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Biological materials, such as bones, teeth and mollusc shells, are well known for their excellent strength, modulus and toughness.sup.1-3. Such properties are attributed to the elaborate layered microstructure of inorganic reinforcing nanofillers, especially two-dimensional nanosheets or nanoplatelets, within a ductile organic matrix.sup.4-6. Inspired by these biological structures, several assembly strategies--including layer-by-layer.sup.4,7,8, casting.sup.9,10, vacuum filtration.sup.11-13 and use of magnetic fields.sup.14,15--have been used to develop layered nanocomposites. However, how to produce ultrastrong layered nanocomposites in a universal, viable and scalable manner remains an open issue. Here we present a strategy to produce nanocomposites with highly ordered layered structures using shear-flow-induced alignment of two-dimensional nanosheets at an immiscible hydrogel/oil interface. For example, nanocomposites based on nanosheets of graphene oxide and clay exhibit a tensile strength of up to 1,215 [plus or minus] 80 megapascals and a Young's modulus of 198.8 [plus or minus] 6.5 gigapascals, which are 9.0 and 2.8 times higher, respectively, than those of natural nacre (mother of pearl). When nanosheets of clay are used, the toughness of the resulting nanocomposite can reach 36.7 [plus or minus] 3.0 megajoules per cubic metre, which is 20.4 times higher than that of natural nacre; meanwhile, the tensile strength is 1,195 [plus or minus] 60 megapascals. Quantitative analysis indicates that the well aligned nanosheets form a critical interphase, and this results in the observed mechanical properties. We consider that our strategy, which could be readily extended to align a variety of two-dimensional nanofillers, could be applied to a wide range of structural composites and lead to the development of high-performance composites. Layered nanocomposites fabricated using a continuous and scalable process achieve properties exceeding those of natural nacre, the result of stiffened matrix polymer chains confined between highly aligned nanosheets., Author(s): Chuangqi Zhao [sup.1] , Pengchao Zhang [sup.1] , Jiajia Zhou [sup.1] [sup.2] , Shuanhu Qi [sup.1] [sup.2] , Yoshihiro Yamauchi [sup.3] , Ruirui Shi [sup.1] , Ruochen Fang [sup.1] [...]

\nImpact statementUnderstanding the nature of grain boundaries is a prerequisite for fabricating high-performance superconducting bulks and wires. For iron-based superconductors [e.g. Ba(Fe,Co)2As2, Fe(Se,Te), and NdFeAs(O,F)], the dependence of the critical current density Jc on misorientation angle (θGB) has been explored on [001]-tilt grain boundaries, but no data for other types of orientations have been reported. Here, we report on the structural and transport properties of Fe(Se,Te) grown on CeO2-buffered symmetric [010]-tilt roof-type SrTiO3 bicrystal substrates by pulsed laser deposition. X-ray diffraction and transmission electron microscopy revealed that θGB of Fe(Se,Te) was smaller whereas θGB of CeO2 was larger than that of the substrate. The difference in θGB between the CeO2 buffer layer and the substrate is getting larger with increasing θGB. For θGB≥24∘ of the substrates, θGB of Fe(Se,Te) was zero, whereas θGB of CeO2 was continuously increasing. The inclined growth of CeO2 can be explained by the geometrical coherency model. The c-axis growth of Fe(Se,Te) for θGB≥24∘ of the substrates is due to the domain matching epitaxy on (221) planes of CeO2. Electrical transport measurements confirmed no reduction of inter-grain Jc for θGB≤9∘, indicative of strong coupling between the grains.The issue of weak-links inherent in iron-based superconductors, Fe(Se,Te), can be avoided by employing CeO2-buffer layer containing the Σ9[110]/{221} grain boundary. [ABSTRACT FROM AUTHOR]

Ruthenium-catalyzed preparation of the conjugated enynes is carried out in reactions of 1-cyclopropyl-2-propyn-1-ols with nitrogen- and oxygen-centered nucleophiles like anilines and water in the presence of a catalytic amount of sulfur-bridged diruthenium complexes. These complexes are used as catalysts for realizing the completely stereoselective preparation of tri- and tetrasubstituted conjugated enynes where ruthenium-allenylidene complexes work as key intermediates.

The longest bottlebrush polymers reported so far (up to 7 μm in length) were synthesized in two steps from a norbornene derivative bearing two 2‐bromoisobutylate moieties (NB). The key to this achievement is the excellent reactivity of NB in ring opening metathesis polymerization, which proceeded in a well‐controlled manner with quantitative conversion of NB for monomer‐initiator ratios ranging up to 10,000. The resultant polymer derived from NB was readily converted to various bottlebrush polymers in a divergent synthetic route by grafting vinyl monomers from the 2‐bromoisobutylate units in NB via atom transfer radical polymerization. The structure of the ultra‐long bottlebrush polymer was directly observed using atomic force microscopy. [ABSTRACT FROM AUTHOR]

Three-dimensional m * n arrays of metal ion clusters, assembled as aromatic stacks of planar polynuclear metal complexes within columnar coordination cages are described. The reactions between hexanuclear [Au.sub.3]-[Au.sub.3] clusters and Ag(I) ions to prepare a silver-sandwiched hetero-[Au.sub.3]-Ag-[Au.sub.3] cluster are described.

One-step multicomponent self-assembly is used to synthesize septuple columnar stacks of large aromatic molecules with solubilizing side chains. The m * n aggregates of aromatic stacks is observed to form at increased concentrations in aqueous solution while simple addition of water induces lyotropic liquid-crystalline mesophases.

Several crystallographic studies are conducted to explain the assembly of the well-defined stacks of the polarized aromatic compounds in the confined aromatic cavities. The various dipole-dipole interactions are shown to play an extremely significant role in the discussed interactions.

The self-assembly of aromatic columns consisting of seven to nine discretely stacked aromatic rings is described by using the precisely controlled noncovalent interactions. These structures have provided vertical [pi]-conjugations and they are potential elements for nanofabrication systems for electroconductive and photophysical devices.

A novel ruthenium-catalyzed vinylic substitution reaction of vinylic trifluoromethanesulfonates with nucleophiles is described. This is considered to be a new type of vinylic substitution reaction, which has proceeded via ruthenium-butatrienylidene complexes as key intermediates.