Inner surfaces, crystals

Double-Pipe Scrapea-Surface Crystallizer This type of equipment consists of a double-pipe heat exchanger with an internal agitator fitted with spring-loaded scrapers that wipe the wall of the inner pipe. The cooling hquid passes between the pipes, this annulus being dimensioned to permit reasonable shell-side velocities. The scrapers prevent the buildup of solids and maintain a good film coefficient of heat transfer. The equipment can be operated in a continuous or in a recirculating batch manner. 

There is almost no degree of freedom in the choice of the crystallizer type Crystallization in fine chemicals manufacture is usually carried out in jacketed stirred tanks. Coils can also be used to enhance cooling, but crystals are often formed on their surface. This encrustation results in a large increase of the thermal resistance, and, consequently, a decrease of the cooling capability of the tank. Any roughness of inner surfaces of the tank can be a germ for crystals, particularly the cooled surfaces. Therefore, crystallizers are often made with polished cooled surfaces. 

Perforated bowls are used when relatively large particles are to be separated from a liquid, as for example in the separation of crystals from a mother liquor. The mother liquor passes through the bed of particles and then through the perforations in the bowl. When the centrifuge is used for filtration, a coarse gauze is laid over the inner surface of the bowl and the filter cloth rests on the gauze. Space is thus provided behind the cloth for the filtrate to flow to the perforations. 

In the other end-member scenario, the mass of the component in the host mineral is negligible. A quasi-steady-state diffusion profile is established in the host crystal and the melt inclusion maintains the concentration on the inner surface. The steady-state concentration profile would be (Equation 3-3 Ig)... 

Prismatic structure layer the layer consisting of polygonal rhombic prismatic aragonite crystals perpendicular to the inner surface of the shell. 

Crossed lamellar structure aragonite needle crystals align in the c-axis direction forming rectangular blocks. The c-axes are inclined at 45 — 55° to the inner surface of the shell, and the neighboring blocks are oppositely inclined. 

Complex crossed lamellar structure a layer consisting of aragonite needle crystals with orientations inclined at 45° to the inner portion of the cell. These needle crystals aggregate in a radial manner, forming a conical body, which is arranged nearly perpendicularly to the inner surface of the shell. 

The crystals of rock-salt are nearly always cubes or small octahedrons. When the crystals form on the surface of evaporating brine, distinctive hopper-shaped crystals resembling hollow quadrilateral pyramids are developed the inner surface appears to be arranged in a series of steps. D. I. Mendeleeff1 explains the formation of hopper salt crystals as follows ... 

Deposition of liquid crystalline material containing cholesterol esters on the inner surfaces of human arteries is another nonequilibrium process in which much interest exists. No doubt there are other examples as well where dynamic phenomena involving liquid crystals are important in biological systems. 

The crystalline micronized bisallene rac-1 was heated to 140-150 °C in a vacuum. The crystals turned dark-green and the reaction was completed within 4 h. Product 2 (20-28%) was very sensitive to oxygen. Supermicroscopy (AFM) revealed that the reaction occurred only at outer and inner surfaces. 

In this polymerization, the biofunctional component (enzyme) can be concentrated in an interfacial area between the frozen ice crystal and the supercooled monomer phase, and immobilized by molecular entanglement between the enzyme and polymer molecules. This is a different procedure for fixation from the usual entrapping method with a crosslinked structure in a gel. Therefore, we may call this procedure the adhesion-method to distinguish it from the usual entrapping. This term was extended to cover the use of the usual synthetic polymers including hydrophobic polymers as the supports. One of the characteristic properties of products obtained in this way was that there is a maximum activity at a certain monomer concentration. The maximum activity is observed when the increased inner surface area is balanced by the increased leakage of enzyme and these occur with a decrease of monomer concentration. Immobilization by physical entrapping was also studied by Rosiak [26], Carenza [27] and Ha [28]. 

---