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1.
V. Bradnova M. M. Chernyavsky L. Just S. P. Kharlamov A. D. Kovalenko M. Haiduc K. A. Kotel’nikov V. A. Krasnov V. G. Larionova F. G. Lepekhin A. I. Malakhov G. I. Orlova N. G. Peresadko N. G. Polukhina P. A. Rukoyatkin V. V. Rusakova N. A. Salmanova B. B. Simonov S. Vokal P. I. Zarubin 《Physics of Atomic Nuclei》2003,66(9):1646-1650
A physical program of irradiation of emulsions in beams of relativistic nuclei named the BECQUEREL Project is reviewed. It is destined to study in detail the processes of relativistic fragmentation of light radioactive and stable nuclei. The expected results would make it possible to answer some topical questions concerning the cluster structure of light nuclei. Owing to the best spatial resolution, the nuclear emulsions would enable one to obtain unique and evident results. The most important irradiations will be performed in the secondary beams of He, Be, B, C, and N radioactive nuclei formed on the basis of JINR Nuclotron beams of stable nuclei. We present results on the charged state topology of relativistic fragmentation of the 10B nucleus at low energy-momentum transfers as the first step of the research. 相似文献
2.
M. I. Adamovich V. Bradnova S. Vokal S. G. Gerasimov V. A. Dronov P. I. Zarubin A. D. Kovalenko K. A. Kotel'nikov V. A. Krasnov V. G. Larionova F. G. Lepekhin A. I. Malakhov G. I. Orlova N. G. Peresadko N. G. Polukhina P. A. Rukoyatkin V. V. Rusakova N. A. Salmanova B. B. Simonov M. M. Chernyavsky M. Haiduc S. P. Kharlamov L. Just 《Physics of Atomic Nuclei》2004,67(3):514-517
New results concerning the topology of the fragmentation of relativistic nuclei 7Li and 10B are presented. A program is proposed for studying the cluster structure of stable and radioactive nuclei. The use of emulsions in the investigation of nuclear clustering in the fragmentation of light nuclei at energies are in excess of 1 GeV per nucleon is discussed. 相似文献
3.
Ionel Rosenthal Joe Z. Sostaric Peter Riesz 《Research on Chemical Intermediates》2004,30(7-8):685-701
Sonochemistry and photochemistry are initiated by high-energy transient species, which may be prone to mutual interaction. Electronic excitation of solutes by energy transfer from high energy species generated in collapsing bubbles is already supported by experimental evidence. The rates of photochemical reactions can be affected by ultrasound-induced mixing of liquids caused by microstreaming near pulsating cavitation bubbles and shockwaves due to bubble collapse. This may not only improve light absorption but also modify the pathway of reaction by increasing the contact between reagents. Finally, one may speculate about a potentially new chemistry of photoexcited solutes under the extreme conditions inside cavitation microreactors. This work reviews research on the excitation of solutes by sonoluminescence, the combined effects of ultrasound and light on liquid systems and the effect of ultrasound on photocatalytic reactions. 相似文献
4.
Ionel I Mangalagiu Geanina C MangalagiuCalin Deleanu Gabi DrochioiuMagda Ghe Petrovanu 《Tetrahedron》2003,59(1):111-114
The ability of 4-methylpyrimidinium ylides (as 1,3-dipoles) to react with activated non-symmetrical substituted dipolarophiles (alkenes and alkynes) is presented. 4-Methylpyrimidinium ylides did not react with alkenes. With alkynes the reactions are regiospecific, a single regioisomer being obtained. A possible mechanism for the reaction pathway is proposed. For the first time in the pyrimidinium ylides series both isomers resulting from bonding to the 2-and 6-positions of the heterocycle ring were obtained. The appropriate conditions in order to increase the selectivity of one of the isomers were determined. 相似文献
5.
Organotin derivatives of dimethyldithioarsinic (dithocacodylic) acid have been obtained from the appropriate organotin chloride and the sodium salt of the latter. Tin(IV) chloride and NaS2AsMe2 · 2 H2O yielded only two products, namely Cl2Sn(S2AsMe2)2 and Sn (S2AsMe2)4, regardless of the reagent ratio. Spectroscopic characterization of the compounds (infrared and1H NMR) provides structural information suggesting that the dimethyldithioarsinato group behaves as monodentate (or anisobidentate) ligand in Me2Sn(S2AsMe2)2, Bu2Sn-(S2AsMe2)2 and Cy3Sn(S2AsMe2), as bidentate in Ph2Sn(S2AsMe2)2, Ph3Sn(S2AsMe2) and Cl2As(S2AsMe2)2, whereas Sn(S2AsMe2)4 contains both mono- and bidentate ligands, presumably in a six-coordinate structure. 相似文献
6.
Sorin Mager Ionel Hopârtean Dan Bini§or 《Monatshefte für Chemie / Chemical Monthly》1978,109(6):1393-1401
The spectra of some 9-chloro-6-nitroacridines with methoxy substituents in position 1,4; 2,4; 3,4; 2,3; and ethoxy substituents in positions 1, 2, 3, were recorded. The influence of electron releasing alkoxy groups and electron withdrawing nitro groups on chemical shifts of protons in the 9-chloroacridinic cycle was discussed and PMR parameters were determined, comparatively with those of acridine and 9-chloroacridine. Good agreement between calculated and experimental values is observed. The spectrum of 9-chloro-1,2,3-triethoxyacridine shows for the four protons of the ringC. (H-5, H-6, H-7, H-8) anAMNX coupling pattern whose parameters were determined. 相似文献
7.
T. Hodisan M. Curtui I. Haiduc 《Journal of Radioanalytical and Nuclear Chemistry》1998,238(1-2):129-133
The separation of uranium and thorium from matrices containing various metal ions, was studied. The mobile phase contains
isopropyldithiophosphoric acid (i-PrDTP), as a complexing agent, in order to differentiate the studied species by modifying
their retention. The paper reports the successful separation and the quantitative determination of uranium and thorium in
the presence of Ni2+, Co2+ and Ag+ in the concentration range 2.5–2.5 μg/μl for uranium and 2.5–30 μg/μl for thorium. 相似文献
8.
Key aspects of the microenvironment surrounding the Fe center in the nitrosyl adduct of iron phthalocyanine, [Fe(Pc)(NO)], have been elucidated from the analysis of the Fe K-edge extended X-ray absorption fine structure (EXAFS) of the material adsorbed on the surface of a high area carbon electrode recorded in situ, in 0.5 M H(2)SO(4). Statistical best fits to the EXAFS data place the Fe center in a five-coordinated square pyramidal configuration shifted away from the Pc plane toward the axially bound NO bent at an angle of ca. 40 degrees with respect to the normal to the Pc plane. This environment is analogous to that of Fe in the nitrosyl adduct of crystalline [Fe(TPP)], where TPP = meso-tetraphenylporphyrinato(2-), determined from X-ray diffraction. 相似文献
9.
The behaviour of the bright palladium electrode toward the redox systems Cr(2)O(7)(2-)/Fe(2+) and Ce(4+)/Fe(2+) (in potentiometric titration) has been investigated as a function of pretreatment of the electrode. Anodization of the electrode at potentials higher than 800 mV increases DeltaE at the equivalence point by 300-400 mV for the dichromate titration. The sharp change in potential is due to the reaction between PdO(2) and Fe(2+). The equivalence point corresponds to the beginning of the potential drop, rather than the inflexion point, especially for dilute solutions. If the electrode is ignited before use the surface oxide PdO is oxidized to PdO(2) by Cr(V), the potential increases during the titration and DeltaE is 200 mV bigger than when an untreated electrode is used. In the titration of Ce(4+) with Fe(2+) the DeltaE is largest with untreated electrodes, and if the anodized electrode is used, the titration curves clearly show the reaction between PdO(2) and Fe(2+). 相似文献
10.
Solvent extraction of uranium/VI/ from aqueous perchlorate media into cyclohexane, chloroform and carbon tetrachloride solutions of di-2-ethylhexyldithiophosphoric acid /HEhdtp/ was investigated. The treatment of the partition data showed that the extraction occurs via an ion-exchange mechanism similar to that established in benzene. The species extracted in the oxygen-free noncoordinating solvents mentioned are 12 complexes of uranyl ion with phosphorodithioato group. The high distribution ratio obtained is due to the long and branched alkyl chain /2-ethylhexyl/ of phosphorodithioato ligand, which increases the solubility of the uranium/VI/ chelate in the organic phase and decreases considerably its solubility in the aqueous phase. 相似文献