Stereospecific Polymerization Technology. Progress and Expectation.

Stereospecific carbene polymerization with oxygenated Rh(diene) species.

Polymers bearing polar functionalities are important materials, since they exhibit beneficial properties with respect to adhesion, paint/printability and surface properties. Commercial synthesis of these materials is mainly based on radical processes, which (so far) only allow poor control over the stereochemistry of the resulting polymers. 2 ] Stereo-controlled polymerisation generally require...

Highly trans-stereospecific Isoprene Polymerization by Neodymium Borohydrido Catalysts

Expectation Confirmation in Technology Use

W propose a model to study expectation confirmation in information systems. The proposed model is based on the assimilation-contrast model and prospect theory, and suggests that both are needed to account for the magnitude and direction of the deviations between experiences and expectations. Using the technology acceptance model’s (TAM) primary construct—namely, perceived usefulness—expectation...

Trans-stereospecific polymerization of butadiene and random copolymerization with styrene using borohydrido neodymium/magnesium dialkyl catalysts

The combination of a neodymium borohydride, Nd(BH4)3(THF)3 (1) or Cp*Nd(BH4)2(THF)x (2), with MgBuEt (BEM), affords an efficient and highly selective (up to 96.7% 1,4-trans) catalyst for butadiene polymerization. In the presence of excesses of Mg co-catalyst, polymer chain transfer takes place between neodymium and magnesium, and significant amounts of 1,2-units are observed. When considered fo...

Progress in device technology.

Advances in implantable device technology over the past few years can be seen in these illustrations. The photograph on the left shows a 1997-model implantable cardioverter-defibrillator (ICD) in front of an older version. Beside it is a modern single-chamber pacemaker in front of an older mercury-zinc–cell model. The Table shows their relative weights. These devices are now small enough to per...