Download or read book An Investigation Into the Interaction of Some Sulfur Containing Molecules with Metal Surfaces written by Hefin Griffiths and published by . This book was released on 1999 with total page 232 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Site specific Chemistry of Sulfur containing Amino Acids on Si 111 3 3 Ag written by Hanieh Farkhondeh Borazjani and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The interfacial interactions and film growth mechanisms of sulfur-containing amino acids on Si(111)-√3×√3-Ag are investigated by using x-ray photoelectron spectroscopy (XPS) and scanning tunneling microscopy (STM) at room temperature and at elevated temperature under ultrahigh vacuum condition. The complementary density functional theory (DFT) calculations with dispersion correction are used to provide precise modeling of the equilibrium adsorption configurations of biomolecules. Cysteine is found to chemisorb initially at surface defects where its island growth fronts further propagate onto terrace regions exhibiting coral-reef-like nanostructures. The lower-step edges and the antiphase boundaries are found to be the preferred adsorption sites followed by upper-step edges and terrace sites. Chemisorption of interfacial cysteine monolayer occurs through S-H cleavage and S-Ag linkage. The zwitterionic hydrogen bonding governs the intermolecular interactions in the interfacial layer, which further grows to zwitterionic multilayer. Our DFT calculations support the experimental results for chemisorption of single molecules to multimers through S-Ag covalent bonding and intermolecular zwitterionic hydrogen bonding. In addition, Ag bridge sites are found to be the most favourable adsorption sites on the surface terraces. At elevated temperatures, cysteine adspecies are found to transform the highly ordered single-atom-thick Si(111)-√3×√3-Ag overlayer into Ag agglomerates of nanometer sizes. This phenomenon offers an interesting approach to converting monoatomic silver silicide layers to silver nanoclusters and quantum dots for chemical sensing and catalysis applications. Methionine, on the other hand, does not chemisorb on Si(111)-√3×√3-Ag due to the termination of its sulfur atom by a methyl group in its methylthio methylene side chain. A minority of methionine adspecies are found to chemisorb through a dehydrogenated amino group most likely at defect sites, step edges and antiphase boundaries. Self-assembled one-dimensional molecular wires are observed at room temperature and at lower temperatures in our variable-temperature STM study, while the chemical state of these molecular wires is found to be zwitterionic by XPS. Our large-scale DFT calculations further support the zwitterionic dimer row structures of the molecular wires. To demonstrate the molecular size effect, the adsorption mechanism of glycine on Si(111)-√3×√3-Ag is also studied. All three amino acids appear to induce metallic Ag 3d features at elevated temperature, indicating the formation of metallic agglomerates. The Si(111)-√3×√3-Ag surface offers a unique platform for developing not only self-assembled molecular nanostructures but also metal nanoclusters and agglomerates for potential applications in catalysis. The Si(111)-√3×√3-Ag surface contains a number of defects, notably step edges and antiphase boundaries, that could significantly affect the adsorption and other surface properties. Detailed understanding of the relations between their structural configurations and these surface properties is of fundamental interest to further unraveling the many unique processes found for this intricate surface. Using first-principle quantum mechanical calculations based on DFT, the equilibrium geometries of the step edge and antiphase boundary are calculated and found to exhibit a one-dimensional chain of Ag trimers on both types of defect sites. Unlike the monolayer coverage in the terrace regions, the Ag:Si stoichiometric ratio is found to be 4:3 at the step edge. This ratio is calculated to be 1:1 for the antiphase boundary (and for the terrace). The total densities of states calculated for the step edge, antiphase boundary, and terrace models exhibit surface states near the Fermi level. The mid-gap state found for the step edge appears to have a more intense density of state and to locate closer to the Fermi level. The corresponding calculation of partial densities of states reveals different contributions of Ag and Si atoms at defect sites. Mid-gap states are known to improve the optical properties of materials such as photon absorption and transfer. As the Si(111)-√3×√3-Ag surface defects promote the mid-gap states and considering their adsorption to be the most favourable, they are expected to play a crucial role in designing applications in (photo) catalysis and chemical sensing.
Download or read book First principles Density Functional Theory Study of Sulfur Oxide Chemistry on Transition Metal Surfaces written by Lin, Xi and published by . This book was released on 2003 with total page 310 pages. Available in PDF, EPUB and Kindle. Book excerpt: (Cont.) The thesis closes with a chemical selectivity analysis of the effects of catalyst particle size on chemisorption of gas-phase adatoms. In summary, the presentation of the chemistry of sulfur-containing molecules in this work is aimed at a scientific understanding of the strong poisoning effects in heterogeneous catalysis. However, the chemistry of sulfur-containing molecules has many more fundamental implications, such as in designing novel re-conjugated conducting devices for quantum computers. The underlying hybrid bonding flexibility of sulfur allows it to simultaneously bind to heavy transition metal atoms (such as Pt, Cu, or Au) and first-row atoms (such as oxygen atoms or carbon atoms in organic molecules).
Download or read book Energy Research Abstracts written by and published by . This book was released on 1995 with total page 782 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Chalcogens Advances in Research and Application 2011 Edition written by and published by ScholarlyEditions. This book was released on 2012-01-09 with total page 2783 pages. Available in PDF, EPUB and Kindle. Book excerpt: Chalcogens: Advances in Research and Application: 2011 Edition is a ScholarlyEditions™ eBook that delivers timely, authoritative, and comprehensive information about Chalcogens. The editors have built Chalcogens: Advances in Research and Application: 2011 Edition on the vast information databases of ScholarlyNews.™ You can expect the information about Chalcogens in this eBook to be deeper than what you can access anywhere else, as well as consistently reliable, authoritative, informed, and relevant. The content of Chalcogens: Advances in Research and Application: 2011 Edition has been produced by the world’s leading scientists, engineers, analysts, research institutions, and companies. All of the content is from peer-reviewed sources, and all of it is written, assembled, and edited by the editors at ScholarlyEditions™ and available exclusively from us. You now have a source you can cite with authority, confidence, and credibility. More information is available at http://www.ScholarlyEditions.com/.
Download or read book Research in Progress written by and published by . This book was released on 1991 with total page 274 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1994 with total page 892 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fiscal Year 1986 Department of Energy Authorization basic Research Programs written by United States. Congress. House. Committee on Science and Technology. Subcommittee on Energy Development and Applications and published by . This book was released on 1985 with total page 1160 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Research Grants Index written by National Institutes of Health (U.S.). Division of Research Grants and published by . This book was released on 1974 with total page 1116 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Research Awards Index written by and published by . This book was released on with total page 1128 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Auger Electron Spectroscopy written by Donald T. Hawkins and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 305 pages. Available in PDF, EPUB and Kindle. Book excerpt: Auger electron spectroscopy is rapidly developing into the single most powerful analytical technique in basic and applied science.for investigating the chemical and structural properties of solids. Its ex plosive growth beginning in 1967 was triggered by the development of Auger analyzers capable of de tecting one atom layer of material in a fraction of a second. Continued growth was guaranteed firstly by the commercial availability of apparatus which combined the capabilities of scanning electron mi croscopy and ion-mill depth profiling with Auger analysis, and secondly by the increasing need to know the atomistics of many processes in fundamental research and engineering applications. The expanding use of Auger analysis was accompanied by an increase in the number of publications dealing with it. Because of the developing nature of Auger spectroscopy, the articles have appeared in many different sources covering diverse disciplines, so that it is extremely difficult to discover just what has or has not been subjected to Auger analysis. In this situation, a comprehensive bibliography is obviou-sly useful to those both inside and outside the field. For those in the field, this bibliography should be a wonderful time saver for locating certain references, in researching a particular topic, or when considering various aspects of instrumentation or data analysis. This bibliography not only provides the most complete listing of references pertinent to surface Auger analysis available today, but it is also a basis for extrapolating from past trends to future expectations.
Download or read book Interfacial Electrochemistry written by Andrzej Wieckowski and published by Routledge. This book was released on 2017-11-22 with total page 1008 pages. Available in PDF, EPUB and Kindle. Book excerpt: This text probes topics and reviews progress in interfacial electrochemistry. It supplies chapter abstracts to give readers a concise overview of individual subjects and there are more than 1500 drawings, photographs, micrographs, tables and equations. The 118 contributors are international scholars who present theory, experimentation and applications.
Download or read book Encyclopedia of Interfacial Chemistry written by and published by Elsevier. This book was released on 2018-03-29 with total page 5276 pages. Available in PDF, EPUB and Kindle. Book excerpt: Encyclopedia of Interfacial Chemistry: Surface Science and Electrochemistry, Seven Volume Set summarizes current, fundamental knowledge of interfacial chemistry, bringing readers the latest developments in the field. As the chemical and physical properties and processes at solid and liquid interfaces are the scientific basis of so many technologies which enhance our lives and create new opportunities, its important to highlight how these technologies enable the design and optimization of functional materials for heterogeneous and electro-catalysts in food production, pollution control, energy conversion and storage, medical applications requiring biocompatibility, drug delivery, and more. This book provides an interdisciplinary view that lies at the intersection of these fields. Presents fundamental knowledge of interfacial chemistry, surface science and electrochemistry and provides cutting-edge research from academics and practitioners across various fields and global regions
Download or read book ACTH Action in the Adrenal Cortex From Molecular Biology to Pathophysiology written by Nicole Gallo-Payet and published by Frontiers Media SA. This book was released on 2017-07-27 with total page 421 pages. Available in PDF, EPUB and Kindle. Book excerpt: By stimulating adrenal gland and corticosteroid synthesis, the adrenocorticotropic hormone (ACTH) plays a central role in response to stress. In this Research Topic, a particular attention has been given to the recent developments on adrenocortical zonation; the growth-promoting activities of ACTH; the various steps involved in acute and chronic regulation of steroid secretion by ACTH, including the effect of ACTH on circadian rhythms of glucocorticoid secretion. The Research Topic also reviews progress and challenges surrounding the properties of ACTH binding to the MC2 receptor (MC2R), including the importance of melanocortin-2 receptor accessory protein (MRAP) in MC2R expression and function, the various intracellular signaling cascades, which involve not only protein kinase A, the key mediator of ACTH action, but also phosphatases, phosphodiesterases, ion channels and the cytoskeleton. The importance of the proteins involved in the cell detoxification is also considered, in particular the effect that ACTH has on protection against reactive oxygen species generated during steroidogenesis. The impact of the cellular microenvironment, including local production of ACTH is discussed, both as an important factor in the maintenance of homeostasis, but also in pathological situations, such as severe inflammation. Finally, the Research Topic reviews the role that the pituitary-adrenal axis may have in the development of metabolic disorders. In addition to mutations or alterations of expression of genes encoding components of the steroidogenesis and signaling pathways, chronic stress and sleep disturbance are both associated with hyperactivity of the adrenal gland. A resulting effect is increased glucocorticoid secretion inducing food intake and weight gain, which, in turn, leads to insulin and leptin resistance. These aspects are described in detail in this Research Topic by key investigators in the field. Many of the aspects addressed in this Research Topic still represent a stimulus for future studies, their outcome aimed at providing evidence of the central position occupied by the adrenal cortex in many metabolic functions when its homeostasis is disrupted. An in-depth investigation of the mechanisms underlying these pathways will be invaluable in developing new therapeutic tools and strategies.
Download or read book Metals Abstracts written by and published by . This book was released on 1990 with total page 1590 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book OAR written by and published by . This book was released on 1967 with total page 570 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fossil Energy Update written by and published by . This book was released on 1986 with total page 774 pages. Available in PDF, EPUB and Kindle. Book excerpt:
