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Search Results: 1 - 10 of 408509 matches for " Elói S. Garcia "
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Absorbing photonic crystals for thin film photovoltaics
O. El Daif,E. Drouard,G. Gomard,X. Meng,A. Kaminski,A. Fave,M. Lemiti,E. Garcia Caurel,P. Roca i Cabarrocas,S. Ahn,H. Jeon,C. Seassal
Physics , 2010, DOI: 10.1117/12.854035
Abstract: The absorption of thin hydrogenated amorphous silicon layers can be efficiently enhanced through a controlled periodic patterning. Light is trapped through coupling with photonic Bloch modes of the periodic structures, which act as an absorbing planar photonic crystal. We theoretically demonstrate this absorption enhancement through one or two dimensional patterning, and show the experimental feasibility through large area holographic patterning. Numerical simulations show over 50% absorption enhancement over the part of the solar spectrum comprised between 380 and 750nm. It is experimentally confirmed by optical measurements performed on planar photonic crystals fabricated by laser holography and reactive ion etching.
Estudi de la dependència energètica de les diferències entre jets de quarks i gluons utilitzant el detector DELPHI de LEP
S. Marti i Garcia
Physics , 1995,
Abstract: Three jet events arising from decays of the $Z^0$ boson, collected by the DELPHI detector at LEP, were used to measure differences in the properties of quark and gluon jet fragmentation. Gluon jets were anti-tagged in $b\bar{b}g$ events, by identifiying $b$ quark jets with high purities. Unbiased quark jets came from events $q\bar{q}\gamma$ with two jets plus one photon. A comparison of quark and gluon jet properties in different energy ranges was performed for the first time and within the same detector. The average value of the ratio of the mean charged multiplicities of gluon and quark jets was measured to be \[ 1.232 \pm 0.026 (\mbox{esta.}) \pm 0.018 (\mbox{sist.}) \] where the fraction of b-quark initiates jets was 11\% and the Durham jet finding algorithm has been used for the selection of three jet events. In agreement with QCD an increase of this ratio with energy was observed at a $3\sigma$ level. A further dependence of this ratio related with the angular acceptance of the algorithm used to reconstruct jets was also measured. Gluon jets have a broader energy and particle flow around its jet axis than quark jets of equivalent energy. The string effect has been observed in fully symmetric three-jet events. The ratio $R_\gamma$ of the charged particles flow in the $q\bar{q}$ inter-jet region of the $q\bar{q}g$ and $q\bar{q}\gamma$ samples was measured in agreement with the perturbative QCD expectation \[ \frac{(N_{qq})_{q\bar{q}g}}{(N_{qq})_{q\bar{q}\gamma}} = 0.058 \pm 0.06 (\mbox{stat.+sist.}) \] The dependence of the mean charged multiplicity on the hadronic center-of-mass energy was analysed in photon plus $n$-jet events. A value for
Review of the measurements of the strong coupling constant at LEP 2
S. Marti i Garcia
Physics , 1997,
Abstract: Since 1995, LEP has steadily increased the center of mass energy of the colliding beams, from the M_Z resonance to 133, 161 and 172 GeV. New measurements of the strong coupling constant, alpha_s, at these energies have been performed by the LEP experiments, L3, ALEPH, OPAL and DELPHI. In this article, the new results are summarized, and combined with the previous LEP measurement of alpha_s(M_Z) in order to obtain an updated LEP average of alpha_s(M_Z) = 0.120 +- 0.005.
Biodiesel Production from Spirulina-Platensis Microalgae by In-Situ Transesterification Process  [PDF]
H. I. El-Shimi, Nahed K. Attia, S. T. El-Sheltawy, G. I. El-Diwani
Journal of Sustainable Bioenergy Systems (JSBS) , 2013, DOI: 10.4236/jsbs.2013.33031
Abstract:

This research investigates the effect of reaction variables that strongly affect the cost of biodiesel production from non-edible Spirulina-Platensis microalgae lipids, and use the acid-catalyzed in situ transesterification process. Experiments were designed to determine how variations in volume of reacting methanol, the concentration of an acid catalyst, time, temperature and stirring affected the biodiesel yield. The total lipid content of Spirulina-Platensis microalgae was obtained to be 0.1095g/g biomass. The weight of the by-product glycerol obtained was used to predict the percentage yield conversion of microalgae oil biodiesel. Best results (84.7%), a yield of fatty acid methyl ester (FAME), were obtained at 100% (wt./wt.oil) catalyst concentration, 80 ml methanol volumes, 8 h reaction time and 65℃ reaction temperature with continuous stirring at 650 rpm. Properties of the produced biodiesel were measured according to EN 14214 standards.

Removal of Cesium on Polyaniline Titanotungstate as Composite Ion Exchanger  [PDF]
I.M. El-Naggar, E. S. Zakaria, I. M. Ali, M. Khalil, M. F. El-Shahat
Advances in Chemical Engineering and Science (ACES) , 2012, DOI: 10.4236/aces.2012.21020
Abstract: Polyaniline titanotungstate (PATiW) was synthesized by the sol-gel method. Adsorption isotherm studies of Cs+ from aqueous solution are described. Elemental Composition, chemical solubility, ion-exchange capacity (IEC) and pH titration are studied. Distribution coefficients (Kd) for ten metal ions have been determined. It was found that the polyaniline titanotungstate has high affinity and high selectivity for Cs+. The material was high separation of Cs+ from other metal ions. The adsorbent capacity was determined using the Freundlich and Langmuir adsorption isotherm models. The Cs+ adsorption isotherm data fit best to the Freundlich isotherm model. The maximum Cs+ uptake of polyaniline titanotungstate was found 217 mg/g. A column tests were performed to determine the breakthrough curves with varying bed depths and flow rates in different solutions. The results show that the half breakthrough time increases proportionally with increasing bed depths. Kinetic studies for removal cesium from milk were investigated.
ELECTROCHEMICAL STUDIES AND EXTRACTION OF CHEMICAL AND ELECTROCHEMICAL PARAMETERS OF ZN(II) ION AT MERCURY ELECTRODE VIA CONVOLUTIVE VOLTAMMETRY AND DIGITAL SIMULATION METHODS
EL-HALLAG,I. S;
Journal of the Chilean Chemical Society , 2010, DOI: 10.4067/S0717-97072010000300023
Abstract: the electrochemical behaviour of zn(ii) ion as example of creveirr system was studied at hanging mercury drop electrode in aqueous solution in the presence of im kcl using cyclic voltammetry and convolutive voltammetry methods. digital simulation technique was used to test the chemical and electrochemical parameters of zn(ii) ion estimated experimentally as well as verifying the proposed electrode mechanism.
New soliton solutions of some important nonlinear systems via He's variational principle
S. I. El-Ganaini
International Journal of Mathematical Analysis , 2012,
Abstract:
ELECTROCHEMICAL STUDIES AND EXTRACTION OF CHEMICAL AND ELECTROCHEMICAL PARAMETERS OF ZN(II) ION AT MERCURY ELECTRODE VIA CONVOLUTIVE VOLTAMMETRY AND DIGITAL SIMULATION METHODS
I. S EL-HALLAG
Journal of the Chilean Chemical Society , 2010,
Abstract: The electrochemical behaviour of Zn(II) ion as example of CrevEirr system was studied at hanging mercury drop electrode in aqueous solution in the presence of IM KCl using cyclic voltammetry and convolutive voltammetry methods. Digital simulation technique was used to test the chemical and electrochemical parameters of Zn(II) ion estimated experimentally as well as verifying the proposed electrode mechanism.
Olive Mill Wastewaters: Diversity of the Fatal Product in Olive Oil Industry and its Valorisation as Agronomical Amendment of Poor Soils: A Review
S. Hanifi,I. El Hadrami
Journal of Agronomy , 2009,
Abstract: Discharge of olive mill wastewaters is known to have adverse effects on environment. Several scientific treatment technologies were proposed for these effluents. However, they are limited by some economical and technical constraints. Olive mill wastewaters direct agronomical recycling is both classical and innovative alternative for removal of these pollutant effluents. However, this procedure can still not be recommended as safe practice because data is often inconsistent and the physico-chemical characteristics of olive mill wastewaters are not the same depending on several intrinsic and extrinsic aspects. This review compiles and discusses the results of studies conducted worldwide over the last two decades on the effects of olive mill wastewaters as soil amendment. It particularly focuses on OMW associated eco-toxicity and the capability of the biotic and abiotic components of soils to overcome it. Moreover, it explores olive mill wastewaters bio-transformation in soils and also their potential environmental impact.
Tocopherols and flavonoids of SOS-7 halophyte
El-Shami, S. M.,El-Negoumy, S. I.
Grasas y Aceites , 1993,
Abstract: Halophyte is an oil seed coded as SOS-7 (Salicomia Oil Seed, 7th year of selection). Tocopherol constituents of SOS-7 halophyte oil were determined directly in the oil by using high pressure liquid chromatography coupled to fluorescence detector. It was found that the oil contains 710 ppm total tocopherols. The tocopherol constituents, alpha, beta, gamma and delta, were found at the level of 38.2,1.0, 58.7 and 2.1% respectively. Nine flavonoid glycosides were isolated and identified from the seeds and it was found that they belong to the flavonol class of flavonoids. These flavonol compounds were identified as: quercetin-3, 7-diglucoside, quercetin-3-glucoside-7-galactoside, quercetin-3-sophoroside, quercetin-3-glucoside, quercetin-3-galactoside, isorhamnetin-3, 7-di-glucoside, isorhamnetin-3-glucoside, kaempferol-3, 7-diglucoside and kaempferol-3-glucoside. Halofito es una semilla oleaginosa codificada como SOS-7 (semilla oleaginosa Salicomia, séptimo a o de selección). Los tocoferoles del aceite de halofito SOS-7 fueron determinados directamente en el aceite usando cromatografía líquida de alta presión acoplada a detector fluorescente. Se encontró que el aceite contenía 710 ppm de tocoferoles totales. Los tocoferoles alfa, beta, gamma y delta, se encontraron a niveles de 38.2,1.0, 58.7 y 2.1%, respectivamente. Nueve glicósidos flavonoides fueron aislados e identificados de las semillas y se encontró que pertenecen a la clase flavonol dentro de los flavonoides. Estos flavonoles fueron identificados como: quercetina-3,7-diglucosido, quercetina-3-glucosido-7-galactosido, quercetina-3-soforosido, quercetina- 3-glucosido, quercetina-3-galactosido, isorannetina-3, 7-di-glucosido, isorannetina-3-glucosido, kampferol-3, 7-diglucosido y kampferol-3-glucosido.
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