Página 1 dos resultados de 68219 itens digitais encontrados em 0.012 segundos

Downscaling a multicommuted flow injection analysis system for the photometric determination of iodate in table salt

BORGES, Sivanildo S.; PEIXOTO, Jailson de Souza; FERES, Mario A.; REIS, Boaventura F.
Fonte: ELSEVIER SCIENCE BV Publicador: ELSEVIER SCIENCE BV
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
36.28316%
In this work a downscaled multicommuted flow injection analysis setup for photometric determination is described. The setup consists of a flow system module and a LED based photometer, with a total internal volume of about 170 mu L The system was tested by developing an analytical procedure for the photometric determination of iodate in table salt using N,N-diethyl-henylenediamine (DPD) as the chromogenic reagent. Accuracy was accessed by applying the paired r-test between results obtained using the proposed procedure and a reference method, and no significant difference at the 95% confidence level was observed. Other profitable features, such as a low reagent consumption of 7.3 mu g DPD per determination: a linear response ranging from 0.1 up to 3.0 m IO(3)(-), a relative standard deviation of 0.9% (n = 11) for samples containing 0.5 m IO(3)(-), a detection limit of 17 mu g L(-1) IO(3)(-), a sampling throughput of 117 determination per hour, and a waste generation 600 mu L per determination, were also achieved. (C) 2010 Elsevier B.V. All rights reserved.

Green Chemistry-Sensitive Analytical Procedure for Photometric Determination of Orthophosphate in River and Tap Water by Use of a Simple LED-Based Photometer

SILVA, Milton B.; BORGES, Sivanildo S.; PERDIGAO, Sheila R. W.; REIS, Boaventura F.
Fonte: TAYLOR & FRANCIS INC Publicador: TAYLOR & FRANCIS INC
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
36.252607%
In the current work a Green Analytical Chemistry (GAC) procedure for photometric determination of orthophosphate in river water at mu g L-1 concentration level is described. The flow system module and the LED-based photometer were assembled together to constitute a compact unit in order to allow that a flow cell with optical path-length of 100mm was coupled to them. The photometric procedure based on the molybdenum blue method was implemented employing the multicommuted flow injection analysis approach, which provided facilities to allow reduction of reagent consumption and as well as waste generation. Aiming to prove the usefulness of the system, orthophosphate in river and tap waters was determined. Accuracy was ascertained by spiking samples with orthophosphate solution yielding recoveries ranging from 96% up to 107%. Other profitable features such as a wide linear response range between 10 to 800 mu g L-1 [image omitted]; a detection limit (3 sigma criterion) of 2.4 mu g L-1 [image omitted]; a relative standard deviation (n=7) of 2% using a typical water sample with concentration of 120 mu g L-1 [image omitted]; reagent consumption of 3.0mg ammonium molybdate, 0.3mg hydrazine sulfate, and 0.03mg stannous chloride per determination; a waste generation of 2.4mL per determination; and a sampling throughput of 20 determination per hours were also achieved.; CNPq (Conselho Nacional de Desenvolvimento Cientifico e Tecnologico do Brasil); CAPES (Coordenadenacao de Aperfeicoamento de Pessoal de Nivel Superior)

Simultaneous Differential Pulse Voltammetric Determination of Ascorbic Acid and Caffeine in Pharmaceutical Formulations Using a Boron-Doped Diamond Electrode

LOURENCAO, Bruna Claudia; MEDEIROS, Roberta Antigo; ROCHA-FILHO, Romeu C.; FATIBELLO-FILHO, Orlando
Fonte: WILEY-BLACKWELL Publicador: WILEY-BLACKWELL
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
36.252607%
A cathodically pretreated boron-doped diamond electrode was used for the simultaneous anodic determination of ascorbic acid (AA) and caffeine (CAF) by differential pulse voltammetry Linear calibration curves (r = 0 999) were obtained from 1 9 x 10(-5) to 2 I x 10(-4) mol L(-1) for AA and from 9 7 x 10(-6) to 1 1 x 10-4 mol L(-1) for CAF. with detection limits of 19 wool L(-1) and 7 0 mu nol L(-1). respectively This method was successfully applied for the determination of AA and CAF in pharmaceutical formulations. with results equal to those obtained using a HPLC reference method; FAPESP[2007/05894-9]; Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); CNPq; Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); CAPES

Simultaneous voltammetric determination of paracetamol and caffeine in pharmaceutical formulations using a boron-doped diamond electrode

LOURENCAO, Bruna Claudia; MEDEIROS, Roberta Antigo; ROCHA-FILHO, Rorneu C.; MAZO, Luiz Henrique; FATIBELLO-FILHO, Orlando
Fonte: ELSEVIER SCIENCE BV Publicador: ELSEVIER SCIENCE BV
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
36.342078%
A simple and highly selective electrochemical method was developed for the single or simultaneous determination of paracetamol (N-acetyl-p-aminophenol, acetaminophen) and caffeine (3,7-dihydro-1,3,7-trimethyl-1H-purine-2,6-dione) in aqueous media (acetate buffer, pH 4.5) on a boron-doped diamond (BDD) electrode using square wave voltammetry (SWV) or differential Pulse voltammetry (DPV). Using DPV with the cathodically pre-treated BDD electrode, a separation of about 550 mV between the peak oxidation potentials Of paracetamol and caffeine present in binary mixtures was obtained. The calibration curves for the simultaneous determination of paracetamol and caffeine showed an excellent linear response, ranging from 5.0 x 10(-7) mol L(-1) to 8.3 x 10(-7) mol L(-1) for both compounds. The detection limits for the simultaneous determination of paracetamol and caffeine were 4.9 x 10(-7) mol L-1 and 3.5 x 10(-8) mol L(-1), respectively. The proposed method Was Successfully applied in the simultaneous determination of paracetamol and caffeine in several pharmaceutical formulations (tablets), with results similar to those obtained using a high-performance liquid chromatography method (at 95% confidence level). (C) 2008 Elsevier BY. All rights reserved.; FAPESP[2007/05894-9]; Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); CAPES; Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); CNPq; Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Desenvolvimento de métodos eletroanalíticos (análise por redissolução e eletroforese capilar) para a determinação de metais e ânions em combustíveis e derivados de petróleo; Development of electroanalytical methods (Stripping Analysis and Capillary Electrophoresis) for the determination of metals and anions in fuels and petroleum-based products

Muñoz, Rodrigo Alejandro Abarza
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 15/03/2006 Português
Relevância na Pesquisa
36.307068%
Neste trabalho foram desenvolvidos métodos eletroanalíticos (redissolução potenciométrica e voltamétrica) para a determinação de metais (mercúrio, cobre, chumbo e zinco) em petróleo, óleo diesel, óleo lubrificante e álcool combustível. Para analisar álcool, foi também desenvolvido um método por eletroforese capilar, que possibilita a determinação de cátions (sódio, potássio e cálcio) e ânions (cloreto, sulfato e nitrato). Procedimentos envolvendo a utilização de fornos de microondas (focalizadas - que opera a pressão atmosférica - e com cavidade, que promove a digestão em frascos pressurizados) para a decomposição de petróleo, óleo diesel e óleo lubrificante são descritos. As determinações de cobre e mercúrio por redissolução potenciométrica apresentaram melhores limites de detecção do que a voltametria de redissolução de onda quadrada nas amostras digeridas, utilizando eletrodos de ouro confeccionados a partir de CDs graváveis (Cdtrodos), como eletrodo de trabalho. Para a determinação de chumbo e zinco nas mesmas amostras digeridas, os melhores resultados foram obtidos com eletrodos de filme de mercúrio e utilizando a voltametria de redissolução potenciométrica. Perdas de mercúrio por volatilização foram verificadas quando as amostras foram digeridas em fornos de microondas focalizadas. Para os demais metais...

Pari-cachoeira e Trinidad: convivência e construção da autodeterminação indígena na fronteira Brasil-Colômbia; Pari-Cachoeira and Trinidad: coexistence and construction of the self-determination indigenous in the border Brasil-Colômbia

Dutra, Israel Fontes
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 23/04/2009 Português
Relevância na Pesquisa
36.252607%
Esta dissertação enfoca as contradições e conflitos da convivência dos Tukano de Pari- Cachoeira (Brasil) e Tuyuka de Trinidad (Colômbia) e a construção da autodeterminação indígena na fronteira Brasil-Colômbia, pois, mesmo depois da demarcação da Terra Indígena Alto Rio Negro em 1998, ficaram entrecortados pela fronteira. Este fato ameaça as relações de diversos matizes entre esses dois grandes povoados, a saber, prejudicam as relações de parentesco e circulação. Pari-Cachoeira é uma comunidade habitada pelo povo Tukano, do subgrupo Pãsi Põã, localizada no alto rio Tiquié, Uaupés, Brasil. Trinidad é habitada pelo povo Tuyuka, alto Tiquié, na Gran Resguardo Indígena Del Vaupés, Departamento Del Vaupés, Colômbia. No cenário da política indígena do rio Negro, Pari-Cachoeira se destaca por ser o lugar onde se originou o Movimento Indígena do rio Negro, no início da década de 70, que culminou na fundação da Federação das Organizações Indígenas do rio Negro (FOIRN), em 1987. E, Trinidad se destaca por estar situada em uma zona de conflito entre Governo colombiano e as Forças Armada Revolucionária da Colômbia (FARC), que ameaça a circulação e a autonomia indígena em território colombiano. A dissertação está constituída por quatro capítulos. O primeiro capítulo apresenta o contexto histórico dos indígenas do alto rio Negro e o movimento indígena na atualidade. Conjugo informações bibliográficas acadêmicas e as fontes orais dos sujeitos sociais da pesquisa. No segundo capítulo apresentamos uma abordagem teórica dos conceitos selecionados para a pesquisa...

Comparação de métodos não-destrutivos de cubagem de árvores em pé visando à determinação da biomassa; Comparison of non-destructive methods of wood volume determination of standing trees for biomass determination

Nicoletti, Marcos Felipe
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 06/10/2011 Português
Relevância na Pesquisa
36.252607%
As florestas são vistas como excelentes acumuladoras de biomassa e carbono da atmosfera, contribuindo para a redução do efeito estufa. Para ter conhecimento da biomassa acumulada nas árvores é necessário realizar determinadas técnicas para levantar o volume de madeira dos povoamentos. Desta forma, objetiva-se neste trabalho estudar a qualidade das medidas de cubagem da árvore em pé através de dendrômetros ópticos de medição do tronco visando à determinação da biomassa de árvores sem amostragem destrutiva. O trabalho foi desenvolvido na Estação Experimental de Itatinga/SP que pertence a Universidade de São Paulo (ESALQ-USP). Foram amostradas 175 árvores em três parcelas de Eucalyptus grandis. O diâmetro do fuste das árvores em pé foi mensurado com os dendrômetros (Criterion 400 e RC3H) em distâncias de 0,1; 0,4; 0,7; 1,0; 1,3; 2,0 m e a partir deste de metro em metro ao longo do tronco até os 8 m de altura. Após a cubagem em pé foi derrubada a árvore e seccionada para pesagem do tronco, sendo que o diâmetro foi obtido com auxílio de suta e da trena nas mesmas posições em que se realizou a cubagem não destrutiva. De posse dos diâmetros foram calculados o volume por secção e por árvore individual através da fórmula de Smalian para posterior comparação dos métodos. Depois de seccionado o tronco...

Elementos traço em óleo cru: determinação total e estudo de especiação; Trace elements in crude oil: total determination and speciation study

Luz, Maciel Santos
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 17/12/2013 Português
Relevância na Pesquisa
36.355278%
O objetivo desta pesquisa foi o desenvolvimento de métodos para: determinação simultânea de Cr/Fe/Ni/V em óleo cru; determinação simultânea de Co/Cu/Pb/Se em óleo cru, gasolina e diesel; determinação monoelementar de Si em óleo cru, gasolina e diesel; e determinação de espécies porfirínicas de Fe/Ni/V em óleo cru, utilizando ultracentrifugação e extração em ponto nuvem, por espectrometria de absorção atômica com forno de grafite e detecção simultânea (SIMAAS). Foram estudadas as condições de preparo das amostras por emulsão, empregando Triton X-100® como surfactante e hexano ou clorofórmio como solventes diluentes do óleo cru. Nas melhores condições, as emulsões foram preparadas em 6% (m v-1) de Triton X-100® com o óleo cru previamente diluído com 125 µL de hexano (nos métodos para as determinações totais dos elementos) ou diluído com 400 µL de clorofórmio (no método para a determinação das espécies porfirínicas). No método envolvendo a determinação simultânea total de Cr/Fe/Ni/V não foi utilizada agitação ultrassônica devido à pequena massa de óleo necessária (50 mg) para análise. Por outro lado, a agitação ultrassônica foi essencial para possibilitar a estabilização de maiores massas de óleo cru (200 mg e 400 mg) na emulsão. A estabilidade da emulsão só foi melhorada com agitação ultrassônica...

Sex determination studies in two species of teleost fish, Oreochromis niloticus and Leporinus elongatus

Baroiller, Jean-Francois; Nakayama, Ichiro; Foresti, Fausto; Chourrout, Daniel
Fonte: Acad Sinica Inst Zoology Publicador: Acad Sinica Inst Zoology
Tipo: Artigo de Revista Científica Formato: 279-285
Português
Relevância na Pesquisa
36.252607%
Genetic analyses of sex determination have identified sex chromosomes in many teleost fish species. However, there are several cases for which sex ratios do not fit perfectly with the expectations of heterogametic systems, suggesting the influence of either minor sex determining genes or environmental influences on the process of sex differentiation. The frequent absence of sex chromosome markers makes the identification of minor sex-determining genes very difficult. It is easier to test first the hypothesis of environmental sex determination (ESD) by studying the temperature effect, since temperature-dependent sex determination has been demonstrated to occur in several vertebrate groups including 1 fish species. To contribute to a better understanding of fish sex determination, we have tested the effects of high temperatures on sex ratios of Oreochromis niloticus, and have attempted to isolate sex chromosome molecular markers in Leporinus elongatus. Treatments of O. niloticus fry at 36 degrees C applied for 10 days and more, and starting 1 week after fertilization markedly increased the proportion of males, and progeny-testing these males confirmed that some of them are sex-reversed genetic females. Two non-coding sequences of L. elongatus Z and W chromosomes were cloned by genomic subtraction. They cross-hybridized with the genome of a close species without providing sex-specific patterns. A collection of L. elongates individuals was subjected to gonadal and chromosomal sexing...

Determination of iodide and idoxuridine at a glutaraldehyde-cross-linked poly-L-lysine modified glassy carbon electrode

Pereira, F. C.; Fogg, A. G.; Ugo, P.; Bergamo, E. P.; Stradiotto, N. R.; Zanoni, Maria Valnice Boldrin
Fonte: Wiley-Blackwell Publicador: Wiley-Blackwell
Tipo: Artigo de Revista Científica Formato: 1309-1316
Português
Relevância na Pesquisa
36.28316%
The detection limit (about 0.017 mu g mL(-1)) for voltammetric determination of iodide (peak at +0.87 V vs. Ag/AgCl at pH 2) at a glutaraldehyde-cross-linked poly-L-lysine modified glassy carbon electrode involving oxidation to iodine was found to be several orders of magnitude lower than that for the voltammetric determination on a bare glassy carbon electrode. This method was applied successfully to the determination of iodide in two medicinal formulations. Idoxuridine was determined indirectly at the same electrode by accumulating it first at -0.8 V vs. Ag/AgCl. At this potential the C-I bond in the adsorbed idoxuridine is reduced giving iodide, which is then determined at the modified electrode. The method was successfully applied to the determination of idoxuridine in a urine sample.

Sex determination in mythology and history

Mittwoch,Ursula
Fonte: Sociedade Brasileira de Endocrinologia e Metabologia Publicador: Sociedade Brasileira de Endocrinologia e Metabologia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/02/2005 Português
Relevância na Pesquisa
36.28316%
The history of ideas on how the sexes became divided spans at least three thousand years. The biblical account of the origin of Eve, and the opinions of the philosophers of classical Greece, have unexpected bearings on present-day ideas. The scientific study of sex determination can be said to have begun in the 17th century with the discovery of spermatozoa, but the origin and function of the "spermatic animalcules" eluded investigators until 1841. The mammalian egg was discovered in 1827, and in the last quarter of the century fertilization was observed. The view current at that time, that sex determination was under environmental control, gave way to the idea of chromosomal determination in the first quarter of the 20th century. The study of human and other mammalian chromosomes during the third quarter of the century, and the discovery of sex-chromosome abnormalities, emphasized the importance of the Y chromosome for male sex determination. The last quarter of the century witnessed a hunt for the "testis-determining" gene, thought to be responsible for the differentiation of Sertoli cells, and culminating in the isolation of SRY (Sry in the mouse). However, an increasing number of additional genes and growth factors were found to be required for the establishment of male sex. During the same period evidence emerged that male development was accompanied by enhanced growth...

Spectrophotometric Determination of Aluminium in Iron Ores Using Solid-Phase Extraction

Ferreira,Sérgio Luis Costa; Lemos,Valfredo Azevedo; Costa,Antônio Celso Spinola; Jesus,Djane Santiago de; Carvalho,Marcelo Souza de
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/04/1998 Português
Relevância na Pesquisa
36.28316%
In the present paper, a procedure for separation and determination of aluminium in iron matrices is proposed. It is based on the solid-phase extraction of the iron, in the form of thiocyanate complexes, by a polyurethane(PU) foam. The followings parameters were studied: effect of pH and of the thiocyanate concentration on the iron extraction, shaking time required for quantitative extraction, amount of PU foam necessary for complete extraction of iron, aluminium separation from other cations, influence of anions on the iron sorption by PU foam and analytical characteristics of the procedure for aluminium determination using methylthymol blue as chromogenic reagent. The results show that, in the pH range from 1.5 to 4.7, with a thiocyanate concentration of 0.80 mol L-1, by extraction using 1 g of polyurethane foam and a shaking time of 1 min, aluminium (40 mug) can be separated from large amounts of iron (10 mg), 800 mug of copper(II), cobalt(II), zinc(II), mercury(II), tin(IV), manganese(II) and tungsten(V); 100 mug of titanium(IV) and lead(II); and 50 mug of vanadium(V). Calcium(II), barium(II), strontium(II) and magnesium(II) can not be separated by this process, but do not react with MTB under the conditions used for aluminium determination. The anions nitrate...

Spectrophotometric simultaneous determination of uranium and thorium using partial least squares regression and orthogonal signal correction

Niazi,Ali
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/10/2006 Português
Relevância na Pesquisa
36.28316%
A simple, novel and sensitive spectrophotometric method was described for simultaneous determination of uranium and thorium. The method is based on the complex formation of uranium and thorium with Arsenazo III at pH 3.0. All factors affecting the sensitivity were optimized and the linear dynamic range for determination of uranium and thorium found. The simultaneous determination of uranium and thorium mixtures by using spectrophotometric methods is a difficult problem, due to spectral interferences. By multivariate calibration methods such as partial least squares (PLS), it is possible to obtain a model adjusted to the concentration values of the mixtures used in the calibration range. Orthogonal signal correction (OSC) is a preprocessing technique used for removing the information unrelated to the target variables based on constrained principal component analysis. OSC is a suitable preprocessing method for PLS calibration of mixtures without loss of prediction capacity using spectrophotometric method. In this study, the calibration model is based on absorption spectra in the 600-760 nm range for 25 different mixtures of uranium and thorium. Calibration matrices contained 0.10-21.00 and 0.25-18.50 µg mL-1 of uranium and thorium, respectively. The RMSEP for uranium and thorium with OSC and without OSC were 0.4362...

Selbstbestimmung und Menschen mit schwerer geistiger Behinderung; Self-determination and persons with profound mental disabilities

Weingärtner, Christian
Fonte: Universität Tübingen Publicador: Universität Tübingen
Tipo: Dissertation; info:eu-repo/semantics/doctoralThesis
Português
Relevância na Pesquisa
36.391785%
Diese Arbeit behandelt die Frage, wie Selbstbestimmung für Menschen mit schwerer geistiger Behinderung zu fassen ist. Hierfür wird das Konzept der Basalen Selbstbestimmung entwickelt und anhand von Beispielen aus der sonderpädagogischen Praxis expliziert. Basale Selbstbestimmung, verstanden als die mögliche Selbstbestimmung von Menschen mit schwerer geistiger Behinderung, setzt sich aus drei Aspekten zusammen: - "Selbstentscheiden", - "Erfahren der eigenen Wirkung", - "Selbsttätigkeit". Die Fragestellung dieser Arbeit rührt aus folgender Problemlage: Selbstbestimmung ist als Forderung für Menschen mit geistiger Behinderung im Rahmen der deutschen und internationalen sonderpädagogischen Selbstbestimmungsdiskussion weitgehend anerkannt. Konzepte für die Umsetzung existieren aber hauptsächlich für Menschen mit leichterer geistiger Behinderung. Für Menschen mit schwerer geistiger Behinderung mangelt es an praktisch umsetzbaren Konzepten. Diese Lücke versucht die vorliegende Arbeit zu schließen, indem sie ein Konzept für Selbstbestimmung bzw. Autonomie entwickelt, welches der Lebenswelt schwer geistig behinderter Menschen gerecht wird. Dazu wird das Prinzip "Entscheidenlassen" von Martin Th. Hahn um die Elemente "Erfahren der eigenen Wirkung"...

Jurisdictional devolution: Towards an effective model for Indigenous community self-determination

Smith, Diane E
Fonte: Universidade Nacional da Austrália Publicador: Universidade Nacional da Austrália
Tipo: Working/Technical Paper Formato: 386702 bytes; application/pdf
Português
Relevância na Pesquisa
36.307068%
Over a decade ago the House of Representatives Standing Committee on Aboriginal Affairs and the Royal Commission into Aboriginal Deaths in Custody concluded that the essence of self-determination is the devolution of political and economic power to Indigenous communities. Self-determination was defined to mean Indigenous people having control over the ultimate decisions about a wide range of matters including political status, and economic, social and cultural development, and having the resources and capacity to control the future of their own communities within the legal structure common to all Australians.

This paper proposes that the concept of jurisdictional devolution could provide a key framework for the practical implementation of self-determination at the community level for Indigenous Australians, and proceeds to examine the nature of the concept, its application, and the challenges and opportunities it presents. It argues that the concept of jurisdictional devolution can be used as an organising perspective or frame of reference. This enables us to develop a policy-relevant language with which to discuss the implementation of local-level self-determination, and connects theoretical propositions about inherent rights to self-determination...

An Environmental Friendly Procedure for Photometric Determination of Hypochlorite in Tap Water Employing a Miniaturized Multicommuted Flow Analysis Setup

BORGES, Sivanildo S.; REIS, Boaventura F.
Fonte: HINDAWI PUBLISHING CORPORATION Publicador: HINDAWI PUBLISHING CORPORATION
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
36.28316%
A photometric procedure for the determination of ClO(-) in tap water employing a miniaturized multicommuted flow analysis setup and an LED-based photometer is described. The analytical procedure was implemented using leucocrystal violet (LCV; 4,4', 4 ''-methylidynetris (N, N-dimethylaniline), C(25)H(31)N(3)) as a chromogenic reagent. Solenoid micropumps employed for solutions propelling were assembled together with the photometer in order to compose a compact unit of small dimensions. After control variables optimization, the system was applied for the determination of ClO(-) in samples of tap water, and aiming accuracy assessment samples were also analyzed using an independent method. Applying the paired t-test between results obtained using both methods, no significant difference at the 95% confidence level was observed. Other useful features include low reagent consumption, 2.4 mu g of LCV per determination, a linear response ranging from 0.02 up to 2.0 mg L(-1) ClO(-), a relative standard deviation of 1.0% (n = 11) for samples containing 0.2 mg L(-1) ClO(-), a detection limit of 6.0 mu g L(-1) ClO(-), a sampling throughput of 84 determinations per hour, and a waste generation of 432 mu L per determination.

Self-determination between the challenges of diversity and liberal peace dictates

Barata, Maria João
Fonte: Perspectivas – Portuguese Journal of Political Science and International Relations Publicador: Perspectivas – Portuguese Journal of Political Science and International Relations
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
36.307068%
Self-determination is a crucial concept in establishing the legitimacy of political communities in the international system, and thereby in constructing social identities and political loyalties. At the most general level, self-determination refers to an idea of a right to freedom. In international politics, it also refers to a norm on ways of bounding political communities. At the same time, what self-determination precisely means is contested and contingent. I argue that self-determination evolves today amidst a tension between the challenges of diversity and liberal peace dictates. While diversity has to do with varieties of cultural expression, socioeconomic organization and political status, liberal peace dictates concern global governance practices that tend to impose previous liberal models of democracy, development and human rights. The essay first presents the evolution of the meaning of self-determination in international politics. Then it addresses critical approaches upon contemporary liberal peace. The remaining sections analyze how contemporary self-determination movements present claims highly suggestive to rethink forms of political community, of state-community relation, and of participation in global governance structures.

Temperature-Dependent Sex Determination in Fish Revisited: Prevalence, a Single Sex Ratio Response Pattern, and Possible Effects of Climate Change

Ospina-Álvarez, Natalia; Piferrer, Francesc
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artículo Formato: 470051 bytes; application/pdf
Português
Relevância na Pesquisa
36.28316%
11 pages, 5 figures, 2 tables.-- PMID: 18665231 [PubMed].-- Supporting information available: Supplementary Table "Field and laboratory data used for the assessment of the presence of temperature-dependent sex determination in gonochoristic fish" and list of references.; [Background] In gonochoristic vertebrates, sex determination mechanisms can be classified as genotypic (GSD) or temperature-dependent (TSD). Some cases of TSD in fish have been questioned, but the prevalent view is that TSD is very common in this group of animals, with three different response patterns to temperature.; [Methodology/Principal Findings] We analyzed field and laboratory data for the 59 fish species where TSD has been explicitly or implicitly claimed so far. For each species, we compiled data on the presence or absence of sex chromosomes and determined if the sex ratio response was obtained within temperatures that the species experiences in the wild. If so, we studied whether this response was statistically significant. We found evidence that many cases of observed sex ratio shifts in response to temperature reveal thermal alterations of an otherwise predominately GSD mechanism rather than the presence of TSD. We also show that in those fish species that actually have TSD...

A systems-level view of mammalian sex determination.

Munger, Steven Carmen
Fonte: Universidade Duke Publicador: Universidade Duke
Tipo: Dissertação
Publicado em //2010 Português
Relevância na Pesquisa
36.307068%

Pathologies of sexual development are common in humans and reflect the precarious processes of sex determination and sexual differentiation. The gonad forms as a bipotential organ, and recent results from the Capel lab revealed that it is initially balanced between testis and ovarian fates by opposing and antagonistic signaling networks. In XY embryos, this balance is disrupted by the transient expression of the Y-linked gene, Sry, which activates genes that promote the testis pathway and oppose the ovarian pathway. While the roles of a few genes have been defined by mutation, current evidence suggests that the interactions of many genes and signaling pathways are involved in the establishment of sexual fate. For example, most cases of disorders of sexual development (DSDs) are unexplained by mutations in known sex determination genes. In addition, recent microarray studies in the mouse revealed that nearly half the transcriptome is expressed in the gonad at the time of sex determination (Embryonic day 11.5, or E11.5), and as many as 1,500 genes are expressed in a sexually dimorphic pattern at this early stage. Thus the sexual fate decision in the developing gonad likely depends on a complex network of interacting factors that converge on a critical threshold.

To begin to elucidate the transcription network topology underlying sex determination...

Evolution of mammalian sex chromosomes and sex determination genes: insights from monotremes.

Toledo-Flores, Deborah Fernanda
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2015 Português
Relevância na Pesquisa
36.307068%
Genetic sex determination systems are generally based on the presence of differentiated sex chromosomes. Birds have a ZZ/ZW sex chromosome system in which males are ZZ and females ZW, whereas mammals have an XX/XY system with males being XY and females XX. Monotremes have an extraordinary sex chromosome system that consists of multiple sex chromosomes: 5X5Y in platypus and 5X4Y in echidna. Intriguingly, the monotreme sex chromosomes show extensive homology to the bird ZW and not to the therian XY. However, sex determination in monotremes is still a mystery; the Y-specific Sry gene that triggers male sex determination in therian mammals is absent and so far very few genes have been identified on Y chromosomes in monotremes. To gain more insights into the gene content of Y-chromosomes and to identify potential sex determination genes in the platypus a collaborative large scale transcriptomic approach led to the identification of new male specific genes including the anti-Muellerian hormone AMH that I mapped to Y₅, this makes Amhy an exciting new candidate for sex determination in monotremes. Platypus chromosome 6 is largely homologous to the therian X and therefore it represents the therian proto sex chromosome. In addition, this autosome features a large heteromorphic nucleolus organizer region (NOR) and associates with the sex chromosomes during male meiosis (Casey and Daish personal communication). I investigated chromosome 6 heteromorphism in both sexes and found a number of sex-specific characteristics related to the extent of the NOR heteromorphism...