The use of heterogeneous chemistry for the characterization of functional groups at the gas/particle interface of soot and TiO(2) nanoparticles

Six gases (N((CH3)3), NH2OH, CF3COOH, HCl, NO2, O3) were selected to probe the surface of seven combustion aerosol (amorphous carbon, flame soot) and three types of TiO2 nanoparticles using heterogeneous, that is gas-surface reactions. The gas uptake to saturation of the probes was measured under molecular flow conditions in a Knudsen flow reactor and expressed as a density of surface functional groups on a particular aerosol, namely acidic (carboxylic) and basic (conjugated oxides such as pyrones, N-heterocycles) sites, carbonyl (R1-C(O)-R2) and oxidizable (olefinic, -OH) groups. The limit of detection was generally well below 1% of a formal monolayer of adsorbed probe gas. With few exceptions most investigated aerosol samples interacted with all probe gases which points to the coexistence of different functional groups on the same aerosol surface such as acidic and basic groups. Generally, the carbonaceous particles displayed significant differences in surface group density: Printex 60 amorphous carbon had the lowest density of surface functional groups throughout, whereas Diesel soot recovered from a Diesel particulate filter had the largest. The presence of basic oxides on carbonaceous aerosol particles was inferred from the ratio of uptakes of CF3COOH and HCl owing to the larger stability of the acetate compared to the chloride counterion in the resulting pyrylium salt. Both soots generated from a rich and a lean hexane diffusion flame had a large density of oxidizable groups similar to amorphous carbon FS 101. TiO2 15 had the lowest density of functional groups among the three studied TiO2 nanoparticles for all probe gases despite the smallest size of its primary particles. The used technique enabled the measurement of the uptake probability of the probe gases on the various supported aerosol samples. The initial uptake probability, g0, of the probe gas onto the supported nanoparticles differed significantly among the various investigated aerosol samples but was roughly correlated with the density of surface groups, as expected. [Authors]

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

The impact of theoretical chemistry in Biology

Els avenços en les bases dels mètodes teòrics i l'espectacular desenvolupament de la potència de càlcul han fet possible progressar enormement en el somni dels fundadors de la química, és a dir, ser capaços d'estudiar amb mètodes computacionals el conjunt de processos químics. Actualment, la química teòrica està completant el darrer avenç: intentar esdevenir l'eina més recent per a comprendre la naturalesa química dels éssers vius. Aquesta revisió pretén mostrar com els mètodes de la química teòrica, originalment desenvolupats per a examinar molècules petites en fase gas, han evolucionat per a assolir la complexa descripció de sistemes biològics.

Construcción de un índice de calidad ocupacional (ICO) para el análisis de la inserción profesional de los graduados universitarios = Building an employment quality index (EQI) to analyse graduates’ access to the labour market

En este trabajo se propone la construcción de un índice de calidad ocupacional (ICO) a partir de los datos de la Encuesta de Inserción Laboral de los Graduados de las Universidades Catalanas realizada por la Agencia para la Calidad del Sistema Universitario de Catalunya (AQU), que ha de permitir un mejor análisis de la información que proporciona la encuesta y facilitar su comparación con estudios similares. La encuesta se realiza tres años después de la graduación. En este artículo, se utiliza la segunda encuesta realizada el año 2005 entre 11.456 graduados (52,63%) de la promoción 2001 (AQU, 2005, Serra-Ramoneda, 2007). El índice se ha elaborado a partir de los indicadores objetivos ‘tipo y duración del contrato laboral’, ‘retribución económica’, ‘adecuación entre la formación universitaria y el empleo’ a los que se otorga una puntuación ponderada según las respuestas dadas por los graduados. La suma de las puntuaciones se matiza con un coeficiente derivado del indicador subjetivo ‘satisfacción con el trabajo en general’. A partir de la información proporcionada por el índice, se realiza un análisis comparativo del nivel de calidad ocupacional que han logrado los graduados de áreas de conocimiento, ámbitos de trabajo, ramas de actividad y ubicaciones territoriales del empleo diferentes. Los resultados obtenidos permiten observar que entre los graduados catalanes los siguientes hechos son buenos predictores de la calidad de la ocupación: haber estudiado una carrera que no sea de Humanidades, ser un hombre, haber desempeñado durante la carrera un trabajo relacionado con los estudios, estar ocupado en la construcción, en instituciones financieras o en servicios a empresas, haber tenido algún tipo de movilidad por motivos de trabajo, trabajar fuera de Cataluña y hacerlo en empresas grandes, especialmente con más de 500 trabajadores. Finalmente, se presentan algunas reflexiones y propuestas que pueden resultar de interés para la orientación de los estudiantes y la planificación universitaria

Effects of repeated slash removal in thinned stands on soil chemistry and understorey vegetation

Abstract

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

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

Postmortem chemistry update part II.

As a continuation of "Postmortem Chemistry Update Part I," Part II deals with molecules linked to liver and cardiac functions, alcohol intake and alcohol misuse, myocardial ischemia, inflammation, sepsis, anaphylaxis, and hormonal disturbances. A very important array of new material concerning these situations had appeared in the forensic literature over the last two decades. Some molecules, such as procalcitonin and C-reactive protein, are currently researched in cases of suspected sepsis and inflammation, whereas many other analytes are not integrated into routine casework. As in part I, a literature review concerning a large panel of molecules of forensic interest is presented, as well as the results of our own observations, where possible.

Trace element chemistry and U-Pb dating of zircons from oceanic gabbros and their relationship with whole rock composition (Lanzo, Italian Alps)

The U-Pb ages and the trace element content of zircon U-Pb along with major and trace element whole rock data on gabbroic dikes from the Lanzo lherzolitic massif, N-Italy, have been determined to constrain crustal accretion in ocean-continent transition zones. Three Fe-Ti gabbros were dated from the central and the southern part of the massif providing middle Jurassic ages of 161 +/- 2, 158 +/- 2 and 163 +/- 1 Ma, which argue for magmatic activity over few millions of years. Zircon crystals are characterized by high but variable Th/U ratios, rare earth element patterns enriched in heavy rare earths, pronounced positive Ce and negative Eu-anomalies consistent with crystallization after substantial plagioclase fractionation. The zircon trace element composition coupled with whole rock chemistry was used to reconstruct the crystallization history of the gabbros. A number of gabbros crystallized in situ, and zircon precipitated from trapped, intercumulus liquid, while other gabbros represent residual liquids that were extracted from a cumulus pile and crystallized along syn-magmatic shear zones. We propose a model in which the emplacement mechanism of gabbroic rocks in ocean-continent transition zones evolves from in situ crystallization to stratified crystallization with efficient extraction of residual liquid along syn-magmatic shear zones. Such an evolution of the crystallization history is probably related to the thermal evolution of the underlying mantle lithosphere.

Are we wasting our talent? Overqualification and overskilling among PhD graduates

Drawing on a very rich data set from a recent cohort of PhD graduates, we examine the correlates and consequences of qualification and skills mismatch. We show that job characteristics such as the economic sector and the main activity at work play a fundamental direct role in explaining the probability of being well matched. However, the effect of academic attributes seems to be mainly indirect, since it disappears once we control for the full set of work characteristics. We detected a significant earnings penalty for those who are both overqualified and overskilled and also showed that being mismatched reduces job satisfaction, especially for those whose skills are underutilized. Overall, the problem of mismatch among PhD graduates is closely related to demand-side constraints of the labor market. Increasing the supply of adequate jobs and broadening the skills PhD students acquire during training should be explored as possible responses.

Clinical chemistry variables in normal elderly and healthy ambulatory populations: comparison with reference values.

Laboratory values of the most commonly assayed clinical chemistry variables were determined in selected elderly and healthy ambulatory populations. The upper and lower limits (2.5 and 97.5 fractiles) were compared with the adult reference values in use in university hospitals of Switzerland. The results suggest that conventional adult reference values can be used for most variables in the elderly and that these values are also useful in an ambulatory population.

Assessment of the water chemistry and the macroinvertebrate community changes produced during the creation of the new Llobregat river mouth (Barcelona, NE Spain)

In 1999, a set of coordinated projects and investments whose principal objective was to transform Barcelona into one of the main distribution points of southern Europe resulted in the relocation of the Llobregat River mouth. The mouth was relocated by draining the old river mouth and constructing a new one. The aim of this study was to characterise the physico-chemical properties and the aquatic macroinvertebrate communities of the new river mouth and to monitor the changes experienced by the estuarine environment during its creation. A sampling point was established in the river 1.8 km upstream from its connection with the new mouth, and two sampling points were established in the new mouth. Samples of water and macroinvertebrates were collected every two months from May 2004 to June 2005, covering the periods before (from May to September 2004) and after (from September 2004 to June 2005) the new mouth was connected to the river and the sea. During the period before its connection to the river and the sea, the new mouth was functionally similar to a lagoon, with clear waters, charophytes and a rich invertebrate community. After the connection was completed, seawater penetrated the river mouth and extended to the connection point with the river (approximately 3.9 km upstream). An increase in conductivity from 4-6 mS cm 1 to 24-30 mS cm 1 caused important changes in the macroinvertebrate community of the new mouth. An initial defaunation was followed by a colonisation of the new mouth by brackish-water and marine invertebrate species. Due to its design (which allows the penetration of the sea) and the decreased discharge from the lower part of the Llobregat River, the new mouth has become an arm of the sea

Why do university graduates regret their study program? A comparison between Spain and the Netherlands

[cat] En aquest article investiguem els factors que porten a universitaris espanyols i holandesos a lamentar els estudis cursats. Espanya i Holanda tenen un sistema educatiu molt diferent en termes de la rigidesa de l’educació secundària i el vincle entre l’educació i el mercat laboral. Comparant Espanya i Holanda ens permet aprendre sobre les conseqüències de dos sistemes educatius molt diferenciats a la probabilitat de lamentar els estudis cursats. Basant-nos en la literatura psicològica sobre l’arrepentiment/lamentació, derivem unes hipòtesis de partida que contrastem empíricament. Els resultats mostren que tant la rigidesa de l’educació secundària com el desajustament entre educació i ocupació són factors importants per explicar la lamentació dels estudis universitaris cursats. L’article conclou amb recomenacions sobre el sistema educatiu universitari.