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Parts-per notations may be expressed in terms of any unit of the same measure. For instance, the expansion coefficient of some brass alloy, α = 18.7 ppm/°C, may be expressed as 18.7 (μm/m)/°C, or as 18.7 (μ in/in)/°C; the numeric value representing a relative proportion does not change with the adoption of a different unit of length.
C h = Concentration, in mass per unit volume at altitude h and specified temperature T As an example, given an air pollutant concentration of 260 mg/m 3 at sea level, calculate the equivalent pollutant concentration at an altitude of 2800 meters:
Pollution regulations in the United States typically reference their pollutant limits to an ambient temperature of 20 to 25 °C as noted above. In most other nations, the reference ambient temperature for pollutant limits may be 0 °C or other values. 1 percent by volume = 10,000 ppmv (i.e., parts per million by volume).
The provisional tolerable daily intake (PTDI) for patulin was set at 0.43 μg/kg body weight by the FDA [3] based on a NOAEL of 0.3 mg/kg body weight per week. [3] Monte Carlo analysis was done on apple juice to compare exposure and the PTDI. Without controls or an action limit, the 90th percentile of consumers would not be above the PTDI.
Gaussian / ˈ ɡ aʊ s i ə n / is a general purpose computational chemistry software package initially released in 1970 by John Pople [1] [2] and his research group at Carnegie Mellon University as Gaussian 70. [3]
eV/c 2: ≡ 1 eV / c 2 = 1.782 661 84 (45) × 10 −36 kg [3] gamma: γ ≡ 1 μg = 1 μg grain: gr ≡ 1 ⁄ 7000 lb av ≡ 64.798 91 mg: grave: gv grave was the original name of the kilogram ≡ 1 kg hundredweight (long) long cwt or cwt ≡ 112 lb av = 50.802 345 44 kg: hundredweight (short); cental: sh cwt ≡ 100 lb av = 45.359 237 kg: hyl ...
In the metric system, a microgram or microgramme is a unit of mass equal to one millionth (1 × 10 −6) of a gram. The unit symbol is μg according to the International System of Units (SI); the recommended symbol in the United States and United Kingdom when communicating medical information is mcg .
Maximum contaminant levels (MCLs) are standards that are set by the United States Environmental Protection Agency (EPA) for drinking water quality. [1] [2] An MCL is the legal threshold limit on the amount of a substance that is allowed in public water systems under the Safe Drinking Water Act (SDWA).