Spin-sorting process

Superconductors are a special sort of material which conducts with no resistance below a temperature called the critical temperature (Figure 5.14). As we have seen, the conductivity of conductors falls with increasing temperature, as the lattice vibrations increase and hinder the flow of current. In a superconductor the electrons are thought to move in pairs with the lattice vibrations in a concerted process, so there is no resistance. Bardeen, Cooper and Schrieffer proposed a theory (called BCS theory) to explain superconductivity involving the movement of electrons with opposite spin in pairs. When an electron moves past a lattice point. 

These initial results on the temperature dependence of 13C spin-lattice relaxation times indicate the importance of VT-MAS experiments in the interpretation of relaxation pathways and suggests such experiments will help sort out the various motional processes. 

Non-reactions of the sort exemplified by the valence tautomerism of 3,4-homotropylidene obviously cannot be studied by conventional methods which involve measuring the rate of disappearance of a starting material or rate of formation of a product. However, many of these degenerate rearrangements occur so rapidly that they cause averaging of some or all of the nmr frequencies of protons in the substrate at temperatures which are experimentally accessible. The rates of these processes can be estimated by use of temperature-dependent line broadening or spin-echo nmr techniques. 

Reclaimed fibres can be manufactured from a variety of textile waste. Both quality and processability of such fibres depend on the kind of waste. Well-known are the pure sorted fibres of high-quality which are achieved from spinning-fibre waste. In contrast, reclaimed fibres made from end-of-life textiles are of much poorer quality. They will rarely be found of homogeneons fibre type. 

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