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1	Studies on environmentally benign depressants in mineral flotation : Khmeleva, T. N. Unknown Date (has links) The effects of sodium bisulphate on the xanthate-induced flotation of chalcopyrite, copper-activated sphalerite and copper-activated pyrite have been studied. These investigations were conducted in two steps: 1) single mineral studies with varying experimental conditions; and 2) a mixed mineral chalcopyrite-pyrite-sphalerite study. A number of solution and surface spectroscopic techniques were used, which allowed simultaneous investigation of the mechanisms of interaction of sulphite ions with the mineral surfaces, and with the xanthate species in solution and its adsorbed state. Based on the results obtained, the following depressing mechanisms have been proposed. / It was found that sulphite ions had no depressing effect on chalcopyrite flotation under the experimental conditions studied. It was suggested that the main species responsible for chalcopyrite floatation were the hydrophobic sulphur-like species, such as an iron deficient chalcopyrite and polysulphide, and to some extent the adsorbed collector species. Sodium bisulphite did not decompose these hydrophobic phases on the chalcopyrite surface. It was also found that the chalcopyrite surface was not heavily oxidised either in the presence or absence of sulphite ions. / From the single mineral studies it was concluded that sodium bisulphite had a complex effect on the xanthate-induced floatation of copper-activated pyrite and sphalerite. These results demonstrated that under the experimental conditions tested, the following processes contribute to the selective depression of pyrite and sphalerite: (i) Xanthate decomposition in solution by sulphite ions, hence reducing the xanthate adsorption on the mineral surfaces. (ii) Collector removal from the mineral particles, rendering the mineral surfaces more hydrophilic. (iii) Sulphite oxidation to sulphate, accompanied by consumption of dissolved oxygen in solution, thus limiting collector adsorption (accompanied by a drop of pulp redox potential). (iv) Decomposition of hydrophobic sulphur-like species on the sphalerite and pyrite surfaces, rendering the mineral particles less floatable. (v) Surface oxidation of pyrite and sphalerite particles to produce hydroxide and oxy species, also rendering the mineral surfaces hydrophilic and preventing collector adsorption. As expected, these effects were more pronounced in the floatation experiments with air purging. / The mixed mineral study demonstrated that sodium bisulphate acted as an effective depressant for pyrite and sphalerite in the mineral mixture, while the chalcopyrite floatability was almost un-affected by sulphite ions. It was found that the mechanisms proposed for single mineral systems could satisfactorily explain the effect of sodium bisulphite on the floatation results obtained with the chalcopyrite-sphalerite-pyrite mineral mixture. Chalcopyrite floatation was not depressed by sulphite, due to the high stability of adsorbed xanthate species, and also due to the natural floatability of the chalcopyrite particles. At the same time, a reduction in the adsorbed collector concentration and a commensurate increase in surface hydrophilicity were responsible for the depression of pyrite and sphalerite from the mineral mixture in the presence of sulphite ions. / Thesis (PhDAppliedEngineering)--University of South Australia, 2003. Flotation Sodium bisulphite Chalcopyrite
2	Action of sodium bisulfite on lignin model compounds Sen, Biswanath 01 January 1952 (has links) see pdf Lignins Model compounds Analysis Sulfonation Sulphonation Bisulfites Sodium bisulphite
3	Action of sodium bisulfite on lignin model compounds Sen, Biswanath, January 1952 (has links) (PDF) Thesis (Ph. D.)--Institute of Paper Chemistry, 1952. / Includes bibliographical references (p. 66-68).
4	Polimerização aquosa do Metil Metacrilato (MMA) na presença da vermiculita modificada pela troca por Íons Cromo (III) e Cobalto (II). / Aqueous Polymerization of Methyl Methacrylate (MMA) in the presence of vermiculite modified by the exchange for Ions Chromium (III) and Cobalt (II). SUDÉRIO, Vilma Maria. 28 September 2018 (has links) Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-09-28T18:12:22Z No. of bitstreams: 1 VILMA MARIA SUDÉRIO - DISSERTAÇÃO PPGEQ 1995..pdf: 12571558 bytes, checksum: 00b0d5b9a33da42cdeac794bde348de8 (MD5) / Made available in DSpace on 2018-09-28T18:12:22Z (GMT). No. of bitstreams: 1 VILMA MARIA SUDÉRIO - DISSERTAÇÃO PPGEQ 1995..pdf: 12571558 bytes, checksum: 00b0d5b9a33da42cdeac794bde348de8 (MD5) Previous issue date: 1995-11-06 / Neste trabalho investigou-se a atividade catalítica da vermiculita natural (V-N) e trocada com cromo (III), (V-Cr) e cobalto (II), (V-Co), na reação de polimerização aquosa do metil metacrilato (MMA). utilizando bissulfito de sódio como iniciador. Foi estudada a influência de vários fatores, como: presença dos catalisadores V-N, V-Cr e V-Co. temperatura de calcinação dos catalisadores, massa dos catalisadores, tempo de polimerização, teor de cátions cromo (III) e cobalto(II) trocados, concentração de MMA e NaHSO? e temperatura de polimerização, sobre a velocidade de polimerização do MMA. A partir dos resultados obtidos foram observados os seguintes efeitos: 1) a V-N apresentou um efeito catalítico na reação, sendo que este efeito foi mais significativo quando os catalisadores V-Cr e V-Co foram utilizados, e que a V-Cr apresentou o maior efeito catalítico. A atividade catalítica cresceu, com o aumento dos teores dos cátions cromo e cobalto trocados; 2) o aumento da temperatura de calcinação de 100 até 800°C, das amostras V-Cr e V-Co, aumentaram a sua atividade catalítica. Entretanto, este aumento foi maior na temperatura de 400°C: 3) os efeitos dos outros fatores, citados no paragrafo anterior, mostraram um aumento na conversão do MMA. Porém, nos altos valores de conversão, foi observada a desativação dos sítios ativos, devido ao recobrimento das partículas dos catalisadores, pelo polímero formado; 4) o efeito catalítico das amostras estudadas é explicado com base no mecanismo em que a presença dos cátions de metais de transição na superfície da vermiculita. favorecem a dissociação do iniciador, produzindo maior quantidade de radicais de bissulfito, que em conseqüência aumentam a taxa de polimerização. / This work presents an investigation of the catalytic activity of the natural vermiculite (V-N) and that of vermiculite exchanged with chromium (III) (V-Cr) and Cobalt (II) (V-Co) for the aqueous polymerization of metil methacrylate (MMA), using sodium bissulfite as an initiator. The influence of various factors, as the presence of catalysts V-N, V-Cr e V-Co, calcination temperature of catalysts, catalyst mass, polymerization time, amount of exchanged chromium and cobalt cations, MMA and NaHSO? concentration and polymerization temperature, on the rate of polymerization of MMA has been studied. Based on the results obtained the following effects have been observed: 1) the samples of V-N, V-Cr and V-Co have shown catalytic activity on the aqueous polymerization reaction of MMA, and V-Cr being more significant. The catalytic activity was increased with the increase of the amounts of exchanged chromium and cobalt cations; 2) the increase in the calcination temperature from 100 to 800°C for the samples of V-Cr and V-Co increased their catalytic activity. However, this increase was highest for 400°C; 3) the effect of other factors mentioned in the previous paragraph also showed an increase in MMA conversion. However, for higher values of conversion, due to covering of the catalyst particles by the polymer formed, deactivation of the active sites was observed; 4) the catalytic effect of the samples studied is explained on the basis of mechanism that the presence of transition metal cations on the vermiculite surface favor the initiator dissociation and thereby more bissulfite radicals are produced which in consequence increase the polymerization rate of the MMA. Engenharia Química. Metil Metacrilato - MMA Polimerização aquosa do Metil Vermiculita modificada Íons Cromo Cobalto Bissulfito de sódio Aqueous Polymerization of Methyl Sodium bisulphite
5	A Novel Approach to Identify Candidate Imprinted Genes in Humans Shapiro, Jonathan 21 March 2012 (has links) Many imprinted genes are necessary for normal human development. Approximately 70 imprinted genes have been identified in humans. I developed a novel approach to identify candidate imprinted genes in humans using the premise that imprinted genes are often associated with nearby parent-of-origin-specific DNA differentially methylated regions (DMRs). I identified parent-of-origin-specific DMRs using sodium bisulfite-based DNA (CpG) methylation profiling of uniparental tissues, mature cystic ovarian teratoma (MCT) and androgenetic complete hydatidiform mole (AnCHM), and biparental tissues, blood and placenta. In support of this approach, the CpG methylation profiling led to the identification of parent-of-origin-specific differentially methylated CpG sites (DMCpGs) in known parent-of-origin-specific DMRs. I found new DMRs for known imprinted genes NAP1L5 and ZNF597. Most importantly, I discovered many new DMCpGs, which were associated with nearby genes, i.e., candidate imprinted genes. Allelic expression analyses of one candidate imprinted gene, AXL, suggested polymorphic imprinting of AXL in human blood. Allele Allele-specific DNA Methylation Allele-specific Gene Expression Allele-specific Expression Allele-specific Methylation AnCHM Androgenetic Androgenetic Mole Mole Complete Mole Hydatidiform Mole Complete Hydatidiform Mole Androgenetic Hydatidiform Mole Androgenetic Complete Hydatidiform Mole Biparental Tissue Bisulfite Bisulphite Blood Blood DNA Computational Biology DNA Methylation DNA Methylation Profiling Epigenetic Epi-genetic Epigenomic Epi-genomic Expression Expression Regulation Gene Expression Gene Expression Regulation Genetic Genetic Imprint Genetic Imprinting Genomic Genomic DNA Genomic Imprint Genomic Imprinting Human Imprint Imprinting Teratoma Ovarian Teratoma Cystic Teratoma Mature Teratoma Mature Cystic Teratoma Mature Ovarian Teratoma Cystic Ovarian Teratoma Mature Cystic Ovarian Teratoma MCT Methylation Cytosine Methylation Microarray Neoplasm Ovarian Neoplasm Placenta Profiling Promoter Promoter Region Sodium Bisulfite Sodium Bisulphite Uniparental Tissue WB WBC Imprinted Gene Polymorphic Imprinting Parent-of-origin Parent-of-origin-specific Methylation Parent-of-origin-specific Expression 0369 0307
6	A Novel Approach to Identify Candidate Imprinted Genes in Humans Shapiro, Jonathan 21 March 2012 (has links) Many imprinted genes are necessary for normal human development. Approximately 70 imprinted genes have been identified in humans. I developed a novel approach to identify candidate imprinted genes in humans using the premise that imprinted genes are often associated with nearby parent-of-origin-specific DNA differentially methylated regions (DMRs). I identified parent-of-origin-specific DMRs using sodium bisulfite-based DNA (CpG) methylation profiling of uniparental tissues, mature cystic ovarian teratoma (MCT) and androgenetic complete hydatidiform mole (AnCHM), and biparental tissues, blood and placenta. In support of this approach, the CpG methylation profiling led to the identification of parent-of-origin-specific differentially methylated CpG sites (DMCpGs) in known parent-of-origin-specific DMRs. I found new DMRs for known imprinted genes NAP1L5 and ZNF597. Most importantly, I discovered many new DMCpGs, which were associated with nearby genes, i.e., candidate imprinted genes. Allelic expression analyses of one candidate imprinted gene, AXL, suggested polymorphic imprinting of AXL in human blood. Allele Allele-specific DNA Methylation Allele-specific Gene Expression Allele-specific Expression Allele-specific Methylation AnCHM Androgenetic Androgenetic Mole Mole Complete Mole Hydatidiform Mole Complete Hydatidiform Mole Androgenetic Hydatidiform Mole Androgenetic Complete Hydatidiform Mole Biparental Tissue Bisulfite Bisulphite Blood Blood DNA Computational Biology DNA Methylation DNA Methylation Profiling Epigenetic Epi-genetic Epigenomic Epi-genomic Expression Expression Regulation Gene Expression Gene Expression Regulation Genetic Genetic Imprint Genetic Imprinting Genomic Genomic DNA Genomic Imprint Genomic Imprinting Human Imprint Imprinting Teratoma Ovarian Teratoma Cystic Teratoma Mature Teratoma Mature Cystic Teratoma Mature Ovarian Teratoma Cystic Ovarian Teratoma Mature Cystic Ovarian Teratoma MCT Methylation Cytosine Methylation Microarray Neoplasm Ovarian Neoplasm Placenta Profiling Promoter Promoter Region Sodium Bisulfite Sodium Bisulphite Uniparental Tissue WB WBC Imprinted Gene Polymorphic Imprinting Parent-of-origin Parent-of-origin-specific Methylation Parent-of-origin-specific Expression 0369 0307

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