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- Das, D. K., et al.
(author)
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Microstructural degradation of plain and platinum aluminide coatings on superalloy CM247 during isothermal oxidation
- 1999
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In: Materials Science and Technology. ; 15:10, s. 1199-1208
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Journal article (peer-reviewed)abstract
- Isothermal oxidation at 1100°C of a high activity plain aluminide coating and a platinum aluminide coating, developed by the pack cementation technique, on cast nickel base superalloy CM247 has been carried out with the primary objective of systematically understanding the coating degradation process during oxidation. While the weight gains during oxidation for both plain aluminide and platinum aluminide coatings follow parabolic kinetics from the very beginning of oxidation exposure, the bare alloy was seen to exhibit a considerably long initial transient oxidation period (∼20 h), beyond which the parabolic law was followed. The parabolic rate constant for the platinum aluminide coating was found to be nearly two orders of magnitude lower than that for the plain aluminide coating. Alumina was identified as the only oxide phase that formed on both plain aluminide and platinum aluminide coatings during most of the oxidation exposure, although NiAl2O4 was also found in the case of the plain aluminide coating beyond ∼200 h. The oxide layer on the bare alloy, however, was found to consist of Al2O3, Cr2O3, and NiAl2O4. The microstructural degradation of both the plain aluminide and platinum aluminide coatings during oxidation was seen to occur in three distinct stages which, however, differed for each coating. This stagewise degradation, which involves final obliteration of the interdiffusion layer in each case, is discussed in detail. © 1999 IoM Communications Ltd.
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- Ehrnström, Roy, et al.
(author)
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An experimental study of gastric stump carcinoma in Wistar rats
- 1995
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In: APMIS : acta pathologica, microbiologica, et immunologica Scandinavica. - 1600-0463. ; 103:12, s. 878-884
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Journal article (peer-reviewed)abstract
- The risk of gastric stump carcinoma is increased 15-20 years after gastric resection for benign disease. Reflux of duodenal juice, bacterial overgrowth and formation of N-nitroso compounds are possible etiological factors. There is a geographical variation in the incidence of gastric cancer, possibly explained by differences in food intake. Experimentally it is possible to induce gastric stump carcinoma in rats without the addition of exogenous carcinogens. The aim of this study was: 1) to find the incidence of gastric carcinoma in rats subjected to BII resection and followed for 10 months, and 2) to examine if acetic acid, a common dietary factor, could influence the development of gastric carcinoma. Amongst BII-operated male Wistar rats, infiltrating carcinoma was found in 5/20 on a normal diet and in 5/24 exposed to acetic acid (NS). Benign mucosal changes were seen in 12/20 and 16/24 respectively (NS). With the exception of a profound inflammation in one sham-operated animal, no mucosal pathological changes were found in 24 sham-operated and 24 control animals where no operation was performed.
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- Ottersten, Björn, 1961-, et al.
(author)
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Spectrally efficient high capacity wireless communication systems with spatio-temporal processing
- 1998
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Patent (pop. science, debate, etc.)abstract
- A wireless system includes a network of base stations for receiving uplink signals transmitted from a plurality of remote terminals and for transmitting downlink signals to said plurality of remote terminals using a plurality of channels. A plurality of antenna elements at each base station receives uplink signals, and a plurality of antenna elements at each base station for transmits downlink signals. A signal processor at each base station is connected to the receiving antenna elements and to the transmitting antenna elements for determining spatio-temporal signatures. Spatio-temporal multiplexing and demultiplexing functions are provided for each remote terminal antennae for each channel, and a multiple base station network controller optimizies network performance, whereby communication between the base stations and the plurality of remote terminals in each of the channels can occur simultaneously.
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- Ronquist, F, et al.
(author)
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Phylogeny of the Hymenoptera: A cladistic reanalysis of Rasnitsyn's (1988) data
- 1999
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In: ZOOLOGICA SCRIPTA. - : BLACKWELL SCIENCE LTD. - 0300-3256. ; 28:1-2, s. 13-50
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Journal article (other academic/artistic)abstract
- The hypothesis of higher-level relationships among extinct and extant hymenopterans presented by Rasnitsyn in 1988 is widely cited but the evidence has never been presented in the form of a character matric. or analysed cladistically. We review Rasnitsyn'
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