Rotor spinning

Under the influence of a gravitational (centrifugal) field, a solute particle of mass m — M/Ni immersed in a solvent of density p at a distance r from the rotor axis experiences three forces. Within the frame of reference of the rotor, spinning with angular velocity co, these are the centrifugal force Fc, the buoyant force Fb, and the frictional force Ff. 

The ZSM-4 sample was prepared following the previously described procedures.[20] The elemental analysis showed that the Si/Al ratio was 3.0. 29Si MAS NMR spectra were recorded at 11.7 T MHz on a Varian InfinityPlus 500 spectrometer on a sample loaded in a 7.5 mm MAS rotor spinning at 4 kHz using a rc/2 rad pulse length and a recycle delay of 360 s. The 29Si chemical shifts are referenced with respect to an external solution of TMS (5Si = 0.0 ppm). 

Rotor bodies, in steam turbines, 23 231 Rotor electrostatic separators, 16 643-644 Rotor rotating converter, 16 151 Rotors, molecular, 17 59-61 Rotor spinning cotton yarn, 3 17 Rotor-stator devices, 10 127 Rotor-stator disperser, 3 701 Rotor-stator mills, 13 65 Rotor-stator mixers, 16 674-675 Rotosil process, 22 412 Roughages, as ruminant feeds, 10 863 Roughing, in mineral separation, 16 604 Roughing services, magnetic drums used in, 15 446... 

Measurement and analysis of trash and dust in cotton is important in the prediction of dust generation potential, in relation to byssinosis (14) and rotor spinning performance (15). By definition, trash is the nonlint particles including dust which settle under the influence of gravity in the processing of cotton. Dust is the finer material capable of being dispersed in air. Particulate burden is the combined trash and dust level in cotton. 

The usual precautions regarding temperature and vibration control also apply to the ultracentrifuge. To overcome air resistance and the attendant frictional heating, the compartment in which the rotor spins is evacuated and may be thermostated over a wide range of temperatures. The rotor is mounted on a flexible drive shaft that minimizes the need for precise balancing as a requirement for vibration-free operation. Finally, the rotor assembly is enclosed in an armored steel chamber for safety. At these speeds, a runaway rotor is deadly ... 

The skimmed oil Is collected and transferred to wet crude tank. Water from the SPI separator is discharged to induced air floatator. This unit is composed of four floatation cells. Each cell is equipped with a motor driven self-aerating rotor meonanistn. As the rotor spins, minute bubbles are generated ar.d oil and suspended solid particles attach to the gas bubbles as tney rise to the surface. Tne oil and suspended solids gather in a dense froth on the surface and are removed from the cell by skimmer paddles and collected in a scum tank. Then skum is pumped out of scum tank to the inlet of SPI separator by skum return pump. 

This is the basic concept of Magic Angle Spinning NMR the sample is placed in a rotor, spinning at high speed around an axis at 54,7° to the axis of the applied magnetic field. 

Rotor and Cells. In the ultracentrifuge a rotor spins about a vertical axis at speeds ranging from about 600 to 68,000 rpm. 

The unit of absolute viscosity is the pascal second (Pa.s), but centipoise (cP) is generally used as the alternative unit, where 1 Pa.s = 10 cP. Absolute viscosity is usually measured with rotary viscometers where a rotor spins in a container of the fluid to be measured and the resistance to rotation, torque, is measured. Absolute viscosity is an important measurement for the lubricating properties of oils used... 

These orders of magnitude indicate that, in principle, the observed transition temperature as well as the width of the transition should depend on the rotor-spinning frequency. However, to my knowledge, no effects of the MAS centripetal forces on phase transitions were reported to date. 

The cell in the rotor is sector shaped (Fig. 35.17). As the rotor spins, the macromolecule moves outward leaving the pure solvent behind. A moving boundary is established between the solution and the solvent. The position of the boundary can be detected by the difference in refractive index between the two parts of the cell. Using measurements of the positions and V2 at times and 2 we can calculate the value of 5 from Eq. (35.80). Alternatively, if In r is plotted against t, we can obtain the value of s from the slope. 

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