Atmospheric
particulate matter (PM) has the potential to diminish
solar energy production by direct and indirect radiative forcing as
well as by being deposited on solar panel surfaces, thereby reducing
solar energy transmittance to photovoltaics. Worldwide solar energy
production is expected to increase more rapidly than any other energy
source into the middle of this century, especially in regions that
experience high levels of dust and/or anthropogenic particulate pollutants,
including large areas of India, China, and the Arabian Peninsula.
Here we combine field measurements and global modeling to estimate
the influence of dust and PM related to anthropogenic sources (e.g.,
fossil and biomass fuel combustion) on solar electricity generation.
Results indicate that solar energy production is currently reduced
by ∼17–25% across these regions, with roughly equal
contributions from ambient PM and PM deposited on photovoltaic surfaces.
Reductions due to dust and anthropogenic PM are comparable in northern
India, whereas over eastern China, anthropogenic PM dominates. On
the basis of current solar generation capacity, PM is responsible
for ∼1 and ∼11 GW of solar power reduction in India
and China, respectively, underscoring the large role that PM plays
in reducing solar power generation output.
DNA-based
nanostructures have emerged as a versatile component
for nanoscale construction of soft materials. Multiple structural,
functional properties and versatility in conjugation with other biomolecules
made DNA the material of choice to use in various biomedical applications.
DNA-based hydrogels significantly attracted attention in recent years
owing to their properties and applications in biosensing, bioimaging,
and therapeutics. Here, we summarize the recent advances in the area
of DNA hydrogels where these are used either as structural material
or as functional entities to make hybrid constructs with various biomedical
applications. Multiple synthetic routes for constructing DNA hydrogels
are summarized first, where the structural motifs and spatial arrangements
are considered for the classification of DNA materials. We then present
the characterization and properties of DNA hydrogels using multiple
imaging and biophysical techniques. Further, different biomedical
applications of DNA hydrogels are presented such as biosensing, bioimaging,
and targeted drug delivery and as scaffolds to program cellular systems.
Last, we discuss the vision and potential of DNA based hydrogels as
an emerging class of therapeutically important devices for theragnostic
and other biological applications.
in Wiley InterScience (www.interscience.wiley.com).Tricalcium aluminate is an important constituent of Portland cement, apart from having other applications. It is formed by a solid-solid reaction between CaO and Al 2 O 3 , themselves formed by solid-state decompositions of CaCO 3 and Al(OH) 3 , respectively. There is no unanimity in the literature about the kinetic and mechanistic aspects of its formation. In this article we report experimental studies on this system with a view to identifying the reasons for these discrepancies and to present reproducible kinetic information under a well-defined set of conditions. The experiments cover a temperature range of 1100-13008C and use CaCO 3 and Al(OH) 3 gel powder as the starting materials. Reactions have been carried under a variety of conditions in an attempt to identify the experimental variables that influence the observed kinetics. The results show that mechanochemical activation can profoundly influence rates. The most reproducible and consistent results were obtained under conditions of good interparticle contact, with controlled pretreatment to define the physical structure of the reacting entity. Further, the results throw light on the sequential nature of the reaction and establish the nature of the intermediate phase. The data, when interpreted in the traditional manner, show consistent trends with the literature, but the deficiencies of such interpretation have been analyzed and the need for new models has been advanced. Because solid-solid reactions are generally less well understood than their fluid counterparts, our results argue in favor of a comprehensive modeling framework for such series reaction networks in the solid phase.
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