Effect of Low Concentrations

The sensitivity of fronts to the dynamics of small perturbations about the unstable or metastable states has been studied by Brunet and Derrida [61] for pulled fronts and Kessler et al. [227] for pulled and pushed fronts. The mean-field description of reacting and diffusing systems ceases to be valid for low values of the particle density p, values that correspond to less than one particle. This fact can be incorporated into the RD equation by introducing a cutoff for the reaction term. Such a cutoff strongly affects the front velocity. Throughout this section we consider for simplicity that space and time have been rescaled such that D = r =.  

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The threshold limit value—time integrated average, TLV—TWA, of chlorine dioxide is 0.1 ppm, and the threshold limit value—short-term exposure limit, STEL, is 0.3 ppm or 0.9 mg /m of air concentration (87,88). Chlorine dioxide is a severe respiratory and eye irritant. Symptoms of exposure by inhalation include eye and throat irritation, headache, nausea, nasal discharge, coughing, wheezing, bronchitis, and delayed onset of pulmonary edema. Delayed deaths occurred in animals after exposure to 150—200 ppm for less than one hour. Rats repeatedly exposed to 10 ppm died after 10 to 13 days of exposure. Exposure of a worker to 19 ppm for an unspecified time was fatal. The ingested systemic effects of low concentration chlorine dioxide solutions are similar to that of chlorite. 

Gemmel GC, Lorian V Effects of low concentrations of antibiotics on bacterial ultrastructure, virulence, and susceptibility to immunod-efenses Clinical significance, in Lorian V (ed) Antibiotics in Laboratory Medicine, ed 4. Baltimore, Williams Wilkins, 1996, pp 397-452. 

Forney, D.R. and D.E. Davis. 1981. Effects of low concentrations of herbicides on submersed aquatic plants. Weed Sci. 29 677-685. 

Cows fed fenvalerate in grain at 10 mg/kg diet for 4 days excreted most of the fenvalerate, essentially unchanged, in urine (Wszolek etal. 1981b). A secondary excretion route is feces, accounting for about 25% of the ingested dose. Milk accounted for 0.44 to 0.64% of the total excreted (Wszolek et al. 1980). Half-time persistence of fenvalerate in milk of treated cows is about 6.4 days (Frank et al. 1984). Effects of low concentrations (1.14 to 6.8 pg/L) of fenvalerate in milk of treated cows on newborn suckling calves are unknown and merit additional research (Frank et al. 

Cameron, G.R. and Foss, G.L. 1941. Effect of low concentrations of phosgene for 5 hours on 5 consecutive days in groups of different animals. Washington, DC British Embassy Defense Staff Porton report no. 2316, serial no. 63. (Cited in EPA 1986)... 

These studies, although few, suggest that exposure to photochemical oxidants can influence fertility and fecundity in animals and that the genera] health of newborn animals is much more likely to be impaired by exposure to oxidants than that of their parents. Whether the changes observed in reproduction variables can be related to mutagenic actions of ozone, discussed earlier, remains to be determined. In any event, it seems logical that effects of low concentrations of ozone and other photochemical oxidants on reproduction must be indirect and may be mediated by endocrine or ozone-biologic reaction products. 

Todd, G. W. Effect of low concentrations of ozone on the enzymes catalase, peroxidase, papain and urease. Physiol. Plant. 11 457-463, 1958. 

Young WA et ah Effect of low concentrations of ozone on pulmonary function. J Appl Physiol 19 765-768, 1964... 

The effect of low concentrations of urea (2M) on the large dihydroxy bile salt micelles is striking, while similar concentrations have no effect on the small trihydroxy or dihydroxy micelles. The effects of urea on micelle formation and aggregate size are undoubtedly complicated (10) and involve changes in solvent structure and thus hydrophobic bonding and hydration of polar groups. For large micelles of dihydroxy bile salt... 

Fontaras G, Kousoulidou M, Karavalakis G, Tzamkiozis Th, Pistikopoulos P, Ntziachristos L, Stoumas S, Samaras Z (2010) Effects of low concentration biodiesel blend application on modem passenger cars. Part 1 feedstock impact on regulated pollutants, fuel consumption and particle emissions. Environ Pollut 158 1451-1460... 

Waghorn GC. 1990. Beneficial effects of low concentrations of condensed tannins in forages fed to ruminants. In Akin DE, Ljungdahl LG, Wilson JR, Harris PJ, Ed. Microbial and Plant Opportunities to Improve Lignocellulose Utilization by Ruminants. New York Elsevier Science, pp. 137-147. 

This reaction scheme does not take into account the negative allosteric effect of sucrose concentrations above 200 mM or the positive allosteric effect of low concentrations of glucan. 

J. Liggins, N. Rodda, V. Bumage, J. Iley, and A. Furth, Effect of low concentrations of aminoguanidine on formation of advanced glycation endproducts in vitro, in F, 1998,424. 

The above refinements of the interpretation of earlier work have been brought about by two important developments, recognition from studies in trifluoroacetic acid that acetic and formic acids are nucleophilic (Peterson et al., 1965) and the use of 2-adamantyl tosylate as a reference point for SnI reactivity (Schleyer et al., 1970). These developments have led to sensitive ways of detecting nucleophilic assistance and have shown that solvolyses of secondary substrates in acetic and formic acids may be significantly nucleophilically assisted (Table 2). Previous arguments were based on less sensitive tests such as the rate-accelerating effect of low concentrations of added nucleophiles, which must be appropriately oriented and desolvated before they are able nucleophilically to assist in the displacement reaction (Peterson et al., 1967). 

Airway effects of low concentrations of sulfur dioxide Dose-response characteristics. Arch. Environ. Health 39(l) 34-42. 

Farris GM, Robinson SN, Gaido KW, et al. 1996. Effects of low concentrations of benzene on mouse hematopoietic cells in vivo. A preliminary report. Environ Health Perspect 104 (Suppl 6) 1275-1276. 

Bentin S, Collins GI, Adam N. Effects of low concentrations of enflurane on probability learning. Br J Anaesth 1978 50(12) 1179-83. 

McKee and Woolcott (1949) evaluated the effects of low concentrations of agent GB on 14 male volunteers. A single exposure to 0.6 mg GB/m for 1 min, or 0.06 mg GB/m for 40 min resulted in miosis and slight tightness of the chest within 24 h, signs and symptoms resolved in subjects exposed for 1 min, while more than 48 h was required for resolution in subjects exposed for 40 min. 

Johns, R.J. (1952). The effect of low concentrations of GB on the human eye. Research Report No. 100, Publication Control No. 5030-100 (CMLRE-ML-52). Chemical Corps Medical Laboratories, Army Chemical Center, MD. 

Central nervous system effects of low concentrations of local anesthetics are mainly sedation and confusion high concentrations are more likely to cause seizures (18). 

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