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Topic Review
Spiking Neural Networks
Spiking neural networks (SNNs) are artificial neural network models that more closely mimic natural neural networks. In addition to neuronal and synaptic state, SNNs also incorporate the concept of time into their operating model. The idea is that neurons in the SNN do not fire at each propagation cycle (as it happens with typical multi-layer perceptron networks), but rather fire only when a membrane potential – an intrinsic quality of the neuron related to its membrane electrical charge – reaches a specific value. When a neuron fires, it generates a signal which travels to other neurons which, in turn, increase or decrease their potentials in accordance with this signal (ref).
  • 5.4K
  • 13 Oct 2021
Topic Review
Yeasts in Cocoa Bean Fermentation
During the fermentation of cocoa beans, the yeasts produce volatile organic compounds (VOCs). Through reactions associated with amino acid metabolism, yeasts generate important aroma precursors as acetate esters and fatty acid ethyl esters; these are essential in developing fruity flavors and aromas in the final product (usually chocolate). In addition, some yeasts may have pectinolytic and antifungal activity, which is desirable in the post-harvest process of cocoa. The main yeast species in cocoa fermentation are Saccharomyces cerevisiae, Pichia kudriavzevii, and Hanseniaspora opuntiae. These produce higher alcohols and acetyl-CoA to make acetate–esters, compounds that produce floral and fruity notes.
  • 5.4K
  • 19 Jul 2022
Topic Review
Purple Economy
The purple economy is that part of the economy which contributes to sustainable development by promoting the cultural potential of goods and services. “The purple economy refers to taking account of cultural aspects in economics. It designates an economy that adapts to the human diversity in globalization and that relies on the cultural dimension to give value to goods and services.”
  • 5.4K
  • 18 Oct 2022
Topic Review
List of Aircraft (D)
This is a list of aircraft in alphabetical order beginning with 'D'.
  • 5.4K
  • 27 Oct 2022
Topic Review
Possessions of Muhammad
The possessions of the Islamic prophet Muhammad are a group of his items and possessions such as weapons, animals and others known with unique names. There is doubt about the attribution of these possessions to Muhammad, as many of them were lost during wars and tribulations. The scholar Ahmed Taymour says - after listing the remnants attributed to Muhammad in Constantinople (later Istanbul): "It is no secret that some of these remnants are likely to be true. However, we did not see any of the trustworthy people who mentioned it with proof or denial, for Allah (God), Glory be to Him, who knows about it best, and some of them cannot conceal what the idea or notion that stumbles on of suspicion and disputes it in doubts." The emir Ahmad Ibn Tulun mentioned in his book “Mufākahat al-Khullān fī Hawādith Az-Zamān”, in the incidents of the year 19 AH (640 CE) and 900 AH (1500 CE) that some claimed that they had a mug and some crutches of Muhammad and that “it was found that they are not of the possessions of the Prophet Muhammad, but rather they are the fragments of Al-Layth ibn Sa'd." The scholar Al-Suyuti said, on the authority of Muhammad (his garment): "This (the possessions) was used by the caliphs to inherit it and put it on their shoulders in processions sitting and riding, and it was on the able-bodied when he was killed and contaminated with blood, and I think it was lost in the temptation of the Tatars, for we belong to Allah (God) and to Him we shall return."
  • 5.4K
  • 11 Nov 2022
Topic Review
Covalent Adaptable Networks
Thermosets are known to be very reliable polymeric materials for high-performance and light-weight applications, due to their retained dimensional stability, chemical inertia and rigidity over a broad range of temperatures. However, once fully cured, they cannot be easily reshaped or reprocessed, thus leaving still unsolved the issues of recycling and the lack of technological flexibility. Vitrimers, introduced by Leibler et al. in 2011, are a valiant step in the direction of bridging the chasm between thermoplastics and thermosets. Owing to their dynamic covalent networks, they can retain mechanical stability and solvent resistance, but can also flow on demand upon heating. More generally, the family of Covalent Adaptable Networks (CANs) is gleaming with astounding potential, thanks to the huge variety of chemistries that may enable bond exchange. Arising from this signature feature, intriguing properties such as self-healing, recyclability and weldability may expand the horizons for thermosets in terms of improved life-span, sustainability and overall enhanced functionality and versatility. In this review, we present a comprehensive overview of the most promising studies featuring CANs and vitrimers specifically, with particular regard for their industrial applications. Investigations into composites and sustainable vitrimers from epoxy-based and elastomeric networks are covered in detail.
  • 5.4K
  • 26 Oct 2020
Topic Review
Zwitterionics Surfactants
Zwitterions are molecules that contain both a positive and negative charge within the same molecule. They are electrically neutral as a whole, but have distinct positive and negative regions within the molecule. The most common example of a zwitterion is the amino acid molecule, which contains both a carboxyl group (-COOH) and an amino group (-NH2) within the same molecule. The carboxyl group is negatively charged at physiological pH, while the amino group is positively charged, resulting in a net charge of zero for the molecule as a whole. Zwitterions have unique properties that make them useful in various applications. They are often used as buffer solutions in biochemistry and molecular biology, as they can maintain a stable pH even when small amounts of acid or base are added. Zwitterions are also used as surfactants, due to their amphipathic nature (i.e. they have both hydrophilic and hydrophobic regions). They are used in applications such as detergents and fabric softeners, where they can help to reduce surface tension and improve the wetting and dispersibility of the product. Zwitterionic surfactants have a unique structure that allows them to interact with a wide range of substances, making them useful in various applications. The unique combination of positive and negative charges in the same molecule provides a balance that enables them to interact with both hydrophilic and hydrophobic substances, allowing them to solubilize oils and greases, emulsify water-insoluble substances, and reduce surface tension.
  • 5.4K
  • 24 Mar 2023
Topic Review
Applications of Ant Colony Optimization
Ant-inspired metaheuristic algorithms known as ant colony optimization (ACO) offer an approach that has the ability to solve complex problems in both discrete and continuous domains. ACOs have gained significant attention in the field of water resources management, since many problems in this domain are non-linear, complex, challenging and also demand reliable solutions. 
  • 5.4K
  • 10 May 2023
Topic Review
The Brazilian Cement Sector
The worldwide cement industry plays an important role in addressing the climate change challenge. Brazil’s cement industry currently has 91 cement plants with an installed production capacity of 94 million tons per year and has started to calculate the net CO2 emissions to achieve a carbon-neutral cement sector by 2050. Accordingly, the carbon dioxide uptake due to mortar and concrete carbonation is subtracted from the carbon dioxide emitted by the chemical reaction for the calcination of lime, i.e., the calcination process performed during clinker production.
  • 5.4K
  • 07 Mar 2024
Topic Review
Plant-Based Antioxidants
Antioxidants are compounds that normally prevent lipid and protein oxidation. They play a major role in preventing many adverse conditions in the human body, including inflammation and cancer. Synthetic antioxidants are widely used in the food industry to prevent the production of adverse compounds that harm humans. However, plant and animal-based antioxidants are more appealing to consumers than synthetic antioxidants. Plant-based antioxidants are mainly phenolic compounds, carotenoids, and vitamins, while animal-based antioxidants are mainly whole protein or the peptides of meat, fish, egg, milk, and plant proteins. Plant-based antioxidants mainly consist of aromatic rings, while animal-based antioxidants mainly consist of amino acids. The phenolic compounds and peptides act differently in preventing oxidation and can use in the food and pharmaceutical industries. Therefore, compared with the animal-based antioxidants, plant-based compounds are more practical in the food industry. 
  • 5.4K
  • 07 Jun 2022
Topic Review
Major Histocompatibility Complex Class II Presentation in Autoimmunity
Antigen presentation by major histocompatibility complex class II (MHC-II) molecules is crucial for eliciting an efficient immune response by CD4+ T cells and maintaining self-antigen tolerance. Some MHC-II alleles are known to be positively or negatively associated with the risk of the development of different autoimmune diseases (ADs), including those characterized by the emergence of autoreactive T cells. Apparently, the MHC-II presentation of self-antigens contributes to the autoimmune T cell response, initiated through a breakdown of central tolerance to self-antigens in the thymus. 
  • 5.4K
  • 02 Feb 2023
Topic Review
Techniques for Emulsion Characterization
Emulsions have garnered significant attention within a variety of industries, including pharmaceuticals, food production, and cosmetics. The importance of emulsions across these sectors is attributed to their versatility and unique properties, such as increased interfacial area and the ability to deliver compounds insoluble in water or to mask the flavor of unpalatable ingredients. A comprehensive and precise assessment of the physicochemical properties, structural features, and stability of emulsions is an indispensable phase in the pursuit of new formulations and the improvement of manufacturing protocols. The characterization of emulsions encompasses an array of methodologies designed to determine their attributes, such as composition, texture, rheological and thermal properties, electrical conductivity, droplet size, size distribution, concentration, surface charge, and others.
  • 5.4K
  • 17 Feb 2024
Topic Review
Role of Evapotranspiration in Agricultural Water Management
Evapotranspiration (ET) is a major component of the water cycle and agricultural water balance. Estimation of water consumption over agricultural areas is important for agricultural water resources planning, management, and regulation. It leads to the establishment of a sustainable water balance, mitigates the impacts of water scarcity, as well as prevents the overusing and wasting of precious water resources. As evapotranspiration is a major consumptive use of irrigation water and rainwater on agricultural lands, improvements of water use efficiency and sustainable water management in agriculture must be based on the accurate estimation of ET. 
  • 5.4K
  • 12 Jul 2022
Topic Review
Sandwich Structures
Sandwich structures are a class of multifunctional high-performance structural composites that have the advantages of being lightweight, of a high strength-to-weight ratio, and of high specific energy absorption capabilities. 
  • 5.4K
  • 01 Dec 2022
Topic Review
Inclusive Governance
Inclusive governance is strongly connected to, yet not limited to, notions such as good governance, and democratic governance, a human rights-based approach to development and legitimacy. Inclusive governance is an intrinsic value within governance and has become an integral feature of the good governance agenda aiming at achieving a better world through establishing fair, judicious, transparent, accountable, and inclusive political systems and decision-making processes in public institutions.
  • 5.4K
  • 07 Aug 2023
Topic Review
Urban Green Spaces
n the context of urban land-use growth and the consequent impacts on the environment, green spaces provide ecosystem services for human health. The ecosystem services concept synthesises human–environmental interactions through a series of combined components of biodiversity and abiotic elements, linking ecological processes and functions. The concept of green infrastructure (GI) in the urban context emphasises the quality and quantity of urban and peri-urban green spaces and natural areas.
  • 5.4K
  • 05 Mar 2021
Topic Review
ISO 29110
ISO/IEC 29110: Systems and Software Life Cycle Profiles and Guidelines for Very Small Entities (VSEs) International Standards (IS) and Technical Reports (TR) are targeted at Very Small Entities (VSEs). A Very Small Entity (VSE) is an enterprise, an organization, a department or a project having up to 25 people. The ISO/IEC 29110 is a series of international standards and guides entitled "Systems and Software Engineering — Lifecycle Profiles for Very Small Entities (VSEs)". The standards and technical reports were developed by working group 24 (WG24) of sub-committee 7 (SC7) of Joint Technical Committee 1 (JTC1) of the International Organization for Standardization and the International Electrotechnical Commission. Industries around the world have agreed that there are certain ways of working that produce predictable results. Companies that agree to use these agreed methods and then to have their compliance measured are called ISO certificated. Some ISO-certificated organizations require that their vendors also be ISO certificated. The general standard for software development, ISO/IEC/IEEE 12207, is appropriate for medium and large software development efforts. Similarly, the general standard for system development, ISO/IEC/IEEE 15288, is appropriate for medium and large system development efforts. Systems, in the context of ISO/IEC 29110, are typically composed of hardware and software components. Things work differently in small organisations; ISO 29110 reflects that.
  • 5.4K
  • 07 Nov 2022
Topic Review
G-Factor
A g-factor (also called g value or dimensionless magnetic moment) is a dimensionless quantity that characterizes the magnetic moment and angular momentum of an atom, a particle or the nucleus. It is essentially a proportionality constant that relates the different observed magnetic moments μ of a particle to their angular momentum quantum numbers and a unit of magnetic moment (to make it dimensionless), usually the Bohr magneton or nuclear magneton.
  • 5.4K
  • 28 Oct 2022
Topic Review
Activity of Natural Carboxylic Acids
Natural carboxylic acids described in this paper are plant-derived compounds having biological activity. The aim of this review is to summarize and evaluate the physicochemical properties of selected compounds naturally occurring in plants, their potential of microbiological  and anticancer activity. In order to create targeted modifications of the structure enhancing its activity, it is; therefore, necessary to thoroughly understand the mechanisms of action of a given molecule under systemic conditions.
  • 5.4K
  • 03 Dec 2020
Topic Review
Packaging Materials for Postharvest Conservation of Table Grapes
Table grapes are one of the leading fruit species cultivated in several countries due to their distinguishing sensory and nutritional properties. However, grapes are a non-climacteric fruit with relatively low physiological activity after harvest, and they are highly perishable due to gray mold caused by Botrytis cinerea as well to mass loss, berry softening, color degradation, and dehydration and darkening of the stem. To avoid all these difficulties, several packaging materials are used during cold storage to keep table grapes fresh and healthy for consumers. Proper packaging and cold storage combined can extend the shelf life of high-quality bunches by protecting them from mechanical injuries and decays during transportation and storage.
  • 5.4K
  • 30 Jun 2023
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