95 research outputs found

    Nanocomposite MFI-alumina and FAU-alumina Membranes: Synthesis, Characterization and Application to Paraffin Separation and CO2 Capture

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    Rouleau, L. Pirngruber, G. Guillou, F. Barrere-Tricca, C. Omegna, A. Valtchev, V. Pera-Titus, M. Miachon, S. Dalmon, J. A.International audienceIn this work, we report the preparation of thermally and mechanically resistant high-surface (24-cm2) nanocomposite MFI-alumina and FAUalumina membranes by pore-plugging synthesis inside the macropores of α-alumina multilayered tubular supports. The MFI membranes were prepared from a clear solution precursor mixture being able to easily penetrate into the pores of the support. The MFI membranes were evaluated in the separation of n-/i-butane mixtures. The synthesis reliability was improved by mild stirring. The most selective MFI membranes were obtained for supports with mean pore sizes of 0.2 and 0.8 μm. The MFI effective thickness could be reduced to less than 10 μm by impregnating the support with water prior to synthesis and by diluting the synthesis mixture. The best MFI membrane offered an excellent tradeoff between selectivity and permeance at 448 K, with separation factors for equimolar n-butane/i-butane mixtures up to 18 and n-butane mixture permeances as high as 0.7 μmol⋅\cdots-1⋅\cdotm-2⋅\cdotPa-1.Furthermore, a novel nanocomposite FAU membrane architecture has been obtained by an original synthesis route including in situ seeding using a cold gel-like precursor mixture, followed by growth of the FAU material by hydrothermal synthesis in two steps using a clear solution of low viscosity. This new membrane showed interesting performance in the separation of an equimolar CO2/N2 mixture at 323 K, with CO2/N2 separation factors and mixture CO2 permeances up to 12 and 0.4 μmol⋅\cdots-1⋅\cdotm-2⋅\cdotPa-1,respectively

    A ausência de mutações no gene PAX6 em três casos de síndrome de Morning Glory associada à deficiência isolada de hormônio do crescimento

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    Morning glory syndrome (MGS) is a congenital optic disc dysplasia often associated with craniofacial anomalies, especially basal encephalocele and hypopituitarism. Clinical signs are varied and often occult. The PAX6 gene is involved in ocular morphogenesis and is expressed in numerous ocular tissues during development especially in the developing central nervous system. The aim of the present study is to evaluate PAX6 in MGS associated with isolated growth hormone deficiency. Three pre-pubertal males (A, B and C) with MGS and short stature due to growth hormone deficiency, treated with recombinant human growth hormone with limited response, were reported. Two of them had basal encephalocele. Coding and non-coding sequences corresponding of PAX6 different transcripts were analyzed by direct sequencing. Nucleotide variations causing putative aminoacid change were not observed. Patient A presented the new IVS2+9G>A transition, whereas patients A and C were heterozygous for known single nucleotide polymorphisms (SNP) within the intron 4. In addition, two SNP heterozygoses were observed for patient C in both intron 9 and 13. Sequencing also revealed several nucleotide variations in patient B. Two heterozygoses for known polymorphisms were identified along with a novel C>A nucleotide change in intron 4. This patient also presented a low number on the TG repeat in intron 9 and a new IVS11+33A>T transversion. Gene regulation and transcription of PAX6 are complex processes; there are two major protein isoforms, PAX6(-5a) and PAX6(+5a), and nine transcripts described. Furthermore, extra transcription regulatory elements have been postulated within PAX6 introns. Considering that neither population distributions on PAX6 polymorphism nor their linkeages with diseases have been reported, a functional effect due to alterations described here cannot be discarded.A síndrome de Morning Glory (SMG) é uma displasia óptica congênita associada a anomalias craniofaciais, principalmente encefalocele basal e hipopituitarismo. Os sinais clínicos são variados e muitas vezes ocultos. O gene PAX6 está envolvido na morfogênese ocular e se expressa em vários tecidos oculares durante o desenvolvimento do sistema nervoso central. O objetivo deste estudo foi avaliar o gene PAX6 na SMG associada com deficiência isolada de hormônio de crescimento. Foram relatados três pacientes pré-púberes (A, B e C) com SMG e baixa estatura por deficiência de hormônio de crescimento tratados com hormônio de crescimento recombinante humano. As seqüências codificadoras e não-codificadoras correspondentes ao PAX6 em diferentes transcritos foram analisadas por seqüenciamento direto. Variações nucleotídeas com trocas pontuais de aminoácidos não foram encontradas. O paciente A apresentou uma transição nova IVS2+9G>A, enquanto os pacientes A e C foram heterozigotos para um polimorfismo (SNP) no íntron 4. Ainda, dois SNPs em heterozigose nos íntrons 9 e 13 foram observados no paciente C. O seqüenciamento também mostrou várias variações nucleotídeas no paciente B. Dois SNPs conhecidos com a alteração nucleotídea nova C>A no íntron 4 foram observados em heterozigose. Este paciente também apresentou um baixo número de repetições TG no íntron 9 e uma nova transversão IVS11+33A>T. A regulação e a transcrição do gene PAX6 são um processo complexo; existem 2 isoformas principais da proteína, PAX6(-5a) e PAX6(+5a) e 9 transcritos descritos. Considerando que nem a distribuição de SNPs no PAX6 e nem as suas ligações com as doenças foram relatadas, um defeito funcional devido às alterações descritas não pode ser descartado.University of Campinas Faculty of Medical Sciences Pediatric Endocrinology UnitFederal University of São Paulo School of Medicine Pediatric Endocrinology UnitUNIFESP School of Medicine Department of RadiologyUnicamp Center of Molecular Biology and Genetic EngineeringUNIFESP, EPM, Pediatric Endocrinology UnitUNIFESP, School of Medicine Department of RadiologySciEL

    A ausência de mutações no gene PAX6 em três casos de síndrome de Morning Glory associada à deficiência isolada de hormônio do crescimento

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    Morning glory syndrome (MGS) is a congenital optic disc dysplasia often associated with craniofacial anomalies, especially basal encephalocele and hypopituitarism. Clinical signs are varied and often occult. The PAX6 gene is involved in ocular morphogenesis and is expressed in numerous ocular tissues during development especially in the developing central nervous system. The aim of the present study is to evaluate PAX6 in MGS associated with isolated growth hormone deficiency. Three pre-pubertal males (A, B and C) with MGS and short stature due to growth hormone deficiency, treated with recombinant human growth hormone with limited response, were reported. Two of them had basal encephalocele. Coding and non-coding sequences corresponding of PAX6 different transcripts were analyzed by direct sequencing. Nucleotide variations causing putative aminoacid change were not observed. Patient A presented the new IVS2+9G>A transition, whereas patients A and C were heterozygous for known single nucleotide polymorphisms (SNP) within the intron 4. In addition, two SNP heterozygoses were observed for patient C in both intron 9 and 13. Sequencing also revealed several nucleotide variations in patient B. Two heterozygoses for known polymorphisms were identified along with a novel C>A nucleotide change in intron 4. This patient also presented a low number on the TG repeat in intron 9 and a new IVS11+33A>T transversion. Gene regulation and transcription of PAX6 are complex processes; there are two major protein isoforms, PAX6(-5a) and PAX6(+5a), and nine transcripts described. Furthermore, extra transcription regulatory elements have been postulated within PAX6 introns. Considering that neither population distributions on PAX6 polymorphism nor their linkeages with diseases have been reported, a functional effect due to alterations described here cannot be discarded.A síndrome de Morning Glory (SMG) é uma displasia óptica congênita associada a anomalias craniofaciais, principalmente encefalocele basal e hipopituitarismo. Os sinais clínicos são variados e muitas vezes ocultos. O gene PAX6 está envolvido na morfogênese ocular e se expressa em vários tecidos oculares durante o desenvolvimento do sistema nervoso central. O objetivo deste estudo foi avaliar o gene PAX6 na SMG associada com deficiência isolada de hormônio de crescimento. Foram relatados três pacientes pré-púberes (A, B e C) com SMG e baixa estatura por deficiência de hormônio de crescimento tratados com hormônio de crescimento recombinante humano. As seqüências codificadoras e não-codificadoras correspondentes ao PAX6 em diferentes transcritos foram analisadas por seqüenciamento direto. Variações nucleotídeas com trocas pontuais de aminoácidos não foram encontradas. O paciente A apresentou uma transição nova IVS2+9G>A, enquanto os pacientes A e C foram heterozigotos para um polimorfismo (SNP) no íntron 4. Ainda, dois SNPs em heterozigose nos íntrons 9 e 13 foram observados no paciente C. O seqüenciamento também mostrou várias variações nucleotídeas no paciente B. Dois SNPs conhecidos com a alteração nucleotídea nova C>A no íntron 4 foram observados em heterozigose. Este paciente também apresentou um baixo número de repetições TG no íntron 9 e uma nova transversão IVS11+33A>T. A regulação e a transcrição do gene PAX6 são um processo complexo; existem 2 isoformas principais da proteína, PAX6(-5a) e PAX6(+5a) e 9 transcritos descritos. Considerando que nem a distribuição de SNPs no PAX6 e nem as suas ligações com as doenças foram relatadas, um defeito funcional devido às alterações descritas não pode ser descartado.1221122

    Catalytic membrane reactors

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    High temperature behavior of MFI-based membranes: comparison of film like and nanocomposite membranes

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    Preparing and Testing Pd Films of Thickness 1-2 Micrometer with High Selectivity and High Hydrogen Permeance

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    Théorie visco-élastique non-extensive II. Premiers tests expérimentaux de la théorie simplifiée à modes rotationnels

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    La théorie simplifiée à modes rotationnels développée dans l'article précédent (I), est testée à l'aide de données publiées de constantes élastiques, d'indice de réfraction, de susceptibilité magnétique, de viscosité de torsion, d'effets induits par des champs intenses, de chaleur spécifique et de chaleur de transition, et d'effets de pression sur la température de transition, de trois substances nématiques typiques. Un accord remarquable, tant du point de vue qualitatif que quantitatif, est obtenu avec toutes les données considérées. Les différentes conjectures proposées dans l'article (I) apparaissent être en très bon accord avec l'expérience, en particulier en ce qui concerne la description des phénomènes à travers la transition de phase. Deux conclusions importantes de cette étude concernent : (i) l'influence non-triviale des conditions expérimentales, telles que la taille de l'échantillon et des champs externes appliqués sur les valeurs des quantités physiques macroscopiques (ii) la mise en évidence, pour les matériaux nématogènes, et donc pour tous les liquides, de l'existence d'une échelle d'espace intermédiaire entre les molécules et l'échantillon macroscopique. Cette échelle est celle de la cellule unité du réseau cristallin de la phase solide, telle qu'on la détermine par la cristallographie de monocristaux. On argumente que la présente description peut remplacer avantageusement les descriptions partielles standards pour décrire la réalité expérimentale correspondante

    The dehydrogenation of 2-butanol over copper-based catalysis: optimising catalyst composition and determining kinetic parameters.

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