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We present a method for directly locating density-driven phase transitions in multicomponent systems. Phase coexistence conditions are determined through manipulation of a total density probability distribution evaluated over a density range that includes both coexisting phases. Saturation quantities are determined through appropriate averaging of density-dependent mean values of a given property of interest. We discuss how to implement the method in both the grand-canonical and isothermal-isobaric semigrand ensembles. Calculations can be conducted using any of the recently introduced flat-histogram techniques. Here, we combine the general algorithm with a transition-matrix approach to produce an efficient self-adaptive technique for determining multicomponent phase equilibrium properties. To assess the performance of the new method, we generate phase diagrams for a number of binary and ternary Lennard-Jones mixtures. 相似文献
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A computational study of hydration, solution structure, and dynamics in dilute carbohydrate solutions 总被引:1,自引:0,他引:1
We report results from a molecular simulation study of the structure and dynamics of water near single carbohydrate molecules (glucose, trehalose, and sucrose) at 0 and 30 degrees C. The presence of a carbohydrate molecule has a number of significant effects on the microscopic water structure and dynamics. All three carbohydrates disrupt the tetrahedral arrangement of proximal water molecules and restrict their translational and rotational mobility. These destructuring effects and slow dynamics are the result of steric constraints imposed by the carbohydrate molecule and of the ability of a carbohydrate to form stable H bonds with water, respectively. The carbohydrates induce a pronounced decoupling between translational and rotational motions of proximal water molecules. 相似文献
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Charles E. Carraher JR. 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(8):1293-1356
This review emphasizes the breadth of metallic and metallic-like polymers evaluated as to thermal properties. Techniques usefully applied to particular systems are noted with the aim of suggesting their application to other systems. 相似文献
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Multireference configuration interaction (MRCI) and complete active space second-order perturbation theory (CASPT2) calculations are performed on Fe2 and Fe? 2. Although it is not possible to definitively identify the ground states of Fe2 and Fe? 2, the calculations suggest that the ground state of Fe? 2 in 8Σ? u derived from 3d134σ2 g4σ2 u and that the states observed in photodetachment are the 9Σ? g and 7Σ? g states with a 3d134σ2 g4σ1 u occupation, but that the ground state of Fe2 is 7Δu(3d144σ2 g) and is not observed in the photo-detachment spectra. 相似文献
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Nathaniel W. Alcock Adam J. Clarke William Errington Ana Maria Josceanu Peter Moore Simon C. Rawle 《Supramolecular chemistry》2013,25(3-4):281-291
Abstract A series of azamacrocycles which have been N-functionalised with pendent pyridylmethyl-(pyCH2-), bipyridylmethyl-(bipyCH2-) and terpyridylmethyl- (terpyCH2-) arms have been synthesised and characterised, and some of their coordination chemistry with transition metal ions is reported. By attaching the pendent-arms at the 5- rather than the 6-position of the py, bipy and terpy, new ligands are generated which can be used to form polynuclear metal complexes in a controlled and systematic fashion. Fluorescent pH and transition metal ion sensors have been developed by reacting the azamacrocyclic N-pendent bipyCH2 arm(s) with cis-[Ru(bipy)2Cl2], to give macrocycles with up to four attached [Ru(bipy)3]2+ groups. That based on 1,4,7-triazacyclononane (9N3), with three attached [Ru(bipy)3]2+ groups, has a first photo excited state pKa of 7.1, and is a useful fluorescent sensor for physiological pH at below micromolar concentrations. The analogous derivative of cyclam (1,4,8,11-tetraazacyclotetradecane) carrying four [Ru(bipy)3]2+ groups has a first photo excited state pKa of 5.7, allowing kinetic and thermodynamic fluorescence studies of metal ion uptake by an azamacrocycle at neutral pH without complications from protonated species. A pre-organised hexadentate tris(2,2′-bipyridyl) chelating ligand, 1,4,7-tris(2′,2″-bipyridyl-5′-ylmethyl)-1,4,7-triazacyclononane (L) has been developed, and crystal structures of mononuclear complexes [M(LH)]3+ (M = Ru, Cu) are reported. In [M(LH)]3+ the azamacrocyclic N-atoms are non-coordinating to M, but have a very high affinity for a single proton trapped in the macrocyclic cavity. An analogous and potentially nonadentate ligand has been developed based on 9N3 with three N-pendent terpyCH2-arms. 相似文献
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Alves GA Amato S Anjos JC Appel JA Astorga J Bracker SB Cremaldi LM Dagenhart WD Darling CL Dixon RL Errede D Fenker HC Gay C Green DR Jedicke R Karchin PE Kennedy C Kwan S Lueking LH de Mello Neto JR Metheny J Milburn RH de Miranda JM da Motta Filho H Napier A Passmore D Rafatian A dos Reis AC Ross WR Santoro AF Sheaff M Souza MH Spalding WJ Stoughton C Streetman ME Summers DJ Takach SF Wallace A Wu Z 《Physical review letters》1996,77(12):2388-2391
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OPTIMAL FISH HARVESTING FOR A POPULATION MODELED BY A NONLINEAR PARABOLIC PARTIAL DIFFERENTIAL EQUATION 下载免费PDF全文
As the human population continues to grow, there is a need for better management of our natural resources in order for our planet to be able to produce enough to sustain us. One important resource we must consider is marine fish populations. We use the tool of optimal control to investigate harvesting strategies for maximizing yield of a fish population in a heterogeneous, finite domain. We determine whether these solutions include no‐take marine reserves as part of the optimal solution. The fishery stock is modeled using a nonlinear, parabolic partial differential equation with logistic growth, movement by diffusion and advection, and with Robin boundary conditions. The objective for the problem is to find the harvest rate that maximizes the discounted yield. Optimal harvesting strategies are found numerically. 相似文献
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