185 research outputs found

    Experimenting with undergraduate practicals

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    In my experience the prescriptive nature of many undergraduate practicals restricts the scope for students to apply and develop their subject-specific knowledge. In addition, the nature of such practicals places limitations on their effectiveness for development of problem solving, team working and transferable skills. In recognition of this, a number of laboratory practicals in physical chemistry have been developed (some from existing traditional scripts) which feature clearly formulated and explicit objectives, but which omit detailed instructions to a greater or lesser extent. One particular aspect of these practicals is that the onus is placed on students to design a viable experimental approach in order to achieve the stated objectives and to reflect critically on their work. In this respect some of the practicals may be considered as structured mini-projects. Another implicit aspect is an attempt to encourage students to de-compartmentalise their subject knowledge (e.g. organic mechanisms in a ‘physical’ chemistry practical).The practicals have been used successfully at levels 1 and 2 during the past two years at Keele, and although the approach described has been applied to laboratory work in physical chemistry, there is no reason why it cannot be applied more generally

    Industry-linked context-based chemistry practicals

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    There is considerable evidence that the use of tangible contexts enriches the learning experience for students. In view of this, the author has developed two ‘industry-linked context-based chemistry practicals’ that illustrate the importance of core chemistry topics within commercial/industrial contexts. A common feature of the practicals is that the students work with actual commercial samples and compare their data with that published by the two companies. The principal features of the two practicals are described and contrasted with conventional practicals. Finally, the results of a student evaluation of the practicals are reported

    Remotely triggered scaffolds for controlled release of pharmaceuticals

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    Fe3O4-Au hybrid nanoparticles (HNPs) have shown increasing potential for biomedical applications such as image guided stimuli responsive drug delivery. Incorporation of the unique properties of HNPs into thermally responsive scaffolds holds great potential for future biomedical applications. Here we successfully fabricated smart scaffolds based on thermo-responsive poly(N-isopropylacrylamide) (pNiPAM). Nanoparticles providing localized trigger of heating when irradiated with a short laser burst were found to give rise to remote control of bulk polymer shrinkage. Gold-coated iron oxide nanoparticles were synthesized using wet chemical precipitation methods followed by electrochemical coating. After subsequent functionalization of particles with allyl methyl sulfide, mercaptodecane, cysteamine and poly(ethylene glycol) thiol to enhance stability, detailed biological safety was determined using live/dead staining and cell membrane integrity studies through lactate dehydrogenase (LDH) quantification. The PEG coated HNPs did not show significant cytotoxic effect or adverse cellular response on exposure to 7F2 cells (p < 0.05) and were carried forward for scaffold incorporation. The pNiPAM-HNP composite scaffolds were investigated for their potential as thermally triggered systems using a Q-switched Nd:YAG laser. These studies show that incorporation of HNPs resulted in scaffold deformation after very short irradiation times (seconds) due to internal structural heating. Our data highlights the potential of these hybrid-scaffold constructs for exploitation in drug delivery, using methylene blue as a model drug being released during remote structural change of the scaffold

    Using audio for feedback on assessments: Tutor and student experiences

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    Recently we have been providing individual audio feedback to 1st and 2nd year undergraduate Chemistry students on a variety of assessments (posters, laboratory reports, laboratory diaries) with the aim of providing richer, more detailed and more comprehensible individual feedback than is possible within the same timeframe using written feedback. In this communication, various aspects of the use of audio for feedback are discussed including practical and technical aspects of the recording of audio files whilst viewing and assessing student work, the transmission of these files to individual students, our experiences as tutors of providing audio feedback and the experiences and views of students on audio feedback

    Statistical mechanics of voting

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    Decision procedures aggregating the preferences of multiple agents can produce cycles and hence outcomes which have been described heuristically as `chaotic'. We make this description precise by constructing an explicit dynamical system from the agents' preferences and a voting rule. The dynamics form a one dimensional statistical mechanics model; this suggests the use of the topological entropy to quantify the complexity of the system. We formulate natural political/social questions about the expected complexity of a voting rule and degree of cohesion/diversity among agents in terms of random matrix models---ensembles of statistical mechanics models---and compute quantitative answers in some representative cases.Comment: 9 pages, plain TeX, 2 PostScript figures included with epsf.tex (ignore the under/overfull \vbox error messages

    Increasing diterpene yield with a modular metabolic engineering system in E. coli: comparison of MEV and MEP isoprenoid precursor pathway engineering

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    Engineering biosynthetic pathways in heterologous microbial host organisms offers an elegant approach to pathway elucidation via the incorporation of putative biosynthetic enzymes and characterization of resulting novel metabolites. Our previous work in Escherichia coli demonstrated the feasibility of a facile modular approach to engineering the production of labdane-related diterpene (20 carbon) natural products. However, yield was limited (<0.1 mg/L), presumably due to reliance on endogenous production of the isoprenoid precursors dimethylallyl diphosphate and isopentenyl diphosphate. Here, we report incorporation of either a heterologous mevalonate pathway (MEV) or enhancement of the endogenous methyl erythritol phosphate pathway (MEP) with our modular metabolic engineering system. With MEP pathway enhancement, it was found that pyruvate supplementation of rich media and simultaneous overexpression of three genes (idi, dxs, and dxr) resulted in the greatest increase in diterpene yield, indicating distributed metabolic control within this pathway. Incorporation of a heterologous MEV pathway in bioreactor grown cultures resulted in significantly higher yields than MEP pathway enhancement. We have established suitable growth conditions for diterpene production levels ranging from 10 to >100 mg/L of E. coli culture. These amounts are sufficient for nuclear magnetic resonance analyses, enabling characterization of enzymatic products and hence, pathway elucidation. Furthermore, these results represent an up to >1,000-fold improvement in diterpene production from our facile, modular platform, with MEP pathway enhancement offering a cost effective alternative with reasonable yield. Finally, we reiterate here that this modular approach is expandable and should be easily adaptable to the production of any terpenoid natural product

    Mutations in the UBIAD1 Gene, Encoding a Potential Prenyltransferase, Are Causal for Schnyder Crystalline Corneal Dystrophy

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    Schnyder crystalline corneal dystrophy (SCCD, MIM 121800) is a rare autosomal dominant disease characterized by progressive opacification of the cornea resulting from the local accumulation of lipids, and associated in some cases with systemic dyslipidemia. Although previous studies of the genetics of SCCD have localized the defective gene to a 1.58 Mbp interval on chromosome 1p, exhaustive sequencing of positional candidate genes has thus far failed to reveal causal mutations. We have ascertained a large multigenerational family in Nova Scotia affected with SCCD in which we have confirmed linkage to the same general area of chromosome 1. Intensive fine mapping in our family revealed a 1.3 Mbp candidate interval overlapping that previously reported. Sequencing of genes in our interval led to the identification of five putative causal mutations in gene UBIAD1, in our family as well as in four other small families of various geographic origins. UBIAD1 encodes a potential prenyltransferase, and is reported to interact physically with apolipoprotein E. UBIAD1 may play a direct role in intracellular cholesterol biochemistry, or may prenylate other proteins regulating cholesterol transport and storage