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Chemistry Faculty Research & Creative Works

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Full-Text Articles in Chemistry

Effect Of Micelles And Mixed Micelles On Efficiency And Selectivity Of Antibiotic-Based Capillary Electrophoretic Enantioseparations, Kimber L. Rundlett, Daniel W. Armstrong Jul 1995

Effect Of Micelles And Mixed Micelles On Efficiency And Selectivity Of Antibiotic-Based Capillary Electrophoretic Enantioseparations, Kimber L. Rundlett, Daniel W. Armstrong

Chemistry Faculty Research & Creative Works

Vancomycin (an oligophenolic, glycopeptide, macrocyclic antibiotic) has been shown to be a superb chiral selector for anionic and neutral compounds. It was found that adding sodium dodecyl sulfate to the run buffer increased efficiency by over 1 order of magnitude, decreased analysis times, and reversed the elution order of the enantiomers. This allows for control of the retention order as well as the resolution of enantiomers in complex mixtures in a single run. A mechanism is proposed which explains all of the observed effects and is verified experimentally. Since vancomycin is present in both the micelle and in free solution, …

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Composition Profiles In Electrodeposited Ceramic Superlattices, Jay A. Switzer, Richard J. Phillips, Teresa D. Golden Feb 1995

Composition Profiles In Electrodeposited Ceramic Superlattices, Jay A. Switzer, Richard J. Phillips, Teresa D. Golden

Chemistry Faculty Research & Creative Works

Superlattices in the Pb-Tl-O system with layer thicknesses in the 4-6 nm range were electrodeposited from a single aqueous solution by pulsing the applied potential during deposition. The current-time transients that resulted from the potential steps were monitored to both calculate and tailor the composition profiles of the superlattices during growth. The Cottrell method was used to determine that Tl(l) oxidation was diffusion limited at high potentials. The diffusion limitation resulted in a composition profile that was graded throughout the layer with a t-1/2 dependence. Superlattices grown at lower potentials in which both reactants were under kinetic control had …

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Highly Enantioselective Capillary Electrophoretic Separations With Dilute Solutions Of The Macrocyclic Antibiotic Ristocetin A, Daniel W. Armstrong, Mary P. Gasper, Kimber L. Rundlett Jan 1995

Highly Enantioselective Capillary Electrophoretic Separations With Dilute Solutions Of The Macrocyclic Antibiotic Ristocetin A, Daniel W. Armstrong, Mary P. Gasper, Kimber L. Rundlett

Chemistry Faculty Research & Creative Works

Ristocetin A is one of a series of structurally related amphoteric, glycopeptide, macrocyclic antibiotics. These compounds have several features that make them attractive as chiral selectors. These include spatially oriented functional groups that are known to provide the types of interactions that are conducive to enantio-recognition, a somewhat rigid "pocket" that can provide a site for hydrophobic interactions and polar, flexible arms (i.e., pendent sugar moieties) that can rotate to hydrogen bond and otherwise interact with a variety of chiral analytes. In addition, these compounds are sufficiently soluble in water, aqueous buffers and aqueous-organic solvents that are commonly used in …

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Determination And Use Of Rohrschneider-Mcreynolds Constants For Chiral Stationary Phases Used In Capillary Gas Chromatography, Alain Berthod, Eve Yiwen Zhou, Kang Le, Daniel W. Armstrong Jan 1995

Determination And Use Of Rohrschneider-Mcreynolds Constants For Chiral Stationary Phases Used In Capillary Gas Chromatography, Alain Berthod, Eve Yiwen Zhou, Kang Le, Daniel W. Armstrong

Chemistry Faculty Research & Creative Works

The overall polarity of 22 chiral stationary phases (CSPs) used in capillary open tubular gas chromatography columns was estimated using the first five Rohrschneider-McReynolds constants. Most of the columns (i.e., 18) were wall-coated, and four were of the wall-immobilized or of the so-called "bonded" type. A wall-coated capillary squalane column was specially prepared as a polarity reference column. All but two of the CSPs were based on derivatized cyclodextrins (CDs) of different sizes. The overall properties of the CSPs are discussed in terms of the five Rohrschneider-McReynolds constants and their average values. It was found that the derivatized cyclodextrin CSP …

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Foam Flotation Enrichment Of Enantiomers, Daniel W. Armstrong, Eve Y. Zhou, Shushi Chen, Kang Le, Yubing Tang Dec 1994

Foam Flotation Enrichment Of Enantiomers, Daniel W. Armstrong, Eve Y. Zhou, Shushi Chen, Kang Le, Yubing Tang

Chemistry Faculty Research & Creative Works

Adsorptive bubble separation methods are known to be useful for processing large amounts of material at a relatively low cost These techniques have been used to enrich components from both heterogeneous and homogeneous solutions. There is a need for economical process-scale enantiomeric separations. Thus far there has been little evidence to support the feasibility of using an adsorptive bubble process to enrich enantiomers. We demonstrate that foam-forming chiral collectors can be used in conjunction with an inexpensive glass device to enantiomerically enrich some pharmaceutically important compounds as well as derivatized and underivatized amino acids. Factors that appeared to affect this …

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A Magnetic, Neutron Diffraction, And Mössbauer Spectral Study Of The Nd₂Fe₁₇₋ₓalₓ Solid Solutions, Gary J. Long, Gaya Kanishka Marasinghe, Sanjay R. Mishra, Oran Allan Pringle, Zhongbo Hu, William B. Yelon, D. P. Middleton, K. H. J. Buschow, Fernande Grandjean Nov 1994

A Magnetic, Neutron Diffraction, And Mössbauer Spectral Study Of The Nd₂Fe₁₇₋ₓalₓ Solid Solutions, Gary J. Long, Gaya Kanishka Marasinghe, Sanjay R. Mishra, Oran Allan Pringle, Zhongbo Hu, William B. Yelon, D. P. Middleton, K. H. J. Buschow, Fernande Grandjean

Chemistry Faculty Research & Creative Works

The magnetic properties of a series of Nd2Fe17-xAlx solid solutions, with x equal to 2.04, 4.01, 5.97, 7.94, and 9.06, have been studied by magnetic measurements, neutron diffraction, and Mössbauer spectroscopy. Magnetization studies indicate that the Curie temperature increases from 330 K in Nd2Fe17 to a maximum of ~470 K at an x of 3.5. The compounds crystallize in the Th2Zn17 structure with lattice parameters and unit cell volumes which increase linearly with increasing aluminum content. The neutron diffraction results indicate that aluminum atoms are excluded from the 9d …

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Use Of A Macrocyclic Antibiotic, Rifamycin B, And Indirect Detection For The Resolution Of Racemic Amino Alcohols By Ce, Daniel W. Armstrong, Kumber Rundlett, George L. Reid May 1994

Use Of A Macrocyclic Antibiotic, Rifamycin B, And Indirect Detection For The Resolution Of Racemic Amino Alcohols By Ce, Daniel W. Armstrong, Kumber Rundlett, George L. Reid

Chemistry Faculty Research & Creative Works

Ansamycins are a very specific class of macrocyclic antibiotics of which the rifamycins are among the better-known members. Rifamycins bind to and inhibit DNA polymerase. Rifamycin B (the most easily obtained ansamycin) is negatively charged and is shown to associate with and enantioselectively resolve several chiral amino alcohols including terbutaline, isoproterenol, bamethan, metaproterenoi, synephrine, metanephrine, salbutamol, epinephrine, norphenylephrine, ephedrine, ψ-ephedrine, octopamine, norepinephrine, normetanephrine, metoprolol, alprenolol, atenolol, and oxprenolol. A description of the structure and properties of rifamycins, in general, and rifamycin B, in particular, is given. The complexation and chiral recognition of the aforementioned racemic compounds by rifamycin B is …

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Comparative Mössbauer Effect Study Of Several R₂Fe₁₇ And R₂Fe₁₇Nₓ Compounds, Gary J. Long, Sanjay R. Mishra, Oran Allan Pringle, Fernande Grandjean, K. H. Buschow May 1994

Comparative Mössbauer Effect Study Of Several R₂Fe₁₇ And R₂Fe₁₇Nₓ Compounds, Gary J. Long, Sanjay R. Mishra, Oran Allan Pringle, Fernande Grandjean, K. H. Buschow

Chemistry Faculty Research & Creative Works

The Mössbauer spectra of Sm2Fe17 and Ho 2Fe17 and their nitrides have been measured between 295 and 85 K and analyzed with a model which is consistent with our earlier work on R2Fe17 and R2Fe17Nx compounds, where R is Pr, Nd, and Th. This model is completely consistent throughout these rare-earth compounds and is in agreement with the crystallographic changes occurring upon nitrogenation and with the prediction of band structure calculations. The dramatic increase in Curie temperature in the nitrides results from the expansion of the crystallographic …

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Macrocyclic Antibiotics As A New Class Of Chiral Selectors For Liquid Chromatography, Daniel W. Armstrong, Yublng Tang, Shushi Chen, Yiwen Zhou, Christina Bagwlll, Jing Ran Chen May 1994

Macrocyclic Antibiotics As A New Class Of Chiral Selectors For Liquid Chromatography, Daniel W. Armstrong, Yublng Tang, Shushi Chen, Yiwen Zhou, Christina Bagwlll, Jing Ran Chen

Chemistry Faculty Research & Creative Works

There are a large number of antibiotic macrocycles which include several different structural types. Three representative macrocyclic compounds were covalently linked to silica gel and evaluated by HPLC for their ability to resolve racemic mixtures as well as for their stability and loadability. Over 70 compounds were resolved. In some cases separations were achieved that have not been reported on any other chiral stationary phase (CSP). These stationary phases appear to be multimodal in that they can be used in both the normal-phase and reversed-phase modes. Different compounds are resolved in each mode. There does not appear to be any …

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A Mössbauer Effect Study Of The Microscopic Magnetic Properties Of Th₂Fe₁₇ And Its Nitride, Th₂Fe₁₇N₂.₆, Gary J. Long, Oran Allan Pringle, Fernande Grandjean, T. H. Jacobs, K. H. Buschow Mar 1994

A Mössbauer Effect Study Of The Microscopic Magnetic Properties Of Th₂Fe₁₇ And Its Nitride, Th₂Fe₁₇N₂.₆, Gary J. Long, Oran Allan Pringle, Fernande Grandjean, T. H. Jacobs, K. H. Buschow

Chemistry Faculty Research & Creative Works

The Mössbauer spectra of Th2Fe17 and Th2Fe17N2.6 have been measured at various temperatures between 85 and 295 K and analyzed with a model that is based on the Wigner-Seitz cell environment of each iron site, the orientation of the magnetization, and the magnetic moments as determined from either neutron-diffraction measurements or band-structure calculations. Upon nitrogenation of Th2Fe17, the 85 K weighted average isomer shift increases from 0.037 to 0.156 mm/s and further the isomer shifts of the four crystallographically distinct sites increase in agreement with the increase observed …

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Gender And Aphasia In The Stroke Data Bank, Daniel B. Hier, William B. Yoon, J. P. Mohr, Thomas R. Price, Philip A. Wolf Jan 1994

Gender And Aphasia In The Stroke Data Bank, Daniel B. Hier, William B. Yoon, J. P. Mohr, Thomas R. Price, Philip A. Wolf

Chemistry Faculty Research & Creative Works

Aphasia Was Present in 19.4% of the Men and 22.5% of the Women in the Stroke Data Bank. There Were No Gender Differences in Aphasia Incidence among the Intracerebral Hemorrhages. Aphasia Was More Frequent among Women with Infarcts (37.0%) Than Men (28.3%). When Stroke Mechanism Was Controlled For, There Was an Excess of Aphasia among the Women with Stroke Due to Cardiac Embolism. When Stroke Site Was Controlled For, There Were No Gender Differences in Aphasia Frequency. Wernicke′s, Global, and Anomic Aphasias Were More Common in Women Than Men; Broca′s Aphasia Was Somewhat More Common in Men. Although There Were …

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A Prospective Community-Based Study Of Stroke In Warsaw, Poland, Anna Czlonkowska, Danuta Ryglewicz, Thomas Weissbein, Maria Baranska-Gieruszczak, Daniel B. Hier Jan 1994

A Prospective Community-Based Study Of Stroke In Warsaw, Poland, Anna Czlonkowska, Danuta Ryglewicz, Thomas Weissbein, Maria Baranska-Gieruszczak, Daniel B. Hier

Chemistry Faculty Research & Creative Works

Background and Purpose Poland is a Country with High Morbidity and Mortality Rates from Cardiovascular Diseases. No Recent Studies Have Evaluated the Contribution of Cerebrovascular Diseases to This Morbidity and Mortality. Our Aim Was to Accurately Determine Stroke Incidence Rates in Warsaw, Poland. Methods a 2-Year Prospective and Population-Based Stroke Registry Was Maintained for Health Care Units 2 and 3 in Warsaw, Poland (Population, 182 285). Case Subjects Were Ascertained by Surveying Hospital Admissions, Outpatient Visits, and Death Certificates. Results during the 2 Years of the Study (1991 to 1992), 633 Cases of First-Event Strokes Were Registered, 462 of Which …

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Distribution Of Sedimentary Phosphorus In Gulf Of Mexico Estuaries, Weng Huanxin, Bob J. Presley, Daniel W. Armstrong Jan 1994

Distribution Of Sedimentary Phosphorus In Gulf Of Mexico Estuaries, Weng Huanxin, Bob J. Presley, Daniel W. Armstrong

Chemistry Faculty Research & Creative Works

Sediment samples were collected from all the major bays and estuaries along the US Gulf of Mexico Coastline in 1986-1988 by the NOAA NS & T Program (NOAA (1989), The National Status and Trends Program for marine environmental quality; NOAA/OMA, Rockville, MD, USA). These have been analyzed for total phosphorus as well as leachable Al-P, Ca-P and Fe-P. Total phosphorus concentration ranges from 1·8 to 45·9 μmol/g and averages 11·3 μmol/g. Higher values were found in Louisiana estuaries than in those in Texas but the highest values occur in the phosphate rock mining region of southern Florida. Ca-P is the …

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Separation And Characterization Of Components Of Catalytic Cracker Feed Using Centrifugal Partition Chromatography, Randy A. Menges, Daniel W. Armstrong, Larry A. Spino Oct 1993

Separation And Characterization Of Components Of Catalytic Cracker Feed Using Centrifugal Partition Chromatography, Randy A. Menges, Daniel W. Armstrong, Larry A. Spino

Chemistry Faculty Research & Creative Works

Centrifugal partition chromatography (CPC) was used to fractionate a catalytic-cracking feedstock (i.e., catalytic cracker feed) into 16 separate fractions in the descending mode and 5 fractions in the inverse or ascending mode. Each fraction was analyzed by UV, fluorescence, and synchronous luminescence (SL) spectroscopy as well as by gas chromatography/mass spectrometry (GC/MS). It appeared that CPC can be used to fractionate larger samples of this type and with a greater degree of selectivity than previously reported preparative HPLC approaches. The SL spectra tended to be much more useful and information rich for these complex mixtures as compared to UV or …

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Symmetrically H-Bridged Dimer Of 2-Carboxylatobenzenediazonium. The 1:1 Complex Between 2-Carboxybenzenediazonium Chloride And Benzenediazonium-2-Carboxylate, Christopher J. Horan, Paul E. Haney, Charles Leslie Barnes, Rainer Glaser Aug 1993

Symmetrically H-Bridged Dimer Of 2-Carboxylatobenzenediazonium. The 1:1 Complex Between 2-Carboxybenzenediazonium Chloride And Benzenediazonium-2-Carboxylate, Christopher J. Horan, Paul E. Haney, Charles Leslie Barnes, Rainer Glaser

Chemistry Faculty Research & Creative Works

The two zwitterions in the H-bridged dimer of 2-carboxylatobenzenediazonim (1) are linked by a crystallographically symmetric O⋯Hctdot;O hydrogen bond with an O⋯O distance of 2.436 (3) Å. Comparison of the (1) with the other benzenediazonium salts shows that the phenyl ring distortions in (1) are determined primarily by the diazonium substituent with only modest additional effects by the carboxylato group. Intramolecular neighboring goup interactions between the N2 group and the orthoCOO(H) group are indicated and are discussed. The terminal N atom of the diazonium group is bent away from the neighboring carboxylato group. The N2 and the …

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A Neutron Diffraction And Mössbauer Effect Study Of The Magnetic Properties Of Pr₂Fe₁₇ And Pr₂Fe₁₇N₂.₆, Gary J. Long, Oran Allan Pringle, Fernande Grandjean, William B. Yelon, K. H. Buschow Jul 1993

A Neutron Diffraction And Mössbauer Effect Study Of The Magnetic Properties Of Pr₂Fe₁₇ And Pr₂Fe₁₇N₂.₆, Gary J. Long, Oran Allan Pringle, Fernande Grandjean, William B. Yelon, K. H. Buschow

Chemistry Faculty Research & Creative Works

The neutron diffraction powder patterns of Pr2Fe17 and Pr2Fe17N2.6 have been measured at 295 K and refined within the Th2Zn17 structure type to give the structural changes which occur upon nitrogenation; changes which include a 6.4% expansion of the unit cell volume. The Mössbauer spectra of Pr 2Fe17 and Pr2Fe17N2.6 have been measured between 85 and 295 K and analyzed with a model which is based on the Wigner-Seitz cell environment of each iron site, the basal orientation of the magnetization, and …

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Derivatized Cyclodextrins Immobilized On Fused-Silica Capillaries For Enantiomeric Separations Via Capillary Electrophoresis, Gas Chromatography, Or Supercritical Fluid Chromatography, Daniel W. Armstrong, Yubing Tang, Timothy Ward, Molly Nichols Apr 1993

Derivatized Cyclodextrins Immobilized On Fused-Silica Capillaries For Enantiomeric Separations Via Capillary Electrophoresis, Gas Chromatography, Or Supercritical Fluid Chromatography, Daniel W. Armstrong, Yubing Tang, Timothy Ward, Molly Nichols

Chemistry Faculty Research & Creative Works

No abstract provided.

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2-Carboxybenzenediazonium Chloride Monohydrate, Christopher J. Horan, Charles Leslie Barnes, Rainer Glaser Mar 1993

2-Carboxybenzenediazonium Chloride Monohydrate, Christopher J. Horan, Charles Leslie Barnes, Rainer Glaser

Chemistry Faculty Research & Creative Works

C7H5N2O2 +.Cl-H2O, Mr = 202.60, monoclinic, C2c, a = 25.62(3), b = 4.964(2), c = 14.900 (14)Å, β = 107.15 (4)°, V = 1811 (3)Å3, Z = 8, Dx = 1.486 g cm-3, λ(Mo Kα) = 0.71073 Å, µ = 3.9 cm-1, F(000) = 832, T = 298 K, R = 0.035 for 1275 observed reflections. The terminal N atom of the diazonium group is bent away from the carboxyl group. The N2 and the …

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Infarct Topography And Hemiparesis Profiles With Cerebral Convexity Infarction: The Stroke Data Bank, J. P. Mohr, M. A. Foulkes, A. T. Polis, D. (Daniel) B. Hier, C. S. Kase, T. R. Price, T. K. Tatemichi, P. A. Wolf Jan 1993

Infarct Topography And Hemiparesis Profiles With Cerebral Convexity Infarction: The Stroke Data Bank, J. P. Mohr, M. A. Foulkes, A. T. Polis, D. (Daniel) B. Hier, C. S. Kase, T. R. Price, T. K. Tatemichi, P. A. Wolf

Chemistry Faculty Research & Creative Works

For the 183 of 1276 Patients in the NINDS Stroke Data Bank with Convexity Infarction in the Middle Cerebral Artery Territory, the Size of the Infarct Did Not Differ between the Two Sides But the Location of the Main Site of the Infarct Differed: on the Left Side, It Was Centered in the Inferior Parietal Region, and Was Mid-Frontal on the Right. There Was a Good Correlation between Infarct Size and Weakness Severity Whether Estimated by overall Motor Function on One Side, Arm, or Hand Alone. There Was a Poor Correlation, However, for Lesion Location (Lower Third, Middle Third or …

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Aminolysis Of Activated Esters Of Indole-3-Acetic Acid In Acetonitrile, Michael J. Pfeiffer, Samir B. Hanna Jan 1993

Aminolysis Of Activated Esters Of Indole-3-Acetic Acid In Acetonitrile, Michael J. Pfeiffer, Samir B. Hanna

Chemistry Faculty Research & Creative Works

Seven activated esters of indole-3-acetic acid (IAA) [4-oxo-l,2,3-benzotriazin-3-yl indole-3-acetate (IAA-3HBO), succinimido indole-3-acetate (IAA-NHS), 5-norbornene-1,3-dicarboximido indole-3-acetate (IAA-NHND), phthalimido indole-3-acetate (IAA-NHP), naphthalimido indole-3-acetate (IAA-NHN), 4-nitrophenyl indole-3-acetate (IAA-4NP), 8-quinolyl indole-3-acetate (IAA-8HQ)] were prepared and characterized. Their kinetics of aminolysis with butylamine, piperidine, and pyrrolidine in acetonitrile were investigated. In general, the observed pseudo-first-order rate constants, kobs, fit the two-term rate equation kobs = k1[amine] + k2[amine]2. For the aminolysis of six of the esters with piperidine there was no measurable k2 term. The 8-hydroxyquinoline ester and N-hydroxy-naphthalimide ester of indole-3-acetic acid had no measurable k2 term for aminolysis with either pyrrolidine or piperidine. …

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Enantiomeric Separation Of Chiral Components Reported To Be In Coffee, Tea, Or Cocoa, Apryll M. Stalcup, K. Helen Ekborg, Mary P. Gasper, Daniel W. Armstrong Jan 1993

Enantiomeric Separation Of Chiral Components Reported To Be In Coffee, Tea, Or Cocoa, Apryll M. Stalcup, K. Helen Ekborg, Mary P. Gasper, Daniel W. Armstrong

Chemistry Faculty Research & Creative Works

Literally hundreds of volatile compounds have been identified in coffee, tea, and cocoa. A significant proportion of these compounds are known to be chiral. The enantiomeric composition of most of these compounds is unknown, and until recently there were no efficient analytical procedures for their identification. The advent of cyclodextrin-based chiral stationary phases for capillary gas chromatography provides effective means for the enantioselectivity analysis of many of these compounds. Some of these are known to be flavor and fragrance components that occur naturally or are produced from the manufacturing process (e.g., fermentation, drying, and roasting). © 1993, American Chemical Society. …

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Tetrabutylammonium Benzoate‐Initiated Polymerization Of Propylene Oxide, Xuemin Chen, Michael R. Van De Mark Jan 1993

Tetrabutylammonium Benzoate‐Initiated Polymerization Of Propylene Oxide, Xuemin Chen, Michael R. Van De Mark

Chemistry Faculty Research & Creative Works

The polymerization of propylene oxide by the benzoate anion was aided through the use of the tetrabutylammonium counterion. The effect of the tetrabutylammonium ion was to increase the solubility of the salt and to increase the ion separation. The polymerization was carried out in a pressure reactor at temperatures from 40 to 108°C, producing polymer yields of 2–78%. The study addressed the general effects of solvent, temperature, and ratio of initiator to monomer. © 1993 John Wiley & Sons, Inc. Copyright © 1993 John Wiley & Sons, Inc.

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A Mössbauer Effect Study Of The Microscopic Magnetic Properties Of Nd₂Fe₁₇ And Nd₂Fe₁₇N₂.₆, Gary J. Long, Oran Allan Pringle, Fernande Grandjean, K. H. J. Buschow Nov 1992

A Mössbauer Effect Study Of The Microscopic Magnetic Properties Of Nd₂Fe₁₇ And Nd₂Fe₁₇N₂.₆, Gary J. Long, Oran Allan Pringle, Fernande Grandjean, K. H. J. Buschow

Chemistry Faculty Research & Creative Works

The Mössbauer spectra of Nd2Fe17 and Nd 2Fe17N2.6 have been measured at various temperatures between 78 and 295 K and analyzed with a model that is based on the Wigner-Seitz cell environment of each iron site, the orientation of the magnetization, and the magnetic moments as determined from either neutron-diffraction measurements or band-structure calculations. Upon nitrogenation of Nd2Fe17, the weighted average isomer shift increases from 0.060 to 0.164 mm/s and further the isomer shifts of the four crystallographically distinct sites increase in agreement with the increase observed in their …

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Thalamic Stroke: Presentation And Prognosis Of Infarcts And Hemorrhages, Wolfgang Steinke, Ralph L. Sacco, J. P. Mohr, Mary A. Foulkes, Thomas K. Tatemichi, Philip A. Wolf, Thomas R. Price, Daniel B. Hier Jan 1992

Thalamic Stroke: Presentation And Prognosis Of Infarcts And Hemorrhages, Wolfgang Steinke, Ralph L. Sacco, J. P. Mohr, Mary A. Foulkes, Thomas K. Tatemichi, Philip A. Wolf, Thomas R. Price, Daniel B. Hier

Chemistry Faculty Research & Creative Works

Thalamic Strokes in 62 Patients Selected from the Stroke Data Bank Were Studied to Determine Differences among 18 Infarctions (INF), 23 Localized Hemorrhages (ICH), and 21 Hematomas with Ventricular Extension (IVH). Stupor or Coma at Onset Occurred More Frequently in the IVH (62%) Than in the INF (6%) or ICH (13%) Groups and Was Reflected in Significantly Lower Median Glasgow Coma Scores in the IVH Group (7) Than in the INF (15) and ICH (14) Groups. Although Ocular Movements Were More Frequently Abnormal in the IVH Group Compared with the ICH and INF Groups, No Significant Differences Were Found in …

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Early Clinical Differentiation Of Cerebral Infarction From Severe Atherosclerotic Stenosis And Cardioembolism, S. G. Timsit, R. L. Sacco, J. P. Mohr, M. A. Foulkes, T. K. Tatemichi, P. A. Wolf, T. R. Price, D. (Daniel) B. Hier Jan 1992

Early Clinical Differentiation Of Cerebral Infarction From Severe Atherosclerotic Stenosis And Cardioembolism, S. G. Timsit, R. L. Sacco, J. P. Mohr, M. A. Foulkes, T. K. Tatemichi, P. A. Wolf, T. R. Price, D. (Daniel) B. Hier

Chemistry Faculty Research & Creative Works

Background and Purpose: Hyperacute Cerebral Infarction Trials Require Early Differentiation of Infarction Subtype. Our Aim Was to Determine Clinical Factors Predictive of Infarction Subtype from Data Collected in the Early Hours of Admission. Methods: using the 1,273 Patients Enrolled in the Stroke Data Bank, Stroke Risk Factors and Demographic, Clinical, and Radiological Features Were Compared between the 246 Cardioembolic and 113 Large-Vessel Atherosclerotic Cerebral Infarcts. Results: Stroke Data Bank Definitions Ensured More Transient Ischemic Attacks in Atherosclerotic Infarcts and More Cardiac Disease in Cardioembolic Infarcts, But the Diagnosis Was Distinguished Further using a Logistic Regression Model. Fractional Arm Weakness (Shoulder …

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1-Ferrocenyl-1-Cyclopropyl Cation: The First Long-Lived Cyclopropyl Cation, G. K.Surya Prakash, Herwig Buchholz, V. Prakash Reddy, Armin De Meijere, George A. Olah Jan 1992

1-Ferrocenyl-1-Cyclopropyl Cation: The First Long-Lived Cyclopropyl Cation, G. K.Surya Prakash, Herwig Buchholz, V. Prakash Reddy, Armin De Meijere, George A. Olah

Chemistry Faculty Research & Creative Works

No abstract provided.

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Empirical Procedure That Uses Molecular Structure To Predict Enantioselectivity Of Chiral Stationary Phases, Alain Berthod, San Chun Chang, Daniel W. Armstrong Jan 1992

Empirical Procedure That Uses Molecular Structure To Predict Enantioselectivity Of Chiral Stationary Phases, Alain Berthod, San Chun Chang, Daniel W. Armstrong

Chemistry Faculty Research & Creative Works

A total of 121 racemic compounds were separated In the normal-phase mode on a (S)-(1-naphthylethyl)carbamoylated β-cyclodextrin (S-NEC-β-CD) bonded phase and 74 on the R equivalent (-NEC) chiral stationary phase (CSP). All compounds are of the type that have four substituents on a stereogenlc center, rather than an "axis of chirality". It is shown that the binary solvent pair used as the mobile phase has a significant Influence on chiral recognition. However, the proportions of the components of a specific pair have little effect. From the results, the Individual contributions to chiral recognition by these CSPs were estimated for 81 different …

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Multiple Enantioselective Retention Mechanisms On Derivatized Cyclodextrin Gas Chromatographic Chiral Stationary Phases, Alain Berthed, Weiyong Li, Daniel W. Armstrong Jan 1992

Multiple Enantioselective Retention Mechanisms On Derivatized Cyclodextrin Gas Chromatographic Chiral Stationary Phases, Alain Berthed, Weiyong Li, Daniel W. Armstrong

Chemistry Faculty Research & Creative Works

2, 6-Di-O-pentyl-3-O-(trifluoroacetyl) (DP-TFA) derivatized β and γ-cyclodextrlne are able to resolve a wide variety of volatile racemic compounds. The enantiomeric recognition mechanism of these phases was Investigated. The retention behavior of homologous series showed that lengthening the side alkyl chain Increases the retention time but does not affect enantioselectivlty. The thermodynamic parameters, free energy, enthalpy, and the difference In free energy, enthalpy, and entropy between enantiomers were evaluated for 24 enantiomeric pairs. From this data, It appears that the compounds can be arranged In two groups. One group has high values for enthalpy, entropy, free energy, and the corresponding difference …

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Fundamental Aspect And Behavior Of Saturated Fluorocarbons In Glow Discharge In Absence Of Potential Source Of Hydrogen, Yu Iriyama, H. Yasuda Jan 1992

Fundamental Aspect And Behavior Of Saturated Fluorocarbons In Glow Discharge In Absence Of Potential Source Of Hydrogen, Yu Iriyama, H. Yasuda

Chemistry Faculty Research & Creative Works

The glow discharge of a series of saturated fluorocarbons, CnF2n+2 (n = 1, 2, 4, 6, and 8), was studied with glass substrates which do not contain any hydrogen. It was found that the deposition rate was a function of the F/C ratio of the starting fluorocarbons. That is, fluorocarbons with higher F/C ratio, such as CF4 and C2F6, hardly polymerized, while fluorocarbons with lower F/C ratio, such as C8F18, polymerized as well as C2F4. After plasma exposure, the surface of glass substrate was …

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Paint Stripper Composition Having Reduced Volatility Containing Decanolactone, N-Methylpyrrolidone And Butyrolactone And Method Of Use, Harvest L. Collier, Gary L. Bertrand, Raymond L. Venable Dec 1991

Paint Stripper Composition Having Reduced Volatility Containing Decanolactone, N-Methylpyrrolidone And Butyrolactone And Method Of Use, Harvest L. Collier, Gary L. Bertrand, Raymond L. Venable

Chemistry Faculty Research & Creative Works

An improved composition of matter and method of use for removing cured coatings of paint or varnish or other similar coatings from substrates. The composition comrpises chlorinated solvent paint strippers (especially methylene chloride (CH2CI2)), waxes and an additive selected from the group consisting of decanolactone (C10H18O2), N-methylpyrrolidone (CH3NCH2CH2CH2CH2) and butyrolactone (OCH2CH2CH2CO). The additive retards the evaporation of the solvent resulting in a composition that is environmentally less hazardous to a user and also resulting …

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