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In vitro tests to establish LC(50) and discriminating concentrations for fipronil against Rhipicephalus (Boophilus) microplus (Acari: Ixodidae) and their standardization

CASTRO-JANER, E.; RIFRAN, L.; PIAGGIO, J.; GIL, A.; MILLER, R. J.; SCHUMAKER, T. T. S.
Fonte: ELSEVIER SCIENCE BV Publicador: ELSEVIER SCIENCE BV
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.15%
Laboratory test was carried out on larvae and adults of the cattle tick, Rhipicephalus (Boophilus) microplus, to determine fipronil toxicity. Adult immersion test (AIT, N = 26), larval immersion test (LIT, N = 71) and larval packet test (LPT, N = 41) were standardized using susceptible strain (Mozo). Dose-response curves were compared with a fipronil resistant strain. Four variables were analyzed from AIT results: mortality, weight of eggs on day 7 and on day 14, index of fertility, and index of fecundity. For larval test, dose mortality curves were analyzed. In spite of the high LC(50) variability, all variables determined for AIT were appropriate to discriminate both strains. AIT and LIT had more sensitivity than LPT, with larger resistance factors. It was used two times LC(99.9) as discriminating doses (DCs) following FAO suggestion. For mortality by AIT, LIT and LPT the DCs were estimated: 4.98 ppm, 7.64 ppm and 2365.8 ppm, respectively, for Mozo strain. DCs mortality values estimated for resistant strain by AIT, LIT and LPT were: 6.96 x 10(5) ppm, 343.26 ppm and 5.7 x 10(3) ppm, respectively and their respective resistant factors were: 202.4, 5.36 and 1.52. Protocols for AIT, LIT and LPT have been presented in this paper. (C) 2009 Elsevier B.V. All rights reserved.; INIA-FPTA; INIA-FPTA; FAPESP (Brazil); Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Applicability of in vitro bioassays for the diagnosis of ivermectin resistance in Rhipicephalus microplus (Acari: Ixodidae)

Klafke, Guilherme Marcondes; Janer, Eleonor Adega Castro; Mendes, M. C.; Namindome, A.; Schumaker, Teresinha Tizu Sato
Fonte: ELSEVIER SCIENCE BV; AMSTERDAM Publicador: ELSEVIER SCIENCE BV; AMSTERDAM
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
36.25%
The applicability of laboratory bioassays to diagnose ivermectin (IVM) resistance in Rhipicephalus microplus was evaluated. Adult immersion tests (AITs), larval immersion tests (LITs) and larval packet tests (LPTs) were performed to characterise the effects of ivermectin toxicity on adults and larvae of a susceptible reference strain. The AIT was determined to be a reasonable assay but requires a large number of individuals to attain interpretable results. The LIT and LPT were validated with an IVM resistant strain, revealing resistance ratios (RRs) of 6.73 and 1.49, respectively. In a field survey, nine different populations of cattle tick from the states of Sao Paulo and Mato Grosso do Sul, Brazil, were analysed with the LIT. Populations without previous exposure to ivermectin exhibited RRs between 0.87 and 1.01. Populations previously exposed to IVM showed RRs between 1.83 and 4.62. The LIT was more effective at discriminating between resistant and susceptible populations than the LPT. The use of the LIT is recommended for the diagnosis of ivermectin resistance in R microplus. (C) 2011 Elsevier B.V. All rights reserved.; CNPq; FAPESP, Brazil [2007/56082-4]; INIA-FPTA, Uruguay [243]

Avaliação da corrosividade do biodiesel por técnicas gravimétricas e eletroquímicas.; Evaluation of biodiesel corrosiveness by gravimetric and electrochemical techniques.

Aquino, Isabella Pacifico
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 24/01/2012 PT
Relevância na Pesquisa
46.4%
A corrosão provocada pelo biodiesel é um problema relevante associado à incompatibilidade do biodiesel com diversos materiais metálicos e poliméricos, sendo de suma importância quanto à durabilidade dos motores automotivos. O objetivo deste trabalho foi avaliar a corrosividade do biodiesel sobre os metais presentes no circuito de combustível dos motores que trabalham segundo o ciclo diesel aplicando técnicas gravimétricas e eletroquímicas. Todos os ensaios foram realizados em biodiesel puro obtido pela reação de transesterificação do óleo de soja refinado com etanol na presença de um catalisador alcalino. Foi avaliada a influência de dois métodos de purificação na corrosividade do biodiesel. A corrosividade do biodiesel e a degradação após contato com os íons metálicos foram avaliadas bem como em função da incidência de luz natural, temperatura e disponibilidade de oxigênio. Os resultados foram comparados com um biodiesel comercial fornecido pela Petrobrás. Ensaios de perda de massa segundo as normas ASTM G1 e ASTM G31 foram realizados para determinar a taxa de corrosão para cada metal nas diferentes condições de incidência de luz e temperatura. Na caracterização eletroquímica foi empregada a técnica de espectroscopia de impedância eletroquímica para avaliar o comportamento de corrosão dos metais em contato com o biodiesel puro...

Efeitos da imersão no meio líquido na recuperação de exercício físico anaeróbico sobre o desempenho e o comportamento de parâmetros fisiológicos de atletas; Effects of immersion during recovery from anaerobic exercise about physical performance and physiological variables

Coertjens, Marcelo
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Dissertação Formato: application/pdf
POR
Relevância na Pesquisa
36.32%
Introdução: Existem dúvidas quanto à validade da utilização da imersão no meio líquido como recurso para acelerar o período de recuperação passiva após a realização de exercícios anaeróbicos. Objetivo: Verificar se a imersão no meio líquido em diferentes temperaturas acelera a recuperação de variáveis fisiológicas após exercício anaeróbico e melhora o desempenho físico subseqüente. Métodos: 16 ciclistas e 5 triatletas treinados do sexo masculino (idade: 26,9 ± 5,8 anos, massa corporal: 72,3 ± 7,9 kg e estatura: 175,7 ± 7,7 cm) foram convidados para três visitas ao laboratório. Em cada visita foram realizados dois Testes de Wingate (TW) em cicloergômetro seguidos por recuperação passiva que poderia ser fora da água, imerso a 20ºC ou a 40ºC com duração de 10 minutos. Para cada visita foi realizado um tipo de recuperação previamente randomizado. Valores de constante de tempo (CT), média do último minuto de recuperação (Média_10min) e área foram calculados para variáveis ventilatórias consumo de oxigênio (VO2), produção de dióxido de carbono (VCO2), volume expirado (VE), taxa de troca respiratória (TTR) e freqüência cardíaca (FC). Amostras de sangue foram coletas para análise do lactato [LAC] sangüíneo em intervalos de 2 min. Valores de pico de potência (PP)...

Tests to determine LC50 and discriminating doses for macrocyclic lactones against the cattle tick, Boophilus microplus

Sabatini, G. A.; Kemp, D. H.; Hughes, S.; Nari, A.; Hansen, J.
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 53-62
ENG
Relevância na Pesquisa
36.27%
Laboratory tests were carried out on larvae and adults of the cattle tick Boophilus microplus to determine the toxicity of macrocyclic lactone acaricides (MLs). Technical and commercial MLs were used in larval packet test (LPT), larval immersion test (LIT) and adult immersion test (AIT). Tn LIT and AIT the toxicity of MLs was much higher than for LPT. In the AIT, diluting the injectable formulation of MLs in water was as effective as dilution in ethanol + Triton X-100. LC50, LC99.9 and 95% confidence limits were determined so that a discriminating dose (DD) could be set for larval and adult tests in order to diagnose potential resistance to MLs in field samples of the tick. These DDs are for Australian strains of B. microplus and may not be suitable for other strains until further work is carried out.The value of these diagnostic tests can only be verified if or when resistance to MLs emerges in ticks. (C) 2001 Elsevier B.V. B.V. All rights reserved.

Effects of high temperature plasma immersion ion implantation on wear resistance of Ti-Si-B sintered alloys

Fernandes, Bruno Bacci; Oliveira, Rogério Moraes; Ueda, Mário; Mariano, Samantha de Fátima Magalhães; Ramos, Alfeu Saraiva; Vieira, Maxson Souza; de Melo, Francisco Cristóvão Lourenço; de Oliveira, Guilherme
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 195-200
ENG
Relevância na Pesquisa
36.2%
Although titanium and its alloys own good mechanical properties and excellent corrosion resistance, these materials present poor tribological properties for specific applications that require wear resistance. In order to produce wear-resistant surfaces, this work is aimed at achieving improvement of wear characteristics in Ti-Si-B alloys by means of high temperature nitrogen plasma immersion ion implantation (PIII). These alloys were produced by powder metallurgy using high energy ball milling and hot pressing. Scanning electron microscopy (SEM) and X-ray diffraction identified the presence of α-titanium, Ti6Si2B, Ti5Si3, TiB and Ti3Si phases. Wear tests were carried out with a ball-on-disk tribometer to evaluate the friction coefficient and wear rate in treated and untreated samples. The worn profiles were measured by visible light microscopy and examined by SEM in order to determine the wear rates and wear mechanisms. Ti-7.5Si-22.5B alloy presented the highest wear resistance amongst the untreated alloys produced in this work. High temperature PIII was effective to reduce the wear rate and friction coefficient of all the Ti-Si-B sintered alloys. © 2013 Elsevier B.V.

Corrosion behavior of mild steel and SS 304L in presence of dissolved nickel under aerated and deaerated conditions

Mobin,Mohd; Shabnam,Hina
Fonte: ABM, ABC, ABPol Publicador: ABM, ABC, ABPol
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2011 EN
Relevância na Pesquisa
36.42%
In dual purpose water/power co-generation plants, the presence of high concentration of Cu and Ni in the re-circulating brine/condensate as a result of condenser tubes corrosion has been attributed as one of the several causes of corrosion damage of flash chamber materials and water touched parts of the boilers. The present investigation deals with the effect of dissolved nickel in the concentration range of 10 ppb to 100 ppm on the corrosion behavior of mild steel and SS 304L in two aqueous medium namely, distilled water and artificial seawater. The effect of pH, dissolved oxygen and flow condition of aqueous medium on the corrosion behavior was also monitored. The experimental techniques include immersion test and electrochemical tests which include free corrosion potential measurements and potentiodynamic polarization measurements. The corrosion rate of mild steel and SS 304L under different experimental conditions was determined by weight loss method and spectrophotometric determination of iron ion entered into the test solution during the period of immersion. The pH of the test solution was also monitored during the entire period of immersion. The left over nickel ions present in the test solution after completion of immersion was also estimated using Atomic Absorption Spectrophotometer. The surface morphology of the corroded steel surface was also examined using scanning electron microscopy (SEM). The results of the studies show that SS 304L largely remains unaffected in both distilled water and artificial seawater under different experimental conditions. However...

Effect of repeated immersion solution cycles on the color stability of denture tooth acrylic resins

Silva,Paulo Maurício Batista da; Acosta,Emílio José Tabaré Rodríguez; Jacobina,Matheus; Pinto,Luciana de Rezende; Porto,Vinícius Carvalho
Fonte: Faculdade De Odontologia De Bauru - USP Publicador: Faculdade De Odontologia De Bauru - USP
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2011 EN
Relevância na Pesquisa
36.32%
OBJECTIVE: Chemical solutions have been widely used for disinfection of dentures, but their effect on color stability of denture tooth acrylic resins after repeated procedures is still unclear. The aim of this in vitro study was to evaluate whether repeated cycles of chemical disinfectants affected the color stability of two denture tooth acrylic resins. MATERIAL AND METHODS: Sixty disc-shaped specimens (40 mm x 3 mm) were fabricated from two different brands (Artiplus and Trilux) of denture tooth acrylic resin. The specimens from each brand (n=30) were randomly divided into 6 groups (n=5) and immersed in the following solutions: distilled water (control group) and 5 disinfecting solutions (1% sodium hypochlorite, 2% sodium hypochlorite, 5.25% sodium hypochlorite, 2% glutaraldehyde, and 4% chlorhexidine gluconate). Tooth color measurements were made by spectrophotometry. Before disinfection, the initial color of each tooth was recorded. Further color measurements were determined after subjecting the specimens to 7, 21, 30, 45, 60, and 90 immersion cycles in each tested solution. Color differences (ΔE*) were determined using the CIE L*a*b* color system. Data were analyzed using two-way repeated measures analysis of variance (ANOVA) followed by Tukey tests. The significance level was set at 5%. RESULTS: There were statistically significant differences in ΔE* among the 5 disinfectants and water during the 90 cycles of immersion for both denture tooth acrylic resins. Distilled water promoted the greatest color change in both denture tooth acrylic resins...

Analgesic and Anti-Inflammatory Properties of Gelsolin in Acetic Acid Induced Writhing, Tail Immersion and Carrageenan Induced Paw Edema in Mice

Gupta, Ashok Kumar; Parasar, Devraj; Sagar, Amin; Choudhary, Vikas; Chopra, Bhupinder Singh; Garg, Renu; ., Ashish; Khatri, Neeraj
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 14/08/2015 EN
Relevância na Pesquisa
36.14%
Plasma gelsolin levels significantly decline in several disease conditions, since gelsolin gets scavenged when it depolymerizes and caps filamentous actin released in the circulation following tissue injury. It is well established that our body require/implement inflammatory and analgesic responses to protect against cell damage and injury to the tissue. This study was envisaged to examine analgesic and anti-inflammatory activity of exogenous gelsolin (8 mg/mouse) in mice models of pain and acute inflammation. Administration of gelsolin in acetic acid-induced writhing and tail immersion tests not only demonstrated a significant reduction in the number of acetic acid-induced writhing effects, but also exhibited an analgesic activity in tail immersion test in mice as compared to placebo treated mice. Additionally, anti-inflammatory function of gelsolin (8 mg/mouse) compared with anti-inflammatory drug diclofenac sodium (10 mg/kg)] was confirmed in the carrageenan injection induced paw edema where latter was measured by vernier caliper and fluorescent tomography imaging. Interestingly, results showed that plasma gelsolin was capable of reducing severity of inflammation in mice comparable to diclofenac sodium. Analysis of cytokines and histo-pathological examinations of tissue revealed administration of gelsolin and diclofenac sodium significantly reduced production of pro-inflammatory cytokines...

A comparison of three different methodologies for evaluating Rhipicephalus (Boophilus) rnicroplus susceptibility to topical spray compounds

Correa, Rafael Rodrigues; Zanetti Lopes, Welber Daniel; Pires Teixeira, Weslen Fabricio; Cruz, Breno Cayeiro; Costa Gomes, Lucas Vinicius; Felippelli, Gustavo; Maciel, Willian Giquelin; Favero, Flavia Carolina; Buzzulini, Carolina; Bichuette, Murilo Abud;
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 115-124
ENG
Relevância na Pesquisa
36.46%
This study aimed to compare three different methodologies (Adult Immersion Tests, field trials with naturally infected animals, and a Stall Test using artificially infested cattle) to evaluate the efficacy of two topical formulations that we administered as whole body sprays (15% Cypermethrin + 30% Chlorpyriphos + 15% Fenthion-Colosso (R) FC 30, Ouro Fino Agronegocios; and 60% Dichlorvos + 20% Chlorpyriphos-Ectofos (R), Vallee Saude Animal Ltd.), against a susceptible strain of Rhipicephalus (Boophilus) microplus. To achieve this objective, two natural infestation trials were conducted, as well as two artificial infestation trials (Stall Tests) and two Adult Immersion Tests (AIT). The AIT results showed that both spray formulations achieved 100% efficacy against R. (B.) micro plus fully engorged females. However, when observing results obtained by field trials (natural infestations) and Stall Tests, none of these topically applied compounds reached 100% efficacy or affected the reproductive capacity of the fully engorged female ticks. Additional studies must be conducted to compare these in vivo methodologies with different in vitro techniques, such as the Larval Packet Test. However, based on results obtained here, we can conclude that depending on the spray formulations used...

Understanding Reading Comprehension in English Immersion Students in China

Li, Miao
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado
EN; EN
Relevância na Pesquisa
36.3%
Compared to research on English as a First Language (EL1) reading comprehension, there is a dearth of studies investigating English as a Second Language (ESL) reading comprehension. This dissertation reports findings from two studies which examined the cognitive processes underlying English reading comprehension in Chinese ESL students. Two-hundred and forty six Grade 8 students in an English immersion program in a junior middle school in China were administered a battery of reading-related and reading comprehension tests. The first study investigated the cognitive predictors of English reading comprehension in these students. It tested whether the Simple View of Reading model (Gough & Tunmer, 1986) applied to Chinese ESL students and whether the effects of breadth and depth of vocabulary contributed to different levels of reading comprehension. The results showed that the Simple View of Reading model did not predict Chinese English-immersion students’ reading comprehension well. Vocabulary as well as inference and strategy added further variance to the general understanding of text. Vocabulary breadth and depth explained unique variance in reading comprehension, with vocabulary breadth contributing more to general understanding of text and vocabulary depth to deep processing of text. The second study explored characteristics of reading comprehension difficulties among Chinese English-immersion students. Three groups of comprehenders matched on age...

Respostas fisiológicas e comportamentais de recém-nascidos pré-termos submetidos a duas técnicas de banho de imersão: ensaio clínico cruzado; Physiological and behavioral responses of preterm newborn underwent to two immersion baths techniques: cross-over clinical trial

Freitas, Patricia de
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 28/05/2015 PT
Relevância na Pesquisa
36.35%
Introdução: a revisão de literatura aponta que os recém-nascidos submetidos ao banho de imersão produzem menor variação térmica pós-banho comparado aos submetidos ao banho com esponja. No Brasil, o Ministério da Saúde vem capacitando profissionais que atuam em unidades de internação neonatal para implementar o Método Mãe Canguru e, entre outras práticas, recomenda que o recém-nascido pré-termo (RNPT) e com baixo peso seja submetido ao banho de imersão envolto em cueiro ou lençol, sugerindo mudança da prática hegemônica do banho com esponja ou banho de imersão convencional. No entanto, a técnica de banho de imersão recomendada carece de evidências científicas quanto a sua segurança em relação às repercussões na estabilidade da temperatura corporal (T), frequência cardíaca (FC), cortisol salivar (CS) e comportamental em RNPT. Hipótese: os RNPT submetidos ao banho de imersão envoltos em lençol (BIE) apresentam respostas fisiológicas e comportamentais similares aos submetidos à técnica de banho de imersão convencional (BIC), nos primeiros 20 minutos pós-banho. Objetivo: avaliar os parâmetros fisiológicos e comportamentais de RNPT submetidos ao banho de imersão envolto em lençol (BIE) e banho de imersão convencional (BIC). Método: ensaio clínico randomizado cruzado com amostra composta por 43 RNPT...

Evaluation of apatite ceramics containing alpha-tricalcium phosphate by immersion in simulated body fluid

Hirakata, Luciana Mayumi; Kon, Masayuki; Asaoka, Kenzo
Fonte: IOS Press; Porto Alegre Publicador: IOS Press; Porto Alegre
Tipo: Artigo de Revista Científica
EN_US
Relevância na Pesquisa
36.25%
The purpose of this study was to estimate the availability of alpha-tricalcium phosphate (alpha-TCP) on/in hydroxyapatite (HAP) ceramics for bioactivity as bone-substitute materials by immersion in a simulated body fluid (SBF; Hanks' solution) containing ion concentrations similar to those in human blood plasma. Two alpha-TCP-surface-modified HAP and alpha-TCP-HAP composite materials were prepared by orthophosphoric acid treatment of sintered HAP and controlling the crystal phases of calcium phosphate cement, respectively. After immersion in SBF, the sintered HAP modified on the surface in an approximately 0.2 microm alpha-TCP layer was more effective for the precipitation of carbonated apatites than an approximately 2 microm alpha-TCP layer and HAP-only layer. In the calcium phosphate cements consisting of HAP and alpha-TCP phases, after immersion for 1 week, the specimens precipitated large amounts of apatites having alpha-TCP contents of approximately 25% and 50% in the cement. The results of immersion tests imply the possibility that the alpha-TCP on/in HAP ceramics may be a bioactive agent for bone-substituting HAP materials

Impact strength of denture base and reline acrylic resins subjected to long-term water immersion

Wady,Amanda Fucci; Machado,Ana Lucia; Vergani,Carlos Eduardo; Pavarina,Ana Cláudia; Giampaolo,Eunice Teresinha
Fonte: Fundação Odontológica de Ribeirão Preto Publicador: Fundação Odontológica de Ribeirão Preto
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2011 EN
Relevância na Pesquisa
36.2%
Water may influence the mechanical properties of the acrylic resins. Thus, the effect of water storage on the impact strength (IS) of one denture base (Lucitone 550 - L) and four reline resins (Tokuyama Rebase II - T; UfiGel Hard - U; Kooliner - K; New Truliner - NT) was evaluated. Bars of L were made (60 x 6 x 2 mm) and relined (2 mm) with T, U, K, NT and L. Intact specimens of each material (60 x 6 x 4 mm) were also fabricated for comparative purposes. Specimens were submitted to Charpy impact tests without water storage (control) and after immersion in water for 7, 90 and 180 days. Data (kJ/m²) analyzed by two-way ANOVA and Tukey's test (p=0.05) revealed that after 90 days, U exhibited an increase in the IS (0.93) compared to 7 days (0.58). K (1.48) and L/K (7.21) exhibited a decrease at the 7-day period (1.01 and 3.23, respectively). NT (0.60) showed an increase in the IS after 180 days (1.52), whereas L/NT (7.70) showed a decrease (3.17). Water immersion improved the IS of U and NT, and decreased the IS of K, L/K, and L/NT. Water may affect differently the IS of acrylic resins and, consequently, the resistance to fracture of relined denture bases.

Flexural strength of fluorapatite-leucite and fuorapatite porcelains exposed to erosive agents in cyclic immersion

Junpoom,Peerapong; Kukiattrakoon,Boonlert; Hengtrakool,Chanothai
Fonte: Faculdade De Odontologia De Bauru - USP Publicador: Faculdade De Odontologia De Bauru - USP
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/04/2011 EN
Relevância na Pesquisa
36.14%
OBJECTIVE: The aim of this study was to evaluate the fexural strength of two porcelain materials (IPS d.SIGN and IPS e.max Ceram) exposed to erosive agents. MATERIAL AND METHODS: One hundred and twenty bar-shaped specimens were made from each of fuorapatite-leucite porcelain (IPS d.SIGN) and fuorapatite porcelain (IPS e.max Ceram) and divided into 8 groups of 15 specimens each. Six groups were alternately immersed in the following storage agents for 30 min: deionized water (control), citrate buffer solution, pineapple juice, green mango juice, cola soft drink and 4% acetic acid. Then, they were immersed for 5 min in deionized water at 37ºC. Seven cycles were completed, totalizing 245 min. A 7th group was continuously immersed in 4% acetic acid at 80ºC for 16 h. The final, 8th, group was stored dry at 37ºC for 245 min. Three-point bending tests were performed in a universal testing machine. The data were analyzed statistically by 2-way ANOVA, Tukey's HSD test and t-test at signifcance level of 0.05. RESULTS: The fexural strengths of all groups of each porcelain after exposure to erosive agents in cyclic immersion did not differ signifcantly (p>0.05). For both types of porcelain, dry storage at 37ºC yielded the highest fexural strength...

Resiliency in Native Languages : Three Indigenous Communities’ Experiences with Language Immersion

Aguilera, Dorothy
Fonte: Universidade Autônoma de Barcelona Publicador: Universidade Autônoma de Barcelona
Tipo: Artigo de Revista Científica Formato: application/pdf
Publicado em //2007 ENG
Relevância na Pesquisa
36.14%
Este texto se presentó como comunicación al II Congreso Internacional de Etnografía y Educación: Migraciones y Ciudadanías. Universidad Autónoma de Barcelona, Barcelona, 5-8 Septiembre 2008.; This paper examines the outcomes of language immersion models implemented by three Indigenous communities to revitalize and preserve their native languages through ethnographic research design and methods. The history and implementation of language instruction in three Indigenous communities are described. The multi-stage analysis includes an examination of national and state test scores and other qualitative and quantitative data for the school communities. School demographics and standardized tests are used in the comparison of case studies as well as the relevant issues featured in the research literature about indigenous language revitalization. Data findings are summarized and include analysis of additional anecdotal information and test data used to explore research questions about academic achievement and Native language-medium education.

Effect of repeated immersion solution cycles on the color stability of denture tooth acrylic resins

Silva, Paulo Maurício Batista da; Acosta, Emílio José Tabaré Rodríguez; Jacobina, Matheus; Pinto, Luciana de Rezende; Porto, Vinícius Carvalho
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 01/12/2011 ENG
Relevância na Pesquisa
36.32%
OBJECTIVE: Chemical solutions have been widely used for disinfection of dentures, but their effect on color stability of denture tooth acrylic resins after repeated procedures is still unclear. The aim of this in vitro study was to evaluate whether repeated cycles of chemical disinfectants affected the color stability of two denture tooth acrylic resins. MATERIAL AND METHODS: Sixty disc-shaped specimens (40 mm x 3 mm) were fabricated from two different brands (Artiplus and Trilux) of denture tooth acrylic resin. The specimens from each brand (n=30) were randomly divided into 6 groups (n=5) and immersed in the following solutions: distilled water (control group) and 5 disinfecting solutions (1% sodium hypochlorite, 2% sodium hypochlorite, 5.25% sodium hypochlorite, 2% glutaraldehyde, and 4% chlorhexidine gluconate). Tooth color measurements were made by spectrophotometry. Before disinfection, the initial color of each tooth was recorded. Further color measurements were determined after subjecting the specimens to 7, 21, 30, 45, 60, and 90 immersion cycles in each tested solution. Color differences (ΔE*) were determined using the CIE L*a*b* color system. Data were analyzed using two-way repeated measures analysis of variance (ANOVA) followed by Tukey tests. The significance level was set at 5%. RESULTS: There were statistically significant differences in ΔE* among the 5 disinfectants and water during the 90 cycles of immersion for both denture tooth acrylic resins. Distilled water promoted the greatest color change in both denture tooth acrylic resins...

EXPERIMENTAL STUDY OF INTERACTION SHALE-FLUID THROUGH IMMERSION TESTS

Rabe, Claudio; da Fontoura, Sérgio Augusto Barreto; Antunes, Franklin dos Santos
Fonte: UFPR Publicador: UFPR
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; Peer-reviewed Article Formato: application/pdf
Publicado em 09/12/2005 ENG
Relevância na Pesquisa
46.15%
The present work has as objective the study of the behavior of preserved shale samples when immersed in aqueous solutions. The obtained results show that the solutions presented high variations of pH, salinity and electric conductivity, what indicates ionic migration of salts from the rock to the fluid, and small variations of Redox potential. Chemical analysis indicate strong migrations of ions from the rock to the fluid. It can also be observed that the solutions become cloudy, denser and more viscous. Besides, the samples suffer elevations of its water content, small variation of its cation exchange capacity and chemical composition, loss of solid material from superficial disintegration and the development of fractures in the cores. This work contributes to the understanding of the shale behavior in presence of drilling fluid water base.

Corrosion Behavior of Chemically Deposited Single and Bi-layered Conducting Polymer Coatings on Mild Steel

Mobin,M; Tanveer,Nelofar
Fonte: Sociedade Portuguesa de Electroquímica Publicador: Sociedade Portuguesa de Electroquímica
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/07/2011 EN
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The emeraldine base (EB) was synthesized by chemically oxidative polymerization using ammonium persulphate as an oxidant in hydrochloride aqueous medium. The polymer was chemically deposited on mild steel specimens using tetra methyl urea (TMU) as solvent through solvent evaporation method. The coating of polypyrrole (PPy) on carbon steel was deposited by chemical polymerization. A bi-layered polymer coating comprising of inner coat of PPy with top coat of EB (PPy/EB) was also deposited on mild steel following identical procedure. The deposited EB, PPy and PPy/EB coatings were characterized by Fourier Transform Infrared (FTIR) Spectroscopy and Scanning Electron Microscopy (SEM). The anticorrosive properties of single and bi-layered coatings was investigated in major corrosive environments such as 0.1 M HCl, 5% NaCl solution, artificial seawater, distilled water, tap water and open atmosphere by conducting various corrosion tests which include: immersion test, open circuit potential measurements, potentiodynamic polarization measurements, and atmospheric exposure test. The results of immersion tests showed that the PPy/EB coating gave best protection in all media under investigation, the protection efficiency being in the range of 72 to 79% after 30 days of immersion. The result of OCP measurements showed significant positive shift in the corrosion potential for single as well as bi-layered coatings in all corrosive medium under investigation; the bi-layered coating showing more positive corrosion potential. The potentiodynamic polarization studies also confirmed lower corrosion rates for PPy/EB coating than the single polymer coatings.

Comparison of linear polarization resistance corrosion monitoring probe readings and immersion test results for typical cooling water conditions

van der Merwe,J.W.; Palazzo,A.
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 01/03/2015 EN
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Owing to the corrosiveness of the untreated brackish cooling water typically used for steel mills (and other environments), it is important to treat the water and monitor corrosion in such systems. Generally, corrosion rates are monitored with corrosion probes inserted into a pipeline or vessel. This has been standard practice for many years, and is widely accepted in industry. Typically, two kinds of probes are used - electrical resistance and linear polarization resistance (LPR) probes. In this study, the effectiveness and accuracy of the LPR technique was evaluated by comparing the electrochemical measurements with the results of mass loss tests using corrosion coupons. The corrosivity of the environment, a synthetic brackish water, was varied by varying the calcium hardness and alkalinity, and to simulate actual plant conditions temperatures of 35°C and 45°C were used. In addition to the corrosion rate measurements, the iron concentration was measured, as well as the imbalance from the probe. The corrosion rates obtained by LPR were from 57% lower to 385% higher than those from the immersion tests. Most probe measurements were higher than the immersion results, and 50% of the probe results were 50% or more higher than the immersion results. The best correspondence between the two methods was obtained at low calcium levels...