Analysis of the interlayer infrared conductivity of cuprate high-transition temperature superconductors reveals an anomalously large energy scale extending up to midinfrared frequencies that can be attributed to formation of the superconducting condensate. This unusual effect is observed in a va- riety of materials, including Tl2Ba2CuO6+x, La2-xSrxCuO4, and YBa2Cu3O6.6, which show an incoherent interlayer response in the normal state. Midinfrared range condensation was examined in the context of sum rules that can be formulated for the complex conductivity. One possible interpretation of these experiments is in terms of a kinetic energy change associated with the superconducting transition.

We report the synthesis and properties of network polymers of intrinsic microporosity (network−PIMs) derived from triptycene monomers that possess alkyl groups attached to their bridgehead positions. Gas adsorption can be controlled by the length and branching of the alkyl chains so that the apparent BET surface area of the materials can be tuned within the range 618−1760 m2 g−1. Shorter (e.g., methyl) or branched (e.g., isopropyl) alkyl chains provide the materials of greatest microporosity, whereas longer alkyl chains appear to block the microporosity created by the rigid organic framework. The enhanced microporosity, in comparison to other PIMs, originates from the macromolecular shape of the framework, as dictated by the triptycene units, which helps to reduce intermolecular contact between the extended planar struts of the rigid framework and thus reduces the efficiency of packing within the solid. The hydrogen adsorption capacities of the triptycene-based PIMs with either methyl or isopropyl substituents are among the highest for purely organic materials at low or moderate presures (1.83% by mass at 1 bar/77K; 3.4% by mass at 18 bar/77 K). The impressive hydrogen adsorption capacity of these materials is related to a high concentration of subnanometre micropores, as verified by Horvath−Kawazoe analysis of low-pressure nitrogen adsorption data.

The superconductivity discovered in iron-pnictides is intimately related to a nematic ground state, where the C4 rotational symmetry is broken via the structural and magnetic transitions. We here study the nematicity in NaFeAs with the polarization dependent angle-resolved photoemission spectroscopy. A uniaxial strain was applied on the sample to overcome the twinning effect in the low temperature C2-symmetric state, and obtain a much simpler electronic structure than that of a twinned sample. We found the electronic structure undergoes an orbital-dependent reconstruction in the nematic state, primarily involving the dxy-and dyz-dominated bands. These bands strongly hybridize with each other, inducing a band splitting, while the dxz-dominated bands only exhibit an energy shift without any reconstruction. These findings suggest that the development of orbitaldependent spin polarization is likely the dominant force to drive the nematicity, while the ferroorbital ordering between dxz and dyz orbitals can only play a minor role here.

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The erythrocyte sedimentation rate and the C-reactive protein level provide excellent diagnostic test information for establishing the presence or absence of infection prior to surgical intervention in patients with pain at the site of a knee arthroplasty.

Quick on the uptake: Following its identification during a targeted search, the intriguing crystal structure of 3,3′,4,4′‐tetra(trimethylsilylethynyl)biphenyl was investigated. Simple removal of the included solvent provides an organic crystal with an open microporous structure that has a striking similarity to that of zeolite A (see picture). Reversible adsorption of nitrogen and hydrogen gases at 77 K confirms that the microporosity is permanent.

Treatment of siliceous MCM-41 with aluminum chloride was performed in a vacuum at a temperature of 403 K. The obtained AlCl3/MCM-41 material was characterized by multinuclear solid-state NMR spectroscopy and by application of probe molecules. The results of NMR spectroscopy indicate a reaction of aluminum chloride with vicinal silanol groups at the surface of conditioned MCM-41 and the formation of tetrahedrally coordinated aluminum species bound to chlorine and framework oxygen atoms. In the local structures of 3% of these aluminum atoms, strong Brønsted acid sites are formed causing a 1H MAS NMR signal at 6.0 ppm. According to 13C MAS NMR spectroscopy of acetone-2-13 C adsorbed on AlCl3/MCM-41 (241 and 245 ppm), these Brønsted acid sites are characterized by an acid strength higher than that of bridging OH groups in H−ZSM-5 (223 ppm).

The strength of the interlayer Josephson tunneling in layered superconductors is an essential test of the interlayer tunneling model as a mechanism for superconductivity, as well as a useful phenomenological parameter. A scanning superconducting quantum interference device (SQUID) microscope was used to image interlayer Josephson vortices in Tl2Ba2CuO6+delta and to obtain a direct measure of the interlayer tunneling in a high-transition temperature superconductor with a single copper oxide plane per unit cell. The measured interlayer penetration depth, lambdac, is approximately 20 micrometers, about 20 times the penetration depth required by the interlayer tunneling model.