Physical Sciences and Mathematics Commons^™

Preparation And Testing Of Novel Dental Adhesives Based On Bis- Gma/Tegdma Monomer System, Deyun Sun

Theses

In this study, polymerizable phosphonate adhesives synthesized from Diethylchloro-phosphate and 2-Hydroxyethylmethylacrylate and formulated with G-methacryloxy-propyltrimethoxy silane is used in Bis-GMA/TEGDMA monomer system. All the raw materials and finished products are characterized with infrared spectra, vapor pressure osmometry, viscosity and gel test. The bonding strength to tooth materials is determined by Instron machine. The work emphasizes applying polymeric organic phosphonate adhesive to Bis-GMA/TEGDMA monomer system and investigates the appropriate conditions for the crosslinking of Bis-GMA/TEGDMA monomer system. Average bonding strength of 744 psi to enamel and 600 to dentine are ob¬tained in comparision to 550 psi to enamel for phosphonate/silane/MMA/PMMA and …

Methods Development For Determination Of Trace Polar Volatile Organics In Environmental Samples, Qingchu Peng

Theses

The determination of trace levels of organic compounds in water samples is well developed for the less polar compounds, but the polar compounds are more difficult. The development of reliable and reproducible methods for such compounds as volatile alcohols and ketones is necessary if environmental monitoring is to be extended to these compounds.

The purge-and-trap method is frequently used for determination of volatiles in water samples. The method has problems when hydrophylic substances are being analyzed, since these are less easy to purge from the solution and more difficult to trap and desorb quantitatively. The high amount of water carried …

Evidence For An Unusual Kinetic Phenomenon In The Metallation Of Porphyrins, F. González-Vílchez, R. A. Vilaplana, Robert F. Pasternack

Chemistry & Biochemistry Faculty Works

Reaction of copper(II) with water soluble porphyrins (H₂porph) in the presence of ethylenediamine shows an unusual and so far unreported kinetic phenomenon that can be explained in terms of supramolecular assembly formation apparently involving all solute species as confirmed via light scattering and conductivity measurements.

The Influence Of Cation Size Upon The Infrared Spectrum Of Carbon Monoxide Adsorbed On Platinum Electrodes, Mark Anderson, Jimin Huang

Mark R. Anderson

No abstract is currently available.

A New Twist On Pseudorotation, Theresa L. Windus, Mark S. Gordon, Larry W. Burggraf, Larry P. Davis

Mark S. Gordon

For pentacoordinated structures in a trigonal bipyramidal ar· rangement, Berry1 proposed a "pseudorotation" mechanism whereby two such isomers can interconvert through a tetragonal transition state (TS). This Berry pseudorotation mechanism was demonstrated explicitly for SiH5- by following the MP22/6· 31G(d)3 minimum energy path4 (MEP).

Structure Of 2,9-Dimethyl-1,10-Phenanthroline Hemihydrate, Doyle Britton, Larry C. Thompson, Richard C. Holz

Chemistry Faculty Research and Publications

C₁₄H₁₂N₂•½H₂O, M_r = 217•27, tetragonal I4₁/a, a = 14•258 (3), c = 22•286 (4) Å, V = 4531 (3) ų, Z = 16, D_x = 1•274 (1) g cm^-3, Mo Kα radiation λ = 0•71073 Å, µ = 0•74 cm^-1, F(000) = 1840, T = 297 K, R = 0•041 for 1196 unique observed reflections with I > 2σ(I). Pairs of dimethylphenanthroline molecules related by a twofold axis are bridged by water molecules lying on the twofold …

Evolved Gas Analysis Using Coupled Tg-Cg & Tg-Ftir, Keith Bradfield

Masters Theses & Specialist Projects

Thermal analysis methods have ben used for many years for material characterization. In recent years, thermal methods have been coupled to other methods of chemical analysis to obtain more complete material characterization. This study looks at thermal decomposition of polymer samples as well as coal samples in atmospheres of nitrogen and air. The thermal analysis instrument used was coupled to a Gas Chromatograph (GC) and a Fourier Transform Infrared Spectrometer (FTIR) so that the gaseous products evolved during thermal decomposition could be analyzed. The results obtained show that the coupled techniques of TG -GC and TG-FTIR can show pyrolysis and …

The Limitations Of Women In Science At Six Midwestern Colleges Due To The Adherence To Conceptions Of Gender Differences Between The Sexes In The Years Of 1880 Through 1940, Denise Mohney '91

Honors Projects, History

It is difficult for college students today to imagine life when the term "discrimination" had not yet been defined or conceived. Yet only a little more than a hundred years ago women were first entering the academic world alongside men. These were often middle class women whose primary interactions with men had been through courtship and marriage. It was questioned whether women's intellectual ability and physical stamina were strong enough to persevere through the college experience. Scientists and physicians, writing for the general public, cited evidence that besides physical distinctions between the sexes, there were also intellectual and emotional differences. …

Electrostatically Paired Porphyrin And Phthalocyanine: Equilibria And Electrochemical Oxidation, Libin Ho '91

Honors Projects

A synthetic model system for the special pair in the photosynthetic reaction center of bacteria has been prepared from electrostatically paired porphyrin and phthalocyanine molecules. Use of rigorously dry propylene carbonate as the solvent allowed complex fonnation to occur between tetra-(N-methyl-4-pyridyl)porphyrin hexafluorophosphate (H2TMPyP(PF6)4) and tetraphenylphosphonium tetrasulfatophthalocyanine (Ph4P)4H2TSPc molecules. The stoichiometry of the complex was determined to be 1:1 by Job's method and the pair formation constant K1 was estimated to be 1x108.T he dependence of K1 on ionic strength was studied at various concentrations of tetra-n-butylammonium tetrafluoroborate BU4NBF4. With increasing ionic strength K1 decreases as expected according to the Debye-Huckellimiting …

Sniftirs Study Of The Behavior Of The Spectrum Of Carbon Monoxide Adsorbed On A Platinum Electrode In Alcoholic Solvents, Andrea Russell, Daniel Blackwood, Mark Anderson, Stanley Pons

Mark R. Anderson

The vibrational spectrum of carbon monoxide as a function of coverage in various alcoholic solvents was investigated using the SNIFTIRS technique. At low coverage the potential dependence of the band position was found to be linearly dependent on the inverse of the bulk dielectric constant of the solvent. An electrostatic model was developed to represent the interaction between adjacent adsorbate molecules. This model provides evidence in support of an island formation mechanism.

Synthesis And Characterization Of An 18-Membered Macrocyclic Ligand Containing 2,2-Biimidazole For Selective Binding Of Transition Metal Ions, Mark Barnett

Opportunities for Undergraduate Research Experience Program (OURE)

A description of the synthetic approach to the preparation of an 18 membered macrocyclic ligand containing 2/2'-biimidazole is presented. A diol derivative of 2,2'-biimidazole is tosylated with p-toluene sulfonyl chloride making it susceptible to bimolecular substitution with a disodium salt of tetratosylated triethylenetetraamine. The final desired product is an 18N6 macrocycle, 4,7-(l,l'-(2,2'-biimidazolo))-l,4,7,10,13,16-hexaazacyclooctadecane, potentially capable of binding transition metal ions in various combinations with three chelating sites. Initial characterization includes NMR and IR spectroscopic analysis.

Analysis Of Two Circuits For Detecting Superconducting Transition Temperatures, Terry Bowness

Opportunities for Undergraduate Research Experience Program (OURE)

When measuring the transition temperature of large numbers of high T_c superconducting samples it is desirable to have available equipment that is both easy to operate and reliable. In addition should anything malfunction, the device should be relatively simple to repair. One method of measurement involves placing a sample in the magnetic field of an inductor, the inductor being an active member of some type of oscillating circuit. There are many standard oscillator designs which can be used for this type of application. In this report two such circuits, the tunnel diode and Hartley oscillators, will be examined and …

Model Calculational Approach To The Conformation Of Adsorbed Polypeptide Fragments, Timothy J. Mckeon

Opportunities for Undergraduate Research Experience Program (OURE)

The focus of the paper is to examine possible conformational changes of peptides when placed in the presence of a poly-synthetic material. A major concern in the pharmaceutical industry is the loss of potency of polypeptide drug products during processing, packaging and storage. An example of this is polymer syringes being used in place of glass ones. The effect is that some protien-derived products experience structural changes due to contact with the polymer. This is otherwise known as surface denaturation. In order to understand the energetics of interfacial polypeptide systems, a calculational approach was used via the program Alchemy. The …

Enantiomeric Separation By Cloud Point Precipitation Of Cyclodextrins, Deanna L. Schmid

Opportunities for Undergraduate Research Experience Program (OURE)

Certain cyclodextrins exhibit a diminishing solubility in water when heated. This phenomena of cloud point precipitation in conjunction with cyclodextrin's ability to form an inclusion complex with many compounds, can be used as a method of chemical separation. These cyclodextrins can be removed from the solution after precipitation by a hot filtration technique and the remaining solution analyzed by HPLC. Enantiomeric separations, concentration of compounds and removal of hazardous organic materials are all possible applications of cloud point extraction using cyclodextrins.

Fourier Transform Infrared (Ftir) Spectroscopy Analysis Of Combustion Aerosol, Gary Jacquin

Opportunities for Undergraduate Research Experience Program (OURE)

In conjunction with my co-op program at McDonnell-Douglas, my current OURE project is the analysis of combustion aerosols using Fourier Transform Infrared (FTIR) Spectroscopy. Aerosol science is a very important field as it is concerned with atmospheric chemistry, atmospheric physics, climate, public health, and environmental issues.

In the Cloud and Aerosol Sciences Laboratory (CASL) at UMR, combustion aerosols are generated by an in-house designed torch or burner. The fuels, JP4 and JP5, are provided by McDonnell-Douglas. Some other commercial fuels are also used. The primary objective of my OURE project was to generate and collect combustion aerosols for chemical analysis. …

Stimulation Of Amorphous Layers In The Co-Si System By Third Element Additions, Denise Brandt

Opportunities for Undergraduate Research Experience Program (OURE)

Multilayer thin films play an important role in our technology today. They can be found in many devices such as magnetic hard disks, microelectronic circuits, and x-ray optical elements. In many of these metal-metal and metal-metalloid multilayers, amorphous layers have been discovered using various techniques such as extended x-ray absorption fine structure (EXAFS) and high resolution transmission electron microscopy (HTEM). These amorphous layers enhance the magnetic and electrical properties of the alloy. They also affect the mechanical and structural properties of the system.

The solid state amorphous reactions (SSAR) occur whether the layers are formed by epitaxy or by sputtering. …

The Synthesis And Characterization Of Metal Binding Polymers Containing 2,2'-Biimidazole, Renee Proctor

Opportunities for Undergraduate Research Experience Program (OURE)

Epoxides are known to form ring-opened polymer products that have demonstrated improved material strength, high heat stability, and chemical resistance as adhesives, coatings, and molding materials. It has been suggested that imidazoles can be used in the catalysis of this polymerization, and that the pyridyl nitrogen of the imidazole ring participates in epoxy ring-opening and is then incorporated in the polymeric structure. This study was conducted to test this theory of the role of pyridyl nitrogen in the reaction of 1,1'- dihydroxyethyl-2,2’-biimidazole (HEB) and metal-HEB complexes in reactions with the diglyddyl ether of bisphenol A (DGEBA). Of particular interest in …

An Analysis Of Dissolved Organic Compounds And Their Contribution To Iron Complexation In The Shallow Leachate Plume Of The West Kl Landfill Kalamazoo, Michigan, Eric Fahle

Masters Theses

High concentrations of dissolved iron are present in downgradient groundwater samples adjacent to the western border of the West KL Landfill. Analysis by Rudder (1988) of groundwater samples indicates oversaturation of selected iron oxides, iron sulfides and siderite in monitoring wells TW-4 and M3.

Previous research suggests that pyrogallol, gallic acid, tannic acid and similar organic compounds may retard the oxidation of ferrous iron in the shallow leachate plume of the West KL landfill (Rudder, 1988). Present research utilizing solid phase extraction, reverse phase high performance chromatography, Fourier transform IR spectrophotometry, UV/Visible spectrophotometry, and gas chromatography/mass spectroscopy indicate that pyrogallol, …

A Mössbauer-Effect Study Of A Series Of R₂Fe₁₄C Hard Magnetic Materials, Gary J. Long, Oran Allan Pringle, Gaya Kanishka Marasinghe, Fernande Grandjean, K. H. Buschow

Chemistry Faculty Research & Creative Works

The ⁵⁷Fe Mössbauer-effect spectra of the series of hard magnetic materials, R₂Fe₁₄C, where R is Nd, Gd, Tb, Dy, Ho, and Lu, have been measured at 295 K. All of these carbides exhibit uniaxial magnetic anisotropy. The spectra resemble those obtained for the related R ₂Fe₁₄B compounds and have been fit with the model used earlier for Nd₂Fe₁₄B. The magnitude of the hyperfine field on each site, as a function of rare earth, parallels the Curie temperature; the maximum hyperfine fields and the maximum Curie temperature are observed …

Molecular-Orbital Studies Via Satellite-Free X-Ray Fluorescence: Cl-K Absorption And K–Valence-Level Emission Spectra Of Chlorofluoromethanes, Rupert C. Perera, P. L. Cowan, Dennis W. Lindle, R. E. Lavilla, T. Jach, R. D. Deslattes

Chemistry and Biochemistry Faculty Research

X-ray absorption and emission measurements in the vicinity of the chlorine K edge of the three chlorofluoromethanes have been made using monochromatic synchrotron radiation as the source of excitation. By selectively tuning the incident radiation to just above the Cl 1s single-electron ionization threshold for each molecule, less complex x-ray-emission spectra are obtained. This reduction in complexity is attributed to the elimination of multielectron transitions in the Cl K shell, which commonly produce satellite features in x-ray emission. The resulting "satellite-free" x-ray-emission spectra exhibit peaks due only to electrons in valence molecular orbitals filling a single Cl 1s vacancy. These …

The Reactions Of N-Phenylaminoiminomethanesulfonic Acid (Paimso) With Meldrum's Acid, Milana-Minja Maletic '91

Honors Projects

No abstract provided.

A Study Of The Reactions Of P-Dipiperidino Benzene And Its Synthesis From 1,4-Dicyano-1,4-Dipiperidinocyclohexane, Ilias Konstantinos Dorziotis

Chemistry & Biochemistry Theses & Dissertations

Following a classical synthesis of PCP² Williams attempted to prepare l,4-diphenyl-1,4-dipiperidino cyclohexane 4¹ . This approach involved the preparation of 1,4- dicyano-1,4-dipiperidinocyclohexane 7 and the subsequent decyanation of the compound with phenylmagnesium bromide to produce 4. This attempt failed, however, as only the monophenylated product, 8, was thought to be obtained. This product had unique reactivity, producing a blue intermediate upon treatment with halogen in both aqueous and non aqueous media. The same intermediate was produced upon irradiation of a chloroform solution of this product with sunlight or UV light in a UV chamber, with the …

Analytical Modeling And Simulation For Investigation Of A Digital Gas Filter Correlation Radiometer, Catherine P. Mcgowan

Electrical & Computer Engineering Theses & Dissertations

This thesis investigates a digital gas filter correlation radiometer called the Tropospheric Radiometer for Atmospheric Chemistry and Environmental Research (TRACER), which will be used to remotely measure carbon monoxide at three levels in the troposphere. The nadir-viewing radiometer measures the differential absorption of radiation through the atmosphere at 4.67@m and 2.33pm wavelengths. This thesis develops an analytical model of the TRACER measurement process to evaluate the effect of varying certain system parameters on the measurement. The independent sampling criterion and the response of linear systems to random signals are explained. A parametric simulation model is also developed to evaluate the …

Multiphoton Ionization Of Nitrobenzene In Non-Aqueous Solutions: Characterization Of The Cation And Ion-Molecule Chemistry, G. Siuzdak, J. J. Belbruno

Dartmouth Scholarship

The phenoxy cation has been generated in polar and nonpolar solutions by multiphoton ionization of nitrobenzene using nanosecond pulses of 266 nm and 355 nm light. The ions have been characterized by pulsed conductivity (ion mobility) measurements and transient absorption spectroscopy. The involvement of the phenoxy ion in ion-molecule chemistry with either neutral solute or solvent molecules has also been observed and the photochemical products and quantum yields of the ion-molecule products are presented and compared with the neutral photochemistry results.

Nonadiabatic Electronic Interactions In The Ion-Pair States Of Nelcl, Thomas Alex Stephenson, Y. Hong, M. I. Lester

Chemistry & Biochemistry Faculty Works

Nonadiabatic interactions in the NeIC1 van der Waals complex have been explored in the lowest energy triad of IC1 ion-pair states (approximately 39 000 cm-1). Dispersed fluorescence measurements reveal emission characteristic of multiple ion-pair electronic states, with the relative contributions from the E(O+ ), beta(1), and D'(2) states changing with the initial IC1 vibrational excitation (v(IC1)). Emission directly from NeIC1 (v(IC1) = O) complexes indicates that the initially prepared NeIC1 levels have mixed electronic character and that the IC1 electronic parentage changes with the initial van der Waals vibrational level selected. NeIC1 complexes prepared with 1-4 quanta of IC1 stretch …

Gas-Phase Chemistry Of The Dimethylaluminum Oxide Ion And Related Aluminum Oxide Ions: Comparison Of Reactivity With Siloxide Ions, Robert Damrauer, Michèle Krempp, Michael W. Schmidt, Mark S. Gordon

Mark S. Gordon

The anion [(CH3hAIOt (1) has been prepared in a flowing afterglow selected ion flow tube (FA-SIFT) by ion selection from the reaction mixture of trimethylaluminum dimer and hydroxide. This unusual ion is quite reactive and has been extensively studied. It reacts with halogen-containing compounds of several types, including fluorobenzene, chlorobenzene, bromofluorobenzene, acetyl chloride, and HF, to give [(CH3hAI(OH)Xt, where X = F, Cl, and Br. Its chemistry with hexafluorobenzene and silicon tetrafluoride has also been detailed as have a number of reactions with carboxylic acids, esters, anhydrides, sulfur-containing neutrals, alcohols, water, and ammonia. The dominant reaction pattern of 1 involves …

Polarized X-Ray-Emission Studies Of Methyl Chloride And The Chlorofluoromethanes, Dennis W. Lindle, P. L. Cowan, T. Jach, R. E. Lavilla, R. D. Deslattes, Rupert C. Perera

Chemistry and Biochemistry Faculty Research

A new technique sensitive to molecular orientation and geometry, and based on measuring the polarization of x-ray emission, has been applied to the Cl-containing molecules methyl chloride (CH₃Cl) and the chlorofluoromethanes (CF₃Cl, CF₂Cl₂, and CFCl₃) in the gas phase. Upon selective excitation using monochromatic synchrotron radiation in the Cl K-edge (Cl 1s) near-threshold region, polarization-selective x-ray emission studies reveal highly polarized molecular valence x-ray fluorescence for all four molecules. The degree and the orientation of the polarized emission are observed to be sensitive to the incident excitation energy near …

Stability And Structure Of Three-Way Dna Junctions Containing Unpaired Nucleotides, Neocles B. Leontis, Wendy Kwok, Jennifer S. Newman

Chemistry Faculty Publications

Non-paired nucleotides stabilize the formation of three-way helical DNA junctions. Two or more unpaired nucleotides located in the junction region enable oligomers ten to fifteen nucleotides long to assemble, forming conformationally homogeneous junctions, as judged by native gel electrophoresis. The unpaired bases can be present on the same strand or on two different strands. Up to five extra bases on one strand have been tested and found to produced stable junctions. The formation of stable structures is favoured by the presence of a divalent cation such as magnesium and by high monovalent salt concentration. The order-disorder transition of representative three-way …

Equilibrium And Non-Equilibrium Complex Fragment Emission In 50-100 Mev/U 139la + 12c Reactions, D. R. Bowman, Graham F. Peaslee, N. Colonna, R. J. Charity, M. A. Mcmahan, D. Delis, H. Han, K. Jing, G. J. Wozniak, L. G. Moretto, W. L. Kehoe, B. Libby, A. C. Mignerey, A. Moroni, S. Angius, I. Iori, A. Pantaleo, G. Guarino

Faculty Publications

Complex fragment emission (Z > 2) has been studied in the reactions of 50, 80, and 100 MeV/u139La + 12C. Charge, angle, and energy distributions were measured inclusively and in coincidence with other complex fragments, and were used to extract source rapidities, velocity distributions, and cross sections. The binary signature of the coincidence events and the sharpness of the velocity distributions illustrate the primarily 2-body nature of these reactions. Calculations based on statistical compound nucleus decay have been compared with the experimental data. The emission velocities, angular distributions, and absolute cross sections of fragments of 20 ⩽ Z ⩽ 35 at …

N-Acetoxy-N-Acetyl-2-Aminofluorene Binding Sites On [Phi] X174 And Sv40, Marta L. Bascoy

FIU Electronic Theses and Dissertations

Restriction enzyme inhibition and lambda exonuclease studies indicate that carcinogen N-acetoxy-N-acetyl-2 aminofluorene (AAAF) binds to sequences on ɸX174 RF and SV40 plasmids DNA that are similar to the eight preferred binding sites previously located on pBR 322.

Both DNAs were digested with enzyme Hinf I and resultant fragments 32P end-labeled. Labeled fragments were reacted with the carcinogen to give one to sixteen bound moieties per DNA. Fragments were isolated and restriccion enzyme and lambda exonuclease inhibition assays were performed.

Inhibition detected occurred at selected sites and was not specific for a certain enzyme or certain size of recognition sequence.

Results …