McFarland scale

Add the bacterial suspension to addition basal broth that contains a pH indicator (0.016% w/v bromcresol green) to obtain an optical density of McFarland Scale of 2 (Table 15.2). 

Table 15.2. McFarland scale standards used to estimate bacterial populations.

Prepare the McFarland scale by mixing 1% w/v sulfuric acid and 1% w/v barium chloride (BaCl2) according to Table 15.2. 

If the scale is used with the API Rapid GH system to prepare the bacterial inoculum, it is best to make McFarland Scale 1 to 4 in order to compare densities of the inoculum and determine the specific dilutions required. 

Gore AY, McFarland DW, Batuyios NH. Fluid-bed granulation factors affecting the process in laboratory development and production scale-up. Pharm Technol 1985 9(9) 114. 

This approach, originally proposed for binary response variables [McFarland and Cans, 1986], was extended to the quantitative biological responses y, scaled between zero and one [Rose and Wood, 1998] and then called Generalized Cluster Significance Analysis (GCSA). 

P. Jiang and M. J. McFarland, Large-scale fabrication of wafer-size colloidal crystals, macroporous polymers and nanocomposites by spincoating,/ Am. Chem. Sac., 126,13778-13786 (2004). 

Jiang, P. and McFarland, MJ. (2004) Large-scale fabrication of wafer-size... 

The development of toxicity equivalent factors (TEFs) for halogenated aromatic compounds, as proposed by Safe [34], is based on the observed common receptor-mediated mechanism of action of toxic halogenated aromatics. The relative toxicity of 2,3,7,8-TCDD is taken as unity on the TEF scale, and individual TEF values have been derived for the other stereoisomers including PCBs [38]. Recendy, a thermodynamic model for calculating the TEF values for PCBs was reported by Kafafi et al. [39] their model permitted calculation of the dissociation constants of complexes formed between the aryl hydrocarbon receptor and a PCB molecule. McFarland and Clarke [40] have argued that, as the toxicity of individual congeners varies over a range of 10, the determination of total PCB content is of... 

McFarland, A. W., Poggi, M. A., Bottomley, L. A., and Colton, J. S., Injection Moulding of High Aspect Ratio Micron-scale Thickness Polymeric Microcantilevers, Nanotechnology, 15, 1628-1632 (2004). 

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