A bending piezoelectric actuator has been manufactured with a 250
μm thick PZT plate embedded in five layers of unidirectional fiber Kevlar epoxy. The selected orientation of the fibers produces a ...gradient of residual stresses in the composite that enhances bending actuation. By segmenting the electrodes, it is possible to launch an ultrasonic pulse in the actuator so that structural health monitoring of the actuator itself can be performed using pitch catch ultrasonic NDE during the low frequency actuation. Qualitative experimental results of fatigue tests and damage detection are presented.
A bending piezoelectric actuator has been manufactured with a 250
μm thick PZT plate embedded in five layers of unidirectional fiber Kevlar epoxy. The selected orientation of the fibers produces a ...gradient of residual stresses in the composite that enhances bending actuation. By segmenting the electrodes, it is possible to launch an ultrasonic pulse in the actuator so that structural health monitoring of the actuator itself can be performed using pitch catch ultrasonic NDE during the low frequency actuation. Qualitative experimental results of fatigue tests and damage detection are presented.
Considering the NO adsorption process, starting from theoretical considerations, evaluation of the variation of the properties of metallic clusters versus their size and composition leads to a ...prediction of the NO adsorption mode on these nanoentities. Then, based on experimental results obtained mostly through X-ray absorption spectroscopy, we have connected the adsorption mode of the molecule to the behaviour of the metallic cluster following the adsorption process. A simple hypothesis leads us to discuss the catalytic activity of nanometer scale metallic clusters following NO adsorption.
Partant des considérations théoriques, l'évaluation de la variation des propriétés d'agrégats métalliques en fonction de leur taille et leur composition mène à une prédiction du mode d'adsorption du NO sur ces nanoentités. En nous appuyant sur les résultats expérimentaux obtenus surtout par la spectroscopie d'absorption de rayons X, nous proposons de lier le mode d'adsorption de la molécule au comportement de l'agrégat métallique suite à l'adsorption. Une hypothèse simple nous mène à envisager une interprétation de l'activité catalytique d'agrégats métalliques nanométriques lors de l'adsorption du NO.
New advances in theoretical background as well as recent experimental results associated to nanometer scale monometallic clusters are presented. Regarding the calculation of their electronic ...structure, the significant physical parameters, which control the relaxation of the intermetallic distances are introduced. From an experimental point of view, the limitations and advantages of a study based on an Extended X-ray Absorption Fine Structure (Exafs)–Anomalous Wide Angle X-ray Scattering (Awaxs) approach are discussed. Finally, through a review of recent papers, we try to make a link between metallic surfaces and nanometer scale monometallic clusters in the case of the interaction with a small molecule namely nitric oxide (NO). This parallel could be used to classify and thus predict the behaviour of the nanometer scale monometallic particles during adsorption of this molecule.
The importance of understanding the interactions between nanoscale materials and living matter has now begun to be appreciated by an extraordinaryly large range of stakeholders, including ...researchers, industry, governments and society, all of whom appreciate both the opportunities presented by and challenges raised by this arena of research. Not only does it open up new directions in nanomedicine and nanodiagnostics, but it also offers the chance to implement nanotechnology across all industry in a safe and responsible manner. The underlying reasons for this arena as a new scientific paradigm are real and durable. Less than 100 nm nanoparticles can enter cells, less that 40 nm they can enter cell nucleus, and less that 35 nm they can pass through the blood brain barrier. These are fundamental length scales of biological relevance that will ensure that engineered nanoscience will impinge on biology and medicine for many decades to come. One important issue is the current lack of reproducibility of the outcomes of many experiments in this arena. Differences are likely a consequence of such things as uncontrolled nanoparticle aggregation leading to unpredictable doses being presented to cells, interference of the nanoparticles themselves with many of the tests being applied, differences in the degree of confluency of the cells used, and a host of other factors. NanoInteract has shown how careful control of all aspects of the test system, combined with round robin type approaches, can help resolve these issues and begin to ensure that the field can become a quantitative science. The basic principle of NanoInteract is that given identical nanomaterials, cells and biological materials, and using a common protocol, experiments must yield identical answers. Thus, any deviations result from errors in (applying) the protocol which can be tracked and eliminated, until quantitatively reproducible results are obtained by any researcher in any location. This paper outlines the NanoInteract programme, illustrates key advances, and highlights early successes. (www.nanointeract.net)
The reproducibility of the binary typing (BT) protocol developed for epidemiological typing of
Staphylococcus aureus was analyzed in a biphasic multicenter study. In a Dutch multicenter pilot study, ...10 genetically unique isolates of methicillin-resistant
S. aureus (MRSA) were characterized by the BT assay as presented by van Leeuwen et al. J. Clin. Microbiol. 2001 39 (1) 328. The BT assay, including a standardized DNA extraction protocol was performed in duplicate in eleven medical microbiology laboratories. Two different hybridization detection procedures were applied and a prelabeled DNA sample as process control was included. Only three laboratories accurately identified all strains. Divergence in technical procedures resulted in misinterpretation due to an increasing number of faint or absent hybridization signals in combination with high background staining. The binary type of the process control was determined correctly by all participating laboratories. The feasibility of the BT protocol was related directly to the skill of the laboratory personnel. On the basis of the national study, we concluded that the DNA extraction protocol needed modification to improve DNA yield and purity.
Subsequently, seven European laboratories participated in an international study to determine the reproducibility of the modified BT protocol. Each center was asked to analyze 10 DNA samples previously extracted from 10 MRSA strains (phase 1) and, additionally, to analyze 10 MRSA strains, using the standardized or their in-house DNA isolation protocol (phase 2). A prelabeled DNA process control sample was included again. The binary types of all DNA samples were identified correctly by all but one laboratories. This latter laboratory diverged from the protocol by adding an excess of labeled DNA to the hybridization mixture, resulting in a high background and, therefore, noninterpretable BT results. All centers produced identical BT results for the process control. Five of the seven centers correctly identified the binary types of all 10 MRSA strains in phase 2 of the international study. Three of these centers used their in-house DNA extraction protocol. Divergence from the standard BT protocol in the remaining two centers resulted in no interpretable BT data for the 10 MRSA strains. The study demonstrated that each center that followed the BT protocol to the letter could generate reproducible results, irrespective whether or not an in-house DNA isolation protocol was used. The current BT protocol thus represents a simple method generating robust, reproducible genotype data for
S. aureus strains.
La chute du communisme et l’effondrement économique des pays de l’Est ont donné au Plan Marshall du relief, voire de l’actualité : les responsables économiques et politiques ne se lassent pas ...d’interroger, à la lumière de la nouvelle donne mondiale, ce transfert financier et idéologique qui contribua, en grande partie, au redressement de l’Europe d’après-guerre. Quarante-cinq ans plus tard, il était plus que temps de dresser un état sérieux de cette question, jamais traitée dans son ensemble. Les spécialistes - historiens, économistes, responsables politiques - qui ont participé au colloque international qui lui fut consacré à Bercy sous l’égide du Comité pour l’histoire économique et financière, livrent ici leurs études et leurs réflexions. Ne se limitant pas à l’Europe et aux États-Unis, mais débordant aussi sur l’Extrême-Orient, celles-ci couvrent tous les aspects du Plan Marshall : économiques, industriels, financiers, mais aussi politiques, diplomatiques ou idéologiques...
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