Improved short-lived nuclide activation analysis

A novel technique has been developed to increase the sensitivity, precision and accuracy of short-lived nuclide activation analysis and especially of delayed fission neutron counting, by improving the counting statistics. This has been achieved by approaching the irradiated sample to the detector during the counting period in order to compensate for the rapid radioactive decay by variation of the counting efficiency, permitting prolongation of the counting period with constant count rate. The sample holder movement with approximately exponentially decreasing velocity is implemented by a variable DC motor with a rotary to linear movement converter, which is being replaced by a more reliable stepping motor.     

Production of new lagochilin derivatives

The tetrahydric alcohol Lgochilin belongs to the 9,13-epoxylabdane series of diterpenoids. It is produced by many species of plants of the Lagochilus genus and can be used as the starting material for the synthesis of new compounds with a broad spectrum of physiological action [1, 2]. Many lagochilin derivatives possess hemostatic (3, 4) and antiviral properties. Lagochilin derivatives with aromatic hydroxaldehydes and naphthaldehydes have been synthesized, and the cytotoxic effects of the compounds synthesized in cell cultures have been studied.Tashkent State University, (fax (3712) 46 24. 42. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 86–88, January–February, 1995. Original article submitted October 17, 1994.     

Influence of cation structure on decomposition of diacyl peroxides activated by chloride salts of amines

A kinetic study has been made of the interaction of benzoyl peroxide with a number of chloride salts of amines. It is shown that a change of the cation in quaternary ammonium salts does not have any significant effect on the kinetic parameters of the reaction. By means of NMR spectroscopy it has been determined that the structure of the NR₄ ⁺ cation does not change during the course of the reaction. The role of the cation in the process of activation of a diacyl peroxide by chloride salts of amines has been investigated by means of MNDO calculations.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 28, No. 4, pp. 324–328, July–August, 1992.     

L-asparaginase bound in a polyacrylamide gel

Summary The enzyme L-asparaginase fromE. coli has been included in polyacrylamide gel, and some of its properties have been investigated: stability, pH dependence, heat stability, K_m. It has been shown that the enzymegel obtained has a better stability then the native enzyme.Institute of Organic Synthesis, Academy of Sciences of the Latvian SSR, Riga. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 382–384, May–June, 1976.     

Vinylidene complexes of transition metals : II. A new method of synthesis of vinylidene complexes. Cymantrene derivatives containing phenylvinylidene ligands

A rearrangement of transition metal acetylenic π-complexes into compounds with vinylidene n-ligands has been established. Compounds CpMn(CCHPh)-(CO)₂ and Cp₂Mn₂(μ-CCHPh)(CO)₄ with terminal and bridging phenylvinylidene (benzylidenecarbene) ligands respectively were obtained from the π-complexes CpMn(CO)₂(PhCCR) where R  H, Ph₃Ge or Ph₃Sn. Reactions leading to conversion of the terminal CCHPh group into a bridging ligand and vice versa were studied. Under the action of L  Ph₃P, (EtO)₃P or (PhO)₃P, substitution of CO groups in vinylidene complexes takes place and compounds CpMn(CCHPh)-(CO)L are formed. IR, ¹H and ¹³C NMR spectra of the novel complexes are discussed. The data obtained indicate an electron-withdrawing property of the CCHPh ligand and stronger bonding of this ligand to the metal as compared with a CO group.     

A new solid-phase polymerization—metal phthalocyanine sheet polymers

The thermal reactions of pure metal(11) 4,4′,4″,4′″-phthalocyanine-tetracarboxylic acids of copper, cobalt, and nickel at 350–400°C in vacuum have been studied using Fourier transform infrared spectrometry, gas chromatography, and mass spectrometry. Based on these observations, novel in situ reactions for the synthesis of heat-resistant phthalocyanine “sheet” polymers are described. The poly(metal phthalocyanine) polymers of copper, cobalt, and nickel so synthesized have been characterized by elemental analysis, infrared spectroscopy, and dynamic thermogravimetric analysis. The most noteworthy property of these polymers is their extreme resistance to heat in an anaerobic atmosphere and their high char yields (89–93%) at 800°C in a nitrogen atmosphere.     

Furocoumarins ofCnidium dubium

Summary 1. Paper chromatography has shown that the fruit ofC. dubium contains not less than eight substances of coumarinic nature; six of these (A, B, C, D, E, and H) have been isolated in the crystalline state.2. Substances B, D, and E are identical with isoimperatorin, imperatorin, and oxypeucedanin, respectively. Some properties of substance H have been determined. Prangenin [F] has been detected in the fruit ofC. dubium by paper chromatography.3. The structure of two new compounds has been established: substance A (cnidicin) (I) is 5, 8-di-(, -dimethylallyloxy) psoralen, and substance C (cnidilin) (II) is 5-(, -dimethylallyloxy)-8-methoxypsoralen.Khimiya Prirodnykh Soedinenii, Vol. 2, No. 6, pp. 375–380, 1966     

Analyse de la fraction monophénolique des condensats de fumée de cigarettes par association de méthodes chromatographiques

Résumé Les monophénols sont isolés des condensats de fumées de cigarette par chromatographie sur couche mince de Kieselgel G avec un mélange (31) de cyclohexane et d'acétate d'éthyle extraits du support, puis séparé et dosés par chromatographie en phase gazeuse sur colonne capillaire. Le rendement de l;opération est de 80±2% pour le triméthyl 3,4,5 phénol, de 65% pour le triméthyl 2,3,5 phénol. Les teneurs obtenues sont de 8g de phénol, 3g de (para + méta) crésol et 0,5 g de diméthyl 2,6 phénol par mg de condensat. De nombreux autres alkylphénols ont été identifiés.

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Analysis of the monophenolic fraction of tobacco smoke condensates by a combination of chromatographic methods

Summary Monophenols are separated from tobacco smoke condensates by thin-layer chromatography on Kieselgel G using a 31 mixture of cyclohexane and ethylacetate. The monophenolic fraction is recovered from the support and analyzed by GC on a capillary column. The yield is 80±2% for 3,4,5 trimethylphenol and 65% for 2,3,5 trimethylphenol. The concentration determined for phenol, (para+meta) cresol and 2,6 dimethylphenol are 8,3 and 0.5 g per mg of condensate respectively. Numerous other alkyl phenols have been identified.

     

Decay of atomic systems in a strong electric field. Negative ion and hydrogen atom

An exact transcendental equation was obtained determining the energy levels of a particle bound by a short-range force and placed in uniform electric field. At high intensities there is a considerable difference between the values of decay probabilities calculated by previous theory and by this one. The results obtained were used to determine the electron binding energy and the polarizability of negative ions by employing experimental data on ion decay during a flight through the field region. Concrete calculations were carried out for the C^? ion.The calculation of the resonance energy E_r and the decay probability 2Γ of the quasistationary state n = S, n₁ = 3, n₂ = 0, and m = 1 of the hydrogen atom in a uniform electric field was performed by means of the direct integration of the time-independent Schrödinger equation for field intensities ranging from 0.8 × 10⁶V/cm to 1.7 × 10⁶V/cm. The calculated values fo E_r perfectly agree with those of the Rayleigh—Schrödinger perturbation energies calculated up to the fourth power in the field strength and differ substantially from the resonance energies obtained earlier by Hirschfelder and Curtiss. Our results concerning the rate of spontaneous ionization also differ substantially from the results of Hirschfelder and Curtiss and agree rather well with the results of Bailey, Hiskes and Riviere who used the general WKB method of Rice and Good.     

Electrochemical behaviour of mono- and oligonucleotides I. Effects of charge and configuration of adenine mononucleotides on their adsorption at the mercury—solution interface

A systematic study of the adsorption and interfacial behaviour of the adenine mono-nucleotides (5′-AMP, 3′-AMP, cyclic 3′,5′-AMP, 5′-ADP and 5′-ATP) and adenosine for comparison at the HMDE has been carried out at pH 3.4 to 3.5. Thus, the N(1) of the adenine moiety is protonated to a major extent.The adsorption was followed by single sweep voltammetry (measurement of the time integral of the reduction peak of the adsorbed adenine moiety) and by a.c. voltammetry (out-of-phase component of the a.c. response being proportional to the differential double layer capacity). In this paper the situation corresponding to a “dilute” adsorption layer existing at low bulk concentrations is studied for various degrees of coverage. The potential dependence of the coverage is of bell shaped type with an extended maximum region around the potential of electrocapillary maximum (E_ecm) of the blank. For the same bulk concentration the coverage decreases in the series AMP, ADP, ATP, i.e. with increasing negative charge of the nucleotide, and at the same time the potential range of adsorption narrows. Among the monophosphates the coverage decreases in the series 3′-AMP, 5′-AMP, cyclic 3′,5′-AMP. The variations are connected with the varying charge of the mononucleotides and with the possibilities for interactions with adjacent molecules in the adsorption layer.At elevated bulk concentrations above a threshold value a substantial increase in coverage occurs around E_ecm as due to strong interactions between the adsorbed base moieties a rather compact film is formed.