Search results for "visual_art"
showing 10 items of 2987 documents
Normal metal - insulator - superconductor thermometers and coolers with titanium-gold bilayer as the normal metal
2018
We have fabricated superconductor - insulator - normal metal - insulator - superconductor (SINIS) tunnel junctions in which Al acts as the superconductor, AlOx is the insulator, and the normal metal consists of a thin Ti layer (5 nm) covered with a thicker Au layer (40 nm). We have characterized the junctions by measuring their current-voltage curves between 60 mK and 750 mK. For comparison, the same measurements have been performed for a SINIS junction pair whose normal metal is Cu. The Ti-Au bilayer decreases the SINIS tunneling resistance by an order of magnitude compared to junctions where Cu is used as normal metal, made with the same oxidation parameters. The Ti-Au devices are much mo…
Flexural properties of the epoxy resin filled with single and hybrid carbon nanofillers
2020
Abstract The aim of this paper was to estimate the effect of moisture and temperature on the flexural properties of the epoxy filled with single and hybrid carbon nanofillers (CNTs and CNFs) and to reveal the most environmentally stable NC. Water absorption at 70 °C until equilibrium moisture content and heating at 70 °C for 4 weeks were followed by freezing at -20 °C for 8 weeks. Microstructural characterization of optical images revealed homogeneous dispersion of all carbon nanofillers in the epoxy resin at microscale. Positive nanofiller effects were found for sorption, flexural and thermophysical characteristics of the epoxy resin. The most environmentally stable NC was epoxy filled wit…
An analysis of through-thickness residual stresses in aluminium FSW butt joints
2006
Abstract In the paper, the results of a wide experimental campaign on friction stir welding (FSW) of aluminum alloys are reported. The attention was focused on the through-thickness residual stresses that occur on aluminum joints, after the welding process. In detail, using the hole-drilling method the residual stresses distribution in the zone close to the tool shoulder border of the joint advancing side, has been investigated; four different aluminum alloys and three different process conditions have been considered. The experimental analysis has shown that unlike traditional welding processes, the residual stresses are negative in the surface of the examined zone, and increase with depth…
Microhardness of demineralized enamel following home bleaching and laser-assisted in office bleaching
2015
Background There is little data regarding the effect of tooth whitening on microhardness of white spot lesions. This study was conducted to investigate the effect of home-bleaching and laser-assisted in-office bleaching on microhardness of demineralized enamel. Material and Methods Forty bovine incisors were selected and immersed in a demineralizing solution for 12 weeks to induce white spot lesions. Enamel blocks were prepared and randomly assigned to two groups of 20 each. The first group underwent home bleaching with 15% carbamide peroxide which was applied for 8 hours a day over a period of 15 days. In the second group, in-office bleaching was performed by 40% hydrogen peroxide and powe…
Influence of complexation between amylose and a flavored model sponge cake on the degree of aroma compound release
2008
International audience; Flavoring is used in the food industry to reinforce the aroma profile of baked cereal goods. During the processing of such products, interactions between starch and aroma compounds can occur, and this may have an impact on aroma release and perception. In the present study, 20 aroma compounds were tested to establish whether they formed complexes with amylose. The structure of the complexes was determined by wide-angle X-ray scattering (WAXS). A cocomplexation study proved that several complexing compounds could be present in the same crystalline aggregate. WAXS and differential scanning calorimetry (DSC) experiments were performed in a flavored model sponge cake at …
Size Dependent Breakdown of Superconductivity in Ultranarrow Nanowires
2005
Below a certain temperature Tc (typically cryogenic), some materials lose their electric resistance R entering a superconducting state. Folowing the general trend toward a large scale integration of a greater number of electronic components, it is desirable to use superconducting elements in order to minimize heat dissipation. It is expected that the basic property of a superconductor, i.e. dissipationless electric current, will be preserved at reduced scales required by modern nanoelectronics. Unfortunately, there are indications that for a certain critical size limit of the order of 10 nm, below which a "superconducting" wire is no longer a superconductor in a sense that it acquires a fin…
Mechanical behavior of carbon/flax hybrid composites for structural applications
2012
In this work, the influence of an unidirectional carbon fabric layer on the mechanical performances of bidirectional flax fabric/epoxy composites used for structural applications was studied. Two different bidirectional flax fabrics were used to produce flax fabric reinforced plastic (FFRP) laminates by a vacuum bagging process: one is normally used to make curtains; the other, heavier and more expensive than the previous one, is usually used as reinforcement in composite structures. In order to realize hybrid structures starting from FFRP, an unidirectional UHM carbon fabric was used to replace a bidirectional flax fabric. Tensile and three-point bending tests were performed to evaluate t…
Combinatorial Identification of Hydrides in a Ligated Ag40 Nanocluster with Noncompact Metal Core
2019
No formation of bulk silver hydride has been reported. Until very recently, only a few silver nanoclusters containing hydrides have been successfully prepared. However, due to the lack of effective techniques and also poor stability of hydride-containing Ag nanoclusters, the identification of hydrides' location within Ag nanoclusters is challenging and not yet achieved, although some successes have been reported on clusters of several Ag atoms. In this work, we report a detailed structural and spectroscopic characterization of the [Ag40(DMBT)24(PPh3)8H12]2+ (Ag40H12) cluster (DMBT = 2,4-dimethylbenzenethiol). The metal framework consists of three concentric shells of Ag8@Ag24@Ag8, which can…
Mono- and di-bridged heterobimetallic systems from group 5 hydride phosphido and hydride phosphino metalloligands. Crystal structure of Cp2Ta(H)( μ-H…
1997
Abstract The trihydrides Cp2MH3 (M Nb, Ta) react with chlorophosphines PR2Cl (R Me, Ph) affording phosphonium salts [Cp2MH2(PR2H)]+, Cl− (2 (a, b) 2′ (a, b)). Depending on the metal (Nb or Ta) and on the nature of the phosphine substituent (Me or Ph), deprotonation of these salts leads to hydride phosphino Cp2MH(PR2H) (3 (a, b) 3′a) or hydrided phosphido Cp2 TaH2(PPh2) (4′b) metalloligands. These two kinds of complexes are able to bind [M′(CO)5] or [M′(CO)4] (M′ Cr, Mo, W) organometallic fragments to give mono- or di-bridged heterobimetallic systems. The crystallographic analysis of Cp2Ta(H)(μ-H)(μ-PMe2)Cr(CO)4 (7′aCr) is reported and discussed.
Sheet Metal Hydroforming Technology - State-of-the-Art
2016
The present paper describes the current status of hydroforming technology in today’s global market that focuses on energy use in respect to increasing requirements especially from the automotive industry with its renaissance after the economic crisis. A vast hydroforming classification and the restrictions and drawbacks for a wider market share are also presented.