Living colloids

Trivino GC, Klabunde KJ, Dale EB (1987) Living colloidal palladium in nonaqueous solvents. Formation, stability, and film-forming properties. Clustering of metal atoms in organic media. 14. Langmuir 3 986-992... 

Living Colloidal Metal Particles from Solvated Metal Atoms Clustering of Metal Atoms in Organic Media... 

Film Formation. A novel feature of these Au-organic solvent colloids is their film forming properties that can be induced simply by solvent stripping. In this sense they are "living" colloidal particles. Films formed in this way are conductive, but less so than pure metals. (in ) The higher resistance of the films is due to the incorporation of substantial portions of the organic solvent, which can partially be removed by heating, and resistivity then decreases.(M1)... 

A bacterial suspension can be interpreted as a living colloidal system, and the initial step of adhesion involves, at a first approximation, an adsorption phenomenon that takes place between the organic macromolecules that constitute the bacteria outer shell and the carbon surface. Hence, bacteria adsorption can be explained by colloid and surface chemistry theories, which is why this section... 

In Chapter 12 micro-organisms in suspension were referred to as "living colloids". It is to be expected therefore, that microbial fouling will be influenced by cathodic protection. Maines [1993] however, suggests that the picture is far from clear with respect to electrode material, types of organism and the technique adopted for cathodic protection. It would appear that in some situations biofouling is increased and in others it is reduced. Where a biofllm is present it would be expected to modify the electrochemical conditions at the metal surface and thereby influence the metal dissolution reactions [Dexter et al 1989]. 

Relationship.s 80 and 81 reflect the law of so-called thermodynamic retardation near the critical point (van Hove, 1954 de Gennes, 1979, 1980), where concentration fluctuations practically do not disappear and they may be regarded as long-living colloidal particles which was discussed above with other systems as examples. 

C12MG is far too soluble in liquid water to display in its biphasic aqueous mixture s long-lived colloidal structure (such as the vesicles that occur with dichain surfactants). At low temperatures, however, its solubility is sufficiently small that such structures could be more stable. 

In extensively deionized suspensions, tliere are experimental indications for effective attractions between particles, such as long-lived void stmctures [89] and attractions between particles confined between charged walls [90]. Nevertlieless, under tliese conditions tire DLVO tlieory does seem to describe interactions of isolated particles at tire pair level correctly [90]. It may be possible to explain tire experimental observations by taking into account explicitly tire degrees of freedom of botli tire colloidal particles and tire small ions [91, 92]. 

It is also quite an open question whether the second law is applicable to living organisms the fineness of the cell-structure, and the comparatively enormous—almost microscopically visible —molecules of the colloidal substances occurring in the latter, make it not impossible that there are processes going on there which are quite outside the consideration of thermodynamics. 

Overview. Humans living in areas surrounding hazardous waste sites may be exposed to endosulfan primarily via dermal contact with or ingestion of contaminated soils since this compound is found bound to soil particles. Although endosulfan can be found in water as colloidal suspensions adsorbed to particles, ingestion of contaminated finished drinking water is not expected to be a major route of exposure since endosulfan is not very water soluble. Likewise, inhalation exposure to endosulfan via volatilization from contaminated media is not a major route of exposure since endosulfan is not very... 

Clearly the improved understanding of colloidal behaviour within living systems that we are developing offers the eventual prospect of our being able to manipulate such systems. The control of microarchitecture in both living and synthetic systems has many potential applications. The most important aspect is the ability to define the particular conditions under which a certain pattern or structure will be formed such that the products will be uniform. This clearly happens in Nature, but natural systems have been subject to trial and error for considerably longer than any experiment involving synthetic systems. 

A precursor of the studies on electron transfer reactions between short-lived radicals and colloidal particles was the development of a fast pulse radiolysis method to measure. the polarograms of radicals in the 10 s range . After considerable information had been acquired about the electron transfer reactions of a few dozen radicals at the mercury electrode, this compact electrode was replaced by metal colloids somewhat later, by semiconductor colloids These studies led to the detection of the electron-storing properties of certain colloids and of reactions of the stored electrons. 

They do not occur in homogeneous solution, as two radicals encountering each other dimerize or disproportionate. However, the formation of by short-lived radicals can be catalysed by colloidal metals The most detailed investigation has been carried out with colloidal silver Figure 1 shows the mechanism in a... 

Flash photolysis with microwave detection of charge carriers could become an additional technique in the future. The method has not yet been applied to colloids but has been used with small suspended particles. Immediately after the laser flash a conductivity signal was observed which decayed in the 0.1 to 1 microsecond range. The signal was longer-lived for a suspension of TiOj in para-dioxane than in Decalin. Such an effect of the surrounding medium on the decay kinetics of the conductivity indicates that surface states are involved... 

Radiation chemical studies were carried out with an acidic WO3 H O sol stabilized by polyvinyl alcohol It was found that (CH3)2COH radicals inject electrons into the colloidal particles. A long-lived blue color arose and the absorption spectrum showed a rising absorption above 700 nm. This absorption could have been produced by free electrons, although it could not be ruled out that the electrons reduced ions... 

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