Digital Commons Network^™

Cross Sections For The Production Of He+ (Np) 2p0 States By 50 To 150 Kev Proton Impact On Helium, Wayne C. Stolte, R. Bruch

Chemistry and Biochemistry Faculty Research

Cross sections have been measured for the production of He⁺ (np) ²P^o states, n=2,3,4, by proton impact on helium over a projectile velocity range of 1.42–2.45 a.u. (50 ≤E≤150 keV). Cross sections were determined by measuring the extreme ultraviolet photons emitted from excited He1 ions. The data indicate a lower energy than expected for the maximum cross section. A comparison of the present results in terms of projectile energy dependance with the cross sections for excitation to He (1snp) ¹P^o, ionization, and total electron capture suggests the primary mechanism …

First Results From The High-Brightness X-Ray Spectroscopy Beamline 9.3.1 At Als, W. Ng, G. Jones, Rupert C. Perera, D. Hansen, J. Daniels, Oliver Hemmers, P. Glans, S. B. Whitfield, H. Wang, Dennis W. Lindle

Environmental Studies Faculty Publications

Beamline 9.3.1 at the Advanced Light Source (ALS) is a windowless beamline, covering the 1–6 keV photon energy range. This beamline is designed to achieve the goal of high brightness at the sample for use in the x‐ray atomic and molecular spectroscopy (XAMS) science, surface and interface science, biology and x‐ray optical development programs at ALS. X‐ray absorption and time‐of‐flight photoemission measurements in 2–5 keV photon energy range along with the flux, resolution, spot size and stability of the beamline will be discussed. Prospects for future XAMS measurements will also be presented.

Kinetics And Jamming Coverage In A Random Sequential Adsorption Of Polymer Chains, Jian-Sheng Wang, Ras B. Pandey

Faculty Publications

No abstract provided.

A Hplc Method To Assay Mycotoxins - Fumonisin, Ochratoxin And Zearalenone, Nalini Sadagopan

Masters Theses

A HPLC method to quantitate the mycotoxins Fumonisin B1 (FB1), Ochratoxin A(OA), and Zearalenone (ZON) was developed and validated. Mycotoxins are secondary metabolites of fungi like Fusarium, Asperigillus and Penicillium that contaminate crops. They have a wide array of chemical structures which facilitate their analytical detection.

The analytical method consists of reverse phase chromatography and fluorescence detection. Sample cleanup was performed using SAX and C18 cartridges prior to analysis on the HPLC.

The method developed for FB1 is unique in that it is more sensitive, accurate, and reproducible than the existing methods. Automation is one of the salient features that …

The Role Of Written And Verbal Expression In Improving Communication Skills For Students In An Undergraduate Chemistry Program, Brian P. Coppola, Douglas S. Daniels

Chemistry Faculty Publications

Proofreading, editing, and critique, the customary assessment tools scientists use to evaluate professional journal articles, grant applications, and any other writing, can be applied equally well in introductory science instruction. Such feedback is, in fact, crucial to growth and development. When learning anything new, students and faculty alike rely heavily on sources other than themselves (‘external editors’) to assess their understanding as they develop self-assessment skills (or ‘internal editors’). Although they rarely describe it in these terms, faculty nonetheless assume that students have developed and refined their internal skills by the time they take examinations and write term papers. Unfortunately, …

38th Rocky Mountain Conference On Analytical Chemistry

Rocky Mountain Conference on Magnetic Resonance

Final program, abstracts, and information about the 38th annual meeting of the Rocky Mountain Conference on Analytical Chemistry, co-sponsored by the Colorado Section of the American Chemical Society and the Rocky Mountain Section of the Society for Applied Spectroscopy. Held in Denver, Colorado, July 21-26, 1996.

Model Calculations Of Langmuir Monolayers: Pressure Effects On Tilting Behavior Of Idealized Amphiphiles, D.R. Swanson, Robert J. Hardy, Craig J. Eckhardt

Craig J. Eckhardt Publications

Model amphiphiles consisting of lines of Lennard-Jones (LJ) centers are investigated to determine the effect of pressure and molecular geometry on ground-state tilting behavior. Both the amphiphile length and the intramolecular distance between LJ centers is varied. The results give guidelines for understanding and controlling tilting behavior in monolayer films.

Concentrations, Complexation And Speciation Of Total Dissolved Zinc In The Chesapeake Bay, Charles William Henry Iii

Chemistry & Biochemistry Theses & Dissertations

This is the first research to examine the horizontal, vertical, and temporal variability of total dissolved zinc, organic complexation of zinc, and zinc speciation in the Chesapeake Bay. Filtered (0.45μm) surface and bottom water samples were taken along the salinity gradient of the Chesapeake Bay in October 1993, March 1995, July 1995, and October 1995. Analysis by Differential Pulse Anodic Stripping Voltammetry (DP ASV) indicated that total dissolved zinc concentrations in the Bay ranged from 2.9 ± 0.7nM to 38.8 ± 2nM. Total zinc was highest at the northern end of the Bay (low salinity), approximately 10 times lower at …

Two-Dimensional 1H Nmr Studies On Octahedral Nickel(Ii) Complexes, Richard C. Holz, Evgenij A. Evdokimov, Feben T. Gobena

Chemistry Faculty Research and Publications

The dinucleating ligand ethylene glycol−bis(β-aminoethyl ether) N,N,N‘,N‘-tetrakis[(2-(1-ethylbenzimidazoyl)] (EGTB-Et; 1) was used to synthesize the dinuclear Ni(II) tetraacetonitrile complex cation [Ni₂(EGTB-Et)(CH₃CN)₄]²⁺ (2):  triclinic space group P1̄ (a = 12.273(5) Å, b = 12.358(7) Å, c = 12.561(6) Å, α = 90.43(4)°, β = 110.26(3)°, γ = 99.21 (4)°, and Z = 1). The structure shows two identical octahedral Ni(II) centers each bound to two benzimidazole ring nitrogen atoms, one amine nitrogen atom, an ether oxygen atom, and two acetonitrile nitrogen atoms. The …

Cleavage Of Dna By The Insulin-Mimetic Compound, Nh4[Vo(O2)2(Phen)], Catharina Hiort, Jerry Goodisman, James C. Dabrowiak

Chemistry - All Scholarship

The kinetics and mechanism of cleavage of DNA by the insulin-mimetic peroxo-vanadate NH4[VO(O2)2(phen)], pV, are described. In the presence of low energy UV radiation or biologically common reducing agents, pV decomposes into the monomer, dimer, and tetramer of vanadate and an uncharacterized compound of V4+ as shown by 51V NMR, ESR, and absorption spectra. The rate of photodecomposition of pV is reduced in the presence of calf thymus DNA, indicating that a decomposition product of the peroxo-vanadate, that is important in the destruction pathway of the complex, is interacting with DNA. This species, probably a short-lived complex of V4+, may …

Experimental Evidence For Self-Similar Structures In The Aggregation Of Porphyrins In Aqueous Solutions, F. Mallamace, N. Micali, S. Trusso, L. M. Scolaro, A. Romeo, A. Terracina, Robert F. Pasternack

Chemistry & Biochemistry Faculty Works

We have studied the aggregation of the porphyrin t-H₂Pagg in aqueous solution by light scattering. The intensity profile of the elastically scattered light, studied in the exchanged wave-vector range 0.2 ≤ q ≤ 31.4 μ m⁻¹, indicates that the aggregation produces large monodisperse clusters having a fractal structure, and is driven by diffusion-limited aggregation kinetics. Additional measurements performed at different q values confirm such a picture giving a hydrodynamic radius R(H) consistent with the radius of gyration R(g) measured by elastic scattering. This is explained taking into account the q² dependence observed in the mean decay rate of the intensity-intensity …

An Investigation On Nonenzymatic Autoxidation Of Phenolic Compounds In Natural Waters, Lei Jiang

Masters Theses

The nonenzymatic autoxidation of the phenolic compounds chlorogenic acid in aqueous solution was studied. The study demonstrated that the oxidation rate of chlorogenic acid was strongly dependent on pH. The higher the pH, the faster the rate of oxidation. The involvement of phenolate ions and radicals in oxidation reactions are two possible reasons for the pH dependency. The presence of a trace amounts of reducible transition metal ions, such as copper(II), dramatically increases the oxidation rate of chlorogenic acid. Light also increases the oxidation rate of chlorogenic acid. However, the photochemical reaction was a much slower process.

The TLC and …

A Graph Theoretic Study Of The Similarity Of Discrete Structures, Heather D. Gavlas

Dissertations

A basic problem in drug design consists of finding a compound that satisfies a spectrum of biological and chemical properties. Although drug design problems are central to pharmaceutical research, statisticians have yet to become involved in this area as these problems are viewed statistically as optimization problems. Before statistical optimization procedures can be defined on these spaces whose points are structures and not vectors, very basic mathematical notions of distance must be defined. Graphs have been used as mathematical models to represent the bonding arrangements of molecules for quite some time. In fact, if some of the methodology used by …

Speciation And Determination Of Trace Lead : Methodology Development And Analysis Of Natural Waters Using Chelex-100 And Gfaas, Xidan Ma

Theses

The development of a method for speciation, preconcentration, and determination of lead was successfully conducted using Chelex-100 and graphite furnace atomic absorption spectroscopy (GFAAS). Sorption under static conditions and direct measurements in the bead slurry or after fast elution of lead from beads with HNO3 solution was used. The effects of buffers, sorption kinetics, filtration criteria, sample concentration, resin particle size and temperature program for the GFAAS were carefully studied. In this study, synthetic aqueous samples containing lead were preconcentrated under static conditions using the ion exchange resin, Chelex-100, and the resin was directly analyzed using GFAAS. The batch preconcentration …

Methods And Methodologies For Organic Synthesis, Frank Favaloro

Honors Theses

Methods and methodologies for organic synthesis

Isolation From Soil Microorganisms That Are Inhibitory To Wheat Seeding Pathogens, Kynita Wilson-Humphrey

McCabe Thesis Collection

Many diseases caused by bacteria, viruses, or fungi are responsible for the ruin of a great number of crops annually. At present, many of these crops are being treated for diseases by synthetic or man-made chemicals. Some of the chemicals have been proved to have adverse effects on the environment, including humans and animals. Very few non-chemical means are available to farmers at this time to control these pathogens. This is due to the fact that many of the means of control have little effect against the pathogens or diseases. This research attempts to isolate microorganisms from the soil which …

Reconnecting The Sciences, John Eggebrecht, Raymond Dagenais, Don Dosch, Norman J. Merczak, Margaret N. Park, Susan C. Styer, David Workman

Faculty Publications & Research

During the last three years at the Illinois Mathematics and Science Academy, we have been working on a partial reconstruction of Whitehead's "one subject matter," a course reconnecting biology, chemistry, earth and space sciences, and physics into an Integrated Science program.

Critical Pressures In Multicomponent Lipid Monolayers, John P. Hagen, Harden M. Mcconnell

Chemistry and Biochemistry

Epifluorescence microscopy has been used previously to study coexisting liquid phases in lipid monolayers of dihydrocholesterol and dimyristoylphosphatidylcholine at the air/water interface. This binary mixture has a critical point at room temperature (22°C), a monolayer pressure of approx. 10 mN/m, and a composition in the vicinity of 20-30 mol% dihydrocholesterol. It is reported here that this critical pressure can be lowered, raised, or maintained constant by systematically replacing molecules of this phosphatidylcholine with molecules of a phosphatidylethanolamine, or an unsaturated phosphatidylcholine, or mixtures of the two, while maintaining the dihydrocholesterol concentration at 20 mol%. Thus, even complex mixtures of lipids …

Indirect Ultraviolet Detection Of Biologically Relevant Organic Acids By Capillary Electrophoresis, Hong Chen, Yan Xu, Frederick Van Lente, Michael P.C. Ip

Chemistry Faculty Publications

Indirect UV detection of fourteen short-chain organic acids (e.g., oxalic acid, citric acid, malonic acid, tartaric acid, methylmalonic acid, α-ketoglutaric acid, succinic acid, ethylmalonic acid, methylsuccinic acid, glutaric acid, apidic acid, methylglutaric acid, lactic acid and pyruvic acid) by capillary electrophoresis is described. The method used phthalate as the UV-absorbing additive in carbonate buffer and the non-absorbing analytes were detected indirectly at 230 nm. The influences of buffer pH, ionic strenght, concentration of phthalate and organic modifier on indirect signal response and migration behavior of the organic acids were investigated. Comparisons of reproducibility on migration time, limit of detection and …

The Advanced Glycation End Product, NE-(Carboxymethyl)Lysine, Is A Product Of Both Lipid Peroxidation And Glycoxidation Reactions, Min-Xin Fu, Jesus R. Requena, Alicia J. Jenkins, Timothy J. Lyons, John W. Baynes, Suzanne R. Thorpe

Faculty Publications

Nepsilon-(Carboxymethyl)lysine (CML) is an advanced glycation end product formed on protein by combined nonenzymatic glycation and oxidation (glycoxidation) reactions. We now report that CML is also formed during metal-catalyzed oxidation of polyunsaturated fatty acids in the presence of protein. During copper-catalyzed oxidation in vitro, the CML content of low density lipoprotein increased in concert with conjugated dienes but was independent of the presence of the Amadori compound, fructoselysine, on the protein. CML was also formed in a time-dependent manner in RNase incubated under aerobic conditions in phosphate buffer containing arachidonate or linoleate; only trace amounts of CML were formed from …

Pursuit Of A Chiral Amino Aldehyde Intermediate In The Synthesis Of (+)-Obafluorin, A B-Lactone Antibiotic, Jim Cwik '96

Honors Projects

This research is focused on synthesizing a chiral amino aldehyde from L-Serine. The proposed synthesis of the amino aldehyde would yield a stereochemically pure product working through an L-Serine beta-lactone intermediate. The amino aldehyde is a proposed intermediate in the synthesis of (+)-obafluorin, a beta-lactone antibiotic of interest. The proposed synthesis might provide a simpler, more versatile way to synthesize obafluorin.

Evaluation Of The Concentration And Enantiomeric Purity Of Selected Free Amino Acids In Fermented Malt Beverages (Beers), K. Helen Ekborg-Ott, Daniel W. Armstrong

Chemistry Faculty Research & Creative Works

Even though amino acids are important trace components in the brewing of beers, they have not been extensively evaluated in these beverages. Studies involving the enantiomeric composition of these amino acids are even less prevalent. A brief summary of the brewing process for malt beverages is given. The total concentration and enantiomeric composition of three amino acids (leucine, phenylalanine, and proline) were determined in 25 different beers. Proline tended to have the highest average absolute concentration and the lowest percentage of the D-enantiomer in most samples. In some cases the relative amounts of D-phenylalanine and D-leucine exceeded 10% of the …

Heme Proton Resonance Assignments And Kinetics Study In High-Spin And Mixed-Spin Metmyoglobin Complexes By Chemical Exchange Nmr Spectroscopy, Ying Luo

Dissertations and Theses

NMR studies of paramagnetic hemoproteins have improved significantly our understanding of the structure-function relationship of hemoproteins in general. Up to date most of the studies focus on low-spin ferric systems which are characterized by relatively narrow resonance peaks and concomitant better resolution.

However, characterizing in detail the NMR spectra of high-spin ferric hemoproteins is important since there are several hemoproteins, such as peroxidases, catalases, oxygenases, and some ferricytochromes that contain high-spin iron (III) in their biologically active forms. Yet assigning resonances from heme peripheral protons and/or heme pocket residues in high-spin myoglobins is a daunting undertaking. Only a sparse number …

Photoinduced Electron Transfer Along A Β-Sheet Mimic, Alexei B. Gretchikhine, Michael Y. Ogawa

Chemistry Faculty Publications

Electron energy-loss spectroscopy (EELS) is used to determine the energies of low-lying singlet and triplet states of the title compound. The EELS measurements give a splitting of 0.45 eV between the two lowest π f π* singlet states, as confirmed by optical absorption measurements, but do not give a discernable splitting between the corresponding triplet states. The experimental results are interpreted with the aid of ab initio electronic structure calculations using the CIS and CASPT2 methods. The calculations are consistent with the experiments, giving a much larger splitting between the π f π* singlet as compared to the π f …

Termolecular Proton Transfer Reactions Assisted By Ionic Hydrogen Bond Formation: Reactions Of Aromatic Cations With Polar Molecules, George M. Daly, Michael Mautner, Y. B. Pithawalla, M. Samy El-Shall

Chemistry Publications

We present a new method that applies resonant‐two‐photon ionization to generate reactant ions selectively in the source of a high‐pressure mass spectrometer (R2PI‐HPMS) for kinetic and equilibrium studies. Applications to reactions that would be obscured otherwise in a complex system are illustrated in mixtures of benzene with polar solvent molecules (S). We observe a novel type of proton transferreactions from C₆H₆ ^+• to two S molecules where S=CH₃CN, CH₃OH, C₂H₅OH and CH₃COOC₂H₅, and from C₆H₅CH₃ ^+• to two …

Substitution Reactions Of (C5ph5)Cr(Co)3: Structural, Electrochemical, And Spectroscopic Characterization Of (C5ph5)Cr(Co)2l, L = Pme3, Pme2ph, P(Ome)3, D. John Hammack, Mills M. Dillard, Michael Castellani, Arnold L. Rheingold, Anne L. Rieger, Philip H. Rieger

Chemistry Faculty Research

The radical complex (C₅Ph₅)Cr(CO)₃ reacts with small, neutral, monodentate Lewis bases (PMe₃, PMe₂Ph, P(OMe)₃) in THF at −78 °C (PMe₂Ph reacts at ambient temperature) to yield the monomeric substitution products (C₅Ph₅)Cr(CO)₂L·THF as thermally stable solids. Electrochemical and spectroscopic data are provided. An X-ray crystal structure of the hemisolvate (C₅Ph₅)Cr(CO)₂PMe₃·0.5THF was obtained. Frozen-solution ESR spectra of (C₅Ph₅)Cr(CO)₂L in toluene are comparable to those of other low-spin d^{5 …}

The Lipooligosaccharides Of Haemophilus Ducreyi Are Highly Sialylated, William Melaugh, A A. Campagnari, B W. Gibson

Chemistry Faculty Publications

The major lipooligosaccharides of the sexually transmitted pathogen Haemophilus ducreyi 35000 have been previously found to terminate in N-acetyllactosamine and sialyl-N-acetyllactosamine, Neu5Ac alpha 2-->3Gal beta 1-->4GlcNAc (W. Melaugh, N. J. Phillips, A. A. Campagnari, M. V. Tullius, and B. W. Gibson, Biochemistry 33: 13070-13078, 1994). In this study, mass spectrometry and composition analyses have shown that the lipooligosaccharides from three other H. ducreyi strains also contain N-acetyllactosamine and are highly sialylated (approximately 30 to 50%), although one African strain was found to contain neither of these structural features.

Space-Based Genetic Cryoconservation Of Endangered Species, Michael Noah Mautner

Chemistry Publications

Genetic materials of endangered species must be maintained, for cryoconservation, permanently near liquid nitrogen temperatures below 77 K. Due to the instability of human institutions, permanent safety is best provided at storage sites that maintain passively the needed low temperatures, and provide barriers to access. The required conditions are available in permanently shaded polar lunar craters with equilibrium temperatures of 8 to 40 K, on the moons of Saturn, and unshielded storage satellites. A genetic depository can be incorporated readily into planned lunar programmes.

A Monte Carlo Study Of Methanol Clusters (Ch3oh)N, N=5-256, D. Wright, M. S. El-Shall

Chemistry Publications

The thermodynamic and structural properties of methanol clusters (CH₃OH) _N , N=5–15, 20, 30, 60, 128, 256 and the bulk liquid have been investigated using Monte Carlo simulation. Calculated properties as a function of size include electrostatic and dispersive contributions to the configurational energy, configurational heat capacities,fractal dimension, density profiles, order parameters characterizing dipole and bond vector orientation, and the Lindemann index. The clusterheat capacities as a function of N possess an interior maximum near N=128 and converge to the bulk value from above. Monocyclic, semiplanar structures are found to persist at liquidlike temperatures up to …

Condensation Of Supersaturated Vapors Of Hydrogen Bonding Molecules: Ethylene Glycol, Propylene Glycol, Trimethylene Glycol, And Glycerol, David B. Kane, M. Samy El-Shall

Chemistry Publications

The critical supersaturations required for the homogeneous nucleation (rate of 1 drop cm⁻³ s⁻¹) of ethylene glycol, propylene glycol, trimethylene glycol and glycerol vapors have been measured over wide temperature ranges (e.g., 280–400 K) using an upward thermal diffusion cloud chamber. At lower temperatures the experimental nucleation rates are much higher than the predictions of the classical nucleation theory. Glycerol shows the best agreement between experiment and theory in the temperature range of 340–370 K. An apparent increase in the critical supersaturation of glycerol is observed with increasing carrier gas (helium) pressure and this effect is more …