Ratchet phase

Below a temperature of Toi 260 K, the Ceo molecules completely lose two of their three degrees of rotational freedom, and the residual degree of freedom is a ratcheting rotational motion for each of the four molecules within the unit cell about a different (111) axis [43, 45, 46, 47]. The structure of solid Ceo below Tqi becomes simple cubic (space group Tji or PaS) with a lattice constant ao = 14.17A and four Ceo molecules per unit cell, as the four oriented molecules within the fee structure become inequivalent [see Fig. 2(a)] [43, 45]. Supporting evidence for the phase transition at Tqi 260 K is... 

In conclusion, we have found the ratchet current for strong and weak asymmetric potentials. It exhibits a set of universal power dependencies on the voltage and can grow as the voltage decreases. In Ref. [25] our analysis was extended to include the electron spin. This leads to a complicated phase diagram with several qualitatively different transport regimes for different interaction strengths. 

During cell/stack operation, water content in the membrane is affected by the local intensive variables, such as local temperature, water vapor concentration in the gas phase, gas temperature and velocity in the channel, and the properties of the electrode and gas diffusion media. The power fluctuation can result in temperature variation inside the cell/stack, which will subsequently change the local membrane water content. As the water content in the membrane tends to be non-uniform and unsteady, this results in operation stresses. When the membrane uptakes water from a dry state, it tends to expand as there is no space for it to extend in plane and it can wrinkle up as schematically shown in Fig. 4 when the membrane dries out, the wrinkled part may not flatten out, and this ratcheting effect can cause the pile up of wrinkles at regions where membrane can find space to fold. The operation stress is typically cyclic in nature due to startup-shutdown cycles, freeze-thaw cycles, and power output cycles. 

In 2005 and 2007 (Phase 2), a more recent study for the U. S. Marine Corps, by Hill et al., evaluated 13 self-applied tourniquets for their applicability in combat applications. This study attempted to measure the functionality of the candidate tourniquets in battlefield conditions by immersing them in a simulated blood/sand mixture prior to testing. In contrast to the earlier Army study by Walters et al., the conclusion drawn from this study was the recommendation that one of the ratcheting or stretch-retention type tourniquet systems be adopted for combat deployment. These types had the best user subjective ratings as well as the lowest application times especially on the upper extremities where one-handed application was required. The recommended group had application times 30-50% lower on the upper extremities than the windlass types recommended by the Army study. Velcro was observed to lose its effectiveness as a clamp when it became fouled with wet sand or mud and, therefore, should be avoided. It should be noted that none of the tourniquet types used in the Marine Corps study were pneumatic. 

With regard to the architecture of these phases the authors suggest a helical arrangement of the molecules in the columns. This chiral arrangement is more pronounced in case of the a-anomers, because the axially oriented chain at the anomeric position mesh into the gap at the pyranosidic oxygen of the neighboring molecule in the column [139]. In case of the ]5-anomer this ratcheting is not expected, and indeed not observed, since all five substituents are in an equatorial position [139]. 

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