BLAS

Blanco Directo process Blanc-Quelet reaction Blanket crepes Bla-S... 

Cera.micA.bla.tors, Several types of subliming or melting ceramic ablators have been used or considered for use in dielectric appHcations particularly with quartz or boron nitride [10043-11 -5] fiber reinforcements to form a nonconductive char. Fused siHca is available in both nonporous (optically transparent) and porous (sHp cast) forms. Ford Aerospace manufactures a 3D siHca-fiber-reinforced composite densified with coUoidal siHca (37). The material, designated AS-3DX, demonstrates improved mechanical toughness compared to monolithic ceramics. Other dielectric ceramic composites have been used with performance improvements over monolithic ceramics (see COMPOSITE MATERIALS, CERAMIC MATRIX). 

The Iron Bla.stFurna.ee, The reduction of iron oxides by carbon in the iron (qv) blast furnace is the most important of all extractive processes, and the cornerstone of all industrial economies. Better understanding of the reactions taking place within the furnace has made possible a more efficient operation through better preparation of the burden, higher blast temperature, and sometimes increased pressure. Furnace capacity has doubled since the 1800s, whereas coke consumption has been reduced by about half The ratio of coke to iron produced on a per weight basis is ca 0.5 to 1. 

Several authors have shown (cf. Gumz, Ga.s Producer.s and Bla.st Furnace.s, Wiley, New York, 1950 and Elhott and von Fredersdorff,... 

In 1994 Yamamoto et al. developed a novel catalyst which they termed a "Brmsted acid-assisted chiral Lewis acid" (BLA) [10] (Scheme 1.14, Table 1.3). The catalyst 7 was prepared from (R)-3,3 -dihydroxyphenyl)-2,2 -dihydroxy-l,l -binaphthyl by reaction with B(OMe)3 and removal of methanol [10a, dj. The Brmsted acid is essential for both the high reactivity of the Lewis acid and the high enantioselectivity - the... 

Among the many chiral Lewis acid catalysts described so far, not many practical catalysts meet these criteria. For a,/ -unsaturated aldehydes, Corey s tryptophan-derived borane catalyst 4, and Yamamoto s CBA and BLA catalysts 3, 7, and 8 are excellent. Narasaka s chiral titanium catalyst 31 and Evans s chiral copper catalyst 24 are outstanding chiral Lewis acid catalysts of the reaction of 3-alkenoyl-l,2-oxazolidin-2-one as dienophile. These chiral Lewis acid catalysts have wide scope and generality compared with the others, as shown in their application to natural product syntheses. They are, however, still not perfect catalysts. We need to continue the endeavor to seek better catalysts which are more reactive, more selective, and have wider applicability. 

Yamamoto et al. have developed a catalytic enantioselective carbo-Diels-Alder reaction of acetylenic aldehydes 7 with dienes catalyzed by chiral boron complexes (Fig. 8.10) [23]. This carbo-Diels-Alder reaction proceeds with up to 95% ee and high yield of 8 using the BLA catalyst. The reaction was also investigated from a theoretical point of view using ab-initio calculations at a RHF/6-31G basis set. 

The four different transition states in Fig. 8.10 were considered with BF3 as a model for the BLA catalyst in the theoretical calculations. It was found that the lowest transition-state energy for the BF3-catalyzed reactions was calculated to be 21.3 kcal mol for anti-exo transition state, while only 1.5 kcal mol higher in energy the syn-exo transition state, was found. The uncatalyzed reaction was calculation to proceed via an exo transition state having an energy of 37.0 kcal mol . The calculations indicated that the reaction proceeds predominantly by an exo transition-state structure and that it is enhanced by the coordination of the Lewis acid. 

Blas-rohr, n., -rShre, /. blast pipe, blast tube. 

Blas-tisch, m. = Blasetisch. -vorrichtung, /. blast apparatus, blower. 

The Food and Drug Administration (FDA) also accept submissions prepared according to the CTD format. However, they have not directly incorporated the CTD format into US regulatory requirements, which are detailed in Title 21 CFR, Part 514.50 in the case of a New Drug Application (NDA), or Title 21 CFR Part 601.2 (a) in the case of a Biologies License Application (BLA). Rather, they have introduced the CTD format via Guidance for Industry documents. The correlation between the requirements in 21 CFR Part 514.50 and the CTD format is shown in Table 6.2. 

Patent information on any patent that claims the drug, if applicable Patent certifications (not for BLA)... 

An action letter must be issued within 180 days of the start of the review, unless an extension has been agreed with the applicant. If the submission is fully acceptable an Approval Letter is issued. However, if there are problems remaining, the applicant vdll receive a Not Approvable Letter (major problems), or an Approvable Letter (minor problems) in the case of an NDA and a Complete Response Letter in the case of a BLA. These not only summarise the deficiencies that exist but also either outline what steps need to be taken to address the issues or explain why the application carmot be approved. A negative action letter will usually trigger an end-of-review meeting between the FDA and the applicant. This allows the applicant and FDA to discuss and... 

Table 3.3 Diels-Alder reactions of ot, -unsaturated aldehydes (67) with cyclopentadiene (18) catalyzed by (R)-BLA 68 and (R)-BLA 69...

Sangameswaran, L, Pales, HM, Friedrich, P and De-Blas, AL (1986) Purification of a benzodiazepine from bovine brain and detection of benzodiazepine-like immunoreactivity in human brain. Proc. Natl. Acad. Sci. USA 83 9236-9240. 

An even more impressive example of catalytic efficiency has recently been disclosed by Novartis (Bader and Bla.ser, 1997). The key step in a proce.ss for the synthesis of the optically active herbicide, (S)-metolachlor involves asymmetric hydrogenation of a prochiral imine catalysed by an iridium-ferrocenyldipho-sphine complex (see Fig. 2.36). 

Microscopic investigation for the presence of blas-tospores or pseudohyphae saline wet mount has a sensitivity of 40% to 50%, while a potassium hydroxide (KOH) preparation has a sensitivity of 50% to 70%.7... 

---