No abstract available

No abstract available

[en] The molecular structure of 3-methoxy-7α-methyl-8,14-iso-1,3,5(10)-estratrien-17β-ol acetate was determined by X-ray diffraction (sp. gr. Pcab, a=6.664(2), b=12.056(2), and c=47.723(6)A; Z=8; and D_x=1.1832(7) g/cm³). The structure was solved by the direct method and refined to R(F)=0.051 [Rw(F²)=0.1106] for 843 nonzero unique reflections with I>2σ_I. In the molecule, ring A is planar, ring B is 7β,8α-half-chair, ring C is a chair, and the five-membered ring D is 13α-envelope. The A/B ring junction is planar, and the B/C and C/D junctions are of the 8α,9α-cis and 13β,14β-cis types. In addition to the X-ray study, a complete optimization of the molecular geometry was performed within a molecular modeling approach (AMI). The calculated bond lengths and angles are close to the values obtained in the X-ray structure analysis

[en] The molecular structures of three steroids, namely, 17β-acetoxy-3-methoxy-8-isoestra-1,3,5(10)-triene (I), 17β-acetoxy-3-methoxy-7α-methyl-8-isoestra-1,3,5(10)-triene (II), and 17β-acetoxy-3-methoxy-1-methyl-8-isoestra-1,3,5(10)-triene (III), are determined by X-ray diffraction analysis. It is shown that the substituents in the A and B rings of the compounds of the 8-iso series have a slight effect on the conformation of the steroid skeleton as a whole, which manifests itself only in insignificant distortions of the B and D rings. The methyl group in the 1-position (compound III) affects the geometric parameters of the steroid nucleus less than the same substituent in the 7-position (compound II). A sharp decrease in the uterotropic activity of compounds II and III (compared to compound I) revealed in biological studies can be attributed to unfavorable steric interactions of the substituents in the A and B rings with the estradiol receptor

[en] Recently there has been an effort towards developing a closed nuclear fuel cycle by recycling uranium from spent fuel, and disposing of fission products and minor actinides by vitrification or transmutation. The Universal Extraction (UNEX) method is a group separation process that has been developed in order to simultaneously extract cesium, strontium, and actinides from acidic solutions. UNEX employs a single extraction mixture which allows for the same organic phase composition to be used throughout the process. By changing the aqueous phase conditions, radionuclides are selectively stripped.1 The organic phase consists of CCD (chlorinated cobalt dicarbollide), PEG-400 (polyethyleneglycol), CMPO (diphenyl-N,N-di-n-butyl-carbamoyl-methylphosphine oxide) diluted in FS-13 (phenyl-trifluoromethyl sulfone, C₆H₅SO₂CF₃). This combination provides simultaneous extraction of Cs, Sr, actinides and lanthanides from aqueous nitric acid solutions up to 2 ? HNO₃ and 4 ? total nitrates. Currently, usage of the UNEX process for high level waste is limited due to the low solubility of CMPO in the organic phase. As a result, new possible extractants are being investigated as possible substitutes for a UNEX group separation process. Diamide derivatives have shown a large synergistic effect in the extraction of trivalent metals in solutions containing CCD.2 As a result, dipicolinamides have been proposed as possible substitutes for CMPO as an extractant component in a modified UNEX solvent. Three diamide derivatives of dipicolinic acid were studied: ortho, meta and para isomers of N,N'- diethyl-N,N'-ditolyl-diamide of dipicolinic acid (EtTDPA),3 as well as their analogous di-ethyldi( fluoro-phenyl) derivates. Extractions of selected actinides (An) and lanthanides (Ln) with the studied diamides of dipicolinic acid and the mixture of diamides with CCD were investigated as a function of the ligands structure and nitric acid concentration. A synergistic effect with chlorinated cobalt dicarbollide (CCD) on the extraction of Am and Ln with EtTDPA was observed. By developing a stripping protocol, the modified diamide-UNEX process can be used for the extraction of Cs, Sr, An and Ln followed by selective separation. References: [1] V. N. Romanovskiy, I. V. Smirnov, V. A. Babain et al., Solv. Extr. Ion Exch. 19 (2001) 1; [2] M. Yu. Alyapyshev, V. A. Babain, I. V. Smirnov; Radiochemistry, Engl. Ed. 46 (2004) 270; [3] V. A. Babain, M. Yu. Alyapyshev, R.N. Kisileva; Radiochim. Acta, 95, 217, 2007. (authors)

[en] Separation of minor actinides (particularly americium and curium) from rare earth elements is very important for reducing of actinide waste volume. New synergistic extraction mixtures - chlorinated cobalt dicarbollide (CCD) and diamides of 2,2'-dipyridyl-6,6'-dicarboxylic acid were proposed [1]. It was shown, that high enough americium-europium separation factors (∼20) in acidic media can be reached. Extraction of Am and lanthanides depending on diamide structure, ratio CCD - diamide, type of diluent was studied. Optimal conditions for Am/ REE separation were determined. [1] - M.Yu. Alyapyshev et al., Mendeleev Commun., 2008, 18, 336-337. (authors)