Anodic systems

02 g bromophenol blue in 0.25 ml ethanol and 0.02 g Py-ronin Y (Pyronin G) in 0.25 ml ddH20 separately dissolved, combined and supplemented with 0.5 ml glycerol or 1 ml 50% sucrose (w/v) in ddH20, filled up with ddH20 to 2 ml 

05 pi of this dye solution are added per 1 pi sample solution of all SDS-PAGE systems with a pH of separation gel 5. The color of bromophenol blue solution switches from yellow-brown to blue-violet. Better than bromophenol blue, especially at separation of small polypeptides, is Orange G (C.I. 16230), because it moves directly with the electrophoresis front. Unfortunately, Orange G is not as easily visible as bromophenol blue or Pyronin Y. 

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In the case of higher protection current densities and protection currents, interference can occur on nearby installations not covered by the protection. The danger of anodic interference must be investigated by making measurements and prevented by taking appropriate measures [7] (see Section 9.2). For the same reasons, anode systems should not be installed near steel-reinforced concrete foundations. 

The anode systems used today consist of a fine-meshed, oxide-covered titanium network [55,56] (see Section 7.2.3), polymer cable anodes of high flexibility... 

Fig. 19-4 Older anode system for roadway plates (a) Silicon iron anodes in coke breeze bed, (b) noble metal lead in conducting bedding in a trench.

Sacrificial anode system (reactive metal anode)... 

Sacrificial anode systems operate without external power source. The anodes are reactive metals such as magnesium and zinc or aluminum alloys. The energy for the process is derived from the anode material. Careful design is required to match the output and lifetime of the anodes with the polarization and life-expectancy requirements of the plant. Sacrificial anode CP is used for offshore platforms, sub-sea pipelines and the inside of ballast tanks on tanker ships. 

For use in high resistivity soils, the most common mixture is 75% gypsum, 20% bentonite and 5% sodium sulphate. This has a resistivity of approximately 50 ohm cm when saturated with moisture. It is important to realise that carbonaceous backfills are relevant to impressed current anode systems and must not be used with sacrificial anodes. A carbonaceous backfill is an electronic conductor and noble to both sacrificial anodes and steel. A galvanic cell would therefore be created causing enhanced dissolution of the anode, and eventually corrosion of the structure. 

Magnetite may also be used in combination with lead or electrodeposited onto a titanium substrate". The latter anode system has been shown to exhibit good operating characteristics in seawater but at present it is only of academic interest. 

A continuous polymer anode system has been developed specifically for the cathodic protection of buried pipelines and tanks. The anode, marketed under the trade name Anodeflex , consists of a continuous stranded copper conductor (6AWG) which is encased in a thick jacket of carbon-loaded polymer, overall diameter 12-5 mm. To prevent unintentional short circuits an insulating braid is sometimes applied to the outer surface of the conductive polymer. 

The various anode systems used specifically for reinforced concrete cathodic protection have been discussed in recent literature and... 

Schutt reported that the coke breeze specification and conditions in which the mix is prepared are important factors in determining the optimum operation of the conductive cement mix, whilst further details on the coke breeze asphalt mix composition are given by AndersonConductive concrete mixes, with a polymer binder have also been developed as an anode system specifically for reinforced concrete cathodic protection systems . 

Failures due to delamination of the gunite coating have been reported in the USA, but have not been observed to any significant extent in F.urope although some early failures of the anode system have been associated with high local current densities in areas of low concrete cover and high moisture or salt contentThe major application of this anode system is therefore on structures that are relatively dry with a uniform current requirement. 

These consist of a number of parallel slots cut into the concrete surface. Each slot is then filled with a secondary anode of carbon/graphite fibres embedded in a conductive polymer grout. The current to each of these secondary anode systems is provided by a primary anode of platinised niobium wire placed in slots filled with conductive polymer which acts as the primary anode, these slots intersecting each slot of graphite fibre/conductive polymer at right angles. 

These systems have not been installed to any significant extent and have now been superseded by conductive paints, conductive polymers or titanium mesh anode systems. 

Wyatt, B. S., Anode Systems for Cathodic Protection of Steel in Concrete , paper 23, Cathodic Protection Theory and Practice, 2nd International Conference, Stratford-upon-Avon, UK, June (1989)... 

The cathodically protected primary structures may be the hulls of ships, jetties, pipes, etc. immersed in water, or pipes, cables, tanks, etc. buried in the soil. The nearby unprotected secondary structures subjected to interaction may be the hulls of adjacent ships, unbonded parts of a ship s hull such as the propeller blades, or pipes and cables laid close to the primary structure or to the cathodic-protection anode system or groundbed. 

Crosnier O., Brousse T., Devaux X., Fragnaud P., Schleich D.M. New anode systems for lithium ion cells. J.Power Sourc.2001 94 169-74. 

A review of photo-assisted electrolysis studies performed with p-type semiconductor photocathode/dark Pt anode systems suggests that a complementary phenomena arising from the presence of OH ions produced during the reduction half-cell reaction,... 

Lower self-discharge rates, especially in primary metal anode systems such as Li/Mn02 and Li/S02. 

The sacrificial anode system consists of a galvanic cell system in which the anode is made of a more active metal than the structure. The anode is attached to the structure and the anode output current may be measured. Magnesium and zinc anodes are commonly use in underground operations, zinc and aluminum alloy anodes in salt water. 

Galvanic anode systems are generally used in well-coated electrically isolated structures, offshore structures, ship hulls, hot-spot pipeline protection, heat exchanger water boxes and other environments of resistivity below 10000 Q cm. 

The sacrificial anode system typically uses magnesium, zinc or aluminum and their alloys Figure 7.25. These metals or alloys act as anodes when coupled with steel and its... 

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