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Topic Review

The atomic radius of a chemical element is a measure of the size of its atom, usually the mean or typical distance from the center of the nucleus to the outermost isolated electron. Since the boundary is not a well-defined physical entity, there are various non-equivalent definitions of atomic radius. Four widely used definitions of atomic radius are: Van der Waals radius, ionic radius, metallic radius and covalent radius. Typically, because of the difficulty to isolate atoms in order to measure their radii separately, atomic radius is measured in a chemically bonded state; however theoretical calculations are simpler when considering atoms in isolation. The dependencies on environment, probe, and state lead to a multiplicity of definitions. Depending on the definition, the term may apply to atoms in condensed matter, covalently bonding in molecules, or in ionized and excited states; and its value may be obtained through experimental measurements, or computed from theoretical models. The value of the radius may depend on the atom's state and context. Electrons do not have definite orbits nor sharply defined ranges. Rather, their positions must be described as probability distributions that taper off gradually as one moves away from the nucleus, without a sharp cutoff; these are referred to as atomic orbitals or electron clouds. Moreover, in condensed matter and molecules, the electron clouds of the atoms usually overlap to some extent, and some of the electrons may roam over a large region encompassing two or more atoms. Under most definitions the radii of isolated neutral atoms range between 30 and 300 pm (trillionths of a meter), or between 0.3 and 3 ångströms. Therefore, the radius of an atom is more than 10,000 times the radius of its nucleus (1–10 fm), and less than 1/1000 of the wavelength of visible light (400–700 nm). For many purposes, atoms can be modeled as spheres. This is only a crude approximation, but it can provide quantitative explanations and predictions for many phenomena, such as the density of liquids and solids, the diffusion of fluids through molecular sieves, the arrangement of atoms and ions in crystals, and the size and shape of molecules.

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18 Oct 2022

Topic Review Peer Reviewed

Passivhaus or Passive House buildings are low-energy buildings in which the design is driven by quality and comfort, hence achieving acceptable levels of comfort through post-heating or post-cooling of fresh air. Additionally, Passivhaus building design follows the Passivhaus design criteria, as described in the Passive House Planning Package (PHPP). This article aims to introduce the Passivhaus background, development, and basic design principles. Finally, it also presents a brief description of the performance of Passivhaus buildings.

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18 Apr 2022

Topic Review

Chemical Industry in China

The chemical industry in China is one of China's main manufacturing industries. It valued at around $1.44 trillion in 2014, and China is currently the largest chemicals manufacturing economy in the world. The chemical industry is central to modern China's economy. It uses special methods to alter the structure, composition or synthesis of substances to produce new products, such as steel, plastic, and ethyl. Chemical industry provides building materials for China's infrastructure, including subway, high-speed train, and highway. Prior to 1978, most of the product was produced by the state-owned business, and the share in product outputted by state-owned business had decreased in 2002. The Chinese chemical industry is also one of the world's largest producers of both controlled and non-controlled precursor chemicals used in the Global illicit drug trade, particularly in the Golden Triangle as well as Latin America.

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26 Oct 2022

Topic Review

Beam-Squinting Effect in Broadband Mobile Communication

Due to the fact that the quality of the received signal is adversely affected by the beam squint phenomenon, which is especially pertinent to the millimeter wave (mmwave) bands, many studies have been utilised by other researchers to provide light on some of the challenges that come with analysing this type of occurrence. Squint causes several issues, the most important of which are its detrimental effects on gain, line of sight, angle of arrival, progressive phase, usable bandwidth, and fading effect. As a result of these obstacles, the advantages of adopting a high-frequency band such as mmwave in modern wireless communication systems are severely limited.

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06 Feb 2023

Topic Review

Gastrointestinal Diseases in Primary Immunodeficiencies

In recent years, the incidence of immune-mediated gastrointestinal disorders, including celiac disease (CeD) and inflammatory bowel disease (IBD), is increasingly growing worldwide. It is well established that primary immunodeficiencies (PIDs) exhibit gastrointestinal manifestations and mimic other diseases, including CeD and IBD. The most common PIDs in adults are the selective immunoglobulin A deficiency (SIgAD) and the common variable immunodeficiency (CVID). However, some differences concerning diagnostics and management between enteropathy/colitis in PIDs, as compared to idiopathic forms of CeD/IBD, have been described. There is an ongoing discussion whether CeD and IBD in CVID patients should be considered a true CeD and IBD or just CeD-like and IBD-like diseases. This review addresses the current state of the art of the most common primary immunodeficiencies in adults and co-occurring CeD and IBD.

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29 Oct 2020

Topic Review

Euphorbia neriifolia Linn.

Medicinal plants have considerable potential as antimicrobial agents due to the presence of secondary metabolites. Researchers aim to summarize the classification, morphology, and ethnobotanical uses of Euphorbia neriifolia L. and its derived phytochemicals with the recent updates on the pharmacological properties against emerging infectious diseases, mainly focusing on bacterial, viral, fungal, and parasitic infections.

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14 Jul 2022

Topic Review

Struvite Precipitation Technologies

The abatement of nutrient compounds from aqueous waste and wastewater is currently a priority issue. Indeed, the uncontrolled discharge of high levels of nutrients into water bodies causes serious deteriorations of environmental quality. On the other hand, the increasing request of nutrient compounds for agronomic utilizations makes it strictly necessary to identify technologies able to recover the nutrients from wastewater streams so as to avoid the consumption of natural resources. In this regard, the removal and recovery of nitrogen and phosphorus from aqueous waste and wastewater as struvite (MgNH4PO4·6H2O) represents an attractive approach. Indeed, through the struvite precipitation it is possible to effectively remove the ammonium and phosphate content of many types of wastewater and to produce a solid compound, with only a trace of impurities. This precipitate, due to its chemical characteristics, represents a valuable multi-nutrients slow release fertilizer for vegetables and plants growth. For these reasons, the struvite precipitation technology constantly progresses on several aspects of the process.

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08 Feb 2021

Topic Review

Yarrowia lipolytica

After having drawn some industrialists’ attention as early as the 1950s, the non-conventional oleaginous yeast Yarrowia lipolytica has been recognized since several decades, as a powerful host for heterologous protein expression, secretion and surface display. The development of sequencing and genetic engineering tools, combined with an increasing knowledge of its metabolism, have then facilitated the complex engineering of the metabolic pathways of this yeast for various applications. Since nearly two decades, numerous laboratories throughout the world have chosen Y. lipolytica as a chassis for designing microbial cell factories. White biotechnology applications of this yeast include notably single cell oil production, whole cell bioconversion and upgrading of industrial wastes.

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19 Jul 2021

Topic Review

Extraction Functional Ingredients from Jackfruit

Various studies in the literature showed the effect of conventional and non-conventional extraction methods to obtain jackfruit functional ingredients; among the non-conventional methods, some use emerging technologies to extract or as a pre-treatment. Among the studies using conventional extraction, applying solvents such as methanoland oxalic acidstands out, as well as the extraction with hot water. Regarding extraction by emerging technologies, radio frequency-assistedand supercritical fluid (SFE) with CO2extractions have attracted attention owing to their less negative impact on the environment and safety of the final product obtained in comparison with other methods using non-conventional technologies.

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26 Aug 2021

Topic Review

In management research, CEO power refers to the power that can override objections to influence key decision outcomes within the company. This power can be obtained in formal or informal ways.

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27 Aug 2021

Topic Review

Inhalants are a broad range of household and industrial chemicals whose volatile vapors or pressurized gases can be concentrated and breathed in via the nose or mouth to produce intoxication, in a manner not intended by the manufacturer. They are inhaled at room temperature through volatilization (in the case of gasoline or acetone) or from a pressurized container (e.g., nitrous oxide or butane), and do not include drugs that are sniffed after burning or heating. For example, amyl nitrite (poppers), nitrous oxide and toluene – a solvent widely used in contact cement, permanent markers, and certain types of glue – are considered inhalants, but smoking tobacco, cannabis, and crack are not, even though these drugs are inhaled as smoke or vapor. While a few inhalants are prescribed by medical professionals and used for medical purposes, as in the case of inhaled anesthetics and nitrous oxide (an anxiolytic and pain relief agent prescribed by dentists), this article focuses on inhalant use of household and industrial propellants, glues, fuels, and other products in a manner not intended by the manufacturer, to produce intoxication or other psychoactive effects. These products are used as recreational drugs for their intoxicating effect. According to a 1995 report by the National Institute on Drug Abuse, the most serious inhalant use occurs among homeless children and teenagers who "... live on the streets completely without family ties." Inhalants are the only substance used more by younger teenagers than by older teenagers. Inhalant users inhale vapor or aerosol propellant gases using plastic bags held over the mouth or by breathing from a solvent-soaked rag or an open container. The practices are known colloquially as "sniffing", "huffing" or "bagging". The effects of inhalants range from an alcohol-like intoxication and intense euphoria to vivid hallucinations, depending on the substance and the dose. Some inhalant users are injured due to the harmful effects of the solvents or gases or due to other chemicals used in the products that they are inhaling. As with any recreational drug, users can be injured due to dangerous behavior while they are intoxicated, such as driving under the influence. In some cases, users have died from hypoxia (lack of oxygen), pneumonia, heart failure or arrest, or aspiration of vomit. Brain damage is typically seen with chronic long-term use of solvents as opposed to short-term exposure. Even though many inhalants are legal, there have been legal actions taken in some jurisdictions to limit access by minors. While solvent glue is normally a legal product, a Scottish court has ruled that supplying glue to children is illegal if the store knows the children intend to inhale the glue. In the US, thirty-eight of 50 states have enacted laws making various inhalants unavailable to those under the age of 18 or making inhalant use illegal.

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28 Nov 2022

Topic Review

Modified Frequency Modulation

Modified Frequency Modulation, commonly MFM, is a run-length limited (RLL) coding scheme used to encode the actual data-bits on most floppy disks. It was first introduced in disk drives with the IBM 3330 hard disk drive in 1970. Floppy disk drive hardware examples include Amiga, most CP/M machines as well as IBM PC compatibles. MFM is a modification to the original digital FM (digital frequency modulation also known as delay coding) scheme for encoding data on single-density floppy disks and some early hard disk drives. Due to the minimum spacing between flux transitions that is a property of the disk, head and channel design, MFM, which guarantees at most one flux transition per data bit, can be written at higher density than FM, which can require two transitions per data bit. It is used with a data rate of 250–500 kbit/s (500–1000 kbit/s encoded) on industry standard 5¼-inch and 3½-inch ordinary and high density diskettes. MFM was also used in early hard disk designs, before the advent of more efficient types of run-length limited codes. Except for the steadily disappearing 360 KiB/1.2 MiB (5.25-inch) and 720~880 KiB/1.4~1.6 MiB (3.5-inch) floppy disk formats, MFM encoding is obsolete in magnetic recording.

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22 Nov 2022

Topic Review

Level of Consciousness (Esotericism)

Consciousness is a loosely defined concept that addresses the human awareness of both internal and external stimuli. This can refer to spiritual recognition, psychological understanding, medically altered states, or more modern-day concepts of life purpose, satisfaction, and self-actualization. Levels of Consciousness can be presented in a map. Some levels are more continuous or complex than others. Movement between levels or stages is often bidirectional depending on internal and external conditions, with each mental ascension precipitating a change in reactivity. In the most basic sense, this alteration might lead to a reduced responsiveness as seen in anesthesiology; more abstract facets of tiered consciousness describe characteristics of profoundness, insight, perception, or understanding. First appearing in the historical records of the ancient Mayan and Incan civilizations, proposals of multiple levels of consciousness have pervaded spiritual, psychological, medical, and moral speculations in both Eastern and Western cultures. Because of occasional and sometimes substantial overlap between hypotheses, there have recently been attempts to combine perspectives to form new models that integrate components of separate viewpoints. Any of these proposals, models or viewpoints can be verified or falsified, and are open to question.

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24 Nov 2022

Topic Review

Australian Modernism

Australian Modernism, similar to European and American Modernism was a social, political and cultural movement that was a reaction to rampant Industrialisation, associated moral panic of modernity and the death and trauma of the World Wars. This movement was predominately a reaction of female artists towards the male dominated art style of naturalism. It is also important to note the presence of Indigenous Art during this time of modernity. Indigenous Modernism refers to the unique experience of modernity of Aboriginal people that is vastly different to the White Australians experience of Modernity. The mainstream movement began in Australia approximately in 1914 and continued until 1948. Throughout these years tensions continued between the conservative and the Avant-garde schools of thought. The years following the Second World War is when Australian Modernism gained notability in the art world of Australia. Nationalistic pastoral painting of the Australian landscape were superseded by abstracted, colourful distorted images of Modernist works. After the World Wars the dynamics of society in Australia and overseas changed dramatically causing increased acceptance and attraction towards Modernism. Social and political unrest continued due to the devastation of war and increased immigration occurred. This caused a subsequent amount of European artists to travel to Australia to live. This contributed to the introduction of further art styles to Australia such as Surrealism, social realism and expressionism. Additionally, continued technological progress in the later 20th century contributed to an increase in cubism and print making. The first Indigenous Modernist or Modern Artist is said to be the Artists Albert Namatjira. He created art that aligned with the styles and techniques of western Modernism in Australia and Europe. It was not until the 1960s and 1970s that scholars began to call Indigenous Art Modern as there was a distinction made between Modern and Contemporary art to traditional Indigenous art. However, it is argued that all types of Indigenous Art is Modernist as it is all an aesthetic expression of Indigenous experiences of modernity.

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28 Sep 2022

Topic Review

Clustal is a series of widely used computer programs used in bioinformatics for multiple sequence alignment. There have been many versions of Clustal over the development of the algorithm that are listed below. The analysis of each tool and its algorithm are also detailed in their respective categories. Available operating systems listed in the sidebar are a combination of the software availability and may not be supported for every current version of the Clustal tools. Clustal Omega has the widest variety of operating systems out of all the Clustal tools.

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06 Oct 2022

Topic Review

Computer Designed Architecture and Architects

The designs generated by computer algorithms are becoming such a serious part of designers’ work that some are beginning to question whether they are more the work of computers than humans. There are also increasing suggestions that software development will eventually lead to a situation where humans in the profession will become redundant. This review article aims to present the currently used, implemented, and planned computer technologies employed in the design and consider how they affect and will affect the work of architects in the future.

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06 Sep 2021

Topic Review

Intersection (Euclidean Geometry)

In geometry, an intersection is a point, line, or curve common to two or more objects (such as lines, curves, planes, and surfaces). The simplest case in Euclidean geometry is the intersection of two distinct lines, which either is one point or does not exist if the lines are parallel. Determination of the intersection of flats – linear geometric objects embedded in a higher-dimensional space – is a simple task of linear algebra, namely the solution of a system of linear equations. In general the determination of an intersection leads to non-linear equations, which can be solved numerically, for example using Newton iteration. Intersection problems between a line and a conic section (circle, ellipse, parabola, etc.) or a quadric (sphere, cylinder, hyperboloid, etc.) lead to quadratic equations that can be easily solved. Intersections between quadrics lead to quartic equations that can be solved algebraically.

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31 Oct 2022

Topic Review

The Laser Interferometer Gravitational-Wave Observatory (LIGO) is a large-scale physics experiment and observatory to detect cosmic gravitational waves and to develop gravitational-wave observations as an astronomical tool. Two large observatories were built in the United States with the aim of detecting gravitational waves by laser interferometry. These can detect a change in the 4 km mirror spacing of less than a ten-thousandth the charge diameter of a proton, equivalent to measuring the distance from Earth to Proxima Centauri (4.0208x1013km) with an accuracy smaller than the width of a human hair. The initial LIGO observatories were funded by the National Science Foundation (NSF) and were conceived, built, and are operated by Caltech and MIT. They collected data from 2002 to 2010 but no gravitational waves were detected. The Advanced LIGO Project to enhance the original LIGO detectors began in 2008 and continues to be supported by the NSF, with important contributions from the UK Science and Technology Facilities Council, the Max Planck Society of Germany, and the Australian Research Council. The improved detectors began operation in 2015. The detection of gravitational waves was reported in 2016 by the LIGO Scientific Collaboration (LSC) and the Virgo Collaboration with the international participation of scientists from several universities and research institutions. Scientists involved in the project and the analysis of the data for gravitational-wave astronomy are organized by the LSC, which includes more than 1000 scientists worldwide, as well as 440,000 active Einstein@Home users (As of December 2016). LIGO is the largest and most ambitious project ever funded by the NSF. In 2017, the Nobel Prize in Physics was awarded to Rainer Weiss, Kip Thorne and Barry C. Barish "for decisive contributions to the LIGO detector and the observation of gravitational waves." "The Nobel Prize in Physics 2017". Nobel Foundation. https://www.nobelprize.org/nobel_prizes/physics/laureates/2017/press.html. As of March 2018, LIGO has made six detections of gravitational waves, of which the first five were colliding black-hole pairs. The sixth detected event, on August 17, 2017, was the first detection of a collision of two neutron stars, which simultaneously produced optical signals detectable by conventional telescopes.

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25 Oct 2022

Topic Review

Multiracial is defined as made up of or relating to people of many races. Many terms exist for people of various multiracial backgrounds. Preferred terms include multiracial, biracial, multiethnic, polyethnic, Métis, Creole, Coloured, Dougla, mestizo, Melungeon, quadroon, Chindian, zambo, Eurasian, hapa, hāfu, Garifuna and pardo. There are various other terms used that are sometimes considered insulting and offensive, such as "half," "half-and-half," mulatto, and "Biracial" Individuals of multiracial backgrounds make up a significant portion of the population in many parts of the world. In North America, studies have found that the multiracial population is continuing to grow. In many countries of Latin America and the Caribbean, people with multiracial backgrounds make up the majority of the population. Other countries where multiracial people make up a sizable portion of the population are Singapore, Malaysia, Hong Kong, South Africa , Botswana, Namibia, the United States , New Zealand, Mauritius, the Philippines , Fiji , Vietnam and Thailand.

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24 Nov 2022

Topic Review Peer Reviewed

The Principle of Action and Reaction According to Newton

The principle of action and reaction is generally considered the least problematic and interesting of Newton’s three laws of dynamics—least problematic because it seems self-evident, and least interesting because Newton’s mechanics of Principia essentially represents the dynamics of a mass point, while the principle of action and reaction is mainly important in the case of a set of bodies that interact with each other. However, reading Newton’s text is enough for the principle to appear equally problematic and interesting as the other two. This entry aims to justify this statement and to help clarify the meaning of the principle.

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13 Jun 2023

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