Platinum elements

In the light of what we have said above, we might expect that satellites due to platinum-element coupling would be useful in structure determination. However, because of chemical shift anisotropy they are in fact often not visible, and experience (and theory) suggest that the chance of seeing them decreases as the magnetic field of the spectrometer increases. 

This particular design has a platinum element that is surrounded by a porcelain insulator. The insulator prevents a short circuit between the wire and the metal sheath. 

To eliminate the errors caused by lead wire resistance changes, it is recommended to use transmitters that accept 4-wire RTD inputs as a standard feature. In order to eliminate errors by self-heating, the measuring current should be minimized. For platinum elements, it should not exceed 250 pA. The best installation practice is to place all electronics directly on top of the thermowell and thereby eliminate lead wire and noise effects. If this cannot be done, the lead wires should be twisted and shielded the wires should also not be stressed, strained, or made to go through steep gradients. The... 

Performance Criteria Platinum Element Nickel Element Digital Output Analog Output (4—20 mA DC)... 

Ross,33 and Beard and Ross34 had also been interested in electrocatalytic properties of Pt-3d transition metal binary-alloys, with a view that stable intermetallics could be formed. It was also their view that the catalytic enhancement shown by Pt-V, Pt-Cr, and latterly Pt-Co was due to the surface roughening of the platinum crystallites caused by leaching of the non-platinum elements from the surface. In the case of the Pt-Co alloy, they believed that a more stable alloy is formed that protects against further alloy degradation. 

Figure 10-15. Electrode used for measuring the conductivity of a solution. The sampling end of the electrode is fitted with small bore rubber tubing and a glass capillary tube to aid in removing samples from large test tubes. The large rubber tubing fitted to the top of the electrode is connected to a reservoir of glass-distilled water and is used to thoroughly rinse the electrode between measurements. The close-up of the electrode shows the two platinum elements.

The electrode is a combination probe containing a platinum (redox) sensing element and an iodine-sensing reference element. The potential developed at the platinum element depends upon the relative levels of iodine and iodine ion in solution ... 

The microreactors, which are operated in a continuous flow fashion, consist of a long, meander-shaped channel, the length of which can be designed to meet the required residence time to yield a fully developed reaction product. Heating or cooling of the reactor takes place by heaters or Peltier elements and can be controlled by temperature sensors (i.e. thermocouples or platinum elements). The chips comprised externally placed heaters and sensors, but could also be applied by sputtering afterwards, similar to the electrodes for EOF. 

Samadi A. A., Gr3/nszpan R., Fedoroff M. Behaviour of trace impurities during chemical dissolution of a metal Platinum elements in aluminium and nickel. Talanta 1976 23 829-833. 

When comparing the data for the two different types of fuel, uranium fuel and mixed-oxide fuel, one can see the main differences in the region of the lighter platinum elements ruthenium, rhodium and palladium where the higher fission yields in the Pu fission lead to higher concentrations of these elements in the irradiated mixed-oxide fuel. 

The system applied in the study mentioned above consisted of a CDS model 122 Pyroprobe with a ribbon filament as the heating surface (see Chapter 3 and Appendix 1). This pyrolyser heats by varying the resistance of the platinum element. Temperature rise times for flash pyrolysis are typically of the order of milliseconds. IR spectra were obtained with an FT-IR bench system equipped with a CDS pyrolysis/FT-IR interface. The data were collected at 8 cm" with a deuterated triglycine sulfate (DTGS) detector. The interface is cylindrical in shape with two potassium bromide windows for the IR beam to pass through. 

Domanov, V.P., Zvara, I. Continuous-flow thermochromatographic separation of unsupported radioisotopes of platinum elements in a stream of air from nuclear-reaction products in an accelerator heavy-ion beam. Sov. Radiochem. 26, 731-739 (1984)... 

Zude, F., Fan, W., Trautmann, N., Herrmann, G., Eichler, B. Thermochromatography of platinum elements in oxygen—radiochemical studies of the behavior of rhodium, palladium, osmium and platinum. Radiochim. Acta 62, 61-63 (1993)... 

Platinum elements not suitable for higher temperature service due to recrystallization and grain growth... 

Some papers report measurements of Oj for K and higher shells with relativistic electrons up to ultra relativistic energies [12] with reference to theory by Kolbenstvedt [13]. K- and L-shell ionization of atoms Z = 18 to 92 by relativistic electrons were calculated for incident energy 50 keV to 1 GeV and compared to experimental results [14] but no data are given for platinum elements. The same applies to a former systematic study of the K-shell ionization cross sections at 2 MeV for elements between Z = 23 and 83 but curves as a function of Z with comparison to [13] may be useful [15]. 

Wagner established the first model for the selective oxidation in the case of the nickel-platinum alloys. It is based on the following assumption the alloy is compared to a perfect solid solution of substitution therefore, the selective oxidation of nickel involves a nickel impoverishment in alloy near the metal/oxide interface. It follows from a relative enrichment in platinum element in the same area that would have as a consequence a diffusion of platinum in alloy from this interface toward the bulk of the metal. 

J. Berzelius, Ldrhok i kemi, vol3 [Textbook in Chemistry] (Stockholm, 1818), 464. Cf James L. 8c Virginia R. Marshall, Reinvestigating Vestium One of the Spurious Platinum Elements, Bulletin for the History of Chemistry 35 1 (2010), 33-39. 

Resistance thermometers, which usually employ platinum elements, have very high sensitivity, linearity and precision. They can be used safely up to temperatures of 500 C, however, one should consider that they are sensitive to neutron and gamma radiation, and in general they have larger time constant then thermocouples, so this must be taken into account when they are employed in the reactor protection system. 

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