Models Pulling-holding model

The STRAIN AND DISTORTION model for catalysis involves pushing, pulling, or twisting a bond that is to be made or broken during the reaction. Parts of the substrate not involved directly in the chemical reaction are required to hold the substrate on the enzyme in the distorted form. The distortion and strain make it easier to reach the transition state. 

The results stated so far has been with saturated vapor or liquid as the equilibrium bulk phase. Liquid-like state in pore, however, can hold with reduced vapor pressure in bulk the well-known capillary condensed state. One of the most important feature of the capillary condensation is the liquid s pressure Young-Laplace effect of the curved surface of the capillary-condensed liquid will pull up the liquid and reduce its pressure, which can easily reach down to a negative value. In the section 2 we modeled the elevated freezing point as a result of increased pressure caused by the compression by the excess potential. An extension of this concept will lead to an expectation that the capillary-condensed liquid, or liquid under tensile condition, must be accompanied with depressed freezing temperature compared with that under saturated vapor. Then, even at a constant temperature, a reduction in equilibrium vapor pressure would cause phase transition. In the following another simulation study will show this behavior. 

Problem 6-5. Honey on a Spoon . You must have observed that when you dip a spoon into honey (or other viscous fluid) withdraw it and hold the spoon horizontal, you can keep the honey from draining by rotating the spoon. If you rotate the spoon too slowly the honey will drain, but above a critical rotation speed the honey will not drain from the spoon. (Try this with water and it will not work ) We want to analyze this problem and see if we can t predict the critical speed of rotation required to keep the honey on the spoon. The honey forms a thin layer of thickness h(0) around the spoon. The spoon is modeled as a cylinder of radius R and rotates about its axis at angular velocity 2 so that the speed of the surface of the cylinder is U = HR. The force of gravity acts downward and tries to pull the fluid off the cylinder. 

In summary, this book on metabohc encephalopathies is meant to combine and correlate animal and human studies. It is hoped that increased awareness of the importance of early diagnosis and treatment of these disorders may result in a lowering of the incidence of structural changes, and morbidity. These disorders hold a special fascination for both basic scientists and chnical investigators because they are accessible, treatable, and there exist good animal models for study. Therefore, this book pulls together basic and chnical neuroscience issues in the treatment of specific metabolic encephalopathies. 

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