Heat Capacity of a Synthetic Distillation Cut+n-Hexane System under Pressure

Isobaric heat capacities of synthetic mixtures were determined up to 40 MPa with a modified C-80 Setaram calorimeter equipped with cells designed for high pressures. The system investigated was a pseudo-binary hexane+synthetic cut, the latter consisting of compounds of the three chemical families that occur most frequently in natural effluents (paraffins, naphthenes and aromatics). The additional knowledge of density vs. pressure and temperature affords the specific heat γ ratio.     

Mössbauer and magnetization studies of the U1−xNpxO2 fluorites

²³⁷Np Mössbauer effect and magnetic susceptibility measurements of the U_1?Np_xO₂ fluorite solid solution have been performed in the composition range 0.15 ? x ? 0.75. For x = 0.15 and 0.25, the Np ions order magnetically at a lower temperature T₀ than the bulk material (T_N) (T₀ ～ 19 K, T_N ～ 27 K for x = 0.15). For x = 0.50, T₀ ～ 10 K (T_N ～ 12 K from recent neutron diffraction measurements). For x = 0.75, T₀ ～ T_N ～ 9 K. The Np (induced) ordered moment is ～ 0.5 μ_B. The ²³⁷Np Mössbauer isomer shift shows that the Np ions are in a IV charge state.     

PUVA-Induced Cell Mortality in NCTC 2544 Keratinocytes: Is It Related to the Microenvironmental Properties of the Excited States of Psoralens?

The phototoxic effect of psoralen (PSO), 5-methoxypsoralen (5MOP), 8-methoxypsoralen (8MOP) and 4,5',8-trimethylpsoralen (TMP) has been compared on the NCTC 2544 keratinocyte cell line in terms of cell mortality and lipid peroxidation. The order of effectiveness for cell photokilling is TMP, 5MOP >> 8MOP, PSO, whereas a little lipid peroxidation is observed for the four psoralens under study. Oxygen-independent membrane damage seem to play a key role in the lethal photodamage because the biological effectiveness of the most hydrophobic lipid-soluble psoralens, TMP and 5MOP, is about an order of magnitude higher than that of the more water-soluble 8MOP and PSO. In relation to this hypothesis, and in contrast to 8MOP, TMP is readily extracted from cells by ethyl acetate, a good membrane solvent, as shown by GC/MS analysis on cell extracts. The results are discussed in terms of the highly microenvironment-dependent photophysical properties of psoralens. By the measure of the intracellular psoralen concentration, the neutral red uptake and the lipid peroxidation products, this work provides evidence that PUVA therapy-mediated cell mortality is a lipid peroxidation-independent phenomenon.     

Retro carotenoids with substituted 2,5-oxa-bicycloheptane end groups

BF₃-mediated formation of a 2,5-oxygen bridge from carotenoids with 2-hydroxy-β-type end groups accompanied by dehydrogenation and $\text{retro}$ shift of the polyene system is reported. The configuration of the Δ6,6′ double bonds are established by ¹H NMR.     

Hausdorffsche Dimensionen spezieller Punktmengen

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