Specific Cell Characteristics

Cellular materials range in size from 1 |im to 50 |im. Cell populations are classified by a set of morphological, functional and biophysical characteristics. The biophysical characteristics are of particular interest in FFF. Usually, separations in FFF are influenced (but not directed) by surface properties of the sample components (to avoid particle-particle or particle-separator interactions). These properties can be modulated by the use of appropriate carrier-phase modifiers (surfactants). In terms of FFF separations, mass, size and density appear to be the major first order parameters. However, size is generally defined by the radius or the diameter of a sphere whose volume is identical to that of the cell. Size can therefore be deduced accurately if the cell of interest is perfectly spherical. However, this is not usually the case, and the sphericity index, I, is then used:

In this equation V is the cell volume and S is its surface area can be difficult to determine. In terms of cell population, these dimensions are averages and should be associated with a variance. These general

The cleaning procedure involves flushing the channel (ten times the void volume) with a hypo-osmotic carrier phase to destroy the cells, then with a classical deproteinization agent (ten times the void volume) to desorb and destroy the cell and surfactant proteins adsorbed in the FFF separator. Finally the system is flushed again with the hypo-osmostic carrier phase.

Decontamination is performed by allowing a hypochloride solution (3-6°C) to flow through the whole FFF system. The volume used should be three to four times the void volume of the FFF device. Prior to injection the channel should be flushed with ethanol and rinsed with the sterile mobile phase. Decontamination and sterilization can be simultaneous if a 5°C hypochloride solution is used with a 70°C ethanol solution.

Cell Detection, Viability and Recovery

At the outlet of the channel it is necessary to obtain eluted material that retains its integrity, that is the diagnosis of the whole particle. Photometric devices operated in the light scattering mode can be used to follow elution. After fraction collection off-line analyses methods such as microscopy, granulometric or flow cytometry analyses are recommended. Cell specific staining is also possible. Cell viability can be diagnosed by means of specific tests, and recovery must also be clearly defined.

Solar Panel Basics

Solar Panel Basics

Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.

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