Subjects -> FOOD AND FOOD INDUSTRIES (Total: 410 journals)
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    - FOOD AND FOOD INDUSTRIES (289 journals)

FOOD AND FOOD INDUSTRIES (289 journals)                  1 2     

Showing 1 - 62 of 62 Journals sorted alphabetically
Acta Alimentaria     Full-text available via subscription   (Followers: 7)
Acta Universitatis Cibiniensis. Series E: Food Technology     Open Access   (Followers: 2)
Acta Universitatis Sapientiae, Alimentaria     Open Access   (Followers: 1)
adhäsion KLEBEN & DICHTEN     Hybrid Journal   (Followers: 9)
Advances in Food and Nutrition Research     Full-text available via subscription   (Followers: 71)
Advances in Nutrition     Hybrid Journal   (Followers: 61)
African Journal of Drug and Alcohol Studies     Full-text available via subscription   (Followers: 6)
African Journal of Food Science     Open Access   (Followers: 10)
African Journal of Food, Agriculture, Nutrition and Development     Open Access   (Followers: 26)
Agricultural and Food Science     Open Access   (Followers: 22)
Agriculture & Food Security     Open Access   (Followers: 18)
Agriculture and Food Sciences Research     Open Access   (Followers: 11)
Agro-Science     Full-text available via subscription   (Followers: 2)
Agroecology and Sustainable Food Systems     Hybrid Journal   (Followers: 18)
Agrosearch     Open Access   (Followers: 2)
Alimentos e Nutrição     Open Access   (Followers: 2)
Alimentos Hoy     Open Access   (Followers: 1)
American Journal of Food and Nutrition     Open Access   (Followers: 58)
American Journal of Food Science and Technology     Open Access   (Followers: 11)
American Journal of Food Technology     Open Access   (Followers: 11)
Amerta Nutrition     Open Access  
Amino Acids     Hybrid Journal   (Followers: 7)
Animal Production     Open Access   (Followers: 5)
Animal Production Science     Hybrid Journal   (Followers: 2)
Annual Review of Food Science and Technology     Full-text available via subscription   (Followers: 15)
Anthropology of food     Open Access   (Followers: 16)
Applied Food Biotechnology     Open Access   (Followers: 4)
Arquivos Brasileiros de Alimentação     Open Access  
Asian Food Science Journal     Open Access   (Followers: 2)
Asian Journal of Animal and Veterinary Advances     Open Access   (Followers: 8)
Asian Journal of Cell Biology     Open Access   (Followers: 6)
Asian Journal of Clinical Nutrition     Open Access   (Followers: 14)
Asian Journal of Crop Science     Open Access   (Followers: 3)
Asian Plant Research Journal     Open Access   (Followers: 1)
Bangladesh Rice Journal     Open Access   (Followers: 2)
Biotechnology and Genetic Engineering Reviews     Hybrid Journal   (Followers: 12)
Boletim de Indústria Animal     Open Access  
Brazilian Journal of Food Technology     Open Access   (Followers: 3)
Bulletin of University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca : Food Science and Technology     Open Access  
Canadian Food Studies / La Revue canadienne des études sur l'alimentation     Open Access   (Followers: 1)
Cerâmica     Open Access   (Followers: 5)
Chemical Research in Chinese Universities     Hybrid Journal   (Followers: 3)
Ciência e Agrotecnologia     Open Access  
COCOS : The Journal of the Coconut Research Institute of Sri Lanka     Open Access   (Followers: 1)
Cogent Food & Agriculture     Open Access   (Followers: 3)
Comprehensive Reviews in Food Science and Food Safety     Hybrid Journal   (Followers: 7)
Critical Reviews in Food Science and Nutrition     Hybrid Journal   (Followers: 31)
Cuizine: The Journal of Canadian Food Cultures / Cuizine : revue des cultures culinaires au Canada     Open Access   (Followers: 3)
Culture, Agriculture, Food and Environment     Hybrid Journal   (Followers: 17)
Culture, Agriculture, Food and Environment     Hybrid Journal   (Followers: 9)
Current Botany     Open Access   (Followers: 1)
Current Opinion in Food Science     Hybrid Journal   (Followers: 6)
Current Research in Dairy Sciences     Open Access   (Followers: 6)
Current Research in Food Science     Open Access   (Followers: 1)
Current Research in Microbiology     Open Access   (Followers: 25)
Current Research in Nutrition and Food Science     Open Access   (Followers: 5)
CyTA - Journal of Food     Open Access   (Followers: 1)
Detection     Open Access   (Followers: 4)
Developments in Food Science     Full-text available via subscription   (Followers: 2)
EFSA Journal     Open Access   (Followers: 6)
Emirates Journal of Food and Agriculture     Open Access   (Followers: 2)
Engineering in Agriculture, Environment and Food     Hybrid Journal  
Enzyme Research     Open Access   (Followers: 5)
Estudios sociales : Revista de alimentación contemporánea y desarrollo regional     Open Access   (Followers: 1)
EUREKA : Life Sciences     Open Access   (Followers: 3)
European Food Research and Technology     Hybrid Journal   (Followers: 9)
European Journal of Nutrition & Food Safety     Open Access   (Followers: 1)
Flavour     Open Access   (Followers: 3)
Flavour and Fragrance Journal     Hybrid Journal   (Followers: 4)
Focusing on Modern Food Industry     Open Access   (Followers: 2)
Food & Function     Full-text available via subscription   (Followers: 9)
Food & Nutrition Research     Open Access   (Followers: 35)
Food Additives & Contaminants Part A     Hybrid Journal   (Followers: 10)
Food Additives and Contaminants: Part B: Surveillance     Hybrid Journal   (Followers: 3)
Food Analytical Methods     Hybrid Journal   (Followers: 3)
Food and Applied Bioscience Journal     Open Access   (Followers: 2)
Food and Bioprocess Technology     Hybrid Journal   (Followers: 4)
Food and Bioproducts Processing     Hybrid Journal   (Followers: 4)
Food and Chemical Toxicology     Hybrid Journal   (Followers: 22)
Food and Energy Security     Open Access   (Followers: 6)
Food and Environment Safety     Open Access   (Followers: 1)
Food and Nutrition Bulletin     Hybrid Journal   (Followers: 6)
Food and Nutrition Sciences     Open Access   (Followers: 17)
Food and Public Health     Open Access   (Followers: 17)
Food and Waterborne Parasitology     Open Access  
Food Biology     Open Access   (Followers: 1)
Food Biophysics     Hybrid Journal   (Followers: 4)
Food Bioscience     Hybrid Journal   (Followers: 2)
Food Biotechnology     Hybrid Journal   (Followers: 8)
Food Chain     Full-text available via subscription   (Followers: 1)
Food Chemistry     Hybrid Journal   (Followers: 25)
Food Chemistry : X     Open Access   (Followers: 2)
Food Control     Hybrid Journal   (Followers: 10)
Food Digestion     Hybrid Journal   (Followers: 5)
Food Economics     Hybrid Journal   (Followers: 2)
Food Ethics     Hybrid Journal   (Followers: 1)
Food Hydrocolloids     Hybrid Journal   (Followers: 5)
Food In     Open Access  
Food Manufacturing Africa     Full-text available via subscription  
Food Microbiology     Hybrid Journal   (Followers: 22)
Food Modelling Journal     Partially Free   (Followers: 2)
Food New Zealand     Full-text available via subscription   (Followers: 4)
Food Packaging and Shelf Life     Hybrid Journal   (Followers: 5)
Food Processing     Full-text available via subscription   (Followers: 7)
Food Quality and Preference     Hybrid Journal   (Followers: 7)
Food Quality and Safety     Open Access   (Followers: 1)
Food Research International     Hybrid Journal   (Followers: 11)
Food Reviews International     Hybrid Journal   (Followers: 4)
Food Science & Nutrition     Open Access   (Followers: 59)
Food Science and Biotechnology     Hybrid Journal   (Followers: 9)
Food Science and Human Wellness     Open Access   (Followers: 5)
Food Science and Quality Management     Open Access   (Followers: 9)
Food Science and Technology     Open Access   (Followers: 3)
Food Science and Technology (Campinas)     Open Access   (Followers: 1)
Food Science and Technology International     Hybrid Journal   (Followers: 6)
Food Security     Open Access   (Followers: 11)
Food Structure     Hybrid Journal   (Followers: 3)
Food Technology     Full-text available via subscription   (Followers: 9)
Food Technology and Biotechnology     Open Access   (Followers: 1)
Foodborne Pathogens and Disease     Hybrid Journal   (Followers: 13)
Foodnews     Partially Free   (Followers: 2)
Foods     Open Access  
Frontiers in Sustainable Food Systems     Open Access  
Future of Food : Journal on Food, Agriculture and Society     Open Access   (Followers: 15)
Gastroia : Journal of Gastronomy And Travel Research     Open Access   (Followers: 1)
Gastronomica     Full-text available via subscription   (Followers: 13)
Gıda Dergisi     Open Access  
Global Food History     Hybrid Journal   (Followers: 1)
Global Food Security     Hybrid Journal   (Followers: 2)
GM Crops and Food: Biotechnology in Agriculture and the Food Chain     Full-text available via subscription   (Followers: 3)
Grain & Oil Science and Technology     Open Access   (Followers: 1)
Grasas y Aceites     Open Access  
Habitat     Open Access  
Harran Tarım ve Gıda Bilimleri Dergisi     Open Access   (Followers: 1)
Himalayan Journal of Science and Technology     Open Access   (Followers: 1)
Indonesian Food and Nutrition Progress     Open Access  
Indonesian Food Science & Technology Journal     Open Access   (Followers: 1)
INNOTEC : Revista del Laboratorio Tecnológico del Uruguay     Open Access  
Innovative Food Science & Emerging Technologies     Hybrid Journal   (Followers: 5)
International Journal of Agricultural Science and Food Technology     Open Access   (Followers: 2)
International Journal of Agriculture, Environment and Food Sciences     Open Access   (Followers: 2)
International Journal of Dairy Science     Open Access   (Followers: 6)
International Journal of Food Contamination     Open Access  
International Journal of Food Design     Hybrid Journal   (Followers: 2)
International Journal of Food Engineering     Hybrid Journal   (Followers: 3)
International Journal of Food Engineering Research     Open Access  
International Journal of Food Microbiology     Hybrid Journal   (Followers: 20)
International Journal of Food Properties     Open Access   (Followers: 2)
International Journal of Food Safety, Nutrition and Public Health     Hybrid Journal   (Followers: 22)
International Journal of Food Science     Open Access   (Followers: 5)
International Journal of Food Science & Technology     Hybrid Journal   (Followers: 7)
International Journal of Food Science and Nutrition Engineering     Open Access   (Followers: 8)
International Journal of Gastronomy and Food Science     Open Access   (Followers: 6)
International Journal of Latest Trends in Agriculture and Food Sciences     Open Access   (Followers: 6)
International Journal of Meat Science     Open Access  
International Journal of Poultry Science     Open Access   (Followers: 6)
International Journal on Food System Dynamics     Open Access  
Investigación Pecuaria     Open Access   (Followers: 1)
ISABB Journal of Food and Agricultural Sciences     Open Access   (Followers: 1)
Italian Journal of Food Safety     Open Access   (Followers: 1)
Italian Journal of Food Science     Open Access   (Followers: 3)
itepa : Jurnal Ilmu dan Teknologi Pangan     Open Access  
JKI Datenblätter : Obstsorten     Open Access   (Followers: 2)
JOT Journal für Oberflächentechnik     Hybrid Journal   (Followers: 1)
Journal für Verbraucherschutz und Lebensmittelsicherheit     Hybrid Journal  
Journal of Acupuncture and Herbs     Open Access   (Followers: 3)
Journal of Agricultural & Food Industrial Organization     Hybrid Journal  
Journal of Agriculture and Food Sciences     Full-text available via subscription   (Followers: 2)
Journal of Agriculture and Natural Resources     Open Access   (Followers: 1)
Journal of Agriculture, Food Systems, and Community Development     Open Access  
Journal of AOAC International     Full-text available via subscription   (Followers: 8)
Journal of Applied Botany and Food Quality     Open Access   (Followers: 5)
Journal of Aquatic Food Product Technology     Hybrid Journal   (Followers: 4)
Journal of Berry Research     Hybrid Journal   (Followers: 1)
Journal of Culinary Science & Technology     Hybrid Journal   (Followers: 1)
Journal of Environmental Health Science & Engineering     Open Access   (Followers: 1)
Journal of Ethnic Foods     Open Access   (Followers: 1)
Journal of Excipients and Food Chemicals     Open Access   (Followers: 1)
Journal of Fisheries and Aquatic Science     Open Access   (Followers: 6)
Journal of Food and Dairy Technology     Open Access  
Journal of Food and Drug Analysis     Open Access  
Journal of Food and Pharmaceutical Sciences     Open Access   (Followers: 2)
Journal of Food Biochemistry     Hybrid Journal   (Followers: 5)
Journal of Food Chemistry & Nanotechnology     Open Access   (Followers: 3)
Journal of Food Chemistry and Nutrition     Open Access   (Followers: 6)
Journal of Food Composition and Analysis     Hybrid Journal   (Followers: 3)
Journal of Food Engineering     Hybrid Journal   (Followers: 6)
Journal of Food Health and Bioenvironmental Science     Open Access  
Journal of Food Industry     Open Access   (Followers: 1)
Journal of Food Lipids     Hybrid Journal  
Journal of Food Measurement and Characterization     Hybrid Journal  
Journal of Food Microbiology     Open Access   (Followers: 9)
Journal of Food Process Engineering     Hybrid Journal   (Followers: 4)
Journal of Food Processing & Beverages     Open Access  
Journal of Food Processing & Technology     Open Access   (Followers: 2)
Journal of Food Processing and Preservation     Hybrid Journal   (Followers: 3)
Journal of Food Products Marketing     Hybrid Journal   (Followers: 2)
Journal of Food Protection(R)     Full-text available via subscription   (Followers: 7)
Journal of Food Quality     Hybrid Journal   (Followers: 8)
Journal of Food Research     Open Access   (Followers: 4)

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Cerâmica
Journal Prestige (SJR): 0.186
Number of Followers: 5  

  This is an Open Access Journal Open Access journal
ISSN (Print) 0366-6913
Published by SciELO Homepage  [911 journals]
  • Characterization of the BFO-BZN-based electroceramic composite for
           application as DRA

    • Abstract: Abstract The study and development of ceramic composites are important because of the properties that these materials can provide, such as high dielectric constant and low dielectric loss in the RF and microwave range. Such characteristics make this type of material appropriate to several segments, such as in the telecommunication sector, especially in dielectric resonator antenna (DRA). Ceramic composites provide new materials with a range of properties that can be controlled through the phases to meet the specifications of a given application. This study aimed to synthesize and characterize the composite based on hexaferrite (BFO) and ceramics based on bismuth (BZN), aiming application as DRA. The composites were characterized by FTIR, XRD, and SEM. The composites presented a compact and heterogeneous microstructure, indicating that the sintering at 1000 °C/150 min was adequate for obtaining the ceramic composites; besides, BFO-BZNβ composite was shown to be less porous than the composite BFO-BZNα.Resumo O estudo e desenvolvimento de compósitos cerâmicos possui elevada importância devido às propriedades que esses materiais podem fornecer, tais como elevada constante dielétrica e baixa perda dielétrica na faixa de RF e micro-ondas. Tais características tornam esse tipo de material aplicável a diversos segmentos, como no setor de telecomunicações, em especial em antena dielétrica ressonadora (DRA). Compósitos cerâmicos fornecem novos materiais com uma gama de propriedades que podem ser controladas através das fases para atender as especificações de uma determinada aplicação. Esse estudo teve como objetivo sintetizar e caracterizar o compósito baseado em hexaferrita (BFO) e cerâmicas à base de bismuto (BZN) visando aplicação como DRA. Os compósitos foram caracterizados por FTIR, DRX e MEV. Os compósitos apresentaram microestrutura compacta e heterogênea, indicando que a sinterização em 1000 °C/150 min foi adequada para obtenção dos compósitos cerâmicos, sendo o que compósito BFO-BZNβ se mostrou menos poroso que o compósito BFO-BZNα.
       
  • Cobalt-based pigments for application in ceramic coatings

    • Abstract: Resumo Pigmentos inorgânicos foram preparados com estrutura espinélio para aplicações em revestimentos cerâmicos. Pigmentos com composição CoCr2O4 e Co0,8Zn0,2Cr2O4 foram sintetizados por uma rota química usando gelatina de uso farmacêutico como precursor orgânico. Foram investigadas a influência da dopagem e a temperatura de tratamento térmico na coloração dos pigmentos e dos esmaltes cerâmicos. Os materiais foram caracterizados por análise termogravimétrica, difração de raios X, microscopia eletrônica de varredura, espectroscopia por energia dispersiva, espectroscopia na região do UV-visível e colorimetria. Os pós apresentaram estrutura espinélio a partir de 500 °C, com formação de fase secundária residual de Cr2O3 nas amostras Co0,8Zn0,2Cr2O4 tratadas termicamente a 500 e 1000 °C. Os pigmentos e os esmaltes preparados apresentaram cores em tons de azul esverdeado para as amostras CoCr2O4 e verde para a amostra Co0,8Zn0,2Cr2O4. Os resultados confirmaram a efetividade da rota de síntese utilizada para produzir óxidos com estrutura espinélio.Abstract Inorganic pigments were prepared with spinel structure for applications in ceramic tiles. Pigments with composition CoCr2O4 and Co0.8Zn0.2Cr2O4 were synthesized by a chemical route using gelatin for pharmaceutical use as an organic precursor. The influences of doping and thermal treatment temperature on pigment and ceramic glaze color were investigated. The materials were characterized by thermogravimetric analysis, X-ray diffraction, scanning electron microscopy, dispersive energy spectroscopy, spectroscopy in the UV-visible region and colorimetry. The powders treated at 500 °C presented spinel structure, with the formation of residual secondary phase of Cr2O3 in samples Co0.8Zn0.2Cr2O4 heat-treated at 500 and 1000 °C. The prepared pigments and glazes presented blue-green colors for the samples CoCr2O4 and green color for the sample Co0.8Zn0.2Cr2O4. The results confirmed the effectiveness of the synthesis route used to produce oxides with a spinel structure.
       
  • Effect of niobium content on the wettability of TiO 2: Nb films

    • Abstract: Resumo Filmes de TiO2 dopados com Nb podem associar propriedades como TCO (transparent conductive oxide) e super-hidrofilicidade, quando ativados por luz UV. Filmes metálicos de Ti-Nb foram depositados sobre substrato de vidro via triodo magnétron sputtering e posteriormente os filmes foram oxidados em atmosfera ambiente a 600 °C durante 1,0 h em condições similares àquelas usadas no tratamento térmico de vidros. Medidas de rugosidade, cristalização, composição química e molhabilidade foram realizadas através das técnicas de microscopia de força atômica, difração de raios X, fluorescência de raios X e ângulo de contato, respectivamente. Os resultados mostraram que os filmes foram completamente oxidados, tornando-se visualmente transparentes à luz visível com cristalização da fase rutilo-TiO2. Após irradiação com luz UV, os filmes TiO2:Nb apresentaram rugosidade em escala nanométrica podendo ser classificados como super-hidrofílicos, com valores de ângulo de contato similares àqueles de filmes de TiO2 puros, preservando características de filmes autolimpantes.Abstract Niobium doped TiO2 films can combine properties of TCO (transparent conductive oxide) with superhydrophilicity activated by UV radiation. Ti-Nb metal films were deposited on a glass substrate through triode magnetron sputtering. Afterward, the Ti-Nb metallic films were oxidized at 600 °C during 1.0 h in air atmosphere, with similar parameters of those used in glass heat-treatment. Measurements of roughness, crystallization, chemical composition, and wettability were carried out through atomic force microscopy, X-ray diffraction, X-ray fluorescence, and contact angle, respectively. Results showed that all films were crystallized as rutile-TiO2 phase and were transparent in visible range. TiO2:Nb films showed nanometer roughness that can be classified as superhydrophilic, after activation with UV light. The contact angle values were similar to those of pure TiO2 films, that is, the TiO2:Nb films preserved the self-cleaning properties.
       
  • Evaluation of two processing routes for the synthesis of molybdenum oxide
           with cobalt addition

    • Abstract: Abstract Molybdenum oxides are very interesting technologic materials, which present several industrial uses. The addition of a second metal may enhance its catalytic properties as well as change electronic behavior. Several methodologies for adding a second metal can be found in the literature, however, the comparison between them is hardly ever found. Here two processing routes were tested for the synthesis of molybdenum oxide with cobalt addition: solid-state and wet routes. Ammonium molybdate and cobalt nitrate were used as starting materials and cobalt addition was carried out before calcination. Starting materials were characterized by SEM, FTIR, XRF, and XRD. Calcination products were evaluated by SEM, XRF, XRD and UV-vis spectroscopy. Calcined products whose doping was performed via solid-state presented smaller crystal size (~25 nm), larger cobalt retention (deviation, δ ~10%) and slightly smaller band gap in comparison to those doped via the wet route (~40 nm and δ>11%).Resumo Os óxidos de molibdênio são materiais tecnológicos muito interessantes, que apresentam diversos usos industriais. A adição de um segundo metal pode melhorar suas propriedades catalíticas, bem como alterar o comportamento eletrônico. Várias metodologias para adicionar um segundo metal podem ser encontradas na literatura, porém a comparação entre elas é dificilmente encontrada. Aqui duas rotas de processamento foram aplicadas para a síntese de óxido de molibdênio com adição de cobalto: via sólida e via úmida. Molibdato de amônio e nitrato de cobalto foram usados como materiais de partida e a adição de cobalto foi realizada antes da calcinação. Os materiais iniciais foram caracterizados por MEV, FTIR, FRX e DRX. Os produtos de calcinação foram avaliados por MEV, FRX, DRX e espectroscopia UV-vis. Produto calcinado cuja dopagem foi realizada via estado sólido apresentou menor tamanho de cristal (~25 nm), maior retenção de cobalto (desvio, δ ~10%) e band gap levemente menor em comparação com aquele dopado por via úmida (~40 nm e δ>11%).
       
  • Experimental analysis and finite element modeling of the piston-on-three
           balls testing of Y-TZP ceramic

    • Abstract: Abstract The objectives of this study were to characterize and evaluate the physical and mechanical properties of an experimental zirconia for dental application and compare the biaxial flexural strength results with the finite element simulation (FEM). Yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) ceramic samples were sintered at 1475 °C/2 h and characterized by X-ray diffraction, scanning electron microscopy, relative density, flexural strength using piston-on-three balls (P-3B) test and Young’s modulus. From the flexural strength results, numerical simulations were performed using Abaqus software. The complete model used 70216 elements, considering the components of the test. The results indicated full densification of sintered samples, ZrO2-tetragonal and ZrO2-cubic as crystalline phases, and average grain size of 0.6±0.2 μm. Mechanical characterization of sintered samples indicated Young’s modulus of 195±4 GPa, flexural strength of 1191±9 MPa and Weibull modulus m=16.3. FEM simulation indicated a flexural strength close to 1100 MPa, with a difference lower than 7% in relation to the experimental results. The results were compared associating the physical and mechanical properties of Y-TZP with its intrinsic phenomena such as tgm transformation and ferroelastic domain.Resumo O objetivo deste estudo foi caracterizar e avaliar as propriedades físicas e mecânicas de uma zircônia experimental para aplicação odontológica e comparar os resultados da resistência à flexão biaxial com a simulação de elementos finitos (MEF). Amostras de zircônia tetragonal estabilizada com ítria (Y-TZP) foram sinterizadas a 1475 °C/2 h e caracterizadas por difração de raios X, microscopia eletrônica de varredura, densidade relativa, resistência à flexão usando teste de pistão em três bolas (P-3B) e módulo de Young. A partir dos resultados de resistência à flexão, foram realizadas simulações numéricas utilizando o software Abaqus. O modelo completo utilizou 70216 elementos. Os resultados apontaram para densificação total em amostras sinterizadas, ZrO2 tetragonal e cúbica como fases cristalinas, tamanho de grão de 0,6±0,2 μm, módulo de Young de 195±4 GPa, resistência à flexão de 1191±9 MPa e módulo de Weibull m=16,3. A simulação numérica indicou uma resistência à flexão próxima de 1100 MPa, com diferença menor que 7% em relação aos resultados experimentais. Os resultados foram comparados associando as propriedades físicas e mecânicas de Y-TZP com seus fenômenos intrínsecos, como a transformação tgm e o domínio ferroelástico.
       
  • Substitution effect of Y3+ ions on the structural, magnetic and electrical
           properties of cobalt ferrite nanoparticles

    • Abstract: Abstract Y3+-doped cobalt ferrite nanoparticles, CoYxFe2-xO4 (x=0.00, 0.05, 0.10, 0.15), were synthesized using the sol-gel auto-combustion technique. Single-phase cubic spinel structure was confirmed by the X-ray diffraction technique. The lattice parameter increased with the increase of Y3+ content in the cobalt ferrite and varied from 8.3876 to 8.4271 Å. FE-SEM images showed that the samples had distinct crystalline nanoparticles of spherical shape with small agglomeration. EDAX results showed good agreement with the particularized composition. Magnetic measurement using a vibrating sample magnetometer (VSM) recorded a reduction in saturation magnetization (Ms) and coercivity (Hc) by Y3+ substitution. The values of Ms and Hc ranged from 66.61 to 17.52 emu/g and 1168.9 to 801.9 Oe, respectively. The electrical properties of Y3+-substituted cobalt ferrite were studied by measuring the dielectric constant and loss. With increasing frequency, the value of the dielectric constant decreased, as a natural behavior of the ferrite material.Resumo Nanopartículas de ferrita de cobalto dopada com Y3+, CoYxFe2-xO4 (x=0,00, 0,05, 0,10, 0,15), foram sintetizadas usando a técnica de autocombustão sol-gel. A estrutura de espinélio cúbico monofásica foi confirmada pela técnica de difração de raios X. O parâmetro da rede aumentou com o aumento do teor de Y3+ na ferrita de cobalto e variou de 8,3876 para 8,4271 Å. Imagens de MEV mostraram que as amostras possuíram nanopartículas cristalinas distintas de forma esférica com pequena aglomeração. Os resultados de EDAX mostraram boa concordância com a composição especificada. A medição magnética usando o magnetômetro de amostra vibrante (VSM) registrou uma redução na magnetização de saturação (Ms) e coercividade (Hc) pela substituição de Y3+. Os valores de Ms e Hc variaram de 66,61 a 17,52 emu/g e 1168,9 a 801,9 Oe, respectivamente. As propriedades elétricas da ferrita de cobalto substituído com Y3+ foram estudadas por meio da medição de constante e perda dielétrica. Com o aumento da frequência o valor da constante dielétrica diminuiu, conforme comportamento natural da ferrita.
       
  • Study of the effect of diatomite on physico-mechanical properties of
           concrete

    • Abstract: Abstract Concretes present great potential to be used in many areas of civil construction. Their properties can be improved by substitution or addition of alternative materials to the Portland cement. The diatomite is a sedimentary material composed mainly by silica and amorphous impurities, presenting very fine particle size, high porosity, and low specific mass. Concrete was produced in a ratio of 1:1:2 (cement: sand: gravel) with the addition of diatomite at contents of 5% and 10% by cement weight and a water/cement ratio of 0.54. The physico-mechanical properties of the concretes were evaluated by tests of compressive strength and water absorption by immersion. Also, X-ray diffraction and scanning electron microscopy were carried out to analyze the main phases in the cement paste. The results indicated that the addition of diatomite in the concrete increased the compressive strength due to the silica content in the material and reduced slightly the porosity.Resumo Os concretos apresentam alto potencial de uso nas mais diversas áreas da construção civil e suas propriedades podem ser melhoradas através da utilização de materiais alternativos por substituição ou adição ao cimento Portland. A diatomita é um material sedimentar composto principalmente por sílica e impurezas amorfas e possui granulometria muito fina, alta porosidade e baixa massa específica. Foram produzidos concretos em proporção de 1:1:2 (cimento: areia: brita) com adição de diatomita em níveis de 5% e 10% em massa de cimento e relação água/cimento de 0,54. As propriedades físico-mecânicas dos concretos foram avaliadas por meio dos ensaios de resistência à compressão e absorção de água por imersão. Também foram realizados ensaios de difratometria de raios X e microscopia eletrônica de varredura para análises das principais fases na pasta de cimento. Os resultados indicaram que a adição de diatomita no concreto aumentou a resistência à compressão devido ao teor de sílica no material e reduziu levemente a porosidade.
       
  • Fabrication and characterization of dielectric ceramics using alumina and
           aluminosilicates

    • Abstract: Abstract The aim was to study formulations containing aluminosilicate and alumina in order to obtain compositions with suitable properties to fabricate dielectric ceramic devices. Initially, the precursors were subjected to chemical, mineralogical and granulometric characterization. The formulations were defined and specimens were pressed (19.6 MPa) in shapes of disc and rectangular bar. Specimens were dried, heat-treated at 1400, 1450 and 1500 °C and the mineralogical, morphological, physical, dielectric and mechanical properties were evaluated. The relative dielectric constant (εr) and loss tangent (tanδ) were evaluated at 0.1, 1, 10 and 100 kHz at room temperature. The mullite was the major phase for the studied temperature range. Compositions with a higher content of fluxes showed lower porosity and better dielectric properties and flexural strength. Values of εr at 1 kHz (~3.5 to 4.5) were close to that of the mullite for the samples fired at 1400 °C.Resumo O objetivo foi estudar formulações contendo aluminossilicatos e alumina visando obter composições com propriedades adequadas para fabricação de componentes cerâmicos dielétricos. Inicialmente os precursores foram submetidos à caracterização química, mineralógica e granulométrica. As formulações foram definidas e os corpos de prova foram prensados (19,6 MPa) em forma de disco e barra retangular. Os espécimes foram secos, tratados termicamente entre 1400 e 1500 °C e as características mineralógica, morfológica, física, dielétricas e mecânicas foram avaliadas. A constante dielétrica relativa (εr) e a tangente de perdas (tanδ) foram avaliadas a 0,1, 1, 10 e 100 kHz à temperatura ambiente. A fase mulita foi majoritária para a faixa de temperatura estudada. Composições contendo maior teor de fundentes apresentaram menor porosidade e melhores propriedades dielétricas e resistência à flexão. Valores de constante dielétrica na frequência de 1 kHz (εr ~3.5 a 4.5) foram próximos ao da mulita, para as composições sinterizadas a 1400 °C.
       
  • Freeze casting process for the generation of graded porosity in
           Al2O3 ceramics

    • Abstract: Abstract Alumina ceramic materials with graded functional porosity were prepared by the freeze casting method and characterized. The effects of processing route parameters on the pore formation were studied. Pore characteristics were investigated concerning morphology and distribution in the ceramic matrix. The mercury intrusion method was used to evaluate the porosity. Mechanical properties, as well as the fracture mode, were investigated by the uniaxial compression test. Scanning electron microscopy was used to analyze and correlate the created interface between the layers with the mechanical response. The results suggested that the porosity obtained in all samples was similar, even with varying parameters (different suspension solidification configurations). When evaluating the mechanical behavior, these distinct parameters showed drastic differences in compressive strength and failure mode. This was due to the formation of interfaces between the layers of different porosities, according to the solidification configuration. The interfaces modified the fracture mode, changing from a longitudinal-directed to an interface-directed fracture. The pore microstructure and morphology indicated highly connected pore channels.Resumo Foram efetuadas a preparação e a caracterização de materiais cerâmicos de alumina com gradientes funcionais de porosidade utilizando o método de freeze casting. Foram estudados os efeitos dos parâmetros da rota de processamento na formação dos poros. As características dos poros foram analisadas quanto à morfologia e distribuição na matriz cerâmica. O método de porosimetria de mercúrio foi utilizado para avaliar a porosidade. As propriedades mecânicas, bem como o modo de fratura, foram investigadas em teste de compressão uniaxial. A microscopia eletrônica de varredura foi empregada para analisar a morfologia dos poros e correlacionar a interface formada entre as camadas com a resposta mecânica do material. Os resultados sugeriram que a porosidade obtida em todas as amostras foi semelhante, mesmo variando os parâmetros de processo (diferentes configurações de solidificação de suspensão). Ao avaliar o comportamento mecânico, esses diferentes parâmetros alteraram drasticamente a resistência à compressão e o modo de falha, devido à formação de interfaces entre as camadas de diferentes porosidades, de acordo com a configuração de solidificação. As interfaces modificaram a forma de fratura passando de uma fratura em direção longitudinal para uma na direção das interfaces. A microestrutura dos poros indicou que foram obtidos canais de poros altamente conectados.
       
  • Influence of MgO and CaCl2 on the rheological properties of bentonitic
           clays from the new Paraíba-Brazil deposits using experimental planning
           and statistical analysis

    • Abstract: Abstract New deposits of bentonite clays have been discovered in the Brazilian State of Paraíba; the most recent was at the municipality of Olivedos. Recent studies have discovered the presence of high levels of non-clay minerals that can produce unsatisfactory results when attempting to use these clays in drilling fluids. In order to make them suitable for this purpose, the MgO and CaCl2 as chemical additives were used and their influences on the rheological properties of these clays were analyzed, using an experimental planning technique and statistical analysis. The samples were obtained using experimental modeling by the delineation of mixtures technique; first, the clays were transformed with sodium carbonate and then dosed with MgO and CaCl2. The rheological properties, apparent viscosity (AV) and plastic viscosity (PV) were determined according to the Petrobras standard (AV≥15 cP; PV≥4 cP). The results showed that the values of AV and PV increased considerably and that MgO was the additive that contributed most to the improvement of these properties, making these additives suitable for use in water-based drilling fluids.Resumo Novos depósitos de argila bentonítica foram descobertos no estado brasileiro da Paraíba, sendo o mais recente no município de Olivedos. Estudos recentes descobriram a presença de altos níveis de minerais não argilosos que podem produzir resultados insatisfatórios ao tentar usar essas argilas em fluidos de perfuração. Para torná-los adequados para esse fim, utilizaram-se MgO e CaCl2 como aditivos químicos e analisaram-se suas influências nas propriedades reológicas dessas argilas, utilizando técnica de planejamento experimental e análise estatística. As amostras foram obtidas utilizando modelagem experimental pela técnica de delineamento de misturas; inicialmente as argilas foram transformadas com compostos de sódio e posteriormente dosadas com MgO e CaCl2. As propriedades reológicas, viscosidade aparente (AV) e viscosidade plástica (PV), foram determinadas de acordo com a normativa da Petrobras (AV≥15 cP; PV≥4 cP). Os resultados mostraram que os valores de AV e PV aumentaram consideravelmente e que o MgO foi o aditivo que mais contribuiu para a melhoria dessas propriedades, tornando-os adequados para uso em fluidos de perfuração à base de água.
       
  • Influence of the additivation process on cation exchange capacity and
           viscosity of bentonitic clay dispersions

    • Abstract: Abstract In Brazil, bentonite clays are not naturally sodic and it is an industrial practice the sodium additivation, since sodium ion expands their lamellae allowing a larger amount of water to penetrate. The objective was to analyze the influences of the use of sodium carbonate on the clay during the additivation process, the moisture content and the cure time on cation exchange and viscosity of bentonite clay dispersions for water-based drilling fluids, since there is a shortage of studies on this subject. Newly discovered bentonite clays in Paraíba State, Brazil, were chemically, physically and mineralogically characterized and were additivated with sodium carbonate in aqueous solution (process 1) or in powder form (process 2). Samples with 25% to 60% of moisture (dry basis) were prepared and submitted to cure times of 7 to 45 days. Process 1, as expected, showed better results of cation exchange capacity, viscosity and filtrate volume. The ideal cure time was 15 days. After this period there was a reversal of the cation exchange reactions.Resumo No Brasil, as argilas bentoníticas não são naturalmente sódicas e é uma prática industrial a aditivação sódica, uma vez que o íon de sódio expande suas lamelas permitindo a penetração de uma maior quantidade de água. O objetivo foi analisar as influências da adição do carbonato de sódio na argila durante o processo de aditivação, do teor de umidade e do tempo de cura na troca de cátions e viscosidade de dispersões de argilas bentoníticas para fluidos de perfuração à base de água, uma vez que há escassez de estudos neste tema. Argilas bentoníticas recém descobertas do estado da Paraíba, Brasil, foram caracterizadas química, física e mineralogicamente e aditivadas com carbonato de sódio em solução aquosa (processo 1) ou na forma de pó (processo 2). Amostras com 25% a 60% de umidade (base seca) foram preparadas e submetidas a tempos de cura de 7 a 45 dias. O processo 1, como esperado, apresentou melhores resultados de troca catiônica, viscosidade e volume de filtrado. O tempo de cura ideal foi de 15 dias. Após esse período houve reversão das reações de troca de cátions.
       
  • Development of electrically conductive concrete

    • Abstract: Abstract The effects of the addition of steel fiber and graphite powder on the electric conductivity of concrete were investigated. The percolation transition zone of the concrete + steel fiber was determined, thus fixing the optimum content of steel fiber at 8.5%. Graphite was added to investigate its influence on the electrical conductivity and mechanical properties of the concrete. The electric current passing through the specimens was measured, setting the electric voltage to 50 V. The surface temperature of the specimens submitted to the electrical current was measured for 20 min. It was observed that the higher the graphite addition, the higher the conductivity was and, therefore, the higher the final temperature, which achieved 58 °C higher than the reference mixture, but the compressive strength decreased from 60 to 30 MPa, although still considered as structural concrete.Resumo Os efeitos da adição de fibra de aço e pó de grafita na condutividade elétrica do concreto foram investigados. Determinou-se o limiar de percolação do concreto fibra de aço, fixando-se o teor ótimo de fibras em 8.5%. O pó de grafita foi adicionado para investigar sua influência na condutividade elétrica e nas propriedades mecânicas do concreto. Mediu-se a corrente elétrica passante pelos corpos de prova, aplicando-se uma tensão de 50 V. A temperatura superficial dos corpos de prova submetidos à passagem de corrente elétrica foi medida durante 20 min. Observou-se que quanto maior a adição de grafita, maior foi a condutividade e, portanto, maior a temperatura final, que atingiu 58 °C a mais que a mistura de referência, mas a resistência à compressão reduziu de 60 para 30 MPa, porém ainda sendo considerado um concreto para fins estruturais.
       
 
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