Search results for " metal"

On the high-pressure phase stability and elastic properties ofβ-titanium alloys

2017

We have studied the compressibility and stability of different β-titanium alloys at high pressure, including binary Ti–Mo, Ti–24Nb–4Zr–8Sn (Ti2448) and Ti–36Nb–2Ta–0.3O (gum metal). We observed stability of the β phase in these alloys to 40 GPa, well into the ω phase region in the P–T diagram of pure titanium. Gum metal was pressurised above 70 GPa and forms a phase with a crystal structure similar to the η phase of pure Ti. The bulk moduli determined for the different alloys range from 97  ±  3 GPa (Ti2448) to 124  ±  6 GPa (Ti–16.8Mo–0.13O).

Détecteurs de métaux, le cas français

2011

Overview of the illegal use of metal detectors in France; Panorama de l'utilisation illégale des détecteurs à métaux en France

Polimeryzacja koordynacyjna alkenylosilseskwioksanów i ich kopolimeryzacja z olefinami lub styrenem

2015

Artykuł stanowi kontynuację przeglądu literatury dotyczącej koordynacyjnej polimeryzacji silseskwioksanów (POSS), zawierających zdolne do polimeryzacji wiązanie podwójne, oraz ich kopolimeryzacji głównie zolefinami, a także ze styrenem. Zastosowanie katalizatorów metalocenowych aktywowanych metyloaluminoksanem (MAO) zapewnia efektywną (ko)polimeryzację silseskwioksanów zarówno z olefinami, jak i styrenem. Wprowadzenie do materiału polimerowego komonomeru POSS korzystnie wpływa na właściwości otrzymanych produktów, które cechują się większą odpornością termiczną oraz wytrzymałością mechaniczną niż ich odpowiedniki niezawierające POSS.

Amphoteric, prevailingly cationic L-arginine polymers of poly(amidoamino acid) structure: Synthesis, acid/base properties and preliminary cytocompati…

2013

A linear amphoteric poly(amidoamino acid), L-ARGO7, is prepared by Michael-type polyaddition of L-arginine with N,N′-methylenebisacrylamide. Chain-extension of acrylamide end-capped L-ARGO7 oligomers with piperazine leads to high-molecular-weight copolymers in which L-arginine maintains its absolute configuration. Acid/base properties of L-ARGO7 polymers show isolectric points of ≈10 and positive net average charges per repeating unit at pH = 7.4 from 0.25 to 0.40. These arginine-rich synthetic polymers possibly share some of the unique biological properties of polyarginine cell-permeating peptides. In vitro tests with mouse embryo fibroblasts balb/3T3 clone A31 show that L-ARGO7 polymers a…

Hetero-difunctional dimers as building blocks for the synthesis of poly(amidoamine)s with hetero-difunctional chain terminals and their derivatives

2012

This article reports on a simple and straightforward preparation method of poly(amidoamine)s (PAAs) with hetero-difunctional chain ends as well as of several up to now hardly obtainable PAA derivatives of biotechnological interest, such as for instance PAAs of controlled molecular weight and narrow polydispersity mono-functionalized at one end with an acrylamide group, PAAs with star-like molecular architecture, graft-PAA-protein conjugates, “tadpole-like” PAA conjugates with hydrophobic moieties able to self assemble into nanoparticles in aqueous media. The key step was to design suitable building blocks consisting of hetero-difunctional dimers (HDDs). In particular, the HDDs considered we…

Transition metal complexes of tetradentate and bidentate Schiff bases as catalysts for ethylene polymerization: Effect of transition metal and cocata…

2009

This article compares catalytic performance of ethylene polymerization in similar polymerization conditions of transition metal complexes having two ligands [O,N] (phenoxy-imine) and having one tetradentate ligand [O,N,N,O] (salphen or salen). It is shown that the activity of both complex types as well as the product properties depend in the same way on the type of central metal in the complex and on the cocatalyst used. Although the type of ligand has some effect on the catalyst activity, yet it does not control the properties of the obtained products. The vanadium and zirconium complexes, irrespective of the cocatalyst used, yield linear polyethylene with high molecular weight (a few hund…

Complex formation of copper(II) and cadmium(II) with pectin and polygalacturonic acid in aqueous solution. An ISE-H + and ISE-Me 2+ electrochemical s…

2012

The acid-base properties of pectin and its ability to complex with copper(II) or cadmium(II) were quantitatively determined in order to define the ability of this natural polyelectrolyte to sequester metal ions. Potentiometric measurements carried out at different ionic strengths (0.1 - 0.7 mol L-1, in Na+ ionic medium) allowed us to define the acid-base properties of pectin together with the dependence of the protonation constants on ionic strength and to calculate the protonation constant at infinite dilution. The formation of complex species between pectin and copper(II) or cadmium(II) was investigated potentiometrically (using H+, Cu2+ and Cd2+ Ion Selective Electrodes, ISEs) in NaNO3 a…

Spontaneous urban weeds: a resource against environmental pollution

2022

Quality of the environment and social well-being, both at a collective and individual level, are closely interrelated issues. It is, in fact, a relationship that invests values of primary importance, such as those relating to human health and safety, heritage and resources to be passed on to future generations. Plant growth and survival can be challenged by harsh urban conditions. Many studies show the persistence of endemic species in built-up areas and document the ecosystem services provided. With this research we wanted to investigate the bioaccumulation of heavy metals such as cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), arsenic (As), molibden (Mo), cadmium (Cd), lead (Pb) and mer…

Influence of the microstructure on the durability of hard coatings obtained from metal powders

2016

Influence of the process parameters on the microstructure of a hardfacing coating elaborated by hot isostatic pressing

2019

Hot Isostatic Pressing elaboration of Norem02, an austenitic-ferritic hypereutectoid stainless steel, leads to the formation ofan austenitic matrix with a mixture of acicular M7C 3 and globular M23 C 6 carbides. The sintering tests, carried out by using an AISI304L container, showed that the final microstructure and the carbides’ distribution of the HIPed Norem02 are strongly influencedby the process parameters (heating and cooling rate, sintering time, holding temperature and pressure) and by the particles’ size,microstructure and phase distribution of the initial powder. The morphological, crystallographic and chemical analysis of the sinteredsamples were completed by comprehension of the…