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See detailInvestigation of defect levels in Mg-doped GaN Schottky structures by thermal admittance spectroscopy
Nguyen, Ngoc Duy ULg; Germain, Marianne; Schmeits, Marcel et al

in Physica Status Solidi B. Basic Research (2001), 228

Schottky structures based on Mg-doped GaN layers grown by metalorganic chemical vapor deposition (MOCVD) on sapphire substrate are studied by thermal admittance spectroscopy from 90 K to room temperature ... [more ▼]

Schottky structures based on Mg-doped GaN layers grown by metalorganic chemical vapor deposition (MOCVD) on sapphire substrate are studied by thermal admittance spectroscopy from 90 K to room temperature. Evidence of two impurity levels results from the analysis of the observed peaks in the conductance curves, whose positions and strengths are temperature dependent. The experimental results are analyzed within a detailed theoretical study of the steady-state and small-signal electrical characteristics of the structure. Numerical simulations are based on the solution of the basic semiconductor equations for the structure consisting of two Schottky diodes connected back-to-back by a conduction channel formed by the GaN layer. [less ▲]

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See detailInvestigation of defect levels in Mg-doped GaN Schottky structures by thermal admittance spectroscopy
Nguyen, Ngoc Duy ULg; Germain, Marianne; Schmeits, Marcel et al

in Ponce, Fernando; Bell, Abigail (Eds.) ICNS-4: Proceedings of The Fourth International Conference on Nitride Semiconductors (2001)

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See detailInvestigation of differential virus transmission efficiency in aphid strains: from biological to proteomic assays
Bosquée, Emilie ULg; Francis, Frédéric ULg

Poster (2014, June)

Aphids are well known for their variable efficiency in virus transmission to host plant. Not only aphid species but also aphid strain is an important factor to consider in the plant-aphid-virus ... [more ▼]

Aphids are well known for their variable efficiency in virus transmission to host plant. Not only aphid species but also aphid strain is an important factor to consider in the plant-aphid-virus interactions. In order to investigate these relations, different approaches should be developped from biological observations assessing the virus transmission efficiency to molecular tasks to better know the involved mechanisms in the aphid vector. After a period of virus acquisition on an artificial diet (depending on the kind of transmission, permanent or non permanent ways), the virus transmission rate were assayed and followed by the determination of the presence of virus in the aphid by PCR or immudetection. The aphids were then collected to investigate the variation of aphid proteome and potential involvement in virus interactions. Changes in protein expressions were investigated using a 2D-DIGE approach comparing most and least efficient aphid strains selecting different aphid – virus models (PVY and PLRV in potato, BYDV in wheat, CMV on tobacco) . The proteome changes were analysed using the samespot software. Protein spots with significant up- and down expressions were then mechanically picked, trypsin digested and analysed by Maldi-Tof-Tof. Significantly changed proteins were classify according to metablic pathways and biological functions. Interesting proteins found to probably interact with virus were not only detected from aphid but also from related bacterial symbionts. Theses results were discussed in order to better understand virus – vector relations and potentially promote new ways to control virus transmitted by hemipteran pest. [less ▲]

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See detailInvestigation of DyBa2CU3O7-d superconducting domains grown by the infiltration technique starting with small size Dy-211 particles
Mathieu, Jean-Philippe; Koutzarova, T.; Rulmont, André ULg et al

in Superconductor Science and Technology (2005), 18(2 Sp. Iss. SI), 136-141

An infiltration and growth process is here used as an alternative to the classical top-seeded melt-textured growth process for the production of Dy-123 single-domains with finely dispersed small size Dy ... [more ▼]

An infiltration and growth process is here used as an alternative to the classical top-seeded melt-textured growth process for the production of Dy-123 single-domains with finely dispersed small size Dy-211 particles. The starting materials are the 211-particles and a barium and copper rich liquid phase precursor. The infiltration and growth process allows for controlling both the spatial and size distribution of the 211-particles in the final superconducting 123-single-domain. The main parameters (set-ups, maximum processing temperature with respect to the peritectic temperature, nature of reactant, porosity of the 211-preform) of the infiltration and growth process are discussed. Moreover, different processes of chimie douce are shown in order to produce Dy-211 particles with controlled shape and size, particles that can be used as precursors for the infiltration and growth process. [less ▲]

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See detailInvestigation of edge effect on wood density in recent tropical forest edges in Yangambi Man and Biosphere Reserve
de Haulleville, Thalès ULg; Bogaert, Jan ULg; Beeckman, Hans

Conference (2013, April)

Rapid development of lumbering activities in tropical forested areas has an important impact on carbon stocks and landscape configuration. Indeed, lumbering tend to fragment forest patches, extend edges ... [more ▼]

Rapid development of lumbering activities in tropical forested areas has an important impact on carbon stocks and landscape configuration. Indeed, lumbering tend to fragment forest patches, extend edges length, and expose core areas to non-forested ecosystems. These exposed core areas then undergo new constraints that can lead to a shift in their ecological features, called the edge effect. We investigate the possible presence of an edge effect on wood density in Yangambi reserve. Wood density (along with diameter and height) is a key feature for biomass estimations in tropical forests. Thus, fluctuations of wood density in forest edges could lead to incorrect estimations of carbon stocks. Ten 1ha plots were installed in core and recent (5 to 10 years) forest¿s edges. Trees were measured and wood samples were collected for density analysis. We focused on 2 main research questions: 1) Does the edge effect induce the emergence of species with a higher or lower wood density in edge area? 2) Does wood density differ amongst individuals of the same specie in core and in edge area? While the data is still being explored as we write, preliminary results seem to indicate that there is no significant difference between the overall mean wood density in edge and core plots. Density differences amongst species are still under exploration. If this behaviour still holds, this would imply that the fragmentation of a forested landscape has no short-term effect on the overall forest wood density and thus, no effect on biomass estimations. [less ▲]

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See detailInvestigation of eighteenth-century Prussian blue pigments by PDF analysis
Samain, Louise ULg; Martinetto, Pauline; Bordet, Pierre

Poster (2012, October 30)

Prussian blue, a hydrated iron(III) hexacyanoferrate(II) complex, is a synthetic pigment discovered in Berlin in 1704. Because of both its highly intense color and its low cost, Prussian blue was widely ... [more ▼]

Prussian blue, a hydrated iron(III) hexacyanoferrate(II) complex, is a synthetic pigment discovered in Berlin in 1704. Because of both its highly intense color and its low cost, Prussian blue was widely used as a pigment in paintings until the 1970's. The early preparative methods were rapidly recognized as a contributory factor in the fading of the pigment [1], a fading already known by the mid-eighteenth century. The eighteenth-century methods are based on the calcination of dried blood to produce a potassium hexacyanoferrate complex, which is the first of two essential reactants for synthesizing Prussian blue. The second reactant is an iron salt. We successfully reproduced two typical eighteenth-century empirical recipes [2]. The resulting pigments were of variable color quality, ranging from intense blue to blue-gray or blue-green, and exhibit broadened or inexistent Bragg peaks. High-energy powder X-ray diffraction experiments were performed at the ID11 beamline at ESRF, Grenoble, France. The pair distribution function (PDF) of the pure Prussian blue pigments was refined with a three-phase model, in order to take into account the vacancy distribution in the unit cell of Prussian blue. In certain ancient Prussian blues, the PDF analysis revealed the presence of nanocrystalline ferrihydrite, Fe10O14(OH)2, and also identified the presence of alumina hydrate, Al10O14(OH)2, with a particle size of ca. 15 Å. Paint layers prepared from these ancient pigments subjected to accelerated ageing showed a tendency to turn green, a tendency that was often reported in eighteenth- and nineteenth-century books. The presence of particles of hydrous iron(III) oxides was also observed in a genuine Prussian blue sample obtained from an eighteenth-century polychrome sculpture. [1] Kirby, J.; Saunders, D. The National Gallery Technical Bulletin 2004, 25, 73. [2] Dossie, R. The Handmaid to the Arts; Nourse, J.: London, 1758; Le Pileur d'Apligny, M. Traité des couleurs matérielles et de la manière de colorer relativement aux différents arts et métiers; Saugrain et Lamy: Paris, 1779. [less ▲]

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See detailInvestigation of Epstein-Barr virus (EBV) prevalence in thyroid carcinomas in Tunisia
Trimeche, Mounir; Ziadi, Sonia; Hachana, Mohamed Ridha ULg et al

in Virchows Archiv : An International Journal of Pathology (2007)

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See detailInvestigation of Epstein-Barr virus in Tunisian breast carcinomas
Hachana, Mohamed Ridha ULg; Amara, Khaled; Ziadi, Sonia et al

in Pathology - Research & Practice (2011), 207(11), 695-700

Breast carcinoma is a major cause of death among women, and the potential implication of viruses in its pathogenesis remains worth a hypothesis. The potential role of Epstein-Barr virus (EBV) in its ... [more ▼]

Breast carcinoma is a major cause of death among women, and the potential implication of viruses in its pathogenesis remains worth a hypothesis. The potential role of Epstein-Barr virus (EBV) in its pathogenesis is still a subject of continued discussion and investigation. The aim of this study was to evaluate the prevalence of EBV in sporadic breast cancers in Tunisia, and to determine the clinicopathological characteristics of virus-positive cases. Viral presence has been evaluated by polymerase chain reaction (PCR), in situ hybridization, and immunohistochemistry investigated on tumor tissues and their corresponding normal breast tissues collected from 123 Tunisian women with sporadic breast carcinomas. Viral status in tumors was then correlated with various clinicopathological parameters. Using specific PCR assays, EBV DNA was found in 33 (27%) out of 123 breast carcinoma cases. EBV-encoded small RNAs (EBERs) in situ hybridization was negative in the neoplastic cells, but stomal lymphocytes were positive in 4 cases. Immunohistochemistry for latent membrane protein 1 (LMP1) was negative in all cases. None of the normal breast tissues showed positive results for EBV using PCR, in situ hybridization, and immunohistochemistry. A correlation was found between EBV DNA presence and the negativity of estrogen receptor (P=0.008). However, no significant correlation was found for the other parameters investigated, including patient age, Scarff-Bloom-Richardson (SBR) histological grade, tumor size, and histological node involvement. With regard to survival data, overall and disease-free survivals were shorter in EBV-positive breast carcinoma cases than in EBV-negative ones, but this difference did not reach statistical significance. Our study indicates the presence of EBV DNA in a significant proportion of breast cancer in Tunisia. Further studies are required to elucidate the role of this virus in breast carcinogenesis. [less ▲]

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See detailInvestigation of factors influencing levels of trace metals using stable isotope analysis.
Bustamante, Paco; Das, Krishna ULg; Caurant, Florence

Poster (2006)

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See detailInvestigation of fuel oil flames by means of Emission Spectroscopy
Ngendakumana, Philippe ULg

in 5th International Conference on Technologies and Combustion for a Clean Environment (1999, July)

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See detailInvestigation of germinal centres in vivo and in vitro in the context of prion disease
Demonceau, C.; Defaweux, Valérie ULg; Flandroy, S. et al

Poster (2005, April)

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See detailInvestigation of height-resolved information in ground-based high-resolution Fourier infrared solar spectra above the Jungfraujoch
Barret, Brice; De Mazière, Martine; Demoulin, Philippe ULg et al

in Proceedings of the Quadriennal ozone symposium - Sapporo 2000 (2000)

Vertical profiles of HF, O3, and HNO3 have been retrieved from high-resolution solar spectra recorded at the Jungfraujoch observatory (Swiss Alps, 46.5°N latitude, 8.0°E longitude, 3.58 km altitude). Two ... [more ▼]

Vertical profiles of HF, O3, and HNO3 have been retrieved from high-resolution solar spectra recorded at the Jungfraujoch observatory (Swiss Alps, 46.5°N latitude, 8.0°E longitude, 3.58 km altitude). Two algorithms for the retrieval of vertical concentration profiles based on the Optimal Estimation Method have been used. The results of the vertical profile retrievals are compared to the Halogen Occultation Experiment (HALOE) profiles, to the Cryogenic Infrared Spectrometers and Telescope (CRISTA2) second mission (August 1997) profiles for HNO3 and O3 and also to nearby ozone sondes and lidar profile for O3. [less ▲]

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See detailInvestigation of human JC and BK polyomaviruses in breast carcinomas
Hachana, Mohamed Ridha ULg; Amara, Khaled; Ziadi, Sonia et al

in Breast Cancer Research and Treatment (2011)

We have previously showed the presence of the simian virus 40 (SV40) and the mouse mammary tumor virus (MMTV)-like in a significant proportions of Tunisian breast carcinomas. However, to date there are no ... [more ▼]

We have previously showed the presence of the simian virus 40 (SV40) and the mouse mammary tumor virus (MMTV)-like in a significant proportions of Tunisian breast carcinomas. However, to date there are no published studies concerning evaluation of the possible implication of the human polyomaviruses JC (JCV) and BK (BKV) in breast carcinomas. The presence of JCV and BKV DNA was investigated by PCR in a 123 primary breast carcinomas and matched adjacent non-tumor breast tissues. The results were correlated to clinicopathological and virological parameters. JCV T-antigen DNA was detected in 23% of breast carcinoma cases; however, all cases were negative for BKV. JCV T antigen PCR products were further confirmed as authentic JCV genome by direct sequencing. JCV was found in invasive ductal carcinomas (28/112 cases) but not in invasive lobular carcinomas (0/5) or medullary carcinomas (0/6). JCV DNA presence correlates inversely with the expression of estrogen (P = 0.022) and progesterone (P = 0.008) receptors. JCV DNA presence correlates also with "triple negative" phenotype (P = 0.021). With regard to virological data, a trend toward an inverse correlation was noted between the presence of JCV and SV40 (P = 0.06). Moreover, significant correlation was found between multiple viral infection (JCV, and/or SV40, and/or MMTV-like in the same tumor) and "triple negative" phenotype (P = 0.001) and also with p53 accumulation (P = 0.028). To the best of our knowledge, this is the first study demonstrating the presence of JCV in a subset of breast carcinomas. Also our results suggest that "triple negative" breast carcinomas are viral-related tumors. [less ▲]

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See detailInvestigation of human papillomavirus (HPV) in breast cancer among women from Tunisia
Trimeche, Mounir; Hachana, Mohamed Ridha ULg; Ziadi, Sonia et al

in Virchows Archiv : An International Journal of Pathology (2007)

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See detailInvestigation of human papillomavirus in bladder cancer in a series of Tunisian patients
Ben Selma, Walid; Ziadi, Sonia; Ben Gacem, Riadh et al

in Pathology - Research & Practice (2010), 206(11), 740-743

Background: Association between human papillomavirus (HPV) infection and the development of bladder cancer is variable. Furthermore, the prevalence of HPV DNA in bladder carcinoma subtypes varies from ... [more ▼]

Background: Association between human papillomavirus (HPV) infection and the development of bladder cancer is variable. Furthermore, the prevalence of HPV DNA in bladder carcinoma subtypes varies from study to study. To clarify the impact of HPV infection on the development of bladder carcinoma, we performed a retrospective study on Tunisian patients for the status of HPV infection in urothelial carcinoma, squamous cell carcinoma and adenocarcinoma. Methods: A total of 125 formalin-fixed, paraffin-embedded archival tissue of bladder carcinoma were reviewed and classified according to the World Health Organization (WHO) classification of tumors (119 urothelial carcinomas, five squamous carcinomas and one adenocarcinoma). Anogenital HPV DNA detection was performed with three different polymerase chain reaction (PCR) techniques. The first one, using primers pU-2R/pU-1M specific to high-risk oncogenic HPV. The second one, using primers PU-2R/PU-31B specific to low-risk oncogenic HPV and the third one, employing consensus primers (E1-547R/E1-350L). Results: No evidence of HPV infection was detected by morphological examination and PCR in any case of bladder carcinoma. Conclusion: Our study shows that anogenital HPV investigated are not associated with the pathogenesis of bladder cancer in Tunisia, however, the possibility that other subtypes of HPV contribute to bladder carcinogenesis remains to be clarified. [less ▲]

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See detailInvestigation of interactions between phospholipids, cholesterol and surfactin by atomic force microscopy and differential scanning calorimetry
Eeman, Marc; Nylander, Tommy; Dufrêne, Yves et al

Poster (2006)

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See detailInvestigation of Ion Mobility coupled with mass spectrometry (IMMS) for the screening of pesticide residues in food
Goscinny, Séverine ULg; Touilloux, Romain; Joly, Laure et al

Conference (2011, June)

Detailed reference viewed: 27 (1 ULg)