Units of specification

Typical Units of Specific Rates For order Ot, typical units i... 

One particularly widely used test is the National Bureau of Standards (NBS) smoke chamber test. This provides a measure of the obscuration of visible light by smoke in units of specific optical density. The NBS smoke test can be run in either of two modes ... 

In other words, 1 MBq of tritium contains about 3 ng of tritium. Thus, an important feature of radionuclides becomes apparent—we routinely work with extremely small quantities of material. Pure samples of radioisotopes are called carrier free. Unless a radionuclide is in a carrier-free state, it is mixed homogeneously with the stable nuclides of the same element. It is, therefore, desirable to have a simple expression to show the relative abundances of the radioisotope and the stable isotopes. This specification is readily accomplished by using the concept of specific activity, which refers to the amount of radioactivity per given mass or other similar units of the total sample. The SI unit of specific activity is Bq/kg. Specific activity can also be expressed in terms of the disintegration rate (Bq or dpm), or... 

Several electrolytic-conductivity detectors are produced (Table 3.5). The Laboratory Data Control Model 701 Conducto Monitor (Fig.3.59) may be operated in either a differential mode or an absolute mode. It provides direct readout in units of specific conductance and differences as small as 0.01% in the differential mode between the carrier and the carrier plus solute can be measured. The dynamic range of linearity is 0.01-100,000 pSl 1 /cm. The detector can function in solvents ranging from distilled water to concentrated salt solutions without the necessity of changing the cell. The volume of the cell is 2.5 pi, and the nominal cell constant is 20 cm-1. This type of detector is of use mainly in high-speed ion-exchange chromatography for the detection of ionic species. 

The units of specific impulse are seconds. There is some confusion with respect to these units when the English system is used. As stated above the specific impulse is defined as the thrust divided by the weight flow rate ... 

Units of specific moles sec i liters liters liters" ... 

Figyre 11. Activities of enzymes that remove inappropriate bases from DNA- The specific activities of uracil DMA glycosidase (black bars) and thymine ONA glycosidase (open bars) were measured in extracts of colon mucosa. Extracts were prepared from seven normal human subjects [subjects A to Q. To the extracts were added synthetic strands of double-stranded DNA that contained a mismatched U G pair or a mismatched T G pair. The unit of specific activity used was nmol/mg protein/min. The resuJts show, at least in tissue extracts, that the removal of U occurs at a dramatically greater rate than the removal ofT-... 

The specific volume of any compound is the inverse of the density, that is, the volume per unit mass or unit amount of material. Units of specific volume might be ft / Ibm, ftVlb mole, cmVg, bbl/lbm, m /kg, or similar ratios. 

Note how the units of specific gravity as used here clarify the calculations. 

Surface area is important in all applications where the process is surface-dependent like in mass and heat transfer, flow through packed beds or fluidization. Activity of drugs, setting time of cement and effectiveness of cracking catalysts are just three examples of direct dependence on specific surface. Some such materials, like fillers or catalysts, are often specified in units of specific surface rather than in particle size and its distribution. Specific surface also offers some practical advantages, in favourable cases, in the ease and speed of measurement and also in that it gives a... 

TABLE 2.5 Conversion Factors for Units of Specific Energy... 

Typical Units of Specific Rates For order a, typical units are Kc (L/g mol) s and s when first order... 

Units of specific heat that are obtained from the polynomial expression... 

The specific surface area of a soil clay sample is the combined surface area of ail the particles in the sample as determined by some experimental technique and expressed per unit mass of the sample. Thus the SI units of specific surface "area are square meters per kilogram. As its definition implies, specific surface area is an operational concept. The numerical value found for a given soil clay depejadSjaa Jdtud, fi3 ... 

Specific heat capacity is the amount of heat required to change the temperature of 1 g of a substance by 1K. The units of specific heat capacity are J g K . ... 

Taking into account concentration of the polymer, c, we get two more quantities, inherent and reduced viscosity. These quantities have the unit of specific volume. In the limit of infinite dilution, reduced viscosity represents intrinsic viscosity [77]. 

Where is the thermal conductivity of the barrel, 3T/3rb is the temperature gradient in the barrel at the polymer/metal interface. If occurs over unit length, then represents the power per unit volume. Thus, if q is divided by the thickness, t, over which the heat conduction occurs, it attains the units of specific power, just as q. ... 

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