高聚合度Ⅱ-型聚磷酸铵的合成

用聚合反应-热处理两段工艺合成了高聚合度的聚磷酸铵（APP）阻燃材料,其结构经XRD,粒度及平均聚合度表征。优化反应条件为：磷酸氢二铵1mol,n（磷酸氢二铵）：n（五氧化二磷）：n（脲）：1．0：1．0：0．3．干燥氨气氛下于290℃反应30min,再经250℃-280℃后处理100min-110min。APP的平均聚合度大于150,粒度小于50μm。     

Experimental and Computational Study of the Thermal Decomposition of 3‐Methyl‐3‐buten‐1‐ol in m‐Xylene Solution

An experimental study of the thermal decomposition of a β‐hydroxy alkene, 3‐methyl‐3‐buten‐1‐ol, in m‐xylene solution, has been carried out at five different temperatures in the range of 513.15–563.15 K. The temperature dependence of the rate constants for the decomposition of this compound in the corresponding Arrhenius equation is given by ln k (s^?1) = (25.65 ± 1.52) ? (17,944 ± 814) (kJ·mol^?1)·T^?1. A computational study has been carried out at the M05–2X/6–31+G(d,p) level of theory to calculate the rate constants and the activation parameters by the classical transition state theory. There is a good agreement between the experimental and calculated rate constants and activation Gibbs energies. The bonding characteristics of reactant, transition state, and products have been investigated by the natural bond orbital analysis, which provides the natural atomic charges and the Wiberg bond indices. Based on the results obtained, the mechanism proposed is a one‐step process proceeding through a six‐membered cyclic transition state, being a concerted and slightly asynchronous process. The results have been compared with those obtained previously by us (Struct Chem 2013, 24, 1811–1816) for the thermal decomposition of 3‐buten‐1‐ol, in m‐xylene solution. We can conclude that in the compound studied in this work, 3‐methyl‐3‐buten‐1‐ol, the effect of substitution at position 3 by a weakly activating CH₃ group is the stabilization of the transition state formed in the reaction and therefore a small increase in the rate of thermal decomposition.     

Structural and Kinetic Aspects of Blood Plasma Protein Adsorption on the Surface of Hydrophobic Polymers

Abstract

Due to the wide use of polymers in medicine, researchers are required to solve a very important problem–to understand the interaction between materials of nonphysiological origin and the surrounding biological liquids, and tissues, particularly blood.     

SPIN LABELED CYSTEINES AS SENSORS FOR PROTEIN-LIPID INTERACTION AND CONFORMATION IN RHODOPSIN

In stoichiometric amounts, the spin label N-tempoyl-(p-chloromercuribenzamide) reacts rapidly with one cysteine residue in membrane-bound bovine rhodopsin. This residue is distinct from the two reactive cysteines previously used as attachment sites for spectroscopic labels, and is on the external surface of the protein near the cytoplasmic membrane/aqueous interface. The spin-labeled side chain has revealed a light-induced conformational change in membrane-bound rhodopsin that is apparently not associated with protein aggregation. The changes are reversible upon the addition of 11-cis retinal, and the magnitude of the change is dependent on the identity of the phospholipid in the surrounding bilayer. Alteration of lipid composition has a much larger effect on bleached rhodopsin than rhodopsin itself, indicating that the former is more readily deformable in response to changes in bilayer properties. This is consistent with the loss of 11-cis retinal binding energy in opsin compared to rhodopsin. These results provide direct structural evidence that the conformation of a membrane protein can be modulated by the lipid properties.     

Structure and dynamics of annexin 12 bound to a planar lipid bilayer

Site directed spin labeling is used to investigate the protein annexin 12 absorbed on a single planar phospholipid bilayer of approximately 2-3 cm(2). Electron paramagnetic resonance spectra of nitroxide side chain at several topological sites reveal a conserved tertiary fold of the protein in the absorbed state, in agreement with earlier diffraction results. The angular dependent spectra of the two-dimensional microcrystals are shown to provide information on the degree of ordering of spin labels in a alpha-helix and in turn on the orientation of the alpha-helix with respect to the surface.     

Synthesis of new spin labels for Cu-free click conjugation

New pyrroline nitroxides attached to a terminal acetylenic sulfone, a dibenzocyclooctyne or a cyclooctyne carboxylic acid were synthesized and tested in Cu-free click reactions to conjugate these new spin labels with 4-azido-TEMPO, azidophenylalanine and an azidophenylalanine-containing protein.     

Oxidation-sensitive polymeric nanoparticles

We have recently demonstrated the possible use of organic polysulfides for the design of oxidation-sensitive colloidal carriers in the form of polymeric vesicles, which are particularly suitable for the encapsulation of hydrosoluble drugs. In the present research we extend our efforts to carriers specifically suitable for hydrophobic molecules. Exploiting the living emulsion polymerization of episulfides, we have produced new cross-linked polysulfide nanoparticles. Here we demonstrate how this process allows the production of stable nanoparticles with a good control over their size and functionality. The nanoparticles showed negligible cytotoxicity on a fibroblast model; furthermore, they exhibited sensitivity to oxidative conditions, which first produce swelling and then solubilize the material.