Mechanical shear forces

If the char formed by the burning of the elastomer is not strong, it wdl easily erode due to mechanical shear forces, thermal stresses, and internal pressure generated by the hot volatile gases [98]. Therefore, mbber should be properly reinforced so that the char can withstand both mechanical... 

In cold mastication of rubber, a substance which prevents the recombination of the free radicals produced by the mechanical shearing forces. See Cold Mastication, Free Radical and Mechano-Chemical. 

Agglomerates are broken down through mechanical shearing forces Particle size reduction Desagglomeration. 

DNA is extremely sensitive to mechanical shearing forces because of its huge length. Routine laboratory manipulations such as pipetting can break DNA into shorter fragments. However, once isolated, DNA is a relatively stable macromolecule and can remain so when stored dry or under ethanol... 

In the process of sonication, electrical energy is converted into mechanical energy. The sound waves produce cavitation (the process of formation and collapse of microscopic bubbles) which leads to great mechanical shear forces. Particles are hammered to form smaller particles, and the increased energy of the system can promote chemical reactions. Ultrasonic chemistry has recently been reviewed [34]. Most research in sonichemistry has been carried out in ultrasonic cleaning baths. Operations on scale can be carried out by using commercial flow cells [35],... 

Most typical slurries consist of at least two components. The first component is the slurry abrasive, which typically provides the mechanical shear force that is needed to remove the oxide or metal films from the wafer. Most abrasive particles are in the range of 40-150 nm in size. The slurry will also have an oxidizer component such as H2O2 to provide the right chemical environment or chemical forces for the oxidation of the metal layer. For oxide polishing, mechanical forces predominate. Typical oxide slurries such as SCI 12 (KOH based slurry with silica abrasive from Cabot) do not have any oxidizer component. For metal polishing, it is theorized that the metal film has to go through a transformation of forming the oxide, which in most cases is fairly soluble and can easily be removed by mechanical action on the wafer surface. 

Matrix solid-phase dispersion (MSPD) was developed by researchers at Louisiana State University s School of Veterinary Medicine in order to isolate, identify, and quantify veterinary drug residues in livestock (Barker and Hawley, 1992). Compared to traditional methods, MSPD reduces solvent use by 98% and turnaround time by as much as 90%. The method involves the mechanical blending of a sample matrix with bulk C-18 sorbent. The C-18 hydrophobic phase has the ability to incorporate the lipids in meat and other food products into its matrix. Mechanical shearing forces initially disrupt the sample structure and disperse the sample over the surface of the C-18 bonded silica. The process causes the sample and polymer phase to become semidry, which then allow the material to be packed into a column (see Fig. 9.4). 

Cotton cellulose is susceptible to degradation by mechanical shear forces supplied by either a Wiley mill or a Norton ball mill. Mechanoradicals are produced in the interim. 

Production of petroleum is often hampered by damage to the permeability of reservoir rocks resulting from interaction of injected fluids with the porous rock formation. Fine particles of clays and other minerals are often found attached to the pore walls of reservoir rocks. The interaction between injected fluids and the rock can cause their movement by a combination of mechanical shear forces, colloid-chemical reactions and geochemical transformations. This chapter reviews several different aspects of the fines migration process. 

Rapid fractionation of hepatocytes by mechanical shearing forces [33]. 

PIA of staphylococci can be isolated from the cell surface or from the bacterial culture filtrate. The majority of partially deacetylated PIA is attached to the bacterial cell wall, whereas completely acetylated PIA (from the icaB deletion mutant strain) is released into the culture filtrate (4). In addition, small amounts of deacetylated PIA released from the cell surface by mechanical shear force might be detectable in the culture filtrates (1). 

One of the main applications of microfluidic electroporation devices is cell lysis. In these devices, the mechanical (shear force) or electrical forces are applied to rapture the cell membrane and release its intercellular contents. 

How do mechanical shear force and diffusion influence the dispersion of nanoparticles in a vegetable oil-based polymer matrix ... 

The term s can be thought of as being proportional to the rate at which stability suppresses the generation of turbulence. Turbulence is also being generated by mechanical shear forces at a rate proportional to du/dzf. The Richardson number is the ratio of these two processes. 

The mechanical shearing forces experienced during processing in extruders and mixing machinery are capable of breaking the polymer chain molecules, so that each molecule forms two highly reactive free radicals. 

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