聚丙烯酰胺对石油磺酸盐／正丁醇混合胶束体系流变性的影响

研究了一定矿化度下，不同分子量、不同水解度的聚丙烯酰胺对石油磺酸盐／正丁醇混合胶事体系的流型、粘度等充变性质的影响。     

Heat capacities of concentrated multicomponent aqueous electrolyte solutions at various temperatures

The specific heat capacities of the aqueous multicomponent system NaCl +KCl+MgCl₂+CaCl₂ with ionic strength between 8.3 and 9.6 (resembling Dead Sea waters) were measured between 15°C and 45°C. The obtained data were fitted to an empirical equation as a function of concentration and temperature. The thermodynamic functions of the studied multicomponent system were found to be strongly influenced by changes in MgCl₂ concentrations. The application of Young's rule to such concentrated systems was checked at 25°C. The calculated (by Young's rule) specific heat capacitiesC _p and apparent molar heat capacities C_p, of these multicomponent electrolyte solutions were in reasonable agreement with the measured values (–0.008 J-g^–1-K^–1 and –2.6 J-mol^–1-K^–1, respectively).     

Synthesis and characterization of dinuclear ruthenium complexes covalently linked to Ru(II) tris-bipyridine: an approach to mimics of the donor side of photosystem II

To mimic the electron-donor side of photosystem II (PSII), three trinuclear ruthenium complexes (2, 2a, 2b) were synthesized. In these complexes, a mixed-valent dinuclear Ru2(II,III) moiety with one phenoxy and two acetato bridges is covalently linked to a Ru(II) tris-bipyridine photosensitizer. The properties and photoinduced electron/energy transfer of these complexes were studied. The results show that the Ru2(II,III) moieties in the complexes readily undergo reversible one-electron reduction and one-electron oxidation to give the Ru2(II,III) and Ru2(III,III) states, respectively. This could allow for photooxidation of the sensitizer part with an external acceptor and subsequent electron transfer from the dinuclear ruthenium moiety to regenerate the sensitizer. However, all trinuclear ruthenium complexes have a very short excited-state lifetime, in the range of a few nanoseconds to less than 100 ps. Studies by femtosecond time-resolved techniques suggest that a mixture of intramolecular energy and electron transfer between the dinuclear ruthenium moiety and the excited [Ru(bpy)3]2+ photosensitizer is responsible for the short lifetimes. This problem is overcome by anchoring the complexes with ester- or carboxyl-substituted bipyridine ligands (2a, 2b) to nanocrystalline TiO2, and the desired electron transfer from the excited state of the [Ru(bpy)3]2+ moiety to the conduction band of TiO2 followed by intramolecular electron transfer from the dinuclear Ru2(II,III) moiety to photogenerated Ru(III) was observed. The resulting long-lived Ru2(III,III) state decays on the millisecond timescale.     

Enthalpies of transfer of 2-methyl-2-propanol from water to mixtures of water with methanol,ethanol and 1,4-dioxane

The enthalpies of transfer of 2-methyl-2-propanol (TBA) from water to mixtures of water with methanol, ethanol and 1,4-dioxane have been measured. The data are considered in terms of recently developed theory, and it is found that the enthalpies of transfer can be reproduced quantitatively over most of the composition range in each solvent system. The parameters recovered from the analyses indicate that the net effect of TBA on the solvent structure is a breaking of solvent-solvent bonds and that TBA is preferentially hydrated in the aqueous alcohol systems, but randomly solvated in the water+1,4-dioxane system. It is also found that the model parameters for TBA solvation in the alcohol systems are independent of the alcohol.     

U(IV)/LN(III) unexpected mixed site in polymetallic oxalato complexes. Part II. Substitution of U(IV) for Ln(III) in the new oxalates (N2H5)Ln(C2O4)2·nH2O (Ln=Nd, Gd)

Two new hydrazinium lanthanide(III) oxalates, (N₂H₅)[Nd(C₂O₄)₂(H₂O)]·4H₂O (1) and (N₂H₅)[Gd(C₂O₄)₂(H₂O)]·4.5H₂O (2) have been prepared and their crystal structures determined by single-crystal X-ray diffraction. The crystal structures were solved by the direct methods and Fourier difference techniques, and refined by a least-squares method on the basis of F² for all unique reflections. Crystallographic data: 1, triclinic, space group , , b=9.762(4), , α=62.378(5), β=76.681(5), γ=73.858(5), Z=2, R₁=0.0335 for 172 parameters with 3430 reflections with I?2σ(I); 2, triclinic, space group , , b=9.51(3), , α=62.11(4), β=76.15(5), γ=73.73(5), Z=2, R₁=0.0325 for 172 parameters with 1742 reflections with I?2σ(I). The two isotypic structures are built from a three-dimensional (3D) arrangement of lanthanide and oxalate ions. The lanthanide atom is coordinated by eight oxygen atoms from four tetradentate oxalate ions and one aqua oxygen. Alternating lanthanide and oxalate ions form six-membered rings that delimit tunnels running down three directions and occupied by hydrazinium and water molecules. Starting from these lanthanide(III) compounds two isotypic mixed Ln(III)/U(IV) oxalates, (N₂H₅)_0.75[Nd_0.75U_0.25(C₂O₄)₂(H₂O)]·4.5H₂O (3) and (N₂H₅)_0.75[Gd_0.75U_0.25(C₂O₄)₂(H₂O)]·4H₂O (4), are obtained by partial substitution of Ln(III) by U(IV) in the nine-coordinated site, the charge excess being compensated by removal of monovalent ions from the tunnels. Finally, using Na⁺ gel, two mixed Ln(III)/U(IV) sodium oxalates, Na_0.5[Nd_0.5U_0.5(C₂O₄)₂(H₂O)]·3H₂O (5) and Na_0.65[Gd_0.65U_0.35(C₂O₄)₂(H₂O)]·4.5H₂O (6) have been obtained without any change in the 3D framework.     

Effects of Nonionic and Mixed Cationic-Nonionic Micelles on the Rate of Alkaline Hydrolysis of 4-Nitrophthalimide

Pseudo-first-order rate constants (k_obs) for alkaline hydrolysis of 4-nitrophthalimide show a monotonic decrease with increase in [C₁₂E₂₃]_T (total concentration of Brij 35) at constant [CH₃CN] and [NaOH]. This micellar effect is explained in terms of a pseudophase micelle model. The rate of hydrolysis becomes too slow to monitor at [C₁₂E₂₃]_T≥0.03 M in the absence of cetyltrimethylammonium bromide (CTABr) and at [C₁₂E₂₃]_T≥0.04 M in the presence of 0.006–0.02 M CTABr at 0.01 M NaOH. The plots of k_obs versus [C₁₂E₂₃]_T show minima at 0.006 and 0.01 M CTABr, while such a minimum is not visible at 0.02 M CTABr.     

Antimicrobial and anticancer activities of Schiff base ligand and its transition metal mixed ligand complexes with heterocyclic base

A new Schiff base ligand (HL) was prepared via a condensation reaction of quinoline‐2‐carboxaldhyde with 2‐aminophenol in a molar ratio of 1:1. Its transition metal mixed ligand complexes with 1,10‐phenanthroline (1,10‐phen) as co‐ligand were also synthesized in a 1:1:1 ratio. HL and its mixed ligand complexes were characterized using elemental analysis, infrared, ¹H NMR, mass and UV–visible spectroscopies, molar conductance, magnetic measurements, solid reflectance, thermal analysis, electron spin resonance and X‐ray diffraction. Molar conductance measurements showed that all complexes have an electrolytic nature, except Cd(II) complex. From elemental and spectral data, the formulae [M(L)(1,10‐phen)(H₂O)]Cl_x?nH₂O (where M = Cr(III) (x = n = 2), Mn(II) and Ni(II) (x = 1, n = 2), Fe(III) (x = n = 2), Co(II), Cu(II) and Zn(II) (x = 1, n = 2)) and [Cd(L)(1,10‐phen)Cl]?3H₂O for the metal complexes have been proposed. The geometric structures of complexes were found to be octahedral. Powder X‐ray diffraction reflected the crystalline nature of the complexes; however, the Schiff base is amorphous. HL and its mixed ligand complexes were screened against Gram‐positive bacteria (Streptococcus pneumoniae and Bacillus subtilis) and Gram‐negative bacteria (Pseudomonas aeruginosa and Escherichia coli). Antifungal activity was determined against Aspergillus fumigatus and Candida albicans, the data showing that most complexes had activity less than that of the Schiff base while Mn(II), Fe(III) and Ni(II) complexes showed no significant antifungal activity. The anticancer activity of HL and its metal complexes was also studied against breast and colon cell lines. The metal complexes showed IC₅₀ higher than that of HL, especially the Cu(II) complex which showed the highest IC₅₀ against breast cell line.     

Efficient stochastic FEM for flow in heterogeneous porous media. Part 1: random Gaussian conductivity coefficients

This paper is concerned with the development of efficient iterative methods for solving the linear system of equations arising from stochastic FEMs for single‐phase fluid flow in porous media. It is assumed that the conductivity coefficient varies randomly in space according to some given correlation function and is approximated using a truncated Karhunen–Loève expansion. Distinct discretizations of the deterministic and stochastic spaces are required for implementations of the stochastic FEM. In this paper, the deterministic space is discretized using classical finite elements and the stochastic space using a polynomial chaos expansion. The highly structured linear systems which result from this discretization mean that Krylov subspace iterative solvers are extremely effective. The performance of a range of preconditioned iterative methods is investigated and evaluated in terms of robustness with respect to mesh size and variability of the conductivity coefficient. An efficient symmetric block Gauss–Seidel preconditioner is proposed for problems in which the conductivity coefficient has a large standard deviation.The companion paper, herein, referred to as Part 2, considers the situation in which Gaussian random fields are transformed into lognormal ones by projecting the truncated Karhunen–Loève expansion onto a polynomial chaos basis. This results in a stochastic nonlinear problem because the random fields are represented using polynomial chaos containing terms that are generally nonlinear in the random variables. Copyright © 2013 John Wiley & Sons, Ltd.     

Preparation of safe water–lipid mixed electrolytes for application in ion capacitor

Aqueous electrolytes are safe, economic, and environmentally friendly. However, they have a narrow potential window. On the other hand, organic electrolytes exhibit good thermodynamic stability but are inflammable and moisture sensitive. In this study, we prepared water–PEG–lipid ternary electrolytes(TEs). To combine the advantages of water, polyethylene glycol(PEG) and propylene carbonate(PC). The nonflammable mixed electrolytes exhibited a wide potential window of about 2.8 V due to the beneficial effects of PEG and PC. Using these TEs, a lithium manganate–active carbon ion capacitor could be operated at 2.4 V with an energy density of 32 Wh/kg, based on the total active electrode material(current density of 3.3 m A/cm~2). This value was significantly higher than that achieved using an aqueous electrolyte, thereby rationalizing the higher energy density.     

混合质点系的一类几何恒等式及其应用

首先给出了混合质点系的概念,然后又给出了关于混合质点系的一类几何恒等式,并且给出了一个有趣的应用.