A new, simple and rapid procedure has been developed and validated for the determination of cocaine and its main metabolite, benzoylecgonine, in human hair samples. After extraction from within the hair matrix by a mixture of methanol/hydrochloric acid (2:1) at 65 degrees C for 3 h, and sample cleanup by mixed-mode solid-phase extraction (SPE), the extracts were analyzed by gas chromatography/m...

Addition of lithium aryl(tetraisopropoxy)titanates [ArTi(OPri)4 Li ] to , -unsaturated ketones proceeded with high enantioselectivity (up to 99% ee) in the presence of an excess amount of chlorotrimethylsilane and a rhodium catalyst (3 mol % Rh), generated from [RhCl(C2H4)2]2 and (S)-binap, in tetrahydrofuran at 20°C to give high yields of the corresponding silyl enolates as 1,4-addition produc...

In the in vitro motility assay, actin filaments are propelled by surface-adsorbed myosin motors, or rather, myosin motor fragments such as heavy meromyosin (HMM). Recently, efforts have been made to develop actomyosin powered nanodevices on the basis of this assay but such developments are hampered by limited understanding of the HMM adsorption geometry. Therefore, we here investigate the HMM a...

Membranes exhibiting high flux and selectivity are important for many applications, including water desalination, greenhouse gas storage and abatement, H2 purification, and selective proton/oxygen conduction in fuel cells. Combined high flux and selectivity is achieved in natural systems by membrane-bound ion and molecular channelsswhose pore size is defined with sub-nanometer precision through...

A gas chromatographic method which makes possible simultaneous analysis of common types of acidic and neutral sugars is described. Particular advantages are achieved with hydroxy acids, ketoses, and uronic acids. Acids and lactones are first converted into their sodium salts. Free or potential aldehydo and keto groups are transformed to oximes or O-methyloximes. Fully substituted acyclic ester ...

Wound healing is still a serious medical problem due to process complexity and lack of effective medicaments. This is particularly true in the treatment of wounds arising in the course of such diseases as AIDS or diabetes. Therefore, scientific efforts are focused on the search for new compounds of natural origin, which could be used as medicines or evaluated for subsequent drug design. In folk...

Gastropod haemocyanins are multisubunit copper-containing proteins with molecular weights in the region of 9 x lo6. They have been shown to be glycoproteins with total carbohydrate contents of 1-8 %, estimated by colorimetric and quantitative t.1.c. methods (Dijk et al., 1970). They are unusual in having no sialic acid residues, but, as is the case with most other glycoproteins, there are few c...

tic cis-benzenediol was present on both plates, with R, values of 0.21 and 0.24 respectively. Another portion of the thoroughly dried ether extract was treated with Bis (trimethylsily1)trifluoracetamide and trimethylchlorosilane for 30min at 90° C and the trimethylsilyl derivative injected into a Pye 104 chromatograph fitted with a glass column packed with 4% OV 255 on Chromosorb WHP and a flam...

In vitro techniques have been used to investigate the nature of microsomal cytochrome P450 involved in the metabolism of oleic acid, a physiological monounsaturated fatty acid. Like lauric acid, which is currently used as a model substrate of fatty acid metabolism, the alkyl chain of oleic acid is hydroxylated on its v and ( v –1) carbons. The identity of these hydroxylated metabolites was asce...