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31.
Badr Bassou Nolven Guilhaume Eduard Emil Iojoiu David Farrusseng Karine Lombaert Daniel Bianchi Claude Mirodatos 《Catalysis Today》2011,159(1):103-143
Following the development of a high-throughput (HT) methodology for the evaluation of diesel soot oxidation catalysts in a 16 parallel channels reactor, a library of over 60 catalysts was tested under optimized conditions. The catalyst compositions were chosen to include solids which specific properties like oxygen storage capacity, oxygen mobility and ionic conductivity. The key parameters for high activity appear related to the presence of active and mobile surface oxygen species, and to an appropriate catalyst particle size in order to favour the number of contacts with the soot. In contrast, high oxygen storage capacity and bulk oxygen ion mobility do not appear as relevant properties for high catalytic activity. Nine new formulations were found to perform better than the reference catalyst “high surface area (HSA) ceria” (Rhodia). 相似文献
32.
In this paper, a gap discharge approach to create acoustic signals for ultrasonic low pressure gas flow measurements is investigated. The objective is to develop an ultrasonic gas flow meter system that is capable of operation in extreme industrial environments. These environments might have extremely high temperatures (1200 °C), moisture, steam, dust, low gas pressure and large transmission distances.Most other types of ultrasonic transducers found show sensitivity to such conditions: their operation suffers, or they may even stop functioning if exposed to such environments. The development of new transducer technology is therefore crucial to allow ultrasonic flow measurements in extreme industrial environments. In this paper, the gap discharge emitter is evaluated as a candidate to be used in these applications. Its capabilities as a sound source are investigated, and its impact on flow meter performance is estimated. It can be concluded that, despite the uncertainties it introduces to a flow meter system, it stands out as a strong candidate to be used as an acoustic emitter in a gas flow meter system for extreme environments. 相似文献
33.
Highly sensitive label-free techniques of DNA determination are particularly interesting in relation to the present development of the DNA sensors. We show that subnanomolar concentrations (related to monomer content) of unlabeled DNA can be determined using copper solid amalgam electrodes or hanging mercury drop electrodes in the presence of copper. DNA is first treated with acid (e.g., 0.5 M perchloric acid), and the acid-released purine bases are directly determined by the cathodic stripping voltammetry. Volumes of 5-3 microL of acid-treated DNA can easily be analyzed, thus making possible the determination of picogram and subpicogram amounts of DNA corresponding to attomole and subattomole quantities of 1000-base pair DNA. Application of this determination in DNA hybridization detection is demonstrated using surface H for the hybridization (superparamagnetic beads with covalently attached DNA probe) and the mercury electrodes only for the determination of DNA selectively captured at surface H. 相似文献
34.
35.
Emil Simiu 《Engineering Structures》1983,5(4):273-281
This is the fourth in a series of review papers devoted to the state-of-the-art in wind engineering. The first three parts of the series were published in the October 1981 (pp. 233–241 and 242–248) and March 1982 (pp. 66–74) issues of Engineering Structures. 相似文献
36.
A survey questionnaire eliciting information on the number of internships offered, average salary of interns, selection criteria, and percentages of work time was sent to 294 American Psychological Association (APA)- and non-APA-approved internship sites. Results of this study and the new criteria for accreditation indicate that students from approved doctoral programs have a definite advantage in the internship marketplace. Sufficient evidence exists, however, to conclude that students from non-APA-approved programs may be encouraged to risk competing for APA-approved internships. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
37.
Mathematical statistics are used to design electronic systems in which the effects of the initial variations of the system parameters and the drift of these parameters on the system performance criteria are a minimum. This is accomplished by minimizing the initial variances of the system performance criteria with respect to the initial mean values of the system parameters while constraining the means of these parameters to their required values. In addition, the drift rates of the system parameters are selected in such a manner as to prevent the drift of the mean values of the system performance criteria while reducing the tendencies of the variances of these criteria to increase with time. These techniques were successfully applied to a number of electronic systems, including systems with both active and passive elements, thus illustrating the usefulness of mathematical statistics in the design of mass produced electronic systems. 相似文献
38.
Korotkova O Wolf E 《Journal of the Optical Society of America. A, Optics, image science, and vision》2004,21(12):2382-2385
The complex spectral degree of coherence of a general random, statistically stationary electromagnetic field is introduced in a manner similar to the way it is defined for a beamlike field, namely, by means of Young's interference experiment. Both its modulus and its phase are measurable. We illustrate the definition by applying it to blackbody radiation emerging from a cavity. The results are of particular interest for near-field optics. 相似文献
39.
Palecek E Masarík M Kizek R Kuhlmeier D Hassmann J Schülein J 《Analytical chemistry》2004,76(19):5930-5936
MutS protein plays an important role in the DNA repair system in prokaryotic and eukaryotic cells; it recognizes unpaired and mispaired bases in duplex DNA and can be used for detection of point mutations in vitro. We have shown that small amounts of this protein can be detected electrochemically at mercury and carbon electrodes without any labeling. Using constant current stripping analysis (CPSA) and mercury electrodes, tens of attomoles of this protein can be detected. The sensitivity of the determination at carbon electrodes is by more than 3 orders of magnitude lower. Using biotinylated DNA duplexes attached to magnetic beads, single-base mismatches and insertion/deletions were recognized by MutS. Picogram amounts of this protein were detected by CPSA after MutS releasing from the beads. 相似文献
40.
Mode analysis of spreading of partially coherent beams propagating through atmospheric turbulence 总被引:11,自引:0,他引:11
Shirai T Dogariu A Wolf E 《Journal of the Optical Society of America. A, Optics, image science, and vision》2003,20(6):1094-1102
The spreading of partially coherent beams propagating through atmospheric turbulence is studied by use of the coherent-mode representation of the beams. Specifically, we consider partially coherent Gaussian Schell-model beams entering the atmosphere, and we examine the spreading of each coherent mode, represented by a Hermite-Gaussian function, on propagation. We find that in atmospheric turbulence the relative spreading of higher-order modes is smaller than that of lower-order modes, whereas the relative spreading of all order modes is the same as in free space. This modal behavior successfully explains why under certain circumstances partially coherent beams are less affected by atmospheric turbulence than are fully spatially coherent laser beams. 相似文献