Search results for " metal"

Impact of heavy metals on soil microflora

2006

Copper binding capacity of root exudates of cultivated plants and associated weeds

2001

International audience; Cu binding to root exudates of two cultivated plants, wheat (Triticum aestivum) and rape (Brassica napus), and two weeds associated with wheat, dog daisy (Matricaria inodora) and cornflower (Centaurea cyanus), was studied in vitro under hydroponic and sterile conditions. Nutrient solutions were prepared with or without P. A MetPLATE microbiological test was used to assess the metal complexing capacity of root exudates. In the P-deficient solutions, no exudation was observed for any of the four plants; consequently, no Cu binding occurred. When P was present in the nutrient solutions, the plant exudates displayed differing abilities to complex Cu. No difference was de…

Cinq millénaires de métallurgie en montagne basque. Les apports d'une démarche intégrée alliant palynologie et géochimie isotopique du plomb

2001

Five thousand years of metallurgy in the basque mountains : the contributions of an integrated process mixing palynology and the isotopic chemistry of lead. An interdisciplinary research combining palyno- logy and lead isotopic geochemistry was performed in a peat bog of the Basque Country, in an area recognized as being an old metallurgical centre. These various analyses make it possible to reconstitute mining and metallurgical activities and to appreciate the impact on forest during last five millennia. Several phases are attested between late Neolithic and modern times (Middle Bronze age, Late Bronze age, Antiquity and finally modern time). Most of these phases are clearly related to for…

Phytoextractors of metal(loid)s of the Italian flora: An Outline

Intensive farming, wastewater irrigation, mining, heavy industry, smelting procedures and improper waste disposal are some of the human activities that contribute to heavy metal soil contamination (Sharma et al. 2007; Khan et al. 2008; Yu et al. 2008). As heavy metals cannot be degraded by microorganisms and tend to remain in polluted sites for long periods of time, soil contamination by heavy metals represents a particular environmental concern and a serious threat to human health. Conventional soil remediation techniques, such as soil washing, excavation, in situ vitrification, solidification and stabilization, can be effectively employed in order to achieve remediation of heavy metal con…

Acid−Base Properties of Synthetic and Natural Polyelectrolytes: Experimental Results and Models for the Dependence on Different Aqueous Media

2008

Protonation constants of several natural and synthetic humates and fulvates were determined by ISE-H+ potentiometry in different ionic media (alkali metal halides and tetraethylammonium iodide) at different ionic strengths and T ) 298.15 K. Experimental data obtained in previous studies of different synthetic (polyacrylates, polymethacrylates, polyacrylate-co-maleate) and naturally occurring (alginate, humic substances) polycarboxylates were also taken into account in the general analysis of acid-base properties of polyelectrolytes. Protonation constants were expressed as a function of the dissociation degree (R) using three models, namely, a simple linear model, the Ho¨gfeldt three-paramet…

Activin a and matrix metalloproteinase-2 and -9 blood levels as gauges of bone metastatic spread. In: Tumor microenvironment:Heterotypic interactions.

2006

Development of Removable Visual Impact Indicator or Polymer Composite Materials

2021

The prototype of removable visual impact indicator for thermoset polymer composite materials is developed, and its characteristics are experimentally determined. The indicator is a fabric tape glued by epoxy to the surface of the polymer composite. The tape is impregnated with a composition that provides a visual response at the place of an impact on the composite surface. Ball-drop tests demonstrated the increase of the magnitude of the visual response with the impact energy at different substrate hardnesses. The shelf-life and mode of the tape storage until commissioning are determined. Peel tests showed the ability to remove a used indicator without damaging the surface of the composite.

Pull-off adhesion of hybrid glass-steel adhesive joints in salt fog environment

2016

The aim of this paper was to evaluate the durability behaviour of glass/steel adhesive joints exposed to salt fog environmental conditions for ten weeks, according to ASTM B117 standard. To this scope, pull-off mechanical tests were carried out in order to evaluate the performances evolution and damage phenomena of the adhesive joints during the ageing exposition. Two different types of adhesives were compared (i.e. epoxy and polyurethane ones). Moreover, the effects of the glass surface condition and the presence of a basalt mat layer within the adhesive thickness were evaluated. The mechanical performances were related with the occurred failure mechanisms. Epoxy-based joints showed higher…

Test MetAphAs. Avaliação Metalinguística de Afasia

2021

Test MetAphAs. Avaliação Metalinguística de Afasia (Rosell-Clari & Hernández-Sacristán, 2021) es una versión adaptada al portugués brasileño y abreviada de Rosell Clari & Hernández Sacristán, 2014). Esta prueba fue desarrollada inicialmente para evaluar las habilidades metalingüísticas naturales en personas con afasia (Hernández-Sacristán, Rosell-Clari, Serra-Alegre y Quiles-Climent, 2012). Las habilidades metalingüísticas naturales se refieren al uso del lenguaje que revela reflexividad (Hockett, 1960); es decir, la distancia perceptiva del hablante con respecto a su propio comportamiento verbal (Werner & Kaplan, 1978). Esta autoconciencia del lenguaje nos permite monitorear nuestros propi…

Magnetic hysteresis up to 80 kelvin in a dysprosium metallocene single-molecule magnet

2018

Breaking through the nitrogen ceiling Single-molecule magnets could prove useful in miniaturizing a wide variety of devices. However, their application has been severely hindered by the need to cool them to extremely low temperature using liquid helium. Guo et al. now report a dysprosium compound that manifests magnetic hysteresis at temperatures up to 80 kelvin. The principles applied to tuning the ligands in this complex could point the way toward future architectures with even higher temperature performance. Science , this issue p. 1400