The large difference between the Planck scale and the electroweak scale, known as the hierarchy problem, is addressed in certain models through the postulate of extra spatial dimensions. A search for evidence of extra spatial dimensions in the diphoton channel has been performed using the full set of proton-proton collisions at √ s = 7 TeV recorded in 2011 with the ATLAS detector at the CERN Large Hadron Collider. This dataset corresponds to an integrated luminosity of 4.9 fb −1 . The diphoton invariant mass spectrum is observed to be in good agreement with the Standard Model expectation. In the context of the model proposed by Arkani-Hamed, Dimopoulos and Dvali, 95% confidence level lower limits of between 2.52 and 3.92 TeV are set on the ultraviolet cutoff scale M S depending on the number of extra dimensions and the theoretical formalism used. In the context of the Randall-Sundrum model, a lower limit of 2.06 (1.00) TeV at 95% confidence level is set on the mass of the lightest graviton for couplings of k/M Pl = 0.1(0.01). Combining with the ATLAS dilepton searches based on the 2011 data, the 95% confidence level lower limit on the Randall-Sundrum graviton mass is further tightened to 2.23 (1.03) TeV for k/M Pl = 0.1(0.01). 1 ATLAS uses a right-handed coordinate system with its origin at the nominal interaction point (IP) in the centre of the detector and the z-axis along the beam pipe. The x-axis points from the IP to the centre of the LHC ring, and the y-axis points upward. Cylindrical coordinates (r, φ) are used in the transverse plane, φ being the azimuthal angle around the beam pipe. 2 The pseudorapidity is defined in terms of the polar angle θ as η = −ln tan(θ/2).

The ATLAS detector at the Large Hadron Collider is used to search for excited electrons and excited muons in the channel pp → * → γ , assuming that excited leptons are produced via contact interactions. The analysis is based on 13 fb −1 of pp collisions at a centre-of-mass energy of 8 TeV. No evidence for excited leptons is found, and a limit is set at the 95% credibility level on the cross section times branching ratio as a function of the excitedlepton mass m * . For m * 0.8 TeV, the respective upper limits on σ B( * → γ ) are 0.75 and 0.90 fb for the e * and µ * searches. Limits on σ B are converted into lower bounds on the compositeness scale . In the special case where = m * , excited-electron and excited-muon masses below 2.2 TeV are excluded.

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Ultrathin porous Co3O4 nanosheets are synthesized successfully, the thickness of which is about three unit-cell dimensions. The enhanced oxygen evolution reaction (OER) performance and electronic interaction between Co3O4 and Au is firstly reported in Co3O4 ultrathin porous nanosheets by physically mixing with Au nanoparticles. With the loading of the Au nanoparticles, the current density of ultrathin porous Co3O4 nanosheets is enhanced from 9.97 to 14.76 mA cm−2 at an overpotential of 0.5 V, and the overpotential required for 10 mA cm−2 decreases from 0.51 to 0.46 V, smaller than that of commercial IrO2 (0.54 V). Furthermore, a smaller Tafel slope and excellent durability are also obtained. Raman spectra, XPS measurement, and X-ray absorption near edge structure spectra (XANES) show that the enhanced OER ascribed to a higher Co2+/Co3+ ratio and quicker charge transfer due to the electronic interaction between Au and ultrathin Co3O4 nanosheets with low-coordinated surface, and Co2+ ions are beneficial for the formation of CoOOH active sites.