Chemistry Commons^™

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 …

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 …

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 …

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, C_nF_2n+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 …

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 …

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 …

Resolution Of Enantiomeric Hydrocarbon Biomarkers Of Geochemical Importance, Daniel W. Armstrong, Yubing Tang, Janusz Zukowski

Chemistry Faculty Research & Creative Works

Chlral isoprenoid and hydroaromatic compounds occur in all crude oils, coals, shales, and most sediments. Many of these compounds are referred to as biological markers since they are thought to be derived from biological sources and their presence, relative concentrations, or stereochemistry can provide information as to a geological deposit's age, maturity, diagenetic history, and so forth. Because of the previous lack of effective and efficient analytical methodologies for resolving hydrocarbon enantiomers, the stereochemical information encoded in these molecules is largely untouched. A series of derivatized α-, β-, and γ-cyclodextrin chiral stationary phases (CSPs) were used for the gas chromatographic …

Change Of Magnetic Properties Of Th₂Fe₁₇ Due To Interstitial Solution Of C And N, T. H. Jacobs, Gary J. Long, Oran Allan Pringle, Fernande Grandjean, K. H. Buschow

Chemistry Faculty Research & Creative Works

The changes in magnetic and crystallographic properties in the series Th₂Fe₁₇C_x and Th₂Fe ₁₇N_x have been studied. The changes in the latter series were also studied by ⁵⁷Fe Mössbauer spectroscopy. The ultimate enhancements of the saturation moments in these series are 13% and 24%, respectively. This is much larger than observed previously in the corresponding rare-earth compounds, although the Curie temperature enhancements are of comparable magnitude. In the Th-Fe-C system a novel compound of the BaCd ₁₁ type was found, having a Curie temperature around 370 K.

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 …

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. …

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. …

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.

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.

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 …

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 …

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 …

Evaluation Of D-Amino Acid Levels In Human Urine And In Commercial L-Amino Acid Samples, Daniel W. Armstrong, J. D. Duncan, S. C. Lee

Chemistry Faculty Research & Creative Works

Detectable levels of four free D-amino acids (phenylalanine, tyrosine, tryptophan and leucine) were found in human urine. This was accomplished using a liquid chromatographic coupled column (i.e., achiral-chiral) method that was developed for the rapid and sensitive analysis of these compounds. The technique was tested on a series of commercial L-amino acids. Care was taken to minimize racemization. Trace to percent levels of contaminating D-enantiomers were found in all commercial samples. In urine the D-amino acids ranged from several hundredths of a percent up to percent levels of the corresponding excreted natural L-amino acids. There were no apparent correlations between …

Clinical-Computed Tomographic Correlations Of Lacunar Infarction In The Stroke Data Bank, A. Chamorro, R. L. Sacco, J. P. Mohr, M. A. Foulkes, C. S. Kase, T. K. Tatemichi, P. A. Wolf, T. R. Price, D. (Daniel) B. Hier

Chemistry Faculty Research & Creative Works

Lacunar Stroke Was Diagnosed in 337 (26%) of the 1,273 Patients with Cerebral Infarction among the 1,805 Total in the Stroke Data Bank. We Analyzed the 316 Patients with Classic Lacunar Syndromes. among These, 181 (57%) Had Pure Motor Hemiparesis, 63 (20%) Sensorimotor Syndrome, 33 (10%) Ataxic Hemiparesis, 21 (7%) Pure Sensory Syndrome, and 18 (6%) Dysarthria-Clumsy Hand Syndrome. No Striking Differences Were Found among the Risk Factors for the Lacunar Subtypes, But Differences Were Found between Lacunar Stroke as a Group and Other Types of Infarcts. Compared to 113 Patients with Large-Vessel Atherosclerotic Infarction, Those with Lacunar Stroke Had …

Status Of Aluminum As A Risk Factor For Dialysis Encephalopathy And Alzheimer's Disease, P. B. Gorelick, D. (Daniel) B. Hier, C. Mangone, S. Robbins, A. Plioplys, S. Kathpalia

Chemistry Faculty Research & Creative Works

No abstract provided.

Stroke Recurrence Within 2 Years After Ischemic Infarction, D. (Daniel) B. Hier, M. A. Foulkes, M. Swiontoniowski, R. L. Sacco, P. B. Gorelick, J. P. Mohr, T. R. Price, P. A. Wolf

Chemistry Faculty Research & Creative Works

We Prospectively Studied Stroke Recurrence in 1,273 Patients with Ischemic Stroke Who Were Entered into the Stroke Data Bank. Median Follow-Up Was 13 Months. the 2-Year Cumulative Recurrence Rate among These Patients Was 14.1%. Age, Sex, Race, History of Hypertension, Atrial Fibrillation, or Transient Ischemic Attacks, and Stroke Location Were Not Associated with a Higher Risk of Stroke Recurrence. Patients with an Elevated Blood Pressure, an Abnormal Initial Computed Tomogram, or a History of Diabetes Mellitus Were at a Higher Risk of Stroke Recurrence. in Contrast, Patients with an Infarct of Unknown Cause Were at a Lower Risk of Stroke …

Deriving Clinical Prediction Rules From Stroke Outcome Research, Daniel B. Hier, Gilda Edelstein

Chemistry Faculty Research & Creative Works

Background and Purpose. Our Purpose Was to Determine Whether Clinical Prediction Rules Could Be Derived from Current Stroke Outcome Research. Summary of Report. We Reviewed 92 Articles on Stroke Outcome Research to Determine their Suitability for Implementation as a Clinical Prediction Rule. Methodological Problems in Many of These Studies Made Implementation of their Results as a Clinical Prediction Rule Difficult. Conclusions. Implementation of Stroke Outcome Research as Clinical Prediction Rules Would Be Facilitated by Description of Patient Population Demographics; Precise Definitions of Predictor and Outcome Measures; Stratification of Patients by Stroke Mechanism; Use of Adequate Patient Sample Sizes; and Description …

New Bio-Analytical Separations Utilizing Chiral Mobile Phase Additives In Thin Layer Chromatography And Chiral Stationary Phases In High Performance Liquid Chromatography, Jo Dee Duncan

Doctoral Dissertations

"The problem addressed by this dissertation is the separation of optical isomers in commercial as well as biological samples. The chromatographic separation of enantiomers is an important and rapidly developing field of study. Chiral separations of pharmaceutical compounds and important organic intermediates in high performance liquid chromatography (HPLC) and thin layer chromatography (TLC) were achieved. Two methods were employed for the direct liquid chromatographic resolution of chiral analytes: chiral stationary phases (CSPs) and chiral mobile phase additives (CMAs). Native and derivatized ß-cyclodextrins (ß-CD) were used as chiral stationary phases in reverse phase and normal phase HPLC, respectively. This study marked …

Mössbauer-Effect, Magnetic, And Neutron-Diffraction Study Of Nafep₂O₇, R. C. Mercader, L. Terminiello, Gary J. Long, D. G. Reichel, K. Dickhaus, R. Zysler, R. Sanchez, M. Tovar

Chemistry Faculty Research & Creative Works

Neutron-diffraction, magnetic-susceptibility, specific-heat, and Mössbauer-effect studies of NaFeP₂O₇ reveal that it is a normal Heisenberg isotropic three-dimensional antiferromagnetic material with a Néel temperature of 29.0 K. NaFeP₂O₇ has the monoclinic P2₁/c magnetic space group, which is the same as the nuclear crystallographic space group. The easy axis of magnetization lies in the monoclinic ac plane at an angle of 21.0° from the c axis. The specific-heat measurements reveal a λ-type anomaly at 28.7(2) K. A molecular-field model analysis indicates that the intrasublattice magnetic exchange coupling J_aa=J_bb=-0.37 cm-1, whereas …

Polar-Liquid, Derivatized Cyclodextrin Stationary Phases For The Capillary Gas Chromatography Separation Of Enantiomers, Daniel W. Armstrong, Weiyong Li, Chau Dung Chang, Josef Pitha

Chemistry Faculty Research & Creative Works

A new class of hydrophilic, relatively polar liquid, cyclodextrin (CD) derivatives have been used as highly selective chiral stationary phases (CSPs) for capillary gas chromatography (GC). Several possible requirements for liquidity In CD derivatives are discussed. O-(S)-2-Hydroxypropyl derivatives of α-, β-, and γ-cyclodextrlns were synthesized, exclusively characterized, permethylated, and evaluated for enantloselectlvity. Seventy pairs of enantiomers were resolved. They represent a wide variety of structural types and classes of compounds including chlral alkyl amines, amino alcohols, epoxides, pyrans, furans, sugars, dlols, esters, ketones, bicyclic compounds, alcohols, and so on. Many of these compounds were not aromatic and cannot be resolved …

Reversing Enantioselectivity In Capillary Gas Chromatography With Polar And Nonpolar Cyclodextrin Derivative Phases, Daniel W. Armstrong, Weiyong Li, Josef Pitha

Chemistry Faculty Research & Creative Works

No abstract provided.

A Study Of The Hydration Properties Of Selected Laser Dye Aerosols Including Continuous-Flow Parallel Plate And Alternating-Gradient Thermal Diffusion Cloud Chamber Measurements In The High Supersaturation Regime, Donald E. Hagen, Max B. Trueblood, Darryl J. Alofs

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The Hydration Behavior of Aerosols made Up of Various Fluorescent Dyes when Exposed to Water Saturation or Supersaturated Conditions Has Been Studied. Critical Supersaturation Spectra Are Reported. the Dyes Are Found to Behave as High Molecular Weight Ionic Compounds that Obey Kohler Theory. their Relevant Kohler Parameters Are Measured. This Study Makes Use of and Compares Results from the Isothermal Hazecontinuous-Flowand Alternating-Gradient Thermal Diffusion Cloud Chambers. the Ability of the Continuous-Flow Thermal Diffusion Chamber to Operate Correctly at High Supersaturations is Shown. © 1990 Elsevier Science Publishing Co., Inc.

Relevance Of Enantiomeric Separations In Food And Beverage Analyses, Daniel W. Armstrong, Chau Dung Chang, Wei Yong Li

Chemistry Faculty Research & Creative Works

A series of new derivatized cyclodextrins have been developed for use as chiral stationary phases in capillary gas chromatography. As a result, a large number of the enantiomeric components in food and beverage products can be resolved relatively quickly and easily. The study focuses on compounds other than amino acids (e.g., malic acid, lactic acid, tartaric acid, esters, alcohols, lactone flavors or fragrances, and so on). The ability to separate and quantitate enantiomers at low levels should be useful for detecting adulterated products, for evaluating fermentation processes, and for the accurate characterization of enantiomeric flavor components, growth regulators, pesticides, and …

Caudate Infarcts, Louis R. Caplan, Edward Feldmann, Jeremy D. Schmahmann, Carlos S. Kase, Phillip B. Gorelick, Daniel B. Hier, Cathy Helgason, George Baquis, John P. Greenberg

Chemistry Faculty Research & Creative Works

Eighteen Patients Had Caudate Nucleus Infarcts (10 Left-Sided; 8 Right-Sided). Infarcts Extended into the Anterior Limb of the Internal Capsule in 9 Patients, and Also the Anterior Putamen in 5 Patients. Thirteen Patients Had Motor Signs, Most Often a Slight Transient Hemiparesis. Dysarthria Was Common (11 Patients). Cognitive and Behavioral Abnormalities Were Frequent, and Included Abulia (10 Patients), Agitation and Hyperactivity (7 Patients), Contralateral Neglect (3 Patients, All Right Caudate), and Language Abnormalities (2 Patients, Both Left Caudate). the Majority of Patients Had Risk Factors for Penetrating Artery Disease. Branch Occlusion of Heubner's Artery, or Perforators from the Proximal Anterior …

Self‐Diffusion Coefficients Of Boc‐Amino Acid Anhydrides Under Conditions Of Solid Phase Peptide Synthesis, Stephen Pickup, Frank D. Blum, Warren T. Ford

Chemistry Faculty Research & Creative Works

No abstract provided.

Molecular Mobility In A Model Polymer Composite, Joan Ethel Gambogi

Masters Theses

"The adsorption of aminoalkysilane coupling agents onto silica surfaces and the interaction of these functional silanes with a bismaleimide and an epoxy resin has been studied using solid-state NMR techniques. ¹³C CP-MAS was used to confirm the bonding between the silence and bismaleimide (BMI) resin and elucidate the nature of the crosslinking reaction of BMI. Deuterated coupling agents were synthesized and adsorbed on silica surfaces. The motional dynamics were probed using deuterium solid-echo NMR. It was determined that the motion of the alky portion of the coupling agents was consistent with gauche migrations (gtt ↔ tig) and pair gauche …