查看更多>>摘要：Addition of aluminum source was one of the effective methods to prepare single-phase mullite. The effect of different aluminum sources on phase transition kinetics and mechanism of mullite preparation from kaolinite were studied. The results showed that the addition of aluminum sources increased the phase transition activation energy (E) of kaolinite, among which the E of mixed gamma-Al2O3 was increased least. The addition of gamma-Al2O3 & nbsp;effectively reacted with the excess silicon species in kaolinite to form secondary mullite and thus increased the crystallinity of mullite. Therefore, single-phase mullite could be prepared from kaolinite by controlling the additional amount of gamma-Al2O3.
查看更多>>摘要：Water dispersible 3-marcaptoproponic acid protected Mn@ZnSe QDs were applied for sensing hazardous mercury and lead ions, which acts as an acceptor for metal ions due to the strong interaction between the metal ions and thiol group (-SH). The photoluminescence (PL) intensity of Mn@ZnSe QDs was strongly quenched with Hg2+ and Pb2+ (0-100 mu L). The average PL lifetime of Mn@ZnSe was shortened with Hg2+ and Pb2+ concentrations, whereas increased with initial Pb2+ concentrations. A filter paper-based sensor was also prepared and successfully tested for sensing via colorimetric and fluorometric detection methods. The system provided a new possibility for dual response ions detection in real samples.
查看更多>>摘要：To use solar energy effectively, BiOX (Cl, Br, I) nanosheets with reasonable band gap structure were prepared by ultrasonic assisted hydrothermal method. The prepared BiOX (Cl, Br, I) nanosheets removed 90% of CBZ within 5 min, showing rapid degradation kinetic of 0.3858 min(-1). The improved photocatalytic activities can be due to the reduced recombination of photoinduced electron-hole pairs, strong visible-light absorption ability, large surface area and pore. Radicals experiments indicated that the BiOX (Cl, Br, I) generated main holes (h(+)) and minor electrons (e(-)) to degrade CBZ. These results demonstrated the good feasibility of BiOX (Cl, Br, I) nano-sheets in the degradation of CBZ under simulated solar light irradiation.
查看更多>>摘要：Herein we report micellization behavior of anionic surfactant, sodium dodecyl sulfate (SDS) in presence and absence of anionic hydrotrope (1,3-Benzenedisulfonic acid disodium salt (BDS)) in aqueous medium. Critical micelle concentrations (CMC) of mixed surfactant-hydrotrope systems were determined by conductometric technique. CMC values of surfactant-hydrotrope decrease with increasing hydrotrope concentration. Interactions between hydrotrope and surfactant are synergistic in nature. We also deduced thermodynamic parameters of micellization (viz., Delta G degrees(m), Delta H degrees(m), and Delta S degrees(m)). The effect of hydrotrope and temperature on different thermophysical properties have been discussed. Experimental techniques like FT-IR and NMR were employed to reveal the non-covalent interactions of mixed surfactant-hydrotrope systems.
查看更多>>摘要：In this work, we present the efficient combination of Smolyak representations with time independent quantu m mechanical approach using absorbing bounda r y conditions for the cumulative reaction probability calculations of a multidimensional reactive scattering problem. Ou r approach uses both kinds of Smolyak representations (finite basis and grid) which drastically reduces the size of the basis representation for the cumulative reaction operator. The cumulative reaction probability is thus obtained by solvin g the eigenvalue problem within the context of reaction path Hamiltonian using the compact Smolyak basis combined with an iterative Lanczos al-gorithm. Benchmark calculations are presented for reactive scattering models with a linear reaction coordinate and applied to a 25D model highlighting the efficiency of the present approach for multidimensional reactive processes.
查看更多>>摘要：We examined the charge-ordered phase transition in (TMTTF)(2)MF6 systems by exact diagonalization of an extended Hubbard model Hamiltonian whose parameters were referred from quantum chemical calculations with periodic boundary conditions along with inversion symmetry breaking in the crystal. We showed that a nearest-neighbor Coulomb interactions for the charge-ordered phase transition should be twice as much as those previously obtained by fitting for conductivities with a minute inversion symmetry breaking of the crystal (similar to 0.01 angstrom) which was confirmed by a recent experimental study.
查看更多>>摘要：The recent discovery of cyclo[18]carbon has attracted widespread attention. Density functional theory (DFT) study was carried out to evaluate the viability of the encapsulation of magnesium dimer inside the all-carboatomic ring, that is, Mg-2@C-18. Results indicated that Mg-2@C-18 possesses a perfect endohedral structure. Charge transfer resulted in forming typical [Mg-2](2+)[C-18](2-) ionic complexes. The high stability of the complex could be due to the strong electrostatic interaction between the guest Mg-2 and the host C(18 )ring. The structure and bonding properties of the C-18 ring of the system is different from those of pristine cyclo[18]carbon. Mg-2@C-18 shows remarkable aromatic character.
查看更多>>摘要：A first principles calculation in this work is performed on two polymorphic forms of uranium pentafluoride (UF5) by using density functional theory (DFT) merging with dynamical mean-field theory (DMFT) scheme with spin-orbit coupling (SOC) and on-site Coulomb repulsion for correlation effect due to the incompletely filled U 5f orbitals. Calculation results suggest that U-j = 5/2 and j = 7/2 manifolds both are in weakly correlated states in alpha and beta phases UF5 and, Russel-Saunders (LS) coupling scheme is appropriate for U 5f electrons. Occupation probability analysis demonstrates that U ions are mostly composed of mixed atomic configurations 5f1, 5f(2) and 5f(3) with average occupation numbers of n(f) ~ 2.002 and 1.862 for U-5f electrons in alpha and beta phases UF5, respectively, mainly due to the complicated quantum mechanics processes including the dual nature of localized and itinerant U 5f electrons, as well as the flexible outer electronic configuration of U ions. Finally, we estimate the momentum-resolved electronic spectrum function (the so-called quasiparticle band structure) to compare with angle-resolved photoemission spectrum (ARPES).
查看更多>>摘要：Metal-CO interplay has been repeatedly emphasized to modify the structure or reactivity of a chemical species. A fundamental understanding on the nature of strongly bonded CO on noble metal catalysts is vital to prevent the catalysts from poisoning and then guide the advanced design. Herein, we identified the CO self-promoted oxidation by gas-phase cluster anions IrVO4-. Mass spectrometry experiment showed that the IrVO4- cluster can only anchor CO while product IrVO4CO- can oxidize CO and generate IrVO3CO-. The molecular-level origin of this positive effect of strongly bonded CO on noble metal has been rationalized by quantum-chemical calculations.
Morales-Meza, SharitySanchez-Castro, Maria E.Ibarra-Rodriguez, MarisolSanchez, Mario...
6页
查看更多>>摘要：Pentalene and alkali elements were studied in order to understand the nature of the M-H-2 bond. Our results showed that the highest adsorption energy values are for Li-2[C8H6)H-12 , Na-2[C8H6)H-24 and K-2[C8H6)H-32 with-2.44,-2.15 and-2.06 kcal/mol, respectively. The Cs-2[C8H6] complex adsorbs up to 20 hydrogen molecules, while the Li-2[C8H6] complex is only capable of capturing 6 molecules. Also, the Gibbs free energies for all complexes with maximum number of hydrogens were analyzed in order to know the effect of temperature on the adsorption process. All studies were performed with the PBE0-D3BJ/def2-TZVP and DLPNO-CCSD(T) methods.
NSTL
Elsevier