Effective cavity thickness

It is now assumed that isothermal flow equations can be applied using the reduced, effective cavity thickness X a so that the pressure drop frrom the center of a spreading disk flow can be written [6]... 

Thick insert (> 1/3 of the cavity thickness) or very thin plastic layer will cause a weak adhesion. This phenomenon can be explained so, that aluminum insert is effectively a heat sink that cools the melt and limits the penetration of melt to its microcavities. After a certain thickness value saturation penetration is reached and no additional effect can be obtained by decreasing the insert thickness. When the heat capacity of insert is low enough the viscosity of plastic does not decrease substantially and a good wetting of the microcavities is achieved. 

In practice the clamping pressure will also depend on the geometry of the cavity. In particular the flow ratio (flow length/channel lateral dimension) is important. Fig. 4.42 illustrates typical variations in the Mean Effective Pressure in the cavity for different thicknesses and flow ratios. The data used here is typical for easy flow materials such as polyethylene, polypropylene and polystyrene. To calculate the clamp force, simply multiply the appropriate Mean Effective Pressure by the projected area of the moulding. In practice it is... 

The recommended radius not only reduces the brittleness effect but also provides a streamlined flow path for the plastic melt in the mold cavity. The radiused corner of the metal in the mold reduces the possibility of its breakdown and thus eliminates a potential repair need. Too large a radius is also undesirable because it wastes material, may cause sink marks, and may even contribute to stresses from having excessive variations in thickness. 

X-ray studies showed that all the complexes listed in Table 4 are crystalline and displayed the diffraction patterns as predicted from the molecular models, in which the a-CD cavity is threaded by an OE chain but not by a squalane chain, and also from the experimental finding that a-CD forms complexes with the former but not with the latter. The fact that neither jS-CD nor y-CD can complex with OE may be ascribed to the thickness of the OE chain that is too thin to interact effectively with the inner surfaces of these CD rings. The 13C CP/MAS NMR spectra of the a-CD-OE complexes were similar to those of a-CD-PEG complexes, exhibiting each carbon atom of glucose as a single peak. Thus, the a-CD molecules in the complex with OE assume a symmetrical conformation and each glucose unit finds itself in a similar environment. 

Although pheromones can be considered as a special form of odorants (scents), their actions, effects and functions have similarities to those of hormones. They bind to a specific receptor which then activates an effector system, which initiates an action potential. They bind to specific sensory cells, the neurones, in the olfactory epithelium, which is located on the roof of the nasal cavities. The epithelium consists of three types of cells, basal, supporting and sensory cells (neurones). The neurones are bipolar, that is they possess a single dendrite, which extends from the cell body to the surface of the olfactory epithelium, and an axon that forms a synapse with a nerve that transfers information to the olfactory centre in the brain. The epithelium is covered with a thick layer of mucus, in which the pheromones dissolve. The mucus contains proteins that bind the pheromone(s) for delivery to the olfactory receptors and then to remove them once they have been detected. 

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