742 research outputs found

    Assessment of Heavy Metal Contamination in Soils and Vegetables in Cameron Highlands Vegetable Farms

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    Vegetable cultivation is the most important agricultural activity in Cameron Highlands; about 64% of the population are involved in vegetable cultivation, with a total area of 2 599 hectares. Due to the extensive land levelling and construction of terraces, the vegetables are essentially grown on the subsoil. The subsoil are mainly sandy clay or clay, with large amounts of organic matter being added usually in the form of chicken manure. In a study of assessment of heavy metals in soils and vegetables of Cameron Highlands, Peninsular Malaysia, 200 soil and 40 vegetable samples from various locations were analyzed for cation exchange capacity (CEC), texture, cadmium (Cd), copper (Cu), nickel (Ni), lead (Pb), chromium (Cr) and zinc (Zn), organic carbon COe), pH and available phosphorus (P). The results showed that there was no relationship between total Cd, Cr, Cu, Ni, Pb and Zn concentrations in the soils and in the vegetables. Correlation studies of soil fertility parameters and total heavy metal concentration showed positive correlation between total P and Pb (r =0.492*) and Ni (r = 0.514*). This is indicative of addition of these metals as impurities in organic and inorganic fertilizers Organic Cd showed a positive correlation (r = 0.538*) with soil carbon (OC), while Pb showed a negative correlation (r = - 0.507*). This is indicative of addition of Cd as impurities in organic manures. Copper was positively correlated with clay content (r = 0.678**), while Pb (r = - 0.484*) and Ni (r = -0.554*) were negatively correlated with AI. Pb was negatively correlated with CEC (r = -0.502*). Anova analysis of total Zn, Cd, Cu, Cr, Ni and Pb with soil depth showed a very strong positive relationship. The concentration of Zn, Cd, Cr and Cu are high only in the topsoil (0-20 em), but the concentration of these elements remain the same in the depths of 20-40 em and 40-60 em. This is indicative of the contamination from agriculture activities. The difference in heavy metals from the cultivated soils and the control (primary forest) provides further evidence of the contamination by agriculture activities. The concentrations of heavy metal in Cameron Highlands soils from different vegetable farms were studied. Brinchang and Tanah Rata vegetable farms had very high concentration of Zn (219.80 mglkg); in Brinchang it is above the background values (Dutch Standard Guidelines). Also Brinchang and Tanah Rata farms had very high concentration of eu (61.80 and 71.20 mglkg, respectively), which is above the background level. Cd tends to be high in all Cameron Highlands farm soils

    Design of supramolecular nanomaterials : from molecular recognition to hierarchical self-assembly

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    In the present thesis, are reported new strategies for the design of nanostructures to partly address environmental issues. The work carried out has been divided into three parts: the design of cyclodextrin (CD)-based polymeric materials, the molecular engineering of a pyrene derivative for the formation of self-assembled nanostructures and the design of smart nanocarriers. Considerable efforts have been devoted to the design of molecular receptors capable of specific recognition of a wide variety of targets ranging from small inorganic ions to large biomolecules. These molecular receptors have been widely used to produce (nano)materials with superior molecular recognition properties. While these materials have been extensively studied for biomedical applications, their use in environmental sciences or biotechnology has been, to some extent, neglected. Supramolecular materials, because of their superior molecular recognition properties may find a wealth of new applications for the selective removal of harmful or valuable targets from industrial waste streams. While the specific recovery of valuable chemicals from waste streams represents an environmentally-friendly and potentially economically-relevant alternative to synthetic chemical productions, it remains a largely unmet challenge. This is partially explained by the complexity of designing sorption materials able to target one specific compound and able to function in complex matrices. In this manuscript, is reported the synthesis of a series of CD-based polymers (CDPs) designed to selectively extract phenolic compounds from a complex organic matrix that is OMW. In order to endow these polymers with selective adsorption properties, several monomers and cross-linkers were screened and selected. The adsorption properties of the CDPs produced were first tested with selected phenolic compounds commonly found in OMW, namely syringic acid, p-coumaric acid, tyrosol (TY) and caffeic acid. The selected CDPs were subsequently tested for their ability to adsorb phenolic compounds directly from OMW, which is known to possess a high and complex organic content. Adsorption models and adsorption kinetics were studied and allowed to set a new method on a pilot plant. It was demonstrated through liquid chromatography-mass spectroscopy (LC-MS) analyses that efficient removal of phenolic compounds from OMW could be achieved but also that two compounds, namely TY and hydroxytyrosol (HT), could be selectively extracted from OMW. The chemical oxygen demand (COD) level which is correlated to the amount of organic compounds was also reduced in the recovered fractions after extraction of the phenolic compounds, which makes the recovered waters relevant for irrigation purposes. The use of CD-based polymeric materials for the removal of valued added molecules could represent a new approach that will benefit from the ease of production of CDP and cost. Nature represents an inexhaustible source of inspiration for elegant hierarchically assembled structures and biology is replete with numerous examples of highly complex self-assembled structures. From cell membranes to proteins and viruses, the precise internal organisation of these biological structures is based on non-covalent interactions of subunits. Self-assembly strategies have been extensively exploited for the creation of supramolecular entities due to the complex synthesis of large structures through covalent synthetic strategies. Bottom-up approaches permit to build large and complex supramolecular assemblies through the interactions of building blocks. The accurate molecular design of organic building blocks is of great importance for the creation of large supramolecular entities with precise dimensional organisation. In this PhD thesis, we report the synthesis and template-free hierarchical self-assembly of a novel pyrene derivative into well-defined nanorods. The formation and the three dimensional packing of this pyrene derivative into nanorods were studied by means of fluorescence and UV-Vis spectroscopy, scanning electron microscopy, single crystal and powder X-ray diffraction studies. Nowadays oil and hydrocarbons cover most of our energy needs. In 2008, the world demand reached 85.62 million barrels/day.[1] Consequently spill accidents cause also considerable damages and water contamination by oil spills represents a major global problem. Several approaches for the degradation of oil spills are available including mechanical removal, wiping with absorbent materials or booming and skimming, but these techniques stay fairly limited in efficiency. Besides these methods, bioremediation has emerged as one of the most promising treatment for oil spill. Bioremediation is divided into two branches, biostimulation and bioaugmentation. We propose in this thesis an alternative way to overcome dilution related issues in biostimulation to degrade hydrocarbons through the stimulation of the microbial growth to increase the rate and efficiency of hydrocarbons degradation. The system would be able then to target specifically the oil phase and avoid any dilution of the needed nutrients into the sea, which should lead to a higher performance of the bacteria. We reported in this manuscript the synthetic strategy to produce what we named "Smart Gates Particles" (SGPs) that can act as nanocarriers and deliver specifically the nutrients to bacteria. The loading and kinetic releases of the nutrients contained in the SGPs have been studied in different environments, water and mixture oil/water. The design of such particles represents an alternative and ecological way to overcome the dilution or the non-targeted release of nutrients for oil-degrading bacteria

    La négation en rifain (parler de Ait Qamra)

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    International audienceEn rifain, il existe diffĂ©rents morphĂšmes qui servent Ă  obtenir des Ă©noncĂ©s nĂ©gatifs, ainsi ce travail sepropose de dresser un tableau de leurs diffĂ©rents emplois et d’en faire une analyse morphosyntaxiqueet sĂ©mantique. Cette Ă©tude sera basĂ©e sur le parler de la commune de Ait Qamra qui se situe Ă  unevingtaine de kilomĂštres au sud-ouest de la ville de Al Hoceima dans le canton de Ait Waryaghel(Maroc).Avant de rentrer dans le dĂ©tail de nos recherches, il convient de donner une dĂ©finition de ce qu’est lanĂ©gation. Je reprends Ă  mon compte la dĂ©finition que donne Robert Forest Ă  ce sujet et qui me sembleĂȘtre trĂšs complĂšte : La nĂ©gation est un « ensemble de procĂ©dures morphosyntaxiques de marquage,ayant pour fonctions principales de faire en sorte que les Ă©noncĂ©s qu’elles contribuent Ă  formerexhibent avec d’autres Ă©noncĂ©s un rapport systĂ©matique d’opposition sĂ©mantique, et d’introduire dansla situation de l’énonciation la communication du rejet par l’énonceur d’un contenu propositionnel (ouĂ©ventuellement situationnel non verbal) Ă  l’expression duquel le marquage nĂ©gatif se trouveformellement liĂ© » (Forest 1993).En fonction de ce qu’il vient d’ĂȘtre dit prĂ©cĂ©demment ce type d’énoncĂ© nĂ©gatif en berbĂšre secaractĂ©rise par la combinaison d’un ou plusieurs morphĂšmes nĂ©gatifs Ă  un prĂ©dicat verbal ou nonverbal(Ă©noncĂ© minimal), c’est ce que nous allons rendre compte prĂ©cisĂ©ment en les passanten revue le plus exhaustivement possible et en articulant notre Ă©tude autour de ces marqueurs denĂ©gations

    HOPX Crossover Operator for the Fixed Charge Logistic Model with Priority Based Encoding

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    In this paper, we are interested to an important Logistic problem modelised us optimization problem. It is the fixed charge transportation problem (FCTP) where the aim is to find the optimal solution which minimizes the objective function containig two costs, variable costs proportional to the amount shipped and fixed cost regardless of the quantity transported. To solve this kind of problem, metaheuristics and evolutionary methods should be applied. Genetic algorithms (GAs) seem to be one of such hopeful approaches which is based both on probability operators (Crossover and mutation) responsible for widen the solution space. The different characteristics of those operators influence on the performance and the quality of the genetic algorithm. In order to improve the performance of the GA to solve the FCTP, we propose a new adapted crossover operator called HOPX with the priority-based encoding by hybridizing the characteristics of the two most performent operators, the Order Crossover (OX) and Position-based crossover (PX). Numerical results are presented and discussed for several instances showing the performance of the developed approach to obtain optimal solution in reduced time in comparison to GAs with other crossover operators

    Rupture sous-cutanée traumatique du ligament quadricipital chez un sujet jeune

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    La rupture sous-cutanée traumatique du tendon quadricipital est exceptionnelle. Nous présentons un patient de 19 ans victime d'un accident de sport occasionnant cette blessure. La réparation chirurgicale puis la rééducation fonctionnelle ont permis une récupération complÚte des fonctions du genou et de la marche.Keywords: Rupture spontanée, tendon quadricipital, traumatisme, geno

    Prospects of implementing xAPI as a solution for progress tracking in a Blended Learning environment

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    Learning and development is an exciting world of never ending change, challenges, and trends. Businesses are currently attempting to adapt to the rapid digitization of workplaces. Therefore, L&D (Learning and Development) professionals are making learning material available to learners when and where they need it. According to two of “The State of Learning and Development” reports, published by “InSync Training” in 2016 and 2017 [1,2], the L&D industry is experiencing a shift from traditional approaches (e.g. classrooms, multi-day workshops
), to more modern learner-centered approaches (e.g. blended learning, mobile learning
). The aforementioned reports emphasize on the importance of implementing blended learning. It’ a learner-centered approach that matches different parts of the educational content to their most appropriate delivery methods (e.g. classroom interaction, article, video, audio, video game
) and sequences the resulting learning activities into a complete program of instruction. Although it’s currently a very popular trend given its benefits, there are multiple challenges it’s facing. In this article, we’ll explain the different benefits and challenges of blended learning. After that we’ll explore the prospects of implementing the Experience API (xAPI in short), a new open source specification for learning technology published by ADL (Advanced Distributed Learning) in 2013 [3], as a solution to improve the effectiveness and efficiency of blended learning

    Modelisation of the maintenanceproduction

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