Oligomers 1970-01-01
Oligomers are short chains of monomers, which are small, repeating units that can combine to form larger molecules known as polymers. In chemistry, oligomers typically consist of a limited number of monomer units, generally ranging from two to around ten or twenty. They can be formed from various types of monomers, including sugars, amino acids, and other organic compounds. Oligomers can have distinct physical and chemical properties compared to their corresponding polymers.
Organic solar cells 1970-01-01
Organic solar cells (OSCs) are a type of photovoltaic technology that uses organic molecules, typically carbon-based compounds, to convert sunlight into electricity. Unlike traditional solar cells that are based on inorganic materials such as silicon, organic solar cells utilize organic semiconductors, which can be small organic molecules or polymers. **Key Features of Organic Solar Cells:** 1. **Materials**: They are made from organic materials, including conjugated polymers and small organic molecules.
Radical initiators 1970-01-01
Radical initiators are compounds that generate free radicals when subjected to certain conditions, such as heat, light, or chemical reactions. Free radicals are highly reactive species with unpaired electrons that can initiate a chain reaction, commonly utilized in various chemical processes, such as polymerization. In radical polymerization, radical initiators are used to start the polymerization process of monomers, leading to the formation of polymers.
Addition polymer 1970-01-01
Addition polymers are a type of polymer that are formed through a process called addition polymerization, in which monomers (small, reactive molecules) are joined together without the loss of any small molecules (such as water or gas). This process typically involves unsaturated monomers, which contain double bonds (e.g., alkenes). In addition polymerization, the double bonds in the monomers open up and link together to form long chains, resulting in the formation of high molecular weight polymers.
Die swell 1970-01-01
Die swell is a phenomenon that occurs during the processing of polymers, especially during extrusion. When a molten polymer is forced through a die to take a specific shape (such as in the production of pipes, sheets, or films), it often expands or swells as it exits the die. This swelling is primarily due to the relaxation of the polymer chains as they leave the constraints of the die.
Dispersity 1970-01-01
Dispersity is a term that can refer to the degree or measure of how dispersed or spread out a set of data points or elements is within a particular space or dataset. It often applies in various fields, such as statistics, ecology, economics, and social sciences, to describe the distribution and variation among entities. In a statistical context, dispersity may relate to measures like variance, standard deviation, or range, which indicate how much variation exists from the average or mean value of a dataset.
Elastin-like polypeptides 1970-01-01
Elastin-like polypeptides (ELPs) are a class of genetically engineered polypeptides that mimic the properties of natural elastin, a key protein in connective tissues known for its elasticity and ability to return to its original shape after stretching. ELPs are composed of repeating peptide sequences typically rich in the amino acids glycine, proline, and valine, which are characteristic of elastin.
Flory–Fox equation 1970-01-01
The Flory–Fox equation describes the relationship between the molecular weight of polymers and their properties, particularly in the context of solubility and the Flory-Huggins theory of polymer solutions. The equation is used to predict the behavior of polymers in solvents and provides insights into their thermodynamic interactions.
Flory–Stockmayer theory 1970-01-01
The Flory-Stockmayer theory is a theoretical framework used to describe the behavior of polymer networks, specifically the gelation and cross-linking processes in polymeric materials. This theory was developed by Paul J. Flory and William R. Stockmayer in the 1940s and provides insights into the conditions under which a liquid polymer solution transitions to a gel or polymer network structure.
John Edwin McGee 1970-01-01
John Edwin McGee is not a widely recognized public figure or a term with a standard definition, based on the information available up to October 2023.
Chain-growth polymerization 1970-01-01
Chain-growth polymerization, also known as chain reaction polymerization, is a method of synthesizing polymers in which the structure of the polymer grows by the sequential addition of monomer units. This process typically involves three main steps: initiation, propagation, and termination. 1. **Initiation**: This step begins with the formation of reactive species, such as free radicals, cations, or anions, which are necessary to initiate the polymerization process.
Chain propagation 1970-01-01
Chain propagation typically refers to a process in various fields, but it most commonly relates to the spreading of effects or signals through a system or network. Depending on the context, it could have specific meanings: 1. **Communications and Signal Processing**: In these fields, chain propagation may describe how signals are transmitted through multiple stages or components in a network. Each stage can affect the quality and characteristics of the signal as it propagates through the system.
Chain walking 1970-01-01
Chain walking is a term that can refer to different concepts depending on the context. In general, it might refer to: 1. **In Exercise or Fitness Context**: Chain walking could refer to a form of exercise that involves walking while using a chain or resistance tool to enhance strength training or endurance activities. 2. **In Engineering or Robotics**: It might describe a method or technique used in robotic movement or mechanisms that involve chains for locomotion.
Two-dimensional polymer 1970-01-01
Two-dimensional (2D) polymers are a class of materials that consist of a polymeric structure extending in two dimensions while having a limited thickness in the third dimension. Unlike traditional polymers that are typically one-dimensional (like linear or branched chains), 2D polymers are characterized by their planar, flat nature, which can yield unique mechanical, optical, and electronic properties.
Szegő polynomial 1970-01-01
The Szegő polynomials are a sequence of orthogonal polynomials that arise in the context of approximating functions on the unit circle and in the study of analytic functions. They are particularly related to the theory of Fourier series and have applications in various areas, including signal processing and control theory. ### Definition The Szegő polynomials can be defined in terms of their generating function or through specific recurrence relations.
Tian yuan shu 1970-01-01
Tian yuan shu, or the "Heavenly Element Method," is a traditional Chinese mathematical system that is primarily concerned with solving equations. It is an ancient technique that originated from China's rich mathematical history and was used extensively in dealing with polynomial equations. In tian yuan shu, problems are typically formulated in terms of a single variable, and the solutions are often derived geometrically or through specific numerical methods.
Tricomi–Carlitz polynomials 1970-01-01
Tricomi–Carlitz polynomials are a class of polynomials that arise in the study of $q$-analogues in the context of basic hypergeometric series and combinatorial identities. They are named after the mathematicians Francesco Tricomi and Leonard Carlitz, who studied these polynomials in relation to $q$-series. These polynomials can be defined through various generating functions and properties related to $q$-binomial coefficients.
Wilson polynomials 1970-01-01
Wilson polynomials, denoted as \( W_n(x) \), are a class of orthogonal polynomials that arise in the context of probability theory and statistical mechanics. They are defined on the interval \( (0, 1) \) and are associated with the Beta distribution. Wilson polynomials can be expressed using the following formula: \[ W_n(x) = \frac{n!}{(n + 1)!
3SUM 1970-01-01
The 3SUM problem is a classic algorithmic problem in computer science, particularly in the fields of computer algorithms and complexity theory. The problem can be stated as follows: Given an array of integers, the task is to determine if there exist three distinct indices \( i, j, k \) such that the sum of the elements at these indices is equal to zero, i.e.
Element distinctness problem 1970-01-01
The Element Distinctness problem is a fundamental problem in computer science and algorithms, particularly in the area of data structures and complexity theory. The problem can be succinctly described as follows: **Problem Statement:** Given a set of \( n \) elements, determine if all the elements are distinct or if there are any duplicates in the set.