Contact Agents

Kontakt-(ab)dnick, m. contact print(ing). -fiache, /. surface of contact, -gift, n. contact poison, -korper, m. contact body (as a catalyst pellet) contact substance, catalyst, -mittel, n. contact agent, catalyst, -ober-fiache, /. contact surface, -russ, m. contact black, -schraube, /. contact screw, -sub-stao2, /. contact substance, catalyst, -ver-... 

Example 1 Citrus oil or citrus root products can Indeed kill slugs if they are applied as a contact agent or act as a slug repellent. Although some patents have been issued on the use of citrus oil as a slug control agent, such control with a contact agent is difficult and the chemical compositions of citrus oil and root exudate are ill-defined. Other obstacles for commercialization of citrus oil are (1) market size is too small to justify the development cost, and (2) an effective delivery method has yet to be developed. 

Larger and more powerful than a regular squirt gun, this device also holds a greater quantity of "ammo" in a large bottle attached to the gun. Its more powerful spray is better for delivery of contact agents than the standard squirt gun, but it is still far from optimal, and the target receives a +1 bonus on his save. 

When the addition of chlorine to ethylene is carried out in the vapor phase and in the presence of metal contact agents, higher proportions of 1,2-dichloroethane are obtained. Equimolecular proportions of chlorine and ethylene reacting at 80-100°C in the presence of copper or iron give about 90-95 per cent of the theoretical yield of dichloroethane. The reactions may be carried out in tubes that are packed with shavings or particles of the preferred metal. When small amounts of dichloroethane are recirculated to the reaction zone, the exit gases can be scrubbed more easily. In many plants, the concurrent formation of polychloroethanes is considered desirable, for such compounds are subsequently submitted to dehydrochlorination and yield desired chloroolefins. 

When ethanol acts as solvent, and NaOH and sulfur are used as contact agent, this overall reaction can be divided into the following steps ... 

It can be seen that side reaction occurs when CS2 and NaOH are surplus in solution. When sulfur acts as contact agent, the overall reaction takes place quickly. But sulfur can react with phenylisothiocyanate to form benzothiazole mercaptan ... 

Pine oil frothers can be synthesized by adopting pinene as raw material in the presence of acid as a contact agent. Take a-pinene for example, and the synthetic reaction of 2 oil can be given as follows ... 

During contact activation with sephadex or zymosan the enzyme is (partly) adsorbed. For this to occur, preparatory biochemical steps are apparently necessary, for the adsorption gnto and activation by sephadex does not take place at 0°. Efforts to elute the active enzyme from the contact agent have so far not met with success. By gel chromatography purified enzyme preparations have been obtained but the results have been varying and the yields were poor. 

Anaphylatoxinogen is present also in guinea-pig serum, but not in human, bovine or dog blood (Schwoerer, cited from Vogt, 1967 a). This is the reason why no AT is detected when sera of these species are incubated with contact agents or cobra enzyme. 

Dias da Silva and Lepow (1967) have recently produced AT-like activity from purified complement factors of human serum. The product showed, however, differences to AT formed by contact in rat or guinea-pig plasma. This and the fact that generation of AT activity in humanplasma by contact agents or cobra venom has been unsuccessful raise doubt whether the product of this complement reac-... 

Blister agents or vesicants are chemicals that cause blister or vesicle formation upon dermal contact. Agents such as mustards or lewisite have been used as CWAs in the past (Yu et al., 2003). Although these agents have less toxicity than nerve agents, they cause prolonged... 

Buruli Toxins (Mycolactones A/B Necrotic Contact Agents)... 

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