Bilayer-by-bilayer antiferroelectric ordering in freely suspended films of an achiral polymer-monomer liquid crystal mixture

Thin freely suspended films of a mixture of an achiral side-chain liquid crystal polymer and its monomer have been studied with depolarized reflected light microscopy. We observe that regions with an odd number of bilayers exhibit a net spontaneous polarization in the tilt plane of the molecules, while regions with an even number of bilayers have no net polarization. These odd-even effects are direct evidence that the tilted smectic bilayers are anticlinic at the polymer backbone and synclinic at bilayer interface and confirm that the phase is bilayer-by-bilayer antiferroelectric.     

Feasibility study for the production of 32 P-labeled diphosphonic acids by neutron irradiation and radiochemical separation

Two simple diphosphonates, CH₆P₂ O₆(MDP) and C₂ H₈ P₂ O₇ (HEDP),have been irradiated with neutrons to produce the corresponding ³²P-labeled compounds. After irradiation for 0.5–5 hours in a thermalneutron flux of 4.2 . 10¹⁶ n . m ^—2 s^—1 the irradiated compounds were dissolved and fractionated using a SephadexG10 column. The separated fractions were identified using planar paper chromatographyand autoradiography. The labeling yield was ca 35% for each of the compounds,and the specific activity attainable ranged up to 4.8 GBq . mol ^—1 . For practical applications, the labeled diphosphonates have to bepurified further.     

Multi-element analysis of biological material by RNAA using HPLC with on-line yield determination

The idea to use high performance liquid chromatography with continuous UV detection for multi-element radiochemical separation and simultaneous multi-element on-line yield determination is introduced. The validity of the concept was evaluated by demonstrating the constancy of the ratio of the signals for a main isotope (⁶⁰Co) and a carrier (⁵⁹Co) as a function of the elemental mass processed in the separation. The suitability of the method for practical purposes is demonstrated by its application to the RNAA determination of cobalt in biological materials. It is concluded that the method, although not yet completely developed, bears the potential of improving both accuracy and precision of multi-element RNAA.     

Cyclopropanation and epoxidation of tricyclo[5.2.1.0]deca-2(6),8-dien-3-one

Cyclopropanation of tricyclo[5.2.1.0^2,6]deca-2(6),8-dien-3-one using dimethylsulfoxonium ylide gave a highly strained annulated cyclopropane in 68% yield with complete exo-face selectivity. Nucleophilic epoxidation gave a strained epoxide in 68% yield, again completely exo-face selective. Surprisingly, using methanol as the co-solvent in this epoxidation yielded a disubstituted tricyclodecenone in 85% yield instead of the epoxide. This result can be explained by a Payne-type rearrangement of the initially formed epoxide.