Chemical similarity refers to the concept of comparing the chemical structures, properties, or behaviors of different molecules to determine how alike they are. This can involve evaluating various aspects, including: 1. **Structural Similarity**: Molecules may be considered chemically similar if they share a similar arrangement of atoms, functional groups, or overall 3D conformation. Structural similarity can be quantified using methods such as graph theory or molecular descriptors.

In chess, a "fortress" is a defensive formation or setup that a player creates to prevent the opponent from being able to make progress, often in a situation where one side is at a material disadvantage but can effectively safeguard against losing. This concept is typically relevant in endgames, where one side has an inferior position but can set up a configuration of pieces that makes it impossible for the opponent to break through and force a win.

The 19th century was a period of significant development in mathematics in Chile, marked by the establishment of educational institutions and the promotion of scientific research. Here's an overview of some key figures and contributions from Chilean mathematicians during this period: 1. **Joaquín V. González (1860-1923)**: Although more known as an educator and reformer, González contributed to the field of mathematics and played a critical role in the advancement of education in Chile.

"Chemical space" refers to the theoretical multidimensional space that represents all possible chemical compounds and their properties. Each point in this space corresponds to a unique chemical structure, which can be described by its molecular formula, structural formula, or other chemical descriptors. The concept is often used in cheminformatics, drug discovery, and materials science to explore and visualize the vast number of potential molecules that could exist, including those that have not yet been synthesized.

Dendral is one of the earliest expert systems developed in the field of artificial intelligence and is primarily associated with the domain of chemistry. It was created in the 1960s by researchers at Stanford University, including Edward Feigenbaum, Joshua Lederberg, and Carl Djerassi. Dendral was designed to assist chemists in the process of identifying molecular structures based on mass spectrometry data.

As of my last update in October 2023, Kimito Funatsu is a Japanese professional wrestler known for his work in various wrestling promotions, including DDT Pro-Wrestling (Dramatic Dream Team) in Japan. He has participated in multiple events and has made a name for himself through his performances in the ring.

Ya-Jun Pan is a researcher known for work in the field of cancer biology, specifically in the context of breast cancer research. Her research often focuses on the mechanisms of cancer progression, therapy resistance, and how different biological pathways contribute to tumor development.

The Enzyme Commission (EC) number is a unique numerical classification scheme for enzymes, based on the chemical reactions they catalyze. Established by the International Union of Biochemistry and Molecular Biology (IUBMB), the EC number provides a systematic way to categorize enzymes into groups based on their functions. An EC number consists of four digits, separated by periods, formatted as EC x.y.z.

The Estrada index is a graph-theoretic invariant that quantifies the complex structure of a molecular graph, representing a chemical compound. It is defined as a weighted sum of the entries of the inverse of the adjacency matrix of the graph.

The European Chemicals Bureau (ECB) was a part of the European Commission that operated under the Directorate-General for Environment. It was primarily responsible for implementing various regulatory frameworks related to chemical substances in the European Union, particularly the REACH (Registration, Evaluation, Authorisation, and Restriction of Chemicals) regulation. The ECB provided technical and scientific support for the development of policies on chemicals and facilitated the registration and assessment of chemical substances.

The European Chemical Substances Information System (ESIS) was a database established by the European Commission to provide information on chemical substances that are manufactured or imported in the European Union (EU). Its main objective was to support the implementation of various European regulations regarding chemical safety, such as the Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) regulation. ESIS contained data on: 1. **Chemical substance identity**: Information on the chemical name, CAS number, and other identifiers.

The Herman Skolnik Award is an honor given by the American Chemical Society (ACS) to recognize outstanding contributions to the field of chemical information. Established in 1995, the award is named in honor of Herman Skolnik, who was a prominent figure in chemical information and played a significant role in the development of resources in this area. The award typically acknowledges individuals who have made exceptional contributions to the advancement of chemical information and the effective use of information in the practice of chemistry.

IUCLID stands for "International Uniform Chemical Information Database." It is a software application developed by the European Chemicals Agency (ECHA) that is used for managing and exchanging information on chemical substances. IUCLID allows users to create, store, and manage data related to the properties and hazards of chemicals, as well as information necessary for regulatory compliance, such as the European Union's REACH (Registration, Evaluation, Authorisation and Restriction of Chemicals) regulation.

The *Journal of Chemical Information and Modeling* is a scholarly journal that publishes research related to the application of computational methods in chemical and biochemical contexts. This includes areas such as cheminformatics, molecular modeling, and the use of computational techniques to predict the behavior and properties of chemical compounds.

Cheminformatics toolkits are software libraries and frameworks designed to facilitate the handling and analysis of chemical data. These toolkits can perform a variety of tasks, including molecular modeling, cheminformatics analysis, data mining, visualization, and simulation. Here’s a list of some notable cheminformatics toolkits: 1. **RDKit**: A collection of cheminformatics and machine learning tools designed for use in Python. It includes functionality for molecular representation, descriptor calculations, and substructure searching.

Medicinal chemistry is a multidisciplinary field that combines principles from chemistry, biology, and pharmacology to design, develop, and evaluate pharmaceutical compounds. Its primary objective is to discover and create new drugs that are effective, safe, and cost-effective for treating various diseases and conditions. Key aspects of medicinal chemistry include: 1. **Drug Design**: Medicinal chemists utilize structure-activity relationship (SAR) studies to understand how the chemical structure of a compound influences its biological activity.

SMILES (Simplified Molecular Input Line Entry System) is a notation system used to represent chemical structures in a way that can be easily read by both humans and computers. The notation consists of a line of text that encodes the atoms, bonds, connectivity, and sometimes stereochemistry of a molecule. **Arbitrary Target Specification (ATS)** refers to a feature in SMILES that allows for the representation of complex chemical structures, including various modifications and functional groups.

Scoring functions are mathematical models used in molecular docking to evaluate the quality of the predicted interactions between a drug (or ligand) and its target protein (or receptor). The main goal of docking is to predict the best pose (orientation and conformation) of a ligand when it binds to a protein, optimizing the interaction energy and thus indicating potential biological activity.

The National Chemical Emergency Centre (NCEC) is an organization in the United Kingdom that provides support and information regarding chemical incidents and emergencies. It is part of the UK government’s response to chemical safety and risk management. The NCEC offers a range of services, including: 1. **Emergency Response**: Providing 24/7 support for chemical incidents, helping emergency responders and organizations manage situations involving hazardous substances.

Topology in chemistry refers to the study of molecular structures and their properties based on their spatial arrangement and connectivity, rather than their exact geometric shapes or distances. In this context, topology is used to analyze how atoms are connected within a molecule and how these connections influence the molecule's properties and behavior. Key aspects of topology in chemistry include: 1. **Graph Theory**: Molecules can be represented as graphs, where atoms are vertices and bonds are edges.