Chemical composition of the essential oil of aerial parts of Haussknechtia elymaitica Boiss. from Iran: a good natural source for trans-asaron

The chemical composition of the essential oil of Haussknechtia elymaitica Boiss. was investigated by capillary GC and GC/MS for the first time. Twelve components were identified which accounting for 99.7% of the oil composition. The major compounds were trans-asarone (59.9%), trans-methyl isoeugenol (22.4%), α-zingiberene (7.96%), β-sesquiphellandrene (4.7%) and β-bisabolene (4.3%). The first three compounds considered as the main components of the essential oil were isolated and characterised by spectroscopic techniques.     

A new flavonoid and other constituents from Centaurea nicaeensis All. var. walliana M

A new flavone glucoside, apigenin 4'-(6″-methylglucuronide) (1), together with six known compounds, cirsilineol, jaceosidin, melitensin, apigenin, apigenin 7-(6″-methylglucuronide) and prunasin, were isolated from the ethanolic extract of the aerial parts of Centaurea nicaeensis All. var. walliana M. (Asteraceae) collected from Souk-Ahras, eastern Algeria. The structures were established by spectral analysis, mainly HRESI-MS, UV and 2D-NMR experiments (COSY, HSQC and HMBC).     

Organic-Assisted Nano-Sized Antimony Telluride Prepared by Co-Precipitation Reductive Route

Nano-sized antimony telluride is of much interest for improving the thermoelectric figure of merit. In the present work, organic-assisted antimony telluride nanorods were successfully fabricated by a simple hydrothermal method. The products were characterized by means of X-ray diffraction, scanning electron microscope, and transmission electron microscope. The results show that the typical antimony telluride synthesized by co-precipitation reductive route is rodlike in shape with about 35 nm in thickness and 300 nm in edge length.     

Interaction of cations with 2′‐deoxythymidine nucleoside and analysis of the nature and strength of cation bonds

Binding of Mg²⁺, Ca²⁺, Zn²⁺, and Cu⁺ metal ions with 2′‐deoxythymidine (dT) nucleoside was studied using a density functional theory method and a 6‐311++G(d,p) basis set. This work demonstrated that the interaction of dT with these cations is tri‐coordinated η (O2, O4′, O5′). Among the four types of cations, Zn²⁺ cation exhibited the most tendency to interact with the dT. Cations via their interaction with dT can affect the N‐glycosidic bond length, the values of pseudorotation of the sugar ring, the orientation of the base unit with respect to the sugar ring, and the acidity of the O5′H, O3′H, and N3H groups in the dT nucleoside. Natural bond orbital analysis was performed to calculate the charge transfer and natural population analysis of the complexes. Quantum theory of atoms in molecules was also applied to determine the nature of interactions. It was shown that in dT–Mg²⁺ and dT–Ca²⁺ complexes, the bonds are electrostatic (closed‐shell) interactions, although they are partially covalent and partially electrostatic interactions in dT–Zn²⁺ and dT–Cu⁺ complexes. Copyright © 2011 John Wiley & Sons, Ltd.     

Analytical analysis of buckling and post-buckling of fluid conveying multi-walled carbon nanotubes

In this work, buckling and post-buckling analysis of fluid conveying multi-walled carbon nanotubes are investigated analytically. The nonlinear governing equations of motion and boundary conditions are derived based on Eringen nonlocal elasticity theory. The nanotube is modeled based on Euler–Bernoulli and Timoshenko beam theories. The Von Karman strain–displacement equation is used to model the structural nonlinearities. Furthermore, the Van der Waals interaction between adjacent layers is taken into account. An analytical approach is employed to determine the critical (buckling) fluid flow velocities and post-buckling deflection. The effects of the small-scale parameter, Van der Waals force, ends support, shear deformation and aspect ratio are carefully examined on the critical fluid velocities and post-buckling behavior.     

Movement of Intransitive Permutation Groups Having Maximum Degree

Let G be a permutation group on a set Ω with no fixed points in,and m be a positive integer.Then the movement of G is defined as move(G):=sup Γ {|Γg\Γ| | g ∈ G}.It was shown by Praeger that if move(G) = m,then |Ω| 3m + t-1,where t is the number of G-orbits on.In this paper,all intransitive permutation groups with degree 3m+t-1 which have maximum bound are classified.Indeed,a positive answer to her question that whether the upper bound |Ω| = 3m + t-1 for |Ω| is sharp for every t > 1 is given.     

A GENERALIZED SEMICONJUGACY IN DIFFERENCE EQUATIONS＊

Difference equations arise in many fields.This article is concerned to generalization of semiconjugacy in difference equations.In fact,H.Sedaghat in [7] investigated the semiconjugacy in difference equ...     

Simple routes to synthesis and characterization of nanosized tin telluride compounds

Nanosized tin telluride compounds were prepared by chemical reduction process and hydrothermal methods. The nanosized SnTe compounds were characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The SnTe nanoalloy prepared by chemical reduction process presented quasi-spherical morphology with aggregation. The sizes of particle were 40-50 nm. The powder prepared by hydrothermal process was nearly nanospheres, and the particle sizes were 30-40 nm with narrow distribution. The effect of capping agent, reductant sort, and reaction temperature on the morphology, the particle sizes and the phase of SnTe alloys have been investigated. Experimental results indicated that N₂H₄·H₂O plays a crucial role in the formation of nanosized rode-like SnTe compounds.     

Synthesis of New 1,3‐bis(Heteroaryl)‐4,5‐imidazolidinediones Through Reaction of N,N′‐bis(Heteroaryl)methanediamines with Oxalyl Chloride

Reaction of N,N′‐bis(2‐pyridinyl, 3‐pyridinyl, 4‐pyridinyl, 2‐thiazolyl, 4‐nitrophenyl, and 2‐benzothiazolyl)methanediamines 1a–f with oxalyl chloride in dry dichloroethane in the presence of pyridine affords the corresponding 1,3‐bis (heteroaryl)‐4,5‐imidazolidinediones 3a–f in good to excellent yields. The essential role of pyridine in the reaction mixture is described, and reaction details as well as product characterization is discussed.