C12-s-C12•2Br和C12En混合水溶液的胶团化行为

季铵盐二聚表面活性剂C12 s C12•2Br（s=2、3、4、6）和非离子表面活性剂C12E10或C12E23在水溶液中生成混合胶团.其临界胶团总浓度cmcT值介于二元复配体系中各组分的临界胶团浓度和之间.当添加少量非离子型表面活性剂（在水溶液中的摩尔分数α2=0.1）时,混合胶团中C12E10或C12E23的摩尔分数均已超过0.35;随着溶液中非离子型表面活性剂含量的增大,混合胶团中逐渐以C12E10或C12E23成分为主.     

Neue Alkalioxoarsenate(V): NaLi2[AsO4] — ein neuer Formeltyp [1]

New Alkali Oxoarsenates(V): NaLi₂[AsO₄] — A New Type of Formula [1] . By heating of well ground mixtures of the binary oxides As₂O₃, Na₂O, and Li₂O₂, molar ratio As:Na:Li = 1.0:1.0:2.0, in a well closed Ni tube (650°C, 21 d) colourless single crystals of NaLi₂[AsO₄] were obtained for the first time. The new orthoarsenate(V) crystallizes orthorhombic (space group P mn2₁-C, No. 31) with Z = 2. The structure determination showed that it is isostructural to β_II-Li₃[VO₄] and that means the Li₃[PO₄]-type. The lattice constants a = 702.9(2) pm, b = 520.5(1) pm, c = 505.4(2) pm were taken from Guinier-Simon powder data. The structure was determined by four-circle diffractometer data [Philips PW 1 100, AgKα , 679 independent out of 2 373 I_o(hkl), R = 3.03%, R_w = 2.29%; parameter see text]. The Madelung Part of Lattice Energy, MAPLE, and Effective Coordination Numbers, ECoN, these calculated via Mean Fictive Ionic Radii, MEFIR, are calculated and discussed.     

Mixed chelates of some trivalent lanthanide ions containing (trans-1,2-cyclhexylenedinitrilo)tetraacetate and norleucinate

Summary Formation constants of mixed chelates with (trans-1,2-cyclohexylenedinitrilo)tetra-acetate (DCTA) as primary ligand and norleucinate (nle) as secondary ligand with metal ions La(III), Ce(III), Pr(III), Sm(III), Gd(III), Tb(III), Dy(III), Er(III), and Yb(III) have been determined by the modified potentiometricpH titration method of Irving-Rossotti in aqueous medium at (295±1) K and fixed ionic strength of =0.1M (NaClO₄). Formation constants of binary complexes of the metal ions with the secondary ligand have also been determined under identical conditions. The mixed chelates were found to be more stable than the binary ones. The order of stabilities in terms of metal ions is La(III)Gd(III)

Gemischte Chelate einiger dreiwertiger Lanthanidenionen mit (trans-1,2-Cyclohexylendinitril)tetraacetat und Norleucinat

Zusammenfassung Es wurden die Komplexbildungskonstanten gemischter Chelate mit (trans-1,2-Cyclohexylendinitril)tetraacetat als Primärkomponente und Norleucinat als Sekundärkomponente mit den Metallionen La(III), Ce(III), Pr(III), Sm(III), Gd(III), Tb(III), Dy(III), Er(III) und Yb(III) mittels einer modifizierten potentiometrischen Titrationsmethode nach Irving-Rossotti in wäßrigem Medium bei (295±1) K und einer konstanten Ionenstärke von =0.1M (NaClO₄) bestimmt. Die Bildungskonstanten der binären Komplexe der Metallionen mit dem Sekundärliganden wurden ebenfalls unter identen Bedingungen bestimmt. Es wurde festgestellt, daß die gemischten Chelate stabiler sind als die binären. Die Stabilitätsreihenfolge bezüglich der Metallionen ist La(III)Gd(III)     

Oxygen transport in La<Subscript>0.6</Subscript>Sr<Subscript>0.4</Subscript>Co<Subscript>1−<Emphasis Type="Italic">y</Emphasis></Subscript>Fe<Subscript><Emphasis Type="Italic">y</Emphasis></Subscript>O<Subscript>3−δ</Subscript>

The surface exchange coefficient and chemical diffusion coefficient of oxygen for the perovskites La_0.6Sr_0.4Co_1–yFe_yO_3– (y=0.2, 0.5 and 0.8) were measured using the conductivity relaxation technique. Measurements were performed between 600 and 800 °C in an oxygen partial pressure range between 10^–4 and 1 bar. Both transport coefficients decrease markedly with decreasing oxygen partial pressure below about 10^–2 bar at all temperatures. This is attributed to ordering of oxygen vacancies. Implications for using La_0.6Sr_0.4Co_1–yFe_yO_3– as an oxygen separation membrane are discussed.Presented at the OSSEP Workshop Ionic and Mixed Conductors: Methods and Processes, Aveiro, Portugal, 10-12 April 2003     

Synthesis,structure and properties of aquabis(2,4′-bipyridine)di(propionato-O)copper(II)

The title complex has been synthesized and characterized by elemental and thermal analysis, IR and electronic spectroscopy, conductivity studies and X-ray crystallography. In the crystal, the complex has two-fold symmetry and the copper atom adopts square pyramidal coordination. Bond valences for Cu were computed. Cu–O_(propionate) bonds are slightly stronger than the Cu–N bonds, and the Cu–O_(water) bond is distinctly weaker. Molecules are linked by O–H···O hydrogen bonds to form infinite hydrogen-bonded chains along the y axis.     

Recognition of polymer-particle interfacial morphology in mixed matrix membranes through ideal permeation predictive models

Interfacial properties play an important role in determining characteristics and performance of composite materials, especially in membrane gas separation applications. Formation of any undesirable defect at polymer-particle interface can directly influence on membrane permeability and selectivity in addition to unwanted effects on the other mechanical/physical properties. For achieving a quick insight about the role and nature of interfacial morphologies in mixed matrix membranes (MMMs) and their effects on gas transport properties, a new technique mainly in terms of mathematical modeling was developed. Based on the proposed approach, although ideal models often failed in predicting MMMs performance, these models can provide guidelines for discernment of the types of formed interfacial morphology, like current methods in characterization.     

A Mixed Mann Iteration Process for Fixed Points of Mixed Increasing Operators in Ordered Banach Spaces

In this paper, we develop a new mixed Mann iteration process to approximate the fixed points of mixed increasing operators in ordered Banach spaces and discuss the convergence analysis of the iterative sequences generated by the iteration process. As an application, we develop a new iterative method for solving a class of nonlinear integral equations.     

A note on a priori error estimates for augmented mixed methods

In this note we describe a strategy that improves the a priori error bounds for augmented mixed methods under appropriate hypotheses. This means that we can derive a priori error estimates for each one of the involved unknowns. Usually, the standard a priori error estimate is for the total error. Finally, a numerical example is included, that illustrates the theoretical results proven in this paper.     

Maximum likelihood estimation for second level fMRI data analysis with expectation trust region algorithm

The trust region method which originated from the Levenberg–Marquardt (LM) algorithm for mixed effect model estimation are considered in the context of second level functional magnetic resonance imaging (fMRI) data analysis. We first present the mathematical and optimization details of the method for the mixed effect model analysis, then we compare the proposed methods with the conventional expectation-maximization (EM) algorithm based on a series of datasets (synthetic and real human fMRI datasets). From simulation studies, we found a higher damping factor for the LM algorithm is better than lower damping factor for the fMRI data analysis. More importantly, in most cases, the expectation trust region algorithm is superior to the EM algorithm in terms of accuracy if the random effect variance is large. We also compare these algorithms on real human datasets which comprise repeated measures of fMRI in phased-encoded and random block experiment designs. We observed that the proposed method is faster in computation and robust to Gaussian noise for the fMRI analysis. The advantages and limitations of the suggested methods are discussed.     

Collective risk models with dependence

In actuarial science, collective risk models, in which the aggregate claim amount of a portfolio is defined in terms of random sums, play a crucial role. In these models, it is common to assume that the number of claims and their amounts are independent, even if this might not always be the case. We consider collective risk models with different dependence structures. Due to the importance of such risk models in an actuarial setting, we first investigate a collective risk model with dependence involving the family of multivariate mixed Erlang distributions. Other models based on mixtures involving bivariate and multivariate copulas in a more general setting are then presented. These different structures allow to link the number of claims to each claim amount, and to quantify the aggregate claim loss. Then, we use Archimedean and hierarchical Archimedean copulas in collective risk models, to model the dependence between the claim number random variable and the claim amount random variables involved in the random sum. Such dependence structures allow us to derive a computational methodology for the assessment of the aggregate claim amount. While being very flexible, this methodology is easy to implement, and can easily fit more complicated hierarchical structures.