The reproducibility of phospholipid analyses by MALDI-MSMS

The identification of phosphocholine and phosphoethanolamine lipids by MALDI TOF/TOF, including characterisation of the headgroup and delineation of the acyl chain at each position of the glycerol backbone, has been explored using lipids representative of each type. The relative intensities of fragments involving the neutral loss of one or other of the acyl chains from ion adducts of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine (POPE), 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and 1-oleoyl-2-palmitoyl-sn-glycero-3-phosphocholine (OPPC) were compared. For POPC and POPE, a statistical preference for the loss of the chain from the sn-1 position was observed in the presence of lithium. For OPPC this selectivity was reversed for one of the fragments. In the absence of lithium, fragmentation was favoured at the sn-2 position for all lipids. In all cases, spectra obtained in the presence of lithium yielded more intense product ion peaks. Although Collision Induced Dissociation (CID) could be used for complete lipid characterisation, LIFT? was found to be a better method due to the presence of a greater number of distinguishing product ion peaks and a better shot-to-shot reproducibility of peak intensities.     

Nucleophilic reactivity of thiolate, hydroxide and phenolate ions towards a model O-arylated diazeniumdiolate prodrug in aqueous and cationic surfactant media

The kinetics of aromatic nucleophilic substitution of the nitric oxide‐generating diazeniumdiolate ion, DEA/NO, by thiols (L ‐glutathione, L ‐cysteine, DL ‐homocysteine, 1‐propanethiol, 2‐mercaptoethanol, and sodium thioglycolate) from the prodrug, DNP‐DEA/NO, has been examined in aqueous solution and in solutions of cationic DOTAP vesicles. Second‐order rate constants in buffered aqueous solutions (k_RS‐ = 3.48–30.9 M^?1 s^?1; 30 °C) gave a linear Brønsted plot (β_nuc = 0.414 ± 0.068) consistent with the rate‐limiting S_NAr nucleophilic attack by thiolate ions. Cationic DOTAP vesicles catalyze the thiolysis reactions with rate enhancements between 11 and 486‐fold in Tris‐HCl buffered solutions at pH 7.4. The maximum rate increase was obtained with thioglycolate ion. Thiolysis data are compared to data for nucleophilic displacement by phenolate (k_PhO‐ = 0.114 M^?1 s^?1) and hydroxide (k_OH‐ = 1.82 × 10^?2 M^?1 s^?1, 37 °C) ions. The base hydrolysis reaction is accelerated by CTAB micelles and DODAC vesicles, with the vesicles being ca 3‐fold more effective as catalysts. Analysis of the data using pseudo‐phase ion‐exchange (PIE) formalism implies that the rate enhancement of the thiolysis and base hydrolysis reactions is primarily due to reactant concentration in the surfactant pseudo‐phase. Copyright © 2009 John Wiley & Sons, Ltd.     

2-(Aminoaryl)alkanone O-phenyl oximes: versatile reagents for syntheses of quinazolines

Microwave irradiations of 2-(aminoaryl)alkanone O-phenyl oximes and carbonyl compounds generate iminyl radicals in company with imines; iminyl on imine ring closure yields dihydroquinazolines or quinazolines when ZnCl2 is included in the mixture.     

Synthesis of carbohydrate-conjugated nanoparticles and quantum dots

Nanoparticle-based probes are emerging as alternatives to molecular probes due to their various advantages, such as bright and tunable optical property, enhanced chemical and photochemical stability, and ease of introduction of multifunctionality. This work presents a simple and general approach for functionalizing various nanoparticle systems for use as glycobiological probes. Silica-coated nanoparticles of Ag, Fe3O4, and ZnS-CdSe were synthesized and functionalized with dextran. The resulting 10-40-nm-sized particles were robust, water-soluble, colloidally stable, and biochemically active.     

Developing and applying quantitative skills maps for STEM curricula,with a focus on different modes of learning

Mapping quantitative skills across the science, technology, engineering and mathematics (STEM) curricula will help educators identify gaps and duplication in the teaching, practice and assessment of the necessary skills. This paper describes the development and implementation of quantitative skills mapping tools for courses in STEM at a regional university that offers both on-campus and distance modes of study. Key elements of the mapping project included the identification of key graduate quantitative skills, the development of curriculum mapping tools to record in which unit(s) and at what level of attainment each quantitative skill is taught, practised and assessed, and identification of differences in the way quantitative skills are developed for on-campus and distance students. Particular attention is given to the differences that are associated with intensive schools, which consist of concentrated periods of face-to-face learning over a three-four day period, and are available to distance education students enrolled in STEM units. The detailed quantitative skills mapping process has had an impact on the review of first-year mathematics units, resulted in crucial changes to the curriculum in a number of courses, and contributed to a more integrated approach, and a collective responsibility, to the development of students' quantitative skills for both face-to-face and online modes of learning.     

Synthesis of Microporous Transition Metal Oxide Molecular Sieves with Bifunctional Templating Molecules

Systematic tuning of the micropore size in microporous transition metal oxide molecular sieves can be achieved by varying the length of the hydrocarbon chain of the diamine molecules used as templating agents. The large bifunctional molecules self-assemble with much smaller cross-sectional micellar dimensions than their monofunctional counterparts. The resulting family of porous materials offers exciting new flexibility in designing molecular sieves targeted for size selectivity and chemical functionality.     

Carbon dioxide mediated stereoselective copper-catalyzed reductive coupling of alkynes and thiols

A simple protocol for the stereoselective copper-catalyzed hydrothiolation of alkynes under a CO(2) atmosphere has been developed. The stereoselectivity is determined by the presence/absence of a CO(2) atmosphere. The reaction system is robust and utilizes inexpensive, readily available substrates. A cyclic alkene/carboxylate copper complex intermediate is proposed as the key step in determining the stereoselectivity, and an equivalent amount of water is found to play an active role as a proton donor.