Vapor action activity

Vapor Action Activity Evaluation in Non-Heating Formulation at Room Temperature Against Common House Mosquitoes (C. pipiens pallens)... 

Recently much attention has been directed at the development of devices to control mosquitoes by using products in ambient temperature devices because of their increased safety and ease of use, especially during outdoor activities. This development has resulted in a variety of fan powered mosquito vaporizers and associated formulations which are now being marketed. These devices have limitations in performance that are imposed by the insecticidal activity of the active ingredient used. In order to overcome some of these limitations, we undertook extensive research to find new pyrethroids with higher vapor action which were highly active against mosquitoes. 

One of the major characteristics of Metofluthrin is its vapor action at room temperature not seen in the existing pyrethroids D-allethrin and prallethrin. We will describe a fan type formulation ( a fan vaporizer ) where a motor turns a fan and the active ingredient is vaporized by the airflow from it at room temperature. 

Natural vaporization agents, where the active ingredient is formulated on paper or resin, and where it is vaporized without heating or use of power, are easy to use, so there is particular high potential for associated new developments in the field of mosquito control. Insecticides that can be used in formulations for this purpose must possess the characteristics of room temperature vapor action, high level activity, and a high degree of safety for mammals. Metofluthrin meets all of these requirements. 

The acaricldal activity of propargite occurs primarily through vapor action, while the phytotoxic effects seem to arise only from direct contact with the plant leaf or fruiting body. Conceptually, therefore, a delivery system vdiich could prevent contact with the plant, yet allow the acaricldal vapor to escape, would prevent phytotoxicity and allow use on sensitive crops. 

Volatilization — Volatilization is a physico-chemical phenomenon of particular interest to environmental managers as well as safety managers. It is the tendency of a material to transfer from a liquid phase (either pure or dissolved as in aqueous systems) to a gaseous phase (commonly air). The volatilization, or evaporation as it is more commonly called, is controlled by a number of factors, the most important of which are the vapor pressure of the material, temperature (vapor pressure increases with temperature), and air/material interfacial surface area, and the action of active mass transfer agents such as wind. 

Trigard 75 WP is a new insecticide with a unique mode of action and a unique triazine structure. It is a solid formulated as a wettable powder and is packaged in water-soluble bags. The active ingredient in Trigard has the common name cyromazine. Cyromazine is a triazine, but, unlike the well-known triazine herbicides, this compound has insecticidal properties and no herbicidal activity. Cyromazine has low mammalian toxicity and low vapor pressure. It is hydrophilic, so dermal penetration is expected to be... 

Natural attenuation should not be perceived as a permanent remedy or as a means to achieve certain cleanup levels, but rather as (1) an interim measure until future technologies are developed, (2) a managerial tool for reducing site risks, and (3) a bridge from active engineering (i.e., pump-and-treat, vapor extraction, etc.) to no further action. 

In developing the thermodynamic framework for ECES, we attempted to synthesize computer software that would correctly predict the vapor-liquid-solid equilibria over a wide range of conditions for multicomponent systems. To do this we needed a good basis which would make evident to the user the chemical and ionic equilibria present in aqueous systems. We chose as our cornerstone the law of mass action which simply stated says "The product of the activities of the reaction products, each raised to the power indicated by its numerical coefficient, divided by the product of the activities of the reactants, each raised to a corresponding power, is a constant at a given temperature. ... 

SPMD sample extracts, e.g., certain organochlorine pesticides (OCPs), are known to inhibit cholinesterase activity. Therefore, these results were not unexpected. However, it was surprising that a similar response was not observed with brain cholinesterase activity. It is possible that brain cells can more readily metabolize the chemicals, that the chemicals did not pass the brain blood barrier or that the effects occurred earlier in the exposure period, effectively allowing the activity to recover. Considering the numerous neurotoxic chemicals potentially entering aquatic ecosystems or present as airborne vapor phase chemicals, the neurotoxic mode of action related to exposure to contaminants is of increasing interest. Evidence presented in this work demonstrate that SPMDs concentrate members of this class of toxicants. 

Catalysts are porous and highly adsorptive, and their performance is affected markedly by the method of preparation. Two catalysts that are chemically identical but have pores of different size and distribution may have different activity, selectivity, temperature coefficient of reaction rate, and response to poisons. The intrinsic chemistry and catalytic action of a surface may be independent of pore size, but small pores appear to produce different effects because of the manner and time in which hydrocarbon vapors are transported into and out of the interstices. 

In crystallizing and drying salts, it must be remembered that the entire operation is usually carried out in the presence of air. The air contains three constituents that are more or less active as chemical reagents, viz., oxygen, carbon dioxide, and water vapor, and in many cases special precautions must be taken to protect the preparation from atmospheric action. Each case will suggest a somewhat different mode of procedure, and a few typical examples will be used to illustrate these. 

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