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Molecular dynamics simulation of a polysorbate 80 micelle in waterYork, Peter, Anwar, Jamshed, Amani, A., de Waard, H. January 2011 (has links)
Yes / The structure and dynamics of a single molecule of the nonionic surfactant polysorbate 80 (POE (20)
sorbitan monooleate; Tween 80 ) as well as a micelle of polysorbate 80 in water have been investigated
by molecular dynamics simulation. In its free state in water the polysorbate 80 molecule samples almost
its entire conformational space. The micelle structure is compact and exhibits a prolate ellipsoid shape,
with the surface being dominated by the polar terminal groups of the POE chains. The radius of
gyration of the micelle was 26.2 A. The physical radius, determined from both the radius of gyration
and atomic density, was about 35 A. The estimated diffusion constants for the free molecule (1.8 10 6
cm2 s 1) and the micelle (1.8 10 7 cm2 s 1) were found to be remarkably close to the respective
experimental values. The lateral diffusion of the molecules on the micelle surface was estimated to be
1.7 10 7 cm2 s 1, which confirms the highly dynamic nature of the micelle structure. / Tehran University of Medical Sciences & Health Services
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Estudo da efic?cia do tensoativo sorbitano tween 80 veiculado em nanoemuls?o contendo ?leo de soja, como inibidor de corros?oRodrigues, Ciro Jos? Ferreira 30 August 2012 (has links)
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Previous issue date: 2012-08-30 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / Nowadays, the use of chemicals that satisfactorily meet the needs of
different sectors of the chemical industry is linked to the consumption of
biodegradable materials. In this context, this work contemplated
biotechnological aspects with the objective of developing a more
environmentally-friendly corrosion inhibitor. In order to achieve this goal,
nanoemulsion-type systems (NE) were obtained by varying the amount of
Tween 80 (9 to 85 ppm) a sortitan surfactant named polyoxyethylene (20)
monooleate. This NE-system was analyzed using phase diagrams in which the
percentage of the oil phase (commercial soybean oil, codenamed as OS) was
kept constant. By changing the amount of Tween 80, several polar NE-OS
derived systems (O/W-type nanoemulsion) were obtained and characterized
through light scattering, conductivity and pH, and further subjected to
electrochemical studies. The interfacial behavior of these NE-OS derived
systems (codenamed NE-OS1, S2, S3, S4 and S5) as corrosion inhibitors on
carbon steel AISI 1020 in saline media (NaCl 3.5%) were evaluated by
measurement of Open Circuit Potential (OCP), Polarization Curves (Tafel
extrapolation method) and Electrochemical Impedance Spectroscopy (EIS). The
analyzed NE-OS1 and NE-OS2 systems were found to be mixed inhibitors with
quantitative efficacy (98.6% - 99.7%) for concentrations of Tween 80 ranging
between 9 and 85 ppm. According to the EIS technique, maximum corrosion
efficiency was observed for some tested NE-OS samples. Additionaly to the
electrochemical studies, Analysis of Variance (ANOVA) and Principal
Component Analysis (PCA) were used, characterization of the nanoemulsion
tested systems and adsorption studies, respectively, which confirmed the
results observed in the experimental analyses using diluted NE-OS samples in
lower concentrations of Tween 80 (0.5 1.75 ppm) / Atualmente, a utiliza??o de produtos qu?micos que atendam satisfatoriamente
as necessidades de diferentes setores da ind?stria qu?mica encontra-se
vinculada ao consumo de materiais biodegrad?veis. Neste contexto, o presente
trabalho foi desenvolvido contemplando aspectos biotecnol?gicos com o
objetivo de se desenvolver um inibidor de corros?o menos agressivo ao meio
ambiente. Para tanto, uma nanoemuls?o (denominada de NE-OS) foi obtida
com Tween 80 (polioxietileno (20) monooleato), ?leo de soja (OS) e ?gua
bidestilada. A modifica??o dos percentuais deste tensoativo sorbitano (entre 9
e 85 ppm) foi avaliada em diagramas de fases em que se manteve constante o
percentual da fase ?leo, possibilitando a forma??o do sistema NE-OS em
diferentes concentra??es. Desta forma, nanoemuls?es (NE-OS1, S2, S3, S4 e
S5) polares (do tipo O/A) foram caracterizadas (an?lise de dispers?o de luz,
condutividade e pH) e submetidas a estudos eletroqu?micos. O comportamento
interfacial destes sistemas nanoemulsionados como inibidores de corros?o na
presen?a de a?o-carbono AISI 1020, em meio salino (NaCl 3,5%) foi avaliado
pela determina??o do Potencial de Circuito Aberto (OCP), Curvas de
Polariza??o (obtidas pela extrapola??o das curvas de Tafel) e Espectroscopia
de Imped?ncia Eletroqu?mica (EIE). De acordo com os resultados obtidos pelas
an?lises das Curvas de Polariza??o, foi poss?vel caracterizar o sistema NE-OS
(e suas varia??es) como inibidores mistos com efici?ncias m?ximas de
inibi??es quantitativas (98,6% - 99,7%) para NE-OS1 e NE-OS2 (9 - 85 ppm do
tensoativo). No entanto, de acordo com a t?cnica EIE, as efici?ncias m?ximas
de inibi??es quantitativas foram observadas para v?rias amostras deste
sistema NE-OS. Como ferramentas adicionais aos estudos eletroqu?micos
foram realizados quimiom?tricos de An?lise de Vari?ncia (ANOVA) e An?lise de
Componentes Principais (PCA), utilizadas, respectivamente, para
caracteriza??o das nanoemuls?es e estudo de isotermas de adsor??o, que
confirmaram os resultados observados nas investiga??es experimentais em
que se utilizaram as nanoemuls?es dilu?das com o tensoativo em
concentra??es reduzidas (0,5 1,75 ppm)
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Extraction, concentration and detection of metallic pollutants in environmental samples: (1) silver nanoparticles; (2) mercury ionWu, Zong-Han 09 July 2011 (has links)
I. Combined cloud point extraction and Tween 20-stabilized gold
nanoparticles for colorimetric assay of silver nanoparticles in
environmental water
This study investigated a simple, sensitive and selective method for the colorimetric
assay of silver nanoparticles (AgNPs) using Triton X-114-based cloud point extraction
(CPE) as a preconcentration step and Tween 20-stabilized gold nanoparticles
(Tween-AuNPs) as a colorimetric probe. After heating beyond the cloud point
temperature of Triton X-114, a solution containing Triton X-114 micelles and AgNPs
separated into a surfactant-rich phase (small volume) and a dilute aqueous phase.
AgNPs partitioned into a Triton X-114-rich phase through a hydrophobic interaction
between Triton X-114 micelles and AgNPs. After phase separation, the concentrated
AgNPs oxidized to form Ag+ upon adding H2O2. The generated Ag+ triggered the
aggregation of Tween 20-AuNPs in a high-ionic-strength solution because the reduction
of Ag+ on the AuNP surface enabled Tween 20 (stabilizer) to be removed from the NP
surface. The efficiency of Triton X-114-based CPE of the AgNPs was found to be
iv
insensitive to their size and coating type. Under optimal extraction and detection
conditions, the selectivity of this method for AgNPs was considerably higher than for
other nanomaterials. The minimum detectable concentrations for 7, 22, and 54 nm
AgNPs were measured to be 0.1, 420, and 600 ng/mL, respectively. This method was
successfully applied to the analysis of 7 nm AgNPs in drinking water, tap water and
seawater.
Keyword: silver nanoparticles, gold nanoparticles, cloud point extraction, Tween-20,
colorimetric assay
II. Functionalized silver nanoparticles as an extracting and preconcentrating
agent for detection of mercury ions
In this research we provided highly sensitive and selective for fluorescence assay of
combined polythymine oligonucleotide (PolyT) with silver nanoparticles (AgNPs) as an
extracting agent to detect mercury ion in environmental water. According to previous
researches, PolyT will form a hairpin structure in the presence of Hg2+, this structure
provide several 3-D grooves that the fluorescent dye can inlay with it. SYBR Green I
(SG) is a staining dye for DNA, when binding with single strand DNA, it shows low
fluorescence. On the contrast, SG inlay with grooves of hairpin structure, it shows
v
11-fold of fluorescence signal. Hence, we used SG as a fluorescence probe for Hg2+. We
modified thiol group at the 5¡¦ of PolyT DNA, because of forming silver sulfur bond,
PolyT will able to modified on the surface of AgNPs. PolyT33SH-AgNPs are the
extracting and concentrating agent in Hg2+ solution, by the centrifugation, we collected
the PolyT33SH-AgNPs. For the purpose of releasing PolyT from AgNPs¡¦ surface, we
adding H2O2 to oxidize the AgNPs into Ag+. By mixing buffer and SG into previous
solution, mercury ion could be detected. In this study, we successfully detecting Hg2+
in the aqueous solution contained drinking water and tap water. The detection limit in
drinking water is 20 pM, which is below Environmental Protection Agency limit for
Hg2+ in drinkable water (10 nM), the linear range is from 50-600 pM. On the other hand,
the detection limit in tap water is 50 pM, linear range is from 100-700 pM.
Keyword: silver nanoparticles, mercury ion, PolyT, SYBR Green I, thymine
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Optimization of the enzymatic conversion of maize stover to bioethanol / by Nombongo MabentselaMabentsela, Nombongo January 2010 (has links)
The severe effects associated with global warming and the rapid increase in oil prices are the
driving forces behind the demand for clean carbon–neutral and biofuels such as bioethanol.
Research studies are now focusing on using lignocellulosic biomass for bioethanol production due
to concerns about food security and inflation. The chosen feedstock for this study was maize stover,
given that it is the most abundant agricultural residue in South Africa. Maize stover consists of
structural carbohydrates that can be enzymatically converted into fermentable sugars. The major
drawback in the production of bioethanol from lignocellulosic biomass has been its high equipment
and operational costs due to the use of acids and high enzyme loadings. The aim of this study was
to investigate the possibility of optimizing the enzyme hydrolysis of pre–treated maize stover
without further increasing the amount of enzymes. The maximum glucose yield attained was
690 ± 35 mg of glucose per gram of substrate which is equivalent to a conversion efficiency of
119%. The preferred pre–treatment method used was 3% sulphuric acid for 60 minutes at 121oC and
the enzymatic hydrolysis process was performed at a 5% substrate loading, 50oC and pH 5.0 using
30 FPU per gram of cellulose in the presence of 1.25 g.L–1 of Tween 80 for 48 hours. The addition
of Tween 80 increased the glucose yields by 23 % and thus, it has the potential of lowering the
overall process costs by increasing the glucose yield without further addition of enzymes.
Keywords: Bioethanol, maize stover, lignocellulosic biomass, pre–treatment, enzymatic hydrolysis / Thesis (M.Sc. Engineering Sciences (Chemical Engineering))--North-West University, Potchefstroom Campus, 2011.
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Optimization of the enzymatic conversion of maize stover to bioethanol / by Nombongo MabentselaMabentsela, Nombongo January 2010 (has links)
The severe effects associated with global warming and the rapid increase in oil prices are the
driving forces behind the demand for clean carbon–neutral and biofuels such as bioethanol.
Research studies are now focusing on using lignocellulosic biomass for bioethanol production due
to concerns about food security and inflation. The chosen feedstock for this study was maize stover,
given that it is the most abundant agricultural residue in South Africa. Maize stover consists of
structural carbohydrates that can be enzymatically converted into fermentable sugars. The major
drawback in the production of bioethanol from lignocellulosic biomass has been its high equipment
and operational costs due to the use of acids and high enzyme loadings. The aim of this study was
to investigate the possibility of optimizing the enzyme hydrolysis of pre–treated maize stover
without further increasing the amount of enzymes. The maximum glucose yield attained was
690 ± 35 mg of glucose per gram of substrate which is equivalent to a conversion efficiency of
119%. The preferred pre–treatment method used was 3% sulphuric acid for 60 minutes at 121oC and
the enzymatic hydrolysis process was performed at a 5% substrate loading, 50oC and pH 5.0 using
30 FPU per gram of cellulose in the presence of 1.25 g.L–1 of Tween 80 for 48 hours. The addition
of Tween 80 increased the glucose yields by 23 % and thus, it has the potential of lowering the
overall process costs by increasing the glucose yield without further addition of enzymes.
Keywords: Bioethanol, maize stover, lignocellulosic biomass, pre–treatment, enzymatic hydrolysis / Thesis (M.Sc. Engineering Sciences (Chemical Engineering))--North-West University, Potchefstroom Campus, 2011.
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Heavy metal removal from bilge water by electrocoagulation treatmentAndrade, Milton 20 December 2009 (has links)
The purpose of this research was to observe the removal efficiency for copper (Cu), nickel (Ni), and zinc (Zn) using Electrocoagulation (EC) technique in a continuous flow reactor with a synthetic bilge water emulsion; and additionally, to discuss the operation cost of the treatment. The optimal configuration for EC treatment used combined electrodes, aluminum and carbon steel; flow rate of 1 L/min; effluent recycling and 7.5 amps; this optimal configuration achieved 99% of zinc removal efficiency, 70% of both, copper and nickel removal efficiency, and low operation costs. The current intensity did not have significance incidence on the removal efficiency. The analysis of cost per gram of removed contaminant indicated that nickel had an average cost of $1.95 per gram removed, zinc and copper had $0.60 and $0.88 per gram removed, respectively. To develop additional experiments with the EC reactor are required in order to optimize metal removal efficiency.
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Marketing health issues to tweens : recommendations for reaching this demographic more effectivelyKelly, Erin Joy 20 February 2012 (has links)
This paper explores public health campaigns as they relate to tweens and their use of technology. After considering how this demographic utilizes both traditional and new media, further examination was done on general health problems that affect this group. Three major health issues were then chosen for analysis. A relevant campaign for each issue was also evaluated, as were its overall marketing and communication efforts. The health problems and corresponding campaigns chosen include childhood obesity and the “Let’s Move” campaign, electronic aggression and the “Stop Bullying” campaign and youth suicide and the “WeCanHelpUs” campaign. From these analyses, recommendations for ways to improve each campaign were provided, as were general conclusions for reaching this demographic more efficiently and effectively. / text
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Desenvolvimento e caracterização de biofilmes a base de gelatina, triacetina, acido estearico ou acido caproico e surfactantes / Development and characterization of biofilms based on gelatin, triacetin, stearic or caproic acid and surfactantsDavanço, Taciana 23 February 2006 (has links)
Orientador: Carlos Raimundo Ferreira Grosso / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-05T16:31:42Z (GMT). No. of bitstreams: 1
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Previous issue date: 2006 / Resumo: Desenvolvimento de biofilmes tem crescido devido a possibilidade de substituição parcial de materiais plásticos não degradáveis. Proteínas e polissacarídeos têm sido utilizados para a produção de filmes com boas propriedades mecânicas. Porém filmes a partir desses materiais apresentam alta permeabilidade ao vapor de água. Uma alternativa usada para diminuir a permeabilidade ao vapor de água dos filmes é a incorporação de substancias hidrofóbicas na composição da solução filmogênica, porém a incorporação dessas substâncias na matriz filmogênica não ocorre de maneira homogênea. Com o objetivo de melhorar a incorporação das substâncias hidrofóbicas na matriz protéica do filme foram adicionados os surfactantes (SDS e Tween 80), que são compostos orgânicos constituídos por moléculas anfifílicas, contendo uma parte polar e outra apolar, com o intuito desta substância interagir na proteína e no ácido graxo, tornando a matriz filmogênica menos heterogênea. O efeito do pH também foi estudado, com a finalidade de observar se este exerce influência na homogeneidade da matriz filmogênica. Os ácidos graxos utilizados no trabalho foram o ácido capróico (6C), e o ácido esteárico (18C), com o objetivo de avaliar e comparar se o número de carbonos da cadeia do ácido graxo exerce influencia na incorporação da matriz protéica. Os filmes foram caracterizados quanto as propriedades de barreira ao vapor de água e propriedades mecânicas, solubilidade em água, opacidade, isotermas de sorção e calorimetria diferencial de varredura, podendo ser observado que a adição dos surfactantes melhorou a barreira ao vapor de água e diminuiu a resistência à tração dos filmes, não sendo observado diferenças na cor e opacidade dos filmes . Posteriormente foram analisadas as características morfológicas, através da microscopia ótica, microscopia eletrônica de varredura e microscopia confocal de varredura a laser, observando que o ajuste do pH e a adição do surfactante modificam a estrutura morfológica do filme / Abstract: Development of biofilms has grown considering the possibility of partial substitution of plastic materials not degradable. Proteins and polysaccharides have been used for the production of films with good mechanical properties. However films produced with these materials present high water vapor permeability to the water vapor. An used alternative to improve the water vapor barrier of the films is the incorporation of hydrophobic substances in the composition of the filmogenic solution, however the incorporation of these substances in the filmogenic matrix does not occur in homogeneous way. Thus with, the objective to improve the incorporation of hydrofhobic substances in the protein matrix of the film surfactants had been added (SDS and Tween 80). They are organic compounds constituted by anphiphilics molecules, incluing a polar part and other apolar, with the intention that is substances improve the interaction between the protein and the fats acids, producing a less heterogeneous filmogenic matrix. The effect of pH also was studied, with the purpose to observe if this produce influence in the homogeneity of the filmogenic matrix. The fats acids used in this work were the caproic acid (6C), and the stearic acid (18C), with the objective to evaluate and to compare if the carbon number of the fats acids exerts influences in the incorporation on the protein matrix. The films were characterized with respect to the properties of barrier to the water vapor, solubility in water, opacity, isotherms of sorption and thermal properties, being able to be observed that the addition of the surfactants improved the water vapor permeability and decreased the tensile strenght of the films, not being observed differences in the color and opacity of the films. Later the morphologic characteristics had been analyzed, through optics microscopy, scanning electron microscopy and confocal laser scanning microscopy, observing that the adjustment of pH and the addition of the surfactant modify the morphological structure of the films / Mestrado / Nutrição Experimental e Aplicada à Tecnologia de Alimentos / Mestre em Alimentos e Nutrição
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Estudo da formação de micelas e microemulsões contendo nifedipina : influência das fases na estrutura dos sistemasOliveira, Dayane Xavier de 03 February 2014 (has links)
Micelles (MIs) and microemulsions (MEs) are classified as stabilized systems by surfactants and are very similar with respect to their structure and physico-chemical properties. As for the applicability, they have been deployed by being able to carry drugs which have a limited systemic bioavailability by oral route. The formation of these systems is mainly dependent on the types of components used, making it important to study its influence on the structure. The goal of this study was to obtain and characterize micellar and microemulsion systems (containing essential oil of Citrus sinensis (L.) Osbeck as oil phase) stabilized by a nonionic surfactant (Tween 80) and short-chain cosurfactant (alcohol ethyl) which may be used as a delivery system for nifedipine (NFD a model drug) seeking to verify the influence of the phases and the interaction of the drug in the structure of these systems. Ternary and pseudoternary phase diagrams for MIs and MEs, respectively, and were obtained from the formation regions, formulations were selected for physico-chemical characterization and incorporation of NFD. The macro and microscopic aspects were evaluated using polarized light microscopy (MLP), measures pH, electrical conductivity and surface tension. The average droplet size was measured by dynamic light scattering (DLS) and small angle x-ray scattering (SAXS). The results demonstrated that such systems are stable, optically isotropic and transparent in the absence and presence of drug. The droplet size decreases with increasing amount of surfactant to MIs and the mixture surfactant/cosurfactant to the MEs. The influence of the cosurfactant in MIs was negligible. The increase of the amount of oily phase in MEs caused an increase in the droplet size. The presence of NFD no influence on the structure of MIs, but for the MEs increased droplet size, suggesting that the NFD is the internal phase of the MEs. The modeling by SAXS curves for MIs and MEs most diluted were made and showed the interaction between the NFD and systems, confirming the previous results. Studies by Fourier Transformed Infra Red (FTIR) confirmed the interaction between MIs and MEs with the stratum corneum (EC) , which allows the use of these systems as permeation enhancers of NFD. / As micelas (MIs) e as microemulsões (MEs) são classificadas como sistemas estabilizados por tensoativos e se assemelham bastante com relação a sua estrutura e propriedades físico-químicas. Quanto a sua aplicabilidade, elas têm sido destacadas por serem capazes de veicular fármacos que possuem uma biodisponibilidade sistêmica limitada por via oral. A formação destes sistemas é dependente principalmente dos tipos de componentes utilizados, tornando-se relevante o estudo da sua influência na estrutura. O objetivo do presente trabalho foi a obtenção e caracterização de sistemas micelares e microemulsionados (contendo óleo essencial de Citrus sinensis (L.) Osbeck como fase oleosa), estabilizados por um tensoativo não iônico (Tween 80) e um cotensoativo de cadeia curta (álcool etílico), que possam ser utilizados como sistema de liberação para a nifedipina (NFD, um fármaco modelo), buscando verificar a influência das fases e a interação do fármaco na estrutura desses sistemas. Diagramas de fase ternário e pseudoternário para MIs e MEs, respectivamente, foram obtidos e a partir das regiões de formação, formulações foram selecionadas para caracterização físico-química e incorporação da NFD. Os aspectos macro e microscópicos foram avaliados utilizando microscopia de luz polarizada (MLP), medidas de pH, condutividade elétrica e tensão superficial. O tamanho médio de gotículas foi avaliado por espalhamento dinâmico de luz (DLS) e espalhamento de raios-x a baixos ângulos (SAXS). Os resultados demonstraram que esses sistemas são estáveis, isotrópicos e opticamente transparentes na ausência e presença de fármaco. O tamanho das gotículas diminuiu com o aumento da quantidade de tensoativo para as MIs e de mistura de tensoativo/cotensoativo para as MEs. A influência do cotensoativo nas MIs foi praticamente desprezível. O aumento da quantidade de fase oleosa nas MEs ocasionou um aumento do tamanho das gotículas. A presença da NFD não exerceu influência na estrutura das MIs, entretanto para as MEs aumentou o tamanho de gotículas, sugerindo que a NFD se encontra na fase interna das MEs. Os modelamentos das curvas de SAXS para as MIs e MEs mais diluídas foram realizados e mostraram a interação existente entre a NFD e os sistemas, corroborando com os resultados anteriores. Estudos por espectrofotometria de absorção na região do infravermelho com transformada de Fourier (FTIR) comprovaram a interação das MIs e das MEs com o estrato córneo (EC), o que possibilita o uso destes sistemas como promotores de permeação da NFD.
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L’expérience de l’enseignement de la Shoah en France par des professeurs de collège et de lycée : un analyseur de l’expertise professionnelle face à une question socialement vive / The experience of teaching the Shoah in France by high school and secondary school teachers : an analyser of the professional expertise grappling with an acute societal point at issueDrahi, Patricia 30 June 2015 (has links)
Depuis le début des années 2000, l’enseignement de la Shoah est perçu en France comme une question socialement vive susceptible de déréguler les pratiques de classe. Cette thèse en sciences de l’éducation étudie l’expérience de l’enseignement de la Shoah des profes-seurs du secondaire en France. En s’appuyant sur 30 entretiens semi-directifs, la recherche montre, de l’intérieur, comment les professeurs interrogés perçoivent cet enseignement, ses difficultés et s’intéresse aux réponses déployées par les interrogés. Les résultats montrent les difficultés provenant du côté des élèves : saturation présumée, antisémitisme, concur-rence des mémoires, mais aussi concurrence entre les savoirs sociaux et le savoir scolaire. Du côté des enseignants, apparaît également la vivacité de la question, divisant davantage qu’elle ne fédère les membres de l’équipe éducative. De plus, l’impact émotionnel sur l’enseignant que la confrontation entre savoir scolaire et savoir social véhiculé par les élèves peut engendrer, accentue les difficultés rencontrées. Les professeurs qui montrent une assu-rance dans cet enseignement révèlent au travers des récits de vie de classe, qu’ils investis-sent pleinement le pôle didactique et le pôle pédagogique de la fonction de professeur. Aller à la rencontre de ce savoir social avec bienveillance et exigence, faire dire mais ne pas lais-ser dire amènent ces professeurs à répondre dans le cadre d’un savoir historique, précis et rigoureux qui refuse la dérive relativiste ou normative (Legardez, 2006). L’énoncé de repères éthiques et citoyens, une vigilance quant à la gestion de l’émotion dans la classe y compris de celle de l’enseignant, participent aussi au cadre construit par les professeurs. Ainsi ces derniers alternent entre le pôle didactique le pôle pédagogique, ce qui leur permet de rentrer dans « le fonctionnement improvisationnel de l’enseignant expert » (Tochon, 1993). L’enseignement de la Shoah dans certaines situations sensibles est assimilé à un combat. Une typologie inspirée des travaux de Jacques Pain (1992) sur la régulation de la violence délinquante par les arts martiaux émerge : combattant stratège, combattant intrépide, com-battant émotif, ou témoin distancié sont les différentes figures enseignantes qui se dégagent de cette recherche. / Since the beginning of the 2000’s, teaching Shoah has been perceived as a deep social is-sue in France which may well change the rules of classroom practices. This thesis studies the experience of teaching the Shoah from the point of view of secondary school teachers. Drawing from 30 semi-directive interviews, this research in education shows from the inside how the teachers questioned perceive this teaching and its difficulties. This thesis shows how teachers deal with this issue from an educational point of view and the answers they provide. The results underline difficulties stemming from “the pupils’ point of view”: presumed satura-tion, anti-Semitism, competition between memoirs, but also competition between social backgrounds and school knowledge. “From the teachers’ point of view” the intensity of the issue is also present, dividing more than federating the members of the educational team. Moreover, the emotional impact on the teacher concerning the confrontation between school knowledge and social background conveyed by pupils can create and increase the difficulties encountered. The teachers who show confidence in this teaching have disclosed through classroom stories that they fully invest the didactic pole and the educational pole of their po-sition. In doing so, they hail, welcome and accept the social background with the necessary benevolence and unstructured consciousness that this entails. Helping pupils express them-selves but not letting them talk without knowing helps the teacher answer questions in a precise and rigorous historical framework and is against relativistic or normative drifting as defined by Legardez (2006). The framework of ethical and citizen indicators as far as the management of emotions in the classroom is concerned (including the teacher's emotions) also part of the framework built by the teacher. Thus, these latter alternate between the di-dactic pole and educational pole and enable them to bring in and adopt the improvisational operation mode of the expert instructor as defined by Tochon (1993). In some sensitive situa-tions, the teaching of the Shoah is compared to a fight. A typology inspired by Jacques Pain's thoughts concerning the regulation of delinquent violence through martial arts has emerged: the strategist fighter, the dauntless fighter, the emotional fighter or the aloof witnesses are the various teaching figures that have emerged from this research.
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