scholarly journals LOW-MOLECULAR WEIGHT POLYETHYLENE AND ITS EFFECT ON THE PROPERTIES OF ASPHALT CONCRETE

Author(s):  
Le Chan Min Dat ◽  
◽  
M.Yu. Protsenko ◽  
Author(s):  
Александр Борисович Соломенцев ◽  
Моиз Режист ◽  
Швендески Маселюс Жозеф

Получены значения динамической вязкости битумного вяжущего с добавками низкомолекулярного полиэтилена в температурном интервале 60…160 °С. При введении полимерных добавок в дорожный битум вязкость битума повышается. Наиболее высокие значения динамической вязкости наблюдаются у полимерной добавки Вискодор - ПВ1, это ярко выражено при расходе 4 % добавки от массы битума и при температурах ниже 130°С. Добавка неокисленного низкомолекулярного полиэтилена Honeyvell Titan 7205 увеличивает вязкость в большей степени, чем добавка окисленного полиэтилена Honeyvell Titan 7686. Определены допустимые технологические температуры асфальтобетонных смесей с полимерными добавками на этапах структурообразования асфальтобетона. We obtained the values of the dynamic viscosity of bitumen binder with additives of polyethylene with low molecular weight in the temperature range of 60…160 °C. When polymer additives are introduced into road bitumen, the viscosity of bitumen increases. The highest values of dynamic viscosity are observed for the polymer additive Viskodor - PV1, this is clearly pronounced at the consumption of 4 % of the additive based on the mass of bitumen and at temperatures below 130 °С. The additive of unoxidized low molecular weight polyethylene Honeyvell Titan 7205 increases the viscosity to a greater extent than the additive of oxidized polyethylene Honeyvell Titan 7686. We determined as well the permissible technological temperatures of asphalt concrete mixtures with polymer additives at the stages of structure formation of asphalt concrete.


Author(s):  
G.K.W. Balkau ◽  
E. Bez ◽  
J.L. Farrant

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.


1998 ◽  
Vol 1 (5) ◽  
pp. 166-174 ◽  
Author(s):  
Evelyn R Hermes De Santis ◽  
Betsy S Laumeister ◽  
Vidhu Bansal ◽  
Vandana Kataria ◽  
Preeti Loomba ◽  
...  

VASA ◽  
2007 ◽  
Vol 36 (1) ◽  
pp. 17-22
Author(s):  
Schulz ◽  
Kesselring ◽  
Seeberger ◽  
Andresen

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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