Search Results - (Author, Cooperation:C. M. Cheng)

2018-03-20

The American Association of Immunologists (AAI)

0022-1767

1550-6606

Medicine

2018-04-21

American Physical Society (APS)

1098-0121

1095-3795

Physics

Surface physics, nanoscale physics, low-dimensional systems

2018-04-13

Nature Publishing Group (NPG)

2041-1723

Biology

Chemistry and Pharmacology

Natural Sciences in General

Physics

2012-12-04

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

Animals ; COUP Transcription Factor II/deficiency/genetics/*metabolism ; Cell Cycle Checkpoints ; Cell Line, Tumor ; *Cell Transformation, Neoplastic ; Disease Models, Animal ; Disease Progression ; Gene Deletion ; Humans ; Male ; Mice ; Neoplasm Metastasis ; PTEN Phosphohydrolase/deficiency/genetics ; Proportional Hazards Models ; Prostate/metabolism/pathology ; Prostatic Neoplasms/*metabolism/*pathology ; *Signal Transduction ; Smad4 Protein/deficiency/genetics/metabolism ; Transforming Growth Factor beta/*antagonists & inhibitors/metabolism

0093-934X

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Linguistics and Literary Studies

Medicine

Psychology

Electronic Resource

0006-291X

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Biology

Chemistry and Pharmacology

Physics

Electronic Resource

0887-624X

microspheres, aggregation ; divinylbenzene, copolymerization ; seeded emulsion polymerization ; particle morphology ; gel, phase separation ; monodisperse macrospheres ; Chemistry ; Polymer and Materials Science

Wiley InterScience Backfile Collection 1832-2000

Chemistry and Pharmacology

Monodisperse porous styrene-divinylbenzene copolymer particles were prepared via seeded emulsion polymerization using a mixture of linear polymer (polystyrene seed) and non-solvent as inert diluent. Experimental evidence was presented to describe the mechanism of formation of porous polymer particles during the copolymerization and solvent extraction stages, in which porosity was a consequence of phase separation in the presence of diluents. Pore structure formation was investigated by changes in copolymerization kinetics, gel content, crosslinking density, particle morphology, surface area, pore volume, and pore size distribution. The process of copolymerization was presented, based on the concepts of production, agglomeration, and fixation of the interior gel microspheres of polymer particles. A portion of linear polymer used as diluent was found to participate in the network structure while the porous matrix was built-up. The influence of the removal of the linear polymer from the matrix pores during the solvent extraction process on the porous structure was also discussed.

11 Ill.

Electronic Resource

0887-624X

monodisperse particles ; emulsion copolymerization, divinylbenzene ; porous particles ; macroporous structure ; linear polymer, diluent ; crosslinked domains ; Chemistry ; Polymer and Materials Science

Wiley InterScience Backfile Collection 1832-2000

Chemistry and Pharmacology

Monodisperse porous polymer particles in the size range of 10 μm in diameter were prepared via seeded emulsion polymerization. Linear polymer (polystyrene seed) or a mixture of linear polymer and solvent or nonsolvent were used as inert diluents. The pore diameters of these porous polymer particles were on the order of 1000 Å with pore volumes up to 0.9 mL/g and specific surface areas up to 200 m2/g. The physical features of the porous polymer particles depended on the diluent type and the crosslinker content, as well as the molecular weight of polymer seed particles. By varying the molecular weight of the linear polymer, monodisperse porous polymer particles with different pore size distribution could be synthesized. Polymer seed with a low degree of crosslinking instead of linear polymer could also be used to prepare monodisperse porous polymer particles with smaller pore volume and pore size.

11 Ill.

Electronic Resource

0887-624X

thymine styrene monomer ; functional styrene monomer ; multifunctional monomer ; photoresist ; photocrosslinking ; photopolymer ; 2π + 2π photocyclization ; Chemistry ; Polymer and Materials Science

Wiley InterScience Backfile Collection 1832-2000

Chemistry and Pharmacology

1 Ill.

Electronic Resource

0021-9304

Chemistry ; Polymer and Materials Science

Wiley InterScience Backfile Collection 1832-2000

Medicine

Technology

Fibrinogen adsorption on polymers from blood may mediate or potentiate thrombosis because of its involvement in both the intrinsic clotting system and the formation of platelet aggregates. While the kinetics of fibrinogen adsorption from plasma in vitro have previously been found to be very different on polar and nonpolar surfaces [T. A Horbett, “The kinetics of adsorption of plasma proteins to a series of hydrophilic-hydrophobic copolymers,” ACS Org. Coat. Plas. Chem., 40, 642-646 (1979)] the significance of this difference with respect to thrombogenesis in vivo has not been clarified. In this study, the kinetics of deposition of baboon 125I fibrinogen from plasma in vitro or from blood in vivo on a series of polymers was measured. The polymers chosen for this study had previously been found to have a large range in surface polarity and reactivity in the in vivo baboon shunt model. The kinetics of fibrinogen adsorption in vitro were observed to be of three types, depending on the polymer: (1) high initial adsorption decreasing to a lower steady state value; (2) constant throughout the time course; (3) low initial adsorption rising steadily to a plateau value. In vivo, fibrinogen deposition kinetics were of two types: (1) low, constant deposition throughout the time course, independent of heparinization; (2) low deposition initially followed by a second phase of greatly increased deposition (probably as fibrin) which was prevented or greatly decreased by heparinizing the animals. Polymers for which fibrinogen adsorption increased to a plateau in vitro were found to have a heparin inhibitable second phase of enhanced in vivo fibrinogen deposition. These polymers also have been found in previous studies to enhance the rate of platelet destruction when used as in vivo shunts on baboons. Conversely, most polymers with high initial in vitro fibrinogen adsorption followed by a decrease had low fibrinogen deposition behavior in vivo and were also minimally destructive of platelets. The adsorption kinetics of fibrinogen to polymers from blood in vivo and in vitro and the consumption of platelets in vivo induced by the polymers all vary with polymer polarity. More polar polymers had in vitro fibrinogen kinetics characterized by a rise to a plateau, in vivo fibrinogen deposition characterized by a second stage of great increase inhibitable by heparin, and enhanced platelet consumption. The correlation of three separate indicators of surface thrombogenicity with surface polarity suggests that more polar materials may be more thrombogenic because of an influence on the way in which fibrinogen interacts with these surfaces.

10 Ill.

Electronic Resource