Crystal floating particles

Floating particles and seed crystal rotation control... 

The rolling-indenting model of free-floating particles in the slurry forms the basis of the wire-sawing process. Combined with the fracture-mechanical processes of individual particles indenting into the crystal surface one can derive a... 

From tha preceding remarks, the cause of ice— solidified or crystallized water—floating in water will be readily understood. It has been shown that at the point of solidification the liquid has the same, if not a lesser density than at 40° but, in passing to the Solid state, the gravity is much further reduced, as well by the arrangement which its particles assume, as by the expulsion of the gases dissolved in the water, and which, before they can escape, are enveloped and compressed within the solid crystal. From both, and perhaps other conjoint causes, the density of ice at a temperature of 32° is less than that of water at 212°, and hence the former floats in the latter. At the normal degree at which chemists are accustomed to compare the densities of bodies, namely 60s, and a barometric pressure of the atmosphere of thirty inches, pure water is taken as the standard of comparison, and is expressed by unity, or 1000—compared to this ice has a density of 0-916. 

Particle size — 4% below 20 y Crystal density (sink-float) — 1.93g/cc... 

Solid-liquid mixing is used to float solid particle in a liquid and is important for solid solutions, solid catalyst reactions, crystallization, and so on. 

A mixture consists of two or more substances that when put together retain their individual physical and chemical properties. That is, no new substances are formed. Differences in physical and chemical properties of the components of the mixture can be used to separate the mixture. For example, salt and pepper have different colors and can be separated by physically moving the white crystals away from the dark particles. Or salt dissolves in water while pepper does not and the two can be separated by adding water to the mixture. The salt will dissolve while the pepper will float on top of the water. Skim off the pepper and then evaporate the water. The salt and pepper are now separated. 

At the end of the reactivity measurements the sample is transferred back to the preparation chamber where a carbon film is deposited on the sample. This carbon layer has a double use. First, it protects the clusters against a further evolution (coalescence, restructuring, oxidation during air exposure) and second, in the case of MgO crystals it will serve as a thin support for the metal particles (after floating in acidic solution) for subsequent TEM characterization [12]. 

The physical properties of the solid state seen in crystals and powders of both drugs and pharmaceutical excipients are of interest because they can affect both the production of dosage forms and the performance of the finished product. Powders, as Pilpel reminded us, can float like a gas or flow like a liquid but when compressed can support a weight. Fine powders dispersed as suspensions in liquids are used in injections and aerosol formulations. Both liquid and dry powder aerosols are available and are discussed in Chapter 9 some properties of compacted solids are dealt with in Chapter 6. In this chapter we deal with the form and particle size of crystalline and amorphous drugs and the effect these characteristics have on drug behaviour, especially on drug dissolution and bioavailability. 

Analysis and spectroscopic study. The elemental analysis was performed with anICP-6000 spectrometer. The precursors crystallization was studied by thermal analysis methods (TG85). The samples were analysed by IR spectroscopy (Nicollet, FTIR-7500) and powder X-ray diffraction (PXRD, DRON-3). The morphology of surface was studied by scanning electron microscopy (SEM) (JEOL, JSM-6100). The density of KTP particles was determined by a sink-float method. Local x-ray analysis was performed using Link ISIS microanalysis system (Si Li detector) mounted on Jeol 2000 FX microscope. Bruker-400 apparatus was used for P, C and H NMR study of precursor solution. The YAG Nd SHG was measured on LS-10 device. 

In operations such as crystallization or solid-catalysed liquid reactions, it is necessary to suspend solid particles in a relatively low viscosity liquid. This can be achieved in mechanically agitated vessels where the mixer is used to prevent sedimentation of the solids and to provide conditions suitable for good liquid-solid mass transfer and/or chemical reaction. If agitation is stopped the solids will settle out or float to the surface, depending upon the relative densities of the solid and liquid phases. The suspension of solids in mixing vessels and the design of mixing vessels for solid-liquid reactions are treated in Chapters 16 and 17 respectively. 

Compared to the other flotation systems, the material is much coarser in potash flotation, due to a large liberalization size of the crystals. The rather small difference in density between the mineral salt and the brine makes it possible to float much larger particles in the brine system as compared to water systems. 

Ice, the solid state of water, floats when placed in water. Normally, you may think of a solid as having a higher density than its corresponding liquid, because the particles are closer together in the solid. When water freezes, however, it s locked into a crystal lattice that has large holes incorporated into it by its hydrogen bonds. So the density of ice is less than that of water (see Figure 19-3). 

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