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Hmida D.,University Paris - Sud | Hmida D.,Institute Preparatoire aux Etudes Scientifiques et Techniques IPEST | Hmida D.,Tunis el Manar University | Abderrabba M.,Institute Preparatoire aux Etudes Scientifiques et Techniques IPEST | And 3 more authors.
Journal of Chromatography B: Analytical Technologies in the Biomedical and Life Sciences | Year: 2015

Triacylglycerols (TAGs) are a large class of neutral lipids that naturally occur in both plant and animal oils and fats. Their analyses in Non-Aqueous Reversed Phase Liquid Chromatography (NARP) require a mixture of weak solvent (mostly acetonitrile) and strong solvent. In the present work, we have established eluotropic solvent strength scale of several binary mobile phases on C18 bonded silica at different temperatures (acetonitrile/methylene chloride, acetonitrile/acetone, acetonitrile/ethyl acetate, acetonitrile/propan-2-ol, and acetonitrile/butan-1-ol at 25°C, 43°C, 63°C and 85°C); it is based on the methylene selectivity and the use of homologous series. We show that this scale is well suited to the TAGs analysis. The analysis of nine seed oils (Aleurites fordii, Calophyllum inophyllum, Glycina max, Olea europea, Orbignya olifeira, Pinus koraiensis, Pistacia lentiscus, Punica granatum and Ribes nigrum) in iso-eluotropic conditions leads to propose unambiguously the couple MeCN/BuOH at 25°C as the best system to separate TAGs. The use of butanol, as strong solvent, provides very good TAGs congeners separations and avoids the use of chlorinated solvents which gave to this day the best separations. © 2015 Elsevier B.V.


PubMed | Tunis el Manar University, University Paris - Sud and Institute Preparatoire aux Etudes Scientifiques et Techniques IPEST
Type: | Journal: Journal of chromatography. B, Analytical technologies in the biomedical and life sciences | Year: 2015

Triacylglycerols (TAGs) are a large class of neutral lipids that naturally occur in both plant and animal oils and fats. Their analyses in Non-Aqueous Reversed Phase Liquid Chromatography (NARP) require a mixture of weak solvent (mostly acetonitrile) and strong solvent. In the present work, we have established eluotropic solvent strength scale of several binary mobile phases on C18 bonded silica at different temperatures (acetonitrile/methylene chloride, acetonitrile/acetone, acetonitrile/ethyl acetate, acetonitrile/propan-2-ol, and acetonitrile/butan-1-ol at 25C, 43C, 63C and 85C); it is based on the methylene selectivity and the use of homologous series. We show that this scale is well suited to the TAGs analysis. The analysis of nine seed oils (Aleurites fordii, Calophyllum inophyllum, Glycina max, Olea europea, Orbignya olifeira, Pinus koraiensis, Pistacia lentiscus, Punica granatum and Ribes nigrum) in iso-eluotropic conditions leads to propose unambiguously the couple MeCN/BuOH at 25C as the best system to separate TAGs. The use of butanol, as strong solvent, provides very good TAGs congeners separations and avoids the use of chlorinated solvents which gave to this day the best separations.


Lakhdar Z.B.,University of Tunis | Lahmar S.,Institute Preparatoire Aux Etudes Scientifiques et Techniques IPEST | Lakshminarayanan V.,University of Waterloo
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2014

Optics is an enabling science that has far ranging importance in many diverse fields. However, many students do not find it to be of great interest. A solution to this problem is to train teachers in active learning methodologies so that the subject matter can be presented to generate student interest. We describe a workshop to present an example of an active learning process in Optics developed for training of teachers in developing countries (a UNESCO project) and will focus on 2 two different activities: 1. Interference & diffraction is considered by students as being very hard to understand and is taught in most developing countries as purely theoretical with almost no experiments. Simple experiments to enhance the conceptual understanding of these wave phenomena will be presented and 2. Image formation by the eye. Here we will discuss myopia, hyperopia and astigmatism as well as accommodation. In this module we will discuss image. The objective of the workshop will be to provide an experience of the use of the active learning method in optics including the use of experiments, mind's on & hands-on exercises, group & class discussions. © 2014 SPIE, OSA, IEEE, ICO.


Juan C.,University of Valencia | Oueslati S.,Institute Preparatoire aux Etudes Scientifiques et Techniques IPEST | Manes J.,University of Valencia
Food Additives and Contaminants - Part A Chemistry, Analysis, Control, Exposure and Risk Assessment | Year: 2016

ABSTRACT: Alternariol (AOH), alternariol methyl ether (AME) and tentoxin (TEN) are Alternaria mycotoxins produced by the most common post-harvest pathogens of fruits. The production of these metabolites depends on several environmental factors, mainly temperature, water activity, pH and the technological treatments that have been applied to the product. In this study, the occurrence of AOH, AME and TEN was evaluated in strawberries samples stored at different temperatures ranges (at 22 ± 2 or 6 ± 2°C) and different periods (up to 1 month) simulating the current practice of consumer’s storage conditions. Sample extraction was performed using a liquid–liquid extraction method prior to LC-MS/MS analysis. AOH was the most prevalent mycotoxins with a 42% at strawberries stored at (22 ± 2)°C and 37% stored at (6 ± 2)°C. The highest AOH levels were found in samples conserved at (22 ± 2)°C ranging between 26 and 752 ng g–1. AME levels ranged between 11 and 137 ng g– 1, which were found mainly in stored samples at (6 ± 2)°C for more than 28 days. None sample presented levels of TEN in either of the studied conditions. © 2016 Informa UK Limited, trading as Taylor & Francis Group.


PubMed | University of Valencia and Institute Preparatoire aux Etudes Scientifiques et Techniques IPEST
Type: Journal Article | Journal: Food additives & contaminants. Part A, Chemistry, analysis, control, exposure & risk assessment | Year: 2016

Alternariol (AOH), alternariol methyl ether (AME) and tentoxin (TEN) are Alternaria mycotoxins produced by the most common post-harvest pathogens of fruits. The production of these metabolites depends on several environmental factors, mainly temperature, water activity, pH and the technological treatments that have been applied to the product. In this study, the occurrence of AOH, AME and TEN was evaluated in strawberries samples stored at different temperatures ranges (at 222 or 62C) and different periods (up to 1 month) simulating the current practice of consumers storage conditions. Sample extraction was performed using a liquid-liquid extraction method prior to LC-MS/MS analysis. AOH was the most prevalent mycotoxins with a 42% at strawberries stored at (222)C and 37% stored at (62)C. The highest AOH levels were found in samples conserved at (222)C ranging between 26 and 752 ngg(-1). AME levels ranged between 11 and 137 ngg(-)(1), which were found mainly in stored samples at (62)C for more than 28 days. None sample presented levels of TEN in either of the studied conditions.


Halary J.L.,CNRS Laboratory for Soft Matter & Chemistry | Jarray J.,Institute Preparatoire Aux Etudes Scientifiques et Techniques IPEST | Fatnassi M.,Institute Preparatoire Aux Etudes Scientifiques et Techniques IPEST | Ben Cheikh Larbi F.,Institute Preparatoire Aux Etudes Scientifiques et Techniques IPEST
Journal of Engineering Materials and Technology, Transactions of the ASME | Year: 2012

After extensive studies starting in the 1970s in relation to miscibility and piezoelectric properties, the blends of poly(vinylidene fluoride) (PVDF) and poly(methyl methacrylate) (PMMA) have been revisited with the aim of assessing their mechanical behavior. Depending on the amount of PVDF, either amorphous or semicrystalline blends are produced. Typically, the blends remain amorphous when their PVDF content does not exceed 40 wt. . Blend composition influence on the values of the glass transition temperature, T g, and on its mechanical expression, T α, is extensively discussed. Then, emphasis is put on the stress-strain behavior in tension and compression over the low deformation range covering the elastic, anelastic, and viscoplastic response. The reported data depend, as expected, on temperature and strain rate and also, markedly, on blend composition and degree of crystallinity. Molecular arguments, based on the contribution of the glass transition motions are proposed to account for the observed behavior. Thanks to the understanding of phenomena at the molecular level, accurate models can be selected in the view of mechanical modeling. © 2012 American Society of Mechanical Engineers.

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