Orientational specificity

The high degree of orientational specificity which controls the cycloadditions to (267) of allene [(273) (274) 30 1 ] and acetoxybutenone [rz t/-adducts (278) and (279)] is suggestive of being meaningful in mechanistic terms. Several proposals have been advanced to account for these observations, inter alia a polar ground-state complex of the reactants, (281), which undergoes photoexcitation followed by concerted bond formation to products... 

A useful principle of object-oriented specification (and design) is that the structure of a software system should be based on a well-chosen model of the world with which it deals that approach makes the design easier to update with business changes. Each real-world object (whether physical or more abstract orders, meetings, menus) has its counterpart inside the system. A first step in building an object-oriented program from scratch is therefore to make a business model and then declare it to be the first draft of a type model of the software. The objects and their relationships are used as the type model of the system. 

Kurki-Suonio90] Kurki-Suonio, R., et al. 1990. Object-Oriented Specification of Reactive Systems. In Proceedings of the International Conference of Software Engineering. 

An MO study of triplet coumarin has indicated that the mobile bond order for the 3,4-double bond decreases significantly on excitation (73MI22201). Furthermore, the electron density at C-3 is decreased but is increased at C-4 and hence an explanation of the orientational specificity of the photoaddition of coumarin to 1,1-diethoxyethylene is available (equation 1) (66TL1419). The reactivity of the 3- and 4-positions of triplet coumarin is also substantiated by the high spin-densities calculated for these positions (70JPC4234). 

Unsymmetrically substituted olefins also exhibit a marked orientational specificity in azide addition reactions7,9,12,27,32 the direction of addition is controlled by electronic rather than steric factors.28 Thus unlike acetylenes,33... 

Polymers at interfaces are an important part of a large number of polymeric technological applications. The orientation, specific interactions, and higher order structures of amphiphilic molecules at a quasi two- dimensional plane form the basis of a variety of interesting phenomena [3-6], Scheme 3.1 shows a schematic representation of this behavior. 

The electron-donating nature of this diene confers high reactivity and orientational specificity in its reaction with unsymmetrical dienophiles.5 This fact, coupled with the readily available conversion to the a,(3-un-saturated ketone from the imparted functionality, makes l-methoxy-3-trimethylsiloxy-1,3-butadiene (2) a potentially very valuable reagent in organic synthesis. The general reaction scheme is illustrated below ... 

FIG. 21-36 Marking authorized by the U.S. DOT prior to October 1, 1994 prior to the change to performance-oriented specifications. Marking is found on the bottom head of the drum. 

Axis % of fibres oriented Specific wear rate... 

In conclusion, we are inclined to think that polarised ester molecules are responsible for the propagation in the polymerisation of styrene by di- and trichloroacetic acid. However, we realise that only a new study oriented specifically at understanding the role of the esters and at trying to ascertain the presence or absence of acid-mono-... 

Procedures should be realistic, and any instructions must be scale-oriented. Specific parameters may be necessary for manufacturing areas. For example, cooling or heating times are typically equipment-dependent. Cooling 1 kg in the laboratory in 15 min may take 4 hours for a 40,000-kg batch in the plant. Similarly, filtration of small batches in the laboratory may not provide the necessary information to predict filter life or flow rates needed for large-scale manufacturing. 

In the laboratory of D.W. Cameron the total synthesis of the azaanthraquinone natural product bosttycoidin was undertaken using the Minisci reaction and the intramolecular Houben-Hoesch reaction as the key steps. It is worth noting that the synthesis of specific di- and trihydroxyazaanthraquinones by the Friedel-Crafts acylation is very limited due to the lack of orientational specificity and the lack of reactivity of pyridine derivatives in acylation reactions. 

In Germany, Austria and Sweden, drug-prevention activities are oriented specifically towards very young women and schoolgirls. These initiatives often focus on female identity and how to refuse offers of drugs from boyfriends or other male peers. 

Outer-sphere electron-transfer from BPH2 to 1 involves ion pairing, local ordering of solvent molecules (coordination of water to M ), steric (/-butyl groups in BPH2) and orientational (specific orientations of both Donor and Acceptor) constraints. These phenomena are not consistent with the simplifying assumptions used to calculate essential parameters in theoretical models, such as that of Marcus, that relate standard free-energies... 

In this geometry (figure A1.6) the crystal is oriented specifically so as to bring the incident and reflected beam, for a given hk plane, into the equatorial plane. In this way the detector is moved to intercept the reflected beam by a single rotation movement about a vertical axis (the 20-axis). The value of 6 is given by Bragg s law as sin 1(rf /2). 

Old, new, and future drug discovery paradigms (strategic orientations, specific steps, limiting factors, durations, and costs) U.S. NIH Road Map Initiative treatment and preventative use of drugs. 

Much of the importance of, and interest in, the structural aspects of hydrogen bonds stems from their orientational specificity. This leads to interactions between different molecular species with defined and fixed stoichiometry and directionality. The complementarity or non-complementarity of these interactions may be utilized for the design of materials with desired physical, chemical, or biological properties. The last few years have seen rather intense efforts to understand and exploit these interactions between two or more different molecules. 

The major advantage of thallation is orientational specificity. While thallation is essentially all para to alkyl groups, halides and alkoxy substituents, orientation is almost all ortho to a carboxyl or an ester substituent. We see that such orientation to ester and carboxyl substituents is unusual in that these groups are typically meta-directing in electrophilic aromatic substitution. This behavior can be attributed to an intramolecular interaction involving the electrophilic thallium and the carbonyl group which allows for facile ortho substitution. 

The topography of orientation-specific cells and of ocular dominance columns is remarkably uniform throughout VI, which is surprising because the receptive fields near the fovea are 10 to 30 times smaller than those at the periphery. This phenomenon is called magnification. The fovea maps to a greater relative distance on the surface of VI than does the peripheral retina, by as much as 36-fold [Daniel and Whitteridge, 1961]. In fact, the majority of VI processes only the central 10° of the visual field. Both simple and complex cells in the foveal portion can resolve bars as narrow as 2 min of arc. Toward the periphery, the resolution falls off to 1° of arc. 

Publications oriented specifically to adhesives and sealants are listed in Appendix G. Although there are many publications which do provide feature articles and news items on adhesives and sealants, those trade publications and journals are not listed here for the sake of brevity. Some of the directories in Appendix E will list publications in more detail. 

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