Temperature dependence of ion association constants in nonaqueous solutions of metal perchlorates

The ion association constants in nonaqueous solutions of singly and doubly charged metal perchlorates in organic solvents in a wide range of temperatures have been calculated by integrating the ligand distribution density function. The standard Gibbs energies, entropies, and enthalpies of formation of ion pairs have been calculated. Comparison with experimental data have shown that diluted solutions of doubly charged metal perchlorates are dominated by solvent-separated ion pairs, whereas such pairs coexist with contact ion pairs in solutions of alkali metal perchlorates. It has been demonstrated that the dielectric continuum approximation satisfactorily predicts the temperature dependence of ion association constants.     

离子型共聚单体参与下的全氟丙烯酸酯无皂乳液共聚

离子型共聚单体参与下的全氟丙烯酸酯无皂乳液共聚;全氟烷基丙烯酸酯;无皂乳液;离子型共聚单体     

Cold compression of nuclei induced by antiprotons

On the basis of a dynamical Relativistic Mean Field (RMF) model we study the response of a nucleus on an antiproton implanted in its interior. We solve the Vlasov equation for the p?-nuclear system assuming different strengths of attractive p? potential and show that a compressed state is formed on a rather short time scale of about 4?÷?10 fm/c. The evolution of the system after p? annihilation is simulated using the Giessen Boltzmann-Uehling-Uhlenbeck (GiBUU) transport model. Finally, several observables sensitive to the p? annihilation in a compressed nuclear configuration are proposed, e.g. the nucleon kinetic energy spectra and the total invariant mass distributions of produced mesons.     

A 1.107 μm Yb3+-doped Phosphate Fiber Laser Pumped by a Ti:sapphire

Lasers and amplifiers in a single fiber have been developed rapidly, especially for optical fiber communication and various sensors, in the recent years. However, remarkable progress and achievement have been made mainly in silica fiber doped with rare earth elements. In this paper, we report the progress on the development of the Yb3+-doped phosphate fiber laser.     

Electromagnetic and hadronic interactions of ultrarelativistic nuclei

Beam nuclei accelerated at the Large Hadron Collider (LHC) at CERN are lost due to interactions with the counter-rotating beam, residual gas, and accelerator elements. Proper modelling of the beam transport and radiation load on accelerator components requires reliable prediction of the yields of nuclear fragments produced in electromagnetic dissociation and hadronic fragmentation of beam nuclei. We investigate electromagnetic and hadronic fragmentation of lead nuclei in collisions with various nuclei and single electrons at the injection and collision energies of the LHC. The consideration is based on the RELDIS and abrasion-ablation models. Since this approach well describes Pb fragmentation data at 30 and 158 A GeV, its validity for Pb nuclei at the LHC collision energy is also expected.     

Hydrophobic/hydrophilic solvation: inferences from Monte Carlo simulations and experiments

In this study Monte Carlo simulations are used to determine the solvation properties of model hydrophobic (xenon and hard sphere) and hydrophilic (dimethyl ether) solutes in SPC/E water. Various contributions to the experimental solvation entropy, including the solvent reorganization entropy, have been determined. The main conclusion drawn, which is in accord with solubility data, is that poor solubility correlates with poor solute-water interaction. At room temperature, energy dominates the aqueous solubility of both hydrophobic and hydrophilic solutes, rather than entropy. However, at higher temperatures the solubility can pass through a minimum, and then entropy becomes dominant. Another interesting finding is the presence of larger than expected cavities in water. Two different simulation results support this finding. This unexpected hollow structure in water explains why a hard sphere solute is more soluble in water than in a comparable hard sphere or Lennard-Jones solvent. Hydrogen bonding causes water to aggregate into clusters that produce a few large cavities rather than many smaller cavities. The propensity for clustering also explains why water gives the illusion of being a low density liquid. Sufficient theoretical apparatus is developed to connect theoretical solvation properties to those measured by simulation and experiment. Finally, based on gas solubility, an intuitive hydrophobic/hydrophilic scale is developed.     

Mechanisms of fragment production in heavy-ion reactions at intermediate energies

Comparative analysis of three typical models of nuclear disintegration, the statistical multifragmentation model (SMM), the quantum statistical model (QSM) and a generalized evaporation model (GEM), is carried out. The thermodynamical properties of a decaying system as well as observable characteristics in heavy ion collisions predicted by the different models are discussed. It is shown that these models yield quite similar results for low charge yields at higher excitation energies (E/A>6 MeV per nucleon) and it is suggested that the coincidence measurements of the intermediate mass fragment multiplicity and the neutron and proton multiplicity (or alternatively, the total bound charge) may be very useful for deducing the decay mechanism. The GEM is shown to differ from the other models in predicting a high Z residue peak.     

The excitation function of Au + Au in the framework of the (2+1)-fluid model

We present the excitation function of the reaction Au+Au in the frame work of the recently developed (2+1)-fluid model. In the (2+1)-fluid model, it is assumed that two baryonic fluids formed by the projectile and target nucleons produce a third hadronic fluid via inelastic nucleon-nucleon collisions. For this third fluid we use the equation of state of an interacting hadron gas obtained within the relativistic mean field model, including a first order phase transition. The dependence of the pion mean transverse momentum is investigated to observe the predicted plateau in the region of the phase transition of the hadronic matter to the quark-gluon plasma.