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The odor detection threshold is the lowest concentration of a certain odor compound that is perceivable by the human sense of smell.The threshold of a chemical compound is determined in part by its shape, polarity, partial charges, and molecular mass.
In pharmacology, an effective dose (ED) or effective concentration (EC) is the dose or concentration of a drug that produces a biological response. [ 1 ] [ 2 ] The term "effective dose" is used when measurements are taken in vivo , while "effective concentration" is used when the measurements are taken in vitro .
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TDS = k e EC. where TDS is expressed in mg/L and EC is the electrical conductivity in microsiemens per centimeter at 25 °C. The conversion factor k e varies between 0.55 and 0.8. [5] Some TDS meters use an electrical conductivity measurement to the ppm using the above formula. Regarding units, 1 ppm indicates 1 mg of dissolved solids per 1,000 ...
An equianalgesic chart can be a useful tool, but the user must take care to correct for all relevant variables such as route of administration, cross tolerance, half-life and the bioavailability of a drug. [5] For example, the narcotic levorphanol is 4–8 times stronger than morphine, but also has a much longer half-life. Simply switching the ...
Atmospheric pollutant concentrations expressed as mass per unit volume of atmospheric air (e.g., mg/m 3, μg/m 3, etc.) at sea level will decrease with increasing altitude because the atmospheric pressure decreases with increasing altitude.
The EC 10 and EC 90 concentrations to induce 10% and 90% maximal responses are defined similarly. There is a wide range of EC 50 values of drugs; they are typically anywhere from nM to mM. Hence, it is often more practical to refer to the logarithmically transformed p EC 50 values instead of EC 50 , where
Water chemists measure water impurities in parts per million (ppm). For understandability, hardness ordinarily is expressed in grains of hardness per gallon of water (gpg). The two systems can be converted mathematically.