Synthesis,characterization, and biological activity of [2‐oxo‐2‐(4‐acetyl) phenyl amino] ethylene methacrylate and its derivatives

A new type of methacrylate monomer, [2‐oxo‐2‐(4‐acetyl) phenyl amino] ethylene methacrylate (APEMA), was synthesized. The oxime, 2,4‐dinitrophenylhydrazone, and thiosemicarbazone derivatives of poly{[2‐oxo‐2‐(4‐acetyl) phenyl amino] ethylene methacrylate} [poly(APEMA)] were prepared with hydroxylamine hydrochloride, 2,4‐dinitrophenylhydrazine, and thiosemicarbazone hydrochloride, respectively. The radical homopolymerization of APEMA was performed at 65 °C in a 1,4‐dioxane solution with benzoyl peroxide as an initiator. The monomer and its homopolymer were characterized with Fourier transform infrared and NMR techniques. The thermal stabilities of poly(APEMA) and its derivatives were investigated with thermogravimetric analysis and differential scanning calorimetry. The ultraviolet stability of the polymers were compared. The solubility and inherent viscosity of the polymers were also determined. The number‐average and weight‐average molecular weights and polydispersity index of the polymers were determined with gel permeation chromatography. The antibacterial and antifungal effects of the monomer and the polymer and its derivatives were also investigated on various bacteria and fungi. The activation energies of the thermal degradation of the polymers were calculated with the Ozawa method. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3157–3169, 2004     

Analytical TEM examinations of CoPt-TiO2 perpendicular magnetic recording media.

For this analytical TEM study, nonmagnetic oxygen-rich boundaries were introduced into Co-Pt-alloy perpendicular recording media by cosputtering Co and Pt with TiO2. Increasing the TiO2 content resulted in changes to the microstructure and elemental distribution within grains and boundaries in these films. EFTEM imaging was used to generate composition maps spanning many tens of grains, thereby giving an overall depiction of the changes in elemental distribution occurring with increasing TiO2 content. Comparing EFTEM with spectrum-imaging maps created by high-resolution STEM with EDXS and EELS enabled both corroboration of EFTEM results and quantification of the chemical composition within individual grain boundary areas. The difficulty of interpreting data from EDXS for these extremely thin films is discussed. Increasing the TiO2 content of the media was found to create more uniformly wide Ti- and O-rich grain boundaries as well as Ti- and O-rich regions within grains.     

Charge transfer efficiency in hybrid bulk heterojunction composites

On the basis of recently published electrochemical measurements, the charge transfer efficiency within CdSe nanocrystal/conducting polymer heterojunction composites was investigated by means of luminescence interaction strength. It was found that poly[2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylenevinylene] and poly-9-vinylcarbazole luminescence was not totally quenched by nanocrystals, whereas poly-3-octylthiophene and polyvinylpyrrolidone was completely quenched. In case of poly-3-hexylthiophene, the nanocrystal luminescence was quenched. The results are in complete agreement with the electrochemical findings and thus, the CdSe nanocrystal/Polyvinylpyrrolidone composite should be a promising material for electroluminescent devices.     

Synthesis, spectral and thermal properties of homo- and copolymers of 2-[(5-methylisoxazol-3-yl)amino]-2-oxo-ethyl methacrylate with styrene and methyl methacrylate and determination of monomer reactivity ratios

The methacrylate monomer, 2-[(5-methylisoxazol-3-yl)amino]-2-oxo-ethyl methacrylate (IAOEMA), was synthesized by reacting 2-chloro-N-(5-methylisoxazol)acetamide dissolved in acetonitrile with sodium methacrylate in the presence of triethylbenzylammoniumchloride (TEBAC). The free-radical-initiated copolymerization of IAOEMA, with styrene (ST) and methyl methacrylate (MMA) was carried out in dimethylsulphoxide (DMSO) solution at 65 °C using 2,2^′-azobisisobutyronitrile (AIBN) as an initiator with different monomer-to-monomer ratios in the feed. The monomer (IAOEMA) and copolymers were characterized by FTIR, ¹H- and ¹³C-NMR spectral studies. The copolymer composition was evaluated by nitrogen content in polymers led to the determination of reactivity ratios. The reactivity ratios of the monomers were determined by the application of Fineman-Ross and Kelen-Tüdös methods. The analysis of reactivity ratios revealed that ST and MMA are more reactive than IAOEMA, and copolymers formed are statisticalle in nature. The molecular weights (M_w and M_n) and polydispersity index of the polymers were determined using gel permeation chromagtography. Glass transition temperatures of the copolymers were found to increase with an increase in the mole fraction of IAOEMA in the copolymers. The apparent thermal decomposition activation energies (E_d) were calculated by Ozawa method using the SETARAM Labsys TGA thermobalance.     

Molar conductance of aqueous solutions of sodium, potassium, and nickel trifluoromethanesulfonate at 25‡C

The electrical conductivities of aqueous solutions of NaCF₃SO₃, KCF₃SO₃, and Ni(CF₃SO₃)₂ have been measured at 25‡C in the concentration range 1 to 25X 10^-3 mol-dm^-3 The data approach the Onsager limiting law at low concentrations, leading to a limiting molar ion conductivity for the CF₃SO ₃ ⁻ ion of 44.5±0.2 S-cm²-mol^-1, based on standard values for the cations. Using a simple size parameter for unsymmetrical polyatomic ions, based on the ion geometry, it is shown that the well known empirical relation between the molar conductivities of symmetrical ions and their radii can be extended to include certain polyatomic anions including CF₃SO ₃ ⁻ . The results suggest that the CF₃SO ₃ ⁻ ion is either a weak structure breaker in aqueous solution or neutral in this respect.     

New Methacrylate Copolymers Based on the Benzofurane Ring: Synthesis,Characterization, Monomer Reactivity Ratios and Biological Activity

The free radical copolymerization of (5-bromo-1-Benzofuran-2-yl)(phenyl)-O-methacrylketoxime (BPMKO) with 2-(4-acetylphenoxy)-2-oxoethyl-2-methylacrylate(AOEMA) has been carried out in 1, 4-dioxane at 65°C ± 1 and was analyzed by Fourier transform infrared, ¹H-NMR, ¹³C-NMR and gel permeation chromatography. Elemental analysis was used to determine the molar fractions of BPMKO and AOEMA in the copolymers. The monomer–reactivity ratios were calculated according to the general copolymerization equation using Kelen-Tüdõs and Finemann-Ross linearization methods. The reactivity ratios indicated a tendency toward random copolymerization. The polydispersity indices of the polymers were determined by gel permeation chromatography and suggested a strong tendency for chain termination by disproportionation. The thermal behaviors of copolymers with various compositions were investigated by differential scanning calorimetry and thermogravimetric analysis. The glass-transition temperature of the copolymers increased with increasing BPMKO content in the copolymers. All the products showed moderate activity against different strains of bacteria and fungi.     

Stereochemical assignments of aldol products of 2‐arylimino‐3‐aryl‐thiazolidine‐4‐ones by 1H NMR

The aldol reactions of 2‐arylimino‐3‐aryl‐thiazolidine‐4‐ones with benzaldehyde carried out at ?78 °C were found to produce sec‐carbinols. Intramolecular hydrogen bonding within the aldol products forming a six‐membered ring enabled the assignment of stereochemistries of the major and minor diastereomers via analysis of the syn and anti ³J_H,H ¹H NMR coupling constants. Copyright © 2012 John Wiley & Sons, Ltd.     

Chaotic dynamics of resistively coupled DC-driven distinct Josephson junctions and the effects of circuit parameters

Two distinct Josephson junctions (JJs) connected with a constant coupling resistance R_cp are theoretically considered to investigate the overall dynamics below and above the critical current I_c. The circuit model of the device is driven by two DC current sources, I₁ and I₂. Each junction is characterized by a nonlinear resistive–capacitive junction (NRCSJ). Having constructed the circuit model, time-dependent simulations are carried out for a variety of control parameter sets. Common techniques such as bifurcation diagrams, two-dimensional attractors and Lyapunov exponents are applied for the determination of chaotic as well as periodic dynamics of the superconducting junction devices. According to the findings, two states (namely superconducting and ordinary conducting) are determined as functions of the source currents. The chaotic current which flows through R_cp exhibits a very rich behavior depending on the source currents I₁ and I₂ and junction capacitances C₁ and C₂. The device characteristics are summarized by a number of three-dimensional phase diagrams in the parameter space. In addition, for certain parameters, hyper-chaotic cases with two positive Lyapunov exponents are encountered. In contrast to earlier studies claiming the need for a sinusoidal feeding current for generating a chaotic signal, our circuitry can easily generate one via a DC source.