A novel procedure for the aromatization of ring a in 19-nortestosterone

A convenient, 40% overall yield synthesis of 2,3,17β-triacetoxy-1,3,5(10)-estratriene is described, which involves epoxidation of 19-nortestosterone and subsequent acetylation, lead tetra-acetate acetoxylation of the so-formed 17β-acetoxy-4β,5-epoxy-5β-estran-3-one, and aromatization of ring A, by means of acidic alumina, of the resulting 2α and 2β epimers of 2,17β-diacetoxy-4β,5-epoxy-5β-estran-3-one.     

Absorption properties of commercial lead chromates

For the cyanide determination in waste waters containing more than 2.5×10^?6 Mol of CN^?/l a conductometric method has been proposed. The sulphuric acid containing samples were distilled and the obtained HCN was passed into a 5×10^?4 Mol/l AgNO₃ solution, of which the conductivity was measured. The method offers the possibility of a precise observation of the completion of the HCN distillation and also the direct measurement of the cyanide concentration by the change of conductivity. The analysis time is about 40 min.     

100 GW pulsed iodine photodissociation laser system PERUN I

The photodissociation iodine laser system PERUN I is described. The laser generates and amplifies the subnanosecond pulse with the energy about 80 J of the fundamental wavelength 1·315 μm and beam diameter 10 cm. The physical principles of this type of the high power laser are briefly explained and the laser system and its characteristics are described from the physical and technical point of view. Special attention is paid to the realization of such system with the slow optical pumping (≈300 μs).     

Wall processes and radial gain of the cw HCN laser

The measurement of the degree of dissociation and a discussion of the formation of excited laser-active HCN molecules are presented. It is shown that HCN molecules formed by chemical reactions on the wall of the discharge tube contribute significantly to the laser gain and cause the experimentally observed constant gain over the resonator.     

A note on the Hohenberg-Kohn theorem

An alternative, concise proof of the general form of Hohenberg-Kohn theorem is presented.     

Speciation fingerprints of binary mixtures by optimized repeated two-phase separation

A method for determination of the composition of binary mixtures of a metal or radionuclide species by optimized repeated two-phase separations (SORTS) was proposed and theoretically substantiated. Its principle consists in repeated equilibration of two immiscible phases, one being the original liquid or solid matrix with minimal adjustment of its composition and varying the phase ratio (separation stage cut) as the optimized parameter. The batch separation technique may consist in the repeated solvent extraction or aqueous biphasic distribution, or in the replicate equilibration with solvent or leaching solution. Results of SORTS can be presented e.g. by Tukey box diagrams as the characteristic fingerprints of original species composition.     

Neutron-to-proton ratios in heavy-ion reactions

An expression for determining then/p ratio in heavy-ion reactions has been tested using recently published data. The agreement between the calculated and measured ratios is satisfactory.     

Proton NMR relaxation of adsorbed water in gelatin and collagen

The dependence of the water self-diffusion coefficients as well as of the proton spin-lattice and spin-spin relaxation rates on the concentration have been studied in the gelatin-water system and in hydrated native collagen. The bound and free water fractions and the corresponding spin-spin and spin-lattice relaxation rates have been determined within the multi-phase water proton exchange model. Various theoretical models for the water proton cross-relaxation to the biopolymer have been studied and the results compared with the observed Larmor frequency dependence of the water proton spin-lattice relaxation rate.