From the branches of Microtropis japonica (Celastraceae), seven phenolic alcohol glucosides, named microtropins J-P (1-7), were isolated. The 6-position of glucose was esterified with 2-ethyl-2,3-dihydroxybutyric acid. Microtropin K (2) was hydrolyzed under a mild basic condition to give methyl (2S,3R)-2-ethyl-2,3-dihydroxybutyrate, whose absolute structure was determined by the comparison of N...

A VLA survey of nearby LINER galaxies at 15 GHz has revealed the presence of a compact radio core in many sources. The cores seem to be correlated with the optical activity. Follow-up VLBA observations of the ten brightest sources confirm that these cores have brightness temperatures> 10 Kelvin, thus confirming their AGN nature. The two brightest radio sources show extended jet-like structures ...

An angular displacement-enhanced heterodyne polarimeter has been employed to investigate the interplay between trifluoroethanol (TFE) and glycerol on the thermal denaturation of type I collagen. The concentration of the collagen solution was fixed at 0.341 (mg/mL), and was heated from 25 °C to 55 °C. TFE solutions with concentrations of 5%, 10%, 15%, 20%, 40% and 80% (v/v) were prepared and the...

Antirelaxation surface coatings allow long spin relaxation times in alkali-metal cells without buffer gas, enabling faster diffusion of the alkali atoms throughout the cell and giving larger signals due to narrower optical linewidths. Effective coatings were previously unavailable for operation at temperatures above 80 °C. We demonstrate that octadecyltrichlorosilane OTS can allow potassium or ...

The identification of a universal biosignature that could be sensed remotely is critical to the prospects for success in the search for life elsewhere in the universe. A candidate universal biosignature is homochirality, which is likely to be a generic property of all biochemical life. Due to the optical activity of chiral molecules, it has been hypothesized that this unique characteristic may ...

We analyse the optical activity in twisted dimers, the meta-atoms of a chiral metamaterial, by introducing a simple yet accurate model for the coupling between them. The near-field interaction coefficients are derived from a Lagrangian model and include the effects of retardation, whereas the far-field radiation is based on a multipole expansion. We show that the optimum twist angle varies with...

Following the recent observation of a large second-harmonic intensity difference from a monolayer of chiral molecules with left and right circularly polarized light, the scattering theory is generalized and extended to predict linear and circular intensity differences for the more versatile sum-frequency spectroscopy. Estimates indicate that intensity differences should be detectable for a typi...

We propose a model to describe a gas of pyramidal molecules interacting via dipole-dipole interactions. A cooperative effect induced by the interaction modifies the tunneling properties between the classical equilibrium configurations of the single molecule. The model suggests that, for sufficiently high gas density, the molecules become localized in these classical configurations. On this basi...

The standard scalar paraxial parabolic (Fock–Leontovich) propagation equation is generalized to include allorder nonparaxial corrections in the significant case of a tensorial refractive-index perturbation on a homogeneous isotropic background. In the resultant equation, each higher-order nonparaxial term (associated with diffraction in homogeneous space and scaling as the ratio between beam wa...

Symmetry and reciprocity constraints on polarization state of the field diffracted by gratings of quasi-planar particles are considered. It is shown that the optical activity effects observed recently in arrays of quasi-planar plasmonic particles on a dielectric substrate are due to the reflection of the field at the air-dielectric slab interface and are proportional to this reflection coeffici...