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《Comptes Rendus Geoscience》2014,346(3-4):53-63
Natural organic matter (OM) is widespread in terrestrial ecosystems and it plays a major role in the global carbon cycle. Despite this high environmental importance, its characterization at the molecular level remains unsatisfactory, especially when the macromolecular OM is concerned. Such a characterization is challenging because of the diversity and heterogeneity of OM, but it is of prime importance to derive OM reactivity and, more generally, to model environmental processes in which natural OM is involved. This awareness led to a wealth of analytical developments, which are described in the present review. They include improvements of existing techniques, but also new approaches and concern spectroscopic tools along with chemical and thermal degradations. 相似文献
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Bacteria-infected turbots Scophthalmus maximus with septicaemia were examined between 2001 and 2004 in aspects of the conditions of disease occurrence, clinical syndromes and pathological changes. The phenotypic information of pathogenic bacteria was studied, including morphology, physiological and biochemical characteristics, and the mol% G C of the DNA. In addition, representative strains (S010623-1, LH031120-1) were selected for molecular identification by partial 16S rRNA gene sequencing. The results show that the isolates (LH031120-1 to LH031120-6, HT040308-1 to HT040308-6, HT040620-1 to HT040620-6) from three farms were identified as Edwardsiella tarda. The isolates (S010610-1 to S010610-10, S010623-1 to S010623-20) from one farm were identified as Listonella anguillarum. We conducted studies on the pathogenicity of isolates by artificial infection, and revealed all infected groups in morbidity and mortality. The septicaemia infected turbot showed a syndrome similar to that of the naturally infected fish. Antibiotic sensitivity showed that of 37 antimicrobial agents, E. tarda was sensitive to 27 agents, and L. anguillarum was sensitive to 21 agents. 相似文献
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非晶态镍硼酸盐的制备和表征 总被引：2，自引：2，他引：0
由摩尔比分别为1:2和1:8的六水氯化镍和硼砂反应得到两种镍硼酸盐样品1.25NiO·B_2O_3·4.5H_2O和NiO·B_2O_3·3.1H_2O。用XRD、TG-DSC、FT-IR和Raman等实验方法对其进行表征,样品为非晶态,确定了样品中的阴离子等,并结合化学分析结果近似确定了上述两种非晶态镍硼酸盐样品的结构组成式,前者为三元复盐,结构式为Ni[B_3O_3(OH)_5]·0.5Ni[B_2O(OH)_6]·Ni(OH)_2·4H_2O,后者结构式为Ni[B_2O(OH)_6]。 相似文献
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A. ALEXIS D. MAROT P. THOMAS Doctor-Engineer Laboratoire Genie Vivil Nantes Saint-Nazaire BP Saint-Nazaire France. Doctor Laboratoire Genie Vivil Nantes Saint-Nazaire BP Saint-Nazaire France. Professor Laboratoire Genie Vivil 《国际泥沙研究》2001,16(3)
l INTRODUCTIONTo ensure the long-term futhe of dams, the emPtying of storage reservoirs is often realised with tWoobjectives:'-periodic insPection of the sttucthe,-flushing oftalrials Which sedimatd within the reservoir.Both aims are lthely to cause the instability of sedhoent, and these displacements can induceenvirOInnenal distheances that have to be reduced to the Ininimum. This imPlies a good knowledge ofthese maerials and of the processes Which originated the disPlacements.The se… 相似文献
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K. Benzzi B. Tanouti M. Bouabdelli A. Alvarez J. L. Brianso F. Cherradi 《Environmental Geology》2006,51(2):275-282
Bab Agnaou is the most ancient gate sculpted in stone during the Almohad era (twelfth century). The petrographic and mineralogical studies were carried out in order to characterize the original materials of construction. So the ashlar is a calcareous mudstone, whereas the mortar is one with lime binder. The characterization of the ashlar’s degradation state, based on the mapping of the gate, permitted to highlight the evolution, the extension and the relation between the different weathering forms. Thus it proved to be possible to distinguish the weathering forms related to architecture and the provision of the blocks, from those related to infiltration of water. 相似文献
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In seismic interpretation and seismic data analysis, it is of critical importance to effectively identify certain geologic formations from very large seismic data sets. In particular, the problem of salt characterization from seismic data can lead to important savings in time during the interpretation process if solved efficiently and in an automatic manner. In this work, we present a novel numerical approach that is able to automatically segmenting or identifying salt structures from a post‐stack seismic data set with a minimum intervention from the interpreter. The proposed methodology is based on the recent theory of sparse representation and consists in three major steps: first, a supervised learning assisted by the user which is performed only once, second a segmentation process via unconstrained ?1 optimization, and finally a post‐processing step based on signal separation. Furthermore, since the second step only depends upon local information at each time, the whole process greatly benefits from parallel computing platforms. We conduct numerical experiments in a synthetic 3D seismic data set demonstrating the viability of our method. More specifically, we found that the proposed approach matches up to 98.53% with respect to the corresponding 3D velocity model available in advance. Finally, in appendixes A and B, we present a convergence analysis providing theoretical guarantees for the proposed method. 相似文献
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Temporal variability of dimethylsulfide and dimethylsulfoniopropionate in the Sargasso Sea 总被引：1，自引：0，他引：1
John W. H. Dacey Frances A. Howse Anthony F. Michaels Stuart G. Wakeham 《Deep Sea Research Part I: Oceanographic Research Papers》1998,45(12):2085-2104
Vertical profiles of dimethylsulfide (DMS) and β-dimethylsulfoniopropionate, particulate (pDMSP) and dissolved (dDMSP), were measured biweekly in the upper 140 m of the Sargasso Sea (32°10′N, 64°30′W) during 1992 and 1993. DMS and pDMSP showed strong, but different, seasonal patterns; no distinct intra-annual pattern was observed for dDMSP. During winter, concentrations of DMS were generally less than 1 nmol l−1 at all depths, dDMSP was less than 3 nmol l−1 and pDMSP was less than 8 nmol l−1. In spring, concentrations of both dDMSP and pDMSP rose, on a few occasions up to 20 nmol l−1 in the dissolved pool and up to 27 nmol l−1 in the particulate pool. These increases, due to blooms of DMSP-containing phytoplankton, resulted in only minor increases in DMS concentrations (up to 4 nmol l−1). Throughout the summer, the concentrations of DMS continued to increase, reaching a maximum in August of 12 nmol l−1 (at 30 m depth). There was no concomitant summer increase in dDMSP or pDMSP. The differences among the seasonal patterns of DMS, dDMSP, and pDMSP suggest that the physical and biological processes involved in the cycling of DMS change with the seasons. There is a correlation between the concentration of DMS and temperature in this data set, as required by some of the climate feedback models that have been suggested for DMS. A full understanding of the underlying processes controlling DMS is required to determine if the temperature-DMS pattern is of significance in the context of global climate change. 相似文献
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