We demonstrate that a newly developed instrument which measures all polarization and intensity information contained in differentially and elastically scattered light has valuable applications in biology. The polarization states of light scattered differentially from suspensions of biological scatterers are shown to contain structural information about those systems. The scatterers are discussed in the context of a 16 component matrix which completely characterizes the scattering process. The instrument and method are described in terms of the corresponding matrix algebra. We also discuss the use of the instrument as a device for distinguishing between closely related structural systems and as a tool for following time-dependent structural changes. A technique has recently been developed (1)

Large area single crystals of Cu2O were grown by the process of high temperature annealing. Cu2O was prepared in finely polycrystalline form by the complete oxidation of Cu plate in air at temperatures of 1020°C to 1050°C. Subsequent annealing of the polycrystalline plates at higher temperatures allowed secondary recrystallization to occur. Single-crystal grains having surface areas larger than 1 in.2 were grown consistently on Cu2O plates having thicknesses of 0.010 in. to 0.060 in. In some cases, entire polycrystalline plates were transformed into single crystals, and as a result, individual single crystals having surface areas of 3 in.2 and larger were obtained. The annealing temperature and the annealing time were found to depend markedly on the plate thickness. Thick plates required lower temperatures and longer annealing times than the thinner plates. X-ray analysis of the large grains verified that they were single crystals without excess strain, and indicated preferred orientation, with the (211) and (311) planes predominating. Resistance profile measurements at room temperature on quenched samples showed that a variation in resistance exists through the thickness of the plate.

No abstract

The intrinsic birefringence of multiple-coiled DNA is computed in terms of an equally dense array of parallel DNA molecules. The birefringence for n times-coiled DNA molecules is given by [Formula: see text] where beta(o) = 0, beta(i) = tan(-1) (p(i)/2pir(i)), p(i) = period of the i(th) helix coil and r(i) = radius of i(th) helix coil. The formula is applied to two cases of helically coiled DNA in biological material and found to agree quantitatively with experimental results.

No abstract