Di-2-piridil cetona saliciloilhidrazona (DPKSH) é uma hidrazona que forma compostos de coordenação com diversos íons metálicos. DPKSH adsorve facilmente em superficies de vidro e pode ser determinado por espectrofotometria. Estudos de adsorção do DPKSH em matrizes de sílica-gel foram efetuados em pHap 1 e 4,7 e meio 3% de etanol (v/v), a (25±1) °C. Massas conhecidas de sílica-gel foram colocadas em contato com soluções de DPKSH em concentrações conhecidas, sob agitação durante certo intervalo de tempo. A concentração de DPKSH adsorvida foi calculada considerando-se a diferença entre a concentração inicial e a concentração residual na solução sobrenadante, ambas obtidas a partir de medidas de absorbância. Estudo cinético permitiu encontrar o tempo adequado de contato sílica/DPKSH para adsorção máxima. Diferentes modelos de isotermas foram aplicados aos dados experimentais. Titulações condutométricas permitiram caracterizar as propriedades ácidas/básicas da sílica e da sílica modificada. Fez-se também um estudo preliminar sobre a retenção de íons Cu(II) na superficie de sílica-gel modificada com DPKSH. / Di-2-pyridyl ketone salicyloy1hydrazone (DPKSH) is a hydrazone that gives sensitive reactions with most of metal ions forming coulored chelates. DPKSH solutions present a visible adsorption onto glass when stored in glass bottles and can be determined by spectrophotometry. The adsorption of DPKSH onto silica gel has been investigated, at (25±l) °C and pHap 1 and 4.7 at aqueous solution containing 3%(v/v) ethanol. Masses well-known of silica gel were placed in contact with known concentration DPKSH solutions, under agitation during certain intervals of time. The quantity of DPKSH adsorbed was calculated considering the difference between the initial DPKSH concentration and the residual one in the sobrenadant solution after achieved the equilibrium, both obtained from absorbance measurements. Kinetic studies allowed to find the optimal rime for the contact silica DPKSH in order to obtain the maximum adsorption. Different models of isotherms were applied to the experimental data. Condutometric titrations led to acid/basic characteristics of silica and modified silica. A preliminary study of Cu(II) ions retention into silica gel surface modified with DPKSH was carried out.

As tetraciclinas são compostos antibacterianos utilizados no gado leiteiro para tratamento de doenças infecciosas, como a mastite e também como aditivos em ração animal para melhorar a conversão alimentar. O uso das tetraciclinas pode resultar na presença de resíduos destes fármacos no leite, principalmente se não forem utilizados de acordo com as indicações e se não for respeitado o período mínimo de eliminação dos antibióticos pelo leite. A presença de resíduos de antibióticos no leite interfere no processo industrial de derivados, inibindo fermentos láticos usados na produção de iogurtes e queijos, o que, consequentemente, causa sérios prejuízos econômicos. Resíduos de antibióticos no leite de consumo podem representar riscos à saúde humana, podendo causar reações alérgicas em indivíduos sensíveis, efeitos adversos à flora intestinal humana prejudicando sua ação protetora local, além de propiciar a seleção de populações de bactérias resistentes. O Food and Drug Administration (FDA) estabelece limite máximo de resíduo (LMR) para as tetraciclinas em leite de 300ppb, enquanto a Joint FAO/WHO Expert Committee on Food Additives (JECFA) e o Plano Nacional de Controle de Resíduos Biológicos em Produtos de Origem Animal do Ministério da Agricultura brasileiro estabelecem LMR de 100 ppb·. O objetivo deste estudo foi validar um método multirresíduo para determinação de oxitetraciclina, tetraciclina, clortetraciclina e doxiciclina em leite por extração com desproteinização acídica e identificação e quantificação por cromatografia líquida de alta eficiência acoplada ao detector de arranjo de diodos. O método apresentou limite de detecção e quantificação, respectivamente de 37,5 e 50ng/ml, lineridade de 50-1600ng/ml e coeficientes de determinação de 0,9996; 0,9994; 0,9996 e 0,9996 para oxitetraciclina, tetraciclina, clortetraciclina e doxiciclina, respectivamente, recuperação entre 66,6 e 89,6%, com precisão e exatidão adequadas. Para avaliar a aplicabilidade do método foram analisadas 231 amostras de leite in natura, obtidas em um laticínio, em três coletas consecutivas e mensais. O índice de amostras positivas para oxitetraciclina manteve-se superior a 11%. Na primeira coleta 19% das amostras foram positivas para oxitetraciclina, na segunda coleta 11,5% e na terceira coleta 12,2%. Os resultados indicam que o método validado mostrou-se apropriado para monitorização da qualidade do leite. / The tetracyclines are antimicrobial agent used in dairy cattle to treat infection diseases, as mastitis and also as additives in animal food to produce improvements in feed efficiency and growth. The use of tetracyclines can result in presence of residue of these antimicrobials in the milk, especially if they are not used according to the label directions and if the minimum period of their elimination is not respected. The presence of antibiotic residues in the milk interferes in the dairy industrial process diminishing starter culture growth used in the yogurt and cheese production, what causes strong economic loss. Antibiotic residue in the consumer milk can represent risk to the human health, being possible to cause allergic reactions in sensitives human beans, disorders of the intestinal flora damaging its local protection action besides to provide antibiotic resistance development. The Food and Drug Administration (FDA) establishes maximum residue limit (MRL) of 300ppb for tetracycline in milk while the Joint FAO/WHO Expert Committee on Food Additives (JECFA) and the National Plan of Biological Residue Control in animal products of Brazilian Agricultural Bureau establishe MRL of 100ppb. The objective of this study was to validate the multiresidue method to determine the oxytetracycline, tetracycline, chlortetracycline and doxycycline in milk by acidic desproteinization extraction and to identify and quantify by high performance liquid chromatography with photo-diode array detector. The method presented detection limit and quantification limit respectively of 37,5 and 50 ng/ml, linearity from 50 to 1600ng/ml and correlation coefficient of 0,9996, 0,9994, 0,9996 and 0,9996 to the oxytetracycline, tetracycline, chlortetracycline and doxycycline respectively; recovery between 66,6 and 89,2%, with good precisions and accurancy. There were analyzed 231 samples of milk in nature obtained in a dairy industrie, in three stages consecutive and monthly. The indices of positive samples for oxytetacycline remained superior to 11%. In the first stage 19% of the samples were positive for oxytetracycline, in the second stage 11,5% and in the third stage 12,2%. The results show that the validated method is appropriated for the monitoring the quality of the milk.

O mel de abelhas é um produto biológico muito complexo, cuja composição varia notavelmente em função da flora visitada pelas abelhas e das condições climáticas e edáficas da região onde foi produzido. Este trabalho teve como objetivos confrontar os resultados das análises físico-químicas entre as amostras de méis produzidos em diferentes localidades do Brasil por Apis mellifera e por Meliponíneos e investigar se o mel produzido por essas abelhas nas suas diferentes regiões de origem apresenta níveis toleráveis de contaminantes inorgânicos. Para tanto, foram avaliadas 56 amostras de méis de A. mellifera e 56 amostras de méis de Meliponíneos dos Estados da Bahia, Minas Gerais, Mato Grosso do Sul, Paraíba, Piauí, Paraná, Santa Catarina e São Paulo, em relação aos seguintes parâmetros: umidade, atividade de água, viscosidade, pH, acidez livre, índice de formol, açúcares redutores, sacarose aparente, teor de cinzas, cor, condutividade elétrica, hidroximetilfurfural, atividade diastásica e metais (Hg+2, Zn+2, Cd+2, Pb+2 e Cu+2). Foi utilizada a técnica de Voltametria de Redissolução Anódica de Pulso Diferencial (DPASV) para quantificar os metais, e métodos convencionais e próprios para mel nas demais análises. Os resultados mostraram que a legislação atual, referente ao mel de A. mellifera, não é adequada para os parâmetros açúcares redutores, umidade e atividade diastásica de algumas espécies de Meliponíneos. Pôdese concluir que as espécies A. mellifera, Tetragonisca angustula, Melipona quadrifasciata, M. scutellaris, M. mandacaia, M. fasciculata, M. subnitida produzem méis com características físico-químicas diferentes e próprias de cada uma delas. Para todas as espécies avaliadas, os níveis de contaminantes inorgânicos encontrados nos méis foram toleráveis à saúde humana. Os méis produzidos por A. mellifera apresentaram variações nas características físico-químicas: atividade de água, viscosidade, acidez livre, índice de formol, açúcares redutores, condutividade elétrica, hidroximetilfurfural, atividade diastásica e o mineral zinco, em função dos diferentes locais onde foram produzidos. / The honeybee is a very complex biological product, whose composition varies markedly depending on the plant visited by the bees and the weather and soil conditions in the region where it was produced. This study aimed to compare the results of physicochemical analysis between the samples of honey produced in different locations in Brazil by Apis mellifera and Meliponid and to investigate whether honey produced by these bees, in different regions of origin, has tolerable levels of inorganic contaminants. To this end, we evaluated 56 samples of honey from A. mellifera and 56 samples of honey from Meliponid from the states of Bahia, Minas Gerais, Mato Grosso do Sul, Paraíba, Piauí, Paraná, Santa Catarina and São Paulo, for the following parameters: moisture content, water activity, viscosity, pH, free acidity, formol index, reducing sugars, apparent sucrose, ash content, color, electrical conductivity, hydroxymethylfurfural, diastase activity and metals (Hg+2, Zn+2, Cd+2, Pb+2 and Cu+2). Differential Pulse Anodic Stripping Voltammetry (DPASV) technique was used to quantify the metals, and, to the other analysis, conventional and suitable methods for honey were used. The results showed that the current legislation, referring to the honey of A. mellifera, is not appropriate for the parameters reducing sugars, moisture content and diastase activity of some species of Meliponid. It was concluded that the species A. mellifera, Tetragonisca angustula, Melipona quadrifasciata, M. scutellaris, M. mandacaia, M. fasciculata, M. subnitida produce honeys with different and specific physico-chemical characteristics. For all species studied, levels of inorganic contaminants found in honey were tolerable to human health. The honey produced by A. mellifera showed variations in physicochemical water activity, viscosity, free acidity, formol index, reducing sugars, electrical conductivity, hydroxymethylfurfural, diastase activity and the mineral zinc, depending on the different locations where they were produced.

Made available in DSpace on 2016-04-28T14:58:38Z (GMT). No. of bitstreams: 1 2001 - Claudia de Souza.pdf: 251955 bytes, checksum: b69d1d8a6093e5f84e1aeb625a7a998e (MD5) Previous issue date: 2001-02-16 / The objective of this research was to study the relationship between non-conventional, or agroecological coffee production management and the quality of the product. This was a demand of the Association of Small Coffee Producers of Po?o Fundo, Minas Gerais State, Brazil. Six small farms were studied between the months of May and September 1996. Surveys were applied to farmers to find out about the main agricultural practices used by their coffee production. The following chemical and qualitative analyses were performed on the coffee drink from the studied areas: phenolics, poliphenoloxidases, color index and titrable acidity. Macro and micronutrients contents on coffee leaves and soil nutrient levels were evaluated. In addition, visual analysis was also carried out to assess the symptoms of leaf miner caused by Leucoptera coffeella Gu?rin-M?neville & Perrottet, 1842 Lepdoptera: Lyonetiidae (bicho-mineiro) and syndrome of caused by Phoma sp. The farms were typified according to the level of use of practices considered as agroecological or conventional. The results were analyzed by principal component analyses followed by cluster analyses. Two out of the six farms that used the most agroecological practices, formed a distinct group characterized by coffee drink of better quality. However, regarding soil fertility variables, a cluster was formed due to soil acidity. One of the farms using the most agroecological practices, clustered by itself for its lower soil pH, higher exchangeable Al+3 levels and lower Ca+2 levels. The variables related to leaf nutrient levels, were responsible for clustering farms with higher levels of agroecological practices. In this case, clustering took place by the lower levels of leaf S and B and higher levels of Ca and Mg. Also a trend of lower levels of leaf micronutrients on those properties was found. As a recommendation, more attention should be given to soil acidity and micronutrient replacement on those farms. Also, the agroecological practices used by the farms should be studied further since they resulted in better coffee quality. / O objetivo desse estudo foi estudar a rela??o entre o manejo n?o convencional, ou agroecol? gico e a qualidade da bebida de caf?, como resposta a demanda apresentada pela Associa??o de Pequenos Produtores de Po?o Fundo. Seis propriedades foram estudadas entre os meses de maio e setembro de 1996. Entrevistas semi-estruturadas foram aplicadas com objetivo de se conhecer o manejo efetuado nas lavouras de caf?. Foram realizadas an?lises qu?micas qualitativas da bebida do caf? nas ?reas amostradas quanto aos fen?licos totais, polifenoloxidase, ?ndice de cor e acidez titul?vel. Levantamento nutricional das propriedades tamb?m foram efetuados tanto no que diz respeito a an?lises foliares quanto de fertilidade do solo. Al?m disso, foi realizada a observa??o visual quanto ? incid?ncia de sintomas relacionados ? Leucoptera coffeella Gu?rin-M?neville & Perrottet, 1842 Lepdoptera: Lyonetiidae (bicho- mineiro) e da s?ndrome da seca de ponteiros, associados a Phoma sp. As propriedades foram tipificadas quanto ao grau de utiliza??o de pr?ticas consideradas como agroecol?gicas ou convencionais . Os resultados foram analisados por meio de an?lise de componentes principais, seguida de an?lise de conglomerados (clusters) indicaram que as duas propriedades que utilizavam o maior n?mero de pr?ticas agroecol?gicas formaram um grupo distinto, caracterizado por uma qualidade de bebida considerada superior ?s demais. Quanto ?s vari?veis de fertilidade do solo, observou-se um agrupamento relacionando ? acidez do solo; uma propriedade que utilizando o maior n?mero de pr?ticas agroecol?gicas se diferenciou das demais por formar um cluster na regi?o de baixa acidez no solo (pH mais elevado e menor teor de Al troc?vel), bem como menor teor de Ca. As vari?veis de teores foliares tamb?m separaram as duas propriedades de maior uso de pr?ticas agroecol?gicas das demais. Neste caso, a separa??o se deu devido aos menores teores de S e B e uma tend?ncia de maiores teores de Ca e Mg foliares. Os resultados indicam que, apesar do baixo uso de insumos industrializados, a boa qualidade da bebida foi mantida nas duas propriedades de maior grau de uso de pr?ticas agroecol?gicas , embora a acidez do solo estivesse alta (em uma das duas propriedades). H? uma tend?ncia de teores de alguns micronutrientes mais baixos nos cafeeiros dessas propriedades. Assim, como recomenda??es preliminares visando ? melhoria dos cafezais da regi?o estudada, uma maior aten??o deve ser dada aos aspectos de acidez do solo e restitui??o de S e B como tamb?m, as pr?ticas usadas na propriedade considerada como de maior uso de pr?ticas agroecol?gicas devem ser mais estudadas, pois, segundo este estudo relacionam-se a uma melhor qualidade de bebida de caf?.

Scandate cathode under various processing stages: scandia nano-powder, tungsten scandia mix powder, sintered and impregnated pellets, were characterized with techniques that included electron microscopy, EDS, XPS, and work function measurements. The size and shape uniformity of nano-scale scandia particles changed from round to square and polyhedron during heat treatment. Reduction in size and improvement in size uniformity as heat treating temperature increased were observed. When determining the highest Sc coverage, three assessment methods were used and with their combined results, it was concluded that set VII had the highest Sc at%. In the sintered pellets, it was observed with SEM that more initial scandia coverage in the mix powder sets corresponded to a larger number of scandia particles distributed over the tungsten surface. The structure of the cross section made on pellet surface was porous which was expected in any functional cathode. Kelvin probe measurements revealed that work function values of sintered pellets were similar and decreased by approximately 0.6 eV after the impregnation. A cross section on the impregnated pellet surface revealed that the pores that existed in sintered pellets were gone and filled with impregnated materials that emerged to the surface during impregnation.

No description available.

Es wird die Entwicklung der Röntgenspektralanalyse und die Entdeckung der Röntgenfluoreszenzanalyse durch Georg von Hevesy und Richard Glocker mit ihren Assistenten in Freiburg i. Br. und in Stuttgart 1928 beschrieben. / The development of the x-ray chemical analysis and the discovery of the x-ray fluorescence analysis by Georg de Hevesy and Richard Glocker with their assistants in Freiburg i. Br. and in Stuttgard 1928 is described.

Characterization of phosphorus (P) in organic amendments is essential for environmentally sustainable fertilization of agricultural soils. The sequential chemical extraction (SCE) technique commonly used for P characterization does not provide any direct molecular information about P species. Studies were conducted to characterize P species in organic amendments and amended soils at a molecular level. The SCE was used to fractionate P in organic amendments including biosolids, hog, dairy and beef cattle manures, and poultry litter. The extracts were analyzed for total P and P species using inductively coupled plasma - optical emission spectroscopy (ICP-OES) and solution 31P nuclear magnetic resonance (NMR) spectroscopy, respectively. The relative proportions of P species in intact organic amendments and residues after each extraction, and calcareous soils amended with organic amendments and monoammonium phosphate (MAP) were estimated using the synchrotron-based P 1s X-ray absorption near edge structure (XANES) spectroscopy. The solution 31P NMR provided a detailed characterization of organic P in the non-labile NaOH and HCl fractions of organic amendments, but was limited in characterizing the labile fractions of most of these organic amendments due to their proneness to alkaline hydrolysis. The XANES analysis, however, identified the actual chemical species constituting the labile P that was only characterized as inorganic P or orthophosphates by sequential extraction and solution 31P NMR. In the amended Vertisolic and Chernozemic soils, XANES analysis estimated ‘soluble and adsorbed P’ as the dominant P species. For the Vertisolic soil, both the unamended and soil amended with biosolids and MAP contained hydroxyapatite (HAP). In addition, soil amended with biosolids, hog and dairy manures contained β-tricalcium phosphate (TRICAL), a more soluble CaP than HAP. TRICAL was found in all amended soils except in that amended with hog manure, while HAP was present in appreciable amount only in the control. Overall, the combination of techniques used in these studies improved the understanding of P species in organic amendments and amended soils that would not have been possible with any individual technique. Technological advances in P analysis should therefore be combined with conventional chemical extraction techniques to determine the fate of P in the environment.

Characterization of phosphorus (P) in organic amendments is essential for environmentally sustainable fertilization of agricultural soils. The sequential chemical extraction (SCE) technique commonly used for P characterization does not provide any direct molecular information about P species. Studies were conducted to characterize P species in organic amendments and amended soils at a molecular level. The SCE was used to fractionate P in organic amendments including biosolids, hog, dairy and beef cattle manures, and poultry litter. The extracts were analyzed for total P and P species using inductively coupled plasma - optical emission spectroscopy (ICP-OES) and solution 31P nuclear magnetic resonance (NMR) spectroscopy, respectively. The relative proportions of P species in intact organic amendments and residues after each extraction, and calcareous soils amended with organic amendments and monoammonium phosphate (MAP) were estimated using the synchrotron-based P 1s X-ray absorption near edge structure (XANES) spectroscopy. The solution 31P NMR provided a detailed characterization of organic P in the non-labile NaOH and HCl fractions of organic amendments, but was limited in characterizing the labile fractions of most of these organic amendments due to their proneness to alkaline hydrolysis. The XANES analysis, however, identified the actual chemical species constituting the labile P that was only characterized as inorganic P or orthophosphates by sequential extraction and solution 31P NMR. In the amended Vertisolic and Chernozemic soils, XANES analysis estimated ‘soluble and adsorbed P’ as the dominant P species. For the Vertisolic soil, both the unamended and soil amended with biosolids and MAP contained hydroxyapatite (HAP). In addition, soil amended with biosolids, hog and dairy manures contained β-tricalcium phosphate (TRICAL), a more soluble CaP than HAP. TRICAL was found in all amended soils except in that amended with hog manure, while HAP was present in appreciable amount only in the control. Overall, the combination of techniques used in these studies improved the understanding of P species in organic amendments and amended soils that would not have been possible with any individual technique. Technological advances in P analysis should therefore be combined with conventional chemical extraction techniques to determine the fate of P in the environment.

The study of two pharmaceutically active systems that each display polymorphism has provided a platform upon which to develop and apply solid-state NMR techniques in order to increase the understanding of the solid-state structure of small organic molecules. The multidisciplinary approach adopted has highlighted the advantages of solid-state NMR as a non-invasive probe of molecular conformation and crystallographic packing.Carbon-13 CP/MAS spectra of the two polymorphs of BRL55834 - a fluorinated benzopyran derivative - immediately suggest the presence of one and three molecules in the asymmetric unit. A lack of crystals suitable for single-crystal XRD has catalysed the application of high-power powder X-ray diffraction studies. Subsequent attempts at structure solution using Genetic Algorithm techniques are showing preliminary results that reinforce predictions made from solid-state NMR. Novel triple-channel techniques have aided assignment and resolution of die complex (^13)C CP/MAS spectra. Enrichment of the (^15)N site appears to have resulted in the formation of a new polymorph. Techniques for the analysis of detection Units have been developed using solid-state Raman spectroscopy and chemometric analysis. The aminoxanthine derivative, BRL61063, provides interesting inter-form variations in molecular disorder, solid-state packing, and hydrogen bonding. A previously basic understanding of the single-crystal XRD data has been further evaluated through the course of this Ph.D. and solid-state NMR spectral editing techniques have been developed and applied to identify these phenomena. Recrystallisation studies have produced two samples that appear to exist in an intermediate state between the rigid and mobile structural limits. Temperature variation causes interesting changes in the relaxation characteristics and natural abundance (^15)N and (^13)C CP/MAS spectra. Residual dipolar coupling effects vary in their manifestation within the (^13)C CP/MAS spectra of the polymorphic systems studied and comparison with the literature yields important information regarding molecular conformation. Nitrogen-15 enrichment and operation at higher magnetic field have been applied to reduce these second order effects. Finally, some distance has been travelled along the path towards decoupling (^14)N. Future development of this technique holds potential for resolution enhancement in the solid state spectra of most naturally occurring, nitrogen-containing molecules.