Monte Carlo simulations including energy from an entropic force

Several experimental techniques have shown that the primary response of many materials comes from a heterogeneous distribution of independently relaxing nanoscale regions; but most Monte Carlo simulations have homogeneous correlations. Resolving this discrepancy may require including the energy needed to change the configurational entropy, which is often used in theoretical treatments of thermal fluctuations, but not in computer simulations. Here the local configurational entropy is shown to give a nonlinear correction to the Metropolis algorithm that restores conservation of energy, maintains maximum entropy, and yields heterogeneous correlations. The nonlinear correction also improves agreement between Monte Carlo simulations of the Ising model and measurements of specific heat and structural correlations from the Jahn–Teller distortion in LaMnO₃.     

Integrated approaches for reducing sample size for measurements of trace elemental impurities in plutonium by ICP-OES and ICP-MS

A novel microsphere adsorbent based upon carboxymethyl cellulose sodium/prussian blue composite loaded with Lanthanum(III) (CMC/PB-La) was successfully synthesized via electrostatic ejection device for removal of cesium from contaminated water, and characterized by FT-IR, SEM, EDX and XPS. Influencing factors to adsorption cesium were investigated, including solution pH, adsorbent dosage, contact time, initial concentration, temperature and competing ions. Linear Freundlich isotherm was fitted satisfactorily to the adsorption data, and the adsorption kinetic data was fitted well with pseudo-second-order model. Moreover, the results of γ-irradiation experiments indicate that CMC/PB-La has good radiation stability.     

Modified Conditions for Efficient Baeyer-Villiger Oxidation with m-CPBA

The utility of 3-chloroperoxybenzoic acid (m-CPBA) combined with trifluoroacetic acid (TFA) in Baeyer-Villiger oxidations is described. These conditions offer practical advantages over alternative procedures.     

Deprotonation of lithiated benzenes

The deprotonation energies of all possible lithiobenzenes (C(6)Li(n)H(6-n), n = 0-5) were computed at B3LYP/6-311+G(d,p). Based on natural population analysis, the conjugate bases can be thought of as salts between a polyanionic phenyl core and associated lithium cations. The most stable structures maximize the electrostatic attraction between these two species, typically by positioning the lithium cations to bridge in the ring plane across two adjacent carbanion centers. Favorable deprotonation occurs when the formal carbanion centers are adjacent to each other and then the proton is removed from an adjacent carbon. The deprotonation free energies range from 365.0 to 397.2 kcal mol(-1), with most of them less than the deprotonation free energy of benzene (391.8 kcal mol(-1)).