Modules satisfying the weak Nakayama property

Let R$R$ be a commutative ring with identity. We will say that an R$R$-module M$M$ satisfies the weak Nakayama property, if IM=M$IM=M$, where I$I$ is an ideal of R$R$, implies that for any x∈M$x\in M$ there exists a∈I$a\in I$ such that (a−1)x=0$(a-1)x=0$. In this paper, we will study modules satisfying the weak Nakayama property. It is proved that if R$R$ is a local ring, then R$R$ is a Max ring if and only if J(R)$J\left(R\right)$, the Jacobson radical of R$R$, is T$T$-nilpotent if and only if every R$R$-module satisfies the weak Nakayama property.     

A novel and easy route to 1,3,4-thiadiazine derivatives via the three-component reaction of phenylhydrazine, α-bromo aryl ketones and aryl isothiocyanates

The three-component condensation of phenylhydrazine, α-bromo aryl ketones and aryl isothiocyanates leading to 1,3,4-thiadiazine derivatives is described.     

Solid phase extraction of trace amount of Cu(II) using functionalized-graphene

A novel and selective method for the fast determination of trace amounts of Cu(II) ions in water samples has been developed. The first organic-solution-processable functionalized-graphene (SPF-Graphene) hybrid material with porphyrins, porphyrin-graphene nanohybrid, 5-(4-aminophenyl)-10, 15, 20-triphenyl porphyrin and its photophysical properties including optical (TPP) and grapheme oxide molecules covalently bonded together via an amide bond (TPP-NHCO-SPFGraphene) were used as absorbent for extraction of Cu(II) ions by solid phase extraction method. The complexes were eluted with HNO₃ (2 M) 10% (vol/vol) methanol in acetone and determined the analyte by flame atomic absorption spectrometry. The procedure is based on the selective formation of Cu(II) at optimum pH by elution with organic eluents and determination by flame atomic absorption spectrometry. The method is based on complex formation on the surface of the ENVI-18 DISK? disks modified porphyrin-graphene nanohybrid, 5-(4-aminophenyl)-10,15,20-triphenyl porphyrin (TPP) and grapheme oxide molecules covalently bonded together via an amide bond (TPP-NHCO-SPFGraphene) followed by stripping of the retained species by minimum amounts of appropriate organic solvents. The elution is efficient and quantitative. The effect of potential interfering ions, pH, TPP-NHCO-SPFGraphene, amount, stripping solvent, and sample flow rate were also investigated. Under the optimal experimental conditions, the break-through volume was found to about 1000 mL providing a preconcentration factor of 600. The maximum capacity of the disks was found to be 398 ± 3 μg for Cu²⁺. The limit of detection of the proposed method is 5 ng per 1000 mL. The method was applied to the extraction and recovery of copper in different water samples.     

NMR parameters of SiC-doped (6,0) zigzag single-walled boron phosphide nanotubes: a density functional study

Abstract  

Nuclear magnetic resonance (NMR) parameters including isotropic and anisotropic chemical shielding parameters and electronic structures were calculated using density functional theory (DFT) for silicon–carbide-doped boron phosphide nanotubes. Geometry optimizations were carried out at the B3LYP/6-31G* level of theory using the Gaussian 03 program suite. The isotropic and anisotropic chemical shielding parameters were calculated for the sites of various ¹³C, ²⁹Si, ¹¹B, and also ³¹P atoms in pristine and SiC-doped (6,0) zigzag boron phosphide nanotube models. The calculations indicated that doping of ¹¹B and ³¹P atoms by C and Si atoms had a more significant influence on the calculated shielding tensors than did doping of the B and P atoms by Si and C atoms. In comparison with the pristine model, Si- and C-doping of P and B sites of the zigzag nanotubes reduces the energy gaps of the nanotubes and increases their electrical conductance.     

Voltammetric Determination of Hemoglobin Using a Pencil Lead Electrode

In this paper the electrochemical behavior of hemoglobin (Hb) immobilized on a pencil lead electrode (PLE) was investigated. Immobilization of Hb on the pencil lead electrode was performed by nonelectrochemical and electrochemical methods. In phosphate buffer solution with pH 7.0 Hb showed a pair of well‐defined and nearly reversible redox waves (the anodic and cathodic peak potentials are located at ?0.18 V and ?0.22 V, respectively). The dependence of the anodic peak potential (E_pa) on the pH of the buffer solution indicated that the conversion of Hb? Fe(III)/Hb? Fe(II) is a one‐electron‐transfer reaction process coupled with one‐proton‐transfer. In addition the effect of scan rate on peak currents and peak separation potential was investigated and electrochemical parameters such as α and k_s were calculated. In the second part of this work, the ability of the electrode for determination of Hb concentration was investigated. The results showed a linear dynamic range from 0.15 to 2 µM and a detection limit of 0.11 µM. The relative standard deviation is 4.1 % for 4 successive determinations of a 1 µM Hb solution.     

Measurement of optical and electrical properties of silicon microstructuring induced by ArF excimer laser at SF6 atmosphere

The irradiation of ArF excimer laser (193 nm) on Si wafer (〈1 1 1〉, n-type, arsenic-doped, 0.01 Ω cm) in SF₆ atmosphere, from vacuum to 1000 mbar, creates a regular self-assembled microstructure owning to a great number of microconical spikes covered with SiF₂ (fluorosilyl) layer containing sulfur impurities. The geometry of microstructure as well as the layer thickness varies with the gas pressure and the laser parameters, particularly duration, pulse energy and the dose. In this work, the electrical properties of the layer on the microstructured silicon have been investigated based on electrical impedance spectroscopy (EIS). The measured impedance significantly changes regarding to the unirradiated samples. It was shown that the corresponding electrical conductance and the dielectric constants of the layer are strongly dependent on the gas pressure and UV dose. The layer thickness was also determined in terms of SF₆ pressures.