乳酸基聚氨酯与羟基磷灰石的共价杂化

由乳酸聚乙二醇酯二醇中间体（LPEG）、羟基磷灰石以及甲苯-2,4-二异氰酸酯（TDI）发生加聚反应,探讨羟基磷灰石与乳酸基聚氨酯的共价杂化。 对提纯后的杂化产物(HA-g-LPEU5K)及相应共混体系(HA/LPEU5K)的结构及其热稳定性进行了分析对比,HA-g-LPEU5K和HA/LPEU5K热解的剩余百分数分别为92.5%和41.7%。 共价和物理杂化物静置3 d后,分别呈均相、出现少量HA沉淀。 杂化体系的稳定性明显高于共混物,说明乳酸基聚氨酯与羟基磷灰石通过共价键结合而实现了共价杂化。 此外,杂化体系呈现可降解性。     

Blow‐up dynamics of L2−critical inhomogeneous fractional nonlinear Schrödinger equation

The purpose of this work is to investigate the blow‐up dynamics of L²?critical focusing inhomogeneous fractional nonlinear Schrödinger equation: with 0<b<1. For this, we establish a new compactness lemma related to the equation. By applying this lemma, we study the dynamical behavior for blow‐up solutions for initial data satisfying , where Q is the ground state solution of our problem.     

反相色谱法测定聚苯乙烯的溶度参数

用反相色谱法测定了聚苯乙烯的溶度参数,实验数据用计算机予以处理,简化了测定过程,建议探针分子与聚合物的极性应尽可能接近。     

Synthesis of New Substituted 4-Amino-3,5-dinitropyridine Derivatives

Facile synthetic routes for the preparation of some new 4-amino-3,5-dinitropyridine derivatives have been revealed. Nitration of 2-chloropyridin-4-amine （1） as a starting material, in an unexpected one-step reaction, to give dinitrated derivatives, followed by nucleophilic substitution reactions with sodium azide, potassium fluoride, ammonia, methylamine, and 4-nitroimidazol, respectively, gave substituted 4-amino-3,5-dinitropyridine derivatives. Meanwhile, its azide derivative underwent a ring closure conversion into 7-amino-6-nitro-[1,2,5]oxadiazolo[3,4-b]- pyridine-1-oxide. It is of significance that all of the nucleophilic substitution reactions were carried out under mild conditions.     

Dislocation cross-slip mechanisms in aluminum

We have systematically studied dislocation cross-slip in Al at zero temperature by atomistic simulations, focusing on the dependence of the transition paths and energy barriers on dislocation length and position. We find that for a short dislocation segment, the cross-slip follows the uniform Fleischer (FL) mechanism. For a longer dislocation segment, we have identified two different cross-slip mechanisms depending on the initial and final positions of the dislocation. If the initial and final positions are symmetric relative to the intersection of the primary and cross-slip planes, the dislocation cross-slips via the Friedel–Escaig (FE) mechanism. However, when the initial and final positions are asymmetric, the dislocation cross-slips via a combination of the FL and FE mechanisms. The leading partial folds over to the cross-slip plane first, forming a stair-rod dislocation at the intersection with which the trailing partial then merges via the FL mechanism. Afterwards, constrictions appear asymmetrically and move away from each other to complete the cross-slip via the FE mechanism.     

Improved fluoroquinolone detection in ELISA through engineering of a broad-specific single-chain variable fragment binding simultaneously to 20 fluoroquinolones

Fluoroquinolones (FQs) are a group of synthetic, broad-spectrum antibacterial agents. Due to its extensive use in animal industry and aquaculture, residues of these antibiotics and the emergence of bacteria resistant to FQs have become a major public health issue. To prepare a generic antibody capable of recognizing nearly all FQs, a single-chain variable fragment (scFv) was generated from the murine hybridoma cells C49H1 producing a FQ-specific monoclonal antibody. This scFv was characterized by indirect competitive enzyme-linked immunosorbent assay (ciELISA), and it showed identical binding properties to parental monoclonal antibody: it was capable of recognizing 17 of 20 targeted FQs below maximum residue limits, except for sarafloxacin (SAR), difloxacin (DIF), and trovafloxacin (TRO) which are highly concerned members in the FQs family. In order to broaden the specificity of this scFv to SAR and its analogues (DIF and TRO), protein homology modeling and antibody-ligands docking analysis were employed to identify the potential key amino acid residues involved in hapten antibody. A mutagenesis phage display library was generated by site directed mutagenesis randomizing five aminoacid residues in the third heavy-chain complementarity determining region. After one round of panning against biotinylated norfloxacin (NOR) and four rounds of panning against biotinylated SAR, scFv variants we screened showed up to 10-fold improved IC(50) against SAR, DIF, and TRO in ciELISA while the specificity against other FQs was fully retained.     

Moving planes, moving spheres, and a priori estimates

In this paper, we use the method of moving planes and the method of moving spheres to obtain a priori estimates for the solutions of semi-linear elliptic equations.Using the ‘method of moving planes’, we establish a sharper estimate on the solutions for prescribing scalar curvature equations with indefinite curvature functions and thus generalized a resent result of Lin.Applying ‘the method of moving spheres’, we give a different proof for a well-known sup+inf inequality established by Brezis, Li and Shafrir.     

Gaussian curvature on singular surfaces

We consider prescribing Gaussian curvature on surfaces with conical singularities in both critical and supercritical cases. First we prove a variant of Kazdan-Warner type necessary conditions. Then we obtain sufficient conditions for a function to be the Gaussian curvature of some pointwise conformai singular metric. We only require that the values of the function are not too large at singular points of the metric with the smallest angle, say, less or equal to 0, or less than its average value. To prove the results, we apply some new ideas and techniques. One of them is to estimate the total curvature along a certain minimizing sequence by using the “Distribution of Mass Principle” and the behavior of the critical points at infinity.     

Multi‐responsive methylcellulose/Fe‐alginate‐g‐PVA/PVA/Fe3O4 microgels for immobilizing enzyme

To take advantage of the respective character of methylcellulose (MC), poly(vinyl alcohol) (PVA), and alginate, novel physically cross‐linked methylcellulose/Fe‐alginate‐g‐PVA/PVA (MC/Fe‐Alg‐g‐PVA/PVA) microgels were prepared by emulsification/thermal gelation/freezing–thawing/ionic cross‐linking technique. Subsequently, some ferrous ions bound in the microgels were transformed into magnetite via in situ self oxidation. A model enzyme α‐amylase was immobilized into microgels by direct adsorption. The release behavior of α‐amylase indicated that the obtained complex microgels were magnetic‐, temperature‐, and pH‐ triple sensitive. Copyright © 2010 John Wiley & Sons, Ltd.     

Electrically tunable magnetic configuration on vacancy-doped GaSe monolayer

Group-IIIA metal-monochalcogenides with the enticing properties have attracted tremendous attention across various scientific disciplines. With the aim to satisfy the multiple demands of device applications, here we report a design framework on GaSe monolayer in an effort to tune the electronic and magnetic properties through a dual modulation of vacancy doping and electric field. A half-metallicity with a 100% spin polarization is generated in a Ga vacancy doped GaSe monolayer due to the nonbonding 4p electronic orbital of the surrounding Se atoms. The stability of magnetic moment is found to be determined by the direction of applied electric field. A switchable magnetic configuration in Ga vacancy doped GaSe monolayer is achieved under a critical electric field of 0.6 V/Å. Electric field induces redistribution of the electronic states. Finally, charge transfers are found to be responsible for the controllable magnetic structure in this system. The magnetic modulation on GaSe monolayer in this work offers some references for the design and fabrication of tunable two-dimensional spintronic device.