Polymerization of chlorophenyl glycidyl ethers. VI

Summary Polymerization of p-chlorophenyl glycidyl ether initiated by potassium glycolates (ethylene, propylene and 2-methyl propylene glycolatea) in DMSO containing some 18-crown-6 ether or glycol was investigated. For the reaction system containing the propylene glycolate asymmetrically substituted with a methyl group, relatively high polymerization rates were obtained as compared with those found for the other systems studied, the resultant polymers also having higher molecular weights and comparatively low polydispersities. Aliphatic double bonds were found to be absent in the polymers synthesized, which would suggest that in the anionic polymerization process studied the growing chain is not transferred to the monomer.Dedicated to Prof. C.I. Simionescu on the occasion of the 60th anniversary of his birthday     

The ultra-low friction of the articular surface is pH-dependent and is built on a hydrophobic underlay including a hypothesis on joint lubrication mechanism

In this study, the influence of pH on interfacial energy distributed over the phospholipids-bilayer surface model and the effect of hydrophobicity on coefficient of friction (f) were investigated by using microelectrophoresis. An important clinical implication of deficiency in hydrophobicity is the loss of phospholipids that is readily observed in osteoarthritis joints. This paper establishes the influence of pH on interfacial energy upon an increase f, which might be associated with a decrease of hydrophobicity of the articular surface.     

Hydrodechlorination of CCl<Subscript>4</Subscript> on Pt–Au/Al<Subscript>2</Subscript>O<Subscript>3</Subscript> Catalysts

A series of Pt/Al₂O₃ catalysts were prepared by the impregnation method and were characterized by TEM, XRD, H₂ and CO chemisorptions, and investigated in the hydrodechlorination of tetrachloromethane. Three Pt-rich, Pt–Au/Al₂O₃ catalysts (Pt₁₀₀, Pt₉₅Au₅ and Pt₉₀Au₁₀) showed a similar metal particle size (~2.5–2.7 nm), so observed changes in the catalytic behavior are ascribed to alloying effect, especially because a considerable degree of Pt–Au mixing was achieved in the bimetallic samples. It appeared that by introducing very small amount of gold (10 at.%) to platinum, the catalytic activity is increased. It is argued that the occurrence of this moderate synergistic effect is associated with a decreased tendency of surface chloriding when platinum is alloyed with gold. Zbigniew Kowalczyk—deceased.     

Spectral studies of zinc octacarboxyphthalocyanine aggregation

The association of zinc octacarboxyphthalocyanine, was studied using UV–vis absorption and fluorescence emission spectroscopy; the effects of dye concentration, pH and solvents on spectra were discussed. Calculations showed that the dye dimerized in aqueous solutions ranging from 5.0 × 10^?7 to 5.0 × 10^?5 mol/dm³, at 25 °C. The dimerization constant of 10⁶ dm³/mol and the spectral Q band shift of 1185 cm^?1 imparted by dimerization indicated strong π–π interactions between phthalocyanine molecules. Red S₁ fluorescence of the dye monomer was observed in various solutions which was quenched owing to molecular association and other factors. The strong influence of pH on both aggregation and fluorescence was discussed. At pH < 5.0, only dye aggregates were present in solution; monomers appeared at pH ≥ 5.0 and, in alkaline solution, only the monomeric anions of phthalocyanine existed. The spectral absorption and emission data for the dye in binary solvents revealed that at concentrations ranging from 0.5 × 10^?5 to 1.0 × 10^?5 mol/dm³, the dye can be used in photosensitised oxidation reactions.     

Scaling up microbial fuel cells

The goal of this study was to quantify the relation between the surface area of the current-limiting electrode of a microbial fuel cell (MFC) and the power density generated by the MFC. Shewanella oneidensis (MR-1) was grown anaerobically in the anodic compartment of an MFC utilizing lactate as the electron donor. Graphite plate electrodes of various sizes were used as anodes. Commercially available air electrodes, composed of manganese-based catalyzed carbon bonded to a current-collecting screen made of platinum mesh, were used as cathodes, and dissolved oxygen was used as the cathodic reactant. The surface area of the cathode was always significantly larger than that of the anode, to ensure that the anode was the current-limiting electrode. The power density generated by the MFC decreased as the surface area of the anode increased, which fits well with the trend we detected comparing various published results. Thus, our findings bring into question the assertion that the overall power density generated by an MFC with large electrodes can be estimated by extrapolating from an electrode with a small surface area. Our results indicate that the maximum power density generated by an MFC is not directly proportional to the surface area of the anode, but is instead proportional to the logarithm of the surface area of the anode.     

Nido-Hydroborate-Based Electrolytes for All-Solid-State Lithium Batteries

Hydroborate-based solid electrolytes have recently been successfully employed in high voltage, room temperature all-solid-state sodium batteries. The transfer to analogous lithium systems has failed up to now due to the lower conductivity of the corresponding lithium compounds and their high cost. Here LiB₁₁H₁₄ nido-hydroborate as a cost-effective building block and its high-purity synthesis is introduced. The crystal structures of anhydrous LiB₁₁H₁₄ as well as of LiB₁₁H₁₄-based mixed-anion solid electrolytes are solved and high ionic conductivities of 1.1 × 10⁻⁴ S cm⁻¹ for Li₂(B₁₁H₁₄)(CB₁₁H₁₂) and 1.1 × 10⁻³ S cm⁻¹ for Li₃(B₁₁H₁₄)(CB₉H₁₀)₂ are obtained, respectively. LiB₁₁H₁₄ exhibits an oxidative stability limit of 2.6 V versus Li⁺/Li and the proposed decomposition products are discussed based on density functional theory calculations. Strategies are discussed to improve the stability of these compounds by modifying the chemical structure of the nido-hydroborate cage. Galvanostatic cycling in symmetric cells with two lithium metal electrodes shows a small overpotential increase from 22.5 to 30 mV after 620 h (up to 0.5 mAh cm⁻²), demonstrating that the electrolyte is compatible with metallic anodes. Finally, the Li₂(B₁₁H₁₄)(CB₁₁H₁₂)  electrolyte is employed in a proof-of-concept half cell with a TiS₂ cathode with a capacity retention of 82% after 150 cycles at C/5.     

A quadratic boundedness approach to a neural network-based simultaneous estimation of actuator and sensor faults

Neural Computing and Applications - The paper is devoted to the problem of a neural network-based robust simultaneous actuator and sensor faults estimator design for the purpose of the fault...