Cation
Mostrando 1-12 de 2724 artigos, teses e dissertações.
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1. NMR Relaxometry Applied to Chemical Studies of Paramagnetic Metal Cation Complexes: Fundamentals and Applications
Low field time-domain nuclear magnetic resonance (TD-NMR) relaxometry of paramagnetic metal cations (PMC) has been widely used to study and improve contrast agents for magnetic resonance imaging (MRI). However, despite its remarkable potential, TD-NMR is rarely used to study PMC complexes, and coordination compounds in non-biomedical application. Therefore,
Journal of the Brazilian Chemical Society. Publicado em: 2022
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2. Influence of the Local Structure on the Photocatalytic Properties of Zinc Spinel Ferrite Nanoparticles
The correlation between iron distribution in octahedral or tetrahedral sites in synthetic magnetite and zinc spinel ferrites and their catalytic properties were investigated in this work. The zinc-doped nanomagnetites were prepared by co-precipitation method and annealed at 420 °C. X-ray diffraction, UV-Vis, X-ray absorption and 57Fe Mössbauer spectroscopi
Journal of the Brazilian Chemical Society. Publicado em: 2022
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3. Expansibility of vermiculite (Santa Luzia, Brazil) irradiated with microwave
Abstract The effect of microwave heating on the expansion of vermiculite was studied at a level of 700 W for 4 min exposure time and compared with raw vermiculite. In this study, the characterization of vermiculite from a mine in the northeast region of Brazil was performed using thermogravimetry, N2-adsorption, cation exchange capacity, X-ray powder diffrac
Cerâmica. Publicado em: 2021-06
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4. Sintering mechanisms of partially stabilized zirconia (TZ3Y) with ZnO and Co3O4 as sintering additives
Abstract In this work, the sintering mechanisms of 3 mol% yttria-stabilized zirconia (TZ3Y) and TZ3Y containing 0.3 wt% of ZnO or Co3O4 were analyzed by determining the apparent activation energy of sintering from dilatometry data and observing the evolution of microstructure. Dilatometry test was performed at a heating rate ranging from 5 to 20 °C/min from
Cerâmica. Publicado em: 2021-06
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5. Síntese e aplicação de TiO2 em células solares: uma análise da proporção de isopropóxido de titânio
Resumo Células solares sensibilizadas por corante são eficientemente desenvolvidas com TiO2 na composição. O isopropóxido de titânio, por possuir uma extensa cadeia alcoxi, evita a aglomeração de núcleos metálicos, gerando partículas com tamanho reduzido, tornando-se um precursor ideal para produção do TiO2. Este trabalho teve como objetivo aval
Cerâmica. Publicado em: 2021-03
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6. Brazilian Mineral Clays: Classification, Acid Activation and Application as Catalysts for Methyl Esterification Reactions
In this study, three raw Brazilian clays from João Pessoa, Paraíba State (Aço AP, AVL and Verde Lodo) were characterized before and after purification and acid activation. Several instrumental techniques were used, and the raw clays were classified as dioctahedral smectites with different compositions, where the AVL sample had the highest content of montm
J. Braz. Chem. Soc.. Publicado em: 2021-01
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7. SOIL CHEMICAL CHANGES AND RESEMBLANCES IN A CHRONOSEQUENCE RAINFOREST-SUGARCANE-PASTURELAND IN THE ATLANTIC FOREST BIOME
ABSTRACT This study evaluated soil chemical and isotopic changes in soils of a chronosequence rainforest-sugarcane-pasture in the Atlantic Forest biome, Brazil. Soil samples were collected (0-20 cm) in areas of native Brazilian Atlantic rainforest, sugarcane plantation and pastures of Brachiaria decumbens. The soil analyses performed were: pH (water 1:2.5),
CERNE. Publicado em: 2020-12
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8. A Symmetrical Dirhenium(I) Complex with 4,4’’-Azobis(2,2’-bipyridine) as a Bridging Ligand: Synthesis, Physicochemical Properties and Applications in Detection of Biologically Relevant Thiols and in Chemotherapy for Bone Cancer
A new dinuclear complex of formula [{Re(CO)3(py)}2(µ-4,4”-azobpy)](PF6)2, with py = pyridine and 4,4”-azobpy = 4,4”-azobis(2,2’-bipyridine), has been synthesized and characterized by spectroscopic and electrochemical techniques. The symmetrical nature of the dimetallic cation has been confirmed by nuclear magnetic resonance (NMR) measurements. When
J. Braz. Chem. Soc.. Publicado em: 2020-11
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9. Intercalation of Apocarotenoids from Annatto (Bixa orellana L.) into Layered Double Hydroxides
Synthetic conditions were evaluated to intercalate norbixin into layered double hydroxides (LDH). Norbixin was isolated from a hydrosoluble commercial annatto extract. LDH samples comprising M2+/Al3+ (M = Mg, Zn) were synthesized by coprecipitation and characterized by X-ray diffraction, thermal analysis coupled to mass spectrometry, vibrational spectroscopi
J. Braz. Chem. Soc.. Publicado em: 2020-11
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10. Geostatistics or machine learning for mapping soil attributes and agricultural practices
ABSTRACT Applying the upcoming technologies in agriculture has been a major economic, environmental and social challenge for scientists and farmers. In order to overcome such challenge, this study evaluated the advantages and limitations of using geostatistics and machine learning for soil mapping in agricultural practices and soil surveys. The study occurre
Rev. Ceres. Publicado em: 2020-08
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11. DIAGNOSIS AND SPATIAL VARIABILITY OF SOIL FERTILITY AND CROP PRODUCTION IN A TEAK AREA IN EASTERN PARÁ STATE.
ABSTRACT This study aims to generate the diagnosis and spatial variability maps of soil fertility attributes, as well as teak (Tectona grandis L.f.) production through geostatistics. The study was conducted on a commercial farm in the municipality of Capitão Poço, state of Pará, Brazil. Soil and yield data were collected from 155 sampled georeferenced poi
CERNE. Publicado em: 2020-03
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12. Geochemical assessment of platinum group metals for phytomining
Abstract Phytomining is suggested as a technology to obtain platinum group metals (PGMs) nanoparticles from plants grown on the mineralized soils or tailings. Samples from North American Palladium (Canada) and gossans from Broken Hill (BH) (Australia) were studied to assess the possibility of using these PGM-rich samples as substrates for phytomining. The bi
REM, Int. Eng. J.. Publicado em: 2020-03