Amplified cathodic electrochemiluminescence of luminol based on zinc oxide nanoparticle modified Ni-foam electrode for ultrasensitive detection of amoxicillin

Journal of Solid State Electrochemistry - Here is reported a new feasible and facile method for the determination of amoxicillin by the electrochemiluminescence (ECL) method. The ECL signal was...     

A combined experimental and computational investigation of the binary mixtures of 2-methylcyclohexanol and isobutanol

Structural Chemistry - The measured densities and viscosities of the binary mixtures of the isobutanol and 2-methylcyclohexanol were reported experimentally in a certain range of concentrations at...     

Highly functionalized pyrazolines from symmetric and asymmetric 1,2-disulfonylhydrazines: a combination of experimental and DFT perspectives

Chemistry of Heterocyclic Compounds - In this work, new pyrazole derivatives were prepared by one-pot three-component reaction emloying symmetric and asymmetric 1,2-disulfonyl-hydrazines,...     

Investigation of viscoelastic focusing of particles and cells in a zigzag microchannel

Microfluidic particle focusing has been a vital prerequisite step in sample preparation for downstream particle separation, counting, detection, or analysis, and has attracted broad applications in biomedical and chemical areas. Besides all the active and passive focusing methods in Newtonian fluids, particle focusing in viscoelastic fluids has been attracting increasing interest because of its advantages induced by intrinsic fluid property. However, to achieve a well-defined focusing position, there is a need to extend channel lengths when focusing micrometer-sized or sub-microsized particles, which would result in the size increase of the microfluidic devices. This work investigated the sheathless viscoelastic focusing of particles and cells in a zigzag microfluidic channel. Benefit from the zigzag structure of the channel, the channel length and the footprint of the device can be reduced without sacrificing the focusing performance. In this work, the viscoelastic focusing, including the focusing of 10 μm polystyrene particles, 5 μm polystyrene particles, 5 μm magnetic particles, white blood cells (WBCs), red blood cells (RBCs), and cancer cells, were all demonstrated. Moreover, magnetophoretic separation of magnetic and nonmagnetic particles after viscoelastic pre-focusing was shown. This focusing technique has the potential to be used in a range of biomedical applications.     

Effect of source strength on dislocation pileups in the presence of stress gradients

The behaviour of a dislocation pileup with a finite-strength source is investigated in the presence of various stress gradients within a continuum model where a free-dislocation region exists around the source. Expressions for dislocation density and stress field within the pileup are derived for the situation where there are first and second spatial gradients in applied stress. For a pileup configuration under an applied stress, yielding occurs when the force acting on the leading dislocations at the pileup tips reaches the obstacle strength, and at the same time, it is required that the source be at the threshold stress for dislocation production. A numerical methodology is presented to solve the underlying equations that represent the yielding conditions. The yield stress calculated for a pileup configuration is found to depend on stress gradients, obstacle spacing and source/obstacle strengths. It increases with increasing the first stress gradient, yet dependent on the second stress gradient. Furthermore, while the dependency of yield stress on the obstacle spacing intensifies with increasing the first stress gradient, it diminishes with an increase of second stress gradient. Therefore, the second stress gradient, as a newly introduced parameter, can provide a new physical insight into the size-dependent plasticity phenomena at small length scales.     

Synthesis and Characterization of H3PW12O40 and H3PMo12O40 Nanoparticles by a Simple Method

In this study H₃PW₁₂O₄₀·9H₂O and H₃PMo₁₂O₄₀·6H₂O (HPA) particles were changed into nano forms by heat-treatment in an autoclave as a simple, repaid, inexpensive and one step method. The particle size of these nanoparticles was around 25 nm. The as-synthesized nanostructures were characterized by dynamic light scattering, X-ray powder diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy and inductively coupled plasma analyzer. Thermal stability of nanoparticles was surveyed by thermal gravimeter analyse. Acidity of prepared nanoparticles was investigated by pyridine adsorption method. Results showed rising acidity by declining particle size of HPA.     

The analysis of structural and electronic properties for assessment of intramolecular hydrogen bond (IMHB) interaction: a comprehensive study into the effect of substitution on intramolecular hydrogen bond of 4-nitropyridine-3-thiol in ground and electronic excited state

The hydrogen bond strength, molecular geometry, π-electron delocalization, and physical properties such as dipole moment, chemical potential, and chemical hardness of 4-nitropyridine-3-thiol and its 29 derivatives have been studied by means of density functional method with 6-311++G** basis set in gas phase and water solution. Also, the excited-state properties of intramolecular hydrogen bonding in these systems have been investigated theoretically using the time-dependent density functional theory method. The HOMA, NICS, PDI, ATI, FLU, and FLU_π indices as well-established aromaticity indicators have been examined. Natural bond orbital analysis is also performed for better understanding the nature of intramolecular interactions. The electron density and Laplacian (?² ρ) properties, estimated by AIM calculations, indicate that H···O bond possesses low ρ and positive ?² ρ values, which are in agreement with electrostatic character of the HBs, whereas S–H bond has covalent character. Numerous correlations between topological, geometrical, and energetic parameters are also found.     

Synthesis and properties of thermally stable polyimides bearing pendent fluorene moieties

A new diamine monomer containing fluorene unit, 3,5‐diamino‐N‐(9H‐fluoren‐2‐yl)benzamide was successfully synthesized via the condensation of 2‐aminofluorene and 3,5‐dinitrobenzoyl chloride and subsequent reduction of the dinitro compound. A series of novel aromatic polyimides having pendent fluorenamide moieties were prepared from the reaction of the diamine monomer and various tetracarboxylic dianhydrides by a conventional two‐step polymerization process. The polyimides were obtained in quantitative yields with inherent viscosities of 0.33–0.44 dl/g. The resulting polymers dissolved in N‐methyl‐2‐pyrrolidinone, N,N‐dimethylacetamide, N,N‐dimethylformamide, and dimethyl sulfoxide. The glass transition temperature of these polymers was in the range of 261–289°C. They were fairly stable up to a temperature around 450°C and lost 10% weight in the range of 498–556°C in nitrogen. The UV–vis absorption spectra showed that all of the polymers had absorption maxima around 320 nm. Cyclic voltammograms of the polyimides revealed an oxidation wave with a peak around 1.3 V. Copyright © 2014 John Wiley & Sons, Ltd.     

Simultaneous extraction and preconcentration of copper,silver and palladium with modified alumina and their determination by electrothermal atomic absorption spectrometry

In the present work,an easy solid phase extraction method using alumina modified with polyethylenimine as a new adsorbent was applied to the simultaneous extraction of copper,silver,and palladium ions prior to their determination with electrothermal atomic absorption spectrometry.The analytical procedure involved the complex formation of these cations with polyethylenimine as a chelating agent in buffer media of pH 7.0.Under the optimum conditions,a preconcentration factor of200,150,and 200,precision of ±5.4%,±4.7%,and ±5.2%and linear calibration ranges of 15.0-140,4.0-93,and 7.5-125 ng/L(in original solution) for Cu,Ag,and Pd were obtained,respectively.Also detection limits of3.9,1.1,and 2.0 ng/L were obtained for Cu,Ag,and Pd,respectively.The proposed method was applied to the determination of copper,silver,and palladium in some real samples with satisfactory results.