Forced hydrolysis scaling

Generally, alkoxide-derived monodisperse oxide particles have been produced by batch processes on a beaker scale. However, on an industrial scale, the batch process is not suitable. Therefore, a continuous process is required for mass production. The stirred tank reactors (46) used in industrial process usually lead to the formation of spherical, oxide powders with a broad particle size distribution, because the residence time distribution in reactor is broad. It is necessary to design a novel apparatus for a continuous production system of monodispersed, spherical oxide particles. So far, the continuous production system of monodisperse particles by the forced hydrolysis... 

A second example of the formation of monodisperse particles hes in the production of hematite particles produced using a forced hydrolysis process in very dilute solutions (Matijevic, 1978 Hamada, 1981 Ozaki, 1984,1990 Morales, 1992). However, with the recent introduction of the gel-sol process by Sugimoto et al. (1993a, 1992) the prospect of large-scale production of monodisperse particles has become a reality. A dissolution-deposition model has been proposed to interpret the formation mechaiusm of these... 

Methods used to demonstrate the existence of membrane phospholipid asymmetry, such as chemical labelling and susceptibility to hydrolysis or modification by phospholipases and other enzymes, are rmsuitable for dynamic studies because the rates of chemical and biochemical reactions are of a different order compared to the transmembrane translocahon of the phospholipids. Indirect methods have therefore been developed to measure the translocation rate which are consequent on the loss of membrane phospholipid asymmetry. Thus time scales appropriate to rates of lipid scrambling under resting conditions or when the forces preserving the asymmetric phospholipid distribution are disturbed can be monitored. Generally the methods rely on detecting the appearance of phosphatidylserine on the surface of cells. Methods of demonstrating Upid translocation in mammalian cells has been the subject of a recent review (Bevers etal., 1999). 

Since acid addition is normally used to prevent scaling in the RO unit and to prevent hydrolysis of cellulose acetate RO membranes, the reaction of the acid with bicarbonate in the feedwater produces carbon dioxide which can further deplete the ion exchange capacity. Forced-draft degasification removes the C02. 

To obtain a better understanding of the sigmoid kinetics observed for hydrolysis and aminolysis reactions, as discussed in the previous sections, these reactions were investigated on the nanometer scale by iCFM. In these experiments the force required to pull gold-coated AFM tips functionalized with SAMs of NHS-CIO away from contact with an inert octadecanethiol (ODT) SAM on flat Au(lll) was monitored in real-time during reaction in aqueous NaOH and n-butylamine for hydrolysis and aminolysis, respectively. 

Figure 13.3. A. Mechanical characterization by a short beam 3-point bending (see inset) of polyurea-crosslinked silica aerogel monoliths and their noncrosslinked (native) counterparts a, 0.63 gcm b, 0.44 gcm c, 0.38 gcm , and d, 0.28 gcm . Native samples do not register in the load-force scale shown. B. Cumulative data. Dark blue triangles and the dark blue line concern two-step aerogels made by acid-catalyzed hydrolysis and base-catalyzed gelation. All other samples use one-step base-catalyzed silica with different isocyanates. Multiple lines for crosslinked samples correspond to different di- and tri-isocyanate crosslinkers.

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