Search results for "STICS"
showing 10 items of 21128 documents
Vanadium-based Ziegler-Natta catalyst supported on MgCl2(THF)2 for ethylene polymerization
1996
A supported magnesium‐vanadium‐aluminium catalyst was prepared by depositing –with the use of a milling technique–VOCl3 on the MgCl2(THF)2 support and subsequent activation with diethylaluminium chloride. Catalytic activity of the obtained system for ethylene polymerization was evaluated as a function of Mg/V and Al/V ratios as well as catalyst ageing time and polymerization temperature. High concentrations of THF in the catalytic system and considerable excess of an organoaluminium co‐catalyst were found to have no deactivating action on vanadium active sites. The catalyst obtained is stable and its activity for ethylene polymerization is high. It yields polyethylene with higher molecular …
Sense of coherence and health among home-dwelling older people.
2010
Sense of coherence (SOC) is important for maintaining health. The aim of this study was to investigate if the SOC experience among home-dwelling physically active older people differs from that of hospital patients with the same age and sex. Data were collected with questionnaires and structured interviews containing Antonovsky’s SOC scale in an age- and sex-matched study group (n=160). Non-parametric statistical analyses were performed. No differences were found in SOC between home-dwelling individuals and patients. Ninety-five percent of the home-dwelling individuals perceived themselves as being in good health and 42.5% among the patients (p<0.001). SOC and disease were predictors fo…
Production of Phosphorescent Coatings on 6082 Aluminum Using Sr0.95Eu0.02Dy0.03Al2O4-δ Powder and Plasma Electrolytic Oxidation
2019
In this study, a new approach for producing phosphorescent aluminum coatings was studied. Using the plasma electrolytic oxidation (PEO) process, a porous oxide coating was produced on the Al6082 aluminum alloy substrate. Afterwards, activated strontium aluminate (SrAl2O4: Eu2+, Dy3+) powder was filled into the cavities and pores of the PEO coating, which resulted in a surface that exhibits long-lasting luminescence. The structural and optical properties were studied using XRD, SEM, and photoluminescence measurements. It was found that the treatment time affects the morphology of the coating, which influences the amount of strontium aluminate powder that can be incorporated into the coating …
Amino-Acid-Based Polymerizable Surfactants for the Synthesis of Chiral Nanoparticles
2016
Amino-acid-based chiral surfactants with polymerizable moieties are synthesized, and a versatile approach to prepare particles thereof with a chiral surface functionality is presented. As an example of an application, the synthesized particles are tested for their ability as nucleating agents in the enantioselective crystallization of amino acid conglomerate systems, taking rac-asparagine as a model system. Particles resulting from chiral surfactants with different tail groups are compared and the results demonstrate that only the chiral nanoparticles made of the polymerizable surfactant are able to act efficiently as nucleation agent in enantioselective crystallization.
Measurements on the temperature dependence of the cationic polymerization of styrene in CH2Cl2 with CF3SO3H as catalyst
1979
The cationic polymerization of styrene in CH2Cl2 with CF3SO3H as catalyst and at low monomer concentrations shows, at −15°C, −45°C and −60°C, the same formal dependence on monomer concentration. The dependence on the catalyst concentration is approximately but not exactly of a third order.
Effect of hydrogen on the ethylene polymerization process over Ziegler-Natta catalysts supported on MgCl2(THF)2. I. Studies of the chain-transfer rea…
2000
The effect of hydrogen on the molecular weight of polyethylene obtained over vanadium catalysts (based on VCl4 and VOCl3) supported on MgCl2(THF)2 was studied and the results were compared to those obtained for similar titanium catalysts. It was confirmed that the dependencies of the transfer reaction on the hydrogen concentration are a half-order in all investigated systems. However, the transition metal of the catalytic site affects the ratio of the transfer rate with hydrogen to the propagation rate (ktr,H/kp) and the results showed that hydrogen is a more effective agent of polyethylene molecular weight control in vanadium-based systems as compared to the titanium catalyst. © 2000 John …
Tailoring polymers through interplay of ligands within precatalysts: 8-(Nitro/benzhydryl-arylimino)-7,7-dimethyl-5,6-dihydroquinolylnickel halides in…
2017
A series of 8-(nitro/benzhydryl-substituted arylimino)-7,7-dimethyl-5,6-dihydroquinolines and the corresponding nickel halide complexes were synthesized and characterized. Molecular structures of representative nickel complexes were determined by single crystal X-ray diffraction, showing the dinuclear dimers with distorted square-pyramidal geometry around the nickel center. The binding energies determined by X-ray photoelectron spectroscopy (XPS) indicate the effective coordination between the sp2-nitrogen and nickel atoms as well as the influence of both the halogen ligands and the substituents within dihydroquinolines on the strength of the NiN bond. Ethylene polymerization with the nicke…
Nature of activating effect of two-step polymerization of propylene
1999
The prepolymerization effect on propylene polymerization in the presence of a TiCl 3 -based catalyst, modified by di-n-buthyl ether, was studied. The influence of prepolymerization on the electron spin resonance spectra and morphology of the catalyst, as well as the properties and the morphology of both prepolymer and regular polymerization products, was investigated. The polymer morphology was evaluated through scanning electron microscopy, polymer bulk density, and particle size distribution. Some evidence of the enhancement effect of prepolymerization on the catalyst activity and stereospecificity was obtained. No influence from prepolymerization was observed on molecular weight and its …
Cisplatin plus weekly vinorelbine versus cisplatin plus vinorelbine on days 1 and 8 in advanced non-small cell lung cancer: a prospective randomized …
2008
Summary Purpose A phase III randomized trial was carried out to compare two schedules of the vinorelbine (VNR)–cisplatin (CDDP) regimen in patients with locally advanced unresectable poor prognosis stage IIIB or metastatic stage IV non-small cell lung cancer. The primary endpoints were overall survival (OS) and analysis of toxicity, while secondary endpoints included response rates, time-to-progression (TTP) and quality of life (QoL). Patients and methods Eligible patients were randomized to receive: (a) VNR 25 mg/m 2 on day 1, 8 and 15 plus CDDP 100 mg/m 2 on day 1 every 4 weeks or (b) VNR 30 mg/m 2 on day 1 and 8 plus CDDP 80 mg/m 2 on day 1 every 3 weeks. All patients were chemotherapy-n…
Synthesis of branched polyethylenes by the tandem catalysis of silica-supported linked cyclopentadienyl-amido titanium catalysts and a homogeneous di…
2003
The synthesis of branched polyethylenes by ethylene polymerization with new tandem catalyst systems consisting of methylaluminoxane-preactivated linked cyclopentadienyl-amido titanium catalysts [Ti(η5:η1-C5Me4SiMe2NR)Cl2 (R = Me or tBu)] supported on pyridylethylsilane-modified silica (PySTiNMe and PySTiNtBu) and homogeneous dibromo nickel catalyst having a pyridyl-2,6-diisopropylphenylimine ligand (PyminNiBr2) in the presence of modified methylaluminoxane was investigated. Ethylene polymerization with only PyminNiBr2 yielded a mixture of 1- and 2-olefin oligomers with methyl branches [weight-average molecular weight (Mw) ∼ 460)] with a ratio of about 1:7. By the combination of this nickel …