Buttressing

In a study of the nitrosation of camphor-3-glyoxylic acid (89), Chorley and Lapworth isolated a compound whose structure (90) has recently been clarified by Hatfield and Huntsman. Decarboxylation and ring expansion occur and the reaction is rationalized in the sequence 89 90. The buttressing effect of a methyl group on... 

The buttress dam uses much less concrete than the gravity dam, and also relies on its shape to transfer the water load. Buttress dams were developed in areas... 

Figure 4-371. Buttress thread casing and coupling. (From Ref [51].) From API Spec 5A, 35th Edition, March 1981, Ref, [151], p. 25.

Buttress threads are designed to resist high axial tension or compression loading in addition to offering resistance to leakage. 

Figure 4-374. Buttress thread configuration for 16-in. outside diameter and iarger casing. (From Ref. [54].)...

Note Most buttress thread couplings will not develop the highest minimum joint strength unless couplings of the next higher order are specified. (See API Specification 5A for more detailed information.)... 

Buttress Thread Casing Coupling Dimensions, Weights, and Tolerances... 

Buttress Thread Casing Joint Strength. Buttress thread casing joint strength is calculated from formulas 4-318 and 4-319. The lesser of the values obtained from the two formulas governs. 

Moldable holes and inserts can complicate molding and may require extra postmolding operations. Thus, the most economical designs are those that minimize the number of holes. With many plastics, both external and internal threads can be molded, but sharp V threads should be avoided because they can cause the plastic to bridge, resulting in incomplete thread fill. Rounded or modified buttress threads will allow improved thread fill. 

The transition state for disproportionation requires overlap of the p C—H bond undergoing scission and the p-orbital containing the unpaired electron.18 This requirement rationalizes the specificity observed in disproportionation of radicals 29 (Section 1.4,2) and provides an explanation for the persistency of the triisopropylmcthyl radical (33) and related species (Section 1.4.3.2).166 In the case of 33, the P-bydrogens are constrained to lie in the nodal plane of the p-orbital due to stcric buttressing between the methyls of the adjacent isopropyls. 

Easy availability of ultrafast high intensity lasers has fuelled the dream of their use as molecular scissors to cleave selected bonds (1-3). Theoretical approaches to laser assisted control of chemical reactions have kept pace and demonstrated remarkable success (4,5) with experimental results (6-9) buttressing the theoretical claims. The different tablished theoretical approaches to control have been reviewed recently (10). While the focus of these theoretical approaches has been on field design, the photodissociation yield has also been found to be extremely sensitive to the initial vibrational state from which photolysis is induced and results for (11), HI (12,13), HCl (14) and HOD (2,3,15,16) reveal a crucial role for the initial state of the system in product selectivity and enhancement. This critical dependence on initial vibrational state indicates that a suitably optimized linear superposition of the field free vibrational states may be another route to selective control of photodissociation. 

Jet lag loosens the moorings of your everyday mind. I m thinking about the ruins that are all I ve ever known of the chapel at the Chantry, the thick stumps of flint and stubby buttresses that were once walls the tarry beams and props supporting the wall of the house that once joined it the tiled floor, with the white harts and fleurs-de-lis still visible, though the grass creeps over them. Once I dug some tiles up in search of buried treasure, and found only earth and worms. 

One of Alphapharm s witnesses further buttressed the court s conclusion, "acknowledging that [compound (2)] had the negative side effects of increased body weight and brown fat" and that "a compound with such side effects would presumably not be a suitable candidate for treatment of Type II diabetes [36]."... 

The Harmata group also found that certain ort/w-bromocinnamates underwent a Michael addition during the course of the Buchwald-Hartwig reaction. This one-pot process produced the same products as the two step process and with the same, complete stereoselectivity. For example, this was first observed with bromocinnamate 107, where the reaction with (7 )-77b afforded a 53% yield of sulfoximine 108 as well as a 36% yield of benzothiazine 95 under standard coupling conditions (Scheme 27). The cyclization was attributed to a buttressing effect of the ortho-methoxy in bromocinnamate 107. This presumably favored a conformation that placed the methyl group of its sulfoximine functionality near the p-carbon of the a,P-unsaturated ester, thus favoring cyclization. 

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