Magnetic Relaxation Probing of the State of Diheptyl Dithiophosphate Ions in Water and Aqueous Triton X-100 Solutions

The nuclear magnetic relaxation was used to study the state of diheptyl dithiophosphoric acid (D7DTP, L7) anions in water and aqueous solutions of the nonionic surfactant, Ttiton X-100, at 298 K in the presence of paramagnetic probes, Mn2+ ions. It was found that increase in the spin-lattice relaxation rate of water protons is caused by formation of simple and mixed (with surfactant) aggregates of D7DTP. Unlike the Mn2+-sodium dodecyl sulfate -Triton X-100 system, studied previously an influence of a probe concentration was found at surfactant concentration close to the CMC. It was suggested that two types of mixed species containing diheptyl dithiophosphate ions, Mn(II), and nonionic surfactant can be formed: micellar aggregates, {Mn(L7)2(TX)}, and polynuclear associates, [Mnx(L7)y(tx)z]. The associates likely contain surfactant in the form of monomers (tx)

Interaction between nickel(II) and anions of short-chain dialkyl dithiphosphoric acids in aqueous surfactant solutions

Spectrophotometry was used to study the complexation of nickel(II) with anions L- of diisopropyl and dibutyl dithiophosphoric acids in water and aqueous solutions of nonionic surfactant, Triton X-100 (T). Weak bis-complexes [NiL2], whose formation are stimulated by the addition of nonionic surfactant, were found in water. Within the framework of simple model including equilibria of the formation of micelle-bound complexes {[NiL2]T} and ligand associates {LT2 - }, the values of log K = 3.87 ± 0.01 and 1.3 ± 0.3 for diisopropyl dithiophosphoric acid anions and log K = 5.47 ± 0.03 and 2.8 ± 0.2 for dibutyl dithiophosphoric acid anions, respectively, were calculated. The obtained results showed that the stability of associates of hydrophobic anions of dialkyl dithiophosphates and their nickel bis-complexes with nonionic micelles increases with the length of ligand chain

High pressures, low temperatures, and magnetic field effects on AgFeAsSe3 and AgFeSbSe3 properties

A procedure for synthesizing AgFeAsSe3 and AgFeSbSe3 is presented, and their electric and magnetic properties are investigated over a wide range of temperatures, pressures, and magnetic field variation. At 100-400K, the samples are characterized by semiconductor properties. Under pressures of ∼25 and ∼24 GPa, the electric properties of AgFeAsSe 3 and AgFeSbSe3 change greatly. © 2013 Allerton Press, Inc

Influence of the structure of nonionic surfactants and the length of alkyl substituents of calix[4]resorcinarenes on their solubility, acid-base, and complexation properties

Regularities of solubilization of calix[4]resorcinarenes (H8L) with the variable length of hydrophobic radicals (R = CH3, C 3H7, C5H11, C7H 15, C8H17, C9H19, C 11H23) by the micelles of nonionic surfactants Triton X-100 and Triton X-405 in aqueous solutions were studied using solubility measurements. It was found that the solubilization capacity of surfactant micelles with respect to H8L and [H4]4- depends on the extension (thickness) of their polar layers. It was shown by means of potentiometric titration that, in solutions of nonionic surfactants, the constants of the interaction between tetraanions [H4L]4- and tetrametylammonium ions depend on the structure and concentration of nonionic surfactants and the hydrophobicity of H8L molecules. A change in the affinity of the [H4L]4- anions for protons and tetramethylammonium cations in nonionic surfactant solutions was revealed in relation to the length of substituents R and reagent concentrations

Solubility, acid-base and complexation properties of calix[4]resorcinarene in aqueous solutions of nonionic surfactants

Solubility and acid-base properties of calix[4]resorcinarene (H8L) in aqueous solutions of nonionic surfactants Triton X-100, Triton X-405, and Brij-35, as well as isopropanol were studied by pH-potentiometry. The dependence of the amount of a nonionic surfactant necessary to dissolve H8L on the length of ethylene oxide chain was found. The dissociation constants of macrocycle for the first four steps are low sensitive to the medium nature (micellar or water-alcohol solutions). Complexation ability of the [H8-nL]n- anions with respect to tetramethyl- and tetraethylammonium, N-methylpyridinium, and [Co(En)2(C2O4)]+ cations was studied by pH-potentiometry. A noticeable increase in the selectivity of guest-host binding was found on going from aqueous or water-alcohol to micellar solutions

Aggregation and counter ion binding ability of sulfonatomethylcalix[4] resorcinarenes in aqueous solutions

1H NMR spectroscopy, 1H NMR spin-lattice relaxation, conductivity and pH-metric titration data have been used to study the aggregation and counter-ion binding of tetrasulfonatomethylcalix[4] resorcinarenes with methyl (H8XNa4) and amyl (H 8YNa4) substituents. The data obtained reveal the self-aggregation of H8YNa4 driven by hydrophobic interactions. The NMR relaxation data indicate that Gd3+ is bound by both H8XNa4 and H8YNa4. The Gd 3+ ions were found to induce the aggregation of H8YNa 4 with critical association concentration (CAC) value less than in case of its self-aggregation. Using Gd3+ as a probe of counter-ion binding with the aggregate interface it was found out that binding of quaternary ammonium cations (QUATSs) with H8YNa4 aggregates and SDS aggregates is quite different, while binding of inorganic ions by both types of aggregates is similar. The most outstanding peculiarity of QUATSs binding with H8YNa4 aggregates is selective recognition of QUATSs, possessing trimethylammonium group, detected by NMR relaxation method. © 2004 Elsevier B.V. All rights reserved

Calibration of the NEVOD-EAS array for detection of extensive air showers

In this paper we discuss the calibration of the NEVOD-EAS array which is a part of the Experimental Complex NEVOD, as well as the results of studying the response features of its scintillation detectors. We present the results of the detectors energy calibration, performed by comparing their response to different types of particles obtained experimentally and simulated with the Geant4 software package, as well as of the measurements of their timing resolution. We also discuss the results of studies of the light collection non-uniformity of the NEVOD-EAS detectors and of the accuracy of air-shower arrival direction reconstruction, which have been performed using other facilities of the Experimental Complex NEVOD: the muon hodoscope URAGAN and the coordinate-tracking detector DECOR.Comment: 16 pages, 17 figures, To be submitted to Nuclear Instruments and Methods