Iron oxide nanominerals are generated by photocatalytic oxidation of Fe2+aq, and Fe2+aq promotes the transformation of the photochemically synthesized schwertmannite.

interest, because of their superior theoretical energy density (11.6 kWh kg −1 ) in comparison with conventional Li-ion batteries, [1][2][3][4][5][6][7] which makes them a strong candidate for grid scale energy storage and critical part of future renewable energy portfolio. A typical rechargeable aprotic Li-O 2 battery contains a lithium metal anode, a glass-fiber separator soaked with electrolyte, and an oxygen-breathing cathode. [8] In the discharge process, oxygen is supplied to the cell as one of the active materials, which is different from the conventional battery systems such as lead-acid batteries or lithium-ion batteries. Li-O 2 battery induces a current flow by the oxidation of lithium at the anode and the reduction of oxygen at the cathode, namely, the oxygen reduction reaction (ORR) during discharge. In the charge process, the oxygen evolution reaction (OER) occurs on cathode side by decomposing the discharge products Li 2 O 2 or LiO 2 . The standard redox potential of these electrochemical reactions is close to 3.0 V versus Li/Li + . [4,5] Currently, several issues limit the performance of Li-O 2 batteries such as large overpotential, low rate capability, and poor cycleability. [9][10][11][12] In particular, the significant charge overpotential is one of the major challenges hindering the commercialization of longterm viable Li-O 2 battery. The high charge overpotential increases the possibility of electrolyte decomposition and other side reactions, from which the byproducts may be produced, which continuously aggravates the charge overpotential and passivates the whole battery system. [13][14][15] In addition, the high overpotential also causes a low round-trip efficiency and coulombic efficiency. It is well known that due to the multiple electron transfer nature, the charge overpotential is usually caused by the sluggish kinetics of the OER. Hence, various electrocatalysts, including metals, [16][17][18][19][20] metal oxides, [21][22][23][24][25] and metal complexes, [26][27][28] have been explored to lower the overpotential and to improve the battery performance. However, most of the charge potentials are still too high for practical use of the rechargeable Li-O 2 battery. In addition, most of the efforts have been focused on single metal catalysts, which may limit the tunability to further improve their catalytic activity.Over the last few decades, nanostructured bimetallic catalysts have shown extraordinary electronic and chemical catalytic properties for many applications, such as fuel cells, nitrogen production, and biomass-fuel conversion. [29][30][31][32] The greatly enhanced catalytic performance can be ascribed to the formation Rechargeable lithium-oxygen (Li-O 2 ) batteries are one of the most pro mising technologies for next-generation energy storage, which is also a critical part of the future renewable energy portfolio; however, its commercialization is still hindered by several challenges. The high charge overpotential, in particular, not only causes problems by increasing the possibi...

SEM and in-operando XRD correlate operating conditions, spinel peak shifts, nano-nodule formation, and activation or degradation behavior in LSCF cathodes.

No abstract

The implementation of a laser pump/X-ray probe scheme for performing picosecond-resolution X-ray diffraction at the 1W2B wiggler beamline at Beijing Synchrotron Radiation Facility is reported. With the hybrid fill pattern in top-up mode, a pixel array X-ray detector was optimized to gate out the signal from the singlet bunch with interval 85 ns from the bunch train. The singlet pulse intensity is ∼2.5 × 10(6) photons pulse(-1) at 10 keV. The laser pulse is synchronized to this singlet bunch at a 1 kHz repetition rate. A polycapillary X-ray lens was used for secondary focusing to obtain a 72 µm (FWHM) X-ray spot. Transient photo-induced strain in BiFeO3 film was observed at a ∼150 ps time resolution for demonstration.

This paper proposes an adaptive fault-tolerant control scheme for nonaffine nonlinear systems. A model approximation method which is a solution that bridges the gap between affine and nonaffine control systems is developed firstly. A joint estimation approach is based on unscented Kalman filter, in which both failure parameters and states are simultaneously estimated by means of the argument state vector composed of the unknown faults and states. Then, stability analysis is given for the closed-loop system. Finally, the proposed approach is verified using a three-degree-of-freedom simulation of a typical fighter aircraft and the significantly improved system response demonstrates the practical potential of the theoretic results obtained.

A new triterpenoid glycoside, heterobetulinic acid 3-O-β-D-glucopyranosyl(1 → 2)-β-D-xylopyranoside (1), together with a new phenylacrylic acid derivative, 3'S,4'-dihydroxyl-2'-methylene-but-1'-enyl caffeate (2), were isolated from the roots of Ilex pubescens. Their structures were elucidated by HR-ESI-MS, 1-D and 2-D NMR analyses and chemical methods. In addition, the absolute configuration of 2 was established by the application of a modified Mosher's method.

In order to retrain chaotic oscillation of marine power system which is excited by periodic electromagnetism perturbation, command-filtered adaptive backstepping method is used to design the chaotic controller based on the two parallel nonlinear mathematical model. Lyapunov stability theory is applied to prove that the system can remain close-loop asymptotically stable with this controller. Simulation results indicate that the designed controller can suppress chaotic oscillation with fast convergence speed, that make the system return to the equilibrium point quickly, meanwhile the parameter which induces chaotic oscillation can also be discriminated.