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161.
Christophe Nguyen Fabienne Froux Sylvie Recous Thierry Morvan Christophe Robin 《Nutrient Cycling in Agroecosystems》2008,80(1):39-47
Repeated fertilisation of crops with manure commonly increases both the amount and the quality of soil organic matter, the
mineralisation of which strongly determines the availability of N to plants. In the rhizosphere, the microbial mineralisation/immobilisation
of N is enhanced due to rhizodeposition (release of organic compounds from roots). In this work, we studied N transformations
during incubation of maize root mucilage in soils that had been previously fertilized with composted pig manure or with ammonium
nitrate for 7 years. Our work revealed mucilage was rapidly mineralised (average half-life of 3 days), inducing a rapid N
immobilisation of 94 mg N g−1 of mucilage C, followed by a slow remineralisation. Fertilisation with manure induced a persistent stimulation of the soil
organic matter mineralisation, leading to an enhanced content of soil inorganic N (+23% in 58 days of incubation). Due to
this stimulation of microbial activity in the soil fertilized with manure, the decrease in inorganic N during the biodegradation
of mucilage lasted a shorter time as compared to the mineral fertilisation. However, the type of fertilisation did not significantly
change the amount of N immobilised. 相似文献
162.
Effect of the activation procedure on the performance of Mo/H-MFI catalysts for the non-oxidative conversion of methane to aromatics 总被引:1,自引:0,他引:1
Sharifah B. Derouane-Abd Hamid J. Ross Anderson Iver Schmidt Christophe Bouchy Claus J. H. Jacobsen Eric G. Derouane 《Catalysis Today》2000,63(2-4):461-469
The effect of pre-treatment on the performance of Mo/H-MFI zeolite catalysts applied to the non-oxidative conversion of methane to aromatics has been investigated. It is demonstrated that catalyst performance depends on activation conditions. Activation of the Mo-oxide/H-MFI precursor with an n-butane/hydrogen mixture results in higher catalyst stability and benzene selectivity which are tentatively attributed to the formation of the -MoC1−x carbide, with f.c.c. structure as revealed by XRD. 相似文献
163.
The quantitative distribution of volatile compounds in the skin, top mesocarp, middle mesocarp, bottom mesocarp, inner mesocarp, and outer mesocarp of a white-fleshed peach (cv. Maura) was investigated. Volatile compounds were extracted by liquid–liquid microextraction (LLME) and analyzed by GC–FID and GC–MS. The results showed that the levels of volatiles in skin were significantly higher than those observed in the other parts of the fruit, whereas top and bottom mesocarp were mainly discriminated by opposite concentrations in unsaturated lactones and C6-compounds. Distribution of lactones was also found to be different in skin and pulp according to their carbon chain length. Finally, the highest concentrations of benzaldehyde were found to be mainly located close to the stone suggesting that in peach this compound could be derived from enzymatic hydrolysis of amygdalin. 相似文献
164.
Claude Lucat Patrick Ginet Christophe Castille Hlne Debda Francis Mnil 《Microelectronics Reliability》2008,48(6):872-875
A new process derived from screen-printing technology and based on thick sacrificial layers has been developed in our laboratory for the fabrication of films partially released from the substrate. The sacrificial layer acts as a stable mechanical support during the firing of the active layer and is totally removed after the final thermal treatment of the sample. Fabrication of a copper electrothermal actuator was undertaken to demonstrate the efficiency of this simple, collective and low cost process. Passive components based on this new process include the fabrication of heating resistors, strain gauges and microchannels. Moreover, the process can also be used to facilitate the implementation of piezoelectric devices. 相似文献
165.
This work presents an attempt to describe the complex relationship between the development of the solidification microstructures
and buildup of microsegregation in spheroidal graphite (SG) cast irons by coupling an experimental investigation and a modeling
approach. Experimental characterization of microsegregation in cast iron was made by means of point counting microanalysis
along a grid. With this method, the differences of silicon distribution in alloys solidified in the stable system, the metastable
system, or in both systems were clearly evidenced. The distribution of manganese in alloy solidified in the stable system
was also investigated. It has been, in particular, observed that alloys solidified in the stable (respectively, metastable)
system present significant negative (respectively, positive) segregation of silicon, and that alloys solidified in both systems
are much less segregated. The solidification path of these alloys has been conveniently reproduced by means of predictions
made with a physical model accounting for the nature of the alloy, either hypoeutectic or hypereutectic, and for the sensitivity
to temperature and composition of the partition coefficient of alloying elements. 相似文献
166.
The Physical Activity Group Environment Questionnaire: An instrument for the assessment of cohesion in exercise classes. 总被引:1,自引:0,他引:1
The purpose of this study was to develop a cohesion inventory for exercise groups. Five projects were undertaken. In Projects 1 to 3, potential items were generated, content validity was established, and preliminary psychometric testing was carried out. In Project 4, concurrent validity was established. In Project 5, hypothesized relationships between cohesion and both adherence and self-efficacy were tested using older adult exercisers (N?=?60, average age?=?68.9 years, SD?=?6.1). Overall, the results of the 5 projects provided preliminary evidence of the utility of the Physical Activity Group Environment Questionnaire (PAGEQ) as a test of cohesion in exercise groups. The discussion centers on implications of the findings and the identification of future research necessary to continue the process of validation of the PAGEQ. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
167.
Evgenij Starikov Pavel Shiktorov Viktoras Gružinskis Alexandr Dubinov Vladimir Aleshkin Luca Varani Christophe Palermo Lino Reggiani 《Journal of Computational Electronics》2007,6(1-3):45-48
A possibility to develop the so called TASER (Terahertz-Amplification-by-the-Stimulated-Emission-of- Radiation) by using two-dimensional
(2D) electron transport in quantum well (QW) structures is investigated by Monte Carlo simulation of the optical-phonon-emission
assisted transit-time resonance (OPTTR) of 2D electrons in momentum space under the low lattice temperature. A considerable
extension of the frequency region for THz radiation generation (upto 5 times) when going from 3D- to 2D-case is predicted. 相似文献
168.
Nathalie Favrot Jacques Besson Christophe Colin Francis Delannay 《Journal of the American Ceramic Society》1999,82(5):1153-1161
Cold compaction (200-1900 MPa) and sintering (1250°-1350°C) of cermets based on WC-Co were experimentally studied using die compaction, cold isostatic pressing, sintering, and creep tests. Two different-sized WC powders were used. The cobalt content varied over a range of 10-30 wt%. Cold-compaction behavior has been described by using a Cam-Clay model. Die-wall friction was measured by using green powder compacts that had different aspect ratios. Friction coefficients were 0.28-0.85, depending on the WC particle size and cobalt content. Simple constitutive equations have been used to model the high-temperature behavior (sintering and creep). The constitutive equations were implemented in a finite-element program to model the compaction, ejection, and sintering of bilayer structures that had different cobalt contents. The model can represent the effect of die-wall friction on the average density, as well as deformation inside the green compact. Density gradients were generated; they were revealed during sintering, because the compact does not deform homogeneously. Simulation also can be used to evaluate deformations that are induced by sintering. 相似文献
169.
In the hierarchy of infinite graph families, rational graphs are defined by rational transducers with labelled final states. This paper proves that their traces are precisely context-sensitive languages and that this result remains true for synchronized rational graphs.Received: 17 December 2003, Published online: 27 December 2004 相似文献
170.
Jean-Luc Loizeau Michel Pardos Fabrice Monna Christophe Peytremann Laurence Haller Janusz Dominik 《Lakes & Reservoirs: Research and Management》2004,9(1):53-63
The Bay of Vidy is the most contaminated area of Lake Geneva, Switzerland, as a result of the release of treated and untreated waste water from the municipal sewage treatment plant of the city of Lausanne and its surroundings. The reconstruction of the historical deposition of heavy metals in the sediment of the bay has been performed by the analysis of several dated (radiocaesium) sediment cores. The presence of sewage‐derived contaminants in the Bay of Vidy since the beginning of the sewage treatment plant's operations in 1964 is clearly observed, when a sharp increase in heavy metal contents is recorded, with maximum concentrations of cadmium, copper, zinc and lead occurring between the late 1960s and early 1970s. Despite considerable improvement in recent times, the present concentrations of the investigated heavy metals in sediments of the Bay of Vidy are still higher than concentrations measured at the centre of the lake, the latter close to Lake Geneva's natural background values. It is concluded that the quantity of heavy metals deposited in the bay is considerable and, because of sediment instability, will constitute a potential hazard for biota. 相似文献