N-methyl-N-alkylsilyltrifluoroacetamide-I2 as a new derivatization reagent for anabolic steroid control.

Analytical methods for the control of growth promoters have to be specific and sensitive. At low concentration levels, it is difficult to identify some molecules unambiguously even with the improved performance of analytical methods. GC-MS analysis of 17 beta-trenbolone and its major metabolite, 17 alpha-trenbolone, is a good example. A new derivatization agent has been developed which is based on silylation of the 3- and 17-oxygenated functions and nucleophilic substitution in the 4-position. The structure of the derivatized products was demonstrated using a simple model, cyclohex-2-en-1-one, by NMR and MS spectrometry. In contrast to data found in the literature, this derivative permitted specific mass spectra for trenbolone, sensitive signals for high mass ions and reproducible gas chromatograms to be obtained. The addition of an N(CH3)COCF3 radical to the steroid nucles allowed highly specific detection in GC-high resolution MS even following extraction from complex matrices; sensitive responses were also observed in the negative chemical ionization mode. Moreover, there are significant differences in the electron ionization mass spectra of the two stereoisomers, 17 alpha- and 17 beta-trenbolone. These preliminary results and those obtained for androsta-1,4-dien-3-one and pregna-4,6-dien-3-one indicate useful advances for the determination of steroids and potential applications for metabolism studies on such compounds.     

Intrinsic and rotational states in 173Ta

High spin rotational levels in ¹⁷³Ta are populated in the ¹⁶⁵Ho(¹²C, 4n)¹⁷³Ta and ¹⁷⁵Lu(α, 6n)¹⁷³Ta reactions. The de-excitation γ-ray cascades are studied with Ge(Li) detectors. The rotational bands, which are built on the $\text{7}\text{2}$⁺(404), $\text{5}\text{2}$⁺(402), $\text{9}\text{2}$^?(514) and $\text{1}\text{2}$^?(541) intrinsic states, are identified up to high spin values. A state, interpreted as a three quasi-particle state with a probable spin of $\text{21}\text{2}$ is located at 1713 keV. Its half-life is about 100 ns. The behaviour of the moment of inertia of each rotational band versus the rotational frequency is compared with that of the doubly even core.     

La reaction SN-Ge. Etude stereochimique a partir des dimethyl-1,2 germacyclopentanes

The stereochemistry of the nucleophilic substitution of various functional 1,2-dimethylgermacyclopentanes MeC₄H₇Ge(Me)X (X = Cl, OR, SR, NR₂, PR₂) by reducing reagents (LiAlH₄, LiBH₄), Grignard and organolithium compounds is studied. It depends both on the nucleophile and the leaving group. The results agree completely with those obtained in silicon series using optical NpPhRSi*X or geometrical MeC₄H₇Si(Me)X isomers.     

Ab initio calculations of the static electric polarizability of infinite polymer chains

The results of recent investigations on the potentialities of the Genkin-Mednis approach for calculating the electric polarizability of infinite stereoregular polymers at the ab initio level are reported. The working expressions are deduced and some of the computation implications are exemplified with results obtained in two study cases: the infinite chain of hydrogen molecules and trarns-polyacetylene.     

Multicommodity Flow Problem with Variable Arcs Capacities

The problem of maximizing the sum of the flows of all commodities in a network where the capacities of some arcs can be increased by integer numbers within a fixed budget is solved in this paper. Benders' technique is used to decompose the problem. Then Rosen's primal partitioning and non-linear duality theory are used to solve the subproblems generated by the Benders' decomposition. An application of a multicommodity network to the defence problem is mentioned.     

Numerical Method and Composition at and out of Chemical Equilibrium in a Multitemperature Plasma. Application to a Pure Nitrogen Plasma

The disequilibrium between the temperatures (excitation, rotation, vibration, translation) in plasmas lead us to specific chemical potentials. Then, they are used to develop a mass action law in a multitemperature plasma. This mass action law enables us to determine the composition of a pure nitrogen mixture out of thermal equilibrium. The composition evolution versus time is determined from a kinetic method modified to take into account different temperature hypotheses. The composition and different thermodynamic properties of a pure nitrogen mixture are given at the chemical equilibrium, then versus time for various temperature hypotheses and thermal disequilibriums.     

Neutralization-reionization study of C6H6O isomers

Neutralization-reionization (⁺NR⁺) mass spectrometry is employed to examine the behavior of C₆H₆O isomers in the gas phase. Phenol and cyclohexa-2,4-dienone are found not to interconvert following neutralization with mercury of their corresponding cation radicals at 9.9 keV kinetic energy. A very low extent of isomerization is observed following collisional activation of fast C₆H₆O neutrals with helium. The ⁺NR⁺ and collisionally activated dissociation spectra, the latter obtained at unit mass resolution, are used to identify these [C₆H₆O]^{+ ˙} isomers. Hexa-1,3,5-trienal is found to cyclize spontaneously to cyclohexa-2,4-dienone during attempted pyrolytic preparation. The thermochemistry of these C₆H₆O molecules and cation radicals is discussed on the basis of experimental data and MNDO calculations.