Dynamical Study of a Constant Viscous Dark Energy Model in Classical and Loop Quantum Cosmology

Dynamical behaviors and stability properties of a flat space Friedmann-Robertson-Walker universe filled with pressureless dark matter and viscous dark energy are studied in the context of standard classical and loop quantum cosmology. Assuming that the dark energy has a constant bulk viscosity, it is found that the bulk viscosity effects influence only the quintessence model case leading to the existence of a viscous late time attractor solution of de- Sitter type, whereas the quantum geometry effects influence the phantom model case where the big rip singularity is removed. Moreover, our results of the Hubble parameter as a function of the redshift are in good agreement with the more recent data.

THE LINEAR CORRELATIONS BETWEEN ELECTRONIC TRANSITION ENERGY AND HAMMETT CONSTANTS FOR THE SUBSTITUTED PORPHYRIN-LIKE MACROCYCLE

The properties of absorption spectra are presented and the linear correlations of Hammett constants with the 0-0 transition energy(E_(o,o))of S_←S_o, and the ratios of oscillator strength(f/f)are used to probe the interactions betwee π-electron of aromatic maerocycles or metal ion of complexes with the sub- stituents on β-position of benzene ring for porphyrin-like maerocyclic compounds.

Interaction of Gravitational field and Brans-Dicke field in R/W universe containing Dark Energy like fluid

On studying some new models of Robertson-Walker universes with a Brans-Dicke scalar field, it is found that most of these universes contain a dark energy like fluid which confirms the present scenario of the expansion of the universe. In one of the cases, the exact solution of the field equations gives a universe with a false vacuum, while in another it reduces to that of dust distribution in the Brans-Dicke cosmology when the cosmological constant is not in the picture. In one particular model it is found that the universe may undergo a Big Rip in the future, and thus it will be very interesting to investigate such models further.

Na Induced Changes in the Electronic Band Structure of Graphene Grown on C-Face SiC

Studies of the effects induced on the electron band structure after Na deposition, and subsequent heating, on a C-face 2 MLs graphene sample are reported. Na deposition shifts the Dirac point downwards from the Fermi level by about 0.5 eV due to electron doping. After heating at temperatures from around 120℃ to 300℃,thep-band appears considerably broadened. Collected Si 2p and Na 2p spectra then indicate Na intercalation in between the graphene layers and at the graphene SiC interface. The broadening is therefore interpreted to arise from the presence of two slightly shifted, but not clearly resolved,p-bands. Constant energy photoelectron distribution patterns, E(kx,ky);s, extracted from the clean 2MLs graphene C-face sample look very similar to earlier calculated distribution patterns for monolayer, but not Bernal stacked bilayer, graphene. After Na deposition the patterns extracted at energies below the Dirac point appear very similar so the doping had no pronounced effect on the shape or intensity distribution. At energies above the Dirac point the extracted angular distribution patterns show the flipped, “mirrored”, intensity distribution predicted for monolayer graphene at these energies. An additional weaker outer band is also discernable at energies above the Dirac point, which presumably is induced by the deposited Na.

FLRW non-singular cosmological model in general relativity

A singularity free cosmological model is obtained in a homogeneous and isotropic background with a specific form of the Hubble parameter in the presence of an interacting dark energy represented by a time-varying cosmological constant in general relativity. Different cases that arose have been extensively studied for different values of the curvature parameter. Some interesting results have been found with this form of the Hubble parameter to meet the possible negative value of the decelera- tion parameter （- 1/3≤ q 〈 0） as the current observations reveal. For some particular values of these parameters, the model reduces to Berman＇s model.

Determination of energy transfer and upconversion constants for Yb^(3+)/Er^(3+) codoped phosphate glass

The energy transfer and cooperation upconversion processes are investigated in Yb3＋/Er3＋ codoped phos- phate glass. Based on the measured curves of output power versus incident power, the laser and spectroscopic parameters of the glass are fitted and analyzed. We focus on the resonant energy transfer constant k from Yb3＋ to Er3＋ as well as the cooperation upconversion coefficient Cup from 4113/2 of Era＋. The fitted k and Cup can give almost the same results for different thicknesses of glass disk with the same dop- ing concentrations. The determination of these parameters is helpful for the development of Yb3＋/Er3＋ codoped laser glass.

MRCI+Q study of the low-lying electronic states of CdF including spin-orbit coupling

Cd F molecule, which plays an important role in a great variety of research fields, has long been subject to numerous researchers. Due to the unstable nature and heavy atom Cd containing in the Cd F molecule, electronic states of the molecule have not been well studied. In this paper, high accurate ab initio calculations on the Cd F molecule have been performed at the multi-reference configuration interaction level including Davidson correction（MRCI ＋ Q）. Adiabatic potential energy curves（PECs） of the 14 low-lying Λ–S states correlating with the two lowest dissociation limits Cd（~1S_g） ＋ F（~2P_u） and Cd（~3P_u） ＋ F（~2P_u） have been constructed. For the bound Λ–S and ？ states, the dominant electronic configurations and spectroscopic constants are obtained,and the calculated spectroscopic constants of bound states are consistent with previous experimental results. The dipole moments（DMs） of 2 Σ＋ and 2Π are determined, and the spin–orbit（SO） matrix elements between each pair of X2Σ＋, 22Σ＋, 12Π, and 22Π are obtained. The results indicate that the sudden changes of DMs and SO matrix elements arise from the variation of the electronic configurations around the avoided crossing region. Moreover,the Franck–Condon factors（FCFs）, the transition dipole moments（TDMs）, and radiative lifetimes of low-lying states-the ground state X2Σ＋are determined. Finally, the transitional properties of 22Π–X2Σ＋and 22Σ＋–X2Σ＋are studied. Based on our computed spectroscopic information of Cd F, the feasibility and challenge for laser cooling of Cd F molecule are discussed.

Linear free energy relationships between reaction rate constants and equilibrium constants of complex compounds——III. Kinetics and mechanisms of ternary complex formation between (5-X-1, 10-phenanthroline)copper(II) and threonine

The kinetics of ternary complex formation involving Cu(5-X-1, 10-phen) and threonine (CuAL, A=5-X-1, 10-phen; L=threonine or represented by O-N; X=NO_2, Cl, H, CH_3) has been studied by temperature-jump and stopped-flow methods. The formation rate constants, k_f(M^(-1).s^(-1)), for the complexation reaction, CuA + LCuAL, are as follows; X=NO_2, 8.68×10~8; X=Cl, 7.13×10~8; X=H, 6.12×10~8; X=CH_3, 5.42×10~8. The rate constants for zwitterion attack are nil within experimental error. It has been found that a linear free energy relationship exists between the stability(logK_(CuAL)^(CuA) of the complexes CuAL and log kf as follows: IogK_(CuAL)^(CuA)=0.13 + 0.83 logk_f, r=0.99. It suggested that the formation rate governed the stability of the ternary complexes. The rates of formation of the ternary complexes increased with decreasing electron-donating property of the substituents. A linear relationship was found to exist as expressed by the following equation: log(k_f^R/k_F^O) = 0.097σ, r=0.96. A mechanism involves a rapid equilibrium between CuA and L followed by a slow ring closure of L.

Dielectric phenomena and electrical energy storage of poly(vinylidene fluoride) based high-k polymers

Polymeric dielectrics have wide range of applications in the field of electrical energy storage because of their light weight and easy processing. However, the state-of-the-art polymer dielectrics, such as biaxially orientated polypropylene, could not meet the demand of minimization of electronic devices because of its low energy density. Recently, poly（vinylidene fluoride） （PVDF） based ferroelectric polymers have attracted considerable interests for energy storage applications because of their high permittivity and high breakdown strength. Unfortunately, the high dielectric loss and/or high remnant polarization of PVDF-based polymers seriously limits their practical applications for electrical energy storage. Since the discovery of relaxor ferroelectric behavior was firstly reported in irradiated poly（vinylidene fluoride- trifluoroethylene） （P（VDF-TrFE）） copolyrner, many strategies have been developed to enhanced the electrical energy storage capability, including copolymerization, grafting, blending and fabricating of multilayer How these methods affect the polymorphs, crystallinity, crystal size of PVDF-based polymers and the connection between these microstructures and their corresponding energy storage properties are discussed in detail.