Plant dose time

The most important factor is the dose-time relationship. The amount of a substance that enters or contacts a person is called a dose. An important consideration in evaluating a dose is body weight. Dose is the quantity of a chemical substance that a surface, plant, or animal is exposed to. Time means how often one is exposed to or the duration of exposure to a chemical substance. In simple terms, the dose-time relationship provides information on how much of the test substance is involved and how often the exposure to the test substance occurs. This relationship gives rise to two different types of toxicity of a chemical substance—namely, acute toxicity and chronic toxicity. 

The success of the Stellite reduction programme can be judged by comparing the figures given in Table i. The personnel doses on the KONVOI plants are in the range 100-300 man-mSv, whereas on the Stellited plant doses are from five to ten times higher. 

The plant s product was hexachlorophene, a bactericide, with trichlorophenol produced ns an intermediate. During normal operation, a very small amount of TCDD (2,3,7,8 telrachlomdib zoparadioxin) is produced in the reactor as an undesirable side product. TCDD is perhaps the most ]in(enl toxin known to man. Studies have shown TCDD to be fatal in doses as small as lE-9 times die body weight, it insolubility in water makes decontamination very difficult. Nonlethal doses of TCDD result in chloracne, an acne-like disea.se that can persist for several years. 

Rocksloh K, Rapp F-R, Abu Abed S, Mueller W, Reher M, Gauglitz G, Schmidt PC. Optimization of crushing strength and disintegration time of a high dose plant extract tablet by neural networks. Drug Dev Ind Pharm 1999 25 1015-25. 

In this work, a suspension culture of Taxus chinensis, which produces a bioactive taxoid, taxuyunnanine C (Tc), was taken as a model plant cell system. Experiments on the timing of jasmonates addition and dose response indicated that day 7 and 100 pM was the optimal elicitation time and concentration for both cell growth and Tc accumulation [8]. ITie Tc accumulation was increased more in the presence of novel hydroxyl-containing jasmonates compared to that with methyl jasmonate (MJA) addition. For example, addition of 100 pM... 

Lead at a lightly contaminated brownfield site has a concentration in soil of 600 mg/kg to a depth of 1 ft. The cleanup standard has been set at 400 mg/kg. Indian mustard, Bmssica juncea, will be planted, fertilized, and harvested three times each year for phytoextraction. Using small doses of EDTA, it is possible to achieve concentrations in the plant of 5000 mg/kg (dry weight basis), and harvestable densities of 2.721 (3 short tons) dry matter per crop. Estimate the time required for cleanup ... 

The traditional system of medicine of the Pacific Rim uses approx 80 species of Apiaceae, for instance, Centella asiatica (L.) Urban (Hydrocotyle asiatica L. centella, Indian Pharmaceutical Codex, 1955). The plant has been used in India since early times for skin diseases and as a diuretic. It has long been a popular remedy in India for leprosy and syphilis. However, large doses are said to have narcotic action. The plant was used also by the surgeons of Napoleon s army. 

Kampa et al. made the interesting observation that protocatechuic acid, which is found in grapes and red wine from Vitis vimfera (Vitaceae), showed a time- and dose-dependent inhibitory effect on cell growth of T47D human breast cancer cells at low concentrations (108). The phenolic compound is a potent inhibitor of topoisomerase I (109). The plant likely contains some germanacrolides because these sesquiterpenes are known... 

Biosensors are the analytical systems, which contain sensitive biological elements and detectors. Plant cells as a possible biosensors have natural structure that determinates their high activity and stability. Criteria in the screening of the plant cells as biosensors for allelopathy should be as under (i) Reaction is fast based on the time of response, (ii) Reaction is sensitive to small doses of analysed compounds or their mixtures and (iii) Methods of detection viz., biochemical, histochemical, biophysical (in particular, spectral changes in absorbance or fluorescence) are easy in laboratory and in the field conditions. The search of biosensors in active plant species is suitable to determine the mechanisms of action of biologically active substances or external factors of the environment (Roshchina and Roshchina, 2003 Roshchina, 2004 2005 c)). 

Acute biological effects of the Chernobyl accident on local natural resources were documented by Sokolov et al. (1990). They concluded that the most sensitive ecosystems affected at Chernobyl were the soil fauna and pine forest communities and that the bulk of the terrestrial vertebrate community was not adversely affected by released ionizing radiation. Pine forests seemed to be the most sensitive ecosystem. One stand of 400 ha of Pirns silvestris died and probably received a dose of 80 to 100 Gy other stands experienced heavy mortality of 10- to 12-year-old trees and up to 95% necrotization of young shoots. These pines received an estimated dose of 8 to 10 Gy. Abnormal top shoots developed in some Pirns, and these probably received 3 to 4 Gy. In contrast, leafed trees such as birch, oak, and aspen in the Chernobyl Atomic Power Station zone survived undamaged, probably because they are about 10 times more radioresistant than pines. There was no increase in the mutation rate of the spiderwort, (Arabidopsis thaliana) a radiosensitive plant, suggesting that the dose rate was less than 0.05 Gy/h in the Chernobyl locale. 

The two most critical factors in terms of air quality standards are duration of exposure and concentration. These two factors determine the exposure dose for a plant. In determining the response of vegetation, concentration is more important than time. A given dose presented to a plant in a short period has a greater effect than the same dose applied over a longer period. This suggests a threshold effect for plant populations and is probably related to the repair mechanisms inherent in bio-... 

In contrast to muscarine, atropine blocks these actions of acetylcholine and muscarine. Atropine is, therefore, an acetylcholine antagonist. It binds where acetylcholine binds and therefore prevents the binding of the latter but does not activate it. Two molecules cannot occupy the same binding site at the same time. Atropine is isolated from the plant Atropa belladonna. Extracts of this plant have been used for millennia for a variety of purposes. Although large doses are poisonous (Atropos is the name of the Fate who cuts the thread of life), small doses causes dilation of the pupils, a consequence of its action as an acetylcholine antagonist, and has been used for cosmetic purposes by women, hi Itahan, belladonna means beautiful woman. 

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