Mass optical density

Mass Optical Density of Smoke from NBS Smoke Chamber. Figure 5 shows the data for the mass optical density measured in the NBS smoke chamber for the flaming and nonflaming fires under static conditions. For MTL 1 and 2 samples, the MOD values in flaming fires are lower than in the nonflaming fires. For the other three samples, for which the MOD values are smaller, the trend is reversed. 

Figure 5. Mass Optical Density of Smoke Measured in the NBS Smoke Chamber for the Fiber Reinforced Composite Materials...

Figure 6. Correlation Between the Mass Optical Density Data for Fiber Reinforced Composite Materials Measured in the FMRC Small-Scale Flammability Apparatus for Flaming Fires and the NBS Smoke Chamber for Flaming and Non-Flaming Fires...

Instead of the specific optical density, the authors suggested that the optical density should be related to the mass of the material burnt away (mass optical density, MOD), It was theoretically and experimentally demonstrated that this value is less dependent on the thickness and density of the specimen. 

Replacing the exposed area by the mass loss (m), the mass optical density is... 

Fig. 4.11 Time plots of mass optical density (MOD) for various burning materials 1 PVC 2 poly(methyl methacrylate) i. red wood 4 Douglas fir marine plywood 5 a-cellulose 6 flexible polyurethane foam 7 plasticized PVC 8 neoprene Reprinted from Ref. 14. See footnote of Fig. 4.8...

The results are interpreted by using the maximum mass optical density in m kg as introduced by Seader et al. ... 

It should be noted that the mass optical density (MOD) could also be calculated in these large-size experiments and compared with those obtained with the COME-CON chamber (cf. Section 4.1.1.2). Taking the MOD of poly(methyl methacrylate) as unity, the values for all the involved polymers were between 1 and 1.46 in the large compartment and between 1 and 20 in the COMECON chamber. The order of the materials was also different. 

Ascertainment of smoke formation from a material is rather difficult due to the uncertainties in testing and evaluation. The measurement of smoke generation is to some extent dependent on the measurement technique i.e. whether smoke has been collected in a chamber or is streaming in a pipe whether gravimetric or optical evaluation is used and in the case of optical density, whether specific optical density, mass optical density, or a different measure is to be considered. 

Seader, J. D. and Chien, W. P. Mass optical density as a correlating parameter for the NBS density chamber. J. Fire and Flammability, 5, 151 (1974)... 

At the end of 24 hours of continuous process the system was shut down. The knowledge of flowed buffer volumes and of the optical densities inside and downstream each ultrafiltration stage allowed to estimate product distribution (see appendix for mass-balance equations and the calculation procedure). The content of each cell was recovered and ffeeze-dried in order to be stored and used for subsequent kinetic experiments. A schematic flow-sheet of the whole procedure is illustrated in figure 1. 

Maximum residue limit Mass spectrometry Tandem mass spectrometry Material safety data sheet North American Free Trade Act N-Hydroxysuccinimide Nitrogen-phosphorus detection Neomycin phosphotransferase II Optical density Office of Plant Protection and Quarantine... 

Generation rate of smoke can be quantified by measuring the mass of smoke and/or the optical density of smoke, D, defined as ... 

These optical probes are the most universally applicable in situ devices for on-line biomass monitoring up to now [15,16]. Konstaninov et al. [17] tested several absorbance and scattering sensors for real-time biomass concentration monitoring in mammalian cell cultivation processes and Hatch and Veilleux [18] compared optical density probes with oxygen uptake rates, packed cell volume, and off-line cell mass monitoring in commercial fed-batch fermentations of Saccharomyces cerevisiae [19]. In order to minimize influencing effects, special chemometric data treatment is necessary [20]. 

Since the obtained optical density (intensity of stain) per mass unit of a protein differs depending on its nature and the staining method, for some commercial available protein mixtures the composition is given, which produces staining a homogeneous picture by Coomassie. 

The conservation of mass equations are used with refractometric optics. The absorption optical system will give absorbance (optical density) which is directly proportional to concentration. Unless conservation of mass equations are used, one can only obtain concentration differences from refractometric optics. The Rayleigh optical system will give information proportional to cr — cTm thus Equation 20 or 23 would have to be used to obtain cTm. Note also that the initial concentration c0 is needed. This must be measured by differential refractometry, by boundary-forming experiments, or from ultraviolet light absorption. 

Changes in biomass concentration throughout the fermentation process were followed by optical density (OD) measurement at 580 nm using an Ultrospec 2000 Spectrophotometer. Quantitative biomass concentration was assayed applying microbiuret cell protein determination (16). Biomass concentration was expressed in grams of dry matter per liter of fermentation broth by assuming a twofold multiplication constant for microbial protein to cell mass. For carbon balance calculations, the elemental composition of C. saccharolyticus was assumed to be CH1 8O0 5N0 2 (24.6 mg/mmol). 

The output of the disk centrifuge, a curve of optical density versus time, can be converted to a particle size distribution by using Stokes law to convert the time axis to a size axis and by the application of light-scattering theory to calculate the particle frequencies from the optical densities. As described herein, one obtains mass distributions with linear size increments or the equivalent area distributions with logarithmic increments. 

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