bluuebunny/crossref_metadata_2025 huggingface dataset:
L'apprentissage de l'itération dans deux environnements informatiques
Authors: Dagdilelis Vassilios , Balacheff Nicolas , Capponi Bernard
Published: June 2010

Cet article présente une étude comparée de l'apprentissage de l'itération dans deux environnements informatiques différents : Pascal et Multiplan. Cette étude a été réalisée avec des élèves de troisième (fin de la scolarité obligatoire) d'un collège français. Nous avons pu dégager des analogies importantes entre les deux environnements à propos de l'itération Mais l’hypothèse consistant à prévoir un transfert des connaissances d'un logiciel à l’autre ne s’est pas trouvée confirmée, ce qui confirme la complexité cognitive du concept d'itération, déjà mise en évidence dans d'autres recherches.
Associer raisonnablement informatique et didactique, par l'étude des automatismes
Authors: Toussaint Jacques
Published: June 2010

Informatique et enseignement sont deux termes que l'on cherche de plus en plus à associer. La didactique produit des outils pour analyser, comprendre et faciliter l'enseignement. L’association de l'informatique et de la didactique doit donc être réalisable. En choisissant d'aborder l'informatique par l'étude des automatismes, on répond au libellé de certains programmes, plus particulièrement des classes de flndEcole élémentaire, ainsique des Collèges, dans le cadre de la Technologie. Mais pour apprendre quoi et comment aux élèves ? C'est en regardant de près et en analysant les éléments du contrat que l’association entre informatique et didactique pourra être justifiée. Le domaine des automatismes s'avère privilégié pour une telle analyse, quitte à rendre nécessaire un changement de point de vue des champs disciplinaires classiques.
Analyse d'une image satellitaire
Authors: Cariou François , Le Gall Rudolf
Published: June 2010

Analysis of a satellite image.

As part of a pluridisciplinary study (associating physics, biology and geography) conducted on the Natural Reserve of Grand-Lieu, in Loire-Atlantique, pupils of 16-17 years'old worked on a digital image of Nantes'region taken by the satellite Spot on june the 26th, 1986. With computer help, they were able to treat the numerical data and to obtain a map of the vegetation in summer. This document was used to study the ecosystem of this area and its evolution.
Le concept de système immunitaire
Authors: Rumelhard Guy
Published: June 2010

En biologie fondamentale et médicale le terme de système, couramment employé a souvent un sens ambigu. De système anatomique il doit devenir système fonctionnel. Mais en immunologie l'ensemble des réactions n'a longtemps pas formé une fonction générale permanente de l'organisme. Il s'agissait plutôt d'une bizarrerie de la nature, une suite d'événements accidentels liés à l'histoire individuelle. Longtemps tourné uniquement vers le rejet, le système immunitaire présente désormais une deuxième face, celle de la facilitation. La perspective évolutive enfin complique encore le tableau. Pédagogiquement, pour lutter contre cette présentation de l'immunologie l'auteur propose de sélectionner des situations paradoxales jouant une fonction polémique.
Le concept de réseau idiotypique : une nouvelle façon de penser le système immunitaire
Authors: Dewaele Jacques
Published: June 2010

El concepto de red idiotipica : Una nueva manera de pensar el sistema inmunitario.

La inmunología enseñada actualmente es esencialmente pasteuriana. Su teoría explicativa,fechada en el año 1957, es la teoría de la selección clonal. Existe, sin embargo una teoría más reciente (1974), es la teoría de la red inmunitaría. Intentamos de mostrar, que esta teoría utiliza un concepto interdisciplinario, que es bien explicativa, tratando de cesar de ser un andamiaje conceptual reservado a los inmunologistas advertidos ; y en fin que entra en ruptura con un conocimiento anterior muy resistente que es la idea que nosotros nos hacemos del ser y del no ser. Esta ruptura sería la causa de las resistencias a su adopción en la enseñanza.
Les formulations successives du savoir : le concept de récepteur et le modèle clé-serrure
Authors: Perez Eric
Published: June 2010

Admettre la possibilité de formulations successives d'un même savoir ayant une valeur explicative réelle mais partielle n'est pas une banalité. Cette conception se heurte à celle qui identifie vérité et savoir le plus récent, autrement dit qui nie la dimension historique du travail des savants.

Pour le modèle analogique "clé-serrure" qui fournit une explication du fonctionnement des récepteurs biologiques il est possible de définir quatre formulations qui intègrent les concepts impliqués et les représentations auxquelles il faut renoncer.
Le récepteur en immunologie, polysémie-polyphonie historique
Authors: Moulin Anne-Marie
Published: June 2010

L'immunologie est particulièrement riche en expressions métaphoriques qui fournissent d'utiles indicateurs de ses péripéties historiques. L'univers sémantique de ces métaphores déborde les limites du langage scientifique et la polysémie de certains termes-clé scientifiques aide à comprendre leur impact sur l'imagination des chercheurs. Cet article retrace plus particulièrement l'histoire du terme récepteur, sans cesse réemployé depuis le début du XXème siècle et qui assure des fonctions épistémologiques multiples, parmi lesquelles la garantie de la continuité historique en immunologie et le renforcement de l'unité de la discipline.
Présentation du concept de climax aux visiteurs du Marais Vernier
Authors: Lemare Emmanuel
Published: June 2010

Presentación del concepto de "climax" a los visitantes del "Marais Vernier".

Este trabajo resulta de la observación de la evolución del "Marais Vernier" luego del abandono de las practicas agrícolas

de pastura y de siega llevadas a cabo por un equipo de biologos (CEDENA, Pare Natural Régional de Bretonne), T.Lecomte y C.Le Neveu. La degradación ecológica que siguió, conduzco la puesta a punto de la Reserva Natural de Mannevilles, de una gestión restauradora compatible con los apremios del medio, y a una reflexión teórica sobre el concepto de "climax". Contribuyendo a promover y a difundir ese modo de gestión, el autor ha intentado un primer análisis de las reacciones del público, de sus resistencias y sus adhesiones.
L'art comme jubilation critique
Authors: Caillet Elisabeth , Ba Catherine
Published: June 2010

El arte como jubilo critico.

Nosotros consideramos aquí la actividad creadora del arte como homologa a la actividad del científico que imagina sus conceptos, del técnico que imagina sus dispositivos. El arte no es pues examinado como ilustrador de los "describrimientos de la ciencia o de la técnica (papel que juega a menudo en las exposiciones y museos científicos y o técnicos) es necesario considerarlo como un acto de un imaginario creador, al mismo título que la actividad de investigación científica.

Pero el trabajo del artista que se encuentra con los conceptos científicos o técnicos es del mismo orden que de l'investigador, del inventor ? Con el fin de avanzar en esta reflexión, lo abordaremos bajo el ángulo particular : aquel de la puesta en oliras y operaciones de dos tipos de actores, en ciertas ocasiones de exposiciones en las cuales, hemos buscado a establecer un diálogo entre las dos aproximaciones. Y luego analizaremos ciertos aspectos de las primeras acciones experimentales de clases inter-museos ciencias y artes.
La ville, lieu d'éducation à l'environnement
Authors: Lapoix Catherine , Lapoix François
Published: June 2010

La ciudad, lugar de educación al medio ambiente.

Después de haber mostrado como la nueva pedagogía de descubrimiento del medio urbano puede ser una ayuda a la educación al medio ambiente, los autores presentan una experimentación realizada en Melun-Sénart a propósito del medio urbano.

Van presentando diferentes instrumentos orignales de tal educación urbana, así como las estructuras, y los actores de la investigación pedagógica. Aparece que lo que prevale en ese tipo de estudio, es el descubrimiento de las ciencias humanas y la educación de los sentidos.

Los autores dan ciertos resultados de la evaluación, y enumeran los principales propósitos de esa nueva deucación cuya finalidad es formar niños-ciudadanos, capaces de llegar a ser gerentes del futuro urbano.
Alors! Raconte-moi ton excursion de géologie !
Authors: Jacob Jean-Pierre
Published: June 2010

Well - tell me about your geology excursion !

The writer describes an innovation in one of his classes, with 13-14-years olds : during the whole year, his pupils were acquiring the necessary skills for producing reports on geological excursions.

Various tools are presented, which aim at helping the pupils to write and to draw, at first with much guidance from the teacher, but progressively less and less. Students are often strongly motivated for this type of work, and are aware of its potential use in other disciplines.

In Natural Science, writing takes up time : the present syllabus is so heavy, that detailed, individual scientific texts produced in class will long remain exceptional in our secondary education.
"Prendre le bâton de l'expérience..."
Authors: Lacombe Geneviève
Published: June 2010

Le statut de l'expérience au XVIIIe siècle peut-il nous aider à relativiser l'image que nous en donnent les Instructions Officielles inspirées de Claude Bernard ? Comment peut-on faire, en biologie, dans le second cycle, l'expérience de l'expérimentation ?
Deux approches pour modifier les activités de résolution de problèmes en physique dans l'enseignement secondaire : une tentative de synthèse
Authors: Dumas-carré Andrée , Caillot Michel , Martinez-Torregrossa Joaquim , Gil-Pérez Daniel
Published: June 2010

Dans cet article nous présentons un cadre théorique pour analyser les activités de résolution de problèmes "papier crayon" issu de la confrontation des recherches menées par deux équipes (Gil Perez D. et Martinez Torregrossa J. en Espagne et Caillot M. et Dumas-Carré A. en France) dans le domaine de la physique.

Le point de départ commun des deux équipes est de considérer que l'échec généralisé des élèves ne peut être imputé seulement (ni principalement) à des caractéristiques ou des lacunes des élèves, mais que la plus grande responsabilité doit être cherchée du côté de la didactique habituelle. Ce qui doit être remis en question de façon prioritaire est la conception même des activités de résolution de problèmes. Cette remise en question de la conception didactique commence par une interrogation sur le concept de problème lui-même. De même, le comportement habituellement retenu comme modèle (celui de l'expert) est remis en question ; le comportement proposé comme modèle est celui du chercheur scientifique.
Vers des activités didactiques de mise au point de modèles de physique avec des micro-ordinateurs
Authors: Durey Alain , Journeaux Roger
Published: June 2010

Construire des activités scolaires utilisant l'ordinateur doit s'inspirer de l'évolution provoquée par l'introduction des ordinateurs dans les pratiques professionnelles en établissant des relations définissables et contrôlables avec ces "pratiques de références". Deux caractéristiques générales de ces pratiques émergent : la prise en compte nécessaire de relations nouvelles avec le domaine empirique et l'utilisation d'une méthodologie de mise au point de modèles par approximations successives. En explorant dans les deux sens l'espace entre cadre scolaire et pratiques de référence, on élabore à la fois des outils pédagogiques (d'un autre ordre que les didacticiels) et des données utilisables pour la technique : c'est la base d'une méthodologie d'utilisation didactique des ordinateurs en physique.
Mouvement et vitesse au cours élémentaire
Authors: Invernizzi Susanna , Marioni Cesare , Sabadini Piera
Published: June 2010

Nous avons réalisé cette recherche dans une classe de cours élémentaire (enfants de 7-8 ans) sur les notions d'espace, de temps et de vitesse. Notre propos était d'analyser, en classe, les représentations que les enfants se font de ces trois notions et d'élaborer des actions didactiques qui, en s'appuyant sur les procédés spontanés des enfants, leur permettent d'élaborer plus facilement ces notions de physique.
Quels textes scientifiques espère-t-on voir les élèves écrire? Quelques exemples de l'utilisation d'une modélisation des textes scientifiques dans un contexte d'évaluation formatrice
Authors: Veslin Jean
Published: June 2010

Cet article propose une modélisation des textes scientifiques. Ce modèle est un outil permettant de mettre en place un dispositif qui utilise l’évaluation comme moteur de l’apprentissage (cf. "Evaluation formatrice" définie par Bonniol, Nunziati, Vial et coll.). Il est utilisé pour aider les élèves à s’approprier les critères qui caractérisent les textes scientifiques, et leur permettre ainsi de réaliser de tels textes.
Approche didactique de quelques aspects du concept d'écosystème. Introduction
Authors: Astolfi Jean-Pierre
Published: June 2010

Aproximación didáctica de algunos aspectos del concepto de ecosistema.

Tres artículos de este numero de Aster, relacionados a las nociones de Medio, Población y de Relaciones alimenticias prolongan la publicación de un precedente informe de investigación.

Esta introducción desarrolla la problemática del conjunto que orientó la redacción de estos artículos, insistiendo particularmente sobre los dos conceptos didácticos de objetivo obstáculo y de nivel/registro de formulación.
L'écologie en livres et en images
Authors: Toudic Claudine , Ginsburger-Vogel Yvette
Published: June 2010

Pour les enseignants et pour les élèves, de l'école élémentaire à la classe de seconde : des livres, des diapositives et des films permettant de se former et de s'informer sur tous les domaines de l'écologie.
Utilisation des représentations enfantines en biologie et formation des maîtres
Authors: De Vecchi Gérard
Published: June 2010

Using children's representations in biology teaching and in teacher-training.

This article develops some of the ideas put forward in a thesis on the importance of taking representations into account. The use of these in the classroom provides tools for prediction and anticipation, but also for elaboration and diagnosis. For teacher-training, representations are valuable in throwing light on "what" and "how" to teach, and also in helping to understand how scientific knowledge is built up.
Enseignement de l'énergie. Une recherche pluridisciplinaire de l'INRP
Authors: Darot Éliane
Published: June 2010

Cette recherche demandée à 1'INRP par différents organismes oeuvrant dans le domaine énergétique s'est surtout axée sur une approche pluridisciplinaire cohérente du "savoir-énergie". Elle a donné lieu à la réalisation, dans plusieurs collèges et lycées, de progressions pluridisciplinaires importantes par leur durée et l'intérêt suscité auprès des élèves. Elle a conduit ses concepteurs à élaborer des dossiers pédagogiques qui devraient aider les enseignants désireux de s'engager dans un travail pluridisciplinaire à propos de l'énergie.
Eléments d'une bibliographie concernant l'enseignement de l'énergie au niveau des collèges
Authors: Koliopoulos Dimitris , Tiberghien Andrée
Published: June 2010

L’enseignement de l'énergie fait l'objet de recherches et de propositions didactiques depuis une dizaine d'année, à la suite notamment de la crise pétrolière. Cette bibliographie recense les études conduites au niveau du collège et portant sur trois aspects principaux : l'analyse conceptuelle de la matière avec ses composantes historiques et épistémologiques, la connaissance des conceptions des élèves au sujet de l'énergie et leur évolution, la caractérisation des projets d'enseignement de l’énergie à caractère curriculaire.
Un instrument d'analyse des modèles implicites de l'enseignement scientifique chez les enseignants
Authors: Vérin Anne , Peterfalvi Brigitte
Published: June 2010

A technique for analysing implicit models teachers have of science teaching.

The "Q-sort" technique is used here as a means of exploring the different conceptions that science teachers have of their teaching, and to measure what can be imputed to personal choice of values in the research work they are associated with.
Quelques représentations à propos de la photosynthèse
Authors: Rumelhard Guy
Published: June 2010

Dans le cadre des programmes antérieurs un séminaire a été consacré aux représentations à propos de la photosynthèse.

S'appuyant sur trois types d'analyses, celle de réponses d'élèves obtenues à partir de questionnement en classe, celle d'études historiques faites dans une optique épistémologique, celle de manuels scolaires, ce travail tente de dégager certaines difficultés qui peuvent se présenter dans l'appropriation des concepts de la photosynthèse. Quelques propositions sont discutées, dans une perspective Interdisciplinaire, pour surmonter ces obstacles et résistances.
Energie et mouvement. Représentations à partir de l'étude de jouets mobiles
Authors: Agabra Jacqueline
Published: June 2010

L'analyse des comptes rendus de séquences de classe de l'école élémentaire qui visent à introduire la notion d'énergie à partir de jouets mobiles montre que , dans ce contexte, les enfants produisent des représentations pour expliquer, Ils décrivent ainsi préférentiellement les mécanismes à l'aide de chaînes cinématique même si parfois ils citent la source d'énergie. Persuadés que la persistance d'un mouvement implique le contact permanent avec l'agent causal, ils construisent un modèle hydraulique qui réduit l'électrique au mécanique. Ils utilisent aussi la notion d'élan qu'ils apparentent à un capital de force ou d'énergie, sans que toutefois les idées d'interaction ou de transfert soient nécessairement présentes.
Possibilités et obstacles à propos de l'utilisation d'un système Logo
Authors: Zimmermann Jean-Luc , Nidegger Christian , Giordan André
Published: June 2010

L’introduction de micromondes au sein des écoles primaires, de machines et de langages nouveaux, nécessite une vigilance extrême quant à la construction du savoir chez les enfants et aux stratégies de formation à mettre en place. Une première phase de recherche réalisée en condition d'apprentissage permet d'objectiver les obstacles rencontrés et d'aboutir à des réflexions, des propositions techniques et pédagogiques sur l'utilisation de l'outil informatique.
Statut et rôle des modèles dans le travail scientifique et dans l'enseignement de la biologie
Authors: Rumelhard Guy
Published: June 2010

Status and role of models in scientific work and in the teaching of biology.

The word model is increasingly used in the vocabulary of science, and in teaching. Does this mean that we have a new scientific method in Biology, or a new philosophy of science ? The author, after analysing several historical and contemporary examples, elucidates certain common properties of analogical and formalised models, and defines the principal characteristics of the evolution of modélisation. He compares this scientific process with classical analytical experimentation, and describes three types of models used in Biology. Finally he underlines the principal obstacles, the false frontiers and the true limits to the use of models as a mean of reducing complexity. These limits are made apparent if attention is given to the specificity of the biological object and to the possibility of illness.
De l'interrupteur au relais électronique, du relais électromagnétique au transistor
Authors: Canal Jean-Loup
Published: June 2010

From switch to electronic relay, from electro-magnetic relay to transistor.

We suggest that, in the field of science didactics, the introduction of modelisation can be an aid to the building up of knowledge. Without aiming at the rigour and efficacity of certain scientific models, we wish to show the effects of modelisation in the internalisation of knowledge. We base this hypothesis on the fact that one of the functions of models, the explanatory function, makes use of analogy. We give examples here in which, to explain the role of the electro magnetic relay, the mechanical switch serves as a model, then the relay itself becomes a model of the transistor. The idea of a model, in these situations, is used in the limited sense of a tool for thought, simplifying the complexity of reality. It will be seen how pupils aged 10-11 (highest primary class) were able, by means of this aid, to integrate the first principles of the transistor used as a switch.
Circuits et modélisation
Authors: Sarrazin Liliane , Genzling Jean-Claude
Published: June 2010

Les deux modèles présentés ci-dessous différent non seulement par leur nature, mais aussi par leur champ de validité : ils n’ont pas été construits pour résoudre le même problème. ils montrent bien la diversité des modèles qu’on peut construire et utiliser dans un domaine donné. Ils remplissent cependant les mêmes fonctions : interpréter des faits expérimentaux et si possible en prévoir d'autres, ils illustrent la même méthode et c'est cette méthode (la modélisation) que devront peu à peu maîtriser nos élèves.
Gestion d'activités de modélisation en classe
Authors: Lemeignan Gérard , Weil-Barais Annick
Published: June 2010

Regulating modelisation activity in the classroom.

Two ways of regulating the formation of knowledge in a shool context are envisa ged : one using the building up of knowledge, the other the appropriation of knowledge. By studying the gap between the pupils’ first conceptions and the conceptualisation which they should have reached when they leave shool, we are led to recommend a double approach, involving the two different ways.

The description of a teaching sequence, introducing the "quantity of movement" in a "2nd class" (15-16 year-olds), gives practical indications on this approach, which seems to help pupils to acquire competence in the modélisation of situations in physics. Without changing the content of the syllabus, it seems possible to bring more pupils to a mastery of the methods and content of physics, provided a suitable regulation of class activities is organized to this end.
Les représentations du cerveau : modèles historiques
Authors: Mein Marie-Thérèse
Published: June 2010

Une question essentielle posée dès le début des temps historiques est celle de la spécificité des phénomènes psychiques et de leur localisation, ainsi que celle du rapport entre ces phénomènes et notre corps matériel.

Au cours de l’Histoire des Sciences, la réponse à ces questions a pris des formes variées : thèse cardiocentrique ou céphalocentrique, cerveaux-machines, cerveau-mosaïque ou cerveau global se sont succédé ou plutôt ont coexisté sans se remplacer tout à fait. Le présent travail cherche à caractériser ces divers modèles explicatifs afin de mieux situer les modèles de notre temps.
Beam-excited whistler waves at oblique propagation with relation to STEREO radiation belt observations
Authors: Sauer K. , Sydora R. D.
Published: June 2010

Abstract. Isotropic electron beams are considered to explain the excitation of whistler waves which have been observed by the STEREO satellite in the Earth's radiation belt. Aside from their large amplitudes (~240 mV/m), another main signature is the strongly inclined propagation direction relative to the ambient magnetic field. Electron temperature anisotropy with Te⊥>Te||, which preferentially generates parallel propagating whistler waves, can be excluded as a free energy source. The instability arises due to the interaction of the Doppler-shifted cyclotron mode ω=−Ωe+kVbcosθ with the whistler mode in the wave number range of kc/ωe≤1 (θ is the propagation angle with respect to the background magnetic field direction, ωe is the electron plasma frequency and Ωe the electron cyclotron frequency). Fluid and kinetic dispersion analysis have been used to calculate the growth rate of the beam-excited whistlers including the most important parameter dependencies. One is the beam velocity (Vb) which, for instability, has to be larger than about 2VAe, where VAe is the electron Alfvén speed. With increasing VAe the propagation angle (θ) of the fastest growing whistler waves shifts from θ~20° for Vb=2VAe to θ~80° for Vb=5VAe. The growth rate is reduced by finite electron temperatures and disappears if the electron plasma beta (βe) exceeds βe~0.2. In addition, Gendrin modes (kc/ωe≈1) are analyzed to determine the conditions under which stationary nonlinear waves (whistler oscillitons) can exist. The corresponding spatial wave profiles are calculated using the full nonlinear fluid approach. The results are compared with the STEREO satellite observations.
Fractal metrology for biogeosystems analysis
Authors: Torres-Argüelles V. , Oleschko K. , Tarquis A. M. , Korvin G. , Gaona C. , Parrot J.-F. , Ventura-Ramos E.
Published: June 2010

Abstract. The solid-pore distribution pattern plays an important role in soil functioning being related with the main physical, chemical and biological multiscale and multitemporal processes. In the present research, this pattern is extracted from the digital images of three soils (Chernozem, Solonetz and "Chocolate'' Clay) and compared in terms of roughness of the gray-intensity distribution (the measurand) quantified by several measurement techniques. Special attention was paid to the uncertainty of each of them and to the measurement function which best fits to the experimental results. Some of the applied techniques are known as classical in the fractal context (box-counting, rescaling-range and wavelets analyses, etc.) while the others have been recently developed by our Group. The combination of all these techniques, coming from Fractal Geometry, Metrology, Informatics, Probability Theory and Statistics is termed in this paper Fractal Metrology (FM). We show the usefulness of FM through a case study of soil physical and chemical degradation applying the selected toolbox to describe and compare the main structural attributes of three porous media with contrasting structure but similar clay mineralogy dominated by montmorillonites.
A stochastic design rainfall generator based on copulas and mass curves
Authors: Vandenberghe S. , Verhoest N. E. C. , Buyse E. , De Baets B.
Published: June 2010

Abstract. The use of design storms can be very useful in many hydrological and hydraulic practices. In this study, the concept of a copula-based secondary return period in combination with the concept of mass curves is used to generate design storms. The analysis is based on storms selected from the 105 year rainfall time series with a 10 min resolution, measured at Uccle, Belgium. In first instance, bivariate copulas and secondary return periods are explained, together with a focus on which couple of storm variables is of highest interest for the analysis and a discussion of how the results might be affected by the goodness-of-fit of the copula. Subsequently, the fitted copula is used to sample storms with a predefined secondary return period for which characteristic variables such as storm duration and total storm depth can be derived. In order to construct design storms with a realistic storm structure, mass curves of 1st, 2nd, 3rd and 4th quartile storms are developed. An analysis shows that the assumption of independence between the secondary return period and the internal storm structure could be made. Based on the mass curves, a technique is developed to randomly generate an intrastorm structure. The coupling of both techniques eventually results in a methodology for stochastic design storm generation. Finally, its practical usefulness for design studies is illustrated based on the generation of design storm ensembles and rainfall-runoff modelling.
Response of growing swine to dietary exposure to pure fumonisin B1 during an eight‐week period: Growth and clinical parameters
Authors: Rotter Barbara A. , Thompson Brian K. , Prelusky Dan B. , Trenholm H. Locksley , Stewart Brian , Miller J. David , Savard Marc E.
Published: June 2010

Consumption of corn or corn‐based products contaminated with Fusarium moniliforme/fumonisins has been associated with a variety of animal and human diseases and is a major food/feed safety issue. This study focused on the clinical toxicity and performance parameters in growing swing exposed to low to moderate levels of pure fumonisin B1 (FB1) for 8 weeks. Male (castrated) and female pigs were fed diets containing 0, 0.1, 1.0, and 10 mg FB1/kg diet (ppm). Weight gains and feed consumption were measured weekly. Blood samples were collected throughout the study, and various clinical and hematological parameters were measured. Because fumonisins are potent inhibitors of sphingolipid biosynthesis, sphinganine and sphingosine concentrations were determined in the liver, lung, and kidney. Organ weights and carcass quality were measured at the end of the trial.

In general, male pigs were more adversely affected by FB1 in the diet than females. The average daily gain for males decreased by 8% for pigs fed 1.0 ppm and by 11% at 10.0 ppm, when compared to the control (0 ppm). Males fed 0.1 ppm showed an erratic growth pattern during the first 5 weeks of the experiment. Feed consumption for the same animals was somewhat higher than that of the controls during each of the first 4 weeks but thereafter was 6–7% lower each week as compared to controls. Female pigs fed FB1‐diets showed a general enhancement of feed consumption until week 4. Among clinical chemistry parameters, cholesterol increased in males for the 1.0 and 10.0 ppm diets as compared to controls after 2 weeks, while the levels in both sexes were elevated for the 1.0 ppm diet only by the end of the experiment. Serum liver enzyme concentrations were altered during week 2 only. Changes were observed in the weight of the pancreas and adrenals for male pigs fed FB1 diets as compared to controls. The free sphinganine to free sphingosine ratio (biomarker of exposure in FB1‐consuming animals) increased in all three organs for the 10 ppm diet, regardless of sex. The study indicated that FB1 can cause different effects at each dose level, at concentrations as low as 0.1 ppm (showing erratic growth) followed by a reduced growth and biochemical abnormalities in blood (1.0 ppm) and sphingolipid alterations in tissues (10.0 ppm). Some of these effects occurred below the exposure level that caused alteration in sphingolipid metabolism. c̊ 1996 Wiley‐Liss, Inc
Enzymatic oxidation products of allelochemicals as a basis for resistance against insects: Effects on the corn leafhopper dalbulus maidis
Authors: Dowd Patrick F. , Vega Fernando E.
Published: June 2010

Oxidation products of com allelochemicals generated by peroxidases or tyrosinases were tested in 10% sucrose solutions for effects on the com leafhopper Dalbulus maidis. Some reduction in feeding was noted with hydrogen peroxide (a cofactor for peroxidase). Significant reduction in feeding was noted with chlorogenic acid, ferulic acid, p‐coumaric acid, and 6‐methoxybenzoxazolinone (MBOA), but not rutin at 400 ppm in solution. Oxidation products of these compounds all caused significantly less feeding by the leafhoppers compared to the original compound. Oxidation products generated by peroxidase from ferulic acid and 6‐methoxybenzoxazolinone caused significant mortality to the leafhoppers within 5 days. Thus, provided conditions are such that oxidizing enzymes and allelochemicals can interact due to damage by insects, resistance may be significantly enhanced by the oxidized products as opposed to the effects of the allelochemicals alone.
(2,4‐cis)‐asimicinone and (2,4‐trans)‐asimicinone: Two novel bioactive ketolactone acetogenins from asimina triloba (annonaceae)
Authors: Zhao Geng‐Xian , Chao Jin‐Feng , Zeng Lu , McLaughlin Jerry L.
Published: June 2010

Two novel bioactive ketolactone Annonaceous acetogenins, (2,4‐cis)‐asimicinone (1) and (2,4‐trans)‐asimicinone (2), have been isolated from Asimina triloba (Annonaceae) by bioactivity directed fractionation The separation of these two epimeric compounds was achieved by HPLC methods using a Si gel normal phase column eluted with acetone in hexane gradients. The assignments of cis or trans stereochemistry of the ketolactone moieties were made on the bases of 1H‐1H COSY and NOESY experiments. 1 and 2 showed selective cytotoxicities against A‐549 (human lung cancer) and MCF‐7 (human breast cancer) cell lines with ED50 values as low as <10−7 μg/ml with 2 being the more active isomer.
Fumonisin B1 production by fusarium proliferatum strain M5991 in a modified myro liquid medium
Authors: Dantzer W. R. , Pometto A. L. , Murphy P. A.
Published: June 2010

Fusarium proliferatum strain M5991 cultures were grown in shake flasks containing modified Myro (MM) medium (MgSO4 reduced to 0.5 g/L) plus 0, 0.25, 0.50, 0.75, 1.00, or 1.25% (v/v) hot‐water corn‐hull‐extract (CHE) for 69 days. After 4 days of incubation, shake flask liquid cultures with 0.75, 1.00, and 1.25% (v/v) CHE showed a reduction in pH from 6.0 to 2.6 and consumed sucrose at > 6.3 g/L/d. After 69 days of incubation, the same shake flask cultures produced over 7.8 g/L cell mass and over 990 mg/L fumonisin B1 (FB1). A minimum CHE level of 0.75% was recommended for enhanced FB1 production by F. proliferatum strain M5991 During three serial (10, 12, and 12 L) batch fermentations in MM medium + 1.00% (v/v) CHE (first batch only), F. proliferatum strain M5991 produced FB1 concentrations of 619, 659, and 375 mg/L after 35, 47, and 52 days of incubation, respectively. By analysis, a total yield of 20 g FB1 was obtained from three serial batch fermentations
SARs of annonaceous acetogenins in rat liver mitochondria
Authors: Alfonso Dorothée , Johnson Holly A. , Colman‐Saizarbitoria Trina , Presley Christopher P. , McCabe George P. , McLaughlin Jerry L.
Published: June 2010

The Annonaceous acetogenins represent a class of compounds with diverse bioactivities, including promising cytotoxicites. These are due, at least in part, to inhibition of complex I in the oxidative phosphorylation pathway in mitochondria. Fourteen Annonaceous acetogenins were tested in a rat liver mitochondrial oxygen uptake assay to probe additional structure‐activity relationships. In this subcellular assay, the activity of non‐adjacent bis‐THF ring acetogenins depends on the distance between the two THF rings; the activity decreases to that of a mono‐THF ring acetogenin if the distance is too long. When one THF ring is replaced with a tetrahydropyran ring, the activity remains comparable. The configuration of the THF ring, in mono ring compounds, seems to be more important than stereochemical differences in the rings of adjacent bis‐THF ring compounds. Bullatacin, an adjacent bis‐THF ring acetogenin, was used as a standard compound in every run to normalize the data. c̊ 1996 Wiley‐Liss, Inc.
A new interval‐based method to characterize estimability
Authors: Reynet O. , Jaulin L.
Published: June 2010

Estimability is a property that states the accuracy of the parameter estimation in the case of experimental data. This paper defines a new method based on interval analysis and set inversion to characterize estimability in the case of a bounded additive noise. To illustrate this new method, the time difference of arrival (TDOA) passive location estimability is evaluated. Copyright © 2010 John Wiley & Sons, Ltd.
Dynamic Collapse Mechanisms in Metal Foam Expansion
Authors: Lehmhus Dirk
Published: June 2010

The study provides insight into decomposition of titanium hydride as foaming agent for powder metallurgically produced aluminum foams. Decomposition is characterized using thermal and kinetic analysis, allowing prediction of decomposition reactions. Such predictions are made for various time–temperature cycles, which are experimentally evaluated in parallel foaming experiments. A new explanation of foam collapse is derived from the results, which interprets hints at a maximum gas release rate, limiting maximum expansion, in terms of the existence of a maximum cell wall stretching rate and expanding foam can sustain. Thus a dynamic collapse criterion is added to existing static ones.
Fabrication of Sub‐10 nm Metallic Lines of Low Line‐Width Roughness by Hydrogen Reduction of Patterned Metal–Organic Materials
Authors: Nedelcu Mihaela , Saifullah Mohammad S. M. , Hasko David G. , Jang Arang , Anderson David , Huck Wilhelm T. S. , Jones Geraint A. C. , Welland Mark E. , Kang Dae Joon , Steiner Ullrich
Published: June 2010

The fabrication of very narrow metal lines by the lift‐off technique, especially below sub‐10 nm, is challenging due to thinner resist requirements in order to achieve the lithographic resolution. At such small length scales, when the grain size becomes comparable with the line‐width, the built‐in stress in the metal film can cause a break to occur at a grain boundary. Moreover, the line‐width roughness (LWR) from the patterned resist can result in deposited metal lines with a very high LWR, leading to an adverse change in device characteristics. Here a new approach that is not based on the lift‐off technique but rather on low temperature hydrogen reduction of electron‐beam patterned metal naphthenates is demonstrated. This not only enables the fabrication of sub‐10 nm metal lines of good integrity, but also of low LWR, below the limit of 3.2 nm discussed in the International Technology Roadmap for Semiconductors. Using this method, sub‐10 nm nickel wires are obtained by reducing patterned nickel naphthenate lines in a hydrogen‐rich atmosphere at 500 °C for 1 h. The LWR (i.e., 3 σLWR) of these nickel nanolines was found to be 2.9 nm. The technique is general and is likely to be suitable for fabrication of nanostructures of most commonly used metals (and their alloys), such as iron, cobalt, nickel, copper, tungsten, molybdenum, and so on, from their respective metal–organic compounds.
Surface‐Protected Etching of Mesoporous Oxide Shells for the Stabilization of Metal Nanocatalysts
Authors: Zhang Qiao , Lee Ilkeun , Ge Jianping , Zaera Francisco , Yin Yadong
Published: June 2010

Nanoparticles of transition metals, particularly noble metals, are widely used in catalysis. However, enhancing their stability during catalytic reactions has been a challenge that has limited the full use of the benefits associated with their small size. In this Feature Article, a general “encapsulation and etching” strategy for the fabrication of nanocatalyst systems is introduced in which catalyst nanoparticles are protected within porous shells. The novelty of this approach lies in the use of chemical etching to assist the creation of mesopores in a protective oxide shell to promote efficient mass transfer to encapsulated metal nanoparticles. The etching process allows for the direct transformation of dense silica coatings into porous shells so that chemical species can reach the catalyst surface to participate in reactions while the shells act as physical barriers against aggregation of the catalyst particles. By using the surface‐protected etching process, both yolk–shell and core–satellite type nanoreactors are synthesized and their utilization in liquid‐ and gas‐phase catalysis is demonstrated. The thermal and chemical stability of the metallic cores during catalytic reactions is also investigated, and further work is carried out to enhance recyclability via the introduction of superparamagnetic components into the nanoreactor framework.
The studies on the motion of the sine‐Gordon kink on a curved surface
Authors: Dobrowolski T.
Published: June 2010

The numerical studies of the kink motion on a curved manifold were performed. Examples of the curved surfaces are considered in detail. Enlarging the kink width in curved regions of the surface and reduction of its speed is confirmed. Reflection of the kink front from the large curvature areas is observed. The influence of the curvature on the speed of the Vachaspati waves is also observed.
Shape‐Persistent Organic Cage Compounds by Dynamic Covalent Bond Formation
Authors: Mastalerz Michael
Published: June 2010

One area of supramolecular chemistry involves the synthesis of discrete three‐dimensional molecules or supramolecular aggregates through the coordination of metals. This field also concerns the chemistry of supramolecular cage compounds constructed through the use of such coordination bonds. To date, there exists a broad variety of supramolecular cage compounds; however, analogous organic cage compounds formed with only covalent bonds are relatively rare. Recent progress in this field can be attributed to important advances, not least the application of dynamic covalent chemistry. This concept makes it possible to start from readily available precursors, and in general allows the synthesis of cage compounds in fewer steps and usually higher yields.
Thermal decomposition of cellulose/synthetic polymer blends containing grafted products. V. Cellulose/polystyrene blends
Authors: Nishioka Noboru , Funakoshi Miyuki , Inamoto Kohji , Uno Masakuni , Ueda Akira
Published: June 2010

Homogeneous grafting of styrene onto cellulose was carried out in a dimethylacetamide/lithium chloride solvent system. The grafted products were added to cellulose/polystyrene (PS) blends as compatibilizers. The thermal decomposition behavior of the blends was investigated by thermogravimetry. The thermal stability of the blends decreased with an increase in grafted product content. The crystallinity of the blends decreased with grafted product content. The microphase‐separated structures of the blends became finer with grafted product content. The glass transition temperatures for cellulose and PS in the blends were lowered with grafted product content. Differences in thermal decomposition behavior of the blends were correlated with compatibility. Thermogravimetry was effective for compatibility estimation in cellulose/PS blends containing grafted products. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Characteristics of soy protein isolate‐montmorillonite composite films
Authors: Lee Jung‐Eun , Kim Ki Myong
Published: June 2010

Soy protein isolate/montmorillonite (SPI/MMT) nanocomposite films were prepared in which MMT was used as a nanofiller at 0, 3, 6, 9, 12, and 15 wt % relative to SPI dry weight. Effects of MMT on film properties including tensile strength, elongation at break, total soluble matter, water vapor permeability, and oxygen permeability were assessed. X‐ray diffraction patterns were determined, and morphologies of SPI and the SPI‐MMT composite films were visualized by scanning electron microscopy. Mechanical and barrier properties were improved by evidenced increases in tensile strength and modulus, and decreases in permeability to water vapor and oxygen. MMT concentrations of 3%–12% were optimal for improving functional properties of the composite films. X‐ray diffraction and scanning electron microscopy examinations revealed the formation of an intercalated and exfoliated structure on the addition of MMT into the SPI matrix. We conclude that intercalated and exfoliated MMT silicates enhance mechanical and barrier properties of SPI films. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Effect of styrene–ethylene–butadiene–styrene and its synergetic effect with ethylene vinyl acetate on the mechanical, thermal, dielectric, and water‐treeing behaviors of crosslinked polyethylene
Authors: Ma Zhisen , Jiang Pingkai , Wang Lichun , Yang Junsheng
Published: June 2010

In this study, we investigated the effect of an aromatic polymer, styrene–ethylene–butadiene–styrene (SEBS), on the water‐tree resistance of crosslinked polyethylene (XLPE), and the synergetic effect of SEBS and ethylene vinyl acetate (EVA) was also investigated. The XLPE/SEBS and XLPE/SEBS/EVA samples were characterized by means of differential scanning calorimetry, scanning electron microscopy, mechanical measurements, and an accelerated water‐treeing experiment, and the obtained results clearly show the relevant influence of SEBS and EVA, and as expected, the addition of SEBS and EVA was found to synergistically influence the water‐tree resistance of XLPE more positively in comparison with that without the addition of EVA. In addition, it also indicated that the blends possessed excellent dielectric behaviors, such as the dielectric constant and dissipation factor. The crystallization of the blends decreased with increasing SEBS content and addition of EVA. However, the melting temperature of the blends increased with the addition of SEBS and EVA, but the melting temperature of the blends decreased with increasing SEBS content. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Controlled release of chlorpheniramine maleate through IPN beads of sodium alginate‐g‐methylmethacrylate
Authors: Lakshmi Narayana Reddy C. , Swamy B. Yerri , Prasad C. Venkata , Subha M.C.S. , Rao K. Chowdoji
Published: June 2010

Controlled release of chlorpheniramine maleate drug, through sodium alginate‐g‐methylmethacrylate (NaAlg‐g‐MMA) interpenetrating polymeric network beads, has been investigated. Beads were prepared by precipitating the viscous solution of NaAlg‐g‐MMA in acetone followed by cross‐linking with glutaraldehyde. The beads were characterized by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). Different formulations of beads were developed by varying amounts of MMA, cross‐linking agent, and drug concentration. DSC thermograms of chlorpheniramine maleate drug‐loaded NaAlg‐g‐MMA beads confirmed the molecular level distribution of drug in the polymer matrix. FTIR of beads confirm the grafting and cross‐linking, SEM of the beads suggested the formation of spherical particles. Swelling experiments on the beads provided an important information on drug diffusion properties. Release data have been analyzed using an empirical equation to understand the nature of transport of drug containing solution through the polymeric matrices. The controlled release characteristics of the matrices for chlorpheniramine maleate was investigated in pH 7.4 media. Drug was released in a controlled manner upto 12 h. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Synthesis and characterization of AB‐type copolymers poly(L‐lactide)‐block‐poly(methyl methacrylate) via a convenient route combining ROP and ATRP from a dual initiator
Authors: Wang Wei‐Wei , Ren Wu‐Yang , Jiang Long , Dan Yi
Published: June 2010

Diblock copolymers of poly(L‐lactide)‐block‐poly(methyl methacrylate) (PLLA‐b‐PMMA) were synthesized through a sequential two‐step strategy, which combines ring‐opening polymerization (ROP) and atom transfer radical polymerization (ATRP), using a bifunctional initiator, 2,2,2‐trichloroethanol. The trichloro‐terminated poly(L‐lactide) (PLLA‐Cl) with high molecular weight (Mn,GPC = 1–12 × 104 g/mol) was presynthesized through bulk ROP of L‐lactide (L‐LA), initiated by the hydroxyl group of the double‐headed initiator, with tin(II) octoate (Sn(Oct)2) as catalyst. The second segment of the block copolymer was synthesized by the ATRP of methyl methacrylate (MMA), with PLLA‐Cl as macroinitiator and CuCl/N,N,N′,N″,N″‐pentamethyldiethylenetriamine (PMDETA) as catalyst, and dimethyl sulfoxide (DMSO) was chosen as reaction medium due to the poor solubility of the macroinitiator in conventional solvents at the reaction temperature. The trichloroethoxyl terminal group of the macroinitiator was confirmed by Fourier transform infrared spectroscopy (FTIR) and 1H‐NMR spectroscopy. The comprehensive results from GPC, FTIR, 1H‐NMR analysis indicate that diblock copolymers PLLA‐b‐PMMA (Mn,GPC = 5–13 × 104 g/mol) with desired molecular composition were obtained by changing the molar ratio of monomer/initiator. DSC, XRD, and TG analyses establish that the crystallization of copolymers is inhibited with the introduction of PMMA segment, which will be beneficial to ameliorating the brittleness, and furthermore, to improving the thermal performance. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010