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111.
A. C. S. da Costa I. G. de Souza Jr. M. A. Batista K. L. da Silva J. V. Bellini A. Paesano Jr. 《Hyperfine Interactions》2007,175(1-3):103-111
Nanosized Fe3???x Zn x O4 powders were synthesized by co-precipitation and characterized by total chemical analysis, X-ray diffraction, magnetic susceptibility and Mössbauer spectroscopy. The results showed that, for x?≤?0.15, the as-prepared samples are mostly zinc-substituted magnetites but have maghemite as a minor phase. For x?≥?0.30, only the Fe3???x Zn x O4 solid solution is found. Increasing the zinc content from the end concentration x?=?0, increases the lattice parameter but smaller become the mean crystalline diameter and the magnetic susceptibility. In addition, the magnetic hyperfine fields of the iron sites in the spinel structure, A and B, decrease up to collapse at x?≤?0.90. 相似文献
112.
The intrinsic bistable terahertz response of intersubband plasmons in wide n-type delta-doped quantum wells is predicted to be enhanced by a resonant Fabry-Perot cavity. With a simple low-Q resonator, the threshold for bistability is decreased by a factor of 2-3 compared with that for bare multiple quantum wells. 相似文献
113.
Singly Periodic Costa Surfaces 总被引:1,自引:0,他引:1
Global Weierstrass representations are derived for completeminimal surfaces obtained by substituting the planar end ofthe Costa surface by Scherk ends. This gives rise to singlyperiodic examples, of which the fundamental piece is provedto be embedded by a simple geometric technique. This techniquecan be generalised for embeddedness proof of future examplesof the same nature. 相似文献
114.
Neuberger MS Sale JE Cumbers SJ Jolly CJ Bemark MP Ehrenstein MR Lanoue A Brüggemann M Batista FD Davies SL Williams GT 《Applied biochemistry and biotechnology》2000,83(1-3):53-60; discussion 60-2, 145-53
The physiological mechanism for producing antigen-specific antibodies is based on a two-phase neo-Darwinian process: the first phase consists of diversity generation (formation of the repertoire), and the second phase is antigen-mediated selection. In this article, we consider how the natural immunoglobulin gene-diversification processes can be exploited both in vivo and in vitro in order to allow the generation of novel antibody (and heterologous protein) repertoires. 相似文献
115.
Rigorous simulations of quantum tunneling dynamics in model systems with up to 20 coupled degrees of freedom are reported. The simulations implement an extension of the recently developed matching-pursuit/split-operator Fourier-transform method to complex-valued coherent-state representations. The resulting method recursively applies the time-evolution operator, as defined by the Trotter expansion to second order accuracy, in dynamically adaptive coherent-state representations generated by an approach that combines the matching-pursuit algorithm with a gradient-based optimization method. 相似文献
116.
117.
Dr. Luís A. E. Batista de Carvalho Dr. M. Paula M. Marques Dr. Christine Martin Dr. Stewart F. Parker Dr. John Tomkinson 《Chemphyschem》2011,12(7):1334-1341
The well‐known platinum(II) chemotherapeutic drugs cisplatin [cis‐(NH3)2PtCl2] and carboplatin [Pt(NH3)2C6O4H6], as well as the analogous transplatin [trans‐(NH3)2PtCl2], were studied by inelastic neutron scattering (INS) spectroscopy, coupled to quantum mechanical methods, and some ancillary work with X‐ray diffraction on powders. An assignment of the experimental spectra was carried out based on the calculated INS transition frequencies and intensities (at the DFT level), thereby achieving a good correspondence between the calculated and observed data. Unusually good‐quality INS spectra were obtained from about 250 mg, which is the smallest sample of a hydrogenous compound for which a successful INS interpretation has been reported. The knowledge of the local configuration of this kind of complexes is essential for an accurate understanding of their activity, which will pave the way for the rational design of novel third‐generation drugs comprising cisplatin‐ and carboplatin‐like moieties. 相似文献
118.
119.
Gari V. Ccana-Ccapatinta Bruno L. Sampaio Fernando M. dos Santos João M. Batista Fernando B. Da Costa 《Tetrahedron: Asymmetry》2017,28(12):1823-1828
Recently, it was observed that infrared (IR) and vibrational circular dichroism (VCD) calculations including deuterated hydroxyl groups in phenolic and saccharide moieties improved significantly the agreement with experimental data obtained in methanol-d4. In the present study, the relative and absolute configurations of three methanol-soluble caffeic acid ester derivatives 1–3, isolated from Tithonia diversifolia, were established by a combined use of experimental and calculated 13C NMR chemical shifts, as well as electronic circular dichroism (ECD) and VCD spectroscopies. Interestingly, the attempt to reproduce the deuteration pattern arising from possible isotopic exchange in methanol-d4 solution led to nearly mirror image calculated VCD spectra for 1 when compared to the non-deuterated molecule with the same absolute configuration. This latter fact can potentially lead to absolute configuration misassignments. A closer inspection of the vibrational chiroptical properties of 1 revealed that the deuteration status of the tertiary hydroxyl group at C-2 is critical for the correct reproduction of experimental VCD data in protic solvents. Therefore, in the case of stereochemical analysis of polar chiral natural product molecules, a combination of VCD and ECD is recommended. 相似文献
120.
Daiane Cristina Sass Vladimir Constantino Gomes Heleno Jader da Silva Barbosa Gustavo Oliveira Morais Fernando Batista Da Costa Mauricio Gomes Constantino 《Tetrahedron letters》2013,54(7):625-627
The conversion of a germacranolide structure (tagitinin C) into a furanoheliangolide one (diversifolin) was achieved by hydride conjugate addition using Stryker’s reagent. 相似文献