Search results for "Elements"

MODELLING OF WATER-ROCK INTERACTIONS IN CARBONATE AQUIFERS: INSIGHTS FROM A CASE STUDY IN THE MADONIE AREA (SICILY)

2009

Searching the most appropriate sample pretreatment for the elemental analysis of wines by inductively coupled plasma-based techniques.

2008

Different sample preparation methods were evaluated for the simultaneous multielement analysis of wine samples by inductively coupled plasma optical emission spectrometry (ICP-OES) and inductively coupled plasma mass spectrometry (ICP-MS). Microwave-assisted digestion in closed vessel, thermal digestion in open reactor, and direct sample dilution were considered for the determination of Li, Be, Na, Mg, Al, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Sr, Y, Mo, Cd, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Tl, Pb, and Bi in 12 samples of red wine from Valencia and Utiel-Requena protected designation of origin. ICP-MS allows the determination of 17 elements in most…

Assessment of Modelling in Mathematics Examination Papers: Ready-Made Models and Reproductive Mathematising

2013

In the Netherlands modelling is integrated into the mathematics curriculum. This chapter describes a study of modelling characteristics in recent mathematics examination papers. Results show that the tasks convey the message that mathematics can be found in unexpected situations. In many tasks a situation and a ready-made model are given and students are asked to work with the model. For mathematising, two design principles were: to finalise the parameters of a given model, and to reconstruct a given mathematical model from verbal descriptions and diagrams of a situation. These formats were coined as mechanistic and reproductive mathematising respectively. These formats have been introduced…

Virtual reality as a recovering environment - Implications for design principles

2020

In this study, a simulated, VR-based environment was built and analyzed to explore if a VR environment can possess recovering effects. 61 university students tested a VR application depicting a forest and answered survey questions about the experience. The results showed that VR-environment can indeed have recovering effects. Moreover, when comparing to previous studies in real forests, the recovery effects were at similar levels. The study results suggest that as the VR-based environments can possess recovery effects, they can work as recovery environments at schools or similar environments. The study results offer implications for the designers and propose design principles to build recov…

YREE determination in seawater. Standardization and validation of a new method based on preconcentration techniques

2010

The most interesting attraction of using rare-earth elements and yttrium (YREE) to address geochemical and marine chemical problems consists of their chemical coherence as group of trace elements. These characters allow YREE compositions of rocks and minerals to be extensively used in studies of provenance, petrogenesis and chemical evolution of the geological materials (1). Similarly, YREE compositions in the hydrosphere were used in studies of coagulation, particle-solution reactions and oceanic circulation of water masses (2-4). Unfortunately, very low concentrations of YREE (ng l-1 or sub-ng l-1) associated to high ionic strength of seawater always represented the main difficulty to ana…

A Neandertal dietary conundrum: Insights provided by tooth enamel Zn isotopes from Gabasa, Spain

2022

The characterization of Neandertals’ diets has mostly relied on nitrogen isotope analyses of bone and tooth collagen. However, few nitrogen isotope data have been recovered from bones or teeth from Iberia due to poor collagen preservation at Paleolithic sites in the region. Zinc isotopes have been shown to be a reliable method for reconstructing trophic levels in the absence of organic matter preservation. Here, we present the results of zinc (Zn), strontium (Sr), carbon (C), and oxygen (O) isotope and trace element ratio analysis measured in dental enamel on a Pleistocene food web in Gabasa, Spain, to characterize the diet and ecology of a Middle Paleolithic Neandertal individual. Based on…

Effets à long terme de l'apport répété de déchets organiques sur l'évolution de la matière organique et des éléments trace métalliques dans un sol sa…

2002

The distribution of trace metal elements (ETM) in soils depends on physico-chemical characteristics of the soil (pH, redox potential …) and does not remain fixed during time. The objective of this work was to study the long-term effects of the organic waste applications (sewage sludge and manure) on the evolution of the ETM and the organic matter in a cultivated soil. This study was made on the acid sandy soil of the experimental site of Ambarès (Gironde) set up in 1974 by the INRA of Bordeaux. During 20 years, this soil, cultivated in maize, received various organic applications (manure 10 t ha-1 year-1, sludges 10 t ha-1 year-1 and sludges 100 t ha-1 year-1), which stopped in 1993. This s…

Interconnecteurs métalliques de piles à combustible de type SOFC - Résistance à la corrosion et conductivité électrique à haute température

2009

The need of interconnect to connect individual cells into electrical series in a SOFC stack appears as one of the most important point in fuel cell technology. The main important criteria requires for interconnect is an excellent oxidation resistance in air and in H2/H2O. The goal of this study is to determine the influence on corrosion behaviour of a reactive element oxide coating (La2O3, Y2O3) realized by MOCVD on different metallic alloys like Crofer22APU, Haynes230 and Fe30Cr. The realisation of long ageing (7 700 and 15 400 hours) proved to be insightful. The corrosion kinetic experiments, the oxide scale characterisation and ASR measurements established that the presence of perovskite…

Networks of Seed Storage Protein Regulation in Cereals and Legumes at the Dawn of the Omics Era

2012

BAP GEAPSI CT2 (BAP); International audience; Finely regulated and orchestrated events occur during seed development and germination in different cell organelles (mitochondria, peroxisomes, plastids, vacuoles, endoplasmic reticulum, oil bodies and nuclei). Therefore, some of the ongoing investigations pass through sub-cellular organelle purifications for a deeper comprehension of these complex developmental processes. In seed biology, recent ambitious efforts in proteomics have been directed toward organelle isolation from seeds and high-throughput protein separation and identification by mass spectrometry at defined developmental stages. The construction of reference maps allowed identifyi…

Trait distribution within winter wheat fields can partly be explained by disturbances and competition for resources

2013

International audience; Weed species are not homogeneously distributed into field elements (Cordeau et al. 2012)*.In a field, weed species are mainly competing with the crop and constrained by management practice (i.e.disturbances). In the crop edge, less unfavorable conditions for weed development (i.e.absence of direct crop competition,l ess frequent disturbances could explain the greater diversity of weeds.To understand this observation, a functional approach base dont raits known to respond both to disturbances and to competitive or facilitative interactions can be used.Our assumptions are that(i)the crop edge is likely to all owawi derrange of ecological strategies thus promoting speci…