Search results for "melting"

Environmental impact of early Basque mining and smelting recorded in a high ash minerogenic peat deposit.

2004

International audience; More than four metres of core, covering almost 5000 years of deposition, were collected in a high ash minerogenic peat deposit located in the High Aldudes valley (Basque country), an area well known for its mineral abundance, exploited from Roman Times at least.Although minerogenic peatlands are not generally considered as the best archives to reconstruct past atmospheric metal deposition history, lead isotopic geochemistry demonstrates the integrity of the Pb record at least within the three upper meters; that is to say over the last four millennia.Zn, Cd and Cumay have been widely redistributed either by biological cycling, advective groundwater movements, or diffu…

The contamination legacy of a decommissioned iron smelter in the Italian Alps

2018

The economically important activity of metal processing can tend to contribute to the degradation of the environment. Smelting is an important source of contaminants, dispersing large quantities of potentially toxic elements (PTE) and coproducts into the environment. Soils in the vicinity of smelters frequently contain high concentrations of PTE. In terms of the quantities processed, the major PTE are iron (Fe), aluminium (Al), copper (Cu), lead (Pb), manganese (Mn), and zinc (Zn); of these Cu, Pb and Zn are, potentially, highly hazardous elements. The general problem addressed by this study is to determine if the PTE concentration in the soils of an area downwind from a decommissioned iron…

Über die synthese von gewinkelten oligophenylenen höheren kondensationsgrades. 17. Mitteilung

1965

Es wird uber die Synthese von methylsubstituierten, ein- und zweifach m-gewinkelten Oligophenylenen bis zum Kondensationsgrad 14 berichtet. Durch Anwendung chromatographischer Methoden konnten die Verbindungen rein isoliert werden. Gewinkelte Oligophenylene besitzen bei vergleichbarer Struktur einen niedrigeren Schmelzpunkt und eine bessere Loslichkeit als p-Oligophenylene. The synthesis of methyl-substituted oligophenylenes with one or two meta-bonds up to a polymerisation degree of 14 is described. By application of chromatographic methods these compounds could be isolated free of impurities and homolog products. Angled oligophenylenes possess a lower melting point and a higher solubility…

Synthesis and Sequential Deprotection of Triblock Copolypept(o)ides Using Orthogonal Protective Group Chemistry

2014

The synthesis of triblock copolymers based on polysarcosine, poly-N-ε-t-butyloxycarbonyl-l-lysine, and poly-N-ε-t-trifluoroacetyl-l-lysine by ring-opening polymerization of the corresponding α-amino acid N-carboxyanhydrides (NCAs) is described. For the synthesis of N-ε-t-butyloxycarbonyl-l-lysine (lysine(Boc)) NCAs, an acid-free method using trimethylsilylchloride/triethylamine as hydrochloric acid (HCl) scavengers is presented. This approach enables the synthesis of lysine(Boc) NCA of high purity (melting point 138.3 °C) in high yields. For triblock copolypept(o)ides, the degree of polymerization (Xn ) of the polysarcosine block is varied between 200 and 600; poly-N-ε-t-butyloxycarbonyl-l-…

Single tube optimisation of APOE genotyping based on melting curve analysis

2008

Objectives: To develop and validate a single-tube protocol for APOE genotyping using fluorescent probes. Design and methods: We have designed and validated a hybrid, single-tube, SimpleProbe/FRET probe protocol that takes advantage of the different probe wavelength emissions. Results: Our method offers high quality outcomes, minimum interferences between probe signals and is 100% concordant with the reference protocol. Conclusions: This method is cheaper, faster and more reliable and versatile than other alternatives proposed. © 2008 Elsevier Inc. All rights reserved.

Renforcement de la résistance à la corrosion localisée de l’acier inoxydable 304L grâce au traitement de surface par laser impulsionnel

2013

L’acier inoxydable 304L est utilise dans de nombreux domaines. Cependant, il peut, dans certaines conditions, etre sensible a la corrosion par piquration. Dans cette etude, nous nous sommes interesses aux potentialites du traitement de fusion superficielle par laser nanopulse pour l’amelioration de la resistance a la corrosion de cet acier. Ce traitement consiste a focaliser un faisceau laser sur la surface du materiau, provoquant sa fusion quasi instantanee sur quelques microns, immediatement suivie d’un refroidissement ultra-rapide allant jusqu’a 1011 K/s. Les parametres laser impliquent des modifications des proprietes physico-chimiques. Nous avons notamment etudie l’influence du recouvr…

Coarse Graining of Short Polythylene Chains for Studying Polymer Crystallization.

2015

We derive coarse-grained models of polyethylene in the melt state with the aim to study polymer crystallization. This requires a low level of coarse-graining:  We use a mapping of two CH2 groups onto one bead. The coarse-grained beads are connected with harmonic springs, an optimized angular potential, and an optional torsional potential. Coarse-grained potentials are derived from detailed all-atom simulations, and an optimized form of the force field is then derived which achieves a good accuracy in reproducing the static properties of the chains. We address the question over which temperature range such models can be used, and in particular if the model is capable of reproducing the phase…

Postharvest quality and sensory attributes of ‘pesca di bivona’ peaches (Prunus persica L.) during storage

2017

“Pesca di Bivona” ‘Murtiddara’, ‘Bianca’, ‘Agostina’, and ‘Settembrina’ are non-melting white flesh peach landraces characterized by a persistent aroma and excellent flavour highly appreciated by Italian consumers. The aim of this work was to assess the persistence of their quality and sensory profiles after storage at 0 °C for 28 days, using destructive and non-destructive analyses. The IAD index, measured either at harvest or at fruit removal from cold storage, was correlated to TSS, TA and firmness of all the landraces. ‘Settembrina’ and ‘Agostina’ harvested at the right ripening time (50.5 ± 4.3 N) and stored at 0 °C during 4 weeks kept harvest quality in terms of sensorial attributes, …

Aryldimethylsilyl Modified Hypersilanes

2008

Aryldimethylsilyl-substituted hypersilanes ArSiMe2Hyp [Hyp =Si(SiMe3)3; Ar = Mes (3a), Bph (3b), Mph (3c), Pph (3d), Tph (3e); Dpp (3f); with Mes = 2,4,6-Me3C6H2, Bph = 2-PhC6H4, Mph = 2-MesC6H4, Pph = 2′,3′,4′,5′,6′-pentamethylbiphenyl2-yl, Tph = 2′,4′,6′-triisopropylbiphenyl-2-yl and Dpp = 2,6-Ph2C6H3] have been synthesized by a multi-step reaction starting from the readily available starting materials ArI and (thf)xKHyp. For this purpose the aryl iodides were first converted into the lithium aryls by lithium-halogen exchange with n-butyl lithium. A salt-metathesis reaction with SiMe2Cl2 gave the corresponding arylchlorodimethylsilanes (2a–e) in excellent yields. Finally, reaction of 2a–e…

1985

From the break-down in the viscosity and from the increase of the intensity of the scattered light, associated with the entrance into the two-phase region, the pressure dependence of the demixing temperature of solutions of PVC 37 000, PVC 75 000 and PVC 100 000 in phenetole and PVC 75 000 in o-xylene was measured up to 1 000 bar. (The numbers in the codes of the PVC specimens are their approximate molecular weights.) The application of pressure increases the demixing temperatures of PVC in both solvents by about 1 K/100 bar. For a qualitative forecast of the pressure effects, the solubility parameter theory in combination with the corresponding states principle, and an empirical correlatio…