Chemistry Commons^™

Electrochemical Surface-Enhanced Raman Spectroscopy—Current Status And Perspective, Bin Ren, Jian-Feng Li, Yi-Fan Huang, Zhi-Cong Zeng, Zhong-Qun Tian

Journal of Electrochemistry

Electrochemical interface is a very important interface closely related to various energy and life processes. Surface-enhanced Raman scattering was widely used in electrochemistry soon after its discovery to understand the surface bonding,configuration,and orientation of the surface species. In recent 10 years,the fast development of nanoscience and nanotechnology has offered SERS with abundant substrates and characterization methods,which has allowed impressive development of electrochemical SERS. This articles will follow the time line to make systematically overview of SERS on Au and Ag,thin-layer transition-metal SERS,pure transition metal SERS,core-shell SERS and those methods for studying single crystal surfaces,including gap-mode SERS, TERS and SHINERS. Emphasis …

The Mechanism Of 13CoAd/12Co Isotope Exchange At Pt Electrode,A Combined Study By Electrochemical In-Situ Infrared Spectroscopy And Dipole-Dipole Coupling Analysis, Sang-Zi Liang, Shao-Xiong Liu, Ling-Wen Liao, Qian Tao, Jing Kang, Yan-Xia Chen

Journal of Electrochemistry

In this contribution,we have analyzed the IR spectra of saturated CO adlayer at rough Pt film electrode as a function of fractional surface coverage of ¹³CO_ad /¹²CO recorded during ¹³CO_ad /¹²CO isotope exchange process according to dipole-dipole coupling theory and coherent potential approximation. By properly choosing the parameters of adlayer structure and dipole-dipole coupling interaction under coherent potential approximation, we demonstrated that we can successfully simulate the IR spectra as a function of the surface coverage of CO adlayer at rough Pt film electrodes by assuming that CO_ad molecules with low …

Phenomena Characterization Of Energy Materials By X-Ray Absorption Spectroscopy, Ming-Yao Cheng, Chun-Jen Pan, Ju-Hsiang Cheng, Bing-Joe Hwang

Journal of Electrochemistry

The aim of this review is to introduce the characterization of energy materials by X-ray absorption spectroscopy (XAS) . This technique allows us to probe changes in the valance state and the local environment of the targeted element in the active material; thereby,leading to a better understanding of its electrochemical behavior,and hopefully showing the way to improved performance. Here,electrocatalysts for fuel cells and active electrode materials for Li-ion batteries are taken as the examples that illustrate the capability of XAS and allow observation and theory to be correlated with electrochemical phenomena.

In Situ Surface-Enhanced Raman Scattering Spectroscopic Study Of Sulfur Adsorption On Polycrystalline Platinum Electrode Surface, Bolian Xu, In-Su Park, Ying Li, De-Jun Chen, Yuye J. Tong

Journal of Electrochemistry

The paper reports the first in situ surface enhanced Raman scattering (SERS) spectroelectrochemistry study of sulfur adsorption and electro-oxidation on highly roughened polycrystalline Pt surface in both acidic and basic supporting electrolytes. The SERS spectra were taken at a constant electrode potential after accumulative electro-oxidation CVs of the Pt electrode with pre-adsorbed sulfur species and at different electrode potentials that were varied stepwise of the Pt electrode immersed in sulfur-containing electrolytes without pre-adsorbed sulfur species. In both cases,a dominant vibrational band at 299 cm^-1 in acidic electrolyte but at 310 cm^-1 in basic electrolyte was observed,which was assigned …

Studies Of Oxidation Processes Of Adsorbed And Solution Co On Pt(110) Electrode By Cyclic Voltammetry And In Situ Ftirs, Li Tian, Jun-Tao Li, Jin-Yu Ye, Chun-Hua Zhen, Shi-Gang Sun

Journal of Electrochemistry

The oxidation processes of adsorbed CO (COad) and solution phase CO (COsol) on Pt(110) electrode were investigated by cyclic voltammetry and in-situ FTIR spectroscopy. It has revealed that in comparison with COad on Pt(110) in a CO-free solution,the oxidation current peak of COsol in a CO-saturated solution is positively shifted ca. 168 mV,and the peak current density has been increased by 6. 70 times. Linear adsorbed CO (COL) is determined by in-situ FTIR spectroscopy as the main species,which is uniformly distributed on Pt (110) surface. In a CO-free solution,the onset potential of COL is measured by in-situ FTIRS ca. 0. …

Electrochemical Sers Studies On The Adsorption Of Benzoimidazole And Derivative In Nonaqueous Solution, Ya-Xian Yuan, Feng-Zhu Yang, Wei Liu, Ping-Jie Wei, Jian-Lin Yao, Ren-Ao Gu

Journal of Electrochemistry

The surface adsorption of benzoimidazole (BIMH) and 2-mercaptobenzimidazole(MBI) was investigated by electrochemical in-situ surface enhanced Raman spectroscopy (SERS) and direct electrochemical synthesis on Cu electrode. The influence of the neutral ligand of triphenylphosphine (pph₃) on the adsorption and surface coordination of BIMH and MBI were investigated respectively. BIMH interacted with metal surface by the neutral molecule to form chemical adlayer in the extremely negative potential,while it adsorbed onto metal surface through the N atoms to form a polymer film which may suppress the corrosion of the metal. The introduction of pph₃ destroyed the film formation of BIMH …

Frataxin And Mitochondrial Fes Cluster Biogenesis, Timothy L. Stemmler, Emmanuel Lesuisse, Debumar Pain, Andrew Dancis

Biochemistry and Molecular Biology Faculty Publications

Friedreich’s ataxia is an inherited neurodegenerative disease caused by frataxin deficiency. Frataxin is a conserved mitochondrial protein that plays a role in Fe-S cluster assembly in mitochondria. Fe-S clusters are modular cofactors that perform essential functions throughout the cell. They are synthesized by a multi-step and multi-subunit mitochondrial machinery that includes a scaffold protein Isu for assembling a protein bound Fe-S cluster intermediate. Frataxin interacts with Isu, iron, and with the cysteine desulfurase Nfs1 that supplies sulfur, thus placing it at the center of mitochondrial Fe-S cluster biosynthesis.

I, Development Of The In Situ Reductive Ozonolysis Of Alkenes With Tertiary Amine N-Oxides. Ii, Progress Toward The Asymmetric Synthesis Of Peroxyplakoric Acid A3, Christopher P. Schwartz

Department of Chemistry: Dissertations, Theses, and Student Research

Ozone, first discovered in the mid 1800’s, is a triatomic allotrope of oxygen that is a powerful oxidant. For over a century, research has been conducted into the synthetic application and mechanism of reactions of ozone with organic compounds. One of the major areas of interest has been the ozonolysis of alkenes. The production of carbonyl compounds is the most common synthetic application of ozonolysis. The generally accepted mechanism developed by Rudolf Criegee for this reaction involves the 1,3-electrocyclic addition of ozone to the π bond of the alkene to form a 1,2,3-trioxolane or primary ozonide. The primary ozonide is …

Novel Polymer Coupling Chemistry Based Upon Latent Cysteine-Like Residues And Thiazolidine Chemistry, Jospeh S. Carlson, Megan R. Hill, Taiga Young, Philip Costanzo

Chemistry and Biochemistry

Chain end functional polymers were prepared via reversible addition–fragmentation transfer (RAFT) polymerization techniques that were further chain extended with acrylonitrile. Under reducing conditions, latent cysteine-like residues were exposed at the chain ends. A variety of reduction conditions were explored and base polymers were then tethered together via thiazolidine chemistry.

Remote Measurements Of On-Road Emissions From Heavy-Duty Diesel Vehicles In California; Year 2, 2009, Brent G. Schuchmann, Gary A. Bishop, Donald H. Stedman

Fuel Efficiency Automobile Test Publications

No abstract provided.

New C1 Geometries For Free 12-Crown-4 In Aqueous Solution And The Absolute Selectivity Of 12-Crown-4 On Alkali Metal Ions In Aqueous Solution: A Theoretical Study, Tanika Arora

Student Theses and Dissertations

The IEFPCM conformational study of 12c4 in aqueous phase with B3LYP/6-31+G* and metal ion complex, M+(12c4), M= Li, Na and K withB3LYP, B3P86, B3PW91 and mPW3PBE using 6-31+G* basis sets are performed. Our result shows that the ground state conformer of 12c4 in gas phase, 1(S4) has population of no more than 2% in aqueous solution. The conformer 11(C1) structure was diagnosed to be the most populated conformer while B3LYP method predicts the conformer 6(Ci) has the lowest energy. The metal ion (Li+, Na+, K+) selectivity of 12c4 in aqueous phase is determined by the isodesmic reaction. The ensemble averaged …

Preliminary Analysis Of Thermally Induced Condensed Phase Electron Transfer Reactions Of Copper Chloride With Electropositive Metals, Indrani Kothuru

Student Theses and Dissertations

The thermal stabilities and thermal decomposition of copper metal and its chlorides with electropositive metals such as Pb, Sn, Ni, Co, Cd, Fe, Cr and Mn at non standard temperatures was investigated. The heat capacities and change in enthalpy (ΔH) of the reactions were calculated using the onset temperatures obtained from DTA/TGA plot using Kirchhoff‟s Law. In the case of Co, it was observed that the calculated ΔH values at elevated temperatures gives a negative value indicating the reaction is exothermic but their respective DTA/TGA plots of CuCl2 + Co shows no sign of exothermic peak. However, in the case …

Nvrec Subtask 1.1: Pre-Treatment Of Lignocellulosic Biomass, Amber Broch, Kent Hoekman, Larry Felix, Rick Purcell, Curt Robbins, Wei Yan

Nevada Renewable Energy Consortium Meeting

The second annual Nevada Renewable Energy Consortium meeting took place at UNLV on August 20. The meeting focused on the current three NVREC program areas: Solar, Biomass and Geothermal. Presentations were made by participating entities and a poster session followed.

Nvrec Subtask 1.2: Thermal Treatment Of Biomass, Curtis Robbins, Eric Ceniceros, Kent Hoekman, Richard Jasoni

Nevada Renewable Energy Consortium Meeting

The second annual Nevada Renewable Energy Consortium meeting took place at UNLV on August 20. The meeting focused on the current three NVREC program areas: Solar, Biomass and Geothermal. Presentations were made by participating entities and a poster session followed.

Integrated Affinity Column Capillary Electrophoresis Microdevices For Biomarker Analysis, Weichun Yang

Theses and Dissertations

In this dissertation, microfluidic systems that integrate antibody-based sample preparation methods with electrophoretic separation are developed to analyze multiple biomarkers in a point-of-care setting. To form an affinity column, both monolith materials and wall-coated channels were explored. I successfully demonstrated that monolith columns can be prepared in microfluidic devices via photopolymerization. The selectivity of monolith columns was improved by immobilizing antibodies on the surface. These affinity columns can selectively enrich target analytes and reduce the signal of contaminant proteins up to 25,000 fold after immunoaffinity extraction. These results clearly demonstrate that microchip affinity monoliths can selectively concentrate and purify target …

Trans-Excision-Splicing Ribozyme And Methods Of Use, Stephen M. Testa, Michael A. Bell

Chemistry Faculty Patents

A group I intron-derived ribozyme which binds RNA in trans, excises an internal segment from within the RNA, and splices the remaining 5′ and 3′ ends of the RNA back together (the trans-excision-splicing reaction) is disclosed. The excised segment can be as long as 28 nucleotides, or more, and as little as one nucleotide. The ribozymes of the invention are easily modified to alter their sequence specificity. Such ribozymes represent a new and potentially powerful class of generally adaptable genetic therapeutics.

Functional, Degradable Polyester Materials Synthesized From Poly(Epsilon-Caprolactone-Co-2-Oxepane-1,5-Dione): An Investigation Into The Derivatization, Self Assembly, And Degradation Behavior Of Poly(Epsilon-Caprolactone)-Based Materials, Rhiannon K. Iha

Arts & Sciences Graduate Student Theses and Dissertations

Biocompatible, degradable polymers possessing a high degree of complexity are an extremely desirable target for many applications. In order to further develop the range and utility of materials made from aliphatic polyesters, poly(epsilon-caprolactone-co-2-oxepane-1,5-dione) (P(CL-co-OPD)) was used as a polymeric precursor for the construction of a series of functional polyester-based materials. By taking advantage of the electrophilic ketone moieties characteristic of the OPD repeat unit, small molecule and polymer grafts were attached to the PCL backbone through the formation of both hydrazone and ketoxime ether linkages. This work has focused on both the synthesis and characterization of functional, degradable polyesters, including …

Spin Obit Interaction, Ronald Lovett

Topics in Quantum Mechanics

No abstract provided.

Cyanoscorpionates And Transition Metal Complexes., Donald Martin Johnson

Electronic Theses and Dissertations

The new dihydrobis(4-cyano-3-tert-butylpyrazolylborate) ligand has been synthesized. Isolated crystals of the thallium complex were collected and structurally characterized by X-ray diffraction. Transition metal complexes of the ligand are currently under investigation.

Synthesis And Characterization Of An Oligothiophene-Ruthenium Complex And Synthesis And Optical Properties Of Oligothiophene-Ruthenium Complexes Bound To Cdse Nanoparticles, Nathan A. Bair

Theses and Dissertations

Oligothiophenes are of increasing interest in organic based electronic devices in part due to their high electron and hole mobilities. In an organic photovoltaic (OPV) device, the electronic properties of oligothiophenes make them advantageous as charge transfer junctions. To serve as charge transfer junctions, oligothiophenes must be functionalized to bind to the donor and acceptor parts of the device. The donor and acceptor parts are different materials and the synthesis of asymmetric oligothiophenes is of great interest. Previous researchers in our lab synthesized four asymmetric oligothiophenes, two with two thiophene subunits and two with four. Each set of oligothiophenes contained …

Sumpter, Ward Cullin, 1902-1977 (Sc 2318), Manuscripts & Folklife Archives

Manuscript Collection Finding Aids

Finding aid only for Manuscripts Small Collection 2318. Chemistry notebook of Ward Cullin Sumpter, probably kept about 1930 while he was a doctoral student at Yale University. Includes other miscellaneous documents: a tribute to a church's departing pastor, a draft petition in support of an anti-cigarette law, and a poem relating to the 1928 presidential election.

Guest Induced Transformations Of Assembled Pyridyl Bis-Urea Macrocycles, Kinkini Roy, Chun Wang, Mark D. Smith, Mahender B. Dewal, Arief C. Wibowo, Julius C. Brown, Shugo Ma, Linda S. Shimizu

Faculty Publications

Pyridine macrocycles with no cavities assembled into close packed columns yet absorbed guests including hydrogen, carbon dioxide, and iodine.

Aspergillus Fumigatus Sida Is A Highly Specific Ornithine Hydroxylase With Bound Flavin Cofactor, Samuel W. Chocklett, Pablo Sobrado

Chemistry Faculty Research & Creative Works

Ferrichrome is a hydroxamate-containing siderophore produced by the pathogenic fungus Aspergillus fumigatus under iron-limiting conditions. This siderophore contains N5-hydroxylated l-ornithines essential for iron binding. A. fumigatus siderophore A (Af SidA) catalyzes the flavin- and NADPH-dependent hydroxylation of l-ornithine in ferrichrome biosynthesis. Af SidA was recombinantly expressed and purified as a soluble tetramer and is the first member of this class of flavin monooxygenases to be isolated with a bound flavin cofactor. The enzyme showed typical saturation kinetics with respect to l-ornithine while substrate inhibition was observed at high concentrations of NADPH and NADH. Increasing amounts of hydrogen peroxide were measured …

Chain-Selective And Regioselective Ethylene And Styrene Dimerization Reactions Catalyzed By A Well-Defined Cationic Ruthenium-Hydride Complex: New Insights On The Styrene Dimerization Mechanism, Do W. Lee, Chae S. Yi

Chemistry Faculty Research and Publications

The cationic ruthenium hydride complex [(η⁶-C₆H₆)(PCy₃)(CO)RuH]⁺BF₄⁻ was found to be a highly regioselective catalyst for the ethylene dimerization reaction to give 2-butene products (TOF = 1910 h⁻¹, >95% selectivity for 2-butenes). The dimerization of styrene exclusively produced the head-to-tail dimer (E)-PhCH(CH₃)CH═CHPh at an initial turnover rate of 2300 h⁻¹. A rapid and extensive H/D exchange between the vinyl hydrogens of styrene-d₈ and 4-methoxystyrene was observed within 10 min without forming the dimer products at room temperature. The inverse …

Acetic Acid Aldol Reactions In The Presence Of Trimethylsilyl Trifluoromethanesulfonate, C. Wade Downey, Miles W. Johnson, Daniel H. Lawrence, Alan S. Fleisher, Kathryn J. Tracy

Chemistry Faculty Publications

In the presence of TMSOTf and a trialkylamine base, acetic acid undergoes aldol addition to non-enolizable aldehydes under exceptionally mild conditions. Acidic workup yields the β-hydroxy carboxylic acid. The reaction appears to proceed via a three-step, one-pot process, including in situ trimethylsilyl ester formation, bis-silyl ketene acetal formation, and TMSOTf-catalyzed Mukaiyama aldol addition. Independently synthesized TMSOAc also undergoes aldol additions under similar conditions.

Residue Mutations In [Fe-Fe]-Hydrogenase Impedes O 2 Binding: A Qm/Mm Investigation, Daniela Dogaru, Stefan Motiu, Valentin Gogonea

Chemistry Faculty Publications

[Fe-Fe]-hydrogenases are enzymes that reversibly catalyze the reaction of protons and electrons to molecular hydrogen, which occurs in anaerobic media. In living systems, [Fe-Fe]-hydrogenases are mostly used for H(2) production. The [Fe-Fe]-hydrogenase H-cluster is the active site, which contains two iron atoms. The latest theoretical investigations1,2 advocate that the structure of di-iron air inhibited species are either Fe(p) (II)-Fe(d) (II)-O-H(-), or Fe(p) (II)-Fe(d) (II)-O-O-H, thus O(2) has to be prevented from binding to Fe(d) in all di-iron subcluster oxidation states in order to retain a catalytically active enzyme. By performing residue mutations on [Fe-Fe]-hydrogenases, we were able to weaken O(2) …

Full Multiple Scattering Analysis Of Xanes At The Cd L 3- And O K- Edges In Cdo Films Combined With A Soft-X-Ray Emission Investigation, I. N. Demchenko, J. D. Denlinger, M. Chernyshova, K. M. Yu, D. T. Speaks, P. Olalde-Velasco, Oliver Hemmers, W. Walukiewicz, A. Derkachova, K. Lawniczak-Jablonska

Environmental Studies Faculty Publications

X-ray absorption near edge structure (XANES) at the cadmium L3 and oxygen K edges for CdO thin films grown by pulsed laser deposition method, is interpreted within the real-space multiple scattering formalism, FEFF code. The features in the experimental spectra are well reproduced by calculations for a cluster of about six and ten coordination shells around the absorber for L3 edge of Cd and K edge of O, respectively. The calculated projected electronic density of states is found to be in good agreement with unoccupied electronic states in experimental data and allows to conclude that the orbital character of the …

Influence Of Ambient Temperature On The Pm Emissions From A Gas Turbine Engine, Donald E. Hagen, Prem Lobo, Philip D. Whitefield, Max B. Trueblood

Physics Faculty Research & Creative Works

During Project AAFEX, PM emissions measurements were conducted on a CFM56-2C1 gas turbine engine in January 2009 in Palmdale CA. The engine was mounted on a NASA DC-8 aircraft, which was parked on the runway, and emission samples were extracted at the engine exit plane (1m), in the near field (30m), and in the advected plume (145m). The engine was operated at several power levels, and burned several fuels: JP-8, a Fischer-Tropsch fuel derived from natural gas (FT1), and a second Fischer-Tropsch fuel derived from gasified coal (FT2). In addition to these fuels, 50:50 blends of the Fischer-Tropsch fuels and …

Nitrogen Cycle In Great Basin Hot Springs, Tara A. Edwards, Paula Matheus-Carnevali, Ryan Wahrenbrock, Jeremy A. Dodsworth, Brain P. Hedlund

Undergraduate Research Opportunities Program (UROP)

Nitrification and denitrification are two important steps in the nitrogen cycle . Nitrification, a two step process, leads to the production of NO3-, (Fig. 1). In the first step, ammonia oxidation, NH3 is oxidized to NO2-, and in the second step, nitrite oxidation, NO2- is oxidized to NO3-. Until recently, very little was know about nitrification in high temperature environments. However, in 2008 a thermophilic archaeon, named “Candidatus Nitrosocaldus yellowstonii”, was shown to mediate ammonia oxidation up to 74°C. More recently , NO2- oxidizing bacteria were discovered that are active in temperatures up to 48°C(4). While NH3 oxidation is generally …

Synthesis Of Novel Aromatic Quinols For Colon And Renal Cancers, Bradley J. Davey, Tae Soo Jo, Pradip K. Bhowmik

Undergraduate Research Opportunities Program (UROP)

Colon Cancer: The third most common cancer in USA. More than 1 million Americans currently living with colon cancer. 148,810 new cases expected in 2010. 50,000 deaths annually.

Renal Cancer: Approximately 58,000 people diagnosed in USA annually. Seventh most common cancer and tenth most common cause of cancer related death in men.

Aromatic quinols have demonstrated in vitro antitumor activity. Three heteroaromatic quinols show antitumor activity.