Proposed Wave Momentum Source for Generating the 22-Year Solar Cycle

For the 22-year solar cycle oscillation there is no external time dependent source. A nonlinear oscillation, the solar cycle must be generated internally, and Babcock-Leighton models apply an artificial nonlinear source term that can simulate the observations—which leaves open the question of the actual source mechanism for the solar cycle. Addressing this question, we propose to take guidance from the wave mechanism that generates the 2-year Quasi-biennial Oscillation (QBO) in the Earth atmosphere. Upward propagating gravity waves, eastward and westward, deposit momentum to generate the observed zonal wind oscillation. On the Sun, helioseismology has provided a thorough understanding of the acoustic p-waves, which propagate down into the convective envelope guided by the increasing temperature and related propagation velocity. Near the tachocline with low turbulent viscosity, the waves propagating eastward and westward can produce an axisymmetric 22-year oscillation of the zonal flow velocities that can generate the magnetic solar dynamo. Following the Earth model, waves in opposite directions can generate in the Sun wind and magnetic field oscillations in opposite directions, the proposition of a potential solar cycle mechanism.

Electrocatalytic oxygen reduction performances of surface Ag granular packs electrodeposited from dual-phase Ag_(35.5)Zn_(64.5) precursor alloys by triangle wave potential cycling

Surface Ag granular packs(SAgPs) have been fabricated from dual-phase Ag_(35.5)Zn_(64.5) precursor alloy consisting of both e and c phases by using a facile one-step triangle wave potential cycling in 0.5 mol·L^(-1) KOH.During the continuous potential cyclic sweeping, the c phases preferentially dissolve during the anodic scan and dominant reduction reactions of Ag cations lead to redeposition and accumulation of Ag atoms together to form SAg Ps during cathodic scan. The e phases stay inactive to form a continuous skeleton in the inner regions. SAg Ps with an average particle size of 94-129 nm can be obtained at scan rates of 25, 50 and 100 mV·s^(-1) for 100 triangle wave potential cycles. SAgPs formed at a scan rate of 50 mV·s^(-1) exhibit superior oxygen reduction reaction performances with the onset potential of 0.93 V, half-wave potential of 0.72 V and an electron transfer number of 4.0.The above-mentioned SAgPs have superior stabilities as ORR catalysts.