Fuzzy set Theory and Quantum Chemistry

Es discuteixen breument algunes consideracions sobre l'aplicació de la Teoria delsConjunts difusos a la Química quàntica. Es demostra aqui que molts conceptes químics associats a la teoria són adequats per ésser connectats amb l'estructura dels Conjunts difusos. També s'explica com algunes descripcions teoriques dels observables quàntics espotencien tractant-les amb les eines associades als esmentats Conjunts difusos. La funciódensitat es pren com a exemple de l'ús de distribucions de possibilitat al mateix temps queles distribucions de probabilitat quàntiques

New insights on river water chemistry by using non-centred simplicial principal component analysis: a case study

The use of perturbation and power transformation operations permits the investigation of linear processes in the simplex as in a vectorial space. When the investigated geochemical processes can be constrained by the use of well-known starting point, the eigenvectors of the covariance matrix of a non-centred principalcomponent analysis allow to model compositional changes compared with a reference point.The results obtained for the chemistry of water collected in River Arno (central-northern Italy) have open new perspectives for considering relative changes of the analysed variables and to hypothesise the relative effect of different acting physical-chemical processes, thus posing the basis for a quantitative modelling

Comparison studies of tin deposits (Priamurye, Russia) using the Aitchison’s methodology

A study of tin deposits from Priamurye (Russia) is performed to analyze the differencesbetween them based on their origin and also on commercial criteria. A particularanalysis based on their vertical zonality is also given for samples from Solnechnoedeposit. All the statistical analysis are made on the subcomposition formed by seventrace elements in cassiterite (In, Sc, Be, W, Nb, Ti and V) using the Aitchison’methodology of analysis of compositional data

Grain size analyses in tin-lead glazes based on 2d-sections

A problem in the archaeometric classification of Catalan Renaissance pottery is the fact, thatthe clay supply of the pottery workshops was centrally organized by guilds, and thereforeusually all potters of a single production centre produced chemically similar ceramics.However, analysing the glazes of the ware usually a large number of inclusions in the glaze isfound, which reveal technological differences between single workshops. These inclusionshave been used by the potters in order to opacify the transparent glaze and to achieve a whitebackground for further decoration.In order to distinguish different technological preparation procedures of the single workshops,at a Scanning Electron Microscope the chemical composition of those inclusions as well astheir size in the two-dimensional cut is recorded. Based on the latter, a frequency distributionof the apparent diameters is estimated for each sample and type of inclusion.Following an approach by S.D. Wicksell (1925), it is principally possible to transform thedistributions of the apparent 2D-diameters back to those of the true three-dimensional bodies.The applicability of this approach and its practical problems are examined using differentways of kernel density estimation and Monte-Carlo tests of the methodology. Finally, it istested in how far the obtained frequency distributions can be used to classify the pottery

Statistical evidences of cyclic changes in volcanic gas chemistry composition by inverse modelling

The identification of compositional changes in fumarolic gases of active and quiescent volcanoes is one of the mostimportant targets in monitoring programs. From a general point of view, many systematic (often cyclic) and randomprocesses control the chemistry of gas discharges, making difficult to produce a convincing mathematical-statisticalmodelling.Changes in the chemical composition of volcanic gases sampled at Vulcano Island (Aeolian Arc, Sicily, Italy) fromeight different fumaroles located in the northern sector of the summit crater (La Fossa) have been analysed byconsidering their dependence from time in the period 2000-2007. Each intermediate chemical composition has beenconsidered as potentially derived from the contribution of the two temporal extremes represented by the 2000 and 2007samples, respectively, by using inverse modelling methodologies for compositional data. Data pertaining to fumarolesF5 and F27, located on the rim and in the inner part of La Fossa crater, respectively, have been used to achieve theproposed aim. The statistical approach has allowed us to highlight the presence of random and not random fluctuations,features useful to understand how the volcanic system works, opening new perspectives in sampling strategies and inthe evaluation of the natural risk related to a quiescent volcano

Exploring chromium (VI) dioxodihalides chemistry: is density functional theory the most suitable tool?

A comparative systematic study of the CrO2F2 compound has been performed using different conventional ab initio methodologies and density functional procedures. Two points have been analyzed: first, the accuracy of results yielded by each method under study, and second, the computational cost required to reach such results. Weighing up both aspects, density functional theory has been found to be more appropriate than the Hartree-Fock (HF) and the analyzed post-HF methods. Hence, the structural characterization and spectroscopic elucidation of the full CrO2X2 series (X=F,Cl,Br,I) has been done at this level of theory. Emphasis has been given to the unknown CrO2I2 species, and specially to the UV/visible spectra of all four compounds. Furthermore, a topological analysis in terms of charge density distributions has revealed why the valence shell electron pair repulsion model fails in predicting the molecular shape of such CrO2X2 complexes

Surface states in template synthesized tin oxide nanoparticles

Tin-oxide nanoparticles with controlled narrow size distributions are synthesized while physically encapsulated inside silica mesoporous templates. By means of ultraviolet-visible spectroscopy, a redshift of the optical absorbance edge is observed. Photoluminescence measurements corroborate the existence of an optical transition at 3.2 eV. The associated band of states in the semiconductor gap is present even on template-synthesized nanopowders calcined at 800°C, which contrasts with the evolution of the gap states measured on materials obtained by other methods. The gap states are thus considered to be surface localized, disappearing with surface faceting or being hidden by the surface-to-bulk ratio decrease.

Gas identification with tin oxide sensor array and self-organizing maps: adaptive correction of sensor drifts

Low-cost tin oxide gas sensors are inherently nonspecific. In addition, they have several undesirable characteristics such as slow response, nonlinearities, and long-term drifts. This paper shows that the combination of a gas-sensor array together with self-organizing maps (SOM's) permit success in gas classification problems. The system is able to determine the gas present in an atmosphere with error rates lower than 3%. Correction of the sensor's drift with an adaptive SOM has also been investigated

Tennessee Williams's Cat on a hot tin roof or the dramatic aptitudes of the goddess Diana

The aim of this article is to show which are the dramatic "yields" of the inclusion of the reference to the goddess Diana in Tennessee Williams's Cat on a Hot tin Roof. In the author's opinion, it does not deal simply with a meaningful reference; on the contrary, the accurate analysis of Williams's text proves that it is a true nuclear and cohesive element of the whole drama.

Indagación edípica e ironía trágica: el modelo sofocleo en Cat on a Hot Tin Roof de Tennessee Williams

Dado que el referente clásico "Edipo en busca de su identidad" ha sido siempre reconocido para Suddenly Last Summer , el autor de este artículo, mediante un análisis minucioso del texto del dramaturgo americano, propone leer en este caso Cat on a Hot Tin Roof desde el modelo Edipo Rey de Sófocles y descubrir en él igualmente la tradicional ironía clásica tanto desde el punto de vista del espectador como de los mismos personajes principales, Brick y su padre, ambos en busca de su verdad, una verdad, claro está, contraria a la esperada.

Indagació edípica i ironia tràgica: el model sofocleu a Cat on a Hot Tin Roof de Tennessee Williams

Atès que el referent clàssic "Èdip en cerca de la seva identitat" ha estat sempre reconegut per a Suddenly Last Summer, l'autor d'aquest article, mitjançant una anàlisi acurada del text del dramaturg americà, proposa de llegir en aquest cas Can on a Hot tin Roof des del model Èdip Rei de Sòfocles i descobrir-hi igualment la tradicional ironia clàssica tant des del punt de vista de l'espectador com dels mateixos personatges principals, Brick i el seu pare, ambdós en cerca de la seva veritat, una veritat, és clar, contrària a la que esperaven.

Cat on a hot tin roof de Tennessee Williams o les aptituds dramàtiques de la deessa Diana

L'objectiu d'aquest article és mostrar quins són els rèdits dramàtics de la inclusió de la referència a la deessa Diana a Cat on a Hot Tin Roof de Tennessee Williams. En opinió del autor, no es tracta simplement d'una referència significativa, sinó que l'anàlisi acurada del text de Williams demostra que és un element vertaderament nuclear i cohesionador de tot el drama.

Cat on a hot tin roof de Tennessee Williams o las aptitudes dramáticas de la diosa Diana

El objetivo de este artículo es mostrar cuáles son los réditos dramáticos de la inclusión de la referencia a la diosa Diana en Cat on a Hot Tin Roof de Tennessee Williams. En opinión del autor, no se trata simplemente de una referencia significativa, sino que el análisis minucioso del texto de Williams demuestra que es un elemento verdaderamente nuclear y cohesionador de todo el drama.

CLIL Materials in Chemistry and English: Iodometric Titrations

Content and Language Integrated Learning (CLIL)Materials in Chemistry and English following the principles of CLIL / Content-based Instruction and Task-based Learning

Chemistry in Catalonia 1990-1995

The seven-year period studied here differs very little from the sixyear period described in the previous Report (1990-1995). Sustained growth was observed in almost all the indicators used to evaluate the resources invested and the scientific results obtained