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Metal fluorides/oxides (MF x /M x O y ) are promising electrodes for lithium-ion batteries that operate through conversion reactions. These reactions are associated with much higher energy densities than intercalation reactions. The fluorides/oxides also exhibit additional reversible capacity beyond their theoretical capacity through mechanisms that are still poorly understood, in part owing to the difficulty in characterizing structure at the nanoscale, particularly at buried interfaces. This study employs high-resolution multinuclear/multidimensional solid-state NMR techniques, with in situ synchrotron-based techniques, to study the prototype conversion material RuO 2 . The experiments, together with theoretical calculations, show that a major contribution to the extra capacity in this system is due to the generation of LiOH and its subsequent reversible reaction with Li to form Li 2 O and LiH. The research demonstrates a protocol for studying the structure and spatial proximities of nanostructures formed in this system, including the amorphous solid electrolyte interphase that grows on battery electrodes. Metal fluorides/oxides are promising electrodes for lithium-ion batteries, but the mechanism by which they exhibit additional reversible capacity is still not well understood. By using high-resolution solid-state NMR techniques it is shown that extra capacity in this RuO 2 system is due to the generation of LiOH and its subsequent reversible reaction with Li to form Li 2 O and LiH.

Nature has evolved efficient strategies to synthesize complex mineralized structures that exhibit exceptional damage tolerance. One such example is found in the hypermineralized hammer-like dactyl clubs of the stomatopods, a group of highly aggressive marine crustaceans. The dactyl clubs from one species, Odontodactylus scyllarus, exhibit an impressive set of characteristics adapted for surviving high-velocity impacts on the heavily mineralized prey on which they feed. Consisting of a multiphase composite of oriented crystalline hydroxyapatite and amorphous calcium phosphate and carbonate, in conjunction with a highly expanded helicoidal organization of the fibrillar chitinous organic matrix, these structures display several effective lines of defense against catastrophic failure during repetitive high-energy loading events.

The structural biology program at the National Synchrotron Light Source II presents a coordinated set of instruments, software and research opportunities for the interested user. We describe in some detail the research capabilities enabled by the Center for BioMolecular Structure. The evolution of the resources is described in detail, considering three major themes: automation, micro‐focusing and computation prediction. We describe the structural biology resources available at the National Synchrotron Light Source II at Brookhaven National Laboratory and ponder the future for automated experiments, micro‐focusing crystallography and structure prediction to inform structural biology studies.

The intercalation compounds with various electrochemically active or inactive elements in the layered structure have been the subject of increasing interest due to their high capacities, good reversibility, simple structures, and ease of synthesis. However, their reversible intercalation/deintercalation redox chemistries in previous compounds involve a single cationic redox reaction or a cumulative cationic and anionic redox reaction. Here we report an anionic redox chemistry and structural stabilization of layered sodium chromium sulfide. It was discovered that the sulfur in sodium chromium sulfide is electrochemically active, undergoing oxidation/reduction rather than chromium. Significantly, sodium ions can successfully move out and into without changing its lattice parameter c , which is explained in terms of the occurrence of chromium/sodium vacancy antisite during desodiation and sodiation processes. Our present work not only enriches the electrochemistry of layered intercalation compounds, but also extends the scope of investigation on high-capacity electrodes. The rational design of intercalation electrodes is largely confined to the optimization of redox chemistry of transition metals and oxygen. Here, the authors report the single anionic redox process in NaCrS 2 where it is sulfur rather than chromium that works as the electrochemical active species.

We report that alkali ions (sodium or potassium) added in small amounts activate platinum adsorbed on alumina or silica for the low-temperature water-gas shift (WGS) reaction (H₂O + CO [rightward arrow] H₂ + CO₂) used for producing H₂. The alkali ion-associated surface OH groups are activated by CO at low temperatures (approximately 100°C) in the presence of atomically dispersed platinum. Both experimental evidence and density functional theory calculations suggest that a partially oxidized Pt-alkali-Ox(OH)y species is the active site for the low-temperature Pt-catalyzed WGS reaction. These findings are useful for the design of highly active and stable WGS catalysts that contain only trace amounts of a precious metal without the need for a reducible oxide support such as ceria.

A new form of boron Boron is an element of fascinating chemical complexity. This arises from frustration: situated between metals and insulators in the periodic table, boron has only three valence electrons that could in principle favour metallicity, yet they are sufficiently localized to give rise to an insulating state. This delicately balanced electronic structure is easily modified by pressure, temperature and impurities, making it difficult to establish boron's structure and properties. Oganov et al . have now explored the high-pressure behaviour of boron and uncovered a previously unknown ionic phase consisting of negatively charged icosahedral B 12 clusters and positively charged B 2 pairs. The ionicity of the new phase strongly affects many of its properties, and arises from the different electronic properties of the B 12 clusters and B 2 pairs and the resultant charge transfer between them. This paper has explored the high-pressure behaviour of boron and uncovered a new phase that consists of negatively charged icosahedral B 12 clusters and positively charged B 2 pairs. The ionicity of the new phase strongly affects many of its properties, and arises from the different electronic properties of the B 12 clusters and B 2 pairs and the resultant charge transfer between them. Boron is an element of fascinating chemical complexity. Controversies have shrouded this element since its discovery was announced in 1808: the new ‘element’ turned out to be a compound containing less than 60–70% of boron, and it was not until 1909 that 99% pure boron was obtained 1 . And although we now know of at least 16 polymorphs 2 , the stable phase of boron is not yet experimentally established even at ambient conditions 3 . Boron’s complexities arise from frustration: situated between metals and insulators in the periodic table, boron has only three valence electrons, which would favour metallicity, but they are sufficiently localized that insulating states emerge. However, this subtle balance between metallic and insulating states is easily shifted by pressure, temperature and impurities. Here we report the results of high-pressure experiments and ab initio evolutionary crystal structure predictions 4 , 5 that explore the structural stability of boron under pressure and, strikingly, reveal a partially ionic high-pressure boron phase. This new phase is stable between 19 and 89 GPa, can be quenched to ambient conditions, and has a hitherto unknown structure (space group Pnnm , 28 atoms in the unit cell) consisting of icosahedral B 12 clusters and B 2 pairs in a NaCl-type arrangement. We find that the ionicity of the phase affects its electronic bandgap, infrared adsorption and dielectric constants, and that it arises from the different electronic properties of the B 2 pairs and B 12 clusters and the resultant charge transfer between them.

Mutations in the enzyme cytosolic isocitrate dehydrogenase 1 (IDH1) are a common feature of a major subset of primary human brain cancers. These mutations occur at a single amino acid residue of the IDH1 active site, resulting in loss of the enzyme’s ability to catalyse conversion of isocitrate to α-ketoglutarate. However, only a single copy of the gene is mutated in tumours, raising the possibility that the mutations do not result in a simple loss of function. Here we show that cancer-associated IDH1 mutations result in a new ability of the enzyme to catalyse the NADPH-dependent reduction of α-ketoglutarate to R (-)-2-hydroxyglutarate (2HG). Structural studies demonstrate that when arginine 132 is mutated to histidine, residues in the active site are shifted to produce structural changes consistent with reduced oxidative decarboxylation of isocitrate and acquisition of the ability to convert α-ketoglutarate to 2HG. Excess accumulation of 2HG has been shown to lead to an elevated risk of malignant brain tumours in patients with inborn errors of 2HG metabolism. Similarly, in human malignant gliomas harbouring IDH1 mutations, we find markedly elevated levels of 2HG. These data demonstrate that the IDH1 mutations result in production of the onco-metabolite 2HG, and indicate that the excess 2HG which accumulates in vivo contributes to the formation and malignant progression of gliomas. Role of 2-hydroxyglutarate in cancer A high percentage of human glioblastomas has been found to harbour mutations in the metabolic enzyme cytosolic isocitrate dehydrogenase 1 (IDH1). The predominant R132H mutation is now shown to act as a gain-of-function mutation, enabling IDH1 to convert α-ketoglutarate to 2-hydroxyglutarate (2-HG). Human glioblastoma samples with IDH1 mutations indeed contain elevated levels of 2-HG. Future work will be directed at understanding the mechanisms by which 2-HG can contribute to tumorigenesis. Mutations in the enzyme cytosolic isocitrate dehydrogenase 1 (IDH1) are commonly found in glioblastomas, a major subset of primary human brain cancers. However, only a single copy of the gene is mutated, suggesting that the mutation does not result in a simple loss of function. Here, IDH1 mutations are shown to act in a gain-of-function manner, resulting in a new ability of the enzyme to catalyse α-ketoglutarate to R (-)-2-hydroxyglutarate, an onco-metabolite.

The development of a direct ethanol fuel cell has been hampered by ethanol’s inefficient and slow oxidation. A ternary electrocatalyst consisting of platinum and rhodium deposited on carbon-supported tin dioxide nanoparticles is now shown to oxidize ethanol to carbon dioxide with high efficiency by splitting C–C bonds at room temperature. Ethanol, with its high energy density, likely production from renewable sources and ease of storage and transportation, is almost the ideal combustible for fuel cells wherein its chemical energy can be converted directly into electrical energy. However, commercialization of direct ethanol fuel cells has been impeded by ethanol’s slow, inefficient oxidation even at the best electrocatalysts 1 , 2 . We synthesized a ternary PtRhSnO 2 /C electrocatalyst by depositing platinum and rhodium atoms on carbon-supported tin dioxide nanoparticles that is capable of oxidizing ethanol with high efficiency and holds great promise for resolving the impediments to developing practical direct ethanol fuel cells. This electrocatalyst effectively splits the C–C bond in ethanol at room temperature in acid solutions, facilitating its oxidation at low potentials to CO 2 , which has not been achieved with existing catalysts. Our experiments and density functional theory calculations indicate that the electrocatalyst’s activity is due to the specific property of each of its constituents, induced by their interactions. These findings help explain the high activity of Pt–Ru for methanol oxidation and the lack of it for ethanol oxidation, and point to the way to accomplishing the C–C bond splitting in other catalytic processes.

Owing to the worldwide abundance and low-cost of Na, room-temperature Na-ion batteries are emerging as attractive energy storage systems for large- scale grids. Increasing the Na content in cathode materials is one of the effective ways to achieve high energy density. Prussian blue and its analogues （PBAs） are promising Na-rich cathode materials since they can theoretically store two Na＋ ions per formula unit. However, increasing the Na content in PBAs cathode materials remains a major challenge. Here we show that sodium iron hexacyanoferrate with high Na content can be obtained by simply controlling the reducing agent and reaction atmosphere during synthesis. The Na content can reach as high as 1.63 per formula, which is the highest value for sodium iron hexacyanoferrate. This Na-rich sodium iron hexacyanoferrate demonstrates a high specific capacity of 150 mAh·g^-1 and remarkable cycling performance with 90% capacity retention after 200 cycles. Furthermore, the Na intercalation/ de-intercalation mechanism has been systematically studied by in situ Raman spectroscopy, X-ray diffraction and X-ray absorption spectroscopy analysis for the first time. The Na-rich sodium iron hexacyanoferrate can function as a plenteous Na reservoir and has great potential as a cathode material for practical Na-ion batteries.

Designer DNA crystals Creating a macroscopic object, such as a crystal, with the microscopic molecular structure desired is a challenge. One promising approach is the use of macromolecules with robust three-dimensional motifs and sticky ends so that, by attaching to one another, they can form a periodic arrangement that can be investigated by crystallographic techniques. Zheng et al . use DNA for this purpose, arranged in a structural motif called a tensegrity triangle, and can grow crystals of the order of 200 micrometres in size, in which the positions of the atoms can be determined with a precision of 4 Å. The highly specific interaction between complementary DNA strands makes it possible to realize the desired and designed structure for the unit cell of the crystal. The latter also exhibits periodic holes, which could potentially be used to host biomolecules in a three-dimensional periodic arrangement, making it possible to determine their structure even if they do not crystallize on their own. Although we live in a macroscopic three-dimensional (3D) world, our best description of the structure of matter is at the atomic and molecular scale. Reconciling these two scales with atomic precision requires high spatial control of the 3D structure of matter, with the simplest practical route to achieving this being to form a crystalline arrangement by self-assembly. Here, the crystal structure of a designed, self-assembled 3D crystal based on the DNA tensegrity triangle is reported. We live in a macroscopic three-dimensional (3D) world, but our best description of the structure of matter is at the atomic and molecular scale. Understanding the relationship between the two scales requires a bridge from the molecular world to the macroscopic world. Connecting these two domains with atomic precision is a central goal of the natural sciences, but it requires high spatial control of the 3D structure of matter 1 . The simplest practical route to producing precisely designed 3D macroscopic objects is to form a crystalline arrangement by self-assembly, because such a periodic array has only conceptually simple requirements: a motif that has a robust 3D structure, dominant affinity interactions between parts of the motif when it self-associates, and predictable structures for these affinity interactions. Fulfilling these three criteria to produce a 3D periodic system is not easy, but should readily be achieved with well-structured branched DNA motifs tailed by sticky ends 2 . Complementary sticky ends associate with each other preferentially and assume the well-known B-DNA structure when they do so 3 ; the helically repeating nature of DNA facilitates the construction of a periodic array. It is essential that the directions of propagation associated with the sticky ends do not share the same plane, but extend to form a 3D arrangement of matter. Here we report the crystal structure at 4 Å resolution of a designed, self-assembled, 3D crystal based on the DNA tensegrity triangle 4 . The data demonstrate clearly that it is possible to design and self-assemble a well-ordered macromolecular 3D crystalline lattice with precise control.