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103.
Vittorio Berbenni Chiara Milanese Giovanna Bruni Alessandro Girella Amedeo Marini 《Journal of Thermal Analysis and Calorimetry》2012,110(2):831-837
Simultaneous TG?CDSC measurements have been used to study the solid state reaction in the system SnC2O4?C4MgCO3·Mg(OH)2·xH2O (Sn:Mg?=?0.5). The results obtained with physically prepared mixture and with mixture mechanically activated by high-energy milling are compared. Synthesis of the compound Mg2SnO4 has been attempted starting from both type of mixture: Mg2SnO4 forms by annealing the activated mixture at temperatures between 850 and 1,000?°C while it can hardly be obtained from physical mixtures even by thermal treatment at temperature as high as 1,300?C1,350?°C. Mg2SnO4 prepared by annealing the activated mixture has been characterized by diffuse reflectance FT-IR spectroscopy, modulated temperature differential scanning calorimetry, scanning electron microscopy, and specific surface area measurements (B.E.T. method). 相似文献
104.
Cathy Knotts Gabriella Carini Gabriel Blaj Philip Hart Sven Herrmann Amedeo Perazzo 《Synchrotron Radiation News》2013,26(2):49-51
Approximately 400 participants learned about the latest scientific capabilities at the Stanford Synchrotron Radiation Lightsource (SSRL) and Linac Coherent Light Source (LCLS) during the 2013 Users' Meeting at the SLAC National Accelerator Laboratory, October 1–4, 2013. The Users' Meeting included more than a dozen workshops as well as scientific awards, poster presentations, and talks on the latest scientific trends, challenges, and opportunities. 相似文献
105.
This paper presents a heuristic algorithm for solving RCPSP/max, the resource constrained project scheduling problem with generalized precedence relations. The algorithm relies, at its core, on a constraint satisfaction problem solving (CSP) search procedure, which generates a consistent set of activity start times by incrementally removing resource conflicts from an otherwise temporally feasible solution. Key to the effectiveness of the CSP search procedure is its heuristic strategy for conflict selection. A conflict sampling method biased toward selection of minimal conflict sets that involve activities with higher-capacity requests is introduced, and coupled with a non-deterministic choice heuristic to guide the base conflict resolution process. This CSP search is then embedded within a larger iterative-sampling search framework to broaden search space coverage and promote solution optimization. The efficacy of the overall heuristic algorithm is demonstrated empirically on a large set of previously studied RCPSP/max benchmark problems. 相似文献
106.
Joannis Apostolakis Andreas Plückthun Amedeo Caflisch 《Journal of computational chemistry》1998,19(1):21-37
A novel procedure for docking ligands in a flexible binding site is presented. It relies on conjugate gradient minimization, during which nonbonded interactions are gradually switched on. Short Monte Carlo minimization runs are performed on the most promising candidates. Solvation is implicitly taken into account in the evaluation of structures with a continuum model. It is shown that the method is very accurate and can model induced fit in the ligand and the binding site. The docking procedure has been successfully applied to three systems. The first two are the binding of progesterone and 5β-androstane-3,17-dione to the antigen binding fragment of a steroid binding antibody. A comparison of the crystal structures of the free and the two complexed forms reveals that any attempt to model binding must take protein rearrangements into account. Furthermore, the two ligands bind in two different orientations, posing an additional challenge. The third test case is the docking of Nα-(2-naphthyl-sulfonyl-glycyl)-D -para-amidino-phenyl-alanyl-piperidine (NAPAP) to human α-thrombin. In contrast to steroids, NAPAP is a very flexible ligand, and no information of its conformation in the binding site is used. All docking calculations are started from X-ray conformations of proteins with the uncomplexed binding site. For all three systems the best minima in terms of free energy have a root mean square deviation from the X-ray structure smaller than 1.5 Å for the ligand atoms. © 1998 John Wiley & Sons, Inc. J Comput Chem 19: 21–37, 1998 相似文献
107.
Russel E. Caflisch 《Communications in Mathematical Physics》1980,74(1):71-95
The initial value problem for the linearized spatially-homogeneous Boltzmann equation has the form ?f/?t+Lf=0 withf(ξ,t=0) given. The linear operatorL operates only on the ξ variable and is non-negative, but, for the soft potentials considered here, its continuous spectrum extends to the origin. Thus one cannot expect exponential decay forf, but in this paper it is shown thatf decays likee ?λ t β with β<1. This result will be used in Part II to show existence of solutions of the initial value problem for the full nonlinear, spatially dependent problem for initial data that is close to equilibrium. 相似文献
108.
Oded Berman Richard C. Larson Amedeo R. Odoni 《European Journal of Operational Research》1981,6(2):104-116
We review four facility location problems which are motivated by urban service applications and which can be thought of as extensions of the classic Q-median problem on networks. In problems P1 and P2 it is assumed that travel times on network links change over time in a probabilistic way. In P2 it is further assumed that the facilities (servers) are movable so that they can be relocated in response to new network travel times. Problems P3 and P4 examine the Q-median problem for the case when the service capacity of the facilities is finite and, consequently, some or all of the facilities can be unavailable part of the time. In P3 the facilities have stationary home locations but in P4 they have movable locations and thus can be relocated to compensate for the unavailability of the busy facilities. We summarize our main results to date on these problems. 相似文献
109.
Rois Benassi Ferdinando Taddei Amedeo Leonardi Dante Nardi 《Magnetic resonance in chemistry : MRC》1981,15(1):25-28
The NMR variable temperature behaviour of N-aroyl- and N-thioaroyl-N′-piperonylpiperazines was investigated. The largest chemical shift separation between the exchanging methylene groups, and the highest energy barrier, is found for the thioamide compounds. Results from semi-empirical calculations are qualitatively in line with the experimental findings, revealing that the higher barrier in the thiocarbonyl compounds compared with the carbonyl compounds is mainly connected with differences in the energies of ground states, rather than in those of transition states, of these molecules. The effect of the nature of the heterocyclic ring containing the amidic nitrogen atom on the barrier height is also discussed. 相似文献
110.
Consider a flat two-dimensional vortex sheet perturbed initially by a small analytic disturbance. By a formal perturbation analysis, Moore derived an approximate differential equation for the evolution of the vortex sheet. We present a simplified derivation of Moore's approximate equation and analyze errors in the approximation. The result is used to prove existence of smooth solutions for long time. If the initial perturbation is of size ? and is analytic in a strip |??m γ| < ρ, existence of a smooth solution of Birkhoff's equation is shown for time t < k2p, if ? is sufficiently small, with κ → 1 as ? → 0. For the particular case of sinusoidal data of wave length π and amplitude e, Moore's analysis and independent numerical results show singularity development at time tc = |log ?| + O(log|log ?|. Our results prove existence for t < κ|log ?|, if ? is sufficiently small, with k κ → 1 as ? → 0. Thus our existence results are nearly optimal. 相似文献