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‣ Efeitos cardiovasculares das manobras de recrutamento alveolar durante lesão pulmonar aguda por ácido clorídrico: estudo experimental em suínos; Cardiovascular effects of alveolar recruitment maneuvers during acute lung injury by hydrochloric acid: experimental study in pigs

Marumo, Cristina Keiko
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 14/06/2007 Português
Relevância na Pesquisa
68.03793%
INTRODUÇÃO: Colapso alveolar é achado freqüente em lesão pulmonar aguda (LPA), levando ao aumento do shunt intrapulmonar e hipoxemia. Estratégias de tratamento atuais visam o recrutamento alveolar para melhora das trocas gasosas. Embora as manobras de recrutamento alveolar (MRA) sejam objetos de investigação nas últimas duas décadas, seu uso tem se tornado mais freqüente para o tratamento de pacientes com LPA. Volumes pulmonares e pressões pleurais elevados associados a MRA podem afetar a resistência vascular pulmonar e o trabalho cardíaco negativamente. Porém, o benefício da MRA na oxigenação, perante seus efeitos hemodinâmicos negativos, permanecem incertos devido à falta de informações dos efeitos cardiovasculares das MRAs. O objetivo deste estudo foi verificar, em modelo de LPA, os efeitos de um tipo de MRA- insuflação sustentada- associada a diferentes valores de PEEP no sistema cardiovascular durante um determinado período de observação. TIPO DE ESTUDO: estudo experimental prospectivo, controlado e randomizado. LOCAL: Laboratório de Anestesiologia Experimental- LIM 08. MATERIAL: Trinta e dois animais suínos. MÉTODO: Os animais anestesiados foram ventilados em modo volume-controlado e randomizados em quatro grupos (G1-PEEP; G2-PEEP-MRA; G3-LPA-PEEP; G4-LPA-PEEP-MRA) com oito animais cada. Os valores de PEEP foram progressivamente aumentados e diminuídos (5...

‣ Influência do laser de CO2 associado ao fluoreto estanhoso no controle da erosão induzida por ácido clorídrico em esmalte de dentes decíduos-análise do desgaste e da permeabilidade; Influence of CO2 laser associated to stannous fluoride in the erosion control induced by hydrochloric acid on enamel of primary teeth wear and permeability analysis.

Rocha, Cristiane Tomaz
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 14/01/2011 Português
Relevância na Pesquisa
48.33154%
Diante da importância e prevalência da erosão em crianças, devido principalmente ao refluxo gastroesofágico e da ausência de estudos na literatura sobre os efeitos do laser de CO2 no controle da erosão induzida por ácido clorídrico, o objetivo deste estudo foi determinar a influência in vitro de diferentes potências do laser de CO2 associado ao fluoreto estanhoso a 0,4% no controle da erosão induzida por ácido clorídrico em esmalte de dentes decíduos, por meio da análise do desgaste e da permeabilidade. Sessenta dentes decíduos foram utilizados para a obtenção de 120 fragmentos de esmalte (3x3 mm). Os fragmentos foram planificados, polidos e montados em blocos de resina acrílica. Duas fitas adesivas foram colocadas na superfície, deixando uma área de 3x1mm2 exposta. Para a formação das lesões de erosão, os espécimes foram submetidos a um desafio ácido de 4 ciclos por 2 minutos cada, com solução de ácido clorídrico a 0,01 M (pH 2). A análise do desgaste inicial foi calculada por perfilometria óptica e usada para selecionar 104 espécimes. Estes foram aleatoriamente divididos em 8 grupos, de acordo com a aplicação de flúor (presente- gel de fluoreto estanhoso a 0,4% e ausente-controle) e potência do laser de CO2 (sem irradiação-controle...

‣ Efeito de bebidas no esmalte dental submetido a desafio erosivo com ácido clorídrico; Effect of beverages on dental enamel submitted to erosive challenge with hidrochloric acid

Amoras, Dinah Ribeiro
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 06/01/2011 Português
Relevância na Pesquisa
58.07948%
A erosão dental de origem endógena apresenta alta prevalência e o efeito da ingestão frequente de determinadas bebidas poderia intensificar ou atenuar a lesão no esmalte. A análise do potencial erosivo das bebidas é uma estratégia importante para prevenir seu efeito na estrutura dental. Neste contexto, este estudo avaliou através de um modelo in vitro o efeito de bebidas no esmalte dental previamente submetido a desafio erosivo com ácido clorídrico. O fator em estudo foi o tipo de bebida, em cinco níveis: refrigerante de limão de baixa caloria (Sprite Zero Coca-Cola® Brasil), leite Ultra Higt Temperature integral (Parmalat®), extrato de soja integral (Ades® Original), chá preto pronto para beber de baixa caloria sabor pêssego (Leão Ice Tea Zero Coca-Cola® Brasil) e água mineral natural (Prata®). 75 espécimes de esmalte bovino foram distribuídos entre os 5 tipos de bebida (n=15), de acordo com delineamento em blocos completos e casualizados. Para a formação das lesões de desgaste erosivo, os espécimes foram imersos por 2 minutos em 10 ml de solução aquosa de ácido clorídrico 0,01 M. Posteriormente foram lavados com água deionizada, imersos em saliva artificial a 37ºC por 2 horas. Foram feitas imersões em 20 ml das bebidas por 1 minuto...

‣ Efeito de alimentos e bebidas no esmalte dental decíduo após desafio erosivo com ácido clorídrico; Effect of food and beverages in deciduous tooth enamel after erosive challenge with hydrochloric acid

Mesquita, Késsia Suênia Fidelis 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 11/05/2012 Português
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68.03793%
O objetivo deste estudo foi avaliar o efeito, in vitro, de alguns alimentos e bebidas industrializados oferecidos como lanche às crianças, sobre o esmalte dental decíduo, após simulação de desafio erosivo intrínseco em função do tempo de exposição. A coroa de cento e dois incisivos decíduos hígidos foram fixadas em bases acrílicas, expondo-se uma área de 2mm de diâmetro da superfície vestibular. Os espécimes foram submetidos a um desafio erosivo com ácido clorídrico e divididos aleatoriamente em 6 grupos (n=17): Leite Achocolatado Toddynho (Pepsico) - controle negativo, Petit Suisse Danoninho (Danone), Iogurte de Morango (Vigor), Papinha de Maçã (Nestlé), Leite Fermentado Yakult (Yakult) e Suco de Laranja Caseira com Gominhos (del Valle) - controle positivo. Os ciclos de imersão nos produtos teste foram realizados durante 28 dias, 2x/dia, intercalados com saliva artificial. Medidas de microdureza superficial do esmalte foram realizadas inicialmente (baseline), após imersão em ácido clorídrico e com 7, 14, 21 e 28 dias de experimento. A Análise de Variância (ANOVA) a dois critérios, seguida pela decomposição da soma dos quadrados e pelo teste de Tukey apresentou diferença significativa a interação entre Lanches e Tempo (p= 0.0000). O suco de laranja foi o produto que resultou em maior perda mineral do esmalte aos 28 dias. Nenhum dos lanches utilizados foi capaz de recuperar a microdureza do esmalte dental decíduo ao longo do tempo final de exposição (28 dias). A análise qualitativa por meio de Microscopia Eletrônica de Varredura foi realizada ao término dos 28 dias de exposição aos produtos...

‣ Avaliação da resposta inflamatória pulmonar de suínos submetidos a lesão pulmonar aguda induzida por ácido clorídrico e tratados com solução salina hipertônica; Lung inflammatory response in pigs submitted to acute pulmonary injury by hydrochloric acid and treated with hypertonic saline

Holms, Carla Augusto Thomaz de Aquino
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 07/11/2012 Português
Relevância na Pesquisa
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INTRODUÇÃO: A lesão pulmonar aguda (LPA) decorrente de aspiração do conteúdo gástrico é freqüente em pacientes com nível de consciência comprometido e depressão dos reflexos de vias aéreas. A solução salina hipertônica (HS) a 7,5% apresenta resultados ainda controversos quanto ao seu potencial efeito protetor na resposta inflamatória pulmonar. OBJETIVOS: Este estudo teve como objetivo avaliar o potencial efeito antiinflamatório da solução salina hipertônica no modelo experimental de lesão pulmonar por aspiração de ácido clorídrico (HCl). MÉTODOS: Foram utilizados 32 suínos (n=32; 8/grupo) divididos aleatoriamente nos seguintes grupos: Sham, onde os animais foram somente anestesiados, ventilados e observados; HS, onde os animais receberam infusão de HS a 7,5% (4 ml/kg), sem LPA; ALI, onde os animais foram submetidos à LPA com HCl; ALI+HS, onde os animais foram submetidos à LPA com HCl e tratados com HS a 7,5% (4 ml/kg). Foram mensurados parâmetros hemodinâmicos e ventilatórios. Amostras de sangue foram coletadas para hemogasometria e análise dos níveis plasmáticos de TNF-?. Foram coletadas amostras do lavado broncoalveolar para mensuração das seguintes citocinas: IL-1, IL-6, IL-8, IL-10 e TNF-?...

‣ The thermal, rheological and structural properties of cassava starch granules modified with hydrochloric acid at different temperatures

Beninca, Cleoci; Colman, Tiago André Denck; Lacerda, Luiz Gustavo; Filho, Marco Aurélio Silva Carvalho; Bannach, Gilbert; Schnitzler, Egon
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 65-69
Português
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Starch is arguably one of the most actively investigated biopolymer in the world. In this study, the native (untreated) cassava starch granules (Manihot esculenta, Crantz) were hydrolyzed by standard hydrochloric acid solution at different temperatures (30 °C and 50 °C) and the hydrolytic transformations were investigated by the following techniques: simultaneous thermogravimetry-differential thermal analysis (TG-DTA), differential scanning calorimetry (DSC), as well as non-contact atomic force microscopy (NC-AFM), X-ray diffraction (XRD) powder patterns, and rapid viscoamylographic analysis (RVA). After the treatment with hydrochloric acid at different temperatures, the thermal stability, a gradual loss of pasting properties (viscosity), alterations in the gelatinization enthalpy (ΔHgel), were observed. The use of NC-AFM and XRD allowed the observation of the surface morphology and topography of the starch granules and changes in crystallinity of the granules, respectively. © 2012 Elsevier B.V. All rights reserved.

‣ Experimental model of smoking and simulation of reflux with acid and pepsin in rats

Zen Junior, Jose Helio; Del Negro, Andre; Colli Neto, Jose Alexandre; Araujo, Marina Rachel; Altemani, Albina Maria; Andreollo, Nelson Adami
Fonte: Acta Cirurgica Brasileira; Sao Paulo Publicador: Acta Cirurgica Brasileira; Sao Paulo
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
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PURPOSE: To develop experimental models to evaluate the effects of hydrochloric acid associated with the pepsin instilled in the mucosa of the upper esophagus and the esophagogastric junction of young male rats Wistar, simulating injury caused by gastroesophageal reflux on the mucosa of aero-digestive tract in humans as well as the action of the risk exposure of mucosa to cigarette smoke. METHODS: Fifty young male Wistar rats divided in 5 groups with 10 animals each one, respectively simulating pharyngo-laryngeal reflux and gastroesophageal reflux, pharyngo-laryngeal reflux and smoking, smoking only, gastroesophageal reflux and control group. RESULTS: The histopathologic studies no recorded neoplasias, only mild changes and no significant alterations. The hemo-oximetry (carboxyhemoglobin and methemoglobim) and CO2 concentration confirm that the animals were submitted to high intensity of exposure to carcinogens in tobacco and its derivatives. CONCLUSION: The experimental models were highly efficient, practical, easy to use and economical and can be employed in other similar studies to determine the harmful effects by smoking and reflux.; Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

‣ Experimental carcinogenesis on the oropharyngeal mucosa of rats with hydrochloric acid, sodium nitrate and pepsin

Del Negro,André; Araújo,Marina Raquel; Tincani,Alfio José; Meirelles,Luciana; Martins,Antônio Santos; Andreollo,Nelson Adami
Fonte: Sociedade Brasileira para o Desenvolvimento da Pesquisa em Cirurgia Publicador: Sociedade Brasileira para o Desenvolvimento da Pesquisa em Cirurgia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/08/2008 Português
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PURPOSE: To investigate the carcinogenic action of hydrochloric acid, pepsin and sodium nitrate on the oropharyngeal mucosa of rats, simulating the reflux of gastric contents. METHODS: Eighty-two Wistar rats were divided in seven groups and submitted to 2 or 3 weekly applications of hydrochloric acid, pepsin and sodium nitrate on the pharyngeal mucosa during six months. Study groups comprised 12 animals each. Rats in groups I and II were submitted to 2 (GI) or 3 (GII) weekly applications of 0.1N hydrochloric acid. Groups III and IV were submitted to 2 (GIII) or 3 (GIV) weekly applications of 0.1N hydrochloric acid solution with pepsin. Groups V and VI were submitted to 2 (GV) or 3 (GVI) weekly applications of 0.1N hydrochloric acid and treated with daily nitrate diluted in water. Group VII consisted of 10 animals submitted to 2 weekly applications of filtered water. RESULTS: No dysplasia, intra-epithelial neoplasia or invasive carcinomas were detected. Inflammatory changes were observed in varying degrees and mast cells were more common in Groups V and VI (p=0.006). CONCLUSION: The data of the current study could not corroborate the hypothesis that gastroesophageal and pharyngolaryngeal refluxes are carcinogenic factors to the laryngopharyngeal mucosa...

‣ Experimental model of smoking and simulation of reflux with acid and pepsin in rats

Zen Junior,José Hélio; Negro,André Del; Colli Neto,José Alexandre; Araujo,Marina Rachel; Altemani,Albina Maria; Andreollo,Nelson Adami
Fonte: Sociedade Brasileira para o Desenvolvimento da Pesquisa em Cirurgia Publicador: Sociedade Brasileira para o Desenvolvimento da Pesquisa em Cirurgia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2012 Português
Relevância na Pesquisa
57.567993%
PURPOSE: To develop experimental models to evaluate the effects of hydrochloric acid associated with the pepsin instilled in the mucosa of the upper esophagus and the esophagogastric junction of young male rats Wistar, simulating injury caused by gastroesophageal reflux on the mucosa of aero-digestive tract in humans as well as the action of the risk exposure of mucosa to cigarette smoke. METHODS: Fifty young male Wistar rats divided in 5 groups with 10 animals each one, respectively simulating pharyngo-laryngeal reflux and gastroesophageal reflux, pharyngo-laryngeal reflux and smoking, smoking only, gastroesophageal reflux and control group. RESULTS: The histopathologic studies no recorded neoplasias, only mild changes and no significant alterations. The hemo-oximetry (carboxyhemoglobin and methemoglobim) and CO2 concentration confirm that the animals were submitted to high intensity of exposure to carcinogens in tobacco and its derivatives. CONCLUSION: The experimental models were highly efficient, practical, easy to use and economical and can be employed in other similar studies to determine the harmful effects by smoking and reflux.

‣ In situ end labelling: effect of proteolytic enzyme pretreatment and hydrochloric acid.

Carr, N. J.; Talbot, I. C.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /06/1997 Português
Relevância na Pesquisa
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AIM: To determine the effect of dilute hydrochloric acid on the in situ end labelling (ISEL) reaction, with and without a variety of different proteolytic enzymes. METHODS: Sections of tissue fixed in buffered formalin were pretreated with trypsin, protease XIV (at two different concentrations), or protease XXIV (for two different incubation times), with and without subsequent 1 M hydrochloric acid treatment. The results were compared with those obtained using hydrochloric acid alone, with proteinase K, and pepsin pretreatment, and with no pretreatment. RESULTS: When hydrochloric acid was added to the sections in addition to trypsin, protease XIV, and protease XXIV, there was a significant increase in ISEL reactivity in both apoptotic nuclei and morphologically normal nuclei. Hydrochloric acid alone had no significant effect. CONCLUSIONS: Hydrochloric acid has a distinctive effect on the ISEL reaction that is dependent on prior proteolytic digestion.

‣ Surface Roughness of Composite Resins Subjected to Hydrochloric Acid

Roque,Ana Carolina Cabral; Bohner,Lauren Oliveira Lima; Godoi,Ana Paula Terossi de; Colucci,Vivian; Corona,Silmara Aparecida Milori; Catirse,Alma Blásida Concepción Elizaur Benitez
Fonte: Fundação Odontológica de Ribeirão Preto Publicador: Fundação Odontológica de Ribeirão Preto
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2015 Português
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The purpose of this study was to determine the influence of hydrochloric acid on surface roughness of composite resins subjected to brushing. Sixty samples measuring 2 mm thick x 6 mm diameter were prepared and used as experimental units. The study presented a 3x2 factorial design, in which the factors were composite resin (n=20), at 3 levels: microhybrid composite (Z100), nanofilled composite (FiltekTM Supreme), nanohybrid composite (Ice), and acid challenge (n=10) at 2 levels: absence and presence. Acid challenge was performed by immersion of specimens in hydrochloric acid (pH 1.2) for 1 min, 4 times per day for 7 days. The specimens not subjected to acid challenge were stored in 15 mL of artificial saliva at 37 oC. Afterwards, all specimens were submitted to abrasive challenge by a brushing cycle performed with a 200 g weight at a speed of 356 rpm, totaling 17.8 cycles. Surface roughness measurements (Ra) were performed and analyzed by ANOVA and Tukey test (p≤0.05). Surface roughness values were higher in the presence (1.07±0.24) as compared with the absence of hydrochloric acid (0.72±0.04). Surface roughness values were higher for microhybrid (1.01±0.27) compared with nanofilled (0.68 ±0.09) and nanohybrid (0.48±0.15) composites when the specimens were not subjects to acid challenge. In the presence of hydrochloric acid...

‣ Effect of beverages on bovine dental enamel subjected to erosive challenge with hydrochloric acid

Amoras, Dinah Ribeiro; Corona, Silmara Aparecida Milori; Rodrigues Jr, Antonio Luiz; Serra, Mônica Campos
Fonte: Fundação Odontológica de Ribeirão Preto Publicador: Fundação Odontológica de Ribeirão Preto
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
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This study evaluated by an in vitro model the effect of beverages on dental enamel previously subjected to erosive challenge with hydrochloric acid. The factor under study was the type of beverage, in five levels: Sprite® Zero Low-calorie Soda Lime (positive control), Parmalat® ultra high temperature (UHT) milk, Ades® Original soymilk, Leão® Ice Tea Zero ready-to-drink low-calorie peach-flavored black teaand Prata® natural mineral water (negative control). Seventy-five bovine enamel specimens were distributed among the five types of beverages (n=15), according to a randomized complete block design. For the formation of erosive wear lesions, the specimens were immersed in 10 mL aqueous solution of hydrochloric acid 0.01 M for 2 min. Subsequently, the specimens were immersed in 20 mL of the beverages for 1 min, twice daily for 2 days at room temperature. In between, the specimens were kept in 20 mL of artificial saliva at 37ºC. The response variable was the quantitative enamel microhardness. ANOVA and Tukey's test showed highly significant differences (p<0.00001) in the enamel exposed to hydrochloric acid and beverages. The soft drink caused a significantly higher decrease in microhardness compared with the other beverages. The black tea caused a significantly higher reduction in microhardness than the mineral water...

‣ Effect of beverages on bovine dental enamel subjected to erosive challenge with hydrochloric acid

Amoras,Dinah Ribeiro; Corona,Silmara Aparecida Milori; Rodrigues Jr,Antonio Luiz; Serra,Mônica Campos
Fonte: Fundação Odontológica de Ribeirão Preto Publicador: Fundação Odontológica de Ribeirão Preto
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2012 Português
Relevância na Pesquisa
68.184927%
This study evaluated by an in vitro model the effect of beverages on dental enamel previously subjected to erosive challenge with hydrochloric acid. The factor under study was the type of beverage, in five levels: Sprite® Zero Low-calorie Soda Lime (positive control), Parmalat® ultra high temperature (UHT) milk, Ades® Original soymilk, Leão® Ice Tea Zero ready-to-drink low-calorie peach-flavored black teaand Prata® natural mineral water (negative control). Seventy-five bovine enamel specimens were distributed among the five types of beverages (n=15), according to a randomized complete block design. For the formation of erosive wear lesions, the specimens were immersed in 10 mL aqueous solution of hydrochloric acid 0.01 M for 2 min. Subsequently, the specimens were immersed in 20 mL of the beverages for 1 min, twice daily for 2 days at room temperature. In between, the specimens were kept in 20 mL of artificial saliva at 37ºC. The response variable was the quantitative enamel microhardness. ANOVA and Tukey's test showed highly significant differences (p<0.00001) in the enamel exposed to hydrochloric acid and beverages. The soft drink caused a significantly higher decrease in microhardness compared with the other beverages. The black tea caused a significantly higher reduction in microhardness than the mineral water...

‣ Hydrochloric Acid; Ácido Clorídrico (CAS No. 7647-01-0)

Nathalia M. C. Tolentino; Universidade Federal Fluminense; Luana S. M. Forezi; Universidade Federal Fluminense
Fonte: Revista Virtual de Química Publicador: Revista Virtual de Química
Tipo: ; Formato: binary/octet-stream
Publicado em 27/06/2014 Português
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This article presents a review of different methods of industrial synthesis of hydrochloric acid, such as: direct synthesis; chlorination of organic compounds; Mannheim process and Hargreaves reactions. Data on physico-chemical properties, toxicity and the main applications of hydrochloric acid are also presented.  DOI: 10.5935/1984-6835.20140072; Este artigo apresenta uma revisão dos diferentes métodos de síntese industrial do ácido clorídrico, tais como: síntese direta; cloração de compostos orgânicos; processo Mannheim e reações Hargreaves. Também são apresentados dados sobre propriedades físico-químicas, toxicidade e as principais aplicações do ácido clorídrico.  DOI: 10.5935/1984-6835.20140072

‣ Study of the picklability of 1.8 mm hot-rolled steel strip in hydrochloric acid

Gines,M.J.L.; Benitez,G.J.; Perez,T.; Merli,E.; Firpo,M.A.; EgliI,W.
Fonte: Latin American applied research Publicador: Latin American applied research
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2002 Português
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After the hot rolling process the steel strip remains covered with an oxide layer (scale) which must be removed previous to the cold rolling process. The scale removal through the pickling process by hydrochloric acid (HCl) depends on both the scale structure and the conditions of the pickling bath (temperature, acid concentration, and dissolved iron concentration). This work is focused on picklability (decapability) studies accomplished in laboratory on hot-rolled steel strip, 1.8 mm thickness. The oxide amount was determined by weight difference of samples with and without acid pickling. The scale was characterized by X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The pickling or descaling time (t d) was determined using different bath conditions. Pickling kinetic studies were carried out being the pickled fraction (a) determined as a function of the immersion time. Expressions were obtained, allowing descaling time estimation under various pickling bath conditions. These expressions were used to estimate the maximum operation line speed that assures a complete descaling.

‣ Thermodynamic Characterization of Metal Dissolution and Adsorption of Polyvinyl Alcohol-Grafted Poly(Acrylamide-Vinyl Sulfonate) on Mild Steel in Hydrochloric Acid

Geethanjali,R.; Subhashini,S.
Fonte: Sociedade Portuguesa de Electroquímica Publicador: Sociedade Portuguesa de Electroquímica
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2015 Português
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The corrosion inhibition of mild steel in hydrochloric acid by polyvinyl alcohol-gpoly( acrylamide-vinyl sulfonate) has been studied by weight loss and electrochemical methods (AC impedance and DC polarisation) techniques in the temperature range of 303 - 343 K. The inhibitor was found to provide an excellent efficiency of more than 90 %. Various adsorption isotherms have been employed for fitting the obtained results to confirm the mode of adsorption of the grafted terpolymer on mild steel. Thermodynamic parameters of adsorption such as equilibrium constant, Gibbs free energy, adsorption heat and adsorption entropy were evaluated and discussed. Various parameters that determine the kinetics of mild steel dissolution such as activation energy, enthalpy and entropy were also calculated. Results obtained from various techniques were comparable and suggest that the terpolymer follows chemical adsorption mode for inhibition.

‣ Schiff Bases of Triethylenetetramine as Corrosion Inhibitors of Zinc in Hydrochloric Acid

Shah,M.D.; Patel,A.S.; Mudaliar,G.V.; Shah,N.K.
Fonte: Sociedade Portuguesa de Electroquímica Publicador: Sociedade Portuguesa de Electroquímica
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2011 Português
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The performance of triethylenetetramine-tribenzylidene (TTTB) and triethylenetetramine-trisalicylidene (TTTS) as corrosion inhibitors for zinc in hydrochloric acid is investigated. At lower concentrations, both inhibitors accelerate the attack but inhibit corrosion at higher concentrations, e.g., 96-100% with 1.0% concentration in 0.5 M and 1.0 M HCl. The efficiency of TTTB decreases while that of TTTS remains almost constant (≥ 99.7%) up to 120 minutes and in the temperature range 35 - 65 ºC. The activation energies are higher in inhibited than in plain acid with both inhibitors. The free energy of adsorption (ΔGads) and heat of adsorption (Qads) are negative, which suggests that there is spontaneous adsorption on metal surface, and from the values of (ΔGads) and (Qads), the values of entropy of adsorption (ΔSads) were calculated. Galvanostatic polarization shows that corrosion is under mixed control with predominance of the cathodic part. In uninhibited 1.0 M HCl, complete cathodic protection is achieved at a current density of 4.2224 Adm-2, but in presence of these inhibitors, much lower current densities are required. Plot of log (θ/1-θ) versus log Cinh gives a straight line, suggesting that inhibitors cover both the anodic and cathodic regions through general adsorption following Langmuir isotherm. The mechanism of inhibition has been proposed.

‣ Corrosion Resistance of Mo3Si with Niobium Additions in Hydrochloric Acid

Huicochea,C.; Rosales,I.; Castañeda,I.E.; Uruchurtu,J.
Fonte: Sociedade Portuguesa de Electroquímica Publicador: Sociedade Portuguesa de Electroquímica
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2007 Português
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In the present work, the electrochemical behavior of molybdenum-silica-niobium alloy produced by arc cast technique is presented, keeping silica constant (at 24 wt %), using different niobium concentrations (5, 10, 15 & 20 wt %) as alloying elements. These samples were immersed in an electrochemical solution of 10 % by volume hydrochloric acid. The corrosion behavior was obtained using electrochemical techniques, namely: open circuit potential, polarization curves and electrochemical current noise. The potential behaviour as a function of time allows to determine the activity of the alloy as a function of its content, the polarization technique was used to obtain characteristic electrochemical parameters and the electrochemical current noise the type of attack while comparing them with the corrosion surface morphological features. Surface images showed different corrosion morphologies, being the most attacked the sample without niobium additions. It was found that niobium additions result in a better corrosion resistance when its concentration is increased in the alloy.

‣ Leachability of nitrided ilmenite in hydrochloric acid

Swanepoel,J.J.; van Vuuren,D.S.; Heydenrych,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 01/01/2011 Português
Relevância na Pesquisa
68.415117%
Titanium nitride in upgraded nitrided ilmenite (bulk of iron removed) can selectively be chlorinated to produce titanium tetrachloride. Except for iron, most other components present during this low temperature (ca. 200°C) chlorination reaction will not react with chlorine. It is therefore necessary to remove as much iron as possible from the nitrided ilmenite. Hydrochloric acid leaching is a possible process route to remove metallic iron from nitrided ilmenite without excessive dissolution of species like titanium nitride and calcium oxide. Calcium oxide dissolution results in unrecoverable acid consumption. The leachability of nitrided ilmenite in hydrochloric acid was evaluated by determining the dissolution of species like aluminium, calcium, titanium and magnesium in a batch leach reactor for 60 minutes at 90°C under reflux conditions. The hydrochloric acid concentration (11%, 18% and 25%), initial acid-to-iron mole ratio (2:1, 2.5:1 and 3.3:1), and solid-to-liquid mass ratio (1:8.33 to 1:2.13) were varied. The results indicate that a hydrochloric acid concentration of 25 wt% supplied in a 2:1 acid-to-iron mole ratio would produce the most favourable upgraded nitrided ilmenite product. The dissolution of iron in this solution reached 97 per cent after only 60 minutes. The total dissolution of calcium and titanium species was 0.01 and 0.11 wt% respectively. Hydrochloric acid can therefore be used as lixiviant to remove metallic iron from nitrided ilmenite.

‣ The effects of hydrochloric acid on all-ceramic restorative materials: an in-vitro study

Harryparsad,A; Dullabh,H; Sykes,L; Herbst,D
Fonte: SciELO África do Sul Publicador: SciELO África do Sul
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em // Português
Relevância na Pesquisa
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OBJECTIVES: The aim of this in-vitro study was to assess the long-term effects of hydrochloric acid on the surface roughness of three all-ceramic restorative materials CEREC VITABLOC® Mark II CAD, IPS Empress CAD® and IPS e.max CAD®. MATERIALS AND METHODS: Six cylindrical specimens (10mm diameter, 3mm height) of each material type were prepared, using the CEREC CAD/CAM machine. The unpolished samples were immersed in 15ml hydrochloric acid (pH 2) at 370C. Before immersion (baseline) and at periods of 7.5 hours, 45 hours and 91 hours, the specimens were removed from the acid and two randomised areas (10µm X 10µm) were selected and tested on each. The atomic force microscope (Bruker Dimension icon) was used to assess surface roughness and surface area at baseline and after each exposure time. The materials were compared over time with respect to surface roughness and surface area (baseline, 1 month, 6 months, 1 year) in a repeated measures analysis of variance (ANOVA). RESULTS: Sample groups differed significantly for roughness (p<0.0001) and surface area (p<0.0001). For both parameters a significant interaction also existed between material and time (surface roughness: p=0.0085; surface area: p=0.0014). CEREC VITABLOC® Mark II CAD and IPS Empress CAD® had substantially higher levels of roughness and surface area than IPS e.max CAD®...