Magnetic resonance imaging of the vocal tract: techniques and applications

Magnetic resonance (MR) imaging has been used to analyse and evaluate the vocal tract shape through different techniques and with promising results in several fields. Our purpose is to demonstrate the relevance of MR and image processing for the vocal tract study. The extraction of contours of the air cavities allowed the set - up of a number of 3D reconstruction image stacks by means of the combination of orthogonally oriented sets of slices for e ach articulatory gesture, as a new approach to solve the expected spatial under sampling of the imaging process. In result these models give improved information for the visualization of morphologic and anatomical aspects and are useful for partial measure ments of the vocal tract shape in different situations. Potential use can be found in Medical and therapeutic applications as well as in acoustic articulatory speech modelling.

Modelling and segmentation of the vocal tract during speech production by using deformable models in magnetic resonance images

The first and second authors would like to thank the support of the PhD grants with references SFRH/BD/28817/2006 and SFRH/PROTEC/49517/2009, respectively, from Funda����o para a Ci��ncia e Tecnol ogia (FCT). This work was partially done in the scope of the project ���Methodologies to Analyze Organs from Complex Medical Images ��� Applications to Fema le Pelvic Cavity���, wi th reference PTDC/EEA- CRO/103320/2008, financially supported by FCT.

Simulation of the magnetic induction vector of a magnetic core to be used in FFC NMR relaxometry

This paper is a contribution for the assessment and comparison of magnet properties based on magnetic field characteristics particularly concerning the magnetic induction uniformity in the air gaps. For this aim, a solver was developed and implemented to determine the magnetic field of a magnetic core to be used in Fast Field Cycling (FFC) Nuclear Magnetic Resonance (NMR) relaxometry. The electromagnetic field computation is based on a 2D finite-element method (FEM) using both the scalar and the vector potential formulation. Results for the magnetic field lines and the magnetic induction vector in the air gap are presented. The target magnetic induction is 0.2 T, which is a typical requirement of the FFC NMR technique, which can be achieved with a magnetic core based on permanent magnets or coils. In addition, this application requires high magnetic induction uniformity. To achieve this goal, a solution including superconducting pieces is analyzed. Results are compared with a different FEM program.

Electrochemical and spectroscopic studies of the oxidation mechanism of the herbicide propanil

Electrochemical oxidation of propanil in deuterated solutions was studied by cyclic, differential pulse, and square wave voltammetry using a glassy carbon microelectrode. The oxidation of propanil in deuterated acid solutions occurs at the nitrogen atom of the amide at a potential of +1.15 V vs Ag/ AgCl. It was also found that, under the experimental conditions used, protonation at the oxygen atom of propanil occurs, leading to the appearance of another species in solution which oxidizes at +0.60 V. The anodic peak found at +0.79 V vs Ag/AgCl in deuterated basic solutions is related to the presence of an anionic species in which a negative charge is on the nitrogen atom. The electrochemical data were confirmed by the identification of all the species formed in acidic and basic deuterated solutions by means of NMR spectroscopy. The results are supported by electrochemical and spectroscopic studies of acetanilide in deuterated solutions.

Utiliza����o da Nanotecnologia para o desenvolvimento sustent��vel na ind��stria agro-alimentar

O crescimento populacional esperado para os pr��ximos anos conduzir�� �� necessidade de aumentar a produ����o agr��cola de modo a satisfazer o aumento da procura. Nos ��ltimos anos tem-se assistido a uma evolu����o tecnol��gica nos sistemas de produ����o que tem permitido aumentar a produtividade agr��cola, por vezes �� custa de elevados consumos de energia e com pr��ticas nem sempre ambientalmente corretas. Os desafios que se colocam atualmente s��o no sentido de melhorar a conserva����o de recursos escassos, como o solo e a ��gua, de aumentar a efici��ncia de uso de fatores de produ����o, de encontrar novas culturas, do desenvolvimento da biotecnologia, da diminui����o dos consumos energ��ticos e de melhorar ainda mais as tecnologias associadas �� produ����o. De maneira a responder aos desafios emergentes da procura por alimentos, da escassez de terrenos agr��colas ar��veis bem como da exist��ncia de pragas de insetos e de ervas daninhas, os pesticidas tem vindo a ser usados com maior frequ��ncia, tendo-se assistido a uma contamina����o dos solos e ��guas subterr��neas, causando deste modo um risco para a sa��de dos seres vivos. Neste sentido, v��rios fabricantes de pesticidas est��o a desenvolver novas formula����es contendo pesticidas encapsulados em nanopart��culas como modo de aumentar a sua solubilidade em ��gua, biodisponibilidade, volatilidade, estabilidade e efic��cia. tendo por objetivo um desenvolvimento sustent��vel. Neste trabalho, procedeu-se ao estudo do encapsulamento do herbicida Oxadiargil (5-terc-butil-3-[2,4-dicloro-5-(2-propiniloxi)fenil]-1,3,4-oxadiazol-2(3H)-ona) com a 2-hidroxipropil-��-ciclodextrina (HP-��-CD). O estudo da forma����o do complexo de inclus��o Oxadiargil - HP-��-CD foi realizado em diferentes meios, ��gua desionizada, tamp��o acetato pH = 3,46 e pH = 5,34 e tamp��o fosfato pH = 7,45, com o objetivo de determinar e comparar a sua constante de estabilidade. Verificou-se, em qualquer dos casos, a ocorr��ncia de uma rela����o linear entre o aumento da solubilidade do Oxadiargil e o aumento da concentra����o de HP-��-CD, com um declive inferior a um, o que indicia a forma����o de um complexo na propor����o estequiom��trica de 1:1. Os resultados obtidos permitiram concluir que o processo de complexa����o Oxadiargil - HP-��-CD n��o �� muito influenciado pela constitui����o e pelo pH do meio. De facto, as constantes de estabilidade obtidas para a ��gua desionizada e solu����es-tamp��o pH = 3,46, pH = 5,34 e pH = 7,45 foram de 919 �� 25, 685 �� 13, 623 �� 17 e 753 �� 9, respetivamente. A solubilidade do complexo obtido nos estudos realizados, em diferentes meios, �� cerca de 23 a 32 vezes superior �� observada para o Oxadiargil livre. De forma a caracterizar o complexo Oxadiargil - HP-��-CD procedeu-se �� sua s��ntese utilizando o m��todo de ���kneading���. O composto obtido foi caracterizado por Resson��ncia Magn��tica Nuclear (RMN) tendo-se confirmado a forma����o de um complexo de inclus��o na propor����o estequiom��trica de 1:1. O complexo obtido �� mais sol��vel e porventura mais est��vel quimicamente. O encapsulamento permite uma redu����o da aplica����o dos pesticidas diminuindo assim os custos e o impacto negativo no ambiente. Com a nanotecnologia �� poss��vel a liberta����o controlada dos pesticidas, aumentando a sua efic��cia e fornecendo os meios necess��rios para um desenvolvimento sustent��vel.

Influence of Hydroxypropyl- �� -Cyclodextrin on the Photostability of Fungicide Pyrimethanil

Pesticides continue to play an important role in pest management. However, the intensive pesticide application has triggered several environment negative effects that cannot be disregarded. In this study, the inclusion complex of pyrimethanil with HP- �� -CD has been prepared and characterized by proton nuclear magnetic resonance spectroscopy. The formation of the pyrimethanil/HP- �� -CD inclusion complex increased the aqueous solubility of this fungicide around five times. To assess the influence of microencapsulation on the environmental photostability of the fungicide, the photochemical degradation of pyrimethanil and pyrimethanil/HP- �� -CD inclusion complex has been investigated in different aqueous media such as ultrapure and river water under simulated solar irradiation. The studies allow concluding that pyrimethanil/HP- �� -CD inclusion complex increases significantly the photostability of the fungicide in aqueous solutions, especially in natural water. Actually, the half-life of pyrimethanil/HP- �� -CD inclusion complex was increased approximately by a factor of four when compared to the free fungicide. The overall results point out that pyrimethanil can be successfully encapsulated by HP- �� -CD, a process that can improve its solubility and photostability properties.