An electropolymerized aniline-based fiber coating for solid phase microextraction of phenols from water

An aniline-based polymer was electrochemically prepared and applied as a new fiber coating for solid phase microextraction (SPME) of some priority phenols from water samples. The polyaniline (PANI) film was directly electrodeposited on the platinum wire surface in sulfuric acid solution using cyclic voltammetry (CV) technique. The efficiency of new coating was investigated using a laboratory-made SPME device and gas chromatography with flame ionization detection for the extraction of some phenols from the headspace of aqueous samples. The scanning electron microscopy (SEM) images showed the homogeneity and the porous surface structure of the film. The results obtained proved the ability of this polymer as a suitable SPME fiber coating for trapping the selected phenols. Influential parameters affecting the extraction process were optimized and an extraction time of 50 min at 50 °C gave maximum efficiency, when the aqueous sample was saturated with NaCl and adjusted at pH 2. This new coating can be prepared easily in a reproducible manner and it is rather inexpensive and stable against most of organic solvents. The PANI thickness can be precisely controlled by the number of CV cycles. At the optimum conditions, the R.S.D. for a double distilled water spiked with phenol and chlorophenols at ppb level were 4.8-17% (n = 3) and detection limits for the studied compounds were between 0.69 and 3.7 ng ml⁻¹, except for phenol and 4-chlorophenol. The optimized method was successfully applied to some real-life water samples.     

Network of nano-droplets by a tri-block polymer

Mixtures of oil in water nano-droplets with two molecular weights of a tri-block polymer was studied by quasi elastic light scattering and small angle X-ray scattering. The results showed that the size and interaction of droplets didn’t change with increase of the tri-block polymer length but the order parameters increased. The increase of length of the tri-block biopolymer changed the dynamics of the droplets. A network formation is resulted with increase of the amount of tri-block polymer in the microemulsions.     

Effect of concentration and particle size on nonlinearity of Au nano-fluid prepared by γ (Co) radiation

Nonlinear properties of Au nano-fluid prepared by γ-radiation method at different concentrations were investigated. Measurements of nonlinear refractive index and nonlinear absorption coefficient were carried out using a single beam Z-scan technique. A green CW laser beam operated at 532 nm was used as excitation source. The Au nano-fluid shows a good third order nonlinear response. The sign of the nonlinear refractive index is found to be negative and the magnitude is in the order of 10⁻⁷ cm²/W. This nonlinear effect increases as the concentration increases from 3.119 × 10⁻⁴ to 2.354 × 10⁻³ M which correspond to particle sizes of 4.0-30.5 nm, respectively. A good linear relationship was obtained between nonlinear refractive index and concentration. However the relationship between nonlinear refractive index and particle size was nonlinear behavior.     

On doubly warped product Finsler manifolds

In this paper, we introduce horizontal and vertical warped product Finsler manifolds. We prove that every C-reducible or proper Berwaldian doubly warped product Finsler manifold is Riemannian. Then, we find the relation between Riemannian curvatures of doubly warped product Finsler manifold and its components, and consider the cases that this manifold is flat or has scalar flag curvature. We define the doubly warped Sasaki-Matsumoto metric for warped product manifolds and find a condition under which the horizontal and vertical tangent bundles are totally geodesic. We obtain some conditions under which a foliated manifold reduces to a Reinhart manifold. Finally, we study an almost complex structure on the tangent bundle of a doubly warped product Finsler manifold.     

Strong red emissions induced by Pt–Pt interactions in binuclear cycloplatinated(II) complexes containing bridging diphosphines

A series of dinuclear cycloplatinated(II) complexes with general closed formula of [Pt₂Me₂(C^N)₂(μ‐P^P)] (C^N = 2‐vinylpyridine (Vpy), 2,2′‐bipyridine N‐oxide (O‐bpy), 2‐(2,4‐difluorophenyl)pyridine (dfppy); P^P = 1,1‐bis(diphenylphosphino)methane (dppm), N,N‐bis(diphenylphosphino)amine (dppa)) are reported. The complexes were characterized by means of NMR spectroscopy. Due to the presence of dppm and dppa with short backbones as bridging ligands, two platinum centres are located in front of each other in these complexes so a Pt…Pt interaction is established. Because of this Pt…Pt interaction, the complexes have bright orange colour under ambient light and are able to strongly emit red light under UV light exposure. These strong red emissions originate from a ³MMLCT (metal–metal‐to‐ligand charge transfer) electronic transition. In most of these complexes, the emissions have unstructured bell‐shaped bands, confirming the presence of large amount of ³MMLCT character in the emissive state. Only the complexes bearing dfppy and dppa ligands reveal dual luminescence: a high‐energy structured emission originating from ³ILCT/³MLCT (intra‐ligand charge transfer/metal‐to‐ligand charge transfer) and an unstructured low‐energy band associated with ³MMLCT. In order to describe the nature of the electronic transitions, density functional theory calculations were performed for all the complexes.     

Asymmetric and axisymmetric vibrations of finite transversely isotropic circular cylinders

This paper presents an approach for obtaining the exact frequency equations of axisymmetric and asymmetric free vibrations of transversely isotropic circular cylinders. The solution method is based on the three dimensional theory of linear elasticity and uses potential functions. Using this approach, the frequency spectra and vibration mode shapes are plotted for a number of transversely isotropic cylinders. The proposed approach introduces a number of merits compared to earlier approximate and exact solution methods. First, unlike numerically complicated series methods that provide approximate solutions, the proposed approach is exact. Second, combination of scalar functions employed for representing the displacement field is consistent with the physics of the problem. One scalar potential function has been considered for each component of the wave field inside the elastic cylinder. As a result, the solution is systematically divided into coupled and decoupled equations. In addition, by using this approach, there is no need to guess the final of the solution a priori. These merits make the proposed approach suitable for other vibration problems of anisotropic materials.     

Design,synthesis and antibacterial activity evaluation of novel 2-(4-((1-aryl-1H-1,2,3-triazol-4-yl)methoxy)phenyl)2-(2-oxoazetidin-1-yl)acetamide derivatives

In this paper, a novel series of 2-(4-((1-aryl-1H-1,2,3-triazol-4-yl)methoxy)phenyl)2-(2-oxoazetidin-1-yl)acetamide derivatives are synthesized in two steps. The first step involved Ugi multicomponent reaction of β-alanine, o-(propargyl)benzaldehyde and isocyanide derivatives. The product of this step, underwent a click 1,3-dipolar cycloaddition reaction with benzyl azide derivatives. The 2-(4-((1-aryl-1H-1,2,3-triazol-4-yl)methoxy)phenyl)2-(2-oxoazetidin-1-yl)acetamide product was characterized and their antibacterial activities were evaluated against various G-positive (Staphylococcus aureus and Bacillus subtilis) and G-negative (Pseudomonas aeruginosa and Escherichia coli) bacteria, using minimal inhibition concentration. The compounds showed very good antimicrobial activity and a number of products have been more active than ciprofloxacin.     

Correlation between helical surface waves and guided modes of an infinite immersed elastic cylinder

Scattering of obliquely incident plane acoustic waves from immersed infinite solid elastic cylinders is a complex phenomenon that involves generation of various types of surface waves on the body of the cylinder. Mitri [F.G. Mitri, Acoustic backscattering enhancement resulting from the interaction of an obliquely incident plane wave with an infinite cylinder, Ultrasonics 50 (2010) 675-682] recently showed that for a solid aluminum cylinder, there exist acoustic backscattering enhancements at a normalized frequency of ka?0.1. The incidence angle α_c at which these enhancements are observed lies between the first (longitudinal) and second (shear) coupling angles of the cylinder. He also confirmed the observations previously reported by the authors that there exist backscattering enhancements of the dipole mode at large angles of incidence where no wave penetration into the cylinder is expected. In this paper, physical explanations are provided for the aforementioned observations by establishing a correlation between helical surface waves generated by oblique insonification of an immersed infinite solid elastic cylinder and the longitudinal and flexural guided modes that can propagate along the cylinder. In particular, it is shown that the backscattering enhancement observed at ka?0.1 is due to the excitation of the first longitudinal guided mode travelling at the bar velocity along the cylinder. It is also demonstrated that the dipole resonance mode observed at incidence angles larger than the Rayleigh coupling angle is associated with the first flexural guided mode of the cylinder. The correlation established between the scattering and propagation problems can be used in both numerical and experimental studies of interaction of mechanical waves with cylinders.     

Some curvature properties of Cartan spaces with mth root metrics

In this paper, we define some non-Riemannian curvature properties for Cartan spaces. We consider a Cartan space with the mth root metric. We prove that every mth root Cartan space of isotropic Landsberg curvature, or isotropic mean Landsberg curvature, or isotropic mean Berwald curvature reduces to a Landsberg, weakly Landsberg, and weakly Berwald spaces, respectively. Then we show that the mth root Cartan space of almost vanishing H-curvature satisfies H?=?0.