Large-Eddy Simulation of Dispersion from Line Sources in a Turbulent Channel Flow

Large-eddy simulations of the dispersion from scalar line sources at various locations within a fully developed turbulent channel flow at Re = uh/ν = 10,400 are presented. Both mean and fluctuating scalar quantities are compared with those from the single available set of experimental data (Lavertu and Mydlarski, J Fluid Mech 528:135–172, 2005) and differences are highlighted and discussed. The results are also discussed in the context of scalar dispersion in other kinds of turbulent flows, e.g. homogeneous shear-flow. Initial computations at a much lower Reynolds number are also reported and compared with the two available direct numerical simulation data sets.     

Sr doping effects on the transport and magnetic properties of GdBaCo2O5+δ

Studies on some new members of the cobalt perovskite Gd_1−xSr_xBaCo₂O_5+δ with low strontium concentrations (0<x<0.1) have been carried out with the aim of investigating possible metallization of the GdBaCo₂O_5+δ system by hole doping. Low temperature electrical resistivity, magnetic susceptibility and thermopower of the above system have been studied. The pristine compound with x=0 and δ∼0.5 exhibits a semiconductor-like behavior and two magnetic transitions below room temperature. Upon Sr²⁺ substitution, there is a fall in resistivity by 2-3 orders of magnitude at low temperature and also a dramatic reduction in the ferromagnetic to antiferromagnetic transition temperature. These changes can be explained on the basis of hole doping (and increase in the Co⁴⁺content). Evidence for an increase in Co⁴⁺ with Sr²⁺ substitution is provided by iodometric analysis.     

A Multitarget Approach to Evaluate the Efficacy of Aquilaria sinensis Flower Extract against Metabolic Syndrome

Aquilaria sinensis (Lour.) Spreng is known for its resinous secretion (agarwood), often secreted in defense against injuries. We investigated the effects of A. sinensis flower extract (AF) on peroxisome proliferator-activated receptors alpha and gamma (PPARα and PPARγ), liver X receptor (LXR), glucose uptake, and lipid accumulation (adipogenesis). Activation of PPARα, PPARγ and LXR was determined in hepatic (HepG2) cells by reporter gene assays. Glucose uptake was determined in differentiated muscle (C2C12) cells using 2-NBDG (2-deoxy-2-[(7-nitro-2,1,3-benzoxadiazol-4-yl)amino]-D-glucose). Adipogenesis was determined in adipocytes (3T3-L1 cells) by Oil red O staining. At a concentration of 50 µg/mL, AF caused 12.2-fold activation of PPARα and 5.7-fold activation of PPARγ, while the activation of LXR was only 1.7-fold. AF inhibited (28%) the adipogenic effect induced by rosiglitazone in adipocytes and increased glucose uptake (32.8%) in muscle cells at 50 μg/mL. It was concluded that AF acted as a PPARα/γ dual agonist without the undesired effect of adipogenesis and exhibited the property of enhancing glucose uptake. This is the first report to reveal the PPARα/γ dual agonistic action and glucose uptake enhancing property of AF along with its antiadipogenic effect, indicating its potential in ameliorating the symptoms of metabolic syndrome.     

Positron annihilation measurements across the superconducting transition in Y1Ba2Cu3O7−x

Positron lifetime and Doppler broadened annihilation radiation lineshape measurements have been carried out in Y₁Ba₂Cu₃O_7−x as a function of temperature in the range of 300 K to 58 K. The positron lifetime and the peak parameter of the annihilation radiation lineshape are observed to decrease on lowering the temperature without showing any discontinuous change across the superconducting transition temperature of 90 K as determined by susceptibility measurements. The variation of positron annihilation parameters with temperature in the superconducting state is significantly larger than that in the normal state. This is qualitatively explained in terms of the dimerization of oxygen ions in the superconducting state of Y₁Ba₂Cu₃O_7−x .     

Are nuclei withN∼43 deformed?

The level schemes of⁷⁵Se and⁷⁹Kr have been established through gamma ray and conversion electron spectroscopy following⁷⁵As (p, nγ ^?e) and⁷⁹Br (p, nγe^?) reactions. The data on these nuclei and the nuclei in the neighbourhood of this mass region are discussed and evidence is presented to show that the nuclei withN～43 are deformed.     

Nickel(II) complexes with tetra- and pentadentate aminopyridine ligands: synthesis, structure, electrochemistry, and reduction to nickel(I) species

A series of nickel(II) complexes with polydentate aminopyridine ligands N,N,N'-tris-[2-(2'-pyridyl)ethyl]ethane-1,2-diamine (L1), N,N,N'-tris-[2-(2'-pyridyl)ethyl]-N'-methylethane-1,2-diamine (L2), and N,N'-bis-[2-(2'-pyridyl)ethyl]-N,N'-dimethylethane-1,2-diamine (L3) were synthesized and characterized by elemental analysis and spectroscopic methods. Single-crystal X-ray diffraction studies showed that the Ni(II) ions have five-coordinate square-pyramidal geometry in [NiL2](ClO(4))(2), similar to that previously found in [NiL1](ClO(4))(2) x CH(3)NO(2) (Hoskins, B. F.; Whillans, F. D.J. Chem. Soc., Dalton Trans. 1975, 657), and square-planar geometry in [NiL3](ClO(4))(2). All three nickel(II) complexes are reduced by sodium borohydride or sodium amalgam in organic solvents to nickel(I) species, which were identified by highly anisotropic EPR spectra at 100 K: g(1) = 2.239, g(2) = 2.199, and g(3) = 2.025 for [NiL1](+); g(axially) = 2.324 and g(radially) = 2.079 for [NiL2](+) and [NiL3](+). Cyclic voltammetry of the nickel(II) complexes in acetonitrile exhibited reversible reduction waves at -1.01 V for [NiL1](2+), -0.91 V for [NiL2](2+), and -0.83 V for [NiL3](2+) versus SCE, potentials which are significantly less negative than those of most previously characterized Ni(II) complexes with nitrogen-only donor atoms. Complexes [NiL1](2+) and [NiL2](2+) showed high catalytic activity in the electroreduction of 1,2-trans-dibromocyclohexane to cyclohexene.     

Novel synthesis of cyclobutanone derivatives via dimetalation of iminium ions with the TiCl4-trialkylamine reagent system

Iminium salts are generated in situ, react with TiCl4-trialkylamines, and diaryl ketones to produce 3,3-diaryl-cyclobutanones in moderate to good yields.     

Development and validation of a sensitive LC-MS/MS method with electrospray ionization for quantitation of zafirlukast, a selective leukotriene antagonist in human plasma: application to a clinical pharmacokinetic study

A highly sensitive and specific LC-MS/MS method has been developed and validated for the estimation of zafirlukast (ZFK) with 500 microL human plasma using valdecoxib as an internal standard (IS). The API-4,000 LC-MS/MS was operated under multiple reaction-monitoring mode using the electrospray ionization technique. The assay procedure involved extraction of ZFK and IS from human plasma with ethyl acetate. The resolution of peaks was achieved with 10 mm ammonium acetate (pH 6.4):acetonitrile (20:80, v/v) on a Hypersil BDS C(18) column. The total chromatographic run time was 2.0 min and the elution of ZFK and IS occurred at approximately 1.11 and 1.58 min, respectively. The MS/MS ion transitions monitored were 574.2 --> 462.1 for ZFK and 313.3 --> 118.1 for IS. The method was proved to be accurate and precise at a linearity range of 0.15-600 ng/mL with a correlation coefficient (r) of >or=0.999. The method was rugged with 0.15 ng/mL as lower limit of quantitation. The intra- and inter-day precision and accuracy values were found to be within the assay variability limits as per the FDA guidelines. The developed assay method was applied to a pharmacokinetic study in human volunteers following oral administration of 20 mg ZFK tablet.