Atomic Spectroscopy
Mostrando 1-12 de 367 artigos, teses e dissertações.
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1. Study of rhombohedral tricalcium phosphate in hexagonal crystal structure family on the sample prepared by the sol-gel route and the effect of calcination temperature
Abstract The effect of the calcination temperature at 800 and 1000 °C on the stable formation of the tricalcium phosphate with rhombohedral structure in the system of the hexagonal crystal family was determined, while its precursor was made from limestone obtained from nature in the Lumajang district, Indonesia. The rhombohedral tricalcium phosphate samples
Cerâmica. Publicado em: 2023
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2. Atomic Absorption Spectrometry as an Alternative to Determine the Presence of Gold Nanoparticles on or in Silica Matrix
Two different gold-silica-based nanomaterials were prepared: (i) silica-supported gold nanoparticles (AuNP/SiO2); and (ii) gold-silica core-shell nanoparticles (AuNP@SiO2). Three strategies for sample treatment (S), consisting in acid treatments, were employed: (S1) HNO3; (S2) HNO3 + HCl; and (S3) HF + HNO3 + HCl, applying microwave oven digestion for S2 and
Journal of the Brazilian Chemical Society. Publicado em: 2022
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3. Phase transformation of kaolinite to hexagonal kalsilite using K2CO3
Abstract Hydrothermal synthesis of kalsilite was facilitated by the inclusion of potassium carbonate (K2CO3) as the source of the potassium ion. After a 24 h reaction at 220 °C, kaolin clay treated with 1.25 M K2CO3 showed the most significant peaks at 2θ of 28.5° and 34.7° by X-ray diffraction corresponding to the hexagonal kalsilite. In addition, field
Cerâmica. Publicado em: 2022
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4. Morphology Behavior of Copper Films Deposited after Wet Surface Treatment on Polished Alumina
In this paper, a pre-treatment process for electroless copper (Cu) deposition on the polished alumina (Al2O3) 99.9% and the behavior of Cu plating by electroless process after Al2O3 surface treatment were explored. Our work was carried out by changing the roughness of Al2O3 through micro-etching (coarsening), nucleation its surface by a two-step method (sens
Journal of the Brazilian Chemical Society. Publicado em: 2022
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5. Study of Crystallization and Composition on Silicon Oxycarbide (SiOC) and Silicon Boron Oxycarbide (SiBOC) Ceramics Obtained from Alkoxysilanes Precursors
This work deals on the preparation of silicon oxycarbide (SiOC) and silicon boron oxycarbide (SiBOC) ceramics from pyrolysis involving alkoxysilanes with different organic groups. Boron content, organic substituent and annealing time were evaluated on crystallization and composition of resulting ceramics. B-free precursors composed of methyltriethoxysilane (
J. Braz. Chem. Soc.. Publicado em: 2021-06
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6. Thallium Associated with Manganese Ore Tailings in a Deactivated Mine in the Western Region of Bahia, Brazil
Thallium (Tl) is a rare metal with toxic effects notably harmful to human health and the environment. In this article, the natural occurrence of Tl was evaluated in a deactivated manganese mine located in the western region of Bahia, Brazil. The extraction procedure with aqua regia was used to dissolve the soil, sediment, and tailings samples. The Tl content
J. Braz. Chem. Soc.. Publicado em: 2021-05
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7. EVALUATION OF THE CHEMICAL COMPOSITION AND STRUCTURE OF ASPHALTENES FROM THREE OFFSHORE BRAZILIAN BIODEGRADED HEAVY OILS
Asphaltenes fractions were extracted and purified from three heavy Brazilian oils. Their mass compositions of C, H, N, Ni and V were obtained from elemental analysis and S and O atomic percentages from EDS. The H/C ratios showed high degree of unsaturation, while the O atomic percentages indicated more pronounced biodegradation effects on two samples. Quanti
Quím. Nova. Publicado em: 2021-04
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8. An Electrochemiluminescence Biosensor for the Determination of Mercury Ion via Dual-Amplification Strategy
A novel dual-signal amplificatory electrochemiluminescence (ECL) deoxyribonucleic acid (DNA) biosensor was designed for the determination of Hg2+. One amplification unit was gold nanoparticles (AuNPs) modified on a glassy carbon electrode, and the other was single-stranded DNA (ssDNA) (with amino at the 3’ terminal and thiol at the 5’ terminal) labeled w
J. Braz. Chem. Soc.. Publicado em: 2020-12
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9. Hybrid Hydrogels Based on Polyethylene Glycol Bioconjugated with Silylated-Amyloidogenic Peptides
Hybrid-peptide hydrogel arrangements are a promising alternative to obtaining biocompatible structures at the nanoscopic scale. In this work, a new class of hybrid hydrogels was obtained through the sol-gel process based on the reaction between an amyloid-like octapeptide sequence [RF]4 (where R = arginine and F = phenylalanine) covalently bonded with glycin
J. Braz. Chem. Soc.. Publicado em: 2020-11
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10. Screening of the Au:Pt Atomic Ratio Supported in SrCO3: Effects on the Performance of the Solvent-Free Oxidation of Benzyl Alcohol
We have prepared, by a sol-immobilization method, bimetallic catalysts with different Au:Pt atomic ratios supported on commercial SrCO3. The catalytic performance for the oxidation reaction of benzyl alcohol of such materials was compared to the monometallic counterparts, aiming at the obtaining of the best composition of the material. It was found that the
J. Braz. Chem. Soc.. Publicado em: 2020-03
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11. Selective Entrapment of Pb2+ from Fresh Thunbergia laurifolia Leaves Extract and Thunbergia laurifolia Tea Extract
The leaves of Thunbergia laurifolia and its tea were extracted by water. The abilities to chelate heavy metal ions of the extracts were studied by inductively coupled plasma-optical emission spectroscopy (ICP-OES) and atomic absorption spectroscopy (AAS). The results showed that the extracts exhibited high selectivity for Pb2+ chelation via a favourable-sele
J. Braz. Chem. Soc.. Publicado em: 2020-03
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12. Biosorption Potential of the Aspergillus sp. and Insights into Secondary Metabolism in the Presence of Copper and Lead
The fungus Aspergillus sp. was isolated from copper mining rejects and cultured in a liquid culture medium (potato dextrose, PD) enriched with CuSO4.5H2O and Pb(NO3)2 in different concentrations. By flame atomic absorption spectrometry (FAAS) it was observed that fungus absorbed 86% of both copper and lead, with initial concentrations of 100, 500 and 1000 mg
J. Braz. Chem. Soc.. Publicado em: 2020-03