Unlocking the Transition of Electrochemical Water Oxidation Mechanism Induced by Heteroatom Doping.

Heteroatom doping has emerged as a highly effective strategy to enhance the activity of metal-based electrocatalysts toward the oxygen evolution reaction (OER). It is widely accepted that the doping does not switch the OER mechanism from the adsorbate evolution mechanism (AEM) to the lattice-oxygen-mediated mechanism (LOM), and the enhanced activity is attributed to the optimized binding energies toward oxygen intermediates. However, this seems inconsistent with the fact that the overpotential of doped OER electrocatalysts (<300 mV) is considerably smaller than the limit of AEM (>370 mV). To determine the origin of this inconsistency, we select phosphorus (P)-doped nickel-iron mixed oxides as the model electrocatalysts and observe that the doping enhances the covalency of the metal-oxygen bonds to drive the OER pathway transition from the AEM to the LOM, thereby breaking the adsorption linear relation between *OH and *OOH in the AEM. Consequently, the obtained P-doped oxides display a small overpotential of 237 mV at 10 mA cm-2 . Beyond P, the similar pathway transition is also observed on the sulfur doping. These findings offer new insights into the substantially enhanced OER activity originating from heteroatom doping.

Subnanometric Ru clusters with upshifted D band center improve performance for alkaline hydrogen evolution reaction.

Subnanometric metal clusters usually have unique electronic structures and may display electrocatalytic performance distinctive from single atoms (SAs) and larger nanoparticles (NPs). However, the electrocatalytic performance of clusters, especially the size-activity relationship at the sub-nanoscale, is largely unexplored. Here, we synthesize a series of Ru nanocrystals from single atoms, subnanometric clusters to larger nanoparticles, aiming at investigating the size-dependent activity of hydrogen evolution in alkaline media. It is found that the d band center of Ru downshifts in a nearly linear relationship with the increase of diameter, and the subnanometric Ru clusters with d band center closer to Femi level display a stronger water dissociation ability and thus superior hydrogen evolution activity than SAs and larger nanoparticles. Benefiting from the high metal utilization and strong water dissociation ability, the Ru clusters manifest an ultrahigh turnover frequency of 43.3 s-1 at the overpotential of 100 mV, 36.1-fold larger than the commercial Pt/C.

Recent advances in high- ß N experiments and magnetohydrodynamic instabilities with hybrid scenarios in the HL-2A Tokamak.

Over the past several years, high- ß N experiments have been carried out on HL-2A. The high- ß N is realized using double transport barriers (DTBs) with hybrid scenarios. A stationary high- ß N ( > 2 ) scenario was obtained by pure neutral-beam injection (NBI) heating. Transient high performance was also achieved, corresponding to ß N ≥ 3 , n e / n e G ∼ 0.6 , H 98 ∼ 1.5 , f b s ∼ 30 % , q 95 ∼ 4.0 , and G ∼ 0.4 . The high- ß N scenario was successfully modeled using integrated simulation codes, that is, the one modeling framework for integrated tasks (OMFIT). In high- ß N plasmas, magnetohydrodynamic (MHD) instabilities are abundant, including low-frequency global MHD oscillation with n = 1, high-frequency coherent mode (HCM) at the edge, and neoclassical tearing mode (NTM) and Alfvénic modes in the core. In some high- ß N discharges, it is observed that the NTMs with m / n = 3 / 2 limit the growth of the plasma energy and decrease ß N . The low-n global MHD oscillation is consistent with the coupling of destabilized internal (m/n = 1/1) and external (m/n = 3/1 or 4/1) modes, and plays a crucial role in triggering the onset of ELMs. Achieving high- ß N on HL-2A suggests that core-edge interplay is key to the plasma confinement enhancement mechanism. Experiments to enhance ß N will contribute to future plasma operation, such as international thermonuclear experimental reactor .

Influence of thermal blooming on the beam quality of an array of Hermite-Gaussian beams propagating in the atmosphere.

The influence of thermal blooming on the quality of an array of Hermite-Gaussian (H-G) beams propagating in the atmosphere is studied, where the incoherent combination is considered. An analytical expression of the equivalent distortion parameter of such an array is derived and validated. As the mode order or the inverse radial fill factor of an array of H-G beams increases, the thermal blooming effect weakens, requiring more time to reach steady-state thermal blooming. The focal shift of an array of H-G beams in the atmosphere is also investigated. Owing to the thermal blooming effect in the atmosphere, the actual focus moves away from the geometric focus as the mode order decreases, which is different from the behavior in free space. Additionally, for an array of multimode beams, the actual focus moves away from the target as the weighting factor of TEM00 increases.

Thermal blooming effect of Hermite-Gaussian beams propagating through the atmosphere.

The thermal blooming effect of Hermite-Gaussian (H-G) beams propagating through the atmosphere is studied analytically and numerically. The analytical expression for the distortion parameter of steady-state thermal blooming of H-G beams propagating through the atmosphere is derived. It is shown that, under the same beam power, the higher the mode order of H-G beams, the weaker the thermal blooming effect. In particular, the thermal blooming effect for a H-G beam is weaker than that for a Gaussian beam. It is found that as the mode order increases, the beam width at the target may decrease due to the thermal blooming effect, although the initial beam width increases. When the cross-wind velocity is large enough, the symmetry of an asymmetric H-G beam may be improved by thermal blooming if the astigmatism parameter is adopted to characterize the symmetry of H-G beams. As the mode order of H-G beams increases, the shift of the beam centroid position decreases, but it takes more time to reach steady-state thermal blooming. On the other hand, the thermal blooming effect on the multimode beam quality is also examined in this paper. It is shown that a minimum beam spot on the target can be obtained if the optimal weighting factor of multimode beams is adopted.

Application of Doctor-Nurse-Patient Integration Management Mode in Patients with Endometriosis.

BACKGROUND: To investigate the effect of applying doctor-nurse-patient integration management mode to patients with endometriosis (EMT). METHODS: A total of 160 patients with EMT from the Department of Neurology of The Fifth Affiliated Hospital Sun Yat-Sen University from January 2017 to October 2017 were selected. They were divided into control group and experimental group according to the time sequence of hospitalization, with 80 patients in each group. The traditional nursing management mode was implemented in the control group, and doctor-nurse-patient integration mode was implemented in the experimental group. The psychological status, quality of life, and satisfaction of the 2 groups of patients were compared one year after surgery. RESULTS: The anxiety and depression scores in the observation group were (41.89±7.50) and (42.40±7.40) points, respectively, and those in the control group were (57.55±9.68) and (55.00±9.35) points, respectively. The differences between the two groups were statistically significant (t=-11.44, -9.42, P<0.05). The improvement rate of quality of life (sleep, work and sexual life) in the observation group was 87.5%, which was higher than that in the control group (63.8%). The difference between the 2 groups was statistically significant (U=583, P<0.01). The satisfaction rate in the observation group was 90.00%, which was higher than that in the control group (78.75%) (U=592.00, P< 0.01). CONCLUSION: The doctor-nurse-patient integration management mode can effectively improve the negative psychological status and quality of life of patients with EMT and improve patient satisfaction, which is worth popularizing.

Cryopump development of the 5 MW neutral beam injector system on HL-2M tokamak.

In order to carry out the long pulse and high power neutral beam injector (NBI) heating experiment on the HL-2M tokamak and satisfy its high vacuum pumping speed in the NBI, two built-in cryopumps with large area and based on a three-stage adsorption structure have been developed. The design idea and size of the three stage structure, the manufacturing technique, and the test experiment for cryopumps have been described in this paper. The experimental result shows that the cooldown time of liquid nitrogen pipes and liquid helium pipes are 1.5 h and 10 min, respectively. With activated charcoal bonded on the condensation plates, the pumping speed reaches 1.13 × 106 l/s, and the consumption of liquid helium is 2.53 g/s and 3.11 g/s for the 4-component pump and the 5-component pump, respectively. The conductance probability of the pump inlet is 0.25 for hydrogen.