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Topic Review
Class D Audio Power Amplifier
Class D power amplifiers, one of the most critical devices for application in sound systems, face severe challenges due to the increasing requirement of smartphones, digital television, digital sound, and other terminals. The audio power amplifier has developed from a transistor amplifier to a field-effect tube amplifier, and digital amplifiers have made significant progress in circuit technology, components, and ideological understanding. The stumbling blocks for a successful power amplifier are low power efficiency and a high distortion rate.
  • 3.7K
  • 01 Nov 2022
Topic Review Peer Reviewed
Molecular Aspects of Spike–ACE2 Interaction
A new betacoronavirus (CoV-2) is responsible for the pandemic of severe acute respiratory syndrome (SARS) that began in China at the end of 2019, today known as COronaVIrus Disease 2019 (COVID-19). Subsequent studies confirmed the human angiotensin-converting enzyme 2 (hACE2) as the main cell receptor of spike trimeric glycoprotein, located on the viral envelope, mediating the CoV-2 invasion into the host cells through the receptor-binding domain (RBD) of the spike. Computational analysis of the known experimental 3D structures of spike–ACE2 complexes evidenced distinguishing features in the molecular interactions at the RBD-cell receptor binding interface between CoV-2 and previous CoV-1. The spike represents a key target for drug design as well as an optimal antigen for RNA/viral vector vaccines and monoclonal antibodies in order to maximize prevention and therapy of COVID-19.
  • 3.7K
  • 13 Apr 2022
Topic Review
Photocatalytic Properties of SnO2
SnO2 is an n-type semiconductor with a band gap between 3.6 and 4.0 eV, whose intrinsic characteristics are responsible for its electrical conductivity, good optical characteristics, high thermal stability, and other qualities. Such characteristics have provided excellent results in advanced oxidative processes, i.e., heterogeneous photocatalysis applications. This process involves semiconductors in the production of hydroxyl radicals via activation by light absorption, and it is considered as an emerging and promising technology for domestic-industrial wastewater treatment.
  • 3.7K
  • 05 May 2022
Topic Review Peer Reviewed
Telework: Before and after COVID-19
Telework is, today, a voluntary form of work organization in which the employee is located outside the employer’s premises, at home or elsewhere, under a telework contract, uses information and communication technologies (ICT) and works according to a predetermined schedule on the basis of an agreed supervisory mechanism and an online reporting system on the work undertaken.
  • 3.7K
  • 19 Jul 2022
Topic Review
Single-Speed Bicycle
A single-speed bicycle is a type of bicycle with a single gear ratio. These bicycles are without derailleur gears, hub gearing or other methods for varying the gear ratio of the bicycle. There are many types of modern single speed bicycles; BMX bicycles, most bicycles designed for children, cruiser type bicycles, classic commuter bicycles, unicycles, bicycles designed for track racing, fixed-gear road bicycles, and single-speed mountain and cyclocross bikes. Although most fixed-gear bicycles (fixies) are technically single speed, the term single-speed generally refers to a single gear ratio bicycle with a freewheel mechanism to allow it to coast.
  • 3.7K
  • 20 Oct 2022
Topic Review
Electrodeposition of Common Metals
The electrodeposition process of metals and their alloys is widely used in the automotive, space, electronics, computing, jewelry, and other consumer items industries.
  • 3.7K
  • 15 Dec 2022
Topic Review
Geopolymers as Construction Materials
Utilising geopolymer as a construction material has gained institutional and commercial interest over the past decade, due to its favourable emissions profile as an alternative to carbon-intensive Ordinary Portland Cement-based concrete, which currently accounts for around 7% of global carbon emissions.
  • 3.7K
  • 11 May 2021
Topic Review
Bee-Products in Male Reproductive Impairment
Bee products are sources of functional food that have been used in complementary medicine to treat a variety of acute and chronic illnesses in many parts of the world. The products vary from location to location as well as country to country. 
  • 3.7K
  • 08 Jun 2021
Topic Review
Visual Adaptations in Raptors
Ecological diversity among diurnal birds of prey, or raptors, is highlighted regarding their sensory abilities. While raptors are believed to forage primarily using sight, the sensory demands of scavengers and predators differ, as reflected in their visual systems. Here, I have reviewed the visual specialisations of predatory and scavenging diurnal raptors, focusing on (1) the anatomy of the eye and (2) the use of vision in foraging. Predators have larger eyes than scavengers relative to their body mass, potentially highlighting the higher importance of vision in these species. Scavengers possess one centrally positioned fovea that allows for the detection of carrion at a distance. In addition to the central fovea, predators have a second, temporally positioned fovea that views the frontal visual field, possibly for prey capture. Spatial resolution does not differ between predators and scavengers. In contrast, the organisation of the visual fields reflects important divergences, with enhanced binocularity in predators opposed to an enlarged field of view in scavengers. Predators also have a larger blind spot above the head. The diversity of visual system specializations according to the foraging ecology displayed by these birds suggests a complex interplay between visual anatomy and ecology, often unrelatedly of phylogeny.
  • 3.7K
  • 09 Nov 2020
Topic Review
Fabrication Techniques Using Myco-Materials
Within Euro-centric traditions of architecture, the significance of a building is often tied to its permanence. The Pantheon in Rome, for example, is a nearly 2000-year-old cementitious dome structure, whose resilience to time elevates it to a monumental status. Notwithstanding the significance of cultural and economic factors associated with the need for permanent buildings and structures, there is a doubt on whether all buildings should be assembled with the goal of being permanent. Globally, the lifespans of buildings are rapidly decreasing. The average lifespan of buildings in China was reported to be 34 years, and 25 years for residential buildings in Japan. To great detriment, buildings are more than ever being demolished prematurely and yet, use materials that are manufactured with energy-intensive processes and are expensive or impractical to recycle. In the United States alone, the Environmental Protection Agency (EPA) reported there was 600 million tons of construction and demolition waste generated in 2018. Structural materials, including wood, and architectural metals, such as steel, copper, and brass, are valuable commodities that can be reused and recycled. However, in present-day architectural assemblies, these materials nearly ubiquitously inter-face with expanded foams, plastics, and resins, sometimes in irreversible composites. For example, wood is widely treated with synthetic resins and glues to increase its resistance to decay or structural performance.
  • 3.7K
  • 28 Sep 2022
Topic Review
Occupational Safety and Health Management System Standards
Occupational accidents present a momentous effect on human well-being and, in addition, create large costs in any country’s social health/insurance system. Moreover, the topic of “safety and health” (OSH, OS&H) or “health and safety” (OHS, OH&S) concerning labor (or occupational work) is one of the most significant issues in any corporation. OSHMS systems were developed as a consequence of a plethora of several and severe industrial accidents throughout the decades of the 1970s and 1980s (for example, the Flixborough accident in 1974, the Seveso incident in 1976, and the Piper Alpha disaster in 1987). Thorough examinations of these events revealed insufficiencies in the dominant techniques for the regulation and the management of OSH and determined the necessity to use approaches that methodically address both engineering and educational action. The proliferation of OSH management systems, which have been used worldwide since the 1990s, has dramatically increased the concentration of performance measurement methods, tools, and techniques.
  • 3.7K
  • 04 Nov 2022
Topic Review
PEC Reactors for Water/Wastewater Treatment
Now and in the coming years, how we use and treat water, greywater and wastewater will become more important. A suitably designed photoelectrocatalytic (PEC) reactor is one potential solution. The photoexcitation of suitable semiconducting materials in aqueous environments can lead to the production of reactive oxygen species (ROS). ROS can inactivate microorganisms and degrade a range of chemical compounds. In the case of heterogeneous photocatalysis, semiconducting materials may suffer from fast recombination of electron–hole pairs and require post-treatment to separate the photocatalyst when a suspension system is used. To reduce recombination and improve the rate of degradation, an externally applied electrical bias can be used where the semiconducting material is immobilised onto an electrically conducive support and connected to a counter electrode. These electrochemically assisted photocatalytic systems have been termed “photoelectrocatalytic” (PEC). The term is stated in the IUPAC Recommendations 2011 as “electrochemically assisted photocatalysis. The role of the photocatalyst is played by a photoelectrode, often a semiconductor”. A short description of photocatalysis is included as it can be beneficial for those unfamiliar with the topic, before moving onto PEC. This entry is adapted from https://doi.org/10.3390/w13091198
  • 3.7K
  • 20 Oct 2021
Topic Review
Mechanical Properties and Microstructure of Ti6Al4V by LPBF
Ti6Al4V alloy is an ideal lightweight structural metal for a huge variety of engineering applications due to its distinguishing combination of high specific mechanical properties, excellent corrosion resistance and biocompatibility. Laser Powder Bed Fusion (LPBF) provides very different mechanical properties from that of casting or wrought Ti6Al4V. The inherent specificities of the LPBF process, as the layer-by-layer building strategy; the powder feedstock; the melting phenomena and thermal gradients, define the mechanical properties, once they will dictate the microstructural features (e.g. grain size, crystal growth direction, residual porosity and defects, among other). 
  • 3.7K
  • 16 Jun 2022
Topic Review
Doctor of Medicine
Doctor of Medicine (abbreviated M.D., from the Latin Medicinae Doctor) is a medical degree, the meaning of which varies between different jurisdictions. In the United States , and some other countries, the M.D. denotes a professional graduate degree. This generally arose because many in 18th-century medical professions trained in Scotland, which used the M.D. degree nomenclature. In England, however, Bachelor of Medicine, Bachelor of Surgery was used and eventually in the 19th century became the standard in Scotland too. Thus, in the United Kingdom , Ireland and other countries, the M.D. is a research doctorate, higher doctorate, honorary doctorate or applied clinical degree restricted to those who already hold a professional degree (Bachelor's/Master's/Doctoral) in medicine; in those countries, the equivalent professional to the North American and some others use of M.D. is still typically titled Bachelor of Medicine, Bachelor of Surgery (M.B.B.S.).
  • 3.7K
  • 19 Oct 2022
Topic Review
Geosynchronous Satellite Launch Vehicle Mark III
The Geosynchronous Satellite Launch Vehicle Mark III (GSLV-III), also referred to as the Launch Vehicle Mark 3 (LVM3) is a three-stage medium-lift launch vehicle developed by the Indian Space Research Organisation (ISRO). It is designed to launch satellites into geostationary orbit and is intended as a launch vehicle for crewed missions under the Indian Human Spaceflight Programme. The GSLV-III has a higher payload capacity than the similarly named GSLV. After several delays and a sub-orbital test flight on 18 December 2014, ISRO successfully conducted the first orbital test launch of GSLV-III on 5 June 2017 from the Satish Dhawan Space Centre, Andhra Pradesh. A second orbital test flight is planned for October 2018. In June 2018, the Union Cabinet approved ₹4,338 crore (US$610 million) to build 10 GSLV Mk-III rockets over a five-year period. On 15 August 2018, Indian Prime Minister Narendra Modi announced in his Independence Day speech an Indian foray into human spaceflight in 2022 with the aim of sending a crewed spacecraft called Gaganyaan to low Earth orbit. The GSLV Mk III will be the launch vehicle for this mission.
  • 3.7K
  • 13 Oct 2022
Topic Review
Natural Fiber Composites
Recent advancements in natural fiber composites have minimized the usage of man-made fibers, especially in the field of structural applications such as aircraft stiffeners and rotor blades. However, large variations in the strength and modulus of natural fiber degrade the properties of the composites and lower the safety level of the structures under dynamic load. Without compromising the safety of the composite structure, it is significant to enrich the strength and modulus of natural fiber reinforcement for real-time applications.
  • 3.7K
  • 17 May 2022
Topic Review
Taboo Language in Audiovisual Translation
Translating taboo language is a daunting task and solving it with spatial-temporal constraints makes it even more challenging. Taboo language, or emotionally charged language, is often toned down in audiovisual translation (AVT) by deleting the words and expressions, if space is limited, or by using euphemisms. Studies have focused on increasingly diverse subtitling strategies and techniques in rendering taboo language in professional and non-professional subtitling (NPS). Some scholars noted the fluidity, heterogeneity, and fuzziness of NPS. One of the main issues is that this NPS term implies the lack of professional training and thus poor translation quality, neglecting the creative and flexible nature of this kind of subtitling practice.
  • 3.7K
  • 23 Jun 2022
Topic Review
Character Strengths and Virtues
The VIA Inventory of Strengths (VIA-IS), formerly known as the "Values in Action Inventory," is a proprietary psychological assessment measure designed to identify an individual's profile of character strengths. It was created by Christopher Peterson and Martin Seligman, well-known researchers in the field of positive psychology, in order to operationalize their Character Strengths and Virtues Handbook (CSV). The CSV is the positive psychology counterpart to the Diagnostic and Statistical Manual of Mental Disorders (DSM) used in traditional psychology. Unlike the DSM, which scientifically categorizes human deficits and disorders, the CSV classifies positive human strengths. Moreover, the CSV is centered on helping people recognize and build upon their strengths. This aligned with the overall goal of the positive psychology movement, which aims to make people's lives more fulfilling, rather than simply treating mental illness. Notably, the VIA-IS is the tool by which people can identify their own positive strengths and learn how to capitalize on them.
  • 3.7K
  • 25 Oct 2022
Topic Review Peer Reviewed
Nanotechnology-Enabled COVID-19 mRNA Vaccines
COVID-19 mRNA vaccines contain synthetic mRNA sequences encoded for the Spike proteins expressed on the surface of SARS-CoV-2, and utilize the host cells to produce specific antigens that stimulate both humoral and cellular immunities. Lipid nanoparticles are essential to facilitate the intracellular delivery of the mRNA to its action site, the ribosome, to fully exert its effect.
  • 3.7K
  • 13 Apr 2022
Topic Review
Electrospun Nanofibers: Basic Principles
Electrospun nanofibers had been gaining importance in several areas such as the biomedical, environmental, food, textile, and biotechnology industries, amongst others. The fabrication of three-dimensional membranes through the electrospinning technique confers several characteristics that are important in the above industrial approaches such as high-to-volume radio, high surface area, controllable porosity, thickness, and mechanical properties, also the non-toxicity, biocompatibility, and biodegradability can be conferred to the scaffolds by choosing the adequate polymeric formulation. This entry discusses the characteristics and importance of electrospun nanofibers in industry.
  • 3.7K
  • 13 Aug 2021
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