Conselho Nacional de Desenvolvimento Científico e Tecnológico / This work investigates the influence of operation point (Δi @ fs) in the final volume of PFC boost converter. The boost inductor, EMI filter and thermal heatsink are the elements which main influences in the converter volume. These elements are strongly influenced by the chosen operation point, showing a direct relationship among them. With the increase of switch frequency and of the input current ripple occurs reduction of the boost inductor volume. On the other hand, it increases the switching losses in semiconductors, and influence on the EMI filter volume. It should be highlight that the optimum designs of individual devices or parameters of a system could not take the optimization of the overall system. In this form it is strongly recommended that the engineers and designers take into account the overall system, as well available technologies, standard and recommendation, and finally market commitments. The methodology presented realize the converter design in a integrate form, selecting the operation point that the converter finds the minimal total volume, starting from input variable output power, input and output voltage. The design takes into account different semiconductors technologies, different input filter topologies, different heart sinks profile, different magnetic cores technologies further of international standards that the converter must be adapt. Based on an integrate design of converter parameters is possible optimize the design finding the operation point for the minimal volume. / Esse trabalho investiga o impacto do ponto de operação (Δi @ fs) no volume final do conversor boost operando como pré regulador com correção do fator de potência (PFC). Os elementos de maior influência no volume do conversor são o indutor boost, o filtro de entrada e os dissipadores térmicos. O volume destes elementos é diretamente influenciado pelo ponto de operação, mostrando uma relação direta entre eles. Com o aumento da freqüência de comutação e da ondulação da corrente de entrada ocorre a diminuição do indutor boost, porém, aumentam as perdas nas comutações dos semicondutores e aumenta o volume do filtro de entrada. Com a diminuição da freqüência e da ondulação da corrente ocorre o inverso, sabendo disto, fica claro que projetar individualmente cada um destes três elementos pode resultar em um bom projeto individual, contudo penaliza os outros parâmetros. Assim, a metodologia apresentada realiza o projeto do conversor de forma integrada, escolhendo o ponto de operação em que o conversor encontre o volume final mínimo, partindo de algumas variáveis de entrada, como potência de saída e tensões de entrada e saída. O projeto leva em consideração diferentes tecnologias de semicondutores, topologias de filtros de entrada, perfis de dissipadores térmicos, tecnologias de núcleos magnéticos além das normas internacionais a que o conversor deve se adequar. Baseado no projeto integrado dos parâmetros do conversor é possível otimizar o projeto encontrando o ponto de operação para o volume total mínimo do conversor.

Les systèmes microélectromécaniques (MEMS) sont des dispositifs de taille micrométrique capables de transformer un signal mécanique en un signal électrique et vice-versa. Ils sont aujourd'hui largement répandus dans notre vie quotidienne pour la détection, la transformation de l'énergie et l'actionnement de dispositifs grâce à leur faible dissipation énergétique, leur réponse ultra-rapide et leur grande sensibilité. Même si depuis plusieurs décennies, les progrès technologiques ont entraîné la miniaturisation des ces dispositifs, il reste nombreux challenges à surmonter dont l'un des plus importantes est l'intégration à l'échelle nanométrique d'actionneurs à base des matériaux dit " intelligents " (à ces dimensions, les matériaux habituellement utilisés perdent leurs propriétés d'actionnement). Dans ce contexte, ce travail de thèse avait pour objectif d'explorer l'utilisation des matériaux moléculaires à transition de spin pour le développement d'actionneurs électromécaniques. Dans ce but, nous avons conçu des microleviers en silicium que nous avons recouvert par différentes molécules à transition de spin soit par sublimation, soit par " spray-coating ". Les MEMS ont été caractérisés à température et pression variables en modes dynamique et statique à l'aide d'un unique dispositif expérimental. Les résultats obtenus démontrent que les molécules à transition de spin peuvent être intégrées, à l'aide de différents procédés de fabrication, dans des dispositifs MEMS et qu'il est possible de réaliser l'actionnement à l'aide d'une source d'énergie thermique (chauffage et refroidissement) et/ou lumineuse. Simultanément, cette étude a également permis d'évaluer les propriétés mécaniques des matériaux à transition de spin (module de Young, coefficient de Poisson) qui restent mal connues. / Microelectromechanical systems (MEMS) are micrometric devices able to transform a mechanical signal into an electrical one and vice-versa. In the past years they have been successfully employed in different fields of our everyday life for sensing, transducing different forms of energy and for actuating purposes thanks to their low energy dissipation, fast response and high sensibility. Even if recent technological progress has allowed a considerable miniaturization of these devices, several challenges remain. In particular the integration of smart actuating materials at the nanometric scale remains arduous because in most cases they lose their actuating properties at reduced sizes. In this context, this thesis work aimed for exploring the possibility of using molecular spin crossover materials for the development of electromechanical actuators. To this aim we have conceived silicon microcantilevers, which have been coated by various spin crossover molecules using either thermal evaporation or spray-coating methods. The MEMS have been characterized at variable temperature and pressure both in dynamical and static modes using a single experimental setup. The results prove that spin crossover molecules can be successfully integrated into silicon MEMS devices using different fabrication processes and their actuation can be achieved using either a thermal energy source or light irradiation. In parallel, this work has allowed us to extract relevant mechanical properties of spin crossover materials (Young's modulus, Poisson's ratio), which have been largely unknown previously.

CoordenaÃÃo de AperfeÃoamento de Pessoal de NÃvel Superior / Estudos mostram que o desempenho do aluno em MatemÃtica nÃo à satisfatÃrio, pois apenas uma pequena parcela desses alunos tem os conhecimentos necessÃrios para prosseguir nos estudos. O presente trabalho visa criar ferramentas que possam auxiliar e melhorar as prÃticas em sala de aula, mais precisamente nos estudos de Geometria. Apresentaremos o Teorema de Pick, que visa calcular a Ãrea de um polÃgono simples usando contagem, analisando os pontos do bordo e do interior da figura em uma rede fixada, tornando-se uma ferramenta de uso simples e poderosa para a compreensÃo do estudo de Ãreas. Logo em seguida, mostraremos o Teorema de Reeve que, de modo anÃlogo a Pick, calcula o volume de um poliedro convexo contando os seus pontos de rede, trabalhando em uma rede secundÃria de pontos Z3n, realizando um elo entre Geometria e contagem. / Studies show that the performance of students in Mathematics is not satisfactory, since only a small portion of these students has the knowledge needed to pursue studies. The present work aims to create tools that can assist and improve classroom practices, more precisely in the studies of Geometry. We will present by counting Pick's Theorem, which calculates the area of a simple polygon by counting the points of the boundary and of the interior of the figure on a fixed lattice, making it a powerful tool of simple use for the understanding of the study of areas. Then we will present Reeve's Theorem that, similarly to Pick's, calculates the volume of a convex polyhedron by counting their lattice points, working on a secondary lattice of points Z3n, making a link between Geometry and counting.

Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2017-02-16T13:44:43Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertação BCTG_Digital.pdf: 7436148 bytes, checksum: 8202bd7e2553a94e29e709b92f260072 (MD5) / Made available in DSpace on 2017-02-16T13:44:43Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Dissertação BCTG_Digital.pdf: 7436148 bytes, checksum: 8202bd7e2553a94e29e709b92f260072 (MD5) Previous issue date: 2016-06-29 / FACEPE / Material particulado em suspensão (séston) em ecossistemas aquáticos contém dois compartimentos: organismos (plâncton) e partículas. Conhecimento sobre a contribuição das partículas para o séston é essencial para a compreensão da dinâmica de fluxos tróficos em ecossistemas marinhos. Este estudo tem como objetivo medir a biomassa sestônica úmida total e avaliar as contribuições relativas do mesozooplâncton e das partículas em suspensão em amostras de plâncton. As amostras foram obtidas no estuário do Rio Formoso e na Baía de Tamandaré (Pernambuco, Brasil). Arrastos subsuperficiais horizontais foram realizados durante dois anos (junho / 2013 a maio / 2015) em intervalos bimestrais com redes de plâncton (malhas: 200 e 300 µm) durante as estações seca e chuvosa. Um total de 155 amostras foram analisadas para estimar a biomassa sestônica úmida total e posterior identificação e estimativa de densidade e volume do zooplâncton e das partículas usando o equipamento ZooScan. Foram detectados, identificados, quantificados e medidos 26 grupos taxonômicos do zooplâncton. Dentre estes os grupos mais abundantes foram Copepoda (Calanoida e Cyclopoida), zoeas de Brachyura, outros decápodes, apendiculárias e náuplios de crustáceos. Foram detectadas 15 categorias de partículas, entre elas, as partículas opacas, transparentes e escuras, fibras vegetais, e exúvias de copépodos foram as mais abundantes. O ambiente estuarino apresentou os maiores valores de biomassa sestônica úmida, densidade e volume, e, também apresentou as maiores concentrações de partículas e contribuições relativas em termos de volume (72% e 59% do volume, para as malhas de 200 e 300 micrômetros, respectivamente). No entanto, o ambiente marinho também mostrou concentrações e volumes de partículas muito elevadas (32% e 44% do volume, para as malhas de 200 e 300 micrômetros, respectivamente). Zooplâncton e partículas mostraram maiores densidades durante o período seco. A comparação entre os volumes totais obtidos com medidas semi-automáticas de imagens digitalizadas e a biomassa sestônica úmida revelou uma relação linear significativa (R² = 0,73; p <0,0001). Este estudo confirma a importância de mesopartículas (maiores do que 200 micrômetros) na estrutura do séston em áreas costeiras tropicais. / Suspended particulate matter (seston) in aquatic ecosystems contains two compartments: organisms (plankton) and particles. Knowledge on the contribution of particles to the seston is essential in understanding the dynamics of trophic energy flows in marine ecosystems. This study aims to measure the total wet seston biomass (wet weight) and to assess the relative contributions of zooplankton and particles to plankton net samples. The samples were obtained in the Rio Formoso estuary and in Tamandaré Bay (Pernambuco State, Brazil). Subsurface horizontal tows were performed during two years (June / 2013 to May / 2015) at bimonthly intervals with plankton nets (meshes: 200 and 300 µm) during dry and rainy seasons. 155 samples were analyzed to estimate the total wet seston biomass and subsequent identification and estimation of density and zooplankton volume and particle volume using a ZooScan equipment. 26 taxonomic groups of zooplankton were detected, identified, quantified, and measured. The most abundant were Copepoda (Calanoida and Cyclopoida), brachyuran zoea, other decapods, appendicularians and crustacean nauplius. 15 categories of particles were detected, among these, opaque, transparent and dark particles, plant fibers, and copepod exuviae were the most abundant. The estuarine environment showed the highest values of wet seston biomass, density and volume and also had the highest particle concentrations and relative volume contributions, (72% and 59% volume, for 200 and 300 µm mesh nets, respectively). However, the marine environment also showed very high concentrations and volumes of particles (32% and 44% volume, for 200 and 300 µm mesh nets, respectively). Zooplankton and particles showed highest densities during the dry period. The comparison between total volumes obtained with semi-automatic measurements of scanned images with wet seston biomass revealed a significant linear relationship (R² = 0.73; p < 0.0001). This study underlines the importance of particles (greater than 200 micrometers) in the structure of the seston in tropical coastal areas.

Orientador: Ivo Milton Raimundo Junior / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-09T15:37:40Z (GMT). No. of bitstreams: 1 Panontin_Flavia_M.pdf: 2358588 bytes, checksum: 5556de1b55db28438143379cca4b4281 (MD5) Previous issue date: 2007 / Resumo: Um método para a determinação do volume de poros de sílicas, utilizadas como suportes de fases estacionárias para CLAE (Cromatografia Líquida de Alta Eficiência), foi desenvolvido utilizando a espectroscopia na região do infravermelho próximo (NIR). Foram preparadas amostras pela adição de sílica em soluções de diferentes concentrações de compostos de recobrimento, como polímeros, hidrocarbonetos lineares e ramificados, nujol, glicerol, entre outros, em meio de diclorometano ou metanol. Foram registrados espectros de reflectância difusa na região de 1100 a 2300 nm. Os espectros obtidos foram submetidos à primeira derivada e as intensidades em 1688 nm (primeiro sobretom de ligações C-H) foram empregadas para a construção de uma curva em função da carga inicial (massa recobrimento/massa total) da amostra. Foram obtidos dois ramos lineares, o primeiro (praticamente paralelo à abscissa) indica que a imobilização do reagente no interior dos poros da sílica, e o segundo mostra um aumento crescente dos valores de primeira derivada, indicando o recobrimento de sua superfície externa. A intersecção destas duas retas fornece o valor de carga equivalente ao total preenchimento dos poros. Os resultados obtidos de volume de poro são concordantes com os valores fornecidos pelo método padrão (BJH), apresentando desvios padrão menores que 10%. O método proposto apresenta boa reprodutibilidade, com desvios menores que 1,0%, sendo rápido, simples e não destrutivo o que mostra uma grande vantagem frente ao método BJH, que faz uso de equipamentos caros e procedimentos lentos / Abstract: A method for the determination of pore volume of silicas, used as stationary phases for HPLC (High Performance Liquid Chromatography) was developed using near infrared spectroscopy (NIR). Samples were prepared by the addition of silica in covering compounds solutions of different concentrations, as linear and ramified polymers, hydrocarbons, nujol, glycerol, and among others, using dichloromethane or methanol as solvents. Diffuse reflectance spectra were registered in the 1100 to 2300 nm region. Spectra were submitted to a first derivative pre-treatment and the intensities at 1688 nm (first overtone of C-H bonds) were used for the construction of a curve as a function of the initial load (covering/total mass) of the sample. Two linear branches were obtained; the first one (practically parallel to the abscissa) indicates the immobilization of the reagent in the interior silica pores, and the second one shows increasing values of first derivative, indicating the covering of its external surface. The intersession of these two straight lines supplies the load value that is equivalent to the total fulfilling of the pores. The results obtained for of pore volume are in agreement with those supplied by the standard method (BJH), presenting deviation lower than 10 %. The proposed method presents good reproducibility with standard deviation lower than 1.0 %, being fast, simple and no destructive technique, that is a great advantage over the BJH method, which uses expensive equipment and slow procedures / Mestrado / Quimica Analitica / Mestre em Química

É sabido das vantagens da utilização do sêmen criopreservado na reprodução eqüina, mas também é de conhecimento que o entendimento desta biotecnologia ainda é carente. Não se tem concordância quanto à dose e concentração espermáticas ideais para se obter bons resultados de fertilidade. Assim, este experimento teve o intuito de avaliar o movimento espermático pelo sistema computadorizado (CASA), a morfologia espermática, além da integridade das membranas plasmática e acrossomal e o potencial de membrana mitocondrial, com sondas fluorescentes, em espermatozóides eqüinos criopreservados nas concentrações de 100, 200, e 400x106sptz/mL e nos volumes 0,50 e 0,25mL. Foram utilizados quatro garanhões sendo oito colheitas de cada animal, através de vagina artificial. Após a colheita, o sêmen foi diluído em extensor à base de leite desnatado (1:1), centrifugado 500xg por 10 minutos, o sobrenadante retirado, e o pellet ressuspendido em diluidor Botu-Crio® nas concentrações de 100 (C100), 200 (C200) e 400x106sptz./mL (C400). Em seguida, envasado em palhetas de 0,50 e 0,25mL. Para criopreservação do sêmen utilizou–se aparelho automatizado (TK3000®), com curvas de resfriamento -0,25ºC/min e de congelação -15ºC/min até -80ºC e -10ºC/min, até atingir -120ºC, quando as palhetas foram mergulhadas em N2 líquido (-196 ºC) e armazenadas em botijões criogênicos. Foram descongeladas duas palhetas de cada tratamento em banho-maria (37ºC por 30s). Uma amostra do sêmen foi diluída em formol salino para avaliação da morfologia espermática e outra em TALP sperm à concentração de 25x106sptz/mL. Logo após, uma amostra desta solução foi submetida à análise computadorizada do movimento espermático. As características analisadas foram: motilidade total (MTCA, %), motilidade progressiva (MPRO, %), velocidade progressiva (VSL, &#956;m/s), velocidade curvilinear (VCL, &#956;m/s), deslocamento lateral de cabeça (ALH, &#956;m) e freqüência de batimento flagelar (BCF, Hz). Em seguida, uma outra amostra foi avaliada quanto à integridade das membranas plasmática e acrossomal e o potencial de membrana mitocondrial, utilizando PI, JC-1 e FITC-PSA, por microscopia de epifluorescência. Foram determinados os percentuais de espermatozóides com membranas plasmáticas intactas (MPI), acrossomais intactas (MAI) e mitocondriais de alto potencial (APM) e membranas plasmática e acrossomal intactas e com alto potencial de membrana mitocondrial (PIAIA). Foi utilizada análise de variância (ANOVA) (p<0,05) e teste de médias SNK (p<0,05), pelo método SAS®. Não houve efeito da interação entre volume da palheta e concentração espermática para as características estudadas. As características do movimento espermático foram influenciadas pela concentração, de forma que C100>C200>C400, exceto em LIN e STR. O volume somente alterou os valores de STR e VCL. Quanto à integridade e funcionalidade das membranas, não houve efeito do volume, enquanto que as concentrações alteraram somente MPI (C100>C200>C400) e APM (C100=C200>C400). Na morfologia espermática, a concentração somente afetou a percentagem de cauda dobra ou enrolada (C100>C200=C400) e o volume de armazenamento somente as quantidades de cabeça isolada normal e patológica (0,50>0,25mL). Assim, o melhor método de congelação, neste experimento, foi em C100, seguido por C200 e por último C400, em ambos os volumes. Portanto, a qualidade seminal pós-descongelação está diretamente relacionada com a quantidade de agentes crioprotetores por unidade celular, independente do volume da palheta. / It has been known the advantages of cryopreserved semen utilization in equine reproduction, but the understanding of this biotechnology is uncertain yet. There was not agreement of the ideal spermatic dose and concentration to optimize fertility results. Thus this experiment had the objective to evaluate spermatic motion by computed analysis (CASA), spermatic morphology and the plasmatic and acrosomal membrane integrity and mitochondrial membrane potential with fluorescence probes of equine cryopreserved spermatozoa on 100, 200 and 400x106sptz/mL concentrations and 0.50 and 0.25mL volumes. Eight ejaculates from four stallions were collected in artificial vagina. The semen was diluted in skim-milk extender (1:1), centrifuged at 500xg for ten minutes, the supernatant was removed and the freezing extender Botu-Crio® was added in the pellet to a final concentrations of 100 (C100), 200 (C200) and 400x106sptz/mL (C400); after that, it was packed in 0.50 and 0.25mL straws. The cryopreservation of semen utilized an automatic system (TK3000®), with cooling slope -0.25°C/minute and freezing slope of -15°C/minute, until -80°C, and -10°C/minute, until -120°C, when the straws were plunged into liquid nitrogen (-196°C), and stored in cryogenics tank. They were thawed for 30s in a 37°C waterbath. A sample of semen was diluted in saline formol to morphology spermatic evaluation and another diluted in TALP sperm at 25x106sptz/mL. After, a sample was submitted to CASA evaluation. The analyzed characteristics were: total motility (TMCA, %), progressive motility (PROM, %), progressive velocity (VSL, µm/s), track speed (VCL, µm/s), beat cross frequency (BCF, Hz) and lateral amplitude of head (ALH, µm). Afterward, another sample was evaluated about plasmatic and acrosomal membranes integrity and mitochondrial potential membrane, using PI, JC-1 and FITC-PSA by epifluorescence microscope. It was determined the spermatozoa percentage with intact plasmatic membranes (IPM), intact acrosomal membranes (IAM), and high potential mitochondrial membrane (HPM) and intact plasmatic and acrosomal membranes and with high potential mitochondrial membrane (IPIAH). For statistical analysis were utilized variance analysis (ANOVA - p<0.05) and SNK test (p<0.05) with standard deviation, by SAS® system. There was not effect of straw volume and spermatic concentration interaction in the studied characteristics. The spermatic motion characteristics were influenced by concentration (C100>C200>C400), except LIN and STR. The volume changed the values of percentage of STR e VCL. In membrane integrity and functionality there was no volume effect, however the concentrations changed only IPM C100>C200>C400) e HPM (C100=C200>C400). In spermatic morphology, the concentration affected the percent of folded or coiled tail (C100>C200=C400) and the volume only affected the loose normal and abnormal head (0.50>0.25mL). Thus, the better freezing method, in this experiment, was C100, followed by C200, and C400, in both straws volumes. The seminal quality post-thawed is related with the cryoprotector quantity by cell, free of the straw volume.

As the volumes are entering the world of computer graphics the pure volume visualisation becomes a more important tool in for example research and medical applications. But the advance in haptics --- force feedback from the computer --- is behind. In volume haptics no equal to the proxy method so popular in surface haptics has yet emerged. Some implementations of volume haptics even use surfaces as intermediate representations so that surface haptics can be used. The intention of this work was to create natural feeling haptic feedback from volumetric density data using pure volume haptics. The haptic algorithm would be implemented in Reachin API for the Reachin Desktop Display, together with other parts to build up a usable volume visualisation environment. To achieve the feeling of stiffness and friction dependent on tissue type, a proxy based method was developed. In the volume the proxy is constrained by virtual surfaces defined by the local gradient. This algorithm was implemented in a volume haptics node and for visualisation a volume renderer node was implemented. These nodes can be used to setup different volume visualisation environments using VRML.

Knowledge of the leftventricular (LV) pressure-volume relation, along withparameters derived from this relation, have led to newpossibilities for the characterisation of cardiac pumpfunction, in both experimental studies and clinicalsettings. The pressure-volume diagram is apowerful tool for visualising LV performance, but in order tobe clinically useful it is necessary to make plots continuouslyand on-line. The conductance catheter technique offers thispossibility. The conductance catheter system has experiencedgrowing interest among cardiologists, physiologists, surgeons,and anaesthesiologists around the world as a powerful newresearch tool, but the invasiveness of this technique has beena limiting factor for most clinical applications. The catheterneeds to be thinner and softer in order to make this techniquemore suitable for human use. This thesis reports of a newthin and soft conductance catheter for continuously and on-linemeasurements of LV pressure and volume. One way to reduce both cathetersize and stiffness is to decrease the number of electrodes onthe catheter. Theoretical calculations shown in this thesisproves that it is possible to obtain the same performance witha single segment catheter as with a five-segment catheter. Thethin catheter has been tested and compared to a commercialfive-segment conductance catheter in animal studies. We conclude that the thin singlesegment conductance catheter can measure left ventricularvolume and pessure. The regression coefficient between the twomethods is good independent of loading condition and duringbaseline conditions the catheters produce very similar volumecurves. During preload reduction the estimated volume reductionis different in the two systems. Our thin catheter does notdisturb the heart's normal electrophysiology, neither by thecatheter current nor by any mechanical stimuli. The resultsdemonstrates that our thin, soft, single segment conductancecatheter has performance characteristics which warrant furtherdevelopment, with the goal to make the method available forhuman use. / NR 20140805

Membrane gas separation became an industrial reality in the late 1970s with Monsanto's first commercial asymmetric hollow fiber membrane modules. Innovations in membrane separations result from new materials that exhibit an improved permeability and are more selective than their predecessors, with materials commonly compared to the "upper bound line." Accurate determination of the three transport properties which characterize a membrane, permeability (P), diffusivity (D), and solubility (S), is thus of great interest to exceed the current upper bound line. Also, proper characterization of membrane materials enables enhancing current commercial membrane processes or allows for new applications. All three transport properties, P, S, and D, can be determined using a single dynamic gas permeation experiment in a constant volume (CV) system, commonly called the time-lag method. This work presents the next-generation CV system that utilizes the two-tank volume concept, namely a reference volume and a working volume. Compared to the previous iteration, the pressure in the reference volume can be reduced to the anticipated pressure in the working volume after initiating the gas permeation experiment. This allows monitoring of the pressure decay in the working volume (i.e., gas permeation into the membranes) using a high-resolution differential pressure transducer (DPT) right after initiating the experiment. The new system's operation is demonstrated by simultaneous monitoring of the upstream pressure decay and the downstream pressure rise during the time-lag experiments using a polyphenylene oxide (PPO) membrane. The values determined using the pressure decay method are compared to those determined using the downstream method to identify any limitations still present in the current iteration of the CV system. To set a reliable benchmark value to compare against, the downstream receiver was redesigned, and an optimal configuration was identified, which was associated with negligible resistance to gas accumulation and, thus, a minor error in the experimental time lag downstream from the membrane. Furthermore, a temperature enclosure was built to minimize errors caused by the constant temperature assumption during the time lag analysis. Additionally, the temperature-controlled enclosure allows for transport properties temperature dependence to be quantified by determining the activation energy of permeability, diffusion, and the enthalpy of solution for a given gas/polymer system.

Background: Ultrasound is safe and painless, produces pictures of the inside of the body using sound waves (not use ionizing radiation), thus there is no radiation exposure to the patient. The thyroid gland is among the most commonly imaged glands using ultrasound due to the limitation of clinical examination. The Radiographers' skills in ultrasound differ according to the country and the basic formations. And throught this study we want to emphasize about the role of radiographer. Aim: The porpuse of this study is determine the volume and morphological characteristics of normal thyroid order to get reference values for young adults. Material and Method: We selected 204 students consist of male and female from Danang University of Medical Technology And Pharmacy were studied. Mean age of our subjects was 22 (range 18-25) all of them were healthy and with normal thyroid gland status. Descriptive statistics and analytic statistic was used. Results: In our study, the thyroid volume between female and male is different. The total thyroid volume significantly correlated with individual’s height, weight, body surface area and body mass index. The mean of total thyroid volume was 7.44 ± 2.09ml (range 3.51-14.57). The thyroid volume was best correlated with height (r = 0.44; p = 0.0001). Conclusion: Knowledge about the size of the thyroid gland is important in following the thyroid diseases and the examination of the gland. The radiographer's role is very important in determining the volume of thyroid.Radiographer is an important member of the diagnostic health care team.