of saNOS did not vary significantly for the various W56 mutants, suggesting that saNOS catalysis may be unaffected by thiolate electronegativity. / Thesis (Master, Chemistry) -- Queen's University, 2008-09-04 11:37:38.688

Established techniques for the detection of pathogens, such as bacteria and viruses, require long timeframes for culturing. State of the art biosensors rely on the diffusion of the target analyte to the sensor surface. AC electric fields can be exploited to enhance the sampling of pathogens and concentrate them at specific locations on the sensor surface, thus overcoming these bottlenecks. AC electrokinetic effects like the dielectrophoretic force and electrothermal flows apply forces on the particle and the bulk fluid, respectively. While dielectrophoresis forces pathogens towards a target location, electrothermal flows circulates the fluid, thus replenishing the local concentration. Numerical simulations and experimental proof of principle demonstrate how AC electrokinetics can be used to collect model bioparticles on an antibody functionalized selective surface from a heterogeneous solution having physiologically relevant conductivity. The presence of parallel channels in a quadrupolar microelectrode design is identified as detrimental during the negative dielectrophoretic collection of bioparticles at the centre of the design while simultaneously providing secondary concentration points. These microelectrodes were incorporated onto the surface of a novel cantilever design for the rapid positive dielectrophoretic collection of Escherichia coli bacteria and enabled the subsequent detection of the bacteria by measuring the shift in the resonance frequency of the cantilever. Finally, a proof of principle setup for a Raman coupled, AC electrokinetically enhanced sampling and detection of viruses is shown where the presence of M13 phages are identified on a selective antibody functionalized surface using Raman spectroscopy. / Thesis (Ph.D, Chemical Engineering) -- Queen's University, 2012-01-30 19:23:48.958

No description available.

The Tahorakuri Formation was introduced as a stratigraphic term to simplify the sometimes complex and inconsistent naming conventions in subsurface deposits within the geothermal fields of the central Taupo Volcanic Zone (TVZ). It consists of all volcaniclastic and sedimentary deposits between the ~350 ka Whakamaru-group ignimbrites and the greywacke basement that cannot be correlated with known ignimbrites. As such, it represents a long period in which relatively little is known about the volcano-tectonic history of the TVZ. The thesis focuses on the Tahorakuri Formation at Ngatamariki and Rotokawa geothermal fields and the implications for the volcano-tectonic evolution of the TVZ. Drill cuttings from wells NM5 and NM6 are re-examined, and new U-Pb zircon dates from the Tahorakuri Formation are presented and implications discussed. Potassium feldspars identified in the drill cuttings from NM5 were examined by Raman spectroscopy and electron microprobe (EMP) analysis. Although petrographically many of the feldspars appear similar to sanidine, a primary volcanic mineral phase, this showed them to be adularia which formed during hydrothermal alteration. Raman spectroscopy was found to be ideal for analysing a large number of grains quickly, with the spectral peak at ~140 cm⁻¹ being particularly useful for identifying adularia as it is absent in sanidine. EMP analysis was found to be somewhat slower, but definitively identified the feldspars as adularia, with typical potassium-rich compositions of Or₉₄-Or₉₉. U-Pb dating shows that the Tahorakuri Formation formed over a very long time, with pyroclastic deposits ranging from 1.89 - 0.70 Ma. This was followed by a period with little or no explosive volcanism until ~0.35 Ma during which sediments were deposited at Ngatamariki. The periods at ~1.9 Ma and ~0.9 Ma were particularly active phases of pyroclastic deposition, with the second phase likely correlating with the Akatarewa ignimbrite. The oldest deposits overlie a large andesitic composite cone volcano. Significant subsidence of the andesite must have preceded emplacement of the silicic deposits, indicating that rifting within the central TVZ may have started earlier than previously thought. While the origin of the deposits is uncertain, the distribution of the oldest deposits outcropping at the surface, as well as the likely early initiation of rifting, would suggest a source within the TVZ is likely.