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Articles 481 - 510 of 517

Full-Text Articles in Chemistry

Surface Area Of Coal As Influenced By Low Temperature Oxidation Processes, Salvador Leon Arredondo Jan 1980

Surface Area Of Coal As Influenced By Low Temperature Oxidation Processes, Salvador Leon Arredondo

Dissertations and Theses

The possibility of increasing the amount of readily accessible surface area by enlarging the 5 A pore was examined via pretreating the PSOC-371 coal with gases such as nitrogen, nitrogen-oxygen, and ozone-oxygen and hydrogen peroxide solutions. Surface areas were obtained from nitrogen adsorption at 77 K and carbon dioxide adsorption at either 298 or 195 K for each sample before and after treatment.


A Study Of The Photolysis Of O-Methyl Podocarpinitrile Oxide, Dianne Marie Hunter Jan 1980

A Study Of The Photolysis Of O-Methyl Podocarpinitrile Oxide, Dianne Marie Hunter

Dissertations and Theses

The photolytic reaction of 0-methyl podocarpinitrile oxide to yield the δ-lactam (shown below) was studied under various conditions such as: solvent (hexane, methanol), mercury lamp wattage (lOOW, 450W), filter (Pyrex, Corex, Vycor), and additives (dichloromethane, hexafluorobenzene). The reactions were analyzed with IR, NMR and HPLC. Preparative medium pressure liquid chromatography and TLC were used in the δ-lactam isolation. The conditions resulting in the optimum yield of δ-lactam were determined. The photolytic stability of the δ-lactam under the conditions in which it was formed indicated that it was relatively stable only in hexane.


Transport Of Ozone Across An Air/Water Interface Coupled With Aqueous Decomposition, Ahmad Ali Mehrabzadeh Jan 1980

Transport Of Ozone Across An Air/Water Interface Coupled With Aqueous Decomposition, Ahmad Ali Mehrabzadeh

Dissertations and Theses

Photoacoustic spectroscopy was used to analyze the transport of ozone through the air/water interface. Experimental results showed that the ozone transport rate is similar to rates measured for other gases of low solubility and low reactivity. The transport rate increases with increasing pH. The decomposition rate of ozone was studied in solutions. The decomposition rate also depends on the pH of the solution, and in high pHs both the deposition velocity and the decomposition rate constant of ozone have larger values. The value of the deposition velocity (Kd) is 3.7 ± .9 x 10-3 cm/sec and the decomposition rate …


The Concentration And Speciation Of Sugars In Natural Waters, Minoo Shakerin Sweet May 1979

The Concentration And Speciation Of Sugars In Natural Waters, Minoo Shakerin Sweet

Dissertations and Theses

Due to the importance of carbohydrates in biological systems, many efforts have been made to develop a quantitative method for analysis of carbohydrates in natural waters. The low concentrations of dissolved sugars in natural waters require a sensitive analytical method. In this study, gas chromatography of alditol acetate derivatives of sugars was investigated for quantitative and qualitative analysis of individual dissolved sugars in natural waters. The alditol acetate derivatives of sugars give only one derivative for each sugar, yielding qualitative and quantitative results.

The detection limit was 25 nM for each sugar. Because of this very low detection limit, only …


A Polarographic Study Of Fe(Ii) And Fe(Iii) Complexes With Catechol, Wen-Tang Shen Jan 1979

A Polarographic Study Of Fe(Ii) And Fe(Iii) Complexes With Catechol, Wen-Tang Shen

Dissertations and Theses

A study of the anodic polarography of catechol in 0.100 F sodium perchlorate is presented. A new wave is observed in alkaline solutions which is different from the simple oxidation wave of catechol to ortho-quinone observed by previous workers. The importance of buffer materials is discussed and a possible explanation of the new wave is suggested.

A study of the polarography behavior of Fe(II) and Fe(III) in the presence of catechol is reported. In the case of reduction of Fe(III) in the presence of catechol, two steps occur at about -1.5 and -1.8 volts (vs. SCE) at pH higher than …


The Systhesis And Photolysis Of 1-Phenylcyclohexaneacetic Acid Azide, Jack P. Mourad Jan 1979

The Systhesis And Photolysis Of 1-Phenylcyclohexaneacetic Acid Azide, Jack P. Mourad

Dissertations and Theses

The aim of this research project was to study the possible synthesis of the morphine analog 3-oxo-5-phenylmorphan via the photochemical cyclization of the acyl azide of 1-phenylcyclohexaneacetic acid.


An Investigation Of Arsenic(V)-Catechol Complexes, Ronald P. Haak Jun 1978

An Investigation Of Arsenic(V)-Catechol Complexes, Ronald P. Haak

Dissertations and Theses

There is not, at this time, a simple method for the simultaneous determination of As (III) and As (V) at trace levels. The development of such as method is needed, as the toxicities of these two species differ so greatly.

As (III) and As (V) are polarographically reducible in the presence of excess catechol, but the wave produced by As (V) is depended on time, pH and catechol concentration as well as As (V) concentration. In order to understand this behavior, determination of formation constants for any complex species present were needed to identify which species is electroactive. The literature …


Purification And Characterization Of Nadh Oxidase And Peroxidase From Lactobacillus Casei, Louise Ann Barstad Jan 1978

Purification And Characterization Of Nadh Oxidase And Peroxidase From Lactobacillus Casei, Louise Ann Barstad

Dissertations and Theses

A protein exhibiting NADH oxidase and NADH peroxidase activity has been isolated from Lactobacillus casei in high purity. Evidence obtained through gel filtration, electrophoresis, and electrofocusing indicates that the two activities are characteristic of a single tetrameric protein with an approximate molecular weight of 240,000.


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.


Involvement Of Hemerythrin Sulfhydryl Groups In Heavy Atom Binding And Subunit Interactions, Suzanne Elizabeth Clarke Dec 1977

Involvement Of Hemerythrin Sulfhydryl Groups In Heavy Atom Binding And Subunit Interactions, Suzanne Elizabeth Clarke

Dissertations and Theses

Hemerythrin is a respiratory protein found in the erythrocytes of certain marine invertebrates. Structures have been obtained by x-ray crystallography for hemerythrins from Phascolopsis gouldii (P. gouldii) and Themiste dyscritum (T. dyscritum). Since many proteins are inactivated upon binding heavy metals such as mercury, an investigation of mercury-protein interactions in this protein was undertaken. In order to understand the nature of heavy-metal protein interactions in T. dyscritum it was necessary to identify the metalloprotein ligands since neither the liganding amino acid residues nor the geometry of the mercury complexes could be identified in the crystallographic studies.


The Chemistry Of Sf₅Br And Sf₅Cf=Cf₂ - Addition Reactions, Robin J. Debuhr Nov 1977

The Chemistry Of Sf₅Br And Sf₅Cf=Cf₂ - Addition Reactions, Robin J. Debuhr

Dissertations and Theses

Addition reactions of pentafluorosulfur bromide (SF5Br) with fluoroolefins were studied. Three new adducts were prepared, SF5CHFCHC1Br, SF5CH2CH(CF3)Br, SF5CHFCFC1Br. SF5Br and CFC1=CHC1 yielded a small amount of product but attempts to add SF5Br to CF2=FCOF were unsuccessful.

The mechanism for these addition reactions seems to involve a free radical addition pathway. Steric factors seem to be important in determining whether SF5Br will add to fluoroolefins.

The new compounds, SF5CF(CF3)COF and SF5CF(CF3 )CONH2 have …


Determination Of Mercury By Photoacoustic Spectroscopy, Robert Allen Cary Jul 1977

Determination Of Mercury By Photoacoustic Spectroscopy, Robert Allen Cary

Dissertations and Theses

A new detector for atomic spectroscopy was developed based on the photoacoustic principle. A simple system was constructed based on this detector and applied to the trace analysis of mercury. The detection limit was found to be about 0.2 μg/1 of mercury with a one milliliter sample.


Characterization Of Trace Iron Species In Natural Water, James Robert Johnson Jul 1977

Characterization Of Trace Iron Species In Natural Water, James Robert Johnson

Dissertations and Theses

The distribution and speciation of trace metals in natural waters is only slightly, at best, understood. Interactions with organic substances can effectively distribute the metals throughout many ill-defined physical and chemical. To better comprehend the complexity of metal-organic interactions this work focused on the delineation of trace iron species present in a natural system. The separation of Fe(II) and Fe(III) was successfully accomplished using a variation of an ion exchange method involving resin-loaded filter paper. The quantitation of the various iron species was determined using linear scan voltammetry and atomic absorption. The total iron concentration, determined as the sum of …


The Addition Of Sf5br To Unsaturated Systems, Qui-Chee Wendy Wang Jun 1976

The Addition Of Sf5br To Unsaturated Systems, Qui-Chee Wendy Wang

Dissertations and Theses

Addition reactions of pentafluorosulfur bromide with unsaturated substrates were studied and four new compounds containing the pentafluorosulfur group have been prepared.

The mechanism for these reactions seems to involve a radical addition pathway. In reaction with CH2=CFC1, CF3C≡CH and CH3C≡CH the SF5 radical attacks the carbon atoms carrying the most hydrogens. The reaction with CF2=CHCl is interesting, as by analogy with other fluoroolefins, the SF5 primary attack should occur.at the CHCl group, however, SF5CF2CHC1Br was found as the only product for this reaction. The reaction of …


The Chemistry Of Chromium (Vi) And Chromium (V) Oxide Fluorides, Patrick Jay Green Apr 1976

The Chemistry Of Chromium (Vi) And Chromium (V) Oxide Fluorides, Patrick Jay Green

Dissertations and Theses

New preparative routes to chromyl fluoride were sought. It was found that chlorine monofluoride reacts with chromium trioxide and chromyl chloride to produce chromyl fluoride. Attempts were made to define a mechanism for the reaction of ClF and Cr03 in light of by-products observed and previous investigations. Carbonyl fluoride and chromium trioxide react to form chromyl fluoride and carbon dioxide. A mechanism was also proposed for this reaction. Chromium trioxide with MoF6 or WF6 reacts to produce chromyl fluoride and the respective oxide tetrafluoride.


Polymerization Of Amino Acids On Kaolinite, Z. Badri Adnani-Gleason Jan 1976

Polymerization Of Amino Acids On Kaolinite, Z. Badri Adnani-Gleason

Dissertations and Theses

In the origin of life on the primitive earth a major step must have involved the condensation of amino acids to form the first polypeptides. Several suggestions as to how this might have occurred have been made by other workers. One of the more appealing proposals is that the polymerization was catalyzed by clay minerals. It has been reported, for example, that L-apartic acid polymerizes significantly faster than D-aspartic in the presence of kaolinite in aqueous suspension at 90˚. In this work an attempt was made to repeat this report and extend the pH range to include values presumably present …


Isolation And Characterization Of Two Sterols From The Green Alga, Selenastrum Capricornutum, Raymond Mark Owings Aug 1975

Isolation And Characterization Of Two Sterols From The Green Alga, Selenastrum Capricornutum, Raymond Mark Owings

Dissertations and Theses

The green alga, Selenastrum capricornutum, was cultured in artificial nutrient medium utilizing five-gallon carboys, each of which contained 16 1. of culture. The algal cells were separated from the nutrient medium by continuous-flow centrifugation at 7500 RPM, and were then lyophilized. The lyophilized cells were extracted by refluxing with ether, acetone, and chloroform:methanol (2:1). Free sterols and sterol esters were separated from the crude extract using preparative thin-layer chromatography. Sterol esters were saponified and both the sterols and the fatty acids were recovered.

Individual sterols were separated from the free sterol fraction using argentation thin-layer chromatography. Gas chromatograms, mass …


Studies In Transition Metal Chemistry, Steven David Brown May 1975

Studies In Transition Metal Chemistry, Steven David Brown

Dissertations and Theses

The electronic and vibrational spectra of liquid chromium pentafluoride have been investigated. They were found to be consistent with a d1 system that is extensively fluorine-bridged at room temperature. The vibrational spectra were not consistent with C4v or D3h monomers.


The Development Of An Arsenic(V) Selective Electrode, Sandra Gee Kang Nov 1974

The Development Of An Arsenic(V) Selective Electrode, Sandra Gee Kang

Dissertations and Theses

The object of this research was to develop an arsenic(V) selective electrode. The electrode is based on a solid state membrane prepared by pressing a precipitate of silver arsenate-silver sulfide into a pellet. After the electrode was made, experiments were designed to check for three general characteristics of the electrodes: dependence of potential on pH for constant arsenic(V) concentration; dependence of potential on arsenic(V) concentrations at constant pH and extent of interference due to phosphate and arsenic(III) ions. From these measurements, it was found that Ag2HAs04 was formed originally in the membranes containing a small fraction of …


Characterization Of Zinc-Containing Metalloproteins By Resonance Raman Spectroscopy, Robert Edward Derry Sep 1974

Characterization Of Zinc-Containing Metalloproteins By Resonance Raman Spectroscopy, Robert Edward Derry

Dissertations and Theses

Cobalt-substituted carboxypeptidase and carbonic anhydrase were chosen as candidates for resonance Raman spectroscopy because they possess visible absorption due to the Co(II)-protein complex. However, no evidence for resonance-enhanced peaks due to the cobalt-containing chromophore was found with laser excitation near the visible absorption bands (514.5 nm) or closer to the ultraviolet absorption bands (457.9nm).

Arsanilazocarboxypeptidase and model azotyrosine compounds were selected for a Raman spectroscopic investigation because they have intense absorption bands in the visible region. All of these substances yielded similar resonance Raman spectra. Although there was no evidence for specific zinc-ligand vibrations, shifts in vibrational frequencies of the …


Alumina-Catalyzed Cope Rearrangement, Paul Jhy-Shing Wang Aug 1974

Alumina-Catalyzed Cope Rearrangement, Paul Jhy-Shing Wang

Dissertations and Theses

The alumina-catalyzed Cope rearrangements of meso- and dl-3,4-diphenylhexa-1,5-diene were examined in detail, following up a preliminary observation by H. Berg at Portland State University. Commercial column-chromatography grade alumina was employed, and was further activated before use by heating at 650-700° for four hours.

Using a ratio of 20 mg of dl-3,4-diphenylhex-l,5-diene to 1 g of alumina in heptane, the Cope rearrangement was complete within 15 minutes at room temperature to give exclusively trans,trans-1,6-diphenylhexa-1,5-diene. This was identified.by melting point, infrared spectroscopy and vapor phase chromatography.

The catalyzed rearrangement of meso-3,4-diphenylhexa-l,5-diene was run using the same diene …


A Phytochemical Investigation Of Liverwort Frullania Franciscana Howe, Timothy Ta-E Huang Jan 1974

A Phytochemical Investigation Of Liverwort Frullania Franciscana Howe, Timothy Ta-E Huang

Dissertations and Theses

Liverwort Frullania franciscana Howe was found high on the allergic test scale by J. Mitchell of the Medical School of the University of British Columbia and co-workers. Frullanolide was isolated from Frullania tamarisci by J.D. Connoly and by G. Oisson and his co-workers.

The plant sample, collected in Oregon, was hand separated, confirmed, air dried and milled before the extractions were done. A Soxhlet extraction with ether and cold extractions with n-hexane and with ether were carried out. Ether is a better extraction solvent than n-hexane for cold extraction.

Column chromatography was used for the separation of the extract based …


A Study Of The Adsorption Of Some Atmospheric Gases On Soils Of The Willamette Valley River Basin, Thomas R. Quale Dec 1973

A Study Of The Adsorption Of Some Atmospheric Gases On Soils Of The Willamette Valley River Basin, Thomas R. Quale

Dissertations and Theses

Recent work indicates that microorganisms present in soils can remove carbon monoxide from the atmosphere and as such constitutes a major sink. B.E.T. adsorption studies were carried out on representative soils from the Willamette Valley River Basin in order to determine their adsorptive characteristics for carbon monoxide and other gases. Attempts were made to isolate, through a non-soildestructive sterilization, the adsorptive characteristics of the soil microorganisms as well as of the test soil.

The carbon monoxide studies show physical adsorption equivalent to the coverage of a few per cent of the surface area at 25.0° and 76 cm-Hg. Adsorption studies …


Synthesis Of Uranium Fluorosulfates And The Group Vi B Difluorophosphates, Larry Mccain Emme Jan 1973

Synthesis Of Uranium Fluorosulfates And The Group Vi B Difluorophosphates, Larry Mccain Emme

Dissertations and Theses

Some reactions leading to several anhydrous Uranium fluorosulfates through the use of fluorosulfonic acid or peroxydisulfuryl di-fluoride have been studied. It was found that HS0F can oxidize uranium 3metal to the +4 state or the +2 state depending on the reaction conditions. The synthesis of the tan solid; U(S03F)4 and the pale green solid thought to be U(S03F)2 were prepared in this manner. It was found that S206F2 can also oxidize uranium to yield the green solid U(S03F)3. S206F2 was …


Kinetics Of The Cope Rearrangement Of 3,4-Diphenylhexa-1,5-Diene, Harlan Albert Jerome Berg Sep 1972

Kinetics Of The Cope Rearrangement Of 3,4-Diphenylhexa-1,5-Diene, Harlan Albert Jerome Berg

Dissertations and Theses

Kinetics investigations of the thermal Cope rearrangement of meso- and dl-3,4-diphenylhexa-1,5-dienes were undertaken in order to gain information about the transition states for these reactions by determining the appropriate enthalpies and entropies of activation. Of particular interest were the activation parameters for the meso compounds' rearrangement as it represents the only known example in which both four- and six-centered transition states are of comparable energy.

Kinetics of the dl isomers' rearrangement in the temperature range 90-110° were determined using 5 X 10-5 M solutions of the olefin in heptane contained within sealed Pyrex ampules. Extents of reaction …


Catechol Effected Dissolution Of Silicate Minerals, James Maurice Kelley Jan 1972

Catechol Effected Dissolution Of Silicate Minerals, James Maurice Kelley

Dissertations and Theses

The chemical properties of guanidinium tris(catecholato)siliconate, [(H₂N)₂C=NH₂]₂[Si(C₆H₄O₂)₃]·XH₂O (0 < X < 1), precipitated from an ammoniacal solution of silica and catechol by adding guanidinium hydrochloride, (H₂N)₂C=NH·HC1, were studied, and infrared, nmr, x-ray powder diffraction, and analytical data were gathered.

This same compound was, upon addition of' (H₂N)₂C=NH·HC1, isolated from 0.25, M aqueous catechol solutions buffered at pH 10 and containing the silicate minerals albite, andradite, muscovite, pyrophyllite, talc, and wollastonite, and also from unbuffered catechol solutions containing wollastonite and andradite.

It is concluded from this work that the formation of an anionic catechol-silicon complex, Si(C₆H₄O₂)₃²⁻, is largely responsible for the dissolution of the minerals mentioned above. From this conclusion, it is proposed that naturally occurring members of the class of organic compounds to which catechol belongs, the aromatic v̲i̲̲c̲-diols, may play …


On The Mechanism Of The Diels-Alder Reaction--Dimerization Of Trans-Phenylbutadiene, Michael Ward Mcnicholas Jan 1972

On The Mechanism Of The Diels-Alder Reaction--Dimerization Of Trans-Phenylbutadiene, Michael Ward Mcnicholas

Dissertations and Theses

The Diels-Alder dimerization of trans-1-substituted butadienes is expected to yield a cyclohexene adduct with the substituents in the 3 and 4 positions cis to one another. This prediction is based on past observations of other Diels-Alder additions. The cis-isomer is the only one consistent with a two-stage mechanism proposed by Woodward and Katz.

In the case of trans-phenylbutadiene, the expected adduct is cis-3-phenyl 1-4-(trans-styry1) cyclohexene. Alder, Haydn and Vogt, however, reported that the corresponding trans-isomer is the dimerization product. There is reason to believe that the observation of the trans-isomer may have been the result of product isomerization during purification. …


Reaction Of Aqueous Catechol Solutions With Minerals, Boonthong Poocharoen Jan 1972

Reaction Of Aqueous Catechol Solutions With Minerals, Boonthong Poocharoen

Dissertations and Theses

The effectiveness of catechol, an aromatic vic-diol, in dissolving silicate minerals was studied. A synthetic amorphous magnesium trisilicate, Mg₂Si₃O₈∙5H₂O, as well as the minerals olivine, sepiolite, diopside, augite, and enstatite were used to react with catechol in slightly acidic, basic, and neutral solutions. It was found, depending on the solvent used, that 33-52, 8-17, 14-30, 5-11, 3-6, and 0.5-1 % of the minerals dissolved, respectively.

The reaction with Mg₂Si₃0₈·5H₂0 resulted in the formation of crystals of magnesium tris (catecholato) siliconate nonahydrate Mg[Si(Cat)₃]∙9H₂0. Dehydration of the crystals at room temperature resulted in the loss of 6 moles of water to form …


Evidence For The Existence Of Two Stable Sites For Cobalt Impurity Atoms In Aluminum, Arun Venkatachar Aug 1971

Evidence For The Existence Of Two Stable Sites For Cobalt Impurity Atoms In Aluminum, Arun Venkatachar

Dissertations and Theses

Using Fe57Mössbauer spectroscopy, two alternative sites occupied by cobalt (10-4 at. % ) impurity atoms in aluminum have been isolated. The substitutional site A is the stable position after annealing the sample above 840 K, followed by a rapid quench. The impurity atoms in site A are characterized by a single line Mössbauer spectrum (indicative of a cubic environment), a room-temperature f = 0.502 (r. m. s. displ. 0.071 A) and an I. S. (reI. to Fe) = -0.421 mm/sec. For anneals below 770 K the cobalt atoms migrate to site B, which is characterized by a …


Investigation Of The Alpha-Sub-Gamma Phase In Alnico 6, Cortez Samuel Sep 1970

Investigation Of The Alpha-Sub-Gamma Phase In Alnico 6, Cortez Samuel

Dissertations and Theses

The purpose of this research project was to study the αᵧ phase in Alnico 6. Other phases were studies for comparison. Also the effect of an applied magnetic field on the formation of the αᵧ phase was investigated.

Three single crystals of Alnico 6 were heat treated for one hour--one at 1250°C, one at 1000°C, and one at 800°C--and water-quenched. The microstructure of each sample was observed with the optical microscope, and X-ray diffraction patterns were taken to determine the crystal structure of the phases present.

Several single crystal samples of Alnico 6 were heat treated at 1000°C and furnace-cooled. …