HER and HAR

Dependence of the HER and HAR Rates on the Potential and the Adsorption Gibbs Free Energy... 

From the steady-state equations (2.33) and (2.35), the variations of the surface and bulk atomic fractions 9h and Xh are interrelated and depend on the mechanism of the whole cathodic reaction, that is, both the HER and HAR. 

If a climber slips and falls, engaging the fall-arrest system, his or her body harness (and lanyard, too, if used) has been shock loaded. When the climber returns to the ground, the harness must never be worn again and must be immediately taken out of service (as specified by the PPE manufacturer). 

HER adsorbed intermediate (OP on-top sites on all transition metals. It is admitted that on iron and ferrous alloys the HER and the HAR share a common H g intermediate and that the surface-bulk transfer step is in quasi-equilibrium (see earlier) [31]. The mechanism of H absorption into the bulk of all transition metals at overpotential must then involve a sequence of two adsorption steps ... 

The weakly bonded OP H g in on-top sites simultaneously participates in the HER and the HAR. This mechanism distinguishes two adsorption steps instead of one in the surface-bulk transfer. Of course, this has no implications if the overall transfer step is in quasi-equilibrium, but if it is not—a situation occurring, for example, for H permeation in thin membranes [53,72]— the treatment of the kinetics of H absorption will become more complex. 

On the basis of this model, it is possible to predict die effects of ASB on die bulk H concentration [53,61,62], assuming that H jj is a reaction intermediate common to the HER and the HAR and that the surface-bulk transition is in quasi-equilibrium. 

As discussed earlier, such mechanisms involving two adsorbed H species with different bond energies and sites probably apply to all transition metals. It is likely that the sites for the HER adsorbed intermediate (OP HajJ are the weakly bonded on-top sites. But on oxidizable metals, H electroadsorption in the hollow strongly bonded sites followed by absorption is possible only at potentials below the limit of desorption of the oxygen species, calculated for Ni and Fe to be dose to 0V(rhed [28]. It is admitted that on iron and ferrous alloys the HER and the HAR share a common H ds intermediate and that the surface-bulk transfer step is in quasiequilibrium [8] (see Section 2.2.2.2.S). The mechanism of H absorption into the bulk of transition metals at cathodic overpotential must then involve a sequence of two consecutive adsorption steps ... 

The facilitator pulled her up, unhooked her from the harness, and folded her into his arms. You did it, Marlene. You did it. ... 

Many amputees who wear a body-powered prosthesis develop increased control due to a phenomenon called extended proprioception [ 90]. Extended proprioception gives the wearer feedback as to the position of the terminal device. The subject will know whether the hook is open or closed by the extent of pressure the harness is exerting on his or her shoulder area without having to visually inspect the operation. Many amputees do not like the cosmetic appearance of the hook and control cables and they request a natural-like part of the body replacement. 

While Alice s inquisitiveness may be idle curiosity, it attests to the contrast between them she wields a haphazard power that emanates from her person, and he harnesses occult forces. Intriguingly, Clarke responds to Alice s questions with rather mundane instructions, highlighting the accessibility of his knowledge ... 

---