Chemical Bond
Mostrando 1-12 de 364 artigos, teses e dissertações.
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1. Identifying conceptions of the covalent bond: an analysis from a systematic review
The covalent bond is a classical topic in science education because it is fundamental to a considerable number of other concepts and by its ability to interpret several chemical phenomena. However, the process of learning this concept presents some difficulties discussed here. This article brings together the conceptions related to the covalent bond, identif
Química Nova. Publicado em: 2022
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2. Household Infrared Technology as an Energy-Efficient Approach to Achieve C-Cπ Bond Construction Reactions
We examined the ability of short-wave infrared (IR) light in the λ1.5-3.0 μm region of the infrared emission spectrum to accomplish C-Cπ bond construction reaction between π-excessive azaheteroaromatic and different carbonyl substrates supported on a bentonitic clay catalyst in solventless condition via a three-component condensation reaction. Preliminar
Journal of the Brazilian Chemical Society. Publicado em: 2022
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3. Through-Bond and Through-Space Interactions in [2,2]Cyclophanes
The interpretation of the distortions of the electron distribution in [2,2]cyclophanes (22-CPs) is controversial. Some studies indicate that there is an accumulation of electron density (ρ) outside the cavity of 22-CPs. The nature of through-space (ts) interaction is still under debate. The relative importance of ts and through-bond (tb) is an open question
J. Braz. Chem. Soc.. Publicado em: 2021-07
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4. An Alternative Description for the Electronegativity Difference in Binary Ionic Solids
We are introducing an alternative analytical expression to the electronegativity difference (∆χ) as a function of the charge ge, g is the charge factor, the fraction of the electronic charge devoted to the bond and e the elementary charge, the packing factor (p) and the effective atomic number (Zeff) of binary ionic solids, by using the very basic Coulomb
J. Braz. Chem. Soc.. Publicado em: 2021-02
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5. Effect of Protein-Based Treatment on Chemical Composition, Hardness and Bond Strength of Remineralized Enamel
Resumo Este estudo avaliou a composição química e microdureza do esmalte humano tratado com solução de Derivados da Matriz do Esmalte (EMD) e a resistência de união entre compósito e este esmalte. Trinta amostras de esmalte humano foram aleatoriamente divididas em três grupos: Esmalte Intocado (UE), Esmalte Desmineralizado (DE) e Esmalte Desminerali
Braz. Dent. J.. Publicado em: 2021-02
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6. Copaifera multijuga, Copaifera pubiflora and Copaifera trapezifolia Oleoresins: Chemical Characterization and in vitro Cytotoxic Potential against Tumoral Cell Lines
Copaifera species (Fabaceae) comprises approximately 70 species of large trees, from which 16 can be found in Brazil. The oleoresins obtained from their trunk are widely used in Brazilian folk medicine, which display important antitumoral potential. Chemically, these oleoresins are mainly composed of a mixture of sesquiterpenes and diterpenes. In this paper
J. Braz. Chem. Soc.. Publicado em: 2020-08
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7. Specific Disulfide Bond Formation Directed by Peptide Nucleic Acids
In this study, we successfully demonstrated a strategy for specific disulfide bond formation by hybridization of two complementary peptide nucleic acid strands. Peptides were linked to the pair of complementary peptide nucleic acids by native chemical ligation, respectively, and base pairing drove the two peptides into close proximity for interchain disulfid
J. Braz. Chem. Soc.. Publicado em: 2020-05
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8. Pesquisas em políticas de comunicação em contextos de crise
By way of Density Functional Theory (DFT)-based computational methods with commercially available software, the computational work of which about the molecular properties, the vibrational modes and vibrational frequencies of finasteride were accomplished for the first time. In order to gain a deeper and more thorough understanding of the molecular structure
Intercom, Rev. Bras. Ciênc. Comun.. Publicado em: 2020-05
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9. VIBRATIONAL SPECTROSCOPIC INVESTIGATION AND MOLECULAR STRUCTURE OF A 5α-REDUCTASE INHIBITOR: FINASTERIDE
By way of Density Functional Theory (DFT)-based computational methods with commercially available software, the computational work of which about the molecular properties, the vibrational modes and vibrational frequencies of finasteride were accomplished for the first time. In order to gain a deeper and more thorough understanding of the molecular structure
Quím. Nova. Publicado em: 2020-05
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10. Glass fiber post treatment – does it influence resin cement bond strength?
Resumo Introdução Pinos de fibra de vidro são utilizados para melhorar a retenção das restaurações em dentes tratados endodonticamente. Objetivo Avaliar a resistência de união de pinos de fibra de vidro submetidos a diferentes tratamentos superficiais e cimentados à dentina radicular com cimento resinoso autoadesivo. Material e método trinta ra
Rev. odontol. UNESP. Publicado em: 26/09/2019
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11. Study of the metallurgical bond between 316 steel substrates and NiCrAlY coating sprayed by HVOF and irradiated with a low power CO2 laser
RESUMO Considerando a importância do desenvolvimento de novos materiais ao longo dos últimos anos; os pesquisadores vêm estudando soluções eficazes através do uso de revestimentos de alta dureza para aplicação em ferramentas de corte e matrizes de conformação. Revestimentos de carboneto de tungstênio (WC) são um dos mais utilizados em sistemas de
Matéria (Rio J.). Publicado em: 16/09/2019
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12. THE EFFECT OF CELLULOSE NANOCRYSTALS IN SUGARCANE BAGASSE PARTICLEBOARDS OF PITH AND FIBERS
ABSTRACT The aim of this research was to investigate sugarcane bagasse (SCB) particleboards, using two kinds of particles, from pith and fibers, reinforced with cellulose nanocrystals (NCC). The NCCs were dispersed in the adhesive urea formaldehyde (UF) using a sonificator in two proportions (0 and 1%). The NCCs and UF were applied in the SCB particles using
CERNE. Publicado em: 09/09/2019