Direct construction method

Alternatively, the closed-loop frequency response can be obtained from a Nyquist diagram using the direct construction method shown in Figure 6.25. From equation (6.73)... 

Fig. 6.25 Closed-loop frequency response from Nyquist diagram using the direct construction method.

In 1996, a field demonstration of horizontal recirculation wells was conducted at the X-701B site of the Portsmouth Gaseous Diffusion Plant in Piketon, Ohio. Using directional drilling methods, two horizontal wells 234 ft long were installed to a depth of 32 ft. Design and construction costs were estimated to be 1.43 million (D188709, p. 16). 

Two methods for the direct construction of enantiomerically-enriched allylic amines have recently been reported. John Hartwig of Yale University has developed (Angew. Chem. Int. Ed. 2004,43,4797) an Ir complex that effects the coupling of allylic carbonates such as 6 with aromatic amines to give the secondary amine in high . 

Since the development of (he Haber process, many patents were issued to various persons and companies, but essentially all the "direct synthesis" methods are based on the original process—the main differences are in construction of converters and in some minor details. 

Despite growing importance of axially chiral biaryls as chiral auxiliaries in asymmetric synthesis, direct synthetic methods accessing to the enantiomerically enriched biaryls from achiral precursors are still very rare, Application of asymmetric cross-coupling to construction of the chiral biaryls is one of the most exciting strategies to this goal. The reported application... 

The construction of the electrode is simple, fast and reproducible. The electrode proved to be useful for the determination of the enan-tiopurity of S-captopril—raw material as well as for the content uniformity test of Novocaptopril tablets, by direct potentiometric method. The reliability of the analytical information is assured by the RSD values obtained in the uniformity content test. 

Any chemically encoded library requires a double orthogonal chemical strategy, or the construction of elaborate tags/linkers on the solid support prior to the synthesis. Even when these are easily prepared and inert, the synthetic scheme becomes more complicated than direct deconvolution methods, where only the library synthesis is required. Sometimes the tag chemistry and the... 

In consideration of conceivable strategies for the more direct construction of these derivatives, nitriles can be regarded as simple starting materials with which the 3+2 cycloaddition of acylcarbenes would, in a formal sense, provide the desired oxazoles. Oxazoles, in fact, have previously been obtained by the reaction of diazocarbonyl compounds with nitriles through the use of boron trifluoride etherate as a Lewis acid promoter. Other methods for attaining oxazoles involve thermal, photochemical, or metal-catalyzed conditions.12 Several recent studies have indicated that many types of rhodium-catalyzed reactions of diazocarbonyl compounds proceed via formation of electrophilic rhodium carbene complexes as key intermediates rather than free carbenes or other types of reactive intermediates.13 If this postulate holds for the reactions described here, then the mechanism outlined in Scheme 2 may be proposed, in which the carbene complex 3 and the adduct 4 are formed as intermediates.14... 

The direct construction of seven-membered rings via [4+3] cycloadditions is the most attractive strategy for preparing this frequently observed natural product substructure. A great amount of effort has been focused on methods to synthetize the less accessible three-atom component of these reactions. Oxyallyl cations are the most employed intermediates to generate this moiety (see Scheme 13). Alternatively, the use of 2-(silyloxy)acroleins and related compounds in the presence of a LA catalyst as the three-atom component in [4 + 3] cycloadditions has received much interest in the last years (see Scheme 14). 

By the way, the situation with the ElGamal scheme is similar to that with RSA, although that scheme is not directly constructed from trap-door one-way permutations Existential forgery is possible with a key-only attack. However, no method for selective forgery with an active attack is known. 

With this method a new bicyclic ring-forming process has been developed that results in direct construction of the CP-263,114 core system from a readily available /i-keto ester (Scheme 13.16) [44]. 

The direct Cl method was proposed in 1972 by Roos. The idea of this method is to avoid the explicit construction and storage of the large Hamilton matrix. Instead, the eigenvectors are found iteratively. The basic operation in each iteration is to form the vector g = H c directly from the molecular integrals and the trial vector c. The optimum algorithm to form this product... 

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