Les matériaux de structure utilisés dans le cœur des REP, comme par exemple les aciers austénitiques ou bien les alliages de zirconium, sont soumis à la fois à une forte irradiation neutronique ainsi qu’à divers chargements mécaniques. A l’échelle macroscopique, le comportement mécanique sous irradiation de ces matériaux est bien caractérisé. Cependant, à l’échelle microscopique, les mécanismes de déformation sous irradiation restent encore mal connus. De nombreux mécanismes de fluage d’irradiation ont été envisagés du point de vue théorique mais les données expérimentales existantes n’ont pu, pour l’heure, permettre de déterminer le mécanisme pertinent contrôlant la déformation.L'objectif de ce travail de thèse est justement d’apporter une contribution à la compréhension des mécanismes de fluage d’irradiation des métaux et alliages par la mise en œuvre d’une méthode expérimentale originale. Les irradiations sont reproduites par des irradiations aux ions lourds. Ces irradiations ont l’avantage de créer un dommage rapide sans activer la matière. Cependant l’épaisseur irradiée n’est que de plusieurs centaines de nanomètres. De telles épaisseurs nécessitent un dispositif expérimental spécifique pour l’application d’une charge sur l’échantillon. Le dispositif utilisé est basé sur l’utilisation de contraintes internes dans un film mince de nitrure de silicium pour déformer des films minces métalliques. Cette méthode a été conçue et développée par les équipes de Thomas Pardoen et Jean-Pierre Raskin à l’université catholique de Louvain, en Belgique.Après une démonstration de la faisabilité de l’étude et une adaptation du dispositif aux conditions d’irradiation, cette méthode a pu être utilisée avec succès pour reproduire une expérience de fluage d’irradiation à température ambiante sur un matériau modèle, le cuivre. Une loi de fluage en puissance 5 selon la contrainte a été trouvée sous irradiation sur des films de 200 et 500 nm d’épaisseur. Les observations au microscope électronique à balayage et en transmission suggèrent que les mécanismes de déformation reposent sur le glissement assisté par la montée.Cette loi apparait indépendante de la microstructure et de l’historique de chargement des éprouvettes. La montée, si elle intervient, ne semble pas contrôlée par des mécanismes de diffusion à longue distance mais par des interactions directes entre la cascade déplacements et les dislocations.Hors irradiation et après irradiation, le comportement mécanique des films a également pu être évalué. Les mécanismes de déformation semblent identiques dans les deux conditions. A vitesse de déformation modérée, la déformation est contrôlée par le glissement intragrannulaire des dislocations tandis qu’à basse vitesse un changement de mécanisme se produit. Le nouveau mécanisme reste toujours basé sur les dislocations mais une composante de glissement aux joints de grains semble apparaitre. Un durcissement post irradiation est observé du fait d’une densité importante de SFT dans les éprouvettes irradiées qui agissent comme des obstacles au glissement des dislocations / Structural materials used in the PWR cores, such as austenitic stainless steels or zirconium alloys, are exposed to a significant neutron flux and, at the same time, a stress from various mechanical loadings. At the macroscopic scale, the mechanical behavior under irradiation is well characterized. However, at a microscopic scale, the deformation mechanisms under irradiation still remain unknown. Many irradiation creep mechanisms have been proposed from a theoretical point of view but the available experimental data have not, for now, permitted to identify the relevant mechanism leading to the deformation.The objective of this thesis is precisely to improve our understanding of the irradiation creep mechanisms of metals and alloys by the development of a novel experimental method. In this method, the irradiation is produced by the use of heavy ions. This kind of irradiation has the advantage of a fast damage rate without an activation of the material. However the irradiated area is confined in a few hundreds of nanometers. Such thickness requires a specific experimental device to apply a stress on the specimen. This device is based on the release of internal stress in a silicon nitride film to deform a metallic thin film. This method was designed and developed at the Université Catholique de Louvain in Belgium by the teams of Thomas Pardoen and Jean-Pierre Raskin.After proving the feasibility of the study and adapting the device to the irradiation environment, the method has been used with success to reproduce an irradiation creep experiment at room temperature on a model material : copper. A single creep power law with a stress exponent of 5 has been found under irradiation on 200 and 500 nm thick films. The SEM and TEM observations suggest that the deformation mechanism rely on the glide of dislocations assisted by climb.This law seems to be independent of the microstructure and the loading history. The dislocation climb, if it occurs, would not be controlled by diffusion process at long distance but by direct interaction between displacement cascades and dislocations.The mechanical behavior of unirradiated and irradiated copper films have also been assessed. The deformation mechanisms seem to be the same in both cases. At a moderate strain rate, the deformation is controlled by the intragrannular glide of dislocations whereas at slow strain rate a change of mechanism takes place. The new mechanism still remains based on dislocations but a component of grain boundary sliding may appear. A post irradiation hardening has been observed on a 200 nm thick film due to the presence, in the irradiated samples, of a high density of SFT which act as obstacles against dislocation glide

Este trabalho descreve o desenvolvimento de um processo de fabricação de mini e microdispositivos fluídicos baseado na utilização de um equipamento de usinagem a laser de CO2 para criação de relevos sobre base de poli(metacrilato de metila) e na selagem térmica contra igual material. Inicialmente, o equipamento laser foi detalhadamente caracterizado, o que possibilitou elaborar métodos para a construção de microcanais de forma mais eficiente e com menores chances de defeitos. Tipicamente, os canais apresentaram seção transversal triangular em torno de 200 µm de largura e 100 µm de profundidade, sendo possível, no entanto, criar canais com outras características. A etapa de selagem entre a tampa e a base que apresentou melhores resultados consiste em pressurização acima de 6 kgf·cm-2 e aquecimento a 110 ºC durante 45 minutos, seguido de resfriamento por 1 h. Os microcanais selados por esta técnica, resistiram a pressões superiores a 3,5·kgf·cm-2. O processo desenvolvido se mostrou adequado para a criação de protótipos, sendo também suas principais características: (1) a facilidade de incorporação de regiões de grandes dimensões (como reservatórios) em conjunto com os microcanais, (2) número reduzido de etapas de produção e (3) boa uniformidade química da parede interna dos canais, o que é particularmente interessante para microdispositivos aplicados à Química Analítica / A microfabrication process based machining using CO2 laser on poly(methyl methacrylate) and thermal sealing is described. Initially, the laser equipment was characterized in detail, which allowed developing strategies for the construction of microchannels more efficiently and less failure-prone. Typically, the channels had a triangular cross section around 200 µm in width and 100 µm in depth. It is possible, however, create channels with other features. The sealing step that showed better results consists in to pressurize at 6 kgf·cm-2 and heating at 110 °C during 45 minutes, followed by natural cooling for 1 h. The microchannels sealed by using this procedure resisted pressures above 3.5 kgf·cm-2. The process proved to be adequate for prototyping and also has other main features: (1) easiness of incorporation of large regions (such as reservoirs) together with the microchannel; (2) reduced number of manufacturing steps and (3) good chemical uniformity of the inner wall of the channel, which is particularly interesting for microdevices applied to Analytical Chemistry.

Este trabalho teve como objetivo geral a produção de um equipamento pequeno, multifuncional, de baixo custo e útil para as áreas de engenharia química e de química. Quanto à área de engenharia química, manipulam-se amostras em dispositivos miniaturizados que possuem operações unitárias comuns, como por exemplo, misturadores, formação de spray e remoção de partículas. Em química, efetua-se o pré-tratamento de amostras gasosas e possível detecção de compostos orgânicos voláteis (VOCs). A metodologia utilizada seguiu os protocolos para produção de equipamento. O equipamento projetado e construído apresenta três partes distintas e com as seguintes características. As amostras, que podem ser liquidas ou gasosas, são admitidas ou em fluxo contínuo ou de modo estacionário. A manipulação de dispositivos miniaturizados, como por exemplo, mini-misturadores, ocorre em três eixos distintos, o que permite o uso de dispositivos tridimensionais. Para todas as amostras a detecção é baseada em micro-balança de quartzo, com 5 cristais piezelétricos de quartzo (PQC) medindo simultaneamente e independentemente a aquisição de dados online. Quanto a amostras gasosas, é possível a detecção de VOCs na faixa de ppm e em dispositivo miniaturizado (mini manifold) para distribuição do fluxo uniformemente nos 5 PQCs. Através do uso do spray é possível a detecção de gases, líquidos e particulados. O componente sensor nos PQCs é filme fino depositado por plasma e a base de HMDS, hexametildissilazana. Esses filmes foram modificados por exposição à radiação ultravioleta (UVC) e feixe de íons (Ar+ ou He2+), os filmes após exposição mostraram-se mais eficientes na discriminação de VOCs. O equipamento foi construído com modos convencionais de produção, como por exemplo, usinagem com máquinas operatrizes como torno mecânico e fresadoras, e com partes e peças de fácil aquisição no mercado nacional. / This work aimed the production of a small equipment, multi-functional, lowcost and useful for chemical engineering and chemistry areas. Regarding the chemical engineering area samples are handled in miniaturized devices having common unit operations such as mixing, spray forming and removing particles. In chemistry, the pretreatment of gaseous samples and detection of volatile organic compounds (VOCs) could be made. The methodology followed the protocols for production equipment. The equipment designed and built features three distinct parts with the following characteristics. Samples can be liquid or gaseous, they can be admitted or continuous flow or stationary mode. The manipulation of miniaturized devices, such as minimixers occurs in three distinct axes, which allows the use of three-dimensional devices. For all samples the detection is based on quartz microbalance with 5 piezoelectric quartz crystals (PQC) the online data are acquired by measuring simultaneously and independently. As for gaseous samples, it is possible the VOCs detection in the ppm range and miniaturized device (mini manifold) to flow evenly distribution in 5 PQCs. Through the use of spray it is possible to detect gases, liquids and particulates. The sensing component in PQCs is thin film deposited by plasma and the base of HMDS hexamethyldisilazane. These films were modified by exposure to ultraviolet radiation (UVC) and ion beam (Ar+ or He2+) films after exposure were more efficient in the discrimination of VOCs. The equipment was built with conventional production methods, such as, machining with machine tools such as lathes and milling machines,, and parts and pieces of easy acquisition in the domestic market.

O objeto central desta pesquisa é o termo \"Maker Innovation\", uma síntese de estratégias \"makers\", tornando-as legíveis, replicáveis e contextualizadas dentro de um processo de Inovação pelo Design. Este conceito foi alcançado através do estudo qualitativo: (1) das práticas abertas provenientes do \"Open Design\" e conceitos relacionados, (2) dos ambientes colaborativos do tipo Fab Lab, e (3) das ações de indivíduos intitulados \"makers\". Ambos estão fazendo emergir um novo sistema, o chamado Ecossistema Maker. / The central object of this research is the term \"Maker Innovation\", a synthesis of \"maker\" strategies, presented in a readable, replicable and contextualized manner within a process of Innovation by Design. This concept was achieved through qualitative study of open practices from: (1) the \"Open Design\" and re¬lated concepts, (2) collaborative environments like Fab Lab and (3) the actions of individuals entitled \"makers\". Both are bringing out a new system, called Ecosystem Maker.

Este trabalho teve como objetivo geral a produção de um equipamento pequeno, multifuncional, de baixo custo e útil para as áreas de engenharia química e de química. Quanto à área de engenharia química, manipulam-se amostras em dispositivos miniaturizados que possuem operações unitárias comuns, como por exemplo, misturadores, formação de spray e remoção de partículas. Em química, efetua-se o pré-tratamento de amostras gasosas e possível detecção de compostos orgânicos voláteis (VOCs). A metodologia utilizada seguiu os protocolos para produção de equipamento. O equipamento projetado e construído apresenta três partes distintas e com as seguintes características. As amostras, que podem ser liquidas ou gasosas, são admitidas ou em fluxo contínuo ou de modo estacionário. A manipulação de dispositivos miniaturizados, como por exemplo, mini-misturadores, ocorre em três eixos distintos, o que permite o uso de dispositivos tridimensionais. Para todas as amostras a detecção é baseada em micro-balança de quartzo, com 5 cristais piezelétricos de quartzo (PQC) medindo simultaneamente e independentemente a aquisição de dados online. Quanto a amostras gasosas, é possível a detecção de VOCs na faixa de ppm e em dispositivo miniaturizado (mini manifold) para distribuição do fluxo uniformemente nos 5 PQCs. Através do uso do spray é possível a detecção de gases, líquidos e particulados. O componente sensor nos PQCs é filme fino depositado por plasma e a base de HMDS, hexametildissilazana. Esses filmes foram modificados por exposição à radiação ultravioleta (UVC) e feixe de íons (Ar+ ou He2+), os filmes após exposição mostraram-se mais eficientes na discriminação de VOCs. O equipamento foi construído com modos convencionais de produção, como por exemplo, usinagem com máquinas operatrizes como torno mecânico e fresadoras, e com partes e peças de fácil aquisição no mercado nacional. / This work aimed the production of a small equipment, multi-functional, lowcost and useful for chemical engineering and chemistry areas. Regarding the chemical engineering area samples are handled in miniaturized devices having common unit operations such as mixing, spray forming and removing particles. In chemistry, the pretreatment of gaseous samples and detection of volatile organic compounds (VOCs) could be made. The methodology followed the protocols for production equipment. The equipment designed and built features three distinct parts with the following characteristics. Samples can be liquid or gaseous, they can be admitted or continuous flow or stationary mode. The manipulation of miniaturized devices, such as minimixers occurs in three distinct axes, which allows the use of three-dimensional devices. For all samples the detection is based on quartz microbalance with 5 piezoelectric quartz crystals (PQC) the online data are acquired by measuring simultaneously and independently. As for gaseous samples, it is possible the VOCs detection in the ppm range and miniaturized device (mini manifold) to flow evenly distribution in 5 PQCs. Through the use of spray it is possible to detect gases, liquids and particulates. The sensing component in PQCs is thin film deposited by plasma and the base of HMDS hexamethyldisilazane. These films were modified by exposure to ultraviolet radiation (UVC) and ion beam (Ar+ or He2+) films after exposure were more efficient in the discrimination of VOCs. The equipment was built with conventional production methods, such as, machining with machine tools such as lathes and milling machines,, and parts and pieces of easy acquisition in the domestic market.

Notre connaissance des mécanismes d’acquisition de la chimie des eaux continentales est limitée par la fréquence des prélèvements qui peuvent être réalisés sur le terrain. Échantillonner une rivière tous les 15 jours, c’est négliger une variabilité de sa composition qu’on commence à suspecter et qui renseigne sur des processus ou des variations de sources de courte période intégrés sur l’ensemble du bassin versant. L’automatisation des prélèvements et la mesure en temps réel est un défi important non seulement du point de vue de la compréhension des mécanismes contrôlant la chimie des eaux, de leur dynamique temporelle, des relations entre concentrations et débits, mais aussi du point de vue appliqué pour la détection des pollutions ponctuelles. Ce développement intéresse les professionnels de l’eau qui ne sont pas à ce jour contraint par la loi, mais qui pourraient le devenir. Dans le cadre du projet équipex CRITEX, un prototype de maison chimique appelé ”RiverLab”, véritable laboratoire d’analyses en temps réel sur le terrain a été développé et installé en novembre 2014 sur la bassin versant expérimental de l’Orgeval, un site étudié depuis 50 ans par les équipes de l’IRSTEA. Ce prototype est destiné à être déployé sur deux autres sites du réseau national des bassins versants (dispositif SOERE). Nous nous focalisons sur les deux principaux forçages naturels que subi un bassin versant à savoir les apports de précipitations et l’énergie solaire revisité sous l’angle de la haute fréquence / Our knowledge of the mechanisms of acquisition of inland water chemistry is limited by the frequency of sampling that can be carried out in the field. Sampling a river every 15 days means neglecting a variability in its composition that is beginning to be suspected and which informs processes or variations of short-term sources integrated over the entire catchment area. The automation of sampling and real-time measurement is an important challenge not only from the point of view of understanding the mechanisms controlling water chemistry, their temporal dynamics, the relations between concentrations and flows, but also from the point of view of applied for the detection of point pollution. This development is of interest to water professionals who are not yet legally constrained, but who could become so.As part of the CRITEX team project, a prototype of a chemical house called "RiverLab", a real laboratory for real-time field analysis, was developed and installed in November 2014 on the experimental watershed of Orgeval, a site studied for 50 years by the IRSTEA teams. This prototype is intended to be deployed on two other sites of the national watershed network (SOERE device). We focus on the two main natural forces that have undergone a watershed, namely precipitation inputs and solar energy revisited in terms of high frequency

O objeto central desta pesquisa é o termo \"Maker Innovation\", uma síntese de estratégias \"makers\", tornando-as legíveis, replicáveis e contextualizadas dentro de um processo de Inovação pelo Design. Este conceito foi alcançado através do estudo qualitativo: (1) das práticas abertas provenientes do \"Open Design\" e conceitos relacionados, (2) dos ambientes colaborativos do tipo Fab Lab, e (3) das ações de indivíduos intitulados \"makers\". Ambos estão fazendo emergir um novo sistema, o chamado Ecossistema Maker. / The central object of this research is the term \"Maker Innovation\", a synthesis of \"maker\" strategies, presented in a readable, replicable and contextualized manner within a process of Innovation by Design. This concept was achieved through qualitative study of open practices from: (1) the \"Open Design\" and re¬lated concepts, (2) collaborative environments like Fab Lab and (3) the actions of individuals entitled \"makers\". Both are bringing out a new system, called Ecosystem Maker.

Este trabalho descreve o desenvolvimento de um processo de fabricação de mini e microdispositivos fluídicos baseado na utilização de um equipamento de usinagem a laser de CO2 para criação de relevos sobre base de poli(metacrilato de metila) e na selagem térmica contra igual material. Inicialmente, o equipamento laser foi detalhadamente caracterizado, o que possibilitou elaborar métodos para a construção de microcanais de forma mais eficiente e com menores chances de defeitos. Tipicamente, os canais apresentaram seção transversal triangular em torno de 200 µm de largura e 100 µm de profundidade, sendo possível, no entanto, criar canais com outras características. A etapa de selagem entre a tampa e a base que apresentou melhores resultados consiste em pressurização acima de 6 kgf·cm-2 e aquecimento a 110 ºC durante 45 minutos, seguido de resfriamento por 1 h. Os microcanais selados por esta técnica, resistiram a pressões superiores a 3,5·kgf·cm-2. O processo desenvolvido se mostrou adequado para a criação de protótipos, sendo também suas principais características: (1) a facilidade de incorporação de regiões de grandes dimensões (como reservatórios) em conjunto com os microcanais, (2) número reduzido de etapas de produção e (3) boa uniformidade química da parede interna dos canais, o que é particularmente interessante para microdispositivos aplicados à Química Analítica / A microfabrication process based machining using CO2 laser on poly(methyl methacrylate) and thermal sealing is described. Initially, the laser equipment was characterized in detail, which allowed developing strategies for the construction of microchannels more efficiently and less failure-prone. Typically, the channels had a triangular cross section around 200 µm in width and 100 µm in depth. It is possible, however, create channels with other features. The sealing step that showed better results consists in to pressurize at 6 kgf·cm-2 and heating at 110 °C during 45 minutes, followed by natural cooling for 1 h. The microchannels sealed by using this procedure resisted pressures above 3.5 kgf·cm-2. The process proved to be adequate for prototyping and also has other main features: (1) easiness of incorporation of large regions (such as reservoirs) together with the microchannel; (2) reduced number of manufacturing steps and (3) good chemical uniformity of the inner wall of the channel, which is particularly interesting for microdevices applied to Analytical Chemistry.

Submitted by Helena Bejio (helena.bejio@unioeste.br) on 2018-06-09T00:30:28Z No. of bitstreams: 2 Jaqueline_Barbosa_2018.pdf: 754013 bytes, checksum: 0dd83e656c2f8d6bfc0e9ea67999e134 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2018-06-09T00:30:28Z (GMT). No. of bitstreams: 2 Jaqueline_Barbosa_2018.pdf: 754013 bytes, checksum: 0dd83e656c2f8d6bfc0e9ea67999e134 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2018-02-28 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The substances present in the plant material of green manures can act in the suppression of weeds by the release of allelopathic compounds. The objective of this study was to evaluate the allelopathic effect of the extracts of Dolichos lab lab, Pachyrhizus sp. and Sorghum bicolor, isolated and mixed, under different preparation method, in the weed species Bidens pilosa, Euphorbia heterophylla and Digitaria insularis. The experiment was realized in four stages, the collection of the vegetal material and the preparation of the aqueous extracts; influence of aqueous extracts on germination and initial development of B. pilosa, E. heterophylla and D. insularis, at completely randomized design was used, with factorial 7x4+T, and four replications; the effect of the aqueous extract were evaluated in post-emergence of B. pilosa, E. heterophylla and D. insularis, at completely randomized design was used, with six trataments and four replications, ermination and initial development of B. pilosa after the application of different fractions of aqueous extracts of D. lab lab, with dried plant material submitted to water bath, was used a completely randomized design with 14 trataments, ad four replications. In pre-emergence, the extract Pachyrhizus sp.+S. bicolor with freeze-dried plant material submitted to the water bath, reduced germination percentage, hypocotyl length and root length by 87%, 30% and 61%, respectively. For the E. heterophylla, the mixture Pachyrhizus sp.+S. bicolor, with freeze-dried plant material, caused the reduction of germianation percentage b 23%. For D. insularis, the extract Pachyrhizus sp.+S. bicolor, with freeze-dried plant material submitted to the water bath, reduced the percentage of germinations in 83%, and in 52% the length of the root. In post-emergence, the D. lab lab+Pachyrhizus sp. With freeze-dried plant material submitted to the water bath, reduced the dry mass of roots of B. pilosa plants by 21%, and by 18% the dry mass of roots of D. insularis, however, stimulated in 14% same variable in E. heterophylla. The fractionation of the D. lab lab extract with dried plant material, did not affect the germination percentage and dry mass of B. pilosa, but interfered the hypocotyl and the root. The fractionation of the D. lab lab + Pachyrhizus sp. + S.bicolor, with freeze—dried plant material submitted to the water bath, interfered in all variables. Is conclude that there is allelopathic effect of extracts of S. bicolor, D. lab lab, and Pachyrhizus sp. Isolated or in mixture, in different preparation method, on the germinability and development of B. pilosa, E. heterophylla and D. insularis, this stimulus os inhibition effect being according to the extract used and the method of preparation. Also, that the allelopathic effect happened by the action of several substances of different polarities. / As substâncias presentes no material vegetal podem atuar na supressão de plantas daninhas pela liberação de compostos alelopáticos. Objetivou-se avaliar o efeito alelopático de extratos de Dolichos lab lab, Pachyrhizus sp. e Sorghum bicolor, isolados e em mistura, submetidos a diferentes modos de preparo, nas espécies de plantas daninhas Bidens pilosa, Euphorbia heterophylla e Digitaria insularis. O experimento foi realizado em quatro etapas, sendo, elas, a coleta do material vegetal e o preparo dos extratos aquosos; influência dos extratos aquosos na germinação e desenvolvimento inicial de B. pilosa, E. heterophylla e D. insularis, em delineamento inteiramente casualizado e fatorial 7x4+T, com quatro repetições; efeito alelopático dos extratos de adubos verdes em pós-emergência nas plantas daninhas B. pilosa, E. heterophylla e D. insularis, em delineamento inteiramente casualizado, com seis tratamentos e seis repetições; germinação e desenvolvimento inicial de B. pilosa após a aplicação de diferentes frações dos extratos aquosos de D. lab lab, preparado com material vegetal seco e da mistura D. lab lab+Pachyrhizus sp.+S.bicolor, preparado com material vegetal liofilizado e submetido a banho-maria, em delineamento inteiramente casualizado, com 14 tratamentos e quatro repetições. Em pré-emergência, o extrato Pachyrhizus sp.+S. bicolor preparado com material vegetal liofilizado e submetido a banho-maria reduziu a porcentagem de germinação, o comprimento do hipocótilo e o comprimento da raiz primária em 87%, 30% e 61%, respectivamente. Para E. heterophylla, a mistura Pachyrhizus sp.+S. bicolor, preparado com material vegetal liofilizado, causou a redução em 23% da porcentagem de germinação. Para D. insularis, o extrato Pachyrhizus sp.+S. bicolor, preparado com material vegetal liofilizado e submetido a banho-maria, reduziu a porcentagem de germinação em 83%, e o comprimento da raiz primária em 52%. Em pós-emergência, o extrato de D. lab lab+Pachyrhizus sp., preparado com material vegetal liofilizado e submetido a banho-maria, reduziu em 21% a massa seca das raízes das plantas B. pilosa, e em 18% a massa seca das raízes de D. insularis, contudo, estimulou em 14% a mesma variável em E. heterophylla. O fracionamento do extrato de D. lab lab, preparado com material vegetal seco, não afetou a porcentagem de germinação e a biomassa de B. pilosa, mas interferiu no comprimento do hipocótilo e no comprimento da raiz primária. As frações do extrato D. lab lab+Pachyrhizus sp.+S. bicolor, preparado com material vegetal liofilizado e submetido a banho-maria, interferiu em todas as variáveis avaliadas. Conclui-se que existe efeito alelopático de extratos de S. bicolor, D. lab lab, e P. Pachyrhizus sp. isolados ou em mistura, em diferentes modos de preparo, sobre a germinação e o desenvolvimento de B. pilosa, E. heterophylla, e D. insularis, sendo este efeito de estímulo ou de inibição, de acordo com o extrato utilizado e o modo de preparo. Ainda, que o efeito alelopático ocorre pela ação de várias substâncias de diferentes polaridades.

Lab exercises are a pedagogically essential component of engineering and technology education. Distance education remote labs are being developed which enable students to access lab facilities via the Internet. Collaboration, students working in teams, enhances learning activity through the development of communication skills, sharing observations and problem solving. Web meeting communication tools are currently used in remote labs. The problem identified for investigation was that no standards of practice or paradigms exist to guide remote lab designers in the selection of collaboration tools that best support learning achievement. The goal of this work was to add to the body of knowledge involving the selection and use of remote lab collaboration tools. Experimental research was conducted where the participants were randomly assigned to three communication treatments and learning achievement was measured via assessments at the completion of each of six remote lab based lessons. Quantitative instruments used for assessing learning achievement were implemented, along with a survey to correlate user preference with collaboration treatments. A total of 53 undergraduate technology students worked in two-person teams, where each team was assigned one of the treatments, namely (a) text messaging chat, (b) voice chat, or (c) webcam video with voice chat. Each had little experience with the subject matter involving automation, but possessed the necessary technical background. Analysis of the assessment score data included mean and standard deviation, confirmation of the homogeneity of variance, a one-way ANOVA test and post hoc comparisons. The quantitative and qualitative data indicated that text messaging chat negatively impacted learning achievement and that text messaging chat was not preferred. The data also suggested that the subjects were equally divided on preference to voice chat verses webcam video with voice chat. To the end of designing collaborative communication tools for remote labs involving automation equipment, the results of this work points to making voice chat the default method of communication; but the webcam video with voice chat option should be included. Standards are only beginning to be developed for the design of remote lab systems. Research, design and innovation involving collaboration and presence should be included.