Carrier medium

Other special properties. Materials which are thermally sensitive and have a tendency to spontaneous combustion or high inflammability must be ground using an inert carrier medium (e.g. nitrogen). Toxic or radioactive materials must be ground using a carrier medium operating on a closed circuit. 

The carrier medium may be a gas or a liquid. Although the most common gas used is air, inert gases may be used in some cases as indicated above. The most common liquid used in wet grinding is water although oils are sometimes used. The carrier medium not only serves to transport the material through the mill but, in general, transmits forces to the particles, influences friction and hence abrasion, affects crack formation and cohesivity/adhesivity. The carrier medium can also influence the electrostatic charging and the flammability of the material. 

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This section describes equipment for heat transfer to or from solids by the indirect mode. Such equipment is so constructed that the solids load (burden) is separated from the heat-carrier medium by a wall the two phases are never in direct contact. Heat transfer is by conduction based on diffusion laws. Equipment in which the phases are in direct contact is covered in other sections of this Handbook, principally in Sec. 20. 

Stresses acting on micro-organisms in (a) to (c) are derived on the premise that the flow forces originate from the turbulent motion of the carrier medium. In almost all cases, turbulence is assumed to be locally isotropic and homogeneous which greatly simplifies the analysis and allows the application of the Kolmogoroff s theory of turbulence to the problem [81]. The Kolomogoroff micro-scale of turbulence,... 

Tests performed to determine the effectiveness of the CST system for processing shredded wood particles (simulated by sawdust) combined with a carbon-carrier medium encountered several problems, including the following ... 

Preventing the segregation of the carbon-carrier medium and shredded DPE suit material and wood dunnage in the solids feed to the CST to... 

The detection sensitivity is higher in CFA because the samples are not diluted by a carrier medium. 

Select the type of biological indicator to be used in monitoring process lethality. Calibrate the biological indicator in its carrier medium (strip or suspension). 

Radiated emission is a measure of the level of EMI propagated in air by the source. Radiated emission requires a carrier medium such as air or other gases and is usually expressed in volts/meter (V/m) or microvolts per meter (pV/m). 

Dielectrophoretic forces depend on the polarizibility of species, rather than on movement of charges [99]. This allows the movement of any type of droplet being immersed by a dielectrically distinct immiscible carrier medium. Since dielectric forces are generated by spatially inhomogeneous fields, no mechanical actuation is required. In addition to this, dielectrophoretic droplet movement benefits from the general advantages given by droplet microfluidic, i.e. discrete, well-known very small volumes, no need for channels, avoidance of dead volumes and more. 

Two carrier mediums are considered for biomass water and oil. We review the inherent economics of truck vs pipeline transport, and then evaluate a case of field delivery of biomass by short-haul truck to a pipeline terminal. We also evaluate the impact of water and oil absorption by the biomass fuel. Finally, we discuss the prospects for pipeline transport of biomass. 

In addition to these cost elements, transport of biomass for a direct combustion application by water creates a prohibitive drop in the LHV of the fuel because of absorbed water. These issues limit the application of pipeline transport of biomass to large applications that use oil as a carrier medium, or that supply a process for which the heat content of the fuel is not degraded by the requirement to remove absorbed water as vapor, such as a supercritical water gasification process. 

In microfluidic chips, small (nano- and picoliter) liquid volumes can be generated by the formation of aqueous droplets in a carrier medium such as a hydrophobic... 

We have observed that all separations require some form of displacement or transport. An element of that transport must be selective, which as we saw earlier requires the relative motion of solute components through the solvent or carrier medium in which they are contained. We describe the basics of such transport in this chapter. The other major form of transport— bulk or flow transport—will be detailed in Chapter 4. 

Particulates are commonly classified into micro- and nanoparticles based on the size of the particles. Nanoparticles are colloidal particles ranging from 10 to 1,000 run, in which drag may be entrapped, encapsulated, and/or absorbed. Microparticulates are drag-containing small polymeric particles (erodible, non-erodible or ion-exchange resins) within the size of 1-10 /on, which are suspended in a liquid carrier medium. 

Following the possible identification of the presence of LSD, the next stage in the analysis is the use of thin layer chromatography (TLC). This is employed because although it cannot be used to prove the identity of LSD, it can be used as a rapid, cost-effective method to eliminate those samples which gave a positive colour reaction in the presumptive tests but which do not contain this drug. These will be rarer when blotter acids are suspected, but may be more common where other substrates have been used as the carrier medium for the LSD itself. 

A variety of in vitro toxicity tests have been developed to model the effects of toxins on living cells or tissues. In these tests, a carrier medium (such as fetal bovine serum) containing given concentrations, or doses, of a particular toxin are added to cell cultures (cell lines). Various indicators of toxicity, cell morphology transformation, or cell prohferation are then measured after specified periods of time. The cell types used in a particular study can be chosen to approximate the types of cells that would be affected during acmal exposure, such as respiratory cells or tissues. Toxicity indicators include, for example, measures of the percent of viable cells remaining at the end of the test (compared to a control line with no added toxin), and the concentrations various cytokines or other cytoplasmic enzymes induced from the cells by the toxin. Uncertainties with the in vitro toxicity tests include how comparable their results are to those of in vivo toxicity tests, and how well they reproduce actual physiological conditions and processes in the human body (Johnson and Mossman, 2001). 

The applicability of the continuum model is determined by the local value of the non-dimensional Knudsen number (Kn) which is defined as the ratio of the mean free path (lufp) of the heat-carrier medium to the system reference length scale (say thermal diffusion length). Microscale... 

The spraying cooling systems are another example of a canopy , for which one needs to know not only the flow transformation but also the transformation of the canopy itself. A suggestion was made in Section 1.4 to treat air as a continuous carrier medium and the droplets as another continuous medium being carried by the first one. Several relevant mathematical models for such droplet EPR are studied in this chapter. 

Especially for process control it is often necessary to determine particle size distributions of particulate solids that are in motion. The material may be transported either on or by a moving device, e.g. belt, vibrating, or drag chain, screw, bucket, and other conveyors, or in a carrier medium such as gases or liquids it may also fall freely or slide down chutes of various configurations. The best method to obtain a representative sample from such situations is to temporarily divert the entire stream into a container. If the particulate matter... 

Hay JN, Khan A. Review environmentally friendly coatings using carbon dioxide as the carrier medium. J Mater Sci 2002 37 4743-4752. 

Wl. Waldmann-Meyer, H., and Schilling, K., Determination of free protein mobilities by paper electrophoresis with evaporation. II. Evaluation of temperature and concentration increases, influence of the carrier medium, and measurement of serum protein mobilities. Acta Chem. Scand. 13, 13-28 (1959). 

Direct drying is the process of removing this liquid via the mechanism of convective heat transfer. The heat input usually takes the form of preheating a carrier medium (such as air, evaporated solvent or an inert gas) that transfers the sensible heat and acts as an absorbent to take away the liquid in the vapor form. The carrier medium can hold a fixed amount of liquid (saturation) at its defined temperature. The solids release the liquid to the carrier medium as a function of saturation and equilibrium. In essence, the heated gas has a higher saturation affinity for the liquid in the vapor form than does the solid at the gas temperature. 

Typical examples of conventional direct dryers are spray, fluid bed, flash, rotary, belt and continuous tray type. In the former three types, the wet solids are suspended in the carrier medium. In the latter three types, the carrier medium passes slowly across the bed of solids. Additionally, there exists some minor tumbling of the solids through the gas stream (carrier medium). 

There is a nonconventional form of direct drying that is often overlooked or possibly unknown to the designers of the process. It is applicable to almost any of the forms of dryers mentioned in this chapter. The method is to use the solvent or liquid that is being dried as the carrier medium for the... 

Relative humidity—the percentage of water vapor in a gas stream relativeto it s saturation level. Example 100% relative humidity is the complete saturation of a carrier gas stream, whereby any further vapor cannot be absorbed by the gas and will condense or precipitate out in the liquid phase. There is an equilibrium between the liquid-solid mass and the gas stream (carrier medium). This equilibrium is a result of a combination of saturation capability of the medium at a given temperature. At higher temperatures, the carrier medium has... 

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