Diversity methods

The 2(lH)-pyrazinone system has received increased interest in the past two decades by both synthetic and biological research, due to its presence in a variety of natural and non-natural products as well as pharmacologically active compounds. The easy and diverse methods for the generation of this versatile scaffold make it a prime choice for the current pharmaceutical research hke thrombin inhibitors, substance P antagonists, etc. The rich 1,4-azadiene... 

In order to facilitate the comparison of the effectiveness of the very diverse methods, turnover numbers (TON), and/or turnover frequencies (TOF) (if they were given by the author or could be calculated based on their data) are sum-... 

The field of carbon nanostructure research is vast and novel, and it experienced a major breakthrough after the discovery of fullerenes in 1985 [1], and their subsequent bulk synthesis in 1990 [2]. This event opened the minds of various scientists towards discovering novel carbon allotropes. Promptly, yet another allotrop of carbon was observed by Iijima [3], although it had previously been produced by M. Endo et al. in the 1970s by chemical vapor deposition (CVD) [4]. The most recent important advance in the quest for novel forms of carbon constitutes the isolation of graphene layers [5], which exhibit unique and exceptional electrical properties [6]. In addition, graphene nanoribbons have recently been synthesized and produced using diverse methods [7]. 

Schnur, D. and Venkatarangan, P. Applications of cell-based diversity methods to combinatorial library design. In Combinatorial Library Design and Evaluation, Ghose, A.K. and ViswADHAN, V.N. (Eds). Marcel Dekker, Inc, New York, 2001, 473-501. 

Wide spectrum of degradable substances and diverse methods of biodegradability. 

Diverse methods can be used to identify compounds with similar pharmacological profiles, and application of these methods is subjective. There are many ways to work with the profile data and the results can differ greatly depending on which methods are used. We will summarize some methods that in our experience have yielded the most satisfying results from a biological point of view. 

Evaluation of Molecular Similarity and Molecular Diversity Methods Using Biological Activity Data... 

The concepts of molecular similarity (1-3) and molecular diversity (4,5) play important roles in modern approaches to computer-aided molecular design. Molecular similarity provides the simplest, and most widely used, method for virtual screening and underlies the use of clustering methods on chemical databases. Molecular diversity analysis provides a range of tools for exploring the extent to which a set of molecules spans structural space, and underlies many approaches to compound selection and to the design of combinatorial libraries. Many different similarity and diversity methods have been described in the literature, and new methods continue to appear. This raises the question of how one can compare different methods, so as to identify the most appropriate method(s) for some particular application this chapter provides an overview of the ways in which this can be carried out, illustrating such comparisons by,... 

There are two bases for the comparison of similarity and diversity methods. It is possible to compare the efficiency of methods, i.e., the resources, typically computer time and computer memory, necessary for the completion of processing. Considerations of efficiency, in particular, theoretical analyses of computational complexity, are important in that they can serve to identify methods that are unlikely to be applicable given the rapidly increasing sizes of current and planned chemical datasets. Here, however, we restrict ourselves to comparing the effectiveness of similarity and diversity methods, i.e., the extent to which a method is able to satisfy the user s requirements in terms of identifying similar or diverse sets of compounds. More specifically, we focus on evaluation criteria based on the availability of bioactivity data for the molecules that are being processed, where the data can either be qualitative, i.e., a categorical (usually binary) variable, or quantitative, i.e., a real-valued variable. The discussion here considers only the criteria that can be used for comparative studies the reader is referred elsewhere for the results of such studies. 

Many of the early evaluations of the effectiveness of diversity methods used structure-based diversity indices, such as functions of intermolecular dissimilarities in the context of distance-based selection methods or of the numbers of occupied cells in partition-based selection methods (4). A wide range of such indices has been reported, as discussed in the excellent review by Waldman et al. 

They do, however, have the limitation that they quantify diversity in chemical space, whereas the principal rationale for molecular diversity methods is to maximize diversity in biological space (35), and we hence focus here on indices that take account of biological activity. 

Abstract Palladium-catalyzed oxidation reactions are among the most diverse methods available for the selective oxidation of organic molecules, and benzoquinone is one of the most widely used terminal oxidants for these reactions. Over the past decade, however, numerous reactions have been reported that utilize molecular oxygen as the sole oxidant. This chapter outlines the fundamental reactivity of benzoquinone and molecular oxygen with palladium(O) and their catalyst reoxidation mechanisms. The chemical similarities... 

Since it is relatively easy to transfer molecules from bulk liquid to the surface (e.g. shake or break up a droplet of water), the work done in this process can be measured and hence we can obtain the value of the surface energy of the liquid. This is, however, obviously not the case for solids (see later section). The diverse methods for measuring surface and interfacial energies of liquids generally depend on measuring either the pressure difference across a curved interface or the equilibrium (reversible) force required to extend the area of a surface, as above. The former method uses a fundamental equation for the pressure generated across any curved interface, namely the Laplace equation, which is derived in the following section. 

D. Diverse Methods of Preparation of Allylic Zinc Reagents. 317... 

New and more diverse methods to measure extracellular enzyme activity... 

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