Phase formation photographs

Figure 7. Photographs of phase formation on the heated horizontal cylinder in a solution of 9 mole % TEA in water. AT -10 K. Photograph a shows the structure normally seen, while in photograph b the structure has become organized by the gravity vector without change in operating conditions.

The cleaning process proceeds by one of three primary mechanisms solubilization, emulsification, and roll-up [229]. In solubilization the oily phase partitions into surfactant micelles that desorb from the solid surface and diffuse into the bulk. As mentioned above, there is a body of theoretical work on solubilization [146, 147] and numerous experimental studies by a variety of spectroscopic techniques [143-145,230]. Emulsification involves the formation and removal of an emulsion at the oil-water interface the removal step may involve hydrodynamic as well as surface chemical forces. Emulsion formation is covered in Chapter XIV. In roll-up the surfactant reduces the contact angle of the liquid soil or the surface free energy of a solid particle aiding its detachment and subsequent removal by hydrodynamic forces. Adam and Stevenson s beautiful photographs illustrate roll-up of lanoline on wood fibers [231]. In order to achieve roll-up, one requires the surface free energies for soil detachment illustrated in Fig. XIII-14 to obey... 

All of the Type A and B inclusions studied are surrounded by a layered rim sequence of complex mineralogy [21] which clearly defines the inclusion-matrix boundary. Secondary alteration phases (grossular and nepheline, especially) are also a common feature of these inclusions, suggesting that vapor phase reactions with a relatively cool nebula occurred after formation of inclusions. Anorthite, in particular, is usually one of the most heavily altered phases the relationship between Mg isotopic composition and alteration is discussed below. (See [12] for striking cathodoluminesce photographs of typical Allende alteration mineralogy.) Inclusion Al 3510 does not fit the normal pattern as it has no Wark-rim and does not contain the usual array of secondary minerals. 

A simple and economical method for recovering silver residues by dissolution in used photographic fixer (thiosulfate) solution, then precipitation by addition of zinc powder, is detailed [1]. After the acid digestion phase of silver recovery operations, addition of ammonia followed immediately by addition of ascorbic acid as reducant gives a near-quantitative recovery of silver metal, and avoids the possibility of formation of silver nitride [2],... 

Figure 4.9. Scanning electron microscope photographs showing the roughening transition of 111) faces of a TiOj crystal and the formation of hollowed needle crystals as impurities are added [19]. Growth occurs by liquid phase epitaxy on a (001) substrate. Fe203 is added as an impurity in the following amounts (a) 0%. (b) 1.3 mol%,...

In CoOP above 300 K the compound exists in the Cccm space group, but with characteristic diffuse X-ray lines indicative of the Peierls modulation and no evidence of superstructure formation. Below 300 K a superstructure develops as shown by the appearance of satellite reflections on the X-ray diffraction photographs. At 280 K a phase transition to the Pccn space group occurs and associated with this are changes in the satellite pattern.78 74 Superstructure development which is commensurate with the Peierls modulation is completed about 250 K. 

Fig. 4.9. Formation of a molybdenum boride layer between Mo and B-containing phase (a) and between Mo and MoB (b)289 Annealing temperature 1450°C. Time (a), 9000 s (2.5 h) (b), 7200 s (2 h). Photographs kindly provided by Prof. W. Lengauer. Reprinted with permission from Elsevier Science.

For chemical and physical processes across microdroplet/solution interfaces, obs having dimensions of s or dm mor s is often proportional to r " ( = 0, 1 or 2). A linear relationship between obs and has been reported for the extraction of a neutral compound such as ferrocene derivatives from water into a micro-oil-droplet without adsorption at the microdroplet/water interface [18,19] and for a photographic dye formation reaction in an oil-in-water emulsion [23]. The proportionality of a kobs versus r plot has been reported for a relatively slow process such as a photographic dye formation reaction [23,29,42], electron transfer [43-45] and adsorption at the micro-oil-droplet/water interface [19,20]. For the chemical reaction with the rate-determining step in a solution phase or a microdroplet in a microdroplet/solution system, fcobs is independent of r[23]. Based on the droplet size dependence of the reaction rate, the rate-determining step of the overall reaction processes across a microdroplet/solution interface is analysed and the reaction mechanism can be discussed in detail. 

Fig. 4.9 (See also color plate section.) Photographs of the microscope shde Kofler preparations showing the various phases of the benzocaine picric acid (BC PA) binary system. Top (a) the photomicrograph of the recrystalhzed contact preparation of BC and PA at 25 °C. The interference colours are due to the use of crossed polarizers. The pure compounds are at the extremities of the preparation, while in the region where the original compounds have merged a number of different areas may be observed, due to the formation of different crystalline species combining the two components. Heating this preparation on the hot stage microscope...

Cocrystals can also be prepared in situ in covered depression slides on the polarized optical light microscope or Raman microscope by adding a small drop of solvent to the solid reactants. This has been shown for cocrystals of CBZ NCT with ethanol, ethyl acetate or 2-propanol. Photographs obtained through the polarized light microscope are shown in Fig. 22. These images show cocrystal formation in less than three minutes after solvent addition. In this case, the cocrystallization reaction proceeds by a similar pathway to those of macro-phase suspensions described above. In micro-phases the solvent added must allow for dissolution of both reactants so that concentrations in... 

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