Open Access. Powered by Scholars. Published by Universities.®

Physical Sciences and Mathematics Commons™

Open Access. Powered by Scholars. Published by Universities.®

Chemistry

PDF

Faculty Publications

1998

Articles 1 - 16 of 16

Full-Text Articles in Physical Sciences and Mathematics

Determination Of Chloride Concentration Using Capillary Zone Electrophoresis: An Instrumental Analysis Chemistry Laboratory Experiment, Michael A. Janusa Nov 1998

Determination Of Chloride Concentration Using Capillary Zone Electrophoresis: An Instrumental Analysis Chemistry Laboratory Experiment, Michael A. Janusa

Faculty Publications

Capillary zone electrophoresis (CZE) has received a great deal of attention as a tool for the separation and detection of low-molecular-mass inorganic ions. CZE is a fast growing analytical technique that uses a low-volume sample accompanied by a high detection efficiency. Since this is a fairly new analytical technique that shows tremendous promise, it should be introduced to students at the undergraduate level. We have developed a CZE experiment that is well suited for an instrumental analysis chemistry laboratory and can be modified for other species or substances.

Go to article

Monte Carlo Simulation Of An Ion-Dipole Mixture As A Model Of An Electrical Double Layer, Douglas Henderson, Dezso Boda, Kwong-Yu Chan Nov 1998

Monte Carlo Simulation Of An Ion-Dipole Mixture As A Model Of An Electrical Double Layer, Douglas Henderson, Dezso Boda, Kwong-Yu Chan

Faculty Publications

Canonical Monte Carlo simulations were performed for a nonprimitive model of an electrical double layer. The ions and the solvent molecules are modeled as charged and dipolar hard spheres, respectively, while the electrode as a hard, impenetrable wall carrying uniform surface charge. We found that the ion-dipole model gives a reasonable description of the double layer for partially charged ions with small to moderate dipole moments, or equivalently for an "effective" dielectric constant. Density, polarization and mean electrostatic potential profiles are reported. Strong layering structure, and at higher charges, charge inversion in the second layer were found. With appropriate choices …

Go to article

Chemical Signals From Submarine Fluid Advection Onto The Continental Shelf, W. S. Moore, Timothy J. Shaw Sep 1998

Chemical Signals From Submarine Fluid Advection Onto The Continental Shelf, W. S. Moore, Timothy J. Shaw

Faculty Publications

No abstract provided.

Go to article

Correlation Function Formulation For The State Selected Total Reaction Probability, Sophya Garashchuk, David J. Tannor Aug 1998

Correlation Function Formulation For The State Selected Total Reaction Probability, Sophya Garashchuk, David J. Tannor

Faculty Publications

Investigates the correlation function formulation for the state selected total reaction probability. Discussion of the wave packet propagation; Derivation of the correlation function expression for the N[sub alpha](E); Application of quantum-mechanical and Herman-Kluk propagation methods.

Go to article

Orientational Susceptibility And Elastic Constants Near The Nematic-Isotropic Phase Transition For Trimers With Terminal-Lateral-Lateral-Terminal Connections, Daeseung Kang, Milind P. Mahajan, Rolfe G. Petschek, Charles Rosenblatt, Chaobin He, Puwei Lu, A.C. Griffin Aug 1998

Orientational Susceptibility And Elastic Constants Near The Nematic-Isotropic Phase Transition For Trimers With Terminal-Lateral-Lateral-Terminal Connections, Daeseung Kang, Milind P. Mahajan, Rolfe G. Petschek, Charles Rosenblatt, Chaobin He, Puwei Lu, A.C. Griffin

Faculty Publications

Magnetically induced Freedericksz measurements were performed in the nematic liquid crystal phase to extract the elastic constants of a terminal-lateral-lateral-terminal trimer, i.e., a trimer in which the connections to the first and third mesogens are at the end of the mesogen and both attachments to the central mesogen are lateral. Polymeric liquid crystals based on this unit have negative Poisson ratios. Additionally, electric field Kerr measurements were performed in the isotropic phase to extract the orientational susceptibility. The elastic constants were found to be similar to values obtained for typical monomers, albeit with a slightly enhanced ratio K-33/K-11 and reduced …

Go to article

Role Of The Maillard Reaction In Aging Of Tissue Proteins: Advanced Glycation End Product-Dependent Increase In Imidazolium Cross-Links In Human Lens Proteins, Elisabeth Brinkmann Frye, Thorsten P. Degenhardt, Suzanne R. Thorpe, John W. Baynes Jul 1998

Role Of The Maillard Reaction In Aging Of Tissue Proteins: Advanced Glycation End Product-Dependent Increase In Imidazolium Cross-Links In Human Lens Proteins, Elisabeth Brinkmann Frye, Thorsten P. Degenhardt, Suzanne R. Thorpe, John W. Baynes

Faculty Publications

Dicarbonyl compounds such as glyoxal and methylglyoxal are reactive dicarbonyl intermediates in the nonenzymatic browning and cross-linking of proteins during the Maillard reaction. We describe here the quantification of glyoxal and methylglyoxal-derived imidazolium cross-links in tissue proteins. The imidazolium salt cross-links, glyoxal-lysine dimer (GOLD) and methylglyoxal-lysine dimer (MOLD), were measured by liquid chromatography/mass spectrometry and were present in lens protein at concentrations of 0. 02-0.2 and 0.1-0.8 mmol/mol of lysine, respectively. The lens concentrations of GOLD and MOLD correlated significantly with one another and also increased with lens age. GOLD and MOLD were present at significantly higher concentrations than the …

Go to article

Solute-Solvent Pair Distribution Functions In Highly Asymmetric Additive Hard Sphere Mixtures, Douglas Henderson, Kwong-Yu Chan Jun 1998

Solute-Solvent Pair Distribution Functions In Highly Asymmetric Additive Hard Sphere Mixtures, Douglas Henderson, Kwong-Yu Chan

Faculty Publications

Contact values for the solute-solvent pair distribution function in an additive hard sphere mixture, as computed from the Henderson-Chan (HC) formulas, are compared with the recent Monte Carlo (MC) data and formula of Matyushov and Ladanyi (ML) [J. Chem. Phys. 107, 5815 (1997)]. The agreement is found to be excellent. The negative finding of ML is due to a misprint in one of the HC publications. We find the HC formula to be superior to the ML formula when compared to our MC data [Mol. Phys. 91, 1137 (1997)] for the case where the ratio of diameters is large and …

Go to article

The Effect Of Convection On A Propagating Front With A Liquid Product: Comparison Of Theory And Experiments, B. Mccaughey, John A. Pojman, C. Simmons, V.A. Volpert Jun 1998

The Effect Of Convection On A Propagating Front With A Liquid Product: Comparison Of Theory And Experiments, B. Mccaughey, John A. Pojman, C. Simmons, V.A. Volpert

Faculty Publications

This work is devoted to the investigation of propagating polymerization fronts converting a liquid monomer into a liquid polymer. We consider a simplified mathematical model which consists of the heat equation and equation for the depth of conversion for one-step chemical reaction and of the Navier-Stokes equations under the Boussinesq approximation. We fulfill the linear stability analysis of the stationary propagating front and find conditions of convective and thermal instabilities. We show that convection can occur not only for ascending fronts but also for descending fronts. Though in the latter case the exothermic chemical reaction heats the cold monomer from …

Go to article

In Situ Detection Method For Glutaminyl Cyclase Activity In Polyacrylamide Gels, Justin B. Houseknecht, Jeffrey S. Temple, Robert C. Bateman Jr. Mar 1998

In Situ Detection Method For Glutaminyl Cyclase Activity In Polyacrylamide Gels, Justin B. Houseknecht, Jeffrey S. Temple, Robert C. Bateman Jr.

Faculty Publications

No abstract provided.

Go to article

Single-Head Spin Modes In Frontal Polymerization, Victor M. Ilyashenko, John A. Pojman Mar 1998

Single-Head Spin Modes In Frontal Polymerization, Victor M. Ilyashenko, John A. Pojman

Faculty Publications

The single-head spin mode is the first two-dimensional pattern of self-propagating thermal reaction fronts observed after the planar front loses stability. A "hot spot" is observed to propagate around the periphery of the front. The dynamics of the single-head frontal polymerization regime were studied experimentally, and two novel results were found. The "hot spot" was measured and found to be superadiabatic. The relationship between the rotational velocity and the propagating velocity was found. Experimental data were also compared with the theoretical results based on the linear stability analysis and found to be in a reasonable agreement. (C) 1998 American institute …

Go to article

Effects Of Curing Temperature On The Leachability Of Lead Undergoing Solidification/Stabilization With Cement, Michael A. Janusa Jan 1998

Effects Of Curing Temperature On The Leachability Of Lead Undergoing Solidification/Stabilization With Cement, Michael A. Janusa

Faculty Publications

Curing temperature was found to dramatically affect the amount of waste leached from a solidified waste/cement matrix between 2 and 40°C. Using lead nitrate as a model waste, samples cured for 7,14, and 28 days at a cure temperature of 40°C leached very little lead (1-3 mg/liter), while at a cure temperature of 2°C samples leached approximately 25 times more lead (20-90 mg/liter). The results indicate that curing temperature is a very crucial variable to consider when solidifying waste with cement if maximum stabilization is to be achieved.

Go to article

Effects Of Particle Size And Contact Time On The Reliability Of Toxicity Characteristic Leaching Procedure For Solidified/Stabilized Waste, Michael A. Janusa Jan 1998

Effects Of Particle Size And Contact Time On The Reliability Of Toxicity Characteristic Leaching Procedure For Solidified/Stabilized Waste, Michael A. Janusa

Faculty Publications

Inconsistency in leaching results using the Toxicity Characteristic Leaching Procedure (TCLP)indicates that the procedure should contain specific guidance with respect to the following parameters: ( 1 ) minimum particle size, (2) contact time limit between leachant and waste. Experimental datas how that there is approximately a 50% decrease in the amount of waste leached when a minimum particle size of 8 mm is applied. Results indicate that as the contact time between leachant and waste increases, the amount of waste leached increases drastically. The results suggest that restrictions should be set on these two parameters for TCLP results to be …

Go to article

Radicals, Metals And Magnetism, David J R Brook Jan 1998

Radicals, Metals And Magnetism, David J R Brook

Faculty Publications

The interaction between unpaired electrons governs many physical properties of materials. Although in a fundamental sense the interaction is simple, a full understanding of the interaction in molecular systems is complicated by the presence of other bonding and non-bonding electrons. The resulting many body problem is very challenging. Nevertheless, much qualitative understanding can be obtained from applying simple molecular orbital theory and considering only the partly filled orbitals. The resulting model can be used to describe existing diradical and metal-radical systems and also has predicative value in the search for molecular magnets and design of nanoscale devices.

Go to article

Palladium-Catalyzed Carboxylation Of Allyl Stannanes And Carboxylative Coupling Of Allyl Stannanes And Allyl Halides [Abstract], Russell J. Franks Jan 1998

Palladium-Catalyzed Carboxylation Of Allyl Stannanes And Carboxylative Coupling Of Allyl Stannanes And Allyl Halides [Abstract], Russell J. Franks

Faculty Publications

The reaction of allyl stannanes with CO2 to form stannyl carboxylates (esters) is catalyzed by Pd(PR3)4 complexes. Thus, R3SnCH2CH=CH2 [R=Me and Ph]are converted to R3SnO2 CCH2CH=CH2 and R3SnO2CCH=CHCH3 under 33 atm of CO2 (70°C, THF) in moderate to excellent yield in the presence of 8 mol% Pd(PPh3)4 ; polycarboxylation of diallyldibutyltin and tetraallyltin also is effected, producing the respective di- and tetracarboxylates, Bu2Sn(O2CCH2CH=CH2)2 and Sn(O2CCH …

Go to article

Ab Initio Study Of Formazan And 3-Nitroformazan, G. Buemi, F. Zuccarello, P. Venuvanalingam, M. Ramalingam, Salai Cheettu Ammal Jan 1998

Ab Initio Study Of Formazan And 3-Nitroformazan, G. Buemi, F. Zuccarello, P. Venuvanalingam, M. Ramalingam, Salai Cheettu Ammal

Faculty Publications

Formazan and 3-nitroformazan have been investigated at abinitio level (MP2/6-31G** and B3LYP/6-31G**) in all their possible conformations, for studying the various possibilities of intramolecular hydrogen bonding formation. The trans-syn-s-cis (TSSC), known also asyellowform, has been found to be the most stable conformer (at least in the gas phase) in both compounds. This particular structure is strongly stabilized by a N–H···N hydrogen bridge, which gives rise to a hexatomic chelate ring, with the possibility of a proton transfer process.This closely resembles that of malondialdehyde, previously studied, in the evolution of the …

Go to article

Ab Initio And Dft Investigations Of Lithium/Hydrogen Bonded Complexes Of Trimethylamine, Dimethyl Ether And Dimethyl Sulfide, Salai Cheettu Ammal, P. Venuvanalingam Jan 1998

Ab Initio And Dft Investigations Of Lithium/Hydrogen Bonded Complexes Of Trimethylamine, Dimethyl Ether And Dimethyl Sulfide, Salai Cheettu Ammal, P. Venuvanalingam

Faculty Publications

Ab initio and DFT computations have been carried out on LiF and HF complexes of a set of n-donors viz. trimethylamine, dimethyl ether and dimethyl sulfide with a 6-31++G(d,p) basis set. The effect of correlation has been included with MP2, MP4 and DFT calculations. NBO analyses of the wavefunctions have been performed to examine the intermolecular interaction at the orbital level. Calculations reveal that these donors form strong n→σ* complexes and computed binding energies of the (CH3)2O···HF complex agree very well with the experimental binding energies from IR spectroscopy. LiF forms stronger complexes than HF, …

Go to article