Repellents research

DEVELOPMENT OF A NEW MODEL FOR REPELLENT RESEARCH Chemical Feature-Based Considerations... 

There is a sustained effort to develop novel repellents driven partially by reports of deet toxicity despite its excellent safety record and for consumer preference—since 1998, the number of patents using natural repellents from essential oils has almost doubled every 4 years. Much of the search for new compounds has focused on plants— publications on the repellency of essential oils are increasing year on year. Funding for repellent research is also available. In response to the need to protect troops stationed overseas who regularly suffer from vector-borne disease from noncompliance with deet repellents, research funding support has been provided by Department of Defense s Deployed War-Fighter Protection Program for research into new repellents. ... 

Prior to the availability of deet in the 1950s, the most common topical repellent used was citro-nella oil. It was first reported as being a suitable repellent in the early 1900s and subsequent research focused on the development of botanical-based repellents, particularly, citronella and pyrethrum oil-based products. Much of the repellent research at this time concentrated on the use of botanical products and the development of techniques to prolong their effectiveness by mixing them with nonvolatile oils or greases. ... 

There are numerous ways to approach studies on chemical mixtures, and part of the challenge that remains in insecticide and repellent research is selecting the appropriate model for the analysis of the combined effects especially when information on the mode(s) of action are sometimes limiting. The more simplified and qualitative approach of Berenbaum and Laska offers options including variations of Loewe additivity and tests for significance (Figure 15.1). 

The public has a great desire for products that prevent the annoyance of biting insects and ticks, but that desire does not always translate into sensible use of those products. Insect Repellents Handbook, Second Edition summarizes evidence-based information on insect repellents to inform decisions by those involved with insect repellent research, development, and use. This authoritative, single-volume reference makes it possible for the individual to gain a working level of expertise about insect repellents in a timely manner, without having to search through the literature. 

Fermi had been fascinated by the discovery of the neutron by James Chadwick in 1932. He gradually switched his research interests to the use of neutrons to produce new types of nuclear reactions, in the hope of discovering new chemical elements or new isotopes of known elements. He had seen at once that the uncharged neutron would not be repelled by the positively-charged atomic nucleus. For that reason the uncharged neutron could penetrate much closer to a nucleus without the need for high-energy particle accelerators. lie discovered that slow neutrons could... 

Not surprisingly, much research in sharks, skates and rays has focused on the responses of sharks to human body odors. Human blood attracts sharks, while sweat does not, and urine was even slightly repellent (Tester, 1963). Practitioners use whale meat and mixtures of fish meal and fish oils as shark attrac-tants. In both carnivorous and herbivorous bony fish (Osteichthyes) smell deals with prey odors, social odors, and chemical stimuli in homing, and it is mediated by the first cranial nerve, the olfactory nerve. By contrast, taste serves in detection and selection of food and avoidance of toxic food, and it employs the facial, glossopharyngeal, vagal, and hypoglossal nerves. 

Crazier, E. R. (1991). Practical animal repellents for tree seedlings a success story. Forest Research Institute Bulletin 156,172-177. 

USGS researchers found that at least one of these chemicals was present in more than 80 percent of the rivers and streams examined. Half of the streams had seven or more of the chemicals, and about a third contained 10 or more. The most common substances encountered were coprostanol (a fecal steroid), cholesterol, N,N-diethyl-toluamide (an insect repellent), caffeine, triclosan (a disinfectant), tri(2-chloroethyl) phosphate (a fire retardant), and 4-nonylphenol (a product of the degradation of detergents). None of the chemicals found occurred in very high concentrations. For the less common chemicals, concentrations sometimes ranged as low as less than 1... 

The discovery of insecticidal carbamates arose independently from studies on the naturally occurring toxin physostigmine (86), and from research on insect repellants. The latter produced some pyrazoles of which isolan was an example (87) (68MI10701), derived from 3-methyl-5-pyrazolone which is made by condensation of hydrazine with ethyl acetoacetate. 

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