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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.
71

Determinação macro e microelementos em adoçantes dietéticos por ICP OES / Determination macro and microelements in dietetic sweetener by ICP OES

Porfirio, Darilena Monteiro 16 June 2004 (has links)
Neste estudo foi determinado o conteúdo de metais em adoçantes dietéticos de mesa, consumidos por um número crescente de pessoas preocupadas em manter a forma física e restringir o nível calórico da dieta havendo ou não recomendação médica. Foram coletadas 26 amostras de adoçantes dietéticos distribuídos no mercado de São Paulo, em uma grande variedade de apresentações, produtos, composições e marcas. Como a composição é dependente da produção, esta análise é indispensável ao controle da qualidade e relevante à saúde do consumidor. A Espectrometria de Emissão Óptica com Fonte de Plasma Indutivamente Acoplado (ICP OES) com vista axial, mostrou-se adequada determinação dos macronutrientes Na, K, Ca, Mg e dos microelementos essenciais Fe, Cu, Zn, Cr, Mn e Se, dos potencialmente tóxicos AI, Ni, As, Cd e Pb em adoçantes sólidos e líquidos, atendendo as exigências da legislação brasileira. Assim, foi realizado um estudo comparativo entre as determinações utilizando as metodologias clássicas de pré-tratamento da amostra, como o resíduo de cinzas, a dissolução ácida com aquecimento por microondas com o procedimento sem tratamento prévio das amostras, visando facilitar a análise, uma vez que esta é a etapa que mais consome tempo e esforços. A determinação simultânea do espectro favoreceu a análise, uma vez que 74 comprimentos de onda puderam ser selecionados sem aumento no tempo ou no custo de análise, auxiliando na seleção de 36 linhas analíticas mais adequadas (livre de interferências) à determinação sem tratamento prévio da amostra. Nenhuma amostra de adoçante excedeu o valor recomendado para o somatório dos contaminantes inorgânicos (Aspartame < 10 &#181;g g-1 e Sacarina < 20 &#181;g g-1). No entanto, 6 marcas de adoçantes em pó excederam o valor limite da legislação para As (1,0 &#181;g g-1), excederam o valor para Cr total (0,1 &#181;g g-1) e 2 marcas de adoçante líquido excederam o valor para Ni (0,1 &#181;g g-1). Mostrando que os adoçantes em pó apresentam (&#8776;5 &#181;g g-1) níveis maiores de metais potencialmente tóxicos que os adoçantes líquidos (&#8776;2,O &#181;g mL-1). / The metal content in artificial sweetener usually consumed by a growing population concerned to keep body shape and to restrict the diet caloric content, by medical recommendation or not, was measured. The samples were 26 artificial sweeteners available at São Paulo\'s market, under different forms, and several suppliers, with various sweetener composition, and brands. Because the composition depends on manufacture factors, this analysis is mandatory for quality control and relevant for the user health. Inductively coupled plasma atomic emission with axial view has demonstrated to be an appropriated technique to determine the macronutrient content, such as Na, K, Ca, Mg and essential microelements such as Fe, Cu, Zn, Cr, Mn and Se, besides the potentially toxic elements such as AI, Ni, As, Cd and Pb in solid and liquid sweeteners in accordance with to the Brazilian regulation. It was also performed a comparative study of the sample preparation methodology, using classical sample pretreatment, such as burning to ashes, and acid dissolution with microwave heating and a procedure without prior sample treatment (dissolution and/or convenient dilution), aiming at facilitating the analysis of dietetic sweetener because this step is the most time and labor consuming. The analysis was simplified using the simultaneous spectra acquisition, once 74 wavelengths were selected without time or cost increase, and helping the identification of 36 appropriate analytical lines (free from interferences) to apply to the samples determination without prior treatment. None sweetener exceeded the recommended value of inorganic contaminant (for aspartame samples the value was below 10 &#181;g g-1 and for saccharine samples that was below 20 &#181;g g-1). However, 6 brands of artificial sweetener in powder exceeded the legislation limit value for As (1.0 &#181;g g-1), and other 7 brands exceeded the Cr recommended maximum value (0.1 &#181;g g-1). Other 2 brands of Iiquid sweetener exceeded the Ni recommended maximum value. Therefore, for ali samples, the artificial sweetener in powder presented higher levels of potentially toxic metais (&#8776;5&#181;g g-1) than those in a Iiquid presentation (&#8776;2.0 &#181;g mL-1).
72

Estudo de métodos para determinação total, fracionamento e análise de especiação elementar em fertilizantes base orgânica / Methods development for total elements determination, fractionating and speciation analysis on organic fertilizers

Albuquerque, Luiza Gimenes Rodrigues 08 December 2017 (has links)
A aplicação de fertilizantes aos solos é frequente devido à atual demanda mundial pela produção de alimentos e às projeções feitas para o futuro. Fertilizantes orgânicos têm sido uma opção amplamente explorada devido ao seu preço, possibilidade de reuso de resíduos agriculturais e urbanos, além do caráter sustentável. Podem ser provenientes de diversas origens como lodo de esgoto, estercos e restos de animais e vegetais submetidos a processos de compostagem. Neste trabalho, foi desenvolvido método para determinação elementar total em fertilizantes orgânicos, substratos e condicionadores de solo, e realizados estudos de fracionamento e análise de especiação em fertilizante orgânico. Assim, foi realizada a caracterização geral das amostras com fracionamento por tamanho de partícula, análises dos teores de C e N, difração de Raios-X e determinação elementar total. Para este último, foi desenvolvido método de digestão assistida por radiação micro-ondas, com análise por ICP OES. O procedimento foi otimizado para diferentes misturas ácidas, as quais foram avaliadas quanto aos erros relativos para diversos elementos em CRM de lodo de esgoto, utilizando PCA como ferramenta estatística. A mistura escolhida, constituída por 3 mL HNO3 + 1 mL HBF4 + 2 mL H2O, foi utilizada para digestão das amostras. Apenas a concentração total não traz informações a respeito da mobilidade e disponibilidade dos elementos, então estudos de fracionamento elementar também foram realizados. Na primeira abordagem foi executado fracionamento por tamanho de partícula, no qual foi observado que quanto menor o tamanho de partícula menor o teor de C e maior o teor de N, e maior a concentração de micronutrientes e contaminantes (Cr, Cu, Fe, Mn, Pb e Zn), indicando que estes elementos podem estar mais associados a frações com mais características inorgânicas e maior teor de humificação (dado pela razão C/N). A segunda abordagem refere-se à associação dos elementos com diferentes componentes da matriz seguindo o procedimento de extração sequencial do BCR e extrações em etapa única para avaliar a mobilidade, sendo os extratos analisados por ICP-MS. O elemento Cr mostrou baixa mobilidade e bioacessibilidade. Cu está associado, principalmente, à fração orgânica da matriz, porém também pouco móvel. Fe e Pb também apresentaram baixa mobilidade e associados, principalmente, a óxidos da amostra. Mn e Zn mostraram alta mobilidade, sendo também associados a matéria orgânica e aos óxidos. A análise de especiação dos extratos obtidos foi realizada por SEC-ICP-MS, de modo a investigar a associação dos elementos extraídos com ácidos húmicos e fúlvicos. Nenhum sinal de Cr estava relacionado com a matéria orgânica, enquanto que os elementos Cu, Fe e Pb mostraram associação com ácidos húmicos. Mn apresentou espécies associadas a ácidos fúlvicos, enquanto que o Zn, não está associado a espécies orgânicas. / Fertilizers are frequently applied to soils due to actual global food demand and its future projections. Organic fertilizers have been extensively employed due to its price, as a reuse possibility to agricultural and urban wastes, and its sustainable character. They can be prepared from various sources, such as sewage sludge, manure and plants and animal scraps, submitted to composting process. In this work, it was developed a total elements determination method, as well as fractionating studies and speciation analysis of organic fertilizer. Thus, organic fertilizer samples were generally characterized using particle size fractionating, C and N content analysis, X-Ray diffraction and total elements determination. To the last, it was developed a sample preparation method by microwave-assisted digestion and ICP OES analysis. Digestion procedure was optimized using various acid mixtures, which were evaluated due to its relative errors related to sewage sludge CRM values, using PCA as a statistical tool. The chosen acid mixture constituted of 3 mL HNO3 + 1 mL HBF4 + 2 mL H2O was applied to samples digestion and their total elements determination. As total concentration is not enough to predict elements mobility and bioavailability, fractionation studies were conducted. The first approach was the particle size fractionation, were it was observed that the smaller the particle size the higher the micronutrients and contaminants concentration (Cr, Cu, Fe, Mn and Zn), along with lower C contents and higher N contents, indicating that these elements are associated with inorganic fractions, or with highly humified compounds (due to the lower C/N ratio). A second approach refers to elements association with various matrix components, using BCR and single-step extraction procedures to investigate elements mobility and bioavailability, with ICP-MS analysis of extracts. Cr was poorly mobile and bioavailable. Cu was bound to organic fraction, but also poorly mobile and bioavailable. Fe and Pb were also weakly mobile, and were mostly associated with oxides on matrix. Mn and Zn were greatly mobile and bioavailable, and were also mainly associated with oxides on matrix. Speciation analysis of extract was performed by SEC-ICP-MS, investigating elements association with humic and fulvic acids on previous extracts. Cr could not be associated with any humic substance, as expected with previous extractions results. Cu, Fe and Pb had identifiable species associated with humic acids, while Mn was associated with fulvic acids. Zn, even though high mobile, was not associated with any organic species.
73

Estudo de métodos para determinação total, fracionamento e análise de especiação elementar em fertilizantes base orgânica / Methods development for total elements determination, fractionating and speciation analysis on organic fertilizers

Luiza Gimenes Rodrigues Albuquerque 08 December 2017 (has links)
A aplicação de fertilizantes aos solos é frequente devido à atual demanda mundial pela produção de alimentos e às projeções feitas para o futuro. Fertilizantes orgânicos têm sido uma opção amplamente explorada devido ao seu preço, possibilidade de reuso de resíduos agriculturais e urbanos, além do caráter sustentável. Podem ser provenientes de diversas origens como lodo de esgoto, estercos e restos de animais e vegetais submetidos a processos de compostagem. Neste trabalho, foi desenvolvido método para determinação elementar total em fertilizantes orgânicos, substratos e condicionadores de solo, e realizados estudos de fracionamento e análise de especiação em fertilizante orgânico. Assim, foi realizada a caracterização geral das amostras com fracionamento por tamanho de partícula, análises dos teores de C e N, difração de Raios-X e determinação elementar total. Para este último, foi desenvolvido método de digestão assistida por radiação micro-ondas, com análise por ICP OES. O procedimento foi otimizado para diferentes misturas ácidas, as quais foram avaliadas quanto aos erros relativos para diversos elementos em CRM de lodo de esgoto, utilizando PCA como ferramenta estatística. A mistura escolhida, constituída por 3 mL HNO3 + 1 mL HBF4 + 2 mL H2O, foi utilizada para digestão das amostras. Apenas a concentração total não traz informações a respeito da mobilidade e disponibilidade dos elementos, então estudos de fracionamento elementar também foram realizados. Na primeira abordagem foi executado fracionamento por tamanho de partícula, no qual foi observado que quanto menor o tamanho de partícula menor o teor de C e maior o teor de N, e maior a concentração de micronutrientes e contaminantes (Cr, Cu, Fe, Mn, Pb e Zn), indicando que estes elementos podem estar mais associados a frações com mais características inorgânicas e maior teor de humificação (dado pela razão C/N). A segunda abordagem refere-se à associação dos elementos com diferentes componentes da matriz seguindo o procedimento de extração sequencial do BCR e extrações em etapa única para avaliar a mobilidade, sendo os extratos analisados por ICP-MS. O elemento Cr mostrou baixa mobilidade e bioacessibilidade. Cu está associado, principalmente, à fração orgânica da matriz, porém também pouco móvel. Fe e Pb também apresentaram baixa mobilidade e associados, principalmente, a óxidos da amostra. Mn e Zn mostraram alta mobilidade, sendo também associados a matéria orgânica e aos óxidos. A análise de especiação dos extratos obtidos foi realizada por SEC-ICP-MS, de modo a investigar a associação dos elementos extraídos com ácidos húmicos e fúlvicos. Nenhum sinal de Cr estava relacionado com a matéria orgânica, enquanto que os elementos Cu, Fe e Pb mostraram associação com ácidos húmicos. Mn apresentou espécies associadas a ácidos fúlvicos, enquanto que o Zn, não está associado a espécies orgânicas. / Fertilizers are frequently applied to soils due to actual global food demand and its future projections. Organic fertilizers have been extensively employed due to its price, as a reuse possibility to agricultural and urban wastes, and its sustainable character. They can be prepared from various sources, such as sewage sludge, manure and plants and animal scraps, submitted to composting process. In this work, it was developed a total elements determination method, as well as fractionating studies and speciation analysis of organic fertilizer. Thus, organic fertilizer samples were generally characterized using particle size fractionating, C and N content analysis, X-Ray diffraction and total elements determination. To the last, it was developed a sample preparation method by microwave-assisted digestion and ICP OES analysis. Digestion procedure was optimized using various acid mixtures, which were evaluated due to its relative errors related to sewage sludge CRM values, using PCA as a statistical tool. The chosen acid mixture constituted of 3 mL HNO3 + 1 mL HBF4 + 2 mL H2O was applied to samples digestion and their total elements determination. As total concentration is not enough to predict elements mobility and bioavailability, fractionation studies were conducted. The first approach was the particle size fractionation, were it was observed that the smaller the particle size the higher the micronutrients and contaminants concentration (Cr, Cu, Fe, Mn and Zn), along with lower C contents and higher N contents, indicating that these elements are associated with inorganic fractions, or with highly humified compounds (due to the lower C/N ratio). A second approach refers to elements association with various matrix components, using BCR and single-step extraction procedures to investigate elements mobility and bioavailability, with ICP-MS analysis of extracts. Cr was poorly mobile and bioavailable. Cu was bound to organic fraction, but also poorly mobile and bioavailable. Fe and Pb were also weakly mobile, and were mostly associated with oxides on matrix. Mn and Zn were greatly mobile and bioavailable, and were also mainly associated with oxides on matrix. Speciation analysis of extract was performed by SEC-ICP-MS, investigating elements association with humic and fulvic acids on previous extracts. Cr could not be associated with any humic substance, as expected with previous extractions results. Cu, Fe and Pb had identifiable species associated with humic acids, while Mn was associated with fulvic acids. Zn, even though high mobile, was not associated with any organic species.
74

The heritability of facial morphology

Langstaff, Helen Katherine January 2016 (has links)
Facial recognition methodologies, widely used today in everything from automatic passport controls at airports to unlocking devices on mobile phones, has developed greatly in recent years. The methodologies vary from feature based landmark comparisons in 2D and 3D, utilising Principal Component Analysis (PCA) to surface-based Iterative Closest Point Algorithm (ICP) analysis and a wide variety of techniques in between. The aim of all facial recognition software (FCS) is to find or match a target face with a reference face of a known individual from an existing database. FCS, however, faces many challenges including temporal variations due to development/ageing and variations in facial expression. To determine any quantifiable heritability of facial morphology using this resource, one has to look for faces with enough demonstrable similarities to predict a possible genetic link, instead of the ordinary matching of the same individual’s face in different instances. With the exception of identical twins, this means the introduction of many more variables into the equation of how to relate faces to each other. Variation due to both developmental and degenerative aging becomes a much greater issue than in previous matching situations, especially when comparing parents with children. Additionally, sexual dimorphism is encountered with cross gender relationships, for example, between mothers and sons. Non-inherited variables are also encountered such as BMI, facial disfigurement and the effects of dental work and tooth loss. For this study a Trimmed Iterative Closest Point Algorithm (TrICP) was applied to three-dimensional surfaces scans, created using a white light scanner and Flexscan 3D, of the faces of 41 families consisting of 139 individuals. The TrICP algorithm produced 7176 Mesh-to-mesh Values (MMV) for each of seven sections of the face (Whole face, Eyes, Nose, Mouth, Eyes-Nose, Eyes-Nose-Mouth, and Eyes-Nose- Mouth-Chin). Receiver Operated Characteristic (ROC) analysis was then conducted for each of the seven sections of the face within 11 predetermined categories of relationship, in order to assess the utility of the method for predicting familial relationships (sensitivity/specificity). Additionally, the MMVs of three single features, (eyes, nose and mouth) were combined to form four combination areas which were analysed within the same 11 relationship categories. Overall the relationship between sisters showed the most similarity across all areas of the face with the clear exception of the mouth. Where female to female comparison was conducted the mouth consistently negatively affected the results. The father-daughter relationship showed the least similarity overall and was only significant for three of the 11 portions of the face. In general, the combination of three single features achieved greater accuracy as shown by Areas Under the Curve (AUC) than all other portions of the face and single features were less predictive than the face as a whole.
75

METODI CHIMICI PER IL RICONOSCIMENTO DELL'ORIGINE GEOGRAFICA DEGLI ALIMENTI / Chemical Methods for Foods Geographic Identification

SPALLA, STEFANO 31 January 2008 (has links)
Il presente studio affronta il tema della rintracciabilità alimentare di prodotti agroalimentari, analizzando il caso del pomodoro da industria, cercando di trovare degli indicatori chimici (markers) che siano in grado di discriminare prodotti provenienti da aree geografiche differenti. Viene quindi affrontato il tema della tipicità che consiste nel legame esistente tra l'alimento e il territorio nel quale viene prodotto. I parametri chimici che vengono indagati sono elementi appartenenti al gruppo delle terre rare (o serie dei lantanidi) e dei rapporti isotopici degli elementi pesanti quali lo Stronzio. La determinazione analitica delle terre rare nel pomodoro è stata effettuata con ICP-MS e HR-ICP-MS (Inductivity Coupled Plasma Mass Spectrometry, Hight Resolution Inductivity Coupled Plasma Mass Spectrometry). I rapporti isotopici dello Stronzio sono stati determinati con la tecnica TIMS (Thermal-Ionization Mass Spectroscopy) Le tecniche analitiche utilizzate hanno permesso di determinare con precisione e accuratezza tutti gli elementi appartenenti al gruppo delle terre rare nei comparti della pianta di pomodoro e nel terreno. La misura dei rapporti isotopici dello stronzio ha permesso di discriminare prodotti provenienti da aree geografiche differenti. / Food traceability systems have a broader scope and aim to document the history of a product along the entire production chain from primary raw materials to the final consumable product. the present work has looked at ways of detecting rare earth and strontium isotope abundance ratios. It is fundamental to have knowledge of the REE concentrations of the soil where the plants are grown and the distribution of the REEs in the different parts of the plants: roots, stems, leaves, and berries. Tomato is one of the most widely grown vegetables in the world. The analytical procedure, using inductively coupled mass spectrometry (ICP-MS) and HR-ICP-MS proved to be suitable for the determination of REEs in plants and soil, and was validated using certified samples. Strontium isotope ratio is an important parameter allowing the discrimination of foods coming from different geographical origins. Very high precision is usually reached with Thermal Ionization Mass Spectrometer (TIMS). The analytical techniques have permitted to determine all REEs elements in compartments of tomato plants. The described method point out the measurement of the 87Sr/86Sr ratio as a very important parameter for the discrimination of tomato from different geographical origins, even if the present experimental work treating a limited number of samples have to be considered as a “first step”.
76

Development of Lanthanide-tagged Substrates Towards the Detection of Proteases by Inductively Coupled Plasma-mass Spectrometry (ICP-MS)

Lathia, Urja 04 March 2010 (has links)
Rapid, sensitive and quantitative assays for proteases are of great significance for drug development and in diagnosis of diseases. Herein, we describe work towards a novel assay for the multiplexed detection of proteases using ICP-MS. Protease substrates were synthesized containing a diethylenetriaminepentaaceticacid(DTPA) ligand to chelate lanthanide metal ions at the N-terminus, providing a distinct tag for each substrate. A biotin label was appended to the C-terminus allowing separation of uncleaved peptide from the digestion. The enzymatic activities can then be determined by detecting the lanthanide signal of the peptide cleavage products by ICP-MS. Substrates synthesized include DTPA-Gln-Val-Tyr-Gly-Nle-Nle-Lys(biotin)-amide, DTPA-Asp-Gln-Val-Asp-Gly-Lys(biotin)-amide and DTPA-Gly-Pro-Gln-Gly-Leu-Glu-Ala-Lys-Lys(biotin)-amide for calpain-1, caspase-3 and MMP-9 They were loaded with terbium, holmium and praseodymium respectively. As a proof-of-concept, α-chymotrypsin assays were carried out using DTPA-Asp-Leu-Leu-Val-Tyr-Asp-Lys(Biotin) loaded with lutetium, as a substrate. Calpain-1 assays were also performed. Parallel assays with commercially available fluorogenic substrates for both the enzymes were performed for comparison.
77

Development of Lanthanide-tagged Substrates Towards the Detection of Proteases by Inductively Coupled Plasma-mass Spectrometry (ICP-MS)

Lathia, Urja 04 March 2010 (has links)
Rapid, sensitive and quantitative assays for proteases are of great significance for drug development and in diagnosis of diseases. Herein, we describe work towards a novel assay for the multiplexed detection of proteases using ICP-MS. Protease substrates were synthesized containing a diethylenetriaminepentaaceticacid(DTPA) ligand to chelate lanthanide metal ions at the N-terminus, providing a distinct tag for each substrate. A biotin label was appended to the C-terminus allowing separation of uncleaved peptide from the digestion. The enzymatic activities can then be determined by detecting the lanthanide signal of the peptide cleavage products by ICP-MS. Substrates synthesized include DTPA-Gln-Val-Tyr-Gly-Nle-Nle-Lys(biotin)-amide, DTPA-Asp-Gln-Val-Asp-Gly-Lys(biotin)-amide and DTPA-Gly-Pro-Gln-Gly-Leu-Glu-Ala-Lys-Lys(biotin)-amide for calpain-1, caspase-3 and MMP-9 They were loaded with terbium, holmium and praseodymium respectively. As a proof-of-concept, α-chymotrypsin assays were carried out using DTPA-Asp-Leu-Leu-Val-Tyr-Asp-Lys(Biotin) loaded with lutetium, as a substrate. Calpain-1 assays were also performed. Parallel assays with commercially available fluorogenic substrates for both the enzymes were performed for comparison.
78

none

Hsiao, Po-kai 20 July 2010 (has links)
none
79

Study on the influence of twice deposited mask layer of nano-structure

Liu, Chiao-yun 31 August 2010 (has links)
FIB is currently the economic methods to produce nano-structure below 100nm. In the past, FIB manufactures nano-structure patterns also unsatisfactory. In this study, the influence of twice deposited mask layer on the aspect ratio of nano-structure and verticality of side wall contour was discussed. The single mask layer is used for pattern transfer. Pattern distortion may occur during etching due to several factors like improper parameter setting, limitation of machine table, etc. The most common situations are aciculate and salient shape on the top and angle of slope which is too big to be vertical. In order to improve above-mentioned situations, a mask layer of multi-deposition was designed to protect the side wall so that it could retard etching. In addition to modifying verticality of side wall, the aspect ratio could be raised indirectly because the second deposition had reduced the interval between patterns. In the aspect of using machine table, the first mask layer, chromium, which was deposited by the sputtering machine. And the etching pattern was directly written on the first mask layer by focused ion beam. The silicon was uncovered at etched place, and then the second mask layer, silica (SiO2), which was deposited by the sputtering machine. The surface contour was directly covered with silica layer. Right after that, the top and bottom of silica were removed through vertical etching by inductively coupled plasma machine. The silica on the side wall of structure was retained to protect the side wall and raise aspect ratio. Eventually, the silicon was etched by the same way of inductively coupled plasma machine that it was researched on the difference in etching gas. And there was a comparison between chlorine and fluorine gases. After optimizing parameters, the nano-structure was made under 100nm.
80

Identification and Quantification of selenium-containing compound in dietary supplement and arsenic-containing compound in seaweed by HPLC-ICP-MS and HPLC-ESI-MS

Hsieh, Yu-Jhe 20 July 2011 (has links)
none

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