Preparation of hollow beads of poly(styrene-co-divinyl benzene)

Two methods are described for the production of hollow beads by copolymerization of styrene and divinyl benzene. Characterization of the beads is described and growth mechanisms proposed.     

Synthesis and Liquid Crystalline Behavior of Random Copolymer of Poly(ethylene oxide) Macromonomer and Liquid Crystalline Monomer by the Photon Transmission Technique

Random copolymers of poly(ethylene oxide) macromonomer with p‐vinylbenzyl end‐functional group (PEOVB) and liquid crystalline monomer, namely 6‐(4‐cyanobiphenyl‐4′‐oxy)hexyl acrylate (COA), were prepared by conventional free radical polymerization. A living anionic polymerization technique was employed for the synthesis of PEO macromonomers bearing p‐vinylbenzyl moiety at one end. The photon transmission method was also applied to study the phase transitions of COA monomer and its random copolymer with PEO. It was found that, for both samples, the nematic‐smectic A transition is continuous, but the critical fluctuation regions do not allow to obtain 3D XY values. Instead, we have obtained the values close to mean field regime. Scaling of thermal hystersis for random copolymer sample near the nematic‐isotropic transition was studied as well. Thermal hysteresis loops were produced under linearly varying temperature. It was shown that the areas of the hysteresis loops scale with the temperature scanning rate with an exponent being equal to 0.614 which is in good agreement with the field‐theoretical value.     

An electrochemical chiral sensor based on electrochemically modified electrode for the enantioselective discrimination of D-/L-tryptophan

Journal of Solid State Electrochemistry - Chirality is a universal characteristic of natural systems and discrimination of enantiomers of a chiral molecule plays a major role particularly in...     

Poly(vinylferrocenium) coated disposable pencil graphite electrode for DNA hybridization

Poly(vinylferrocenium) (PVF⁺) modified electrode was developed in this study for the electrochemical sensing of DNA based on the oxidation signals of polymer, adenine and guanine. Experimental parameters, such as; polymeric film thickness, DNA immobilization time and DNA concentration were examined in order to obtain more sensitive and selective electrochemical signals. After optimization studies, DNA hybridization was investigated.     

Electrochemical Investigation of Heavy Metal Ion Transfer Across the Water/1,2‐Dichloroethane Interface Assisted by 9‐Ethyl‐3‐Carbazolecarboxaldehyde‐Thiosemicarbazone

The transfer of heavy metal ions across the polarized water/1,2‐dichloroethane (1,2‐DCE) interface assisted by 9‐ethyl‐3‐carbazolecarboxaldehyde‐thiosemicarbazone (ECCAT) in the 1,2‐DCE phase has been studied by cyclic voltammetry. Voltammetric waves of Pb(II) and Cd(II) ions were reversible and quasi‐reversible, respectively, whereas that of Hg(II) and Zn(II) ion were irreversible. The voltammogram of Cu(II) ion showed a two‐step wave, however the nature of the transfer could not be satisfactorily evaluated by analyzing the cyclic voltammetric data. When Ni(II) and Co(II) was used no peak was visible under the experimental conditions used in this study. The dependence of the half‐wave potentials of Pb(II) and Cd(II) ions on the ligand concentration reveals that their ion‐transfer is assisted by the formation of 1:3 metal‐ECCAT complex in 1,2‐DCE. The over‐all association constants of [Pb(ECCAT)₃]²⁺ and [Cd(ECCAT)₃]²⁺ complexes in DCE‐phase have been determined to be log β =14.03 and log β =15.44, respectively.     

New Copper（Ⅱ） and Nickel（Ⅱ） Complexes of 4-Morpholinoacetophenone Thiosemicarbazone： Structural, Electrochemical and Antimicrobial Studies

4-Morpholinoacetophenone thiosemicarbazone, MAPT, and its nickel（Ⅱ） and copper（Ⅱ） complexes have been prepared and characterized by elemental analysis, magnetic susceptibility, spectral methods （FT-IR, ^1H NMR） and cyclic voltammetry. Electrochemical behaviors of the complexes have been studied by cyclic voltammetry in DMF media showing metal centered reduction processes for both of them. The redox properties, nature of the electrode processes and the stability of the complexes were discussed. [Cu（MAPT）2]Cl2 complex shows Cu（Ⅱ）/Cu（Ⅰ） couple and quasi-reversible wave associated with the Cu（Ⅲ）/Cu（Ⅱ） process. The reduction/oxidation potential values depend on the structures of complexes. Also, the antimicrobial activities of these complexes were determined against S. aureus, E. coli and B. subtilis.     

Facilitated Proton Transfer by a Novel 2-Aminothiazole Derivative Across the Water/1,2-Dichloroethane Interface

The behavior of proton transfer facilitated by a novel thiazole derivative, N-methyl-4-(4-phenoxyphenyl)thiazol-2-amine (MPPT), across the water/1,2-dichloroethane (1,2-DCE) interface was investigated electrochemically. The ionic partition diagram for MPPT was obtained from interpretation of the cyclic voltammograms. The apparent partition coefficient of MPPT was evaluated by the shaking-flask method under experimental conditions, while that for the protonated form of MPPT was calculated from its transfer potential obtained from the ionic partition diagram. It was suggested that the mechanism for transfer of MPPT across the water/1,2-DCE) interface depends on the pH of the aqueous phase. The parameters of the facilitated proton transfer across the water/1,2-DCE interface were evaluated as a quantitative measure of its lipophilicity.     

Weight reduction for mod ? Bianchi modular forms

Let K be an imaginary quadratic field with class number one and ? be a rational prime that splits in K. We prove that mod ?, a system of Hecke eigenvalues occurring in the first cohomology group of some congruence subgroup Γ of SL₂(OK) can be realized, up to twist, in the first cohomology with trivial coefficients after increasing the level of Γ by (?).     

Synthesis and electrochemical properties of a novel calix[4]arene derivative for facilitated transfer of alkali metal ions across water/1,2-dichloroethane micro-interface

The alkali metal ion transfers facilitated by a novel calix[4]arene derivative (OPEC) across the water/1,2-dichloroethane (1,2-DCE) micro-interface supported at the tip of a micropipette were presented. The well-defined voltammetric behaviours except Cs⁺ was obtained by cyclic voltammetry and differential pulse voltammetry. The bulk concentration of metal ions was much higher than that of OPEC in the performed measurements. The diffusion coefficient of OPEC in the 1,2-DCE phase was calculated as 5.18 ± 0.70 × 10^? 6 cm² s^? 1. On the basis of the changes of the half-wave transfer potentials, the logarithms of the association constants having 1:1 ionophore–ion complex stoichiometry for Li⁺, Na⁺, K⁺ and Rb⁺ in 1,2-DCE were determined as 4.80, 4.62, 4.98 and 5.32, respectively. The facilitated ion transfers were also evaluated by the Randles equivalent circuit used for ac-impedance data analysis.     

Simulation Model of a Multi-Shuttle System

Journal of the Operational Research Society - This paper reports on a study of modelling a shuttle transportation system. There were three objectives, the first was to consider alternative ways of...