Orientador: Francisco Haiter Neto / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-09T19:20:36Z (GMT). No. of bitstreams: 1 Pontual_AndreadosAnjos_D.pdf: 4409755 bytes, checksum: 49aa0ed4836e883074310730a70bc34b (MD5) Previous issue date: 2007 / Resumo: O objetivo, nesse trabalho, foi comparar, de forma objetiva e subjetiva, dois sistemas digitais de placa de armazenamento de fósforo (Digora Optime® e DenOptix®), com o sistema CDR Wireless®, utilizando o filme radiográfico como método radiográfico de referência. Para a análise objetiva, foram obtidas imagens radiográficas de uma escala de densidade de Alumínio utilizando os três sistemas digitais. Posteriormente, obtiveram-se os valores do pixel por meio de ferramenta apropriada do software EMAGO®/Advanced. A comparação dos valores médios do pixel dos sistemas digitais foi realizada pelos testes de Kruskal-Wallis e de comparações múltiplas de Dunn (p<0,01). Para a avaliação subjetiva, foram obtidas imagens radiográficas de 20 phantoms constituídos de dentes posteriores, as quais foram avaliadas quanto à presença de cáries por seis radiologistas. Posteriormente, os dentes foram seccionados e analisados microscopicamente para obtenção do padrão ouro. Foram realizados a análise de variância e o teste-t (p<0,05) com o objetivo de verificar a ocorrência de diferença estatisticamente significativa entre os valores de sensibilidade, especificidade, acurácia (área sob a curva ROC), valores preditivos negativos e positivos das modalidades de imagem. Os resultados mostraram diferenças significativas nos valores médios do pixel para os três sistemas digitais, sendo que o Digora Optime® (194,46) apresentou o maior valor, seguido pelo DenOptix® (168,34) e pelo CDR Wireless® (109,44). Os sistemas CDR Wireless® e Digora Optime® obtiveram maiores valores de sensibilidade em relação às demais modalidades de imagem, sendo estatisticamente significativa a diferença entre esses sistemas e o filme radiográfico convencional (p=0,032). O Digora Optime® revelou o menor valor de especificidade e acurácia, o qual foi significativamente inferior ao do filme convencional (p<0,013). O sistema digital CDR Wireless® demonstrou desempenho semelhante ao filme radiográfico Insight® na detecção de cáries proximais incipientes. Por conseguinte, no tocante à qualidade da imagem, o novo CDR Wireless® pode ser uma alternativa viável para a utilização na clínica como método auxiliar de diagnóstico / Abstract: The aim of this study was to compare, both objectively and subjectively, the radiographic image quality of two storage phosphor plate systems (Digora Optime® e DenOptix®) with the results of the new complementary metal oxide silicon system, the CDR Wireless®. For the objective analysis, radiographs of an aluminum step wedge were obtained using the tree digital systems. This analysis was carried out by pixel density measurements using the appropriate tool from the EMAGO®/Advanced software. The data of pixel measurements was analyzed statistically using Kruskal-Walils test and Dunn multiple comparisons test (p<0.01). For the subjective analysis, under in vitro and standardized conditions, twenty phantoms with posterior human teeth were radiographed using one conventional film (Insight® Kodak) and the tree digital systems. Six radiologists recorded small approximal caries lesions on a 5-point confidence scale. The presence of caries was validated histologically. Two-way analysis of variance and post hoc t-test tested differences in sensitivity, specificity, accuracy, and positive predictive and negative predictive values. Differences were considered statistically significant when p<0.05. The results showed significant differences in the pixel density values for the three digital systems, with the Digora Optime® presenting the greatest values (194.46), followed by the DenOptix® (168.34) and CDR Wireless® (109.44). The two-way analysis of variance and post hoc t-tests demonstrated that CDR Wireless® and Digora Optime® had higher sensitivity than almost all other image modalities, significantly higher than conventional film. Digora Optime® had the lowest specificity and accuracy of all systems. Statistically significant difference existed in specificity and accuracy between this system and the conventional film (p<0.05), among the others systems there were no significant differences (p>0.05). The results suggest that the performance of the new CDR Wireless® was comparable to those of the digital systems and that of the Insight® film. Therefore, regarding to image quality, the new CDR Wireless® system may be used as an alternative, in clinical activities, as a diagnostic complementary method / Doutorado / Radiologia Odontologica / Mestre em Radiologia Odontológica

Apresentaremos nesta tese três novos tipos de dosímetros de radiação, projetados para medir radiação X, na faixa de diagnóstico: o dosímetro de radiação fotoacústico pulsado, o dosímetro de radiação piroelétrico e o dosímetro de radiação piroelétrico pulsado. Estudamos também o dosimetro de radiação fotoacústico com o objetivo de compará-lo com os novos dosímetros desenvolvidos. Propomos uma metodologia para calibração de um dosímetro fotoacústico que prescinde da calibração de sua resposta em um campo conhecido de radiação ionizante. Apresentaremos um modelo teórico para explicar os resultados obtidos com o dosímetro de radiação piroelétrico pulsado. Os resultados encontrados mostram que os dosímetros desenvolvidos são do tipo calorimétrico, sendo a resposta deles linear com a taxa de fluência de energia da radiação X. / In this thesis we present three new types of radiation dosimeters, designed to measure X-rays in its diagnostic region: the pulsed photo acoustical radiation dosimeter, the pyroeletric radiation dosimeter and the pulsed pyroelectric radiation dosimeter. We also study the photo acoustical radiation dosimeter with the scope of to compare its characteristics with the characteristics of the new developed dosimeters. We propose a methodology for calibration of a photo acoustical dosimeter which doesn´t require the calibration of its response in a known field of ionizing radiation. We present a theoretical model to explain the results produced by the pulsed pyroelectric radiation dosimeter. The obtained results show that the developed dosimeters are of calorimetric type, being linear its response with the X-ray energy fluency rate.

Um contador a gás, com multifios, sensível à posição, para a detecção de raios X foi construído utilizando linhas de atraso integradas para leitura da posição. Seis linhas de atraso (50ns de atraso cada, frequência de corte de 40MHz) cobrem um comprimento sensível total de 150mm, possuindo uma razão do atraso total pelo tempo de subida dos sinais na linha adequadas para a detecção em posição raios X de 5,9keV do ANTIPOT. 55 Fe com alta resolução. Testes usando a forneceram uma não-linearidade linha de integral máxima menor que 0,1% e não-linearidade diferencial máxima de ±4,0%, com o detector utilizando a mistura 700torr. Testes similares foram feitos usando de Ar-CH IND 4 (90%-10%) a a linha de 8,04keV de um tubo de raios X de Cu. Uma resolução total de 330m, e as mesmas não-linearidades integral e diferencial foram obtidas. Com a finalidade de t.est.ar o comportamento do detector sob condições experimentais reais, duas diferentes amostras foram analisadas na região de espalhamento em baixo ângulo. As amostras analisadas foram o carvão vítreo e o dodecil sulfato de sódio (SLS). O feixe de raios X foi colimado por um conjunto de fendas, com 50,um cada uma delas e separadas de 98mm. A distância entre a amostra e o detector era de 404,5mm, fazendo com que a região sensível do detector cobrisse um ângulo de espalhamento de ±12 °. Foram obtidos um raio de giro de 22 Å para o carvão vítreo e um dos parâmetros da rede cristalina c de 39,1 Å para o SLS. Estes resultados estão de acordo com trabalhos anteriores obtidos com técnicas tradicionais de maior dispêndio de tempo que utilizam detectores de Nal(T1) e chapas fotográficas em uma câmara de Laue. / A multiware position sensitive gas counter for X-Ray detection was developed in our laboratory making use or commercial delay-lines for position sensing. Six delay-line chips (50ns delay each 40Mhz cut-off frequency) cover a total sensitive length of 190mm leading to a delay-risetime ratio that allows for a high-resolution position detection. Tests using the 5,9keV X-Ray line from a 55Fe source an integral linearity better than 0,1% and a maximum differential linearity or ±4,0% were obtained operating the detector with an Ar-CH 4 (90%-10%) gas mixture at 700torr. Similar tests were performed using the 8,04keV line from a Cu X-Ray tube. A total resolution or 330m, and the same integral and differential linearities were obtained. In order to check the detector performance under usual experimental conditions two different samples were analyzed in the low scattering-angle region. The samples analyzed were vitreous carbon and sodium dodecyl sulfate (SLS). The X-Rays were collimated by a set or slits each 50m wide separated by 98mm. The distance between the sample and the detector was 404,5mm, so that the detector covered a scattering angle of ±12°. A radius of gyration of 22Å for vitreous carbon and a crystallographic parameter of 39,1Å for SLS were obtained. These values are in good agreement with those obtained with the more time-consuming traditional techniques making use of a rotating NaI(T1) detector and photographic plates with a Laue camera.

O presente estudo destinou-se a realizar uma análise comparativa entre a osteoartrite de quadris e o posicionamento acetabular através de exames radiográficos e de tomografia computadorizada. Foram incluídos 13 pacientes portadores e oito não-portadores de osteoartrite primária do quadril, recrutados no Ambulatório do Instituto de Ortopedia e Traumatologia do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo. Os exames foram submetidos à medição das seguintes variáveis: ângulos acetabulares, ângulo centro-borda, sinal do entrecruzamento, largura e profundidade do acetábulo no RX; anteversão e ângulos setoriais acetabulares nos tomogramas. Não se verificou diferença estatisticamente significatova na anteversão acetabular entre ambos os grupos, ao passo que o ângulo acetabular setorial posterior mostrou média inferior no grupo afetado / The present study intends to develop a comparative analysis between primary hip osteoarthritis and acetabular positioning through x-ray exams and computed tomographic scans. 13 affected and 8 non-affected patients by degenerative hip disease with no underline causes are recruited within the ambulatory care service of the Institute of Orthopedics and Traumatology of the Hospital of Clinics, São Paulo University Medical School. Their radiographic exams are studied for extracting some parameters named as: acetabular angles, center edge angle, crossover sign, acetabular width and acetabular depth. Tomographic films give information to measure acetabular ante version and acetabular setorial angles. Statistically, there is no significant relationship concerning acetabular ante version within the two groups, although, the posterior acetabular setorial angle shows a lower median value in the osteoarthritic group

Orientador: Frab Norberto Boscolo / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-04T04:02:24Z (GMT). No. of bitstreams: 1 Manzi_FlavioRicardo_D.pdf: 8326674 bytes, checksum: 99330b2ff05f7ff15fe1b4a09ce74602 (MD5) Previous issue date: 2005 / Resumo: Os efeitos da radiação ionizante no desenvolvimento dentário têm demonstrado grande interesse, e avalia-Ios foi o objetivo deste trabalho. Para tanto, foram utilizadas 21 ratas, divididas em 7 grupos de forma aleatória. Por meio de esfregaço vaginal diário, foi determinado o ciclo estral das ratas para a avaliação do período fértil das mesmas e uma vez comprovado este período, as ratas foram isoladas em gaiolas individuais. Efeito da radiação ionizante no desenvolvimento dentário em ratos com um macho para o acasalamento, durante o período noturno. Ao amanhecer, foi determinado o 10 dia de gestação pela presença do plug vaginal e visualização de espermatozóides em outro esfregaço vaginal. A região abdominal das ratas dos grupos La1 e La4 foi irradiada aos 13 dias de gestação com dose de 1 Gy e 4Gy de raios X, respectivamente. Nesta fase, os 1°S molares dos embriões se encontravam no estágio de lâmina. Utilizando-se as mesmas doses, os grupos Br1 e Br4 foram irradiados aos 16 dias de gestação e os grupos Si1 e Si4 aos 19 dias, correspondendo assim, aos estágios de broto e sino. O grupo Co foi formado por animais não irradiados. Após 30 dias do nascimento, foram sacrificados 3 filhotes de cada ninhada para avaliação quantitativa e ualitativa dos molares por meio da microscopia eletrônica de varredura. Foram avaliados 36 1°S molares em cada grupo, sendo 18 superiores e 18 inferiores. Pela análise dos resultados dos a radiação X promove efeito deletério nas dimensões oclusais dos molares em desenvolvimento, em todos os estágios iniciais estudados (lâmina, broto e sino) na dose de 4 Gy, principalmente no estágio de sino, os quais apresentaram fusão de. cúspides, fraturas coronárias e canalículos dentinários levemente mais delgados e dispersos. Na dose de 1 Gy verificou-se alterações dimensionais apenas nos molares irradiados no estágio de sino (p<O,01) / Abstract: The effects of ionizing radiation on molar development in mice were examined in this study. Forty-two female rats were divided into 7 groups. Vaginal secretion was collected to determine the estrous cycle phases, to ascertain the reproductive status of the female period. When this period was confirmed, the female rats were isolated in individual cages with a male for coitus during the night. In the morning, the 1 st day of gestation was confirmed by presence of the vaginal plug and observation of sperms in another vaginal smear. The abdominal region of the rats of Groups La1 and La4 was irradiated on the 13th gestational day, with a 1 Gy and 4Gy dose of X-rays, respectively. In this phase, the 1 st molars of the embryos were in the dental lamina stage. Using the same doses, Groups Br1 and Br4 were irradiated on the 16th gestational day and Groups Si1 and Si4 on the 19th gestational day, corresponding to the dental bud and bell stage, respectively. The Group Co was formed by un-irradiated animais. Thirty (30) days after birth, 3 nestlings of each brood were sacrificed for quantitative and qualitative evaluation of the molars, through the scanning electronic microscopy. Thirty-six 1st molars were evaluated in each group, 18 top and 18 botiom. In these results, X-ray radiation had a deleterious effect on the occlusal dimensions of the molars in development at ali initial dental stages studied (Iamina, bud and bell) exposed to 4 Gy, mainly in the bell stage, which presented fusions of cusps, coronal fractures and slightly thinned and dispersed dentinal tubules. In molars exposed to 1 Gy, only dimensional alterations were observed in the dental bell stage (p <0.01) / Doutorado / Radiologia Odontologica / Doutor em Radiologia Odontológica

Stellar flares are a frequent occurrence on young low-mass stars around which many detected exoplanets orbit. Flares are energetic, impulsive events, and their impact on exoplanetary atmospheres needs to be taken into account when interpreting transit observations. We have developed a model to describe the upper atmosphere of extrasolar giant planets (EGPs) orbiting flaring stars. The model simulates thermal escape from the upper atmospheres of close-in EGPs. Ionisation by solar radiation and electron impact is included and photo-chemical and diffusive transport processes are simulated. This model is used to study the effect of stellar flares from the solar-like G star HD 209458 and the young K star HD 189733 on their respective planets, HD 209458b and HD 189733b. The Sun is used as a proxy for HD 209458, and is an element of Eridani, as a proxy for HD 189733. A hypothetical HD 209458b-like planet orbiting the very active M star AU Microscopii is also simulated. We find that the neutral upper atmosphere of EGPs is not significantly affected by typical flares on HD 209458 and HD 189733. Therefore, stellar flares alone would not cause large enough changes in planetary mass loss to explain the variations in HD 189733b transit depth seen in previous studies, although we show that it may be possible that an extreme stellar proton event could result in the required mass loss. Our simulations do however reveal an enhancement in electron number density in the ionosphere of these planets, the peak of which is located in the layer where stellar X-rays are absorbed. Electron densities are found to reach 2.2 to 3.5 times pre-flare levels and enhanced electron densities last from about 3 to 10 h after the onset of the flare, depending on the composition of the ionospheric layer. The strength of the flare and the width of its spectral energy distribution affect the range of altitudes in the ionosphere that see enhancements in ionisation. A large broadband continuum component in the XUV portion of the flaring spectrum in very young flare stars, such as AU Mic, results in a broad range of altitudes a ff ected in planets orbiting this star. Indeed, as well as the X-ray absorption layer, the layer in which EUV photons are absorbed is also strongly enhanced.

Abstract The purpose of this study was to describe the process of learning to perform plain x-ray examinations, and to interpret the learning culture during radiography students’ studies. The aim was to understand how the students learned. Learning was understood as being collaborative and was examined from the perspective of interpretive ethnography. The data were collected during 2004‒2007 from documents, interviews and by observing 17 radiography students as they studied the theory of plain x-ray examinations, performed lab exercises and completed their practical training. The data were analysed using the constant comparison method. A model of the process of learning to perform plain x-ray examinations was created from the results. Based on the results, different learning views prevailed in the contexts of learning how to perform plain x-ray examinations. These governed the formation of five different learning styles, where the link between theory and practice gained different meanings and the learning outcomes varied. In academic studies, learning took place through acquisition of basic professional knowledge. In lab exercises, the students learned by model-based experimentation. In practical training, learning took the form of progress towards expertise through collaboration, active solo work, and working in the background, following instructions. The styles and outcomes of learning were both supported and impeded by factors dependent on the learning contexts and the students. The process of learning to perform plain x-ray examinations was governed by a learning culture that required the ability to interpret and adapt to the learning contexts. Students needed to identify the learning views that prevailed in the learning contexts and adjust their learning style accordingly. It can be concluded that the learning culture provided a varying degree of support to the students' progress towards expertise as they learned to perform plain x-ray examinations. The study produced new information on the learning of health care students from the socio-cultural viewpoint. The results can be exploited when developing the curriculum and the collaboration between Universities of Applied Sciences and trainee job providers towards cooperative learning. Future studies should focus on the learning culture of professional radiographers to develop the education and the field. / Tiivistelmä Tämän tutkimuksen tarkoituksena oli kuvata natiivitutkimusten oppimista ja tulkita oppimisen oppimiskulttuuria röntgenhoitajaopiskelijoiden opinnoissa. Tutkimuksen tavoitteena oli ymmärtää opiskelijoiden oppimista. Oppiminen ymmärrettiin yhteisölliseksi ja sitä tutkittiin tulkinnallisen etnografian avulla. Tutkimusaineisto tuotettiin vuosien 2004–2007 aikana 17 röntgenhoitajaopiskelijan natiivitutkimusten teoriaopintojen, laboraatioharjoittelun ja harjoittelun havainnoinnista, kirjallisista dokumenteista ja haastatteluista. Aineisto analysoitiin jatkuvan vertailun menetelmällä. Tuloksista muodostettiin malli natiivitutkimusten oppimisesta. Tulosten mukaan natiivitutkimusten oppimisen oppimiskonteksteissa vallitsivat erilaiset oppimisnäkemykset. Nämä ohjasivat viiden erilaisen oppimistavan muodostumiseen, joissa teorian ja käytännön välinen yhteys sai erilaisia merkityksiä ja oppimisen tulokset vaihtelivat. Teoriaopinnoissa oppiminen tapahtui ammatillista tietoperustaa omaksuen. Laboraatioharjoittelussa oppiminen eteni oppimisena mallin mukaan kokeillen. Harjoittelussa oppiminen ilmeni oppimisena kohti asiantuntijuutta yhdessä toimien, aktiivisuutta osoittaen yksin toimien ja ohjeita noudattaen taustalla toimien. Oppimistapoja ja oppimisen lopputuloksia tukivat ja estivät oppimiskonteksteista ja opiskelijoista johtuvat tekijät. Natiivitutkimusten oppimista ohjasi oppimiskontekstin tulkintakykyä ja siihen mukautumista edellyttävä oppimiskulttuuri. Opiskelijan oli tunnistettava oppimiskontekstien oppimisnäkemykset ja muokattava oppiminen niiden mukaiseksi. Tulosten mukaan johtopäätöksenä voidaan todeta, että oppimiskulttuuri tuki vaihtelevasti opiskelijan asiantuntijuuteen kasvua natiivitutkimuksia opiskeltaessa. Tutkimus tuotti uutta tietoa terveysalan opinnoissa oppimisesta sosiokulttuurisesta näkökulmasta. Tuloksia voidaan hyödyntää opetussuunnitelman sekä ammattikorkeakoulun ja harjoittelupaikkojen välisen yhteistyön kehittämisessä kohti yhteistoiminnallista oppimista. Jatkossa on syytä tutkia työssä olevien röntgenhoitajien oppimiskulttuuria koulutuksen ja alan kehittämiseksi.

Les péridotites, roches du manteau terrestre, sont instables en présence d'eau et peuvent se transformer en un minéral hydraté la serpentine, qui a la capacité remarquable de générer de l'hydrogène H2; cette réaction s'appelle la serpentinisation. Au niveau des dorsales médio-océaniques, la circulation d'eau dans ces roches conduit à la formation de larges systèmes hydrothermaux. Ils montrent différentes conditions de température et de pH des fluides, bien qu'ils conduisent tous à la formation abiotique d'H2, de méthane CH4 et possiblement d'autres hydrocarbures légers.Cette thèse est dédiée à l'étude du rôle de la composition chimique du fluide hydrothermal sur la cinétique et les mécanismes de serpentinisation des roches ultrabasiques à différentes conditions de P-T. L'interaction entre l'olivine et/ou l'orthopyroxène a été analysée avec une solution aqueuse simulant une eau de mer enrichie en aluminium et/ou en ions bicarbonates, à différents pH. Une première série d'expériences a été réalisée à 200, 340 °C et 200 MPa en lp-DAC à l'ESRF en France. Elle a permis de quantifier les paramètres cinétiques de réaction, de déterminer un effet opposé de l'aluminium sur la cinétique de ces deux minéraux et l'accélération de la réaction en conditions alcalins. Autres expériences ont été réalisée à Pamb et 80 °C en flacons de verre. Elles ont conduit, pour la première fois, à la formation de serpentine ainsi qu'à la formation d'H2 et de CH4. Ces résultats montrent qu'une chimie plus complexe du fluide hydrothermal peut avoir un impact majeur sur la cinétique de la serpentinisation pour l'accélérer et la rendre plus accessible à une échelle de temps industrielle / Peridotites, Earth's mantle rocks, are unstable in the presence of water and can be transformed into a hydrated mineral, serpentine, which has the remarkable ability to generate hydrogen H2; this reaction is called serpentinization. At the mid-ocean ridges, the circulation of water in these rocks leads to the formation of large hydrothermal systems. They show great variability of temperature and fluids’pH conditions, although they all lead to the abiotic formation of H2, methane CH4 and eventually other light hydrocarbons. This PhD thesis is dedicated to the study of the chemical composition role of the hydrothermal fluid on the kinetics and mechanisms of serpentinization of ultramafic rocks to different conditions of P-T. The interaction between olivine and/or orthopyroxene was analyzed with an aqueous solution to simulate sea water which is rich in aluminum and/or bicarbonate ions, with different pH values. A first series of experiments was carried out at 200, 340 °C and 200 MPa in lp-DAC at the ESRF in France. It was used to quantify the kinetic parameters of the reaction, to determine an opposite effect of aluminum on the kinetics these two minerals and the acceleration of the reaction under alkaline conditions. Other experiments were performed in glass bottles at Pamb and 80 °C. They led, for the first time, to the formation of serpentine, as well as to the formation of H2 and CH4. These results show that the slightly more complex chemistry of the hydrothermal fluid can have a major impact on the kinetics of serpentinization to speed and make it more accessible to industrial time scale

Le Douglas sera la première essence résineuse en France dans les 10 ans à venir, avec des volumes commercialisables de l’ordre de 3 millions de m3/an. Sa valorisation par déroulage se heurte à deux caractéristiques défavorables de son duramen (une humidité à l’état vert proche du point de saturation des fibres (entre 30 et 40%) et une très mauvaise imprégnabilité à l’eau. Ceci rend ce bois très difficile et très long à chauffer par bouillottage avant déroulage. La matière ligneuse étant un bon isolant thermique, l’eau libre constitue généralement le milieu chauffant privilégié dans l’opération d’étuvage préalable au déroulage. Le temps de chauffe dans le cas du Douglas est doublé voire triplé par rapport à d’autres essences plus humides. Cela se traduit par un gaspillage énergétique et une immobilisation de stocks accrue. En vue d’améliorer la cinétique d’imprégnabilité de bois rond de Douglas, nous avons testés un certain nombre de modalités d’imprégnation à deux échelles différentes. À l’échelle de paillasse, des barreaux de 20 mm (R) x 20 mm (T) x 120 mm (L) prélevés dans le duramen, ont subis différents essais de trempage en faisant varier la température de l’eau, la durée du trempage, le type de refroidissement. Certaines modalités ont été répétés en plaçant le bain sous ultrason (fréquence 20 kHz, puissance 400 W) et pour d’autres en ajoutant un tensio-actif dans l’eau ou procéder à un séchage (thermique, naturel, vide) préalable des éprouvettes. Après chaque essai, la reprise d’eau a été quantifiée par double pesée. Nous avons montré un effet de bord répétable sur toutes les modalités mais aucune de celles-ci ne permet une amélioration significative de la reprise en eau du duramen sauf pour le cas du séchage préalable qui a profondément amélioré l’imprégnabilité. La transposition des traitements à l’échelle industrielle sur des billons de 50 cm de longueur et 20 cm de diamètre a montré l’efficacité du séchage préalable sur la capacité du bois d’être pénétré par l’eau, mais insuffisante pour améliorer significativement les conditions de déroulage. Le suivi de l’imprégnabilité par scanner à rayons X a confirmé la persistance de l’hétérogénéité de la répartition d’humidité sur toutes les modalités d’expériences réalisées. Les observations par microscopie confocale à balayage laser (CLSM) ont montré que le processus de séchage à 103°C, a généré des micro-fissures dans les parois cellulaires des ponctuations. Les essais de déroulage réalisés sur les billons issus des différentes modalités étudiées n’ont montré aucune différence de comportement aussi bien en termes d’efforts de coupe qu’en qualité des placages obtenus / In the ten next years, Douglas-fir will be the main softwood resource harvested in France. It its valorization by peeling comes up against two of its particularities that complicate boiling efficiency: (i) the heartwood has a MC near FSP (30 to 40%) i.e. there is near no free water into tracheid (ii) it is impossible to impregnate this heartwood at atmospheric pressure with water. As a result, wood material being a very efficient insulator material, boiling of Douglas-fir prior to peeling for veneer production will take a very long time, free water being the main medium allowing heat transfer into green wood. Wood is a good thermal insulator, free water is generally preferred in the heating operation steaming prior peeling. Heating time in the case of Douglas is doubled or tripled compared to others species. This results in wasted energy and increased immobilization stocks. In order to improve the kinetics of impregnability of Douglas heart wood, we tested a number of methods of impregnating at two different scales. At the bench scale, samples with 20 mm (R) x 20 mm (t) x 120 mm (L) taken from the heartwood, have suffered from various tests by varying the soaking water temperature, duration soaking, the type of cooling. Some terms were repeated by placing the bath in ultrasound (frequency 20 kHz, power 400 W) and others by adding a surfactant in water or to drying samples, (thermal, natural, vacuum) prior impregnation . After each test, the water uptake was quantified by double weighing. We showed a repeatable board effect across all categories but none of them allows a significant improvement in the water uptake heartwood except drying that profoundly improved the moisture content of samples. The transposition to the industrial scale processing on ridges (50 cm long and 20 cm in diameter) showed the effectiveness of prior drying on the ability of wood to be penetrated by the water, but insufficient to significantly improve the peeling conditions. X-ray scanner observations confirm the persistence of the heterogeneity of the moisture distribution across all categories of experiments. The confocal laser scanning microscopy (CLSM) showed that the drying process at 103 ° C, generated microcracks in the cell walls of the pits. The tests performed on the peeling logs from different modalities studied showed no difference in behavior both in terms of cutting forces and quality veneers obtained

Este trabalho narra a aplicação de uma proposta que aborda um tema de Física Moderna e Contemporânea na formação de professores dos anos iniciais do Ensino Fundamental. O tópico “matéria e radiação” foi escolhido para ser um tema estruturante, inspirado na noção de tema gerador de Paulo Freire, com o propósito de aprofundar questões da vida quotidiana, da ciência e das novas tecnologias; e também aspectos relacionados com cuidados com a saúde, visando alcançar uma aprendizagem crítica. Construímos uma sequência didática contemplando a abordagem temática freireana passando pelos três Momentos Pedagógicos, a saber: Problematização Inicial, Organização do Conhecimento e Aplicação do Conhecimento. Como material de apoio para o desenvolvimento da proposta foi elaborado um artigo sobre o tema raios X e ondas que foi utilizado de forma articulada a outras atividades descritas ao longo da dissertação. As distintas estratégias e os materiais compõem o produto educacional no formato de texto de apoio.Os resultados indicam que a sequência didática apresenta potencial para promover uma aprendizagem crítica e emancipatória, almejando a compreensão e futura transformação da realidade vivencial dos estudantes, contribuindo não apenas para a melhoria na qualidade da Educação Básica, na perspectiva de que os futuros professores façam a transposição de elementos do tema trabalhado em suas salas de aula, mas também visando uma sociedade mais justa e humanizada. / This work describes the application of a proposal to approach a theme of Modern and Contemporary Physics at the Normal School for teachers of the early years at Elementary School. The topic "matter and radiation" was chosen to be a structuring theme, inspired by the notion of the generating theme by Paulo Freire, in order to deepen the issues of everyday life, science and new technologies, as well as aspects related to health care, aiming at critical learning. We constructed a didactic sequence contemplating the Freirean thematic approach passing through the three Pedagogical Moments, namely: Problem-posing, Knowledge organization and Knowledge application. An article on X-rays and waves was prepared and used as supporting material together with other activities. All strategies and materials used throughout constitute the Educational product, presented here as Supporting text. The presented didactic sequence was shown to be powerful at promoting a critical and emancipatory learning, achieving an understanding and consequent transformation of the students’ life experience and reality. It is desired that the future teachers can adapt the elements of the topic studied to their classes, contributing to the improvement in the quality of Elementary Education and to a fair and humanized society.