Preparation of High Purity Metals by Crystallization Methods

Preparation of Sulfur of High Purity

A mc thod is described for producing sulfur thaL conLains Ie. Lhan 1.3 X lO5 m ole [racLion of li q uid-solu ble, solid-insolubl e impuriLies as dcLermin ed by Lh e fr'eezing point depression . This corr e ponds t.o a purity of 99.999 mole p ercen t . Man y of Lhe impurities, including organic maLLcl', a r(' re moved by o,(ldaLion with s ulfuric and nitric ac ids. The nonvo lati le impuri ties ...

Preparation of High Purity Mullite Ceramics

Recovery of high purity precious metals from printed circuit boards.

Waste printed circuit boards (WPCB) have an inherent value because of the precious metal content. For an effective recycling of WPCB, it is essential to recover the precious metals. This paper reports a promising method to recover the precious metals. Aqua regia was used as a leachant and the ratio between metals and leachant was fixed at 1/20 (g/ml). Silver is relatively stable so the amount o...

Interplanar coupling-dependent magnetoresistivity in high-purity layered metals

The magnetic field-induced changes in the conductivity of metals are the subject of intense interest, both for revealing new phenomena and as a valuable tool for determining their Fermi surface. Here we report a hitherto unobserved magnetoresistive effect in ultra-clean layered metals, namely a negative longitudinal magnetoresistance that is capable of overcoming their very pronounced orbital o...

High-purity preparation of a large DNA dumbbell.

We report on the efficient biochemical synthesis of a large DNA dumbbell starting from a pair of short DNA hairpins with long single-stranded tails of arbitrary sequence. The DNA dumbbell is obtained by enzymatic ligation yielding a 94-bp duplex stem closed at both termini by single-stranded loops of 5 nt. Following ligation, all unligated precursors and monoligated by-products were multiply bi...