Barium placement

Butadiene-Styrene Copolymers from Ba-Mg-Al Catalyst Systems. Figure 13 shows the relationship between copolymer composition and extent of conversion for copolymers of butadiene and styrene (25 wt.7. styrene) prepared in cyclohexane with Ba-Mg-Al and with n-BuLi alone. Copolymerization of butadiene and styrene with barium salts and Mg alkyl-Al alkyl exhibited a larger initial incorporation of styrene than the n-BuLi catalyzed copolymerization. A major portion of styrene placements in these experimental SBR s are more random however, a certain fraction of the styrene sequences are present in small block runs. 

Sodium softening is used to remove soluble hardness from water, including calcium, magnesium, barium, and strontium. As discussed in Chapter 8.1.6, sodium softeners are commonly used to pre-treat RO feed water to reduce the potential for scaling the membrane with hardness scales. In the next two sections, the placement of the sodium softener, either before or after the RO system, as well as the use of sodium softeners versus antisealants are discussed. 

Fig. 3.7a, b. An 8-year-old patient with recurrent signs of obstruction 4 weeks after stent placement for pyloric stenosis, a A barium study shows obstruction of the outflow at the distal end of the stent due to abutting of the stent end to the wall of the descending duodenum, b There is good flow of barium after placement of a second stent coaxially... 

Some of the recent work in the authors laboratory has shown that catalyst compositions of barium alkoxide salts combined with BuLi as well as with complexes of Mg-Al alkyls also result in low-vinyl solution SBRs (LVSBRs) in hydrocarbon solvent. " Such elastomers have a butadiene portion of ran5-l,4-content as high as 90% and a vinyl content as low as 2%. The comonomer placement in the copolymers is predominantly random. The development and properties of these rubbers will be described more fully in Sections 3 and 4, respectively. 

Sohd BaTiOs has two kinds of prevalent defects oxygen vacancies and barium vacancies. Figure 14.5 gives the relative placement of the phases (noted from 1 to 3) and of the interfaces (noted from a to d). The concentration of species X in phase j close to interface i will be [X(y7)]. 

Figure 14.5. Placement of the phases during the preparation of barium titanate...

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