Non-vacuum Bianchi types <Emphasis Type="Italic">I</Emphasis> and <Emphasis Type="Italic">V</Emphasis> in <Emphasis Type="Italic">f</Emphasis> (<Emphasis Type="Italic">R</Emphasis>) gravity

In a recent paper (Sharif and Shamir in Class. Quantum Grav. 26:235020, 2009), we have studied the vacuum solutions of Bianchi types I and V spacetimes in the framework of metric f (R) gravity. Here we extend this work to perfect fluid solutions. For this purpose, we take stiff matter to find energy density and pressure of the universe. In particular, we find two exact solutions in each case which correspond to two models of the universe. The first solution gives a singular model while the second solution provides a non-singular model. The physical behavior of these models has been discussed using some physical quantities. Also, the function of the Ricci scalar is evaluated.     

Hollow fiber liquid-phase microextraction for the determination of trace amounts of rosiglitazone (anti-diabetic drug) in biological fluids using capillary electrophoresis and high performance liquid chromatographic methods

A three-phase hollow fiber liquid-phase microextraction (HF-LPME) coupled either with capillary electrophoresis (CE) or high performance liquid chromatography (HPLC) with UV detection methods was successfully developed for the determination of trace levels of the anti-diabetic drug, rosiglitazone (ROSI) in biological fluids. The analyte was extracted into dihexyl ether that was immobilized in the wall pores of a porous hollow fiber from 10 mL of aqueous sample, pH 9.5 (donor phase), and was back extracted into the acceptor phase that contained 0.1 M HCl located in the lumen of the hollow fiber. Parameters affecting the extraction process such as type of extraction solvent, HCl concentration, donor phase pH, extraction time, stirring speed, and salt addition were studied and optimized. Under the optimized conditions (extraction solvent, dihexyl ether; donor phase pH, 9.5; acceptor phase, 0.1 M HCl; stirring speed, 600 rpm; extraction time, 30 min; without addition of salt), enrichment factor of 280 was obtained. Good linearity and correlation coefficients of the analyte was obtained over the concentration ranges of 1.0–500 and 5.0–500 ng mL⁻¹ for the HPLC (r² = 0.9988) and CE (r² = 0.9967) methods, respectively. The limits of detection (LOD) and limits of quantitation (LOQ) for the HPLC and CE methods were (0.18, 2.83) and (0.56, 5.00) ng mL⁻¹, respectively. The percent relative standard deviation (n = 6) for the extraction and determination of three concentration levels (10, 250, 500 ng mL⁻¹) of ROSI using the HPLC and CE methods were less than 10.9% and 13.2%, respectively. The developed methods are simple, rapid, sensitive and are suitable for the determination of trace amounts of ROSI in biological fluids.     

Determination of aluminum levels in serum and red blood cells from long-term haemodialysis patients using instrumental neutron activation analysis

Aluminum levels of serum and red blood cell (RBC) were determined by instrumental neutron activation analysis (INAA) in 15 patients undergoing long-term haemodialysis. In the sample, aluminum was bombarded with thermal neutrons due to ²⁷Al(n,γ)²⁸Al and was determined by measuring 1779 keV gamma-ray of ²⁸Al (T _1/2 = 2.24 min) with a HPGe detector. Phosphorus, causing an important interference by the fast neutron reaction, ³¹P(n,α)²⁸Al, was determined by the photometric method to correct the net-area under the ²⁸Al gamma-peak. The one-sample Kolmogorov-Smirnov test was used to control the normality distribution of the aluminum levels in serum and RBC. The results obtained were found to be in agreement with the serum aluminum determination performed by electrothermal atomic absorption spectrophotometry. The statistical results show a correlation between the aluminum levels of serum and RBC. This revised version was published online in July 2006 with corrections to the Cover Date.     

Nickel(II) and copper(II) complexes of 2-acetylpyridine 4 N-(2-methylpyridinyl)-, 4 N-(2-ethylpyridinyl)- and 4 N-methyl(2-ethylpyridinyl) thiosemicarbazones

Summary Ni^II and Cu^II complexes of 2-acetylpyridine ⁴ N-(2-methylpyridinyl)-, ⁴ N-(2-ethylpyridinyl)- and ⁴ N-methyl(2-ethylpyridinyl) thiosemicarbazones (HL4pam, HL4pae, and HL4Mpae, respectively) of general formula [M(HL)X₂] have been isolated from boiling EtOH and characterized by physico-chemical and spectroscopic methods. The growth inhibition activities of the thiosemicarbazones and their complexes were measured against Aspergillus nicer and Paecilomyces variotii.     

Derivatives of 4‐(2‐hydro­xy­lphenyl)‐2‐phenyl‐2,3‐di­hydro‐1,5‐benzothiazepine

In the structures of 2‐(4‐chloro­phenyl)‐4‐(2‐hydroxyphenyl)‐2,3‐di­hydro‐1,5‐benzo­thia­zepine, C₂₁H₁₆ClNOS, 4‐(2‐hy­droxy­phenyl)‐2‐(4‐tolyl)‐2,3‐di­hydro‐1,5‐ben­zo­thia­zepine, C₂₂H₁₉NOS, and 4‐(2‐hydroxyphenyl)‐2‐(3‐methoxy­phenyl)‐2,3‐di­hydro‐1,5‐benzo­thia­zepine, C₂₂H₁₉NO₂S, the central seven‐membered heterocyclic rings adopt twist‐boat conformations in which the N atoms are involved in strong intramolecular hydrogen bonds with the hydroxyl H atoms, resulting in six‐membered rings.     

Magnetic and microstructural characterizations of CoFe and CoFeB nanowires

Magnetic and microstructural characterizations of cobalt-rich CoFe and CoFeB nanowires fabricated in commercially available alumite templates were investigated. The modifications in magnetic and microstructural behaviors of crystalline CoFe and amorphous CoFeB nanowires were observed after magnetic field annealing and reannealing of the samples.     

Effects of Schwarzschild black hole horizon on isothermal plasma wave dispersion

The 3 + 1 GRMHD equations for Schwarzschild spacetime in Rindler coordinates with isothermal state of plasma are formulated. We consider the cases of non-rotating and rotating backgrounds with non-magnetized and magnetized plasmas. For these cases, the perturbed form of these equations are linearized and Fourier analyzed by introducing plane wave type solutions. The determinant of these equations in each case leads to two dispersion relations which give value of the wave number k. Using the wave number, we obtain information like phase and group velocities etc. which help to discuss the nature of the waves and their characteristics. These provide interesting information about the black hole magnetosphere near the horizon. There are cases of normal and anomalous dispersion. We find a case of normal dispersion of waves when the plasma admits the properties of Veselago medium. Our results agree with those of Mackay et al. according to which rotation of a black hole is required for negative phase velocity propagation.     

Biyouyanagin A, an anti-HIV agent from Hypericum chinense L. var. salicifolium

[structure: see text] A structurally unique hydrophobic compound, biyouyanagin A, was isolated from the MeOH extract of the leaves of Hypericum chinense L. var. salicifolium. The structure of biyouyanagin A was elucidated on the basis of spectroscopic evidence. Biyouyanagin A showed a significant activity against HIV and inhibited cytokine production.