Thesis (B.A. (Hons))--University of Adelaide, 1989.

Thesis (M.S.), Biology--University of Central Oklahoma, 2008. / Includes bibliographical references (leaves 98-104).

Thesis (PhD.(Chemistry)--University of Pretoria, 2008. / On title page: Submitted in partial fulfilment of the requirements for the degree Philosophiae Doctor in Chemistry in the faculty of Natural and Agricultural Sciences of the University of Pretoria. Includes bibliographical references.

Thesis (MSc)--University of Stellenbosch, 2008. / Bibliography. Also available via the Internet.

Made available in DSpace on 2014-06-11T19:35:03Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-07-22Bitstream added on 2014-06-13T19:44:50Z : No. of bitstreams: 1 lucas_mg_dr_arafo.pdf: 7609787 bytes, checksum: 818d8660089a22ed3354bf205e9bb72b (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Neste trabalho foram analisadas as alterações nas propriedades físicas e mecânicas de um gesso odontológico do tipo IV após a incorporação de dois agentes desinfetantes (Digluconato e Cloridrato de clorexidina). Foram realizados testes mecânicos para a análise do tempo de presa, reprodução de detalhes, expansão de presa e resistência à compressão, já as alterações físicas foram analisadas através de uma microscopia eletrônica de varredura (MEV) nos aumentos de 375, 750, 1500 e 3000x. Os resultados demonstraram que somente houve alterações significantes no tempo de presa com a incorporação de Digluconato de Clorexidina 2,0% sem diluição e a resistência a compressão que demonstrou valores significantemente inferiores em todas as incorporações, porém todas as alterações dentro do limite estabelecido pela normatização para gessos odontológicos. Pela análise da Microscopia Eletrônica de Varredura, pode-se observar que os cristais obtiveram um aumento pela associação com os agentes derivados da clorexidina diminuindo os microporos existentes. Com isso verificamos que os derivados da clorexidina podem ser uma alternativa para a obtenção de modelos biologicamente seguros. / The purpose of this study was to evaluate the alterations in physical and mechanical properties of a gypsum tipe IV after the incorporation of two disinfectant agents (Chlorhexidine hydrochlooride and Chlorhexidine gluconate). The mechanical tests are made for setting time, reproduction details, setting expansion and compressive tensile, and the physical properties was examinated in a scanning electron microscope (SEM) and photomicrographed are made in 375, 750,1500, 3000x and compared vissually. The results demonstrated were only significant alterations in the setting time with the incorporation of Chlorhexidine gluconate without dilution and the compression resistance that demonstrated under values in all of the incorporations, however all the alterations meet inside of the established limit for I.S.O values. In the analysis of the physical properties, the crystals obtained an increase for the association with the derived agent´s clorhexidine. In conclusion, the incorporation clorhexidine agents can be a alternative to obtained biological models in dentistry.

Orientador: João Neudenir Arioli Filho / Banca: Sérgio Russi / Banca: José Cláudio Martins Segalla / Banca: Raphael de Freitas Souza / Banca: Wirley Gonçalves Assunção / Resumo: Neste trabalho foram analisadas as alterações nas propriedades físicas e mecânicas de um gesso odontológico do tipo IV após a incorporação de dois agentes desinfetantes (Digluconato e Cloridrato de clorexidina). Foram realizados testes mecânicos para a análise do tempo de presa, reprodução de detalhes, expansão de presa e resistência à compressão, já as alterações físicas foram analisadas através de uma microscopia eletrônica de varredura (MEV) nos aumentos de 375, 750, 1500 e 3000x. Os resultados demonstraram que somente houve alterações significantes no tempo de presa com a incorporação de Digluconato de Clorexidina 2,0% sem diluição e a resistência a compressão que demonstrou valores significantemente inferiores em todas as incorporações, porém todas as alterações dentro do limite estabelecido pela normatização para gessos odontológicos. Pela análise da Microscopia Eletrônica de Varredura, pode-se observar que os cristais obtiveram um aumento pela associação com os agentes derivados da clorexidina diminuindo os microporos existentes. Com isso verificamos que os derivados da clorexidina podem ser uma alternativa para a obtenção de modelos biologicamente seguros. / Abstract: The purpose of this study was to evaluate the alterations in physical and mechanical properties of a gypsum tipe IV after the incorporation of two disinfectant agents (Chlorhexidine hydrochlooride and Chlorhexidine gluconate). The mechanical tests are made for setting time, reproduction details, setting expansion and compressive tensile, and the physical properties was examinated in a scanning electron microscope (SEM) and photomicrographed are made in 375, 750,1500, 3000x and compared vissually. The results demonstrated were only significant alterations in the setting time with the incorporation of Chlorhexidine gluconate without dilution and the compression resistance that demonstrated under values in all of the incorporations, however all the alterations meet inside of the established limit for I.S.O values. In the analysis of the physical properties, the crystals obtained an increase for the association with the derived agent's clorhexidine. In conclusion, the incorporation clorhexidine agents can be a alternative to obtained biological models in dentistry. / Doutor

Made available in DSpace on 2014-06-11T19:29:45Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-08-31Bitstream added on 2014-06-13T18:39:46Z : No. of bitstreams: 1 maller_a_me_ilha.pdf: 506299 bytes, checksum: 2f6f5bc4b0471e6ddb7eae1caa041de2 (MD5) / O objetivo foi avaliar a eficiência da calagem e gessagem para o cultivo de algodão, que foram submetidos a diferentes modos de aplicação de fertilizante na semeadura, em região de Cerrado. O experimento foi desenvolvido na Fazenda experimental de Ensino, Pesquisa e Extensão da FE/Unesp, localizado no município de Selvíria-MS (20º22’S e 51º22’W e 335 m de altitude), num LATOSSOLO VERMELHO DISTROFÉRRICO. O delineamento experimental utilizado foi blocos ao acaso, em esquema fatorial 4x3, sendo o primeiro fator manejo da calagem e gessagem (calagem, gessagem, calagem+gessagem, testemunha); o segundo fator foi o modo de aplicação do adubo na semeadura (sulco, à lanço, testemunha), sendo que quando foi efetuada a análise em profundidade, esta foi considerada como o terceiro fator, em um esquema 4x3x3 e as profundidades de 00-10, 10-20 e 20-30 cm, com 4 repetições. Aos 85 dias após emergência (DAE) avaliou-se os teores de macronutrientes foliares das plantas. E ainda no final do ciclo da cultura determinou os componentes de produção (massa de 20 capulhos, massa de 100 sementes, % de fibra e produtividade) e análise de macronutrientes no solo em diferentes profundidades, após a colheita. A calagem proporcionou acréscimos nos teores de Ca, Mg, aumentou os valores de Soma de Bases (SB) e V% . A calagem aumentou o pH do solo, assim reduzindo os teores de Al de H+Al. O gesso não altera o pH do solo, porém a gessagem associada com adubação aplicada à lanço reduziu H+Al e Al, aumentou os valores de SB, além do teor de Ca. O teor foliar de Mg foi alterado pela calagem, sendo que a gessagem proporciona aumentos no S foliar do algodoeiro / The objective was to evaluate the efficiency of the limestone, and gypsum in the ground tillage of cotto crop was submitted to different methods of fertilizer application in the sowing. The esperiment was developed in the experimental Farm of the São Paulo State University FE/Unesp, located in the city of Selvíria-MS (20º22’ S and 51º22’ W and 335 altitude m, in Dark Red Latossol with midian texture. The experiment design delineation was te completely blocks in the sysytem factorial 4 X 3 with the first factor: lamestone and gypsum application with four types; a) limestone, b) gypsum, c) limestone + gypsum and d) control. And the second factor was: a) fertilizer on the ridge, b) fertilizer moad carled, and c) control. With 4 repetition. At 85 days after sowing the leasf content of nutrients was evaluated. In the harvest, the production componets (mass of 20 bolls weight, weight of 100 seeds, % of lint and yield, and soyl analizing in different depths were colhected. It’s concluded that levels of Ca, Mg, K, SB and value V% and pH in the soil and reduce Al and H+Al. Gypsum does not modify pH. The foliar levels of Mg was modified by the limestone and the gypsum provides the increase in the foliar S of the cotton plant

nÃo hà / The accelerated industrial development of recent decades has been touted as one of the most impacting factors on the environmental imbalance. For this reason, research has been developed aiming, among other objectives, the reuse of waste generated by industrial processes as raw materials or inputs in other processes. This study aims to investigate the viability of using waste generated by the combustion of coal in power plants as an additive in the production of gypsum parts for construction. Coal combustion products (CCP) are already being applied in the construction industry as an additive in concrete, but their use in gypsum masses is very limited, which motivated the current reseach project. Initially the influence of water by varying the addition on mass in 5 levels between 10 and 50% was evaluated in order choose the best ratio water / gypsum about the mechanical properties. The materials used were characterized by fluorescence spectroscopy X-ray (XRF), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and energy dispersive X-ray (EDS) and scanning electron microscopy (SEM). The production process used for making the specimens was the so-called UCOS (portuguese acronym for the initials of wetting, compaction and drying), with pressure of 10 MPa. Then, test pieces were prepared with incorporation of PCC to the mass of gypsum in 5 levels between 10 and 50% to analyze the influence of these additions on mechanical properties, which was evaluated by compression tests, hardness and three point bending. The results determined that the water/gypsum (a/g) that provides the best mechanical properties is 0.2, which is used in the evaluation stage of the specimens with addition of PCC. It was concluded that, in general, increasing the incorporation of the waste was damaging to the mechanical properties of the gypsum block. Nonetheless, the studied conditions meet the requirements of NBR 13207, except for the condition with incorporation of 50% of PCC. In general, the mechanical properties behaved in similarly conditions between 10 and 20% of PCC, but the evolution from 20 to 30% caused a significant decrease in the results. Thus, it is concluded that the condition of 20% PCC in plaster and ratio a/g 0,2 meets the standard, ensures recycling of waste and, due to the pressing process, has better mechanical strength compared to the usual products. / O acelerado desenvolvimento industrial das ultimas dÃcadas tem sido apontado como um dos fatores mais impactantes sobre o desequilÃbrio ambiental. Por esse motivo, pesquisas vÃm sendo desenvolvidas visando o reaproveitamento dos resÃduos gerados pelos processos produtivos industriais como matÃrias-primas ou insumos em outros processos. Este trabalho objetiva investigar a viabilidade de se utilizar um resÃduo gerado pela combustÃo de carvÃo mineral em usinas termoelÃtricas como aditivo na produÃÃo de peÃas de gesso para a construÃÃo civil. Este produto da combustÃo de carvÃo (PCC) jà vem sendo aplicado nas indÃstrias de construÃÃo civil como aditivo em cimento, porÃm sua utilizaÃÃo em massas de gesso à bastante restrita. Inicialmente foi avaliada a influÃncia da Ãgua pela variaÃÃo da sua adiÃÃo à massa de gesso em 5 nÃveis entre 10 e 50%, visando escolha da melhor relaÃÃo Ãgua/gesso quanto Ãs propriedades mecÃnicas. Os materiais utilizados foram caracterizados por espectroscopia de fluorescÃncia de raios-X (FRX), difraÃÃo de raios-X (DRX), espectroscopia de absorÃÃo no infravermelho por transformada de Fourier (FTIR) e de energia dispersiva de raios-X (EDS) e microscopia eletrÃnica de varredura (MEV).O processo produtivo utilizado para confecÃÃo dos corpos de prova foi o de Umedecimento, CompactaÃÃo e Secagem (UCOS), com pressÃo de 10 MPa. Em seguida, foram confeccionados corpos de prova com incorporaÃÃo de PCC à massa de gesso em 5 nÃveis, entre 10 e 50% com a finalidade de analisar a influÃncia dessas adiÃÃes sobre as propriedades mecÃnicas, o que foi avaliado por ensaios de compressÃo, dureza e flexÃo em trÃs pontos. Os resultados obtidos determinaram que a relaÃÃo Ãgua/gesso (a/g) que fornece as melhores propriedades mecÃnicas à a de 0,2, sendo esta utilizada na etapa de avaliaÃÃo dos corpos de prova com incorporaÃÃo de PCC. Concluiu-se que, em geral, a crescente incorporaÃÃo do resÃduo foi danosa Ãs propriedades mecÃnicas do bloco de gesso. NÃo obstante, as condiÃÃes estudadas atendem Ãs exigÃncias da NBR 13207, exceto a condiÃÃo com incorporaÃÃo de 50% de PCC. Em geral, as propriedades mecÃnicas se comportaram de forma semelhante entre as condiÃÃes com 10 e 20% de PCC, sendo que a evoluÃÃo de 20 para 30% gerou queda significativa nos resultados de resistÃncia mecÃnica. Com isso, conclui-se que a condiÃÃo de 20% de PCC em gesso e relaÃÃo a/g de 0,2 atende à norma, permite o reaproveitamento de resÃduos e, graÃas ao processo de prensagem, apresenta melhor resistÃncia mecÃnica comparada aos produtos usuais.

Gypsiferous water, i.e water containing high levels of calcium sulphate, is used to irrigate crops such as maize and wheat on a commercial scale, in some parts of South Africa due to shortage of irrigation water. Gypsiferous water is saline due to the presence of Ca2+, S042- and sometimes Mg2+ in solution. These salts may have a detrimental effect on herbicide performance. Possible herbicide injury to crops has been reported in areas irrigated with gypsiferous water, which suggested interaction between herbicides and gypsiferous water. Bioassay experiments were conducted in the greenhouse to assess whether the bioactivity and persistence of the selected herbicides were affected by the presence of gypsum in the soil. The biological activity of atrazine was significantly increased in the presence of gypsum, and in the case of 2,4-D the same effect was even more pronounced. In contrast, the activity of metolachlor was reduced in the presence of gypsum. These differential effects on herbicide activity would have important practical consequences for herbicide performance, i.e weed control efficacy, selectivity, and behaviour in soil. In the persistence experiment, the activity of all herbicides decreased with time. However, the presence of gypsum had a significant effect on the rate of dissipation of only atrazine. In the presence of gypsum the rate of loss of atrazine was significantly less compared to its rate of loss in soil that did not contain gypsum. The rate of loss of metolachlor was not significantly affected by the presence of gypsum, and in the case of 2,4-D the trends were not clear at all. A further experiment was conducted to determine the leaching potential of metolachlor and atrazine in soil irrigated with either gypsiferous water or uncontaminated water. In the leaching experiment metolachlor showed a significant growth reduction of 39% in the first 10 cm column zone in soil irrigated with gypsiferous water and no further losses were observed in deeper column segments, and this indicated that there would be no threat of groundwater contamination. However, the results showed that weeds with shallow roots would be effectively controlled in this column. Similar results were observed in soil without gypsiferous water irrigated. The findings of this experiment appear to contradict the findings of Chapter 4 for metolachlor, however it is to be considered that in Chapter 4 the "close system" was used and in the leaching experiment an "open system" was used. In addition, the calcium sulphate concentrations for the two experiments were different. In the atrazine experiment it was found that 0.1 mg kg-1 would pose a serious threat to groundwater contamination and sensitive follow-up crops. There is a need to reduce the atrazine dosage rate to 0.05 mg kg-1 because no threat to groundwater was observed at this rate. However, weed control efficacy at this low rate maybe poor. / Dissertation (MSc (Agric): Weed Science)--University of Pretoria, 2006. / Plant Production and Soil Science / unrestricted

Two soils were used in this soil column study. Yolo loam soil a non- c al c areous, non-gypsiferous soil from central California and Vernal soil a calcareous soil from eastern Utah. Initial studies were conducted where the solubilities of pure CaC0 3 and CaS0 4 ' 2H 2 0 were determined in the presence of Logan river water, a KCl solution (2.8 mmhos/cm) and a K 2 S0 4 solution (Z. 7 mmhos/cm). Gypsum was more soluble in the KCl solution than in the K Z S0 4 solution. The solubility product of both gypsum and lime were determined from the analytical data. The formation of CaS0 4 0 and caco 3 0 ion pairs were cons idered to be the most important complex ions pres ent. A reasonable agreement was observed between the theoretical values of K and the ca lculated K sp sp Essentially the same results were obtained when these waters were used in leaching the columns of Yolo and Vernal soil columns The solubility of gypsUJn was greatest usmg the KCl leaching' solution and least using the K 2504 leaching solution. Logan river water gave intermediate values. Calcium carbonate was most soluble in the K 2504 leaching solution and les s in the KCl solution. It was found that measuring the ci+ concentration in the effluent was a more reliable index to steady state condition than using an electrical conductivity lneasurement. Unsaturated flow removed more salt per unit volume of effluent than saturated flow. The relative area method was used to analyze the effluent under saturated moisture flow. 2+ It was found that a certain amount of Ca derived from gypsum dissolution precipitated in the column as CaC0 3 . This amount 2+ , was greater than 15% of the Ca dlssolved from gypsum.