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101.
Andrea Desii Federica Chiellini Celia Duce Lisa Ghezzi Susanna Monti Maria R. Tiné Roberto Solaro 《Journal of polymer science. Part A, Polymer chemistry》2010,48(4):889-897
We investigated the self‐aggregation of 12 short ionic oligopeptides constituted by 4–7 amino acid residues to establish useful structure–property relationships that might be exploited in the biomedical field by using the concept of molecular Lego. We show that the critical aggregation concentration (CAC) of tetrapeptides decreases with increasing hydrophobicity of neutral residues. Additionally, the dependence of the CAC of isomeric oligopeptides on the distribution of amino acid residues confirms the high tendency to self‐organization of molecules with alternating ionic and neutral residues. Indeed, atomic force microscopy (AFM) images recorded on oligopeptide solutions above the CAC show the presence of either fibrillar or spherical aggregates depending on oligopeptide structure and concentration, steric hindrance, solution pH, and time. The potential of the investigated oligopeptides in tissue engineering applications is supported by their in vitro cytocompatibility. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 889–897, 2010 相似文献
102.
Joaquín Barber Fernando Navarro Luis Oriol Milagros Piol Jos Luis Serrano 《Journal of polymer science. Part A, Polymer chemistry》1990,28(4):703-715
Some members of four series of polyesters were synthesized by the direct polycondensation of two types of dicarboxylic acids (4,4′-dicarboxy-α,ω-diphenoxyalkanes and 4,4′-dicarboxy-α,ω-dibenzoyloxyalkanes) with two types of bisphenols (4,4′-dihydroxy-α,ω-diphenoxyalkanes and 4,4′-dihydroxy-α,ω-dibenzoyloxyalkanes) using tosyl chloride in pyridine in the presence of N, N-dimethylformamide. The 1H-NMR spectra of the polymers synthesized showed that these polymers have an ordenated structure. The mesogenic properties of these polymers were studied by optical microscopy and differential scanning calorimetry. Many of the polymers show nematic mesomorphism. 相似文献
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104.
P. Crespo I. Navarro A. Hernando P. Rodrí guez A. Garcí a Escorial J. M. Barandiar n O. Drbohlav A. R. Yavari 《Journal of magnetism and magnetic materials》1995,150(3):409-416
A ferromagnetic solid solution with a nominal atomic composition Fe70Cu30 and a body-centered structure has been obtained by high-energy ball milling. The decomposition of the system is monitored by X-ray diffraction (XRD), magnetic measurements and Mössbauer spectroscopy. According to XRD, for healing temperatures below 723 K there is only a bcc phase in the material, while for heating temperatures above 723 K a new phase, with a fcc structure, appears, suggesting that the solid solution has decomposed into bcc-Fe and fcc-Cu. However, the magnetic behavior observed during the decomposition process indicates that this evolution is more complex than the simple decomposition into the equilibrium phases. This behavior can be summarized in two points: (1) a decrease in the magnetization at 5 K, and (2) drastic changes in the coercive field with the thermal treatment, soft magnetic behavior for the material in the as-milled state, superparamagnetism for low heating temperatures and a hardening of the material heated to above 723 K, for which the values of the coercive field at room temperature are several times higher than those for the as-milled sample. The Mössbauer spectroscopy performed at room temperature shows that for the heat-treated samples the Fe atoms are in two different phases: a ferromagnetic phase, which evolves to bcc-Fe, and a paramagnetic phase. 相似文献
105.
partially supported by DGICYT 相似文献
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108.
Recently, Sr2FeMoO6 has been established as a new colossal magnetoresistance material with substantial low-field magnetoresistance at room temperature and has attracted much attention in the double perovskite family. This material always appears with a certain degree of miss-site disorder where Fe and Mo interchange their positions. Using renormalized perturbation expansion, we calculate the density of states and determine the variation of the critical temperature in the low disorder regime. 相似文献
109.
A. Marcilla M. I. Beltrán R. Navarro 《Journal of Thermal Analysis and Calorimetry》2007,87(2):325-330
The effect of regeneration conditions on
the composition of the gases evolved during the catalytic pyrolysis of low
density (LDPE) and high density polyethylene (HDPE) with HUSY and HZSM5 catalysts
has been analysed by the TG/FTIR technique. When regenerated HUSY was employed,
the evolution of the gases obtained was similar to that with fresh HUSY, indicating
that the regeneration treatment did not affect its properties. Nevertheless
with HZSM5, as the regeneration temperature was higher, the composition of
the gases gradually became more similar to that evolved in the thermal process. 相似文献
110.