Repellent properties

Albone [88] has reviewed the literature on anal sac secretions up to the early 1980s. Organosulfur compounds are particularly plentiful in many of these secretions and are responsible for their offensive odors. In general, predator odors seem to be repulsive to potential prey. Epple et al. [89] have speculated that the reason for the repellent properties of the feces and urine of carnivores could be diet related. It would be logical to argue that organosulfur compounds derived from a protein-rich diet could be a cue by which prey can distinguish a potential predator. The results so far are consistent with this hypothesis [90]. 

Evidence of repellent properties in camip, Nepeta cataria, to flies and cockroaches was observed in preliminary studies.This study compared catnip essential oil obtained by steam distillation and elemol (Fig. 8), a major constituent of osage orange essential oil, to current commercial repellents. These comparative studies found both the camip steam distillate and elemol to be as good, and in some cases better, at repelling house... 

ThorseU W, Mikiver A, Tunon H, Repelling properties of some plant materials on the Ac Ixodes ricinus L, Phytomedicine 13 132—134, 2006. 

It is doubtful whether the insect uses pederin for defensive purposes, because it acts on the skin of animals only when it is crushed and not through mere contact with the insect, even if prolonged. It also has neither insecticidal nor repellent properties (92). However, it causes epidermic necrotization as acute pederosis and desquamation as chronic pederosis on human skin. On the other hand, it stimulates bedsore cicatrization in lower doses and leads to complete healing. Application to mouse skin produces dermatitis with necrosis or huge edema, and the damaged tissue is reconstituted with a permanent loss of hair. 

Figure 1. Silicone structure consists of Si—O—Si backbone that provides thermal stability of the material. Hydrocarbon radicals that attach to silicon atoms provide water-repelling properties.

Stylosanthes hamata and scabra, which are highly productive and nutritious species of tropical pasture legumes, are covered with glandular trlchomes. The trlchomes secrete a viscous secretion that immediately Immobilize larvae of the cattle tick, Boophllus mlcroplus (39). Ticks have a natural tendency to climb plants, and wait for a host animal. The secretion has no repellant properties, so that ticks do not attempt to seek alternative plants. In addition to Immobilizing the larvae, the plants produce an unidentified volatile compound(s) that poison the larvae, within 24 hours. 

The difference between the ability of a hydroxyl and an amino group to reduce the intensity of the maximum produced by a nitro group may be due to the stronger electron repelling property of amino groups. 

Waxes also serve a diversity of other functions related to their water-repellent properties and their firm consistency. Certain skin glands of vertebrates secrete waxes to protect hair and skin and keep it pliable, lubricated, and waterproof. Birds, particularly waterfowl, secrete waxes from their preen glands to keep their feathers water-repellent. The shiny leaves of holly, rhododendrons, poison ivy, and many tropical plants are coated with a thick layer of waxes, which prevents excessive evaporation of water and protects against parasites. 

A substance that, because of its physicochemical nature, will not mix or blend with another substance.. All hydrophobic materials have water-repellent properties due largely to differences in surface tension or electric charges, e.g., oils, fats, waxes, and certain types of plastics. Silicone resin coatings can keep water from penetrating masonry by lining the pores, not by filling them they will not exclude water under pressure. 

Folklore The oil has insect repellent properties. The herb is used in cooking to impart a lemon flavour to the food. It is an ingredient of a melissa cordial made by Carmelite nuns as well as being included in other liqueurs such as benedic-tine and chartreuse. Traditionally the herb was seen as an antidepressive. (Bown, 2003 British Herbal Medicine Association, 1983 Graenwald et al., 2002 Tierra, 1998). 

Lukevics reports34 that silylation of 2-dibutylaminoethanol (2a) enhances its insect-repellent activity against X. cheopis (Table 3). For silyl derivative 2c the coefficient of repellent action reaches 99% at a dose of 5 g/m2. This effect is accompanied by prolongation of the repellent action. According to Lukevics, the activity of silyl derivatives 2b-2e cannot be explained by hydrolysis alone, because this process forms less active compounds. It appears that the repellent properties are concentrated within the molecule of the organosilicon compound itself. 

Many approaches comprise some attractive features with respect to specific binding to certain integrins and long-term stability of the produced surface coatings. In order to ensure the exclusive interaction of the cells with the recognition sites presented (and not with unspecifically adsorbed proteins), the matrix (i.e., the background) must possess protein-repellent properties. 

When poly(ethylene oxide) (PEO) silane was grafted onto oxidized PDMS stamps it acts as a protein repellent layer. This property was utilized to design a flat stamp with regions that can attract proteins (nonmodified PDMS) and regions modified with PEO that have protein-repellent properties. The local modification of native PDMS was conducted by oxidation in 02-plasma with the application of a metal mask (areas that were covered by the mask were not oxidized and not modified). Proteins (immunoglobulin G, IgG) were transferred successfully to the glass substrates... 

The treatment of textiles with organohydrosiloxanes with phenyl, ethyl and butoxyl groups in the backbone helps to give them both waterproof and stain-repellent properties. An oligomer of the common formula ... 

An introduction of small amounts of ethers of orthotitanium acid into solutions or emulsions of waterproofing silicone liquids increases water-repellent properties of these liquids. 

In addition to toxic and repellent properties, lupin alkaloids have a number of pharmacological activities.15,47,52... 

Wink, M. 1984. Chemical defense of lupins. Mollusc-repellent properties of quinolizidine alkaloids. Z. Naturforsch. 39c, 553-558... 

Triorganotin compounds have also been used experimentally in controlled-release formulations to control the infective snail vector in the debilitating tropical disease schistosomiasis (bilharzia) and to control mosquitoes in stagnant ponds (103). As yet, the large-scale use of such methods has little support in the host third world countries where these problems are most severe. Tributyltin chloride has been used to confer rodent-repellent properties on wire and cable coatings (104). 

Finally, we note that in a very recent work Heuberger et al. investigated protein-resistant copolymer monolayers of PEG grafted to poly(L-lysine) (PLL) (PLL-g-PEG) in terms of the role of water in surface grafted PEG layers [159], interaction forces and morphology [160], compressibility, temperature dependence and molecular architecture [161], PEG is often used in biomedical applications in order to create protein-resistant surfaces but the mechanisms responsible for the protein-repelling properties of PEG are not fully understood. 

A number of various esters of cellulose are known, for example, propionate and butyrate and mixed esters such as acetate-butyrate, propionate-isobutyrate, and propionate-valerate. The mixed esters have found use in plastic composites when good grease- and water-repelling properties are required. 

Figure 9.13 indicates the typical change in reflection spectra for the thionine reductant system in a PVA matrix coated on paper with a water-repellent property.36 The blue color, with an absorbance of approximately 1.0 at 610nm, faded rapidly upon irradiation with visible light this absorption gradually recovered when the material was stored in a desiccator at constant relative humidity in the absence of light. The recovery was complete except when the exposure was to an extremely intense light. 

Carboxyatractyloside has not yet been tested for either insecticidal or insect repelling properties. We have observed that cocklebur does not appear to be the subject of massive infestations by insects, and we anticipate that the plant contains substances that repel, or are toxic to insects. And, as we shall see shortly, the effects of carboxyatractyloside on enzyme systems are noteworthy and further suggest the possible use of carboxyatractyloside as an insecticide. 

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