Light scattering parameters

Deszczynski, M., Harding, S.E., Winzor, D.J. (2006). Negative second virial coefficients as predictors of protein crystal growth evidence from sedimentation equilibrium studies that refutes the designation of those light scattering parameters as osmotic virial coefficients. Biophysical Chemistry, 120, 106-113. 

Based on these indications, 0.1 M NaCl and 1.5 M NaCl were selected for measurement of the molar mass dependences of the light scattering parameters under two limiting solvent conditions respectively. The following scaling laws were found ... 

Light Scattering Parameters for a Cellulose Triacetate Polymer in Mixed Solvents ... 

The deviation from linearity in the NIR model s prediction capability for nylon66 yarns below 190°C was investigated with various crystalline, thermal, and laser light scattering parameters [16]. These deviations were normally small to moderate (<5°C) down to 185°C, but they consistently... 

In all the application examples presented here we did not discuss any methods and techniques for the measurements of light scattering parameters from cells, organelles and sub-cellular structures in general. This would be very useful in terms of defining the overall biomedical research and clinical context in which FDTD simulations could play a role, however, it was not part of our objectives. For a familiarization with some of the current progress in this field, the interested reader could refer to a recent publication by Boustany and Thakor [59] (and the references therein) as well as to some of the references included here [16-18]. 

This chapter is the narrowest in scope of any chapter in this book. In it we discuss a single experimental procedure and its interpretation. It is appropriate to examine light scattering in considerable detail, since the theory underlying this method is relatively unfamiliar to students and the interpretation yields information concerning a variety of polymer parameters. 

Equations (10.17) and (10.18) show that both the relative dielectric constant and the refractive index of a substance are measurable properties of matter that quantify the interaction between matter and electric fields of whatever origin. The polarizability is the molecular parameter which is pertinent to this interaction. We shall see in the next section that a also plays an important role in the theory of light scattering. The following example illustrates the use of Eq. (10.17) to evaluate a and considers one aspect of the applicability of this quantity to light scattering. 

In principle, the two-angle interval method can produce all CBC parameters within a single measurement channel, uniquely providing ceU-by-ceU hemoglobin concentration. The mean of the concentrations provides an alternative (and direct) measurement of MCHC. The method also provides an alternative HGB measurement, because HGB may be set equal to (RBC x MCV x MCHC)/1000. This method, like the basic light-scattering method, uses the same flow cell to measure platelets and ted cells with the result that the method is capable of providing the CBC parameters RBC, HGB, HCT, MCV, MCHC, MCH, and PLT. The method can also count a sample s white blood cells if the sample s red blood cells have been lysed. 

There are a number of applieations such as bottle and film where tough materials of high elarity are desired. The advent of MBS material has been a significant advance to meet the requirements. It has been found possible here to produce an additive with sufficiently different solubility parameters from the PVC for it to exist in the disperse phase but with a very similar refractive index to the PVC so that light scattering at the interface between the two phases is at a minimum. However, owing to differences in the formulation of PVC compounds, a particular MBS modifier may not have exactly the same refractive index as the PVC eompound. 

Witkowski, W.R., Miller, S.M. and Rawlings, J.B., 1990. Light scattering measurements to estimate kinetic parameters of crystallization. In Crystallization as a separation process, ACS Symposium Series, 438, 102. 

Theta temperature is one of the most important thermodynamic parameters of polymer solutions. At theta temperature, the long-range interactions vanish, segmental interactions become more effective and the polymer chains assume their unperturbed dimensions. It can be determined by light scattering and osmotic pressure measurements. These techniques are based on the fact that the second virial coefficient, A2, becomes zero at the theta conditions. 

This stipulation of the interaction parameter to be equal to 0.5 at the theta temperature is found to hold with values of Xh and Xs equal to 0.5 - x < 2.7 x lO-s, and this value tends to decrease with increasing temperature. The values of = 308.6 K were found from the temperature dependence of the interaction parameter for gelatin B. Naturally, determination of the correct theta temperature of a chosen polymer/solvent system has a great physic-chemical importance for polymer solutions thermodynamically. It is quite well known that the second viiial coefficient can also be evaluated from osmometry and light scattering measurements which consequently exhibits temperature dependence, finally yielding the theta temperature for the system under study. However, the evaluation of second virial... 

The parameter c can be easily determined by using viscometric measurements, which yield a relative number, or by performing, for example, light scattering measurements, which yield absolute values of c. Viscometric measurements are most commonly used because results are obtained quickly. However, this relative method is not equivalent to the absolute value of c LS and only absolute determination methods such as light scattering result in correct values of c. ... 

---