Synthesis and Antimicrobial Studies of New Bis[4,5‐dihydro‐1‐phenyl‐5‐thienyl‐3‐(phenyl‐4‐alkoxy)‐1H‐pyrazole] Derivatives

Syntheses and antimicrobial behavior of the alkyl linked new bispyrazolines 4a , 4b , 4c , 4d , 4e , 4f , 4g have been investigated. These compounds exhibited better antimicrobial activities as compared with their corresponding bischalcones. The structures of the prepared compounds ( 3a , 3b , 3c , 3d , 3e , 3f , 3g and 4a , 4b , 4c , 4d , 4e , 4f , 4g ) were determined from the rigorous analysis of their IR, ¹H NMR, ¹³C NMR, and mass spectral parameters.     

Electrical properties of plasticized chitosan-lithium imide with oleic acid-based polymer electrolytes for lithium rechargeable batteries

Solid polymer electrolytes (SPEs) were prepared and their electrochemical characteristics were characterized. The composition of SPEs containing chitosan, lithium trifluoromethane sulfonimide (LiN(CF₃SO₂)₂) and oleic acid (OA) was optimized employing ac impedance measurements at various temperatures. The electrical conductivity of the SPEs with OA shows the highest value and the presence of OA does not change the structure of the polymer. Paper presented at the International Conference on Functional Materials and Devices 2005, Kuala Lumpur, Malaysia, June 6 – 8, 2005.     

Synthesis, characterization of silica gel phases-chemically immobilized-4-aminoantipyrene and applications in the solid phase extraction, preconcentration and potentiometric studies.

Two new 4-aminoantipyrene chemically-immobilized silica gel phases: ii (N,N-donor) and iii (N,O-donor), were synthesized and characterized by IR and surface coverage determination. The latter was accomplished by thermal desorption and metal probe methods, giving 0.300 and 0.312 mmol g(-1) for ii and 0.220 and 0.250 mmol g(-1) for iii. Moreover, potentiometric titration provided a surface coverage of 0.323 mmol g(-1) for ii. The metal capacity values in mmol g(-1) of ii, iii and the active silica gel phase i for a series of di- and trivalent metal ions were determined at pH 1.0 - 6.7. Phase i showed the lowest values, while ii and iii reflected higher affinity toward most of the metal ions. The highest values were 0.300 for Hg(II)-ii and 0.220 mmol g(-1) for Cd(II)-iii. Distribution coefficients (log Kd) were in the range of 3.57 - 4.76 for ii and 2.32 - 3.46 for iii, thus confirming certain selectivity characters of the solid extractors. The application of the phases as solid extractors and preconcentrators for some heavy metal ions is presented. Good percentage extraction and removal of 94 - 98 +/- 4 - 6% of the spiked 1.000 microg ml(-1) of Hg(II), Cd(II), Pb(II), Cu(II) and Zn(II) and good percentage recovery of 94 - 99 +/- 3 - 6% of 50 ng ml(-1) of these ions from tap water samples were obtained. Stability constants of H(I) and Cu(II) with ii for the two-phase mixture at 25 degrees C and I = 0.1 (KCI) were determined potentiometrically. The pKa of ii are 5.6 and 8.4, while the log K values for CuHL and CuL (L = ii) are 6.3 and 5.8, respectively, leading to the determination of several analytical data for Cu(II)-ii.     

A Result on ℵ1-Compact Spaces

We prove that every countably compact space with quasi-S₁-diagonal is compact. However, it is shown that it need not be metrizable. This revised version was published online in June 2006 with corrections to the Cover Date.     

Minimizing Curves in Prox-regular Subsets of Riemannian Manifolds

Set-Valued and Variational Analysis - We obtain a characterization of the proximal normal cone to a prox-regular subset of a Riemannian manifold and some properties of Bouligand tangent cones to...     

A highly sensitive sensor of paracetamol based on zinc-layered hydroxide-<Emphasis Type="Italic">L</Emphasis>-phenylalanate-modified multiwalled carbon nanotube paste electrode

A new zinc-layered hydroxide-L-phenylalanate (ZLH-LP)-modified multiwalled carbon nanotube (MWCNT) was prepared as a new material of paste electrode for the detection of paracetamol (PCM) in 1.0?×?10^?1 M phosphate buffer solution and at pH 7.5. The electrochemical characterization of the MWCNTs/ZLH-LP paste electrode was characterized by square wave voltammetry, electrochemical impedance spectroscopy, and cyclic voltammetry while the morphology properties of the MWCNTs, ZLH-LP, and MWCNTs/ZLH-LP were investigated using transmission electron microscopy and scanning electron microscopy. Under optimized conditions, the MWCNTs/ZLH-LP paste electrode demonstrated an excellent electrocatalytic activity towards oxidation of PCM in the linear responses’ ranges from 7.0?×?10^?7 M to 1.0?×?10^?4 M (correlation coefficient, 0.996) with the limit of detection obtained at 8.3?×?10^?8 M. As a conclusion, the MWCNTs/ZLH-LP paste electrode revealed good repeatability, reproducibility, and stability, and was found to be applicable for use in pharmaceutical tablet samples.

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Facile Method to Synthesis of Golf Ball-Like Particles via Early-Ceased Seeded Dispersion Polymerization

Golf ball-like poly(methyl methacrylate) particles were produced via seeded dispersion polymerization of 2-ethylhexyl methacrylate with poly(methyl methacrylate) seed beads in the presence of saturated hydrocarbon droplets and evaporation of the hydrocarbon after the polymerization. It was observed that the particles are acquired in the form of a stable dispersion if the reaction is ceased around 42% of monomer conversion. Moreover, the effect of different reaction conditions (e.g. hydrocarbon and stabilizer type, initiator and monomer content, and polarity of the medium) on the shape and stability of the produced particles was investigated. It was revealed that the number and size of the dents on the surface of the golf ball-like particles could be manipulated easily with a simple change in each one of the parameters referred to above. In addition, the experimental results showed that some of the particles become unstable and diffuse into each other during polymerization, resulting in the formation of huge golf ball-like objects. The production of disk-like poly(methyl methacrylate) particles via fully developed seeded dispersion polymerization in the presence of a hydrocarbon which owns lengthy alkyl chain was another interesting finding of this study.     

Voltammetric Characterization of Grafted Polymer Modified with ZnO Nanoparticles on Glassy Carbon Electrode

In this study, a grafted polymer (GP) with ZnO nanoparticles (GP/ZnO NPs) was attached on the surface of glassy carbon electrode (GCE), in order to produce a new modified electrode (GP/ZnO NPs-GCE). The gamma irradiation method was used to grafted polystyrene (polymer) with acrylonitrile (monomer), while slow evaporation process was used to prepare the new modified electrode. The cyclic voltammetry (CV) of K₄[Fe(CN)₆] was used to study the electrochemical properties GP/ZnO NPs-GCE. The peak separation (ΔE_pa-c) was 500 mV between the redox peaks of Fe(II)/Fe(III) in an aqueous solution of 1 M KCl and the current ratio of redox current peaks (I_pa/I_pc) was ≈ 1 for the modified electrode. This indicated that the modified electrode has s good reversibility and conductivity, wherefore; it was applied in the voltammetric filed. It was found that the modified electrode GP/ZnO NPs-GCE have a reasonable solubility and stability at various pH medium. Additionally, the sensitivity of the electrochemical analysis by cyclic voltammetric (CV) method is extensively subjected to the pH medium and the scan rate (SR). A couple of redox current peaks of K₄[Fe(CN)₆] in KCl solution was observed with a reversible process: Fe³⁺/Fe²⁺. Finally a good diffusion coefficient of electroactive species (D) for the new modified electrode was found in this study by chronoamperometry method using Cottrell equation.     

Nondestructive classification and identification of ballpoint pen inks by Raman spectroscopy for forensic document examinations

As a non-destructive analytical method, Raman spectroscopy often provides insufficient information to identify or differentiate the ink used for the preparation of a questioned document. In this study, blue and black ballpoint pen inks deposited on paper substrate were examined in situ by conventional Raman spectroscopy. Inks were successfully classified based on the total number of prominent bands in Raman spectra. It was found that more than 90% of the samples of the same type and color could be differentiated visually using only Raman spectra, i.e. 94 and 95% for blue and black inks, respectively. As a result of this study, a flow chart has been constructed for blue and black ballpoint pen inks allowing their systematic identification. Raman spectroscopy proved to be a fast and precise technique for forensic ink analysis.