234,260 research outputs found
The use of standard electrode potentials to predict the taste of solid metals
Not all metals taste equally metallic when placed in the mouth. While much work has been done to examine the metallic taste sensations arising from metal ions in solutions, there is comparatively less known about the taste of solid metals. In this study seven metals in the form of spoons were used to compare the perception of taste arising from solid utensils placed inside the mouth. 32 participants tasted seven spoons of identical dimensions plated with each of the following metals: gold, silver, zinc, copper, tin, chrome and stainless steel. More negative standard electrode potentials were found to be good predictors of solid metals that had tastes scoring highest for the taste descriptors strong, bitter, and metallic. Thus, it was found that both gold and chrome (having the most positive standard electrode potentials) were considered the least metallic, least bitter and least strong tasting of the spoons. Zinc and copper (having the most negative standard electrode potentials) were the strongest, most metallic, most bitter, and least sweet tasting of the spoons. We conclude that gold and chrome have tastes that are less strong than metals with lower standard electrode potential
Recommended from our members
Processing Parameters for Selective Laser Melting (SLM) of Gold
Research into laser processing of different metals has enabled Solid Freeform Fabrication (SFF)
processes to produce parts for a wide variety of applications. However, less focus has been made
on the processing of precious metals. Currently little research has been reported on the
processing of precious metals and alloys using the Selective Laser Melting (SLM) process. Here
we present an initial investigation into the processing of 24 carat gold (Au) powder using a SLM
system. Gold powder was tested for apparent density, tap density, particle shape and size
distribution. A quality check of the specimen was carried out using a Scanning Electron
Microscope (SEM) for sinterability and occurrence of porosity. Significant processing
parameters were also identified.Mechanical Engineerin
Friction behavior of glass and metals in contact with glass in various environments
Sliding friction experiments have been conducted for heat-resistant glass and metals in contact with glass. These experiments were conducted in various environments including vacuum, moist air, dry air, octane, and stearic acid in hexadecane. Glass exhibited a higher friction force in moist air than it did in vacuum when in sliding contact with itself. The metals, aluminum, iron, and gold, all exhibited the same friction coefficient when sliding on glass in vacuum as glass sliding on glass. Gold-to-glass contacts were extremely sensitive to the environment despite the relative chemical inertness of gold
Engineering of Low-Loss Metal for Nanoplasmonic and Metamaterials Applications
We have shown that alloying a noble metal (gold) with another metal
(cadmium), which can contribute two electrons per atom to a free electron gas,
can significantly improve the metals optical properties in certain wavelength
ranges and make them worse in the other parts of the spectrum. In particular,
in the gold-cadmium alloy we have demonstrated a significant expansion of the
spectral range of metallic reflectance to shorter wavelengths. The experimental
results and the predictions of the first principles theory demonstrate an
opportunity for the improvement and optimization of low-loss metals for
nanoplasmonic and metamaterials applications.Comment: 14 Pages, 4 figure
Characterization of Metal and Metal Alloy Films as Contact Materials in MEMS Switches
This study presents a basic step toward the selection methodology of electric contact materials for microelectromechanical systems (MEMS) metal contact switches. This involves the interrelationship between two important parameters, resistivity and hardness, since they provide the guidelines and assessment of contact resistance, wear, deformation and adhesion characteristics of MEMS switches. For this purpose, thin film alloys of three noble metals, platinum (Pt), rhodium (Rh) and ruthenium (Ru) with gold (Au), were investigated. The interrelationship between resistivity and hardness was established for three levels of alloying of these metals with gold. Thin films of gold (Au), platinum (Pt), ruthenium (Rh) and rhodium (Ru) were also characterized to obtain their baseline data for comparison. All films were deposited on silicon substrates. When Ru, Rh and Pt are alloyed with Au, their hardness generally decreases but resistivity increases. This decrease or increase was, in general, dependent upon the amount of alloying
Friction behavior of members of the platinum metals group with gold
The adhesion and friction behavior of the platinum metals group was examined with clean surfaces and surfaces selectively contaminated with oxygen, vinyl chloride (C2H3Cl), and methyl mercaptan (CH3SH). A pin or disk specimen configuration was used with the pin being a single crystal of gold of the (111) orientation and with the platinum metal disks also being single crystals of the (111) or (0001) orientation. Loads applied ranged from 1 to 10 g and a sliding velocity of 0.7 mm/min was employed. Results indicate adhesion and transfer of gold to all of the platinum metals. Despite this observation friction differences existed among the metals in the group. These differences are related to surface chemical activity. Adsorption of various friction reducing species was selective. With some adsorbates present strong adhesive forces between metals were still observed
Theory for the electromigration wind force in dilute alloys
A multiple scattering formulation for the electromigration wind force on
atoms in dilute alloys is developed. The theory describes electromigration via
a vacancy mechanism. The method is used to calculate the wind valence for
electromigration in various host metals having a close-packed lattice
structure, namely aluminum, the noble metals copper, silver and gold and the
transition metals. The self-electromigration results for aluminum and the
noble metals compare well with experimental data. For the metals small
wind valences are found, which make these metals attractive candidates for the
experimental study of the direct valence.Comment: 18 pages LaTeX, epsfig, 8 figures. to appear in Phys. Rev. B 56 of
15/11/199
Observation of electronic and atomic shell effects in gold nanowires
The formation of gold nanowires in vacuum at room temperature reveals a
periodic spectrum of exceptionally stable diameters. This is identified as
shell structure similar to that which was recently discovered for alkali metals
at low temperatures. The gold nanowires present two competing `magic' series of
stable diameters, one governed by electronic structure and the other by the
atomic packing.Comment: 4 pages, 4 figure
The Success Story of Gold-Based Catalysts for Gas- and Liquid-Phase Reactions: A Brief Perspective and Beyond
Gold has long held the fascination of mankind. For millennia it has found use in art, cosmetic metallurgy and architecture; this element is seen as the ultimate statement of prosperity and beauty. This myriad of uses is made possible by the characteristic inertness of bulk gold; allowing it to appear long lasting and above the tarnishing experienced by other metals, in part providing its status as the most noble meta
- …