Lever arm

Moment of Force (Torque or Bending Moment). Moment of force is force times moment arm (lever arm). Its SI unit is N-m. 

It seems likely, therefore, that as the bound phosphate molecule is released, the cleft starts to open and the myosin head binds to actin (Figure 14.17d). Release of ADP coincides with a conformational change that fully opens the myosin cleft, causing actin to be tightly bound, and moves the lever arm to the "down" position. Since the myosin head is now strongly bound to actin at one end and covalently linked to the myosin fibril at the other... 

On the source-sink mapping diagram, sources are represented by shaded circles and sinks are represented by hollow circles. Typically, process constraints limit the range of pollutant composition and load that each sink can accept. ITie intersection of these two bands provides a zone of acceptable conqKisition and load for recycle. If a source (e.g., source a) lies within this zone, it can be directly recycled to tiie sink (e.g., sink S). Moreover, sources b and c can be mixed using the lever-arm principle to create a mixed stream that can be recycled to sink S. 

In order to reduce fresh-water consumption in the scrubber, the usage of distillation bottoms and the off-gas condensate should be maximized since diey have the least ammonia content. The flowrate resulting from combining these two sources (5.8 kg/s) is sufflcient to run the scrubber. However, its ammonia composition as determined by the lever-arm principle is 12 ppm, which lies outside the zone of permissible recycle to the scrubber. As shown by Fig. 4.7, the maximum flowrate of the off-gas condensate to be recycled to the scrubber is determined to be 4.1 kg/s and the flowrate of fresh water is 0.9 kg/s (5.8 — 0.8 — 4.1). Therefore, direct recycle can reduce the fresh-water consumption (and consequently the... 

In the majority of cases, the tests are conducted using a dead-weight lever-arm stress-rupture rig with an electric timer to determine the moment of fracture, but a variety of test rigs similar to those shown in Fig. 8.89g are also used. The evaluation of embrittlement may be based on a delayed-failure diagram in which the applied nominal stress versus time to failure is plotted (Fig. 8.103) or the specimen may be stressed to a predetermined value (say 75% of the ultimate notched tensile strength) and is considered not to be embrittled if it shows no evidence of cracking within a predetermined time (say 500 h). Troiano considers that the nature of delayed fracture failure can be described by four parameters (see Fig. 8.103) ... 

T = Force x Lever arm = Shear stress x Surface area x Radius... 

Two vectors commonly represented in terms of cross products are the angular momentum of a particle about some point, equal to the cross product of the momentum vector of the particle and the radius vector from the origin to the particle and torque, equal to the cross product of the force vector and the vector representing the lever arm. 

Very good temperature homogenity over a wide temperature range. Convection in the furnace has only a very small influence on the balance without necessity for special shielding. The disadvantages of this construction are the position of the sample holder and its lever arm, its sensitivity to vibrations. 

An example of a binary eutectic system AB is shown in Figure 15.3a where the eutectic is the mixture of components that has the lowest crystallisation temperature in the system. When a melt at X is cooled along XZ, crystals, theoretically of pure B, will start to be deposited at point Y. On further cooling, more crystals of pure component B will be deposited until, at the eutectic point E, the system solidifies completely. At Z, the crystals C are of pure B and the liquid L is a mixture of A and B where the mass proportion of solid phase (crystal) to liquid phase (residual melt) is given by ratio of the lengths LZ to CZ a relationship known as the lever arm rule. Mixtures represented by points above AE perform in a similar way, although here the crystals are of pure A. A liquid of the eutectic composition, cooled to the eutectic temperature, crystallises with unchanged composition and continues to deposit crystals until the whole system solidifies. Whilst a eutectic has a fixed composition, it is not a chemical compound, but is simply a physical mixture of the individual components, as may often be visible under a low-power microscope. 

Another technique consists of submitting the emulsion to centrifugation and determining the droplet volume fraction < / at the top (bottom) of the cream (sediment). The centrifugation typically takes several hours until the equilibrium volume fraction is achieved. After equilibration, if the droplets occupy a distance much less than that of the centrifuge lever arm, the spatial gradient in the acceleration can be neglected, and the osmotic pressure can be determined (see Fig. 4.1) ... 

Note Before the centrifuge test was developed by Dr W.O. Snelling, the Bur of Mines used the pressure test for exudation, which consisted in exposing a sample of explosive to a definite pressure produced by the weight of a lever arm, and determining the amt of liquid forced out of the expl. Many modifications of this test have been tried, in which absorbent materials like cotton or blotting paper have been used to hold the exudant, but none of them made the test reliable (Ref 1, p9)... 

Overturn Couple or Lever Arm. The distance between the center of gravity and the center of pressure is known as the overturning couple or the lever arm, and thru this the stabilizing forces deriving from spin operate. Since neither of these two centers lies exactly on the axis (due to normal manufg errors) the result is yaw. The... 

For a two-pan balance, the lever arms are equal (Lt = L2), the pan weights are equal, and the effect of gravity cancels, so that "at balance" the situation simply reduces to the fact that the effective masses of the object (o) and the weights (w) are equal. That is,... 

This same expression can be derived for single-pan balances that use the method of substitution of weights. The fact that the lever arms are unequal and that there is a constant load on the balance does not alter the final expression. 

Fig. 7. Two models also propose that R may use Gfly to catalyze GDP release. In the lever-arm model, the receptor uses the aN helix as a lever to pull G/ y away from Ga, thereby prying Switch II away from the nucleotide-binding pocket and causing GDP release. The alternative, gearshift model requires that the receptor pushes G/ y closer to Ga. This allows the N-terminus of Gy to engage the helical domain, thus forcing the binding pocket due to the reorientation of the two domains. FJ...

Timken EP test—measure of the extreme-pressure properties of a lubricating oil (see EP oil). The test utilizes a Timken machine, which consists of a stationary block pushed upward, by means of a lever arm system, against the rotating outer race of a roller bearing, which is lubricated by the product under test. The test continues under increasing load (pressure) until a measurable wear scar is formed on the block. Timken OK load is the heaviest load that a lubricant can withstand before the block is scored (see scoring). 

Examining these structures and the fact that they are all powered by ATP, the question remains as to how force is actually produced. Geeves and Holmes (2005) argue that myosin acts by the specific coupling between different myosin head states and different positions of the lever arm on the motor domain, so that, once attached to actin, the myosin acts as an ATP-driven motor where the energy released by ATP hydrolysis is direcdy coupled to the performance of mechanical work. However, Marx et al. (2005) argue that in some cases the kinesins appear to act as thermal ratchets. In this case, the attachment of a second head, once the first head has bound, is an event controlled by thermal motion, but, presumably for steric reasons, the head is more likely to bind to the microtubule in the... 

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