Defined medium definition

Media Definitions. Sample preparation media were defined by the participants to assist laboratories in selecting the appropriate protocol for a specific sample. These definitions were intended to encompass the continuum of wastes and environmental materials, to reduce overlap between individual medium definitions, and to reflect the scope of the protocols. The following media definitions were developed ... 

Over the past 40 years, there have been significant advances in synthetic nutrient medium formulations. Application-specific scientific and regulatory concerns have propelled investigators toward the development of defined media. There appears to be an inverse correlation between the extent of medium definition and its range of... 

C (250° F) on a filtering medium. The sampling apparatus, however, may have to be modified to conform with the states definition of a particulate. For example, a state may define pai ticulate as any material collectible at stack conditions, a definition that would allow the filtering medium to be located in the stack. 

The ideal soil is defined as a loose, granular medium that is devoid of cohesion but possesses internal friction. In contrast, an ideal cohesive medium is one that is devoid of internal friction. Real soils generally fall between the foregoing two limiting definitions. 

Section 3.2 begins with pfCj definitions and a brief description of the state-of-the-art pfCj measurement methods, stressing the needed accuracy, especially with molecules which possess very low aqueous solubility. In a prachcal way, the ioniza-hon constant is treated as a property of the molecule, usually defined at 25 °C in a nonbuffered medium of 0.15 M potassium (or sodium) chloride aqueous... 

It is very often necessary to characterize the redox properties of a given system with unknown activity coefficients in a state far from standard conditions. For this purpose, formal (solution with unit concentrations of all the species appearing in the Nernst equation its value depends on the overall composition of the solution. If the solution also contains additional species that do not appear in the Nernst equation (indifferent electrolyte, buffer components, etc.), their concentrations must be precisely specified in the formal potential data. The formal potential, denoted as E0, is best characterized by an expression in parentheses, giving both the half-cell reaction and the composition of the medium, for example E0,(Zn2+ + 2e = Zn, 10-3M H2S04). 

When we think of paper we think of it primarily as a writing and printing medium, and then perhaps as a wrapping and packaging material. However, because many other products—for example, tissue, board, filtration media, surgical wrap, etc.—are made by essentially the same process, a broader definition is more appropriate. For the purpose of this text therefore, paper will be defined in... 

Hydraulic conductivity is defined as volume units per square unit of medium face per unit of time under a unit hydraulic gradient (often expressed as units3/units2/time). However, many variations of this definition are used for convenience. For example, in the United States hydraulic conductivity is referred to in terms of gallons per day per square foot or, by the U.S. Geological Survey, as square feet per day. 

The effective molarity (EM) is formally the concentration of the catalytic group (RCOO- in [5]) required to make the intermolecular reaction go at the observed rate of the intramolecular process. In practice many measured EM s represent physically unattainable concentrations, and the formal definition is probably relevant only in reactions (which will generally involve very large cyclic transition states) where the formation of the ring or cyclic transition state per se is enthalpically neutral, or in diffusion-controlled processes. For the formation of small and medium-sized rings and cyclic transition states the EM as defined above contains, and may indeed be dominated by, the enthalpy of formation of the cyclic form. This topic has been discussed briefly by Illuminati et al. (1977) and will be treated at greater length in a future volume in this series. 

In most instances the test system will be self-evident (e.g., the animal to which the test article is administered or applied). Studies with micro-organisms, however, sometimes present difficulty in defining the test system. In the case of the Ames test, for example, the test system is not merely the colonies of salmonella or yeast, but includes in addition the culture medium, metabolic activation agent (if any), biotin, histidine, and buffer (if any). The last sentence of the definition makes it clear that untreated control groups also meet the definition of test system even though a test or control article is not administered or applied to such groups. 

Many of these effects of radioactive decay can be treated quantitatively using G values. Historically, the G value was defined as the number of molecules or species decomposed or formed per 100 eV of absorbed energy. A newer (SI) definition of the G value is the number of moles of molecules or species formed or decomposed per Joule of energy absorbed. (Note that 1 mol/J = 9.76 x 106 molecules/100 eV.) The G values depend on the radiation and the medium being irradiated and its physical state. Table 19.1 shows some typical G values for the irradiation of neutral liquid water. 

The quantity pH has been defined at least three different ways (2). S0rensen s (16) original definition was pH = —log[H+]. Those using an ionic medium scale may use this definition since one can usually measure —log[H+] = —log H+ rather accurately. 

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