共查询到20条相似文献,搜索用时 15 毫秒
1.
R. Kapsimalis S. Landsberger N. Reguigui 《Journal of Radioanalytical and Nuclear Chemistry》2009,280(2):293-298
Phosphates, naturally containing trace amounts of uranium, were examined using direct γ-ray spectrometry. Both normal and
Compton-suppressed counting modes were utilized. The 1001 keV photo peak of the second daughter of 238U was chosen because of its isolation from other, potentially interfering peaks. The findings suggest that with the aid of
Compton suppression, it is possible to quantify low uranium levels in phosphates using samples sizes of order 10 grams within
an accuracy of 5%. The uranium content was determined in several sample types and was found to range from 60±4 to 70±8 μg/g,
depending on the sample composition. This investigation also considered the effects of sample size, counting time, and counting
technique as sources of precision maximization. This work has shown that only a small amount of phosphate is needed to determine
the constituent concentration, instead of the standard several hundred grams of material. 相似文献
2.
H. N. Lee S. H. Kang S. D. Yang S. C. Sohn 《Journal of Radioanalytical and Nuclear Chemistry》2010,284(3):513-517
Phosphorous containing radioisotope waste was separated and determined by liquid–liquid extraction method through liquid scintillation
counter (LSC). In this process, ammonium phosphate was converted to phosphomolybdate (PMo) by the reaction of ammonium molybdate
(Mo) in HCl solution (0.02 M) and maximum UV/VIS absorbance (λmax) 218 nm was observed. The PMo solution was extracted with TOA (Tri-n-Octylamine)/xylene mixture and λmax 290 nm was found for this organic layer. Absorbance of aqueous and organic layer was linear through concentration. The impurities
such as Co, Cr, Gd, etc. remain in aqueous layer by treating with Mo which was determined by ICP-AES and AAS. The quenching
correction curve for 32P was calculated using LSC results. No counting change was observed as the volume of quenchers increased. The recovery was
98% and 81% for the extraction and separation process from the test using H332PO4 as standard tracer. 相似文献
3.
N. M. Antovic N. Svrkota I. Antovic 《Journal of Radioanalytical and Nuclear Chemistry》2010,283(2):313-318
A coincidence method for measuring radium and thorium activity has been developed using the PRIPYAT-2M gamma-ray coincidence
spectrometer, with six NaI(Tl) detectors and registration geometry close to 4π. It was tested by measuring soil samples from
the Northern region of Montenegro, as well as vegetation samples from the same region. The results showed a good agreement
with ones obtained by the HPGe spectrometer. 相似文献
4.
E. M. Bond S. Glover D. J. Vieira R. S. Rundberg G. Belier V. Meot D. Hynek Y. Jansen J. Becker R. Macri 《Journal of Radioanalytical and Nuclear Chemistry》2008,276(2):549-554
This paper describes the preparation of samples for an experiment to measure the cross-section for 235U(n,n′)235mU in a fast fission spectrum of neutrons provided by a fast pulsed reactor/critical assembly. Samples of 235mU have been prepared for the calibration of the internal conversion electron detector that is used for the 235mU measurement. Two methods are described for the preparation of 235mU. The first method used a U-Pu chemical separation based on anion-exchange chromatography and the second method used an alpha
recoil collection method. Thin, uniform samples of 235mU+235U were prepared for the experiment using electrodeposition. 相似文献
5.
As part of a mass spectrometric investigation of the binding properties of sulfonamide anion receptors, an atmospheric pressure
chemical ionization mass spectrometric (APCI-MS) method involving direct infusion followed by thermal desorption was employed
for identification of anionic supramolecular complexes in dichloromethane (CH2Cl2). Specifically, the dansylamide derivative of tris(2-aminoethyl)amine (tren) (1), the chiral 1,3-benzenesulfonamide derivatives of (1R,2S)-(+)-cis-1-amino-2-indanol (2), and (R)-(+)-bornylamine, (3), were shown to bind halide and nitrate ions in the presence of (n−Bu)4N+X− (X− = Cl−, NO3−, Br−, I−). Solutions of receptors and anions in CH2Cl2 were combined to form the anionic supramolecular complexes, which were subsequently introduced into the mass spectrometer
via direct infusion followed by thermal desorption. The anionic supramolecular complexes [M+X]−, (M=1–3, X−=Cl−, NO3−, Br−, I−) were observed in negative mode APCI-MS along with the deprotonated receptors [M−H]−. Full ionization energy of the APCI corona pin (4.5 kV) was necessary for obtaining mass spectra with the best signal-to-noise
ratios. 相似文献
6.
Silvia Dulanská Boris Remenec L’ubomír Mátel Igor Antalík 《Journal of Radioanalytical and Nuclear Chemistry》2012,292(1):97-101
Two separation techniques for plutonium determination using AnaLig® Pu02 molecular recognition technology product (MRT) and extraction chromatography TRU® resin were tested. The methods performance was investigated by analysis of National Physical Laboratory (NPL-Alpha-Beta High, ABH 2003, 2005) intercomparison test samples. The results obtained for both procedures were compared in terms of activities and recoveries. Data analysis showed good agreement with the reference values. The AnaLig® Pu02 separation method for 239,240Pu, 238Pu determination was successfully validated with the same performance as the TRU® resin method. 相似文献
7.
The high-field 19F and 91Zr NMR method is used to study the hydrolysis and polycondensation of hexafluorozirconate ZrF62− in aqueous and water-peroxide solutions. During hydrolysis in aqueous solutions only ZrF62− and F− ions were observed by NMR, however, in the water-peroxide medium, an intermediate product of hydrolysis ([F5Zr-OO-ZrF5]4− dimer) was detected. The dimer structure is confirmed by 19F and 91Zr NMR. In high fields (19F NMR frequency > 200 MHz), the fluorine exchange between ZrF62− and F− is slow in the 19F NMR scale and has a multisite character. 相似文献
8.
Boukraa Yamina 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2016,90(13):2642-2645
A study on the extraction of copper(II), cobalt(II), and nickel(II) from solutions containing ions of both metals with N-salicylideneaniline(SAN) in chloroform has been realized. Distribution of the metal ions in wide range of pH has been studied. Extraction of copper(II) was always favored over that of cobalt(II). Extraction of copper(II) from binary metal solution is selective and it can be quantitatively separated from cobalt(II). The equilibrium constant of the extraction of cobalt and nickel from an aqueous solution containing both metals using SAN were evaluated. The separation factors for cobalt and nickel were expressed as a function of the distribution of nickel and cobalt. From these results, salicylideneaniline is an adequate extractant for extractive separation of such mixtures. 相似文献
9.
Potential energy curves of NgH+ cations (Ng = Kr, Xe, Rn) were obtained by using four-component relativistic CCSD(T) coupled cluster calculations. Dissociation
energies, equilibrium bond lengths, electronic properties, such as dipole moments and electric field gradients at the nuclei,
and the related spectroscopic parameters of the electronic ground state have been determined. The results obtained for KrH+ and XeH+ are in good agreement with available experimental data, while those for RnH+ have been determined for the first time at this level of theory. 相似文献
10.
A new method for the possible incorporation of nuclear wastes has been attempted here by using ceramic matrix of TiO2 as a host precursor for confinement. Hafnium is used as a simulant for actinide high-level waste. After incorporating 181Hf tracer into TiO2 matrix, the leaching property of the resulting matrix was studied in water, sodium chloride and humic acid solutions. The
leaching was measured in each of the case by following the radioactivity of 181Hf. TiO2 matrix has also been exposed to γ-radiation in order to simulate the radiation field for nuclear waste. It has been investigated
with a nuclear technique called time differential perturbed Angular Correlation (TDPAC) that the lattice structure of titania
remains undisturbed even under a strong radiation field. The leaching of 181Hf has also been studied after irradiating the TiO2 matrix with γ-radiation and the leaching behavior was observed not to change from that before irradiation. 相似文献
11.
I. V. Terekhova O. V. Kulikov R. S. Kumeev M. Yu. Nikiforov G. A. Al’per 《Russian Journal of Coordination Chemistry》2005,31(3):218-220
Reactions of - and -cyclodextrins with some biologically active acids were studied by 1H NMR spectroscopy. Inclusion complexes are found to be formed only with aromatic amino acids (phenylalanine and tryptophan) and ascorbic acid. The complexes of cyclodextrin with citric acid are obtained through interactions between the polar groups of the guest molecule and the OH groups of the host molecule located on the outside.Translated from Koordinatsionnaya Khimiya, Vol. 31, No. 3, 2005, pp. 234–236.Original Russian Text Copyright © 2005 by Terekhova, Kulikov, Kumeev, Nikiforov, Alper.This revised version was published online in April 2005 with a corrected cover date.This revised version was published online in April 2005 with a corrected cover date. 相似文献
12.
Cyclotron production of <Superscript>211</Superscript>At/<Superscript>211g</Superscript>Po by <Superscript>209</Superscript>Bi(α,2n) reaction 总被引:1,自引:1,他引:0
S. Morzenti M. L. Bonardi F. Groppi C. Zona E. Persico E. Menapace Z. B. Alfassi 《Journal of Radioanalytical and Nuclear Chemistry》2008,276(3):843-847
Astatine-211 (T
1/2 = 7.214 h) is an α-emitter at secular equilibrium by EC with its ultra-short-lived α-emitting daughter, polonium-211g (T
1/2 = 0.516 s), with a high Linear Energy Transfer (LET — 130 eV·nm−1) and a half-life suitable for metabolic radiotherapy; the overall α branching of the 211At/211gPo system is 100%. The direct production of 209Bi(α,2n)211At/211gPo seems the most satisfactory method; Bi targets were irradiated at JRC-Ispra Cyclotron of European Commission, EC, using
α-energy higher than 28.61 MeV in order to produce, via 209Bi(α,3n) reaction, small amounts of the γ-emitter 210At (used as internal spike). 相似文献
13.
Patrícia Severino Samantha C. Pinho Eliana B. Souto Maria H. A. Santana 《Journal of Thermal Analysis and Calorimetry》2012,108(1):101-108
This study focuses on the physicochemical characterization of lipid materials useful for the production of the so-called solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC). The chosen lipids were Dynasan®114 (glyceril trimyristate) and Dynasan®118 (glyceril tristearate) as solid lipids (SL), melting temperature above 80 °C, and Miglyol®812 (caprylic/capric triglyceride) and Miglyol®840 (propylene glycol dicaprylate/dicaprate) as liquid lipids (LL), crystallizing below ?15 °C. Raw lipids (pure or SL:LL mixtures) were analyzed by differential scanning calorimetry (DSC), wide angle X-ray diffraction (WAXD), and Polarized Light Microscopy (PLM), before and after tempering at 80 °C for 1 h. The selected SL:LL combination was 70% (Dynasan®114 and 118) and 30% (Miglyol®812 and 840) for the production of SLN and NLC by high-pressure homogenization (HPH), respectively. Particles with a mean size of 200 nm (polydispersity index <0.329) and zeta potential of ?15 mV were obtained, and their long-term stability was confirmed for 3 months of storage at 7 °C. 相似文献
14.
Elisa Leyva Edgar Moctezuma Silvia E. Loredo-Carrillo Claudia G. Espinosa-González Agobardo Cárdenas-Chaparro 《Journal of inclusion phenomena and macrocyclic chemistry》2018,91(3-4):211-218
The host–guest inclusion complex structure and binding ability of two different quinolones with γ-cyclodextrin (γ-CD) were investigated in solution by means of UV–Vis and 1H NMR spectroscopy. Competition of oxolinic and nalidixic acid molecules for the γ-CD cavity was evaluated by determination of association constants. Both quinolones form 1:1 inclusion complexes, their binding constants at room temperature (25 °C) under acidic and basic conditions were calculated using Benesi–Hildebrand equation. The stability of the complexes was dependent on the structure of the quinolone. In general, the weaker binding constants were observed for oxolinic acid-γ-CD complexes (1616 and 1765 M?1) and the larger binding constants were obtained for nalidixic acid-γ-CD complexes (3760 and 3840 M?1). 1H NMR studies in D2O were performed to elucidate the structure of each inclusion complex, nalidixic acid molecule penetrates more deeply into the γ-CD cavity and an intermolecular hydrogen bond is formed. Knowledge about structure and relative stability of quinolone-γ-CD complexes will be useful for future applications of these antimicrobial agents in medicinal chemistry. 相似文献
15.
Hui-Jun Won Byambatseren Baigalmaa Jei-Kwon Moon Chong-Hun Jung Kune-Woo Lee Jae-Hyuk Hyun 《Journal of Radioanalytical and Nuclear Chemistry》2011,287(2):525-531
Type 304 stainless steel specimens artificially contaminated with CsCl solution were treated with KOH solution and KNO3 solution, respectively. Cs+ ion removal tests by a Q-switched Nd:YAG laser at 1064 nm at a given fluence of 57.3 J/cm2 were performed. The surface morphology and the relative atomic mole ratio of the specimen surface were investigated by SEM
and EPMA. The order of Cs+ ion removal efficiency of laser was no-treatment < KOH < KNO3 during the 42 shots. From the investigation of XPS peaks around 532.7 and 292.9 eV, KNO3 on a surface of specimen was found to be fully decomposed during the laser irradiation. It was suggested that Cs2O particulates formed by the reaction between the reactive oxygen generated from the nitrate ion and Cs+ ion on the metal surface could be easily suspended. For the KOH system, FeOOH was formed during the laser irradiation and
it changed into Fe2O3. It was also suggested that Cs2O particulates were formed by the reaction between the reactive oxygen generated from the decomposition of K2O and Cs+ ion on the metal surface.. 相似文献
16.
It has been found that halide ions (Cl–, Br–, and I–) in aqueous solution initiate structural transformation of silver trigonal prisms (20?50 nm in size) in the sequence prism ? disc ? sphere. It has been demonstrated that the change in structure is caused by the formation of poorly soluble silver salts on nanoprisms and occurs by the electrochemical mechanism. The efficiency of the process is dictated by the nature of the halide ion. 相似文献
17.
I. P. Pozdnyakov E. M. Glebov S. G. Matveeva V. F. Plyusnin A. A. Mel´nikov S. V. Chekalin 《Russian Chemical Bulletin》2015,64(8):1784-1795
Primary photophysical and photochemical processes were studied for PtIVBr6 2– and PtIVCl6 2– complexes in water and methanol by ultrafast kinetic spectroscopy upon excitation in the band region of charge transfer from the ligand-centered group π-orbitals to the eg*-orbital of PtIV complex anion (LMCT bands). The data obtained earlier upon excitation in the region of d—d bands were compared. Irrespective of the excitation wavelength, the photochemical properties of complexes are caused by the reactions of intermediates proceeding in the picosecond time range. These intermediates were identified as PtIVBr5 – upon photolysis of PtIVBr6 2– and, presumably, the Adamson radical pair [PtIIICl5 2–(C 4v )...Cl?] upon photolysis of PtIVCl6 2–. The difference in the exciting light wavelengths has an impact only on the first step of these processes, i.e., transition from the Franck—Condon excited state to intermediates. 相似文献
18.
The adsorption of Cl−, Br−, and I− ions on the renewable liquid In-Ga and Tl-Ga electrodes from 0.1 M solutions in dimethyl formamide (DMF) is investigated
by using the method of differential capacitance measurements. The results are compared with similar data obtained on Hg and
Ga electrodes in DMF and with the corresponding data obtained in acetonitrile (AN). It is shown that, in DMF, the adsorption
parameters and the series of surface activity of halide ions (Hal−) significantly depend on the metal nature. In contrast to Hg electrode, on which the surface activity of halide ions increases
in the series: Cl− < Br− < I−, on In-Ga, as well as on the Ga electrode, it varies in the reverse order: I− < Br− < Cl−, whereas on the Tl-Ga electrode, partially reversed series of surface activity is observed: Br− < I− < Cl−. The results are explained within the framework of Andersen-Bockris model. An analysis of experimental results leads to the
following qualitative conclusions: (1) on the In-Ga and Tl-Ga electrodes, as well as on Ga electrode, free energy of metal-Hal− interaction (
$
\Delta G_{_{M - Hal^ - } }
$
\Delta G_{_{M - Hal^ - } }
) increases in series I− < Br− < Cl−; (2) for Cl−, Br−, and I−,
$
\Delta G_{_{M - Hal^ - } }
$
\Delta G_{_{M - Hal^ - } }
) grows in series Tl-Ga < In-Ga < Ga; (3) an absolute magnitude of $
\Delta G_{_{M - Hal_1^ - } } - \Delta G_{_{M - Hal_2^ - } }
$
\Delta G_{_{M - Hal_1^ - } } - \Delta G_{_{M - Hal_2^ - } }
(Hal1−, and Hal2− are any ions of Cl−, Br−, and I−) increases in series Hg < Tl-Ga < In-Ga < Ga; (4) the metal-DMF chemisorption interaction is much stronger than the metal-AN
interaction and increases in series Tl-Ga < In-Ga < Ga. 相似文献
19.
N. Mabrouk H. Berriche 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2017,91(8):1474-1485
Calculations of the adiabatic potential energy curves and the transition dipole moments between the ground (A1Σ+) and the first excited (A1Σ+) states have been determined for the LiCs and NaCs molecules. The calculations are performed using an ab initio approach based on non-empirical pseudopotentials for Cs+, Li+ and Na+ cores, parameterized l-dependent polarization potentials and full configuration interaction calculations. The potential energy curves and the transition dipole moment are used to estimate the radiative lifetimes of the vibrational levels of the A+Σ+ state using the Franck–Condon (FC) approximation and the approximate sum rule method. The radiative lifetimes associated with the A+Σ+ state are presented here for the first time. These data can help experimentalists to optimize photoassociative formation of ultracold molecules and their longevity in a trap or in an optical lattice. 相似文献
20.
O. V. Glumov V. A. Bodnar N. A. Mel’nikova V. E. Yakobson I. V. Murin 《Russian Journal of Electrochemistry》2017,53(8):846-851
KTiOPO4 crystals, both pure and doped with rubidium Rb+ and fluorine F– ions, were grown in temperature range from 1060 to 846°С from salt solvent containing potassium metaphosphate КРО3 and potassium orthophosphate К3РО4 by using a Czochralski modified method. Potassium–sodium titanyl phosphate crystals were obtained from KTiOPO4 crystals by the potassium isomorphic replacement with sodium; to this purpose, sodium chemical diffusion from NaNO3 melt was used. Their ionic conductivity was studied by the electrochemical impedance spectroscopy method. The KTiOPO4 crystal doping with rubidium and sodium ions was shown to lower the conductivity, whereas the doping with fluorine ions results in increased conductivity. 相似文献