Thiomorpholine-functionalized nanoporous mesopore as a sensing material for Cd2+ carbon paste electrode

A new thiomorpholine-functionalized nanoporous mesopore Mobil Composition of Matter No. 41 (MCM-41), abbreviated as TMMCM-41, was synthesized and applied as a sensing material in construction of a cadmium carbon paste electrode. The electrode composition of 20.1%wt TMMCM-41, 54.0% graphite powder, 25.9% paraffin oil showed the stable potential response to Cd²⁺ ions with the Nernstian slope of 28.6 mV decade^?1 (±1.8 mV decade^?1) over a wide linear concentration range of 10^?6 to 10^?2?mol L^?1 with a detection limit of 6?×?10^?7 mol L^?1. The electrode has fast response time and long-term stability (more than 4 months). The proposed electrode was used to determine the concentration of cadmium in tap water contaminated by this metal and cadmium electroplating waste water samples.     

Nano TiO2 Modified Carbon‐ceramic Electrode and Its Application for Electrocatalytic Oxidation of NADH

The electrocatalytic oxidation of nicotinamide adenine dinucleotide (NADH) was studied on nanoTiO₂ modified sol‐gel electrode, using cyclic voltammetry, chronoamperometry and differential pulse voltammetry as diagnostic techniques. It is demonstrated that TiO₂ nanoparticles on sol‐gel network catalyze the oxidation of NADH in the absence of any electron transfer mediators. Effect of various parameters such as pH, scan rate, TiO₂ percentage on the response of modified electrode was studied. In addition, scanning electron microscopy (SEM) was used to characterize the surface morphology of the spots. A dynamic range between 0.5–50 μM with detection limit of 0.35 μM was obtained with DPV studies. This method was successfully used for determination of NADH in cucumber cotyledons samples. The electrode showed relatively good stability over more than 2 months.     

Nuclear magnetic resonance study of the stoichiometry and stability of several HgX<Subscript>2</Subscript>–acetylemethylentriparatolylphosphorane complexes in various acetone–dimethylformamide mixtures

The reaction of phosphorus ylide, acetylmethylenetriparatolylphosphorane (L) with HgX₂ (X = Cl, Br, I and NO₃) in equimolar ratios using acetone and dimethylformamide as solvents leads to binuclear products. ³¹P NMR spectroscopy was used to investigate the stoichiometry and stability of a HgX₂ complex with CH₃COCHP(p-tolyl)₃ (L) in binary acetone–dimethylformamide mixtures of varying composition. In all cases studied, the variation of ³¹P NMR chemical shift with the [HgX₂]/[L] mole ratio indicated the formation of 1:1 complexes. The formation constants of the resulting complexes were evaluated from computer fitting of the mole ratio data to an equation that relates the observed chemical shifts to the formation constant. In all mercuric salts used, the stabilities of the resulting 1:1 complexes varied in the order Hg(NO₃)₂ > HgCl₂ > HgBr₂ > HgI₂. It was found that, in the case of all complexes, an increase in the percentage of dimethylformamide in the solvent mixtures significantly decreases the stability of the complexes.     

Ab initio study of Pd-decorated single-walled carbon nanotube with C-vacancy as CO sensor

In this paper, the adsorption of CO onto Pd-decorated (5,5) single-walled carbon nanotube (Pd/SWCNT) and Pd-doped (5,5) single-walled carbon nanotube (Pd/SWCNT-V) has been investigated using ab initio studies. The larger binding energies and charges transfer show that the adsorption of CO onto Pd/SWCNT is more stable than that of CO onto Pd/SWCNT-V. The Pd/SWCNT can be utilized as good sensors for CO molecules due to strong binding energy and large electron charge transfer between the Pd/SWCNT and this molecule. Furthermore, the topological properties of the electron density distributions for intramolecular interactions have been analyzed in terms of the Bader theory of atoms in molecules. Finally, the natural population analysis method has been used to evaluate the Pd–C and Pd/CO interactions.     

Catalytic performance in 4-nitrophenol reduction by Ag nanoparticles stabilized on biodegradable amphiphilic copolymers

Biodegradable copolymers have received much more attention in the last decades due their potential applications in the fields related to environmental protection, medicine, agriculture, and the chemical processes. Silver nanoparticles (Ag NPs) were prepared via reduction of silver nitrate (AgNO₃) using biodegradable amphiphilic copolymers in aqueous solution. The micelles were constructed from the amphiphilic copolymer composed of poly(2-ethyl-2-oxazoline) and poly(ε-caprolactone). The Ag NPs with a diameter of 10–15?nm were found to show a comparable high catalytic activity toward the reduction of 4-nitrophenol (4-NP) in the presence of an excess amount of NaBH₄. The synthesized Ag NPs-loaded copolymer exhibits high catalytic activity for the reduction of 4-NP to 4-aminophenol.     

Spectrophotometric determination of ternary mixtures of thiamin, riboflavin and pyridoxal in pharmaceutical and human plasma by least-squares support vector machines.

Ternary mixtures of thiamin, riboflavin and pyridoxal have been simultaneously determined in synthetic and real samples by applications of spectrophotometric and least-squares support vector machines. The calibration graphs were linear in the ranges of 1.0 - 20.0, 1.0 - 10.0 and 1.0 - 20.0 microg ml(-1) with detection limits of 0.6, 0.5 and 0.7 microg ml(-1) for thiamin, riboflavin and pyridoxal, respectively. The experimental calibration matrix was designed with 21 mixtures of these chemicals. The concentrations were varied between calibration graph concentrations of vitamins. The simultaneous determination of these vitamin mixtures by using spectrophotometric methods is a difficult problem, due to spectral interferences. The partial least squares (PLS) modeling and least-squares support vector machines were used for the multivariate calibration of the spectrophotometric data. An excellent model was built using LS-SVM, with low prediction errors and superior performance in relation to PLS. The root mean square errors of prediction (RMSEP) for thiamin, riboflavin and pyridoxal with PLS and LS-SVM were 0.6926, 0.3755, 0.4322 and 0.0421, 0.0318, 0.0457, respectively. The proposed method was satisfactorily applied to the rapid simultaneous determination of thiamin, riboflavin and pyridoxal in commercial pharmaceutical preparations and human plasma samples.     

A novel catalytic method for the regeneration of carbonyl compounds from oximes using aluminum nitrate and NaBr as catalyst

<正>A wide variety of aldoximes and ketoximes were regenerated to corresponding carbonyl compounds with Al(NO_3)_3·9H_2O in presence of catalytic amounts of NaBr in CH_2Cl_2 at room temperature.     

Ultrasound-enhanced Green Synthesis of 5,5-Diphenylhydantoin Derivatives Using Symmetrical or Unsymmetrical Benzils

A rapid, highly efficient and mild green synthesis of 5,5‐diphenylhydantoin derivatives was achieved from the reaction of symmetrical or unsymmetrical benzil derivatives with urea in the presence of ethanolic KOH under ultrasound irradiation. This simple method affords 5,5‐diphenylhydantoin derivatives at room temperature in short reaction time with high yield and purity. This study aimed to overcome the limitations and drawbacks of the reported methods such as tedious work‐up, low yield and long reaction time.     

Iterative algorithms for systems of extended regularized nonconvex variational inequalities and fixed point problems

This paper points out some fatal errors in the equivalent formulations used in Noor 2011 [Noor MA. Projection iterative methods for solving some systems of general nonconvex variational inequalities. Applied Analysis. 2011;90:777–786] and consequently in Noor 2009 [Noor MA. System of nonconvex variational inequalities. Journal of Advanced Research Optimization. 2009;1:1–10], Noor 2010 [Noor MA, Noor KI. New system of general nonconvex variational inequalities. Applied Mathematics E-Notes. 2010;10:76–85] and Wen 2010 [Wen DJ. Projection methods for a generalized system of nonconvex variational inequalities with different nonlinear operators. Nonlinear Analysis. 2010;73:2292–2297]. Since these equivalent formulations are the main tools to suggest iterative algorithms and to establish the convergence results, the algorithms and results in the aforementioned articles are not valid. It is shown by given some examples. To overcome with the problems in these papers, we consider a new system of extended regularized nonconvex variational inequalities, and establish the existence and uniqueness result for a solution of the aforesaid system. We suggest and analyse a new projection iterative algorithm to compute the unique solution of the system of extended regularized nonconvex variational inequalities which is also a fixed point of a nearly uniformly Lipschitzian mapping. Furthermore, the convergence analysis of the proposed iterative algorithm under some suitable conditions is studied. As a consequence, we point out that one can derive the correct version of the algorithms and results presented in the above mentioned papers.