Photoinitiated crosslinking of low density polyethylene: II. Morphology and properties

The crystalline morphology and physical properties of photocrosslinked polyethylene in a low density polyethylene (LDPE)-benzophenone (BP)-triallyl isocyanurate (TAIC) system have been studied. The results of X-ray diffraction and DSC thermal analysis indicate that the effect of crosslinking on the degree of crystallinity of the material is quite limited, but the presence of crosslinks can affect the regularity of the crystal regions. This is proposed to be responsible for the slight variation in properties of the crosslinked material at room temperature, such as the decrease of modulus and the changes of yield behavior. The main improvements in properties of the photocrosslinked polyethylene are found at high temperatures, especially above the melting point. The strength is increased, and the heat distortion temperature is enhanced significantly, as previously reported in the literature.     

Wobbling in modern motorcycles

Serious personal injuries have been reported, caused by motorcycles which suddenly began to wobble when ridden at moderate to high speed. A random sample of 1043 owners of 1978–1982 model year motorcycles was interviewed concerning their experience of wobbling in 1982. The response rate was 95%. Wobbling was reported by 45% of the owners, 8% reported at least one incident of severe wobbling. This figure indicates that about 6000 riders in Sweden experienced severe wobbling during 1982. Wobbling increased proportionately both with the distance ridden and engine displacement and was highest among those riders who make heavy use of the engine's power. A statistically significant difference in wobbling was found between Japanese and other manufacturers. The reported average speed where wobbling occurred was 118 .     

The International Stripa Project: an overview

The International Stripa Project was a cooperative research and development project among several member countries of the Nuclear Energy Agency of the Organization for Economic Cooperation and Development. The scientific and technical objectives of the project were to investigate several aspects of technology concerned with the feasibility and safety of disposal of long-lived, heat-generating radioactive waste at depth in granitic rocks. In particular, the Stripa Project addressed: 1) the development of instruments and procedures to characterize candidate repository sites; 2) the understanding and modelling of groundwater flow and solute transport in fractured crystalline rock; and 3) the design of engineered barriers capable of contributing to waste isolation by restricting groundwater flow in proximity to the waste containers and in the surrounding host rock. This overview summarizes the work focussed on natural barriers and engineered barriers.     

Predicting episodic memory performance in dementia: Is severity all there is?

Whether individual differences in demographic, psychometric, and biological domains can predict episodic memory in dementia was investigated. Mildly to moderately demented very old persons performed episodic memory tasks (free recall and recognition of slowly and rapidly presented random words, free and cued recall of organizable words, and recognition of dated and contemporary famous faces). A factor analysis of the memory measures yielded 2 factors, 1 indexing recall and 1 recognition. Controlling for severity of dementia, only 2 predictors contributed to performance: (a) Block Design (a marker of fluid intelligence) was positively related to recall, and (b) age was negatively related to recognition. Although these results are similar to data reported on predictors of episodic memory in normal aging, (a) the number of predictive variables appears to be reduced in dementia, and (b) age seems to affect recall and recognition differentially in normal aging and dementia. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Mass fragmentographic determination of docosenoic acid in rapeseed oils

A highly sensitive and accurate reference method for determination of docosenoic acid (mainly erucic acid, 22∶1n−9) in different rapeseed oils is described. A fixed amount of [1-¹⁴C]erucic acid methyl ester (about 1 μg) is added to a fixed amount of oil. After treatment with sodium methoxide/methanol reagent and extraction with hexane, the amount of unlabeled erucic acid is determined from the ratio between the recordings at m/e 320 and m/e 322 obtained after analysis with a combined gas chromatograph-mass spectrometer equipped with an MID (multiple ion detector). The two ions used correspond to the M-32 peak in the mass spectrum of unlabeled and [1-¹⁴C]labeled erucic acid methyl ester. The relative standard deviation of the method is about 1.8%. The method was compared with a gas chromatographic method for determination of erucic acid.     

Polyamine deactivation of integrated poly(dimethylsiloxane) structures investigated by radionuclide imaging and capillary electrophoresis experiments

The poly(dimethylsiloxane) (PDMS) material provides a number of advantageous features, such as flexibility, elasticity, and transparency, making it useful in integrated analytical systems. Hard fused-silica capillary structures and soft PDMS channels can easily be combined by a tight fit, which offers many alternatives for structure combinations. PDMS and fused silica are in different ways prone to adsorption of low levels of organic compounds. The need for modification of the inner wall surface of PDMS channels may often be necessary, and in this paper, we describe an easy and effective method using the amine-containing polymer PolyE-323 to deactivate both fused-silica and PDMS surfaces. The adsorption of selected peptides to untreated surfaces was compared to PolyE-323-modified surfaces, using both radionuclide imaging and capillary electrophoresis experiments. The polyamine modification displayed a substantially reduced adsorption of three hydrophobic test peptides compared to the native PDMS surface. Filling and storage of aqueous solution were also possible in PolyE-323-modified PDMS channels. In addition, hybrid microstructures of fused silica and PDMS could simultaneously be deactivated in one simple coating procedure.