Fusion procedures

Special equipment for the parallel fusion of several samples including automatic pouring of the molten mixtures into water for dissolution or leaching are commercially available. 

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Solvent Extraction. The industrial separation of tantalum from niobium was carried out historicahy by the Marignac process of fractional crystallization of potassium heptafluorotantalate and potassium heptafluoroniobate (15,16) or the long-estabhshed Fansteel process (17), which involved the decomposition of the ore by a caustic fusion procedure. Processors have replaced these expensive processes by procedures based on solvent extraction. This technique was developed in the United States at Ames Laboratory and the U.S. Bureau of Mines (18). Figure 2 shows the flow sheet of an industrial instahation for the hydrometahurgical processing of tantalum—niobium raw materials. 

Joining NonmetaUic Pipe Thermoplastic piping may be joined by a qiiahfied hot-gas welding procedure, a qnalined solvent-cement procedure, or by a qualified heat-fusion procedure. The general welding and heat-fiision procedures are described in ASTM D-2657 and solvent-cement procedures in ASTM D-2855. Two other techniques, for flared joints and elastomeric-sealed joints, are described in ASTM D-3140 and D-3139, respectively. 

It was found that chlorides, chlorates, and nitrates interfere by forming in sol ppts (Ref 6). Later it was found that w sol perchlorates could be analyzed gravimetrically by pptn of the perchlorate ion as tetraphenylarsonium perchlorate (Ksp at 20° = 2.60 0.14 x 10"9). The ppt can be (Tried at 105° and weighed directly (Ref 16). Still more recently a specific perchlorate ion electrode has been developed (Ref 17) which can be used for the potentiometric titration of the perchlorate ion using a soln of tetraphenylarsonium chloride as the titrant (Ref 15). Tetra-phenylphosphonium chloride has been similarly used, but the corresponding Sb compd is too insol in w for practical use (Ref 8), For routine assay of perchlorates for use by the armed forces, a Na carbonate fusion procedure is described in Mil Specs MlL-A-23946 (19 Aug 1964) MIL-A-23948 (19 Aug 1964) (see also under Ammonium Perchlorate). The tetraphenylarsonium chloride procedure has also been proposed for use in Mil Specs (Ref 11)... 

Condensation of 1,3-di-0-acetyl-5-0-benzyl-2-deoxy-2-fluoro-D-arabinofuranose (880) or 3-0-acetyl-5-0-benzoyl-2-deoxy-2-fluoro-D-ar-abinofuranosyl bromide (881) with 2,6-dichloropurine (fusion procedure for the former) gave, respectively, an anomeric mixture of 9-glycosylpurine... 

Applications Basic methods for the determination of halogens in polymers are fusion with sodium carbonate (followed by determination of the sodium halide), oxygen flask combustion and XRF. Crompton [21] has reported fusion with sodium bicarbonate for the determination of traces of chlorine in PE (down to 5 ppm), fusion with sodium bisulfate for the analysis of titanium, iron and aluminium in low-pressure polyolefins (at 1 ppm level), and fusion with sodium peroxide for the complexometric determination using EDTA of traces of bromine in PS (down to 100ppm). Determination of halogens in plastics by ICP-MS can be achieved using a carbonate fusion procedure, but this will result in poor recoveries for a number of elements [88]. A sodium peroxide fusion-titration procedure is capable of determining total sulfur in polymers in amounts down to 500 ppm with an accuracy of 5% [89]. 

What materials must be used as containers for the flux or sample mixture in a fusion procedure Explain. 

Quiroga and co-authors [101] also reported eco-friendly solvent-free approach to the synthesis of fused benzo[fjpyrazolo[3,4-b]quinolines 72 by three-component reaction of 5-aminopyrazoles, aldehydes, and p-tetralone accomplished by fusion procedure (Scheme 32). However, this method was found inapplicable for the similar reaction of a-tetralone - multicomponent procedure allowed obtaining only bispyrazolopyridines 74 instead of benzo[h]pyrazolo[3,4-b]quinolines 73. According to these experimental results, the latter were generated via preliminary synthesis of arylidentetralones 75. 

Joining Nonmetallic Pipe All joints should be made in accordance with procedures complying with the manufacturer s recommendations and code requirements. General welding and heat fusion procedures are described in ASTM D-2657. ASTM D2855 describes general solvent-cementing procedures. 

A series of four standard soils, which are certified reference materials from the Canada Centre for Mineral and Energy Technology, Ottawa, was analyzed by the AAS/fusion procedure to assure that it gave satisfactory results. Excellent agreement with recommended values was obtained. Intercalibration of the two laboratories used for the source materials analyses was accomplished by the parallel analyses of K. Again, excellent agreement was achieved. 

The oleosin fusion procedure was used for the purification of the commercially valuable plant-based blood anticoagulant hirudin in transgenic Brassica carinata and Brassica napus. Hirudin, a natural protein from the medicinal leech Hirudo medicinalis, is superior to other anticoagulants such as heparin. Recombinant hirudin was cleaved from oil-bodies using endoproteinase Factor Xa. Released hirudin was biologically active, as determined by a colorimetric thrombin inhibition assay. 

The most commonly used technique to produce bispecific antibodies from two monoclonal antibodies is by fusing two hybridoma cell lines by conventional cell fusion procedure (Staerz and Bevan, 1986). These cells produce all possible combinations of the heavy and light chains of both antibodies, including the desired bispecific antibody. A limitation is that only part of the antibodies is the desired bispecific monoclonal antibody therefore, further purification is necessary (Van Ravenswaay et al., 1993). 

A glycosylation technique using the condensation of acylated furanoses and pyranoses with purines under the influence of a Friedel Crafts catalyst has found widespread application. The method offers advantages over the fusion procedure as fewer a-D-anomers and 7-glycosy-lated regioisomers are formed. 

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