Chemical composition,antimicrobial and antioxidant activities of the essential oil of Psammogetoncanescens

This study reports the chemical composition, antimicrobial activity and antioxidant properties of Psammogeton canescens essential oil (EO) and its main compounds. The EO was obtained from the aerial parts of P. canescens by hydrodistillation and analysed by using GC/MS. The main constituent was β-bisabolene (25%), followed by α-pinene (20%), apiole (15.34%), γ-terpinene (7.34%), p-cymene (5.35%), β-pinene (5.41%), camphene (5.12%), dill apiole (5%), myrcene (4.54%), colchicine (0.56), sylvestrene (0.56%), β-caryophyllene (0.45%), caryophyllene oxide (0.43%), (Z)-β-farnesene (0.32%), cembrene (0.21%), folic acid (0.21%), germacrene D (0.14) and β-sesquiphellandrene (0.13). β-Bisabolene exhibited strong antioxidant activity (14 ± 0.8 μg/mL). The EO of P. canescens was particularly active against Candida albicans and Escherichia coli, with the lowest minimum inhibitory concentration and minimum bactericidal/fungicidal concentration values. In conclusion, these results support the use of the EO and its main compounds for their antioxidant properties and antimicrobial activity.     

Physical processes in high-temperature superconductors at the interface between the vortex-filled and meissner regions

A technique has been proposed for investigating the magnetic microstate of high-temperature superconductors with a simultaneous analysis of the crystalline microstate of the sample with the aim of elucidating the specific features of the interaction between the crystalline and magnetic microstructures of polycrystalline high-temperature superconductors. Qualitatively new results have been obtained for samples with different microstructures. In particular, it has been found that the magnetic field dependences of the trapped magnetic flux density B _tr(H ₀) of polycrystalline and epitaxial films of high-temperature superconductors exhibit regular steps for both increasing and decreasing magnetic fields. The obtained results have demonstrated that, in strong magnetic fields, the studied epitaxial films, as well as bulk and thin-film polycrystalline high-temperature superconductors, “break down” into single domains, crystallites, and subcrystallites with different demagnetization factors. It has been revealed that the dependences B _tr(H ₀) also exhibit steps due to the simultaneous penetration of vortices into crystallites of approximately the same sizes and into more regularly arranged subcrystallites. As the quality of the samples increases, these steps become more pronounced because of the increase in the short-range order. The absence of steps in the dependence B _tr(H ₀) of the polycrystalline bulk samples clearly demonstrates the absence of long-range order in these samples. It is the vitreousness of the crystallographic microstructure of high-temperature superconductors which is responsible for the observed transformations in the vortex system. The similarity of the results obtained for samples with different microstructures indicates that the penetration (escape), distribution, and trapping of the magnetic flux in these samples occur through a universal mechanism. It has been found that the polycrystalline high-temperature superconductors are actually multi-step rather than two-step systems. It has been shown that the vitreousness of the microstructure of high-temperature superconductors and the presence of close-packed twin boundaries in samples lead to the penetration of a magnetic flux in the form of hypervortices into the sample and cause the formation of a superconducting glass state on a different physical basis as compared to the Ebner-Stroud model of a granulated glass.     

Pseudo-amenability of certain semigroup algebras

In this paper, we investigate the pseudo-amenability of semigroup algebra ? ¹(S), where S is an inverse semigroup with uniformly locally finite idempotent set. In particular, we show that for a Brandt semigroup \(S={\mathcal{M}}^{0}(G,I)\), the pseudo-amenability of ? ¹(S) is equivalent to the amenability of G.     

The hydrogen‐bonded dimers of N,N′,N′′‐tricyclohexylphosphoric triamide in new tin(IV) and copper(II) complexes

In the new tin(IV) and copper(II) complexes, cis‐dichlorido‐trans‐dimethyl‐cis‐bis(N,N′,N′′‐tricyclohexylphosphoric triamide‐κO)tin(IV), [Sn(CH₃)₂Cl₂(C₁₈H₃₆N₃OP)₂], (I), and trans‐diaquabis(N,N′,N′′‐tricyclohexylphosphoric triamide‐κO)copper(II) dinitrate–N,N′,N′′‐tricyclohexylphosphoric triamide (1/2), [Cu(C₁₈H₃₆N₃OP)₂(H₂O)₂](NO₃)₂·2C₁₈H₃₆N₃OP, (II), the N,N′,N′′‐tricyclohexylphosphoric triamide (PTA) ligands exist as hydrogen‐bonded dimers via P=O...H—N interactions around the metal center. The asymmetric unit in (I) consists of one complete complex molecule located on a general position. The Sn^IV coordination geometry is octahedral with two cis hydrogen‐bonded PTA ligands, two cis chloride ligands and two trans methyl groups. The asymmetric unit in (II) contains one half of a [Cu(PTA)₂(H₂O)₂]²⁺ dication on a special position (site symmetry for the Cu atom), one nitrate anion and one free PTA molecule, both on general positions. The complex adopts a square‐planar trans‐[CuO₂O₂] coordination geometry, with the Cu^II ion coordinated by two PTA ligands and two water molecules. Each of the noncoordinated PTA molecules is hydrogen bonded to a neighboring coordinated PTA molecule and an adjacent water molecule; the phosphoryl O atom acts as a double‐H‐atom acceptor. The P atoms in the PTA ligands of both complexes and in the noncoordinated hydrogen‐bonded molecules in (II) adopt a slightly distorted tetrahedral environment.     

Numerical modeling on inlet aperture effects on flow pattern in primary settling tanks

Inlets should be designed to dissipate the kinetic energy or velocity head of the mixed liquor and to prevent short-circuiting, mitigate the effects of density currents, and minimize blanket disturbances. Flow in primary settling tank is simulated by means of computational fluid dynamics. The fluid is assumed incompressible and non-buoyant. A two-dimensional computational and one phase fluid dynamics model was built to simulate the flow properties in the settling tank including the velocity profiles, the flow separation area and kinetic energy. In this study, the RNG turbulent model was solved with the Navier–Stokes equations. In order to evaluate hydraulic influences on the velocity profile, separation length and kinetic energy, three different of opening positions and two and three aperture in inlets were simulated. The flow model uses to apply a fixed-grid of cells that are all rectangular faces; the fluid moves through the grid and free surfaces are tracked with the volume-of-fluid (VOF) technique. Effects of numbers and locations of inlet apertures on the flow field are presented and the results show the positions of inlet apertures are affected on the flow pattern in the settling basin and increasing the numbers of slots can reduce kinetic energy in the inlet zone and produce uniform flow.     

Novel and chemoselective one-pot synthesis of 4-arylidene-2-phenyl-5(4H)-oxazolones starting from benzyl alcohols promoted by [(C14H24N4)2W10O32]-[bmim]NO3

Abstract  

A new and practical promoter system for one-pot, efficient, chemoselective synthesis of 4-arylidene-2-phenyl-5(4H)-oxazolones using [(C₁₄H₂₄N₄)₂W₁₀O₃₂]-[bmim]NO₃ under solvent-free conditions is described. The present work opens up a new and ecofriendly synthetic route to Erlenmeyer–Pl?chl adducts from primary benzyl alcohols in a one-pot operation.     

Solvent‐free synthesis of 2H‐pyrans: One‐pot reactions of dithiocarbamates,alkyl propiolates,and isocyanides

A novel, convenient, and an efficient approach to the synthesis of 2H‐pyrans has been reported based on the multicomponent reaction. Solvent‐free condition for the reaction of dithiocarbamates, alkyl propiolates and isocyanides lead to the formation of 2H‐pyrans in good yields. In these reactions, synthesis of 2H‐pyrans is possible based on the one‐pot reaction and without using any catalyst. The mild reaction conditions and high yields of the products exhibit the good synthetic advantage of these methods. J. Heterocyclic Chem., lpar;2011).     

Reaction kinetics of a novel thermoset nanocomposite: the glycerol diglycidyl ether/3,3-dimethylglutaric anhydride/nano-Al2O3 system

Abstract  

The curing behavior of the glycerol diglycidyl ether/3,3-dimethylglutaric anhydride/nano-alumina system was examined using a dynamic differential scanning calorimetry technique. The activation energy of the system was calculated using the Kissinger, Ozawa, Barrett, and two-parameter Sestak–Berggren models. Under the assumption of a constant activation energy and an autocatalytic mechanism, the activation energy, frequency factor, and total order of reaction were computed. The theoretical reaction rate was also calculated and compared to the experimental results. Good agreement was seen between the experimental and calculated data confirming the autocatalytic mechanism. The effect of triethylamine concentration on the reaction rate was clarified using the Barrett method. Fourier transform infrared spectroscopy (FT-IR) spectroscopy was used to verify the formation of internal ester groups. Scanning electron microscopy (SEM) and X-ray mapping analyses revealed that the nanofiller was homogeneously distributed in the continuous phase.     

Molecular structure and theoretical studies of new stable phosphorus ylides derived from trialkyl phosphites

The reaction between dialkyl acetylenedicarboxylates and NH heterocyclic compounds in the presence of trialkyl phosphite leads to stable phosphorus ylide derivatives in good yields. The x‐ray crystallographic data and theoretical study show that there is a resonance between two bonds of C₉P₁ and C₉₁O₉₁ in phosphorous ylide 4c . This compound crystallizes in the triclinic system, space group ( ), with the following unit cell parameters: a = 8.7522(3)Å, b = 8.8513(5)Å, c = 18.3469(5)Å, α = 99.1220(10)°, β = 90.954(2)°, γ = 118.792(2)°, Z = 2, and V = 1222.72(9)ų. © 2010 Wiley Periodicals, Inc. Heteroatom Chem 22:36–43, 2011; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.20653