Metal Free
Mostrando 1-12 de 407 artigos, teses e dissertações.
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1. RECENT ADVANCES IN CYANATION REACTIONS
Transformations involving structurally complex molecules, natural products and representative molecules are extremely important to obtain key reaction intermediates, in addition to accessing molecules with bioactive properties. The development of cyanation methodologies in those molecules becomes important, because nitriles are versatile and important buildi
Química Nova. Publicado em: 2022
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2. RECENTES APLICAÇÕES DO ORGANOFOTOCATALISADOR 1,2,3,5-TETRAQUIS(CARBAZOL-9-IL)-4,6-DICIANOBENZENO EM TRANSFORMAÇÕES QUÍMICAS
Ruthenium and iridium polypyridine complexes are among the most employed photocatalysts described in literature. The broad applicability is due to the redox potentials and long half-life times of the excited state which these molecules presented. The pursuit for metal-free alternatives has been intensified in the last few years, therefore, many organic fluor
Quím. Nova. Publicado em: 2021-03
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3. Shortcomings in the training program of medical residency during the COVID-19 pandemic in Brazil. How will they be repaired?
Ruthenium and iridium polypyridine complexes are among the most employed photocatalysts described in literature. The broad applicability is due to the redox potentials and long half-life times of the excited state which these molecules presented. The pursuit for metal-free alternatives has been intensified in the last few years, therefore, many organic fluor
Rev. Bras. Ginecol. Obstet.. Publicado em: 2021-03
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4. SYNTHESIS, CHARACTERIZATION, DFT MODELING AND IN VITRO ANTIMYCOBACTERIAL ACTIVITY ASSAYS OF A SILVER(I)-ISONIAZID COMPLEX
In the present work, a silver(I) complex with the antimycobacterial drug isoniazid (inh) is described. Elemental and thermogravimetric analyses confirmed a 1:1 metal:ligand ratio for the silver-isoniazid (Ag-inh) complex with molecular composition AgC6H7N3O·NO3. Infrared (IR) analysis suggests a bidentate coordination of isoniazid to silver by the nitrogen
Quím. Nova. Publicado em: 2021-03
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5. Voltammetric Determination of Free and Total Manganese in Tea Infusions
Tea infusions are a source of mineral nutrients, including manganese. Although it is classified as an essential element, the excess of manganese is toxic for humans and its toxicity depends on its bioavailability. In this context, we propose a simple procedure to determine free and total manganese in black tea infusions by square-wave voltammetry (SWV). Free
J. Braz. Chem. Soc.. Publicado em: 2020-07
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6. CONSTRUCTION AND TESTING OF GLUED LAMINATED TIMBER FRAMES FOR USE IN LAYING POULTRY HOUSES
ABSTRACT This study aimed to present a solution in glued laminated timber to replace frame structures built in reinforced concrete and metallic structure, which are common in agricultural buildings in western Paraná such as those destined to laying poultry house building by agricultural cooperatives. Structural behavior of frames build from Araucaria angust
Eng. Agríc.. Publicado em: 2020-04
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7. 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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8. HOTSPOT STABILIZATION OF GOLD NANOPARTICLES FOR APPLICATION OF QUANTITATIVE SERS IN BIOANALYTICAL SYSTEMS
A complete procedure including synthesizing gold nanoparticles and further hotspots stabilization is presented. Colloidal gold synthesis followed a citrate reducing reaction, then, an ideal condition for SERS enhancement with quantitative purposes was reached by searching equilibrium between salt- and analyte-induced aggregation. Under this condition, a mild
Quím. Nova. Publicado em: 05/12/2019
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9. Preparation and characterization of yttria stabilized zirconia (YSZ) films deposited by dip-coating on LSM-YSZ substrate with different proportions
ABSTRACT In this work, sol-gel/dip-coating process for obtaining yttria stabilized zirconia (YSZ, ZrO2–8% Y2O3) films deposited onto LSM-YSZ (lanthanum strontium manganite (LSM, La0.7Sr0.3MnO3) mixed with YSZ) with different proportions (20/80, 50/50, 80/20) was investigated. The films were deposited on substrate varying the number of layers deposited. LSM
Matéria (Rio J.). Publicado em: 25/11/2019
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10. Nanoparticles of Fe2O3 and Co3O4 as Efficient Electrocatalysts for Oxygen Reduction Reaction in Acid Medium
This paper presents a comparative study about the oxygen reduction reaction (ORR) catalyzed by nanoparticles of Fe2O3 and Co3O4 applied on the surface of glassy carbon electrodes (GCE). The nanoparticles were synthesized using the modified polymeric precursor method (Pechini). These two nanomaterials were characterized by Fourier transform infrared spectrosc
J. Braz. Chem. Soc.. Publicado em: 24/10/2019
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11. Oxone®-Promoted One-Pot Synthesis of 1-Aryl-4-(organylselanyl)-1H-pyrazoles
We describe herein an efficient protocol for the one-pot synthesis of 4-organylselanylpyrazoles by direct cyclocondensation and C-H bond selenylation reactions starting from hydrazines, 1,3-diketones and diorganyl diselenides promoted by Oxone®. The products were obtained through a metal catalyst free methodology, under mild conditions, in short reaction ti
J. Braz. Chem. Soc.. Publicado em: 21/10/2019
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12. Técnica de template customizável para remoção de enxerto ósseo de crista ilíaca para reconstruções de defeitos mandibulares.
RESUMO A remoção de enxerto da crista ilíaca anterior é uma boa opção para a reconstrução de defeitos mandibulares após ressecções por trauma ou outras doenças. Para obtenção de resultados clínicos de excelência em cirurgias reconstrutivas com enxertos ósseos, um planejamento pré-operatório preciso e uma refinada técnica cirúrgica são e
Rev. Col. Bras. Cir.. Publicado em: 23/09/2019