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1.
A method for quantitative determination of uranium in phosphoric acid and wet phosphoric acid has been developed. After reduction with Fe, uranium(IV) is extracted with a kerosene solution of octylphenylphosphoric acid. The uranium was stripped with 10M H3PO4, containing H2O2, and then determined spectrophotometrically with Arsenazo III and by direct uranium(IV)-phosphoric acid solution measurements. 相似文献
2.
L. N. Latysheva A. A. Bergman N. M. Sobolevsky R. D. Ilić 《Physics of Atomic Nuclei》2013,76(4):464-468
Lead slowing-down (LSD) spectrometers have a low energy resolution (about 30%), but their luminosity is 103 to 104 times higher than that of time-of-flight (TOF) spectrometers. A high luminosity of LSD spectrometers makes it possible to use them to measure neutron cross section for samples of mass about several micrograms. These features specify a niche for the application of LSD spectrometers in measuring neutron cross sections for elements hardly available in macroscopic amounts—in particular, for actinides. A mathematical simulation of the parameters of SVZ-100 LSD spectrometer of the Institute for Nuclear Research (INR, Moscow) is performed in the present study on the basis of the MCNPX code. It is found that the moderation constant, which is the main parameter of LSD spectrometers, is highly sensitive to the size and shape of detecting volumes in calculations and, hence, to the real size of experimental channels of the LSD spectrometer. 相似文献
3.
Viorel Cîrcu Doina Mănăilă-Maximean Constantin Roşu Monica Iliş Yann Molard Florea Dumitraşcu 《Liquid crystals》2013,40(2):123-132
A series of ortho-metallated Pd and Pt complexes containing an imine ligand carrying three alkoxy chains and N-benzoylthiourea derivatives as co-ligands were prepared and their liquid crystalline properties investigated. Their structures were assigned based on elemental analysis, IR and 1H NMR spectroscopy, whereas thermal properties were investigated by differential scanning calotimetry and polarising optical microscopy. All the compounds exhibit monotropic transitions involving nematic and smectic A phases, with the mesomorphic behaviour strongly related to the type of N-benzoylthiourea as well as the metal centre used. The thermally stimulated depolarisation current technique was employed to determine the conduction mechanism, phase transition temperature and the activation energies for one of the ortho-metallated Pd complexes. 相似文献
4.
A series of flexibly linked bis(pyridinium) salts with various counterions (Br?, PF6?, BF4? and OTf-) was designed and prepared starting from corresponding N-alkylated 4-pyridones precursors with mesogenic 3,4,5-tris(alkyloxy)benzyl moieties (alkyl = dodecyl or tetradecyl). These salts were investigated for their liquid crystalline properties by a combination of differential scanning calorimetry, polarising optical microscopy and temperature-dependent powder X-ray diffraction (XRD). Their thermal stability was checked by thermogravimetric analysis. All bis(pyridinium) salts, except the triflate salt with shorter terminal carbon chain, display an enantiotropic liquid crystalline behaviour with a hexagonal columnar (Colh) phase assigned on the basis of its characteristic texture and XRD studies. It was found that these luminescent bis(pyridinium) salts show weak emission in dichloromethane solutions at room temperature and a pronounced red-shifted emission in solid state. The emission properties of these bis(pyridinium) salts do not depend significantly on the nature of counterion employed. 相似文献
5.
6.
Milovan M. Stoiljković Igor A. Pašti Miloš D. Momčilović Jelena J. Savović Mirjana S. Pavlović 《Spectrochimica Acta Part B: Atomic Spectroscopy》2010
Enhancement of emission line intensities by induced oscillations of direct current (DC) arc plasma with continuous aerosol sample supply was investigated using multivariate statistics. Principal component analysis (PCA) was employed to evaluate enhancements of 34 atomic spectral lines belonging to 33 elements and 35 ionic spectral lines belonging to 23 elements. Correlation and classification of the elements were done not only by a single property such as the first ionization energy, but also by considering other relevant parameters. Special attention was paid to the influence of the oxide bond strength in an attempt to clarify/predict the enhancement effect. Energies of vaporization, atomization, and excitation were also considered in the analysis. In the case of atomic lines, the best correlation between the enhancements and first ionization energies was obtained as a negative correlation, with weak consistency in grouping of elements in score plots. Conversely, in the case of ionic lines, the best correlation of the enhancements with the sum of the first ionization energies and oxide bond energies was obtained as a positive correlation, with four distinctive groups of elements. The role of the gas-phase atom-oxide bond energy in the entire enhancement effect is underlined. 相似文献
7.
The construction of the sum of a direct (semilattice ordered) system of algebras introduced by J. Plonka – later known as the Plonka sum – is one of the most important methods of composition in universal algebra, having a number of applications in different algebraic theories, such as semigroup theory, semiring theory, etc. In this paper we present a more general way for constructing algebras with involution, that is, algebraic systems equipped with a unary involutorial operation which is at the same time an antiautomorphism of the underlying algebra. It is the sum – involutorial Plonka sum, as we call it – of an involution semilattice ordered system of algebras. We investigate its basic properties, as well as the problem of its subdirect decomposition. 相似文献
8.
I. S. Ristić L. Nikolić V. Nikolić D. Ilić J. Budinski-Simendić 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2011,85(13):2264-2269
Polyrotaxanes are intermediary products in the synthesis of topological gels. They are created by inclusion complex formation
of hydrophobic linear macromolecules with cyclodextrins or their derivatives. Then, pairs of cyclodextrin molecules with covalently
linkage were practically forming the nodes of the semi-flexible polymer network. Such gels are called topological gels and
they can absorb huge quantities of water due to the net flexibility allowing the poly(ethylene oxide) chains to slide through
the cyclodextrin cavities, without being pulled out altogether. For polyrotaxane formation poly(ethylene oxide) was used like
linear macromolecules. There are hydroxyl groups at poly(ethylene oxide) chains, whereby the linking of the voluminous molecules
should be made. To avoid the reaction of cyclodextrin OH groups with stoppers, they should be protected by, e.g., acetylation.
In this work, the acetylation of the OH groups of β-cyclodextrin was performed by acetic acid anhydride with iodine as the
catalyst. The acetylation reaction was assessed by the FTIR and HPLC method. By the HPLC analysis was found that the acetylation
was completed in 20 minutes. Inserting of poly(ethylene oxide) with 4000 g/mol molecule mass into acetyl-β-cyclodextrin with
2:1 poly(ethylene oxide) monomer unit to acetyl-β-cyclodextrin ratio was also monitored by FTIR, and it was found that the
process was completed in 12 h at the temperature of 10°C. If the process is performed at temperatures above 10°C, or for periods
longer than 12 hours, the process of uncontrolled hydrolysis of acetate groups was initiated. 相似文献
9.
10.
Dijana Ilišević 《Acta Mathematica Hungarica》2011,132(4):387-400
The problem of representability of quadratic functionals (acting on modules over unital complex ∗-algebras), by sesquilinear
forms, is generalized by weakening the homogeneity equation. The corresponding representation theorem can be considered as
a generalization of (the original form of) the classical Jordan–von Neumann characterization of complex inner product spaces. 相似文献