Rectangular gel

Rheological measurements were made with rectangular gel samples in a torsion geometry. The gel samples had dimensions of approximately 12 x 4.5 x 28 mm. The measurements were made on a Rheometric Scientific ARES instrument at a frequency of 1 Hz and a scan rate of 2 °C/min. An environmentally controlled chamber permitted determination of the modulus over temperatures from -100 to 70 C. Strain sweeps were conducted at various temperatures to ensure that the modulus was independent of strain. 

Models of regular geometrical pores with rectangular, spherical, cylindrical, and conical shapes have been developed for electrophoresis and gel chromatography media. Figure 7, from Ref 314, gives samples of these uniform structures. These uniform-pore models have been used more extensively in the analysis of gel filtration chromatography. 

Squire [364] and Porath [300,301] developed geometrical pore models for gel chromatography media. Squire considered a gel with a set of conical, cylindrical, and rectangular crevices, and found the pore volume, assumed equal to the partition coefficient K y, to vary as... 

Fig. 71.—Weight fraction (Wg) of gel and concentrations of cross-linked units in the sol (p ) and in the gel (p") vs. the over-all degree of cross-linking (p) for the rectangular primary distribution described in the text. ...

This sheet micro flow reactor (Figure 4.32) was used for investigating spatially two-dimensional effects in reaction media using agar gel induced by electric fields [68]. This device utilizes an adapted Petri dish which comprises a rectangular channel... 

The cross-section of the gel film is a rectangular plate of the dimension of bt. Here b and t represent the width and thickness of the film, respectively. Therefore the moment of inertia of the beam cross-section is given by Eq. 27. 

I adopted the first method using cylindrical gels with a few mm diameter and 10 30 mm long, which were attached to the end of a thin glass capillary and set in a rectangular culture tube filled with pure water. The axis of the cylindrical gel was kept nearly vertical. The culture tube had a pair of flat glass windows, through which the diameter of gel was measured in situ with a microscope as a function of temperature. 

DNA arranges into rectangular superlattice in the low-temperature gel phase of saturated cationic lipids [83, 84]. This is evidenced by two or three diffuse reflections in addition to the set of lamellar reflections these are attributed to DNA ordering both within the layer and across the lipid bilayers, from one DNA layer to another. These reflections index on a centered rectangular lattice. Noteworthy, DNA does not affect the gel-liquid crystalline transition temperatures of the lipoplexes [16, 19, 84]. This transition is associated with loss of the DNA inter-lamellar correlation. 

Figure 1.15 Sol-gel generated catalyst support layer inside rectangular stainless steel microchannels. The support layer (dark line in photo) surrounds the microchannels completely, providing a porous system to be wet impregnated.

For these experiments, some of which were also conducted on the ILL D17 small-angle diffractometer, crystals of n-butylammonium vermiculite exhibiting the fewest obvious structural defects were selected and trimmed to a rectangular cross section with a razor blade. This enabled the surface area, and therefore the applied pressure, to be measured accurately. The samples were then immersed in a dilute solution of n-butylammonium chloride of the desired concentration and allowed to swell freely. After equilibration for at least two days at 7°C, the swollen (or colloidal) gel phase samples were placed into the uniaxial pressure cell shown in Figure 3.1. 

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