Tapping mode AFM evidence for an amorphous reticular phase in a condensation-cured hybrid elastomer: alpha,omega-dihydroxypoly(dimethylsiloxane)/poly(diethoxysiloxane)/fumed silica nanoparticles

A new surface phenomenon is reported for hybrid nanocomposites comprising (1) a low Tg poly(dimethylsiloxane) (PDMS) phase cross-linked by (2) a siliceous phase (SP) generated by in situ hydrolysis/condensation of poly(diethoxysiloxane) (PDES), and (3) fumed silica nanoparticles (FSN). After ambient temperature cure, tapping mode atomic force microscopy (TM-AFM) easily reveals near-surface FSN. For nanocomposites with higher PDES content, FSN surprisingly "disappear" after a further cure at 100 degrees C. The observation is explained by further condensation of extant siliceous fragments creating an amorphous reticular phase, which acts as a mechanical barrier between the FSN and the AFM tip.     

Dualities for the Domany–Kinzel Model

We study the Domany–Kinzel model, which is a class of discrete-time Markov processes in one-dimension with two parameters (p ₁,p ₂)[0,1]². When p ₁= and p ₂=(2– ²) with (,)[0,1]², the process can be identified with the mixed site-bond oriented percolation model on a square lattice with probabilities of a site being open and of a bond being open. This paper treats dualities for the Domany–Kinzel model _t ^A and the DKdual _t ^A starting from A. We prove that , as long as one of A,B is finite and p ₂p ₁.     

The "latent membrane permeability" concept: QSPR analysis of inter/intralaboratory variable Caco-2 permeability

Caco-2 cell monolayers grown on a filter support are the most widely used systems for predicting intestinal absorption. However, inter- and intralaboratory variability in Caco-2 permeability makes it difficult to analyze any QSPR relationship for a large number of compounds. We proposed the "latent membrane permeability" concept, assuming that all Caco-2 permeability data sets share a hidden, common relationship between their membrane permeability and physicochemical properties. An iterative calculation method was developed to handle this conceptual approach and applied to the analysis of Caco-2 permeability data sets from different sources. A thorough statistical analysis revealed that the "latent membrane permeability" concept be reasonable.     

Prolonged Plasma Levels of Ketoprofen after Oral Administration of Its α-Cyclodextrin Conjugate/Ethylcellulose Dispersion in Rats

6^A-O-[2-(3-benzoylphenyl)propinoyl]--cyclodextrin (KP/-CyD conjugate), in which an anti-inflammatory drug, ketoprofen (KP), is covalently bound to one of the primary hydroxyl groups of -cyclodextrin, was prepared, and the CyD conjugate-based prolonged-release system was designed by combining the KP/-CyD conjugate (used as a delayed-release fraction) with the KP/ethylcellulose (EC) solid dispersion (used as a slow-release fraction). The conjugate showed a typical delayed-release pattern after oral administration to rats, i.e., plasma levels of KP increased after a lag time of about 3 h and reached a maximum concentration at about 9 h. The co-administration of the conjugate and the EC solid dispersion gave a sustained-release pattern of KP, i.e., a constant plasma KP level was maintained for at least 24 h. The long circulating release patterns in plasma KP levels after oral administration were reflected in the anti-inflammatory effect using with carrageenan-induced acute edema in rat paw.     

Synthesis of long Poly(dA).Poly(dT) DNA without structural defects using enzymatic reaction; tailored ligated Poly(dA).Poly(dT)

Poly(dA).Poly(dT) molecules up to 1000 base pairs (bp) have been synthesized using enzymatic reaction, and characterization by STM observation shows that the DNA has no defects in the duplex structure.     

Structure of three new carotenoids with a 3-methoxy-5-keto-5,6-seco-4,6-cyclo-beta end group from the seeds of Pittosporum tobira

Three new carotenoids with a 3-methoxy-5-keto-5,6-seco-4,6-cyclo-beta end group (1-3) have been isolated from the seeds of Pittosporum tobira. Their structures were elucidated by detailed analyses of nuclear magnetic resonance and UV data.