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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.
1

Nucleation and growth of inorganic crystals at the organic-inorganic interface /

Dennis, Shelli R. January 1998 (has links)
Thesis (Ph. D.)--University of Washington, 1998. / Vita. Includes bibliographical references (leaves [140]-152).
2

Perfilometria e microscopia eletrônica de varredura da superfície dentinária após escovação com cremes dentais dessensibilizantes e desafio erosivo com fruta amazônica / Profilometry and scanning electron microscopy of dentin surface after brushing with desensitizing toothpastes and challenge

Rocha, Max Pinto da Costa da 13 December 2012 (has links)
O objetivo deste estudo in vitro foi avaliar o potencial erosivo de suco de fruta amazônica ácida sobre a superfície dentinaria associado ao efeito abrasivo de diversos cremes dentais contendo agentes dessensibilizantes. O trabalho foi dividido em 3 fases distintas: Na fase 1, o valor do pH inicial de diversas frutas amazônicas foi medido utilizando 50 ml de cada suco, obtido de polpa industrializada. Foi utilizado um eletrodo de pH calibrado e a água destilada foi utilizada como controle. Na fase 2, 120 espécimes de dentina bovina foram submetidos a ciclos alternados de desafio abrasivo e erosivo, com a fruta escolhida na fase 1. Os espécimes foram divididos aleatoriamente em Grupo A (Desafio Abrasivo) e Grupo B (Desafio Erosivo e Abrasivo). Cada um destes grupos foram subdivididos em 5 subgrupos: 1: Água Destilada (Controle Negativo), 2: Colgate Tripla Ação (Controle Positivo), e os demais de acordo com o creme dental utilizado 3: Sensodyne Rápido Alívio, 4: Colgate Pró-Alivio e 5: Sensodyne Repair&Protect, (n=9). Na fase 3 foi realizado microscopia eletrônica de varredura para avaliar qualitativamente os espécimes (n=3). - O suco da fruta taperebá (Spondias mombin) apresentou os menores valores de pH, diante disso, foi escolhido como agente erosivo; Os testes de Kruskall Wallis e Teste de Dunn, mostraram que para os grupos nos quais somente a abrasão foi realizada, todos os cremes dentais mostraram comportamentos semelhantes em relação a perfilometria, não havendo diferença estatisticamente significante entre os grupos. Porém, para os grupos nos quais o processo erosivo foi adicionado, observou-se a potencialização do processo abrasivo, sendo que os cremes dentais Sensodyne Rápido Alivio e Colgate Sensitive Pro-Alivio foram os que mostraram menores alterações superficiais no padrão de perfilometria, comparados com o grupo controle negativo. Já os cremes dentais, Colgate Tripla Ação (controle positivo) e Sensodyne Repair&Protect apresentaram-se semelhantes entre si e com uma perda de estrutura dentinaria. mais significante. Conclui-se que o efeito erosivo da fruta amazônica taperebá é fator de grande importância na potencialização do efeito abrasivo, mesmo quando do uso de cremes dentais com agentes dessensibilizantes.. Na análise qualitativa da superfície dentinária em MEV, com exceção do Colgate tripla ação, os demais grupos não apresentaram oclusão tubular após o desafio ácido / The aim of this in vitro study was to evaluate the erosive potential of amazonian fruit juice with or without the abrasive challenge with various toothpastes containing desensitizing agents. The work was divided into three phases: in phase 1, the pH of various Amazonian fruits was evaluated. In step 2 it was performed surface perfilometry of the specimens, and in phase 3 it was evaluated qualitatively the dentin surface. In step 1, the initial pH value of several amazonian fruits was measured using 50 mL of each juice, from industrialized pulp. It was used a calibrated pH electrode, and distilled water was used as control. In step 2, 120 bovine dentin specimens were subjected to alternate cycles of abrasive and erosive challenge, with the fruit chosen in step 1. The specimens were randomly divided into Group A (without erosion) and Group B (with erosion). Each of these groups were divided into 5 groups: 1: Distilled Water, 2: Colgate Tripla Ação, 3: Sensodyne Rápido Alívio, 4: Pro-Alivio, 5: Sensodyne Repair & Protect, (n = 9). In Phase 3 it was conducted scanning electron microscopy to evaluate qualitatively the specimens (n=3). As a result it can be stated that: 1. The juice of the taperebá fruit had the lowest pH values, so it was chosen as the erosive agent; 2. For the groups in which only the abrasion was performed, all toothpastes showed similar behaviors, no statistically significant difference was observed between groups, but for the groups in which the erosion process was added, there was a potentiation of the abrasive process, and the toothpastes showed different profiles. The toothpaste Sensodyne Rapido Alívio Pró-Alívio was the ones that showed lower mineral loss, compared with the negative control group. Colgate Tripla Ação and Sensodyne Repair&Protect were similar among themselves and with a more significant mineral loss. It can be conclude that erosive effect of diet is a factor of great importance in the potentiation of abrasive effect. Clinical studies are essential to determine the dentin hypersensitivity levels after use of toothpaste used.
3

Perfilometria e microscopia eletrônica de varredura da superfície dentinária após escovação com cremes dentais dessensibilizantes e desafio erosivo com fruta amazônica / Profilometry and scanning electron microscopy of dentin surface after brushing with desensitizing toothpastes and challenge

Max Pinto da Costa da Rocha 13 December 2012 (has links)
O objetivo deste estudo in vitro foi avaliar o potencial erosivo de suco de fruta amazônica ácida sobre a superfície dentinaria associado ao efeito abrasivo de diversos cremes dentais contendo agentes dessensibilizantes. O trabalho foi dividido em 3 fases distintas: Na fase 1, o valor do pH inicial de diversas frutas amazônicas foi medido utilizando 50 ml de cada suco, obtido de polpa industrializada. Foi utilizado um eletrodo de pH calibrado e a água destilada foi utilizada como controle. Na fase 2, 120 espécimes de dentina bovina foram submetidos a ciclos alternados de desafio abrasivo e erosivo, com a fruta escolhida na fase 1. Os espécimes foram divididos aleatoriamente em Grupo A (Desafio Abrasivo) e Grupo B (Desafio Erosivo e Abrasivo). Cada um destes grupos foram subdivididos em 5 subgrupos: 1: Água Destilada (Controle Negativo), 2: Colgate Tripla Ação (Controle Positivo), e os demais de acordo com o creme dental utilizado 3: Sensodyne Rápido Alívio, 4: Colgate Pró-Alivio e 5: Sensodyne Repair&Protect, (n=9). Na fase 3 foi realizado microscopia eletrônica de varredura para avaliar qualitativamente os espécimes (n=3). - O suco da fruta taperebá (Spondias mombin) apresentou os menores valores de pH, diante disso, foi escolhido como agente erosivo; Os testes de Kruskall Wallis e Teste de Dunn, mostraram que para os grupos nos quais somente a abrasão foi realizada, todos os cremes dentais mostraram comportamentos semelhantes em relação a perfilometria, não havendo diferença estatisticamente significante entre os grupos. Porém, para os grupos nos quais o processo erosivo foi adicionado, observou-se a potencialização do processo abrasivo, sendo que os cremes dentais Sensodyne Rápido Alivio e Colgate Sensitive Pro-Alivio foram os que mostraram menores alterações superficiais no padrão de perfilometria, comparados com o grupo controle negativo. Já os cremes dentais, Colgate Tripla Ação (controle positivo) e Sensodyne Repair&Protect apresentaram-se semelhantes entre si e com uma perda de estrutura dentinaria. mais significante. Conclui-se que o efeito erosivo da fruta amazônica taperebá é fator de grande importância na potencialização do efeito abrasivo, mesmo quando do uso de cremes dentais com agentes dessensibilizantes.. Na análise qualitativa da superfície dentinária em MEV, com exceção do Colgate tripla ação, os demais grupos não apresentaram oclusão tubular após o desafio ácido / The aim of this in vitro study was to evaluate the erosive potential of amazonian fruit juice with or without the abrasive challenge with various toothpastes containing desensitizing agents. The work was divided into three phases: in phase 1, the pH of various Amazonian fruits was evaluated. In step 2 it was performed surface perfilometry of the specimens, and in phase 3 it was evaluated qualitatively the dentin surface. In step 1, the initial pH value of several amazonian fruits was measured using 50 mL of each juice, from industrialized pulp. It was used a calibrated pH electrode, and distilled water was used as control. In step 2, 120 bovine dentin specimens were subjected to alternate cycles of abrasive and erosive challenge, with the fruit chosen in step 1. The specimens were randomly divided into Group A (without erosion) and Group B (with erosion). Each of these groups were divided into 5 groups: 1: Distilled Water, 2: Colgate Tripla Ação, 3: Sensodyne Rápido Alívio, 4: Pro-Alivio, 5: Sensodyne Repair & Protect, (n = 9). In Phase 3 it was conducted scanning electron microscopy to evaluate qualitatively the specimens (n=3). As a result it can be stated that: 1. The juice of the taperebá fruit had the lowest pH values, so it was chosen as the erosive agent; 2. For the groups in which only the abrasion was performed, all toothpastes showed similar behaviors, no statistically significant difference was observed between groups, but for the groups in which the erosion process was added, there was a potentiation of the abrasive process, and the toothpastes showed different profiles. The toothpaste Sensodyne Rapido Alívio Pró-Alívio was the ones that showed lower mineral loss, compared with the negative control group. Colgate Tripla Ação and Sensodyne Repair&Protect were similar among themselves and with a more significant mineral loss. It can be conclude that erosive effect of diet is a factor of great importance in the potentiation of abrasive effect. Clinical studies are essential to determine the dentin hypersensitivity levels after use of toothpaste used.
4

Poultry Litter Ash as an Alternative Fertilizer Source for Corn

Ervin, Clara 12 November 2019 (has links)
Poultry litter ash (PLA) is a co-product from manure-to-energy systems that originated in response to increased poultry litter (PL) volumes generated in concentrated poultry production regions. Investigating PLA as a crop fertilizer is an alternative solution to balancing poultry and crop regional nutrient cycling in the Commonwealth of Virginia. As the expanding world population places pressure on the poultry industry to meet consumption demands, increased PL production presents an obstacle to identify alternative uses for increased volumes. Currently, Virginia produces 44 million broilers with PL produced predominately in the Shenandoah Valley and Eastern Shore. Likewise, a growing world population places pressure on crop production areas and subsequently finite natural resources used for crop fertilization. Poultry litter ash is an alternative phosphorus (P) and potassium (K) source enhancing transportation logistics, repurposing PL nutrients, and offers dual purpose as a fertilizer and an energy source when compared to PL. Three PLA products [(fluidized bed bulk (FB Bulk), fluidized bed fly (FB Fly), and combustion Mix (CMix)], two manufactured co-products [(granulated poultry litter ash (GPLA), and ash coated urea (ACU)] were evaluated as P, K, and N sources for corn (Zea Mays L.) production in comparison to industry fertilizers [(PL, triple superphosphate (TSP), muriate of potash (KCL), and urea). A comprehensive examination of elemental composition, P speciation, P and K solubility, improved functionality into granulized forms, and field testing were conducted to discern PLA potential as an alternative fertilizer source. Poultry litter ash products were evaluated by total elemental analysis, backscatter-electron dispersive (BSED) microscopy, and X-ray absorption near edge structure (XANES) spectroscopy. Poultry litter ash elemental concentrations were highly variable ranging from 50.6 to 102.0 g P kg -1 and 62.6 to 120.0 g K kg -1 and were comparatively higher than PL concentrations. Phosphorus structures that provided and controlled P solubility were Ca and Ca-Mg-phosphate compounds. Spectroscopy confirmed Ca structures as predominately monetite (dicalcium phosphate anhydrous; CaHPO4; log K ̊ 0.30) and brushite (dicalcium phosphate dihydrate; CaHPO4.2H20; 0.63 log K ̊ ) species that were supported by BSED and elemental stoichiometric ratios (Ca:P; 1.12 to 1.71:1). Additionally, GPLA acidified from FB Fly had higher brushite and monetite percentages described by spectra models, translating into a more soluble Ca-phosphate species when compared to FB Fly original P species. Granulated poultry litter acidulation trials successfully identified a desired granulation point of 29% (14.5 g acid to 50 g PLA) phosphoric acid (75% H3PO4) acidulation. Acidulation dose response relationships created simple linear regression (SLR) equations that sufficiently (R2 > 0.80) described changes in total measurable P and water soluble P, pH, and exothermic reaction temperatures to increasing H3PO4 acidulation. Solubility tests included: sequential extraction, particle size effect on solubility, carbon effect on water soluble P, and Mehlich-1 extraction of PLA sources that confirmed decreased P solubility. A majority PLA P was found in bound plant unavailable fractions (87.7 to 97.7% P of total P). Granulated poultry litter ash had improved P plant available P of 36.0% P of total P. Carbon (C) effects on PLA P were examined by ashing PLA samples in a muffle furnace at 550 ̊C. Differences in total carbon content negatively impacted FB Bulk and CMix total P (1.30 and 4.56 g P kg -1); however, muffle furnace temperatures increased FB Fly total P by 6.74 g P kg -1. All fertilizer products were investigated under field conditions in separate P, K and N corn studies across Virginia coastal plain soils to determine fertilizer effects on corn plant parameters [(most mature leaf (V6), corn ear leaf (R1), and grain (R6)]. Poultry litter P treatments, averaged over rate, recorded highest yield in both years. At eight of nine field sites, FB Bulk resulted in numerically or significantly higher Mehlich-1 concentrations than other P sources post-harvest. Although Mehlich-1 P increased, yield and plant parameters did not; which leads to the conclusion that PLA sources increased soil residual P that did not translate into immediate plant availability recorded within a growing season. Across plant efficacy parameters examined, PLA K is a comparable nutrient source and improved plant parameters when compared to control. Eighteen out of twenty-one plant parameters examined found similar ACU and urea effects on N concentrations. Therefore, ACU is a comparable N source to urea. When compared to industry fertilizer sources, we concluded that PLA is a slowly available P source, decreased P availability negatively affected early plant growth, K is a comparable nutrient source and improved plant parameters compared to control, and ACU effectively provided N to maintain sufficient corn growth. In conclusion, PLA co-products serve as a densified nutrient source that may provide plant available nutrients if processed to aid in nutrient distribution to grain producing areas. / Doctor of Philosophy / Poultry litter ash (PLA) is a co-product from manure-to-energy systems that originated in response to increased poultry litter (PL) volumes generated in concentrated poultry production regions. Investigating PLA as an alternative crop fertilizer is essential to balancing poultry and crop regional nutrient cycling in the Commonwealth of Virginia. As the expanding world population places pressure on the poultry industry to meet consumption demands, heightened PL production presents an obstacle to identify alternative uses for increased volumes. Currently, Virginia produces 44,683,904 broilers with PL produced predominately in the Shenandoah Valley and Eastern Shore. Likewise, a growing world population places pressure on crop production areas and subsequently finite natural resources used for fertilization vital to maintaining crop yields. Poultry litter ash, a co-product from manure-to-energy systems, is an alternative phosphorus (P) and potassium (K) source enhancing transportation logistics, repurposing PL nutrients, and offers dual purpose as a fertilizer and an energy source when compared to PL. In this dissertation, three PLA products [(fluidized bed bulk (FB Bulk), fluidized bed fly (FB Fly), and combustion Mix (CMix)], two manufactured co-products [(granulated poultry litter ash (GPLA), and ash coated urea (ACU)] were evaluated as P, K, and N source for corn (Zea Mays L.) production in comparison to industry fertilizers (PL, triple superphosphate (TSP), muriate of potash (KCL), and urea). Each of the following chapters provides a comprehensive examination of the following topics: elemental composition, P speciation, P and K solubility, improved functionality into granulized forms, and field testing designed to provide parameters to conclude PLA potential as an alternative P, K and N source. In the second chapter, PLA products were evaluated by total elemental analysis, backscatter-electron dispersive (BSED) microscopy, and X-ray absorption near edge structure (XANES) spectroscopy. Poultry litter ash elemental concentrations are highly variable and are comparatively higher than PL concentrations. Phosphorus structure and species identified Ca as the primary element controlling P structure and subsequent solubility. The third component of this dissertation is granulation trials investigating phosphoric acid effects on granulizing and increasing total and water soluble P. Our results identified 29% (14.5 g acid to 50 g PLA) phosphoric acid acidulation for desired granule size. The third dissertation component examines PLA solubility. The results demonstrated PLA decreased P water solubility when compared to industry fertilizer sources. Granulated poultry litter ash demonstrated improved P plant availability due to the granulation process. The final and fourth dissertation components investigated PLA sources under field conditions in separate P, K and N corn studies across Virginia coastal plain soils to determine fertilizer effects on corn plant parameters. Minority of plant parameters tested revealed P control yielded numerically higher P concentrations than PLA P sources tested. Poultry litter P treatments, averaged over rate, recorded highest yield in both years. At eight of nine field sites, FB Bulk resulted in numerically or significantly higher Mehlich-1 concentrations than other P sources post-harvest. Although Mehlich-1 P concentrations increased, yield and plant parameters did not; which leads to the conclusion that PLA sources increased soil residual P that did not translate into immediate plant availability recorded within a growing season. Across plant efficacy parameters examined, PLA K is a comparable nutrient source and improved plant parameters when compared to controls. The majority of plant parameters examined found similar ACU and urea effects on N concentrations. Therefore, ACU is a comparable N source to urea. When compared to industry fertilizer sources, field results concluded that PLA is a slowly available P source, decreased P availability negatively affected early plant growth, K is a comparable nutrient source and improve plant parameters compared to control, ACU effectively provides N to maintain sufficient corn growth. In conclusion, PLA co-products serve as a densified nutrient source that may provide plant available nutrients if processed to aid in nutrient distribution to grain producing areas.

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