ZnO as an Effective and Reusable Heterogeneous Catalyst for the Synthesis of Arylaminotetrazoles

ZnO is an effective heterogeneous catalyst for the reaction between arylcyanamides with sodium azide to synthesize the arylaminotetrazoles in good yields. This method has advantages of good yields, simple methodology, short reaction times, and easy workup. Furthermore, the catalyst can subsequently be reused for several times without any significant loss of activity.     

Study of Complex Formation between 5,7‐Diiodo‐8‐hydroxyquinoline and Zn2+, Cd2+, Pb2+ and Tl+ Cations in Binary Non‐Aqueous Solvents Using Square Wave Polarography Technique (SWP)

The complexation reaction between Zn²⁺, Pb²⁺, Cd²⁺ and Tl⁺ cations by 5,7‐diiodo‐8‐hydroxyquinoline (IQN) was studied in the Dimethylformamide /Acetonitril (DMF‐AN) binary system using square wave polarography technique. The stoichiometry and stability of the complexes were determined by monitoring the shifts in half‐wave or peak potential of the polarographic waves of metal ions against the ligand concentration. The stoichiometry of the complexes was found to be 1:1. The results obtained show that there is an inverse relationship between the formation constant of the complexes and the donor number of solvent base on the Guttmann donocity scale. In all cases the formation constants increased with increasing amounts of AN in these binary systems. The selectivity order for IQN complexes with the cations is Zn²⁺ > Pb²⁺ > Cd²⁺ > Tl⁺.     

ctDNA interaction of Co-containing Keggin polyoxomolybdate and in vitro antitumor activity of free and its nano-encapsulated derivatives

Polyoxometalates (POMs) are negatively charged clusters consisting of transition metals and oxygen atoms. The antiviral and antitumor activities are the dominant activities of POMs in pharmacology and medicine. Based on Co-containing Keggin polyoxomolybdate (K₆[SiMo₁₁O₃₉Co(H₂O)].nH₂O), nanosized starch, and lipid-encapsulated derivatives (abbreviated as SiMo₁₁Co, SEP and LEP, respectively) were synthesized and characterized by FT-IR spectroscopy, ICP, TG analysis, SEM and TEM images. The results show that the SiMo₁₁Co retains its parent structure after encapsulation by starch and lipid nanoparticles. The biological activity of SiMo₁₁Co has been evaluated by investigating its binding ability to calf thymus DNA (ctDNA), using UV–Vis absorption spectroscopy, fluorescence quenching and fluorescence Scatchard plots. The obtained results of absorption titration rule out the intercalating binding mode and propose the groove or outside stacking binding for SiMo₁₁Co. These results were authenticated by fluorescence quenching experiments and scatchard plots. Absorption spectral traces reveal 10.21 % hyperchromism for SiMo₁₁Co. The value of 7.6 × 10³ M^?1 was obtained for binding constant (K_b) of SiMo₁₁Co to ctDNA. Furthermore, the in vitro antitumor activity of SiMo₁₁Co and nano-encapsulated forms was investigated using the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide (MTT) assay that was carried out on two types of human cancer cells, MCF-7 (breast cancer cells) and HEK-293 (Human Embryonic Kidney). The results represent the enhancement of cell penetration and antitumor activity of SiMo₁₁Co due to its encapsulation in starch or lipid nanoparticles. However, this observed enhancement for the lipid relative to the starch nanocapsule can be attributed to its smaller size.     

On fractional stochastic inequalities related to Hermite–Hadamard and Jensen types for convex stochastic processes

Stochastic convexity and its applications are very important in mathematics and probability (Aequationes Mathematicae 20:184–197, 1980). There are two well-known inequalities for convex stochastic processes: Jensen’s inequality and Hermite–Hadamard’s inequality. Recently, Hafiz (Stoch Anal Appl 22:507–523, 2004) has provided fractional calculus for some stochastic processes. The problem is how to formulate these inequalities for stochastic processes in the class of fractional calculus and that is what is done in this paper. Our results generalize the corresponding ones in the literature.     

Purification assay to prepared ultrapure carboxymethyl-chitosan

Carboxymethyl Chitosan (CMCh) is a semi-synthetic derivative of chitosan (a natural biopolymer) with increasing biomedical applications as a matrix or scaffold material for tissue engineering applications. Since, the presence of impurities can cause immunological reactions in vivo where ultimately pure materials are needed. To this end, purity of commercial-grade CMCh samples was investigated here along with their purification by a solvent/nonsolvent technique. The resulting polymer was characterized by differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR) and energy dispersive X-ray spectroscopy (EDX) to confirm the validity of the purification process.     

A note on rings with McCoy-like properties

According to Nielsen [10 Nielsen, P. P. (2006). Semi-commutativity and the McCoy condition. J. Algebra 298:134–141.[Crossref], [Web of Science ®] , [Google Scholar]], a ring R is called right McCoy if for every nonzero f(x),g(x) in the polynomial ring R[x], f(x)g(x) = 0 implies that there exists a nonzero s in R such that f(x)s = 0. In this work, we state two notes on rings with McCoy-like conditions.     

The effect of TiN nanoparticles deposition with different number of shots on SS316L by plasma focus device

In this paper, we present the result of TiN nanocrystalline deposition on SS316L, using a 4 kJ plasma focus (PF) device for 10, 20, and 30 focus shots. The effect of different number of focus shots on micro-structural changes of thin film is characterized by field emission scanning electron microscope. Existence of grains in different size confirms the formation of TiN nanocrystals on the surface of SS316L substrate. X-ray diffraction (XRD) reveals the formation of a nanocrystalline titanium nitride coating on the surface of SS316L samples. The crystalline size of TiN obtained from XRD data is strongly dependent on the number of focus shots. Thickness of the elements found on the surface of the treated sample that obtain by Rutherford backscattering spectroscopy (RBS) analysis is in the range of 150×10¹⁵?200×10¹⁵ atoms/cm². All the existence elements in the coated samples are identified by Particle Induced X-ray Emission (PIXE) spectra. Investigation on the corrosion resistance of TiN coatings was performed using an electrochemical potentiodynamic polarization. Our results suggest that TiN nanocrystalline implantation with proper ion fluences using PF can significantly improve the corrosion resistance of SS316L.     

Substituent effects on SN2 reaction between substituted benzyl chloride and chloride ion in gas phase

Nucleophilic substitution reaction between some substituted benzyl chlorides and chloride ion has been investigated by ab initio and DFT methods. New calculated energy data are in better agreement with experimental data. The electron‐withdrawing groups increase the energy barriers and the electron‐donating groups decrease them. The changes of geometrical parameters and energy data are in good agreement with the results of atoms in molecules and natural bond orbital analyses. The relationship between Hammett coefficients and energy data (and geometry parameters) has been established and the ρ constant has been calculated for this reaction. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011     

Novel sulfur-doped niobium pentoxide nanoparticles: fabrication, characterization, visible light sensitization and redox charge transfer study

Novel sulfur-modified niobium(V) oxide nanoparticles (SNON) that firstly exhibited good visible light sensitization were fabricated by a modified sol–gel technique using a very stable sol containing niobium(V) chloride, oxalic acid, isopropanol as chelating agent and thiourea as sulfur source. The resulting S-doped Nb₂O₅ nanomaterials were characterized by cyclic voltammetry (CV), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDAX), scanning electron microscope (SEM), ultra-violet diffuse reflectance (UV-DRS) and thermogravimetry thermal Analysis (TG-DTA). As against the response of unmodified niobium(V) oxide nanoparticles (UNON), the doped samples show different electrochemical response indicating an induced charge transfer across the niobium pentoxide/solution interface, thus forming two anodic peaks and a cathodic peak. This important observation was confirmed by UV-DRS in terms of band bending due to sulfur doping. Upon sulfur-modification, the absorption edge extends into the visible light region. The SEM observation shows that the SNPN existed in the mode of polycrystalline structure and the average grain size 63 nm. The EDAX analysis of undoped Nb₂O₅ and sulfur doped Nb₂O₅ shows the Nb₂O₅ (98%) and S (2%) content of nanopowder. These SNON nanoparticles are expected to be suitable candidates as visible light niobium(V) oxide nanoparticles sensitization.     

Synthesis and complexation study of calix[4]arene diamine derivative incorporated in a polymeric backbone with chiral monomers

The novel chiral polymeric compounds containing more than one calix[4]arene have been synthesized by reacting a new calix[4]arene diamine derivative with two chiral monomers. These newly prepared compounds were studied by extraction of toxic heavy metal (Cu²⁺, Co²⁺, Cd²⁺, Hg²⁺), silver and alkali metal (Na⁺, K⁺) cations from aqueous phase. It was observed that the resulting calixarene-based polymers have a good complexing ability towards silver, alkali metal and toxic heavy metal cations.