Hidrogenofosfato de titânio lamelar: síntese, troca iônica e intercalação

The development associated with the research field involving crystalline inorganic lamellar titanium hydrogenphosphate, Ti(HPO4).H2O, synthesized as alpha or gamma forms, is directly linked to the huge number of reactions, that occur inside the free interlamellar space. Two distinguishable well-characterized features such as ion-exchange and intercalation reactions are explored here. From the interactive point of view, the acidic OH centres distributed on the lamella can interact with cations or with basic polar molecules to exchange or to intercalate them. These chemical reactions are normally followed by an expansion of the interlamellar space, proportional to the amount intercalated, reflecting in ion radii or organic molecule size lengths used in ion-exchange or insertion processes, respectively. The effectiveness of the exchange increased when the original matrix has the proton of OH group previously ion-exchanged by an alkaline or an alkylammonium cations. Monoalkyl-, dialkyl- and heterocyclic amines are focused in this revision as clear and elucidative examples of acid-base interactive processes, that come out inside of the well-formed infinite sequence of inorganic lamellar structure.

PROPUESTA DE UN AMBIENTE E-LEARNING PARA EL FORTALECIMIENTO DE LAS HABILIDADES DE ALFABETIZACIÓN VISUAL E INFORMACIONAL: CASO LICENCIATURA EN ELECTRÓNICA - UPN.

El proyecto "Propuesta de un ambiente e-learning para el fortalecimiento de las habilidades de alfabetización visual e informacional: caso Licenciatura en Electrónica - UPN" fortalece la investigación alrededor de ambientes e-learning de la Universitat Oberta de Catalunya (UOC). Con la investigación se buscó determinar las estrategias organizativas, pedagógicas y tecnológicas a implementar en el diseño y desarrollo de un entorno e-learning que promueva las habilidades de alfabetización visual e informacional en estudiantes de primer semestre de la Licenciatura en Electrónica de la Universidad Pedagógica Nacional de Colombia. La investigación realizada fue de tipo cualitativo a través de un estudio de caso.

Distribuição de metais e caracterização das constantes de troca entre espécies metálicas e frações húmicas aquáticas de diferentes tamanhos moleculares

In this work the metal distribution and exchange constants between metal species and aquatic humic fractions with different molecular sizes were studied. The aquatic humic substances (AHS) were extracted by XAD-8 resin from water sample collected from Itapitanguí river, São Paulo State, Brazil. The AHS were fractionated in six fractions with different molecular sizes (>100 - <5 kDa) and characterized by several techniques. Molar ratios H/C suggested higher aromaticity for fractions F1 and F6 whereas molar ratios C/N didn´t show any differences regarding the humification degree between the fractions. The UV-Vis absorbance a254/a436 ratio showed higher results for F4 and F5, probably by less condensed features. FTIR studies showed high similarity in the functional groups in the fractions. The highest percentage of traces of Co, Al, Fe, Mn, Cu, Zn and Ni (determined by ICP-AES) was preferably complexed by fractions F3 and F4 with a greater amount of dissolved organic carbon (DOC). In addition, the exchange constants, determined by ultrafiltration method, showed complexes AHS-Fe and AHS-Al with higher stability than complexes AHS-Co in all fractions.

La regulación de la Administración electrónica y sus principios rectores

[spa] Actualmente, nos encontramos inmersos en un proceso de globalización y tecnificación al que las Administraciones públicas, como parte integrante de l a sociedad, no pueden permanecer ajenas. Todas las Administraciones, en sus distintos niveles y ámbitos de actuación, han introducido en su actividad las nuevas tecnologías de la información y la comunicación, y han puesto en marcha un proceso transformación de carácter cultural, organizativo y jurídico que ha fructificado en un nuevo modelo de gestión de la actividad pública conocido bajo el nombre de Administración electrónica. El uso de las nuevas tecnologías y la transición de una Administración «en pa pel» a una Administración electrónica han conllevado una serie de reformas de nuestro ordenamiento jurídico: nuevas normas y reforma de otras ya existentes que regulan los aspectos técnicos derivados de la utilización de las nuevas tecnologías por parte de la Administración, así como los derechos y garantías de los que están revestidos los ciudadanos cuando se relacionan con la Administración por medios telemáticos. Con este telón de fondo, podemos definir un elenco de principios que regirán la actuación de la Administración electrónica y en los que se erigen como protagonistas aquellos que persiguen garantizar la igualdad y la no discriminación de los ciudadanos, combatiendo la denominada brecha digital.

La Administración electrónica en España: de la 'administración en papel' a la 'e-administración'

[spa] Desde principios de los noventa, nuestra sociedad está sufriendo una serie de cambios asociados al uso masivo de las nuevas tecnologías de la información y la comunicación (TIC). En este nuevo modelo social, conocido bajo el nombre de sociedad de la información, las Administraciones públicas han tenido que adaptarse, introduciendo las nuevas tecnologías en su actividad cotidiana. No obstante, la transformación de las Administraciones públicas va más allá del uso de las TIC, pues supone una auténtica transformación de una administración en papel a una verdadera administración electrónica. Todo ello conlleva modificaciones en el ordenamiento jurídico, así como en las relaciones entre la Administración con los ciudadanos. En este trabajo, analizamos el desarrollo de este proceso en las Administraciones públicas españolas.

Um experimento-charada usando data-show e resinas de troca iônica

A demonstractive experiment was proposed in order to verify students' habilities in recognizing the presence and nature of ions in solutions, before and after their passage through ion-exchange columns. The students have no previous contact with ion-exchange resins, so they must deduce how they work and explain the experimental facts. The performance of classes, at different stages of learning, is compared and discussed.

Multímetro interfaceado de baixo custo para aquisição de dados

A digital multimeter (~U$ 240.00 on the national market) connected to a microcomputer by a RS-232 serial interface is proposed for data acquisition in equipment with analog output. Data are measured at the rate of 2 points per second and stored in text files by the software that accompanies the device, running in a Windows environment. The performance of the multimeter was verified by monitoring the transient signals generated in flow injection systems associated with fluorimetric, spectrophotometric and flame photometric detection. In addition, the performance of the proposed device was similar to that attained by employing an interface card with a 12-bit analog-to-digital converter for acquisition of the signals generated by a capillary electrophoresis equipment with oscillometric detection.

Determinação de bromato em melhoradores de farinha por cromatografia de troca iônica com detecção espectrofotométrica

KBrO3 is registered by the FAO/OMS as a genotoxic and carcinogenic compound. In spite of this, KBrO3 is still employed by Brazilian bakeries. Nowadays ion exchange chromatography (IEC) is the most rapid and trustful method for BrO3- analysis. When at high concentrations, chloride ions can interfere in the BrO3- analysis, if the detection is performed by electrical conductivity. On the other hand, spectrophotometric detection, presented here is based on the absorption of BrO3- in the ultraviolet region (210 - 230 nm) where the absortion of chloride ions is very low, thus making possible the qualitative and quantitative analysis of BrO3- in flour improver samples.

Cromatografia de troca-iônica aplicada ao isolamento da fração ácida do óleo de copaíba (Copaifera multijuga) e da sacaca (Croton cajucara)

Plant extracts are usually complex mixtures which contain several molecules of different sizes with varied functional groups. Such extracts are a challenge to the chemist of natural products. Ion exchange chromatography in non-aqueous medium, used for separation of basic or acidic fractions from plant extracts, is an important unit operation in preparative scale separations. Anionic macroporous resin in non-aqueous medium was used with success in this study for separation of the acid fraction of Copaifera multijuga (Copaiba oil), rich in labdanic diterpenes and for the methanolic extract of Croton cajucara (acetyl aleuritoric acid).

PARAFAC: uma ferramenta quimiométrica para tratamento de dados multidimensionais. Aplicações na determinação direta de fármacos em plasma humano por espectrofluorimetria

Since the last decade, the combined use of chemometrics and molecular spectroscopic techniques has become a new alternative for direct drug determination, without the need of physical separation. Among the new methodologies developed, the application of PARAFAC in the decomposition of spectrofluorimetric data should be highlighted. The first objective of this article is to describe the theoretical basis of PARAFAC. For this purpose, a discussion about the order of chemometric methods used in multivariate calibration and the development of multi-dimensional methods is presented first. The other objective of this article is to divulge for the Brazilian chemical community the potential of the combination PARAFAC/spectrofluorimetry for the determination of drugs in complex biological matrices. For this purpose, two applications aiming at determining, respectively, doxorrubicine and salicylate in human plasma are presented.

Aspectos estruturais relacionados ao processo de troca iônica no niobato lamelar K4Nb6O17

The niobate with formula K4Nb6O17 has a layered structure formed by stacked negative sheets and exchangeable cations in the interlayer region. In this study we discuss some structural aspects related to the ion exchange in layered hexaniobate based on X-ray diffractometry and vibrational Raman spectroscopy data. Hexaniobate has two distinct interlayer regions and the potassium ions of one interlayer in particular are preferably exchanged by other cations, leading to an interstratified material.

Identificação de substâncias em análise toxicológica sistemática utilizando um sistema informatizado para cálculo de parâmetros cromatográficos e busca em bases de dados

In spite of the availability of large databases of chromatographic data on several standardized systems, one major task in systematic toxicological analysis remains, namely how to handle the experimental data and retrieve data from the large available databases in a meaningful and productive way. To achieve this purpose, our group proposed an Internet-based tool using previously published STA databases, which interlaboratorial reproducibility tests have already evaluated. The developed software has the capability to calculate corrected chromatographic parameters, after the input of data obtained with standard mixtures of calibrators, and search the databases, currently incorporating TLC, color reactions, GC and HPLC data. At the end of the process, a list with candidate substances and their similarity indexes is presented.

Reconhecimento de padrões por métodos não supervisionados: explorando procedimentos quimiométricos para tratamento de dados analíticos

An activity for introducing hierarchical cluster analysis (HCA) and principal component analysis (PCA) during the Instrumental Analytical Chemistry course is presented. The posed problem involves the discrimination of mineral water samples according to their geographical origin. Thirty-seven samples of 9 different brands were considered and the results from the determination of Na, K, Mg, Ca, Sr and Ba were taken into account. Non-supervised methods for pattern recognition were explored to construct a dendrogram, score and loading plots. The devised activity can be adopted for introducing Chemometrics devoted to data handling, stressing its importance in the context of modern Analytical Chemistry.

L"ús del portafolis europeu de les llengües en versió electrònica (ePEL+14) en l"aprenentatge formal i no formal de la llengua i cultura catalanes

Aquest article presenta el Portafolis Europeu de les Llengües en versió electrònica (ePEL+14) validat pel Consell d'Europa l"any 2010. En primer lloc, s"introdueix en que consisteix un portafolis educatiu, com s"ha passat al portafolis electrònic per l"ensenyament de llengües. En segon lloc, es descriu aquest nou portafolis electrònic europeu adreçat a l"aprenentatge de llengües i cultures, que pot ser utilitzat com a suport de l"ensenyament de llengües, com a instrument transversal per fomentar l"autonomia de l"aprenent de llengües cap a l"adquisició progressiva dels nivells del Marc Comú Europeu de Referència per a les Llengües (MCER) o com a eina d"auto-aprenentatge de les competències lingüístiques assolides per part de l"aprenent de llengües autònom. En darrer lloc, s"extreuen algunes conclusions preliminars de l"experiència d"incorporar l"ePEL+14 en els Erasmus Intensive Language Courses (EILC) de llengua catalana de la Xarxa Vives d"Universitats.

El portafolis europeu de llengües en versió electrònica (ePEL+14): percepció del professorat universitari de la Xarxa Vives

Aquest article presenta el portafolis europeu de llengües en versió electrònica (ePEL+14) recentment validat pel Consell d'Europa. El propòsit és descriure aquesta innovació educativa en la docència universitària dels Erasmus Intensive Language Courses (EILC) i conèixer l'opinió dels professors universitaris de llengua catalana de la Xarxa Vives participants en la primera preexperimentació amb aquesta innovació en el curs 2011-2012. Es va dur a terme una enquesta després d’un taller de l'ePEL+14 en els EILC. El qüestionari ad hoc contenia quatre dimensions: variables sociodemogràfiques, coneixement previ del PEL i ePEL, materials de suport per implementar-ho i conseqüències del seu ús en l'aprenentatge de la llengua. La valoració va ser positiva, especialment per l'adequació de l'eina tecnològica i les funcionalitats informatives i pedagògiques per a l’aprenent de llengües. No obstant això, també assenyalen una influència moderada en l’aprenentatge de la llengua i cultura.