Crystallization of synthetic

Fig. 4.27 Upper Platy crystals of synthetic feroxyhyte formed by rapid oxidation of FeCl2 solution at pH 8 (Carlson Schwert-mann, 1980 with permission). Lower Vermiform natural feroxyhyte aggregates from the Clara Mine, Black Forest (Courtesy K.Walenta).

One of the simplest methods of purification involves crystallization of synthetic intermediates (and sometimes of the pheromone itself) at low temperature. This technique has been extensively used in the purification of fatty acids, 9). Like unsaturated fatty acids, many of the related alcohols are very insoluble in hydrocarbon solvents at low temperature. 

Crystals of synthetic zeolites often have a non-uniform distribution of their... 

Figure 9.4. Stress-strain curves observed by Morrison-Smith et al. (1976) at the temperatures shown with specimens cut from the z-growth region of a single crystal of synthetic quartz (W2 with a water content of l,600-200H/10 Si). Stress normal to (lOTl) confining pressure 300 MPa strain-rate 10 s .

Figure 9.5. A typical creep curve for a single crystal of synthetic quartz (X-507 with 365H/10 Si) with a stress of 140 MPa applied normal to (lOTl) at 510°C. Note the incubation period followed by a region of constant strain-rate. (After Linker et al. 1984.)...

Hobbs, B. E., McLaren, A. C., Paterson, M. S. (1972). Plasticity of single crystals of synthetic quartz. In Flow and Fracture of Rocks, Geophysical Monograph 16, edited by H. C. Heard, 1. Y. Borg, N. L. Carter, C. B. Raleigh, pp. 29-53. Washington, DC American Geophysical Union. 

Pentelute BL, Gates ZP, Tereshko V et al (2008) X-ray structure of snow flea antifreeze protein determined by racemic crystallization of synthetic protein enantiomers. J Am Chem Soc 130 9695-9701... 

Figure 23. Comparison of ESR signals from a single crystal of synthetic diamond in the TEioi cavity and in the loop-gap resonator. Spectra were obtained at room temperature with 2G field modulation. Spectrometer gains are indicated. A, Absorption signal, 1 mW, 9.3 GHz, 1 second time constant. B, Absorption signal, 2 pW, 8.8 GHz, 0.25 second time constant. C, Dispersion signal, other conditions same as in B. D, Dispersion signal, 1 mW, 8.8 GHz, 0.25 second time constant. From [53], with permission.

A comparison of the optically inactive crystals of synthetic (R, S)-alanine with the optically active natural crystals of is of interest. The crystallographic data for (R, S)-alanine are... 

Increase in the Si/Al ratio in the crystals of synthetic faujasites (37, 41) and analcimes (35) with decreasing alkalinity of initial gels and mixtures can be explained on the basis of these considerations. 

It is essential to note that both Si/Al ratio and NaOH content in all gels used was constant (Si/Al = 2.5 NaOH concentration = 2.61 mole/1). The data of Table VI indicates that the growth of the Si/Al ratio in the crystals of synthetic faujasite is directly associated with increases in the Si02 concentration and Si/Al ratio in the liquid phase of the gels. 

Figure 1. Single crystals of synthetic pretulite [pure Sc(P04)] are shown inside a 50 ml Pt crucible following a high-temperature-solution (flux) growth run. The large white central area is solidified Pb2P20v flux, and the SCPO4 crystals have nucleated and grown around the periphery of the Pt crucible. A normal flux-growth run takes 30 days, and an additional 30 days is required to chemically remove the Sc(P04) crystals from the solidified flux. The outer diameter of the Pt crucible is 3.9 cm.

A modification is the thermocurrent dosimeter. In this case the detector may be a thin crystal of synthetic sapphire 10 mm, thickness 1 mm) between thin metal electrodes. When the crystal is heated after having received a certain dose, the trapped electrons are released and cause a current to pass between the electrodes. The peak of the integrated current is a measure of absorbed dose. The effect is referred to as RITAC (radiation induced thermally activated current) and the technique is named TC (thermocurrent) dosimetry. Because it is instrumentally easier to measure an electric current than light, the TC dosimeter may replace the TLD in time. 

The growth of diamond in metal-carbon systems under superhigh pressures has been observed on a substrate (seed crystals of synthetic diamond) in the form of single crystallites, as discrete linear series of crystals, or in groups of... 

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