beside ziegler-natta and phillips catalysts the development of methylaluminoxane (mao) as cocatalyst incombination with metallocenes or other transition metal complexes for the polymerization of olefins haswidely increased the possibilities in controlling the polymer composition, polymer structure, tacticity and special properties with high precision. these catalysts allow the synthesis of isot...

the stereospecific polymerization of conjugated dienes began in 1954 with the first catalysts obtained by combining ticl4 or ticl3 with aluminum-alkyls, i.e. the catalytic systems previously employed for ethylene and propylene polymerizations. subsequently, many other catalytic systems were obtained and examined by a combination of transition metal or lanthanide compounds with appropriate alkyl...

BACKGROUND Cancer is the second leading cause of death among U.S. children with few known risk factors. There is increasing interest in the role of air pollutants, including benzene and 1,3-butadiene, in the etiology of childhood cancers. OBJECTIVE Our goal was to assess whether census tracts with the highest benzene or 1,3-butadiene ambient air levels have increased childhood lymphohematopoi...

--The macrophage content of cell suspensions from naturally occurring mouse tumours has been assessed by the Fc-mediated phagocytosis assay, and the results compared with the individual tumour's capacity for spontaneous metastasis and with its pulmonary colonization potential after i.v. inoculation. It was found that these tumours differ in their properties from the transplantable fibrosarcomas...

A retrospective mortality analysis and prospective morbidity and haematological analyses were performed for Shell Deer Park Manufacturing Complex (DPMC) male employees who worked in jobs with potential exposure to 1,3-butadiene from 1948 to 1989. 614 employees qualified for the mortality study (1948-89), 438 of those were still employed during the period of the morbidity study (1982-9), and 429...

6Li, 15N, and 13C NMR spectroscopic investigations of [6Li,15N]lithium hexamethyldisilazide ([6Li,15N]LiHMDS) coordinated by 29 polyamines, polyethers, and aminoethers reveal a range of structural types including η1-coordinated monoand disolvated dimers, η2-coordinated (3-coordinate) monomers, η1,η2-coordinated (4-coordinate) monomers, η2,η2-coordinated (5-coordinate) monomers, polymers (linked...

The mechanistic relationship between amyloid β1-42 (Aβ1-42) and the alteration of Tau protein are debated. We investigated the effect of Aβ1-42 monomers and oligomers on Tau, using mice expressing wild-type human Tau that do not spontaneously develop Tau pathology. After intraventricular injection of Aβ1-42, mice were sacrificed after 3 h or 4 days. The short-lasting treatment with Aβ monomers,...