Phosphates, spiral-wound

A recommended pH range for FT-30 spiral-wound elements was set at 3 to 11 for feedwaters at ambient temperatures. The membrane will tolerate a much wider range of pH for limited periods, and strong mineral acids such as phosphoric or nitric acids can be used for cleaning. Also, dilute solutions of strong bases such as sodium hydroxide or trisodium phosphate can be used with anionic surfactants for cleaning at high pH. 

Radioactive waste management plant Selective actinide extraction Supported liquid membrane Spiral-wound reverse osmosis Solvent extraction Tri-n-butyl phosphate Total dissolved solids Tri-n-octylamine... 

Reasoning from these data, Watson and Crick proposed a double helix as a model for the secondary structure of DNA. According to this model, two nucleic acid chains are held together by hydrogen bonds between base pairs on opposite strands. This double chain is wound into a helix with both chains sharing the same axis. The base pairs are on the inside of the helix, and the sugar-phosphate backbone is on the outside (Fig. 25.8). The pitch of the helix is such that 10 successive nucleotide pairs give rise to one complete turn in 34 A (the repeat distance). The exterior width of the spiral is about 20 A, and the internal distance between 1 positions of ribose units on opposite chains is about 11 A. 

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