In 2006, Resilience Thinking addressed an essential question: As the natural systems that sustain us are subjected to shock after shock, how much can they take and still deliver the services we need ...from them? This idea caught the attention of both the scientific community and the general public. In Resilience Practice, authors Brian Walker and David Salt take the notion of resilience one step further, applying resilience thinking to real-world situations and exploring how systems can be managed to promote and sustain resilience.
Management studies on corporate sustainability practices have grown considerably. The field now has significant knowledge of sustainability issues that are firm and industry focused. However, complex ...ecological problems are increasing, not decreasing. In this paper, we argue that it is time for corporate sustainability scholars to reconsider the ecological and systemic foundations for sustainability, and to integrate our work more closely with the natural sciences. To address this, our paper introduces a new development in the natural sciences – the delineation of nine ‘Planetary Boundaries’ which govern life as we know it. We call for more systemic research that measures the impact of companies on boundary processes that are at, or possibly beyond, three threshold points – climate change, the global nitrogen cycle, and rate of biodiversity loss – and closing in on others. We also discuss practical implications of the Planetary Boundaries framework for corporate sustainability, including governance and institutional challenges.
Chronic excessive activation of glucocorticoid receptors induces obesity, insulin resistance, glucose intolerance, dyslipidaemia and hypertension. Subtle abnormalities of the ...hypothalamic-pituitary-adrenal axis and/or of tissue sensitivity to glucocorticoids are also associated with these cardiovascular risk factors in patients with the metabolic syndrome. Furthermore, glucocorticoids have direct effects on the heart and blood vessels, mediated by both glucocorticoid and mineralocorticoid receptors and modified by local metabolism of glucocorticoids by the 11beta-hydroxysteroid dehydrogenase enzymes. These effects influence vascular function, atherogenesis and vascular remodelling following intra-vascular injury or ischaemia. This article reviews the systemic and cardiovascular effects of glucocorticoids, and the evidence that glucocorticoids not only promote the incidence and progression of atherogenesis but also modify the recovery from occlusive vascular events and intravascular injury. The conclusion is that manipulation of glucocorticoid action within metabolic and cardiovascular tissues may provide novel therapeutic avenues to combat cardiovascular disease.
Based on the clinical features of myeloma and related malignancies of plasma cells, it has been possible to generate a model system of myeloma progression from a normal plasma cell through ...smouldering myeloma to myeloma and then plasma cell leukaemia. Using this model system we can study at which points the genetic alterations identified through whole-tumour molecular analyses function in the initiation and progression of myeloma. Further genetic complexity, such as intraclonal heterogeneity, and insights into the molecular evolution and intraclonal dynamics in this model system are crucial to our understandings of tumour progression, treatment resistance and the use of currently available and future treatments.
Singlet exciton fission in solution Walker, Brian J; Musser, Andrew J; Beljonne, David ...
Nature chemistry,
12/2013, Letnik:
5, Številka:
12
Journal Article
Recenzirano
Odprti dostop
Singlet exciton fission, the spin-conserving process that produces two triplet excited states from one photoexcited singlet state, is a means to circumvent the Shockley-Queisser limit in ...single-junction solar cells. Although the process through which singlet fission occurs is not well characterized, some local order is thought to be necessary for intermolecular coupling. Here, we report a triplet yield of 200% and triplet formation rates approaching the diffusion limit in solutions of bis(triisopropylsilylethynyl (TIPS)) pentacene. We observe a transient bound excimer intermediate, formed by the collision of one photoexcited and one ground-state TIPS-pentacene molecule. The intermediate breaks up when the two triplets separate to each TIPS-pentacene molecule. This efficient system is a model for future singlet-fission materials and for disordered device components that produce cascades of excited states from sunlight.
Myocardial infarction (MI) leads to a multi-phase reparative process at the site of damaged heart that ultimately results in the formation of non-conductive fibrous scar tissue. Despite the ...widespread use of electroconductive biomaterials to increase the physiological relevance of bioengineered cardiac tissues in vitro, there are still several limitations associated with engineering biocompatible scaffolds with appropriate mechanical properties and electroconductivity for cardiac tissue regeneration. Here, we introduce highly adhesive fibrous scaffolds engineered by electrospinning of gelatin methacryloyl (GelMA) followed by the conjugation of a choline-based bio-ionic liquid (Bio-IL) to develop conductive and adhesive cardiopatches. These GelMA/Bio-IL adhesive patches were optimized to exhibit mechanical and conductive properties similar to the native myocardium. Furthermore, the engineered patches strongly adhered to murine myocardium due to the formation of ionic bonding between the Bio-IL and native tissue, eliminating the need for suturing. Co-cultures of primary cardiomyocytes and cardiac fibroblasts grown on GelMA/Bio-IL patches exhibited comparatively better contractile profiles compared to pristine GelMA controls, as demonstrated by over-expression of the gap junction protein connexin 43. These cardiopatches could be used to provide mechanical support and restore electromechanical coupling at the site of MI to minimize cardiac remodeling and preserve normal cardiac function.
Conventional methods to engineer electroconductive hydrogels (ECHs) through the incorporation of conductive nanomaterials and polymers exhibit major technical limitations. These are mainly associated ...with the cytotoxicity, as well as poor solubility, processability, and biodegradability of their components. Here, we describe the engineering of a new class of ECHs through the functionalization of non-conductive polymers with a conductive choline-based bio-ionic liquid (Bio-IL). Bio-IL conjugated hydrogels exhibited a wide range of highly tunable physical properties, remarkable in vitro and in vivo biocompatibility, and high electrical conductivity without the need for additional conductive components. The engineered hydrogels could support the growth and function of primary cardiomyocytes in both two dimentinal (2D) and three dimensional (3D) cultures in vitro. Furthermore, they were shown to be efficiently biodegraded and possess low immunogenicity when implanted subcutaneously in rats. Taken together, our results suggest that Bio-IL conjugated hydrogels could be implemented and readily tailored to different biomedical and tissue engineering applications.
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Electroconductive hydrogels (ECHs) are highly hydrated three-dimensional (3D) networks generated through the incorporation of conductive polymers, nanoparticles, and other conductive ...materials into polymeric hydrogels. ECHs combine several advantageous properties of inherently conductive materials with the highly tunable physical and biochemical properties of hydrogels. Recently, the development of biocompatible ECHs has been investigated for various biomedical applications, such as tissue engineering, drug delivery, biosensors, flexible electronics, and other implantable medical devices. Several methods for the synthesis of ECHs have been reported, which include the incorporation of electrically conductive materials such as gold and silver nanoparticles, graphene, and carbon nanotubes, as well as various conductive polymers (CPs), such as polyaniline, polypyrrole, and poly(3,4-ethylenedioxyythiophene) into hydrogel networks. These electroconductive composite hydrogels can be used as scaffolds with high swellability, tunable mechanical properties, and the capability to support cell growth both in vitro and in vivo. Furthermore, recent advancements in microfabrication techniques such as 3D bioprinting, micropatterning, and electrospinning have led to the development of ECHs with biomimetic microarchitectures that reproduce the characteristics of the native extracellular matrix (ECM). The combination of sophisticated synthesis chemistries and modern microfabrication techniques have led to engineer smart ECHs with advanced architectures, geometries, and functionalities that are being increasingly used in drug delivery systems, biosensors, tissue engineering, and soft electronics. In this review, we will summarize different strategies to synthesize conductive biomaterials. We will also discuss the advanced microfabrication techniques used to fabricate ECHs with complex 3D architectures, as well as various biomedical applications of microfabricated ECHs.
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