Carboxylmethyl chitosan-graft-poly(γ-benzyl-l-glutamate) glycopeptides: Synthesis and particle formation as encapsulants

Amphiphilic glycopeptides, carboxylmethyl chitosan-graft-poly(γ-benzyl-l-glutamate) (m-Chi-g-PBLG), were synthesized through ring-opening polymerization of γ-benzyl-l-glutamate N-carboxyanhydride (NCA) using short chained m-Chi as the macroinitiator and employed to form vesicles in aqueous solution. The elemental and NMR analyses revealed that the polymerization degree (DP) of grafted PBLG could be tuned by varying the feed ratio of NCA to m-Chi. The conformation of the grafted PBLG chains transformed from β-sheet to α-helix was correlated with the PBLG chain length. The m-Chi-g-PBLG vesicles can be prepared using double emulsion method and their sizes can be adjusted between 140 and 250 nm. The encapsulation of a model compound, FITC-dextran, in the vesicles revealed their potential applications as encapsulants or carriers. The in vitro release data revealed that a sustained release of FITC-dextran for a time period over two weeks can be achieved.     

Efficient driver drowsiness detection at moderate levels of drowsiness

Previous research on driver drowsiness detection has focused primarily on lane deviation metrics and high levels of fatigue. The present research sought to develop a method for detecting driver drowsiness at more moderate levels of fatigue, well before accident risk is imminent. Eighty-seven different driver drowsiness detection metrics proposed in the literature were evaluated in two simulated shift work studies with high-fidelity simulator driving in a controlled laboratory environment. Twenty-nine participants were subjected to a night shift condition, which resulted in moderate levels of fatigue; 12 participants were in a day shift condition, which served as control. Ten simulated work days in the study design each included four 30-min driving sessions, during which participants drove a standardized scenario of rural highways. Ten straight and uneventful road segments in each driving session were designated to extract the 87 different driving metrics being evaluated. The dimensionality of the overall data set across all participants, all driving sessions and all road segments was reduced with principal component analysis, which revealed that there were two dominant dimensions: measures of steering wheel variability and measures of lateral lane position variability. The latter correlated most with an independent measure of fatigue, namely performance on a psychomotor vigilance test administered prior to each drive. We replicated our findings across eight curved road segments used for validation in each driving session. Furthermore, we showed that lateral lane position variability could be derived from measured changes in steering wheel angle through a transfer function, reflecting how steering wheel movements change vehicle heading in accordance with the forces acting on the vehicle and the road. This is important given that traditional video-based lane tracking technology is prone to data loss when lane markers are missing, when weather conditions are bad, or in darkness. Our research findings indicated that steering wheel variability provides a basis for developing a cost-effective and easy-to-install alternative technology for in-vehicle driver drowsiness detection at moderate levels of fatigue.     

Characterisation Leaching Tests and Associated Geochemical Speciation Modelling to Assess Long Term Release Behaviour from Extractive Wastes

A pH dependent leaching test (CEN/TS 14429) and a percolation leaching test (CEN/TS 14405) developed in CEN/TC 292 have been used for the first time to characterise the release behaviour of different sulphidic mining wastes. Geochemical speciation modeling using LeachXS Orchestra provides another type of partitioning between mineral and sorptive phases than is currently practised in the mining industry. Comparing new leaching test data for seven tailings and two waste rock samples with model predictions gives new insights into release behaviour. In leaching, mineral transformations on the surface of waste rock or tailings particles, rather than bulk mineral composition, dictate release, which implies that mineralogical examinations are not necessarily relevant from a leaching perspective. Kinetic aspects of release from sulphidic waste can be addressed by testing material in different stages of oxidation or exposure to atmospheric conditions.     

An Overview of the Cyclic Partial Austenite-Ferrite Transformation Concept and Its Potential

Over the past decades, the mechanism of interface migration during the austenite-ferrite transformation in steels has attracted significant attention from physical metallurgists. There are two challenging research questions in this field: (i) What is the effect of (substitutional) alloying elements on migrating interfaces? and (ii) How to accurately determine the value of interface mobility?. Recently, a cyclic partial phase transformation approach has been proposed to study interface migration, and new insights into the above two questions have been provided. An overview of the cyclic partial phase transformation concept is given, and pathways for future research are suggested.     

Ester-functionalized poly(3-alkylthiophene) copolymers: Synthesis,physicochemical characterization and performance in bulk heterojunction organic solar cells

The introduction of functional moieties in the donor polymer (side chains) offers a potential pathway toward selective modification of the nanomorphology of conjugated polymer:fullerene active layer blends applied in bulk heterojunction organic photovoltaics, pursuing morphology control and solar cell stability. For this purpose, two types of poly(3-alkylthiophene) random copolymers, incorporating different amounts (10/30/50%) of ester-functionalized side chains, were efficiently synthesized using the Rieke method. The solar cell performance of the functionalized copolymers was evaluated and compared to the pristine P3HT:PCBM system. It was observed that the physicochemical and opto-electronic characteristics of the polythiophene donor material can be modified to a certain extent via copolymerization without (too much) jeopardizing the OPV efficiency, as far as the functionalized side chains are introduced in a moderate ratio (<30%) and that preference is given to side chains with a small molar volume. A range of complementary techniques – UV–Vis spectroscopy, (modulated temperature) differential scanning calorimetry, transmission electron microscopy and X-ray diffraction analysis – indicated that variations in polymer crystallinity, while maintaining a high level of regioregularity, are probably the main factor responsible for the observed differences.     

An Evolutionary Model of Price Competition Among Spatially Distributed Firms

Various studies have shown the emergence of cooperative behavior in evolutionary models with repeated local interaction among spatially distributed agents. We investigate to what extent these findings generalize to evolutionary models of price competition among spatially distributed firms. We consider both one- and two-dimensional models, and we vary the amount of information firms have about competitors in their neighborhood. Our computer simulations show that the emergence of cooperative behavior depends strongly on the amount of information available to firms. Firms tend to behave most cooperatively if they have only a very limited amount of information about their competitors. We provide an intuitive explanation for this phenomenon. Our simulations further indicate that three other factors in our models, namely the accuracy of firms’ information, the probability of experimentation, and the spatial distribution of consumers, have little effect on the emergence of cooperative behavior.     

Straightforward Reconstruction of Smooth Concave Diffusivity Profiles from Photothermal Phase

This article introduces a fast and easy way to retrieve smooth concave thermal-diffusivity profiles from the photothermal (PT) response of a semi-infinite solid with concave depth-dependent thermal diffusivity, such as case-hardened steels. The approach is based on the exact asymptotic behavior of the PT phase and on the position, height, and width of the phase maximum. The resulting procedure, which only requires PT phase data at relatively few frequencies, is unambiguous and involves only simple algebraic formulae and no tweaking. The method is successfully applied to the inversion of some simulated profiles, including the demanding piecewise linear one, proving the value of the method.     

An emergent approach to systems of physical agents

For the past ten years the author has been involved in industrial research on applications of agent architectures to manufacturing, and is presently technical advisor to an industrial consortium that is fielding pilot tests of shop-floor agents. The specific problem addressed by most of their work is the management of material flow and resource utilization on the factory floor. Classically, these problems have been considered under the rubrics of ‘scheduling’ and ‘shop-floor control’, and have been addressed with top-down control that does not offer the robustness and agility required in modern competitive environments. The approach has been to reify parts and equipment as agents, and seek architectures that permit the overall shop schedule to emerge dynamically from their interaction, rather than being imposed top-down.