Navegando por Palavras-chave "Scattering"

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    C-12+C-12 fusion in a multichannel folding model
    (Iop Publishing Ltd, 2016) Assuncao, M. [UNIFESP]; Descouvemont, P.; IOP
    The C-12+C-12 fusion reaction is investigated using a folding potential in a multichannel approach involving the C-12(0(1)(+),2(+), 0(2)(+), 3(-)) states. The C-12 densities (including transition densities) are taken from the RGM calculation of Kamimura. For the nucleon-nucleon interaction, we use the DDM3Y density-dependent interaction. Owing to the explicit presence of inelastic channels, the imaginary part of the optical potential only contains a short-range fusion contribution. The S-factor is then virtually insensitive to the precise value, and the model is free of any fitting parameter. From the coupled-channel system, we determine the elastic and fusion cross sections simultaneously. As elastic data are available around the Coulomb barrier, this simultaneous treatment offers a good test for the reliability of the model. In the fusion cross section, the role of the inelastic channels and, in particular of the C-12(0(1)(+))+C-12(0(2)(+)) channel involving the Hoyle state, is discussed.
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    C-12+C-12 fusion in a multichannel folding model
    (Iop Publishing Ltd, 2016) Assuncao, Marlete [UNIFESP]; Descouvemont, Pierre; IOP
    The C-12+C-12 fusion reaction is investigated using a folding potential in a multichannel approach involving the C-12(0(1)(+),2(+), 0(2)(+), 3(-)) states. The C-12 densities (including transition densities) are taken from the RGM calculation of Kamimura. For the nucleon-nucleon interaction, we use the DDM3Y density-dependent interaction. Owing to the explicit presence of inelastic channels, the imaginary part of the optical potential only contains a short-range fusion contribution. The S-factor is then virtually insensitive to the precise value, and the model is free of any fitting parameter. From the coupled-channel system, we determine the elastic and fusion cross sections simultaneously. As elastic data are available around the Coulomb barrier, this simultaneous treatment offers a good test for the reliability of the model. In the fusion cross section, the role of the inelastic channels and, in particular of the C-12(0(1)(+))+C-12(0(2)(+)) channel involving the Hoyle state, is discussed.
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    Development of silver nanoparticles-based sensor for detection of quinolones by surface-enhanced raman spectroscopy: a case-study using levofloxacin
    (Wiley, 2016) Madalossi, Natiara V.; Mazali, Italo O.; Corbi, Fabiana C. A.; Sigoli, Fernando A.; Santos, Elias B. [UNIFESP]
    Numerous studies have shown that a variety of pharmaceuticals such as quinolones have been detected in the vicinity of municipal wastewater discharges and livestock agricultural facilities. Many of those works have been employed conventional analytical techniques and traditional methods of detection. However, in many cases these detection methodologies are time consuming and generate waste, which can be overcome using Surface-enhanced Raman spectroscopy (SERS) as analytical technique. In the present work, silver nanoparticles (AgNP) films were prepared on amine-modified glass slides with different number of depositions. The AgNP aggregates films were tested as SERS substrates using 4-aminobenzenethiol (4-ABT) as model Raman molecule. A trend between the 4-ABT SERS response and the number of AgNP deposition could be identified, which can be associated with the formation of AgNP aggregates. The aggregation effect could be quantified by calculating the enhancement factor (EF), which was on order of 10(6) for the film with five AgNP depositions. This optimized AgNP film was employed as SERS sensor of Levofloxacin in different concentrations, which was easily detected from 10(-4), 10(-5), and 10(-6) mol L-1 solution. Also, the SERS spectral profile are rich in information, which allowed to describe the chemical interaction between the Levofloxacin molecules and the AgNP sensor surface. This study provides an efficient method for detecting of Levofloxacin using AgNP SERS sensor, which can be extended for others quinolones.
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    Sequence length dependence in arginine/phenylalanine oligopeptides: Implications for self-assembly and cytotoxicity
    (Elsevier Science Bv, 2018) Silva, Emerson R. [UNIFESP]; Listik, Eduardo; Han, Sang W. [UNIFESP]; Alves, Wendel A.; Soares, Bruna M.; Reza, Mehedi; Ruokolainen, Janne; Hamley, Ian W.
    We present a detailed study on the self-assembly and cytotoxicity of arginine-rich fragments with general form [RF](n) (n = 1-5). These highly simplified sequences, containing only two L-amino acids, provide suitable models for exploring both structure and cytotoxicity features of arginine-based oligopeptides. The organization of the sequences is revealed over a range of length scales, from the nanometer range down to the level of molecular packing, and their cytotoxicity toward C6 rat glioma and RAW264.7 macrophage cell lines is investigated. We found that the polymorphism is dependent on peptide length, with a progressive increase in crystalline ordering upon increasing the number of [RF] pairs along the backbone. A dependence on length was also found for other observables, including critical aggregation concentrations, formation of chiral assemblies and half maximum inhibitory concentrations (IC50). Whereas shorter peptides self-assemble into fractal-like aggregates, clear fibrillogenic capabilities are identified for longer sequences with octameric and decameric chains exhibiting crystalline phases organized into cross-beta structures. Cell viability assays revealed dose-dependent cytotoxicity profiles with very similar behavior for both glioma and macrophage cell lines, which has been interpreted as evidence for a nonspecific mechanism involved in toxicity. We propose that structural organization of [RP](n) peptides plays a paramount role regarding toxicity due to strong increase of local charge density induced by self assemblies rich in cationic groups when interacting with cell membranes.