Structural framework

Glue was also used to join the numerous small plywood and wood details necessary to fabricate the structural frameworks typical of early aircraft. Fig. 1 shows a monoplane wing circa 1930 fabricated primarily from wood that was joined via more than one thousand glued joints [2]. Note the many small stringers and gussets bonded together to form the ribs and spars of the wing. 

The structures of chalcogen-nitrogen compounds are frequently unpredictable. For example, the reactions of heterocyclic systems often result in substantial reorganization of their structural frameworks, e.g. ring expansion or contraction. The formation of acyclic products from ring systems (or vice versa) is also observed. 

Metal chalcogenides, apart from their technological significance in industrial applications, have played an important role in the development of new synthetic concepts and methods in the area of solid-state chemistry. A great example is alkali metal intercalation into TiS2 (Chap. 6) first reported three decades ago, which highlighted the then-novel synthetic approach called soft chemistry chimie douce). This low-temperature process allows for new compounds to be obtained while retaining the structural framework of the precursor. Related to this concept is the... 

Ramesh, T. S., Shum, S. K., and Davis, J. F., A structured framework for efficient problem solving in diagnostic expert systems, Comput. Chem. Eng. 12, 891 (1988). 

Dppm has been used widely in coordination chemistry. Silver(I)-dppm complexes have been reported in several ratios and they present different structural frameworks. Due to the bite angle... 

Therefore both symmetrical configurations of the hydroxy functions in the host molecule allow the helical tubuland structure. The unsymmetrical epimer anti-2,, syn-7-dihydroxy-2,7-dimethyltricyclo[4.3.1.13-8]undecane (10), the hybrid of 2 and 8, does not possess a molecular twofold axis (or pseudo twofold axis) or the conformation of C—O bonds of Fig. 5, and would not be expected to fit into the helical tubuland structure framework. Its crystal structure is indeed different, with infinite zig-zag sequences of hydrogen bonds constructing a non-including lattice 14). 

The [6.5.5]-ring fused tricyclic motif is found in many natural products, and has therefore become an important target in synthesis. A convenient access to this structural framework is offered by a radical domino procedure published by the Nagano group [41]. This reaction of optical pure dibromoacetal 3-85 led to the desired tricycle 3-87 via 3-86 as a single diastereoisomer in a very respectable yield of 94% by applying classical radical conditions (excess tributyltin hydride/AIBN, irradia-... 

The collagen fibers leave small compartments where apatite nanocrystals are deposited during a controlled biomineralization process [20]. The collagen acts as a structural framework in which plate-like nanocrystals of carbonated hydroxyapatite (CHA) are embedded to strengthen the bone. The chemical formula of biological CHA can be represented as follows ... 

G. Meng and K. Fiitterer, Structural framework of lfuctosyl transfer in Bacillus subtilis levansucrase, Nat. Struct. Biol., 10 (2003) 935-941. 

The reactions of heterocyclic chalcogen-nitrogen systems often result in substantial reorganization of their structural frameworks. Spectroscopic techniques alone are rarely sufficient to provide decisive structural information, and X-ray crystallography has been of paramount importance in the development of chalcogen-nitrogen chemistry. The structural chemistry of Se-N and Te-N compounds has been reviewed.19... 

Molecular structures Linear structures Layer structures Framework structures Substructures... 

Kuwajima K., Yamaya H., Miwa S., Sugai S. and Nagamura T. Rapid formation of secondary structure framework in protein folding studied by stopped-flow circular dichro-ism. FEBS Lett. (1987) 221(1) 115-118. 

J. Gertler and D. Singer. A new structural framework for parity equations-based failure detection and isolation. Automatica, 26 381-388, 1990. 

The most commonly employed crystalline materials for liquid adsorptive separations are zeolite-based structured materials. Depending on the specific components and their structural framework, crystalline materials can be zeoUtes (silica, alumina), silicalite (silica) or AlPO-based molecular sieves (alumina, phosphoms oxide). Faujasites (X, Y) and other zeolites (A, ZSM-5, beta, mordenite, etc.) are the most popular materials. This is due to their narrow pore size distribution and the ability to tune or adjust their physicochemical properties, particularly their acidic-basic properties, by the ion exchange of cations, changing the Si02/Al203 ratio and varying the water content. These techniques are described and discussed in Chapter 2. By adjusting the properties almost an infinite number of zeolite materials and desorbent combinations can be studied. 

Method A involves a deductive search for all credible ways an occurrence could arise using timeline construction and a simplified fault tree approach. It can be viewed as an integrated method for systematically searching for all underlying root causes. The structured framework helps the investigator to keep on track, reach sufficient depth, and not stop prematurely at the symptoms or apparent causes. 

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