Flow, tear

FIGURE 23.2 Lacrimal flow and drainage. (1) The lacrimal gland produces tears that are distributed by blinking. (2) At normal rates of flow, tears are cleared by nasolacrimal drainage. (3) Sudden increases produced by instillation or reflex tearing overspill the lower fornix. 

The second story is that of Robin. Robin was 53 and had no previous psychiatric history. As she registered, she began to cry, with silently flowing tears and then with her body convulsing with sobs. She was unable to talk. After sitting with me in this state for several minutes, she started to choke out phrases, 1... 

Comparing the properties of TPO-0 and TPO-V of the same constituents at the same hardness, the benefits given by the fully cured rubber in TPO-V become clear (improved set properties, fluid and chemical resistance, service temperature and tensile strength). These are achieved, however, at the cost of some other properties (e.g. reduced melt flow, tear... 

The reasons for those lowfrequent emission events are flow processes during the child mold filling or friction processes between the casting part and the child mold. Investigations where, using radioscopy, hot tears could be detected show that the time based... 

A familiar (and biblical [SO]) example is the formation of tears of wine in a glass. Here, the evaporation of the alcohol from the meniscus leads to a local raising of the surface tension, which, in turn, induces a surface and accompanying bulk flow upward. 

Gum arable comes from various species of Acacia. The gum exudes through cracks, injuries, and incisions in the bark and is collected by hand as dried tears. Gum arable is unique among gums because of its high solubiUty and the low viscosity and Newtonian flow of its solutions. While other gums form highly viscous solutions at 1—2% concentration, 20% solutions of gum arable resemble a thin sugar symp in body and flow properties. 

To remain safe and efficacious on the eye, contact lenses must maintain clear and wetted surfaces, provide an adequate supply of atmospheric oxygen to and adequate expulsion of carbon dioxide from the cornea, allow adequate flow of the eye s tear fluid, and avoid excessive abrasion of the ocular surface or eyeflds, all under a variety of environmental conditions. The clinical performance of a contact lens is controlled by the nature of the lens material the lens design the method and quaUty of manufacture the lens parameters or specifications prescribed by the practitioner and the cleaning, disinfection, and wearing procedures used by the patient. 

Antioxidants may be assessed in a variety of ways. For screening and for fundamental studies the induction period and rate of oxidation of petroleum fractions with and without antioxidants present provide useful model systems. Since the effect of oxidation differs from polymer to polymer it is important to evaluate the efficacy of the antioxidant with respect to some property seriously affected by oxidation. Thus for polyethylene it is common to study changes in flow properties and in power factor in polypropylene, flow properties and tendency to embrittlement in natural rubber vulcanisates, changes in tensile strength and tear strength. 

It is important to keep bolts, nuts and other potentially loose items to a minimum inside the unit, as vibration from air/gas flow and bag cleaning can loosen nuts, break small welds, and ultimately tear holes or rip bags. The bag construction is likewise extremely important, since loose edges and unlocked seams will fray and tear, allowing fibers into the product dust. The bag construction must have straight seams in order for them to bend and flex properly on cleaning and/or loading. 

When rubbers eventually fracture, they do so by tearing. Fracture surface energies, using the Griffith equation, have been found to be of the order of 10 J m , whereas the true surface energies are only 0.1-1.0 J Hence, more energy is involved in fracture than is required to form new surfaces, and, as with other polymers, this extra energy is assumed to be used up in viscoelastic and flow processes that occur between the molecules immediately before the rubber breaks. 

The tear compounds (lachrymators) cause a flow of tears and irritation of the skin. Because tear compounds produce only transient casualties, they are widely used for training, riot control, and situations where long-term incapacitation is unacceptable. When used against poorly equipped guerrilla or revolutionary armies, these compounds have proved extremely effective. When released indoors, they can cause serious illness or death. 

The symbol CNC identifies a 30% solution of CN in chloroform. It was developed to deliver CN in liquid form. CNC causes a flow of tears, irritates the respiratory system, and causes stinging of skin. 

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