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Metaverse
The Metaverse is the post-reality universe, a perpetual and persistent multiuser environment merging physical reality with digital virtuality. It is based on the convergence of technologies that enable multisensory interactions with virtual environments, digital objects and people such as virtual reality (VR) and augmented reality (AR). Hence, the Metaverse is an interconnected web of social, networked immersive environments in persistent multiuser platforms. It enables seamless embodied user communication in real-time and dynamic interactions with digital artifacts. Its first iteration was a web of virtual worlds where avatars were able to teleport among them. The contemporary iteration of the Metaverse features social, immersive VR platforms compatible with massive multiplayer online video games, open game worlds and AR collaborative spaces.
  • 5.1K
  • 13 Apr 2022
Topic Review
Transparency for Architecture
Rowe and Slutzky proposed two types of transparency in architecture in the essay, “Transparency: Literal and Phenomenal”. They divided transparency into literal, meaning the material conditions of glass, and phenomenal, as derived from Cubist paintings. “literal transparency” describes the material quality of being see-through, and phenomenal transparency describes the perceptual attributes that allow the mind to discern the underlying governing concepts or spatial concepts. Through their idea of “phenomenal transparency”, they primarily investigated the relationship of visual perceptions using the human eye with superimposed two-dimensional visions of architectural space and the world.
  • 5.1K
  • 27 Aug 2021
Topic Review
Induction of Polyploidy
Polyploidy has the utmost importance in horticulture for the development of new ornamental varieties with desirable morphological traits referring to plant size and vigor, leaf thickness, larger flowers with thicker petals, intense color of leaves and flowers, long lasting flowers, compactness, dwarfness and restored fertility. Polyploidy may occur naturally due to the formation of unreduced gametes or can be artificially induced by doubling the number of chromosomes in somatic cells.
  • 5.1K
  • 21 Dec 2021
Topic Review
Mac OS Memory Management
Historically, the classic Mac OS used a form of memory management that has fallen out of favor in modern systems. Criticism of this approach was one of the key areas addressed by the change to Mac OS X. The original problem for the engineers of the Macintosh was how to make optimum use of the 128 KB of RAM with which the machine was equipped, on Motorola 68000-based computer hardware that did not support virtual memory. Since at that time the machine could only run one application program at a time, and there was no fixed secondary storage, the engineers implemented a simple scheme which worked well with those particular constraints. That design choice did not scale well with the development of the machine, creating various difficulties for both programmers and users.
  • 5.1K
  • 15 Nov 2022
Topic Review
School Strike for the Climate
The school strike for the climate (Swedish: Skolstrejk för klimatet), also known variously as Fridays for Future (FFF), Youth for Climate, Climate Strike or Youth Strike for Climate, is an international movement of school students who take time off from class on Fridays to participate in demonstrations to demand action from political leaders to take action to prevent climate change and for the fossil fuel industry to transition to renewable energy. Publicity and widespread organising began after Swedish schoolgirl Greta Thunberg staged a protest in August 2018 outside the Swedish Riksdag (parliament), holding a sign that read "Skolstrejk för klimatet" ("School strike for the climate"). A global strike on 15 March 2019 gathered more than one million strikers. Around 2200 strikes were organised in 125 countries. On 24 May 2019, the second global strike took place, in which 1600 events across 150 countries drew hundreds of thousands of protesters. The events were timed to coincide with the 2019 European Parliament election. The 2019 Global Week for Future was a series of 4500 strikes across over 150 countries, focused around Friday 20 September and Friday 27 September. Likely the largest climate strikes in world history, 20 September strikes gathered roughly 4 million protesters, many of them schoolchildren, including 1.4 million people on strike in Germany. On 27 September, an estimated 2 million people participated in demonstrations worldwide, including over 1 million protesters in Italy and several hundred thousand protesters in Canada.
  • 5.1K
  • 06 Dec 2022
Topic Review
The Evolution of Food Security
Food security is one of the most challenging topics globally; however, the concept of food security has taken on additional dimensions that are general and are less detailed. Recognizing the factors that directly and indirectly affect food security will enable future researchers to focus on and study important topics. One of the important indicators of sustainable development is eliminating hunger and ensuring sustainable food security. International organizations and the WHO have various programs and measures to achieve this goal. The consequences of food insecurity, including hunger, malnutrition, and its direct or indirect effects on health and quality of life, have always been considered.
  • 5.1K
  • 23 Mar 2022
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.
  • 5.1K
  • 06 Apr 2021
Topic Review
Artificial Gravity in Fiction
Artificial gravity is a common theme in fiction, particularly science fiction.
  • 5.1K
  • 21 Oct 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. 
  • 5.1K
  • 08 Jul 2022
Topic Review
UAV-based IoT
The Internet of Things (IoT), which consists of a large number of small low-cost devices, has become a leading solution for smart cities, smart agriculture, smart buildings, smart grids, e-healthcare, etc. Integrating unmanned aerial vehicles (UAVs) with IoT can result in an airborne UAV-based IoT (UIoT) system and facilitate various value-added services from sky to ground. In addition to wireless sensors, various kinds of IoT devices are connected in UIoT, making the network more heterogeneous. In a UIoT system, for achieving high throughput in an energy-efficient manner, it is crucial to design an efficient medium access control (MAC) protocol because the MAC layer is responsible for coordinating access among the IoT devices in the shared wireless medium. Thus, various MAC protocols with different objectives have been reported for UIoT.
  • 5.1K
  • 07 Dec 2020
Topic Review
Post-transition Metal
Post-transition metals are a set of metallic elements in the periodic table located between the transition metals to their left, and the metalloids to their right. Depending on where these adjacent groups are judged to begin and end, there are at least five competing proposals for which elements to include: the three most common contain six, ten and thirteen elements, respectively (see image). All proposals include gallium, indium, tin, thallium, lead, and bismuth. Physically, post-transition metals are soft (or brittle), have poor mechanical strength, and have melting points lower than those of the transition metals. Being close to the metal-nonmetal border, their crystalline structures tend to show covalent or directional bonding effects, having generally greater complexity or fewer nearest neighbours than other metallic elements. Chemically, they are characterised—to varying degrees—by covalent bonding tendencies, acid-base amphoterism and the formation of anionic species such as aluminates, stannates, and bismuthates (in the case of aluminium, tin, and bismuth, respectively). They can also form Zintl phases (half-metallic compounds formed between highly electropositive metals and moderately electronegative metals or metalloids). The name is universally used, but not officially sanctioned by any organization such as the IUPAC. The origin of the term is unclear: one early use was in 1940 in a chemistry text. Alternate names for this group are B-subgroup metals, other metals, and p-block metals; and at least thirteen other labels.
  • 5.1K
  • 21 Nov 2022
Topic Review
Devil in Christianity
The Devil in Christianity is the personification of evil and author of sin, who rebelled against God in an attempt to become equal to God himself.[lower-alpha 1] He is depicted as a fallen angel, who was expelled from Heaven at the beginning of time, before God created the material world, and is in constant opposition to God. The devil is identified with several figures in the Bible including the serpent in the Garden of Eden, Lucifer, Satan, the tempter of the Gospels, Leviathan, and the dragon in the Book of Revelation. Early scholars discussed the role of the devil. Scholars influenced by neoplatonic cosmology, like Origen and Pseudo-Dionysius, portrayed the devil as representing deficiency and emptiness, the entity most remote from the divine. According to Augustine of Hippo the realm of the devil is not nothingness, but an inferior realm standing in opposition to God. The standard Medieval depiction of the devil was set up by Gregory the Great. He integrated the devil, as the first creation of God, into the Christian angelic hierarchy as the highest of the angels (either a cherub or a seraph). But as high as he stood in heaven, so far he fell into the depths of hell and became the leader of demons. Since the early reformation period, the devil was imagined as an increasingly powerful entity, with not only a lack of goodness but also a conscious will against God, his word, and his creation. Simultaneously, some reformists interpreted the devil as a mere metaphor for human's inclination to sin and so downgraded the importance of the devil. While the devil played for most scholars no significant role in the Modern Era, he became more important in contemporary Christianity again. At various times in history, some people such as the Cathars and the Bogomiles, as well as theologians like Marcion and Valentinus, believed that the devil was involved in creating the world. Today these views are not part of mainstream Christianity.
  • 5.1K
  • 06 Dec 2022
Topic Review
Cluster Chemistry
In chemistry, a cluster is an ensemble of bound atoms or molecules that is intermediate in size between a molecule and a bulk solid. Clusters exist of diverse stoichiometries and nuclearities. For example, carbon and boron atoms form fullerene and borane clusters, respectively. Transition metals and main group elements form especially robust clusters. Clusters can also consist solely of a certain kind of molecules, such as water clusters. The phrase cluster was coined by F.A. Cotton in the early 1960s to refer to compounds containing metal–metal bonds. In another definition a cluster compound contains a group of two or more metal atoms where direct and substantial metal bonding is present. The prefixed terms "nuclear" and "metallic" are used and imply different meanings. For example, polynuclear refers to a cluster with more than one metal atom, regardless of the elemental identities. Heteronuclear refers to a cluster with at least two different metal elements. The main cluster types are "naked" clusters (without stabilizing ligands) and those with ligands. For transition metal clusters, typical stabilizing ligands include carbon monoxide, halides, isocyanides, alkenes, and hydrides. For main group elements, typical clusters are stabilized by hydride ligands. Transition metal clusters are frequently composed of refractory metal atoms. In general metal centers with extended d-orbitals form stable clusters because of favorable overlap of valence orbitals. Thus, metals with a low oxidation state for the later metals and mid-oxidation states for the early metals tend to form stable clusters. Polynuclear metal carbonyls are generally found in late transition metals with low formal oxidation states. The polyhedral skeletal electron pair theory or Wade's electron counting rules predict trends in the stability and structures of many metal clusters. Jemmis mno rules have provided additional insight into the relative stability of metal clusters.
  • 5.1K
  • 08 Nov 2022
Topic Review
Hydrogen Storage Technologies
Storage is an essential topic when it comes to hydrogen integration in distribution networks and large-scale applications; the existence of a robust and reliable way of storing this energy vector is crucial to addressing the current potential demand for hydrogen in the energy market. Many forms of storage have been developed, which can mainly be divided into Physical-based and Material-based approaches. Physical storage includes compressed gas, liquid, and cryo-compressed hydrogen, and it is the most widely used storage type among these systems. 
  • 5.1K
  • 26 May 2022
Topic Review
VARTM Processed Composite Materials
Fiber-reinforced composite structures are used in different applications due to their excellent strength to weight ratio. Due to cost and tool handling issues in conventional manufacturing processes, like resin transfer molding (RTM) and autoclave, vacuum-assisted resin transfer molding (VARTM) is the best choice among industries. VARTM is highly productive and cheap. However, the VARTM process produces complex, lightweight, and bulky structures, suitable for mass and cost-effective production, but the presence of voids and fiber misalignment in the final processed composite influences its strength. Voids are the primary defects, and they cannot be eliminated completely, so a design without considering void defects will entail unreliability. Many conventional failure theories were used for composite design but did not consider the effect of voids defects, thus creating misleading failure characteristics.
  • 5.1K
  • 07 Apr 2021
Topic Review
Fresh Fruit and Vegetable Waste in Human Health
Food supply disruption and shortage verified during the current pandemic events are a scenario that many anticipate for the near future. The impact of climate changes on food production, the continuous decrease in arable land, and the exponential growth of the human population are important drivers for this problem. 
  • 5.1K
  • 19 Jan 2023
Topic Review
Major Applications of Smart Agriculture
With the rise of new technologies, such as the Internet of Things, raising the productivity of agricultural and farming activities is critical to improving yields and cost-effectiveness. IoT, in particular, can improve the efficiency of agriculture and farming processes by eliminating human intervention through automation. The fast rise of Internet of Things (IoT)-based tools has changed nearly all life sectors, including business, agriculture, surveillance, etc. These radical developments are upending traditional agricultural practices and presenting new options in the face of various obstacles.
  • 5.1K
  • 24 Jan 2022
Topic Review
Deep Eutectic Solvents (DES)
Deep eutectic solvent (DES) are a highly non-ideal mixture of two biodegradable components (HBA and HBD) associated with strong hydrogen bonding interactions. 
  • 5.1K
  • 08 Mar 2022
Topic Review
Muslim World
The terms Muslim world and Islamic world commonly refer to the Islamic community, which is also known as the Ummah. This consists of all those who adhere to the religions beliefs and laws of Islam, or to societies where Islam is practiced. In a modern geopolitical sense, these terms refer to countries where Islam is widespread, although there are no agreed criteria for inclusion. The term Muslim-majority countries is an alternative often used for the latter sense. The history of the Muslim world spans about 1,400 years and includes a variety of socio-political developments, as well as advances in the arts, science, philosophy, and technology, particularly during the Islamic Golden Age. All Muslims look for guidance to the Quran and believe in the prophetic mission of the Islamic prophet Muhammad, but disagreements on other matters have led to the appearance of different religious schools of thought and sects within Islam. In the modern era, most of the Muslim world came under European colonial domination. The nation states that emerged in the post-colonial era have adopted a variety of political and economic models, and they have been affected by secular and as well as religious trends. (As of 2013), the combined GDP (nominal) of 49 Muslim majority countries was US$5.7 trillion, (As of 2016), they contributed 8% of the world's total. As of 2015, 1.8 billion or about 24.1% of the world population are Muslims. By the percentage of the total population in a region considering themselves Muslim, 91% in the Middle East-North Africa (MENA), 89% in Central Asia, 40% in Southeast Asia, 31% in South Asia, 30% in Sub-Saharan Africa, 25% in Asia–Oceania, around 6% in Europe, and 1% in the Americas. Most Muslims are of one of two denominations: Sunni Islam (85-90%) and Shia (10-15%), However, other denominations exist in pockets, such as Ibadi (primarily in Oman). About 13% of Muslims live in Indonesia, the largest Muslim-majority country; 31% of Muslims live in South Asia, the largest population of Muslims in the world; 20% in the Middle East–North Africa, where it is the dominant religion; and 15% in Sub-Saharan Africa and West Africa. Muslims are the overwhelming majority in Central Asia, the majority in the Caucasus and widespread in Southeast Asia. India is the country with the largest Muslim population outside Muslim-majority countries. Sizeable Muslim communities are also found in the Americas, China, and Europe. Islam is the fastest-growing major religion in the world.
  • 5.0K
  • 26 Oct 2022
Topic Review
Physiology of Plant Responses to Water Stress
Drought and waterlogging seriously affect the growth of plants and are considered severe constraints on agricultural and forestry productivity; their frequency and degree have increased over time due to global climate change. The morphology, photosynthetic activity, antioxidant enzyme system and hormone levels of plants could change in response to water stress. 
  • 5.0K
  • 23 May 2022
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