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Alteração do comportamento reológico da suspensão cimentícia aplicada sobre substratos porosos.; Modification of rheological behavior of cementitious paste applied on porous substrates.

Barbosa, Waleska da Silva
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 01/07/2010 PT
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As argamassas de revestimento são amplamente utilizadas na construção civil e, suas propriedades no estado endurecido são fortemente influenciadas pelas propriedades no estado fresco, as quais dependem de fatores como: materiais empregados; forma de aplicação; e interação entre substrato e argamassa. Os ensaios utilizados para caracterização reológica das argamassas não contemplam as alterações que ocorrem devido o contato com o substrato, gerando discordâncias nas teorias sobre os fenômenos pelo qual ocorre a resistência de aderência. Sendo assim, o presente trabalho visa identificar as alterações do comportamento reológico de suspensões cimentícias aplicadas em substratos porosos por meio do ajuste do método do squeeze-flow. Para tanto, foram utilizadas duas configurações do squeeze-flow, com e sem confinamento do fluxo radial; três tipos de base, sendo uma metálica e duas porosas; e, pastas com diferentes materiais, a saber: cimento; cal e filler calcário. A escolha da pasta ao invés da argamassa foi basicamente por duas razões: primeiro, porque a pasta é a parcela da argamassa mais suscetível aos efeitos de sucção capilar do substrato; e segundo, para simplificar o cenário de análise, eliminando a variável areia. Ambas as configurações apresentaram-se viáveis na identificação da alteração do comportamento reológico da pasta...

Estudo da aplicação do processo Pin-in-Paste na montagem de placas de circuito impresso usando pasta de solda lead-free (SAC).; Study of the Pin-in-Paste process in the printed circuit board assembly using lead free solder paste (SAC).

Lima, Ricardo Barbosa de
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 31/10/2011 PT
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375.74188%
Neste trabalho foram estudadas as etapas de processo envolvidas na tecnologia Pin-in-Paste (PIP) de soldagem por refusão de componentes convencionais (THCs - Through Hole Components ou Componentes de Furo Passante) em placas de circuito impresso (PCIs), utilizando pasta de solda sem chumbo (lead-free) com liga SAC (Sn-Ag-Cu) de forma a atender as novas exigências ambientais para a montagem eletrônica. Inicialmente foi feito o projeto da PCI de teste com três diferentes componentes THCs e três componentes SMD com encapsulamentos distintos, com o objetivo de reproduzir uma PCI comercial. Foram gerados dois diâmetros de furos diferentes para inserir os THCs, possibilitando o estudo da variação de preenchimento com solda no PTH. Foi proposta uma equação para o cálculo do volume de pasta de solda a ser impresso sobre os furos no processo de montagem. A partir desta equação foram calculadas as dimensões dos furos do estêncil para a PCI de teste. Os parâmetros de impressão foram otimizados em função da variação de pressão e da velocidade do rodo. Duas curvas de refusão foram utilizadas, uma convencional e outra otimizada para verificar a variação na geração de defeitos. A impressão de pasta de solda ficou superior ao projetado...

Avaliação da alteração das propriedades da pasta de cimento em ambiente de repositório; Assessment of cement paste properties changes in repository environment

Ferreira, Eduardo Gurzoni Alvares
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 30/04/2013 PT
Relevância na Pesquisa
370.6261%
Pasta de cimento é um material comum em repositórios para rejeitos radioativos, atuando como material estrutural e de imobilização. Sua utilização como material de preenchimento em um repositório tipo poço tubular profundo para fontes seladas, no entanto, requer um maior tempo de vida útil do material. O conhecimento de seu comportamento em longo prazo é necessário para garantir a segurança da instalação em milhares de anos. O presente trabalho avaliou as alterações na pasta de cimento induzidas por fatores de degradação, como ataque de agentes agressivos, alta temperatura e presença de campo de radiação. Corpos de prova (cps) de pasta de cimento foram submetidos a ensaios acelerados de degradação e os efeitos deletérios foram avaliados por meio de ensaios de resistência mecânica, variação dimensional, lixiviação/penetração de íons, DRX, TGA e MEV. Observou-se que a hidratação dos cps foi beneficiada pela imersão (em água destilada ou em solução salina) e alta temperatura, resultando em uma resistência maior. O armazenamento à seco prejudicou a hidratação, mantendo a resistência mais baixa. O tempo de imersão e a irradiação não foram capazes de alterar a mineralogia e a resistência da pasta de cimento.; Cement paste is widely used in repositories for radioactive wastes...

Construção e otimização de um eletrodo de pasta de carbono modificado com óxido de manganês tipo espinélio dopado com cobalto (III) para determinação potenciométrica de íons lítio; Cosntruction and optimization of a carbon paste electrode modified with spinel type manganese oxide doped with cobalt (III) to potentiometric determination of lithium ions

Silva, Larissa Santos
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 19/09/2014 PT
Relevância na Pesquisa
363.6411%
Os efeitos terapêuticos dos sais de lítio são comprovados no tratamento de pacientes com depressão, certos tipos de câncer e transtornos bipolares de humor. A dosagem de lítio deve ser cuidadosamente controlada em cada paciente já que excessos na dosagem podem conduzir a danos irreversíveis no sistema nervoso e nos rins. Sendo assim é interessante produzir métodos de baixo custo, simples e rápidos que permitam o monitoramento desse íon. Portanto no presente trabalho foi estudado o desempenho potenciométrico de um eletrodo compósito de pasta de carbono modificado com óxido de manganês tipo espinélio dopado com cobalto (III). O eletrodo de pasta de carbono modificado foi preparado pela mistura de 55% (m/m) de pó de grafite, 20% (m/m) de aglutinante (óleo mineral) e 25% (m/m) de óxido de manganês dopado com cobalto (III) (Li1,05Co0,02Mn1,98O4.). O desempenho eletroquímico do eletrodo foi estudado através de voltametria cíclica (etapa de ativação) e cronopotenciometria (i=0) (etapas de estabilização e adição de padrão). Na caracterização eletroquímica do eletrodo estudou-se a melhor concentração de íons lítio para ativação do sensor, bem como a melhor velocidade de varredura, tempo de estabilização...

Effect of the consumption of tomato paste on plasma prostate-specific antigen levels in patients with benign prostate hyperplasia

Souza, Magda Edinger de; Koff, Walter Jose
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Artigo de Revista Científica Formato: application/pdf
ENG
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The consumption of tomatoes and tomato products has been associated with a reduced risk of prostate cancer. We observed a decrease of 10.77% in prostate-specific antigen (PSA) levels in patients with benign prostate hyperplasia who were submitted to daily ingestion of tomato paste. This was an experimental rather than a controlled study with a sample of 43 men ranging in age from 45 to 75 years, all with histological diagnoses of benign prostate hyperplasia and plasma PSA levels of 4-10 ng/mL. All patients received 50 g of tomato paste once a day for 10 consecutive weeks and PSA levels were analyzed before, during and after the consumption of tomato paste. ANOVA for repeated measures was used to compare PSA levels before, during and after the consumption of tomato paste. The mean ± SD PSA level was 6.51 ± 1.48 ng/mL at baseline and 5.81 ± 1.58 ng/mL (P = 0.005) after 10 weeks. Acceptance was good in 88.3, regular in 9.3, and poor in 2.3% of the patients. Dietary ingestion of 50 g of tomato paste per day for 10 weeks significantly reduced mean plasma PSA levels in patients with benign prostate hyperplasia, probably as a result of the high amount of lycopene in tomato paste. This was not a prostate cancer prevention study, but showed some action of tomato paste in prostate biology. The development of prostate cancer is typically accompanied by an increase in plasma PSA levels...

Voltammetric determination of isoprenaline in pharmaceutical preparations using a copper(II) hexacyanoferrate(III) modified carbon paste electrode

Bonifacio, V. G.; Marcolino, L. H.; Teixeira, MFS; Fatibello-Filho, O.
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 55-59
ENG
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The electroanalytical determination of isoprenaline in pharmaceutical preparations of a homemade carbon paste electrode modified with copper(II) hexacyanoferrate(III) (CuHCF) was studied by cyclic voltammetry. Several parameters were studied for the optimization of the sensor such as electrode composition, electrolytic solution, pH effect, potential scan rate and interferences in potential. The optimum conditions were found in an electrode composition (in mass) of 15% CuHCF, 60% graphite and 25% mineral oil in 0.5 mol l(-1) acetate buffer solution at pH 6.0. The analytical curve for isoprenaline was linear in the concentration range from 1.96 x 10(-4) to 1.07 x 10(-3) mol l(-1) with a detection limit of 8.0 x 10(-5) mol l(-1). The relative standard deviation was 1.2% for 1.96 x 10(-4) mol l(-1) isoprenaline solution (n=5). The procedure was successfully applied to the determination of isoprenaline in pharmaceutical preparations; the CuHCF modified carbon paste electrode gave comparable results to those results obtained using a UV spectrophotometric method. (C) 2004 Elsevier B.V. All rights reserved.

Determination of Analgesics (Dipyrone and Acetaminophen) in Pharmaceutical Preparations by Cyclic Voltammetry at a Copper(II) Hexacyanoferrate(III) Modified Carbon Paste Electrode

Teixeira, Marcos F. S.; Marcolino-Junior, Luiz H.; Fatibello-Filho, Orlando; Moraes, Fernando C.; Nunes, Ronaldo S.
Fonte: Bentham Science Publ Ltd Publicador: Bentham Science Publ Ltd
Tipo: Artigo de Revista Científica Formato: 303-310
ENG
Relevância na Pesquisa
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Processo FAPESP: 05/01296-4; Processo FAPESP: 06/07191-2; Copper(II) hexacyanoferrate(III) (CuHCF) modified carbon paste electrode was used for the electroanalytical determination of dipyrone and acetaminophen in pharmaceutical preparations by cyclic voltammetry. Several parameters were investigated for the optimization of the sensor such as composition of the electrode, electrolytic solution, effect of pH, scan rate of potential and interference. The best conditions were found for an electrode composition in mass of 20% CuHCF, 55% graphite and 25% mineral oil in acetate buffer containing 0.05 mol L(-1) of NaCl. The analytical curve was linear in the dipyrone and acetaminophen concentration ranged from 1.25 x 10(-5) mol L(-1) to 1.23 x 10(-3) and 2.84 x 10(-4) to 2.59 x 10(-3) mol L(-1) respectively, being successfully applied to the determination of dipyrone and acetaminophen in pharmaceutical preparations. The CuHCF modified carbon paste electrode presented comparable results to those obtained using iodimetry and ultraviolet spectrophotometry methods, respectively.

Compostos antioxidantes em polpa de tomte : efeito do processamento e da estocagem; Antioxidant compounds in tomato paste : effect of processing and storage

Adriana Barreto Alves
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 28/08/2009 PT
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Estudos epidemiológicos têm demonstrado que o consumo de frutas e vegetais tem um efeito benéfico na redução da incidência de várias doenças como o câncer e doenças cardiovasculares. Esse efeito tem sido relacionado com a presença de compostos antioxidantes nesses alimentos, sobretudo os flavonóides. O tomate (Lycopersicum esculentum Mill.) é um dos vegetais mais consumidos no mundo, in natura ou processado, e também é rico em compostos antioxidantes como carotenóides, vitaminas e flavonóides. Os alimentos processados, frequentemente, são tidos como menos nutritivos que os alimentos in natura, devido, principalmente, ao fato de que alguns nutrientes são degradados pelas altas temperaturas empregadas. Assim, torna-se importante avaliar o efeito do processamento e da estocagem sobre os compostos antioxidantes do tomate e também sobre sua atividade antioxidante. Um planejamento experimental foi realizado para otimizar as condições de extração dos compostos fenólicos e concentração dos flavonóides em polpa de tomate concentrada. O método otimizado foi validado para as determinações de compostos fenólicos totais e flavonóides totais por espectrofotometria e também para a determinação de flavonóides por cromatografia líquida de alta eficiência (CLAE). Os métodos espectrofotométricos foram validados nos parâmetros repetibilidade e exatidão. A determinação de flavonóides por CLAE foi validada nos parâmetros seletividade...

Effect of the consumption of tomato paste on plasma prostate-specific antigen levels in patients with benign prostate hyperplasia

Edinger,M.S.; Koff,W.J.
Fonte: Associação Brasileira de Divulgação Científica Publicador: Associação Brasileira de Divulgação Científica
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/08/2006 EN
Relevância na Pesquisa
373.00008%
The consumption of tomatoes and tomato products has been associated with a reduced risk of prostate cancer. We observed a decrease of 10.77% in prostate-specific antigen (PSA) levels in patients with benign prostate hyperplasia who were submitted to daily ingestion of tomato paste. This was an experimental rather than a controlled study with a sample of 43 men ranging in age from 45 to 75 years, all with histological diagnoses of benign prostate hyperplasia and plasma PSA levels of 4-10 ng/mL. All patients received 50 g of tomato paste once a day for 10 consecutive weeks and PSA levels were analyzed before, during and after the consumption of tomato paste. ANOVA for repeated measures was used to compare PSA levels before, during and after the consumption of tomato paste. The mean ± SD PSA level was 6.51 ± 1.48 ng/mL at baseline and 5.81 ± 1.58 ng/mL (P = 0.005) after 10 weeks. Acceptance was good in 88.3, regular in 9.3, and poor in 2.3% of the patients. Dietary ingestion of 50 g of tomato paste per day for 10 weeks significantly reduced mean plasma PSA levels in patients with benign prostate hyperplasia, probably as a result of the high amount of lycopene in tomato paste. This was not a prostate cancer prevention study, but showed some action of tomato paste in prostate biology. The development of prostate cancer is typically accompanied by an increase in plasma PSA levels...

The influence of paste feed on the minimum spouting velocity

Spitzner Neto,P.I.; Cunha,F.O.; Freire,J.T.
Fonte: Brazilian Society of Chemical Engineering Publicador: Brazilian Society of Chemical Engineering
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/09/2001 EN
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Due to the lack of reliable mathematical models for predicting the minimum spouting velocity in spouted bed dryers, in this work a new model is proposed that takes into account the effects of adhesive forces acting on particle agglomerates due to the presence of pastes. The results are compared with experimental data reported by Spitzner and Freire (2001), obtained by the continuous feeding of egg paste into a spouted bed, and with additional data obtained for batch feeding of glycerol into the same bed. The equipment was a conical spouted bed with a 0.05 m inlet diameter, a 60° cone angle, and a 0.21 m cone height. Glass spheres with a diameter of 2.6x10-3 m were used as inert particles. It was observed that as saturation increases, the minimum spouting velocity increases for egg paste and decreases for glycerol. The results indicate that there are different forces acting on the bed of particles depending on the paste and operating conditions. The mathematical model provided good predictions only for egg paste, although the values for minimum spouting velocity were slightly overestimated.

Improvement of metallic joint electrical conductivity using a novel conductive paste produced from recycled residues

Souza,Erivelto Luís de; Gomes,José Emanuel L.; Araújo,Fernando Gabriel S.; Oliveira,Cristovam Paes de
Fonte: Escola de Minas Publicador: Escola de Minas
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2006 EN
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In industry, the transmission of electricity usually requires high currents transported for very long distances, and in some cases, such as in aluminum plants, the use of high currents is essential for the reduction process. The connections between the electrical furnaces and the transmission cables are made with busbars, which can be comprised of either one or two different types of metal. In this transmission process, the main method to upgrade electrical circuit performance is by improving conductivity at the joint interface. Due to the need to reduce cost and simplify maintenance procedures, the interfaces at the joints are simply brushed, and conductive pastes are pressed between the contacting metals. The material most commonly used is a high-cost graphite paste, which is not produced by any Brazilian company. This paper presents a novel conductive paste, easily elaborated from industrial residues, involving low-cost production, yet presenting better results than those obtained with the graphite paste.

Lysanda paste: a new option for root-end filling

Bernardineli,Norberti; Bramante,Clovis Monteiro; Moraes,Ivaldo Gomes de; Garcia,Roberto Brandão
Fonte: Faculdade De Odontologia De Bauru - USP Publicador: Faculdade De Odontologia De Bauru - USP
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/08/2007 EN
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This study aimed to compare the apical sealing of root-end fillings performed with Lysanda (zinc oxide-eugenol paste) with radiopacifiers (iodoform or zinc oxide) and calcium hydroxide. Root-end cavities were prepared and filled with different materials, as follows: Group I - Lysanda paste with iodoform; Group II - Lysanda paste with iodoform and calcium hydroxide; Group III - Lysanda paste with iodoform and zinc oxide; Group IV - Lysanda paste with zinc oxide; Group V - mineral trioxide aggregate (MTA). After filling, the teeth were immersed in 2% methylene blue for analysis of marginal leakage. It was observed that marginal leakage occurred in all groups. Lysanda paste with iodoform showed the lowest leakage, with no statistically significant difference compared to the other groups. All materials can be considered as good options for root-end filling.

Paste drying control in a rotating-distributor fluidized bed

Gómez Hernández, Jesús
Fonte: Universidade Carlos III de Madrid Publicador: Universidade Carlos III de Madrid
Tipo: Tese de Doutorado
ENG
Relevância na Pesquisa
368.94453%
Fluidized beds are used for a wide variety of processes due to its high rates of heat and mass transfer. Due to that, fluidized beds are used for a variety of applications ranging from the gasification or combustion of biomass, to coating and drying processes. All these industrial applications show the main influence of the zone close to the distributor on the bed dynamics. In this way, a non-homogeneous mixing in this zone between dense and gas phases leads to fluidization problems such as segregation of particles, formation of dead zones, heterogeneous distribution of temperatures inside the bed and appearance of channels or preference paths for the flowing fluidization gas. These phenomena usually cause the process stop or the bed defluidization, which increase operational costs. Therefore, it is necessary to study the bed dynamics in order to be able to detect these fluidization problems, and modify somehow the hydrodynamic structure of the bed. This PhD thesis develops the methods needed to study and control the behaviour of a bed equipped with a rotating distributor as a tool to change the bed dynamics. These approaches were developed using a lab-scale facility with an electrical motor coupled to the distributor...

Antibacterial activity of root canal filling materials for primary teeth: zinc oxide and eugenol cement, Calen paste thickened with zinc oxide, Sealapex and EndoREZ

QUEIROZ, Alexandra Mussolino de; NELSON FILHO, Paulo; SILVA, Léa Assed Bezerra da; ASSED, Sada; SILVA, Raquel Assed Bezerra da; ITO, Izabel Yoko
Fonte: Fundação Odontológica de Ribeirão Preto Publicador: Fundação Odontológica de Ribeirão Preto
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
366.7205%
This study evaluated in vitro the antibacterial activity of 4 root canal filling materials for primary teeth - zinc oxide and eugenol cement (ZOE), Calen paste thickened with zinc oxide (Calen/ZO), Sealapex sealer and EndoREZ sealer - against 5 bacterial strains commonly found in endodontic infections (Kocuria rhizophila, Enterococcus faecalis, Streptococcus mutans, Escherichia coli and Staphylococcus aureus) using the agar diffusion test (agar-well technique). Calen paste, 1% chlorhexidine digluconate (CHX) and distilled water served as controls. Seven wells per dish were made at equidistant points and immediately filled with the test and control materials. After incubation of the plates at 37oC for 24 h, the diameter of the zones of bacterial growth inhibition produced around the wells was measured (in mm) with a digital caliper under reflected light. Data were analyzed statistically by analysis of variance and Tukey's post-hoc test (?=0.05). There were statistically significant differences (p<0.0001) among the zones of bacterial growth inhibition produced by the different materials against all target microorganisms. K. rhizophila was inhibited more effectively (p<0.05) by ZOE, while Calen/ZO had its highest antibacterial activity against E. faecalis (p<0.05). S. mutans was inhibited by Calen/ZO...

Analysis of the effects of the continuous electrode paste band on precordial leads of the electrocardiogram

Petterson,Carlos Henrique Purper; Koehler,Nelson Rudi; Passos,Ronaldo; Christmann,Iuri
Fonte: Sociedade Brasileira de Cardiologia - SBC Publicador: Sociedade Brasileira de Cardiologia - SBC
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/09/1999 EN
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OBJECTIVE - To determine if the application of a continuous electrode paste band on precordial leads results in alteration of the electrocardiographic tracing as compared with an adequate amount of electrode paste, and if the former condition does not cause uniform morphologies from V1 to V6. METHODS - The amplitude and morphology of the electrocardiographic waves on the precordial leads in electrocardiographic tracings, which were performed with standard (control group) or excessive (continuous band) application of the electrode paste, were compared. RESULTS - None of the 106 patients studied showed uniformity of the QRS morphology from V1 to V6. The eletrocardiographic alterations identified in the tracings performed with a continuous electrode paste band that showed statistical significance in relation to the control group were the following: inversion of the P wave in V1; inversion of the T wave in V1, V2, and V3; appearance of R' waves in V1 and V2; disappearance of S waves in V1; appearance of S waves in V5 and V6; alterations in the amplitude of almost all waves, in all leads. CONCLUSION - Application of a continuous electrode paste band in the precordial leads may cause significant alterations in the electrocardiographic tracing obtained.

Antibacterial activity of root canal filling materials for primary teeth: zinc oxide and eugenol cement, Calen paste thickened with zinc oxide, Sealapex and EndoREZ

Queiroz,Alexandra Mussolino de; Nelson Filho,Paulo; Silva,Léa Assed Bezerra da; Assed,Sada; Silva,Raquel Assed Bezerra da; Ito,Izabel Yoko
Fonte: Fundação Odontológica de Ribeirão Preto Publicador: Fundação Odontológica de Ribeirão Preto
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2009 EN
Relevância na Pesquisa
366.7205%
This study evaluated in vitro the antibacterial activity of 4 root canal filling materials for primary teeth - zinc oxide and eugenol cement (ZOE), Calen paste thickened with zinc oxide (Calen/ZO), Sealapex sealer and EndoREZ sealer - against 5 bacterial strains commonly found in endodontic infections (Kocuria rhizophila, Enterococcus faecalis, Streptococcus mutans, Escherichia coli and Staphylococcus aureus) using the agar diffusion test (agar-well technique). Calen paste, 1% chlorhexidine digluconate (CHX) and distilled water served as controls. Seven wells per dish were made at equidistant points and immediately filled with the test and control materials. After incubation of the plates at 37oC for 24 h, the diameter of the zones of bacterial growth inhibition produced around the wells was measured (in mm) with a digital caliper under reflected light. Data were analyzed statistically by analysis of variance and Tukey's post-hoc test (?=0.05). There were statistically significant differences (p<0.0001) among the zones of bacterial growth inhibition produced by the different materials against all target microorganisms. K. rhizophila was inhibited more effectively (p<0.05) by ZOE, while Calen/ZO had its highest antibacterial activity against E. faecalis (p<0.05). S. mutans was inhibited by Calen/ZO...

The effect of mixing on the extrusion-spheronisation of a micro-crystalline cellulose paste

Bryan, M. P.; Kent, M. D.; Rickenbach, J.; Rimmer, G.; Wilson, D. I.; Rough, S. L.
Fonte: Elsevier Publicador: Elsevier
Tipo: Article; accepted version
EN
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This is the accepted manuscript. It is currently embargoed until 18/12/2015. The final version is available from Elsevier at http://www.sciencedirect.com/science/article/pii/S0378517314009259; The effect of mixer shear strain rate on the performance of a model micro-crystalline cellulose pharmaceutical paste undergoing extrusion?spheronisation was studied using a laboratory scale planetary mixer and a screw-based mixer. The maximum shear strain rate in each mixer was estimated. Five pastes were prepared, one each at 97 and 265 s?1 in the planetary mixer, and one each at 304, 988 and 2220 s?1 in the screw mixer. The rheology of the pastes was quantified by Benbow?Bridgwater characterisation based on ram extrusion. Each paste was spheronised and pellet size and shape distributions obtained by automated size analysis. Mixer type (rather than shear strain rate) was found to have the strongest influence on the paste properties, with the screw-mixed material having a higher yield strength and forming smaller pellets with a narrower size distribution when spheronised under identical conditions.; Support for MPB is gratefully received from Sandvik Hyperion and Ceratizit GmbH.

Lysanda paste: a new option for root-end filling

Bernardineli, Norberti; Bramante, Clovis Monteiro; Moraes, Ivaldo Gomes de; Garcia, Roberto Brandão
Fonte: Universidade de São Paulo. Faculdade de Odontologia de Bauru Publicador: Universidade de São Paulo. Faculdade de Odontologia de Bauru
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; ; Formato: application/pdf
Publicado em 01/08/2007 ENG
Relevância na Pesquisa
371.9421%
This study aimed to compare the apical sealing of root-end fillings performed with Lysanda (zinc oxide-eugenol paste) with radiopacifiers (iodoform or zinc oxide) and calcium hydroxide. Root-end cavities were prepared and filled with different materials, as follows: Group I - Lysanda paste with iodoform; Group II - Lysanda paste with iodoform and calcium hydroxide; Group III - Lysanda paste with iodoform and zinc oxide; Group IV - Lysanda paste with zinc oxide; Group V - mineral trioxide aggregate (MTA). After filling, the teeth were immersed in 2% methylene blue for analysis of marginal leakage. It was observed that marginal leakage occurred in all groups. Lysanda paste with iodoform showed the lowest leakage, with no statistically significant difference compared to the other groups. All materials can be considered as good options for root-end filling.

Effect of solder paste and surface finish on 0201 assembly process defects

Newasekar, Rahul; Ramkumar, S. Manian
Fonte: SMTA: SMTA International Conference Proceedings Publicador: SMTA: SMTA International Conference Proceedings
Tipo: Proceedings
EN_US
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The trend towards smaller, faster and cheaper electronic devices has led to an increase in the use of 0201 and even smaller sized passive components. The size advantages of 0201 components make it a popular choice among design engineers but not among manufacturing engineers. From a manufacturing perspective, the size of the 0201 package poses significant challenges to the printed circuit board (PCB) assembly process. The many challenges with 0201 assembly process can be attributed to the solder paste volume, pad design, aperture design, board finish, solder paste type, pick and place accuracy and reflow profile. This study discusses in detail the effect of solder paste, board finish, and pad-aperture shape on 0201 assembly process defects, specifically lead-free paste and lead-free surface finishes. To investigate these parameters, a Design of Experiment study was carried out at the Center for Electronics Manufacturing and Assembly at the Rochester Institute of Technology.; "Effect of Solder Paste and Surface Finish on 0201 Assembly Process Defects," SMTA International Conference Proceedings. Held in Chicago, IL: 21-25 September 2004

Khumani Iron Ore Mine paste disposal and water recovery system

du Toit,T; Crozier,M
Fonte: Journal of the Southern African Institute of Mining and Metallurgy Publicador: Journal of the Southern African Institute of Mining and Metallurgy
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/03/2012 EN
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Traditional iron ore beneficiation plants using washing, screening, and jigging processes require large volumes of process water. However, when a suitable large iron ore deposit is found in a location where rainfall is erratic and raw water sources are limited, innovative process designs are required to minimize water losses, maximize re-use of process water, and minimize raw water intake to ensure the project viability. This case study provides an overview of the Khumani paste disposal facility (PDF) located in the Northern Cape Province of South Africa. The plant uses a central ring main water reticulation circuit combined with a two-stage thickening system to maximize water recovery. At the process plant there are two large 90 m diameter traction thickeners and at the PDF two 18 m paste thickeners. The net raw water usage has been minimized, and water losses on the PDF are at levels of between 0.43 to 0.69 m³/t deposited.S