Subject:
All Disciplines Arts & Humanities Biology & Life Sciences Business & Economics Chemistry & Materials Science Computer Science & Mathematics Engineering Environmental & Earth Sciences Medicine & Pharmacology Physical Sciences Public Health & Healthcare Social Sciences
Sort:
Hottest Latest Alphabetical (A-Z) Alphabetical (Z-A)
Type:
All Topic Review Biography
Topic Review
Thermoplastic Pultrusion
Pultrusion is one of the most efficient methods of producing polymer composite structures with a constant cross-section. Pultruded profiles are widely used in bridge construction, transportation industry, energy sector, and civil and architectural engineering. There are two types of pultrusion: thermoplastic and thermosetting. The main features of thermoplastic pultrusion are discussed below.
  • 1.4K
  • 11 Feb 2021
Topic Review
Thermoelectric Generators at Low Operating-Temperatures
Thermoelectric generators (TEGs) are a form of energy harvester and eco-friendly power generation system that directly transform thermal energy into electrical energy. The thermoelectric (TE) method of energy harvesting takes advantage of the Seebeck effect, which offers a simple solution for fulfilling the power-supply demand in almost every electronics system. A high-temperature condition is commonly essential in the working mechanism of the TE device, which unfortunately limits the potential implementation of the device.
  • 1.2K
  • 01 Jul 2021
Topic Review
Thermal Stability of Structural Materials
Thermal stability determines the material ability of retaining its properties at required temperatures over extended service time. In addition to temperature and time, thermal stability is affected by load conditions and environmental conditions.
  • 7.1K
  • 20 Aug 2020
Topic Review
The Jahn-Teller Effects
The fundamental property of a polyatomic system to undergo spontaneous symmetry breaking was first formulated by L. Landau in 1934 as follows: the configuration of any nonlinear polyatomic system in a degenerate electronic state undergoes spontaneous distortions that remove the degeneracy. This groundbreaking idea, appended with proof, was published by H. Jahn and E. Teller, resulting in what is presently known as the Jahn-Teller effect (JTE). Since then, many extensions of this groundbreaking idea were revealed and developed. Presently, four types of electronic structures that lead to spontaneous symmetry breaking are revealed: in addition to electronic degeneracy resulting in the proper Jahn-Teller effect, two or more close in energy (pseudodegenerate) electronic states may lead to similar instability and distortions, called the pseudo-JTE (PJTE), and the same spontaneous distortion effects may take place when there is neither degeneracy, nor pseudodegeneracy in the fground state of the high-symmetry configuration, but a strong JTE or pseudo-JTE take place in a low-lying excited state, that penetrates the ground state, distorting the system; these are the hidden -JTE and hidden-PJTE, respectively.
  • 739
  • 26 Oct 2021
Topic Review
The Application of Food-Grade Emulsions
Briefly, an emulsion is simply a mixture of two (or more) liquids that are otherwise immiscible. The detailed investigation of food-grade emulsions, which possess considerable structural and functional advantages, remains ongoing to enhance people's understanding of these dispersion systems and to expand their application scope. 
  • 1.5K
  • 30 Sep 2022
Topic Review
Tetravalence
In chemistry, the valence (US spelling) or valency (British spelling) of an element is the measure of its combining capacity with other atoms when it forms chemical compounds or molecules.
  • 679
  • 27 Oct 2022
Topic Review
Symbol
In chemistry, a symbol is an abbreviation for a chemical element. Symbols for chemical elements normally consist of one or two letters from the Latin alphabet and are written with the first letter capitalised. Earlier symbols for chemical elements stem from classical Latin and Greek vocabulary. For some elements, this is because the material was known in ancient times, while for others, the name is a more recent invention. For example, Pb is the symbol for lead (plumbum in Latin); Hg is the symbol for mercury (hydrargyrum in Greek); and He is the symbol for helium (a new Latin name) because helium was not known in ancient Roman times. Some symbols come from other sources, like W for tungsten (Wolfram in German) which was not known in Roman times. A 3-letter temporary symbol may be assigned to a newly synthesized (or not-yet synthesized) element. For example, "Uno" was the temporary symbol for hassium (element 108) which had the temporary name of unniloctium, based on its atomic number being 8 greater than 100. There are also some historical symbols that are no longer officially used. In addition to the letters for the element itself, additional details may be added to the symbol as superscripts or subscripts a particular isotope, ionization, or oxidation state, or other atomic detail. A few isotopes have their own specific symbols rather than just an isotopic detail added to their element symbol. Attached subscripts or superscripts specifying a nuclide or molecule have the following meanings and positions: In Chinese, each chemical element has a dedicated character, usually created for the purpose (see Chemical elements in East Asian languages). However, Latin symbols are also used, especially in formulas. Many functional groups also have their own chemical symbol, e.g. Ph for the phenyl group, and Me for the methyl group. A list of current, dated, as well as proposed and historical signs and symbols is included here with its signification. Also given is each element's atomic number, atomic weight, or the atomic mass of the most stable isotope, group and period numbers on the periodic table, and etymology of the symbol. Hazard pictographs are another type of symbols used in chemistry.
  • 770
  • 14 Nov 2022
Topic Review
Sustainable Concrete Quality Management
The development of a concrete mixture design process for high-quality concrete production with sustainable values is a complex process because of the multiple required properties at the green/hardened state of concrete and the interdependency of concrete mixture parameters. A new multi-criteria decision making (MCDM) technique based on Technique of Order Preference Similarity to the Ideal Solution (TOPSIS) methodology is applied to a fuzzy setting for the selection of concrete mix factors and concrete mixture design methods with the aim towards sustainable concrete quality management. Three objective properties for sustainable quality concrete are adopted as criteria in the proposed MCDM model. The seven most dominant concrete mixture parameters with consideration to sustainable concrete quality issues, i.e., environmental (density, durability) and socioeconomic criteria (cost, optimum mixture ingredients ratios), are proposed as sub-criteria. Three mixture design techniques that have potentiality to include sustainable aspects in their design procedure, two advanced and one conventional concrete mixture design method, are taken as alternatives in the MCDM model. The proposed selection support framework may be utilized in updating concrete design methods for sustainability and in deciding the most dominant concrete mix factors that can provide sustainable quality management in concrete production as well as in concrete construction. The concrete mix factors found to be most influential to produce sustainable concrete quality include the water/cement ratio and density. The outcomes of the proposed MCDM model of fuzzy TOPSIS are consistent with the published literature and theory. TheDOE method was found to be more suitable in sustainable concrete quality management considering its applicable objective quality properties and concrete mix factors.
  • 578
  • 26 Oct 2020
Topic Review
Sustainable Catalytic Pyranopyrazole Scaffolds’ Synthesis
Heterocycles are important components of many natural materials and are extremely valuable in organic and medicinal chemistry. Among the heterocyclic entities, pyranopyrazole moieties have demonstrated remarkable biochemical behaviours and activities which provide a versatile skeleton for drug innovation. Hence, many nitrogen-based, fused structures have been incorporated as building blocks of various pharmacological potent scaffolds. Pyranopyrazoles are known for their anti-inflammatory, analgesic, antidiabetic, antimicrobial, cholinesterase-inhibiting, antibacterial and anticancer activities, as well as for their efficacy in treating Alzheimer’s disease. Because of this, several cost-effective synthetic protocols for synthesising pyranopyrazole derivatives—utilising less expensive substrates, reusable catalysts, and eco-friendly solvents—have been developed.
  • 864
  • 10 Jun 2021
Topic Review
Surface Attached Mortar for Recycled Coarse Aggregate
Due to the large amount of old hardened cement mortar attached to the surface of aggregate and the internal micro-cracks formed by the crushing process, the water absorption, apparent density, and crushing index of recycled coarse aggregate are still far behind those of natural coarse aggregate. The results showed that the physical strengthening technique can remove old hardened mortar and micro powder attached to the surface of recycled coarse aggregate by mechanical action, which can effectively improve the quality of recycled coarse aggregate. 
  • 797
  • 04 Jan 2022
  • Page
  • of
  • 44
Featured Entry Collections
>>

Featured Books

>>
Encyclopedia of Social Sciences
Encyclopedia of COVID-19
Encyclopedia of Fungi
Encyclopedia of Digital Society, Industry 5.0 and Smart City
Video Production Service
Feedback