Topology and Nematic Ordering II: Observable Critical Behavior

This paper is the second in a pair treating a new lattice model for nematic media. In addition to the familiar isotropic (I) and nematically ordered (N) phases, the phase diagram established in the previous paper (Paper I) contains a new, topologically ordered phase (T) occuring at large suppression of topological defects and weak nematic interactions. This paper (Paper II) is concerned with the experimental signatures of the proposed phase diagram. Specific heat, light scattering and magnetic susceptibility near both the N/T and I/T transitions are studied, and critical behavior determined. The singular dependences of the Frank constants ($K_1$, $K_2$, $K_3$) and the dielectric tensor anisotropy ($\Delta \epsilon$) on temperature upon approaching the N/T transition are also found.Comment: 10 pages, RevTeX 3.

Synthesis of 2-Chloro-3-phthalimido-4-azetidinone and Related Derivatives from Penicillins

The current interest in new azetidinone antibiotics and their preparation has stimulated an intensive search for the synthesis of appropriately substituted monocyclic azetidinones.2- 5 Our initial efforts in this field resulted in the chlorinolysis of the carbon-sulfur bond in penicillin

Reactions of Penicillin Esters and Related Compounds with 1-Chlorobenzotriazole

Recently we reported chlorinolysis of the carbon-sulfur bond in penicillins1. Depending on the amount of halogen used, two kinds of products are .isolated. With 1 mole of chlorine, the reaction gives azetidinone sulfenyl chlorides III and with 2 moles of chlorine, olefinic azetidinone derivatives IV are formed

ChatGPT for Classification: Evaluation of an Automated Course Mapping Method in Academic Libraries

The introduction of ChatGPT has been the focus of much attention, but few specific applications for academic libraries have been shown. This study shows a proof of concept for the use of prompt engineering using reference data in GPT-4 to provide automated classifications of undergraduate course descriptions using the Library of Congress classification system. The method reduces the rate of false hallucinations from 48% to 4%, and achieves a precision of 73%. The method was tested with multiple subjects in the natural sciences, applied to 930 classifications from 181 courses, and used for collection development. This method can be implemented by librarians without extensive experience in machine learning techniques

Superconductivity in hole-doped C60 from electronic correlations

We derive a model for the highest occupied molecular orbital band of a C60 crystal which includes on-site electron-electron interactions. The form of the interactions are based on the icosahedral symmetry of the C60 molecule together with a perturbative treatment of an isolated C60 molecule. Using this model we do a mean-field calculation in two dimensions on the [100] surface of the crystal. Due to the multi-band nature we find that electron-electron interactions can have a profound effect on the density of states as a function of doping. The doping dependence of the transition temperature can then be qualitatively different from that expected from simple BCS theory based on the density of states from band structure calculations