Light scattering, laboratory

The authors thank the U.S. Army Research Office for financial support of this research at TCU and SMU. The light scattering and the thermal analysis experiments were conducted, respectively, by Dr. G.L. Hagnauer (Army Materials Technology Laboratory, Watertown, MA) and Dr. J.J. Meister (SMU). 

Stacey, K. A. The use of light-scattering for the measurement of the molecidar weight and size of proteins. In A laboratory manual of analytical methods of protein chemistry j Vol. 3, 245—275. Ed. R. Alexander u. R. J. Bloch, Pergamon Press 1961. 

To determine the shape of ribosomal proteins in solution, ultracentrifugation, digital densimetry, viscosity, gel filtration, quasi-elastic light scattering, and small-angle X-ray or neutron scattering have all been used. With each technique it is possible to obtain a physical characteristic of the protein. Combining these techniques should allow the size and shape of the protein to be characterized quite well. However, the values determined in various laboratories for the same ribosomal proteins differ considerably. To help understand some of the reasons we will initially discuss each method briefly as it relates to proteins and then review the size and shape of the ribosomal proteins that have been so characterized. 

Chen s laboratory used quasi-elastic light scattering to track migrating chemotactic bands of Escherichia coli in a buffer solution. The temporal development of the bacterial density profile is observed by the intensity of... 

The development and refinement of population balance techniques for the description of the behavior of laboratory and industrial crystallizers led to the belief that with accurate values for the crystal growth and nucleation kinetics, a simple MSMPR type crystallizer could be accurately modelled in terms of its CSD. Unfortunately, accurate measurement of the CSD with laser light scattering particle size analyzers (especially of the small particles) has revealed that this is not true. In mar cases the CSD data obtained from steady state operation of a MSMPR crystallizer is not a straight line as expected but curves upward (1. 32. 33V This indicates more small particles than predicted... 

Light scattering and absorption techniques have also been used, for example to obtain the index of refraction of the particles and then to compare these atmospheric measurements to laboratory measurements of NAT, NAD, etc. determined in laboratory studies. Adriani and co-workers (1995), for example, using light scattering in the visible, report four types of particles... 

It might seem at first glance that arriving at the dipole moment p of an ellipsoidal particle via the asymptotic form of the potential < p is a needlessly complicated procedure and that p is simply t>P, where v is the particle volume. However, this correspondence breaks down for a void, in which P, = 0, but which nonetheless has a nonzero dipole moment. Because the medium is, in general, polarizable, uP, is not equal to p even for a material particle except when it is in free space. In many applications of light scattering and absorption by small particles—in planetary atmospheres and interstellar space, for example—this condition is indeed satisfied. Laboratory experiments, however, are frequently carried out with particles suspended in some kind of medium such as water. It is for this reason that we have taken some care to ensure that the expressions for the polarizability of an ellipsoidal particle are completely general. 

Not only a nephelometer is needed to systematically study light scattering in the laboratory but also means for producing particles of known composition,... 

Quiney, R. G., and A. I. Carswell, 1972. Laboratory measurements of light scattering by simulated atmospheric aerosols, Appl. Opt., 11, 1611-1618. 

Acknowledgment. The research work of Jiang s group mentioned in this review has been supported by the National Natural Science Foundation of China (No. 28970183, 29374156, 29574154) and the National Basic Research Project-Macromolecular Condensed State. The light-scattering experiments were carried out in Prof. Chi Wu s laboratory at the Chinese University of Hong Kong. 

Acknowledgment for support of this research is made to the National Science Foundation (Grant CBT 8412604), the Blandin Foundation, the Graduate School of the University of Minnesota, the Minnesota Agricultural Experiment Station, and the University of Minnesota Computer Center. The authors are indebted to Professor V.A. Bloomfield, Department of Biochemistry at the University of Minnesota, in whose laboratories the light scattering measurements were carried out. 

Dusts, Mists, Aerosols and Fumes. The P-5 Digital Dust Indicator is another sensor currently available for use as a component of the Chronotox System. Suitable for the measurement of silica, lead fumes, pharmaceutical powders as well as many other types of particulates found in manufacturing or laboratory situations, the battery-operated P-5 uses the light scattering technique to measure dusts over a range of either 0.01-100 mg/m or 0.001-10 mg/m (Figure 6). 

One additional item of experimental evidence for the dimeric association of polyisoprenyl lithium was provided by a light scattering study (21), in n-hexane at 25°C., where it was found that the molecular weight of the terminated polymer was very close to one-half that of the active polymer. All of these data seem to leave no doubt that the active chain ends in the organo-lithium polymerization of styrene, isoprene and butadiene, in non-polar solvents, are associated as pairs, at least at chain-end concentrations of 10 2 M or less. This conclusion has also been supported by data obtained in four other laboratories (22,... 

Surface Light Scattering Adapted to the Advanced Undergraduate Laboratory 37... 

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