Sample records for ketones
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Sample records 1 - 20 shown. Select sample records:



1

Reduções enantiosseletivas de cetonas utilizando-se fermento de pão/ Enantioselective reductions of ketones using baker's yeast

Rodrigues, José Augusto R.; Moran, Paulo José S.
2001-12-01

Resumo em inglês Baker's yeast has been successful employed to reduce carbonyl compounds carrying appropriated substituents at distances under the electronic influence of the keto group. High yields and enantiomeric excess (ee) were obtained with 1,2-alkanedione, 1,2-alkanedione (2-O-methyloxime) and 1,3-alkanedione. Potential chiral building blocks were obtained and applied for stereoselective synthesis of valuable compounds. Evidence for a free radical chain process was obtained with baker's yeast reduction of a-iodoacetophenone using radical inhibitors.

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2

Controle genético da concentração de 2-Tridecanona e de 2-Undecanona em cruzamentos interespecíficos de tomateiro/ Genetic control of 2-Tridecanone and 2-Undecanone concentration in tomato interspecific cross

PEREIRA, NORMA ELIANE; LEAL, NILTON ROCHA; PEREIRA, MESSIAS GONZAGA
2000-01-01

Resumo em português Estudou-se o controle genético da concentração das metil-cetonas 2-tridecanona (2-TD) e 2-undecanona (2-UN) no cruzamento de Lycopersicon esculentum cv IPA-6 x L. hirsutum f. glabratum PI 134418. Para tal, as gerações parentais F1 e F2 foram avaliadas em experimento de casa de vegetação, sendo a quantificação das metil-cetonas foliares realizada por cromatografia gasosa com coluna capilar. Os resultados revelaram alta correlação (0,97; P > 0,001) entre as conce (mais) ntrações de 2-TD e 2-UN, possivelmente devido à ocorrência de efeitos pleiotrópicos ou de ligação gênica. O grau médio de dominância revelou a ocorrência de dominância parcial para as menores concentrações de 2-TD e 2-UN, cujas herdabilidades foram 0,75 e 0,78 respectivamente. A análise de média de gerações mostrou não haver adequação dos dados de concentração de 2-TD e 2-UN ao modelo aditivo-dominante, devido, possivelmente, a problemas de incongruidade ou a efeitos epistáticos. Resumo em inglês Genetic control of methyl-ketones 2-tridecanone (2-TD) and 2-undecanone (2-UN) concentration was studied in a cross of Lycopersicon esculentum cv IPA-6 x L. hirsutum f. glabratum PI 134418. The progenitors F1 and F2 generations were evalueted in a green house experiment, and the level of methyl-ketones in the leaves were determined by capilar gas chromatography. The results indicate that there is high correlations between 2-TD and 2-UN concentrations (0.97; P > 0.001), in (mais) dicating that pleiotropic or genic linkage effects may be occurring. The 2-TD and 2-UN showed complete dominance for low concentration and high heritability, 0.75 and 0.78, respectively. The generation means analysis showed that the results of 2-TD and 2-UN concentration can not be explained by the simple additive-dominant model, suggesting that the segregation distortion could be due to incongruity problems of interspecific crosses or epistatic gene action.

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3

Compostos voláteis dos frutos de maracujá (Passiflora edulis forma Flavicarpa) e de cajá (Spondias mombin L.) obtidos pela técnica de headspace dinâmico/ Volatile compounds in passion fruit (Passiflora edulis forma Flavicarpa) and yellow mombin (Spondias mombin L.) fruits obtained by dynamic headspace technique

Narain, Nerendra; Almeida, Juliana das Neves; Galvão, Mércia de Souza; Madruga, Marta Suely; Brito, Edy Souza de
2004-06-01

Resumo em português Entre as inúmeras frutas tropicais e subtropicais produzidas no Brasil, duas que se destacam do ponto de vista do aroma da polpa são maracujá amarelo (Passiflora edulis forma Flavicarpa) e cajá (Spondias mombin L.). Os voláteis da polpa destas frutas foram capturados pela técnica de headspace dinâmico e analisados no sistema de cromatografia gasosa de alta resolução e espectrometria de massa. Foram identificados 48 e 33 compostos voláteis na polpa de maracujá e (mais) cajá, respectivamente. Os compostos voláteis predominantes na polpa de maracujá pertenceram às classes de ésteres (59,24%), aldeídos (15,27%), cetonas (11,70%) e álcoois (6,56%), enquanto na polpa de cajá as principais classes de compostos foram de ésteres (48,76%), álcoois (21,69%), aldeídos (11,61%) e cetonas (4,19%). Outros compostos aromáticos característicos foram para maracujá: beta-ionona e linalol e para cajá: gama-octalactona e ácidos butírico e hexanóico. Resumo em inglês Among the numerous tropical and sub-tropical fruits produced in Brazil, two that attain relatively greater importance from the point of view of aroma of their pulp are yellow passion fruit (Passiflora edulis forma Flavicarpa) and yellow mombin (Spondias mombin L.). The volatile components in the pulp of these fruits were captured by dynamic headspace technique and were analyzed in a system of high-resolution gas chromatography and mass spectrometry. Forty-eight and thirty (mais) -one volatile compounds were identified in passion fruit and yellow mombin fruit pulp, respectively. The predominant volatile compounds in passion fruit pulp belonged to the classes of esters (59.24%), aldehydes (15.27%), ketones (11.70%) and alcohols (6.56%) while in the yellow mombin pulp, the principal classes of compounds were esters (48.76%), alcohols (21.69%). aldehydes (11.61%) and ketones (4.19%). The other characteristic aroma compounds for passion fruit were beta-ionone and linalool and for yellow mombin were gamma-octalactone, butanoic and hexanoic acids.

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4

Carne caprina de animais mestiços: estudos do perfil aromático/ Goat meat of "mestiço" animals: volatile profile analysis

Madruga, M. S.; Souza, J. G; Arruda, S. G. B.; Narain, Narendra
2003-12-01

Resumo em português Análises do perfil aromático da carne caprina cozida de animais mestiços foram realizadas utilizando-se animais castrados e inteiros, abatidos com idades de 175, 220, 265 e 310 dias. O perfil aromático da carne caprina foi constituído por 108 voláteis, sendo que 69 foram positivamente identificados e 39 parcialmente caracterizados utilizando-se análises de CG-EM. O perfil aromático da carne caprina foi formado por hidrocarbonetos alifáticos e alicíclicos, aldeí (mais) dos, compostos benzênicos, álcoois, cetonas, terpenóides, ésteres e compostos heterocíclicos sulfurados, hexadecanal, benzeno, heptano e octadecanal foram os voláteis que apresentaram os maiores índices de abundância relativa. Nas análises quantitativa e qualitativa observaram-se uma predominância de voláteis nos extratos de carne de caprinos castrados. O número total de voláteis e a abundância relativa das diferentes classes de compostos não foram claramente afetados pelo fator idade de abate. Resumo em inglês The volatile profile of cooked goat meat was analysed using meat from castrated and intact animals slaughtered at 175, 220, 265 and 310 days. A total of 108 volatiles was detected and from them 69 was identified and a further 39 were partially characterised by GC-MS. The volatile profile was composed by hydrocarbons aliphatic and alicyclic, aldehydes, benzenoid compounds, alcohols, ketones, terpenoids, esters and sulfur compounds. Hexadecanal, benzen, heptane and octadeca (mais) nal were among the volatiles with highest relative abundance. In both qualitative and quantitative analyses extracts from castrated meat had higher production of volatiles. The total number and the relative abundance of different classes of compounds seemed not to be cleared affected by slaughter age factor.

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5

Estudo fitoquímico e alelopático do extrato de caule de sucupira-branca (Pterodon emarginatus)/ Phytochemistry and allelophatic study of Pterodon emarginatus stem extract

Hernández-Terrones, M.G.; Morais, S.A.L.; Ferreira, S.; Santos, D.Q.; Nascimento, E.A.; Chang, R.
2007-12-01

Resumo em português A alelopatia é um dos fenômenos pouco estudados no Cerrado. Trata-se de uma ocorrência natural, resultante da liberação de substâncias capazes de estimular ou inibir o desenvolvimento de outras plantas. Objetivou-se neste trabalho avaliar a ação alelopática de extratos da sucupira-branca (Pterodon emarginatus) sobre a germinação e o desenvolvimento da raiz e parte aérea do capim-colonião (Panicum maximum). Bioensaios de germinação realizados em placas de Pe (mais) tri comprovaram que o extrato metanólico do tronco dessa planta, a 150 ppm, inibiu 83% do desenvolvimento da raiz, 75% da parte aérea e 30% da germinação de sementes de capim-colonião. Em casa de vegetação, os resultados de inibição foram de 83% para a parte aérea, 80% para a raiz e 63% para a germinação, mas somente na concentração de 400 ppm. Frações do extrato metanólico bruto obtidas por cromatografia de coluna cromatográfica não reproduziram os resultados de inibição obtidos inicialmente. A fração mais ativa (diclorometano/clorofórmio) foi analisada por CG/EM. Ela é constituída fundamentalmente por substâncias alifáticas de cadeia longa: fitol (13,5%), ácido oléico (12,8%), linoleiladato de metila (10,9%) e ácido palmítico (6,9%). Foram detectados, também, os compostos 1,2,4-trimetil e isopropilbenzenos (12,2%) e as cetonas isoméricas isopropenilmetilcetona e 3-penten-2-ona (7,3%). Três compostos desconhecidos também se destacaram: um de baixa massa molar (98 Da, 13,5%) e dois de massa molar elevada (13,6%). Resumo em inglês Allelopathy is one of the natural phenomena little studied in the cerrado. It is the result of the release of substances capable of stimulating or inhibiting the growth of other plants. The objective of this work was to evaluate the allelophatic action of the white sucupira (Pterodon emarginatus) stem extract on the germination and development of colonião grass (Panicum maximum) under germination, root and aerial part development of colonião grass (Panicum maximum) root (mais) and aerial part. Germination assays carried out in Petri dishes confirmed that the methanolic (200 ppm) extract inhibited the growth of hypocotyl (75%), root (83%), and germination (30%) of colonião grass. The greenhouse results obtained were: hypocotyl 83%, root 80% and germination 63%, but at a concentration of 400 ppm. Methanolic extract fractions did not reproduce the results cited above. The most active fraction (dichloromethane/chloroform) was analyzed by GC/MS. It contains mainly long-chain aliphatic compounds such as phytol (13.5%), oleic acid (12.8%), methyl linolelaidate (10.9%) and palmitic acid (6.9%); 1,2,4-trimethyl- and isopropenylbenzene (12.2%); two isomeric ketones (isopropenyl methyl and 3-penten-2-one) (7.3%) were also detected. Three unknown compounds were also important: one with a low molecular weight (98 Da, 13.5%) and two of high molecular weight (13.6%).

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6

Influência da Idade de Abate e da Castração nas Qualidades Físico-Químicas, Sensoriais e Aromáticas da Carne Caprina/ Castration and Slaughter Age Effects on Physical-Chemical, Sensorial and Aromatic Quality of Goat Meat

Madruga, Marta Suely; Narain, Narendra; Arruda, Silvana Gonçalves Brito de; Souza, Janete Gouveia; Costa, Roberto Germano; Beserra, Frederico José
2002-06-01

Resumo em português Grupos de caprinos mestiços castrados e inteiros foram abatidos com idades de 175, 220, 265 e 310 dias. Os efeitos da castração e idade de abate nas qualidades físico-químicas, sensoriais e aromáticos da carne caprina foi pesquisado. O efeito castração foi observado apenas para o conteúdo de cálcio, no entanto a idade de abate apresentou um efeito significativo nos teores de umidade, proteína, cálcio, ferro e pH. Os fatores idade de abate e castração não ap (mais) resentaram efeito significativo nos percentuais de fosfolipídeos porém, a idade de abate afetou os percentuais de colesterol. Caprinos castrados apresentaram maior percentual de ácidos graxos insaturados e, conseqüentemente, maior relação PUFA/SFA. Os ácidos graxos foram afetados significativamente pela castração. Não foram observadas variações nos percentuais dos ácidos graxos saturados e insaturados da carne caprina de animais abatidos com diferentes idades. O fator idade de abate apresentou maior efeito nos atributos sensoriais analisados do que o fator castração. Nos extratos da carne caprina foram identificados um total de cento e oito voláteis, sendo estes: 41 hidrocarbonetos alifáticos, 12 hidrocarbonetos alicíclicos, 19 aldeídos, 9 compostos benzênicos, 9 álcoois, 7 cetonas, 4 compostos sulfurados, 2 terpenoídes, 2 ésteres e 3 outros compostos. Os extratos da carne de caprinos castrados continham maior número de compostos voláteis do que os extratos de animais inteiros. O fator idade de abate foi o parâmetro que mais afetou as características físico-químicas e sensoriais da carne caprina. O fator castração afetou diretamente a produção de voláteis. Resumo em inglês Groups of crossbred castrated and intact goats were slaughtered at 175, 220, 265 and 310 days of age. The effect of castration and slaughter age on physical-chemical, sensorial and aromatic properties was researched. Calcium content was influenced by castration; however, slaughter age had a significant effect on moisture, protein, iron, calcium and pH. Castration and slaughter age had no significant effect on phospholipids contents, but slaughter age affected the percenta (mais) ge of total cholesterol. Fatty acids were significantly affected by castration. Castrated goat meat contained highest unsaturated fatty acids percentage and, consequently, highest ration PUFA/SFA. There were no differences in levels of saturated and unsaturated fatty acids among the animals slaughtered at different ages. Slaughter age had a higher effect on organoleptic qualities of goat meat compared to castration. A total of 108 volatiles were presented in the extract of goat meat, they were identified as: 41 aliphatic hydrocarbons, 12 alicyclic hydrocarbons, 19 aldehydes, 9 benzenoids, 9 alcohols, 7 ketones, 4 sulphur compounds, 2 terpenoids, 2 esters and 3 other compounds. Highest numbers of volatile compounds were identified from castrated goats than from entires. Slaughter age affected more intensively the physic-chemical and sensorial characteristics of goat meat. Castration affected directly the volatile formation.

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7

Utilização do TEMPO (N-oxil-2,2,6,6-tetrametilpiperidina) na oxidação de álcoois primários e secundários/ The use of TEMPO (2,2,6,6-tetramethylpiperidine-N-oxyl) for the oxidation of primary and secondary alcohols

Souza, Marcus Vinícius Nora de
2004-04-01

Resumo em inglês The oxidation of alcohols to obtain ketones, aldehydes or carboxylic acids is a fundamental transformation in organic synthesis and many reagents are known for these conversions. However, there is still a demand for mild and selective reagents for the oxidation of alcohols in the presence of other functional groups. As an alternative, the nitroxyl radical TEMPO (2,2,6,6-tetramethylpiperidine-N-oxyl) has been demonstrated to be a useful reagent for the transformation of al (mais) cohols. The oxidation of alcohols using TEMPO is often efficient, fast, selective, made in mild conditions and can tolerate sensitive functional groups. In this article we report different methodologies using TEMPO in the oxidation of alcohols.

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8

Síntese de fotoprotetores e sua imobilização em poli(metacrilato de metilo): um projeto integrado de química orgânica, química de polímeros e fotoquímica/ Sunscreen synthesis and their immobilisition on polymethylmethacrylate: an integrated project in organic chemistry, polymer chemistry and photochemistry

Murtinho, Dina Maria B.; Serra, Maria Elisa S.; Pineiro, Marta
2010-01-01

Resumo em inglês Dibenzalacetone and other aldol condensation products are known sunscreens commonly used in cosmetics. This type of compounds can easily be prepared in an Organic Chemistry Lab by reaction of aldehydes with ketones in basic medium. These compounds can be incorporated in poly(methyl methacrylate) and used as UV light absorbers, for example in sunglasses. This project has the advantage of using inexpensive reagents which are readily available in Chemistry Laboratories. This experiment can also be a base starting point for discussions of organic, polymer and photochemistry topics.

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9

Redução de amidas por boranos/ Reduction of amides by boranes

Alcântara, Antônio Flávio de Carvalho; Barroso, Hiléia dos Santos; Piló-Veloso, Dorila
2002-05-01

Resumo em inglês Despite the fact that boranes are frequently used in amide reductions, the reaction mechanisms of the involved are note well known. This work presents the results of a bibliographic search on probable amide reduction mechanisms and an analysis of the existing literature. Steric and electronic effects were considered in light of reactivity since it could be concluded that the formation of intermediates and products depends mainly on the substitution patterns of both the bo (mais) ron and nitrogen atoms. Otherwise, results described in the literature for the reactions of boranes, sodium borohydride, lithium aluminum hydride, alkylboranes or haloboranes with others functional groups such as carboxylic acids, esters, ketones and alkenes were analysed with the aim to obtain something about the N-substituted amide reactions employing boranes.

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10

Reações de contração de anel promovidas por sais de tálio(III)/ Ring contraction reactions promoted by thallium(III) salts

Ferraz, Helena M. C.; Silva Jr., Luiz F.
2000-04-01

Resumo em inglês Thallium(III) salts promote a number of different reactions useful in organic synthesis. In this paper, the ring contraction of ketones and olefins, mediated by thallium(III) salts, is exhaustively reviewed.

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11

Reação entre fenilnitrometanos e enoato derivado do D-manitol na presença de TBAF ou DBU: adição conjugada sin-seletiva e reação de NEF consecutiva/ The reaction between Phenylnitromethanes and enoate derived from D-mannitol in the presence of TBAF or DBU: tandem syn-selective conjugate addition and NEF reaction

Dias, Ayres G.; Pinho, Vagner D.; Costa, Paulo R. R.
2008-01-01

Resumo em inglês A tandem syn-selective conjugate addition - Nef reaction was observed when phenylnitromethane and oxygenated derivatives were allowed to react with an enoate derived from D-mannitol at rt in the presence of TBAF or DBU. While nitro-adducts predominate after 4h of reaction, the corresponding ketones were the main products after 12-24h of reaction. The Nef reaction occurred without racemization of the stereogenic center generated in the conjugate addition step.

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12

Oxidações eletrocatalíticas de álcoois e dióis em meio bifásico utilizando metanossulfonato de CeIV como mediador/ Electrocatalytic oxidation of alcohols and diols in a biphasic medium using CeIV methanesulfonate as mediator

Lavagnoli, L. V.; Madurro, J. M.; Romero, J. R.
1998-11-01

Resumo em inglês Some alcohols and diols were oxidized electrocatalytically in a biphasic system using ceriumIV methanesulphonate as mediator. A mixture of methanesulphonic acid solution and benzene was used and aldehydes, ketones and diacids were some of the principal products obtained with yield varying from 27 to 98%. In several cases selectivity was obtained.

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13

Marcadores orgânicos de contaminação por esgotos sanitários em sedimentos superficiais da baía de Santos, São Paulo/ Organic markers of sewage contamination in surface sediments from Santos bay, São Paulo

Martins, César de Castro; Gomes, Fernanda Boechat Azeredo; Ferreira, Juliana Aureliano; Montone, Rosalinda Carmela
2008-01-01

Resumo em inglês Organic markers, such as sterols and ketones, were used to assess sewage contamination in sediments from the Santos Bay, SP, and its continental shelf. These compounds were analyzed by GC/FID after soxhlet extraction, clean up and derivatization. The concentration of coprostanol and ratios between selected sterols were used to evaluate fecal contamination. The stations located in the mid-western part of the Santos Bay presented organic matter from sewage due to the input (mais) of fecal material from the city of Santos by submarine sewage outfall. Stations located at the continental shelf did not present fecal contamination. Coprostanol levels in sewage outfall stations were higher in comparison to other Brazilian coastal areas, except Guanabara Bay/RJ, and could be related to the fraction of the population without sewage treatment.

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14

Influência do material do destilador na composição química das aguardentes de cana: parte II/ Influence of the pot still material on the chemical composition of Brazilian sugar cane spirit: part II

Cardoso, Daniel R.; Lima-Neto, Benedito S.; Franco, Douglas W.; Nascimento, Ronaldo F. do
2003-03-01

Resumo em inglês The quantitative chemical analysis of the Brazilian sugar cane spirit distilled from glass column packaged with copper, stainless steel, aluminum sponge, or porcelain balls is described. The main chemical compounds determined by gas chromatography coupled with flame ionization (FID) and flame photometric (FPD) detectors and liquid chromatography coupled with diode array detector are aldehydes, ketones, carboxylic acids, alcohols, esters and dimethylsulfite (DMS). The spir (mais) its produced either in columns filled with copper or aluminum pot still exhibits the lowest DMS contents but the higher sulfate and methanol contents, whereas spirits produced in stainless steel or porcelain showed higher DMS concentration and lower teors of sulfate ion and methanol. These observations are coherent with DMS oxidation to sulfate, with methanol as by product, in the presence of either copper or aluminum.

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15

Influência do material do alambique na composição química das aguardentes de cana-de-açúcar/ The influence of the material used in building the distiller in the sugar-cane-spirit chemical profile

Nascimento, Ronaldo F.; Cardoso, Daniel R.; Lima Neto, Benedito dos Santos; Franco, Douglas Wagner; Farias, João Bosco
1998-11-01

Resumo em inglês This paper describes variations in the profile of the main volatile organic compounds present in Brazilian sugar cane spirits distilled in copper and stainless steel distillers. The main organic compounds: aldehydes, ketones, carboxylic acids, alcohols and esters, were determined through High Performance Liquid Chromatography (HPLC) and High Resolution Gas Cromatography (HRGC). The spirits produced in copper distillers exhibit higher contents of aldehydes with respect to (mais) the ones produced in stainless steel. The inverse is true with respect to the higher alcohol and ester contents. No significant variation has been observed for the carboxylic acids.

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16

Indução assimétrica 1,5-Anti na adição de enolatos de boro de metilcetonas beta-oxigenadas a aldeídos/ 1,5-Asymmetric induction in the boron-mediated aldol reaction of beta-oxygenated methyl ketones

Dias, Luiz C.; Aguilar, Andrea M.
2007-01-01

Resumo em inglês High levels of substrate-based 1,5-stereoinduction are obtained in the boron-mediated aldol reactions of beta-oxygenated methyl ketones with achiral and chiral aldehydes. Remote induction from the boron enolates gives the 1,5-anti adducts, with the enolate pi-facial selectivity critically dependent upon the nature of the beta-alkoxy protecting group. This 1,5-anti aldol methodology has been strategically employed in the total synthesis of several natural products. At pres (mais) ent, the origin of the high level of 1,5-anti induction obtained with the boron enolates is unclear, although a model based on a hydrogen bonding between the alkoxy oxygen and the formyl hydrogen has been recently proposed.

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17

Hipoglicemia na infância: resultados de um protocolo de avaliação prospectiva em crianças com até 1 ano de idade/ Childhood hypoglycemia: results of prospective evaluation protocols in children with up to 1 year of age

Rodrigues, Ticiana C.; Colli, Maikel; Czepielewski, Mauro A.
2007-12-01

Resumo em português O objetivo deste trabalho é relatar a experiência na aplicação de um protocolo de avaliação de hipoglicemia. Realizamos um estudo prospectivo com treze crianças com sintomas de hipoglicemia atendidas no Hospital de Clínicas de Porto Alegre, com idade média de 5,3 ± 4,5 meses, das quais oito pacientes eram do sexo feminino. Os pacientes foram submetidos ao teste de jejum, estímulo com glucagon e dosagens de glicemia, lactato, pH, ácidos graxos, insulina, (mais) peptídeo C, TSH, GH e cortisol, além de urina para avaliação de cetonúria. Dos treze pacientes avaliados, oito apresentaram hipoglicemia persistente e cinco apresentaram hipoglicemia transitória. O diagnóstico mais freqüente foi hiperinsulinismo persistente. Sugerimos a utilização de um protocolo simples de avaliação para hipoglicemia, que contempla as principais etiologias em crianças e que facilita o manejo desses pacientes. Resumo em inglês The aim of this study is to present the experience of applying hypoglycemia evaluation protocol. We performed a prospective study with 13 children with hypoglycemia symptoms at the Hospital of Clinicas of Porto Alegre, with range age 5.3 ± 4.5 months and eight patients are female. The patients had been submitted to glucagon fasting test and blood glucose, lactate, pH, C peptide, insulin, fatty acids, TSH, GH, cortisol, and urine ketones were measured. Eight patient (mais) s presented persistent hypoglycemia and five presented transitory hypoglycemia. The most frequent diagnosis was persistent hyperinsulinism. We suggest the use of a simple protocol for the evaluation of hypoglycemia, which contemplates the identifications of the main etiologies in children and facilitates the handling of these patients.

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18

Hidrogenação de compostos orgânicos utilizando método eletroquímico para geração de hidrogênio in situ: hidrogenação eletrocatalítica/ Hydrogenation of organic compounds by an electrochemical method for in situ hydrogen generation: electrocatalytic hydrogenation

Navarro, Daniela Maria do Amaral Ferraz; Navarro, Marcelo
2004-04-01

Resumo em inglês Electrocatalytic hydrogenation (HEC) may be compared to catalytic hydrogenation (HC). The difference between these methods is the hydrogen source: HC needs a hydrogen gas supply; HEC needs a source of protons (solvent) to be reduced at a cathode surface. HEC has presented interesting advances in the last decades due to investigation of the influence of the supporting electrolyte, co-solvent, surfactant, presence of inert gas and the composition of the electrode on the rea (mais) ction. Several classes of organic compounds have been hydrogenated through HEC: olefins, ketones, aldehydes, aromatics, polyaromatics and nitro-compounds. This paper shows some details about the HEC which may be regarded as a promising technique for the hydrogenation of organic compounds both in industrial processes and in laboratories.

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19

Fotólise no estado estacionário e com pulso de laser de 1-benzociclanonas e de seus derivados a,a -dimetilados/ Steady-state and laser flash photolysis of 1 - benzocyclanones and their a,a -dimethyl derivatives

Netto-Ferreira, José Carlos; Scaiano, J. C.
1999-07-01

Resumo em inglês Laser excitation of 0.01 M solutions of 1-indanone (Ia), 1-tetralone (Ib), 1-benzosuberone (Ic), and their a,a -dimethyl derivatives IIa-c, respectively, in benzene, produced transients with maximum absorption at 425 nm, and lifetimes ranging from 62 ns (IIa) to 5.5ms (Ic). Quenching studies using well known triplet quenchers such as 1,3-cyclohexadiene and oxygen demonstrated the triplet natu (mais) re of these transients. In the presence of hydrogen donors, such as 2-propanol, the triplet state decay of the ketones Ia-c leads to the formation of the corresponding ketyl radicals, i.e. IIIa-c, which show absorption spectra very similar to the parent ketone, with lmax at 430 nm and lifetime in excess of 20 ms. Steady state irradiations show that the a,a -dimethyl ketones IIa and IIc form ortho-alkyl benzaldehydes probably derived from an initial a-cleavage of the corresponding triplet excited states.

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20

Estudo de compostos orgânicos em lixiviado de aterros sanitários por EFS e CG/EM/ Study of organic compounds in landfill leachate by SPE and GC/MSD

Nascimento Filho, Irajá do; von Mühlen, Carin; Caramão, Elina Bastos
2001-08-01

Resumo em inglês The main purpose of this work was the qualitative study of organic compounds in landfill leachate. The samples were collected from a sanitary landfill located at Gravataí, a southern Brazilian city, that receive both, industrial and domestic refuse. The samples were submitted to solid phase extraction (SPE) with XAD-4 resin as the stationary phase. The instrumental analysis was performed by Gas Chromatography with a Mass Spectrometry Detector (GC/MSD). The compounds achi (mais) eved in the SPE extracts were tentatively identified by the GC/MS library. It was found several oxygen and nitrogen compounds like carboxylic acids, ketones, amines and amides. Sulfur compounds and phthalate esters are also identified.

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Compostos voláteis em méis florais/ Volatile compounds in floral honeys

De Maria, Carlos Alberto Bastos; Moreira, Ricardo Felipe Alves
2003-01-01

Resumo em inglês A review about origin, composition and importance of volatile compounds in floral honeys is presented. Hydrocarbons, aromatic components, acids, diacids, terpenoids, ketones, aldehydes, esters and alcohols have been found in honey aroma of different botanical origin. Cis-rose oxide has been proposed as an indicator for Tilia cordata honey. Citrus honeys are known to contain methyl anthranilate, a compound which other honeys virtually lack. Linalool, phenylethylalcohol, ph (mais) enylacetaldehyde, p-anisaldehyde and benzaldehyde are important contributors for the aroma of different unifloral honeys. Both isovaleric acid, gama-decalactone and benzoic acid appears to be important odourants for Anarcadium occidentale and Croton sp. honeys from Brazil. The furfurylmercaptan, benzyl alcohol, delta-octalactone, eugenol, phenylethylalcohol and guaiacol appear to be only relevant compounds for Anarcadium occidentale. The vanillin was considered an important odourant only for Croton sp..

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Compostos carbonílicos atmosféricos: fontes, reatividade, níveis de concentração e efeitos toxicológicos/ Atmospheric carbonyl compounds: sources, reactivity, concentration levels and toxicologic effects

Andrade, Marta Valéria Almeida Santana de; Pinheiro, Heloisa Lúcia Castellar; Pereira, Pedro Afonso de Paula; Andrade, Jailson Bittencourt de
2002-12-01

Resumo em inglês In the last three decades carbonyl compounds, aldehydes and ketones, have received a great deal of attention due to their strong influence on photochemical smog formation and their recognized adverse human health effects. Carbonyl compounds are directly emitted into the atmosphere by combustion sources and also produced from photochemical oxidation of hydrocarbons and other organic compounds. In this paper it is presented a general overview about the carbonyl compounds sources, reactivity, concentration levels and toxicological effects.

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Componentes voláteis do café torrado. Parte II. Compostos alifáticos, alicíclicos e aromáticos/ Volatile components in roasted coffee. Part II. Aliphatic, alicyclic and aromatic compounds

Moreira, Ricardo Felipe Alves; Trugo, Luiz Carlos; De Maria, Carlos Alberto Bastos
2000-04-01

Resumo em inglês This review is about the aliphatic, alicyclic and aromatic compounds (non-heterocyclic compounds) that are present in the volatile fractions of roasted coffees. Herein, the contents, aroma precursors and the sensorial properties of volatile phenols, aldehydes, ketones, alcohols, ethers, hydrocarbons, carboxylic acids, anhydrides, esters, lactones, amines and sulphur compounds are discussed. Special attention is given to the compounds of these groups that are actually important to the final aroma of roasted coffees.

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Complicações hiperglicêmicas agudas no diabetes melito tipo 1 do jovem/ Hyperglycemic acute crisis in type 1 diabetes mellitus in youth

Damiani, Durval; Damiani, Daniel
2008-03-01

Resumo em português A principal complicação hiperglicêmica no diabetes melito tipo 1 (DM1) é a cetoacidose diabética (CAD). Embora variações nos protocolos possam ocorrer, os princípios básicos que norteiam o tratamento devem ser os mesmos. A recuperação inicial da capacidade circulatória, com a infusão rápida de solução salina na dose de 20 mL/kg, que pode ser repetida, é o ponto de partida para o tratamento. A partir daí, a reposição de volume é relativamente lenta, e (mais) o objetivo principal é corrigir gradualmente os distúrbios metabólicos instalados, sem ocasionar variações muito intensas e muito rápidas na osmolalidade, fator de risco para complicações. Atenção ao desenvolvimento de edema cerebral que, uma vez suspeitado, deve ser imediatamente corrigido, sob pena de óbito ou seqüelas neurológicas. A administração de insulina ultra-rápida, por via subcutânea, mostra-se eficaz e simplifica o atendimento do paciente. A CAD é uma situação grave, ainda com alta mortalidade, e seu tratamento deve ser dirigido aos pontos principais que levaram ao quadro clínico, com correções graduais, sob risco de se agravar o quadro. Resumo em inglês Diabetic ketoacidosis (DKA) is the main hyperglycemic complication in type 1 Diabetes Mellitus (DM1). The basic principles in treatment have to be followed carefully. The patient with DKA has a very deep volume depletion. To restore the circulatory capacity is the first step. From this point on, the restoration of the lost fluids is slow, around 1% per hour, aiming at the correction of the metabolic disturbance already on and avoiding great fluctuations in osmolality, whi (mais) ch increases the risk of having complications. Attention to the development of cerebral edema, which, once suspected, deserves an urgent treatment plan, trying to avoid neurologic sequelae or even death. Subcutaneous ultra-rapid insulin has been demonstrated to be efficient and easier to use. As the perfusion gets improved and the levels of insulin increase, the lipolysis is blocked, as well as the generation of ketones and so the acidemia tends to be solved. DKA is still a high-mortality condition. And to be in a hurry frequently leads to neurologic sequelae and even to a fatal outcome.

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Cetoacidose diabética em crianças: revisão da fisiopatologia e tratamento com o uso do “método de duas soluções salinas”/ Diabetic ketoacidosis in children: review of pathophysiology and treatment with the use of the “two bags system”

Collett-Solberg, Paulo Ferrez
2001-02-01

Resumo em português Objetivo: Rever vários aspectos da cetoacidose diabética, incluindo o “sistema de duas soluções”, um método de administrar líquidos que proporciona correção mais suave do estado de hiperglicemia e de cetose. Métodos: Revisão de publicações recentes (dos últimos 7 anos) referidas na base de dados da Medline e capítulos de livros de pediatria que abordam a etiologia, o tratamento e as complicações da cetoacidose diabética. O tratamento aqui apresentado ut (mais) iliza a informação encontrada nestes artigos e a experiência clínica adquirida no Children’s Hospital of Philadelphia e no Duke University Medical Center. Resultados: A patologia do diabetes mellitus tipo 1 envolve a destruição das células ß do pâncreas, causando uma deficiência de insulina. A insulina é essencial para o metabolismo de carboidratos, proteínas e gorduras. A deficiência de insulina pode levar a um quadro de cetoacidose diabética que apresenta três componentes: 1) a hiperglicemia, que causa glicosúria e conseqüentemente desidratação; 2) a lipólise em excesso, que causa aumento nos níveis séricos e urinários de corpos cetônicos; e 3) a acidose metabólica, que é causada pela desidratação e pela presença de corpos cetônicos no sangue. A cetoacidose diabética é uma condição grave que, se não tratada adequadamente, pode levar ao coma e à morte. Em crianças, uma das mais temidas complicações é o edema cerebral. Conclusões: Na literatura publicada existem diversas maneiras de se tratar a cetoacidose diabética em pediatria, sem um consenso sobre a causa da principal complicação, edema cerebral, e conseqüentemente, sem um consenso quanto ao melhor método de intervenção. O uso do sistema de duas soluções em pacientes em cetoacidose diabética permite o rápido ajuste na concentração da glicose infundida, simplificando e barateando o tratamento da cetoacidose diabética. Resumo em inglês Objectives: To review diabetic ketoacidosis, including the “two bags system”, a method of administering liquids in order to provide a smoother correction of the hyperglycemic and ketotic states. Methods: Review of recent publications (last 7 years) from a Medline search and chapters published in pediatric textbooks that discuss the etiology, therapy, and complications of diabetic ketoacidosis. The management approach incorporates the findings of these publications as we (mais) ll as the clinical experience at the Children’s Hospital of Philadelphia and Duke University Medical Center. Results: The pathology of the type 1 Diabetes Mellitus involves the progressive destruction of the ß cells of the pancreas, causing insulin deficiency. Insulin is essential in the metabolism of carbohydrates, protein and fat. Insulin deficiency may lead to diabetic ketoacidosis which has three components: 1) hyperglycemia, which causes glycosuria and consequently dehydration; 2) lipolysis which, causes ketonemia/ketonuria; and 3) acidosis, that is caused by the dehydration and the high serum levels of ketones. Diabetic ketoacidosis is a serious condition and, if not treated appropriately, can cause coma and death. In children cerebral edema is the major complication of the therapy for diabetic ketoacidosis. Careful replacement of insulin, fluids, glucose and electrolytes is essential. Conclusions: The literature presents different ways to manage DKA in pediatrics, without a consensus on the cause of the most important complication (cerebral edema), and consequently without a consensus on the best approach. The use of the two saline bags in patients in DKA allows fast adjustments in the dextrose concentration of the infusion fluids, simplifying and reducing the costs of the treatment of diabetic ketoacidosis.

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