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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.

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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.

in Wiley InterScience (www.interscience.wiley.com).Solid-solid reactions are important in many chemical and metallurgical process industries, as also in the semiconductor and electrochemical materials industries. In comparison to their fluid counterparts, these systems are difficult to model with any degree of rigour, but models derived from the fluid-solid literature have often been used with success to interpret the data. There are lacunae, however, and our previous work 1 has shown the inadequacy of the conventional models when reactions take place through a network of some complexity. In that work, the conversion of alumina and calcia to C 3 A was shown to be a series network, with C 12 A 7 being the (stable) reaction intermediate. The second reaction step of that network is studied here, namely the conversion of C 12 A 7 to C 3 A by reaction with calcia. It has been shown that this reaction takes place in a single step. While conventional wisdom treats such reactions as taking place invariably at a (moving) reaction front, it has been shown that a proper interpretation of data requires cognizance of a volume reaction component, which may, under conditions of severe diffusion limitations, be approximated well by a front reaction.

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Crystalline materials are of crucial importance to the pharmaceutical industry, as a large number of APIs are formulated in crystalline form, occasionally in the presence of crystalline excipients. Owing to their multifaceted character, crystals were found to have strongly anisotropic properties. In fact, anisotropic properties were found to be quite important for a number of processes including milling, granulation and tableting. An understanding of crystal anisotropy and an ability to control and predict crystal anisotropy are mostly subjects of interest for researchers. A number of studies dealing with the aforementioned phenomena are grounded on over-simplistic assumptions, neglecting key attributes of crystalline materials, most importantly the anisotropic nature of a number of their properties. Moreover, concepts such as the influence of interfacial phenomena in the behaviour of crystalline materials during their growth and in vivo, are still poorly understood. The review aims to address concepts from a molecular perspective, focusing on crystal growth and dissolution. It begins with a brief outline of fundamental concepts of intermolecular and interfacial phenomena. The second part discusses their relevance to the field of pharmaceutical crystal growth and dissolution. Particular emphasis is given to works dealing with mechanistic understandings of the influence of solvents and additives on crystal habit. Furthermore, comments and perspectives, highlighting future directions for the implementation of fundamental concepts of interfacial phenomena in the rational understanding of crystal growth and dissolution processes, have been provided.