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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
51

Determination of toxic 12, 13-epoxy-[symbol]-trichothecenes by gas-liquid chromatography

Ikediobi, Christopher Okwuolisa, January 1970 (has links)
Thesis (M.S.)--University of Wisconsin--Madison, 1970. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.
52

Fundamental study of centrifugal precipitation chromatography and its application in fractionation of protein, RNA and plasmid DNA /

Tomanee, Panarat, January 2005 (has links)
Thesis (Ph. D.)--Lehigh University, 2005. / Includes vita. Includes bibliographical references (leaves 188-193).
53

A study of the synthesis and development of separations processes and specifically ultrafiltration induced polaization chromatography

Lee, Ho-lun. January 1977 (has links)
Thesis--Wisconsin. / Vita. Includes bibliographical references (leaves 205-213).
54

Cytochromes of Azotobacter vinelandii

Neumann, Norbert Paul, January 1958 (has links)
Thesis (Ph. D.)--University of Wisconsin--Madison, 1958. / Typescript. Abstracted in Dissertation abstracts, v. 19 (1959) no. 7, p. 1550. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 44-46).
55

Chromatographic analysis of barley malt extracts on diethylaminoethyl-cellulose

Smith, Marvin Artell, January 1962 (has links)
Thesis (M.S.)--University of Wisconsin--Madison, 1962. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 55-57).
56

Experimental verification and thermodynamic study of the reversal of elution order in chromatography /

Clark, Jonna B. January 2007 (has links) (PDF)
Thesis (M.S.)--University of North Carolina Wilmington, 2007. / Includes bibliographical references (leaves: 80-81)
57

Studies in gas chromatography, with special reference to thermal and discharge reactions

Andrews, T. D. January 1964 (has links)
No description available.
58

Identification and characterization of novel oncology related platinum complexes using chromatographic and mass spectrometric techniques

Wentzel, Mauritz January 2008 (has links)
In this thesis mass spectral and chromatographic techniques were developed and applied to identify and characterise numerous novel platinum(II) and (IV) compounds designed as anticancer agents. In a novel method for the synthesis of cis-oxalato(trans- -1,2- cyclohexanediamine)platinum(II) or oxaliplatin these techniques could be applied to differentiate between the molecular complex and the autoionised analogue (viz. Ptdach2 2+Ptox2 2-). In another novel synthetic method for the same compound the ligand exchange reactions at various temperatures could be investigated and kinetic curves obtained served to illuminate the chemistry involved, indicating the role of small amounts of water in the essentially non-aqueous solvent systems dmf and isoamyl alcohol respectively. These allowed ligand exchange without resulting in hydrolyses even up to 85°C. The ionisation rate of divalent platinum halide complexes was determined for various amine ligands as well as N-S chelate ligands. A comparison of these could suggest why N-S complexes have poor anticancer action. Ionisation was not only studied for neutral molecular species but also for monocationic ones. Relationships could be found with stereochemical aspects of the chelates used. By investigating results of EV-CAD studies thermodynamic data could be obtained which indicated that bond strength decreases from chloro to iodo analogues although extent of ionisation in aqueous solution, i.e kinetic stability, is the reverse. Products formed by the reaction of NO2 gas with Platinum(II) compounds could be identified and separated which greatly contributed to the understanding of the chemistry involved in the formation of mononitro platinum(IV) complexes. Some of these proved to have exceptional anticancer properties. Studies of the interaction of thiol containing biomolecules were performed as a function of time. The results contributed to the understanding of the action of the anticancer agents.
59

Studies in the polysaccharide gums with special reference to sapote gum

Kilgour, Gordon Leslie January 1953 (has links)
Two samples of gum supposedly obtained from Sapotaceae achras and named "sapote gum" were studied using the methods of partition chromatography. The two samples were proven to be entirely different in composition and to constitute in fact two separate and distinct gums. The previously unreported gum was characterized and shown to contain D-xylose, L-arabinose, D-galactose, and one or more glucuronic acids, including some methoxy-glucuronic acid. A new spray reagent was developed for paper chromatography of the sugars, and a novel technique used for making permanent photographic prints of the papergrams. Crystalline sugars were obtained from hydrolysates in pure form by separation on partition columns of powdered cellulose. / Science, Faculty of / Chemistry, Department of / Graduate
60

Studies in gas chromatography and the reaction of methyl radicals with butene-1

Ryce, Stephen Alan January 1958 (has links)
Studies in the general field of gas chromatographic analysis have been made and some of the methods developed have been applied to a kinetic investigation of the reactions of methyl radicals with butene-1. In Part I the developments in the field of gas chromatography are described. An all-metal thermal conductivity cell with platinum sensing elements has been designed and constructed. Excellent compensation for the resulting changes of flow rate of the carrier gas was attained in analyses with rising column temperature. The use of thermistors as sensing elements in such cells was also studied. The influence of polarity of the stationary phase on relative retention volumes in gas partition chromatography was investigated in conjunction with the analysis of a complex mixture of organic sulfur compounds. Satisfactory separations of hydrogen sulfide, methyl mercaptan, ethyl mercaptan, methyl sulfide, propyl mercaptan, ethyl sulfide, thiophene and dimethyl disulfide were obtained. Isopentane and n-pentane were included for purposes of comparison. Irregularities were observed in relating retention volumes to boiling points for some of these compounds. Reversal of normal elution order within groups of compounds with different columns was related to the polarity of the column and the polarisability of the eluents. A high-sensitivity ionization gauge detector for gas chromatography was developed. By keeping the grid potential below the ionization potential of helium the device is sensitive only to the eluted compounds in the gas stream. Sensitivities from 100 to 500 times greater than those of thermal conductivity cells were observed. Only a small fraction of the gas stream emerging from the column is sufficient for detection purposes, and the device is insensitive to temperature and flow rate changes. Significant advantages may be obtained from the application of the newly developed ionization gauge detector to displacement chromatography because of the possibility of distinguishing between isomeric organic compounds. Results obtained with gas chromatographic methods without the use of a carrier gas are reported. A partial separation of a mixture of volatile organic compounds was obtained. The ionization gauge detector may be useful in the development of this method. In Part II the results obtained from the reaction of methyl radical with butene-1 are described. Alumina, squalane-pelletex, and tricresyl phosphate columns were used for the gas chromatographic analysis. Mass spectrometric identification of products was done where necessary. In the temperature range 160 to 220°C with di-t-butyl peroxide as the methyl source the following reaction products were identified: methane, ethane, 3-methyl-butene-1, pentene-2, n-pentane, isopentane, 3-methyl-pentane, and acetone. A mechanism accounting for the formation of these products and supported by kinetic evidence is presented. The butenyl and pentyl radicals formed in the reaction are stable near 200°C. Butenyl radical does not abstract hydrogen from butene-1 near 200°C, but combines with methyl to yield pentene-2 and 3-methyl-butene-1. The energy of activation for the formation of 3-methyl-butene-1 is from 2 to 4 kcal/mole higher than for the formation of pentene-2. Hydrogen abstraction by pentyl radicals from butene-1 gives n-pentane, and isopentane. The reactivity of the branched radical •CH₂CH[CH₃]CH₂CH₃ in hydrogen abstraction is twice as great as that of the straight chain radical CH₃CH₂CHCH₂CH₃. From material balances obtained it was found that 60 to 80% of butenyl, and from 7 to 30% of pentyl radicals are removed from the system by reactions other than combination with methyl and hydrogen abstraction in the case of pentyl. The disproportionation of pentyl radicals to pentane and pentene was unimportant in the present system. At 450 and 492°C methyl radicals do not sensitize the formation of the cyclic reaction products which were observed by other workers in the unsensitized pyrolysis of butene-1 at temperature near 500°C. The main reaction product of methyl with butene-1 at 450 and 492°C was found to be butene-2. The isomerization to butene-2 in the unsensitized reaction is a chain process with chain length increasing with temperature reduction. The mechanism of the chain reaction of isomerization is postulated to be: CH₂=CHCH₂CH₃ → CH₃ • + CH₂ = CHCH₂ • / CH₃ • + CH₂=CHCH₂CH₃ → CH₂=CHCHCH₃ + CH₄ / CH₂=CHCHCH₃ ↔ •CH₂CH=CHCH₃ / •CH₂CH=CHCH₃ + CH₂=CHCH₂CH₃ → CH₃CH=CHCH₃+ CH₂=CHCHCH₃. The chain length at 450°C was found to be 12.6, and at 492°C as 2.3. / Science, Faculty of / Chemistry, Department of / Graduate

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