Trace Elements

En formation, quel qu’en soit le niveau, l’autoévaluation est une pratique qui a fait ses preuves
(Allal, 2004; Campanale, 2007; Vial, 2000). Parfois pratiquée seule (autoévaluation stricto
sensu), entre apprenants (évaluation mutuelle) ou en comparaison avec le regard d’un expert
ou d’un formateur (co-évaluation), elle représente un moyen efficace de prise de recul, de
distanciation et de décentration (Campanale, 1997), des mouvements source de cette prise
de conscience nécessaire au changement et donc à l’apprentissage. St-Pierre (2004)
considère que l’autoévaluation est une habileté et qu’elle peut s’enseigner comme une
discipline.
Notre société se numérise très rapidement, et cette révolution apporte naturellement son lot
de changements dans nos manières de travailler : accessibilité facilitée à l’information, travail
collaboratif à distance synchrone ou non, sauvegarde et partage d’informations et de
matériaux multimédia, nouveaux modes de production et d’innovation, récolte automatique
d’informations sur les utilisateurs et sur leurs pratiques… Ces dimensions ouvrent de
nouvelles possibilités dans le domaine de l’autoévaluation. Que l’on pense à la récolte de
traces numériques d’apprentissage, qu’elles soient convoquées ou provoquées (Peraya et al.
2009), pour alimenter un portfolio, à l’auto-confrontation par vidéoscopie, à l’analyse des
traces d’utilisation des navigateurs ou des LMS (learning management system)… force est de
constater que les ingénieries de formation utilisent ces données numériques pour soutenir
l’autoévaluation des apprentissages. Mais les traces récoltées sont d’origines et de natures
très diverses.
Les contributions constitutives de ce symposium s’intéresseront ainsi à la nature et à l’origine
des traces numériques utilisées dans des dispositifs de formation à des fins d’autoévaluation.
Elles analyseront leur impact sur les apprentissages des apprenants, se demandant si les
différentes traces soutiennent plus efficacement une forme de normalisation ou de
développement et si elles peuvent être liées à différentes formes et fonctions de l’évaluation.

There is accumulating evidence that the metabolism of several trace elements is altered in diabetes mellitus and that these nutrients might have specific roles in the pathogenesis and progress of this disease. The aim of present study was to compare the level of essential ...

Constant current potentiometry was used for nickel and cobalt determination in water. All parameters like deposition potential and time, buffer and DMG concentration, and current density which have an influence on the determination sensitivity were optimized (deposition potential: −0.5 V vs. Ag/AgCl (sat KCl); buffer concentration 0.01 mol/l, pH 9.3; DMG concentration 0.05 mmol/l and deposition time 10 s, current: -15 μA). No significant differences of the determination sensitivity between cathodic stripping voltammetry and constant current potentiometry were found. The latter method is advantageous for automatization.

In this study, twenty one (21) trace elements in the basement complex groundwater of Blantyre district, Malawi were analyzed. The majority of the analyzed trace elements in the water were within the standards set by World Health Organization (WHO) and Malawi Standards Board (MSB). But, iron (Fe) (BH16 and 21), manganese (Mn) (BH01) and selenium (Se) (BH02, 13, 18, 19 and 20) were higher than the WHO and MSB standards. Factor analysis (FA) revealed up to five significant factors which accounted for 87.4% of the variance. Factor 1, 2 and 3 suggest evaporite dissolution and silicate weathering processes while the fourth factor may explain carbonate dissolution and pH influence on trace element geochemistry of the studied groundwater samples. According to PHREEQC computed saturation indices, dissolution, precipitation and rock-water-interaction control the levels of trace elements in this aquifer. Elevated concentrations of Fe, Mn and Se in certain boreholes are due to the geology of the aquifer and probable redox status of groundwater. From PHREEQC speciation results, variations in trace element species were observed. Based on this study, boreholes need constant monitoring and assessment for human consumption to avoid health related issues.

We measured rare earth element (REE) concentrations in river waters to characterize the suspended and dissolved river flux of the REE to the oceans. The REE pattern of river suspended materials is sensitive to drainage basin geology. A positive correlation is observed between La/Yb ratios and Nd model ages for the rivers studied. Major rivers have light REE enriched patterns relative to the North American Shale Composite (NASC), with (La/Yb)N = 1.6−2.7. River water dissolved material ( < 0.2 μm) is heavy REE enriched relative to suspended material, and the most pronounced negative Ce anomalies occur in rivers of high pH. Light REE concentrations vary by approximately 3 orders of magnitude and are inversely related to pH and major cation concentrations.From these data, we estimate that typical major river runoff has heavy REE depleted suspended material with (La/Yb)N ≈ 1.9. We conclude that the terrigenous input to the oceans from major rivers is heavy REE depleted relative to shales. From the available data, average river water dissolved material appears to be heavy REE enriched with (La/Yb)N ≈ 0.4. Estuarine removal processes lower the dissolved REE river flux by approximately 60% and result in a flux that is more heavy REE enriched with (La/Yb)N ≈ 0.2. Calculated oceanic residence times with respect to river input range from 2300 to 21,000 years, are shortest for Ce, and greatest for the heavy REE and La. Such long residence times may suggest the presence of additional sources of REE in seawater.

Current trends in transport electrification and mobile technologies have created an increasing demand for raw materials needed for battery production. The supply chains involved are global, complex, non-transparent and sometimes associated with unsustainable production practices. To improve on the current situation, it is essential to trace battery raw materials back to their origins to verify the conditions in which they were produced. This demand for increased transparency has triggered actions in European Union legislation and among companies operating within battery supply chains.

In this report, we review the current landscape for the application of traceability methods to battery supply chains. The report begins with a global overview of selected battery metals and minerals and their related sustainability issues. As sustainability is an integral goal for traceability, sustainability reporting systems for mining are reviewed from the perspective of traceability. Existing traceability methods and case studies in battery supply chains are reviewed, including the geo-based fingerprinting method (laboratory technology) that is being developed in the BATTRACE research project. We also discuss the business potential of the geo-based fingerprinting method.

Several drivers are identified for traceability. The main driver comes from regulatory development, such as the EU’s battery directives. Customer awareness of sustainability issues is also beginning to influence manufacturers (OEMs) to invest in the transparency of their battery metal supply chains. In addition, the producers of sustainable and low emission raw materials have identified the commercial benefit of tracing the greenhouse gas emissions of their products along the supply chain. Current sustainability and reporting systems used within the mining industry are inadequate to comply with the increased traceability needs, as their focus is limited to the beginning of the supply chain.

The traceability pilots that are currently in use are still limited in scope. For traceability to become commonplace in mining supply chains, OEMs will need to recognize the overall commercial benefits of traceability. Ethical questions dominate in the sustainability considerations on cobalt production, and there are indications that the cobalt market may be separating into traceable and certified cobalt, and bulk cobalt. For lithium and graphite production, the dominating sustainability considerations relate to water and energy consumption and dust. Lithium and graphite are not currently communicated to be included in any digital traceability solution under preparation, but they have been included in BATTRACE research for the geo-based fingerprinting method. Geo-based fingerprinting has considerable commercial potential as a traceability method and a verification tool. As the geological and elemental characteristics of a sample cannot be falsified, the method has unique potential as a stand-alone traceability technology, or as a complementary verification method with any other traceability system. The method could also serve as a verification tool in the “Metals from Finland” certificate, which could sharpen the marketing of sustainable and traceable battery metals production from Finland.

The assessment of groundwater is essential for the estimation of suitability of water for safe use. An attempt has been made to study the groundwater of selected areas of Punjab (Sheikhupura & Sahiwal) and Sindh (Sindh, Jawar Dharki and Dharki), Pakistan. The results indicate that pH, color and odor were all within limits of WHO that is pH ranges 6.5–8.5, colorless and odorless, respectively. The high values of suspended solids were observed in the Sindh-1 and Dharki samples. Microbiologically only Sahiwal and Jawar Dharki were found fit for drinking purpose. Trace metals analysis of Sheikhupura-1 and Sindh-1 showed that values do not fall within limits of WHO for Iron. The ionic concentration analysis showed that high bicarbonate (HCO3-), ions are present in the samples of Sahiwal and Dharki; Sindh-1 and Jawar Dharki samples showed very high concentration for chloride ions, all samples were satisfactory level for sulphate (SO42-), sodium, magnesium and phosphate ions except samples of Sindh-1 and Jawar Dharki. High concentration of calcium and potassium ions was observed in samples of Sindh-1, while all other samples were found fit for drinking purposes in respect of nitrate, nitrite and ammonium ions. The high concentration of Fluoride was found only in Sheikhupura-2 samples.

Determining the diet of an extinct species is paramount in any attempt to reconstruct its paleoecology. Because the distribution and mechanical properties of food items may impact postcranial, cranial, mandibular, and dental morphologies related to their procurement, ingestion, and mastication, these anatomical attributes have been studied intensively. However, while mechanical environments influence skeletal and dental features, it is not clear to what extent they dictate particular morphologies. Although biomechanical explanations have been widely applied to extinct hominins in attempts to retrodict dietary proclivities, morphology may say as much about what they were capable of eating, and perhaps more about phylogenetic history, than about the nature of the diet. Anatomical attributes may establish boundary limits, but direct evidence left by the foods that were actually (rather than hypothetically) consumed is required to reconstruct diet. Dental microwear and the stable light isotope chemistry of tooth enamel provide such evidence, and are especially powerful when used in tandem. We review the foundations for microwear and biogeochemistry in diet reconstruction, and discuss this evidence for six early hominin species (Ardipithecus ramidus, Australopithecus anamensis, Au. afarensis, Au. africanus, Paranthropus robustus, and P. boisei). The dietary signals derived from microwear and isotope chemistry are sometimes at odds with inferences from biomechanical approaches, a potentially disquieting conundrum that is particularly evident for several species. Am J Phys Anthropol 148:285–317, 2012. © 2012 Wiley Periodicals, Inc.

Despite the widespread occurrence of chromium toxicity, its molecular mechanism is poorly documented in plants compared to other heavy metals. To investigate the molecular mechanisms that regulate the response of Miscanthus sinensis roots to elevated level of chromium, seedlings were grown for 4 weeks and exposed to potassium dichromate for 3 days. Physiological, biochemical and proteomic changes in roots were investigated. Lipid peroxidation and H2O2 content in roots were significantly increased. Protein profiles analyzed by two-dimensional gel electrophoresis revealed that 36 protein spots were differentially expressed in chromium-treated root samples. Of these, 13 protein spots were up-regulated, 21 protein spots were down-regulated and 2 spots were newly induced. These differentially displayed proteins were identified by MALDI-TOF and MALDI-TOF/TOF mass spectrometry. The identified proteins included known heavy metal-inducible proteins such as carbohydrate and nitrogen metabolism, molecular chaperone proteins and novel proteins such as inositol monophosphatase, nitrate reductase, adenine phosphoribosyl transferase, formate dehydrogenase and a putative dihydrolipoamide dehydrogenase that were not known previously as chromium-responsive. Taken together, these results suggest that Cr toxicity is linked to heavy metal tolerance and senescence pathways, and associated with altered vacuole sequestration, nitrogen metabolism and lipid peroxidation in Miscanthus roots.► Molecular mechanism of chromium toxicity response is poorly documented in plants. ► Miscanthus sinensis is relatively heavy metal tolerant biomass crop. ► Proteomic analysis was done in M. sinensis root under Cr stress for the first time. ► Several novel Cr-induced proteins were identified along with other known proteins.

For the first time the abundances (the average concentrations) of chemical elements are given for the soils of urban landscapes. The figures were established by authors on the base of average concentrations of chemical elements in the soils of more than 300 cities and settlements in Europe, Asia, Africa, Australia, and America. The major part of data (sampling, analyses and their statistical treatment) was obtained directly by authors as a result of special studies conducted for more than 15 years. The concentrations of elements were defined by the spectral, gravimetric, neutron activation and the X-ray fluorescence methods of analyses. The control of sampling and also inner and outer laboratory controls of analyses were carried out. The ordinary and the control analyses were carried out in the certified and accredited laboratories, including arbitration laboratory. The sufficiently numerous published materials of different researchers were also used.

Elemental composition of ten samples of instant and roasted ground coffee powders available in markets of India have been analyzed using X-ray fluorescence technique. The samples were analyzed for thirty one elements, out of which major elements were K and Ca. Al, Fe, Ni, Mg, Mn, Sb, Sn and Zn were observed to be present in the smaller quantities. Nonmetals such as S, P and Si were detected in almost all the samples. The samples also showed presence of rare earth metals like W, Zr, Y, Ag, Sr, Rb, Nb and Mo. Toxic metals like Hg and As were not detected in any of the samples, while traces of Cd and Pb were found to be present in four samples each. With the absence of toxic elements coffee can be considered a safe beverage. Detection of radioactive elements U and Th in the coffee samples is an important finding of this research work. Results of elemental analysis of the analyzed coffee samples were correlated to the soil analysis data of their geographical origins. There have been good correlations between elements reported in the soil and those detected in the coffee samples. The motive of the research work is to bring out the goodness of coffee in terms of their elemental composition and also their variation with regard to their geographical origin.

Trace element analysis in biological samples has improved significantly over the last 40 years. Improvements in instrumentation such as inductively coupled plasma-mass spectrometry and microwave digestion have resulted in improved precision, accuracy, reliability, and detection limits. The analysis of human scalp hair has benefited significantly from these improvements. A recent article in the Journal of the American Medical Association found significant inter-laboratory variation amongst several laboratories performing trace metal hair testing. It concluded that standardization was necessary to improve inter-laboratory comparability, and an accompanying commentary described the characteristics of a laboratory that should be used in performing hair analysis. The objective of this study is to demonstrate that good laboratory practices will generate precise, accurate, and reliable results. A method for establishing reference ranges and specific data on an analytical method will also b...