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839 results on '"Jonsson, S"'

230. High-temperature mechanical- and fatigue properties of cast alloys intended for use in exhaust manifolds.

Author

Ekström, M. and Jonsson, S.

Subjects
*HIGH temperature metallurgy, *MECHANICAL properties of metals, *METAL fatigue, *METAL castings, *MANIFOLDS (Engineering), *DIESEL motor exhaust gas
Abstract

In the present work materials for use in exhaust manifolds of heavy-duty diesel engines were tested in air from 20 to 1000 °C with respect to mechanical properties. Two cast irons, SiMo51 and Ni-resist D5S, four austenitic cast steels, HF, A3N, HK30 and HK-Nb, and one ferritic cast steel, 1.4509 were studied. The experimental work included thermal conductivity, thermal expansion, uniaxial stress–strain testing, low-cycle fatigue testing up to 30,000 cycles and fractography. Below 500 °C, SiMo51 is superior. At higher temperatures, a transition from elastic to plastic strain dominance was observed for the cast irons, reducing their performance. Carbide-forming elements increase heat conductivity and result in a dendrite-like fracture surfaces during fatigue testing. The austenitic steels are superior only at higher temperatures. [ABSTRACT FROM AUTHOR]

Published
2014
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231. Influence of Cr and Ni on High-Temperature Corrosion Behavior of Ferritic Ductile Cast Iron in Air and Exhaust Gases.

Author

Ekström, M., Szakalos, P., and Jonsson, S.

Subjects
CHROMIUM, NICKEL, CORROSION & anti-corrosives, NODULAR iron, WASTE gases, EMISSIONS (Air pollution), DETERIORATION of metals
Abstract

Due to an expected temperature increase of the exhaust gases in heavy-duty engines in order to meet future emission regulations, there is a need to develop materials that can operate at higher temperatures. The exhaust manifold in the hot end of the exhaust system is specifically affected since the most common material today, SiMo51, is already operating close to its limits. Accordingly, the effects of Cr and Ni-additions on the high-temperature corrosion resistance of this material in air and exhaust gases were examined. It was found that the addition of 0.5 and 1 wt% Cr improved the oxidation resistance in air at 700 and 800 °C by the formation of an SiO 2 barrier layer as well as a Cr-oxide at the oxide/metal interface. However, no Cr-oxide was detected after exposure to exhaust gases, probably due to a water vapor-assisted evaporation of Cr from the oxide. The addition of 1 wt% Ni resulted in a deteriorated SiO 2 barrier layer and reduced oxidation resistance. [ABSTRACT FROM AUTHOR]

Published
2013
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232. Further studies on the tuned photoinitiators

Author

Nagarajan, R, primary, Bowers, JS, additional, Wu, Z, additional, Cui, H, additional, Bao, R, additional, Jonsson, S, additional, McCartney, R, additional, Pittman, CU, additional, Cao, L, additional, and Ran, R, additional

Published
1999
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246. Region-specific depression of striatal activity in Wistar rat by modest ethanol consumption over a ten-month period.

Author

Adermark, L., Jonsson, S., Söderpalm, B., and Ericson, M.

Subjects
*MENTAL depression, *LABORATORY rats, *ETHANOL, *NUCLEUS accumbens, *DOPAMINE, *TARGETED drug delivery, *DRUG abuse, *PHYSIOLOGY
Abstract

The nucleus accumbens (nAc) is the primary target for the mesolimbic dopamine system and a key brain region for the reinforcing effects displayed by drugs of abuse, including ethanol. During the transition from recreational to compulsive consumption of reinforcing drugs, however, the dorsal striatum seems to be recruited. Understanding how synaptic activity is altered in a sub-region specific manner in the striatum during the course of long-term drug consumption thus could be essential for understanding the long-lasting changes produced by addictive substances, including ethanol. Here we evaluated synaptic activity in the dorsolateral striatum (DLS) and ventral striatum (nucleus accumbens, nAc) of singlehoused Wistar rats consuming water, or water and ethanol, for up to 10 months. Even though ethanol intake was moderate, it was sufficient to decrease input/output function in response to stimulation intensity in the DLS, while recorded population spike (PS) amplitudes in the nAc were unaffected. Striatal disinhibition induced by the GABAA receptor antagonist bicuculline had a slower onset in rats that had consumed ethanol for 2 months, and was significantly depressed in slices from rats that had consumed ethanol for 4 months. Bicuculline-induced disinhibition in the nAc, on the other hand, was not significantly altered by long-term ethanol intake. Changes in PS amplitude induced by taurine or the glycine receptor antagonist strychnine were not significantly altered by ethanol in any brain region. Even though input/output function was not significantly affected by age, there was a significant decline in antagonistinduced disinhibition in brain slices from aged rats. The data presented here suggest that even modest consumption of ethanol is sufficient to alter neurotransmission in the striatum, while synaptic activity appears to be relatively well-preserved in the nAc during the course of long-term ethanol consumption. [ABSTRACT FROM AUTHOR]

Published
2013
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