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See detailInvestigation of non-covalent interactions between paramagnetic complexes and human serum albumin by electrospray mass spectrometry
Henrotte, Virginie; Laurent, Sophie ULg; Gabelica, Valérie ULg et al

in Rapid Communications in Mass Spectrometry : RCM (2004), 18(17), 1919-1924

Stable gadolinium(III) chelates are nowadays routinely used as contrast agents for magnetic resonance imaging (MRI). Their non-covalent binding to human serum albumin (HSA) has shown to improve their ... [more ▼]

Stable gadolinium(III) chelates are nowadays routinely used as contrast agents for magnetic resonance imaging (MRI). Their non-covalent binding to human serum albumin (HSA) has shown to improve their efficacy. Non-covalent interactions lead to complex formation that can be quantified by several techniques that are mostly tedious and time-consuming. In this study, electrospray ionization mass spectrometry (ESI-MS) was used to investigate the interaction between HSA and several gadolinium(III) complexes. The results were compared with those obtained in the liquid phase. Four gadolinium complexes were investigated: Gd-DTPA 1, Gd-C4Me-DTPA 2, Gd-EOB-DTPA 3, and MP-2269 4. Relaxometry studies show that complexes 1 and 2 have no significant affinity for HSA, while complexes 3 and 4 have increasing affinities for the protein. 1:1 and 1:2 complexes between HSA and MP-2269 were detected by ESI-MS for a twofold excess of the contrast agent, whereas a ligand/protein molar ratio of 4:1 was necessary to observe a 1:1 stoichiometry for Gd-EOB-DTPA, an observation that is in good agreement with the known weaker affinity of the contrast agent for the protein. At a fourfold molar excess, no supramolecular complex was observed for Gd-DTPA I and Gd-C4Me-DTPA 2; a tenfold molar excess was necessary to detect a 1:1 complex, confirming the very weak affinity of these contrast agents for HSA. [less ▲]

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See detailInvestigation of Nonlinear Aeroelasticity
Dimitriadis, Grigorios ULg

Doctoral thesis (1999)

The investigation of nonlinear aeroelastic phenomena is becoming increasingly important to the aerospace community. The existence of structural and aerodynamic nonlinearities in aircraft has always been ... [more ▼]

The investigation of nonlinear aeroelastic phenomena is becoming increasingly important to the aerospace community. The existence of structural and aerodynamic nonlinearities in aircraft has always been acknowledged but, it is only mainly with the advent of modern digital computers that their investigation has become possible. Additionally, aircraft control systems are becoming increasingly nonlinear with the introduction of Active Control Technology. The effects of these nonlinearities on the dynamic response of aircraft have created the need for further research into the modelling, identification and prediction nonlinear aeroelastic systems. This thesis deals with four aspects of nonlinear aeroelasticity. Firstly, the effect of the common industrial approach to nonlinearity, i.e. that of linearisation, is investigated. Six flutter prediction methods for linear aircraft are tested and compared on linear and nonlinear mathematical models of aeroelastic systems. The performances of the methods on linear systems are evaluated and compared. Subsequently, their predictions predictions when applied to nonlinear systems are assessed. Secondly, the dynamic response of nonlinear aircraft is investigated by means of the Harmonic Balance method and the direct integration of the nonlinear mathematical model. Emphasis is given to the explanation of the appearance of Limit Cycle Oscillations as Hopf bifurcations and on the control and suppression of these oscillations by means of a feedback control system. The chaotic vibration of nonlinear aeroelastic systems is also investigated by means of Poincare diagrams and Lyapunoff exponents. Thirdly, the identification of nonlinear aeroelastic systems is considered. Identification of aeroelastic systems is important since, especially in the case of structural nonlinearities, it is often not known whether an aircraft is linear or not and what nonlinearities it may contain until it is tested, either on the ground (Ground Vibration Testing) or in the air (Flight Flutter Testing). An existing nonlinear system identification method is compared to an approach developed during the course of the present project. The two techniques are applied to a nonlinear mathematical aeroelastic system and to a set of nonlinear input-output data obtained from an experimental system. Both methods were found to be able to deal with both systems with varying degrees of success. Finally, the gust response of nonlinear aircraft is investigated with particular emphasis on the calculation of gust design loads. Turbulent gust clearance is a very important part of any airworthiness testing procedure. Until recently, the linear assumption was considered adequate by the requirements however, there is a current shift towards setting new requirements that take into account nonlinear phenomena. Eight gust load prediction methods for nonlinear aircraft(both stochastic and deterministic) are applied to a simple and a more complex nonlinear mathematical aircraft model. The performance of the methods is assessed with respect to both accuracy and computational efficiency. [less ▲]

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See detailINVESTIGATION OF PARAMETERS AFFECTING VOLTAGE SECURITY OF THE HELLENIC INTERCONNECTED SYSTEM
Christoforidis, George; Kabouris, John; Vournas, Costas et al

(2005, August)

The Hellenic Interconnected System pre-sents a structural geographical imbalance between generation sites and load centers. This imbalance leads to bulk power transfers on long electrical distances ... [more ▼]

The Hellenic Interconnected System pre-sents a structural geographical imbalance between generation sites and load centers. This imbalance leads to bulk power transfers on long electrical distances leading to voltage stability problems. In order to improve the opera-tional practices aiming at improving the voltage security, an on-line Voltage Security Assessment tool has been installed at the National Control Center of the Hellenic Transmission System Operator that operates and controls the interconnected power system of Greece. This paper presents some indicative results obtained by the use of this tool. The analysis includes the investigation of the main parameters that affect the voltage stability of the system, such as the position of non-automatic taps of autotrans-formers, the network topology, and the spatial distribution of generation. [less ▲]

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See detailThe investigation of particle acceleration in colliding-wind massive binaries with SIMBOL-X.
De Becker, Michaël ULg; Rauw, Grégor ULg; Pittard, J. M. et al

in Memorie della Società Astronomica Italiana : Journal of the Italian Astronomical Society (2008), 79

An increasing number of early-type (O and Wolf-Rayet) colliding wind binaries (CWBs) is known to accelerate particles up to relativistic energies. In this context, non-thermal emission processes such as ... [more ▼]

An increasing number of early-type (O and Wolf-Rayet) colliding wind binaries (CWBs) is known to accelerate particles up to relativistic energies. In this context, non-thermal emission processes such as inverse Compton (IC) scattering are expected to produce a high energy spectrum, in addition to the strong thermal emission from the shock-heated plasma. SIMBOL-X will be the ideal observatory to investigate the hard X-ray spectrum (above 10 keV) of these systems, i.e. where it is no longer dominated by the thermal emission. Such observations are strongly needed to constrain the models aimed at understanding the physics of particle acceleration in CWB. Such systems are important laboratories for investigating the underlying physics of particle acceleration at high Mach number shocks, and probe a different region of parameter space than studies of supernova remnants. [less ▲]

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See detailInvestigation of potential new targets for the diagnosis and/or the treatment of osteoarthritis
Lambert, Cécile ULg; Dubuc, J.-E.; Montell, E. et al

in Osteoarthritis and Cartilage (2013, April), 21(Supplement April 2013),

Purpose: Synovial inflammation plays a key role in the pathophysiology process of osteoarthritis (OA). We have previously compared the gene expression pattern of synovial cells isolated from inflammatory ... [more ▼]

Purpose: Synovial inflammation plays a key role in the pathophysiology process of osteoarthritis (OA). We have previously compared the gene expression pattern of synovial cells isolated from inflammatory (I) or normal/reactive (N/R) areas of a synovial membrane harvested from the same OA patient. We identified a large number of mediators belonging to key pathways involved in OA pathogenesis. The aim of this study was to validate different potential new targets for the diagnosis and/or the treatment OA. Methods: Synovial cells (SC) were isolated from synovial specimens obtained from OA patients undergoing knee replacement. The inflammatory status of the synovial membrane was characterized according to macroscopic criteria. The biopsies from N/R and I areas were cultured separately for a period of 7 days. Microarray gene expression profiling between N/R and I areas was performed. The biological relevance of up- and down-regulated genes was analyzed with Ingenuity Pathways Analysis. Western blot and immunohistochemistry confirmed the identified genes most differentially expressed in the key pathways. The production of the triggering receptor expressed on myeloid cells-1 (TREM1), the alarmin S100 calcium binding protein A9 (S100A9), the wingless-type MMTV integration site family, member 5A (Wnt-5A) and the stanniocalcin 1 (STC1) were evaluated by Western blot. S100A9, hyaluronan synthase-1 (HAS1) and STC1 expression and localization were investigated by immunohistochemistry. Results: 896 genes differentially expressed in N/R and I areas were identified. The key pathways were related to inflammation, cartilage metabolism, Wnt signaling and angiogenesis. In the inflammatory gene pattern, TREM1 and S100A9 were strongly upregulated. We validated the production of these proteins in OA synovial biopsies by Western blot. TREM1 and S100A9 were increased in I compared to N/R synovial cells culture. S100A9 was observed in the perivascular area and in sublining cells in I synovial biopsies, but not in N/R biopsies. An increased staining was also observed in the intima lining layer of I when compared to N/R biopsies. The most upregulated anabolism enzyme in I synovial biopsies was HAS1. Using immunohistochemistry, we observed in I areas an increase of the HAS1-positive cells mainly in the intima lining. We also studied the protein production of Wnt-5A, the most upregulated intermediate of Wnt signaling pathway. The protein level was increased in I compared to N/R areas. Finally, in the angiogenesis pathway, one the most u-regulated gene was STC1. A significant increase of STC1 production was observed in I areas compared to N/R areas by Western blot. This result was also supported by the immunohistochemical analysis. In I area, the staining for STC1 was more intense in perivascular and sublining cells. Conclusions: Synovial membrane inflammation is a key target for OA treatments. In this work, we have identified proteins involved in the synovitis pathways like angiogenesis, cells infiltration and matrix remodeling. These proteins could be targeted by drugs and used as companion biomarkers for evaluating their efficacy. Although qualitative, our results could also yield to the identification of markers of the disease. This investigation has to be further pursued. [less ▲]

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See detailInvestigation of pregnancy-associated glycoproteins (PAGs) by means of an enzymoimunoassay (ELISA) sandwich kit for pregnancy monitoring in sheep
El Amiri, Bouchra; Delahaut, Philippe; Colemans, Yves et al

in Chentouf, M; López-Francos, A; Bengoumi, M (Eds.) et al Options méditerranéennes : Series A (2014)

The aim of the present study was to investigate the use of a PAGs ELISA-Sandwich kit (Ret. code E.G.7. CER. Marloie, Belgium) for both early pregnancy diagnosis (in Sardi sheep) and the pregnancy follow ... [more ▼]

The aim of the present study was to investigate the use of a PAGs ELISA-Sandwich kit (Ret. code E.G.7. CER. Marloie, Belgium) for both early pregnancy diagnosis (in Sardi sheep) and the pregnancy follow up (in Boujaâd and Boujaâd x D'man sheep). ln Sardi breed, plasma samples were obtained from pregnant ewes (n = 17) from day 18 to 30 of gestation at 2 days interval. ln Boujaâd (n = 8) and Boujaâd x D'man (n = 20) the blood samples were weekly collected from the first week of gestation till the 4th week after lambing. The PAG concentrations were determined by a sandwich-ELISA based on purified bovine PAG (boPAG-67 kDa) as a standard, the antiserum raised against caprine PAG (caPAG-55+62 kDa) as a capture antibody (1/40000) and antiserum raised against purified PAG from buffalo (AS 859) as detection antibody (1/32 000). The Avidin-HRP and TMB were used to reveal reactions. Ewes were assumed to be pregnant when PAG concentrations were higher than 0.8 ng/ml. Results showed that in Sardi sheep it is possible to detect ail ewes as pregnant as early as on 24 days of gestation. ln Boujaâd and Boujaâd x D'man the PAG concentrations reached the higher values just before lambing. This value is higher in ewes carrying more than one lamb than in those carrying a single lamb. To conclude, the present study shows that the ELISA kit used for early pregnancy diagnosis in sheep as weil as for pregnancy fellow up could be a good alternative to the radioimmunoassay RIA in countries where this last technique is hard to set up. [less ▲]

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See detailInvestigation of pulmonary expression of heat shock protein HSP70 in mice chronically exposed to cigarette smoke
Cheu, Esteban ULg; Steuve, J.; Fievez, Laurence ULg et al

in Proceedings: Autumn Meeting of the Belgian Society of Fundamental and Clinical Physiology and Pharmacology (2007)

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See detailInvestigation of SDS, DTAB and CTAB micelle microviscosities by electron spin resonance
Bahri, Mohamed Ali ULg; Hoebeke, Maryse ULg; Grammenos, Angeliki ULg et al

in Colloids and Surfaces A : Physicochemical and Engineering Aspects (2006), 290(1-3), 206-212

Electron spin resonance spectroscopy (ESR) of the nitroxide labelled fatty acid probes (5-, 16-doxyl stearic acid) was used to monitor the micelle microviscosity of three surfactants at various ... [more ▼]

Electron spin resonance spectroscopy (ESR) of the nitroxide labelled fatty acid probes (5-, 16-doxyl stearic acid) was used to monitor the micelle microviscosity of three surfactants at various concentrations in aqueous solution: sodium dodecyl sulphate (SDS), dodecyltrimethylammonium bromide (DTAB) and cetyltrimethylammonium bromide (CTAB). At low surfactant concentration, there is no micelle, the ESR probe is dissolved in water/surfactant homogeneous phase and gives his microviscosity. At higher surfactant concentration, an abrupt increase in microviscosity indicates the apparition of micelles and, the solubilization of the probes in micelles. The microviscosity of the three surfactants, in a large surfactant range, was obtained as well as the critical micelle concentration (CMC). The microviscosity increased slightly with the increase in surfactant concentration. Phosphate buffer lowered the CMC value and generally increased the microviscosity. (c) 2006 Elsevier B.V. All rights reserved. [less ▲]

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See detailInvestigation of shear stress evolution during neotissue growth in a perfusion bioreactor using 3d multiphysics modeling
Guyot, Yann ULg; Papantoniou, Ioannis; Schrooten, Jan et al

Conference (2014, October)

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See detailInvestigation of singlet oxygen reactivity towards propofol
Heyne, Belinda; Kohnen, Stephan ULg; Brault, Daniel et al

in Photochemical & Photobiological Sciences (2003), 2(9), 939-945

The reaction between the anaesthetic agent 2,6-diisopropylphenol (propofol, PPF) and singlet oxygen (1O2) has been investigated in aqueous solution by means of HPLC, GC, absorption spectroscopy and laser ... [more ▼]

The reaction between the anaesthetic agent 2,6-diisopropylphenol (propofol, PPF) and singlet oxygen (1O2) has been investigated in aqueous solution by means of HPLC, GC, absorption spectroscopy and laser flash photolysis with infrared luminescence detection. The rate constants for the physical and chemical quenching of 1O2 by PPF (kPPF) are found to be 2.66 x 10(5) M(-1) s(-1) and approximately 3.2 x 10(6) M(-1) s(-1) in CD3OD and D2O-CD3OD (75:25 v/v), respectively. The reaction of propofol with singlet oxygen produced by light irradiation of Rose Bengal leads essentially to two reaction products, 2,6-diisopropyl-p-benzoquinone and 3,5,3',5'-tetraisopropyl-(4,4')-diphenoquinone that are unambiguously identified from comparison with authentic samples. [less ▲]

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See detailInvestigation of soil degradation by means of an opto-electronic microreliefmeter
Destain, Marie-France ULg; Descornet, G.; Roisin, C. et al

in Soil & Tillage Research (1989), 13(3), 299-315

To investigate the behaviour of seedbeds as affected by climatic stresses, under the dependance of different systems of organic improvements, an opto-elctronic device was used, presenting a high ... [more ▼]

To investigate the behaviour of seedbeds as affected by climatic stresses, under the dependance of different systems of organic improvements, an opto-elctronic device was used, presenting a high resolution capacity and good rapidity. The contactless measurements ditrectly recorded in a computer have been repeated at different times exactly at the same place in the field. A complete statistical analysis by means of spectrum analysis gave accurate information about the behaviour of clods of different size. The differentiated evolution of the soil surface according to climatic stresses (frost and rainfall) was noted. The influence of organic and/or mineral improveemnts appeared clearly too. [less ▲]

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See detailInvestigation of spectral impacts on the performance of a concentration device using a Fresnel lens combined with a double junction cell
Loicq, Jerôme ULg; Galante, Nicolas ULg; Thibert, Tanguy ULg et al

in Proc. SPIE 9140, Photonics for Solar Energy Systems V, 91400T (2014, May 15)

This experimental study was carried out within the context of high concentration photovoltaics. The paper presents the results of an experimental investigation relating to the quantification of the ... [more ▼]

This experimental study was carried out within the context of high concentration photovoltaics. The paper presents the results of an experimental investigation relating to the quantification of the impacts of the chromatic effect on the performance of a double junction GaInP/GaAs solar cell. Chromatic effects are the result of material dispersion caused by the refractive optics component. This study aims to evaluate the effect of the spectral modification of the incident beam on the whole solar concentrator system performance. Such considerations are fundamental in producing a highly accurate design, with which to achieve the best possible system performance. Efficiency is evaluated within the vicinity of the focus of a Fresnel lens designed for concentration. On the optical axis, rays with different wavelengths are not focalized at the same points. The spectral content of the beam depends, therefore, upon the position of the cell along the optical axis. It is assumed that spectral content modification may have an impact on cell performance and, as a consequence, on system efficiency as a whole. Efficiency of the optical Fresnel lens and of the cell were evaluated in relation to spectral content modification. [less ▲]

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See detailInvestigation of Structure-Fundamental/Functional Property Relationships of (Bio)-surfactants for a Rational Design of their Preparation and Use in Food and Non-food applications
Razafindralambo, Hary ULg

Conference (2012, May 01)

(Bio)-surfactants are among the most versatile compounds in our planet, either in nature or in biological systems, as well as in manufactured products. Increasing knowledge on the relationships between ... [more ▼]

(Bio)-surfactants are among the most versatile compounds in our planet, either in nature or in biological systems, as well as in manufactured products. Increasing knowledge on the relationships between their structure, fundamental properties, and functionalities in simple, and thereafter in more complicated models, are therefore the key factor on their rational preparation and use for any applications. In the present communication, the effect of different structural entities of (bio)surfactants, especially Carbohydrate-based amphiphilic compounds, including monomeric, oligomeric, and polymeric surfactants, on their interfacial properties at short time (under dynamic conditions) and long time (at the equibrium), and the impact of such fundamental properties through physico-chemical parameters on the formation and stability of colloidal systems (micelles, foams, emulsions) will be presented. Some perspectives in their applications will be discussed. [less ▲]

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See detailInvestigation of sudden death of calves after epileptic seizures due to hypomagnesaemia and hyperparathyroidism
Chevalier, Marine ULg; Lebreton, Pascal; Garnier, Catherine et al

in Revista Portuguesa de Buiatria (2012, June), (Special Edition),

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See detailInvestigation of the best suture pattern to close a stuffed Christmas turkey
Verwilghen, Denis ULg; Busoni, Valeria ULg; Van Galen, Gaby ULg et al

in Veterinary Record : Journal of the British Veterinary Association (2011), 169(26), 685-686

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See detailInvestigation of the Biological Activity and the Environmental Impact of Tunisian MSW Landfills
Mhiri, F.; Marouani, L.; Benzarti, A. et al

in Christensen; Cossu; Stegmann (Eds.) Proceedings Sardinia 03, Ninth International Waste Management and Landfill Symposium (2003)

This paper presents the results of the investigation of the biological activity that takes place in three municipal solid waste landfills (MSW landfills) situated in different regions of two dry climate ... [more ▼]

This paper presents the results of the investigation of the biological activity that takes place in three municipal solid waste landfills (MSW landfills) situated in different regions of two dry climate in Tunisia. Since the climatic water balance is negative (potential evapotranspiration being 1.5 to 5 times higher than rainfall), it has often been considered that this kind of landfill has neither environmental impact nor efficient biological activity. However, the three landfills revealed a biological activity with biogas often containing more than 60 percent of methane. Indeed, the upper waste layer that was effectively dry (dry weight from 85 to 98%), the core of refuse contained between 35 and 65% of dry matter. In some boreholes, the produced gases periodically expelled leachates like small geysers. Therefore, the results assess that landfill management in countries with dry climate should be considered with adapted technologies, not necessary the same as under temperate or humid climates. [less ▲]

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