Radioimmunoassay of Human Follicle Stimulating Hormone /HFSH/

A method for determining Human FSH in blood/serum by RIA is described. The radioiodination of FSH with¹²⁵I is carried out under carefully controlled conditions such as, amount of initial activity of¹²⁵I take for iodination, the reaction volume, and the reaction time, etc. The tracer FSH obtained thus is with minimum damage and optimum specific activity which is ideally suited for RIA. The shelf-life of the tracer is enhanced by the addition of benzyl alchol. The tracer can be conveniently stored at+4–6°C upto 10 weeks, avoiding the repeated freezing and thawing process. Antiserum to FSH is raised in rabbits by repeated injections via intramuscular route. The method utilizes polyethylene glycol /PEG/ as the separation system. Using this method, a number of control samples of men and women of reproductive age group are screened. This sensitive assay has a good validity and has an inter-assay variation less than 15%.     

The structure of some classes of <Emphasis Type="Italic">K</Emphasis>-contact manifolds

We study projective curvature tensor in K-contact and Sasakian manifolds. We prove that (1) if a K-contact manifold is quasi projectively flat then it is Einstein and (2) a K-contact manifold is ξ-projectively flat if and only if it is Einstein Sasakian. Necessary and sufficient conditions for a K-contact manifold to be quasi projectively flat and φ-projectively flat are obtained. We also prove that for a (2n + 1)-dimensional Sasakian manifold the conditions of being quasi projectively flat, φ-projectively flat and locally isometric to the unit sphere S ²ⁿ⁺¹ (1) are equivalent. Finally, we prove that a compact φ-projectively flat K-contact manifold with regular contact vector field is a principal S ¹-bundle over an almost Kaehler space of constant holomorphic sectional curvature 4.     

Three-stage auto-ignition of n-heptane and methyl-cyclohexane mixtures at lean conditions in a flat piston rapid compression machine

One approach to enhancing the thermal efficiency of combustion systems is to burn fuels at ultra-lean conditions (equivalence ratio below 0.5). It has been recently reported that the auto-ignition of some hydrocarbon fuels, under specific temperature, pressure, and mixture conditions, releases heat in three distinctive stages. The three auto-ignition stages can be divided as a first low-temperature auto-ignition stage with conventional low temperature, and a high-temperature stage separated into two sub-stages. This study presents ignition delay time measurements of n-heptane and methyl-cyclohexane (MCH) mixtures in a flat piston rapid compression machine (RCM) under ultra-lean conditions. It provides experimental evidence of three-stage auto-ignition. This phenomenon of delayed high-temperature heat release is seldom reported in the literature and this is the first time to be reported for these types of fuels. The experiments cover two binary n-heptane/MCH mixtures of 15/85 and 70/30 by volume, pressures of 11 bar and 16 bar, temperature range of 700 to 900 K, and equivalence ratio of 0.4. The RCM optical access was utilized for high-speed chemiluminescence imaging. Detailed chemical kinetic simulations in a homogenous batch reactor with variable volume were conducted to further interrogate the three-stage auto-ignition phenomenon. Chemiluminescence shows that three-stage auto-ignition occurs in the adiabatically compressed end-gas, which indicates that this phenomenon is chemically-driven and is not induced by a thermal stratification in the RCM experiments. The model predicts the features of three-stage auto-ignition, which were experimentally observed at temperatures approximately below 750 K. As expected, significant discrepancies are observed in the ignition delays of experiment and simulation in the negative temperature coefficient (NTC) region. The simulation of the n-heptane/MCH 70/30 mixture shows better agreement with experiments in the Positive Temperature Coefficient (PTC) region compared to the 15/85 mixture.     

Nanofibrous polyaniline thin film prepared by plasma‐induced polymerization technique for detection of NO2 gas

A nanofibrous polyaniline (PANI) thin film was fabricated using plasma‐induced polymerization method and explored its application in the fabrication of NO₂ gas sensor. The effects of substrate position, pressure, and the number of plasma pulses on the PANI film growth rate were monitored and an optimum condition for the PANI thin film preparation was established. The resulting PANI film was characterized with UV–visible spectrophotometer, FTIR, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The PANI thin film possessed nanofibers with a diameter ranging from 15 to 20 nm. The NO₂ gas sensing behavior was studied by measuring the change in electrical conductivity of PANI film with respect to NO₂ gas concentration and exposure time. The optimized sensor exhibited a sensitivity factor of 206 with a response time of 23 sec. The NO₂ gas sensor using nanofibrous PANI thin film as sensing probe showed a linear current response to the NO₂ gas concentration in the range of 10–100 ppm. Copyright © 2009 John Wiley & Sons, Ltd.     

Intramolecular Aza‐Diels‐Alder Cyclization of a Dimerized Citral with Anilines Catalyzed by InCl3

A series of aza‐polycyles containing octahydroacridine core were prepared via an intramolecular aza‐Diels‐Alder reaction of a dimerized citral with various aromatic amines. This reaction is efficiently catalyzed by InCl₃ at ambient temperature to afford the corresponding cyclized products in moderate to good yields.     

Synthesis and application of a thermosensitive tri-block copolymer as an efficient sample treatment technique for preconcentration and ultra-trace detection of lead ions

We have designed and synthesized a thermosensitive tri-block copolymer for selective trace extraction of Pb(II) ions from biological and food samples. The polymer was characterized by Fourier transform IR and NMR spectroscopy, and by gel permeation chromatography. The critical aggregation concentration and lower critical solution temperature were determined via fluorescence and UV spectrophotometry, respectively. The effects of solution pH value, amount of copolymer, of the temperature on extraction and on phase separation, and of the matrix on the extraction of Pb(II) were optimized. Pb(II) ions were then quantified by FAAS. The use of this copolymer resulted in excellent figures of merit including a calibration plot extending from 0.5 to 160 μg L^?1 (with an R² of >0.99), a limit of detection (LOD) as low as 90 pg L^?1, an extraction efficiency of >98 %, and relative standard deviations of <4 % for eight separate extraction experiments.

Diterpene glycosides from Stevia rebaudiana

Three novel diterpene glycosides were isolated for the first time from the commercial extract of the leaves of Stevia rebaudiana, along with several known steviol glycosides, namely stevioside, rebaudiosides A-F, rubusoside and dulcoside A. The new compounds were identified as 13-[(2-O-β-D-glucopyranosyl-3-O-β-D-glucopyranosyl-β-D-glucopyranosyl)oxy] ent-kaur-15-en-19-oic acid, 13-[(2-O-β-D-glucopyranosyl-3-O-β-D-glucopyranosyl-β-D-glucopyranosyl)oxy]-16β-hydroxy-ent-kauran-19-oic acid and 13-methyl-16-oxo-17-nor-ent-kauran-19-oic acid-β-D-glucopyranosyl ester on the basis of extensive 2D NMR and MS spectroscopic data as well as chemical studies.     

Nickel(II) complexes of tripodal 4N ligands as catalysts for alkane oxidation using m-CPBA as oxidant: ligand stereoelectronic effects on catalysis

Several mononuclear Ni(II) complexes of the type [Ni(L)(CH(3)CN)(2)](BPh(4))(2) 1-7, where L is a tetradentate tripodal 4N ligand such as N,N-dimethyl-N',N'-bis(pyrid-2-ylmethyl)ethane-1,2-diamine (L1), N,N-diethyl-N',N'-bis(pyrid-2-ylmethyl)ethane-1,2-diamine (L2), N,N-dimethyl-N'-(1-methyl-1H-imidazol-2-ylmethyl)-N'-(pyrid-2-ylmethyl)ethane-1,2-diamine (L3), N,N-dimethyl-N',N'-bis(1-methyl-1H-imidazol-2-ylmethyl)ethane-1,2-diamine (L4), N,N-dimethyl-N',N'-bis(quinolin-2-ylmethyl)ethane-1,2-diamine (L5), tris(benzimidazol-2-ylmethyl)amine (L6) and tris(pyrid-2-ylmethyl)amine (L7), have been isolated and characterized using CHN analysis, UV-Visible spectroscopy and mass spectrometry. The single-crystal X-ray structures of the complexes [Ni(L1)(CH(3)CN)(H(2)O)](ClO(4))(2) 1a, [Ni(L2)(CH(3)CN)(2)](BPh(4))(2) 2, [Ni(L3)(CH(3)CN)(2)](BPh(4))(2) 3 and [Ni(L4)(CH(3)CN)(2)](BPh(4))(2) 4 have been determined. All these complexes possess a distorted octahedral coordination geometry in which Ni(II) is coordinated to four nitrogen atoms of the tetradentate ligands and two CH(3)CN (2, 3, 4) or one H(2)O and one CH(3)CN (1a) are located in cis positions. The Ni-N(py) bond distances (2.054(2)-2.078(3) ?) in 1a, 2 and 3 are shorter than the Ni-N(amine) bonds (2.127(2)-2.196(3) ?) because of sp(2) and sp(3) hybridizations of the pyridyl and tertiary amine nitrogens respectively. In 3 the Ni-N(im) bond (2.040(5) ?) is shorter than the Ni-N(py) bond (2.074(4) ?) due to the stronger coordination of imidazole compared with the pyridine donor. In dichloromethane/acetonitrile solvent mixture, all the Ni(ii) complexes possess an octahedral coordination geometry, as revealed by the characteristic ligand field bands in the visible region. They efficiently catalyze the hydroxylation of alkanes when m-CPBA is used as oxidant with turnover number (TON) in the range of 340-620 and good alcohol selectivity for cyclohexane (A/K, 5-9). By replacing one of the pyridyl donors in TPA by a weakly coordinating -NMe(2) or -NEt(2) donor nitrogen atom the catalytic activity decreases slightly with no change in the selectivity. In contrast, upon replacing the pyridyl nitrogen donor by the strongly σ-bonding imidazolyl or sterically demanding quinolyl/benzimidazolyl nitrogen donor, both the catalytic activity and selectivity decrease, possibly due to destabilization of the intermediate [(4N)(CH(3)CN)Ni-O˙](+) radical species. Adamantane is selectively (3°/2°, 12-17) oxidized to 1-adamantanol, 2-adamantanol and 2-adamantanone while cumene is selectively oxidized to 2-phenyl-2-propanol. In contrast to cyclohexane oxidation, the incorporation of sterically hindering quinolyl/benzimidazolyl donors around Ni(ii) leads to a high 3°/2° bond selectivity for adamantane oxidation. A linear correlation between the metal-ligand covalency parameter (β) and the turnover number has been observed.     

The in vivo anti-plasmodial activity of haliclonacyclamine A, an alkaloid from the marine sponge, Haliclona sp

The compound haliclonacyclamine A was isolated from the Haliclona sponge at Solomon Islands. It acts as a powerful in?vitro and in?vivo anti-plasmodial agent against the chloroquine-resistant Plasmodium falciparum strain FCB1and Plasmodium vinckei petteri-infected mice, respectively.