Search results for " Alloys"
showing 10 items of 1469 documents
Oxidative transformation of aryls using molybdenum pentachloride.
2012
Molybdenum pentachloride combines a strong Lewis acid character with an unusually high oxidation potential creating a powerful reagent for oxidative transformations. Since the oxidative coupling reaction of aryls is induced at an extraordinarily high reaction rate, a variety of labile groups, e.g. iodo, tert-alkyl, etc., are tolerated on the aromatic core. Furthermore, the co-formed molybdenum salts can either be exploited for template effects to obtain uncommon geometries in a preferred manner, or redox-play starts after aqueous workup. Therefore MoCl(5) represents a unique and easily available reagent.
In-situ characterisation of organosilane films formation on aluminium alloys by electrochemical quartz crystal microbalance and in-situ ellipsometry
2005
Abstract Organosilane pre-treatments have been studied intensively during the last years in order to replace hexavalent chromium conversion treatments. The aim of this study is to follow in-situ the formation of this organosilane layer in solution. Two in-situ techniques, spectroscopic ellipsometry and electrochemical quartz crystal microbalance, were used to investigate the mechanism and the kinetics of this protective film formation. In-situ measurements highlight that the organosilane film observed after the drying process is not formed into the solution, but during the emersion and drying step. Hence, it has been possible to characterise the presence of a very thin organosilane layer in…
Structural and Vibrational Study of a New Mixed Dipotassium Hydrogenselenate Dihydrogenphosphate K2(HSeO4)1.5 (H2PO4)0.5.
2006
Abstract Ongoing studies of the KHSeO4–KH2PO4 system, aimed at developing novel proton conducting solids, resulted in the new compound K2(HSeO4)1.5(H2PO4)0.5 (dipotassium hydrogenselenate dihydrogenphosphate). The crystals have been prepared by slow evaporation of an aqueous solution at room temperature. The structural properties of the crystals were characterized by X-ray single analysis (performed at room temperature), which revealed that K2(HSeO4)1.5(H2PO4)0.5 (KHSeP) crystallizes in space group P 1 ¯ with lattice parameters: a = 7.417(3) A, b = 7.668(2) A, c = 7.744(5) A, α = 71.59(3)°, β = 87.71(4)° and γ = 86.04(6)°. The compound has a unit cell volume 416.8(3) A3 and two formula unit…
Comparison of global responses to mild deficiency and excess copper levels in Arabidopsis seedlings
2013
[EN] Copper is an essential micronutrient in higher plants, but it is toxic in excess. The fine adjustments required to fit copper nutritional demands for optimal growth are illustrated by the diverse, severe symptoms resulting from copper deficiency and excess. Here, a differential transcriptomic analysis was done between Arabidopsis thaliana plants suffering from mild copper deficiency and those with a slight copper excess. The effects on the genes encoding cuproproteins or copper homeostasis factors were included in a CuAt database, which was organised to collect additional information and connections to other databases. The categories overrepresented under copper deficiency and copper e…
Recovering bronze metallurgy from archaeological artefacts for the production of reference materials in conservation science
2007
The production of reference Cu-based alloys is the first step of an original experimental protocol to be used in the field of conservation and restoration of metal artefacts. The production of these synthetic alloys has a double value. They can be used both as suitable substitutes of unique archaeological pieces for testing new materials and methods for conservation, and as guidelines for contemporary metal production. We report on a research activity focused on the recovery of the ancient production techniques from the investigation of archaeological copper-based artefacts. The chemical, physical and metallurgical characterization of several Cu-based artefacts, found in different Italian a…
Efficient ultraviolet-light energy dissipation by an aromatic ketone.
2010
Experimental evidence on the efficiency of 2,2'4,4'-tetramethoxybenzil for UV-light energy dissipation is provided. This non-phenolic aromatic ketone has a low energy triplet which quickly decays to the ketone ground state, thus avoiding the generation of undesirable reactive species. El Moncef, Abdelkarim, elmonab@alumni.uv.es ; Cuquerella Alabort, Maria Consuelo, Chelo.Cuquerella@uv.es ; Zaballos Garcia, Elena, Elena.Zaballos@uv.es ; Ramirez de Arellano Sanchez, Maria del Carmen, Carmen.Ramirezdearellano@uv.es ; Stiriba, Salah Eddine, Salah.Stiriba@uv.es ; Perez Prieto, Julia, Julia.Perez@uv.es
On the use of artificial intelligence tools for fracture forecast in cold forming operations
2006
Abstract The design of cold forming processes requires the availability of a procedure able to deal with the prevention of ductile fracture. In fact, the ability to predict fracture represents a powerful tool to improve the production quality in mechanical industry. In this paper, artificial intelligence (AI) techniques are applied to ductile fracture prediction in cold forming operations. The main advantage of the application of AI tools and in particular, of artificial neural networks (ANN), is the possibility to obtain a predictive tool with a wide applicability. The prediction results obtained in this paper fully demonstrate the usefulness of the proposed approach.
An NDC approach to helping pensioners cope with the cost of long-term care
2018
The aim of this paper is to analyse whether it would be possible to provide retirement and long-term care benefits using the same unfunded notional defined contribution scheme. We extend the multi-state overlapping generations model developed by Pla-Porcel et al. (2016) to include two new features: a long-term care benefit graded according to the annuitant's degree of disability and a minimum pension benefit for both contingencies. This brings the model closer to the reality of social insurance and enhances its political attractiveness. The paper contains a numerical example to show how the model functions and focuses especially on the mortality rates for dependent persons, the inception ra…
Structural properties of the quaternary Heusler compound Co2 Cr1−x Fex Al
2006
Abstract The structural and chemical properties of the quaternary Heusler compound Co2 Cr1−x Fex Al were investigated comparing powder and bulk samples. The long range order was determined by means of X-ray diffraction, while the site specific (short range) order was proved by the extended X-ray absorption fine structure method (EXAFS). The chemical composition was analysed by means of X-ray photo emission spectroscopy (XPS) combined with Auger electron spectroscopy (AES) depth profiling. The results from these methods are compared to get a detailed idea about the differences between surface and bulk properties and appearance of disorder in such alloys.
Preparation by radio-frequency magnetron co-sputtering and characterization of thin films of lanthanum–strontium ferromanganites
2005
Abstract (La 0.8 Sr 0.2 )(Mn 1 − y Fe y )O 3 ± δ films with y = 0, 0.2, 0.5, 0.8 and 1, a few hundred nanometers thick, were deposited onto polycrystalline yttria-stabilized zirconia YSZ by a magnetron co-sputtering technique using individual targets of La 0.8 Sr 0.2 MnO 3 and La 0.8 Sr 0.2 FeO 3 . The deposition parameters, substrate temperature and gas pressure, were studied by scanning electron microscopy, energy dispersive X-ray spectrometry, X-ray diffraction and interferential microscopy for their effects on the morphological, chemical, topographic and crystallographic properties of films and YSZ-film interfaces. (La 0.8 Sr 0.2 )(Mn 1 − y Fe y )O 3 ± δ thin films were found to be …