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Search Results: 1 - 10 of 28835 matches for " Jean-Marie Herrmann "
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Photocatalytic degradation of reactive dye RED-3BA in aqueous suspension under UV-visible light
Nguyen Thi Dung,Nguyen Van Khoa,Jean-Marie Herrmann
International Journal of Photoenergy , 2005, DOI: 10.1155/s1110662x05000024
Abstract: The photo-catalytic degradation efficiency of several commercial titania powders (Degussa P-25 and Ishihara Sangyo ST-01) and of TiO2 supported on diatomite were investigated in the degradation of a reactive dye (RED-3BA) under UV-Visible light. The observed rate constant for Degussa P-25 was found to be higher than that achieved by using Ishihara Sangyo ST-01 (kobs=3.3×10−2min−1 for Degussa P-25 and 4×10−4min−1 for Ishihara Sangyo ST-01). This could be related to the amount of basic hydroxyl groups on the surface of TiO2 particles as shown in the IR spectra. TiO2 Degussa P-25 supported on diatomite was prepared by dip-coating method. The photo-catalytic activity of supported TiO2 was twice smaller than TiO2 Degussa P-25 (kp-25=3.3×10−2min−1;kp25/diatomite=1.6×10−2min−1). The higher surface areas of ST-01 and the TiO2/diatomite could not lead to a higher degradation rate and to a higher degree of mineralization but TiO2/diatomite could be separated more promptly and more easily from the solution. The effect of pH was investigated in the range 4–9. Acidic (pH = 4) medium was found to favor the adsorption and degradation rate with P-25 particles.
Photocatalytic Degradation of Polynitrophenols on Various Commercial Suspended or Deposited Titania Catalysts Using Artificial and Solar Light
Hinda Lachheb,Ammar Houas,Jean-Marie Herrmann
International Journal of Photoenergy , 2008, DOI: 10.1155/2008/497895
Abstract: Phenol (PH) and three polynitrophenols (4-nitrophenol (PNP), 2,4-dinitrophenol (DNP), 2,4,6-trinitrophenol (TNP)) were photocatalytically degraded by using titania under either artificial or solar light. These four reactions were chosen as test reactions to compare the efficiencies of two suspended commercial titania photocatalysts (Degussa P-25 and Millennium PC-500). It appears that P-25 has a higher initial efficiency in all nitrophenol disappearance reactions. However, for the overall degradation rate, measured by the chemical oxygen demand (COD) disappearance, the performance of PC-500 was similar to that of P25. This was attributed to a favorable textural effect since PC-500 has a much higher surface area which facilitates the readsorption of intermediates. PC-500 was subsequently supported on a special photoinert paper provided by Ahlstrom Company (38-Pont Ev ¨que, France). The influence of the silica binder used for sticking titania particles on the paper fibers was put in evidence as an inhibitor of the coulombic adsorption of anionic species, especially 2,4,6-trinitrophenol, because of the low pzc of silica. Once validated, this supported photocatalyst was introduced in an autonomous solar pilot photoreactor identical to the several prototypes built in the European AQUACAT program. It was demonstrated that the purification of water could be efficiently obtained in a larger scale without any final tedious filtration.
Nano/Molecular Photosciences and Clean Energy
Mohamed Sabry Abdel-Mottaleb,Jean-Marie Herrmann
International Journal of Photoenergy , 2008, DOI: 10.1155/2008/734364
Design of Printed Dipole Array for Omnidirectional Radiation Pattern  [PDF]
Jean-Marie Floc’h
Wireless Engineering and Technology (WET) , 2019, DOI: 10.4236/wet.2019.102002
Abstract: In this paper, we describe 2 kinds of printed dipole arrays and compare the performances of these arrays in term of reflexion coefficient, radiation pattern and dimensions. It is interesting to design array in order to obtain better performances in term of omnidirectional radiation pattern in comparison with single element. We choose this elementary source in order to obtain compact array with good performances. These antenna arrays are designed to have omnidirectional radiation pattern with horizontal polarization. We present an application dedicated to compact base station in the last section.
Why inorganic salts decrease the photocatalytic efficiency
Chantal Guillard,Eric Puzenat,Hinda Lachheb,Ammar Houas,Jean-Marie Herrmann
International Journal of Photoenergy , 2005, DOI: 10.1155/s1110662x05000012
Abstract: Methylene Blue (MB) has been chosen as a model molecule to evaluate the impact of inorganic salts, present in textile waste waters, on the adsorption properties and on the photocatalytic efficiency of TiO2. No OH∘ radical scavenging by anions such as NO3−, Cl−, SO42−, PO43−, and CO32− was observed at neutral and basic pH, while this phenomenon can be suggested at acidic pH for some anions except carbonate anions which are totally neutralized and/or eliminated as CO2 in these conditions. The decrease in the rate MB photocatalytic degradation in the presence of inorganic salts was shown to be due to the formation of an inorganic salt layer at the surface of TiO2, which inhibits the approach of MB molecules. The correlation between the amount of MB adsorbed and the rate of its photocatalytic degradation, whatever the nature of the salt, its concentration and the pH of the solution, indicates (i) that photocatalysis occurs at the surface and not in the solution and (ii) that OH− ions added at basic pH do not participate to the increase in the photocatalytic efficiency by inducing an increase in OH∘ formation. They increase the surface density in adsorption sites TiO−. The effect of various salts is similar on various titania samples of industrial origin (Millennium TiO2 PC 500, PC 50, and Degussa P 25). It is however more important on Millennium PC 10 probably because of its smaller surface area.
Evaluating the Performance of a Climate-Driven Mortality Model during Heat Waves and Cold Spells in Europe
Rachel Lowe,Joan Ballester,James Creswick,Jean-Marie Robine,Franois R. Herrmann,Xavier Rodó
International Journal of Environmental Research and Public Health , 2015, DOI: 10.3390/ijerph120201279
Abstract: The impact of climate change on human health is a serious concern. In particular, changes in the frequency and intensity of heat waves and cold spells are of high relevance in terms of mortality and morbidity. This demonstrates the urgent need for reliable early-warning systems to help authorities prepare and respond to emergency situations. In this study, we evaluate the performance of a climate-driven mortality model to provide probabilistic predictions of exceeding emergency mortality thresholds for heat wave and cold spell scenarios. Daily mortality data corresponding to 187 NUTS2 regions across 16 countries in Europe were obtained from 1998–2003. Data were aggregated to 54 larger regions in Europe, defined according to similarities in population structure and climate. Location-specific average mortality rates, at given temperature intervals over the time period, were modelled to account for the increased mortality observed during both high and low temperature extremes and differing comfort temperatures between regions. Model parameters were estimated in a Bayesian framework, in order to generate probabilistic simulations of mortality across Europe for time periods of interest. For the heat wave scenario (1–15 August 2003), the model was successfully able to anticipate the occurrence or non-occurrence of mortality rates exceeding the emergency threshold (75th percentile of the mortality distribution) for 89% of the 54 regions, given a probability decision threshold of 70%. For the cold spell scenario (1–15 January 2003), mortality events in 69% of the regions were correctly anticipated with a probability decision threshold of 70%. By using a more conservative decision threshold of 30%, this proportion increased to 87%. Overall, the model performed better for the heat wave scenario. By replacing observed temperature data in the model with forecast temperature, from state-of-the-art European forecasting systems, probabilistic mortality predictions could potentially be made several months ahead of imminent heat waves and cold spells.
Clustering of the Values of a Response Variable and Simultaneous Covariate Selection Using a Stepwise Algorithm  [PDF]
Olivier Collignon, Jean-Marie Monnez
Applied Mathematics (AM) , 2016, DOI: 10.4236/am.2016.715141
Abstract: In supervised learning the number of values of a response variable can be very high. Grouping these values in a few clusters can be useful to perform accurate supervised classification analyses. On the other hand selecting relevant covariates is a crucial step to build robust and efficient prediction models. We propose in this paper an algorithm that simultaneously groups the values of a response variable into a limited number of clusters and selects stepwise the best covariates that discriminate this clustering. These objectives are achieved by alternate optimization of a user-defined model selection criterion. This process extends a former version of the algorithm to a more general framework. Moreover possible further developments are discussed in detail.
Long-Term Depression in the Hippocampal CA1 Area of Aged Rats, Revisited: Contribution of Temporal Constraints Related to Slice Preparation
Jean-marie Billard
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0009843
Abstract: The effects of low-frequency conditioning stimulation (LFS, 900 pulses at 1 Hz) of glutamatergic afferents in CA1 hippocampal area using slices from two different strains of adult (3–5 month-old) and aged (23–27 month-old) rats were reinvestigated regarding the discrepancies in the literature concerning the expression of long-term depression (LTD) in the aging brain.
Les chiens s?approchent, et s?éloignent
Gleize, Jean-Marie;
Alea : Estudos Neolatinos , 2007, DOI: 10.1590/S1517-106X2007000200002
Abstract: the paper proposes a rereading of the tension between poetry and prose in baudelaire, taking as its starting point the opposition between "cats" and "dogs", recurring characters in the poet?s work. with/ against baudelaire, the author argues for an affirmation of prose - "prose in prose(s)" - and the rejection, in contemporary poetry, of any instances of the "modern sublime".
Desarrollo del derecho internacional humanitario y la continua pertinencia de la costumbre
Henckaerts, Jean-Marie;
Anuario mexicano de derecho internacional , 2010,
Abstract: treaties have been widely regarded as the main source of international law, nevertheless, historically; custom has often had certain precedence over conventions. this article presents an analysis about the importance of customary international law in the matter of humanitarian law. mostly based on the study performed by the international committee of the red cross, this work achieves a deep exploration through customary humanitarian international law and its roll in fulfilling the vacuums and avoiding the obstacles of conventional humanitarian law effectiveness.
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