Paddle wheel mechanism

One of the main obstacles in the migration of large cations such as Na, K+, or NH4 + (not Li + or H +) in rigid lattices is a too-small size of bottlenecks, or diffusion channels, between the cation sites, as shown above for the perovskite type (Figure 7.4). This factor is most critical for high-connectivity structures having D = 3 or 2. For D = 1 no data are available, while for D = 0 this factor may sometimes be of minor importance as small isolated ions (e.g., SO4 ) may rotate in the crystal structures, providing the so-called paddle-wheel mechanism [1, 2, 5, 61]. 

The algorithms of Voronoi polyhedra construction may easily be used for the high-throughput analysis of new materials to identify the presence ofan infinite network of channels with suitable size for ionic conductivity or molecular diffusion. At the same time, the approach has a limited applicability for those systems where the topological and geometric factors do not play a significant role, such as proton conductors, or where the framework is not truly immobile and participates in the conduction process, for example, via a paddle-wheel mechanism. 

The observations summarised here show that the high temperature polymorph shows fast Li conductivity and dynamic orientational disorder of the sulfate groups. The coexistence of these two highly unusual properties in a crystalline salt leads to the attractive interpretation that these phenomena are linked. Considerable effort has gone into the examination of a model for correlated motion in this structure and this has led to the description of ionic mobility in the a-Li2S04 structure proceeding via what has become known as the paddle-wheel mechanism. This mechanism describes the sulfate as acting as a rotor which provides a... 

Thus, for Li2S04 a paddle wheel mechanism has been proposed (with respect to the abiUty of the SO4 tetrahedron to rotate), in which the rotation of the anion directly effects the cation migration [366]. 

We have investigated the alteration in mechanical properties of the protein layer caused by the PFBC using a modified surface viscometer. The protein film was placed under a shearing stress by the application of a small torque to a teflon paddle wheel inserted into the interfacial boundary, and the angular deformation of the film was measured. From this data it was possible to obtain stress-strain curves and to determine the surface shear modulus and surface fracture point for the protein layer. In most studies protein was adsorbed to the interface of perfluorotributylamine from either a buffered... 

The equivalents 1 have already obtained are - 1st, 8231b., derived from magnetoelectrical experiments (PhU. Mag. Ser. 3 Vol. xxui. pp. 263, 347) 2nd, 7951b., deduced from the cold produced by the rarefaction of air (Ibid. May 1845, p. 369) tmd 3rd, 774 lb. from experiments (hitherto unpublished) on the motion of water through narrow tubes. This last class of experiments being similar to that with the paddle wheel, we may take the mean of 774 and 890, or 8321b., as the equivtilent derived from the friction of water. In such delicate experiments, where one hardly ever collects more than one another than that above exhibited could hardly have been expected. I may therefore conclude that the existence of an equivalent relation between heat and the ordinary forms of mechanical power is proved and assume 8171b., the mean of the results of three distinct classes of experiments, as the equivalent, until more accurate experiments shall have been made. 

James Rumsey was bom in Cecil Coimty, but little is known until he was living at Bath VA in 1782. In 1784 when George Washington stayed there, Rumsey showed him a model of a mechanical boat, which had a bow-moimted paddle wheel that worked poles to pull the boat upstream. Washington had plans to make Potomac River navigable, so that a company was formed. He recommended Rumsey in 1785 to oversee the clearing of rocks at Harper s Ferry on this river, while his brother-in-law built the pole-boat at Shepherdstown WV, yet steam propulsion was included. 

This problem guides you through a calculation of the mechanical equivalent of heat using data from one of James Joule s experiments with a paddle wheel apparatus (see Sec. 3.7.2). The experimental data are collected in Table 3.2. 

Sampling systems can be constructed with a paddle-wheel-type mechanism moving the sample in front of the sample window or by selecting a process location where the sample is continuously moving but still assuring constant coverage of the optical window. This type of sampling was implemented in the flour mill of Kansas State University [43,44]. 

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