Chemical structure handling systems developments

Most large companies are developing office automation systems, as an adjunct to their word processing capability, using local area networks for electronic mail. If they have a need for chemical structure handling within those facilities, in other words if they have chemical documents or reports which they want to send through an electronic mail system, the standard facility should be used and the chemical application software should fit within the standard facility. 

For obvious reasons, we need to introduce surface contributions in the thermodynamic framework. Typically, in interface thermodynamics, the area in the system, e.g. the area of an air-water interface, is a state variable that can be adjusted by the observer while keeping the intensive variables (such as the temperature, pressure and chemical potentials) fixed. The unique feature in selfassembling systems is that the observer cannot adjust the area of a membrane in the same way, unless the membrane is put in a frame. Systems that have self-assembly characteristics are conveniently handled in a setting of thermodynamics of small systems, developed by Hill [12], and applied to surfactant self-assembly by Hall and Pethica [13]. In this approach, it is not necessary to make assumptions about the structure of the aggregates in order to define exactly the equilibrium conditions. However, for the present purpose, it is convenient to take the bilayer as an example. 

Density functional theory (DFT) is today a very powerful tool in the study of electronic structures of molecules. Advancements in DFT, in particular the development of Becke s 3-parameter functional (B3LYP), together with the nearly exponential growth of computer power, have made it possible to treat ever larger systems at a reasonable level of accuracy. Using the B3LYP with a medium-sized basis set, one can routinely handle systems containing more than 100 atoms today, a development that has opened the door for many applications. One of the fields that quantum chemical methods have had very positive impacts on in recent years is the study of enzymatic reaction mechanisms. 

Several groups have a special interest in chemical information handling, in particular the subjects of chemical structure storage and computer-assisted chemical synthesis. The most remarkable French contribution in this area is the DARC system developed by Jacques-fimile Dubois for molecular encoding and chemical information retrieval. ... 

DEVELOPMENT OF AN INTEGRATED SYSTEM FOR HANDLING CHEMICAL STRUCTURES AND ASSOCIATED DATA... 

Glaxo Group Research began developing a system, CBIS (Chemical and Biological Information System), for handling chemical structures and related data, about three years ago. 

In the late 1970s, CAS began developing a. software sy.stem. called Messenger, to address the need for online access to its chemical information. Initially the system was targeted towards access to chemical structure information but handling text information was added shortly after the original system was created. 

The problem of poor retrieval precision, and the development of search systems based on unambiguous (complete) representations of the structure has led to the general demise of fragment codes as a primary representation of chemical structures, at least for specific compounds. However, hidden from the user they remain an important component of structure search systems, and a few user-visible fragment-code systems continue to be used in the handling of Markush structures from chenaical patents these are discussed in more detail in Markush Structure Searching in Patents. 

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