Dispersive technique

Instrumentation. The k region was developed usiag dispersive techniques adapted as appropriate from uv—vis spectroscopy. Unfortunately, k sources and detectors tend to be kiefficient compared to those for other spectral regions. 

Leaching Cycle and Contact Method As is true generally, the choice between continuous and intermittent operation is largely a matter of the size and nature of the process of which the extraction is a part. The choice of a percolation or solids-dispersion technique depends principally on the amenability of the extraction to effective, sufficiently rapid percolation. 

It was claimed that the maximum continuous operating temperature in most chemical environments was 120°C and even 140-150°C in some instances. The major chemical applications were in the form of pipe and tank linings and injection moulded valve and pump parts. Coatings could be applied to metals by means of fluidised bed, water suspension and organic dispersion techniques. 

To sum up, the basic idea of the Doppler-selected TOF technique is to cast the differential cross-section S ajdv3 in a Cartesian coordinate, and to combine three dispersion techniques with each independently applied along one of the three Cartesian axes. As both the Doppler-shift (vz) and ion velocity (vy) measurements are essentially in the center-of-mass frame, and the (i j-componcnl, associated with the center-of-mass velocity vector can be made small and be largely compensated for by a slight shift in the location of the slit, the measured quantity in the Doppler-selected TOF approach represents directly the center-of-mass differential cross-section in terms of per velocity volume element in a Cartesian coordinate, d3a/dvxdvydvz. As such, the transformation of the raw data to the desired doubly differential cross-section becomes exceedingly simple and direct, Eq. (11). 

The production of CLS by the melt dispersion technique is based on the melting of the lipid core material together with the lipophilic agent (i.e., phospholipids). Afterward, a warm aqueous solution is added to the molten material and is mixed by various methods (i.e., mechanical stirring, shaking, sonication, homogenization). Then the preparation is rapidly cooled until lipid solidification and the formation of particle dispersion. This method was used by Olbrich et al. [19] to produce the cationic solid lipid nanoparticles to use as novel transfection agent. 

The solvent evaporation method resulted in the production of LS characterized by a smaller size (20 pm mean diameter) but poor mechanical properties in respect to particles with the same composition that were obtained by the melt dispersion technique (170 pm mean diameter). The use of a combination of lipids and a methacrylic polymer (Eudragit RSI00) overcame this problem, resulting in the production of spherical particles with a narrower size distribution and good mechanical properties [53,56],... 

Solvent-mediated dispersion techniques used to create liposomes first involve dissolving the lipid mixture in an organic solvent to create a homogeneous solution, and then introducing this solution into an aqueous phase. The solvent may or may not be soluble in the aqueous phase to effect this process. There also may be components dissolved in the aqueous phase to be encapsulated in the developing liposomes. 

For the preparation of large quantities of liposomes, mechanical dispersion using a commercially available emulsifier is probably the best route. For limited quantities, the use of simple shaking or ethanolic dispersion techniques works well. 

Verita, M., Basso, R., Wypyski, M.T. and Koestler, R.J. (1994). X-ray microanalysis of ancient glassy materials a comparative study of wavelength dispersive and energy dispersive techniques. Archaeometry 36 241-251. 

There are numerous types of instrumentation available for the measurement of XRF, but most of these are based either on wavelength dispersive methodology (typically referred to as WDX) or on the energy dispersive technique (typically known as EDX). For a detailed comparison of the two approaches for XRF measurement, the reader is referred to an excellent discussion by Jenkins [69]. 

The advantages of FTIR over the dispersive technique are 1) it is faster, making it possible to be incorporated into chromatography schemes, as will be seen in Chapters 12 and 13, and 2) the energy reaching the detector is much greater, thus increasing the sensitivity. 

Thus the following work describes our efforts to compare and apply high dispersion techniques to coal liquefaction. 

Howard has applied his method to high-resolution infrared spectroscopic data obtained by dispersive techniques and to both experimental and simulated Fourier interferograms. The method in the latter application explicitly renders the data as they would be observed by an interferometer having a path difference exceeding the mechanical limits of the instrument used for the observation. Details on both the method and its application constitute Chapters 9 and 10. 

Dust dispersion—Aerosols of mineral particles and a few other materials may be prepared by dust dispersal techniques. A number of dust dispersal devices have been constructed. A commonly used device is the Wright Dust Feeder. In this device the dust is compressed into a cylindrical compact, which is placed in an electronically driven mechanism that rotates it and drives it against a fixed knife blade at a fixed rate. Material is scraped off the compact by the blade, entrained in an air stream, and blown against a metal plate to break up particle aggregates. 

Kai T, Akiyama Y, Nomura S, Sato M. Oral absorption improvement of poorly soluble drug using solid dispersion technique. Chem Pharm Bull 1996 44(3) 568-571. 

Matrix solid-phase dispersion techniques have also been suggested for the determination of aminoglycoside residues in bovine tissues (19, 20). The solid-phase material employed in these methods was a cyanopropylsilyl (CN) sorbent. 

Direct elimination of proteins and other matrix constituents from food samples can also be accomplished with matrix solid-phase dispersion or diphasic dialysis membrane techniques. A matrix solid-phase dispersion technique was used for the determination of chloramphenicol in meat (66) and milk (67) using... 

In contrast to the solid-phase extraction approach, only nonpolar Cis-deriva-tized silica has been used as the sorbent in matrix solid-phase dispersion technique. This technique has been successfully applied in the determination of furazolidone in meat (66), milk (181), and swine tissues (180). 

A matrix solid-phase dispersion technique has been further applied for the determination of oxytetracycline, tetracycline, and chlortetracycline in milk (290, 311), using octadecylsilyl- (Cjg) derivatized silica as the solid phase. To facilitate extraction of the tetracycline antibiotics from milk, addition of an equal ratio of EDTA to oxalic acid has been found advantageous. 

When liquid samples such as serum, plasma, milk, or honey are not to be extracted using direct liquid-liquid partitions with organic solvents but through use of solid-phase extraction or matrix solid-phase dispersion techniques, dilution with water (323, 324), phosphate buffer saline (325), or phosphoric acid (326, 327) is often the only sample preparation procedure applied. Milk analysis sometimes requires further pretreatment for fat removal (328). Centrifugation at about 7000g at 4-10 C for 20 min is the usually applied procedure for making the fat floating on top of milk readily eliminated. 

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