. Biophysical research methods. Biophysics -- Research. 70 E. G. PICKELS weights above several thousand. In the case of paucidisperse prepa- rations that would show multiple boundaries in the absence of dif- fusion, molecular weights generally must be well above 10,000 to ac- complish noticeable differentiation. Also, the smaller the particle size, the greater the uncertainty of differentiating the amount of boundary spreading due to diffusion and the amount due to inhomo- geneity of sedimentation rate, and the greater the necessity of acquir- ing separate diffusion data for making the compari
. Biophysical research methods. Biophysics -- Research. 70 E. G. PICKELS weights above several thousand. In the case of paucidisperse prepa- rations that would show multiple boundaries in the absence of dif- fusion, molecular weights generally must be well above 10,000 to ac- complish noticeable differentiation. Also, the smaller the particle size, the greater the uncertainty of differentiating the amount of boundary spreading due to diffusion and the amount due to inhomo- geneity of sedimentation rate, and the greater the necessity of acquir- ing separate diffusion data for making the comparison. Generally speaking, diffusion can hardly be considered a negligible factor in the analytical centrifuge until a size range at least as high as that of the larger viruses (above 50 m/x roughly) is reached. I00-- < or o o o <3 a: a Boundary positions i I 1. Plateau region 4 0 DISTANCE FROM MENISCUS, cm. Fig. 1. Three curves illustrating the concentration distribution of slowly sedimenting material at eighty- minute intervals after boundary has cleared meniscus sufficiently to permit measurements of position. As illustrated in Figure 1, the general character of the sedimenta- tion process in the centrifuge and the method of analysis are similar to those described for a gravitational field, except for certain condi- tions imposed by the nonuniformity of the centrifugal field. Since the field is radial, the containing vessel or cell in an analytical centri- fuge is made sector-shaped (SO), having two fiat walls that, if ex- tended, would intersect along the axis of rotation, while the other two side walls are perpendicular to the axis. Thus, particles origi- nally close to any of these walls continue during sedimentation to pur- sue an average course parallel to the wall, so that there is no sedimen- tation against or away from the walls to introduce convective dis- turbances. Also, since in their sedimentation the particles on the. Please note that these imag
Size: 1842px × 1356px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookcollectionameri, bookcollectionbiodiversity
