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Solid-state astrochemistry in star-forming regions
No full textSurface-catalysed chemical reactions, the molecules they form, and the implications for star formation were key themes in an international workshop on “Solid-state chemistry in star-forming regions” at the Lorentz Centre, Leiden University, the Netherlands from 14–17 April 2003. Helen Fraser, David Williams, Ian Sims, Anita Richards and Jeremy Yates report
Radically different kinetics at low temperatures
No full text"""The use of the CRESU (Cinétique de Réaction en Ecoulement Supersonique Uniforme, or Reaction Kinetics in Uniform Supersonic Flow) technique coupled with pulsed laser photochemical kinetics methods has shown that reactions involving radicals can be very rapid at temperatures down to 10 K or below. The results have had a major impact in astrochemistry and planetology, as well as proving an exacting test for theory.\footnote{H. Sabbah, L. Biennier, I. R. Sims, Y. Georgievskii, S. J. Klippenstein, I. W. M. Smith, Science \textbf{317}, 102 (2007).} The technique has also been applied to the formation of transient complexes of interest both in atmospheric chemistry\footnote{S. D. Le Picard, M. Tizniti, A. Canosa, I. R. Sims, I. W. M. Smith, Science \textbf{328}, 1258 (2010).} and combustion.\footnote{H. Sabbah, L. Biennier, S. J. Klippenstein, I. R. Sims, B. R. Rowe, J. Phys. Chem. Lett. \textbf{1}, 2962 (2010).}
Until now, all of the chemical reactions studied in this way have taken place on attractive potential energy surfaces with no overall barrier to reaction. The F + H HF + H reaction does possess a substantial energetic barrier ( 800 K), and might therefore be expected to slow to a negligible rate at very low temperatures. In fact, this H-atom abstraction reaction does take place efficiently at low temperatures due entirely to tunneling. I will report direct experimental measurements of the rate of this reaction down to a temperature of 11 K, in remarkable agreement with state-of-the-art quantum reactive scattering calculations by François Lique (Université du Havre) and Millard Alexander (University of Maryland). \footnote{ M. Tizniti, S. D. Le Picard, F. Lique, C. Berteloite, A. Canosa, M. H. Alexander, I. R. Sims, Nature Chemistry \textbf{6}, 141 (2014).}
It is thought that long chain cyanopolyyne molecules H(C)CN may play an important role in the formation of the orange haze layer in Titan’s atmosphere. The longest carbon chain molecule observed in interstellar space, HCN, is also a member of this series. I will present new results, obtained in collaboration with Jean-Claude Guillemin (Ecole de Chimie de Rennes) and Stephen Klippenstein (Argonne National Labs), on reactions of CH, CN\footnote{S. Cheikh Sid Ely, S. B. Morales, J. C. Guillemin, S. J. Klippenstein, I. R. Sims, J. Phys. Chem. A \textbf{117}, 12155 (2013).} and CN radicals (using a new LIF scheme by Hoshina and Endo\footnote{K. Hoshina, Y. Endo, J. Chem. Phys. \textbf{127}, 184304 (2007).}) which contribute to the low temperature formation of (cyano)polyynes."""Submitted by Mary Schlembach ([email protected]) on 2014-11-21T21:55:38Z
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Visualisation of amphetamine contamination in fingerprints using tof-sims technique
No full textTime-of-flight secondary ion mass spectrometry (TOF-SIMS) was applied to detect traces of amphetamine on fingerprints. In the present study, three different lift tapes and latent powder fingerprints were tested. The obtained results show that it is possible to identify traces of a drug as well as its distribution over the tested fingerprint after its transfer from the primary base onto an adhesive lifter (secondary base). Moreover, images obtained by the TOF-SIMS technique enable the observation of very small areas of the analysed fingerprint as well as the identification of micro-objects (residues of a contaminant) that were left on the fingerprint. The use of the black latent fingerprint powder did not interfere with the TOF-SIMS analysis, which makes it possible to effectively use this technique to study the traces of substances on the revealed fingerprints.ChemE/Advanced Soft Matte
decapetala
No full textMentzelia decapetala (Pursh ex Sims) Urban & Gilg ex Gilgten-petalled blazing star;ten-petalled evening star;ten-petalled stickleaf;gumbo-lily;sand-lilymentzélie à dix pétalesdecapetalaWarner District, off highway 36, south side of Chin Coulee ReservoirDry Mixed Grass Ecoregion: prairie - very dry disturbed slope of road cu
Universal Processor Architecture for Biomedical Implants: The SiMS Project
No full textHEALTHCARE in the 21st century is changing rapidly. In advanced countries, in particular, healthcare is moving from a public to a more personalized nature. However, the costs of healthcare worldwide are increasing every year. Better use of technology can and should be used to get control of these costs. At the same time, implants have clearly benefitted from the astounding technology-miniaturization trends of late, boasting smaller sizes, lower power consumption and increased performance of the transistor devices. However, such advances do not come for free. Adverse effects in current implant designs are being witnessed, such as increasing power consumption, absence of design for reliability and highly application-specific nature. Operating under the assumption that implants will constitute an important means towards improved, personal healthcare and, in view of the aforementioned design phenomena, we believe that a new paradigm in implant design is required. This dissertation establishes the concept of Smart implantable Medical Systems (SiMS). SiMS is a systematic approach – a framework – for providing biomedical researchers and, hopefully, industry with a toolbox of ready-to-use, highly reliable implant sub-systems and models in order to construct optimal implants for various medical applications. The SiMS framework has to guarantee essential attributes, such as high dependability, modular design, ultra-low power consumption and miniature size. Having defined the SiMS framework, this dissertation is, then, concerned with exploring the optimal microarchitectural details of a crucial SiMS component: the SiMS processor. Contrary to the current state of the art, this processor aspires to be a new universal, low-power and low-cost processor and capable of efficiently serving a wide range of diverse implant applications.Computer Science and EngineeringElectrical Engineering, Mathematics and Computer Scienc
Correlation of ToF-SIMS surface analysis with particle hydrophobicity and flotation
No full textxvi, 87 pagesill. (some col.)Includes bibliographical references.In minerals processing, flotation is the operation where valuable mineral particles from a ground ore are selectively recovered by attachment to air bubbles rising to the top of the flotation cell. The chemistry of the mineral surfaces plays a critical role on the efficiency of this process. However, how the surface chemistry, and hence hydrophobicity, vary with flotation response is not well understood. This thesis seeks to understand how the chemistry ofthe mineral surfaces correlates with the hydrophobicity surface property and with mineral recovery, the aim being to develop tools for a better understanding of the flotation process.
In this work, the surface chemistry of chalcopyrite (CuFeS2) mineral particles with a dithiophosphate collector was examined by Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) and statistically correlated with hydrophobicity, as measured by the water contact angle. A statistical linear model has been derived that calculates the contact angle based on the surface chemical contribution of key ToF-SIMS secondary ion signals. This is a new method, and is capable of determining the contact angle of surface regions down to a few micrometres (e.g., at the scale of individual particles). The ToF-SIMS method may also be used to analyse flat surfaces, enabling rapid surface chemistry-hydrophobicity correlations to be performed on a wide range of mineral and material systems.
In this thesis, a statistical strategy was developed for predicting the surface chemistry contribution to the flotation recovery of chalcopyrite by ToF-SIMS analysis of a feed, for constant hydrodynamic conditions. The predicted recovery represented the maximum potential floatability based on particle surface chemistry. The comparison between the predicted and real recoveries revealed the impact of hydrodynamics on the flotation response; fine and coarse particle sizes showed the largest differences, highlighting the hydrodynamic effect of particle size in flotation. The extraction of this inforrnation in a flotation process can help in optimizing hydrodynamic flotation conditions.Thesis (PhDEngineering(Minerals&Materials))--University of South Australia, 201
'A bright memory to remain' : the life and works of Charles Sims RA (1873-1928)
No full textThis thesis investigates the life and work of the English painter Charles Sims RA (1873-1928). It takes the form of a monograph and examines key themes of Sims' career within a chronological framework. The study makes consistent reference to the Sims Archive — the artist's studio contents recently brought to light by the author in negotiation with the artist's family and currently in the possession of Northumbria University. For the first time Sims' working practices and motivations have been explored in detail, thus contributing to knowledge of this particular neglected painter and more generally allowing some additional insight into the problems besetting and opportunities afforded to British artists of his generation. Sims' career spanned a transitional period in British art history which is currently being reassessed by art historians: the debates surrounding the effects of European modernism on British art, the inevitable impact of the Great War and the search during the 1920s for a visual language appropriate to modern life. Sims negotiated disparate experiences and preoccupations in an interesting way, and produced a stylistically diverse body of work in his continued search, I argue, for an alternative to modern reality. He attempted the combination of ancient religions, past art and modern experience into pictorial idylls that were simultaneously familiar and unattainable. The thesis aims to explore Sims' inspiration and reassesses his career within the context of his better known contemporaries by cross-referencing information held in national and international collections, libraries and archives with the hitherto unseen material here
Synthesis of furanosesquiterpenoid natural products
No full textThe effect of addition of a catalytic quantity of a crown ether in the reaction of a phosphonate anion with a carbonyl compound (Wadsworth-Emmons reaction) has been studied and found to greatly facilitate this reaction. This modification of the Wadsworth-Emmons reaction, using a catalytic amount of 15-crown-5, has been employed in the synthesis of the naturally occurring furanosesquiterpene Pallescensin-E. The structure of this compound has been confirmed by comparison of its spectral data with that of the synthesised isomer, 4,l0-dihydro-7,8-dimethyl 10H-benzof4,5Jcycloheptafl,2-bJ furan.Homosesquirosefuran, an analogue of the naturally occurring furanosesquiterpene Sesquirosefuran, has been synthesised via the dianion of methylacetoacetate.An approach to the synthesis of Pinguisone (a component of the essential oil of the liverwort Aneura pinguis)has been attempted employing two Diels-Alder reactions to generate the four cis-methyl groups found in the natural product.In a study of the reaction of n-(2-methylallyl)nickel bromide complex with a range of epoxides, this complex was found not only to react with reactive epoxides (e.g. styrene epoxide) but also with less reactive propylene epoxide.Substrates for possible intramolecular n-allylnickel cyclisation to generate an a-methylene-6-valerolactone ring system have been prepared
Library licensing and criminal law: The Aaron Swartz case
No full textReviews the ways that library licenses for subscription content contributed to criminal charges against activist Aaron Swartz, when he downloaded content from JSTOR on the MIT campus. (Author Note: This piece predates Swartz's death by suicide in 2013.)Sims, Nancy, A. (2011). Library licensing and criminal law: The Aaron Swartz case. Retrieved from the University Digital Conservancy, 10.5860/crln.72.9.8637
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