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941.
Delgado JL El-Khouly ME Araki Y Gómez-Escalonilla MJ de la Cruz P Oswald F Ito O Langa F 《Physical chemistry chemical physics : PCCP》2006,8(35):4104-4111
Pyrazolino[60]fullerene covalently-linked to ferrocene and N,N-dimethylaniline groups has been prepared and studied using time-resolved spectroscopic methods. The fluorescence quenching of the C(60) moiety indicates that charge-separation takes place via the singlet excited state of the C(60) moiety in both polar and non-polar solvents. The charge-separated state, in which an electron is localized on the C(60) sphere and a hole is located on the whole donor moieties of ferrocene, pyrazole, and N,N-dimethylaniline groups, has been confirmed by nanosecond transient spectra in the visible and near-IR spectral region. The lifetimes of the radical ion-pairs are as long as 30 - 50 ns in both polar and non-polar solvents. 相似文献
942.
[structure: see text] A new transition state of the addition step in the Baeyer-Villiger reaction was found. The role of proton acceptor is played by the carbonyl oxygen atom, and the free energy barrier is 12.7 kcal/mol lower than that previously reported. This finding changes the mechanism for the acid catalysis and could be of interest for similar reactions in which it is known that such catalysis occurs, especially in nonpolar solvents. 相似文献
943.
Isabel Marques Rodrigues Amaral Jo?o Felipe Moreira Neto Gustavo Borges Pereira Mariani Borges Franco Marcelo Emílio Beletti Warwick Estevam Kerr Ana Maria Bonetti Carlos Ueira-Vieira 《Micron (Oxford, England : 1993)》2010,41(2):123-129
Infection in insects stimulates a complex defensive response. Recognition of pathogens may be accomplished by plasma or hemocyte proteins that bind specifically to bacterial or fungal polysaccharides. Several morphologically distinct hemocyte cell types cooperate in the immune response. Hemocytes attach to invading organisms and then isolate them by phagocytosis, by trapping them in hemocyte aggregates called nodules, or by forming an organized multicellular capsule around large parasites. In the current investigation the cellular in the hemolymph third instar larvae of M. scutellaris has been characterized by means of light microscopy analysis and phagocytosis assays were performed in vivo by injection of 0.5 μm fluorescence beads in order to identify the hemocyte types involved in phagocytosis. Four morphotypes of circulating hemocytes were found in 3rd instar larvae: prohemocytes, plasmatocytes, granulocytes and oenocytoids. The results presented plasmatocytes and granulocytes involved in phagocytic response of foreign particles in 3rd instar larvae of M. scutellaris. 相似文献
944.
F. A. Souza N. Carlin C. Beck N. Keeley A. Diaz-Torres R. Liguori Neto C. Siqueira-Mello M. M. de Moura M. G. Munhoz R. A. N. Oliveira M. G. Del Santo A. A. P. Suaide E. M. Szanto A. Szanto de Toledo 《The European Physical Journal A - Hadrons and Nuclei》2010,44(2):181-187
A study of the kinematics of the $ \alpha$ -d coincidences in the 6Li + 59Co system at a bombarding energy of E lab = 29.6 MeV is presented. With exclusive measurements performed over different angular intervals it is possible to identify the respective contributions of the sequential and direct projectile breakup components. The angular distributions of both breakup components are fairly well described by the Continuum-Discretized Coupled-Channels framework (CDCC). Furthermore, a careful analysis of these processes using a semiclassical approach provides information on both their lifetime and their distance of occurrence with respect to the target. Breakup to the low-lying (near-threshold) continuum is delayed, and happens at large internuclear distances. This suggests that the influence of the projectile breakup on the complete fusion process can be related essentially to the direct breakup to the 6Li high-lying continuum spectrum. 相似文献
945.
In this paper we present an actively switched fiber laser with an all-fiber long-period grating-based interferometer used as an intra-cavity loss modulator. The modulator consists of two equal long-period gratings written sequentially in the same piece of a double-clad optical fiber. One of the gratings is fixed onto a piezoceramic cylinder producing fast modulation of the interferometer transmission spectrum. The laser demonstrates a stable regime of pulsed emission at repetition rates in the range of tens of kHz. 相似文献
946.
We construct a sequence of solutions of the exterior Helmholtz equation such that their restrictions form an orthonormal basis
on a given surface. The dependence of the coefficients of these functions on the coefficients of the surface are given by
an explicit algebraic formula. In the same way, we construct an explicit normal derivative of the Dirichlet Green’s function.
We also construct the Dirichlet-to-Neumann operator. We prove that the normalized coefficients are uniformly bounded from
zero.
__________
Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 157, No. 2, pp. 163–174, November, 2008. 相似文献
947.
M. H. Godinho C. Cruz P. I. C. Teixeira A. J. Ferreira C. Costa P. S. Kulkarni C. A. M. Afonso 《Liquid crystals》2008,35(2):103-107
The phase behaviour of a number of N-alkylimidazolium salts was studied using polarizing optical microscopy, differential scanning calorimetry and X-ray diffraction. Two of these compounds exhibit lamellar mesophases at temperatures above 50°C. In these systems, the liquid crystalline behaviour may be induced at room temperature by shear. Sheared films of these materials, observed between crossed polarisers, have a morphology that is typical of (wet) liquid foams: they partition into dark domains separated by brighter (birefringent) walls, which are approximately arcs of circle and meet at “Plateau borders” with three or more sides. Where walls meet three at a time, they do so at approximately 120° angles. These patterns coarsen with time and both T1 and T2 processes have been observed, as in foams. The time evolution of domains is also consistent with von Neumann's law. We conjecture that the bright walls are regions of high concentration of defects produced by shear, and that the system is dominated by the interfacial tension between these walls and the uniform domains. The control of self-organised monodomains, as observed in these systems, is expected to play an important role in potential applications. 相似文献
948.
G. Portnov A.-N. Uthe I. Cruz R. P. Fiffe F. Arias 《Mechanics of Composite Materials》2005,41(2):139-152
The possibility of using force winding coupled with in situ curing to increase the energy storage capacity of hybrid steel-composite cylindrical flywheels is estimated and analyzed. Relations describing the rotational, thermal, and winding stresses are considered and discussed. These relations are used for a numerical analysis of the stress state and energy capacity of hybrid flywheels in the second part of the paper.__________Russian translation published in Mekhanika Kompozitnykh Materialov, Vol. 41, No. 2, pp. 203–224, March–April, 2005. 相似文献
949.
Joao F. P. Gomes Vitor M. A. Cruz Maria L. C. Ribeiro 《Accreditation and quality assurance》2006,11(3):138-145
This paper presents a methodology for estimation of uncertainty on a reference test method for the determination of nitrogen oxides concentration in gaseous emissions from stationary sources. As a first stage for identification of uncertainty sources, the test method is carefully reviewed in detail. Afterwards, these sources are quantified, bearing in mind its partial uncertainty, allowing the determination of the combined uncertainty and, finally, the expanded uncertainty. The calculation procedure was implemented into an excel calculation file. Using this file and considering several numerical applications from real situations, uncertainities around 15 mg/Nm3 over determined concentrations of 350 mg/Nm3 of NO
x
(expressed as NO2) were obtained. 相似文献
950.
Crosslinking of strongly charged chains via multivalent ions of valence z was treated within the Flory approach, which accounts only for the treelike architecture of the clusters formed. Density–density correlations due to the electrostatic nature of the system were considered with a modified random‐phase approximation. At a certain concentration of multivalent ions that play the role of effective stickers among z monomers, an infinitely large polymer network was formed. We analyzed the gelation driven by the formation of locally neutral clusters induced by divalent and trivalent ions. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 766–776, 2004 相似文献