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Articles 32461 - 32490 of 34540

Full-Text Articles in Physical Sciences and Mathematics

Chemistry Of Low-Valent Molybdenum Phosphite Complexes: Models Of Seven-Coordinate Reaction Intermediates, E. L. Muetterties, J. F. Kirner, W. J. Evans, S. Abdel-Meguid, I. Tavanaiepour, V. W. Day Jan 1978

Chemistry Of Low-Valent Molybdenum Phosphite Complexes: Models Of Seven-Coordinate Reaction Intermediates, E. L. Muetterties, J. F. Kirner, W. J. Evans, S. Abdel-Meguid, I. Tavanaiepour, V. W. Day

Chemistry Department: Faculty Publications

A simple synthesis of the zerovalent complex Mo[P(OCH3)3]6 has been devised from a potassium reduction of MoCI4(tetrahydrofuran)2 followed by reaction with trimethyl phosphite at 70°. Protonation of this octahedral complex gave only low yields of the expected seven-coordinate hydride, HMo[P(OCH3)3]6+. The major product was an octahedral nonhydridic cation, Mo[P(OCH3)3]5P(OCH3)2+, derived from proton cleavage of the P─O phosphite ester bond. This octahedral cation was stereochemically nonrigid, apparently through facile methoxy group migration. Close packing by methoxy groups …


Regulation Of Protein Synthesis In Rabbit Reticulocyte Lysates By The Heme-Regulated Protein Kinase: Inhibition Of Interaction Of Met-TrnaFMet Binding Factor With Another Initiation Factor In Formation Of Met-TrnaFMet.4os Ribosomal Subunit Complexes, R. S. Ranu, I. M. London, A. Das, A. Dasgupta, A. Majumdar, R. Ralston, R. Roy, N. K. Gupta Jan 1978

Regulation Of Protein Synthesis In Rabbit Reticulocyte Lysates By The Heme-Regulated Protein Kinase: Inhibition Of Interaction Of Met-TrnaFMet Binding Factor With Another Initiation Factor In Formation Of Met-TrnaFMet.4os Ribosomal Subunit Complexes, R. S. Ranu, I. M. London, A. Das, A. Dasgupta, A. Majumdar, R. Ralston, R. Roy, N. K. Gupta

Chemistry Department: Faculty Publications

Protein synthesis in reticulocytes and their lysates is regulated by heme. In heme deficiency a heme-regulated translational inhibitor (HRI) that blocks initiation of polypeptide chains is activated. HRI is a protein kinase (ATP: protein phosphotransferase, EC 2.7.1.37) that specifically phosphorylates the 38,000-dalton subunit of the Met-tRNAfMet indin factor (IF), which forms a ternary complex with Met- tRNAfMet and GTP, a finding that suggests that the inhibition by HRI involves the phosphorylation of IF. We have investigated the effect of HRI in the partial reactions of protein chain initiation in which the IF-promoted binding of Met-tRNAf …


In Situ Intercalation Of Tas2 In The Electron Microscope, G. Tatlock, Juana Acrivos Jan 1978

In Situ Intercalation Of Tas2 In The Electron Microscope, G. Tatlock, Juana Acrivos

Faculty Publications, Chemistry

Electron diffraction had been used to study the formation of a variety of complex superlattices in the 1T, 2H and 4Hb polytypes of TaS2 during intercalation with hydrazine gas (N2H4), in situ in the electron microscope. Results are presented over the temperature range 15K-360K and are interpreted in terms of scattering from periodic lattice distortions linked to charge density waves. Comparisons are also made with similar effects in both the as-grown crystals and the TaS2 samples containing other adducts.


Protein Synthesis In Rabbit Reticulocytes: Characteristics Of A Ribosomal Factor That Reverses Inhibition Of Protein Synthesis In Heme-Deficient Lysates, R. O. Ralston, A. Das, A. Dasgupta, R. Roy, S. Palmieri, N. K. Gupta Jan 1978

Protein Synthesis In Rabbit Reticulocytes: Characteristics Of A Ribosomal Factor That Reverses Inhibition Of Protein Synthesis In Heme-Deficient Lysates, R. O. Ralston, A. Das, A. Dasgupta, R. Roy, S. Palmieri, N. K. Gupta

Chemistry Department: Faculty Publications

A ribosomal salt (0.5 M KCI) wash factor (RF) that reverses inhibition of protein synthesis in heme-deficient reticulocyte lysates has been resolved from the bulk of Met-tRNAtmet- binding factor (EIF-1), Co-EIF-I, and EIF-2 (ternary complex dissociation factor, TDF). The purified RF restores protein synthesis activity of heme-deficient lysates to the level observed in the presence of hemin. No direct correlation exists between amount of EIF-i activity and ability to reverse inhibition of protein synthesis in heme-deficient lysates. Homogeneous preparations of EIF-i are completely inactive in reversal of protein synthesis inhibition in heme-deficient lysates. These findings suggest that …


Developmental Dyslexia: Evidence For A Subgroup With A Reversal Of Cerebral Asymmetry, Daniel B. Hier, Marjorie Lemay, Peter B. Rosenberger, Vincent P. Perlo Jan 1978

Developmental Dyslexia: Evidence For A Subgroup With A Reversal Of Cerebral Asymmetry, Daniel B. Hier, Marjorie Lemay, Peter B. Rosenberger, Vincent P. Perlo

Chemistry Faculty Research & Creative Works

The Computerized Brain Tomograms of 24 Patients with Developmental Dyslexia Were Analyzed for Cerebral Asymmetry. Ten Patients Showed a Reversal of the Pattern of Asymmetry Regularly Observed in Normal Right-Handed Individuals So that the Right Parietooccipital Region Was Wider Than the Left. the Ten Dyslexic Patients with This Reversal of Cerebral Asymmetry Had a Lower Mean Verbal IQ Than the Other 14 Dyslexic Patients in This Study. the Reversal of Cerebral Asymmetry that Occurred in Ten of the Dyslexic Patients May Result in Language Lateralization to a Cerebral Hemisphere that is Structurally Less Suited to Support Language Function and Thus …


Mechanism Of The Ninhydrin Reaction, Carey B. Bottom, Samir B. Hanna, Donald J. Siehr Jan 1978

Mechanism Of The Ninhydrin Reaction, Carey B. Bottom, Samir B. Hanna, Donald J. Siehr

Chemistry Faculty Research & Creative Works

No abstract provided.


Emulsification And The Hlb-Temperature, Stig Friberg, Concepcion Solans Jan 1978

Emulsification And The Hlb-Temperature, Stig Friberg, Concepcion Solans

Chemistry Faculty Research & Creative Works

No abstract provided.


Molybdenum(V) Solutions In Hydrobromic Acid, Edwin Charles Perley Jan 1978

Molybdenum(V) Solutions In Hydrobromic Acid, Edwin Charles Perley

Electronic Theses and Dissertations

Interest in the coordination chemistry of molybdenum has increased greatly in recent years because of the discovery that molybdenum plays an active role in several redox enzymes. Model systems have been devised to gain insight into the function of molybdenum in these enzymes. Most model systems are believed to contain an oxomolybdate(V) dimer in equilibrium with a redox active monomer or dimer. A relatively simple system that shows important similarities to model systems is a molybdenum(V) solution in hydrobromic or hydrochloric acid. As in the model systems, these solutions are believed to contain monomers and dimers in equilibrium. The equilibria …


Synthesis And Flame Retardant Studies Of Bromoester Of 2,4-Pentadienoic Acid, Hessam Ghane Jan 1978

Synthesis And Flame Retardant Studies Of Bromoester Of 2,4-Pentadienoic Acid, Hessam Ghane

Retrospective Theses and Dissertations

The synthesis and fire retardancy of several bromoesters of 2,4-pentadienoic acid were investigated. The synthesis of 2,4-pentadienoic acid was accomplished by liquid phase reaction of acrolein and malonic acid in the presence of pyridine. The conversion of the acid to bromoesters was performed by two different procedures. In the first procedure, the corresponding acid chloride was prepared from the acid via reaction with SOCl2 in the presence of powdered (3A°) molecular sieves. The molecular sieves serve as an internal trap for by-product HC1 and inhibit the competing polymerization reaction of the acid chloride. Reaction of the acid chloride with various …


Collisionless Formation And Rovibronic Relaxation Of Ch And Oh From The Ir Multiphoton Photolysisof Ch3Oh, Stephen E. Bialkowski, William A. Guillory Jan 1978

Collisionless Formation And Rovibronic Relaxation Of Ch And Oh From The Ir Multiphoton Photolysisof Ch3Oh, Stephen E. Bialkowski, William A. Guillory

Stephen E. Bialkowski

A CO2 TEA laser has been used to initiate the collisionless multiphotondissociation of CH3OH between 1000 and 10 mtorr. The appearance of OH(X2Πi) 50±20 nsec after the laser pulse, independent of initial CH3OH pressure (50–200 mtorr), suggests the primary dissociative channel CH3OH+n hν→CH3 +OH(X2Πi); although CH3 could not be correspondingly confirmed. The appearance of CH(X2Πr) 70±20 nsec after the OH(X) appearance, independent of initial CH3OH pressure (70–400 mtorr), suggests secondary collisionless dissociation. Initial rovibronic distributions of OH(X) …


Specificity Of Antisera Against Hordeum Vulgare Ribonuclease And Serological Quantitation Of The Enzyme In Tissue Extracts, Steven Bryan Hawthorne Jan 1978

Specificity Of Antisera Against Hordeum Vulgare Ribonuclease And Serological Quantitation Of The Enzyme In Tissue Extracts, Steven Bryan Hawthorne

Electronic Theses and Dissertations

Specific rabbit antisera against purified seedling RNase I from both a hardy (Dicktoo) and less-hardy (Tennessee Winter) cultivar of winter barley was obtained using a 1 mg injection schedule. Both antisera formed a single precipitin band on double immunodiffusion and immunoelectrophoresis when reacted with the homologous crude tissue extract. RNase antigen from either cultivar was highly cross-reactive with both antisera. Passive hemagglutination inhibition was used in an attempt to distinguish purified RNase from both cultivars. A consistent difference in anti-RNase serum specificity between cultivars was shown, but the difference observed by this method was not sufficient to conclude structural differences …


Nucleophilic Substitution At Phosphorus In Six-Membered Ring Phosphate Esters, Mike Bauman Jan 1978

Nucleophilic Substitution At Phosphorus In Six-Membered Ring Phosphate Esters, Mike Bauman

Electronic Theses and Dissertations

From these results the following conclusions may be drawn: 1. The stereochemistry of nucleophilic substitution at phosphorus is influenced by the basicity of the leaving group with the more basic leaving group favoring retention. 2. Lithium ion diverts the reaction to retention by forming an intimate ion-pair with the nucleophile which then attacks phosphorus. This associated ion is less reactive than the unassociated nucleophile. 3. For the retention mechanism the leaving group participates in the rate determining step. 4. The mechanism for retention entails a more sterically unfavorable configuration than for inversion.


Studies On The Gas Given Off By Yeast When It Goes From An Anaerobic To Aerobic Metabolism, David C. Potts Jan 1978

Studies On The Gas Given Off By Yeast When It Goes From An Anaerobic To Aerobic Metabolism, David C. Potts

Electronic Theses and Dissertations

Several investigators have observed that when yeast cells (yeast) go from a strictly anaerobic environment to an aerobic oner and glucose is added a negative value is recorded on the manometer. This phenomenon indicates that a gas has been given off by the yeast. The purpose of this research was to identify the gas and determine how it arises.


The Vapor Phase Oxidation Of 1, 3-Pentadiene, David E. Sasser Jan 1978

The Vapor Phase Oxidation Of 1, 3-Pentadiene, David E. Sasser

Retrospective Theses and Dissertations

The vapor phase oxidation of 1.3-pentadiene, over heterogeneous catalysts, was investigated with the objective of producing 2,4-pentadienal and 2,4-pentadienoic acid. Copper and cobalt-molybdenum catalysts, both supported and unsupported, were utilized at various reaction temperatures, residence times and feed ratios. The matter of 1,3-pentadiene vaporization and introduction into the reactor system proved to be critical. Low temperature vaporization of the hydrocarbon and dilution with the oxidant, air, was found to be necessary to avoid polymerization of the feed. Alumina-supported catalysts were found to be very active, leading to severe cracking of the hydrocarbon feed and subsequent carbonization of the catalysts. Silica-supported …


Concentration Of Radionuclides In Dardanelle Lake, Arkansas, David M. Chittenden Ii, Larry Mcfadden Jan 1978

Concentration Of Radionuclides In Dardanelle Lake, Arkansas, David M. Chittenden Ii, Larry Mcfadden

Journal of the Arkansas Academy of Science

Concentrations of the nuclides ⁹⁰Sr - ⁹⁰Y, ¹⁴⁴Ce - ¹⁴⁴Pr, ¹³⁷Cs, ³⁸Co, ¹¹⁰ͫAg, ¹⁴¹Ce and ⁸⁹Sr have been measured monthly since November, 1975. The results from the period September, 1976, to August, 1977, depend on the relative intensities of the sources of the radionuclides; emissions from Nuclear I, the Chinese nuclear tests of Fall, 1976, and fallout from older atmospheric tests.


The Effect Of Slow Two‐Electron Transfers And Disproportionation On Cyclic Voltammograms, Michael D. Ryan Jan 1978

The Effect Of Slow Two‐Electron Transfers And Disproportionation On Cyclic Voltammograms, Michael D. Ryan

Chemistry Faculty Research and Publications

The EE mechanism (two‐electron transfer) for cyclic voltammetry was investigated in considerable detail along with the effect of disproportionation. The theory was developed for either the first or second electron transfer being slow while the other one was reversible. It was possible to develop generalized working curves for the height and shape of the wave regardless of the difference in Eo's and the values of α and Ks. This theory was then applied to the analysis of the reduction of benzil in the presence of alkaline earth ions in dimethylformamide.


A Solid State 13C-Nmr Study Of Diamonds And Graphites, Charles A. Wilkie, Thomas C. Ehlert, Daniel T. Haworth Jan 1978

A Solid State 13C-Nmr Study Of Diamonds And Graphites, Charles A. Wilkie, Thomas C. Ehlert, Daniel T. Haworth

Chemistry Faculty Research and Publications

The 13C-NMR spectra of gem quality and industrial diamonds show two resonances with the more intense resonance at high field. Two resonances are also shown in 13C-NMR spectra of various graphites; however, the low field resonance is of greater intensity than the high field resonance in the graphites. The resonances are very broad and they are assigned to graphite type (sp2) carbon and diamond type (sp3) carbon.


The 13C-Nmr Solid State Spectroscopy Of Various Classes Of Coals, Charles A. Wilkie, Daniel T. Haworth Jan 1978

The 13C-Nmr Solid State Spectroscopy Of Various Classes Of Coals, Charles A. Wilkie, Daniel T. Haworth

Chemistry Faculty Research and Publications

The 13C-NMR spectra of various classes of coal obtained in the solid state show two resonances, one of which is assigned to aromatic carbon and the other to aliphatic carbon. The resonances are very broad with the high field resonance centered at about 7 ppm below tetramethylsilane and a low field resonance centered at about 140 ppm below tetramethysilane. Based on our previous solid state 13C-NMR studies of graphite and diamond, the high field resonance is typical of a sp3 carbon whereas the low fields resonance is assigned to a sp2 carbon whereas the low fields …


Direct Determination Of Pentachlorophenol By Differential Pulse Polarography, Albert L. Wade Jan 1978

Direct Determination Of Pentachlorophenol By Differential Pulse Polarography, Albert L. Wade

Theses and Dissertations

Concern over environmental contamination leading to the introduction of pentachlorophenol into human and animal systems has resulted in the need for a rapid and direct method for determining trace concentrations of this highly toxic compound. A direct electrochemical procedure has been developed for determining trace conccentrations of this phenol dovm to 0.27 ppm. This method uses the electrochemical techniques of differential pulse polarography at the dropping mercury electrode, and differential pulse voltammetry at the carbon paste electrode to reduce pentachlorophenol for this determination. Cyclic voltammetry at the hanging mercury drop electrode has been used to characterize the reaction behavior of …


The Joy Of Chemistry- Personal Impressions (Text And Audio), Frank D. Starkey Jan 1978

The Joy Of Chemistry- Personal Impressions (Text And Audio), Frank D. Starkey

Honorees for Teaching Excellence

No abstract provided.


Mechanism Of Phenyl Azide-1,2-Cyclonoadiene Adduct Formation And Isomerization Of This Adduct, Isom Harrison Jan 1978

Mechanism Of Phenyl Azide-1,2-Cyclonoadiene Adduct Formation And Isomerization Of This Adduct, Isom Harrison

University of the Pacific Theses and Dissertations

A major purpose of this research was to investigate the mechanism of aryl azide addition to allenes. Much evidence has accumulated in support of a concerted mechanism for aryl azide additions to simple alkenes. Consistent with these findings, this addition is a symmetry allowed process. The analagous aryl azide additions to allenes have received little mechanistic study. The approach taken in this work was to probe the mechanism by using optically active 1,2-cyclonanadiene, observing the stereochemistry of the adduct formed upon addition of phenyl azide.

Another goal was to investigate the isomerization of the phenyl azide-1,2-cylononadiene adduct, 10-phenyl-10,11,12-triaza-△ 11 -bicyclo …


The Solid State 13C-Nmr Spectra Of Some Carbides, Daniel T. Haworth, Charles A. Wilkie Jan 1978

The Solid State 13C-Nmr Spectra Of Some Carbides, Daniel T. Haworth, Charles A. Wilkie

Chemistry Faculty Research and Publications

The utility of NMR spectroscopy to the study of liquids or solids dissolved in liquids is well known. This technique has been used infrequently to studies in the solid state[I,2]. Work has been done on diamond, graphite and coa113-6]. The 13C-NMR of ebony and ivory have been studied by the magic angle technique[7]. The solid state 13C-NMR spectra of graphite and diamond can be interpreted in terms of tetrahedral (sp3) and trigonal planar (sp2) carbon atoms[8]. We now report our investigations using solid state 13C-NMR spectroscopy to study various types of carbides.


Synthesis And Resolution Of Enantiomeric Quaternary Ammonium Halides, Wei Lee Jan 1978

Synthesis And Resolution Of Enantiomeric Quaternary Ammonium Halides, Wei Lee

University of the Pacific Theses and Dissertations

The purpose of the work described in this thesis was the synthesis of a new class of surfactants containing chiral cationic end groups and the synthesis of two chiral reactant molecules which would react in the presence of these surfactants. The structures of the surfactant and substrate molecules were designed to maximize their stereochemical interactions and in this way reveal details of the nature of micellar catalysis. In order to indicate why these structures were selected, several examples of micellar catalysis and the factors influencing it will be discussed in the following pages.


Reduction Of 1,2 Cyclopentanedione With Lithium Aluminum Hydride, David Curtis Winn Jan 1978

Reduction Of 1,2 Cyclopentanedione With Lithium Aluminum Hydride, David Curtis Winn

Dissertations, Theses, and Masters Projects

No abstract provided.


Amperometric Determination Of Chemical Oxygen Demand, Catherine Eckert Hutchins Jan 1978

Amperometric Determination Of Chemical Oxygen Demand, Catherine Eckert Hutchins

Masters Theses

A method is described for measuring the low level --5 to 50 ppm-- chemical oxygen demand (COD) of water samples by amperometric titration. The method involves digestion of the sample with potassium dichromate in a 50% sulfuric acid solution using one-fifth the reagents and sample required for the standard COD method. This is followed by an amperometric titration using a standard ferrous ammonium sulfate solution and employing a rotating platinum electrode in a three-electrode potentiostatic system. The titration is carried out at a potential of +0.80 volts versus a saturated calomel electrode, thus eliminating the need for O2 purging …


Ergosterol Effect On The Desaturation Of 14c-Cis-Vaccenate In Tetrahymena, Tiee-Chyau Miin Jan 1978

Ergosterol Effect On The Desaturation Of 14c-Cis-Vaccenate In Tetrahymena, Tiee-Chyau Miin

Masters Theses

Supplement of ergosterol to the growth medium of the ciliated protozoan Tetrahymena pyriformis W leads to incorporation of the foreign sterol within cell membranes and suppression of synthesis of the native sterol-like compound tetrahymanol, as well as to changes in the fatty acid compositions of several major classes of membrane lipid. Alteration of fatty acid composition is thought to represent a regulatory mechanism whereby optimum membrane fluidity is maintained when the slightly dissimilar foreign sterol is added into the phospholipid bilayer of the membranes.

The present study, using several different conditions of growth temperature, substrate concentrations and incubation time, and …


Thermodynamics Of Ion Association In Aqueous Solutions Of Sodium Sulfate, Sodium Carbonate And Sodium Bicarbonate, Yan-Chun Chung Jan 1978

Thermodynamics Of Ion Association In Aqueous Solutions Of Sodium Sulfate, Sodium Carbonate And Sodium Bicarbonate, Yan-Chun Chung

Masters Theses

Stoichiometric association constants of NaSO4-, NaCO3- and NaHCO3- ion-pairs were determined over the temperature range 10 - 40°C at several ionic strengths by using a sodium ion selective electrode. At zero ionic strength values for K°A,NaSO4- are 15.8 ± .4, 8.5 ± .2 and 4.6 ± .3 at 10°, 25° and 40°C, respectively; like values for K°A,NaCO3- are 17.1 ± 1.4, 19.1 ± .6 and 21.0 ± .7. Values for K°A,NaHCO3° are 3.35 ± .07 and 6.75 ± .02 at 25°C …


Ditertiary Phosphines As Monodentate Ligands In Transition Metal Carbonyl Complexes, Yih-Yau York Sun Jan 1978

Ditertiary Phosphines As Monodentate Ligands In Transition Metal Carbonyl Complexes, Yih-Yau York Sun

Masters Theses

Carbonyl complexes of chromium, molybdenum and tungsten have been synthesized in which two potentially chelating tetraphenyldiphosphinoethane molecules (Ph2PCH2CH2PPh2) are bound as monodentate ligands. The reaction of trans-(CO)4M(PPh2CH=CH2)2 (M = Cr, Mo, W) with diphenylphosphine (PPh2H) in the presence of potassium t-butoxide yields trans-(CO)4M(PPh2CH2CH2PPh2)2. The complexes, which represent the first of this type to be synthesized, have been characterized by 31P nmr. From the XAA'X' phosphorus-31 spectra of the …


The Synthesis And Characterization Of Several Copper (Ii) Complexes Of Quinuclidinone-Containing Ligands. Possible Models For Type I Copper Blue Proteins., Victor Thomas Wilcox Jan 1978

The Synthesis And Characterization Of Several Copper (Ii) Complexes Of Quinuclidinone-Containing Ligands. Possible Models For Type I Copper Blue Proteins., Victor Thomas Wilcox

Masters Theses

Several copper (II) complexes with bidentate quinuclidinone containing ligands have been synthesized and characterized. These complexes appear to be possible models for the type I copper (II) in the copper "blue" proteins. The spectral and magnetic properties indicate that the complexes have a pseudo tetrahedral microsymrnetry about the central metal ion. The complexes contain chromophores of the following forms: CuN4, CuN2O2, and CuN2x2, where X is either Cl or Br. While the spectra of these complexes lack the intense 17,000 cm-1 band typical of copper "blue" proteins, the optical …


New Evidence Supporting The Assignment Of Glutamic Acid As An Iron Ligand In Hemerythrin, Patricia M. Gormley Jan 1978

New Evidence Supporting The Assignment Of Glutamic Acid As An Iron Ligand In Hemerythrin, Patricia M. Gormley

Dissertations and Theses

The amino acid sequence determination of Phascolopsis gouldii hemerythrin in the region of the proposed iron ligand at position 58 was the main objective of this research endeavor. Generation of a large peptide was pursued by trypsin digestion of citraconylated hemerythrin producing peptide 50-113 for sequenator analysis. Detection of the phenylthiohydantoin amino acid derivatives by gas-liquid and high-performance-liquid chromatography yielded unambiguous sequence elucidation through the region of interest identifying residue 58 as glutamic acid.