偏最小二乘法在原子吸收光谱分析中的应用——钴和铟的同时测定

本文用偏最小二乘法（ＰＬＳ）校正了火焰原子吸收分析Ｉｎ２５２．１３７ｎｍ对Ｃｏ２５２．１３６ｎｍ的吸收线重叠干扰,对混合样中Ｃｏ和Ｉｎ的含量进行了测定,结果令人满意。     

Hybrid misclassification minimization

Given two finite point setsA andB in then-dimensional real spaceR ⁿ , we consider the NP-complete problem of minimizing the number of misclassified points by a plane attempting to divideR ⁿ into two halfspaces such that each open halfspace contains points mostly ofA orB. This problem is equivalent to determining a plane {x | x ^T w=} that maximizes the number of pointsx A satisfying inx ^T w>, plus the number of pointsx B satisfyingx ^T w<. A simple but fast algorithm is proposed that alternates between (i) minimizing the number of misclassified points by translation of the separating plane, and (ii) a rotation of the plane so that it minimizes a weighted average sum of the distances of the misclassified points to the separating plane. Existence of a global solution to an underlying hybrid minimization problem is established. Computational comparison with a parametric approach to solve the NP-complete problem indicates that our approach is considerably faster and appears to generalize better as determined by tenfold cross-validation.This material is based on research supported by Air Force Office of Scientific Research Grant F49620-94-1-0036 and National Science Foundation Grant CCR-9322479.     

Theoretical Study on the Mass Transfer of Metal Ions in Ion Exchange Process

The kinetics of ion exchange between Ca2 , Mg2 , Co(Ⅱ), Cu(Ⅱ),Ni(Ⅱ), Fe(Ⅲ), y3 or Sm3 , respectively, in 0.50 mol/L HC1 and H on macrorecticular sulfonic ion exchange resin and the kinetics of the same reactions (M -H exchange) when Mn(Ⅱ) coexisted in resin phase as accelerating ion were studied. The accelerating effect manifested and its rule are consistent with the accelerating effect theory based on the concept concerned with adsorption electrical double layer which has been suggested in a previous paper published.     

Rigid rod anchored to infinite membrane

We investigate the shape deformation of an infinite membrane anchored by a rigid rod. The density profile of the rod is calculated by the self-consistent-field theory and the shape of the membrane is predicted by the Helfrich membrane elasticity theory [W. Helfrich, Z. Naturforsch. 28c, 693 (1973)]. It is found that the membrane bends away from the rigid rod when the interaction between the rod and the membrane is repulsive or weakly attractive (adsorption). However, the pulled height of the membrane at first increases and then decreases with the increase of the adsorption strength. Compared to a Gaussian chain with the same length, the rigid rod covers much larger area of the membrane, whereas exerts less local entropic pressure on the membrane. An evident gap is found between the membrane and the rigid rod because the membrane's curvature has to be continuous. These behaviors are compared with that of the flexible-polymer-anchored membranes studied by previous Monte Carlo simulations and theoretical analysis. It is straightforward to extend this method to more complicated and real biological systems, such as infinite membrane/multiple chains, protein inclusion, or systems with phase separation.     

Amphiphilic miktoarm star copolymers can self-assemble into micelle-like aggregates in nonselective solvents: a case study of polyoxometalate based miktoarm stars

It is well-known that amphiphilic star-shaped copolymers can self-assemble in selective solvents to form complicated micellar constructs as a synergistic result of both the topological constraints and relative volume fractions of the arms. Although the association phenomena of amphiphilic stars have been observed in nonselective solvents, both the structural detail and formation mechanism of these associates are not clear yet. Moreover, these experimental observations are controversial with respect to molecularly dispersed starlike copolymers in nonselective solvents as is popularly believed. To clarify these issues, we have synthesized a series of polyoxometalate-based polystyrene-poly(ethylene glycol)(PS-PEG) miktoarm star supramolecular copolymers(SEW-1–5) by coupling a Keggin-type polyoxometalate of K_4[α-SiW_(12)O_(40)] with 1,2,3-triazolium bridged block copolymers of-PS_n-b~+-PEG_mI~-(n=17, 26, 39, 57, 81; m=45) through ionic exchange reactions, respectively. TEM imaging,contact angle and ~1H NMR studies reveal that SEW-2–5 self-assemble in chloroform, THF, and toluene to create micellelike aggregates ranging from cylinder to sphere with a PS corona and a PEG core, while for SEW-1, reverse bilayers are captured with a PEG corona and a PS core. Among these aggregates, the Keggin clusters of [α-SiW_(12)O_(40)]~(4-) localize at the core-corona interfaces between PS and PEG. In terms of solvent quality, chloroform, THF, and toluene are only slightly poorer for PEG than that for PS with a relative order of chloroformTHFtoluene. These unexpected aggregates originate from the topological constraints of the chemically different arms of PS and PEG in the miktoarm stars, where the weak incompatibility between the PS and PEG arms is intensified appropriately. The presence of the reverse bilayered structures of SEW-1 is due to the magnified steric hindrance of the PEG45 arm with decreasing the molecular weight of the PS17 arm. However, to the best of our knowledge,these are the first examples clearly indicating that miktoarm star copolymers can self-assemble in common good solvents or slightly selective solvents to generate micellelike aggregates. This scenario is not only in sharp contrast to the intuitively considered behavior of unimolecular miktoarm stars in nonselective solvents, but also rather different from the conventional selfassembly behavior of amphiphilic star copolymers in selective solvents.     

聚醚氨酯的氧化及其接枝共聚合的研究

本文研究了在聚醚氨酯表面上进行接枝共聚合的新方法。首先在聚醚氨酯薄膜上通过过氧化氢光氧化引入过氧化氢基,然后在还原剂亚铁盐或N,N-二甲基对甲苯胺的作用下引发丙烯酰胺接枝共聚合,反应具有低温快速的特点。产物经吸水性实验及扫描电子显微镜观察均证实了是一接枝共聚物。通过模型化合物的研究证明,接枝反应具有较高的选择性,接枝共聚占优势地发生在聚醚软段上,接枝地点很可能就在醚键旁的α-碳原子上。