Nanostructured sonogels

Acoustic cavitation effects in sol-gel liquid processing permits to obtain nanostructured materials, with size-dependent properties. The so-called "hot spots" produce very high temperatures and pressures which act as nanoreactors. Ultrasounds force the dissolution and the reaction stars. The products (alcohol, water and silanol) help to continue the dissolution, being catalyst content, temperature bath and alkyl group length dependent. Popular choices used in the preparation of silica-based gels are tetramethoxysilane (TMOS), Si(OCH3)4 and tetraethoxysilane (TEOS), Si(OC 2H5)4. The resultant "sonogels" are denser gels with finer and homogeneous porosity than those of classic ones. They have a high surface/volume ratio and are built by small particles (1 nm radius) and a high cross-linked network with low -OH surface coverage radicals. In this way a cluster model is presented based on randomly-packed spheres in several hierarchical levels that represent the real sonoaerogel. Organic modified silicates (ORMOSIL) were obtained by supercritical drying in ethanol of the corresponding alcogel producing a hybrid organic/inorganic aerogel. The new material takes the advantages of the organic polymers as flexibility, low density, toughness and formability whereas the inorganic part contributes with surface hardness, modulus strength, transparency and high refractive index. The sonocatalytic method has proven to be adequate to prepare silica matrices for fine and uniform dispersion of CdS and PbS quantum dots (QDs), which show exciton quantum confinement. We present results of characterization of these materials, such as nitrogen physisorption, small angle X-ray/neutrons scattering, electron microscopy, uniaxial compression and nanoindentation. Finally these materials find application as biomaterials for tissue engineering and for CO2 sequestration by means the carbonation reaction.Ministerio de Ciencia y Tecnología MAT2005-158

The cluster model: A simulation of the aerogel structure as a hierarchically-ordered arrangement of randomly packed spheres

A new structural model based on the premises widely used for describing the structure of aerogels has been introduced. These structures have been described as an assemblage of randomly-packed spheres in several hierarchically-ordered levels. A new algorithm has been developed for constructing our models from these premises using computer simulation. Subsequently, several applications have been simulated to characterize real systems, obtaining textural parameters such as the specific surface area, specific porous volume or the apparent density of the systems, based on the Monte Carlo technique and on geometrical considerations. The object of these is to test the ability of the models to explain the structure of some real aerogels. This Cluster Model has also been applied as an initial approach to the study of the mechanical properties of aerogels. Results support the general conclusion that these models are useful for explaining the structure of aerogels.Ministerio de Ciencia y Tecnología MAT2002-00859Junta de Andalucía TEP 011

Larnite powders and larnite/silica aerogel composites as effective agents for CO2 sequestration by carbonation

This paper presents the results of the carbonation reaction of two sample types: larnite (Ca2SiO4) powders and larnite/silica aerogel composites, the larnite acting as an active phase in a process of direct mineral carbonation. First, larnite powders were synthesized by the reaction of colloidal silica and calcium nitrate in the presence of ethylene glycol. Then, to synthesize the composites, the surface of the larnite powders was chemically modified with 3-aminopropyltriethoxysilane (APTES), and later this mixture was added to a silica sol previously prepared from tetraethylorthosilicate (TEOS). The resulting humid gel was dried in an autoclave under supercritical conditions for the ethanol. The textures and chemical compositions of the powders and composites were characterized.The carbonation reaction of both types of samples was evaluated by means of X-ray diffraction and thermogravimetric analysis. Both techniques confirm the high efficiency of the reaction at room temperature and atmospheric pressure. A complete transformation of the silicate into carbonate resulted after submitting the samples to a flow of pure CO2 for 15 min. This indicates that for this reaction time, 1 t of larnite could eliminate about 550 kg of CO2. The grain size, porosity, and specific surface area are the factors controlling the reaction.Ministerio de Medio Ambiente A266/2007/3-11.1Ministerio de Educación y Ciencia MAT2005-0158

MÚSICA POPULAR Y LAS ARTES ESCÉNICAS PARA LA APROPIACIÓN DE LA CULTURA VENEZOLANA EN EDUCACIÓN UNIVERSITARIA

La investigación tuvo como propósito generar un cuerpo teórico de la música popular y las artes escénicas para la apropiación de la cultura venezolana en educación universitaria desde el pensamiento complejo, partiendo de la experiencia en la Universidad Pedagógica Experimental Libertador El Mácaro (Upel-El Mácaro) San Fernando, Estado Apure. El estudio se ubicó bajo la epistemología del pensamiento complejo apoyado en el enfoque de la complementariedad, enmarcado en los métodos: etnográfico, hermenéutico y racional. Para la recolección de la información, se recurrió a la observación participante, entrevista a profundidad a informantes clave de la institución y notas de campo. Para el análisis de los resultados se utilizó la categorización, estructuración, triangulación, contrastación y teorización de los hallazgos. El estudio concluyó con la construcción teórica la cual brindó aportes valiosos para  los miembros de la comunidad universitaria, en el perfeccionamiento del conocimiento, formación y capacitación desde una integralidad, asumiendo el arte musical popular y las artes escénicas como parte de dichos elementos, aspectos que  contribuyen al  fortalecimiento de las actitudes y valores del pensamiento artístico a través de experiencias estéticas para impulsar y fomentar el aprecio, la comprensión y la conservación de la cultura venezolana

Lorca y la canción popular: Las tres hojas: de la tradición al surrealismo

El comentario de una versión de la canción popular Las tres hojas que García Lorca oyó en su tierra pone de manifiesto la pervivencia en la tradición moderna de temas (la ausencia del amigo por enfermedad), motivos (el encuentro de los amantes bajo los árboles), formas y estructuras métricas (las series de seguidillas paralelísticas) y recursos de estilo que se afianzaron en la canción antigua, al tiempo que se descubre que en la canción lírica popular, en especial la infantil, Lorca encontró, como otros poetas de su tiempo, la visión de un mundo absurdo, incomprensible desde la realidad lógica, que ofreció y puso de moda el surrealismo.Analyzing a version of the popular song Las tres hojas which García Lorca listened in his homeland, this paper discusses the presence in modern tradition of old songs’ themes (the absence of the lover due to sickness), motifs (the encounter of the lovers under the trees), forms, metric structures (series of paralelistic seguidillas), and stitlistic resources. Lorca, like other poets of his time, found in the popular liric songs –specially in the children’s songs–, a view of an absurd and incomprehensible world that constituted the base for surrealism

Análise transcriptômica da mutante AphaR de Herbaspirillum seropedicae SmR1

Orientador : Prof. Dr. Marcelo Muller dos SantosCoorientadora : Profa. Dra. Leda Satie ShubatsuDissertação (mestrado) - Universidade Federal do Paraná, Setor de Ciências Biológicas, Programa de Pós-Graduação em Ciências : Bioquímica. Defesa: Curitiba, 20/03/2017Inclui referências : f. 89-89Resumo: O acumulo de rejeitos plásticos no mundo representa na atualidade um dos maiores problemas ambientais. Os "bioplásticos" são compostos com propriedades muito similares aos plásticos que sintetizados por numerosos organismos. Os polihidroxialcanoatos são um tipo de bioplásticos produzidos por diversos grupos de bactérias como estoque de carbono e energia, possuem propriedades termoplásticas, elastoméricas e são resistentes a ruptura. Herbaspirillum seropedicae é uma betaproteobactéria fixadora de nitrogênio também capaz de produzir polihidroxibutirato (PHB). Foram identificados vários genes implicados na biossintesse e formação do grânulo de PHB dentro de bactéria, além dos genes das fasinas phaP, phaP2, encontrou-se o gene phaR que codifica para uma proteína reguladora PhaR, a qual se liga ao DNA na região de vários genes implicados na biossíntese de PHB. Em estudos prévios feitos pelo grupo de Fixação Biológica de Nitrogênio da Universidade Federal do Paraná foi gerado o mutante ?phaR derivado da estirpe parental SmR1 que apresentou uma dinâmica de produção de PHB diferente na estirpe selvagem SmR1, neste projeto foi estudado o perfil transcriptómico do mutante ?phaR de H. seropedicae comparando os níveis de expressão dos genes com a estirpe selvagem propondo uma possível via de regulação da proteína repressora PhaR, também foi avaliado o crescimento do mutante em diferentes fontes de carbono e a produção de PHB. O mutante ?phaR apresentou uma diminuição na produção de PHB e diferenças no perfil de crescimento em meio com galactose respeito à estirpe parental SmR1. Na avaliação transcriptômica foram encontrados sobre expressos genes envolvidos na síntese de ácidos graxos assim enquanto transportadores de aminoácidos ramificados e acetaldeído desidrogenase tiveram a sua expressão diminuida; revelando um possível redirecionamento do Acetil-coA que não está sendo empregado na síntese de PHB. Além disso, foi encontrado sobre expresso um gene que codifica para uma proteína envolvida no estresse oxidativo enquanto genes que codificam para o complexo IV da cadeia respiratória tiveram a sua expressão diminuída, indicando uma possível resposta ao estresse gerado pelo acumulo de fatores redutores como NADH. Genes envolvidos no metabolismo de galactose tiveram a sua expressão aumentada, enquanto vários reguladores transcricionais, entre eles um envolvido no metabolismo de arabinose araC, tiveram expressão diminuída. Foi demostrado também o papel de PhaR como regulador de fasinas já que ambos genes tiveram a sua expressão aumentada. Palavras chave: Polihidroxibutirato, Transcriptoma, Herbaspirillum seropedicae, repressor, expressão genética.Abstract: Worldwide plastic waste accumulation is one of the main issues to address today, current alternatives are based on the development of new materials that can be easily degraded biologically in short periods without any contamination. "Bioplastics" are compounds whose properties are very similar to oil derived plastics but they are synthetized by living organisms. Polyhydroxyalkanoates are compounds related to bioplastics produced by several bacteria as an energy and carbon storage. They have good thermoplastics and elastomeric properties and are resistant to break. Herbaspirillum seropedicae it's a nitrogen fixating betaproteobacteria, also able to produce Polyhydroxybatyrate (PHB). There were identified several genes involved in PHB synthesis and granule formation, besides the phasins genes phaP1, phaP2, there was found the phaR gene that codifies a regulatory protein PhaR, wich is able to bind DNA in several regions of genes involved in PHB synthesis. In previous studies developed by the Nitrogen Fixation Group of the Universidade Federal do Paraná the ?phaR mutant was constructed from the parental strain SmR1, this mutant showed differences in the PHB production when compared to the wild type SmR1, in this work the transcriptomic profile of the ?phaR mutant was studied and the levels of expression compared with the wild type SmR1, a possible regulation pathway of the PhaR protein was proposed, also the growth dynamics in different carbon sources and PHB production was assayed. The ?phaR mutant showed a decreased in PHB production, and differences in growth patterns when grown in galactose. The transcriptomic profile showed an over expression of genes involved in fatty acid biosynthesis whereas there was a decrease on the expression of branched chain aminoacids and acetaldehyde dehydrogenase genes, this shows a possible path for redirecting Acetil-coA surplus because of low PHB production. Besides, there were found over expressed genes involved in oxidative stress whereas transcription of genes responsible for the synthesis of complex IV of the respiratory chain were decreased, indicating a possible response to stress generated for excess of NADH. Genes involved in galactose metabolism had an augmented expression in the ?phaR mutant whereas genes involved in transcription regulation included araC, a regulator of the arabinose metabolism presented a decrease on its transcription. It was demonstrated also the role of PhaR as a phasin regulator since both phasins presented an augmented transcription. Keywords: Polyhydroxibutyrate, Transcriptome, Herbaspirillum seropedice, repressor, gene expression

SANS study of hybrid silica aerogels under "in situ" uniaxial compression

We have modified the inorganic silica network of aerogels with polydimethylsiloxane (PDMS), a hydroxyl-terminated polymer, to obtain an organic modified silicate (ORMOSIL). Reactions were assisted by high-power ultrasounds. The resulting gels were dried under supercritical conditions of the solvent to obtain a monolithic sono-aerogel. The mechanical behaviour of these aerogels can be tuned from brittle to rubbery as a function of the organic polymer content. In order to determine the links between the mechanical behaviour and modifications made to the microstructure, SANS (small-angle neutron scattering) experiments were carried out. To measure the intensities under "in situ" uniaxial compression of the aerogel, a specific sample-holder was built. Under uniaxial compression the 2D-diagrams were significantly anisotropic (butterfly pattern), indicating the rearrangement of the polymer. The form factor of these aerogels is described well by two correlation lengths, small microporous silica clusters surrounded by entangled polymer chains of 6 nm average size (blobs), which form a larger secondary level of agglomerates governed by the "frozen-in" elastic constraints.Comisión Interministerial de Ciencia y Tecnología MAT2005-1583European Commission CT-2003-50592

Upcoming Special Issue: “Artificial Intelligence, Data Science and E-health in Vision Research and Clinical Activity”

[Excerpt] Over the past 13 years Journal of Optometry has published a significant amount of scientific and clinical information covered in over 450 manuscripts published with Original Articles and Review Articles representing over 76% of all the documents making the journal rank high in the international databases.1,2 Considering the emerging technological advances applied to visual sciences the Journal will publish a Special Issue to include novel scientific contributions and novel applications of different branches of artificial intelligence, data science and other approaches to digitalization of vision science research and clinical activity. From basic visual function testing of visual acuity or contrast sensitivity3 to complex screening and diagnostic tools including visual field evaluation technology4 is about to change the paradigm of applying screening testing in flexible, portable and self-used platforms. This has the potential of expanding the capability of the population to self-screen their vision, receive warning messages to visit a clinician and potentially promote early diagnosis. This is also an opportunity to obtain massive amounts of data that might improve our understanding of visual science and vision health provision around the World. [...]- (undefined

The cluster model: A hierarchically-ordered assemblage of random-packing spheres for modelling microstructure of porous materials

A new structural model based on the premises widely used for describing the structure of random materials, and especially aerogels, is introduced. Aerogels are described as an assemblage of randomly-packed spheres in several hierarchically-ordered levels. A new algorithm has been developed for constructing structural models from these premises using computer simulation. Subsequently, several techniques based both on the Monte Carlo technique and on geometrical considerations for characterizing real systems have been simulated, and textural parameters of the models have been obtained, including specific surface area, specific porous volume and the apparent density of the systems. This characterization process yields a set of parameters used for testing the capacity of the models to reproduce the structure of several real systems, like aerogels. Special attention has been paid to the pore size distribution calculations: the Monte Carlo integration and the triangulation algorithms have been compared.Comisión Interministerial de Ciencia y Tecnología MAT2005-158