Chromium radiation

The X-ray powder diffraction pattern of vinblastine sulfate has been reported by Beer et al.0 using vanadium-filtered chromium radiation and a wavelength value of 2.2896 t in the calculations ... 

A definitive X-ray diffraction pattern suitable for the identification of vincristine sulfate crystals has not become available to the author. Vincristine may be readily isolated as the free base by making an aqueous solution of the sulfate alkaline with NH40H and extracting into an organic solvent such as ethylene dichloride, chloroform, or benzene. Therefore, the X-ray diffraction pattern of vincristine free base recrystallized from methanol is presented here13 31. The pattern was determined at a wavelength of 2.2896 if. using chromium radiation and a vanadium filter ... 

A pattern is made of a cubic substance with unhltered chromium radiation. The observed sin 0 values and intensities are 0.265(m), 0.321(vs), 0.528(w), 0.638(s), 0.793(s), and 0.958(vs). Index these lines and state which are due to Ka and which to Kfi radiation. Determine the Bravais lattice and lattice parameter. Identify the substance by reference to Appendix 5. 

Fig. 14-4 Partial diffractometer pattern of an oil-quenched Ni-V steel, containing about 30 volume percent austenite (> ). Chromium radiation, V filter.

While chromium radiation is the most popular, shorter wavelengths such as Fe Kol, Co Kol, and Mo Ka will increase the number of lines on the pattern and thus provide more measurable pairs. The low resolution of energy-dispersive diflfrac-tometry (Sec. 7-10) is no hindrance here, because the diffraction lines of steel are well separated, and Voskamp [7.22] has described the application of that technique to austenite measurement. 

U. Andrewes and co- workers studied the absorption of X-rays. The absorption coefi cients of X-rays from chromium radiator were studied by U. Andrewes and coworkers, D. M. Bose, C. G. Barkla and C. A. Sadler, and T. E. Auren. 0. W. Richardson and F. S. Robertson investigated the soft X-rays from chromium. A. C. Davies and F. Horton gave the critical potentials for soft X-rays. J. C. McLennan, and... 

X-ray diffraction studies were performed with chromium radiation in conjunction with a vanadium filter. This radiation eliminated fluorescence in the stainless steel, and the vanadium filter removed the K (beta) portion of the spectrum. 

Protein-Based Adhesives. Proteia-based adhesives are aormaHy used as stmctural adhesives they are all polyamino acids that are derived from blood, fish skin, caseia [9000-71 -9] soybeans, or animal hides, bones, and connective tissue (coUagen). Setting or cross-linking methods typically used are iasolubilization by means of hydrated lime and denaturation. Denaturation methods require energy which can come from heat, pressure, or radiation, as well as chemical denaturants such as carbon disulfide [75-15-0] or thiourea [62-56-6]. Complexiag salts such as those based upon cobalt, copper, or chromium have also been used. Formaldehyde and formaldehyde donors such as h exam ethyl en etetra am in e can be used to form cross-links. Removal of water from a proteia will also often denature the material. 

The term laser is an acronym constmcted from light amplification by stimulated emission of radiation. The first operating laser was produced in 1960 (1). This laser, which used a crystal of mby [12174A9-17, chromium-doped alumina, Al202 Cr, and emitted a pulsed beam of collimated red light, immediately aroused scientific interest. 

Ozonation can be enhanced by the addition of ultraviolet (uv) radiation. This combination can be effective in degrading chlorinated organic compounds and pesticides. In addition, metal ions such as iron, nickel, chromium, and titanium [7440-32-6] can act as catalysts, as can ultrasonic mixing. 

The work function for chromium metal is 4.37 eV. What wavelength of radiation must be used to eject electrons with a velocity of 1.5 X 103 km-s ... 

Chromium makes up just 0.012% of the Earth s crust, yet it is an important industrial metal. The main use of chromium is in metal alloys. Stainless steel, for example, contains as much as 20% chromium. Nichrome, a 60 40 alloy of nickel and chromium, is used to make heat-radiating wires in electrical devices such as toasters and hair dryers. Another important application of chromium metal is as a protective and decorative coating for the surface of metal objects, as described in Chapter 19. 

The total heat requirement is thus around 599.98 kj, which is about 548.81 kj more than the heat available from the reaction. This calculation, however, does not take into account the inevitable heat losses due to the nonadiabatic conditions in the reactor. An estimate of these heat losses can be made by considering the industrial practice for aluminothermic chromium metal production. The charge is preheated to about 500 °C before loading into the aluminothermic crucible. This operation adds about 96.65 kj (i.e., 48.9 cal deg-1 475) of heat to the system. It, therefore, appears that around 41.84 kj (96.65 kj - 54.81 kj) of heat is lost due to radiation and convection for every mole of chromium sesquioxide reduced to the metal by the aluminothermic process. 

The application of the Chelex 100 resin separation and preconcentration, with the direct use of the resin itself as the final sample for analysis, is an extremely useful technique. The elements demonstrated to be analytically determinable from high salinity waters are cobalt, chromium, copper, iron, manganese, molybdenum, nickel, scandium, thorium, uranium, vanadium, and zinc. The determination of chromium and vanadium by this technique offers significant advantages over methods requiring aqueous final forms, in view of their poor elution reproducibility. The removal of sodium, chloride, and bromide allows the determination of elements with short and intermediate half-lives without radiochemistry, and greatly reduces the radiation dose received by personnel. This procedure was successfully applied in a study of... 

National Council on Radiation Protection and Measurement (NCRP), 21 279 National Defense Stockpile, chromium in, 6 470, 483 84... 

Careful measurements of the structure factors of vanadium (Ohba et al. 1981) and chromium (Ohba et al. 1982) up to sin 6/2 = 1.72 A / using AgKa radiation and small spherical crystals ( 0.2 mm diameter), have been reported. The bcc structure of these metals leads to pairs of reflections such as (330/441), (431/510), at identical values of sin 6/2, which have the same intensity for a structure with one spherical atom per lattice point. This is no longer true when the t2g and eg orbitals of the cubic site are no longer equally occupied. This is easiest seen as follows. 

Heat Transfer The movement and dispersion of heat by conduction, convection, or radiation. Heavy Metals High-density metallic elements generally toxic to plant and animal life in low concentrations (e.g. mercury, chromium, cadmium, arsenic, and lead). 

The first report of radiation trapping in a solid was given by Varsanyi and co-workers (42) for 0.05 per cent ruby. Chromium is admittedly not a rare earth, but the results they obtained are so interesting that they deserve further mention. They clearly indicate a potential error in measurement to fee expected for rare-earth systems. 

Camphorate complexes of chromium (III) have been studied. The four possible isomers of the tris complex of (+ )-3-acetylcamphorate (173) were isolated,752,753 and absolute configurations were tentatively assigned. The photoisomerization of these complexes has been investigated 754 quantum yields of the order of 10-3 were obtained with visible or ultraviolet radiation at temperatures around 100 °C. Bond-breaking processes were held to be important in the reactivity of cis isomers. 

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