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See detailNon-confined jet-slot-cavity oscillator: flow-acoustic interaction modeling
Glesser, Martin; Billon, Alexis ULg; Valeau, Vincent et al

Conference (2006, May)

Disturbing whistling due to self-sustained oscillations can be produced in a wide variety of geometries where a sheared subsonic flow impinges on a downstream obstacle. When those self-sustained ... [more ▼]

Disturbing whistling due to self-sustained oscillations can be produced in a wide variety of geometries where a sheared subsonic flow impinges on a downstream obstacle. When those self-sustained oscillations are coupled with an acoustic resonator, the acoustic production can reach dramatically high levels. The configuration known as jet-slot oscillator is studied in the particular case where the resonator is the flow-supply duct and the source region is unconfined. This sound production is due to flow-acoustic interactions and can be modeled by using the vortex-sound theory. It allows one to express the acoustic power generated by the interaction between the acoustic, velocity, and vorticity fields. They are obtained separately by using rather simple models together with experimental input data. The vorticity field is modeled with the assumption that the shear layer is rectilinear and the vorticity is only concentrated on discrete vortex-points convected at constant velocity. The vorticity being non null only in the shear layer, the velocity field is calculated only in this region where it is equal to the vortices convection speed. The source region dimensions being small compared to the acoustic wavelength, this field is considered, in harmonic regime, as a sinusoidal temporal fluctuation of a potential field. This field can be taken as resulting from the flow produced by the radiation of the flow supply duct's acoustic resonance. It is obtained by solving the Poisson equation in a simplified geometry obtained by Schwarz-Christoffel mapping. The configuration studied here presents some specific problems which must be addressed to correctly model its sound production. Experimentations are used to specify the missing parameters. The major one is the synchronisation between the vorticity field and the acoustic field which governs the way that the vortices interact with the resonant acoustic field. At last, comparison between experimental data and modeling results permits to validate the study, in terms of emitted frequency. Further developments of the model will allow to predict the emitted sound level. [less ▲]

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See detailThe non-core regions of human lysozyme amyloid fibrils influence cytotoxicity.
Mossuto, Maria F; Dhulesia, Anne; Devlin, Glyn et al

in Journal of Molecular Biology (2010), 402(5), 783-96

Identifying the cause of the cytotoxicity of species populated during amyloid formation is crucial to understand the molecular basis of protein deposition diseases. We have examined different types of ... [more ▼]

Identifying the cause of the cytotoxicity of species populated during amyloid formation is crucial to understand the molecular basis of protein deposition diseases. We have examined different types of aggregates formed by lysozyme, a protein found as fibrillar deposits in patients with familial systemic amyloidosis, by infrared spectroscopy, transmission electron microscopy, and depolymerization experiments, and analyzed how they affect cell viability. We have characterized two types of human lysozyme amyloid structures formed in vitro that differ in morphology, molecular structure, stability, and size of the cross-beta core. Of particular interest is that the fibrils with a smaller core generate a significant cytotoxic effect. These findings indicate that protein aggregation can give rise to species with different degree of cytotoxicity due to intrinsic differences in their physicochemical properties. [less ▲]

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See detailA non-cytosolic protein of Trypanosoma evansi induces CD45-dependent lymphocyte death.
Antoine-Moussiaux, Nicolas ULg; Cornet, Anne ULg; Cornet, François ULg et al

in PLoS ONE (2009), 4(5), 5728

In a recent study dealing with a mouse model of Trypanosoma evansi-associated disease, a remarkable synchrony between the parasitaemia peak and the white-blood-cell count nadir was noticed. The present ... [more ▼]

In a recent study dealing with a mouse model of Trypanosoma evansi-associated disease, a remarkable synchrony between the parasitaemia peak and the white-blood-cell count nadir was noticed. The present study was designed to establish whether there is a direct causal link between the parasite load during its exponential phase of growth and the disappearance of peripheral blood leukocytes. In vitro experiments performed with trypanosomes and purified peripheral blood mononucleated cells revealed the existence of a lymphotoxin embedded in the T. evansi membrane: a protein sensitive to serine proteases, with a molecular mass of less than 30 kDa. Lymphocytes death induced by this protein was found to depend on the intervention of a lymphocytic protein tyrosine phosphatase. When lymphocytes were exposed to increasing quantities of a monoclonal antibody raised against the extracellular portion of CD45, a transmembrane protein tyrosine phosphatase covering over 10% of the lymphocyte surface, T. evansi membrane extracts showed a dose-dependent decrease in cytotoxicity. As the regulatory functions of CD45 concern not only the fate of lymphocytes but also the activation threshold of the TCR-dependent signal and the amplitude and nature of cytokinic effects, this demonstration of its involvement in T. evansi-dependent lymphotoxicity suggests that T. evansi might manipulate, via CD45, the host's cytokinic and adaptive responses. [less ▲]

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See detailNon-destructive characterization of deer (Cervus Elaphus) antlers by X-ray microtomography coupled with image analysis
Léonard, A.; Guiot, L. P.; Pirard, J. P. et al

in Journal of Microscopy (2007), 225(3), 258-263

X-ray microtomography coupled with image analysis was tested as a non-destructive alternative method for the textural characterization of the trabecular part of deer antlers (Cervus Elaphus). As gas ... [more ▼]

X-ray microtomography coupled with image analysis was tested as a non-destructive alternative method for the textural characterization of the trabecular part of deer antlers (Cervus Elaphus). As gas adsorption and mercury intrusion cannot be applied on this soft and spongy material, its pore texture was, up to now, determined from histological sections that give only two-dimensional information. In this work, X-ray microtomography is used to scan entire or half pieces of antlers and three-dimensional image analysis is performed in order to assess the differences between samples collected at various antler locations. Results clearly show a porosity profile along the sample diameter. The pore size distribution is showed to be dependent on the sample original site. [less ▲]

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See detailNon-destructive characterization of deer (Cervus Elaphus) antlers by X-ray microtomography coupled with image analysis
Léonard, Angélique ULg; Guiot, L. P.; Pirard, Jean-Paul ULg et al

in Journal of Microscopy-Oxford (2007), 225(Pt 3), 258-263

X-ray microtomography coupled with image analysis was tested as a non-destructive alternative method for the textural characterization of the trabecular part of deer antlers (Cervus Elaphus). As gas ... [more ▼]

X-ray microtomography coupled with image analysis was tested as a non-destructive alternative method for the textural characterization of the trabecular part of deer antlers (Cervus Elaphus). As gas adsorption and mercury intrusion cannot be applied on this soft and spongy material, its pore texture was, up to now, determined from histological sections that give only two-dimensional information. In this work, X-ray microtomography is used to scan entire or half pieces of antlers and three-dimensional image analysis is performed in order to assess the differences between samples collected at various antler locations. Results clearly show a porosity profile along the sample diameter. The pore size distribution is showed to be dependent on the sample original site. [less ▲]

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See detailNon-destructive characterization of the Nizet Manuscript (XVIIIth century) : first results
Machowski, Mélanie ULg; Calvo Del Castillo, Helena ULg; Hocquet, François-Philippe et al

Poster (2012, June)

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See detailNon-destructive extraction of junction depths of active doping profiles from photomodulated optical reflectance offset curves
Bogdanowicz, Janusz; Dortu, Fabian; Clarysse, Trudo et al

in Journal of Vacuum Science & Technology : Part B (2010), 28(1), 11

The ITRS Roadmap highlights the electrical characterization of the source and drain extension regions as a key challenge for future complimentary-metal-oxide-semiconductor technology. Presently, an ... [more ▼]

The ITRS Roadmap highlights the electrical characterization of the source and drain extension regions as a key challenge for future complimentary-metal-oxide-semiconductor technology. Presently, an accurate determination of the depth of ultrashallow junctions can routinely only be performed by time-consuming and destructive techniques such as secondary ion mass spectrometry (SIMS). In this work, the authors propose to use the fast and nondestructive photomodulated optical reflectance (PMOR) technique , as implemented in the Therma-Probe\textregistered (TP) dopant metrology system, for these purposes. PMOR is a pump-probe technique based on the measurement of the pump-induced modulated change in probe reflectance, i.e., the so-called (photo) modulated reflectance. In this article, the authors demonstrate that the absolute junction depths of boxlike active dopant structures can be extracted in a very simple and straightforward way from the TP offset curves, which represent the behavior of the modulated reflectance as a function of the pump-probe beam spacing. Although the procedure is based on the insights into the physical behavior of the offset curves, no modeling is involved in the actual extraction process itself. The extracted junction depths are in good correlation with the corresponding junction depths as measured by means of SIMS. The technique has a subnanometer depth sensitivity for depths ranging from 10 to 35 nm with the present Therma-Probe\textregistered 630XP system. The extension of the proposed procedure to the general ultrashallow profiles is also explored and discussed [less ▲]

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See detailNon-destructive measurement of volume magnetic properties of large, bulk superconductors
Vanderbemden, Philippe ULg; Dennis, T.; Shi, Y. H. et al

Conference (2012, December 07)

The development of large, single grain bulk superconductors by melt processing techniques has generated a need to characterize samples magnetically over large dimensions, exceeding typically 20 mm in ... [more ▼]

The development of large, single grain bulk superconductors by melt processing techniques has generated a need to characterize samples magnetically over large dimensions, exceeding typically 20 mm in diameter. The usual magnetic characterization gives relies on miniature Hall probe mapping and gives information about the field distribution above the sample surface. If volume properties are required (e.g. magnetization hysteresis loops), the sample needs to be cut in smaller pieces, since the DC magnetic characterization systems for measurements at cryogenic temperatures generally accommodate samples of relatively small size (typically < 5-10 mm diameter). In this work we describe how the hysteresis B(H) loops of large bulk superconducting samples exceeding 10 mm diameter can be determined using home-made sensing coils, either in liquid nitrogen or within the experimental chamber of a Quantum Design Physical Property Measurement System (PPMS). Magnetic properties are measured and compared to those given by several Hall probes attached to both faces of sample. The system is used successfully to measure the DC hysteresis loops of entire (RE)BCO bulk superconducting domains. A careful data acquisition and numerical integration of pick-up coil voltage enables the sweep rate of the magnetic field to be varied from 0.5 to 10 mT/s while keeping an excellent signal/noise ratio. A simple model based on demagnetizing field approach is used to emphasize how the hysteresis loops determined by this technique differ from “true” magnetization loops derived from classical magnetic moment measurements (e.g. SQUID or VSM). These differences are supported with numerical modelling of the average magnetization of the bulk sample using the Brandt method. [less ▲]

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See detailNon-Destructive Methods for the Detection of Delaminations in Concrete Bridge Decks
Van der Wielen, Audrey ULg

Master's dissertation (2009)

To detect delaminations in concrete bridge decks, the non-destructive techniques (NDT) permit a frequent inspection of the slabs without damaging the structures. Within this study, twelve samples were ... [more ▼]

To detect delaminations in concrete bridge decks, the non-destructive techniques (NDT) permit a frequent inspection of the slabs without damaging the structures. Within this study, twelve samples were realized, presenting diverse horizontal defects simulating delaminations. They were scanned with high frequency GPR with the common offset (CO) and common mid point (CMP) methods. The electromagnetic waves speed and defects depth were determined from the CMPs. A 3D visualization program was also created to display the CO measurements. The visibility of the inserted defects revealed to be dependent on their lateral extension, their thickness and especially their constitutive material. [less ▲]

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See detailNon-destructive provenance differentiation of prehistoric pigments by external PIXE
Beck, Lucile; Salomon, Hélène ULg; Lahlil, Sophia et al

in Nuclear Instruments & Methods in Physics Research. Section B, Beam Interactions with Materials and Atoms (2012), 273

The elemental analysis of minerals/rocks has been often used for the determination of their geological origin. When these natural rocks were exploited by prehistoric civilizations as objects, weapons, or ... [more ▼]

The elemental analysis of minerals/rocks has been often used for the determination of their geological origin. When these natural rocks were exploited by prehistoric civilizations as objects, weapons, or pigments, the composition of the minerals can provide information on the mobility, the exchanges and the interaction between groups of population. In this paper, we will present results obtained from archaeological samples of prehistoric pigments, mainly iron and manganese oxides. PIXE analysis has been applied to samples of the prehistoric cave “La grotte du Renne” in previous termArcynext term-previous termsurnext term-previous termCurenext term, France (Chatelperronian, 38,000–34,000 BP). Because most of the archaeological objects are decorated or display some use marks, it is not possible to take samples. Consequently, we have used a non-destructive technique thanks to the external beam of AGLAE (C2RMF, Paris). In order to improve the limits of detection (LOD less than 10 ppm from Cu to Sb), a metal absorber has been placed on the X-ray detector to preferentially filter the Fe–K or Mn–K lines. Based on the quantitative analysis of major and trace elements, we have obtained groups of compositions corresponding to different geological sources. We demonstrate in this study that it is possible to extend PIXE analysis to the characterization of prehistoric pigments such as iron and manganese oxides for differentiating potential sources of pigments in archaeological contexts. [less ▲]

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See detailA non-destructive testing application solved with A-X geometric eddy-current formulation
Codecasa, Lorenzo; Dular, Patrick ULg; Specogna, Ruben et al

in COMPEL (2010), 29(6), 1606-1615

Purpose – The purpose of this paper is to introduce a perturbation method for the A-X geometric formulation to solve eddy-current problems and apply it to the feasibility design of a non-destructive ... [more ▼]

Purpose – The purpose of this paper is to introduce a perturbation method for the A-X geometric formulation to solve eddy-current problems and apply it to the feasibility design of a non-destructive evaluation device suitable to detect long-longitudinal volumetric flaws in hot steel bars. Design/methodology/approach – The effect of the flaw is accurately and efficiently computed by solving an eddy-current problem over an hexahedral grid which gives directly the perturbation due to the flaw with respect to the unperturbed configuration. Findings – The perturbation method, reducing the cancelation error, produces accurate results also for small variations between the solutions obtained in the perturbed and unperturbed configurations. This is especially required when the tool is used as a forward solver for an inverse problem. The method yields also to a considerable speedup: the mesh used in the perturbed problem can in fact be reduced at a small fraction of the initial mesh, considering only a limited region surrounding the flaw in which the mesh can be refined. Moreover, the full three-dimensional unperturbed problem does not need to be solved, since the source term for computing the perturbation is evaluated by solving a two-dimensional flawless configuration having revolution symmetry. Originality/value – A perturbation method for the A-X geometric formulation to solve eddy-current problems has been introduced. The advantages of the perturbation method for non-destructive testing applications have been described. [less ▲]

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See detailNon-dissipative joints in seismic resistant building frames - Bolted beam-to-column joints
Coméliau, Ludivine ULg; Demonceau, Jean-François ULg; Jaspart, Jean-Pierre ULg

in EUROSTEEL 2011 - 6th European Conference on Steel and Composite Structures - Proceedings (2011, September)

According to Eurocode 8, earthquake resistant steel building frames shall be designed following either the “low dissipative structural behaviour concept” or the “dissipative structural behaviour concept” ... [more ▼]

According to Eurocode 8, earthquake resistant steel building frames shall be designed following either the “low dissipative structural behaviour concept” or the “dissipative structural behaviour concept”. In the second concept, the capability of parts of the structure to resist earthquake actions through inelastic behaviour is taken into account: energy is dissipated in plastic mechanisms. In such a design, it has to be ensured that the dissipative zones form where they are intended to and that they yield before other zones leave the elastic range. In particular, moment resisting frames are designed in such a way that plastic hinges develop at the extremities of the beams. These dissipative zones can be located either in the beams or in the beam-to-column joints. In this paper, non-dissipative bolted beam-to-column connections are considered. They must be sufficiently resistant to remain in elastic range while cyclic yielding develops in the dissipative zones located in the beams. Besides, the possibility that the actual yield strength of the beam is higher than the nominal value has to be taken into account by a material overstrength factor. Such an approach generally leads to very strong and thus expensive joints. In the present paper, a design strategy leading to more economical solutions for full-strength beam-to-column joints is detailed. This study was conducted within the framework of an RFCS project called HSS-SERF (High Strength Steel in Seismic Resistant Building Frames). The considered moment-resisting joints are part of seismic resistant building frames made of high strength steel composite columns and mild carbon steel beams. The columns are either partially-encased wide-flange columns (H columns) or concrete-filled rectangular hollow-section columns (RHS columns). The proposed joint configuration uses hammer-heads extracted from the beam profile. To fulfil the resistance requirement taking account of the possible overstrength of the beam, the resistant moment of the joint is decomposed in the contributions of the different components involved. Then, no overstrength factor needs to be considered for the components related to the beam itself and to the hammer-heads. This approach is in full accordance with the basic principles of Eurocode 8 and can decrease much the required resistance of the joints provided some conditions are fulfilled, meaning lower costs. [less ▲]

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See detailLa non-expression de l’objet direct en égyptien ancien : études valentielles
Winand, Jean ULg

in Lingua Aegyptia [= LingAeg] (2004), (12), 205-234

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See detailNon-fluorescent, short-lived intermediate in photoenzymatic protochlorophyllide reduction at room temperature
Franck, Fabrice ULg; Dujardin, E.; Sironval, C.

in Plant Science Letters (1980), 18

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See detailNon-Gaussian behavior and anticorrelations in ultrathin gate oxides after soft breakdown
Vandewalle, Nicolas ULg; Ausloos, Marcel ULg; Houssa, M. et al

in Applied Physics Letters (1999), 74(11), 1579-1581

The time dependence of the gate voltage V-G(t) after soft breakdown of metal-oxide-semiconductor capacitors with a 2.4 nm SiO2 layer has been measured. It is found that the V-G(t) fluctuation ... [more ▼]

The time dependence of the gate voltage V-G(t) after soft breakdown of metal-oxide-semiconductor capacitors with a 2.4 nm SiO2 layer has been measured. It is found that the V-G(t) fluctuation distributions are non-Gaussian, but can be described by a Levy stable distribution. The long-range correlations in V-G(t) are investigated within the detrended fluctuations analysis. The Hurst exponent is found to be H = 0.25 +/- 0.04 independent of the value of the stress current density J. It is argued that these are universal features of soft breakdown and are due to trapping-detrapping of electrons in and away from the primary percolation path. [less ▲]

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See detailNon-Gaussian electrical fluctuations in a quasi-2d packing of metallic beads
Vandewalle, Nicolas ULg; Lenaerts, Cedric ULg; Dorbolo, Stéphane ULg

in Europhysics Letters [=EPL] (2001), 53(2), 197-201

The electrical properties of a two-dimensional packing of metallic beads are studied. Small mechanical perturbations of the packing lead to giant voltage fluctuations. Fluctuations are found to be non ... [more ▼]

The electrical properties of a two-dimensional packing of metallic beads are studied. Small mechanical perturbations of the packing lead to giant voltage fluctuations. Fluctuations are found to be non-Gaussian and seem to belong to Levy stable distributions. Anticorrelations have been also found for the sign of these fluctuations. [less ▲]

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See detailNon-genetic factors affecting the reproduction performance, lamb growth and productivity indices of Djallonke sheep
Gbangboche, A. B.; Adamou-Ndiaye, M.; Youssao, A. K. I. et al

in Small Ruminant Research (2006), 64((1-2)), 133-142

Detailed reference viewed: 44 (9 ULg)