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Solid-phase extraction and HPLC determination of levamisole hydrochloride in sheep plasma
15 Aug 2013The anthelmintic, levamisole, was determined in sheep plasma by means of ion-pair solid-phase extraction (SPE) and reverse-phase liquid chromatography. The SPE columns were conditioned with 2 ml of methanol followed by 1 ml of octane sulphonic-acid buffer. After sample application, the columns were washed with 2 ml of the same buffer, followed by elution with 90/10 acetonitrile: buffer. A phen…
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Cryopreservation of sheathed third-stage larvae of Gaigeria pachyscelis (Sandveld hookworm)
03 Sep 2013A technique for the cryopreservation of third stage larvae of Gaigeria pachyscelis is described. It consists of incubating sheathed third-stage larvae in 80% (v/v) ethylene glycol as a cryoprotectant for 30 s at 0°C, prior to transfer into liquid nitrogen. The survival rate, as assessed by motility, was 37,6% after 30 d cryopreservation. A sheep infected percutaneously with 700 live cryopreserved…
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Isolation of the toxin responsible for gousiekte, a plant-induced cardiomyopathy of ruminants in southern Africa
12 Sep 2013Gousiekte was induced in sheep and goats by the oral and intravenous (i/v) administration of methanolic and ethanolic precipitates of aqueous extracts of Pavetta harborii. Further purification of the toxic principle was carried out by dialysis and ion-exchange chromatography. The toxin was eluted from the cation-exchange resin with 1 mol/l of ammonium acetate and finally purified on Sephadex G-10…
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Metagenomics, gene discovery and the ideal biocatalyst
20 Sep 2010With the rapid development of powerful protein evolution and enzyme-screening technologies, there is a growing belief that optimum conditions for biotransformation processes can be established without the constraints of the properties of the biocatalyst. These technologies can then be applied to find the ‘ideal biocatalyst’ for the process. In identifying the ideal biocatalyst, the processes o…
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Components for PEM fuel cells: An overview
29 Oct 2010Fuel cells, as devices for direct conversion of the chemical energy of a fuel into electricity by electrochemical reactions, are among the key enabling technologies for the transition to a hydrogen-based economy. Among the various types of fuel cells, polymer electrolyte membrane fuel cells (PEMFCs) are considered to be at the forefront for commercialization for portable and transportation ap…
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Expression, purification and preliminary crystallographic analysis of recombinant human DEAD-box polypeptide 5
05 Jan 2014The DEAD-box RNA helicase DDX5 is involved in many aspects of RNA processing and has been implicated in a number of cellular processes involving alteration of RNA secondary structure. The N-terminal region of DDX5, which contains the conserved domain 1 of the DEAD-box helicases, has been cloned and expressed in Escherichia coli and purified. Here, the crystallization and preliminary diffract…
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Bis(ferrocenylimine)palladium(II) and platinum(II) complexes: synthesis, molecular structures and evaluation as antitumor agents
31 Mar 2014Compounds (ferrocenyl-2-furylmethyl)imine (L1), (ferrocenyl-2-thiophenemethyl)imine (L2) and (ferrocenyl-2-thiopheneethyl)imine (L3) were synthesized by condensation reactions and obtained in very good yields. Reactions of L1 – L3 with 0.5 equiv of either PdCl2(cod), PdClMe(cod) or K2[PtCl4] gave the new corresponding trans bis(ferrocenylimine)palladium(II) and platinum(II) complexes 1 – 9. The c…
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New phenylene bridged binuclear bis (imino-quinolyl) palladium(II) complexes: synthesis, characterization and Heck reactions
17 Mar 2014Two new phenylene bridged binuclear bis(imino-quinolyl) palladium (II) complexes were prepared from the reaction of the ligand 1,4-bis(imino-quinolyl)benzene, L1 with either Pd(cod)Cl2 or Pd(cod)ClMe. The molecular structure of L1 was confirmed by single crystal X-ray diffraction analysis. The structure shows two planar molecules (A and B) in the asymmetric unit. The complexes were evaluated as c…
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What can be deduced from open cluster metallicity measurements?
15 Oct 2013The dependence of [Fe/H] on galactocentric distance, distance from the galactic mid-plane and age is studied. Both ordinary least-squares and non-parametric regression in the form of a ‘generalized additive model’ are used. The radial metallicity slope is found to be shallower than previously claimed in the literature, and there is a significant abundance gradient perpendicular to the galacti…
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Guidelines for the selection of tooth whitening products amongst those available on the market
12 Jan 2014Background: Several tooth whiteners are available on the market, and the ideal choice should be determined by ef ficacy and optimal clinical results. Objectives: The purpose of this study was to compare the reported clinical success rates of different tooth whitening products. Search strategy: The relevant literature (1998 - 2011) was studied, using as sources the databases: Google Scholar, S…