A feasibility study of the cyclotron production of21Na

The cyclotron production of²¹Na, via the²⁰Ne(d, n)²¹Na and the²⁰Ne(³He, pn)²¹Na and²⁰Ne(³He, 2n)²¹Mg ²¹Na nuclear reactions, has been investigated. Transfer of²¹Na from the production target to the medical application site some 10 m distant was achieved by gas phase and liquid phase systems, both of which are described. Under optimal conditions 111 MBq·ml^–1 (3 mCi·ml^–1) of²¹Na were available at the dispensing reservoir 10 m distant from the production target, when irradiating with a 5 A deuteron beam current. Incident deuteron energy was degraded to below 3.0 MeV by a 350 m Al entrance foil, to avoid production of¹⁸F. The charge distribution of²¹Na inside the production target and inside the gas phase transfer tube at distances of 1 m and 15 m were determined, and are reported along with data from similar studies during¹⁸F production via the²⁰Ne(d, )¹⁸F reaction.²¹Na accumulated primarily at the cathode, indicating the production of positively charged species, whereas¹⁸F was equally distributed between the electrodes in a production target constructed especially for measuring the charge distribution of the radioactive species.     

Thick target yield of22Na using 27 MeV α-particles on natural Ne

A gas target chamber was built for the measurement of the thick target yield of²²Na from the bombardment of natural Ne with a cyclotron beam of 27 MeV -particles. An evaluation of these means of production as compared with other methods, especially with time consuming chemical separation methods described in the literature is presented.     

Complex formation equilibria in iron(III)-L-alanine system

Summary Complex formation in iron(III)-L-alanine solutions was studied by emf glass electrode and spectrophotometric measurements, in 0.5 mol dm ^–3 (Na)NO₃ medium, at 25 ° C. In the concentration range 0.5 [Fe]₀ 20.0, 5.0 [Ala]₀ 1000.0 (mmol dm^–3) and 1.0 -log [H⁺] 3.5; {[Ala]/[Fe] = 10:1-100:1| the equilibria in the title system were explained by the model including the species FeHL, FeL, Fe(OH)L, Fe₂(OH)₂L₂ (where HL denotes L-alanine) and several hydrolytic products. The stability constants of complexes are given. The mechanism of formation and structure of complexes in solution is proposed.Abbreviations Ala alaninate ion - HAla alanine (zwitterion) - AlaH alanine (neutral) - H₂Ala⁺ alanine cation     

Preparation of a radioactive multitracer solution from the reaction of selenium with 25 MeV nucleon40Ar ions

A radioactive multitracer solution was prepared from the reaction of selenium with 25 MeV/nucleon⁴⁰Ar ions. Using off-line -ray spectrometry, the solution containing 47 radioactive isotopes of 24 elements was obtained. The nucleide with the longest half-life was²²Na, and the shortest-lived one was⁸¹Rb⁸.     

137Cs,trace and toxic elements distribution in Austrian mushrooms

Various mushroom species have been analyzed for their elemental composition (i.e., Al, B, Ba, Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Na, P, Sr and Zn) by means of ICP-AES. The accuracy of the measurements was confirmed by analyzing a series of the same samples by short time activation analysis. The data were evaluated statistically including the values of¹³⁷Cs. The results denote that the distribution of these elements and their correlation of these elements and their correlation coefficients are highly distinctive for each mushroom species. K, Na and P were found to correlate negatively with¹³⁷Cs in most species. Suillus grevillei and Cantharellus cibarius show high Be values (0.27 and 0.30 g g^–1, respectively), while Pb was high in Suillus grevillei (16.3 g g^–1) and Amanita rubescens (9.3 g g^–1). Higher levels of Cd were found in Rozites caperata and Russula vesca with a mean of 9.2 and 16.1 g g^–1, respectively. Cluster analysis was applied to classify these samples according to their botanical species using their elemental composition. The concentrations of Al, Cr, Mn, Na and¹³⁷Cs have no influence on the classification of these samples.     

Radiocatalytic H2 production with gamma-irradiation and TiO2 catalysts

The radioactive concentrations of radionuclides were measured in the soil and groundwater below the 12 GeV proton beam-line tunnel at KEK. Various long-lived radionuclides, (⁷Be, ²²Na, ⁴⁶Sc, ⁵⁴Mn, ⁶⁰Co, ¹³⁴Cs, ¹⁵²Eu and ¹⁵⁴Eu) were observed in the soil samples by -ray spectra measurements, and ³H was also detected by liquid scintillation counting. On the other hand, ³H, ²²Na and ⁵⁴Mn, which were leached from the soil were measured in the groundwater below the EP2 beam line. ³H and ²²Na were also found in slight amounts in groundwater collected in a well dug beside the East Counter Hall. From a comparison with the radioactive concentration in soil and groundwater, the order of the leaching percentages were ³H>²²Na>⁵⁴Mn. This tendency was in agreement with an experimental result of the RI laboratory.     

Recoil implantation reaction in geometrical isomers of tris/benzoylacetonato/chromium/III/

Hot atom chemical reaction by⁵⁰Cr/n, /⁵¹Cr and⁵²Cr/, n/⁵¹Cr reactions, and recoil implantation reaction by⁵¹V/p, n/⁵¹Cr reaction were investigated using geometrical isomers /mer and fac/ of tris/benzoylacetonato/ chromium/III/ /Cr/ba/₃/. The production of counter isomer was observed for both mer- and fac-targets, although the yield of labelled parent isomer was larger. The observed mer/fac yield ratio suggests that the main formation mechanism of⁵¹Cr/ba/₃ is the reaction of ba^– and Cr/ba/ ₂ ⁺ which has the same geometrical configuration of target complex, and the substitution reaction of central metal atom by recoil⁵¹Cr. Furthermore, implantation gave rise to a much higher yield of labelled Cr/ba/₃ compared to the case of in situ nuclear recoils.     

Reactions of Peroxy Radicals with Hydrocarbons and Alcohols: Transition State Geometry and the Polar Effect

The reaction EtOO + EtH EtOOH + Et was studied by the intersecting parabolas method and calculated using density functional theory. The interatomic C–H, O–H, and C–O distances of the transition state for this reaction were calculated using these methods. The formulas for calculating these distances from experimental data were obtained. Similar calculations and comparisons were carried out for the reaction EtOO + MeCH₂OH EtOOH + MeCHOH. The polar effect of the hydroxy groups on the transition state manifested itself in a decrease in the activation energy and in the formation of a nonlinear structure of the transition state. An empirical formula for estimating the C–H–O angle in the transition state from the enthalpy and activation energy was derived.     

Mechanism of recoil implantation reactions of technetium and ruthenium in metal acetylacetonates

Recoil implantation of Tc and Ru in metal acetylacetonates were performed using ruthenium metal as a source and M^III/acac/₃ and M^II/acac/₂ complexes as catchers. The recoil atoms were obtained by¹⁰⁰Ru/, p/^99mTc and⁹⁸Ru/, n/⁹⁷Ru reactions. The yields of Tc/acac/₃ and Ru/acac/₃ were clearly dependent on the force constant of the bond between the central metal atom and oxygen in acetylacetone K/M–O/. A plot of the yield vs. 1/K(M–O) showed a linear relationship. However, the yield of Tc/acac/₂ implanted in M/acac/₂ did not show such a dependence on the force constant. The difference of the mechanism of complex formation between Tc/acac/₃ and Tc/acac/₂ was discussed on the basis of a reaction cage surrounding the recoil atom and of reaction time necessary for competition between the recoil atom and the central metal of the catcher complex.     

Mechanism of transannular iodination of 3,7-dimethylenebicyclo[3.3.1]nonane derivatives

The kinetics of iodination of 3,7-dimethylenebicyclo[3.3.1]nonane derivatives containing alkyl substituents in one of the methylene groups were studied. The processes proceed selectively with the formation of 1-iodomethyl-3-iodoadamantanes, substituted at the 2-position, and characterized by a negative temperature dependence of the reaction rate (H=–(10–24) kJ/mole). The entropy contributions of the substituents at the double bonds to the reaction kinetics were determined; these contributions completely satisfy the Benson rules for synchronous transformations. A scheme of reaction mechanism was proposed, including the successive formation of diolefin complexes with iodine with a 11 and 12 compositions, a synchronous stage of ring closure with the formation of an ionic pair, and its recombination (the molecular-ionic mechanism).Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 22, No. 6, pp. 743–747, November–December, 1986.     

Mechanisms of chemical reaction initiated by recoil implantation

Mechanisms of chemical reactions initiated by recoil implantation were studied in the systems⁵¹Cr+M/acac/₃⁵¹Cr/acac/₃ where M is a trivalent metal. The yield of⁵¹Cr/acac/₃ increased linearly with an increase of inverse of the force constant of metal-oxygen bonding K(M–O). This indicates that there is competition between the implanted⁵¹Cr atom and M. However, exception for this trend was the case of Co/acac/₃ catcher, for which the yield of⁵¹Cr/acac/₃ was much higher than that expected for a competition reaction. Complex features of the replacement reaction caused by implantation are discussed in this system.     

Formation of Inclusion Complexes between Cyclodextrins and Carbaryl and Characterization of the Complexes

The solubility of carbaryl increased with increasing concentrations of-CD, G₂--CD, and M--CD. The result suggests theformation of soluble inclusion complex. Solubility increase was highestin M--CD-carbaryl, being 18.4 fold higher than that of carbaryl when 100 mM M--CD was used. The apparent formation constant for the complex calculated from phase solubility diagram was 223.18 M^-1. The preparation of the complex in solid form for characterization was successful by kneading andfreeze-drying. The DSC curves for kneading and freeze-drying mixture didnot show the endothermic peak characteristic of carbaryl, but a small new endothermic peak was observed. FTIR analysis showed a shift of the major peak of carbonyl group in carbaryl molecule from 1717 to 1744 and 1734 cm^-1 in kneading and freeze-dried mixtures, respectively. M--CD-carbaryl complex demonstrated higher dissolution rate, higher thermal and UV stability but lower toxicity than its parent carbaryl compound.     

Triterpene glycosides ofAstragalus and their genins. XLVIII. The structures of cycloalpigenin B and cycloalpioside B

The structures of the new cycloartane methylsteroid cycloalpigenin B and its glycoside cycloalpioside B, isolated fromAstragalus alopecurus Pall. (Leguminosae) have been determined on the basis of chemical transformations with the assistance of¹H and¹³C NMR spectroscopy and 2D NMR¹H-¹H and¹H-¹³C correlations of chemical signals and IR, CD, and electron-impact mass spectrometry. Cycloalpigenin B is 20R,24S-epoxycycloartane-3,12,16,25-tetraol. A transition from cycloalpigenin B to cycloalpigenin A has been achieved. Cycloalpioside B is 20R,24S-epoxycycloartane-3,12,16,25-tetraol 3-O--D-xylopyranoside.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Republic of Uzbekistan, Tashkent, FAX (3712) 89 14 75. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 515–521, July–August, 1994.     

Relaxation behavior of selenium based glasses

Summary Relaxation behavior of Ge_ySe_100-y (y=8 and 10) glasses related to the viscosity behavior was studied by dilatometry. The method of two consecutive temperature jumps was applied to study the volume relaxation. The relaxation response can be described by Tool-Narayanaswamy-Moynihan model and the parameters of this model h*, , x, A were determined using curve fitting method and characteristic times method. Viscosities of studied materials in the range of 10⁸-10¹³ Pas were measured by penetration method. The calculated values of activation energies of viscous flow E are close to the values of effective activation energies of relaxation h* for studied chalcogenide materials.     

Ab initio MP2 calculations of the products of acetylene addition to HgCl2

Gas-phase reaction of acetylene with HgCl₂ resulting in -chlorovinylmercury derivatives and their interaction with Cl^– and I^– anions and KI molecule was studied by the ab initio MP2 method with the Dunning—Hay double zeta basis set and LanL pseudopotential for Hg, K, and I atoms. The reaction was shown to proceed via a -complex of acetylene and HgCl₂ (the calculated enthalpy of formation is –6.5 kcal mol^–1). According to calculations, the activation energy of formation of cis--chlorovinylmercury chloride from acetylene and HgCl₂ is 31 kcal mol^–1. Chloride and iodide anions and KI molecule are readily added to both cis- and trans-isomer of -chlorovinylmercury chloride to give stable species.     

Vibronic transitions in the collision of Na with N2

Quenching, by collision, of an alkali atom A with a diatomic molecule X₂ is considered, on the assumption that the reaction occurs via formation of the intermediate complex A ⁺X ₂ ^– . The Landau-Zener approximation is used to calculate the partial rate constants of Na(²P)+N₂(v=0) Na(²S)+N₂(v>0) corresponding to transitions to different vibrational states in the diatomic molecule.I am indebted to A. I. Voronin, E. I. Dinaburg, E. E. Nikitin, and M. Ya. Ovchinnikova for assistance in this work and for valuable discussions.     

The effectivity of solvents as electron pair donors

The effectivity of solvents as electron pair donors, their donicity as expressed by their donor numbers DN, is reexamined. The linear dependence of the enthalpy and the Gibbs free energy for the reaction of donor solvents with antimony pentachloride is affirmed. Extension of the DN scale by other measured quantities, via their linear correlations for sets of solvents where both kinds of data are known is applied to Drago's E-C scale, Kamlet's scale, and Koppel's B scale. This extension, added to previous extensions employing Selbin's D_{I, II} and Popov's ²³Na, produces a DN scale for 170 solvents. The relation of DN measured for isolated solvent molecules in 1,2-dichloroethane to DN values measured for bulk solvents is examined by means of the scaled particle theory and solute-solvent interaction terms. A scale of normalized donor numbers DN ^N is presented. These values are practically the same as the scale, and for those solvents for which DN values are presented here and values are lacking, they can serve in their place for those preferring to use the scale for donor solvents.     

Stability of dicyclohexyl‐18‐crown‐6‐hydrogen complex in nitrobenzene saturated with water

From extraction experiments with 22 Na as a tracer, the extraction constant corresponding to the equilibrium H⁺ (aq)+NaL ⁺(nb) HL⁺ (nb)+Na ⁺ (aq) in the twophase waternitrobenzene system (L = dicyclohexyl18crown6; aq = aqueous phase, nb = nitrobenzene phase) wasevaluated in the form log K ex (H⁺ , NaL⁺ ) = 0.2. Further, the stability constant of the complex HL⁺ in nitrobenzene saturated with water wascalculated for a temperature of 25 °C : log bnb (HL⁺ ) = 7.7.     

Own N-layered integrated molecular orbital and molecular mechanics study of the reaction of OH<Superscript>−</Superscript> with polychlorinated hydrocarbons CH<Subscript>(4−n)</Subscript>Cl<Subscript>n</Subscript> (n=2–4)

The reliability of the two-layer own N-layered integrated molecular orbital and molecular mechanics (ONIOM) method was examined for the S_N2 reaction CH_(4–n)Cl_n+OH^–. In the ONIOM calculation, only the methyl chloride and OH^–were treated at a high level and the effect of polychlorination was taken into account only at a low level. The ONIOM results were compared with the target CCSD(T)/aug-cc-pVDZ//MP2/aug-cc-pVDZ results obtained by Borisov etal. [(2001) J. Phys. Chem. A 105:7724]. The ONIOM[MP2/aug-cc-pVDZ:B3LYP/6-31+G(d)] was found to reproduce well the target geometry and energy at the MP2/aug-cc-pVDZ level. The single-point improved energetics at the ONIOM[CCSD(T)/aug-cc-pVDZ:MP2/6-31+G(d)] is found to give results nearly as accurate as the target CCSD(T)/aug-cc-pVDZ//MP2/aug-cc-pVDZ results. The substantially reduced cost, 20% for optimization and 5% for single-point improved energy of the target cost for n=4, as well as small errors suggest that ONIOM is a powerful tool for accurate potential-energy surfaces of the reaction of large polyhalohydrocarbons.