Counterion
Mostrando 13-24 de 103 artigos, teses e dissertações.
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13. Estudo da interaÃÃo entre compostos orgÃnicos volÃteis e filme finos de polipirrol
Conducting polymers can be used as active materials of sensing devices that find application in different areas, such as quality control of products in industries such as food and beverage, cosmetics and solvents, in the monitoring of air quality for environmental and safety purposes, and as an auxiliary tool in the diagnosis of diseases. In spite of this, a
Publicado em: 2007
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14. Surfactant and counter-ion distribution in styrene-butyl acrylate-acrylic acid dry latex submonolayers
Submonocamadas de látex estireno-acrílico preparado usando um tensoativo sulfonato reativo e um tensoativo fosfato não-reativo foram examinadas em um microscópio de transmissão equipado com um espectrômetro de perda de energia de elétrons, para a aquisição de mapas de distribuição elementar. P está ausente do centro das partículas mas é encontr
Journal of the Brazilian Chemical Society. Publicado em: 2004-02
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15. Formação e caracterização óptica de filmes automontados de POMA/PPV
A study is presented of the formation and optical properties of polymeric heterostructures from poly(p-phenylene vinylene) (PPV) and poly(o-methoxyaniline) (POMA) produced via the self-assembly technique. POMA layers were obtained in a non self-limiting process from its emeraldine salt, semiconducting form in HCl solution. Thermal conversion of PPV was perfo
Química Nova. Publicado em: 2003-03
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16. Estudo das estruturas de solvatação e das propriedades dinamicas de soluções aquosas de Li2C4O4 por simulações de dinamica molecular
Molecular dynamic simulation was performed for the first time to Li2C4O4 aqueous solution with the objective of studying solvation of squaric anion in the microscopic level and get a better understanding of the behavior of this anion in solution. Through an analysis of the simulation trajectories, we suggested a possible structure to the solvent cage whose e
Publicado em: 2000
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17. Quimica do estado solido : preparação, caracterização, comportamento termico e reações topoquimicas em tiometalatos do tipo AM52 (A=K, Ag, Ba e M=Fe)
This is a study on the preparation, characterization, ion-exchange and thermal bahavior of iron potassium sulfide, KFeS2. The structure of this solid is basically composed by edge-sharing FeS4 tetrahedra forming negatively charged linear chains [FeS2]n. Potassium ions act as counter-ion. The Fe-Fe distance within the chains is greater than the distance betwe
Publicado em: 1993
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18. Estrutura de ions complexos adsorvidos sobre superficie de silica gel modificada com 1,4-diazabiciclo (2.2.2.) octano
Silica gel having 242 mg specific surface area, average diameter pore of 100 Å, was chemically modified with 3-[1-onio-4-azabicyclo(2.2.2)octane]propyl trimetoxisilane chIoride, resulting in 0.35 mmol g functionalization degree. Adsorption of Cu(II), Co(II), Ni(II), Zn(II), Cd(Il) and Hg(Il) were carried out in absolute ethanol. Although the amina monoquate
Publicado em: 1991
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19. Oxidação biomimetica de cicloexano por peroxido de hidrogenio catalisada por sais de cobre (II)
Cyclohexane was oxidized by the GoChAgg system (pyridine, copper (II) salt, H2O2 under ambient conditions. The only reaction product was cyclohexanone. Efficiency and turnover number were studied as a function of the following reaction parameters; temperature; amount of catalyst, substrate and oxidant; presence of acetic acid; effect of counter-ion associate
Publicado em: 1991
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20. Estudo dos ions benzenossulfonato, benzoato e anilinio em soluções micelares atraves dos tempos de relaxação de 13C de ressonacia magnetica nuclear
Carbon-13 spin-lattice relaxation times were used to characterize the behavior of ionic solutes in isotropic micellar solutions. Threee monosubstituted benzene were analyzed, benzenesulfonate, benzoate and anilinium ions, in micellar solutions prepared using the surfactants alkyltrimetylammonium bromide (C10, C14 and C16), decylammonium chloride, potassium d
Publicado em: 1990
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21. Evaluation of the counterion condensation theory of polyelectrolytes.
We compare free energies of counterion distributions in polyelectrolyte solutions predicted from the cylindrical Poisson-Boltzmann (PB) model and from the counterion condensation theories of Manning: CC1 (Manning, 1969a, b), which assumes an infinitely thin region of condensed counterions, and CC2 (Manning, 1977), which assumes a region of finite thickness.
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22. Roles of Boundary Conditions in DNA Simulations: Analysis of Ion Distributions with the Finite-Difference Poisson-Boltzmann Method
The wide use of lattice-sum strategies in biomolecular simulations has raised many questions on potential artifacts in these strategies. One interesting question is the artifacts in the counterion distributions of highly charged systems. As one would anticipate, Coulombic interactions under the periodic boundary condition may deviate noticeably from those un
The Biophysical Society.
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23. Localization of the retinal protonated Schiff base counterion in rhodopsin.
Semiempirical molecular orbital calculations are combined with 13C NMR chemical shifts to localize the counterion in the retinal binding site of vertebrate rhodopsin. Charge densities along the polyene chain are calculated for an 11-cis-retinylidene protonated Schiff base (11-cis-RPSB) chromophore with 1) a chloride counterion at various distances from the S
The Biophysical Society.
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24. Thermodynamic extent of counterion release upon binding oligolysines to single-stranded nucleic acids.
A major contribution to the binding free energy associated with most protein-nucleic acid complexes is the increase in entropy due to counterion release from the nucleic acid that results from electrostatic interactions. To examine this quantitatively, we have measured the thermodynamic extent of counterion release that results from the interaction between s