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      Funcionalização de superfícies vítreas por plasma de SiCl4 para a retenção de compostos orgânicos Translated title: Glassy surface functionalization by SiCl4 plasma aiming at organic compounds retaining

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          Abstract

          Superfícies planas de vidro comercial, de composição básica soda-lime-silicato, foram tratadas em ambiente de plasma frio de O2 e SiCl4. Após a ação do plasma os vidros foram submetidos a uma seqüência de reações químicas (derivatização) em ambiente gasoso para a inserção de grupos funcionais reativos. Ao final do processo dois compostos orgânicos de interesse biotecnológico foram separadamente imobilizados: a enzima peroxidase e o polissacarídeo quitosana. Cada estágio do tratamento foi acompanhado por espectroscopia de fotoelétrons (XPS) identificando a variação dos principais elementos na superfície vítrea. O objetivo do presente estudo foi avaliar uma seqüência de funcionalização indicada para vidros e confirmar a imobilização dos compostos. Os resultados são de interesse para a confecção de biossensores e reatores de catálise tendo o vidro como suporte sólido.

          Translated abstract

          In the present work flat surfaces, from commercial soda-lime-silicate glass slides, were treated in O2 and SiCl4 cold plasma environment. After plasma glow the surfaces underwent subsequent chemical reactions (derivatization), by inserting reactive functional groups under gas atmosphere. At the end of the process, two organic compounds of biotechnological interest, the enzyme peroxidase and the polysaccharide chitosan, were separately attached to the surface. Each step of surface tailoring was followed by X-ray photoelectron spectroscopy (XPS), and the main elements change or implanted were identified along the treatment. The main aim of this study was to evaluate a functionalization sequence proper to glass and confirm the organic attachment. The results are important concerning biosensor and catalysis reactor assembling having glass as solid support.

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          Most cited references39

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          Determination of the positions and orientations of concentrated rod-like colloids from 3D microscopy data

          Confocal microscopy in combination with real-space particle tracking has proven to be a powerful tool in scientific fields such as soft matter physics, materials science and cell biology. However, 3D tracking of anisotropic particles in concentrated phases remains not as optimized compared to algorithms for spherical particles. To address this problem, we developed a new particle-fitting algorithm that can extract the positions and orientations of fluorescent rod-like particles from three dimensional confocal microscopy data stacks, even when the fluorescent signals of the particles overlap considerably. We demonstrate that our algorithm correctly identifies all five coordinates of uniaxial particles in both a concentrated disordered phase and a liquid-crystalline smectic-B phase. Apart from confocal microscopy images, we also demonstrate that the algorithm can be used to identify nanorods in 3D electron tomography reconstructions. Lastly, we determined the accuracy of the algorithm using both simulated and experimental confocal microscopy data-stacks of diffusing silica rods in a dilute suspension. This novel particle-fitting algorithm allows for the study of structure and dynamics in both dilute and dense liquid-crystalline phases (such as nematic, smectic and crystalline phases) as well as the study of the glass transition of rod-like particles in three dimensions on the single particle level.
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            Improved Semiconductor Lattice Parameters and Band Gaps from a Middle-Range Screened Hybrid Functional

            We show that the middle-range exchange-correlation hybrid of Henderson, Izmaylov, Scuseria and Savin (HISS) performs extremely well for elemental and binary semiconductors with narrow or visible spectrum band gaps, as well as some wider gap or more ionic systems used commercially. The lattice parameters are superior to those predicted by the screened hybrid functional of Heyd, Scuseria and Ernzerhof (HSE), and provide a significant improvement over geometries predicted by semilocal functionals. HISS also yields band gaps superior to those produced by functionals developed specifically for the solid state. Timings indicate that HISS is more computationally efficient than HSE, implying that the high quality lattice constants coupled with improved optical band gap predictions render HISS a useful adjunct to HSE in the modeling of geometry-sensitive semiconductors.
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              Magnetic ordering and magnetodielectric phenomena in CoSeO\(_4\)

              CoSeO\(_4\) has a structure consisting of edge-sharing chains of Co\(^{2+}\) octahedra which are held together by SeO\(_4^{2-}\) tetrahedra via shared oxygen atoms at the edges of the octahedra. DC magnetization measurements indicate a transition to an ordered state below 30 K. Powder neutron diffraction refinements suggest an ordered state with two unique antiferrromagnetic chains within the unit cell. Isothermal magnetization measurements indicate a temperature-dependent field-induced magnetic transition below the ordering temperature. From neutron diffraction, we find this corresponds to a realignment of spins from the canted configuration towards the c-axis. The dielectric constant shows a change in slope at the magnetic ordering temperature as well as a quadratic dependence on the external magnetic field.
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                Author and article information

                Contributors
                Role: ND
                Role: ND
                Journal
                ce
                Cerâmica
                Cerâmica
                Associação Brasileira de Cerâmica (São Paulo )
                1678-4553
                December 2011
                : 57
                : 344
                : 422-427
                Affiliations
                [1 ] Embrapa Brazil
                Article
                S0366-69132011000400008
                10.1590/S0366-69132011000400008
                3327eb0e-1d19-4929-9a8d-59669669c2fc

                http://creativecommons.org/licenses/by/4.0/

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                SciELO Brazil

                Self URI (journal page): http://www.scielo.br/scielo.php?script=sci_serial&pid=0366-6913&lng=en
                Categories
                MATERIALS SCIENCE, CERAMICS

                Ceramics
                cold plasma,functionalization,glass surface,organic compounds immobilization,plasma frio,funcionalização,superfície vítrea,imobilização de compostos orgânicos

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