Huang scattering allows the measurements of the symmetry and strength of point defects produced by irradiations and constitutes a very sensitive method for observing the clustering that occurs during irradiations or annealings. In the present review, the principles and characteristics of the Huang scattering and recent investigations using this technique are described.
Small spherical virus is made up of a large number of identical protein subunits and a nucleic acid (RNA or DNA) . These proteins are arranged icosahedrally around the nucleic acid which is the core part of a virus particle. In some cases, viruses crystallize and make it possible to get high resolution X-ray diffraction pattern. Southern Bean Mosaic Virus (SBMV) now going to be mentioned is the typical example. The virus Particle with molecular weight 6.6×106 daltons has a shell of 180 protein subunits, arranged with T=3 icosahedral symmetry around a core of RNA with molecular weight 1.4×106 daltons. The crystal of space group R32 with cell dimensions a=318Å, α=64°0' diffracts X-rays beyond 3Å. Here are reported the symmety of spherical virus and the determination of the orientation of virus particle in the unit cell using characteriotic pattern of X-ray diffraction from the virus molecule with very high symmetry, as well as low resolution structure study of SBMV