Environment oxygen-free

Woese chose the name archaebacteria because these microorganisms grow best under conditions which were probably found on the primeval Earth between 3.5 and 4 billion years ago hot boiling water and thermal vents, highly acidic environment, oxygen-free atmosphere and high salt concentrations. 

Anoxic environment is described by values Eh < -0.1 V, practically total absence of unfixed oxygen and elevated content of reduced forms of compounds. Under this environment oxygen-free breathing becomes the basis of life-sustaining activity for microorganisms, among which an ever greater role is played by archaebacteria. With this environment are associated two levels of detrital trophic chain. 

Silver reduces the oxygen evolution potential at the anode, which reduces the rate of corrosion and decreases lead contamination of the cathode. Lead—antimony—silver alloy anodes are used for the production of thin copper foil for use in electronics. Lead—silver (2 wt %), lead—silver (1 wt %)—tin (1 wt %), and lead—antimony (6 wt %)—silver (1—2 wt %) alloys ate used as anodes in cathodic protection of steel pipes and stmctures in fresh, brackish, or seawater. The lead dioxide layer is not only conductive, but also resists decomposition in chloride environments. Silver-free alloys rapidly become passivated and scale badly in seawater. Silver is also added to the positive grids of lead—acid batteries in small amounts (0.005—0.05 wt %) to reduce the rate of corrosion. 

It is claimed that the cured materials may be used continuously in air up to 300°C and in oxygen-free environments to 400°C. The materials are of interest as heat- and corrosion-resistant coatings, for example in geothermal wells, high-temperature sodium and lithium batteries and high-temperature polymer- and metal-processing equipment. 

Activation by a metal surface also takes place in the commercially important anaerobic adhesives. These one-part adhesives are stable in the package, but cure quickly in an oxygen-free environment such as a tightly controlled bond line. Important applications include thread-locking, sealing, retaining, and some structural bonding [111]. A representative model formulation has recently been described [112] (Fig. 3). 

The set-up of an organic LED at first sight appears to be very simple. However, in actuality the preparation of LEDs is rather sophisticated and requires careful and clean processing where many steps have to be performed in a dust- and oxygen-free environment. The performance of the LEDs strongly depends on the preparation conditions and this therefore complicates any comparisons made of different groups on the same LEDs. This must be taken into account as well as... 

P 45] The entire flow system was put in a glove-box in an oxygen-free environment (< 1 ppm, v/v) [1]. A quaternary feed system was used to provide different comonomer additives dissolved in toluene that are mixed with ethylene (25 h) in a mixer. 

Reduction in chemical exposure (oxygen-free environment, little sample degradation)... 

Dead bodies can be naturally mummified under a variety of environmental conditions, such as (1) at extremely low temperatures, about and below the freezing point of water, in extremely cold regions of the world (2) in very dry and hot environments, as in desert areas and in some caves and rock shelters or (3) under anaerobic (oxygen-free) conditions, as in bogs (see Chapter 8). 

Some crude oils contain components which can oxidize and change wettability (12, 25) so tests on reservoir oil samples must be performed in an oxygen-free environment. Exposure to air had a marked effect on the wetting cycle of one crude oil discussed below. 

Methanogens, may be the Earth s oldest organisms, produce methane from carbon dioxide and hydrogen. They can survive only in an anaerobic (i.e., oxygen-free) environment and have been found in ocean trenches, in mud, in sewage, and in cow s stomachs. 

The regeneration process results in the chemical reduction of the adsorbed NO compounds into nitrogen and water vapor. To accomplish the catalyst regeneration in an oxygen-free environment, the system is composed of several separate modules which are alternatively absorbing NO or operated in the regeneration mode. 

Most repository sites under consideration for commercial spent fuel disposal are in reducing environments, such as in Boom clay formations of the Mol site, Belgium, where U02 is thermodynamically stable. In oxygen-free conditions, Spahiu et al. (2002) have shown that fuel in an... 

Co-precipitation in Aqueous Medium - Despite its effectiveness, the alkoxide method presents some drawbacks for industrial scale-up the high cost of the starting reactants and the requirement for water-free and oxygen-free environment for the alkoxide solutions. 

All further manipulations from here on must be done in an oxygen-free environment (a < 1 ppm 02 dry box as monitored by a Vacuum Atmospheres 02 analyzer). Necessary items for the drybox experiments should be assembled before the next step of the synthesis. 

In the different stages of their life cycle, parasitic flatworms have to adapt their behaviour and metabolism to the different environments they encounter (Table 20.1). The most important variations in the environment are the availability of food and oxygen. Free-living stages do not gather food and are therefore... 

Baxendale and Wilson (1957) reported that in an oxygen-free environment Fenton s reagent initiates very rapid polymerization of methyl acrylate, methacrylic acid, methyl methacrylate, acrylonitrile, and styrene, and the... 

The reaction must be performed in a dry, oxygen-free environment although the product is not sensitive to air or moisture, the intermediate C5HJ is. Cyclopentadiene is added dropwise to a stirred slurry of KOH powder and 1,2-dimethoxyethane. A solution of FeCl2.4H20 in dimethyl sulphoxide (CH3)2SO is then added. The choice of solvents is determined by obvious considerations of solubility and miscibility, and chemical inertness towards the products and intermediates. Dimethyl sulphoxide is a fairly weakly-coordinating aprotic solvent, easily displaced by C5H from Fe(II). A mixture of aqueous HC1 and crushed ice is then added this neutralises the KOH (the ice absorbs the heat evolved) and causes the precipitation of ferrocene, which is (predictably) insoluble in water. The crude product is purified by sublimation. 

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