text: DSpace Community: http://hdl.handle.net/2381/118 2016-10-24T14:12:09Z 2016-10-24T14:12:09Z The adsorption of helium atoms on coronene cations Kurzthaler, Thomas Rasul, Bilal Kuhn, Martin Lindinger, Albrecht Scheier, Paul Ellis, Andrew M. http://hdl.handle.net/2381/38177 2016-10-11T02:21:23Z 2016-10-10T11:39:09Z Title: The adsorption of helium atoms on coronene cations Authors: Kurzthaler, Thomas; Rasul, Bilal; Kuhn, Martin; Lindinger, Albrecht; Scheier, Paul; Ellis, Andrew M. Abstract: We report the first experimental study of the attachment of multiple foreign atoms to a cationic polycyclic aromatic hydrocarbon (PAH). The chosen PAH was coronene, C24H12, which was added to liquid helium nanodroplets and then subjected to electron bombardment. Using mass spectrometry, coronene cations decorated with helium atoms were clearly seen and the spectrum shows peaks with anomalously high intensities ("magic number" peaks), which represent ion-helium complexes with added stability. The data suggest the formation of a rigid helium layer consisting of 38 helium atoms that completely cover both faces of the coronene ion. Additional magic numbers can be seen for the further addition of 3 and 6 helium atoms, which are thought to attach to the edge of the coronene. The observation of magic numbers for the addition of 38 and 44 helium atoms is in good agreement with a recent path integral Monte Carlo prediction for helium atoms on neutral coronene. An understanding of how atoms and molecules attach to PAH ions is important for a number of reasons including the potential role such complexes might play in the chemistry of the interstellar medium. 2016-10-10T11:39:09Z Marked long-term decline in ambient CO mixing ratio in SE England, 1997-2014: evidence of policy success in improving air quality Lowry, D. Lanoiselle, M. E. Fisher, R. E. Martin, M. Fowler, C. M. R. France, J. L. Hernandez-Paniagua, I. Y. Novelli, P. C. Sriskantharajah, S. O'Brien, P. Rata, N. D. Holmes, C. W. Fleming, Zoe L. Clemitshaw, K. C. Zazzeri, G. Pommier, M. McLinden, C. A. Nisbet, E. G. http://hdl.handle.net/2381/38131 2016-10-05T02:18:11Z 2016-10-04T11:10:51Z Title: Marked long-term decline in ambient CO mixing ratio in SE England, 1997-2014: evidence of policy success in improving air quality Authors: Lowry, D.; Lanoiselle, M. E.; Fisher, R. E.; Martin, M.; Fowler, C. M. R.; France, J. L.; Hernandez-Paniagua, I. Y.; Novelli, P. C.; Sriskantharajah, S.; O'Brien, P.; Rata, N. D.; Holmes, C. W.; Fleming, Zoe L.; Clemitshaw, K. C.; Zazzeri, G.; Pommier, M.; McLinden, C. A.; Nisbet, E. G. Abstract: Atmospheric CO at Egham in SE England has shown a marked and progressive decline since 1997, following adoption of strict controls on emissions. The Egham site is uniquely positioned to allow both assessment and comparison of 'clean Atlantic background' air and CO-enriched air downwind from the London conurbation. The decline is strongest (approximately 50 ppb per year) in the 1997–2003 period but continues post 2003. A 'local CO increment' can be identified as the residual after subtraction of contemporary background Atlantic CO mixing ratios from measured values at Egham. This increment, which is primarily from regional sources (during anticyclonic or northerly winds) or from the European continent (with easterly air mass origins), has significant seasonality, but overall has declined steadily since 1997. On many days of the year CO measured at Egham is now not far above Atlantic background levels measured at Mace Head (Ireland). The results are consistent with MOPITT satellite observations and 'bottom-up' inventory results. Comparison with urban and regional background CO mixing ratios in Hong Kong demonstrates the importance of regional, as opposed to local reduction of CO emission. The Egham record implies that controls on emissions subsequent to legislation have been extremely successful in the UK. 2016-10-04T11:10:51Z Electrodeposition of chromium using novel deep eutectic solvents Al-Barzinjy, Azeez Abdullah Azeez http://hdl.handle.net/2381/38111 2016-10-04T02:20:46Z 2016-10-03T13:52:07Z Title: Electrodeposition of chromium using novel deep eutectic solvents Authors: Al-Barzinjy, Azeez Abdullah Azeez Abstract: Chromium electrodeposition is important for the production of anti-wear and anti-corrosion coatings. It has been carried out for over 50 years in a multi-billion dollars industry using essentially the same technology based on chromic acid. The toxicity of the electrolyte makes the search for an alternative process an environmental imputative. In this study a variety of novel formulations of deep eutectic solvents are produced and tested to determine their efficacy for chromium deposition. The study concentrates on using urea as a complexing agent with a variety of trivalent chromium salts. In the first results chapter complexes of CrCl3·6H2O with urea are formed. It is shown that this system displays high conductivities, despite relatively high viscosities compared with the previously reported chromium based deep eutectic solvents. Thick, adherent, non-cracked black chromium could be deposited and produce relatively hard chromium coatings. EXAFS suggests that there are a variety of chromium species but they are probably cationic with a variety of oxygen donors as ligands. In the next section [Cr(en)3]3+ species was produced as the cationic species and this had a higher conductivity than any similar system previously described. Bright, adherent, hard chromium was obtained by electroreduction with constant speciation. A novel solvatochromic shift, that we are unaware of in the literature, demonstrates the charge transfer complex results in an unexpected colour change. In an endeavour the remove of Cl- from the formation chrome-alum (KCr(SO4)2·12H2O) was used as the metal salt. This produced unprecedented high conductivity for this type of medium with a low viscosity. It was proposed that unlike most ionic liquids mass transport is not limited by hole transport and instead it is proposed that these liquids function more like very concentrated electrolytes where ion paring becomes important. In the final result section a variety of additives are tested. Some are shown to have a significant effect on the morphology and hardness of the deposit. Ultimately bright metallic chromium films could be reproducibly produced with a hardness of 800±10 HV. This is the first process based on Cr(III) to be able to achieve these rigorous requirements and suggests the first real alternative to hexavalent chromium for hard chrome. 2016-10-03T13:52:07Z T86: New approaches to the rational design of anticancer drugs Barlev, N. Fedorova, O. Lezina, L. Piletsky, Sergiy A. http://hdl.handle.net/2381/38079 2016-09-15T02:21:52Z 2016-09-14T14:26:18Z Title: T86: New approaches to the rational design of anticancer drugs Authors: Barlev, N.; Fedorova, O.; Lezina, L.; Piletsky, Sergiy A. 2016-09-14T14:26:18Z Anodic dissolution of metals in ionic liquids Abbott, Andrew P. Frisch, Gero Hartley, Jennifer Karim, Wrya O. Ryder, Karl S. http://hdl.handle.net/2381/38078 2016-09-15T02:21:51Z 2016-09-14T14:16:41Z Title: Anodic dissolution of metals in ionic liquids Authors: Abbott, Andrew P.; Frisch, Gero; Hartley, Jennifer; Karim, Wrya O.; Ryder, Karl S. Abstract: The anodic dissolution of metals is an important topic for battery design, material finishing and metal digestion. Ionic liquids are being used in all of these areas but the research on the anodic dissolution is relatively few in these media. This study investigates the behaviour of 9 metals in an ionic liquid [C4mim][Cl] and a deep eutectic solvent, Ethaline, which is a 1:2 mol ratio mixture of choline chloride and ethylene glycol. It is shown that for the majority of metals studied a quasi-passivation of the metal surface occurs, primarily due to the formation of insoluble films on the electrode surface. The behaviour of most metals is different in [C4mim][Cl] to that in Ethaline due in part to the differences in viscosity. The formation of passivating salt films can be decreased with stirring or by increasing the electrolyte temperature, thereby increasing ligand transport to the electrode surface. 2016-09-14T14:16:41Z Spectroscopic and computational chemistry studies on terpene related compounds Allpress, Stephanie Marie http://hdl.handle.net/2381/38030 2016-09-10T04:02:06Z 2016-09-09T10:48:49Z Title: Spectroscopic and computational chemistry studies on terpene related compounds Authors: Allpress, Stephanie Marie Abstract: The millimetre wave spectrum of linalool (C10H18O) was recorded and assigned in the region 48-63 GHz whilst the millimetre wave spectrum of verbenone (C10H14O) was recorded and assigned in the region 48-69 GHz. Calculations at the MP3/6-31++g(d,p) and B3LYP/aug-cc-pVTZ levels of theory on both molecules, identified around 60 conformers of linalool and a single conformer of verbenone. The lowest energy conformers of linalool and verbenone are in good agreement with the fitted rotational and centrifugal distortion constants. Calculations using the B3LYP functional with the 6-31G(d,p) and 6-31++G(d,p) basis sets investigated the barrier for internal rotation of the methyl groups to explore the potential splitting of the spectral lines. The barrier for internal rotation for linalool (305 cm-1) resulted in the splitting of the spectral lines, whereas the barrier for internal rotation for verbenone (741 cm-1) did not result in such splitting. There have been no previous theoretical studies examining the products of the ozonolysis of terpinolene. The reaction mechanism for the ozonolysis of terpinolene has been explored at the B3LYP/6-31++G(d,p) and MPW1K/6-31++G(d,p) levels of theory. Single point calculations of the energy minima, transition state structures and possible reaction products were conducted at the MPW1K/6-31++G(3df,3dp) in order to improve the electronic energies. Work was also carried out on a White-type multi-traversal absorption cell. The old 4 m cell possessed a leak, which inhibits it from being used to study terpinolene ozonolysis products over prolonged time periods. Alterations to improve this system were discussed and resulted in the design and construction of a new 64 m absorption cell in which to study these ozonolysis products. 2016-09-09T10:48:49Z Chemical biology tools to explore the activities and mechanisms of Class I HDAC corepressor complexes Robertson, Naomi Stephanie http://hdl.handle.net/2381/37975 2016-08-17T02:26:26Z 2016-08-16T11:20:36Z Title: Chemical biology tools to explore the activities and mechanisms of Class I HDAC corepressor complexes Authors: Robertson, Naomi Stephanie Abstract: Isoform selective histone deacetylase (HDAC) inhibitors are urgently required to investigate HDAC isoform phenotypes and provide targeted therapeutics. Class 1 HDACs (1, 2 and 3) are recruited into large multi-subunit co-repressor complexes for maximal activity. However, little attention has been paid to targeting the disruption of these protein-protein interactions (PPIs) and so represents a novel approach to develop more specific therapeutics and chemical probes. This thesis describes the design, synthesis and evaluation of stapled peptide analogues of the SMRT-DAD protein. A systematic, structure based approach was taken to design the second generation stapled peptides containing phosphotyrosine residues. These were shown to be super activators of the HDAC3:SMRT-DAD corepressor complex. The synthesis of a hydroxamic acid amino acid is also described and an improvement on the current synthetic scheme is discussed. A novel hydroxamic acid containing histone H4 tail peptide was then prepared which was shown to be an inhibitor of the HDAC1:MTA1 corepressor complex with an IC50 of 366 nM. A crystal structure of this inhibitor peptide bound in the active site of HDAC1 was also obtained. The challenging synthesis of a series of histone H3 (1-21) tail sequence peptides has also been described. NMR experiments were carried out using these peptides to study both the demethylase and deacetylase activities of the ternary LSD1:CoREST:HDAC1. The deacetylase activity of HDAC1 has been shown to be much faster than the demethylase activity of LSD1. In order to obtain a crystal structure of the ternary LSD1:CoREST:HDAC1 complex and to determine the distance between the LSD1 and the HDAC1 components, three dual peptide inhibitors based on SNAIL have been designed and synthesised. These crystallisation experiments and biological studies are in progress. 2016-08-16T11:20:36Z Ionometallurgy: The Processing of Metals Using Ionic Liquids Hartley, Jennifer Marie http://hdl.handle.net/2381/37921 2016-08-09T02:18:49Z 2016-08-08T12:29:44Z Title: Ionometallurgy: The Processing of Metals Using Ionic Liquids Authors: Hartley, Jennifer Marie Abstract: Metal processing is commonly carried out using hydrometallurgy or pyrometallurgy. These two techniques, whilst widespread, have inherent issues associated with selectivity and efficiency. The aim of this study is to investigate the use of ambient temperature ionic liquids (IL) to dissolve and recover metals from ionic media. The first stage of the study involved the development of a new stable reference electrode for use in IL media. This was used to obtain activity coefficients for three different silver salts in three different imidazolium-based ILs containing matching anions. Activity coefficients were also obtained for silver chloride, anhydrous copper (II) chloride and trifluoromethanesulfonic acid in the deep eutectic solvent (DES) Ethaline and it was found that these solutions displayed ideal behaviour, even at high concentrations. The electrochemistry of metal complexes in ionic liquids was studied using cyclic voltammetry in an ethylene glycol: choline chloride eutectic (Ethaline) and these potentials were plotted against the corresponding redox potentials in aqueous media to try to determine how speciation affected the reactivity of metals in solution. The speciation of a range of metal chlorides in a range of DESs was investigated and it was found that the majority of the metal ions tended towards chloride speciation, with a few exceptions for the more oxophilic early transition metals. The addition of a substantial amount of water in the form of hydration shells did not affect the metal speciation significantly. In IL media, the speciation tended towards the anionic component of the liquid, depending on its strength as a ligand. The fundamental redox behaviour and speciation data were used to develop a practical method to separate copper from gallium in waste semiconductor scrap. Lumps of the alloy were electrodissolved in Ethaline and this was followed by selective electrowinning of the copper as metal and precipitation of the gallium as a gelatinous white hydroxide. In addition, iodine could be used as a powerful oxidising agent in DES media to oxidise a small amount of gold and recover valuable paleontological microfossils. 2016-08-08T12:29:44Z Resonance Raman spectroscopy as an in situ probe for monitoring catalytic events in a Ru–porphyrin mediated amination reaction Zardi, Paolo Gallo, Emma Solan, Gregory A. Hudson, Andrew J. http://hdl.handle.net/2381/37913 2016-08-04T02:16:58Z 2016-08-03T14:17:58Z Title: Resonance Raman spectroscopy as an in situ probe for monitoring catalytic events in a Ru–porphyrin mediated amination reaction Authors: Zardi, Paolo; Gallo, Emma; Solan, Gregory A.; Hudson, Andrew J. Abstract: Resonance Raman microspectroscopy has been widely used to study the structure and dynamics of porphyrins and metal complexes containing the porphyrin ligand. Here, we have demonstrated that the same technique can be adapted to examine the mechanism of a homogeneously-catalysed reaction mediated by a transition-metal-porphyrin complex. Previously it has been challenging to study this type of reaction using in situ spectroscopic monitoring due to the low stability of the reaction intermediates and elevated-temperature conditions. We have made a straightforward modification to the sample stage on a microscope for time-lapsed Raman microspectroscopy from reaction mixtures in these media. The allylic amination of unsaturated hydrocarbons by aryl azides, which can be catalysed by a ruthenium-porphyrin complex, has been used as an illustrative example of the methodology. The mechanism of this particular reaction has been studied previously using density-functional theory and kinetic approaches. The Raman measurements support the mechanism proposed in the earlier publications by providing the first experimental verification of a precursor reaction complex between the aryl azide and the ruthenium metal ion, and evidence for the formation of a mono-imido intermediate complex under conditions of high concentration of the reactant olefin. 2016-08-03T14:17:58Z Deep Eutectic Solvents Derived From Inorganic Salts Davis, Stefan John http://hdl.handle.net/2381/37784 2016-06-18T03:14:14Z 2016-06-17T10:24:04Z Title: Deep Eutectic Solvents Derived From Inorganic Salts Authors: Davis, Stefan John Abstract: Mixtures of metal salts with complexing agents, such as urea, form liquids, which are known as deep eutectic solvents (DESs). This has previously been applied to metal salts such as ZnCl₂, AlCl₃ and CrCl₃.6H₂O. The aim of this thesis was to see if this model could be expanded to include alkali metal salts. Some of the hydrogen bond donors (HBDs) investigated were found to form liquid mixtures with a limited number of alkali metal salts, which showed melting temperatures below 25 °C. Utilising glycerol as a HBD exhibited the highest mutual solubility with the alkali metal salts of interest, therefore this study focussed on sodium salt:glycerol mixtures. Four sodium salts were chosen: NaBr, NaOAc, NaOAc.3H₂O or Na₂B₄O₇.10H₂O, which provided a range of fluidities and contained hydrates and anhydrous salts. The ionic conductivity and viscosity of these salts with glycerol were studied, and it was found that unlike previous studies of choline chloride with glycerol where the salt decreases the viscosity of glycerol, all of the sodium salts increased the viscosity of glycerol. This suggests that sodium salts have a structure making, kosmotropic effect, rather than structure breaking, chaotropic effect, on glycerol. This phenomenon is probably due to the high charge density of Na⁺, which coordinates to the glycerol. The ion transport properties and molecular dynamics of sodium salt:glycerol mixtures have been investigated at the microscopic level using nuclear magnetic resonance and electrochemical techniques. Self-diffusion coefficients of the components of the systems of interest were found to be 10⁻¹¹- 10⁻¹³ m² s⁻¹ range. T₁ relaxation times were investigated and all systems showed a transition from a diffusion-limited, slow molecular tumbling regime to a fast molecular, high mobility, tumbling regime. Poor solubility was experienced with a range of transition metal salt probes, which was attributed to complex ion speciation. It was concluded that the sodium salt:glycerol systems studied are not ideal for electrochemical applications. The ability of the salts to form viscous gels made them ideal plasticisers for starch. Starch DES mixtures were tested as a binder for medium density fibreboard (MDF). The properties of MDF samples were tested as a function of processing conditions and composition. Pilot scale production of plasticised starch MDF composites was successful, demonstrating the current industrial infrastructure can be utilised for large-scale production at a similar cost to MDF bound with urea formaldehyde resins. 2016-06-17T10:24:04Z Molecularly Imprinted Nanoparticles for Diagnostic Applications Canfarotta, Francesco http://hdl.handle.net/2381/37775 2016-06-17T02:18:17Z 2016-06-16T09:49:27Z Title: Molecularly Imprinted Nanoparticles for Diagnostic Applications Authors: Canfarotta, Francesco Abstract: Molecularly imprinted polymers (MIP) are gaining increasing interest thanks to their low cost of manufacturing, robustness and stability compared to their bio-analogues such as antibodies. The molecular imprinting process can be defined as the generation of molecular recognition sites in a synthetic polymer. The template-derived sites thus created within the polymeric matrix allow MIPs (often referred as plastic antibodies, due to their synthetic nature) to selectively recognise and bind the target molecule. In light of these properties, MIPs have been successfully applied in sensors, assays and separation applications. Due to their small size, MIP nanoparticles (NPs or nanoMIPs) can be used in biomedicine, since the nanoscale format is potentially suitable for cellular or in vivo applications. The aim of this work is to demonstrate the suitability of the nanoMIPs as tools for imaging in cells. For this purpose, the choice of appropriate fluorescent moieties to be included in the nanoMIPs is crucial and depends on the intended application. Several fluorescent monomers were characterised and chosen as imaging functionalities to be employed in the synthesis of MIP NPs (Chapter 2). The innovative solid-phase approach used in this work enables the synthesis of nanoMIPs both in organics (for small templates) and in water (for peptides and proteins), with the possibility to tailor the particle's surface chemistry according to the intended use. (Chapter 3 and 4). Only few examples of MIP NPs for cellular imaging have been reported so far. Such nanosystems should be biocompatible and physiochemically stable under physiological conditions, as demonstrated in Chapter 5 and 6. Thanks to their good biocompatibility and recognition properties, MIP NPs were successfully applied as membrane-targeted diagnostic tools (Chapter 7) in both cancer and senescent cells, thus paving the way for their in vivo use as diagnostic and imaging tools. 2016-06-16T09:49:27Z Speciation, physical and electrolytic properties of eutectic mixtures based on CrCl₃·6H₂O and urea Abbott, Andrew P. Al-Barzinjy, Azeez A. Abbott, Paul D. Frisch, Gero Harris, Robert C. Hartley, Jennifer Ryder, Karl S. http://hdl.handle.net/2381/37718 2016-06-09T02:14:18Z 2016-06-08T11:48:47Z Title: Speciation, physical and electrolytic properties of eutectic mixtures based on CrCl₃·6H₂O and urea Authors: Abbott, Andrew P.; Al-Barzinjy, Azeez A.; Abbott, Paul D.; Frisch, Gero; Harris, Robert C.; Hartley, Jennifer; Ryder, Karl S. Abstract: The electrodeposition of chromium is a technologically vital process, which is principally carried out using aqueous chromic acid. In the current study, it is shown that eutectic mixtures of urea and hydrated chromium(III) chloride provide a liquid which reduces the toxicological issues associated with the current aqueous Cr(VI) electroplating solution. Using EXAFS, mass spectrometry and UV-Vis spectroscopy, it is shown that chromium is present predominantly as a cationic species. Conductivities are higher than for most comparable ionic liquids. It is shown that the electrodeposition of chromium is electrochemically reversible, with a current efficiency much higher than in aqueous electrolytes. Surface tension and density measurements indicate that hole theory is a valid model to describe transport properties in these liquids. Bulk Cr deposits are not macrocrystalline but they are generally crack-free. The deposits have a hardness of 600 ± 10 Vickers and, as such, are comparable to deposits from aqueous systems. 2016-06-08T11:48:47Z Mapping gas-phase organic reactivity and concomitant secondary organic aerosol formation: chemometric dimension reduction techniques for the deconvolution of complex atmospheric data sets Wyche, K. P. Monks, Paul S. Smallbone, K. L. Hamilton, J. F. Alfarra, M. R. Rickard, A. R. McFiggans, G. B. Jenkin, M. E. Bloss, W. J. Ryan, A. C. Hewitt, C. N. MacKenzie, A. R. http://hdl.handle.net/2381/37640 2016-05-25T02:14:45Z 2016-05-24T13:12:36Z Title: Mapping gas-phase organic reactivity and concomitant secondary organic aerosol formation: chemometric dimension reduction techniques for the deconvolution of complex atmospheric data sets Authors: Wyche, K. P.; Monks, Paul S.; Smallbone, K. L.; Hamilton, J. F.; Alfarra, M. R.; Rickard, A. R.; McFiggans, G. B.; Jenkin, M. E.; Bloss, W. J.; Ryan, A. C.; Hewitt, C. N.; MacKenzie, A. R. Abstract: Highly non-linear dynamical systems, such as those found in atmospheric chemistry, necessitate hierarchical approaches to both experiment and modelling in order to ultimately identify and achieve fundamental process-understanding in the full open system. Atmospheric simulation chambers comprise an intermediate in complexity, between a classical laboratory experiment and the full, ambient system. As such, they can generate large volumes of difficult-to-interpret data. Here we describe and implement a chemometric dimension reduction methodology for the deconvolution and interpretation of complex gas- and particle-phase composition spectra. The methodology comprises principal component analysis (PCA), hierarchical cluster analysis (HCA) and positive least-squares discriminant analysis (PLS-DA). These methods are, for the first time, applied to simultaneous gas- and particle-phase composition data obtained from a comprehensive series of environmental simulation chamber experiments focused on biogenic volatile organic compound (BVOC) photooxidation and associated secondary organic aerosol (SOA) formation. We primarily investigated the biogenic SOA precursors isoprene, α-pinene, limonene, myrcene, linalool and β-caryophyllene. The chemometric analysis is used to classify the oxidation systems and resultant SOA according to the controlling chemistry and the products formed. Results show that "model" biogenic oxidative systems can be successfully separated and classified according to their oxidation products. Furthermore, a holistic view of results obtained across both the gas- and particle-phases shows the different SOA formation chemistry, initiating in the gas-phase, proceeding to govern the differences between the various BVOC SOA compositions. The results obtained are used to describe the particle composition in the context of the oxidised gas-phase matrix. An extension of the technique, which incorporates into the statistical models data from anthropogenic (i.e. toluene) oxidation and "more realistic" plant mesocosm systems, demonstrates that such an ensemble of chemometric mapping has the potential to be used for the classification of more complex spectra of unknown origin. More specifically, the addition of mesocosm data from fig and birch tree experiments shows that isoprene and monoterpene emitting sources, respectively, can be mapped onto the statistical model structure and their positional vectors can provide insight into their biological sources and controlling oxidative chemistry. The potential to extend the methodology to the analysis of ambient air is discussed using results obtained from a zero-dimensional box model incorporating mechanistic data obtained from the Master Chemical Mechanism (MCMv3.2). Such an extension to analysing ambient air would prove a powerful asset in assisting with the identification of SOA sources and the elucidation of the underlying chemical mechanisms involved. 2016-05-24T13:12:36Z Synthesis and Applications of Perfluoroalkylated Organophosphorus Ligands Ajlouni, Amin Fathi Amin http://hdl.handle.net/2381/37622 2016-05-21T03:38:33Z 2016-05-20T12:17:47Z Title: Synthesis and Applications of Perfluoroalkylated Organophosphorus Ligands Authors: Ajlouni, Amin Fathi Amin Abstract: This research concerns a new generation of phosphorus ligands bearing short and branched perfluoroalkyl or perfluoropolyether substituents of the fluorine content and their coordination chemistry as an alternative ligands and metal complexes having a potential application in fluorous biphase system in all common organic solvents. A series of new perfluoroalkylated arylphosphines with the general formula of P(C₆H₄-p-R)₃, where R = OC₂H₄OC₄F₉, OCH₂C₄F₉, or CH₂OCF₂ (OCF₂CF₂)₂OCF₃; aryl phosphonic acid ligands [R-p-C₆H₄P(O)(OH)₂], where R = OCH₂CH₂C₄F₉ or OCH₂CF₂ (OCF₂CF₂)₂OCF₃, and alkyl phosphinite and phosphonite ligands (Ph)ₓP(OR)₃₋ₓwhere R = CH₂CH₂C₄F₉, CH(CH₂OC₄F₉)₂, or CH₂CF₂(OCF₂CF₂)₂OCF₃ have been synthesised and fully characterised by ¹H, ¹⁹F, ³¹P, and ¹³C NMR spectroscopies, and mass spectrometry. The perfluoroalkylated phosphine, phosphinite, phosphonite ligands have been reacted with transition metal complexes to form complexes of the type cis and trans-[PtCl₂L₂], and [Cp*RhCl₂L]. The complexes were isolated and characterised using ¹H, ¹⁹F, and ³¹P NMR spectroscopies, mass spectrometry, and X-ray crystallography. The derivatised phosphonic acid ligands have been reacted with transition metal complexes as dianionic bidentate ligands to form coordination complexes of the type [Pt(O₃PR)(PPh₃)₂] and zirconium phosphonate Zr[O₃PC₆H₄-4-R]₂. The platinum complexes have been fully characterised by ¹H, ¹⁹F, and ³¹P NMR spectroscopies, and mass spectrometry. The zirconium phosphonates are immiscible in all the organic solvents. Therefore the characterisation was limited to ESEM and IR studies. A study into potential fluorous solubility of the synthesised ligands and their metal complexes was also undertaken. In this regard, the influence of the fluorine contents, and the electronic insulating groups on the organic/fluorous solubility rate was also examined. 2016-05-20T12:17:47Z Use of Deep Eutectic Solvents (DESs) for the Preparation of Thermoelectric Materials Cook, Amy http://hdl.handle.net/2381/37621 2016-05-21T03:39:31Z 2016-05-20T11:55:42Z Title: Use of Deep Eutectic Solvents (DESs) for the Preparation of Thermoelectric Materials Authors: Cook, Amy Abstract: Global energy consumption was reported at 4.1 x 10²⁰ J (equivalent to 13 terawatts) in 2005, expected to more than triple by the end of the century based on projected population and economic growth. These rapidly increasing energy demands coupled with concerns over climate change as well as depletion of fossil fuel supplies has led to intensive efforts to increase the efficiency of current processes of energy production, conversion and recovery. Thermoelectric materials have in recent years emerged as a potential solution to this problem. Thermoelectric devices use temperature gradients to generate electrical energy due to the potential difference across a cell. The cell potentials for most materials are generally quite small and so semiconductor materials have to be used to optimise the cell potential. These materials are generally quite difficult to produce and this thesis examines two novel methods of creating semiconductor materials on a conducting surface. Both techniques make use of deep eutectic solvents (DESs), a novel type of solvent formed by mixing a quaternary ammonium salt with a hydrogen bond donor. This study will focus on simple metal sulfides as they are inexpensive to prepare and could be used for large surface area devices. The first technique oxidises a metal electrochemically in a DES containing sodium sulfide to produce a metal sulfide on the metal surface. The second technique uses powders of the metal sulfide on an electrode surface and by a process of oxidation and reduction it attempts to fuse the powder onto the electrode surface. It is shown that both techniques are successful and a thermoelectric device could be constructed but the layers produced are relatively thin. 2016-05-20T11:55:42Z Atmospheric Measurements of Biogenic and Anthropogenic Emissions by Broadband Cavity Enhanced Absorption Spectroscopy Adams, Thomas John http://hdl.handle.net/2381/37611 2016-05-20T02:15:48Z 2016-05-19T14:57:11Z Title: Atmospheric Measurements of Biogenic and Anthropogenic Emissions by Broadband Cavity Enhanced Absorption Spectroscopy Authors: Adams, Thomas John Abstract: This thesis describes the quantification of biogenic and anthropogenic trace gases using the highly sensitive spectroscopic technique of broadband cavity enhanced absorption spectroscopy (BBCEAS). This technique uses a high finesse optical cavity to make absorption measurements over extended path lengths within a compact instrument and over wavelength ranges that are sufficiently broad to enable several overlapping absorbers to be quantified simultaneously. Here, BBCEAS was applied to measure I₂ emissions in coastal regions, NO₂ in urban ambient air, and VOC oxidation products during experiments in an atmospheric simulation chamber. Much of the work used a novel, mobile, battery-powered BBCEAS system to measure gas concentrations in very close proximity to their emission sources. The dominant emission source of iodine into the atmosphere in coastal regions comes from intertidal macroalgal beds. Gas-phase iodine chemistry perturbs the HOₓ and NOₓ radical cycles, provides additional sink reactions for tropospheric ozone, and initiates nucleation of new aerosol particles. Results are presented from an extensive laboratory study of I₂ emissions from five species of temperate seaweeds. Time- and species-dependent I₂ emission rates were quantified in studies mimicking the progressive exposure of seaweeds to air around low tide. Seasonal differences in I₂ emission rates were investigated. By deploying the BBCEAS instrument from a boat, I₂ concentrations were also measured directly above Laminaria digitata and Ascophyllum nodosum seaweeds growing in their natural habitat. NOₓ emissions affect urban air quality directly and indirectly (the latter via formation of tropospheric ozone and secondary aerosol). BBCEAS was applied to measure NO₂ and the optical extinction from aerosol particles at locations around the Leicester University campus. BBCEAS results were compared with commercial NOₓ (chemiluminescence) and aerosol instrumentation. The mobile BBCEAS instrument was also deployed to investigate the dispersion of NO₂ from the roadside. 2016-05-19T14:57:11Z Observation of stable HO4+ and DO4+ ions from ion-molecule reactions in helium nanodroplets Renzler, Michael Ralser, Stefan Kranabetter, Lorenz Barwa, Erik Scheier, Paul Ellis, Andrew M. http://hdl.handle.net/2381/37479 2016-05-06T02:05:17Z 2016-05-05T09:54:30Z Title: Observation of stable HO4+ and DO4+ ions from ion-molecule reactions in helium nanodroplets Authors: Renzler, Michael; Ralser, Stefan; Kranabetter, Lorenz; Barwa, Erik; Scheier, Paul; Ellis, Andrew M. Abstract: Ion–molecule reactions between clusters of H₂/D₂ and O₂ in liquid helium nanodroplets were initiated by electron-induced ionization (at 70 eV). Reaction products were detected by mass spectrometry and can be explained by a primary reaction channel involving proton transfer from H₃+ or H₃+(H₂)n clusters and their deuterated equivalents. Very little HO₂+ is seen from the reaction of H₃+ with O₂, which is attributed to an efficient secondary reaction between HO₂+ and H₂. On the other hand HO₄+ is the most abundant product from the reaction of H₃+ with oxygen dimer, (O₂)₂. The experimental data suggest that HO₄+ is a particularly stable ion and this is consistent with recent theoretical studies of this ion. Description: The file associated with this record is under an 12-month embargo from publication in accordance with the publisher's self-archiving policy. The full text may be available through the publisher links provided above. 2016-05-05T09:54:30Z 2-Ethoxy-4-(4-methylphenyl)-6-phenylpyridine-3-carbonitrile Mohamed, S. K. Akkurt, M. Abdelhamid, A. A. Singh, Kuldip El-Remaily, M. A. A. http://hdl.handle.net/2381/37450 2016-04-27T02:05:17Z 2016-04-26T11:41:11Z Title: 2-Ethoxy-4-(4-methylphenyl)-6-phenylpyridine-3-carbonitrile Authors: Mohamed, S. K.; Akkurt, M.; Abdelhamid, A. A.; Singh, Kuldip; El-Remaily, M. A. A. Abstract: The title compound, C21H18N2O, crystallized with two independent molecules (A and B) in the asymmetric unit. In molecule A, the central pyridine ring forms dihedral angles of 14.55 (13) and 39.14 (12)° with the terminal phenyl and benzene rings, respectively. The latter rings make a dihedral angle of 33.06 (13)° with each other. The corresponding values for molecule B are 26.86 (13), 41.82 (12) and 38.99 (13)°, respectively. In the crystal, the B molecules are linked via a pair of weak C-H...N hydrogen bonds, forming inversion dimers. In addition, C-H...[pi] interactions and [pi]-[pi] [centroid-centroid distances = 3.5056 (16) and 3.8569 (17) Å] stacking interactions are observed. Description: Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: SU2474). 2016-04-26T11:41:11Z 5-(4-Methylphenyl)-3-phenylcyclohex-2-en-1-one Mohamed, S. K. Akkurt, M. Abdelhamid, A. A. Singh, Kuldip Allah, O. A. A. A. http://hdl.handle.net/2381/37449 2016-04-27T02:05:22Z 2016-04-26T11:35:16Z Title: 5-(4-Methylphenyl)-3-phenylcyclohex-2-en-1-one Authors: Mohamed, S. K.; Akkurt, M.; Abdelhamid, A. A.; Singh, Kuldip; Allah, O. A. A. A. Abstract: In the title compound, C19H18O, the cyclohexene ring has an envelope conformation with the methine C atom on the flap. The phenyl and methylphenyl rings form a dihedral angle of 85.93 (11)°. The crystal packing is consolidated by van der Waals forces and weak C-H...[pi] interactions. Description: Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: XU5565). 2016-04-26T11:35:16Z 2-Amino-4-(4-chlorophenyl)-5-oxo-5,6,7,8-tetrahydro-4H-chromene-3-carbonitrile Mohamed, S. K. Akkurt, M. Abdelhamid, A. A. Singh, Kuldip Allahverdiyev, M. A. http://hdl.handle.net/2381/37448 2016-04-27T02:06:52Z 2016-04-26T11:27:30Z Title: 2-Amino-4-(4-chlorophenyl)-5-oxo-5,6,7,8-tetrahydro-4H-chromene-3-carbonitrile Authors: Mohamed, S. K.; Akkurt, M.; Abdelhamid, A. A.; Singh, Kuldip; Allahverdiyev, M. A. Abstract: In the title moleclue, C16H13ClN2O2, the cyclohexene ring is in a sofa conformation. The pyran ring is essentialy planar [maximum deviation = 0.038 (2) Å] and forms a dihedral angle of 89.68 (10)° with the benzene ring. In the crystal, molecules are linked by pairs of N-H...N hydrogen bonds, forming inversion dimers with R22(12) ring motifs. These dimers are further linked by N-H...O hydrogen bonds into chains along [110]. Weak C-H...O hydrogen bonds are also present. Description: Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: LH5452). 2016-04-26T11:27:30Z 2-(4-Isobutylphenyl)-N'-[(3Z)-2-oxoindolin-3-ylidene]propanohydrazide Mohamed, S. K. Akkurt, M. Albayati, M. R. Singh, Kuldip Potgieter, H. http://hdl.handle.net/2381/37447 2016-04-27T02:06:52Z 2016-04-26T11:22:08Z Title: 2-(4-Isobutylphenyl)-N'-[(3Z)-2-oxoindolin-3-ylidene]propanohydrazide Authors: Mohamed, S. K.; Akkurt, M.; Albayati, M. R.; Singh, Kuldip; Potgieter, H. Abstract: In the title compound, C21H23N3O2, the indolin-2-one group is essentially planar, with a maximum deviation of 0.016 (2) Å for the N atom, and makes a dihedral angle of 84.38 (14)° with the benzene ring. The =N-N(H)-C(=O)-C- torsion angle is 0.9 (3)°. In the crystal, molecules are linked into a three-dimensional network via N-H...O and C-H...O hydrogen bonds. In addition, a C-H...[pi] interaction was observed. Description: Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: HG5199). 2016-04-26T11:22:08Z 1-(2-Hydroxyethyl)-3-phenylthiourea Abdelhamid, A. A. Mohamed, S. K. Akkurt, M. Singh, Kuldip Potgieter, H. http://hdl.handle.net/2381/37446 2016-04-27T02:05:16Z 2016-04-26T11:13:45Z Title: 1-(2-Hydroxyethyl)-3-phenylthiourea Authors: Abdelhamid, A. A.; Mohamed, S. K.; Akkurt, M.; Singh, Kuldip; Potgieter, H. Abstract: The title compound, C9H12N2OS, was obtained unexpectedly in a multicomponent reaction of an equimolar ratio of phenyl isothiocyanate, malononitrile and aminoethanol. The -C(H2)-N(H)-(C=S)-N(H)- methylthiourea-methane group is almost normal to the phenyl ring, with a dihedral angle of 71.13 (9)°. The N-C-C-O torsion angle is 72.8 (2)°. In the crystal, molecules are connected by N-H...O, O-H...S and N-H...O hydrogen bonds, forming a three-dimensional network. Description: Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: RK2342). 2016-04-26T11:13:45Z (6Z)-4-Bromo-6-{[(2-hydroxyethyl)amino]methylidene}cyclohexa-2,4-dien-1-one Mohamed, S. K. Akkurt, M. Elhamid, A. A. A. Singh, Kuldip Potgieter, H. http://hdl.handle.net/2381/37431 2016-04-23T02:31:26Z 2016-04-22T10:01:16Z Title: (6Z)-4-Bromo-6-{[(2-hydroxyethyl)amino]methylidene}cyclohexa-2,4-dien-1-one Authors: Mohamed, S. K.; Akkurt, M.; Elhamid, A. A. A.; Singh, Kuldip; Potgieter, H. Abstract: The title molecule, C9H10BrNO2, excluding methylene H atoms and the C-OH group, is essentially planar, with a maximum deviation of 0.037 (2) Å for the N atom. The N-C-C-O torsion angle is -63.1 (3)°. The molecular structure is stabilized by a weak intramolecular N-H...O(carbonyl) hydrogen bond, forming an S(6) motif. In the crystal, molecules are linked by O-H...O and C-H...O hydrogen bonds, forming a three-dimensional network. Description: Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: WN2469). 2016-04-22T10:01:16Z Deep Eutectic Solvents (DESs) and Their Applications Smith, E. L. Abbott, Andew P. Ryder, Karl Scott http://hdl.handle.net/2381/37428 2016-04-22T02:07:32Z 2016-04-21T11:23:00Z Title: Deep Eutectic Solvents (DESs) and Their Applications Authors: Smith, E. L.; Abbott, Andew P.; Ryder, Karl Scott 2016-04-21T11:23:00Z Wintertime aerosol chemical composition, volatility, and spatial variability in the greater London area Xu, L. Williams, L. R. Young, D. E. Allan, J. D. Coe, H. Massoli, P. Fortner, E. Chhabra, P. Herndon, S. Brooks, W. A. Jayne, J. T. Worsnop, D. R. Aiken, A. C. Liu, S. Gorkowski, K. Dubey, M. K. Fleming, Zoe L. Visser, S. Prévôt, A. S. H. Ng, N. L. http://hdl.handle.net/2381/37336 2016-04-19T02:04:36Z 2016-04-18T11:04:31Z Title: Wintertime aerosol chemical composition, volatility, and spatial variability in the greater London area Authors: Xu, L.; Williams, L. R.; Young, D. E.; Allan, J. D.; Coe, H.; Massoli, P.; Fortner, E.; Chhabra, P.; Herndon, S.; Brooks, W. A.; Jayne, J. T.; Worsnop, D. R.; Aiken, A. C.; Liu, S.; Gorkowski, K.; Dubey, M. K.; Fleming, Zoe L.; Visser, S.; Prévôt, A. S. H.; Ng, N. L. Abstract: The composition of PM1 (particulate matter with diameter less than 1 µm) in the greater London area was characterized during the Clean Air for London (ClearfLo) project in winter 2012. Two high-resolution time-of-flight aerosol mass spectrometers (HR-ToF-AMS) were deployed at a rural site (Detling, Kent) and an urban site (North Kensington, London). The simultaneous and high-temporal resolution measurements at the two sites provide a unique opportunity to investigate the spatial distribution of PM1. We find that the organic aerosol (OA) concentration is comparable between the rural and urban sites, but the contribution from different sources is distinctly different between the two sites. The concentration of solid fuel OA at the urban site is about twice as high as at the rural site, due to elevated domestic heating in the urban area. While the concentrations of oxygenated OA (OOA) are well-correlated between the two sites, the OOA concentration at the rural site is almost twice that of the urban site. At the rural site, more than 70 % of the carbon in OOA is estimated to be non-fossil, which suggests that OOA is likely related to aged biomass burning considering the small amount of biogenic SOA in winter. Thus, it is possible that the biomass burning OA contributes a larger fraction of ambient OA in wintertime than what previous field studies have suggested. A suite of instruments was deployed downstream of a thermal denuder (TD) to investigate the volatility of PM1 species at the rural Detling site. After heating at 250 °C in the TD, 40 % of the residual mass is OA, indicating the presence of non-volatile organics in the aerosol. Although the OA associated with refractory black carbon (rBC; measured by a soot-particle aerosol mass spectrometer) only accounts for < 10 % of the total OA (measured by a HR-ToF-AMS) at 250 °C, the two measurements are well-correlated, suggesting that the non-volatile organics have similar sources or have undergone similar chemical processing as rBC in the atmosphere. Although the atomic O : C ratio of OOA is substantially larger than that of solid fuel OA and hydrocarbon-like OA, these three factors have similar volatility, which is inferred from the change in mass concentration after heating at 120 °C. Finally, we discuss the relationship between the mass fraction remaining (MFR) of OA after heating in the TD and atomic O : C of OA and find that particles with a wide range of O : C could have similar MFR after heating. This analysis emphasizes the importance of understanding the distribution of volatility and O : C in bulk OA. 2016-04-18T11:04:31Z Active O,Npy,N-Titanium(IV) Fluoride Pre-Catalysts for Ethylene Polymerization; Exploring "Fluoride Effects" on Polymer Properties and Catalytic Performance Solan, Gregory Adam Wright, Luka A. Hope, Eric G. Cross, Warren B. Singh, Kuldip http://hdl.handle.net/2381/37209 2016-04-09T03:40:04Z 2016-04-08T10:30:07Z Title: Active O,Npy,N-Titanium(IV) Fluoride Pre-Catalysts for Ethylene Polymerization; Exploring "Fluoride Effects" on Polymer Properties and Catalytic Performance Authors: Solan, Gregory Adam; Wright, Luka A.; Hope, Eric G.; Cross, Warren B.; Singh, Kuldip Abstract: Three examples of discrete six-coordinate O,Npy,N-bearing titanium(IV) trifluoride complexes, [{2-(C5H4N)-6-(CMe2O)C5H3N}TiF3] (1), [{2-(C6H4-2′-O),6-(CMe═N(2,6-i-Pr2C6H3))C5H3N}TiF3] (2a), and [{2-(3-C12H8-2-O)-6-(CMe═N(2,6-i-Pr2C6H3))C5H3N}TiF3] (3a), were prepared using a one-step HF elimination protocol from cis-[(THF)2TiF4] and the corresponding pincer ligand precursor (HL1, HL2H, and HL2Ph). A mer configuration of the three fluoride ligands is adopted in their solid-state structures, which is mirrored in solution, as shown by mutual two-bond F–F coupling in their 19F{1H} NMR spectra. For purposes of comparison, the chloride counterparts of 2a and 3a, [{2-(C6H4-2′-O),6-(CMe═N(2,6-i-Pr2C6H3)C5H3N}TiCl3] (2b) and [{2-(3-C12H8-2-O)-6-(CMe═N(2,6-i-Pr2C6H3))C5H3N}TiCl3] (3b), are also reported. On treatment with excess MAO, 1 is scarcely active in ethylene polymerization, 2a is more active, and the most sterically protected system, 3a, represents the most active nonmetallocene metal-fluoride precatalyst reported to date (340 g mmol–1 h–1 bar–1) and produces ultra-high-molecular-weight polyethylene (UHMWPE). Similar structure–activity correlations are displayed for chloride-containing 2b and 3b, but, in general, they are significantly more active than their fluoride counterparts, with 3b being the most productive of the series (990 g mmol–1 h–1 bar–1). Using fluoride rather than chloride in the precatalyst has a marked effect on not only the molecular weight but also the molecular weight distribution, with broad dispersities (Đ) being a feature of the polymers obtained from 2a and 3a, whereas those for chloride-containing 2b and 3b are appreciably narrower. Single-crystal X-ray structures are reported for 1, 2a, 2b, and 3a. Description: The file associated with this record is under a 12-month embargo from publication in accordance with the publisher's self-archiving policy. The full text may be available through the publisher links provided above. 2016-04-08T10:30:07Z Infrared spectroscopy of salt-water complexes Ellis, Andrew M. Tandy, Jon Feng, Cheng Boatwright, Adrian Sarma, Gautam Sadoon, Ahmed M. Shirley, Andrew Das Neves Rodrigues, Natercia Cunningham, Ethan Yang, Shengfu http://hdl.handle.net/2381/37142 2016-04-06T02:23:39Z 2016-04-05T10:13:57Z Title: Infrared spectroscopy of salt-water complexes Authors: Ellis, Andrew M.; Tandy, Jon; Feng, Cheng; Boatwright, Adrian; Sarma, Gautam; Sadoon, Ahmed M.; Shirley, Andrew; Das Neves Rodrigues, Natercia; Cunningham, Ethan; Yang, Shengfu Abstract: To explore how the ion-pair in a single salt molecule evolves with the addition of water, infrared (IR) spectra of complexes composed of NaCl and multiple water molecules have been recorded for the first time. The NaCl(H2O)n complexes were formed and probed in liquid helium nanodroplets, and IR spectra were recorded for n = 1 → 4. The spectra for n = 1, 2, and 3 are consistent with formation of the lowest energy contact-ion pair structures in which each water molecule forms a single ionic hydrogen bond to an intact Na+Cl− ion-pair. Alternative structures with hydrogen bonding between water molecules become energetically competitive for n = 4, and the IR spectrum indicates likely the coexistence of at least two isomers. 2016-04-05T10:13:57Z Tryptophan Oxidation by the Heme-Containing Dioxygenases Booth, Elizabeth Suzanne http://hdl.handle.net/2381/37091 2016-03-19T04:52:49Z 2016-03-18T15:27:02Z Title: Tryptophan Oxidation by the Heme-Containing Dioxygenases Authors: Booth, Elizabeth Suzanne Abstract: In biology, the kynurenine pathway is the major degradation pathway of tryptophan (L-Trp). The first and rate-limiting step is the oxidation of L-Trp to N-formylkynurenine (NFK). The mechanism of this oxygen-dependent reaction has not been established, but is catalysed by two heme-containing dioxygenase enzymes: indoleamine 2,3-dioxygenase (IDO) and tryptophan 2,3-dioxygenase (TDO). Early proposals suggested a base-catalysed abstraction mechanism, but most of the recent studies argue against that. Instead, formation of a ferryl (Compound II intermediate) seems more likely. In this thesis, aspects of the reaction mechanism have been investigated. A Compound II intermediate was detected during the oxidation of L-Trp by hIDO using stopped flow photodiode array spectroscopy. A Compound II intermediate was also detected during the oxidation of a number of different tryptophan analogues. The results suggest a common mechanism of oxidation between L-Trp and other substrates of hIDO. The difference in reactivity between the tryptophan analogues 5-hydroxy-tryptophan and 5-methoxy-tryptophan with hIDO have been interpreted to indicate that initial oxygen atom insertion occurs by radical rather than electrophilic addition. An intermediate was detected during the oxidation of L-Trp by hTDO and XcTDO. The spectrum of this intermediate did not appear to be characteristic of a Compound II based on comparison with the spectrum of Compound II from hIDO. Weaker binding of L-Trp to both hTDO and XcTDO has been used to interpret these results. It is suggested that Compound II in TDO has a different spectrum or that the rate-limiting step is altered and an alternative catalytic intermediate accumulates. Crystal trials have been conducted for hIDO and hTDO, with some conditions producing micro-crystals. The structure of XcTDO in complex with potassium cyanide and L-Trp was solved. The binding mode of L-Trp within the distal pocket does not correlate with the L-Trp binding mode in the published ferrous XcTDO- L-Trp binary complex structure. Oxidation of L-Trp by ferric TDO without the addition of reducing agent was investigated. The results suggest the recruitment of hydrogen peroxide from solution to activate ferric heme. A summary of the mechanistic information gathered from all of the above experiments is presented. 2016-03-18T15:27:02Z Synchrotron infrared spectroscopy of the v(4), v(8), v(10), v(11) and v(14) fundamental bands of thiirane Evans, Corey J. Carter, J. P. Appadoo, D. R. T. Wong, A. McNaughton, D. http://hdl.handle.net/2381/37004 2016-03-10T03:26:05Z 2016-03-09T10:13:17Z Title: Synchrotron infrared spectroscopy of the v(4), v(8), v(10), v(11) and v(14) fundamental bands of thiirane Authors: Evans, Corey J.; Carter, J. P.; Appadoo, D. R. T.; Wong, A.; McNaughton, D. Abstract: The high-resolution spectrum of thiirane has been recorded using the far-infrared beamline at the Australian synchrotron facility. Spectra have been recorded between 700 cm[Superscript: −1] and 1200 cm[Superscript: −1] and ro-vibrational transitions associated with four fundamental bands of thiirane have been observed and assigned. The effects of Coriolis coupling were observed in the upper energy levels associated with the ν4 (1024 cm[Superscript: −1]) and the ν14 (1050 cm[Superscript: −1]) fundamental bands as well as in the ν11 (825 cm[Superscript: −1]) and the ν8 (895 cm[Superscript: −1]) fundamental bands. The ν10 (945 cm[Superscript: −1]) fundamental band was also observed and was found to have no significant perturbations associated with it. For each of the observed bands rotational and centrifugal distortion constants have been evaluated, while for all but the ν10 fundamental band, Coriolis interaction parameters have been determined for the upper states. The ground state constants have also been further refined. Description: The file associated with this record is under a 24-month embargo from publication in accordance with the publisher's self-archiving policy. The full text may be available through the publisher links provided above. 2016-03-09T10:13:17Z The pure rotational spectra of the open-shell diatomic molecules PbI and SnI Evans, Corey J. Needham, Lisa-Maria E. Walker, N. R. Köckert, H. Zaleski, D. P. Stephens, S. L. http://hdl.handle.net/2381/36983 2016-03-08T03:20:41Z 2016-03-07T11:22:10Z Title: The pure rotational spectra of the open-shell diatomic molecules PbI and SnI Authors: Evans, Corey J.; Needham, Lisa-Maria E.; Walker, N. R.; Köckert, H.; Zaleski, D. P.; Stephens, S. L. Abstract: Pure rotational spectra of the ground electronic states of lead monoiodide and tin monoiodide have been measured using a chirped pulsed Fourier transform microwave spectrometer over the 7-18.5 GHz region for the first time. Each of PbI and SnI has a X (2)Π1/2 ground electronic state and may have a hyperfine structure that aids the determination of the electron electric dipole moment. For each species, pure rotational transitions of a number of different isotopologues and their excited vibrational states have been assigned and fitted. A multi-isotopologue Dunham-type analysis was carried out on both species producing values for Y01, Y02, Y11, and Y21, along with Λ-doubling constants, magnetic hyperfine constants and nuclear quadrupole coupling constants. The Born-Oppenheimer breakdown parameters for Pb have been evaluated and the parameter rationalized in terms of finite nuclear field effects. Analysis of the bond lengths and hyperfine interaction indicates that the bonding in both PbI and SnI is ionic in nature. Equilibrium bond lengths have been evaluated for both species. 2016-03-07T11:22:10Z Tris(2,2'-bipyridine-[kappa]2N,N')cobalt(II) bis(hexafluoridophosphate) Mentes, A. Singh, Kuldip http://hdl.handle.net/2381/36898 2016-02-26T03:28:12Z 2016-02-25T15:01:47Z Title: Tris(2,2'-bipyridine-[kappa]2N,N')cobalt(II) bis(hexafluoridophosphate) Authors: Mentes, A.; Singh, Kuldip Abstract: In the title compound, [Co(C10H8N2)3](PF6)2, the CoII atom is coordinated by the six N atoms of three 2,2'-bipyridyl ligands and adopts a highly distorted octahedral geometry. The crystal used was a merohedral twin, the refined ratio of twin components being 0.820 (1):0.180 (1). The crystal structure features weak C-H...F interactions, forming a three-dimensional network. Description: Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: LR2090). 2016-02-25T15:01:47Z Substrate Oxidation by Indoleamine 2,3-Dioxygenase : EVIDENCE FOR A COMMON REACTION MECHANISM Booth, E. S. Basran, J. Lee, M. Handa, S. Raven, Emma L. http://hdl.handle.net/2381/36792 2016-02-19T03:24:22Z 2016-02-18T12:50:59Z Title: Substrate Oxidation by Indoleamine 2,3-Dioxygenase : EVIDENCE FOR A COMMON REACTION MECHANISM Authors: Booth, E. S.; Basran, J.; Lee, M.; Handa, S.; Raven, Emma L. Abstract: The kynurenine pathway is the major route of l-tryptophan (l-Trp) catabolism in biology, leading ultimately to the formation of NAD(+). The initial and rate-limiting step of the kynurenine pathway involves oxidation of l-Trp to N-formylkynurenine. This is an O2-dependent process and catalyzed by indoleamine 2,3-dioxygenase and tryptophan 2,3-dioxygenase. More than 60 years after these dioxygenase enzymes were first isolated (Kotake, Y., and Masayama, I. (1936) Z. Physiol. Chem. 243, 237-244), the mechanism of the reaction is not established. We examined the mechanism of substrate oxidation for a series of substituted tryptophan analogues by indoleamine 2,3-dioxygenase. We observed formation of a transient intermediate, assigned as a Compound II (ferryl) species, during oxidation of l-Trp, 1-methyl-l-Trp, and a number of other substrate analogues. The data are consistent with a common reaction mechanism for indoleamine 2,3-dioxygenase-catalyzed oxidation of tryptophan and other tryptophan analogues. 2016-02-18T12:50:59Z Extracting cluster distributions from mass spectra : IsotopeFit Ralser, S. Postler, J. Harnisch, M. Ellis, Andrew Michael Scheier, P. http://hdl.handle.net/2381/36756 2016-02-18T03:18:36Z 2016-02-17T11:36:03Z Title: Extracting cluster distributions from mass spectra : IsotopeFit Authors: Ralser, S.; Postler, J.; Harnisch, M.; Ellis, Andrew Michael; Scheier, P. Abstract: The availability of high resolution mass spectrometry in the study of atomic and molecular clusters opens up challenges for the interpretation of the data. In complex systems each resolved mass peak may contain contributions from multiple species because of the isotope structure of constituent elements and because a multitude of different types of clusters with different compositions are present. A computational procedure which can help to identify a specific cluster from this complex dataset and quantify its relative abundance would be extremely helpful to many who work in this field. Here some new software designed for this purpose, known as IsotopeFit, is described. 2016-02-17T11:36:03Z Does size matter? Study of performance of pseudo-ELISAs based on molecularly imprinted polymer nanoparticles prepared for analytes of different sizes Caceres, C. Canfarotta, F. Chianella, I. Pereira, E. Moczko, Ewa Guerreiro, Antonio Piletska, Elena Esen, C. Whitcombe, Michael J. Piletsky, S. http://hdl.handle.net/2381/36738 2016-02-18T03:10:03Z 2016-02-17T09:44:52Z Title: Does size matter? Study of performance of pseudo-ELISAs based on molecularly imprinted polymer nanoparticles prepared for analytes of different sizes Authors: Caceres, C.; Canfarotta, F.; Chianella, I.; Pereira, E.; Moczko, Ewa; Guerreiro, Antonio; Piletska, Elena; Esen, C.; Whitcombe, Michael J.; Piletsky, S. Abstract: The aim of this work is to evaluate whether the size of the analyte used as template for the synthesis of molecularly imprinted polymer nanoparticles (nanoMIPs) can affect their performance in pseudo-enzyme linked immunosorbent assays (pseudo-ELISAs). Successful demonstration of a nanoMIPs-based pseudo-ELISA for vancomycin (1449.3 g mol[Superscript: −1]) was demonstrated earlier. In the present investigation, the following analytes were selected: horseradish peroxidase (HRP, 44 kDa), cytochrome C (Cyt C, 12 kDa) biotin (244.31 g mol[Superscript: −1]) and melamine (126.12 g mol[Superscript: −1]). NanoMIPs with a similar composition for all analytes were synthesised by persulfate-initiated polymerisation in water. In addition, core–shell nanoMIPs coated with polyethylene glycol (PEG) and imprinted for melamine were produced in organics and tested. The polymerisation of the nanoparticles was done using a solid-phase approach with the correspondent template immobilised on glass beads. The performance of the nanoMIPs used as replacement for antibodies in direct pseudo-ELISA (for the enzymes) and competitive pseudo-ELISA for the smaller analytes was investigated. For the competitive mode we rely on competition for the binding to the nanoparticles between free analyte and corresponding analyte-HRP conjugate. The results revealed that the best performances were obtained for nanoMIPs synthesised in aqueous media for the larger analytes. In addition, this approach was successful for biotin but completely failed for the smallest template melamine. This problem was solved using nanoMIP prepared by UV polymerisation in an organic media with a PEG shell. This study demonstrates that the preparation of nanoMIP by solid-phase approach can produce material with high affinity and potential to replace antibodies in ELISA tests for both large and small analytes. This makes this technology versatile and applicable to practically any target analyte and diagnostic field. Description: The file associated with this record is under a 12-month embargo from publication in accordance with the publisher's self-archiving policy. The full text may be available through the publisher links provided above. 2016-02-17T09:44:52Z Kerb and urban increment of highly time-resolved trace elements in PM10, PM2.5 and PM1.0 winter aerosol in London during ClearfLo 2012 Fleming, Zoe http://hdl.handle.net/2381/36381 2016-01-27T03:12:40Z 2016-01-26T12:11:12Z Title: Kerb and urban increment of highly time-resolved trace elements in PM10, PM2.5 and PM1.0 winter aerosol in London during ClearfLo 2012 Authors: Fleming, Zoe Abstract: Ambient concentrations of trace elements with 2 h time resolution were measured in PM[Subscript: 10–2.5], PM[Subscript: 2.5–1.0] and PM[Subscript: 1.0–0.3] size ranges at kerbside, urban background and rural sites in London during winter 2012. Samples were collected using rotating drum impactors (RDIs) and subsequently analysed with synchrotron radiation-induced X-ray fluorescence spectrometry (SR-XRF). Quantification of kerb and urban increments (defined as kerb-to-urban and urban-to-rural concentration ratios, respectively), and assessment of diurnal and weekly variability provided insight into sources governing urban air quality and the effects of urban micro-environments on human exposure. Traffic-related elements yielded the highest kerb increments, with values in the range of 10.4 to 16.6 for SW winds (3.3–6.9 for NE) observed for elements influenced by brake wear (e.g. Cu, Sb, Ba) and 5.7 to 8.2 for SW (2.6–3.0 for NE) for other traffic-related processes (e.g. Cr, Fe, Zn). Kerb increments for these elements were highest in the PM[Subscript: 10–2.5] mass fraction, roughly twice that of the PM[Subscript: 1.0–0.3] fraction. These elements also showed the highest urban increments (~ 3.0), although no difference was observed between brake wear and other traffic-related elements. All elements influenced by traffic exhibited higher concentrations during morning and evening rush hours, and on weekdays compared to weekends, with the strongest trends observed at the kerbside site, and additionally enhanced by winds coming directly from the road, consistent with street canyon effects. Elements related to mineral dust (e.g. Al, Si, Ca, Sr) showed significant influences from traffic-induced resuspension, as evidenced by moderate kerb (3.4–5.4 for SW, 1.7–2.3 for NE) and urban (~ 2) increments and increased concentrations during peak traffic flow. Elements related to regional transport showed no significant enhancement at kerb or urban sites, with the exception of PM[Subscript: 10–2.5] sea salt (factor of up to 2), which may be influenced by traffic-induced resuspension of sea and/or road salt. Heavy-duty vehicles appeared to have a larger effect than passenger vehicles on the concentrations of all elements influenced by resuspension (including sea salt) and wearing processes. Trace element concentrations in London were influenced by both local and regional sources, with coarse and intermediate fractions dominated by traffic-induced resuspension and wearing processes and fine particles influenced by regional transport. 2016-01-26T12:11:12Z Antitumour potential of BPT: a dual inhibitor of cdk4 and tubulin polymerization Mahale, S. Bharate, S. B. Manda, S. Joshi, P. Jenkins, P. R. Vishwakarma, R. A. Chaudhuri, B. http://hdl.handle.net/2381/36298 2016-01-19T03:09:54Z 2016-01-18T10:00:32Z Title: Antitumour potential of BPT: a dual inhibitor of cdk4 and tubulin polymerization Authors: Mahale, S.; Bharate, S. B.; Manda, S.; Joshi, P.; Jenkins, P. R.; Vishwakarma, R. A.; Chaudhuri, B. Abstract: The marine natural product fascaplysin (1) is a potent Cdk4 (cyclin-dependent kinase 4)-specific inhibitor, but is toxic to all cell types possibly because of its DNA-intercalating properties. Through the design and synthesis of numerous fascaplysin analogues, we intended to identify inhibitors of cancer cell growth with good therapeutic window with respect to normal cells. Among various non-planar tryptoline analogues prepared, N-(biphenyl-2-yl) tryptoline (BPT, 6) was identified as a potent inhibitor of cancer cell growth and free from DNA-binding properties owing to its non-planar structure. This compound was tested in over 60 protein kinase assays. It displayed inhibition of Cdk4-cyclin D1 enzyme in vitro far more potently than many other kinases including Cdk family members. Although it blocks growth of cancer cells deficient in the mitotic-spindle checkpoint at the G0/G1 phase of the cell cycle, the block occurs primarily at the G2/M phase. BPT inhibits tubulin polymerization in vitro and acts as an enhancer of tubulin depolymerization of paclitaxel-stabilized tubulin in live cells. Western blot analyses indicated that, in p53-positive cells, BPT upregulates the expression of p53, p21 and p27 proteins, whereas it downregulates the expression of cyclin B1 and Cdk1. BPT selectively kills SV40-transformed mouse embryonic hepatic cells and human fibroblasts rather than untransformed cells. BPT inhibited the growth of several human cancer cells with an IC50 <1 μM. The pharmacokinetic study in BALB/c mice indicated good plasma exposure after intravenous administration. It was found to be efficacious at 1/10th the maximum-tolerated dose (1000 mg/kg) against human tumours derived from HCT-116 (colon) and NCI-H460 (lung) cells in SCID (severe-combined immunodeficient) mice models. BPT is a relatively better anticancer agent than fascaplysin with an unusual ability to block two overlapping yet crucial phases of the cell cycle, mitosis and G0/G1. Its ability to effectively halt tumour growth in human tumour-bearing mice would suggest that BPT has the potential to be a candidate for further clinical development. 2016-01-18T10:00:32Z The Preparation and Intramolecular Radical Cyclisation Reactions of Chiral Oxime Ethers Booth, Susan E. Jenkins, Paul R. Swain, Christopher J. http://hdl.handle.net/2381/36294 2016-01-16T03:15:04Z 2016-01-15T15:37:45Z Title: The Preparation and Intramolecular Radical Cyclisation Reactions of Chiral Oxime Ethers Authors: Booth, Susan E.; Jenkins, Paul R.; Swain, Christopher J. Abstract: Chiral oxime ether 2 and Oxime ester 4 have been prepared by alkylation and esterification of the oxime 1. Racemic hydroxylamine 6 and chiral hydroxylamine 10 have been synthesised from N-hydroxysuccinimide and the corresponding alcohol in the presence of diethylazodicarboxylate, the two products were converted into the oxime ethers 7 and 11 respectively. The intramolecular radical cyclisation reactions of these oxime ethers and esters has been studied, successful reaction was observed to produce alkyl hydroxylamines 3, 8 and 12.; O éter-oxima quiral 2 e o éster-oxima 4 foram preparados para alquilação e esterificação da oxina 1. Hidroxiamina racêmica 6 e a hidroxiamina 10 foram sintetisadas a partir de N-hidroxipucanimida e o álcool correspondente na presença de di etil azodicarboxilato, e os dois produtos convertidos nos éteres-oximas 7 e 11 respectivamente. As reações de ciclização radicalar intramoleculares desses éteres e ésteres-oxima foram estudadas; a formação das alquil hidróxi-aminas 3, 8 e 12 foi observada nas reações bem sucedidas. 2016-01-15T15:37:45Z Tropospheric ozone and its precursors from the urban to the global scale from air quality to short-lived climate forcer Monks, Paul Steven Archibald, A. T. Colette, A. Cooper, O. Coyle, M. Derwent, R. Fowler, D. Granier, C. Law, K. S. Mills, G. E. Stevenson, D. S. Tarasova, O. Thouret, V. von Schneidemesser, E. Sommariva, R. Wild, O. Williams, M. L. http://hdl.handle.net/2381/36223 2016-01-09T03:11:54Z 2016-01-08T11:20:35Z Title: Tropospheric ozone and its precursors from the urban to the global scale from air quality to short-lived climate forcer Authors: Monks, Paul Steven; Archibald, A. T.; Colette, A.; Cooper, O.; Coyle, M.; Derwent, R.; Fowler, D.; Granier, C.; Law, K. S.; Mills, G. E.; Stevenson, D. S.; Tarasova, O.; Thouret, V.; von Schneidemesser, E.; Sommariva, R.; Wild, O.; Williams, M. L. Abstract: Ozone holds a certain fascination in atmospheric science. It is ubiquitous in the atmosphere, central to tropospheric oxidation chemistry, yet harmful to human and ecosystem health as well as being an important greenhouse gas. It is not emitted into the atmosphere but is a byproduct of the very oxidation chemistry it largely initiates. Much effort is focused on the reduction of surface levels of ozone owing to its health and vegetation impacts, but recent efforts to achieve reductions in exposure at a country scale have proved difficult to achieve owing to increases in background ozone at the zonal hemispheric scale. There is also a growing realisation that the role of ozone as a short-lived climate pollutant could be important in integrated air quality climate change mitigation. This review examines current understanding of the processes regulating tropospheric ozone at global to local scales from both measurements and models. It takes the view that knowledge across the scales is important for dealing with air quality and climate change in a synergistic manner. The review shows that there remain a number of clear challenges for ozone such as explaining surface trends, incorporating new chemical understanding, ozone–climate coupling, and a better assessment of impacts. There is a clear and present need to treat ozone across the range of scales, a transboundary issue, but with an emphasis on the hemispheric scales. New observational opportunities are offered both by satellites and small sensors that bridge the scales. 2016-01-08T11:20:35Z Bis (2-Methyl-Delta-2 (3)-Oxadiazine-4, 6-Dione)-5-Sulfonyl Singh, R. Sridhara, Narendra S. http://hdl.handle.net/2381/36112 2015-12-19T03:19:32Z 2015-12-18T16:08:37Z Title: Bis (2-Methyl-Delta-2 (3)-Oxadiazine-4, 6-Dione)-5-Sulfonyl Authors: Singh, R.; Sridhara, Narendra S. Abstract: The reaction of acetylisocyanate with sulfonyldiisocynate leads to bis (2-methyl Delta[Superscript 2 (3)]-oxadiazine-4, 6-dione)-5-sulfonyl. 2015-12-18T16:08:37Z Dimethyl-Aluminium Complexes Bearing Naphthyl-Substituted Pyridine-Alkylamides as Pro-Initiators for the Efficient ROP of epsilon-Caprolactone Armitage, Andrew P. Boyron, O. Champouret, Yohan D. M. Patel, Mehzabin Singh, Kuldip Solan, Gregory Adam http://hdl.handle.net/2381/36111 2015-12-19T03:19:26Z 2015-12-18T15:53:29Z Title: Dimethyl-Aluminium Complexes Bearing Naphthyl-Substituted Pyridine-Alkylamides as Pro-Initiators for the Efficient ROP of epsilon-Caprolactone Authors: Armitage, Andrew P.; Boyron, O.; Champouret, Yohan D. M.; Patel, Mehzabin; Singh, Kuldip; Solan, Gregory Adam Abstract: Three sterically-enhanced 2-imino-6-(1-naphthyl)pyridines, 2-{CMe=N(Ar)}-6-(1-C10H7)C5H3N [Ar = 2,6-i-Pr2C6H3 (L1dipp), 2,4,6-i-Pr3C6H2 (L1tripp), 4-Br-2,6-i-Pr2C6H2 (L1Brdipp)], differing only in the electronic properties of the N-aryl group, have been prepared in high yield by the condensation reaction of 2-{CMe=O}-6-(1-C10H7)C5H3N with the corresponding aniline. Treatment of L1dipp, L1tripp and L1Brdipp with two equivalents of AlMe3 at elevated temperature affords the distorted tetrahedral 2-(amido-prop-2-yl)-6-(1-naphthyl)pyridine aluminum dimethyl complexes, [2-{CMe2N(Ar)}-6-(1-C10H7)C5H3N]AlMe2 [Ar = 2,6-i-Pr2C6H3 (1a), 2,4,6-i-Pr3C6H2 (1b), 4-Br-2,6-i-Pr2C6H2 (1c)], in good yield. The X-ray structures of 1a–1c reveal that complexation has resulted in concomitant C–C bond formation via methyl migration from aluminum to the corresponding imino carbon in L1aryl; in solution, the restricted rotation of the pendant naphthyl group in 1 confers inequivalent methyl ligand environments. The ring opening polymerization of ε-caprolactone employing 1, in the presence of benzyl alcohol, proceeded efficiently at 30 °C producing polymers of narrow molecular weight distribution with the catalytic activities dependent on the nature of the substituent located at the 4-position of the N-aryl group with the most electron donating i-Pr derivative exhibiting the highest activity (1b > 1a > 1c); at 50 °C 1b mediates 100% conversion of the monomer to polycaprolactone (poly(CL)) in one hour. In addition to 1a, 1b and 1c, the single crystal X-ray structures are reported for L1dipp and L1tripp. 2015-12-18T15:53:29Z Analytical Applications of MIPs in Diagnostic Assays: Future perspectives Whitcombe, Michael J. Bedwell, Thomas S. http://hdl.handle.net/2381/36110 2015-12-19T03:19:00Z 2015-12-18T15:47:15Z Title: Analytical Applications of MIPs in Diagnostic Assays: Future perspectives Authors: Whitcombe, Michael J.; Bedwell, Thomas S. Abstract: Many efforts have been made to produce artificial materials with biomimetic properties for applications in binding assays. Among these efforts, the technique of molecular imprinting has received much attention because of the high selectivity obtainable for molecules of interest, robustness of the produced polymers, simple and short synthesis, and excellent cost efficiency. In this review, progress in the field of molecularly imprinted sorbent assays is discussed—with a focus on work conducted from 2005 to date. 2015-12-18T15:47:15Z Instrument intercomparison of glyoxal, methyl glyoxal and NO2 under simulated atmospheric conditions Thalman, R. Baeza-Romero, M. T. Ball, S. M. Borras, E. Daniels, M. J. S. Goodall, I. C. A. Henry, S. B. Karl, T. Keutsch, F. N. Kim, S. Mak, J. Monks, P. S. Munoz, A. Orlando, J. Peppe, S. Rickard, A. R. Rodenas, M. Sanchez, P. Seco, R. Su, L. Tyndall, G. Vazquez, M. Vera, T. Waxman, E. Volkamer, R. http://hdl.handle.net/2381/36104 2015-12-19T03:19:26Z 2015-12-18T12:16:06Z Title: Instrument intercomparison of glyoxal, methyl glyoxal and NO2 under simulated atmospheric conditions Authors: Thalman, R.; Baeza-Romero, M. T.; Ball, S. M.; Borras, E.; Daniels, M. J. S.; Goodall, I. C. A.; Henry, S. B.; Karl, T.; Keutsch, F. N.; Kim, S.; Mak, J.; Monks, P. S.; Munoz, A.; Orlando, J.; Peppe, S.; Rickard, A. R.; Rodenas, M.; Sanchez, P.; Seco, R.; Su, L.; Tyndall, G.; Vazquez, M.; Vera, T.; Waxman, E.; Volkamer, R. Abstract: The α-dicarbonyl compounds glyoxal (CHOCHO) and methyl glyoxal (CH[Subscript: 3]C(O)CHO) are produced in the atmosphere by the oxidation of hydrocarbons and emitted directly from pyrogenic sources. Measurements of ambient concentrations inform about the rate of hydrocarbon oxidation, oxidative capacity, and secondary organic aerosol (SOA) formation. We present results from a comprehensive instrument comparison effort at two simulation chamber facilities in the US and Europe that included nine instruments, and seven different measurement techniques: broadband cavity enhanced absorption spectroscopy (BBCEAS), cavity-enhanced differential optical absorption spectroscopy (CE-DOAS), white-cell DOAS, Fourier transform infrared spectroscopy (FTIR, two separate instruments), laser-induced phosphorescence (LIP), solid-phase micro extraction (SPME), and proton transfer reaction mass spectrometry (PTR-ToF-MS, two separate instruments; for methyl glyoxal only because no significant response was observed for glyoxal). Experiments at the National Center for Atmospheric Research (NCAR) compare three independent sources of calibration as a function of temperature (293–330 K). Calibrations from absorption cross-section spectra at UV-visible and IR wavelengths are found to agree within 2% for glyoxal, and 4% for methyl glyoxal at all temperatures; further calibrations based on ion–molecule rate constant calculations agreed within 5% for methyl glyoxal at all temperatures. At the European Photoreactor (EUPHORE) all measurements are calibrated from the same UV-visible spectra (either directly or indirectly), thus minimizing potential systematic bias. We find excellent linearity under idealized conditions (pure glyoxal or methyl glyoxal, R[Superscript: 2] > 0.96), and in complex gas mixtures characteristic of dry photochemical smog systems (o-xylene/NO[Subscript: x] and isoprene/NOx, R[Superscript: 2] > 0.95; R2 ∼ 0.65 for offline SPME measurements of methyl glyoxal). The correlations are more variable in humid ambient air mixtures (RH > 45%) for methyl glyoxal (0.58 < R[Superscript: 2] < 0.68) than for glyoxal (0.79 < R[Superscript: 2] < 0.99). The intercepts of correlations were insignificant for the most part (below the instruments' experimentally determined detection limits); slopes further varied by less than 5% for instruments that could also simultaneously measure NO[Subscript: 2]. For glyoxal and methyl glyoxal the slopes varied by less than 12 and 17% (both 3-σ) between direct absorption techniques (i.e., calibration from knowledge of the absorption cross section). We find a larger variability among in situ techniques that employ external calibration sources (75–90%, 3-σ), and/or techniques that employ offline analysis. Our intercomparison reveals existing differences in reports about precision and detection limits in the literature, and enables comparison on a common basis by observing a common air mass. Finally, we evaluate the influence of interfering species (e.g., NO[Subscript: 2], O[Subscript: 3] and H[Subscript: 2]O) of relevance in field and laboratory applications. Techniques now exist to conduct fast and accurate measurements of glyoxal at ambient concentrations, and methyl glyoxal under simulated conditions. However, techniques to measure methyl glyoxal at ambient concentrations remain a challenge, and would be desirable. 2015-12-18T12:16:06Z Intercomparison of measurements of NO2 concentrations in the atmosphere simulation chamber SAPHIR during the NO3Comp campaign Fuchs, H. Ball, Stephen Malcolm Bohn, B. Brauers, T. Cohen, R. C. Dorn, H-P. Dube, W. P. Fry, J. L. Haeseler, R. Heitmann, U. Jones, R. L. Kleffmann, J. Mentel, T. F. Muesgen, P. Rohrer, F. Rollins, A. W. Ruth, A. A. Kiendler-Scharr, A. Schlosser, E. Shillings, A. J. L. Tillmann, R. Varma, R. M. Venables, D. S. Tapia, G. V. Wahner, A. Wegener, R. Wooldridge, P. J. Brown, S. S. http://hdl.handle.net/2381/36101 2015-12-19T03:18:43Z 2015-12-18T12:03:56Z Title: Intercomparison of measurements of NO2 concentrations in the atmosphere simulation chamber SAPHIR during the NO3Comp campaign Authors: Fuchs, H.; Ball, Stephen Malcolm; Bohn, B.; Brauers, T.; Cohen, R. C.; Dorn, H-P.; Dube, W. P.; Fry, J. L.; Haeseler, R.; Heitmann, U.; Jones, R. L.; Kleffmann, J.; Mentel, T. F.; Muesgen, P.; Rohrer, F.; Rollins, A. W.; Ruth, A. A.; Kiendler-Scharr, A.; Schlosser, E.; Shillings, A. J. L.; Tillmann, R.; Varma, R. M.; Venables, D. S.; Tapia, G. V.; Wahner, A.; Wegener, R.; Wooldridge, P. J.; Brown, S. S. Abstract: NO[Subscript: 2] concentrations were measured by various instruments during the NO3Comp campaign at the atmosphere simulation chamber SAPHIR at Forschungszentrum Jülich, Germany, in June 2007. Analytical methods included photolytic conversion with chemiluminescence (PC-CLD), broadband cavity ring-down spectroscopy (BBCRDS), pulsed cavity ring-down spectroscopy (CRDS), incoherent broadband cavity-enhanced absorption spectroscopy (IBB\-CEAS), and laser-induced fluorescence (LIF). All broadband absorption spectrometers were optimized for the detection of the main target species of the campaign, NO[Subscript: 3], but were also capable of detecting NO[Subscript: 2] simultaneously with reduced sensitivity. NO[Subscript: 2] mixing ratios in the chamber were within a range characteristic of polluted, urban conditions, with a maximum mixing ratio of approximately 75 ppbv. The overall agreement between measurements of all instruments was excellent. Linear fits of the combined data sets resulted in slopes that differ from unity only within the stated uncertainty of each instrument. Possible interferences from species such as water vapor and ozone were negligible under the experimental conditions. 2015-12-18T12:03:56Z Ionic Liquids: Potential Electrolytes for Electrochemical Applications Zein El Abedin, S. Ryder, K. S. Höfft, O. Farag, H. K. http://hdl.handle.net/2381/36072 2015-12-18T03:05:51Z 2015-12-17T11:41:46Z Title: Ionic Liquids: Potential Electrolytes for Electrochemical Applications Authors: Zein El Abedin, S.; Ryder, K. S.; Höfft, O.; Farag, H. K. 2015-12-17T11:41:46Z Crystal structure of 4,6-diamino-2-sulfanylidene-1,2-dihydropyridine-3-carbonitrile Mohamed, S. K. Akkurt, M. Singh, Kuldip Hussein, B. R. M. Albayatif, Mustafa R. http://hdl.handle.net/2381/36038 2015-12-11T03:05:24Z 2015-12-10T10:01:02Z Title: Crystal structure of 4,6-diamino-2-sulfanylidene-1,2-dihydropyridine-3-carbonitrile Authors: Mohamed, S. K.; Akkurt, M.; Singh, Kuldip; Hussein, B. R. M.; Albayatif, Mustafa R. Abstract: The title compound, C6H6N4S, crystallizes with two independent molecules, A and B, in the asymmetric unit. Both independent molecules are almost planar [maximum deviations of 0.068 (6) A˚ in molecule A and 0.079 (6) A˚ in molecule B]. In the crystal, molecules A and B are linked by N—HS, N—HN and C—HS hydrogen bonds, forming a threedimensional network. Keyword Description: Supporting information for this paper is available from the IUCr electronic archives (Reference: HG5399). 2015-12-10T10:01:02Z Metabolite profiling of the ripening of Mangifera indica L. cv. 'Tommy Atkins' by real-time measurement of volatile organic compounds Monks, Paul Steven White, I. R. Blake, R. Taylor, A. http://hdl.handle.net/2381/36036 2016-08-23T11:41:43Z 2015-12-10T09:44:05Z Title: Metabolite profiling of the ripening of Mangifera indica L. cv. 'Tommy Atkins' by real-time measurement of volatile organic compounds Authors: Monks, Paul Steven; White, I. R.; Blake, R.; Taylor, A. Abstract: Real-time profiling of mango ripening based on proton transfer reaction-time of flight-mass spectrometry (PTR–ToF–MS) of small molecular weight volatile organic compounds (VOCs), is demonstrated using headspace measurements of 'Tommy Atkins' mangoes. VOC metabolites produced during the ripening process were sampled directly, which enabled simultaneous and rapid detection of a wide range of compounds. Headspace measurements of 'Keitt' mangoes were also conducted for comparison. A principle component analysis of the results indicated that several mass channels were not only key to the ripening process but could also be used to distinguish between mango cultivars. The identities of 22 of these channels, tentatively speciated using contemporaneous GC–MS measurements of sorbent tubes, are rationalized through examination of the biochemical pathways that produce volatile flavour components. Results are discussed with relevance to the potential of headspace analysers and electronic noses in future fruit ripening and quality studies. 2015-12-10T09:44:05Z Removal of casting defects from CMSX-4 (R) and CMSX-10 (R) alloys by electropolishing in a novel electrolyte; Deep Eutectic Solvent Dsouza, N Appleton, M Ballantyne, Andrew Cook, Amy Harris, Robert Ryder, Karl S http://hdl.handle.net/2381/36028 2015-12-09T03:08:15Z 2015-12-08T16:31:09Z Title: Removal of casting defects from CMSX-4 (R) and CMSX-10 (R) alloys by electropolishing in a novel electrolyte; Deep Eutectic Solvent Authors: Dsouza, N; Appleton, M; Ballantyne, Andrew; Cook, Amy; Harris, Robert; Ryder, Karl S Editors: Guedou, J. Y.; Chone, J. Abstract: Here we describe the use of environmentally benign Deep Eutectic Solvents (DESs) to electropolish oxide casting scale from Ni based superalloy turbine blades. These new electrolytes are a viable alternative to hazardous and aggressive aqueous acids and etchants currently used to process these components. In addition we show that the DES electrolytes selectively expose the underlying surface structure of these superalloys. We demonstrate the ability of these electrolytes to preferentially etch either γ or γ′ phases depending on the choice of electrolyte formulation and the applied potential during the electrolytic etch on CMSX-4® and CMSX-10® alloys. 2015-12-08T16:31:09Z Exploring new dimensions in cadaveric decomposition odour analysis Stefanuto, P.-H. Perrault, K. A. Lloyd, R. M. Stuart, B. Rai, T. Forbes, S. L. Focant, J.-F. http://hdl.handle.net/2381/36015 2015-12-09T03:08:25Z 2015-12-08T12:31:32Z Title: Exploring new dimensions in cadaveric decomposition odour analysis Authors: Stefanuto, P.-H.; Perrault, K. A.; Lloyd, R. M.; Stuart, B.; Rai, T.; Forbes, S. L.; Focant, J.-F. Abstract: This study demonstrates the first documented use of comprehensive two-dimensional gas chromatography – high-resolution time-of-flight mass spectrometry (GC×GC-HRTOFMS) for volatile organic compound analysis in the forensic sciences. High-resolution mass spectral data provided higher confidence in analyte identification. GC×GC-HRTOFMS will be valuable for future studies of decomposition odour and other complex volatile matrices. 2015-12-08T12:31:32Z Organo-palladium(II) complexes bearing unsymmetrical N,N,N-pincer ligands: synthesis, structures and oxidatively induced coupling reactions Wright, Luka A. Hope, Eric G. Solan, Gregory A. Cross, Warren B. Singh, Kuldip http://hdl.handle.net/2381/36014 2015-12-09T03:08:16Z 2015-12-08T12:23:57Z Title: Organo-palladium(II) complexes bearing unsymmetrical N,N,N-pincer ligands: synthesis, structures and oxidatively induced coupling reactions Authors: Wright, Luka A.; Hope, Eric G.; Solan, Gregory A.; Cross, Warren B.; Singh, Kuldip Abstract: The 2-(2′-aniline)-6-imine-pyridines, 2-(C6H4-2′-NH2)-6-(CMe=NAr)C5H3N (Ar = 4-i-PrC6H4 (HL1a), 2,6-i-Pr2C6H3 (HL1b)), have been synthesised via sequential Stille cross-coupling, deprotection and condensation steps from 6-tributylstannyl-2-(2-methyl-1,3-dioxolan-2-yl)pyridine and 2-bromonitrobenzene. The palladium(II) acetate N,N,N-pincer complexes, [{2-(C6H4-2′-NH)-6-(CMe=NAr)C5H3N}Pd(OAc)] (Ar = 4-i-PrC6H4 (1a), 2,6-i-Pr2C6H3 (1b)), can be prepared by reacting HL1 with Pd(OAc)2 or, in the case of 1a, more conveniently by the template reaction of ketone 2-(C6H4-2′-NH2)-6-(CMe=O)C5H3N, Pd(OAc)2 and 4-isopropylaniline; ready conversion of 1 to their chloride analogues, [{2-(C6H4-2′-NH)-6-(CMe=NAr)C5H3N}PdCl] (Ar = 4-i-PrC6H4 (2a), 2,6-i-Pr2C6H3 (2b)), has been demonstrated. The phenyl-containing complexes, [{2-(C6H4-2′-NH)-6-(CMe=NAr)C5H3N}PdPh] (Ar = 4-i-PrC6H4 (3a), 2,6-i-Pr2C6H3 (3b)), can be obtained by treating HL1 with (PPh3)2PdPh(Br) in the presence of NaH or with regard to 3a, by the salt elimination reaction of 2a with phenyllithium. Reaction of 2a with silver tetrafluoroborate or triflate in the presence of acetonitrile allows access to cationic [{2-(C6H4-2′-NH)-6-(CMe=N(4-i-PrC6H4)C5H3N}Pd(NCMe)][X] (X = BF4 (4), X = O3SCF3 (5)), respectively; the pyridine analogue of 5, [{2-(C6H4-2′-NH)-6-(CMe=N(4-i-PrC6H4)C5H3N}Pd(NC5H5)][O3SCF3] (5′), is also reported. Oxidation of phenyl-containing 3a with one equivalent of 1-chloromethyl-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate) (Selectfluor™) in acetonitrile at low temperature leads to a new palladium species that slowly decomposes to give 4 and biphenyl; biphenyl formation is also observed upon reaction of 3a with XeF2. However, no such oxidatively induced coupling occurs when using 3b. Single crystal X-ray diffraction studies have been performed on HL1b, 1a, 1b, 2a, 2b, 3a, 3b and 5′. Description: Electronic supplementary information (ESI) available. CCDC 1043191–1043198. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c5dt00216h 2015-12-08T12:23:57Z O,N,N-pincer ligand effects on oxidatively induced carbon-chlorine coupling reactions at palladium Wright, Luka A. Hope, Eric G. Solan, Gregory A. Cross, Warren B. Singh, Kuldip http://hdl.handle.net/2381/36013 2015-12-09T03:08:14Z 2015-12-08T12:13:09Z Title: O,N,N-pincer ligand effects on oxidatively induced carbon-chlorine coupling reactions at palladium Authors: Wright, Luka A.; Hope, Eric G.; Solan, Gregory A.; Cross, Warren B.; Singh, Kuldip Abstract: The syntheses of two families of sterically tuneable O,N,N pro-ligands are reported, namely the 2-(phenyl-2'-ol)-6-imine-pyridines, 2-(C6H4-2'-OH),6-(CMe=NAr)C5H3N [Ar = 4-i-PrC6H4 (HL1(a)), 2,6-i-Pr2C6H3 (HL1(b))] and the 2-(phenyl-2'-ol)-6-(amino-prop-2-yl)pyridines, 2-(C6H4-2'-OH),6-(CMe2NHAr)C5H3N [Ar = 4-i-PrC6H4 (HL2(a)), 2,6-i-Pr2C6H3 (HL2(b))], using straightforward synthetic approaches and in reasonable overall yields. Interaction of HL1(a/c) and HL2(a/b) with palladium(II) acetate affords the O,N,N-pincer complexes, [{2-(C6H4-2'-O)-6-(CMe=NAr)C5H3N}Pd(OAc)] (Ar = 4-i-PrC6H4 (1a), 2,6-i-Pr2C6H3 (1b)) and [{2-(C6H4-2'-O)-6-(CMe2NHAr)C5H3N}Pd(OAc)] (Ar = 4-i-PrC6H4 (2a), 2,6-i-Pr2C6H3 (2b)), which can be readily converted to their chloride derivatives, [{2-(C6H4-2'-O)-6-(CMe=NAr)C5H3N}PdCl] (Ar = 4-i-PrC6H4 (3a), 2,6-i-Pr2C6H3 (3b)) and [{2-(C6H4-2'-O)-6-(CMe2NHAr)C5H3N}PdCl] (Ar = 4-i-PrC6H4 (4a), 2,6-i-Pr2C6H3 (4b)), respectively, on reaction with an aqueous sodium chloride solution. Treating each of 3a, 3b, 4a and 4b with two equivalents of di-p-tolyliodonium triflate at 100 °C in a toluene/acetonitrile mixture affords varying amounts of 4-chlorotoluene along with the 4-iodotoluene by-product with the conversions highly dependent on the steric and backbone properties of the pincer complex employed (viz. 4a > 3a > 4b > 3b); notably, the least sterically bulky and most flexible amine-containing 4a reaches 90% conversion to 4-chlorotoluene in 15 h as opposed to 17% for imine-containing 3b. In the case of 3a, the inorganic palladium species recovered from the reaction has been identified as the Pd(II) salt [{2-(C6H4-2'-O)-6-(CMe=N(4-i-PrC6H4)C5H3N}Pd(NCMe)][O3SCF3] (5a), which was independently prepared by the reaction of 3a with silver triflate in acetonitrile. Single crystal X-ray structures are reported for HL1(a), HL2(a), 1a, 1b, 2a, 2b, 3a and 5a. Description: CCDC 1040521–1040528. For crystallographic data in CIF or other electronic format see DOI: 10.1039/c5dt00062a 2015-12-08T12:13:09Z


text:
The Art of Gladys Goldstein
Paintings, Handmade Papers, Candy Wrappers, and More
Capturing the Essence
Opening May 3, 2004
University of Maryland University College
Arts program Gallery
Baltimore artist Gladys Goldstein wrote, "My canvases are not explicit statements, but hints of things that are, or were, or might have been—of memories, of feelings."
Although her work is abstract, Goldstein's primary source of inspiration is nature. She creates the impression of light emanating from within her paintings and captures the essence, rather than the appearance, of the natural world. In an artistic career spanning six decades, Goldstein has worked with oils, acrylics, watercolor, drawing, collage, and handmade paper. Goldstein was also the first American artist to use the Mexican printmaking technique mixographia to create and reproduce textured prints.
The exhibition Capturing the Essence: The Art of Gladys Goldstein celebrates the opening of the permanent Gladys Goldstein Gallery in the UMUC Inn and Conference Center. This gallery will be the university's first permanent display of contemporary abstract art.
Art Events
Opening Reception
Saturday, November 5, 2016
3–5 p.m.
Exhibition Dates
October 30, 2016–October 29, 2017
Third Biennial Maryland Regional Juried Art Exhibition
Exhibition Dates
September 18–December 31, 2016
All That's Art: Faculty Art Invitational 2016
Exhibition Dates
May 8–July 31, 2016
UMUC Arts Program Gallery,
Lower Level
College Park Marriott Hotel & Conference Center

subset: commoncrawl