Variations in the Electrokinetic Potential of Magnesium Hydrosilicate Fibers upon Treatment with Ammonium Chloride

The effect of the treatment of magnesium hydrosilicate (Mg₃Si₂O₅(OH)₄) fibers with an aqueous 5% ammonium chloride solution at 37?40 and 57?60°C on their electrokinetic potential (ζ potential) is studied. The maximum time of exposure in the NH₄Cl solution was 100 min, while the ζ potential was measured every 20 min. It is shown that the treatment of the initial magnesium hydrosilicate fibers with the NH₄Cl solution leads to a reversal of their surface charge and a rise in the absolute value of the negative charge, which is explained by magnesium leaching out of the surface layer of the fibers. Washing of the treated fibers with distilled water leads again to the sign reversal of the ζ potential. Therewith, the character of the dependences of the fiber ζ potential on the time of the treatment with the 5% NH₄Cl solution at T = 37?40°C is the same before and after washing.     

Complexes of dirhodium(II) carboxylates with calix[4]resorcinarenes functionalized at the upper and lower rim of the molecule with P,N-containing Fragments

The features of the reaction between dirhodium(II) carboxylate and calix[4]resorcinarenes modified with various type functional groups at the upper and lower rim of the molecule in protic anhydrous solvent (ethanol) under inert atmosphere were investigated. Neutral complex compounds were isolated formed as a result of substitution of a water molecule by the macroligand in the axial position with respect to the R $ \tilde h The features of the reaction between dirhodium(II) carboxylate and calix[4]resorcinarenes modified with various type functional groups at the upper and lower rim of the molecule in protic anhydrous solvent (ethanol) under inert atmosphere were investigated. Neutral complex compounds were isolated formed as a result of substitution of a water molecule by the macroligand in the axial position with respect to the RRh bond occurring with the conservation of the latter. The compounds were characterized by 31P NMR, UV, IR, Raman, and ESR spectroscopy. Their composition was confirmed by elemental analysis. Original Russian Text ? E.V. Guseva, E.L. Gavrilova, A.A. Naumova, V.I. Morozov, N.I. Shatalova, D.T. Karimova, V.K. Polovnyak, 2008, published in Zhurnal Obshchei Khimii, 2008, Vol. 78, No. 12, pp. 1963–1971.     

Effect of the properties of solution on the transfer of components to the plasma zone and their emission in an electrolytic-cathode glow discharge

The processes of nonequilibrium transfer of components of a solution to the gas phase by the action of atmospheric-pressure glow discharge were studied. Data on the influence of the initial acidity and the nature of the solution on the intensity of atomic emission lines of alkali metals and the integral rate of nonequilibrium vaporization are presented. It is concluded that the gas discharge has an effect on the structural characteristics of the solution.     

Sandwich-type tetranuclear lanthanide complexes with cucurbit[6]uril: from molecular compounds to coordination polymers

Sandwich-type lanthanide complexes with macrocyclic ligand cucurbit[6]uril (C 36H 36N 24O 12, CB[6]) were synthesized under hydrothermal conditions from aqueous solutions of lanthanide(III) bromides, CB[6], and 4-cyanopyridine. According to X-ray analysis (Ln = La, Pr, Dy, Ho, Er, and Yb), the compounds with different structural types of lanthanide cores have a common fragment where the tetranuclear hydroxo complex is sandwiched between two macrocycles {(IN@CB[6])Ln 4(mu 3-OH) 4(IN@CB[6])} (6+) (IN = isonicotinate). The photoluminescence (for Ln = Eu) and Fourier transform ion cyclotron resonance mass spectra (for Ln = Pr, Dy, and Er) were studied. The compounds are used for the first time as precursors for the synthesis of lanthanide-silver heterometallic coordination polymers. The chainlike crystal structure of polymers (Ln = La, Pr, and Dy) is constituted by the sandwich complexes linked via the coordination of IN nitrogen atoms to the silver atoms.     

Ponderomotive ion acceleration in dense plasmas at super-high laser intensities

Short laser pulses at super-high intensities such as those proposed in the Extreme Light Infrastructure (ELI) project open new prospects for efficient acceleration of ions in overdense plasmas. A simple analytical model and numerical simulations demonstrate that pulses with intensities exceeding 10²² W/cm² may efficiently accelerate ions to high energies up to a few GeV. Maximum ion energy and the energy spectrum of the accelerated ions can be tuned by an appropriate choice of laser pulse intensity and duration at a given plasma density distribution.     

Lithium and beryllium hypophosphites

The structures of monoclinic (C2/m) lithium di­hydrogenphosphate, LiH₂PO₂, and tetragonal (P4₁2₁2) beryllium bis(di­hydrogenphosphate), Be(H₂PO₂)₂, have been determined by single‐crystal X‐ray diffraction. The structures consist of layers of hypophosphite anions and metal cations in tetrahedral coordination by O atoms. Within the layers, the anions bridge four Li⁺ and two Be²⁺ cations, respectively. In LiH₂PO₂, the Li atom lies on a twofold axis and the H₂PO₂⁻ anion has the PO₂ atoms on a mirror plane. In Be(H₂PO₂)₂, the Be atom lies on a twofold axis and the H₂PO₂⁻ anion is in a general position.     

Hysteresis-free spin valves with a noncollinear configuration of magnetic anisotropy

A noncollinear configuration of magnetic anisotropy in spin valves with strong and weak interlayer couplings has been formed by annealing and cooling in a magnetic field. The dependence of the low-field magnetoresistance hysteresis loop width on the angle between the applied magnetic field and the principal axes of the magnetic anisotropy in a spin valve has been investigated. It has been found that, only in the case of a strong ferromagnetic interlayer coupling, the formation of a noncollinear configuration of the magnetic anisotropy provides a hysteresis-free character of the magnetization reversal of the free layer with retaining the maximum magnetoresistance and magnetoresistive sensitivity.     

Plasma sources of VUV radiation for pulse photolysis (Review)

Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 51, No. 3, pp. 367–381, September, 1989.