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991.
Fourier Transform Infrared Spectroscopy and Thermal Analysis have been used to study the thermal and termooxidative degradation of polysiloxane coatings obtained by treating E-glass fiber with aqueous solutions of 3-chloropropyltriethoxysilane. Initial weight losses were due to polymerization of the coatings. Severe oxidative degradations were observed at temperatures above 180°C. At 550°C the residue of the coating was found to be silica with free silanol groups. 相似文献
992.
A study is carried out by FT-IR spectroscopy of the carbonate species formed upon interaction of CO2 with alumina and vanadia-alumina catalysts doped with sodium. It is found that the presence of sodium enhances the ability of the catalyst surface to adsorb CO2, yielding to carbonate formation. The species formed changes in the presence of vanadium, shifting the νCOO stretching bands towards higher wavenumbers than those recorded in Na-Al2O3 systems. 相似文献
993.
Dr. Ilaria Gamba Iria Salvadó Gustavo Rama Miriam Bertazzon Mateo I. Sánchez Prof. Víctor M. Sánchez‐Pedregal Prof. José Martínez‐Costas Rosa F. Brissos Prof. Patrick Gamez Prof. José L. Mascareñas Prof. Miguel Vázquez López Prof. M. Eugenio Vázquez 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(40):13369-13375
A new bipyridine building block has been used for the solid‐phase synthesis of dinuclear DNA‐binding ruthenium(II) metallopeptides. Detailed spectroscopic studies suggest that these compounds bind to the DNA by insertion into the DNA minor groove. Moreover, the potential of the solid‐phase peptide synthesis approach is demonstrated by the straightforward synthesis of an octaarginine derivative that shows effective cellular internalization and cytotoxicity linked with strong DNA interaction, as evidenced by steady‐state fluorescence spectroscopy and AFM studies. 相似文献
994.
The enantiospecific syntheses of both enantiomers of bacillamide C and neobacillamide A are described, along with the measurement of their optical activities, leading to the revision of the proposed absolute configurations of these natural products. 相似文献
995.
996.
Bo Chen Fangyue Chen Junbiao Guan Genaro J. Mart ''{ i}nez 《Journal of Applied Analysis & Computation》2016,6(4):1164-1179
By introducing a sequence-block transformation and vector-block transformation, we explore the dynamical properties of hybrid cellular automation (HCA) and hybrid cellular automation with memory (HCAM) in the framework of symbolic dynamics. As the local evolution rules of HCA and HCAM are not-uniform, the new uniform cellular automata (CAs) with multiple states are constructed by specifical the block transformations. Furthermore, because the new CA rules are topologically conjugate with the originals, the complex dynamics of the HCA and HCAM rules can be investigated via the new CA rules. 相似文献
997.
Gloria Subías Joaquín García Javier Blasco Javier Herrero‐Martín M. Concepción Sánchez Julia Orna Luis Morellón 《Journal of synchrotron radiation》2012,19(2):159-173
The pattern of charge modulations and local anisotropies below the Verwey transition has been determined and quantified in high‐quality Fe3O4 single crystals and thin films grown on MgO by using resonant X‐ray scattering at the Fe K‐edge. The energy, polarization and azimuthal angle dependencies of an extensive set of reflections with potential sensitivity to charge or local anisotropy orderings have been analyzed to explore their origins. A charge disproportion on octahedral B sites of 0.20 ± 0.05 e? with [0 0 1] and cubic periodicities has been confirmed, while no significant charge disproportion has been obtained with [0 0 1/2] cubic periodicity. Additional charge modulations in the monoclinic a–b plane are also present. In addition, the occurrence of new forbidden (1, 1, 0) and (0, 0, 2n + 1/2) cubic reflections that arise from the anisotropy of the local structure around different tetrahedral and octahedral Fe atoms is shown. This complex pattern of weak charge modulations and local anisotropies is fully compatible with the low‐temperature crystal structure refined in the non‐polar C2/c space group and disproves any bimodal charge disproportion of the octahedral Fe atoms. 相似文献
998.
Chargaff’s second parity rule (CSPR) asserts that the frequencies of short polynucleotide chains are the same as those of the complementary reversed chains. Up to now, this hypothesis has only been observed empirically and there is currently no explanation for its presence in DNA strands. Here we argue that CSPR is a probabilistic consequence of the reverse complementarity between paired strands, because the Gibbs distribution associated with the chemical energy between the bonds satisfies CSPR. We develop a statistical test to study the validity of CSPR under the Gibbsian assumption and we apply it to a large set of bacterial genomes taken from the GenBank repository. 相似文献
999.
E. Miranda C. Garzón C.S. Martínez-Cisneros J. Alonso J. García-García 《Journal of Electrostatics》2012,70(3):264-268
The spatial distribution of tiny holes in sheet materials generated by means of electrical discharges is investigated using spatial statistics techniques. It is shown that whereas the holes appear to be randomly distributed according to a Poisson point pattern, there is in fact a small region around each hole in which the generation of a new one is statistically inhibited as a consequence of the lower impedance path offered by the already made hole. The resulting pattern is known in spatial statistics as a point process with a soft-core inhibition potential, which can be characterized using the pair correlation function. 相似文献
1000.
M. Elena Mart��n M. Luz S��nchez Jos�� C. Corchado Aurora Mu?oz-Losa Ignacio Fdez. Galv��n Francisco J. Olivares del Valle Manuel A. Aguilar 《Theoretical chemistry accounts》2011,128(4-6):783-793
The possible influence of the solvent Stark effect (SSE) on the solvatochromic shift in electron transitions has been analyzed by using the ASEP/MD (averaged solvent electrostatic potential from molecular dynamics) method. With this purpose, four molecules, two polar (acrolein and formaldehyde) and two non-polar (p-difluorobenzene and trans-difluoroethene) have been studied in solvents of diverse polarity. Independently of the nature of the system we found that the contribution of SSE on the average value of the solvent shift or on the multipole moment values is negligible. In the case of centro-symmetric molecules, our results permit to discard the SSE as cause of the solvent shift found, which must be assigned to the electrostatic interaction of the solute quadrupole and higher multipoles with the solvent. As the SSE values provide also a measure of the errors introduced by the mean field approximation (MFA), these results indicate that MFA permits a very accurate determination of the solvent shift at the same time that it reduces drastically the computational cost. Finally, a new procedure suited to the ASEP/MD method has been presented that permits to estimate the inhomogeneous broadening of spectral bands, complementing the information provided by mean field theories. This procedure does not need additional quantum calculations and its computational cost is minimal. 相似文献