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Topic Review
Fly Ash
Fly ash or coal fly ash causes major global pollution in the form of solid waste and is classified as a “hazardous waste”, which is a by-product of thermal power plants produced during electricity production. Si, Al, Fe Ca, and Mg alone form more than 85% of the chemical compounds and glasses of most fly ashes. Fly ash has a chemical composition of 70–90%, as well as glasses of ferrous, alumina, silica, and CaO. Therefore, fly ash could act as a reliable and alternative source for ferrous, alumina, and silica. The ferrous fractions can be recovered by a simple magnetic separation method, while alumina and silica can be extracted by chemical or biological approaches. Alumina extraction is possible using both alkali- and acid-based methods, while silica is extracted by strong alkali, such as NaOH. Chemical extraction has a higher yield than the biological approaches, but the bio-based approaches are more environmentally friendly. Fly ash can also be used for the synthesis of zeolites by NaOH treatment of variable types, as fly ash is rich in alumino-silicates. The present review work deals with the recent advances in the field of the recovery and synthesis of ferrous, alumina, and silica micro and nanoparticles from fly ash.
  • 8.5K
  • 06 Apr 2021
Topic Review
SpaceX Dragon 2
The SpaceX Dragon 2 is a class of reusable spacecraft developed and manufactured by American aerospace manufacturer SpaceX as the successor to the Dragon cargo spacecraft. It has two variants: Crew Dragon, a human-rated capsule capable of ferrying up to seven astronauts, and Cargo Dragon, an updated replacement for the original Dragon spacecraft. The spacecraft launches atop a Falcon 9 Block 5 rocket and returns to Earth via an ocean splashdown. Unlike its predecessor, the spacecraft can dock itself to the ISS instead of being berthed. Crew Dragon is equipped with an integrated launch escape system (LES) capable of accelerating the vehicle away from the rocket in an emergency at 11.8 m/s2, accomplished by using a set of four side-mounted thruster pods with two SuperDraco engines each. The spacecraft features redesigned solar arrays and a modified outer mold line compared to the original Dragon, and possess new flight computers and avionics. As of March 2020, four Dragon 2 spacecraft have been manufactured (not counting structural test articles that were never airborne). Crew Dragon serves as one of two spacecraft that is expected to transport crews to and from the International Space Station (ISS) under NASA's Commercial Crew Program, the other being the Boeing CST-100 Starliner. It is also expected to be used in flights by American space tourism company Space Adventures and to shuttle tourists to and from Axiom Space's planned space station. Crew Dragon's first non-piloted test flight occurred in March 2019, and its first crewed flight – with astronauts Robert Behnken and Douglas Hurley – occurred in May 2020. This test flight marked the first time a private company launched a crewed orbital spacecraft. Cargo Dragon is expected to supply cargo to the ISS under a Commercial Resupply Services-2 contract with NASA, along with Northrop Grumman Innovation Systems' Cygnus spacecraft and Sierra Nevada Corporation's Dream Chaser spacecraft. The first flight of the Cargo Dragon is planned to launch in October 2020.
  • 8.5K
  • 26 Oct 2022
Topic Review
Estimation of Maize Yield Per Harvest Area
Maize (Zea mays L.) is one of the most important annual cereal crops in the world, providing a staple food, and being used as source of income for many populations in developing countries. Different methods can be used for estimating maize yields depending on the purpose for which the crop was produced. The estimation of yield can be calculated using kernel weight at harvest, plot area harvested, plant density, and moisture content of grain at harvest. 
  • 8.5K
  • 10 Jan 2022
Topic Review
Platypus
The platypus (Ornithorhynchus anatinus), sometimes referred to as the duck-billed platypus, is a semiaquatic, egg-laying mammal endemic to eastern Australia, including Tasmania. The platypus is the sole living representative or monotypic taxon of its family (Ornithorhynchidae) and genus (Ornithorhynchus), though a number of related species appear in the fossil record. Together with the four species of echidna, it is one of the five extant species of monotremes, mammals that lay eggs instead of giving birth to live young. Like other monotremes, it senses prey through electrolocation. It is one of the few species of venomous mammals, as the male platypus has a spur on the hind foot that delivers a venom, capable of causing severe pain to humans. The unusual appearance of this egg-laying, duck-billed, beaver-tailed, otter-footed mammal baffled European naturalists when they first encountered it, and the first scientists to examine a preserved platypus body (in 1799) judged it a fake, made of several animals sewn together. The unique features of the platypus make it an important subject in the study of evolutionary biology, and a recognisable and iconic symbol of Australia . It is culturally significant to several Aboriginal peoples of Australia, who also used to hunt the animal for food. It has appeared as a mascot at national events and features on the reverse of the Australian twenty-cent coin, and the platypus is the animal emblem of the state of New South Wales. Until the early 20th century, humans hunted the platypus for its fur, but it is now protected throughout its range. Although captive-breeding programs have had only limited success, and the platypus is vulnerable to the effects of pollution, it is not under any immediate threat. (As of 2020), the platypus is a legally protected species in all states where it occurs. It is listed as an endangered species in South Australia and Victoria and has been recommended for listing in New South Wales. The species is classified as a near-threatened species by the IUCN, but a November 2020 report has recommended that it is upgraded to threatened species under the federal EPBC Act, due to habitat destruction and declining numbers in all states.
  • 8.5K
  • 18 Nov 2022
Topic Review Peer Reviewed
Natural Disasters: Origins, Impacts, Management
Natural hazards are processes that serve as triggers for natural disasters. Natural hazards can be classified into six categories. Geophysical or geological hazards relate to movement in solid earth. Their examples include earthquakes and volcanic activity. Hydrological hazards relate to the movement of water and include floods, landslides, and wave action. Meteorological hazards are storms, extreme temperatures, and fog. Climatological hazards are increasingly related to climate change and include droughts and wildfires. Biological hazards are caused by exposure to living organisms and/or their toxic substances. The COVID-19 virus is an example of a biological hazard. Extraterrestrial hazards are caused by asteroids, meteoroids, and comets as they pass near earth or strike earth. In addition to local damage, they can change earth inter planetary conditions that can affect the Earth’s magnetosphere, ionosphere, and thermosphere. This entry presents an overview of origins, impacts, and management of natural disasters. It describes processes that have potential to cause natural disasters. It outlines a brief history of impacts of natural hazards on the human built environment and the common techniques adopted for natural disaster preparedness. It also lays out challenges in dealing with disasters caused by natural hazards and points to new directions in warding off the adverse impact of such disasters. 
  • 8.5K
  • 13 Apr 2022
Topic Review
Green Monopropellants
Green propellants are usually defined as low-hazard, low-toxicity, environmentally friendly propellants that are considered safe during various phases of spacecraft development, launch, and operations. Such propellants provide safe handling and storability when compared to conventional toxic propellants such as hydrazine and its derivatives that require special handling protocols and adhering to strict safety measurements that, in addition to others, include using Self-Contained Atmospheric Protective Ensemble (SCAPE) suits. Due to their favorable characteristics, green propellants demonstrate higher commercial value by being able to cut costs related to transportation, storage, handling, and further reduces ground operations time. Recently, a more specified definition has been noted by Mayer et al. (2018) [3], based on the Acute Toxicity Classification (ATC) by the Global Harmonized System of classification and labeling of chemicals (GHS) [6], which denotes that propellants possessing ATC levels of three and safer are considered as green propellants. ATC levels are typically categorized on a 1:5 scale where level one denotes the most toxic class and level five is considered the least toxic class. Moreover, a controversial topic arises when referring to some modern green propellants, whether to address them by the term “monopropellants” or by more specific terms including (premixed propellants, fuel blends, or mixtures). Monopropellants are fundamentally defined as propellants consisting of chemical compounds (for example N2H4), which release energy through exothermic chemical decomposition. Since the evolution of liquid gun propellants based on HAN compound and other nitrate salts aqueous solutions, the term “monopropellants” was used to describe such premixed formulations. As widely used in literature and industry, some modern green propellants, for instance the Energetic Ionic Liquids (EILs), are undoubtedly classified and described as “monopropellants.” Basically, it can be interpreted from the previous that a "green monopropellant" may be defined as: "A low-hazard, low-toxicity, and safe-to handle propellant that is stored in a single tank and is able to decompose from its storage state by the help of a catalyst or other ignition method, such as thermal or electric ignition, can be considered a “green monopropellant” as long as it does not require another separately stored propellant for decomposition."
  • 8.5K
  • 28 Sep 2021
Topic Review
Social Complexity
Social complexity refers to the intricate and interconnected nature of social systems, where various elements such as institutions, individuals, and cultural dynamics interact in non-linear and unpredictable ways. It involves the recognition that social phenomena often exhibit emergent properties that cannot be fully understood by analyzing individual components in isolation, emphasizing the need for interdisciplinary approaches to grasp the complexity of social structures and behaviors.
  • 8.5K
  • 26 Jan 2024
Topic Review
Segmentation
Segmentation in biology is the division of some animal and plant body plans into a series of repetitive segments. This article focuses on the segmentation of animal body plans, specifically using the examples of the taxa Arthropoda, Chordata, and Annelida. These three groups form segments by using a "growth zone" to direct and define the segments. While all three have a generally segmented body plan and use a growth zone, they use different mechanisms for generating this patterning. Even within these groups, different organisms have different mechanisms for segmenting the body. Segmentation of the body plan is important for allowing free movement and development of certain body parts. It also allows for regeneration in specific individuals.
  • 8.4K
  • 29 Sep 2022
Biography
John Olsen Lear
John Olsen Lear (December 3, 1942 – March 29, 2022) was an influential conspiracy theorist, record-breaking pilot, and a one-time candidate for State Senate.[1][2][3] Unlike previous UFO conspiracy theorists, Lear promoted a story of alien collusion with secret governmental forces.[1] Lear's tale left a lasting influence on the UFO movement -- one author observed "in the early years [UFO writ
  • 8.4K
  • 14 Dec 2022
Topic Review
Theories of International Trade
Economists have developed theories explaining World Trade, which are called” theories of international trade”. Theories of international trade explain what exactly happens in international trade, such as mercantilist theory. This theory was popular in the sixteenth and eighteenth centuries. During that time, a nation’s wealth consisted only of gold or other types of precious metals, so theorists suggested that nations begin to accumulate more and more gold and other types of metals. 
  • 8.4K
  • 08 Jul 2022
Topic Review
Addiction and Spending in Gacha Games
Gacha games are the most dominant games on the mobile market. These are free-to-play games with a lottery-like system, where the user pays with in-game currency to enter a draw in order to obtain the character or item they want. If a player does not obtain what he hoped for, there is the option of paying with his own money for more draws, and this is the main way to monetize the Gacha game.
  • 8.4K
  • 21 Jul 2023
Topic Review
BMW 5 Series Gran Turismo
The BMW 5 Series Gran Turismo (also referred to as "5 Series GT") models are the 5-door fastback versions of the F10 5 Series model range and use the model code F07. The F07 uses the F10 platform and shares many components with the other 5 Series models. It was released in 2009. Engine choices were turbocharged straight-6 petrol, straight-6 diesel and V8 petrol. At launch, all models were rear-wheel drive ("sDrive"), with all-wheel drive ("xDrive") models being added in 2010. For the following G30 generation, the Gran Turismo models were moved to the 6 Series model range and renamed the G32 6 Series Gran Turismo.
  • 8.4K
  • 29 Sep 2022
Topic Review
Grinder (Biohacking)
Grinders are people who apply the hacker ethic to improve their own bodies with do it yourself cybernetic devices or introducing Biochemicals into the body to enhance or change their bodies' functionality. Many grinders identify with the biopunk movement, open-source transhumanism, and techno-progressivism. The Grinder movement is strongly associated with the body modification movement and practices actual implantation of cybernetic devices in organic bodies as a method of working towards transhumanism, such as designing and installing do-it-yourself body-enhancements such as magnetic implants. Biohacking emerged in a growing trend of non-institutional science and technology development. According to Biohack.me, "Grinders are passionate individuals who believe the tools and knowledge of science belong to everyone. Grinders practice functional extreme body modification in an effort to improve the human condition. [Grinders] hack [them]selves with electronic hardware to extend and improve human capacities. Grinders believe in action, [thei]r bodies the experiment." "Biohacking" can also refer to managing one's own biology using a combination of medical, nutritional and electronic techniques. This may include the use of nootropics, non-toxic substances, and/or cybernetic devices for recording biometric data (as in the Quantified Self movement).
  • 8.4K
  • 21 Nov 2022
Topic Review
Red Supergiant Star
Red supergiants (RSGs) are stars with a supergiant luminosity class (Yerkes class I) of spectral type K or M. They are the largest stars in the universe in terms of volume, although they are not the most massive or luminous. Betelgeuse and Antares are the brightest and best known red supergiants (RSGs), indeed the only first magnitude red supergiant stars.
  • 8.4K
  • 18 Nov 2022
Topic Review
Semaphore Telegraph
A semaphore telegraph is an early system of conveying information by means of visual signals, using towers with pivoting shutters, also known as blades or paddles. Information is encoded by the position of the mechanical elements; it is read when the shutter is in a fixed position. The most widely used system was invented in 1792 in France by Claude Chappe, and was popular in the late eighteenth to early nineteenth centuries. Lines of relay towers with a semaphore rig at the top were built within line-of-sight of each other, at separations of 5–20 miles (8.0–32.2 km). Operators at each tower would watch the neighboring tower through a spyglass, and when the semaphore arms began to move spelling out a message, they would pass the message on to the next tower. This system was much faster than post riders for conveying a message over long distances, and also had cheaper long-term operating costs, once constructed. Semaphore lines were a precursor of the electrical telegraph, which would replace them half a century later, and would also be cheaper, faster, and more private. The line-of-sight distance between relay stations was limited by geography and weather, and prevented the optical telegraph from crossing wide expanses of water, unless a convenient island could be used for a relay station. Modern derivatives of the semaphore system include flag semaphore (a flag relay system) and the heliograph (optical telegraphy using mirror-directed sunlight reflections).
  • 8.4K
  • 28 Nov 2022
Topic Review
Pollen Germination in Gymnosperms
Gymnosperms are amazing representatives of the flora. On the one hand, they are ancient plants with primitive characteristics of anatomical structure; on the other hand, they are perfectly adapted to their habitat and are the dominant species in many ecosystems due to their impressive size and longevity, with their reproductive system being of particular interest. It has progressive features, because in this group the reduced male gametophyte—pollen grain—first appeared, as well as the ability to form seeds. In addition, this group still represents a wide variety of reproductive patterns, strategies, and relationships. For example, the degree of gametophyte reduction varies, there are both zooidogamy and siphonogamy, and the reproductive process can both be relatively fast and last over several years.
  • 8.4K
  • 20 Jul 2021
Topic Review
Derringer
A derringer is a small handgun that is neither a revolver nor a semi/fully automatic pistol. It is not to be confused with mini-revolvers or pocket pistols, although some later derringers were manufactured with the pepperbox configuration. The modern derringer is often multi-barreled, and is generally the smallest usable handgun of any given caliber and barrel length due to the lack of a moving action, which takes up more space behind the barrel. It is frequently used by women because it is easily concealable in a purse or a stocking. The original Philadelphia Deringer was a muzzleloading caplock single-shot pistol introduced in 1825 by Henry Deringer. In total, approximately 15,000 Deringer pistols were manufactured. All were single barrel pistols with back-action percussion locks, typically .41 caliber with rifled bores, and walnut stocks. Barrel length varied from 1.5 to 6 in (38 to 152 mm), and the hardware was commonly a copper-nickel alloy known as "German silver". The term "derringer" (/ˈdɛrɪndʒər/) became a genericized misspelling during the reporting of the Lincoln assassination, which was committed with a concealed Philadelphia Deringer. Many copies of the original Philadelphia Deringer pistol were made by other gunmakers worldwide, and the name remained often misspelled; this misspelling soon became an alternative generic term for any pocket pistol, along with the generic phrase "palm pistol'", which Deringer's competitors invented and used in their advertising. With the advent of metallic cartridges, pistols produced in the modern form are still commonly called "derringers".
  • 8.4K
  • 01 Nov 2022
Topic Review
Terminology of the British Isles
The terminology of the British Isles refers to the various words and phrases that are used to describe the different (and sometimes overlapping) geographical and political areas of the islands of Great Britain, Ireland, and the smaller islands which surround them. The terminology is often a source of confusion, partly owing to the similarity between some of the actual words used, but also because they are often used loosely. In addition, many of the words carry both geographical and political connotations which are affected by the history of the islands. The purpose of this article is to explain the meanings of and relationships among the terms in use; however many of these classifications are contentious and are the subject of disagreement (See the British Isles naming dispute).
  • 8.4K
  • 03 Nov 2022
Topic Review
Seaport
Seaports are well known as the medium that has evolved into the central link between sea and land for complex marine activities. The growth in maritime logistics particularly necessitates a large volume of energy supply in order to maintain the operation of sea trade, resulting in an imbalance between generation and demand sides. Future projections for three major concerns show an increase in load demand, cost of operation, and environmental issues. The involvement of a variety of heavy loads such as all-electric ships, cranes, cold ironing, and buildings infrastructure renders it a complicated arrangement task in several aspects, which necessitates further research and leaves space for improvement.
  • 8.4K
  • 06 Dec 2021
Topic Review
The Sims 3 Stuff Packs
Stuff packs are minor expansion packs for The Sims 3 that add new items, clothing, and furniture to the game without implementing any significant changes to gameplay.
  • 8.4K
  • 11 Nov 2022
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