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981.
Fluorescence of metal complexes of 8-hydroxyquinoline derivatives in aqueous micellar media 总被引:1,自引:0,他引:1
The fluorescence characteristics of 8-hydroxyquinoline derivative complexes of A1(III), Ga(III), In(III), Zn(II), and Be(II) in differently charged micellar media are reported. For most of the chelates studied, large increases are observed in micellar media compared with those obtained in hydroorganic solvents. However, some exceptions are observed, of which the low fluorescence of Zn(II) chelates in anionic sodium lauryl sulfate media is the most noticeable. 相似文献
982.
Celia Regaño Romina Marín Abdelilah Alla José I. Iribarren Antxon Martínez De Ilarduya Sebastián Muñoz‐Guerra 《Journal of Polymer Science.Polymer Physics》2007,45(1):116-125
The crystal structure and crystallization behavior of a series of poly(ester amide)s derived from L ‐tartaric acid, 1,6‐hexanediamine, and 6‐amino‐1‐hexanol were examined. The study included aregic polymers containing 5, 10, and 20% of ester groups in addition to the syndioregic polymer containing equal amounts of amide and ester groups. X‐ray diffraction data revealed that all the aregic poly(ester amide)s adopt the same crystal structure as the parent polyamide made of L ‐tartaric acid, and 1,6‐hexanediamine. In this structure, chains are slightly compressed and arranged as in the α‐form of nylon 66. Solid‐state nuclear magnetic resonance (NMR) revealed that ester groups are excluded from the crystal phase except for the case of the syndioregic polymer. Isothermal crystallization kinetics was analyzed according to the Avrami theory. Crystallization rates were found to decrease regularly with increasing contents in ester groups and with increasing crystallization temperature. Avrami exponent values close to 2 were found whereas spherulitic morphologies were observed by optical microscopy. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 116–125, 2007 相似文献
983.
We study four measures of problem instance behavior that might account for the observed differences in interior-point method
(IPM) iterations when these methods are used to solve semidefinite programming (SDP) problem instances: (i) an aggregate geometry
measure related to the primal and dual feasible regions (aspect ratios) and norms of the optimal solutions, (ii) the (Renegar-)
condition measure C(d) of the data instance, (iii) a measure of the near-absence of strict complementarity of the optimal solution, and (iv) the
level of degeneracy of the optimal solution. We compute these measures for the SDPLIB suite problem instances and measure
the sample correlation (CORR) between these measures and IPM iteration counts (solved using the software SDPT3) when these
measures have finite values. Our conclusions are roughly as follows: the aggregate geometry measure is highly correlated with
IPM iterations (CORR = 0.901), and provides a very good explanation of IPM iterations, particularly for problem instances
with solutions of small norm and aspect ratio. The condition measure C(d) is also correlated with IPM iterations, but less so than the aggregate geometry measure (CORR = 0.630). The near-absence
of strict complementarity is weakly correlated with IPM iterations (CORR = 0.423). The level of degeneracy of the optimal
solution is essentially uncorrelated with IPM iterations.
This research has been partially supported through the MIT-Singapore Alliance. 相似文献
984.
Isaac Dyner Ricardo A. Smith Gloria E. Peña 《The Journal of the Operational Research Society》1995,46(10):1163-1173
A System Dynamics model to simulate the substitution of installed household appliances by more efficient ones is presented. The model allows the construction of scenarios and also the analyses of several other issues such as: alternatives for technology penetration, electricity consumption growth, gas consumption growth and effects of pricing policies on various energy demands. The proposed methodology has been applied to assist the decision process in relation to gas penetration policies. The model also supports policy making on energy efficiency and it allows the calculation of total energy savings under different scenarios. Furthermore, government underpricing policies on tariffs and appliance acquisition (longer loan terms, lower interest rates and grace periods) may also be analysed. 相似文献
985.
986.
HDPE based composites were produced with 10-20-30 and 40% composite mass of wood fiber. The coupling agents were epolene and
silane. The thermal behavior of composite samples was analyzed as a function of the coupling agent content, the exposure time
and the wood fibers content by means of differential scanning calorimetry. Calorimetric curves of all samples of first and
second heating shows a similar behavior. Some significant relation has been observed between the exposure time and the degree
of crystallinity for the same percentage of fiber samples. A linear relation between the melting enthalpy average vs. content
in cellulosic fibers is detected. Nevertheless, the fibers non-pretreated with coupling agent show a lower loss of crystallinity
of the HDPE matrix at low wood fiber content (10%). A slight diminution of the melting peak temperature is detected as increasing
the exposure time.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
987.
988.
A theoretical study of the gas-phase alkaline hydrolysis of penicillin G on the assumption of a BAC2 mechanism is reported. Various semiempirical methods were used to determine the influence of different parameterizations on the process. Among the most salient results obtained, the standard AM1 method predicted opening of the thiazolidine ring to yield the corresponding imine and enamine structures. 相似文献
989.
Juan Mateos Guilarte JosMaría Muoz Porras Marina de la Torre Mayado 《Journal of Geometry and Physics》1998,27(3-4):297-332
Algebro-geometric methods are applied to the theoretical understanding of the fractionary quantum Hall effect on a periodic lattice. The fermionic Fock space of the many-electron system is precisely identified, and as a consequence, the variational Haldane-Rezayi ground state is decomposed in terms of one-particle wave functions at the first Landau level; the filling factor is thus analytically computed. Quasi-hole and quasi-particle excitations are also analyzed. The center of mass dynamics is described in terms of a section in a very subtle stable vector bundle. The Hall conductance arises as a topological invariant; namely, the slope of the vector bundle previously mentioned. 相似文献
990.
Vector optimization problems are a significant extension of multiobjective optimization, which has a large number of real life applications. In vector optimization the preference order is related to an arbitrary closed and convex cone, rather than the nonnegative orthant. We consider extensions of the projected gradient gradient method to vector optimization, which work directly with vector-valued functions, without using scalar-valued objectives. We provide a direction which adequately substitutes for the projected gradient, and establish results which mirror those available for the scalar-valued case, namely stationarity of the cluster points (if any) without convexity assumptions, and convergence of the full sequence generated by the algorithm to a weakly efficient optimum in the convex case, under mild assumptions. We also prove that our results still hold when the search direction is only approximately computed. 相似文献