The new composites,polyacetylene-carbon nanotubes: Electrochemical properties

Polyacetylene- and carbon-nanotube-based composite materials are prepared by the method of polymerization filling for the first time. It is shown that the acetylene polymerization mainly occurs at catalytic centers attached to the carbon nanotubes. It follows from TEM data that in the case of single-wall nanotubes the polyacetylene fibriles are wound up onto the nanotubes. In the case of multi-wall nanotubes, polyacetylene can form separate bodies that are connected to the multi-wall nanotubes. The specific electrochemical capacity of the novel composite materials is nearly twice as large as compared with that of the composite prepared by mechanical mixing; it is by two orders of magnitude larger than the pure polyacetylene capacity. The reversibility of the Li⁺ intercalation-deintercalation electrode reaction appears significantly improved at the polyacetylene-carbon nanotubes composites.     

Synthetic transformations of higher terpenoids: XVIII. Synthesis of optically active 9,10-anthraquinone derivatives

Retro-Diels-Alder decomposition of dodecahydro-endo-4b,12-ethenochrysene-1,4-diones obtained from a tricyclic diterpenoid, levopimaric acid, gave optically active 5-[2-(6-vinyl-2,6-dimethyl-2-carboxycyclohexyl) ethyl]-7-isopropyl-1,4-naphthoquinones which reacted with silyloxybutadienes to produce the corresponding 6- and 7-hydroxyanthraquinones, 5-furyl-7-hydroxytetrahydroanthraquinones, or 5-furyl-7-oxohexahydroanthraquinones. Condensation of the naphthoquinone derivatives with 5-isopropenyl-2,3-dihydrothiophene 1,1-dioxide resulted in the formation of 6,11-dioxodihydro- and 6,11-dioxohexahydroanthra[2,1-b]thiophene 3,3-dioxides. 6- and 7-Hydroxyanthraquinones were also obtained by reaction of dodecahydro-endo-4b,12-ethenochrysene-1,4-diones with Danishevsky diene, followed by cleavage of the polycyclic adducts. The cycloaddition of 5-[2-(-2-carboxy-2,6-dimethyl-6-vinylcyclohexyl)ethyl]-7-isopropyl-1,4-naphthoquinones in the presence of Lewis acids was characterized by increased regioselectivity.     

A New Fluorescent Squaraine Probe for the Measurement of Membrane Polarity

The present study was undertaken to evaluate the sensitivity of newly synthesized squaraine dye 1 to the changes in lipid bilayer physical properties and compared it with the well-known dye 2. Partitioning of the dye 1 into lipid bilayer was found to be followed by significant increase of its fluorescence intensity and red-shift of emission maximum, while intensity of the dye 2 fluorescence increased only slightly on going from aqueous to lipidic environment. This suggests that dye 1 is more sensitive to the changes in membrane properties as compared to dye 2. Partition coefficients of the dye 1 have been determined for the model membranes composed of zwitterionic phospholipid phosphatidylcholine (PC) and its mixtures with positively charged detergent cetyltrimethylammonium bromide (CTAB), anionic phospholipid cardiolipin (CL), and sterol (Chol). The spectral responses of the dye 1 in different liposome media proved to correlate with the increase of bilayer polarity induced by Chol and CL or its decrease caused by CTAB. It was concluded that dye 1 can be used as fluorescent probe for examining membrane-related processes.     

Förster Resonance Energy Transfer Study of Cytochrome <Emphasis Type="Italic">c</Emphasis>—Lipid Interactions

Specific interactions between a mitochondrial hemoprotein cytochrome c (cyt c) and cardiolipin, a lipid component of mitochondrial membrane, are crucial to electron shuttling and apoptotic activities of this protein. In the present study the Förster resonance energy transfer (FRET) between anthrylvinyl-labeled phosphatidylcholine as a donor and heme moiety of cyt c as an acceptor was employed to give a quantitative characterization of the protein binding to the model membranes from the mixtures of phosphatidylcholine (PC) with phosphatidylglycerol (PG), phosphatidylserine (PS) or cardiolipin (CL) in different molar ratios. The multiple arrays of the FRET data were globally analyzed in terms of the model of energy transfer in two-dimensional systems combined with the scaled particle adsorption model. The arguments in favor of the specificity of cyt c interactions with CL were obtained, including the higher adsorption potential and the deeper protein insertion in the lipid bilayer.     

Influence of incoherent scattering on stochastic deflection of high-energy negative particle beams in bent crystals

An investigation on stochastic deflection of high-energy negatively charged particles in a bent crystal was carried out. On the basis of analytical calculation and numerical simulation it was shown that there is a maximum angle at which most of the beam is deflected. The existence of a maximum, which is taken in the correspondence of the optimal radius of curvature, is a novelty with respect to the case of positively charged particles, for which the deflection angle can be freely increased by increasing the crystal length. This difference has to be ascribed to the stronger contribution of incoherent scattering affecting the dynamics of negative particles that move closer to atomic nuclei and electrons. We therefore identified the ideal parameters for the exploitation of axial confinement for negatively charged particle beam manipulation in future high-energy accelerators, e.g., ILC or muon colliders.     

High-temperature carbonization of humic acids and a composite of humic acids with graphene oxide

Humic acids (HAs) isolated from high-moor peat have been studied by magic-angle spinning solid-state nuclear magnetic resonance (NMR) spectroscopy, differential scanning calorimetry (DSC), thermogravimetry (TG), and Raman spectroscopy. A composite of HAs with graphene oxide (GO) has been prepared for the first time, and the thermal carbonization (900°C) of both HAs and the HA–GO composite has been carried out. With the use of mass spectrometry, it has been found that CO₂ and H₂O molecules are mainly released from HAs into the gas phase at a low temperature (to 150°C). At higher temperatures, carbon monoxide and different low-molecular-weight hydrocarbons also begin to be released. From microscopic examinations, it follows that HA forms small agglomerates with sharply outlined edges as a result of carbonization, whereas the composite forms only large aggregates.     

Search for P-ODD asymmetry in the radiative cross-section of the interaction of neutrons with lead nuclei

The P-odd effect in the radiation cross section of capture of longitudinally polarized neutrons in a sample of natural lead is measured. The experiment was performed at PF1B facility at the Institut Max von Laue-Paul Langevin. The neutron polarization P _n was 92%, the total flux of polarized neutrons was ～3 × 10¹⁰ n/s, and the mean neutron wavelength was λ = 4.7 Å. Taking into account “0-test” we estimated the asymmetry: a _γ(^natPb) = (2.3 ± 3.5) × 10^?7, i.e., α _γ ≤ 8.1 × 10^?7 at 90% confidence level.     

Mechanisms of Magnetoelectric Effects in Oxide Multiferroics with a Perovskite Praphase

Physics of the Solid State - Magnetoelectric effects in multiferroics with a perovskite structure, such as bismuth ferrite, rare-earth orthochromites, and Ruddlesden–Popper structures...     

Rubbery copolymer electrolytes containing polymerized ionic liquid for dye-sensitized solar cells

A novel type of random copolymer comprised of a polymerized ionic liquid, poly(1-((4-ethenylphenyl)methyl)-3-butyl-imidazolium iodide) (PEBII), and amorphous rubbery poly(oxyethylene methacrylate) (POEM) was synthesized and employed as a solid electrolyte in an I₂-free dye-sensitized solar cell (DSSC). The copolymer electrolytes deeply infiltrated into the nanopores of mesoporous TiO2 films, resulting in improved interfacial contact of electrode/electrolyte. The glass transition temperature (T _g) of the PEBII–POEM (?23 °C) was lower than that of PEBII homopolymer (?4 °C), indicating greater chain flexibility in the former. However, the DSSC efficiency of PEBII–POEM (4.5 % at 100 mW/cm²) was lower than that of PEBII (5.9 %), indicating that ion concentration is more important than chain flexibility. Interestingly, upon the introduction of ionic liquid, i.e., 1-methyl-3 propylimidazolium iodide, the efficiency of PEBII remained almost constant (5.8 %), whereas that of PEBII–POEM was significantly improved up to 7.0 % due to increased I^? ion concentration, which is one of the highest values for I₂-free DSSCs.     

Comparative studies of the features of the formation of impurity heterogeneity in GaSb:Te crystals in the case of directed crystallization under space and ground conditions

The results of comparative studies concerned with the formation of impurity heterogeneity in GaSb:Te crystals grown at the POLIZON facility by the Bridgman method under space and ground conditions are presented. Crystallization is carried out in the same temperature-time modes of the heaters: on board the Foton-M 3 spacecraft in space and by the vertical Bridgman method under conditions of weakened thermogravitational convection on Earth. In both cases, Marangoni convection is eliminated, and the effect of vibration microaccelerations on the ampoule that contains the melt is minimized. The microuniformity of the dopant distribution in the crystal areas that are recrystallized by the Bridgman method is higher than that in the seed grown by the Czochralski method. Microuniformity is higher under space conditions than under ground conditions with weakened thermogravitational convection. Spectral Fourier analysis of the spreading resistance distribution R _s reveals the characteristic periods of heat and mass transfer processes in the melts under ground and space conditions.