Many leaves have two layers of photosynthetic tissue: the palisade and spongy mesophyll. The latter is not well characterized and often treated as a random assemblage of irregularly shaped cells. These results show that simple principles may govern the organization and scaling of the spongy mesophyll in many plants and demonstrate the presence of structural patterns associated with leaf function. Read more »
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Dramatic Conformer-Dependent Reactivity of the Acetaldehyde Oxide Criegee Intermediate with Dimethylamine Via a 1,2-Insertion Mechanism
Acetaldehyde-oxide (CH3CHOO) is an atmospherically pertinent reactive intermediate that exists in syn (right) and anti (left) conformational forms. Experiment and theory reveal that the reaction of anti with dimethylamine is several orders of magnitude faster than that of syn with dimethylamine, despite both reactions being energetically downhill. Read more »
A {Ni12}-Wheel-Based Metal–Organic Framework for Coordinative Binding of Sulphur Dioxide and Nitrogen Dioxide
SO2 and NO2 are important air pollutants, and understanding the mechanism of capture materials drives the development of new clean-up technologies. In situ synchrotron x-ray crystallographic and spectroscopic experiments were used to establish a detailed molecular mechanism consisting of reversible coordination of SO2 and NO2 at the six open NiII sites on the unprecedented {Ni12}-wheel of a robust metal–organic framework material at crystallographic resolution. Read more »
Hardening Effects in Superhard Transition-Metal Borides
Novel superhard materials with exciting potential for applications in cutting tools and abrasives can be designed by combining incompressible transition metals with boron to create phases like WB4, pictured here. Diamond-cell-based high-pressure radial diffraction enables the direct study of lattice specific mechanisms for hardening. Read more »
Synergistic Engineering of Side Chains and Backbone Regioregularity of Polymer Acceptors for High-Performance All-Polymer Solar Cells with 15.1% Efficiency
Researchers developed a series of polymer acceptors with controlled backbone regioregularities and side chain structures. All-polymer solar cells based on a RRg-C20 acceptor which has a regioregular backbone and optimal side chain length achieve a high power conversion efficiency of 15.12%, attributed to high electron mobility and optimal blend morphology. Read more »
Atomic-Scale Insights into Nickel Exsolution on LaNiO3 Catalysts via In Situ Electron Microscopy
In situ electron microscopy provides atomic-scale insight into the dynamic structure evolution of LaNiO3 perovskite during vacuum heating. This research established a sequential two-step process in the decomposition of LaNiO3 and gives evidence of the diffusion pathway for the lattice oxygen released during the perovskite decomposition. Read more »
Synthesis of new two-dimensional titanium carbonitride Ti2C0.5N0.5Tx MXene and its performance as an electrode material for sodium-ion battery
Researchers report on the synthesis and characterization of a new 2D carbonitride MXene, Ti2C0.5N0.5. They explore the performance of this new MXene as electrode materials for sodium-ion batteries (SIBs). It outperformed its carbide counterpart (i.e., Ti2C) and all the other reports for multilayer MXenes in SIBs, and it showed a stable electrochemical performance over 500 cycles. Read more »
The three-dimensional construction of leaves is coordinated with water use efficiency in conifers
3D anatomical views of conifer leaves with diverse morphologies, generated using synchrotron microCT imaging (colors show different segmented tissues). Top–bottom: Pinus monticola, P. pungens, and Wollemia nobilis. Image courtesy of Santiago Trueba. Read more »
Nanoscale Confinement of Photo-Injected Electrons at Hybrid Interfaces
Picosecond time-resolved x-ray photoemission spectroscopy provides real-time electron distributions of donors and acceptors in a prototypical bipyridyl-ZnO hybrid light harvesting system. The measurements show that photo-injected electrons remain localized within the defect-rich surface region of the nanoporous ZnO substrate, revealing a challenge for the extraction of free charge carriers. Read more »
Direct Observation of Surface-Bound Intermediates During Methanol Oxidation on Platinum Under Alkaline Conditions
A comprehensive mechanism for the methanol oxidation reaction (MOR) in alkaline media is presented, and it is shown that the MOR proceeds via two different pathways (via COad or H3C–Oad intermediates). The latter dominates the overall MOR current, suggesting that the H3C–Oad oxidation could be a viable pathway to accelerate the MOR in alkaline systems. Read more »
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