Gel-like structures

Replicas of the tomato cell walls are very similar to those of onion parench5una cell walls but replicas of the DCB-adapted walls did not show the structure of the walls clearly. The principle components of the adapted walls are shorter thinner fibres which seemed to form a gel-like structure with little evidence of long cellulosic microfibrils characteristic of the unadapted cells. It is possible that such a gel will bind water more strongly and reduce the amount of etching that takes place, resulting in a less well-defined replica (2). 

Scheme 5.7 Encapsulation of enzyme microcapsules into a gel-like structure (host gel bead) resulting in a capsules-in-bead microreactor. Reproduced from [20] by permission of The Royal Society of Chemistry.

The property possessed by certain colloids of forming a gel-like structure on standing but which revert to a liquid form when subjected to agitation. The term has also been applied to the stiffening effect shown by uncured rubber compounds containing fillers, particularly carbon black. 

In the course of further work on characterizing the MCC sols it was found that the CCC of a variety of salts varied both with the solids content and temperature. Investigation of these parameters forms the basis of the study. It will be shown that as a result of particle shape, concentration and surface characteristics, coagulation leads to a gel-like structure. On further addition of salt the coagulated gel-like structure aggregates into floes that are irreversible. In this paper, we outline the experimental parameters which lead to these phenomena and present some possible explanations. 

This study has shown that MCC forms a gel-like structure at low solids concentration in the presence of salt. It has also been known for a considerable time (20) that MCC forms aqueous gels and pastes but at much higher solids concentration. It would appear that further studies with the MCC gel in dilute form may elucidate the mechanism of gelation more definitively. 

For cells that are embedded in macroscopic gel-like structures such as floes, biofilms or other porous media such as soil or sediment aggregates, mass transport to the cells can decrease due to ... 

These results are simply explained in the patterns of Figure 9 in the compact complex, the marker (M) is wedged in between the polymer sequences and its mobility is low. In the gel-like structure the mobility of the marker is not affected, because the marker is mainly surrounded by sovlent molecules since the cross-linking between macromolecules is very low. Polarized luminescence results lead to confirmation of the complex structure proposed from visco-metry studies. 

Figures 7, 8 and 9 are plots at 25 C of specific conductance and density versus volume fraction of methanol in 2/1 triolein/ surfactant systems which are 4/1 molar ratios of 2-octanol to bis(2-ethylhexyl) sodium sulfosuccinate, triethylammonium linoleate and tetradecyldimethylammonium linoleate, respectively. For each surfactant system, a maximum for specific conductance and a minimum for density was observed at the same volume fraction, but this volume fraction of methanol varied between the three surfactant systems. At volume fractions of methanol above these abrupt changes, each system exhibited translucence, and it appears that gel-like structures form. These data are consistent for microemulsion structures that are based largely on geometric considerations (16-18).

If 0.01 mole of caffeine and 0.01 mole of pyrogallol are dissolved in 100 ml. of water at 60°C., a 1 1 crystalline complex will appear as the solution cools. Long needle-shaped crystals growing radially from central nuclei cause the entire solution to solidify into a gel-like structure with the fibrous appearance of mold (Figure 1). 

Figure I. Formation of caffeine-pyrogallol crystalline complex by cooling a saturated aqueous solution from above room temperature. Left, homogeneous solution, 0.1M in each component, above room temperature center, preliminary crystallization near room temperature right, gel-like structure of complex crystals after standing at room temperature for one day...

Instead of the conventional gel-like structures, that swell in contact with a solvent, cation exchangers may be synthesized as a macroreticular polymer. 

However, another explanation for the differences in behavior between carbohydrates could be their ability to develop a gel-like structure in solution able to... 

In higher organisms epithelia are covered by a protective gel layer defined as mucus. By weight, mucus consists mainly of water (95-99.5%) in which the mucous glycoprotein mucin (0.5-5 /o) is dispersed. Mucins are the major components responsible for the gel-like structure of the mucus. They possess a linear... 

The photochemical treatment leads to an increase of the average size of the QDs from 5.7 nm for Zno.9Cdo.1Se to 8 nm and to a broadening of the size distribution after the treatment as it was investigated by transmission electron microscopy (TEM) [6]. It is worth to note that during the treatment process the 3D gel-like structures observed for CdTe QDs [7] are formed from the alloyed... 

---