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Topic Review
Essential Oil Prevents COVID-19
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV‑2), also known as coronavirus disease-2019 (COVID-19), is a pandemic disease that has been declared as modern history’s gravest health emergency worldwide. Until now, no precise treatment modality has been developed. The angiotensin-converting enzyme 2 (ACE2) receptor, a host cell receptor, has been found to play a crucial role in virus cell entry; therefore, ACE2 blockers can be a potential target for anti-viral intervention. In this study, we evaluated the ACE2 inhibitory effects of 10 essential oils. Among them, geranium and lemon oils displayed significant ACE2 inhibitory effects in epithelial cells. In addition, immunoblotting and qPCR analysis also confirmed that geranium and lemon oils possess potent ACE2 inhibitory effects. Furthermore, the gas chromatography-mass spectrometry (GC–MS) analysis displayed 22 compounds in geranium oil and 9 compounds in lemon oil. Citronellol, geraniol, and neryl acetate were the major compounds of geranium oil and limonene that represented major compound of lemon oil. Next, we found that treatment with citronellol and limonene significantly downregulated ACE2 expression in epithelial cells. The results suggest that geranium and lemon essential oils and their derivative compounds are valuable natural anti-viral agents that may contribute to the prevention of the invasion of SARS-CoV-2/COVID-19 into the human body.
  • 7.5K
  • 13 Feb 2021
Topic Review
North–South Divide
The North–South divide is a socio-economic and political division of Earth popularized in the late 20th century and early 21st century. Generally, definitions of the Global North include the United States , Canada , almost all the European countries, Israel, Cyprus, Japan , Singapore, South Korea , Australia , and New Zealand. The Global South is made up of Sub-Saharan Africa, Latin America and the Caribbean, Pacific Islands, and the developing countries in Asia, including the Middle East. It is home to the BRIC countries (excluding Russia ): Brazil , India and China , which, along with Indonesia and Mexico, are the largest Southern states in terms of land area and population. The North is mostly correlated with the Western world and the First World, plus much of the Second World, while the South largely corresponds with the Third World and Eastern world. The two groups are often defined in terms of their differing levels of wealth, economic development, income inequality, democracy, and political and economic freedom, as defined by freedom indices. Nations in the North tend to be wealthier, less unequal and considered more democratic and to be developed countries who export technologically advanced manufactured products; Southern states are generally poorer developing countries with younger, more fragile democracies heavily dependent on primary sector exports and frequently share a history of past colonialism by Northern states. Nevertheless, the divide between the North and the South is often challenged and said to be increasingly incompatible with reality. In economic terms, as of the early 21st century, the North—with one quarter of the world population—controls four-fifths of the income earned anywhere in the world. 90% of the manufacturing industries are owned by and located in the North. Inversely, the South—with three quarters of the world population—has access to one-fifth of the world income. As nations become economically developed, they may become part of definitions the "North", regardless of geographical location; similarly, any nations that do not qualify for "developed" status are in effect deemed to be part of the "South".
  • 7.5K
  • 02 Dec 2022
Topic Review
Red Algae
Red algae, or Rhodophyta (/roʊˈdɒfɪtə/, /ˌroʊdəˈfaɪtə/; from grc ῥόδον (rhódon) 'rose', and φυτόν (phutón) 'plant'), are one of the oldest groups of eukaryotic algae. The Rhodophyta also comprises one of the largest phyla of algae, containing over 7,000 currently recognized species with taxonomic revisions ongoing. The majority of species (6,793) are found in the Florideophyceae (class), and mostly consist of multicellular, marine algae, including many notable seaweeds. Red algae are abundant in marine habitats but relatively rare in freshwaters. Approximately 5% of red algae species occur in freshwater, environments with greater concentrations found in warmer areas. Except for two coastal cave dwelling species in the asexual class Cyanidiophyceae, there are no terrestrial species, which may be due to an evolutionary bottleneck in which the last common ancestor lost about 25% of its core genes and much of its evolutionary plasticity. The red algae form a distinct group characterized by having eukaryotic cells without flagella and centrioles, chloroplasts that lack external endoplasmic reticulum and contain unstacked (stroma) thylakoids, and use phycobiliproteins as accessory pigments, which give them their red color. Red algae store sugars as floridean starch, which is a type of starch that consists of highly branched amylopectin without amylose, as food reserves outside their plastids. Most red algae are also multicellular, macroscopic, marine, and reproduce sexually. The red algal life history is typically an alternation of generations that may have three generations rather than two. The coralline algae, which secrete calcium carbonate and play a major role in building coral reefs, belong here. Red algae such as dulse (Palmaria palmata) and laver (nori/gim) are a traditional part of European and Asian cuisines and are used to make other products such as agar, carrageenans and other food additives.
  • 7.5K
  • 11 Nov 2022
Topic Review
Paper
Paper is a thin material produced by pressing together moist fibres of cellulose pulp derived from wood, rags or grasses, and drying them into flexible sheets. It is a versatile material with many uses, including writing, printing, packaging, cleaning, decorating, and a number of industrial and construction processes. Papers are essential in legal or non-legal documentation. The pulp papermaking process is said to have been developed in China during the early 2nd century CE, possibly as early as the year 105 CE, by the Han court eunuch Cai Lun, although the earliest archaeological fragments of paper derive from the 2nd century BCE in China. The modern pulp and paper industry is global, with China leading its production and the United States right behind it.
  • 7.4K
  • 30 Oct 2022
Topic Review
Humid Continental Climate
A humid continental climate is a climatic region defined by Russo-German climatologist Wladimir Köppen in 1900, typified by four distinct seasons and large seasonal temperature differences, with warm to hot (and often humid) summers and cold (sometimes severely cold in the northern areas) winters. Precipitation is usually distributed throughout the year. The definition of this climate regarding temperature is as follows: the mean temperature of the coldest month must be below −3 °C (26.6 °F) and there must be at least four months whose mean temperatures are at or above 10 °C (50 °F). In addition, the location in question must not be semi-arid or arid. The Dfb, Dwb and Dsb subtypes are also known as hemiboreal. Humid continental climates are generally found roughly between latitudes 40° N and 60° N, within the central and northeastern portions of North America, Europe, and Asia. They are much less commonly found in the Southern Hemisphere due to the larger ocean area at that latitude and the consequent greater maritime moderation. In the Northern Hemisphere some of the humid continental climates, typically in Hokkaido, Northern Honshu, Sakhalin island, Scandinavia, Nova Scotia, and Newfoundland are heavily maritime-influenced, with relatively cool summers and winters being just below the freezing mark. More extreme humid continental climates found in northeast China , southern Siberia, the Canadian Prairies, and the Great Lakes region of the American Midwest and Central Canada combine hotter summer maxima and colder winters than the marine-based variety.
  • 7.4K
  • 29 Sep 2022
Topic Review
Frog
A frog is any member of a diverse and largely carnivorous group of short-bodied, tailless amphibians composing the order Anura (ανοὐρά, literally without tail in Ancient Greek). The oldest fossil "proto-frog" Triadobatrachus is known from the Early Triassic of Madagascar , but molecular clock dating suggests their split from other amphibians may extend further back to the Permian, 265 million years ago. Frogs are widely distributed, ranging from the tropics to subarctic regions, but the greatest concentration of species diversity is in tropical rainforest. Frogs account for around 88% of extant amphibian species. They are also one of the five most diverse vertebrate orders. Warty frog species tend to be called toads, but the distinction between frogs and toads is informal, not from taxonomy or evolutionary history. An adult frog has a stout body, protruding eyes, anteriorly-attached tongue, limbs folded underneath, and no tail (the tail of tailed frogs is an extension of the male cloaca). Frogs have glandular skin, with secretions ranging from distasteful to toxic. Their skin varies in colour from well-camouflaged dappled brown, grey and green to vivid patterns of bright red or yellow and black to show toxicity and ward off predators. Adult frogs live in fresh water and on dry land; some species are adapted for living underground or in trees. Frogs typically lay their eggs in water. The eggs hatch into aquatic larvae called tadpoles that have tails and internal gills. They have highly specialized rasping mouth parts suitable for herbivorous, omnivorous or planktivorous diets. The life cycle is completed when they metamorphose into adults. A few species deposit eggs on land or bypass the tadpole stage. Adult frogs generally have a carnivorous diet consisting of small invertebrates, but omnivorous species exist and a few feed on plant matter. Frog skin has a rich microbiome which is important to their health. Frogs are extremely efficient at converting what they eat into body mass. They are an important food source for predators and part of the food web dynamics of many of the world's ecosystems. The skin is semi-permeable, making them susceptible to dehydration, so they either live in moist places or have special adaptations to deal with dry habitats. Frogs produce a wide range of vocalizations, particularly in their breeding season, and exhibit many different kinds of complex behaviors to attract mates, to fend off predators and to generally survive. Frogs are valued as food by humans and also have many cultural roles in literature, symbolism and religion. They are also seen as environmental bellwethers, with declines in frog populations often viewed as early warning signs of environmental damage. Frog populations have declined significantly since the 1950s. More than one third of species are considered to be threatened with extinction and over 120 are believed to have become extinct since the 1980s. The number of malformations among frogs is on the rise and an emerging fungal disease, chytridiomycosis, has spread around the world. Conservation biologists are working to understand the causes of these problems and to resolve them.
  • 7.4K
  • 19 Oct 2022
Topic Review
4.2 Kiloyear Event
The 4.2-kiloyear BP aridification event was one of the most severe climatic events of the Holocene epoch. It defines the beginning of the current Meghalayan age in the Holocene epoch. Starting around 2200 BC, it probably lasted the entire 22nd century BC. It has been hypothesised to have caused the collapse of the Old Kingdom in Egypt as well as the Akkadian Empire in Mesopotamia, and the Liangzhu culture in the lower Yangtze River area. The drought may also have initiated the collapse of the Indus Valley Civilisation, with some of its population moving southeastward to follow the movement of their desired habitat, as well as the migration of Indo-European-speaking people into India. Some scientists disagree with this conclusion and point out that the event was neither a global drought nor did it happen in a clear timeline.
  • 7.4K
  • 04 Nov 2022
Topic Review
Song of Ascents
Song of Ascents is a title given to fifteen of the Psalms, 120–134 (119–133 in the Septuagint and the Vulgate), each starting with the superscription Shir Hama'aloth (שיר המעלות šîr ha-ma‘ălōṯ, meaning "Song of the Ascents"), or, in the case of Psalm 121, Shir Lama'aloth (שיר למעלות šîr la-ma‘ălōṯ, "a song regarding ascents"). They are also variously called Gradual Psalms, Fifteen Psalms, Songs of Degrees, Songs of Steps, songs for going up to worship or Pilgrim Songs. Four of them (Psalms 122, 124, 131, and 133) are linked in their ascriptions to David, and one (127) to Solomon. Three of them (Psalms 131, 133, and 134) have only three verses. The longest is Psalm 132 (18 verses).
  • 7.4K
  • 23 Nov 2022
Topic Review
College Students Career Decision-Making Difficulties
College students suffer from various difficulties due to their own and environmental reasons in the process of career decision-making, which may affect their individual psychological state and social functions over time. One of the main difficulties is career decision-making. Career decision-making difficulties refer to various difficulties or problems faced by individuals in the process of career decision-making, including lack of readiness (LR), lack of information (LI), and inconsistent information (II). College students have certain career decision-making difficulties due to the lack of occupational information and self-information. The career decision-making difficulties not only affect college students’ employment, but also affect their solutions to the problems in career development.
  • 7.4K
  • 02 Jul 2021
Topic Review
Magnetic Potential
The term magnetic potential can be used for either of two quantities in classical electromagnetism: the magnetic vector potential, or simply vector potential, A; and the magnetic scalar potential ψ. Both quantities can be used in certain circumstances to calculate the magnetic field B. The more frequently used magnetic vector potential is defined so that its curl is equal to the magnetic field: [math]\displaystyle{ \nabla \times \mathbf{A}=\mathbf{B}\, }[/math]. Together with the electric potential φ, the magnetic vector potential can be used to specify the electric field E as well. Therefore, many equations of electromagnetism can be written either in terms of the fields E and B, or equivalently in terms of the potentials φ and A. In more advanced theories such as quantum mechanics, most equations use potentials rather than fields. The magnetic scalar potential ψ is sometimes used to specify the magnetic H-field in cases when there are no free currents, in a manner analogous to using the electric potential to determine the electric field in electrostatics. One important use of ψ is to determine the magnetic field due to permanent magnets when their magnetization is known. With some care the scalar potential can be extended to include free currents as well. Historically, Lord Kelvin first introduced vector potential in 1851, along with the formula relating it to the magnetic field.
  • 7.4K
  • 29 Sep 2022
Topic Review
Criticisms of Neoclassical Economics
Neo-classical economics has come under critique on the basis of its core ideologies, assumptions, and other matters.
  • 7.4K
  • 29 Nov 2022
Topic Review
HandWiki
HandWiki is an internet Wiki-style encyclopedia for professional researchers in various branches of science and computer science. As other Wiki type encyclopedias, HandWiki is designed for collaborative editing of articles. Unlike the traditional Wikipedia that uses the categories concept for all articles located in the main namespace, HandWiki uses dedicated namespaces for each topic. This allows creation of "Books" or "Manual" by grouping articles under the same namespace. According to the Handwiki designers, this can simplify organization of articles according to particular topic. HandWiki has the following topics included in the dedicated namespaces: Mathematics, Computers, Analysis, Physics, Astronomy, Biology, Chemistry, Unsolved. In addition to the categories preserved from Wikipedia, HandWiki has its own categories for original articles posted to HandWiki. One notable feature of HandWiki is that it allows to collaborate in real-time on many types of documents (lectures, books, technical documents, etc.) with multiple authors. The text can be protected from viewing, and can only be available for groups of people working on the same project. HandWiki can be used to convert such articles to LaTeX and to use BibTeX for referencing. These two features are a significant advantage for preparing research articles for publication. The HandWiki is designed using the MediaWiki software with additional extensions for inclusion of references to programming codes and BibTeX citations. Handwiki allows adding advertisements to the end of the articles. The advertising icons can be grouped according to the HandWiki topics.
  • 7.4K
  • 18 Oct 2022
Topic Review
Indigenous Aryans
Indigenous Aryans, also known as the Out of India theory (OIT), is the idea that the Aryans are indigenous to the Indian subcontinent, and that the Indo-European languages radiated out from a homeland in India into their present locations. Reflecting traditional Indian views based on the Puranic chronology, the indigenist view proposes an older date than is generally accepted for the Vedic period, and argues that the Indus Valley Civilization was a Vedic civilization. In this view, "the Indian civilization must be viewed as an unbroken tradition that goes back to the earliest period of the Sindhu-Sarasvati (or Indus) tradition (7000 or 8000 BCE)." It is presented as an alternative to the established migration model, which proposes the Pontic steppe as the area of origin of the Indo-European languages. The proposal is based on traditional and religious views on Indian history and identity, and plays a signifcant role in Hindutva politics. Support for this idea mostly exists among Indian scholars of Hindu religion and the history and archaeology of India, and has no support in mainstream scholarship.
  • 7.4K
  • 13 Oct 2022
Topic Review
Library Catalog
A library catalog or library catalogue is a register of all bibliographic items found in a library or group of libraries, such as a network of libraries at several locations. A bibliographic item can be any information entity (e.g., books, computer files, graphics, realia, cartographic materials, etc.) that is considered library material (e.g., a single novel in an anthology), or a group of library materials (e.g., a trilogy), or linked from the catalog (e.g., a webpage) as far as it is relevant to the catalog and to the users (patrons) of the library. The card catalog was a familiar sight to library users for generations, but it has been effectively replaced by the online public access catalog (OPAC). Some still refer to the online catalog as a "card catalog". Some libraries with OPAC access still have card catalogs on site, but these are now strictly a secondary resource and are seldom updated. Many libraries that retain their physical card catalog will post a sign advising the last year that the card catalog was updated. Some libraries have eliminated their card catalog in favour of the OPAC for the purpose of saving space for other use, such as additional shelving. The largest library catalog in the world is the WorldCat.org union catalog managed by the non-profit library cooperative OCLC, based in Dublin, Ohio. In January 2016, WorldCat.org had over 360,000,000 catalog records and over 2 billion library holdings.
  • 7.4K
  • 21 Oct 2022
Topic Review
Smart Cities
"Smart cities" are a new type of city where stakeholders are jointly responsible for urban management. City Information Management (CIM) is an output tool for smart city planning and management, which assists in achieving the sustainable development of urban infrastructure, and promotes smart cities to achieve the goals of stable global economic development, sustainable environmental development, and improvement of people’s quality of life. Existing research has so far established that blockchain and BIM have great potential to enhance construction project performance.
  • 7.4K
  • 14 Mar 2021
Topic Review
Pickup Artist
Pickup artists (PUA), self-identified as dating coaches, the seduction community or the pickup community, is a movement of men whose goal is seduction and sexual success with women. The community exists through Internet newsletters and blogs, marketing (e.g. banner ads, seminars, one-on-one coaching), forums and groups, as well as local clubs, known as "lairs". The rise of "seduction science", "game", or "studied charisma" has been attributed to modern forms of dating and social norms between sexes which have developed from a perceived increase in the equality of women in western society and changes to traditional gender roles. Commentators in the media have described "game" as sexist or misogynistic.
  • 7.4K
  • 10 Oct 2022
Topic Review
Vascular bundles
Vascular bundles play important roles in transporting nutrients, growth signals, amino acids, and proteins between aerial and underground tissues. 
  • 7.4K
  • 26 Feb 2021
Topic Review
Gemini Surfactants
Gemini surfactants are dimeric structures, composed of two hydrophobic chains and two hydrophilic heads, linked by a spacer at or near the head groups. They present lower CMC, better efficiency to form micelles, and solubilization capacity comparedto their conventional (monomeric) counterparts. They can also reduce the surface tension of water and the oil–water interfacial tension from 10 to 100 times. This behaviour depends mainly on the nature of their components (heads, hydrophobic chains and spacer); thus, their synthesis is focused mainly on varying the type and length of these components.
  • 7.4K
  • 21 Feb 2022
Topic Review
Libertarian Marxism
Libertarian Marxism is a broad scope of economic and political philosophies that emphasize the anti-authoritarian and libertarian aspects of Marxism. Early currents of libertarian Marxism such as left communism emerged in opposition to Marxism–Leninism. Libertarian Marxism is often critical of reformist positions such as those held by social democrats. Libertarian Marxist currents often draw from Karl Marx and Friedrich Engels' later works, specifically the Grundrisse and The Civil War in France; emphasizing the Marxist belief in the ability of the working class to forge its own destiny without the need for a vanguard party to mediate or aid its liberation. Along with anarchism, libertarian Marxism is one of the main currents of libertarian socialism. Libertarian Marxism includes currents such as autonomism, council communism, De Leonism, Lettrism, parts of the New Left, Situationism, Socialisme ou Barbarie and workerism. Libertarian Marxism has often had a strong influence on both post-left and social anarchists. Notable theorists of libertarian Marxism have included Maurice Brinton, Cornelius Castoriadis, Guy Debord, Raya Dunayevskaya, Daniel Guérin, C. L. R. James, Rosa Luxemburg, Antonio Negri, Anton Pannekoek, Fredy Perlman, Ernesto Screpanti, E. P. Thompson, Raoul Vaneigem and Yanis Varoufakis, who claims that Marx himself was a libertarian Marxist.
  • 7.4K
  • 11 Nov 2022
Topic Review
African Sheep Breeds
The African continent is home to more than 400 million heads of sheep, the majority of which are classified as indigenous and raised primarily for subsistence. They live and thrive well in a wide range of climatic and production conditions, ranging from unfavorable to favorable environments. 
  • 7.4K
  • 17 Sep 2021
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