Tunable biohybrid hydrogels from coacervation of hyaluronic acid and PEO‐based block copolymers

Accurately tuning the macroscopic properties of biopolymer‐based hydrogels remains challenging due to the ill‐defined molecular architecture of the natural building blocks. Here, we report a biohybrid coacervate hydrogel, combining the biocompatibility and biodegradability of naturally occurring hyaluronic acid (HA) with the tunability of a synthetic polyethylene oxide (PEO) ‐based ABA‐triblock copolymer. Coacervation of the cationic ammonium or guanidinium‐functionalized copolymer A‐blocks with the anionic HA leads to hydrogel formation. Both mechanical properties and water content of the self‐healing hydrogels can be controlled independently by altering the copolymer structure. By controlling the strength of the interaction between the polymer network and small‐molecule cargo, both release rate and maximum release are controlled. Finally, we show that coacervation of HA and the triblock copolymer leads to increased biostability upon exposure to hyaluronidase. We envision that noncovalent crosslinking of HA hydrogels through coacervation is an attractive strategy for the facile synthesis of tunable hydrogels for biomedical applications

The market impacts of shortening feed supply chains in Europe

Recently, consumers’ awareness regarding food production has increased, leading to a growing focus on shorter food supply chains and regional or local food systems. In the livestock sector, these developments are closely related to a regionalization of feed production. At the same time, a low self-sufficiency rate in protein feed is being reported for many European countries. In this paper, we analyze market impacts resulting from a complete switch to regionally produced feed in the European livestock sector. We simulate a shortening of feed supply chains in European livestock production using a large-scale agricultural sector model. Livestock production was restricted to feed that can be produced within the same EU member state. Our work represents a first step towards a simulation of regional or local food systems. The results reveal large increases in the prices of livestock products in Europe due to the shortening of feed supply chains. This is a result of a significant increase in livestock production costs. The ability to supply livestock products with regionally produced feed in the EU would be improved through a reduced consumption of livestock products

Shining new light on mammalian diving physiology using wearable near-infrared spectroscopy

Investigation of marine mammal dive-by-dive blood distribution and oxygenation has been limited by a lack of non-invasive technology for use in freely diving animals. Here, we developed a non-invasive near-infrared spectroscopy (NIRS) device to measure relative changes in blood volume and haemoglobin oxygenation continuously in the blubber and brain of voluntarily diving harbour seals. Our results show that seals routinely exhibit preparatory peripheral vasoconstriction accompanied by increased cerebral blood volume approximately 15 s before submersion. These anticipatory adjustments confirm that blood redistribution in seals is under some degree of cognitive control that precedes the mammalian dive response. Seals also routinely increase cerebral oxygenation at a consistent time during each dive, despite a lack of access to ambient air. We suggest that this frequent and reproducible reoxygenation pattern, without access to ambient air, is underpinned by previously unrecognised changes in cerebral drainage. The ability to track blood volume and oxygenation in different tissues using NIRS will facilitate a more accurate understanding of physiological plasticity in diving animals in an increasingly disturbed and exploited environment

Re-building food systems: embedding assemblages, infrastructures and reflexive governance for food systems transformations in Europe.

This introductory paper to the special section argues that there are now significant signs and opportunities of real transformations of food systems in which to create new synergies between sustainable consumption and production, and which can potentially shift agri-food into more secure and sustainable sets of conditions. With reference to empirical research in Europe, the paper assesses the transformative potential of a series of mobilisations associated with: sustainable city networks, community cooperative and share schemes, and regional agro-ecological, seed, plant and livestock schemes. Not denying the significance of countervailing intensive and industrialised food regimes, the paper introduces a set of conceptual building blocks, which emerge as ways of both assessing and progressing these mobilisations. It is argued that to succeed they need elements of at least four conditions: (i) a significant and lasting reconfiguration of governance and regulatory conditions; (ii) an ability and capacity to both promote sustainable production and food access and diet through the development of new assemblages; (iii) develop new social and physical and distributional infrastructures which can scale out their impacts; and (iv) be embedded in a more reflexive governance context which is both supportive and spatially sensitive to their diverse conditions. The succeeding papers in the special issue will deal with these transformatory factors in comparative and empirical depth. Here we outline how and why such a ‘re-building’ has become so critical at this current juncture

CQG algebras: a direct algebraic approach to compact quantum groups

The purely algebraic notion of CQG algebra (algebra of functions on a compact quantum group) is defined. In a straightforward algebraic manner, the Peter-Weyl theorem for CQG algebras and the existence of a unique positive definite Haar functional on any CQG algebra are established. It is shown that a CQG algebra can be naturally completed to a $C^\ast$-algebra. The relations between our approach and several other approaches to compact quantum groups are discussed.Comment: 14 pp., Plain TeX, accepted by Lett. Math. Phy

Supergravity description of spacetime instantons

We present and discuss BPS instanton solutions that appear in type II string theory compactifications on Calabi-Yau threefolds. From an effective action point of view these arise as finite action solutions of the Euclidean equations of motion in four-dimensional N=2 supergravity coupled to tensor multiplets. As a solution generating technique we make use of the c-map, which produces instanton solutions from either Euclidean black holes or from Taub-NUT like geometries.Comment: 35 pages, some clarifications adde