The structure and properties of nanocomposites of poly(ethylene oxide), with Ag and Au nanoparticles, surface modified with a 1:1 (by volume) oleylamine/oleic acid mixture, were investigated via transmission electron microscopy, scanning electron microscopy, thermogravimetric analysis, differential scanning calorimetry (DSC), infrared spectroscopy, dynamic mechanical analysis, and static mechan...

The tandem C2-domains of synaptotagmin 1 (syt) function as Ca(2+)-binding modules that trigger exocytosis; in the absence of Ca(2+), syt inhibits spontaneous release. Here, we used proline linkers to constrain and alter the relative orientation of these C2-domains. Short poly-proline helices have a period of three, so large changes in the relative disposition of the C2-domains result from chang...

In Pseudomonas aeriginosa, a gene, ppx, that encodes exopolyphosphatase [exopoly(P)ase; EC 3.6.1.11] of 506 amino acids (56,419 Da) was found downstream of the gene for polyphosphate kinase, ppk. Since ppx is located in the opposite direction of the ppk gene, they do not constitute an operon. The predicted amino acid sequence of PPX is 41% identical with Escherichia coli PPX. The gene product o...

Electric conductivity of conducting polymers has been steadily enhanced towards a level worthy of being called its alias, "synthetic metal". PEDOT:PSS (poly(3,4-ethylenedioxythiophene) doped with poly(styrene sulfonate)), as a representative conducting polymer, recently reached around 3,000 S cm(-1), the value to open the possibility to replace transparent conductive oxides. The leading strateg...

The main interest of this work was the investigation of the transport mechanisms of salmon calcitonin through the epithelial cell monolayer in the presence and absence of pH-sensitive hydrogel nanospheres composed of poly(methacrylic acid-grafted-poly(ethylene glycol)) (PMAA-g-EG). For this purpose, a gastrointestinal cell culture model, the Caco-2 cell line, was employed. The transport of othe...

poly(vinyl acetate) is synthesized via solution polymerization, and then it is converted to poly(vinyl alcohol) by alkaline alcoholysis. the aim of the work study was to investigate statistically the  influence of reaction variables in vinyl acetate polymerization, the conversion of this monomer to polymer, degree of branching of acetyl group in poly(vinyl acetate), as well as the molecular wei...

thermodynamic study on the interaction of β-cd with poly ethylene oxide and poly acrylic acid was performed by isothermal titration calorimetry at 298k. when β-cd is added to the interpolymer complex, competition is created between host-guest and hydrogen bond. enthalpy of interaction between the β-cd and interpolymer complex was calculated using the extended solvation theory. p=1 shows that wi...

in this research, hydrogels based on poly vinyl alcohol and poly acrylic acid blend were prepared which were cross-linked by applied thermal conditions. afterward, effects of time and heating on water uptake were investigated. the highest water uptake value exhibited by the sample that was heated for 20 min. at 110 ºc was about 2129% after 4 days at equilibrium state. hydrogels exhibited ph-sen...