Composite electrode materials for solid oxide fuel cells with the protonic electrolyte of La<Subscript>1 – <Emphasis Type="Italic">x</Emphasis></Subscript>Sr<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>ScO<Subscript>3 – δ</Subscript>

Heterogeneous systems based on the proton–conducting oxide of La_0.95Sr_0.05ScO_{3 – δ} with Cu, Fe, Ni, Pd, La_0.9Sr_0.1MnO_{3 – δ} considered as potential materials of solid oxide fuel cell (SOFC) electrodes are synthesized. Chemical interaction between individual components of composite materials is studied, dependences of thermal and chemical expansion of the electrolyte and composites are obtained, conductivity of electrodes is measured under the conditions of SOFC operation.     

Poly(HEMA-co-AA) microparticles for removal of aluminum: The reason for Alzheimer's

Aluminum is one of the most toxic metals causing a variety of neurologic diseases, especially Alzheimer's disease. It is impossible to avoid contact with aluminum because of its existence in food to medications. Therefore, removal of aluminum from the blood or wastewater is urgently important. The cost-effective and easy-to-prepare adsorbents are needed to get efficient aluminum removal. For that purpose, the poly(2-hydroxyethylmethacrylate-co-acrylic acid), poly(HEMA-co-AA), microparticles was synthesized to remove aluminum in a very short interaction time. The achievement of the desired polymeric structure was confirmed via Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and transmission electron microscope (TEM), etc. Additionally, particle features such as swelling ratio, size, and surface area were determined. The microparticles synthesized in this study have been determined with very good adsorption capacity even in small aluminum concentrations.     

<Emphasis Type="Italic">peri</Emphasis>-cyclization of 11-aroylmethyl-2,3,4,5-tetrahydro[1,3]-diazepinobenzimidazoles into 2-aryl-3,4,5,6-tetrahydro-2a,6a,10b-triazabenzo[<Emphasis Type="Italic">a</Emphasis>]cyclopenta[<Emphasis Type="Italic">cd</Emphasis>]azulenium bromides

11-Aroylmethyl-2,3,4,5-tetrahydro[1,3]diazepinobenzimidazoles at heating in conc. HBr suffer a peri-cyclization with the closure of an additional imidazole ring involving the carbonyl group of ketone and the nitrogen atom of the diazepine ring affording previously unknown 2-aryl-3,4,5,6-tetrahydro-2a,6a,10btriazabenzo[a]cyclopenta[cd]azulenium bromides.     

Dulac–Cherkas criterion for exact estimation of the number of limit cycles of autonomous systems on a plane

The problem of exact nonlocal estimation of the number of limit cycles surrounding one point of rest in a simply connected domain of the real phase space is considered for autonomous systems of differential equations with continuously differentiable right-hand sides. Three approaches to solving this problem are proposed that are based on sequential two-step usage of the Dulac–Cherkas criterion, which makes it possible to find closed transversal curves dividing the connected domain in doubly connected subdomains that surround the point of rest, with the system having precisely one limit cycle in each of them. The effectiveness of these approaches is exemplified with polynomial Liènard systems, a generalized van der Pol system, and a perturbed Hamiltonian system. For some systems, the derived estimate holds true in the entire phase space.     

Synthesis of new donor-acceptor polymers containing thiadiazoloquinoxaline and pyrazinoquinoxaline moieties: low-band gap, high optical contrast, and almost black colored materials

Two low band gap conjugated polymers, poly[4,9-bis(4-hexylthien-2-yl)-6,7-di(thien-2-yl)-[1,2,5]thiadiazolo[3,4-g]quinoxaline] (PHTTQ) and poly[5,10-bis(4-hexylthien-2-yl)-2,3,7,8-tetra(thien-2-yl)pyrazino[2,3-g]quinoxaline] (PHTPQ), consisting of alternating electron-rich 3-hexylthiophene and electron-deficient 6,7-di(thien-2-yl)-[1,2,5]thiadiazolo[3,4-g]quinoxaline (TTQ) and 2,3,7,8-tetra(thien-2-yl)-2,3-dihydropyrazino[2,3-g]quinoxaline (TPQ) units were synthesized electrochemically. The structures of the π-conjugated monomers were tailored using thiophene as the pendant group on the acceptor units (TTQ and TPQ). The electrochemical and optical properties of the polymers were investigated by cyclic voltammetry and UV-vis-NIR spectroscopy. The absorption spectra of PHTPQ, revealing a 1.0 eV band gap, exhibited three maxima at 352 nm, 535 nm, and 750 nm. Consequently, its absorption spectra cover the region between 400 and 800 nm, which make the polymer almost black in appearance. PHTTQ shows a λ_max value of 820 nm and a band gap of 0.8 eV which is very low among other [1,2,5]thiadiazolo[3,4-g]quinoxaline-containing donor-acceptor type polymers.     

Ytterbium tris(hexafluoroacetylacetonate) Yb(C<Subscript>5</Subscript>O<Subscript>2</Subscript>HF<Subscript>6</Subscript>)<Subscript>3</Subscript>: The composition of overheated vapor and sublimation thermodynamics

A mass spectrometric study of the saturated vapor over ytterbium tris(hexafluoroacetylacetonate) Yb(hfa)₃ (hfa = CF₃-C(O)-CH-C(O)-CF₃) and of the vapor overheated up to the thermal decomposition temperature of the complex is presented. The vapor composition changes markedly with increasing temperature. At T ≈ 370 K, the mass spectrum of the vapor over Yb(hfa)₃ indicates the presence of ions containing one to three metal atoms. As the temperature is raised, the ion currents due to oligomer ions decrease. The oligomers are not detected at T > 440 K. The total decomposition temperature of Yb(hfa)₃ is 663(9) K. The second-law enthalpy of sublimation (ΔH _s^o (380 K)) is 134 ± 7 kJ/mol for the monomer and 138 ± 10 kJ/mol for the dimer. The enthalpy of dissociation of the dimer into monomer molecules is nearly equal to the enthalpy of sublimation of the monomer and dimer: ΔH _dis(380 K) = 130 ± 15 kJ/mol.     

The characteristics of the nanosized η-TiO2 polymorph

The nanosized η-TiO₂ polymorph was prepared by the hydrolysis of titanyl sulfate (TiO)SO₄ · xH₂SO₄ · yH₂O. η-TiO₂ was studied by X-ray diffraction, X-ray photoelectron spectroscopy, IR spectroscopy, and Raman spectroscopy. Characteristic X-ray data and distinguishing Raman spectrum features were found for η-TiO₂,. The surface of η-TiO₂ samples contained adsorbed OH⁻ particles and water molecules or water molecules of crystal hydrates. The free specific surface area of samples with crystallite sizes of L = 50 (4) and 60 (5) ? was S = 10.17 (9) and 15.6 (1) m²/g. The characteristics of samples with η-TiO₂ were favorable for their use as photocatalysts and adsorbents.     

The influence of solvation on the formation of Ag<Superscript>+</Superscript> complexes with 18-crown-6 ether in water-dimethyl sulfoxide solvents

The Gibbs energies of transfer of 18-crown-6 ether from water into water-dimethyl sulfoxide (DMSO) solvents (χ_DMSO = 0.0–0.97 mole fractions) at 298.15 K were determined by the interphase distribution method. Changes in the composition of the aqueous-organic solvent did not cause noticeable changes in the stability of 18-crown-6 ether solvato complexes. Reagent solvation contributions to shifts of complex formation equilibrium between silver(I) and 18-crown-6 ether when water was replaced with dimethyl sulfoxide were analyzed.     

Determination of some phthalate acid esters in artificial saliva by gas chromatography-mass spectrometry after activated carbon enrichment

The determination of six phthalate acid esters was achieved in artificial saliva using gas chromatography-mass spectrometry following activated carbon enrichment of samples. Central composite experimental design was applied to optimize method parameters, such as pH, adsorption time and amount of activated carbon. The best compromise of analytical conditions for the simultaneous determination of analytes from spiked artificial saliva were found to be: pH (3), adsorption time (30 min), activated carbon amount (1.8 g L⁻¹) and elution solvent (chloroform). These conditions were applied to study the migration of phthalate acid esters from different children's toys into saliva. A horizontal agitation method was applied to extract the analytes from plastic toys into saliva for 2 h at 37 °C. The detection limits of the method were in the range of 1.3-5.1 μg L⁻¹, while the relative standard deviation (%) values for the analysis of 100 μg L⁻¹ of the analytes were below 3.0% (n = 5). Di-2-ethylhexyl phthalate was the main analyte found in these samples.     

Self-organization of crown-containing hetarylphenylethenes,phthalic acid,and potassium cations into supramolecular assemblies

Multicomponent molecular assemblies of 15-crown-5-containing 4-styrylpyridine with phthalic acid in the presence of potassium perchlorate were studied. The structure of the obtained complicated assemblies was determined by ¹H and ¹³C NMR spectroscopy, UV spectroscopy, and X-ray analysis. The composition of the supramolecular complexes was established by spectrophotometric titration, and the stability constants were calculated. The quantum yields of fluorescence for the ligand and its complexes of various nature were determined.