Find this Pin and more on Eprepare. Organic Chemistry Tutor. Chemistry Help. Online Tutoring. Functional Group.

Author:Kigashura Zulkibei
Country:Republic of Macedonia
Language:English (Spanish)
Published (Last):4 July 2018
PDF File Size:4.77 Mb
ePub File Size:10.30 Mb
Price:Free* [*Free Regsitration Required]

Influence of natural organic matter on the speciation of radionuclides in a geochemistry context; Influence de la matiere organique naturelle sur la speciation des radionucleides en contexte geochimique. The principal aim of this work is the study of the influence of natural organic matter, in particularly humic substances HS , on the speciation of radionuclides RN.

It has been shown that mobility and bioavailability of a metal are related to its speciation. However the model has been calibrated with a limited number of experimental data for the RN. Indeed there is only a few speciation technique available for the study of the interactions RN-HS. Within the framework of this study, we have developed and optimised speciation technique Flux Donnan Membrane Technique and the use of an un-solubilized humic acid in order to acquire new experimental data, we have also studied the effect of the competition on RN speciation and finally we have tested the model capacity to predict the RN behavior in laboratory or in situ.

Bioavailability of Polycyclic Aromatic Hydrocarbons in aquatic ecosystems : influence of natural and anthropic organic matter; Biodisponibilite des hydrocarbures aromatiques polycycliques dans les ecosystemes aquatiques: influence de la matiere organique naturelle et anthropique.

Aquatic ecosystems receive micro-pollutants. They also contain organic matter OM of natural and anthropogenic origins. The contaminant bioavailability in aquatic media is determined by the interactions between contaminants and OM.

This work deals with the influence of organic matter from anthropogenic media on the bioavailability of hydrophobic organic pollutants. Polycyclic Aromatic Hydrocarbons PAHs have been used as model contaminants, since they are widely spread in urban media. In anthropogenic media, some OM may be bio-degraded.

Up to now, most researches focused on the interactions between contaminants and humic OM that are mostly non-degradable, using physico-chemical characterizations of OM. On the contrary, in this work, the biodegradability of OM was deliberately taken into account. Indeed, we assume that the contaminant affinity for OM evolves during OM biodegradation, so that pollutants may be released in a bio-available form and then may be bond again by biodegradation sub-products.

In laboratory evaluation, PAH bioavailability was assessed through the measurements of the bioaccumulation in Daphnia magna. The influence of organic matter on the bioavailability of PAHs and the evolution of this influence along OM bacterial mineralization were proved, as well as the strong binding efficiency of degradation by-products.

A model of observed phenomena was elaborated. These observations about urban and natural OM effect were compared to in situ PAH bioavailability measurements in the river Seine basin.

Intelligence Naturelle et Intelligence Artificielle. Tritium in plants; Le tritium dans la matiere organique des vegetaux. The presence of tritium in the environment stems from its natural production by cosmic rays, from the fallout of the nuclear weapon tests between and , and locally from nuclear industry activities.

A part of the tritiated water contained in the foliage of plants is turned into organically bound tritium OBT by photosynthesis. The tritium of OBT, that is not exchangeable and then piles up in the plant, can be used as a marker of the past.

It has been shown that the quantity of OBT contained in the age-rings of an oak that grew near the CEA center of Valduc was directly correlated with the tritium releases of the center.

Study of the behaviour of organic carbon in the soil, and carbon 14 study of podzols; Contribution a l'etude du comportement du carbone organique dans le sol et etude des podzols a l'aide du carbone Centre d' Etudes Nucleaires. Using the penetration into soil of carbon 14 of thermo-nuclear origin, the behaviour and renewal rate were studied on different organic fractions of the soil.

In addition the formation of podzol-type fossil soils in France was dated from the first millenary B. Par ailleurs, la formation en France des sols fossiles du type podzol a ete datee du premier millenaire avant J. Vers une narratologie naturelle de la musique. Directory of Open Access Journals Sweden. Protection des ions organiques contre les dommages induits a l'ADN par les electrons de basse energie.

Il a ete demontre que les electrons de basse energie EBE peuvent induire des cassures simple brin CSB a l'ADN, via la formation d'anions transitoires qui decroissent par attachement dissociatif, ou dans d'autres etats electroniques dissociatifs menant a la fragmentation. Afin d'effectuer une etude complete des effets des electrons de basse energie sur la matiere biologique, il est necessaire de comprendre leur mecanismes d'interaction non seulement avec l'ADN, mais avec les constituants de son environnement.

Les histones sont une composante importante de l'environnement moleculaire de l'ADN. Leur charge positive leur permet de s'associer aux groupements phosphate anionique de l'ADN. Le role principal de ces proteines basiques consiste a organiser l'ADN et l'empaqueter afin de former la chromatine. Les cations sont une autre composante importante de la cellule; ils jouent un role dans la stabilisation de la conformation B de l'ADN in vitro par leurs interactions avec les petits et grands sillons de l'ADN, ainsi qu'avec le groupement phosphate charge negativement.

Avec les histones, ils participent egalement a la compaction de l'ADN pour former la chromatine. Cette etude a pour but de comprendre comment la presence d'ions organiques sous forme de Tris et d'EDTA a proximite de l'ADN modifie le rendement de cassures simple brin induit par les electrons de basse energie.

De plus, la molecule Tris possede un groupement amine alors que l'EDTA possede 4 groupements carboxyliques. Ensembles, ils peuvent se comporter comme un modele simple pour les acides amines. Le ratio molaire de 10 :1 de Tris par rapport a l'EDTA a pour but d'imiter le comportement des histones qui sont riches en arginine et lysine, acides amines possedant un groupement amine charge positivement additionnel.

Des films d. Regeneration naturelle des especes ligneuses dans la foret de Ngotto. Republique Centrafricaine. Recuperation de la matiere organique biodegradable presente dans l'effluent d'un MBBR a forte charge. High-rate processes are receiving great interest due to their potential to favor the energy balance of water resource recovery facilities WRRFs either for their design or retrofit. Anaerobic digestion is a process that allows the valorization of organic biodegradable matter contained in sludge into biogas.

This process also produces a stabilized sludge named digestate or biosolids that can be reused for agriculture purposes. This project proposed a secondary treatment train composed of a high-rate moving bed biofilm reactor HR-MBBR to biotransform colloidal and soluble biodegradable organics into particulate matter followed by an enhanced and compact physico-chemical separation process to recover mainly particulate organics and a part of the colloidal matter.

A high-rate biological process operated at a low hydraulic retention time aimed at transforming colloidal and soluble fractions of organic matter into a particulate fraction for recovery by downstream separation process. The HR-MBBR effluent solids are known for their poor settleability, therefore requiring an efficient separation process downstream to ensure their recovery and to meet the effluent discharge regulations. The global objective of this project was to maximize the recovery of organic biodegradable matter for valorization into biogas by anaerobic digestion with an innovative treatment train combining an HR-MBBR and a separation process.

The specific objectives of this report were 1 to characterize the HR-MBBR effluent solids and 2 to determine the efficiency of several physico-chemical separation processes combined with unbiodegradable or natural based coagulants and polymers. Effluents of lab-scale HR-MBBR fed with a synthetic soluble or domestic wastewater influent and the effluent of a full-scale HR-MBBR were used to evaluate the efficiency of separation processes adapted at bench-scale in jar-tests experiments.

The processes studied were conventionnal settling, ballasted flocculation, dissolved air flotation and an innovative enhanced flotation process. Unlike conventional settling and dissolved air flotation, ballasted flocculation and enhanced flotation use a ballasted or flotation agent to accelerate the sludge settling or flotation rate.

The separation processes efficiencies were evaluated based on their TSS recoveries. Monitoring the chemical oxygen demand COD fractions allowed to better understand the underlying mechanisms of organic matter biotransformation and capture throughout the proposed treatment train.

Without the presence of particulate matter in the influent, the particulate matter in the MBBR effluent represented only the production of biomass detached by the shearing forces between the carriers.

The TSS concentration and the efficiency of colloidal and soluble matter biotransformation into particulate matter increased with the MBBR hydraulic retention time. Wide volumetric particle size distributions ranging from 5 to mum in the lab-scale MBBR effluent were observed with a higher proportion of particles larger than mum for a synthetic feed, and a higher proportion of small size particles of 30 mum for a domestic wastewater feed. The presence of lots of small size particles was attributed to unsettleable solids in the influent unchanged in the reactor.

Hence, coagulating agents were necessary to enhance the solids recovery. The enhanced flotation efficiency was reduced when using natural based chemicals, especially the natural based polymer which was not suited to treat waters with such high TSS concentrations. More experiments are needed to confirm the effect of these parameters on TSS recovery efficiency. Although natural based chemicals reduced the coagulation and flocculation efficiency, they allowed a decrease in sludge production, which can represent a significant cost benefit.

Natural based chemicals are recommended over unbiodegradable ones to promote the use of high biodegradability potential chemicals and to reduce the production of chemical sludge. However, to offset the increase of total COD, it may be required to add a treatment downstream to meet target secondary treatment COD concentration.

The efficiency reduction was attributed to non-optimized and unadapted flotation lab-scale setups to treat medium strength wastewater.

A similar innovative treatment train is currently being tested at pilot-scale in order to evaluate its carbon footprint and its potential to be eventually transposed to full-scale. Furthermore, the biodegradability and the biochemical methane production of the natural based chemicals are being determined.

This project allowed to determine the potential of the innovative enhanced flotation process to recover the HR-MBBR solids when combined with natural based chemicals which are currently not often used in wastewater treatment for resource recovery. Bapuji et al. Pop et. The nature of particulate organic matter settled on solid substrata.

Aucune difference n'a etc dccelee dans lacomposition de la matiere organique et dans les Numerical Study of natural convection in an inclined enclosure. Study of atmospheric tritium transfers in lettuce: kinetic study, equilibrium and organic incorporation during a continuous atmospheric exposure; Etude des transferts du tritium atmospherique chez la laitue: Etude cinetique, etat d'equilibre et integration du tritum sous forme organique lors d'une exposition atmospherique continue.

Dans le sol, le temps de mise a l'equilibre depasse generalement 24 heures; le rapport des concentrations a l'etat stationnaire est compris entre 0, 01 et 0, Cependant, l'incorporation de l'OBT depend fortement du stade de developpement du vegetal.

La periode de plus forte integration du tritium sous forme organique correspond a la phase de croissance exponentielle des vegetaux. Le depot et la diffusion du tritium dans le sol entrainent des activites significatives dans la fraction organique du sol.

Les resultats obtenus vont globalement dans le sens d'une mise a l'equilibre des concentrations du tritium dans le vegetal eau libre et tritium organique avec celles de l'environnement atmosphere, sol. Certaines experiences ont neanmoins revele des activites OBT anormalement elevees dans les laitues au regard des niveaux d'exposition et posent la question d'un possible phenomene d'accumulation locale du tritium dans la matiere organique pour des conditions particulieres d'exposition.

In these textbooks Gerhard presents a way to arrange organic compounds in series. The classification has improved. His idea is that all organic compounds are based on four main types i. Why did Gerhardt chose to develop his theories in a textbook and not in scientific papers? We can think of a few reasons: in a textbook he could articulate ideas and could give constitency to his theories. It is longer than a paper. Textbook authors are less rescricted.

The readers are students. The dating of the fourth volume of Guillaume-Antoine Olivier's "Entomologie, ou histoire naturelle des insectes". Despite the title page is dated , the fourth volume of Olivier's Entomologie, ou histoire naturelle des insectes was issued in two parts, one probably in and the second in All new taxa made available in this work have previously been dated in the literature.


ISBN 13: 9782100776719



Organic Chemistry Tutor






Related Articles