Effect of AlF3 production waste on the processes of hydration and hardening of the alkali-activated Portland cement with sodium silicate hydrate

Journal of Thermal Analysis and Calorimetry - Generally, the early strength of hardened Portland cement paste is controlled, by changing the mineral composition of clinker and grinding fineness. By...     

One-Stage Plasma-Assisted Electrochemical Synthesis of Cobalt-Containing Catalysts for Oxygen Reduction

Russian Journal of Electrochemistry - t—The potentialities of single-stage plasma-assisted electrochemical synthesis of few-layer graphene structures with high electrocatalytic...     

Nonlinear optical properties of systems based on ruthenium(II) tetra-15-crown-5-phthalocyaninate

The third-order nonlinear optical properties of the ruthenium (II) complex with tetra-15-crown-5-phthalocyanine and axially coordinated triethylenediamine molecules (R₄Pc)Ru(TED)₂ were analyzed by means of the z-scanning technique. A solution of (R₄Pc)Ru(TED)₂ in tetrachloroethane was exposed to nanosecond laser pulses at a wavelength of 1064 nm. It was found that the third-order molecular polarizability of the Ru(II) complex is 4.5 × 10^?32 cm⁴/C (esu). The polarizability per molecule increases by a factor of 3.6 when the single molecule occurs in a supramolecular assembly of (R₄Pc)Ru(TED)₂ complexes. The photoelectric and photorefractive properties at 1064 nm of polymer composites, determined by the supramolecular assemblies that exhibits optical absorption and photoelectric sensitivity in the near IR region, are reported.     

Carbon nanotube-containing photorefractive polymer composites operating at telecommunication wavelengths

The field dependences of photocurrent, the two-beam coupling gain coefficient, and the grating formation time constant in polymer composites made from polyvinylcarbazole (PVK) and single-wall carbon nanotubes (SWNTs) were measured under the conditions of one-photon SWNT excitation with continuous laser radiation at a wavelength of 1550 nm. Carbon nanotubes are responsible for optical electronic absorption up to ～2000 nm in this composite. The dependence of the quantum efficiency of generation of mobile charge carriers on the electric field E ₀ as determined from the photocurrent coincides with the curves calculated via the Onsager equation expanded to the (E ₀)⁴ term, at a quantum yield of thermalized electron-hole pairs of η₀ = 0.07 and a charge separation distance in the pair of r ₀ = 9.8 Å. An analysis of the photorefractive characteristics showed that the admixture of fullerene C₆₀ in an amount of 3 wt % to the PVK composite with 0.26 wt % SWNT leads to a twofold increase in the beam-coupling gain coefficient. In the PVK-matrix composite containing 0.26 wt % SWNT and 3 wt % C₆₀, the beam-coupling gain coefficient Γ of a 1550-nm laser beam and the net gain Γ-α are 32 and ～27 cm^?1, respectively, at a constant field of E ₀ = 140 V/μm.     

Gas phase activation energy for unimolecular dissociation of biomolecular ions determined by focused RAdiation for gaseous multiphoton ENergy transfer (FRAGMENT)

We present a novel approach for the determination of activation energy for the unimolecular dissociation of a large (>50 atoms) ion, based on measurement of the unimolecular dissociation rate constant as a function of continuous-wave CO(2) laser intensity. Following a short ( approximately 1 s) induction period, CO(2) laser irradiation produces an essentially blackbody internal energy distribution, whose 'temperature' varies inversely with laser intensity. The only currently available method for measuring such activation energies is blackbody infrared radiative dissociation (BIRD). Compared with BIRD, FRAGMENT: (a) eliminates the need to heat the surrounding ion trap and vacuum chamber to each of several temperatures (each requiring hours for temperature equilibration); (b) offers a three-fold wider range of effective blackbody temperature; and (c) extends the range of applications to include initially cold ions (e.g., gas-phase H/D exchange). Our FRAGMENT-determined activation energy for dissociation of protonated bradykinin, 1.2 +/- 0.1 eV, agrees within experimental error to the value, 1.3 +/- 0.1 eV, previously reported by Williams et al. from BIRD experiments. Copyright 1999 John Wiley & Sons, Ltd.     

Cascade Transformations of 1-R-Ethynyl-9,10-anthraquinones with Amidines: Expanding Access to Isoaporphinoid Alkaloids

The interaction of acetamidine and phenylamidine with peri-R-ethynyl-9,10-anthraquinones in refluxing n-butanol leads to the formation of cascade transformations products: addition/elimination/cyclization―2-R-7H-dibenzo[de,h]quinolin-7-ones and(or) 2-R-3-aroyl-7H-dibenzo[de,h]quinolin-7-ones. The anti-inflammatory and antitumor properties of the new 2-R-7H-dibenzo[de,h]quinolin-7-ones were investigated in vivo, in vitro, and in silico. The synthesized compounds exhibit high anti-inflammatory activity at dose 20 mg/kg (intraperitoneal injection) in the models of exudative (histamine-induced) and immunogenic (concanavalin A-induced) inflammation. Molecular docking data demonstrate that quinolinones can potentially intercalate into DNA similarly to the antitumor drug doxorubicin.     

Copper(II) complexes with bis(4-iodo-3,5-dimethylpyrazol-1-yl)methane: Synthesis,spectroscopic study,and crystal structure

New complexes of copper(II) nitrate, chloride, tetrafluoroborate, perchlorate, and perrhenate with bis(4-iodo-3,5-dimethylpyrazol-1-yl)methane (L) were obtained. The molecular and crystal structures of [CuL(H₂O)(NO₃)₂] · (CH₃)₂CO, [CuL₂(H₂O)][CuL₂Cl][CuCl₄], [CuL₂](BF₄)₂ · (CH₃)₂CO, and [CuL₂(H₂O)](ClO₄)₂ · (CH₃)₂CO were determined by X-ray diffraction analysis. In all the complexes, L was found to serve as a chelating bidentate ligand through the N² and N^2′ atoms of its pyrazole rings to form a six-membered chelate ring.     

Thermodynamic and kinetic characteristics of intermediates of electrode reactions. Comparative laser photoemission study of the kinetics of electron transfer for certain alkylaryl and alkylhalide radicals

Using the laser photoemission technique, a comparative study of thermodynamic and energy characteristics of electron transfer (ET) is carried out for a number of alkylaryl intermediates (IM) (benzyl, benzhydryl radicals) and alkyl halides (chloromethyl and dichloromethyl radicals). It is found that the standard free energies of activation of radicals under study are 0.34–0.38 eV and the preexpoential factors are between 10⁹ and 10¹⁰s^?1 and weakly depend on the solution nature. The reorganization energies of the medium for these IM are estimated in terms of the classical Marcus theory. The results are compared with the literature data on the dissociative ET in monohalogenomethanes CH₃Hal/CH₃Hal^?·, polychloromethanes CH_nHal_{4 ? n} /CH_nHal _4?n ^?· , and some other systems. Possible reasons for the different probabilities of observing reversible ET for IM under study are discussed.     

Studying the dimerization reaction during the abstraction of halogen from organohalides by laser photoemission, controlled-potential electrolysis, and voltammetry

To continue earlier investigations into the dimerization reaction during the cathodic cleavage of a carbon-halogen bond and, in particular, to find an accessible way for synthesizing 1,4-butanediol, a comparative study of the dimerization of ethylene halohydrins and butyl and allyl halides is performed. On the basis of the data obtained by the laser photoemission (LPE), controlled-potential electrolysis, and voltammetry techniques, a general mechanism of the electrode reactions involving these compounds and their intermediates is proposed and recommendations on the optimization of the 1,4-butanediol synthesis are elaborated. According to LPE data, at pH < 8.1, the Β-hydroxyethyl radical reduction occurs with a preceding formation of a complex with a proton donor, whereas a direct electron transfer is characteristic of the butyl radical. This difference in mechanisms is offered as the main reason for the lesser capability of ethylene halohydrins to electrochemical dimerization as compared with butyl halides, where the octane yield reached up to 80–84%. The earlier assumption about a high electrocatalytic activity of the copper cathode in dimerization of ethylene halohydrins is confirmed, and possibilities of an iron cathode in this process are revealed. The dimer yield is found to increase in alkaline solutions and at lowered temperatures, specifically, at pH 11 and temperatures of 0–5°C., the 1,4-butanediol yield reached ∼17%.