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Mostrando 25-36 de 1299 artigos, teses e dissertações.
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25. Adsorption of Calcium(II), Cadmium(II) and Copper(II) Ions from Water by Prepared Silicon-Aluminum-Zirconium Oxide Using Sol-Gel Process
Ternary oxide silica-alumina-zirconia (SiO2/Al2O3/ZrO2) obtained by the sol-gel process was applied as novel adsorbent of ions in aqueous solution. Batch isotherms were performed using standard CuII, CdII and CaII solutions at variable pH and different concentrations. Adsorption capacity was best at weakly acidic pH. The maximum adsorption capacities were 2.
J. Braz. Chem. Soc.. Publicado em: 2021-07
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26. Nonconceptualism and content independence
Resumen: El No-Conceptualismo de Estados es la posición según la cual estados (no contenidos) perceptivos son diferentes en especie respecto a estados (no contenidos) cognitivos, en la medida en que un sujeto podría instanciar ciertos estados perceptivos aun si careciera de los conceptos necesarios para describir dichos estados. Aunque esta posición ha s
Trans/Form/Ação. Publicado em: 2021-06
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27. Evaluation of the use of silica-alumina refractory waste as a supplementary cementitious material
Abstract The use of supplementary cementitious materials (SMCs) is one of the three essential factors for the sustainability of the cement industry. To reduce CO2 emissions, several studies have introduced new methods for the utilization of industrial wastes such as the addition into cementitious materials. The objectives of this study were to chemically and
Cerâmica. Publicado em: 2021-06
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28. Optimization and Study of the Response Surface of Properties for the Synthesis of ZSM-5 Zeolites with Hierarchical Pore Structure Obtained by Desilication
Hierarchical ZSM-5 zeolites were prepared by alkali treatment (desilication) at two temperatures, two reaction times, and two NaOH concentrations. A 23 factorial design was used to study the effect of these variables on the crystallinity, microporosity, and mesoporosity of the zeolite due to the desilication treatment. The factorial design analysis showed th
J. Braz. Chem. Soc.. Publicado em: 2021-06
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29. QUANTIFICAÇÃO DE MULLITA PROVENIENTE DE RESÍDUOS DE CAULIM DA REGIÃO AMAZÔNICA: USO DO MÉTODO DE RIETVELD
Mullite is used to obtain a refractory material, there are several factors that influence the synthesis process of mullite: the preparation of the mixture, the precipitation and the reaction of SiO2 and Al2O3. For the synthesis of mullite, samples of kaolin processing residues were used as precursor material, because it presents SiO2 and Al2O3 in its composi
Quím. Nova. Publicado em: 2021-04
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30. “Si compartimos, alcanza y sobra”. Redes de cuidados comunitarios entre mujeres migrantes del Gran Buenos Aires frente al COVID19
Resumen A partir de una investigación-acción-participativa que comenzó en 2019 en una zona segregada del partido de San Martin del Gran Buenos Aires, este artículo se propone analizar las estrategias de las mujeres migrantes para lidiar con la emergencia sanitaria relacionada al COVID19. Mostraremos que la población migrante residente utiliza sus redes
REMHU, Rev. Interdiscip. Mobil. Hum.. Publicado em: 2021-04
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31. Fenomenología de la inmigración: frontera, territorialización, desplazamiento y sentido de pertenencia
Resumen Las fronteras y las tradicionales territorialidades socioespaciales han estado caracterizado por una delimitación con los estados y territorios y la noción de que las fronteras son consecuencias físicas de procesos políticos, sociales y/o económicos. El espacio/lugar geográfico se ha construido históricamente a través de sistemas de símbolos
REMHU, Rev. Interdiscip. Mobil. Hum.. Publicado em: 2021-04
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32. Use of rice husk ash to produce alternative sodium silicate for geopolymerization reactions
Abstract This study investigated the feasibility of synthesizing sodium silicate from rice husk ash (RHA) and its application to produce geopolymers. Samples were prepared at different SiO2/Al2O3 molar ratios (3.0, 3.5, and 4.0) for both sodium silicates (commercial and from RHA). They were underwater cured at 60 ºC for 1 h and then at room temperature (25
Cerâmica. Publicado em: 2021-03
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33. Thermal decomposition and reaction sintering for synthesis of mullite-zirconia composite using kaolin, γ-alumina and zirconia
Abstract The refractory materials used in the wall of the furnaces for glass melting can be prepared from mullite-zirconia composite material. The composite of mullite/zirconia was synthesized from Iraqi kaolin, γ-alumina, and zirconia using thermal decomposition with reaction sintering at 1600 °C. Several batches were prepared with various ratios of kaoli
Cerâmica. Publicado em: 2021-03
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34. Influence of Mn2+ ions on depression of quartz and spessartine in gondite ore
Abstract Low-grade manganese ores that are composed of manganese oxides, wad, quartz, iron oxides, gibbsite, and especially of spessartine (Mn3Al2(SiO4)3) are known as gondite. Spessartine is a mineral with a high content of silica (SiO2) and alumina (Al2O3) that causes a decrease of the enrichment in manganese oxide concentrates by flotation, giving this o
REM, Int. Eng. J.. Publicado em: 2021-01
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35. Reordering of Depolymerized Silicates as Adsorbents for Large Nitrogen Compounds
The adsorption capacities of two synthesized zeolites (crystalline ZSM-5 and semi-crystalline faujasite Y) for a mixture of indole, quinoline and carbazole were studied. The different samples obtained show different crystalline degree, mesoporosity and Si/Al ratios. The synthesis procedure is based on the simultaneous depolymerization of a mixture of high su
J. Braz. Chem. Soc.. Publicado em: 2021-01
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36. LA IGLESIA CONTINENTAL QUE LLEGABA AL CONCILIO. ECLESIOLOGÍA DE LOS VOTA DE LOS OBISPOS LATINOAMERICANOS PARA EL CONCILIO VATICANO II
RESUMEN El artículo revisa todas las propuestas (o vota) enviadas por los obispos latinoamericanos y de El Caribe a la Comisión Antepreparatoria del Concilio Vaticano II sobre los temas que deberían ser tratados en la asamblea conciliar, para descubrir, a través de ellos, la eclesiología subyacente en los obispos que participaron en el concilio. El text
Perspect. Teol.. Publicado em: 2020-12