Physical Sciences and Mathematics Commons^™

New Progress In Studies Of Lithium Nickel Oxide As Positive Electrode Materials Of Lithium Ion Batteris, Han-San Liu, Yong Yang, Zhong-Ru Zhang, Zu-Geng Lin

Journal of Electrochemistry

Lithium nickel oxide as the positive electrode of lithium ion batteries has aroused more and more interests.This paper reviews the recent reserches on synthesis and element_substitution of LiNiO 2 cathode material,and summarizes the intrinsical relationship between properties and sturcture of the material.The developments of new synthesis methods and mutil_substitution of the material are expecting to be studied in the future research.

Performance Of A Direct Methanol Fuel Cell, Zhao-Bin Wei, Jian-Guo Liu, Ya-Guang Jiao, Wei-Jiang Zhou, Wen-Zhen Li, Li-Kang Chen, Qin Xin, Bao-Lian Yi

Journal of Electrochemistry

A direct methanol fuel cell with 9cm 2 active area consists of Pt_Ru/C anode,Pt/C cathode and Nafion 115 membrane.The effect of operating conditions:methanol solution concentration,oxygen pressure and cell temperature on the cell performances was investigated.The results show that performance of single cell was enhanced by increasing oxygen pressure and cell temperature,and a maximum power density 75 mW/cm 2 was obtained in the range of 250_300 mA/cm 2 current density,0.2 MPa oxygen pressure,1.0 mol/L methanol concentration and 75 ℃ cell temperature.When cell operating at room temperature,a relatively low,but a stable performance of cell was also observed.

Kinetics Of Substitution Of Weakly Coordinating Nitrate By Chloride In (Η5-Cp)Ru(Co)(Er3)Ono2 (Er3 = Asph3, Pph3, P(P-Anisyl)3, Pph2(O-Anisyl), P(Oph)3) In Dichloromethane., Minhton Cao, Liem Do, Norris Hoffman, Man Lung Kwan, Julie Little, J. Mcgilvray, Christopher Morris, Bjorn Söderberg, Andrzej Wierzbicki, Thomas Cundari, Charles Lake, Edward Valente

Man Lung Desmond Kwan

The d6 complexes of formula (η5-Cp)Ru(CO)(ER3)ONO2, where ER3 = AsPh3, PPh3, P(p-anisyl)3, PPh2(o-anisyl), and P(OPh)3, were prepared by reaction of their chloro analogues with AgNO3 in CH2Cl2. They underwent moderately slow substitution of the relatively weakly coordinating nitrate by chloride in dry CH2Cl2 in the presence of excess [N(PPh3)2+]Cl-. A kinetics study showed the reaction to be first order in nitrato complex and independent of chloride salt concentration under pseudo-first-order conditions. First-order rate constants for nitrate metathesis follow the trend P(OPh)3 < PPh3 < P(p-anisyl)3 < AsPh3 PPh2(o-anisyl), with k1 at 25 °C for the first four in the series from 1.4 to 4.4 × 10-5 s-1. Activation parameters for conversion of (η5-Cp)Ru(CO)(AsPh3)ONO2 to its chloride are ΔH‡ = 17(2) kcal/mol and ΔS‡ = −21(5) eu. Even use of a slightly moist solvent increased the rate of nitrate metathesis by 20−30% without changing the form of the rate law. The complex containing PPh2(o-anisyl) was approximately 2 orders of magnitude more reactive (k1 = 4.9 × 10-3 s-1). A likely explanation is stabilization of a coordinatively unsaturated intermediate by weak coordination of the potentially chelating o-OMe group. A mechanism entailing rate-limiting conversion of the neutral nitrato complex into a coordinatively unsaturated ion-paired species is consistent with this set of data. Semiempirical calculations (PM3(tm)), which model the structures of complexes in these systems quite well, supported such behavior. X-ray crystal structures were determined for the AsPh3 nitrato and chloro complexes and for the PPh3 chloro complex.

Computer Simulations Of Confined Systems, Jayendran C. Rasaiah

University of Maine Office of Research Administration: Grant Reports

Jayendran Rasaiah of the University of Maine is supported by an award from the Theoretical and Computational Chemistry program with partial funding provided by the Experimental Program to Stimulate Competitive Research for the development of computational methods to simulate water and other solvents in confined systems, such as carbon nanotubes and the interior of proteins. Other systems which are being studied include capillary evaporation of water between hydrophobic plates, water near surfaces and water between charged membranes. The development of better water potentials for a variety of applications is a major goal of the research. Rasaiah is also developing efficient …

Quantification Of Nanomolar Superoxide In Aqueous Solution : Flow Injection Analysis Using The Chemiluminescent Reagent Mcla., Nathan Boland

Honors Theses

A flow injection system using the chemiluminescent reagent 2-methyl-6-(4methoxyphenyl)- 3,7-dihydroimidazo[1,2-a]pyrazin-3-one (MCLA) was used to quantify aqueous concentrations of superoxide. Stock solutions of superoxide were produced by photolysis of a solution of 2-propanol and benzophenone. The concentration of superoxide was quantified in the stock solutions by direct measurement of the absorbance at 240 nm. Quantified additions of superoxide to the flow injection analysis system reacted with MCLA at pH 5.1 demonstrated a detection limit of 0.074 nM superoxide. Selective superoxide detection was confirmed by pH-dependent decay of superoxide, which was in excellent agreement with published rates.

Metal Ion Stabilization Of G-Tetrads Containing 6-Thioguanosine, Julia Drees

Honors Theses

As alternative structures to the double helix, G-tetrads are thought to occur in DNA with many repeating deoxyguanosines (dG). These tetrads have one dG on each corner of a plane and can stack into tetraplexes that can be aptamers and may be found in telomeres. G-tetrads are destabilized by incorporation of 6-thiodeoxyguanosine (?sdG). Addition of metal ions that bind sulfur may stabilize these ?sdG-tetrads. We have carried out a survey of metal ion titrations into ?sG. Stable ?sG:MD? complexes were found for Hg2? (2:1), Cd2? (4:1), Ag2? (0.7:1) and Pt2? (thought to be 2:1). UV/Visible spectrophotometry indicates that G-tetrads containing …

Photochemical Generation And Intramolecular Chemistry Of 2-Hydroxy-2-Methylpropylidene, Robin Farlow

Honors Theses

2-(1a,9b-Dihydro-lH-cyclopropa[l]phenanthren-1-yl)-propan-2-ol was synthesized by two different but related synthetic routes and characterized by melting point, IR GC/MS, CHN, and NMR spectroscopy. Photolysis of the alcohol in benzene d-6 led to the formation of 2-butanone, 1-methylcyclopropanol, and 2,2-dimethyloxirane in a 26:10:1 ratio via 2-hydroxy-2methylpropylidene, a novel ?-hydroxycarbene. These products are a consequence of intramolecular insertions of the carbene into C-C, C-H, and O-H bonds. Molecular orbital calculations performed at the Becke-3LYP/6-31G(d) level indicate that the singlet form of this carbene is more thermodynamically stable than the triplet. Furthermore, the transition states to the three products from the singlet species were modeled …

Nucleation Of Water And Methanol Droplets On Cations And Anions: The Sign Preference, K.J. Oh, G.T. Gao, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

The barrier height to cation- and anion-induced nucleation to produce water and methanol droplets are calculated by means of an umbrella-sampling Monte Carlo method. The computer simulation corroborates the century-old finding of Wilson that the anion is a better nucleator to produce water droplets than the cation having the same magnitude of charge, even without the presence of external electric field. The simulation also shows that the cation is a better nucleator to produce methanol droplets than the anion.

Synthesis And Reactivity Of Gold Thiolate Cluster Complexes, Hanan Abdou

Electronic Theses and Dissertations

Chemical oxidation of dinuclear gold(I) thiolates of the formula LLAu₂(SC₆H₄CH₃)₂ [LL= dppp, bis(dipheny1phosphine)propane and dppb, bis(dipheny1phosphine)butane] and dinuclear gold(I) thiolate complexes with bridging a propane dithiolate ligand of the formula LLAu₂(SC₃H₆S) [LL = dppp and dppb] was carried out using the mild oxidizing agent, ferrocenium, [Cp₂Fe]PF6). Spectroscopic studies and elemental analysis showed the formation of gold(I) clusters, disulfide, and ferrocene as products of this oxidation reaction. The clusters, [(dppp)AU₂(SC₆H₄CH₃)](PF₆) and [(dppb)Au₂(SC …

Anionic Photofragmentation Of Co: A Selective Probe Of Core-Level Resonances, Wayne C. Stolte, D. L. Hansen, Maria Novella Piancastelli, I. Dominguez-Lopez, A. Rizvi, Oliver Hemmers, H. Wang, Alfred S. Schlachter, M. S. Lubell, Dennis W. Lindle

Environmental Studies Faculty Publications

Anion-yield spectroscopy using x rays is shown to be a selective probe of molecular core-level processes, providing unique experimental verification of shape resonances. For CO, partial anion and cation yields are presented for photon energies near the C K edge. The O^- yield exhibits features above threshold related only to doubly excited states, in contrast to cation yields which also exhibit pronounced structure due to the well-known σ^* shape resonance. Because the shape resonance is completely suppressed for O^-, anion spectroscopy thus constitutes a highly selective probe, yielding information unobtainable with absorption or electron spectroscopy.

New Approaches To Processing Nanoparticles And Nanostructures, Mathew M. Maye

Undergraduate Honors Theses

The study of nanoparticles is an emerging field of nanoscience and nanotechnology. A challenging issue is how deliberate tailoring and processing of the nanoscale materials can lead to well defined and functional nanostructures. In this thesis, we explore new strategies of nanoscale design and processing to address the challenge.

A core-shell chemical processing route towards fabrication of functional composite nanomaterials with defined sizes, shapes, compositions and surface properties is demonstrated. New findings of an investigation of thermally-activated core-shell reactivities of nanoparticles in solutions are described. Gold nanoparticles of ~2-nm core size with thiolate monolayer encapsulation were chosen as a model …

Photostabilization Of High-Yield Pulps Reaction Of Thiols And Quinones With Pulp, Jonathan Spender

Electronic Theses and Dissertations

Some thiols have been shown to be efficient in both bleaching and stabilizing the brightness of mechanical pulps. Two thiols, thioglycerol and glycol dimercaptoacetate, have received considerable attention due to their photostabilization effects. Their reactions with 1,4-benzoquinone, a model lignin compound, were investigated. In the first part of this study, reaction products were isolated using preparative HPLC and were fully characterized using GC-MS as well as ^l3C-NMR Both thiols were found to undergo Michael addition with the model quinone (in methanol) to yield a substituted hydroquinone. Further reaction with excess quinone in the presence of UVlight facilitated subsequent redox …

Effects Of Eluent Ph And Different Types Of Acidic Modifiers On The Retention And Electrospray Ionization Efficiency Of Basic Analytes In Lc-Esi-Ms., Unita L. Peri-Okonny

Seton Hall University Dissertations and Theses (ETDs)

.

The Partition/Adsorption Model For The Description Of The Retention Mechanism In Reversed Phase Liquid Chromatography, Tarun S. Patel

Seton Hall University Dissertations and Theses (ETDs)

.

Trimethylsulfonium Methanesulfonate, Frank R. Fronczek, Rolanda J. Johnson, Robert M. Strongin

Chemistry Faculty Publications and Presentations

In the title compound, C₃H₉S⁺.CH₃O₃S^-, a thermal decomposition product of dimethyl sulfoxide, both cation and anion lie on mirror planes. In the cation, the S atom lies 0.792 (2) Å out of the plane defined by the three C atoms, with S-C distances of 1.781 (2) and 1.786 (3) Å. In the anion, the S-O distances are 1.4556 (14) and 1.4646 (19) Å, and the S-C distance is 1.759 (3) Å.

Energy Gaps In “Metallic” Single-Walled Carbon Nanotubes, Min Ouyang, Jin-Lin Huang, Chin Li Cheung, Charles Lieber

Barry Chin Li Cheung Publications

Metallic single-walled carbon nanotubes have been proposed to be good one-dimensional conductors. However, the finite curvature of the graphene sheet that forms the nanotubes and the broken symmetry due to the local environment may modify their electronic properties. We used low-temperature atomically resolved scanning tunneling microscopy to investigate zigzag and armchair nanotubes, both thought to be metallic. “Metallic” zigzag nanotubes were found to have energy gaps with magnitudes that depend inversely on the square of the tube radius, whereas isolated armchair tubes do not have energy gaps. Additionally, armchair nanotubes packed in bundles have pseudogaps, which exhibit an inverse dependence …

A Greek Cross Dodecaphenylene: Sparteine-Mediated Asymmetric Synthesis Of Chiral D2-Symmetric Π-Conjugated Tetra-O-Phenylenes, Andrzej Rajca, Hua Wang, Pavel Bolshov, Suchada Rajca

Andrzej Rajca Publications

The asymmetric synthesis of a chiral, nonracemic π-conjugated system with D₂ point group of symmetry, dodecaphenylene 4 is described. In the key step, (−)-sparteine- and Cu(II)-mediated oxidation of 2,2′-dilithio-1,1′-biaryls in ether gives the corresponding dimers, tetra-o-phenylenes, in 80% isolated yields and 50–60% ee’s. X-Ray crystallography confirms the structure of rac-4 and its molecular shape of a Greek cross. The torsional angles between the benzene rings in the tetra-o-phenylene core of rac-4 are in the 56.5–71.0° range. However, CD and UV spectra of 4 in CH₂Cl₂ are consistent with significant conjugation between the …

Dependence Of 13C Nmr Chemical Shifts On Conformations Of Rna Nucleosides And Nucleotides, Mohsen Ebrahimi, Paolo Rossi, Christopher Rogers, Gerard S. Harbison

Gerard Harbison Publications

Cross-polarization magic-angle spinning solid-state NMR spectroscopy has been used to investigate the dependence of ¹³C sugar chemical shifts on specific conformational parameters of a variety of ribonucleotides and ribonucleosides. Solid-state NMR is a valuable tool for nucleoside and nucleotide structural studies since it provides the means to acquire spectra that correspond to single conformations, as opposed to ¹³C solutionNMRmethods. The distinct effects of sugar puckering on the C1′, C4′, and C5′ resonances of C2′ endo (S type) and C3′ endo (N type) furanoid conformations allow us to separate them into two groups. Further analysis of each group reveals …

Oxidation Of Zeaxanthin And Characterization Of 3'-Alkyl Lutein Ethers, Jie Chi

FIU Electronic Theses and Dissertations

One purpose of this study was to understand the oxidation metabolites of zeaxanthin, another was to prepare, purify, and characterize a series of 3'-alkyl lutein ethers for use as internal standards.

Studies have proven that lutein and zeaxanthin are two of the principal carotenoids in human serum and the only carotenoids found in the retina, but their metabolism and transport in the human body are still only poorly understood. In vitro oxidation of zeaxanthin with MnO₂ produced three components. They were characterized by HPLC, UV/Vis, MS, NMR and identified as all-trans rhodoxanthin and its cis-isomers.

3'-alkyl lutein ethers have …

Determination Of Lysophosphatidic Acids By Capillary Electrophoresis With Indirect Ultraviolet Detection, Yi Lung Chen, Yan Xu

Chemistry Faculty Publications

Lysophosphatidic acid (LPA) is the simplest form of lysophospholipid. Molecular species of LPA have been identified as the potent components in the ovarian cancer activation factor. The elevated plasma LPAs may be used as potential biomarkers for the early detection of ovarian cancer. This paper is the first report on the quantitative analysis of molecular species of LPA using capillary electrophoresis. In this work, the separation of LPAs was achieved within 14 min in an adenosine monophosphate-borate–methanol–water solution, and the measurement was accomplished by indirect UV detection. With LPA (D) as internal standard, the method had linear calibration ranges for …

Adenosine Triphosphate-Dependent Degradation Of A Fluorescent Λ N Substrate Mimic By Lon Protease, Irene Lee, Anthony J. Berdis

Chemistry Faculty Publications

Escherichia coli Lon exhibits a varying degree of energy requirement toward hydrolysis of different substrates. Efficient degradation of protein substrates requires the binding and hydrolysis of ATP such that the intrinsic ATPase of Lon is enhanced during protein degradation. Degradation of synthetic tetrapeptides, by contrast, is achieved solely by ATP binding with concomitant inhibition of the ATPase activity. In this study, a synthetic peptide (FRETN 89-98), containing residues 89–98 of λ N protein and a fluorescence donor (anthranilamide) and quencher (3-nitrotyrosine), has been examined for ATP-dependent degradation by E. coli and human Lon proteases. The cleavage profile of FRETN 89-98 …

Observations On Lemon Cells, Jerry Goodisman

Chemistry - All Scholarship

In many general chemistry texts (1), the electrochemistry chapter is introduced with a picture of a “lemon cell”, leads of Zn and Cu piercing a lemon (or sometimes a grapefruit). A voltmeter connected across them shows a potential of about 1 V. (It has been shown how several fruits connected in series can be used to run a calculator [2].) The texts then discuss oxidation–reduction, half-cells, and the rest of what we teach freshmen about electrochemistry, and the lemon is never mentioned again.

It would appear to be questionable scientific pedagogy to present something, even something …

An Investigation Into The Mechanistic Interplay Between Th1 And Th2 Cells In Allergic Disease, Christine Marie Rose

WWU Honors College Senior Projects

The incidence of allergic disease has increased steadily in western countries over the past few decades. Substantial amounts of research have been geared toward elucidating the mechanisms whereby some people develop allergies and others do not. As with all development theories, the question revolves around the debate of genetics versus environment - attempting to determine the relative contribution from heredity and nurture in the development of an allergic phenotype.

Heredity has long been identified as a risk factor for allergies. Children born of atopic (allergic disease attributed to heredity) parents are at an increased risk for developing atopy themselves. Consequently, …

Solution Structure Of B. Subtilis Acyl Carrier Protein, Guang-Yi Xu, Amy Tam, Laura Lin, Jeffrey Hixon, Christian C. Fritz, Robert Powers

Robert Powers Publications

Background: Acyl carrier protein (ACP) is a fundamental component of fatty acid biosynthesis in which the fatty acid chain is elongated by the fatty acid synthetase system while attached to the 4’-phosphopantetheine prosthetic group (4’- PP) of ACP. Activation of ACP is mediated by holo-acyl carrier protein synthase (ACPS) when ACPS transfers the 4’-PP moiety from coenzyme A (CoA) to Ser36 of apo-ACP. Both ACP and ACPS have been identified as essential for E. coli viability and potential targets for development of antibiotics.

Results: The solution structure of B. subtilis ACP (9 kDa) has been determined using two-dimensional and three-dimensional …

Interchannel Coupling In The Photoionization Of The M-Shell Of Kr Well Above Threshold: Experiment And Theory, H. S. Chakraborty, D. L. Hansen, Oliver Hemmers, P. C. Deshmukh, P. Focke, I. A. Sellin, Clemens Heske, Dennis W. Lindle, S. T. Manson

Environmental Studies Faculty Publications

Photoionization cross sections and asymmetry (β) parameters for Kr 3s, 3p, and 3d subshells have been measured and calculated in the 300–1300-eV photon energy range. Good agreement between experiment and theory is found for both cross-section branching ratios and β parameters. Interchannel coupling among the channels arising from 3s, 3p, and 3d subshells is found to be necessary for quantitative accuracy of the theory. This shows that the interchannel coupling phenomenology far above threshold, found previously for outer shells of Ne and Ar, is also operative for inner atomic shells.

A Strategy For Improved Expression Of Permuted Myoglobins, Anna Buser

WWU Honors College Senior Projects

Our research is aimed at generating and characterizing topological mutants of sperm whale myoglobin (swMb). The long-term experimental design involves the production of circular permuteins from swMb genes fused by a linker and determination of the effect of linker sequence on protein stability. We have expressed circularly permuted sperm whale myoglobins in E. coli including variants that start at the C helix and end with the B helix (CBLx), and others beginning at the H helix and ending with the G helix (HGLx). Expression yields for mutant myoglobins have been shown to correlate with stabilities of the mutants (Hargrove et …

Molecular Dynamics Simulations Of Large Systems, Patrick B. (Patrick Brian) Kohl, David L. Patrick

WWU Honors College Senior Projects

Chiral symmetry breaking in a fluid of achiral molecules at a liquid-solid interface was studied using atomistic molecular dynamics simulation. The molecules were achiral in three dimensions, but left- and right-handed forms could be distinguished in the reduced symmetry environment of an interfacial fluid. The system consisted of a thick fluid film in contact with a crystalline monolayer adsorbed to a solid surface. When molecules in the crystalline monolayer were arranged in uniformly chiral configurations, a homochiral enantiomeric excess developed in the adjacent interfacial fluid. Fluid properties were characterized through measurements of chiral, nematic, and ferroelectric order parameters, and diffusion …

Effect Of A Modified Isoindole Backbone On The Electrical Optical And Physical Properties Of The Isoindole Organised Semiconductor System, Matthew Boylan

Doctoral

Primarily it was endeavoured to synthesise conducting polymers bearing a modified isoindole backbone with potentially enhanced electrical, optical and physical properties. The addition of electron donating methoxy groups on to the N-methylisoindole system results in alternations to the resultant polymer’s optical and physical properties. The synthesis of the new compounds 5-methoxy-N-methylisoindole and 5, 6-dimethoxy-N-methylisoindole was carried out via a devised route. Characterisation of the two new monomers 5-methoxy-N-methylisoindole and 5,6-dimethoxy-N-methylisoindole and the parent N-methylisoindole and their corresponding polymers has also been carried out initially by cyclic voltammetry studies. The oxidation of the monomers and corresponding polymers occurs at decreasing positive …

An Efficient And Simple Synthesis Of Optically Pure Tricarbonyl(Methyl 6-Oxo-2,4-Hexadienoate)Iron, Kamil Godula, Heiko Bärmann, William A. Donaldson

Chemistry Faculty Research and Publications

No abstract provided.

Lewis Acid Catalyzed Reactions Of Aziridino-Olefins, Steven Tymonko '01

Honors Projects

Electrophilic reactions resulting in the formation of new carbon-carbon bonds are important tools in organic synthesis. For example, the acid catalyzed cyclization of epoxy olefins has been well documented, while similar cyclizations with aziridines have been largely unexplored. The aim of this project is to develop and demonstrate the formation of a carbocyclic compound from aziridino-olefins utilizing a Lewis acid to catalyze the cyclization. In working toward this goal, a number of aziridino-olefins were synthesized from isoprenoid start materials. These aziridino-olefins were then reacted with both Lewis and protic acids in an attempt to induce cyclization. As a result, we …