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Leifer R Juzdan ZR Kelly WR Fassett JD Eberhardt KR 《Science (New York, N.Y.)》1987,238(4826):512-514
The nuclear reactor from the Soviet radar reconnaissance satellite, Cosmos-1402, reentered the earth's atmosphere on 7 February 1983 and disintegrated over the South Atlantic Ocean. The reactor was powered by approximately 50 kilograms of uranium-235 ((235)U). In an effort to determine the fate of the reactor core, a series of aerosol samples were collected at altitudes between 27 and 36 kilometers in the Northern Hemisphere approximately 1.1 years later by high-altitude balloons. At an altitude of 36 kilometers a 53 +/- 20 percent excess in the (235)U concentration was measured. The total excess of (235)U in the stratosphere was calculated to be 44 +/- 15 kilograms. 相似文献
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Plasma heparin values and hemostasis in equids after subcutaneous administration of low-dose calcium heparin 总被引:1,自引:0,他引:1
Different doses of heparin were given to equids SC to establish 0.05 to 0.20 U of heparin/ml of plasma. Plasma heparin values and antithrombin III activities were assayed, using chromogenic substrate methods. Activated partial thromboplastin and thrombin times were determined, using conventional coagulation assays. Tests were run every hour (or every 2 hours for antithrombin III) for 12 hours from 5 groups of 5 equids each after single injection of 40, 60, 80, 100, or 125 U of calcium heparin/kg of body weight and from 11 equids after injection of 150 U of calcium heparin/kg. The smaller dose (40 U/kg) did not or only insufficiently increase plasma heparin values. After 150 U of heparin/kg, plasma heparin concentrations were increased for 11 hours and were significantly (P = 0.05) increased between postadministration hours 2 and 7. The desired range beyond 0.05 U of heparin/ml was achieved between postadministration hours 2 and 6. Antithrombin III, activated partial thromboplastin time, and thrombin time were not significantly affected by any heparin dose. In cumulative studies, 2 equids were given 150 U of heparin/kg 7 times at 12-hour intervals. After the 3rd injection, a mean plasma concentration of 0.20 U of heparin/ml was achieved; after the 7th injection, the mean concentration was 0.22 U of heparin/ml. Four equids were given 150 U of heparin/kg initially, followed by 125 U of heparin/kg 6 times at 12-hour intervals. After the 3rd injection, a maximal plasma heparin concentration of 0.12 U of heparin/ml was achieved; after the 7th injection, the mean concentration was 0.18 U of heparin/ml. Repeated SC heparin injections caused moderate swelling at the injection sites.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
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Florian Wichern Elmar Eberhardt Jochen Mayer Rainer Georg Joergensen Torsten Müller 《Soil biology & biochemistry》2008,40(1):30-48
The objective of the present review was to present the current knowledge on nitrogen (N) rhizodeposition, including techniques for 15N labelling of agricultural plants, amounts of N rhizodeposition and its fate in soil. Rhizodeposition is the process of release of organic and inorganic compounds from living plant roots. It is often quantified in terms of carbon (C) and less often as N derived from rhizodeposition (NdfR). Rhizodeposition of N can be estimated by labelling plants with 15N and following its fate in soil. Most methods used for labelling plants with 15N can only be applied after appearance of the first leaf and only allow pulse or multiple pulse labelling. Only the split-root technique and the application of gaseous 15N allow continuous labelling. All methods available at present have their flaccidities mostly due to the fact that the application of N is not following its physiological pathway of assimilation or by using artificial conditions. In the studies reviewed, amounts of N rhizodeposits ranged from 4% to 71% of total assimilated plant N. In legumes the median was 16% and in cereals it was 14%. Rhizodeposits were 15–96% of the below-ground plant biomass (BGP). In legumes the median was 73% and in cereal it was 57%. The high variability of these results shows the need for more investigations on N rhizodeposition looking especially on the factors influencing the amounts released in different plant species under field conditions. 相似文献
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Eberhardt Diogo Marchão Robélio Quiquampoix Hervé Le Guernevé Christine Ramaroson Volaniaina Sauvadet Marie Muraoka Takashi Becquer Thierry 《Journal of Soils and Sediments》2021,21(2):1024-1037
Journal of Soils and Sediments - Phosphorus (P) is often the main limiting factor for plant growth in highly weathered tropical soils. Phosphate use efficiency and crop yields could be increased in... 相似文献
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Eberhardt MV Kobira K Keck AS Juvik JA Jeffery EH 《Journal of agricultural and food chemistry》2005,53(19):7421-7431
Chemical measures of antioxidant activity within the plant, such as the oxygen radical absorbance capacity (ORAC) assay, have been reported for many plant-based foods. However, the extent to which chemical measures relate to cellular measures of oxidative stress is unclear. The natural variation in the phytochemical content of 22 broccoli genotypes was used to determine correlations among chemical composition (carotenoids, tocopherols and polyphenolics), chemical antioxidant activity (ORAC), and measures of cellular antioxidation [prevention of DNA oxidative damage and of oxidation of the biomarker dichlorofluorescein (DCFH) in HepG2 cells] using hydrophilic and lipophilic extracts of broccoli. For lipophilic extracts, ORAC (ORAC-L) correlated with inhibition of cellular oxidation of DCFH (DCFH-L, r = 0.596, p = 0.006). Also, DNA damage in the presence of the lipophilic extract was negatively correlated with both chemical and cellular measures of antioxidant activity as measured by ORAC-L (r = -0.705, p = 0.015) and DCFH-L (r = -0.671, p = 0.048), respectively. However, no correlations were observed for hydrophilic (-H) extracts, except between polyphenol content and ORAC (ORAC-H; r = 0.778, p < 0.001). Inhibition of cellular oxidation by hydrophilic extracts (DCFH-H) and ORAC-H were approximately 8- and 4-fold greater than DCFH-L and ORAC-L, respectively. Whether ORAC-H has more biological relevance than ORAC-L because of its magnitude or whether ORAC-L bears more biological relevance because it relates to cellular estimates of antioxidant activity remains to be determined. Chemical estimates of antioxidant capacity within the plant may not accurately reflect the complex nature of the full antioxidant activity of broccoli extracts within cells. 相似文献
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Volcanic glasses collected on the rim of Shorty Crater in the Apollo 17 area were formed 3.63 x 10(9) years ago. The amounts of xenon-136 produced by neutron-induced fission of uranium-235 indicate that the glasses resided on the lunar surface for about 38 million years before they were deeply buried. The glass spherules were reexcavated by the impact that formed Shorty Crater 17 million years ago, and remained undisturbed until they were collected. 相似文献
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The circumstellar silicon carbide (SiC) grain X57 from the Murchison meteorite contains large amounts of radiogenic calcium-44 (20 times its solar system abundance) and has an anomalous silicon isotopic composition, different from other circumstellar SiC grains. Its inferred initial 44Ti/Si and 44Ti/48Ti ratios are 1.6 x 10(-4) and 0.37. In addition, it contains radiogenic magnesium-26; the inferred initial 26Al/27Al ratio is 0.11. The isotopic and elemental data of X57 can be explained by selective mixing of matter from different zones of a typical type II supernova of 25 solar masses during its explosion. The high 44Ti/Si ratio requires contributions from the innermost nickel zone of the supernova to the SiC condensation site, as similarly suggested by astronomical observations. 相似文献
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Mark Alexander Butler Joseph Dahlen Thomas L. Eberhardt Cristian Montes Finto Antony Richard F. Daniels 《Annals of Forest Science》2017,74(1):20