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Hexagonal close-packed (hcp) cobalt nanowires with diameters of 150-300 nm and lengths of up to several hundreds of micrometers have been synthesized by a hydrothermal reduction method. These cobalt nanowires were generated by the reduction of cobalt(II) citrate complexes by hypophosphite (H 2 PO 2 -) in basic solution at 160°C. High-resolution TEM and SAED reveal that the as-prepared Co nanowires

A Hydrothermal Reduction Route to Single-Crystalline Hexagonal Cobalt Nanowires. -The title nanowires with diameters of 150-300 nm and lengths of up to several hundreds of micrometers are hydrothermally synthesized in high yield from mixtures of sodium citrate, CoCl2, NaH2PO2, NaOH, and H2O (autoclave, 160°C, 20 h). The samples are characterized by XRD, SEM, TEM, HRTEM, EDS, and FT-IR spectroscopy. The as-prepared Co nanowires show ferromagnetism with a greater coercitivity than the bulk materials. -(XIE, B.-Q.; QIAN*, Y.; ZHANG, S.; FU, S.; YU, W.; Eur.

Well testing technique in the annulus of a pumping well has been a subject on which great efforts have been made by petroleum scientists and engineers in recent years. Based on the practical situation in our country this paper analyzes and discusses in detail the features of such techniques developed in our country. The paper also describes some testing devices, instruments and equipment used for the well testing in cacing-tubing annulus and puts forward their opinions as to the interpretation of the data obtained from such instruments in the downhole annulus and its application. Thus a valuable basis for the development of well testing techniques in pumping wells in our country is provided.

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