Lighting the Path: Light Delivery Strategies to Activate Photoresponsive Biomaterials In Vivo

Photoresponsive biomaterials are experiencing a transition from in vitro models to in vivo demonstrations that point toward clinical translation. Dynamic hydrogels for cell encapsulation, light-responsive carriers for controlled drug delivery, and nanomaterials containing photosensitizers for photodynamic therapy are relevant examples. Nonetheless, the step to the clinic largely depends on their combination with technologies to bring light into the body. This review highlights the challenge of photoactivation in vivo, and presents strategies for light management that can be adopted for this purpose. The authors’ focus is on technologies that are materials-driven, particularly upconversion nanoparticles that assist in “direct path” light delivery through tissue, and optical waveguides that “clear the path” between external light source and in vivo target. The authors’ intention is to assist the photoresponsive biomaterials community transition toward medical technologies by presenting light delivery concepts that can be integrated with the photoresponsive targets. The authors also aim to stimulate further innovation in materials-based light delivery platforms by highlighting needs and opportunities for in vivo photoactivation of biomaterials.     

Geochemical Fractionation of Stream Sediments Impacted by Pb-Zn Mining Wastes: Missouri,USA

Mine Water and the Environment - Stream sediments affected by historic mining in Aurora, Missouri, were digested via sequential extraction to determine the amount of Zn, Pb, and Cd bound to each of...     

The Spatial Patterning of Alcohol Outlets in Post-Disaster Christchurch,New Zealand: Practical and Policy Implications

Natural disasters greatly impact the environment of affected societies with often unknown consequences. In this study we examine the impact that the Canterbury Earthquakes of 2010–2011 had on the distribution of alcohol outlets in Christchurch, New Zealand. Specifically, we compare the distribution of both on-site and off-site alcohol outlets pre- (December 2009) and post-earthquake (December 2014) and use spatial regression models to identify whether any neighbourhood-level factors predict the observed redistributions. Overall, the number of alcohol outlets decreased by almost 13% after the Canterbury Earthquakes. However, we found a moderate increase in the clustering of both outlet types of outlets in the post-quake period. Increases in rates of both on-site and off-site alcohol outlets in neighbourhoods were positively associated with the percentage of residents who resided in their neighbourhood < 5 years and with neighbourhood crime rate change, while negative associations were found with percentage population aged between 15 and 29 years. The results suggest that the changing spatial distribution of alcohol outlets in Christchurch was not random but driven, in part, by the emergent demographic composition of neighbourhoods. The significant practical and policy implications of a redistribution of alcohol outlets are outlined providing a tangible link between empirical research and practice in an urban environment plagued with post-disaster spatial and social uncertainties.     

A framework for governance of public green spaces in cities

Public authorities that seek to transfer the cost of managing green spaces to the private sector face apprehension about the extent of community input in managing of public green spaces in cities. In practice, the governance arrangements for managing public green spaces are neither a purely private or public sector responsibility. They are part of complex and contested governance schemas that involve multiple stakeholder groups with varying interests and responsibilities. This paper proposes a simple framework to support different modes of governance appropriate for the management of public green spaces in cities. The framework classifies stakeholders’ desires for engagement based on ecosystem service characteristics defined on a spectrum of excludability and rivalry. The framework is applied to case studies in Australia and Canada. Finally, we discuss the new insights for governance arrangements for public green space management in cities.     

Quantifying adherence of oxide scales on steels exposed to high temperature and pressure steam

Oxide scale exfoliation is a major concern in fossil fuel power generation because it can cause tube blockages and erode valves and steam turbine components downstream. There is still considerable scientific and commercial interest to improve the mechanistic understanding of oxide failures by developing models to predict exfoliation and the extent of tube blockage as a function of operating conditions and component geometries. Tensile testing inside a scanning electron microscope was conducted on ferritic–martensitic and austenitic steel specimens with the steam side (Fe,Cr)-rich oxides grown after exposures for up to 1000 h in steam with ~100 ppb O₂ at 276 bar and 550°C. Multiple oxide layer cracks and delamination events were observed and analyzed in detail during the tests. Results from the testing agreed well with earlier observations that had identified the failure location at the outer–inner oxide layer for all tested materials. Calculated adhesion energies identified the outer–inner oxide interface of alloy 347HFG as the weakest interface.     

Incorporation of polyfluorenes into poly(lactic acid) films for sensor and optoelectronics applications

Films of neat and plasticized biodegradable poly(lactic acid) (PLA) matrices containing anionic conjugated polyelectrolytes, poly[9,9‐bis(4‐phenoxybutylsulfonate)]fluorene‐2,7‐diyl‐alt‐arylenes, with 1,4‐phenylene and 4,4″‐p‐terphenylene, respectively, as arylene groups or a neutral poly(9,9‐dialkylfluorene) for comparison were prepared by solution casting. These films were characterized using differential scanning calorimetry, thermogravimetry, scanning electron microscopy and fluorescence spectroscopy. In addition, the effects of plasticizer on the thermal properties and the oxygen permeability of the PLA films were measured through the oxygen transmission rate. Results show that it is possible to obtain thin, optically transparent and luminescent films with potential in oxygen sensing, exhibiting good thermal and photochemical stability. At high polyelectrolyte content, evidence is found for phase separation and aggregate formation and it is no longer possible to obtain completely homogeneous films. The possibility of incorporating the cationic metal complex tris(2,2′‐bipyridyl)ruthenium(II) into plasticized PLA films containing conjugated polyelectrolytes for dual‐wavelength ratiometric luminescence sensing is also discussed. Copyright © 2012 Society of Chemical Industry     

Temporal variation of erythemally effective UVB/UVA ratio at Chilton, UK

An analysis of the temporal variation in the erythemally weighted UVB/UVA irradiance ratio using spectral data collected from a monitoring site in Chilton, UK (51°N) for the 5-y period from 2004 to 2008 is presented. The variation in the diurnal ratio was found to be bell-shaped, with minima on average 1 h after sunrise and before sunset. The minima were found to be indicative of the point at which UVB becomes undetectable by the spectroradiometer and therefore the outer boundary of useful data. A potential flaw entailed in the erythemal weighting of low-level spectral UV data is described. The peak daily ratio value was found to have a bell-shaped distribution over the course of a year with a maximum in July rather than at the summer solstice-a result explained by the ozone cycle. The peak daily ratio was found to vary by a factor of 4 over the course of the year; this range of variation was also found to occur over a single day in the summer.