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The aluminum borate whisker reinforced magnesium matrix composites (Al18B4O33w/Mg) were fabricated by pressure infiltration technique and extrusion-vacuum infiltration technique respectively to study the effect of extrusion forming on their mechanical behaviors. The microstructure of the composites was observed by scanning electron microscopy. The compressive strength was investigated and compared with that of the matrix alloy AZ91D. The results show that the extrusion forming could cause fracture of the wh...  相似文献   
2.
Niemenharju休息区位于欧洲E75高速公路上,该高速公路从欧洲南部的希腊一直延伸到欧洲北部的北开普.在漫长的驾驶之后,这里就成了过夜休息并欣赏自然的理想之地.休息区设立的灵感来自于周围的自然环境,因为该休息区毗邻一个美丽的大池塘和一个与科利马湖接壤的山脉(以芬兰语harju命名),该湖是冰河时代的遗迹.  相似文献   
3.
Fast food sold on the streets are good vehicle to transmit gastrointestinal diseases to consumers because they are highly manipulated. The vegetables are a good media for pathogens growth. Raw vegetables salads for hot dog sold in Maracay were studied. Total and fecal Coliforms and Staphylococcus sp. were quantified by the Most Probable Number Technique, Coliforms and Staphylococcus isolated were partially identified. Also the mould population was quantified and identified. Microbial growth was correlated with pH and acidity measurements. MPN/g of Total Coliforms was 1.44 x 10(5) and 4.57 x 10(4) for fecal Coliforms. E. coli was no detected. 87 isolated from the Coliforms were partially identified as Citrobacter freundii variety 1 (45.09% of the isolated), C. freundii variety II (21.57%), Enterobacter aerogenes variety I (17.65%) and E. aerogenes variety II (15.69%); Staphylococcus sp. 3.93 x 10(6) MPN/g and all of its isolated (52) were coagulase negative. The mould population was 4.5 x 10(4) ufc/g, Penicillium sp., Aspergillus, sp., Fusarium sp. were partially identified. The salads presented a pH of 5.92 and an acidity of 0.78 ml of NaOH.  相似文献   
4.
Ethylene/dodecene-1 and ethylene/butene-1/dodecene-1 copolymers were prepared and their polymerization reaction in heptane slurry was studied. The Ziegler–Natta catalyst was aluminium-activated TiCl3, and the cocatalyst was triethylaluminium. The dodecene-1 contents in the ethylene/dodecene-1 copolymers were less than 3 wt %. The dodecene-1 contents in terpolymers of ethylene, butene-1, and dodecene-1 ranged up to 10 wt %. The dependence of basic properties on composition of terpolymers was investigated.  相似文献   
5.
The articles appearing in the following section are condensations of papers presented at a round table discussion on the subject of “Copper Converter Refractory Practices”, sponsored by the Extractive Metallurgy Division of The Metallurgical Society. The discussion was held during the AIME Annual Meeting in New York City, February 1968. All deletions, and the omission of references, have been made solely because of space limitations, and should not be construed as reflections upon the individual authors or their papers.  相似文献   
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The carbon isotopic composition (delta13C) of plants can reveal the isotopic carbon content of the atmosphere in which they develop. The delta13C values of air and plants depend on the amount of atmospheric fossil fuel CO2, which is chiefly emitted in urban areas. A new indicator of CO2 pollution is tested using the delta13C variation in a C4 grass: Eleusine indica. A range of about 4 per thousand delta units was observed at different sites in Cotonou, the largest city in the Republic of Benin. The highest delta13C values, from -12 per thousand to -14 per thousand, were found in low traffic zones; low delta13C values, from -14 per thousand to -16 per thousand, were found in high traffic zones. The amount of fossil fuel carbon assimilated by plants represented about 20% of the total plant carbon content. An overall decrease in plant delta13C values was observed over a four-year monitoring period. This decrease was correlated with increasing vehicle traffic. The delta13C dataset and the corresponding geographical database were used to map and define zones of high and low 13C-depleted CO2 emissions in urban and sub-urban areas. The spatial distribution follows dominant wind directions, with the lowest emission zones found in the southwest of Cotonou. High CO2 emissions occurred in the north, the east and the center, providing evidence of intense anthropogenic activity related to industry and transportation.  相似文献   
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