Thermodynamic characteristics of formation reactions of Zn<Superscript>2+</Superscript> and Ni<Superscript>2+</Superscript> complexes with succinic acid in aqueous solutions

The heat effects of complex formation between zinc(II) and nickel(II) ions and succinic acid were determined calorimetrically at 298.15 K and several ionic strength values against the background of NaNO₃. The standard thermodynamic characteristics of complex formation in aqueous solution were calculated.     

Features of fluorescence of CdSe/ZnS semiconductor quantum rods in multicomponent solutions with pentylcyanobiphenyl

The fluorescence of CdSe/ZnS semiconductor quantum rods (QRs) in the CdSe/ZnS-hexane pentylcyanobiphenyl and CdSe/ZnS-methyl methacrylate pentylcyanobiphenyl multicomponent systems has been investigated. It is shown that the presence of pentylcyanobiphenyl affects differently the QR fluorescence in each composite. The QR fluorescence in hexane solutions is efficiently quenched in the presence of pentylcyanobiphenyl, whereas in the composites based on methyl-methacrylate the QR fluorescence is enhanced as a result of the introduction of pentylcyanobiphenyl in the mesomorphic state. This difference is explained by the different forms of pentylcyanobiphenyl in these systems. The composites based on structured porous polyethylene films containing QRs in a mesomorphic medium have been obtained for the first time. The measured degree of polarization of the QR fluorescence characterizes the composite as strongly ordered.     

Photonuclear production of carrier-free radionuclides: 69mZn

Russian Chemical Bulletin - The yields of 66Ga, 67Ga, 68Ga, 70Ga, 65Zn, and 69mZn upon irradiation of gallium with the natural isotopic composition by the bremsstrahlung photon beam with the energy...     

Small-angle neutron scattering study of high-pressure sintered detonation nanodiamonds

The structure of detonation diamonds sintered at a high pressure (7 GPa) and temperatures of 1200–1700°C has been investigated by small-angle neutron scattering. It is shown that sintering leads to an increase in the particle size from 6 to 30 nm and established that this increase is due to the chainlike oriented attachment of particles. This study supplements the oriented-attachment model, which was suggested based on the X-ray diffraction spectra of detonation nanodiamonds (DNDs) sintered under the same conditions.     

Synthesis and Characterization of Niobium-Bearing Members of the NZP and NbOPO 4 Structural Families

Theoretically predicted by us, M 1/3 Nb 5/3 (PO 4 ) 3 (M = Mg, Mn, Co, Ni, Cu or Zn) compounds with the sodium zirconium phosphate (NZP) framework structure having no interstitial ions were synthesized. The rising of temperature above 900;C causes the change of chemical composition of NZP compounds and formation NbOPO 4 -like products. The phase formation regularities stated gave a possibility to choose optimal conditions for preparation of these phosphates.     

Effect of copper doping on charge ordering in La1/3Ca2/3Mn1 ? y Cu y O3 (0 ≤ y ≤ 0.07)

The effect of copper doping on charge-orbital ordering in La_1/3Ca_2/3Mn_{1 − y} Cu _y O₃ (0 ≤ y ≤ 0.07) is studied by measuring the temperature dependences of the magnetization, the electrical resistivity, and the heat capacity in combination with an electron microscopic investigation of the structure. It is demonstrated that copper doping leads to a lowering of the charge ordering temperature T _CO and that this decrease is proportional to the decrease in the Mn³⁺ ion concentration. In the temperature range 5–300 K, the semiconducting pattern of the electrical resistivity persists for all values of 0 ≤ y ≤ 0.07. Electron microscope studies have shown that the presence of copper suppresses the formation of a regular superstructure, which is characteristic of the undoped starting compound, beginning already from low concentrations (y = 0.01). Differential scanning calorimetry revealed a substantial decrease in the transition entropy at the onset of charge ordering in copper-doped samples as compared to the starting compound. Doping with copper destroys long-range charge-orbital ordering and retains apparently only short-range order. Original Russian Text ? T.S. Orlova, J.Y. Laval, Ph. Monod, V.S. Zakhvalinskiĭ, V.M. Egorov, Yu.P. Stepanov, 2009, published in Fizika Tverdogo Tela, 2009, Vol. 51, No. 1, pp. 91–97.     

Reactions of polyfluorinated chalcones with hydrazine hydrate and phenylhydrazine

Polyfluorinated di-and triarylpyrazolines were synthesized by the reactions of polyfluorinated chalcones with hydrazine hydrate and phenylhydrazine, respectively. Reactions of benzyl-idenepolyfluoroacetophenones with phenylhydrazine resulted in the mixtures of isomeric 1,5-diphenyl-3-polyfluoroaryl-and 1,3-diphenyl-5-polyfluoroarylpyrazolines. Fluorescence properties of the synthesized triarylpyrazolines were studied.     

Elemental Content and Functional Group Analysis of Humic Acids in Fossilized Soils of Different Ages

A comparative study of elemental composition, thermal characteristics, and IR and NMR spectra of humic acids recovered from modern and fossilized soils was made. The results obtained allow reconstruction of trends in variation of the environmental conditions in the course of soil formation at lake depressions in the Khakassia over a period from 3400 to 850 years before present day.     

Thermodynamic Properties of the MZr2(PO4)3 (M=Na,K, Rb or Cs) Compounds

The enthalpies of the solution of MZr₂(PO₄)₃(M=Na, K, Rb or Cs) compounds have been measured by the help of a differential automatic isothermal Calvet calorimeter and the standard enthalpies of formation have been derived. The temperature dependencies of the standard heat capacity of the samples of crystalline NaZr₂(PO₄)₃ and CsZr₂(PO₄)₃ were studied between 7 and 340 K in an automatic adiabatic vacuum calorimeter. The main thermodynamic functions H ⁰(T)–H ⁰(0), S ⁰(T) andG ⁰(T)–H ⁰(0) have been determined. The Gibbs energies of formation of the NaZr₂(PO₄)₃and CsZr₂(PO₄)₃ at 298.15 K were calculated on the basis of these experimental data and the enthalpy of formation data. Qualitative explanations for the results observed were presented. This revised version was published online in July 2006 with corrections to the Cover Date.     

Feasibility of isotopic exchange in the system [125I] iodide - undecahydro-iodo-closo-dodecaborate(2-) anion

Derivatives of the closo-dodecaborate dianion are routinely used or proposed for use in boron neutron capture therapy of cancer. The use of radioactive label on closo-dodecaborate might facilitate pharmacokinetic studies. The use of nucleophilic reactions might be of advantage if derivatives of closo-dodecaborate were oxidation sensitive. The aim of this study was to estimate the feasibility of isotopic exchange in radioiodide - iodo-undecahydro-closo-dodecaborate system. We demonstrated that copper-catalyzed isotope exchange in this system in molten acetamide provides a labeling yield of 78.4±1.1% after 30 minutes at 170 °C. The influence of the ratio between amounts of substrate and catalyst, temperature and time on the labeling yield was studied.