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Burlingame AL Calvin M Han J Henderson W Reed W Simoneit BR 《Science (New York, N.Y.)》1970,167(3918):751-752
The carbon concentration in Apollo 11 lunar fine material is of the order of 200 ppm. By far the largest single amount of this carbon appears to be in carbon monoxide. Some of this seems to be in the form of gas bubbles in the glass spheres, but most of it could be in some complex form other than gas. This result would be consistent with the idea that most of the fines passed through a high temperature and that the carbon was oxidized by mineral oxides at that time. 相似文献
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M. A. Mazurek B. R. T. Simoneit L. J. Standley D. Friedman C. Beeman 《Water, air, and soil pollution》1987,36(1-2):171-192
Extracts of particulate organic matter were examined for discrete rainfall events from metropolitan Los Angeles, California, using an in situ filtration technique. Filtration efficiency was 98 % for the collection of extractable organic C associated with particles having nominal diameters greater than 0m22 μm Organic background levels of less than 260 ng per sample were determined. Rainwater particle samples were extracted with repeated hexane and benzene: isopropanol (2: 1) solvent additions using ultrasonic agitation. Extract mixtures were quantified by high-resolution gas chromatography (HRGC) and were adjusted for component losses with perdeuterated recovery standards. Yields for the neutral fractions ranged from 130 to 669 μg with flux rates corresponding to 371 to 1097μg m?2 day?1. Aliquots of the neutral solvent extracts were derivatized with diazomethane to convert acidic hydroxy and carboxylic acid groups to the respective methyl ether and methyl ester analogs. This step produced increased yields of 8 to 188 %, and resulted in yields for the acid +neutral extracts that ranged from 374 to 8681μg with flux rates of 591 to 2343 μg m?2 day?1. Source identification was conducted by high-resolution gas chromatography/mass spectrometry (HRGC/MS) analyses. Molecular analyses indicated major anthropogenic contributions from petroleum and combustion sources, and for some samples, the significant input of microbial lipid components as well. Minor amounts of vascular plant waxes were also present in most cases. These mixed inputs of both anthropogenic and biogenic materials compared closely with previous source determinations for carbonaceous aerosol particles in the Los Angeles air basin. 相似文献
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Simoneit C Heuwieser W Arlt S 《Tier?rztliche Praxis. Ausgabe G, Grosstiere/Nutztiere》2012,40(3):186-192
The veterinary practitioner should base decisions concerning diagnostic procedures and treatments in practice on recent, valid and clinically relevant information. He may rely on journal papers, colleagues, the internet or other sources. It is a great challenge to find appropriate information in a reasonable time. Furthermore, the practitioner has to judge the information regarding its actuality and validity. Ideally, such information should provide a high level of evidence. This means that this information is more likely to be "correct". Good information can be obtained through high quality trials, such as randomized and blinded controlled clinical trials. Universities, publishers and professional organizations should promote editing of scientific information to support practitioners in decision making. 相似文献
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Schrader H Kelts K Curray J Moore D Aguayo E Aubry MP Einsele G Fornari D Gieskes J Guerrero J Kastner M Lyle M Matoba Y Molina-Cruz A Niemitz J Rueda J Saunders A Simoneit B Vaquier V 《Science (New York, N.Y.)》1980,207(4436):1207-1209
During Deep Sea Drilling Project-International Program of Ocean Drilling leg 64, December 1978 to January 1979, the initial test of the Deep Sea Drilling Project's hydraulic piston corer obtained an almost undisturbed section from a 152-meter hole into the sediments of the oxygen minimum zone at a depth of 655 meters along the Guaymas slope in the central Gulf of California. The section records variations in climate, productivity, and circulation for more than 250,000 years of Late Pleistocene to Holocene history with recordings of seasonal variations in these parameters in the laminated sections. 相似文献
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Numerous saturated and aromatic hydrocarbons, but not polar compounds, originating from plants and microorganisms (biomarkers) have been reported in sediments, coals, and petroleum. Here we describe natural product terpenoids found in two fossil conifers, Taxodium balticum (Eocene) and Glyptostrobus oregonensis (Miocene). A similar terpenoid pattern is also observed in extant Taxodium distichum. The preservation of characteristic terpenoids (unaltered natural products) in the fossil conifers supports their systematic assignment to the Cypress family (Cupressaceae sensu lato). The results also show that fossil conifers can contain polar terpenoids, which are valuable markers for (paleo)chemosystematics and phylogeny. 相似文献
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Organic combustion products generated by the lunar module descent engine, which burns a 1:1 mixture of unsymmetrical dimethylhydrazine fuel and nitrogen tetroxide oxidizer, have been analyzed. The major gaseous combustion products found were ammonia, water, carbon monoxide, nitrous oxide, oxygen, carbon dioxide, and nitric oxide. The minor products were acetylene, hydrogen cyanide, ethylene, formaldehyde, propadiene, ketene, cyanous acid, hydrazoic acid, various methylamines, acetaldehyde, methyl nitrite, formic acid, nitrous acid, butadiyne, nitrilohydrazines, nitromethane, and nitrosohydrazines with other oxidized derivatives of unsymmetrical dimethylhydrazine and hydrazine. The ion intensities of the various species in all mass spectra were estimated as the following concentrations: the gases (NH(3), H(2)O, CO, NO, O(2), CO(2), and NO(2)), 87.7 percent; compounds of C, H, and O, 6.0 percent; and compounds of C, H, and N (with traces of O), 5.8 percent. 相似文献
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Demineralized oil shale was oxidized with chromic acid, and C(14) to C(22) isoprenoid fatty acids were isolated and identified. The major components of the branched-chain acid fraction after successive 3-, 6-, and 15-hour oxidations are C(15) and C(16) branched-chain acids; C(17), C(19) (norphytanic acid), and C(20) (phytanic acid) were obtained in lower concentration; no C(18) product was obtained. Separations were effected by column and gas-liquid chromatography, and the structures of individual components were determined by high- and low-resolution mass spectrometry. 相似文献
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This study's objective was to determine respondents' inter-observer agreement on a detailed checklist to evaluate three exemplars (one case report, one randomized controlled study without blinding, and one blinded, randomized controlled study) of the scientific literature in the field of bovine reproduction. Fourteen international scientists in the field of animal reproduction were provided with the three articles, three copies of the checklist, and a supplementary explanation. Overall, 13 responded to more than 90% of the items. Overall repeatability between respondents using Fleiss's κ was 0.35 (fair agreement). Combining the "strongly agree" and "agree" responses and the "strongly disagree" and "disagree" responses increased κ to 0.49 (moderate agreement). Evaluation of information given in the three articles on housing of the animals (35% identical answers) and preconditions or pretreatments (42%) varied widely. Even though the overall repeatability was fair, repeatability concerning the important categories was high (e.g., level of agreement=98%). Our data show that the checklist is a reasonable and practical supporting tool to assess the quality of publications. Therefore, it may be used in teaching and practicing evidence-based veterinary medicine. It can support training in systematic and critical appraisal of information and in clinical decision making. 相似文献
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Oros Daniel R. Mazurek Monica A. Baham John E. Simoneit Bernd R. T. 《Water, air, and soil pollution》2002,137(1-4):203-233
The molecular compositions and alteration products of the major organic components in soils and litter subjected to controlled or wildfire burning, and subsequent erosion by rain and river transport have been determined by GC-MS. The major compound groups imparted to soils include n-alkanoic acids, n-alkanes, n-alkanols, phytosterols, and terpenoids. Biomarker tracer analysis indicates that organic compounds remain as internal lipid components of char and heavy particles and are deposited onto soil during wildfire and prescribed burning. The process of rain erosion and river transport releases some of these internal components into the surroundings where they are further subjected to biological alteration. The distributions and abundances ofhomologous compound series coupled with biomarker tracer analysis provides a chemical fingerprint which is useful for identifying the single or multiple plant species contributing organic matter by both thermal (burning) and biological processes. Such fingerprints are useful for tracking soils which are transported in the atmosphere by wind as suspended particles in dust storms and on land by rain erosion to rivers. 相似文献
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