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Stability of Perovskite (MgSiO3) in the Earth's Mantle 总被引:1,自引:0,他引:1
SK Saxena LS Dubrovinsky P Lazor Y Cerenius P Haggkvist M Hanfland J Hu 《Science (New York, N.Y.)》1996,274(5291):1357-1359
Available thermodynamic data and seismic models favor perovskite (MgSiO3) as the stable phase in the mantle. MgSiO3 was heated at temperatures from 1900 to 3200 kelvin with a Nd-YAG laser in diamond-anvil cells to study the phase relations at pressures from 45 to 100 gigapascals. The quenched products were studied with synchrotron x-ray radiation. The results show that MgSiO3 broke down to a mixture of MgO (periclase) and SiO2 (stishovite or an unquenchable polymorph) at pressures from 58 to 85 gigapascals. These results imply that perovskite may not be stable in the lower mantle and that it might be necessary to reconsider the compositional and density models of the mantle. 相似文献
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Ullmann D Krause G Knabner D Weber H Beutin L 《Journal of veterinary medicine. B, Infectious diseases and veterinary public health》2005,52(2):82-87
The presence of potentially human pathogenic strains of Aeromonas was investigated in 84 samples of seafood which were purchased from retail traders in Berlin, Germany in spring 2000. A total of 134 Aeromonas strains were isolated on selective [GSP agar and Aeromonas (Ryan) agar] and unselective (standard count agar and enterohaemolysin agar) media from 27 (32.1%) of the samples and were classified as Aeromonas hydrophila (67.9%), A. caviae (26.1%) and A. sobria (6.0%) by biotyping. Thirteen (48.1%) of the 27 positive samples contained more than one species of Aeromonas. Production of haemolysins on enterohaemolysin agar was found with 132 (98.5%) of the strains at 28 degrees C and with 130 strains (97.0%) at 37 degrees C growth temperature. Vero cytotoxins were produced by 99 (73.9%) of the strains when grown at 28 degrees C but only by 24 of the strains (17.9%) at 37 degrees C. The latter strains were identified as A. hydrophila (n = 22) and A. sobria (n = 2) which came from 17 (20.2%) samples of raw seafood and from ready-to-eat salted herring 'Matjes' products. Cytotoxin-encoding genes for aerolysin (aer) and haemolysin A (hlyA) were investigated by PCR. Aer and hlyA genes were detected in both, strains which produced toxins only at 28 degrees C and strains which produced toxins at 37 degrees C. Our data indicate that raw seafood and ready-to-eat fish products can harbour potential human pathogenic, cytotoxin producing Aeromonas strains. 相似文献
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Silva A. F. Farias P. J. A. Silva M. L. C. R. Araújo Júnior J. P. Malossi C. D. Ullmann L. S. Costa D. F. Higino S. S. S Azevedo S. S. Alves C. J. 《Tropical animal health and production》2019,51(1):43-47
Tropical Animal Health and Production - Although some studies in sheep have indicated leptospire colonization of the genital tract, further studies are needed to clarify the role of genital... 相似文献
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Aupperle H Garbade J Ullmann C Krautz C Barten MJ Dhein S Schoon HA Gummert FJ 《Journal of veterinary medicine. A, Physiology, pathology, clinical medicine》2007,54(5):230-237
Preserved ultrastructure is an important precondition for functional regeneration after heart transplantation. We investigated the effectiveness of a newly developed modified Langendorff system in extracorporeal heart perfusion. (Experiment I) Cardioplegia and cold ischaemia were performed in six pigs. Hearts were connected to a modified Langendorff system, and perfused with leucocyte depleted autologous blood. (Experiment II) The untreated hearts of three healthy pigs served as controls. Forty-seven myocardial biopsies at different timepoints (I: n = 29, II: n = 18) were investigated by transmission electronmicroscopy. Cardioplegia/hypothermia (I) induced mild-to-moderate mitochondrial swelling, mild myofibrillar degeneration in cardiomyocytes and moderate endothelial oedema. After 4 h reperfusion cardiomyocytes showed moderate myofibrillar and mild sarcolemmal damage. Moderate endothelial degeneration, mild interstitial oedema and haemorrhages appeared. Untreated hearts (II) showed severely damaged mitochondria and nuclei after 30 min while the myofibrillar structure remained unaffected until 4 h later. This is a promising model for extracorporeal heart perfusion. However, ultrastructural findings indicated that some necessary modifications to prevent cellular damages during reperfusion were needed. 相似文献
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Langoni H Greca H Guimarães FF Ullmann LS Gaio FC Uehara RS Rosa EP Amorim RM Da Silva RC 《Veterinary parasitology》2011,177(1-2):50-54
Neosporosis and toxoplasmosis are two important infections in young and adult sheep, leading to low production and abortion. This study aimed to determine the frequency of antibodies to Toxoplasma gondii and Neospora caninum in sheep from the eastern region of S?o Paulo State, Brazil. Serum samples (382) were collected from the sheep and assayed for T. gondii through modified agglutination test (MAT) and indirect fluorescent antibody test (IFAT), and for N. caninum antibodies, through IFAT, with cut-off titers equal to 16 (T. gondii) and 25 (N. caninum). All frozen samples were sent to the Center for Zoonoses Research (NUPEZO), Department of Veterinary Hygiene and Public Health (DHSVP), FMVZ, UNESP, for serological tests. A total of 71/382 (18.6%) samples reacted to T. gondii, especially at titers 16 (28; 39.4%), 64 (15; 21.1%), 256 (21; 29.6%) and 1024 (6; 8.5%) by MAT, and 16 (34; 47.9%), 64 (18; 25.4%), 256 (14; 19.7%) and 1024 (5; 7%) by IFAT. As regards N. caninum, 49/382 (12.8%) samples reacted at titers 25 (17; 34.7%), 50 (11; 22.5%), 100 (11; 22.5%), and ≥ 200 (10; 20.4%). These animals presented infection but no clinical signs. Six and ten animals had high titers for toxoplasmosis and neosporosis. No significant association was observed between antibodies for both parasites (P=0.535) according to Fisher's exact test, and no correlation was found between T. gondii (MAT) and N. caninum antibody titers (r=-0.0068; P=0.895), T. gondii (IFAT) and N. caninum antibody titers (r=-0.0025; P=0.961). Thus, T. gondii and N. caninum infections were observed in farms located in S?o Paulo State, where sheep play an important economical role for the national and regional business. 相似文献
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LS Nind 《Australian veterinary journal》2019,97(9):362-364
The Tripartite collaboration (World Health Organization, the Food and Agriculture Organisation of the United Nations, and the World Organisation for Animal Health) produced two documents for consultation with Member Countries in 2017 ‐ Monitoring and Evaluation of the Global Action Plan on Antimicrobial Resistance: Proposed approach and the Global Framework for Development & Stewardship to Combat Antimicrobial Resistance: Draft Roadmap. These documents intend to support a strategic whole‐of‐system approach towards the World Health Organization's Global Action Plan on Antimicrobial Resistance. This paper outlines the recent thinking in antimicrobial stewardship being developed by the major international organisations involved with mitigating global antimicrobial resistance. The directions being set in key frameworks will need to be considered by Australian stakeholders as their own antimicrobial stewardship approaches and activities are formulated. 相似文献
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