Dimephosphone analogues. 3. Molecular and crystal structure of dimephosphone pyridinoylhydrazones exhibiting antiphthisic activity

Molecular and crystal structures of dimephosphone nicotinoylhydrazone and dimephosphone isonicotinoylhydrazone exhibiting antiphthisic activity are studied. In contrast to aroylhydrazones of arylaldehydes, existing in the crystalline state as a mixture of two amide conformers, the studied hydrazones exist in the crystalline state in the single geometrical form E _C=N E _N-N Z _N-C(O).     

Synthesis of mesoporous bimetallic Pt-Sn catalytic coatings from polynuclear precursors for fine organic synthesis processes

A new method is developed to obtain nanosized catalytic Pt-Sn/TiO₂ coatings on the inner surface of a capillary microreactor during adsorption of polynuclear carbonyl Pt-Sn complexes on mesoporous TiO₂. Titanium oxide sol prepared in the presence of template (Pluronic F127 surfactant) is supported in dynamic mode. Pt-Sn bimetallic catalysts with an average particle size of 1.5–2 nm are synthesized by adsorption of the bimetallic [Pt₃(CO)₃(SnCl₃)₂(SnCl₂·H₂O)] _n ^2n? complex followed by thermal treatment. Physicochemical properties of samples (thickness, structure and morphology, chemical composition of the material, electronic state, specific surface area, pore volume and size distribution) are characterized by a set of methods (HR TEM, SEM, powder XRD, XRF, XPS, low-temperature nitrogen adsorption). Conditions to prepare the uniform non-peelable Pt-Sn/TiO₂ coating on the inner surface of a silica capillary with good adhesion are determined. To increase the TiO₂ thickness, multilayered TiO₂ films are synthesized by layerby layer deposition. The coating thickness is found to increase with an increase in the capillary diameter. The coating of a capillary with a diameter of 0.55 mm after 14-fold deposition is characterized by a thickness of 2 μm and an average pore size of 5.4 nm. The solvent effect on the adsorption of Pt-Sn carbonyl complexes into the TiO₂ support is studied. The amount of the adsorbed complex increases in the following order: ethanol < acetone ～ tetrahydrofuran. The physicochemical properties of the active component (surface concentration, dispersion, and composition) can be fine-tuned by varying the deposition method, precursor concentration in the initial solution, and temperature conditions of activation treatment. The catalyst activity in citral hydrogenation was 0.06–0.54 min^?1, with the selectivity with respect to unsaturated alcohols reaching 90% at citral conversion above 95%.     

Effect of Concentration on the Photophysics of Dyes in Light‐Scattering Materials.

Photoactive materials based on dye molecules incorporated into thin films or bulk solids are useful for applications as photosensitization, photocatalysis, solar cell sensitization and fluorescent labeling, among others. In most cases, high concentrations of dyes are desirable to maximize light absorption. Under these circumstances, the proximity of dye molecules leads to the formation of aggregates and statistical traps, which dissipate the excitation energy and lower the population of excited states. The search for enhancement of light collection, avoiding energy wasting requires accounting the photophysical parameters quantitatively, including the determination of quantum yields, complicated by the presence of light scattering when particulate materials are considered. In this work we summarize recent advances on the photophysics of dyes in light‐scattering materials, with particular focus on the effect of dye concentration. We show how experimental reflectance, fluorescence and laser‐induced optoacoustic spectroscopy data can be used together with theoretical models for the quantitative evaluation of inner filter effects, fluorescence and triplet formation quantum yields and energy transfer efficiencies.     

Synthesis and structure of the oxalatotetranitratouranylate complex (NH4)2[{UO2(NO3)2}2(μ4-C2O4)] · 2H2O

The reaction of diaquadinitratouranyl with ammonium nitrate in ethanol gave the single crystals of ((NH₄)₂[}UO₂(NO₃)₂}₂(μ₄-C₂O₄)] · 2H₂O (I).The structure of the complex was studied by X-ray diffraction. The crystals are monoclinic, a = 8.6497(10) Å, b = 11.7001(10) Å, c = 20.2135(10) Å, β = 93.924(10)°, space group P2₁/c, Z = 4, V = 2040.9(3) ų. The structural units of the crystal are island binuclear groups [{UO₂(NO₃)₂}₂(μ₄-C₂O₄)]^2?, ammonium cations, and crystal water molecules. The structure has a complex three-dimensional packing provided by electrostatic attraction forces of the counterions and the hydrogen bond system involving water molecules, oxalate, nitrate, and uranyl ions. The IR spectra of I confirm the X-ray diffraction data.     

Plasma Maintenance Mechanisms in Large-Volume Hollow Anode

Russian Physics Journal - The paper presents research into the low-pressure hollow-cathode and hollow-anode glow discharge. The data are obtained for the plasma potential, concentration and...     

Highly radiating hydrogen flames: Effect of toluene concentration and phase

Adapting hydrogen as a carbon-free fuel for industrial applications requires new, innovative approaches, especially when radiant heat transfer is required. One possible option is to dope hydrogen with bio-oils, containing aromatics that help produce highly sooting flames. This study investigates the potential doping effects of toluene on a hydrogen-nitrogen (1:1 vol) flames. Flames with 1–5% toluene, based on the mole concentration of hydrogen, are measured using a combination of techniques including: still photographs and laser-based techniques. Toluene was mixed with hydrogen-nitrogen fuel mixture as either a vapour carried by nitrogen, or as a dilute spray. Spray flames are found to produce substantially more polycylic aromatic hydrocarbons, with significantly more soot near the nozzle exit plane, than the prevaporised flames. Increasing the dopant concentration from 1 to 3% of the hydrogen has a marked effect on soot loading in the flame, although the further increasing the dopant concentration to 5% has a far smaller effect on the soot produced in the flame. Simulations of laminar flames using detailed chemical kinetics support the above findings and reveal details of the competition between soot precursor formation and hydrocarbon oxidation. Correlations of formation rates are non-linear with toluene concentration in cases where toluene represents less than 10% of the fuel, although expected linear relationships are noted beyond this regime up to 1:1 toluene/hydrogen blends. The study provides insight and explanation into effects of toluene as a dopant, comparison between flame doping in gaseous or liquid phases and suggests that flame doping and blending should be treated as different regimes for their global effect on flame sooting characteristics.     

Entanglement of n-heptane and iso-butanol chemistries in flames fueled by their mixtures

This paper concerns itself with the entanglement of the high-temperature oxidation chemistry of n-heptane and iso-butanol in flames fueled by their mixtures. While in many cases the chemistries of the individual fuel components do not interact in mixture flames, in this work, we revealed interactions between the individual species pools originating from n-heptane and iso-butanol oxidation. In a coordinated experimental and modeling effort, chemical structures of three low-pressure premixed flames fueled by different blends of n-heptane and iso-butanol were determined using flame-sampling molecular-beam mass spectrometry with synchrotron-based single-photon ionization and chemical kinetic modeling. The chemical kinetic model, which is based on the reaction set that was used previously [Braun-Unkhoff et al., Proc. Combust. Inst., 2017, 36, 1311–1319], was now extended by an n-heptane sub-mechanism. The overall good performance of the model allows for an extraction of chemically relevant information that highlights the entanglement between the individual fuel-specific species pools. For example, it was shown that methyl radicals, in part from iso-butanol oxidation (i.e., from the decomposition of α-iso-butanol radicals) can participate in n-heptane consumption processes through H-abstraction reactions. Further interactions are related to the formation of the methylallyl radical and aromatics formation. The relevance of such interactions is also discussed regarding the formation of oxygenated byproducts.     

Tunable-Frequency Lasing on Thin Semiconductor Quantum Rings

Doklady Physics - It is been established that thin semiconductor quantum rings in an external magnetic field have unique selection properties: by choosing the type of heterostructure and the...     

The Yttrium,Lanthanum, and Lanthanide Trifluorides: Internal Periodicity of Phase Transitions

Crystallography Reports - Internal periodicity of phase transitions (fusion and polymorphism) has been revealed in trifluorides of Y, La, and 14 lanthanides. This periodicity is determined by the...     

Calculations of the Structural,Elastic, and Magnetic Properties of the Novel Full Heusler Alloys Ru2XY with X = Nb,Mn and Y = Te,Sb

JETP Letters - The electronic, elastic, and magnetic properties of the new full Heusler alloys Ru2XY with X = Nb, Mn and Y = Te, Sb are investigated using the Full Potential Nonorthogonal...