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911.
Giustiniano Tiberio Dr. Luca Muccioli Dr. Roberto Berardi Dr. Claudio Zannoni Prof. 《Chemphyschem》2009,10(1):125-136
We study the important n‐cyanobiphenyl (with n= 4–8) series of mesogens, using modelling and molecular dynamics simulations. We are able to obtain spontaneously ordered nematics upon cooling isotropic samples of 250 molecules. By using the united‐atom force field developed herein, we show that the experimental isotropic–nematic transition temperatures are reproduced within 4 K, allowing a molecular‐level interpretation of the odd–even effect along the series. Other properties, like densities, orientational order parameters and NMR residual dipolar couplings are also reproduced well, demonstrating the feasibility of predictive in silico modelling of nematics from the molecular structure. 相似文献
912.
Luca Granieri 《Indagationes Mathematicae》2009,20(4):527-536
The Monge-Kantorovich problem is equivalent to the problem of finding 1-currents with fixed boundary and minimal mass. We address the question of the stability for the mass minimizing currents. In particular, we state a Γ-convergence result. We provide proofs relying just on basic properties of currents and on the notion of flat norm. 相似文献
913.
Luca Fanelli 《Journal of Mathematical Analysis and Applications》2009,357(1):1-420
We prove some uniform in ? a priori estimates for solutions of the equation
914.
O'Mullane AP Neufeld AK Harris AR Bond AM 《Langmuir : the ACS journal of surfaces and colloids》2006,22(25):10499-10505
The electrochemical reduction of TCNQ to TCNQ*- in acetonitrile in the presence of [Cu(MeCN)4]+ has been undertaken at boron-doped diamond (BDD) and indium tin oxide (ITO) electrodes. The nucleation and growth process at BDD is similar to that reported previously at metal electrodes. At an ITO electrode, the electrocrystallization of more strongly adhered, larger, branched, needle-shaped phase I CuTCNQ crystals is detected under potential step conditions and also when the potential is cycled over the potential range of 0.7 to -0.1 V versus Ag/AgCl (3 M KCl). Video imaging can be used at optically transparent ITO electrodes to monitor the growth stage of the very large branched crystals formed during the course of electrochemical experiments. Both in situ video imaging and ex situ X-ray diffraction and scanning electron microscopy (SEM) data are consistent with the nucleation of CuTCNQ taking place at a discrete number of preferred sites on the ITO surface. At BDD electrodes, ex situ optical images show that the preferential growth of CuTCNQ occurs at the more highly conducting boron-rich areas of the electrode, within which there are preferred sites for CuTCNQ formation. 相似文献
915.
Spani Molella L Rinkleff RH Danzmann K 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2006,63(5):987-993
The optical properties of a caesium atomic beam driven on a resonant hyperfine transition in the D(2) line were studied as a function of the probe laser frequency. Using a third off-resonant laser system, a heterodyne interferometer allowed simultaneous absorption and phase shift measurements of either the probe or the coupling laser. The signal features of the probe and coupling laser transmitted intensities showed strong differences in the vicinity of the hyperfine transitions excited by the probe laser. Regular absorption signals and electromagnetically induced transparency were found in either transmitted intensities. Furthermore, light induced birefringence of the probe laser was measured. 相似文献
916.
The tetrabutylammonium salt of 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin (TPPS) is soluble in dichloromethane, and the general properties of this compound have been investigated as function of various added acids HX (X = Cl, Br, I, CF(3)COO, CF(3)SO(3), TFPB) through UV-vis absorption spectroscopy, steady state fluorescence emission, and resonance light-scattering (RLS) techniques. Upon addition of HX, the initial monomeric free base TPPS is readily converted in an aggregated species, whose spectroscopic features are independent of the nature of the counteranion X. All the spectroscopic evidence suggest a J-type arrangement of chromophores in this aggregate, involving strong hydrogen bonds, electrostatic, and dispersive interactions. In the specific case of chloride and bromide, in the presence of a TBAX excess, the addition of the corresponding acid leads to a monomeric ion-pair between the TBA cations and the diacid TPPS, whose central core is strongly interacting with the halide. On further increasing the acid concentration in these latter solutions, fully protonated species are formed that eventually start to aggregate. 相似文献
917.
918.
We study the self-adjoint and dissipative realization A of a second order elliptic differential operator
with unbounded regular coefficients in
, where μ(dx) = ρ (x)dx is the associated invariant measure. We prove a maximal regularity result under suitable assumptions, that generalize the
well known conditions in the case of constant diffusion part.
Dedicated to Giuseppe Da Prato on the occasion of his 70th birthday 相似文献
919.
Javier Cilleruelo Florian Luca Adolfo Quirós Igor E. Shparlinski 《Monatshefte für Mathematik》2010,159(3):215-223
Let ${f(X) \in \mathbb {Z}[X]}$ be an irreducible polynomial of degree D ≥ 2 and let N be a sufficiently large positive integer. We estimate the number of positive integers n ≤ N such that the product $$F(n) = \prod\limits_{k =1}^n f(k)$$ is a perfect square. We also consider more general questions and give a lower bound on the number of distinct quadratic fields of the form ${\mathbb {Q}(\sqrt{F(n)})}$ , n = M + 1, ... , M + N. 相似文献
920.
Potential Analysis - We prove existence of invariant measures for the Markovian semigroup generated by the solution to a parabolic semilinear stochastic PDE whose nonlinear drift term satisfies... 相似文献