Influence of thermal ageing on the stability of polymer bulk heterojunction solar cells

A new approach is presented in order to improve the thermal stability of polymer: [6-6]-phenyl C₆₁ butyric acid methyl ester (PCBM) bulk heterojunction solar cells. The central idea in this approach is the use of a polymer with high glass transition temperature (T_g), well above the normal operating temperatures of the devices. In this paper, a PPV-derivative with a T_g of 150 °C was used as an electron donor and the thermal stability of the obtained solar cells was compared with solar cells based on the reference material poly[2-methoxy-5-(3′,7′-dimethyloctyloxy)-1,4-phenylene vinylene] (MDMO-PPV) with a T_g of 45 °C. The use of the material with higher glass transition temperature resulted in a significant improvement of the thermal stability of the photovoltaic parameters. Furthermore, a systematic transmission electron microscope (TEM) study demonstrates that the better thermal stability of performance coincides with a more stable active layer morphology. Both improvements are attributed to the reduced free movement of the electron donor material (PCBM) within the active layer of the solar cell.     

Environmentally Smart Design: Designing for Social Wellbeing Across the City and in the Workplace

Sustainable need not mean more expensive. Health problems caused by sedentary lifestyles, pollution and injuries from road accidents come at great financial cost — not just for individuals, but also for employers and indeed national governments. Built environments designed to keep people active and away from harm are thus economically beneficial, too. Alisdair McGregor, Ann Marie Aguilar and Victoria Lockhart of Arup cite some of the company's recent schemes in New York and London that have successfully encouraged cycling, strolling and other healthy behaviours, while also avoiding contributing to climate change.     

Steerable Microinvasive Probes for Localized Drug Delivery to Deep Tissue

Enhanced understanding of neuropathologies has created a need for more advanced tools. Current neural implants result in extensive glial scarring and are not able to highly localize drug delivery due to their size. Smaller implants reduce surgical trauma and improve spatial resolution, but such a reduction requires improvements in device design to enable accurate and chronic implantation in subcortical structures. Flexible needle steering techniques offer improved control over implant placement, but often require complex closed‐loop control for accurate implantation. This study reports the development of steerable microinvasive neural implants (S‐MINIs) constructed from borosilicate capillaries (OD = 60 µm, ID = 20 µm) that do not require closed‐loop guidance or guide tubes. S‐MINIs reduce glial scarring 3.5‐fold compared to prior implants. Bevel steered needles are utilized for open‐loop targeting of deep‐brain structures. This study demonstrates a sinusoidal relationship between implant bevel angle and the trajectory radius of curvature both in vitro and ex vivo. This relationship allows for bevel‐tipped capillaries to be steered to a target with an average error of 0.23 mm ± 0.19 without closed‐loop control. Polished microcapillaries present a new microinvasive tool for chronic, predictable targeting of pathophysiological structures without the need for closed‐loop feedback and complex imaging.     

Effect of processing on the antinutrient content of rapeseed

The effects of dry extrusion of mixtures of rapeseed and soya bean on total and individual glucosinolates, selected glucosinolate hydrolysis products, myrosinase, sinapine and tannins have been compared with those of more conventional processing, e.g. lime treatment, micronisation and ammoniation. Extrusion at 150°C effectively inactivated myrosinase but had relatively little effect on glucosinolate content unless chemicals were added before extrusion; the most effective combination, 5% alkali+1% ferrous sulphate, reduced the total glucosinolate content by 80%. Under the latter conditions very high (>30 μmol g^?1 defatted meal) levels of nitriles were produced, leading to the suggestion that nitriles in addition to oxazolidine-2-thione and isothiocyanates be used to monitor the effectiveness of processing techniques. None of the extrusion conditions showed any significant effect on reducing sinapine or tannin contents. In view of the chemical data presented, and the probable adverse effects which the processing conditions selected have on the nutritional value of the processed meal it seems unlikely that extrusion will play a significant role in rapeseed detoxification.     

Reduction of Furan Formation by High-Pressure High-Temperature Treatment of Individual Vegetable Purées

The present study addressed the need for furan mitigation measures at the level of food production, where the effects of extrinsic (process-related) and intrinsic (product-related) properties on furan formation in vegetable-based systems were investigated. For the first time in the literature, the effect of high-pressure high-temperature (HPHT) processing on the formation of furan was demonstrated. HPHT processing was proven to be an interesting alternative for furan reduction in vegetable-based systems, when aiming for sterilization intensities. Following HPHT treatment, the furan concentrations of a wide range of individual vegetable purées dropped to levels close to the analytical limits (1–2 ng/g purée). A higher processing cost might limit the use of HPHT processing to high-value added products, which means that for many other conduction-heated food products, conventional heating would remain the standard technology. As a first step towards control of furan formation in the latter products, a mixed model regression was used to identify the major precursors in vegetable-based systems. Significant correlations were observed for vitamin C and sugars, which were attributed to the efficiency of the conversion and high concentrations, respectively. Next to furan, the HPHT- and thermally treated purées were analyzed for 2- and 3-methylfuran, which are likely to undergo the same metabolic fate as furan. For most of the vegetables tested, the total amount of methylfuran found in the thermally treated purées could not be ignored. Similarly to furan, there was a clear reduction in the concentrations found in the HPHT-treated purées.     

Moisture migration in idealized bilayer systems: relationships among water-associated properties, structure, and texture

The effects of composition and thermal treatment on the water sorption and diffusional properties of idealized protein gels arranged in bilayer configurations were determined; these water binding/migration properties were related to the mechanical characteristics of the gels. Samples were prepared from whey protein concentrate (WPC), they consisted of water:WPC ratios of 1.5 to 5.67, and were thermally set for 20–60 min. Moisture migration rates from samples interfaced with filters were determined, as were moisture sorption capacities of samples immersed in water. The physical properties of the gels were assessed by uniaxial compression and microscopy. Results showed that gel strength and consequent extent of protein interaction—as affected by thermal treatment—controlled the ability of the gel structure to absorb water. Sorption was exponentially correlated with gel modulus and linearly correlated with a function of protein content, heating time, and immersion time. Rates of diffusion from interfaced gels were dependent solely on water content. It was concluded that the degree of protein interaction, whether influenced by concentration or thermal treatment, affected network extensibility and thus the capacity of the gels to act as receptors of moisture. Results have implications for the functionality of shelf-stable sandwiches and other multicomponent foods.     

Chemopreventive Potential of Wild Lowbush Blueberry Fruits in Multiple Stages of Carcinogenesis

ABSTRACT: Wild lowbush blueberry fruit extract was fractionated using vacuum chromatography and analyzed for chemopreventive potential using bioassays that test the ability of compounds to inhibit the initiation, promotion, and progression stages of carcinogenesis. A fraction containing phytosterols was active against the initiation stage (quinone reductase assay). However, more polar compounds were inhibitors of later stages of carcinogenesis; a fraction containing flavan-3-ols and fractions containing mainly anthocyanins, phenolic acids, flavan-3-ols, and some proanthocyanidin dimers demonstrated activity against the promotion stage (cyclooxygenase and ornithine decarboxylase assays, respectively), and a proanthocyanidin-rich fraction demonstrated antiproliferation activity (inhibition of cancerous murine hepatocyte proliferation is associated with the progression stage). These results indicate that lowbush blueberries contain a range of compounds that have bioactivity against multiple stages of carcinogenesis, and different types of phenolic compounds are active at different stages.     

Antioxidant Capacity of Fruit Extracts of Blackberry (Rubus sp.) Produced in Different Climatic Regions

A range of blackberry genotypes harvested in different seasons and regions in Mexico (Michoacan) and in the United States (Pacific Northwest) were collected to determine their antioxidant capacity using oxygen radical absorbance capacity (ORAC) and ferric reducing antioxidant power (FRAP) assays. Total acidity, ascorbic acid, soluble solids, total phenols, and total anthocyanins, as well as the correlation between all these parameters, were determined for all treatments. Total acidity ranged from 4.22% in wild blackberry from Patzcuaro, Mexico, to 1.02% in ‘Evergreen’ from Woodburn, Oreg. These treatments were also the outliers in terms of ascorbic acid content. Cultivar ‘Brazos’ did not exhibit any significant differences in acidity or ascorbic acid as a consequence of the geographic origin or harvest season. The highest concentration of soluble solids was recorded for ‘Evergreen’ from Woodburn and relatively low soluble solids levels were recorded for all the Mexican treatments. Wild blackberry from Patzcuaro exhibited the highest values for ORAC, FRAP, total phenolic and anthocyanin content. Other relatively high antioxidant capacity values were detected for ‘Marion’ and ‘Evergreen’, both produced in Oregon. Different cultivars grown in the same region/season consistently showed differences in antioxidant capacity. There was little effect of harvest season on phenolic levels. We conclude that levels of total acidity, ascorbic acid, soluble solids, antioxidant capacity, and polyphenols mainly depended on the genotype and not on the climate or the season. ORAC and FRAP values were both highly correlated with each other, and with total phenols and anthocyanin content.