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排序方式: 共有1266条查询结果,搜索用时 15 毫秒
91.
Richard Marchal Isabelle Tabary Michel Valade Dominique Moncomble Laurence Viaux Bertrand Robillard Philippe Jeandet 《Journal of the science of food and agriculture》2001,81(14):1371-1378
Qualitative effects of Botrytis cinerea infection were studied by comparing the foaming properties of Champagnes obtained from healthy grapes with those from grapes infected by B cinerea. This is of particular interest when it is considered that the foaming properties of Champagne wines are important in terms of product attractiveness for the consumer. Experiments using artificial viewing equipment clearly showed the dramatic effects on Champagne foam characteristics when grape berries were highly infected. The speed at which liquid separated from the foam (expressed as liquid height LS) in the glass depended largely on the level of infection for Chardonnary and Pinot noir wines (+268% for Chardonnary wines at 40% infection and +627% for Pinot noir wines at 20% infection). B cinerea infection reduced the time (LT) at which liquid first appeared in the glass; for Pinot noir wines an infection level of 20% caused very rapid drainage. The time of pouring (PT, ie the time to fill the glass under controlled conditions) also diminished considerably at an infection level of 20% for both Pinot noir and Pinot meunier wines (?74 and ?58% respectively). Mouldiness considerably altered the foam height observed 80 s (H80) after the start of pouring (?83% for Pinot noir and ?89% for Pinot meunier at 20% infection). Champagne foamability was also quantified using a sparging technique to standardise effervescence. Foamability suffered considerably (?60 to ?65%) when the B cinerea infection level was 20% as compared to control Champagnes. All wines studied had low and very similar protein contents. Differences in the concentrations of these compounds, which are generally implicated in the formation of foam in sparkling wines, could not explain the differences in Champagne foaming properties observed here. © 2001 Society of Chemical Industry 相似文献
92.
Ghislain Oudinet Laurence Aufore Marie-Jeanne Gotta G. Chiarelli 《Journal of Nuclear Materials》2008,375(1):86-94
A better understanding of MOX fuel in-pile behaviour requires a very detailed characterization of the Pu distribution in the pellet before and after irradiation. Electron probe microanalysis (EPMA) can be used to determine the distributions of chemical elements with a spatial resolution of 1 μm. This paper describes the development of X-ray microanalysis techniques to produce semi-quantitative ‘maps’ of plutonium concentrations in order to rapidly characterize large areas of the fuel microstructure (1 mm2) with reasonable accuracy. A new segmentation technique based on statistical compatibility is then proposed, so as to finely describe the MIMAS MOX fuel microstructure. Two materials were finely characterized to demonstrate the reliability of this new method. In each case, the results demonstrate the good and reliable accuracy of this new characterization methodology. The analysis method used is currently able to identify three so-called phases (Pu-rich agglomerates, a coating phase and uranium-rich agglomerates), as well as to quantify the plutonium distribution and the plutonium content of these three phases. The impact of the fabrication process on the microstructure can be seen both in the surface distribution variations of the plutonium and in the local plutonium content variations. 相似文献
93.
Laurence E. Sheehan 《Information Systems Management》2000,17(3):1-12
When making the decision to hire one of several equally qualified candidates, IS managers fall back on their instincts and choose the candidate that “feels right.” They rely on personal chemistry, which is one of the variables in the hiring equation. Other equally important elements are: aptitude, attitude, and motivational factors. 相似文献
94.
Laurence Ponsonnet Mirela Boureanu Nicole Jaffrezic Ali Othmane Corinne Dorel Philippe Lejeune 《Materials science & engineering. C, Materials for biological applications》2008,28(5-6):896-900
The development of surface-associated layers of matrix-embedded microbial populations, called biofilms, is a serious problem in many medical and industrial settings. These contaminations are difficult to eradicate because of the high resistance level acquired by the cells in their particular environment. From the very beginning of the colonization process, modifications of gene expression are observed and could, at least partially, explain biofilm resistance. In order to develop anti-biofilm molecules and surface treatments, it is of pivotal importance to identify the physico-chemical parameters which activate the sensor systems of pioneering microbes when they come into contact with a surface. The aim of our study was to examine the pH variations in the local micro-environment created between the cell layer and the surface after bacteria adhesion. Using an ion-sensitive field effect transistor (ISFET), as a substratum, colonized by a curli hyperproducing strain known to form biofilms, we observed that the evolution of the pH change was significantly different in the micro-compartment in contact with the electrochemical sensor compared to that within the liquid phase. 相似文献
95.
This paper evaluates moisture content effects on CO2 capture of an ion-exchange resin (IER) functionalised with a primary amine group. IER capacities were determined by breakthrough with an inlet gas containing 10 vol% CO2, nitrogen and various moisture contents. Three types of behaviour were identified according to humidity level. In saturated air conditions, the stoichiometry could be justified by carbonates and bicarbonates fixation. In dry conditions, we suspect a joint physical adsorption and reaction mechanism. For intermediate humidity, the stoichiometry of 1 CO2 for 1 amine group is consistent with a bicarbonate fixation or carbamic acid formation. 相似文献
96.
Air-coupled ultrasonic sources are relatively inefficient because the high impedance mismatch at the air/solid boundary means that most of the input energy (in air) is reflected at this boundary. The objective of this research is to increase efficiency—specifically an increase in ultrasonic signal amplitude—by designing and building a focused, 2D-array of electrostatic transducers (individual diameters of 38 mm). The operating frequency of this array is in the range of 50–100 kHz; this range is selected for civil infrastructure applications. Numerical simulations are used to design an array by modeling the pressure field in air, and then optimizing an array consisting of 20 transducers to create a line-source. An array is then built (following this design) and the emitted pressure field (in air) of the as built array is measured with a microphone and compared to the pressure field predicted by the numerical model. Finally, the as built focused array is used as an ultrasonic source, and its robustness is verified by comparing the numerical simulation of a transient line-load on an elastic half-space with (completely non-contact) experimentally measured values. There is excellent agreement between these two representations, which confirms the possibility of developing a completely non-contact, scanning ultrasonic system in the 50–100 kHz range. 相似文献
97.
Shimada Y Chow LC Takagi S Tagami J 《Journal of research of the National Institute of Standards and Technology》2010,115(4):233-241
Previous studies reported premixed calcium phosphate cements (CPCs) that were stable in the package and form hydroxyapatite (HA) as the product after exposure to an aqueous environment. These cements had setting times of greater than 60 min, which are too long to be useful for some clinical applications. The present study investigated properties of fast-setting HA-forming premixed CPCs that initially consisted of two separate premixed pastes: (1) finely ground (1.0 μm in median size) dicalcium phosphate anhydrous (DCPA) mixed with an aqueous NaH(2)PO(4) solution, 1.5 mol/L or 3.0 mol/L in concentration, and (2) tetracalcium phosphate consisting of combinations of particles of two different size distributions, 5 μm (TTCP5) and 17 μm (TTCP17) in median size, mixed with glycerin. Equal volume of Pastes 1 and 2 were injected with the use of atwo-barrel syringe fitted with a static mixer into sample molds. The molar Ca/P ratio of combined paste was approximately 1.5. Cements were characterized in terms of setting time (Gilmore needle), diametral tensile strength (DTS), and phase composition (powder x-ray diffraction, XRD). Setting times were found to range from (4.3 ± 0.6 to 68 ± 3) min (mean ± sd; n = 3), and 1-d and 7-d DTS values were from (0.89 ± 0.08 to 2.44 ± 0.16) MPa (mean ± sd; n = 5). Both the NaH(2)PO(4) concentration and TTCP particle size distribution had significant (p < 0.01) effects on setting time and DTS. Powder XRD analysis showed that low crystallinity HA and unreacted DCPA were present in the 1-day specimens, and the extent of HA formation increased with increasing amount of TTCP5 in the TTCP paste. CONCLUSION: Injectable HA-forming premixed CPCs with setting times from 4 to 70 min can be prepared by using DCPA and TTCP as the ingredients. Compared to the conventional powder liquid cements, these premixed CPCs have the advantages of being easy to use and having a range of hardening times. 相似文献
98.
99.
Composition of bacterial and archaeal communities in freshwater sediments with different contamination levels (Lake Geneva, Switzerland) 总被引:6,自引:0,他引:6
The aim of this study was to compare the composition of bacterial and archaeal communities in contaminated sediments (Vidy Bay) with uncontaminated sediments (Ouchy area) of Lake Geneva using 16S rRNA clone libraries. Sediments of both sites were analysed for physicochemical characteristics including porewater composition, organic carbon, and heavy metals. Results show high concentrations of contaminants in sediments from Vidy. Particularly, high contents of fresh organic matter and nutrients led to intense mineralisation, which was dominated by sulphate-reduction and methanogenesis. The bacterial diversity in Vidy sediments was significantly different from the communities in the uncontaminated sediments. Phylogenetic analysis revealed a large proportion of Betaproteobacteria clones in Vidy sediments related to Dechloromonas sp., a group of dechlorinating and contaminant degrading bacteria. Deltaproteobacteria, including clones related to sulphate-reducing bacteria and Fe(III)-reducing bacteria (Geobacter sp.) were also more abundant in the contaminated sediments. The archaeal communities consisted essentially of methanogenic Euryarchaeota, mainly found in the contaminated sediments rich in organic matter. Multiple factor analysis revealed that the microbial community composition and the environmental variables were correlated at the two sites, which suggests that in addition to environmental parameters, pollution may be one of the factors affecting microbial community structure. 相似文献
100.
Blackwood Grady L.; Strupp Hans H.; Bradley Laurence A. 《Canadian Metallurgical Quarterly》1975,43(6):810
30 graduate students in clinical psychology (raters) viewed a videotape recording of an interview with a patient after having read 1 of 3 types of posttherapy information about the patient. One group of raters was presented information associated with a good prognosis, one group was presented information associated with a poor prognosis, and the last group received neutral information about the patient. Half of the members of each group were told that the interview was made at the termination of therapy, the other half were told that it was a 1-yr follow-up interview. All raters then completed scales regarding patient's level of adjustment, psychic distress, amount of change, and success of patient's therapy. Only ratings of pre- to posttherapy patient change varied as a function of prognostic information. Results suggest that although poor prognosis patients are perceived as exhibiting more change than good prognosis patients, only final level of functioning determines global judgments of psychotherapy outcome. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献