Contact factor

The proportion AC/AB is termed the coil contact factor. The proportion CB/AB is sometimes used, and is termed the bypass factor. 

Taking the off condition at 5°C dry hulh and measuring the proportion along the process line gives a coil contact factor of 75%. 

Example 25.2 Taking the first stage as Example 25.1, the water would he cooled to 25.4°C and could he used in a coil of 80% contact factor to pre-cool outside air to... 

Activation of the coagulation system may start after activation of the contact factors (intrinsic system) or after release of tissue factor (extrinsic system). 

The quasi-chemical model was derived by Guggenheim for application to organic fluid mixtures. Applying it to crystalline solids is not immediate, because it necessitates conceptual modifications of operative parameters, such as the above-mentioned contact factor. Empirical methods of derivation of the above parameters, based on structural data, are available in the literature (Green, 1970 Sax-ena, 1972). We will not treat this model, because it is of scanty application in geochemistry. More exhaustive treatment can be found in Guggenheim (1952) and Ganguly and Saxena (1987). 

Following activation by the contact factor or TF pathways, the coagulation cascade is maintained in a prothrombotic state by the continued activation of factors VIII and IX to form the tenase complex, until it is down-regulated by the anticoagulant pathways (see Section 11.9). 

This expression leads to the conclusion that the asymmetry contact factor decreases as the viscous damping, tan 8, increases. 

Density Transition State Rr/R, Stability Factors F(0) F(oo) Contact Factor 9(Rp) Attempt Factor U Cage Factor Z Diffusion CoelKcient D/De ... 

Conotrane benzalkonium chloride, contact factor factor XII. 

Also see color figure.) Tissue factor-factor Vila complex. The three-dimensional structure of the complex of factor Vila and tissue factor (minus the transmembrane polypeptide domain of the tissue factor) in the absence of membrane surface. It is approximately 115 A in length and has a diameter of 40-50 A. Factor Vila shows its four distinct domains the Gla domain, two EGF-like domains, and the proteinase domain. Tissue factor contacts factor VHa via the interface between the two fibronectin type Ill-like domains. All four domains of factor Vila appear to be involved in the interaction between tissue factor and factor Vila. The Gla domain of factor Vila is folded very similarly to the Gla domain of prothrombin (Gla domain of prothrombin fragment 1). Activation of factor VII can be catalyzed by thrombin, factor Xa, factor Vila, and factor Xlla—all by cleavage at Arg -Ile . Secondary structures are shown in the center diagram two views of the close interactions between TF and factor Vila are shown in the two diagrams at each side. 

Another possibility is that some other clotting factor is increased or activated in such a way that the assay system responds fortuitously to it in a way indistinguishable from the usual response to factor VIII, e.g., factors XI and XII factor XII is known to rise on exercise (II). That this might occur over a limited range of the dose-response curve in the thromboplastin generation test system was shown by experiments in which the addition of activation product (Wl) simulated an increased factor VIII concentration (author s unpublished observations, 1960 FI), although statistical invalidity would probably be detectable over a series of experiments if this were the explanation. This also was looked for, but was not found (14). It is interesting that, in a patient with severe factor VIII deficiency and partial factor XI deficiency (SI), adrenaline infusion was followed by a marked rise in factor XI concentration and the appearance of a trace of factor VIII (K. Schulz, personal communication, 1964). Furthermore, the confusion that arose some years ago over factor IX assay now seems to have been due to activation of the contact factors (P4), hence... 

It is believed that normal growth within tissues is also controlled by contact inhibition. That is, inhibition of abnormal cell division and growth by cell-to-cell contact factors called integrins and adhesion molecules. In addition, as cells are added during growth and repair, others die so overall size of a tissue or organ is maintained. 

The first phase of the multiphased sequence has the production of the prothrombin-converting factor as its ultimate purpose. The synthesis of the activated form of factor X begins with the activation of factor XII (the contact factor) to XI, then IX followed by VIII. This represents the intrinsic pathway. An extrinsic pathway to activated factor X also exists. It depends on the release of thromboplastin (factor III) into the blood from the damaged blood vessel wall (or other tissue). This tissue thromboplastin, in the presence of Ca2+ and activated factor VII, is also activated to factor X. The two pathways are essential. They operate at very different rates. 

Therefore, it can be seen that allergic contact factors are common, and appropriate, skilled patch-testing investigations can determine relevant causes. 

Most workers are exposed to several metalworking fluids that may have undergone replacement since the onset of dermatitis. The names, batch numbers and manufacturers addresses must be obtained and enquiry made as to whether any other additives are added when the cutting fluid is in use. Other relevant factors to consider include machine-cleaning chemicals, protective metal coatings (Calnan 1978), solvents for removing oil from finished pieces, barrier creams, skin cleansers, protective equipment and domestic contact factors. 

Patch testing with a standard series of allergens, oil batteries (Foulds and Koh 1989) and ingredients of the oil at appropriate dilutions as well as other potential contact factors have to be performed. Facilities for control testing are vital in order to exclude false positive irritant reactions. 

Ion adsorption at active. sites on a contact surface may lead to losses on the order of several nanograms per square centimeter. The importance of this factor therefore increases as the concentration of the analyte decreases. Adsorptive losses are a function of the nature and valence state of the analyte, the nature and concentration of accompanying ions in the solution, pH. temperature, and the duration of contact. Factors related to the containment vessel include the material from which it is constructed, its surface area, and the nature of any pretreatment,... 

XII Hageman Factor Contact Factor Hydrolyses Factor XI Hageman trait... 

Damaged cells, membrane fragments, and the activator complexes of the intrinsic system are as a rule rapidly eliminated from circulation. It thus seems unlikely that phospholipid procoagulants will accumulate in circulation. If they do, the effect should consist in a general activation of the clotting system, provided the contact factors, in particular factor XIa, are also present in adequate amounts. Increased plasma levels of cephalins have nevertheless been described with less dramatic results in patients with hyperlipemia and with coronary heart disease (37). 

Free fatty acids may directly activate the contact factors (17, 47) and thus also contribute to an activated state of the clotting system. However, as will be discussed later, their effect on the platelets is much more pronounced, and in turn may lead to platelet-mediated contact activation. 

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