Double needle technique

Wales LR, Stark P, Morishima MS (1981) Percutaneous aspiration biopsy of the lung. The double needle technique. Radiologe 21(3) 150-154... 

Fig. 18.7 Transfer of air-sensitive reagents using the double-ended needle technique.

Ethereal methyllithium from methyl chloride added slowly under N2 with Dry Ice-acetone cooling via the double-ended needle technique (s. H. C. Brown et al., Organic syntheses via boranes, Wiley, 1975, p. 210) to a mixture of B-ethyl-9-borabicyclo[3.3.1]nonane and dry pentane, stirred 10 min. at -78°, allowed to come to room temp., stirred 1.5 hrs., water-cooled, acetyl chloride added drop-wise from a syringe, and stirred ca. 2 hrs. -> c/>y-bicyclo[3.3.0]oct-l-ylethylmethyl-borane (Y 97%) treated with alkaline HgOg in tetrahydrofuran cw-bicyclo-[3.3.0]octan-l-ol (Y 95%). - The above rearrangement by a variety of reducible compds. (in the above case acetyl chloride, which is converted into ethyl acetate) furnishes many compds. containing the d5 -bicyclo[3.3.0]oct-l-yl moiety whidi have previously been difficult to prepare. F. e. s. G. W. Kramer and H. C. Brown, Am. Soc. 98, 1964 (1976) one-pot procedure s. J. Org. Chem. 42, 2832 (1977). 

An alternative to the syringe technique for the transfer of liquids uses the double-ended needle and is suitable when it is not necessary to know precisely the volume of liquid being transferred, or when the volume is being measured in some other way, e.g. by transfer from a septum-capped measuring cylinder. This... 

Cannula techniques air-sensitive materials, 7 components, 6 double tip needles, 9 flexibility, 7 solution transfer, 6-23 speed,7... 

Modifications of the electrospinning technique have been proposed in order to obtain oriented fibers or core-shell nanofibers and nanotubes. The coelectrospinning allows the preparation of core-shell fibers or tubes different polymeric solutions can be injected thought concentric annular needles and electro-spun through the formation of a double Taylor cone. The mixing of the two solutions can be avoided by means of a very fast electrospinning process by which coaxial nano and micro fibers can be obtained with a proper choice of the polymeric materials, the inner core can be removed and nanotubes isolated [328], as shown in Fig. 1.30. 

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