Molecularly Imprinted Polymers for the isolation of bioactive naphthoquinones from plant extracts

Molecularly Imprinted Polymers (MIPs) targeting shikonin, a potent antioxidant and wound healing agent, have been prepared using methacrylic acid (MAA) and 2-diethylaminoethyl methacrylate (DEAEMA) as functional monomers. An investigation of solution association between shikonin and both acidic and basic functional monomers by UV-Vis titrations, suggested stronger affinity towards the basic functionality. Strong inhibition of the co-polymerisation reaction of such basic monomers was observed, but was overcome by reduction of the amount of template used during polymer synthesis. Polymer morphology was severely impacted by the template’s radical scavenging behaviour as demonstrated by solid state NMR spectroscopy measurements. HPLC evaluation of the final materials in polar conditions revealed limited imprinting effects and selectivity, with the MAA polymers exhibiting marginally better performance. During application of the polymers as MI-SPE sorbents in non-polar solvents it was found that the DEAEMA based polymer was more selective towards shikonin compared to the MAA counterpart, while shikonin recoveries of up to 72% were achieved from hexane solutions of a commercial sample of shikonin, hexane extract of Alkanna tinctoria roots and a commercial pharmaceutical ointment.

Electrical conductivity and glass formation in nitrile-functionalized pyrrolidinium bis(trifluoromethylsulfonyl)imide ionic liquids: chain length and odd–even effects of the alkyl spacer between the pyrrolidinium ring and the nitrile group

The electrical conductivity of a series of pyrrolidinium bis(trifluoromethylsulfonyl)imide ionic liquids, functionalized with a nitrile (cyano) group at the end of an alkyl chain attached to the cation, was studied in the temperature range between 173 K and 393 K. The glass formation of the ionic liquids is influenced by the length of the alkyl spacer separating the nitrile function from the pyrrolidinium ring. The electrical conductivity and the viscosity do not show a monotonic dependence on the alkyl spacer length, but rather an odd-even effect. An explanation for this behavior is given, including the potential energy landscape picture for the glass transition.

Quantum annealing of an ising spin-glass by Green's function Monte Carlo

We present an implementation of quantum annealing (QA) via lattice Green's function Monte Carlo (GFMC), focusing on its application to the Ising spin glass in transverse field. In particular, we study whether or not such a method is more effective than the path-integral Monte Carlo- (PIMC) based QA, as well as classical simulated annealing (CA), previously tested on the same optimization problem. We identify the issue of importance sampling, i.e., the necessity of possessing reasonably good (variational) trial wave functions, as the key point of the algorithm. We performed GFMC-QA runs using such a Boltzmann-type trial wave function, finding results for the residual energies that are qualitatively similar to those of CA (but at a much larger computational cost), and definitely worse than PIMC-QA. We conclude that, at present, without a serious effort in constructing reliable importance sampling variational wave functions for a quantum glass, GFMC-QA is not a true competitor of PIMC-QA.

Multilayered glass fibre-reinforced composites in rotational moulding

The potential of multiple layer fibre-reinforced mouldings is of growing interest to the rotational moulding industry because of their cost/performance ratio. The particular problem that arises when using reinforcements in this process relate to the fact that the process is low shear and good mixing of resin and reinforcement is not optimum under those conditions. There is also a problem of the larger/heavier reinforcing agents segregating out of the powder to lay up on the inner part surface. In this study, short glass fibres were incorporated and distributed into a polymer matrix to produce fibre-reinforced polymer composites using the rotational moulding process and characterised in terms of morphology and mechanical properties. © 2011 American Institute of Physics.

A new and less destructive laboratory procedure for the physical separation of distal glass tephra shards from sediments

Tephrochronology, a key tool in the correlation of Quaternary sequences, relies on the extraction of tephra shards from sediments for visual identification and high-precision geochemical comparison. A prerequisite for the reliable correlation of tephra layers is that the geochemical composition of glass shards remains unaltered by natural processes (e.g. chemical exchange in the sedimentary environment) and/or by laboratory analytical procedures. However, natural glasses, particularly when in the form of small shards with a high surface to volume ratio, are prone to chemical alteration in both acidic and basic environments. Current techniques for the extraction of distal tephra from sediments involve the ‘cleaning’ of samples in precisely such environments and at elevated temperatures. The acid phase of the ‘cleaning’ process risks alteration of the geochemical signature of the shards, while the basic phase leads to considerable sample loss through dissolution of the silica network. Here, we illustrate the degree of alteration and loss to which distal tephras may be prone, and introduce a less destructive procedure for their extraction. This method is based on stepped heavy liquid flotation and which results in samples of sufficient quality for analysis while preserving their geochemical integrity. In trials, this method out-performed chemical extraction procedures in terms of the number of shards recovered and has resulted in the detection of new tephra layers with low shard concentrations. The implications of this study are highly significant because (i) the current database of distal tephra records and their corresponding geochemical signatures may require refinement and (ii) the record of distal tephras may be incomplete due to sample loss induced by corrosive laboratory procedures. It is therefore vital that less corrosive laboratory procedures are developed to make the detection and classification of distal glass tephra more secure.

Bioactive Gyroid Scaffolds Formed by Sacrificial Templating of Nanocellulose and Nanochitin Hydrogels as Instructive Platforms for Biomimetic Tissue Engineering

A sacrificial templating process using lithographically printed minimal surface structures allows complex de novo geometries of delicate hydrogel materials. The hydrogel scaffolds based on cellulose and chitin nanofibrils show differences in terms of attachment of human mesenchymal stem cells, and allow their differentiation into osteogenic outcomes. The approach here serves as a first example toward designer hydrogel scaffolds viable for biomimetic tissue engineering.

Losses of bioactive polyacetylenes during minimal processing of carrots

Vegetables of the Apiaceae plant family such as carrots, parsnip, celery and parsley,contain in minor quantities, a group of bioactive aliphatic C17-polyacetylenes (falcarinol,falcarindiol, falcarindiol-3- acetate). Recent studies have highlighted important biologicalfunctions in vitro and in vivo (animal studies) although the beneficial effect in humannutrition attributable to an increased in polyacetylenes diet are yet to be confirmed(Lund, 1990).Carrots not only contain relatively high polyacetylene content but also form a significantpart of many countries dietary habits. Carrots are also present in some ready-to-eat foodssuch as chilled freshly prepared salads, as part of the increasingly popular minimallyprocessed foods. Whereas the effect of conventional processing (boiling, vacuum processing) on the levels of polyacetylenes has been relatively well studied, the effect of minimal mechanical operations such as “peeling”, “mechanical cutting” and “chlorine washing” remains unknown.

Tephra from andesitic Shiveluch volcano, Kamchatka, NW Pacific: chronology of explosive eruptions and geochemical fingerprinting of volcanic glass

The ~16-ka-long record of explosive eruptions from Shiveluch volcano (Kamchatka, NW Pacific) is refined using geochemical fingerprinting of tephra and radiocarbon ages. Volcanic glass from 77 prominent Holocene tephras and four Late Glacial tephra packages was analyzed by electron microprobe. Eruption ages were estimated using 113 radiocarbon dates for proximal tephra sequence. These radiocarbon dates were combined with 76 dates for regional Kamchatka marker tephra layers into a single Bayesian framework taking into account the stratigraphic ordering within and between the sites. As a result, we report ~1,700 high-quality glass analyses from Late Glacial–Holocene Shiveluch eruptions of known ages. These define the magmatic evolution of the volcano and provide a reference for correlations with distal fall deposits. Shiveluch tephras represent two major types of magmas, which have been feeding the volcano during the Late Glacial–Holocene time: Baidarny basaltic andesites and Young Shiveluch andesites. Baidarny tephras erupted mostly during the Late Glacial time (~16–12.8 ka BP) but persisted into the Holocene as subordinate admixture to the prevailing Young Shiveluch andesitic tephras (~12.7 ka BP–present). Baidarny basaltic andesite tephras have trachyandesite and trachydacite (SiO₂ < 71.5 wt%) glasses. The Young Shiveluch andesite tephras have rhyolitic glasses (SiO₂ > 71.5 wt%). Strongly calc-alkaline medium-K characteristics of Shiveluch volcanic glasses along with moderate Cl, CaO and low P₂O₅ contents permit reliable discrimination of Shiveluch tephras from the majority of other large Holocene tephras of Kamchatka. The Young Shiveluch glasses exhibit wave-like variations in SiO₂ contents through time that may reflect alternating periods of high and low frequency/volume of magma supply to deep magma reservoirs beneath the volcano. The compositional variability of Shiveluch glass allows geochemical fingerprinting of individual Shiveluch tephra layers which along with age estimates facilitates their use as a dating tool in paleovolcanological, paleoseismological, paleoenvironmental and archeological studies. Electronic tables accompanying this work offer a tool for statistical correlation of unknown tephras with proximal Shiveluch units taking into account sectors of actual tephra dispersal, eruption size and expected age. Several examples illustrate the effectiveness of the new database. The data are used to assign a few previously enigmatic wide-spread tephras to particular Shiveluch eruptions. Our finding of Shiveluch tephras in sediment cores in the Bering Sea at a distance of ~600 km from the source permits re-assessment of the maximum dispersal distances for Shiveluch tephras and provides links between terrestrial and marine paleoenvironmental records.