An extensive study and analysis of the concepts, classification, presentation, and nomenclature of chirality and lack of chirality in crystal structures and their constituents is presented. Oriented crystal structures are classified. The chirality rules for existence of molecular crystal structures are examined and the relation to segmentation and latent symmetry highlighted. The nomenclature o...

Optical activity measurements have been performed on the smectic blue phases (BPSm), which are a new kind of chiral liquid crystal. BPSm exhibit both three-dimensional orientational order, like the classical blue phases, and smectic positional order. Thus, they can be viewed as the three-dimensional counterpart of the twist grain boundary phases. A comparison with the optical activity of the cl...

Earlier studies in this laboratory (1) and by other workers (Z-4) have suggested that the effect of alkaline pH and urea on myosin resulted in major structural alterations in the molecule. Many of these studies were concerned with the attempt at the isolation of subunits or small polypeptide fragments by the treatment of myosin with high urea concentrations for long periods of time or by exposu...

HE question of the origin of petroleum has long been debated. In the history of this question, the fact of the optical activity of petroleum has occupied an important place. It was pointed out ( 1 , 2 ) by Walden that "inorganic" hypotheses for explaining the origin of petroleum did not account for its optical activity. Because of the increasing certainty that all petroleums possessed optical a...

Expressions corresponding to the transmission of a uniaxial optically active crystal platelet are provided for an optical axis parallel and perpendicular to the plane of interface. The optical activity is taken into account by a consistent multipolar expansion of the crystal medium response due to the path of an electromagnetic wave. Numerical examples of the effect of the optical activity are ...

The AGN 1ES1959+650 has been observed with the MAGIC telescope in September and October 2004, at the end of the commissioning phase. The MAGIC Telescope is currently the IACT with the lowest energy threshold, which is well suited for observations of weak γ-ray sources with soft spectra, like AGNs in a quiescent state. During the first observations by MAGIC, 1ES1959+650 was in a low state of act...

In a recent letter [1] the PVLAS collaboration reported the observation of optical rotation induced in vacuum by an external magnetic field. More recently [2] the same group reported also the observation of vaccuum birefringence under similar conditions. In this comment I wish to point out that the reported results are excluded at the 95% confidence level by a previous experiment [3] carried ou...

Micellar aggregates have been prepared from chloro­ phyll a. Whereas most detergents including non-ionic, zwitterionic and anionic ones, produce aggregates with long-wavelength shifted and enhanced Q Y absorption, the cationic detergents hexadecyl-trimethylammoniumbromide and hexadecyl-pyridiniumchloride produce complexes with opposite traits: The Q Y absorption is shifted to shorter wavelength...

Sergey Prosandeev,1,2 Andrei Malashevich,3 Zhigang Gui,1 Lydie Louis,1 Raymond Walter,1 Ivo Souza,4 and L. Bellaiche1 1Physics Department and Institute for Nanoscience and Engineering, University of Arkansas, Fayetteville, Arkansas 72701, USA 2Institute of Physics, South Federal University, Rostov on Don 344090, Russia 3Department of Applied Physics, Yale University, New Haven, Connecticut 0651...