This study revisits the classical x-ray diffraction patterns from hydrated, noncrystalline fibers originally used to establish the helical structure of DNA. We argue that changes in these diffraction patterns with DNA packing density reveal strong azimuthally dependent interactions between adjacent molecules up to approximately 40 A interaxial or approximately 20 A surface-to-surface separation...

Knowledge of three-dimensional protein structures is one of the foundations of protein design and protein engineering. Nuclear magnetic resonance spectroscopy was recently introduced as a second method for protein structure determination, in addition to the well-established diffraction techniques with protein single crystals. This new approach enables one to carry out detailed structural studie...

Local atomic arrangements were investigated as a model of amorphous iron in terms of Voronoi polyhedra for a dense random packing of hard spheres with and without relaxation. The structure of liquid iron was also simulated in a computer. As a result of relaxation, the frequency of five-edged faces increases at the expense of others, particularly the three-and seven-edged components. The amorpho...