抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Part I. Experimental Studies: 2. Experiment in psychology 3. Experiments on perceiving III Experiments on imaging 4-8. Experiments on remembering: (a) The method of description (b) The method of repeated reproduction (c) The method of picture writing (d) The method of serial reproduction (e) The method of serial reproduction picture material 9. Perceiving, recognizing, remembering 10. A theory of remembering 11. Images and their functions 12. Meaning Part II. Remembering as a Study in Social Psychology: 13. Social psychology 14. Social psychology and the matter of recall 15. Social psychology and the manner of recall 16. Conventionalism 17. The notion of a collective unconscious 18. The basis of social recall 19. A summary and some conclusions.

Remembering. A Study in Experimental and Social Psychology, Cambridge (University Press) 1964.

Introduction
PaDEL-Descriptor is a software for calculating molecular descriptors and fingerprints. The software currently calculates 797 descriptors (663 1D, 2D descriptors, and 134 3D descriptors) and 10 types of fingerprints. These descriptors and fingerprints are calculated mainly using The Chemistry Development Kit. Some additional descriptors and fingerprints were added, which include atom type electrotopological state descriptors, McGowan volume, molecular linear free energy relation descriptors, ring counts, count of chemical substructures identified by Laggner, and binary fingerprints and count of chemical substructures identified by Klekota and Roth.

Methods
PaDEL-Descriptor was developed using the Java language and consists of a library component and an interface component. The library component allows it to be easily integrated into quantitative structure activity relationship software to provide the descriptor calculation feature while the interface component allows it to be used as a standalone software. The software uses a Master/Worker pattern to take advantage of the multiple CPU cores that are present in most modern computers to speed up calculations of molecular descriptors.

Results
The software has several advantages over existing standalone molecular descriptor calculation software. It is free and open source, has both graphical user interface and command line interfaces, can work on all major platforms (Windows, Linux, MacOS), supports more than 90 different molecular file formats, and is multithreaded.

Conclusion
PaDEL-Descriptor is a useful addition to the currently available molecular descriptor calculation software. The software can be downloaded at http://padel.nus.edu.sg/software/padeldescriptor. © 2010 Wiley Periodicals, Inc. J Comput Chem, 2011

https://onlinelibrary.wiley.com/doi/pdf/10.1002/jcc.21707

PaDEL‐descriptor: An open source software to calculate molecular descriptors and fingerprints

This paper emphasizes the importance of rigorous validation as a crucial, integral component of Quantitative Structure Property Relationship (QSPR) model development. We consider some examples of published QSPR models, which in spite of their high fitted accuracy for the training sets and apparent mechanistic appeal, fail rigorous validation tests, and, thus, may lack practical utility as reliable screening tools. We present a set of simple guidelines for developing validated and predictive QSPR models. To this end, we discuss several validation strategies including (1) randomization of the modelled property, also called Y-scrambling, (2) multiple leave-many-out cross-validations, and (3) external validation using rational division of a dataset into training and test sets. We also highlight the need to establish the domain of model applicability in the chemical space to flag molecules for which predictions may be unreliable, and discuss some algorithms that can be used for this purpose. We advocate the broad use of these guidelines in the development of predictive QSPR models.

The Importance of Being Earnest: Validation is the Absolute Essential for Successful Application and Interpretation of QSPR Models

INTRODUCTION. ELEMENTS OF GRAPH THEORY. The Definition of a Graph. Isomorphic Graphs and Graph Automorphism. Walks, Trails, Paths, Distances and Valencies in Graphs. Subgraphs. Regular Graphs. Trees. Planar Graphs. The Story of the Koenigsberg Bridge Problem and Eulerian Graphs. Hamiltonian Graphs. Line Graphs. Vertex Coloring of a Graph. CHEMICAL GRAPHS. The Concept of a Chemical Graph. Molecular Topology. Huckel Graphs. Polyhexes and Benzenoid Graphs. Weighted Graphs. GRAPH-THEORETICAL MATRICES. The Adjacency Matrix. The Distance Matrix. THE CHARACTERISTIC POLYNOMIAL OF A GRAPH. The Definition of the Characteristic Polynomial. The Method of Sachs for Computing the Characteristic Polynomial. The Characteristic Polynomials of Some Classes of Simple Graphs. The Le Verrier-Faddeev-Frame Method for Computing the Characteristic Polynomial. TOPOLOGICAL ASPECTS OF HUECKEL THEORY. Elements of Huckel Theory. Isomorphism of Huckel Theory and Graph Spectral Theory. The Huckel Spectrum. Charge Densities and Bond Orders in Conjugated Systems. The Two-Color Problem in Huckel Theory. Eigenvalues of Linear Polyenes. Eigenvalues of Annulenes. Eigenvalues of Moebius Annulenes. A Classification Scheme for Monocyclic Systems. Total p-Electron Energy. TOPOLOGICAL RESONANCE ENERGY. Huckel Resonance Energy. Dewar Resonance Energy. The Concept of Topological Resonance Energy. Computation of the Acyclic Polynomial. Applications of the TRE Model. ENUMERATION OF KEKULE VALENCE STRUCTURES. The Role of Kekule Valence Structures in Chemistry. The Identification of Kekule Systems. Methods for the Enumeration of Kekule Structures. The Concept of Parity of Kekule Structures. THE CONJUGATED-CIRCUIT MODEL. The Concept of Conjugated Circuits. The p-Resonance Energy Expression. Selection of the Parameters. Computational Procedure. Applications of the Conjugated-Circuit Model. Parity of Conjugated Circuits. TOPOLOGICAL INDICES. Definitions of Topological Indices. The Three-Dimensional Wiener Number. ISOMER ENUMERATION. The Cayley Generation Functions. The Henze-Blair Approach. The Polya Enumeration Method. The Enumeration Method Based on the N-Tuple Code.

Chemical Graph Theory

A new approach to aromaticity of conjugated hydrocarbons is described. It is based on the concept of conjugated cir­ cuits, which has been recently recognized as an essential structural element for characterization of conjugated systems (Chem. Phys. Lett., 38, 68 (1976)). Kekule structures of a conjugated hydrocarbon are examined and circuits with an alternation of CC double and single bonds enumerated. Systems having only (An + 2) conjugated circuits are defined as aromatic. Systems having only 4n conjugated circuits are considered antiaromatic, i.e., destabilized by the derealization of T electrons. Finally, systems having both (An + 2) and An conjugated circuits are classified as intermediate, showing partial aromatic nature. The approach represents a logical generalization of the famous Hiickel (An + 2) rule, valid rigorously only for monocyclic struc­ tures, to polycyclic systems. A brief comparison with several alternative schemes is given and their limitations illustrated. Difficulties involved in attempts to characterize aromatic­ ity are well known.1 The simple Hiickel (An + 2) rule, valid only for monocyclic systems,2 and Piatt's perimeter model,3 an attempt to extend the rule to polycyclic systems, remain frequently used for more general situations without a proper justification and despite recognized deficiencies. This perhaps indicates an intuitive appreciation of the significance of the (An + 2) 7r-electron role. We present here an approach to aroma­ ticity in which also a role of (An + 2) tr electrons is dominant. However, it turns out that not the number of tr electrons is the critical factor, but their coupling in conjugated circuits as derived from the Kekule structures of the system. The ap­ proach has lead to a logical generalization of the famous Hiickel (An + 2) rule, valid rigorously only for monocyclic conjugated polyenes, to polycyclic structures. In view of the acclaimed value of the Hiickel rule, believed to have been one of the most successful theoretical predictions made in organic chemistry,4 the approach of a classification of cyclic conjugated ir-electron systems developed here seems to be rather inter­ esting mainly because it encloses the polycyclic systems too. The basis for the approach to aromaticity suggested in this work is the concept of conjugated circuits.5 A polycyclic structure contains various circuits, and an individual Kekule structure assigns a single or a double bond character to bonds in a circuit. Circuits which have an alternation of the CC single and double bonds are called conjugated circuits. They neces­ sarily are even, and are either of a (An + 2) or An type. The notion of conjugate circuits is not so unfamiliar in chemistry; however, it has not been realized that they represent an im­ portant structural element. The analysis consists of the enu­ meration of all distinctive conjugated circuits; hence here we have a typical graph theoretical scheme. We illustrate the approach with azupyrene, two Kekule structures of which are decomposed as shown in Scheme I. The remaining two struc- Scheme I

Aromaticity and conjugation

Novel molecular descriptor for structure—property studies

Novel 2-D graphical representation of DNA sequences and their numerical characterization

Analysis of similarity/dissimilarity of DNA sequences based on novel 2-D graphical representation

On propose une technique qui permet d'assigner un numero d'identification a chaque structure moleculaire. Cet outil peut servir d'outil de recherche annexe dans la base CAS

Milan Randić

Papers

Aromaticity and conjugation

Novel molecular descriptor for structure—property studies

Novel 2-D graphical representation of DNA sequences and their numerical characterization

Analysis of similarity/dissimilarity of DNA sequences based on novel 2-D graphical representation

On molecular identification numbers