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The carbon content of Earth and its core 期刊论文
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 2020, 117 (16) : 8743-8749
作者:  Fischer, Rebecca A.;  Cottrell, Elizabeth;  Hauri, Erik;  Lee, Kanani K. M.;  Le Voyer, Marion
收藏  |  浏览/下载:18/0  |  提交时间:2020/05/13
carbon  metal-silicate partitioning  core formation  light elements  
Short-range order and its impact on the CrCoNi medium-entropy alloy 期刊论文
NATURE, 2020, 581 (7808) : 283-+
作者:  Tan, Hwei-Ee;  Sisti, Alexander C.;  Jin, Hao;  Vignovich, Martin;  Villavicencio, Miguel;  Tsang, Katherine S.;  Goffer, Yossef;  Zuker, Charles S.
收藏  |  浏览/下载:20/0  |  提交时间:2020/07/03

Traditional metallic alloys are mixtures of elements in which the atoms of minority species tend to be distributed randomly if they are below their solubility limit, or to form secondary phases if they are above it. The concept of multiple-principal-element alloys has recently expanded this view, as these materials are single-phase solid solutions of generally equiatomic mixtures of metallic elements. This group of materials has received much interest owing to their enhanced mechanical properties(1-5). They are usually called medium-entropy alloys in ternary systems and high-entropy alloys in quaternary or quinary systems, alluding to their high degree of configurational entropy. However, the question has remained as to how random these solid solutions actually are, with the influence of short-range order being suggested in computational simulations but not seen experimentally(6,7). Here we report the observation, using energy-filtered transmission electron microscopy, of structural features attributable to short-range order in the CrCoNi medium-entropy alloy. Increasing amounts of such order give rise to both higher stacking-fault energy and hardness. These findings suggest that the degree of local ordering at the nanometre scale can be tailored through thermomechanical processing, providing a new avenue for tuning the mechanical properties of medium- and high-entropy alloys.


Metal alloys consisting of three or more major elemental components show enhanced mechanical properties, which are now shown to be correlated with short-range order observed with electron microscopy.


  
Constructing protein polyhedra via orthogonal chemical interactions 期刊论文
NATURE, 2020, 578 (7793) : 172-+
作者:  Mooley, K. P.;  Deller, A. T.;  Gottlieb, O.;  Nakar, E.;  Hallinan, G.;  Bourke, S.;  Frail, D. A.;  Horesh, A.;  Corsi, A.;  Hotokezaka, K.
收藏  |  浏览/下载:20/0  |  提交时间:2020/07/03

Many proteins exist naturally as symmetrical homooligomers or homopolymers(1). The emergent structural and functional properties of such protein assemblies have inspired extensive efforts in biomolecular design(2-5). As synthesized by ribosomes, proteins are inherently asymmetric. Thus, they must acquire multiple surface patches that selectively associate to generate the different symmetry elements needed to form higher-order architectures(1,6)-a daunting task for protein design. Here we address this problem using an inorganic chemical approach, whereby multiple modes of protein-protein interactions and symmetry are simultaneously achieved by selective, '  one-pot'  coordination of soft and hard metal ions. We show that a monomeric protein (protomer) appropriately modified with biologically inspired hydroxamate groups and zinc-binding motifs assembles through concurrent Fe3+ and Zn2+ coordination into discrete dodecameric and hexameric cages. Our cages closely resemble natural polyhedral protein architectures(7,8) and are, to our knowledge, unique among designed systems(9-13) in that they possess tightly packed shells devoid of large apertures. At the same time, they can assemble and disassemble in response to diverse stimuli, owing to their heterobimetallic construction on minimal interprotein-bonding footprints. With stoichiometries ranging from [2 Fe:9 Zn:6 protomers] to [8 Fe:21 Zn:12 protomers], these protein cages represent some of the compositionally most complex protein assemblies-or inorganic coordination complexes-obtained by design.


An inorganic chemical approach to biomolecular design is used to generate '  cages'  that can simultaneously promote symmetry and multiple modes of protein interactions.


  
Chemical partitioning of fine particle-bound metals on haze-fog and non-haze-fog days in Nanjing, China and its contribution to human health risks 期刊论文
ATMOSPHERIC RESEARCH, 2017, 183
作者:  Li, Huiming;  39;geng
收藏  |  浏览/下载:10/0  |  提交时间:2019/04/09
Metal elements  Haze-fog episode  Fine particulate matter  Chemical partitioning  Health risk