Systematic studies on dibenzhydryl and pentiptycenyl substituted pyridine-imine nickel(ii) mediated ethylene polymerization

2020 ◽  
Vol 49 (15) ◽  
pp. 4824-4833 ◽  
Author(s):  
Chaoqun Wang ◽  
Yuxing Zhang ◽  
Hongliang Mu ◽  
Zhongbao Jian
Keyword(s):  
Molecular Weight ◽  
Ethylene Polymerization ◽  
Nickel Catalysts ◽  
Low Molecular Weight

Pyridine-imine nickel catalysts bearing different N-aryl/imine substituents were systematically studied for ethylene polymerization to produce low-molecular-weight and branched polyethylenes.

Bis-cycloheptyl-fused bis(imino)pyridine-cobalt catalysts for PE wax formation: positive effects of fluoride substitution on catalytic performance and thermal stability

2020 ◽  
Vol 49 (27) ◽  
pp. 9425-9437 ◽  
Author(s):  
Qiuyue Zhang ◽  
Ningning Wu ◽  
Junfeng Xiang ◽  
Gregory A. Solan ◽  
Hongyi Suo ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Molecular Weight ◽  
Ethylene Polymerization ◽  
Catalytic Performance ◽  
Cobalt Catalysts ◽  
Low Molecular Weight ◽  
Polymerization Catalysts ◽  
Positive Effects

The depicted ethylene polymerization catalysts exhibited optimal activities at 60 °C forming low molecular weight PE waxes; ortho-F substitution proved beneficial.

Synthesis of hyperbranched low molecular weight polyethylene oils by an iminopyridine nickel(ii) catalyst

2017 ◽  
Vol 8 (41) ◽  
pp. 6443-6454 ◽  
Author(s):  
Ilaria D'Auria ◽  
Stefano Milione ◽  
Tonino Caruso ◽  
Gabriele Balducci ◽  
Claudio Pellecchia
Keyword(s):  
Molecular Weight ◽  
Diffraction Analysis ◽  
Ethylene Polymerization ◽  
Low Molecular Weight ◽  
X Ray Diffraction ◽  
X Ray

A 6-(2,6-dimethylphenyl)-2-(2,6-diisopropylphenyl)iminopyridine dibromo nickel(ii) complex was synthesized, characterized by X-ray diffraction analysis and tested in ethylene polymerization using diethylaluminumchloride as the cocatalyst.

Boryl-substituted Zirconocene Dichloride Complexes as Catalyst Precursors for Homogeneous Ethylene Polymerization

2007 ◽  
Vol 62 (3) ◽  
pp. 314-322 ◽  
Author(s):  
Alexandra Kestel-Jakob ◽  
Helmut G. Alt
Keyword(s):  
Molecular Weight ◽  
Ethylene Polymerization ◽  
Nickel Catalysts ◽  
Synthesis And Characterization ◽  
Zirconocene Dichloride ◽  
Molecular Weight Distributions ◽  
Weight Distributions ◽  
Methyl Aluminoxane

The synthesis and characterization of 16 new boryl-substituted zirconocene dichloride complexes are reported. After activation with methyl aluminoxane (MAO) these complexes are catalysts for homogeneous ethylene polymerization. The combination of these complexes with nickel catalysts containing Lewis basic substituents produces polymers with bimodal molecular weight distributions.

Phenoxycycloalkylimine Ligated Zirconium Complexes for Ethylene Polymerization:  Formation of Vinyl-Terminated Low Molecular Weight Polyethylenes with High Efficiency

2006 ◽  
Vol 39 (25) ◽  
pp. 8584-8593 ◽  
Author(s):  
Hiroshi Terao ◽  
Sei-ichi Ishii ◽  
Junji Saito ◽  
Sadahiko Matsuura ◽  
Makoto Mitani ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Ethylene Polymerization ◽  
High Efficiency ◽  
Low Molecular Weight ◽  
Zirconium Complexes

A high-performance oil-free backing pump for electron microscopes

1978 ◽  
Vol 36 (1) ◽  
pp. 110-111
Author(s):  
G.K.W. Balkau ◽  
E. Bez ◽  
J.L. Farrant
Keyword(s):  
Molecular Weight ◽  
Electron Microscope ◽  
Hot Spots ◽  
High Performance ◽  
Carbonaceous Material ◽  
Contamination Rate ◽  
Low Molecular Weight ◽  
Principal Source ◽  
Rotary Pumps ◽  
Electron Microscopes

The earliest account of the contamination of electron microscope specimens by the deposition of carbonaceous material during electron irradiation was published in 1947 by Watson who was then working in Canada. It was soon established that this carbonaceous material is formed from organic vapours, and it is now recognized that the principal source is the oil-sealed rotary pumps which provide the backing vacuum. It has been shown that the organic vapours consist of low molecular weight fragments of oil molecules which have been degraded at hot spots produced by friction between the vanes and the surfaces on which they slide. As satisfactory oil-free pumps are unavailable, it is standard electron microscope practice to reduce the partial pressure of organic vapours in the microscope in the vicinity of the specimen by using liquid-nitrogen cooled anti-contamination devices. Traps of this type are sufficient to reduce the contamination rate to about 0.1 Å per min, which is tolerable for many investigations.

Low-molecular-weight heparin in the prevention and treatment of thromboembolic disorders

1998 ◽  
Vol 1 (5) ◽  
pp. 166-174 ◽  
Author(s):  
Evelyn R Hermes De Santis ◽  
Betsy S Laumeister ◽  
Vidhu Bansal ◽  
Vandana Kataria ◽  
Preeti Loomba ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Low Molecular Weight Heparin ◽  
Low Molecular Weight ◽  
Prevention And Treatment

Venous thromboembolism in a general hospital. An update with low molecular weight heparin prophylaxis

VASA ◽  
2007 ◽  
Vol 36 (1) ◽  
pp. 17-22
Author(s):  
Schulz ◽  
Kesselring ◽  
Seeberger ◽  
Andresen
Keyword(s):  
Molecular Weight ◽  
Pulmonary Embolism ◽  
Venous Thromboembolism ◽  
Low Molecular Weight ◽  
Trauma Patients ◽  
Vte Prophylaxis ◽  
Vein Thrombosis ◽  
Patients At Risk ◽  
Hospital Stays ◽  
Event Rates

Background: Patients admitted to hospital for surgery or acute medical illnesses have a high risk for venous thromboembolism (VTE). Today’s widespread use of low molecular weight heparins (LMWH) for VTE prophylaxis is supposed to have reduced VTE rates substantially. However, data concerning the overall effectiveness of LMWH prophylaxis is sparse. Patients and methods: We prospectively studied all patients with symptomatic and objectively confirmed VTE seen in our hospital over a three year period. Event rates in different wards were analysed and compared. VTE prophylaxis with Enoxaparin was given to all patients at risk during their hospital stay. Results: A total of 50 464 inpatients were treated during the study period. 461 examinations were carried out for symptoms suggestive of VTE and yielded 89 positive results in 85 patients. Seventy eight patients were found to have deep vein thrombosis, 7 had pulmonary embolism, and 4 had both deep venous thrombosis and pulmonary embolism. The overall in hospital VTE event rate was 0.17%. The rate decreased during the study period from 0.22 in year one to 0,16 in year two and 0.13 % in year three. It ranged highest in neurologic and trauma patients (0.32%) and lowest (0.08%) in gynecology-obstetrics. Conclusions: With a simple and strictly applied regimen of prophylaxis with LMWH the overall rate of symptomatic VTE was very low in our hospitalized patients. Beside LMWH prophylaxis, shortening hospital stays and substantial improvements in surgical and anasthesia techniques achieved during the last decades probably play an essential role in decreasing VTE rates.

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