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See detailFluid Bearings in LOX
Bozet, Jean-Luc ULg

Conference (2004, December)

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See detailFluid fragmentation shapes rain-induced foliar disease transmission
Gilet, Tristan ULg; Bourouiba, Lydia

in Journal of the Royal Society, Interface (2015), 12

Plant diseases represent a growing threat to the global food supply. The factors contributing to pathogen transmission from plant to plant remain poorly understood. Statistical correlations between ... [more ▼]

Plant diseases represent a growing threat to the global food supply. The factors contributing to pathogen transmission from plant to plant remain poorly understood. Statistical correlations between rainfalls and plant disease out- breaks were reported; however, the detailed mechanisms linking the two were relegated to a black box. In this combined experimental and theoretical study, we focus on the impact dynamics of raindrops on infected leaves, one drop at a time. We find that the deposition range of most of the pathogen-bear- ing droplets is constrained by a hydrodynamical condition and we quantify the effect of leaf size and compliance on such constraint. Moreover, we identify and characterize two dominant fluid fragmentation scenarios as responsible for the dispersal of most pathogen-bearing droplets emitted from infected leaves: (i) the crescent-moon ejection is driven by the direct interaction between the impacting raindrop and the contaminated sessile drop and (ii) the inertial detachment is driven by the motion imparted to the leaf by the raindrop, lead- ing to catapult-like droplet ejections. We find that at first, decreasing leaf size or increasing compliance reduces the range of pathogen-bearing droplets and the subsequent epidemic onset efficiency. However, this conclusion only applies for the crescent moon ejection. Above a certain compliance threshold a more effective mechanism of contaminated fluid ejection, the inertial detachment, emerges. This compliance threshold is determined by the ratio between the leaf velocity and the characteristic velocity of fluid fragmentation. The inertial detachment mechanism enhances the range of deposition of the larger con- taminated droplets and suggests a change in epidemic onset pattern and a more efficient potential of infection of neighbouring plants. Dimensionless parameters and scaling laws are provided to rationalize our observations. Our results link for the first time the mechanical properties of foliage with the onset dynamics of foliar epidemics through the lens of fluid fragmentation. We discuss how the reported findings can inform the design of mitigation strategies acting at the early stage of a foliar disease outbreak. [less ▲]

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See detailFluid inclusions in charnockites from the Bjerkreim-Sokndal massif (Rogaland, South-Western Norway): fluid origin and in situ evolution
Wilmart, Edith; Clocchiatti, Robert; Duchesne, Jean-Clair ULg et al

Conference (1991, September 14)

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See detailFluid inclusions in charnockites from the Bjerkreim-Sokndal massif (Rogaland, southwestern Norway): fluid origin and in situ evolution
Wilmart, Edith; Clocchiatti, Robert; Duchesne, Jean-Clair ULg et al

in Contributions to Mineralogy & Petrology (1991), 108

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See detailFluid instabilities in the birth and death of antibubbles
Dorbolo, Stéphane ULg; Caps, Hervé ULg; Vandewalle, Nicolas ULg

in New Journal of Physics (2003), 5

Antibubbles have been produced and studied with the help of a high-speed camera. An antibubble is defined as a fluid object constituted by a thin air shell surrounding a liquid and surrounded by the same ... [more ▼]

Antibubbles have been produced and studied with the help of a high-speed camera. An antibubble is defined as a fluid object constituted by a thin air shell surrounding a liquid and surrounded by the same liquid. Images reveal some key physical processes and fluid instabilities which take place when an antibubble forms and dies. The collapsing speed of the air film has been measured. Culik's theory does not apply. A new mechanism has been introduced. [less ▲]

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See detailFluid management and plasma renin activity in organ donors
Canivet, Jean-Luc ULg; Damas, Pierre ULg; Hans, Pol ULg et al

in Transplant International : Official Journal of the European Society for Organ Transplantation (1989), 2(3), 129-132

Fluid management and assessment of organ perfusion in organ donors with hypotonic polyuria remain poorly investigated problems. In our protocol, urinary losses (565 +/- 202 ml/h) were replaced volume for ... [more ▼]

Fluid management and assessment of organ perfusion in organ donors with hypotonic polyuria remain poorly investigated problems. In our protocol, urinary losses (565 +/- 202 ml/h) were replaced volume for volume by 3.3% dextrose/0.3% natrium chloride solution (Baxter) with 20 mmol/l potassium chloride. Concentrated red blood cells were administered to maintain hematocrit at about 30%, and volume expansion (central venous pressure above 6 mmHg) was obtained by gelatin (haemaccel) infusion. In all donors (n = 9), plasma electrolytes remained within normal limits despite hypotonic polyuria. Suppression of initial plasma renin activity (PRA: 9.7 +/- 3.6 ng/ml per hour) was obtained by subacute volume expansion. In eight donors the hemodynamic status improved, dopamine administration, when used, was discontinued, and PRA decreased (2.3 +/- 0.7 ng/ml per hour; P less than 0.05). The only donor who failed to respond to fluid therapy had increased PRA (24.2 ng/ml per hour). During fluid challenge, an inverse relationship was demonstrated between mean arterial pressure and PRA in all nine donors (r = -0.61; P less than 0.001), while there were no significant changes in blood urea. creatinine, or urine output. It is concluded that in organ donors, proper maintenance of the hemodynamic status and suppression of the renin stress response may be obtained by an adequate fluid management, involving both qualitative restoration and expansion of intravascular volume. [less ▲]

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See detailFluid therapy in PET
Brichant, Jean-François ULg

Conference (2005, September 30)

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See detailThe fluid trampoline: droplets bouncing on a soap film
Gilet, Tristan ULg; Bush, John W.M.

in Journal of Fluid Mechanics (2009), 625

We present the results of a combined experimental and theoretical investigation of droplets falling onto a horizontal soap film. Both static and vertically vibrated soap films are considered. In the ... [more ▼]

We present the results of a combined experimental and theoretical investigation of droplets falling onto a horizontal soap film. Both static and vertically vibrated soap films are considered. In the static case, a variety of behaviours were observed, including bouncing, crossing and partial coalescence. A quasi-static description of the soap film shape yields a force–displacement relation that provides excellent agreement with experiment, and allows us to model the film as a nonlinear spring. This approach yields an accurate criterion for the transition between droplet bouncing and crossing. Moreover, it allows us to rationalize the observed constancy of the contact time and scaling for the coefficient of restitution in the bouncing states. On the vibrating film, a variety of bouncing behaviours were observed, including simple and complex periodic states, multi-periodicity and chaos. A simple theoretical model is developed that captures the essential physics of the bouncing process, reproducing all observed bouncing states. The model enables us to rationalize the observed coexistence of multiple periodic bouncing states by considering the dependence of the energy transferred to the droplet on the phase of impact. Quantitative agreement between model and experiment is deduced for simple periodic modes, and qualitative agreement for more complex periodic and chaotic bouncing states. Analytical solutions are deduced in the limit of weak forcing and dissipation, yielding insight into the contact time and periodicity of the bouncing states. [less ▲]

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See detailFluid transfer in anorthosites and related rocks from Rogaland (Southwest Norway): Evidence from stable isotopes
Wilmart, Edith; Pineau, Françoise; Réjou-Michel, A. et al

in Earth and Planetary Science Letters (1994), 125

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See detailFluid-structure interaction effects in the dynamic response of free-standing plates to uniform shock loading
Kambouchev, Nayden; Radovitzky, Raúl; Noels, Ludovic ULg

in Journal of Applied Mechanics (2007), 74

The problem of uniform shocks interacting with free-standing plates is studied analytically and numerically for arbitrary shock intensity and plate mass. The analysis is of interest in the design and ... [more ▼]

The problem of uniform shocks interacting with free-standing plates is studied analytically and numerically for arbitrary shock intensity and plate mass. The analysis is of interest in the design and interpretation of fluid–structure interaction (FSI) experiments in shock tubes. In contrast to previous work corresponding to the case of incident blast profiles of exponential distribution, all asymptotic limits obtained here are exact. The contributions include the extension of Taylor’s FSI analysis for acoustic waves, the exact analysis of the asymptotic limits of very heavy and very light plates for arbitrary shock intensity, and a general formula for the transmitted impulse in the intermediate plate mass range. One of the implications is that the impulse transmitted to the plate can be expressed univocally in terms of a single nondimensional compressible FSI parameter. [less ▲]

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See detailFluidothérapie chez le veau
Sartelet, Arnaud ULg; Lecomte, Denis; Theron, Léonard ULg et al

Conference (2013, September 27)

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See detailFluidothérapie parentérale pratique chez les bovins
Rollin, Frédéric ULg

in Annales de Médecine Vétérinaire (1997), 141(2), 89-111

After setting up the main indications for parenteral fluid therapy in calves and adult cattle, the means are studied to practically evaluate on the field the dehydration, acid-base status, electrolyte ... [more ▼]

After setting up the main indications for parenteral fluid therapy in calves and adult cattle, the means are studied to practically evaluate on the field the dehydration, acid-base status, electrolyte disturbances and glycemia. The various classes of fluids are then considered as a function of the indications. Use of transfusion, hypertonic solutions and parenteral nutrition is broached. Routes and techniques of fluid administration are detailed. Obstacles encountered by the bovine practitioner when using parenteral fluid therapy are emphasized just as the means to overcome them. In this regard, it is described how to correctly prepare fluids for suited parenteral use in cattle. In fact, the present laws do not given this allowance to the practitioners. However, in most cases, it constitutes the only economical option avoiding worthless sufferings and death of the animal. [less ▲]

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See detailFluorescence and circular dichroism studies on the Streptomyces R61 DD-carboxypeptidase-transpeptidase. Penicillin binding by the enzyme
Nieto, Manuel; Perkins, Harnold R.; Frère, Jean-Marie ULg et al

in Biochemical Journal (1973), 135(3), 493-505

The circular dichroism of the dd-carboxypeptidase-transpeptidase from Streptomyces R61 shows in the near u.v. a set of weak extrema at 289nm (positive) and at 282, 275 and 268nm (all negative). In the far ... [more ▼]

The circular dichroism of the dd-carboxypeptidase-transpeptidase from Streptomyces R61 shows in the near u.v. a set of weak extrema at 289nm (positive) and at 282, 275 and 268nm (all negative). In the far u.v. it shows negative extrema at 217-218 and 208nm, crossover at 202nm and a positive maximum at about 194nm. The u.v. absorption of the enzyme shows it to contain tyrosine and tryptophan in approx. 3.4:1 ratio. The enzyme is fluorescent with a maximum emission at 318-320nm. The near-u.v. circular dichroism of the protein is extensively affected by binding of penicillin G, but the far u.v. is unaffected. Binding of the antibiotic also causes quenching of the fluorescence of the enzyme. The latter effect has been used to study the binding of penicillin G to the enzyme and the influence exerted upon it by salts, denaturants and peptide substrates and inhibitors. High-affinity binding of penicillin appears to be comparatively slow and reversible, and can occur under conditions in which the protein is enzymically inactive. The thermal denaturation of the enzyme in guanidinium chloride at pH7 is affected by binding of the antibiotic. The presence of even large concentrations of beta-mercaptoethanol neither impaired the activity of the enzyme nor prevented its inhibition by penicillin G or cephalosporin C. A new hypothesis for the molecular mechanism of the interaction of the enzyme with penicillin is proposed. [less ▲]

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See detailLa fluorescence chlorophyllienne au service des productions végétales
Eyletters, Muriel; Ooms, David ULg; Destain, Marie-France ULg

in Biofutur (2010), (308), 46-48

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See detailLa fluorescence des vapeurs
Swings, Polydore ULg

in Revue Générale des Sciences Pures et Appliquées (1932), 43(juillet), 1-24

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See detailFluorescence in astronomy
Swings, Polydore ULg

in Leaflet - Astronomical Society of the Pacific (1943), 4(175), 192-198

Detailed reference viewed: 16 (3 ULg)