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Topic Review
History of Solar System Formation and Evolution Hypotheses
The history of scientific thought about the Formation and evolution of the Solar System begins with the Copernican Revolution. The first recorded use of the term "Solar System" dates from 1704.
  • 7.4K
  • 22 Nov 2022
Topic Review
Homology
In biology, homology is similarity due to shared ancestry between a pair of structures or genes in different taxa. A common example of homologous structures is the forelimbs of vertebrates, where the wings of bats and birds, the arms of primates, the front flippers of whales and the forelegs of four-legged vertebrates like dogs and crocodiles are all derived from the same ancestral tetrapod structure. Evolutionary biology explains homologous structures adapted to different purposes as the result of descent with modification from a common ancestor. The term was first applied to biology in a non-evolutionary context by the anatomist Richard Owen in 1843. Homology was later explained by Charles Darwin's theory of evolution in 1859, but had been observed before this, from Aristotle onwards, and it was explicitly analysed by Pierre Belon in 1555. In developmental biology, organs that developed in the embryo in the same manner and from similar origins, such as from matching primordia in successive segments of the same animal, are serially homologous. Examples include the legs of a centipede, the maxillary palp and labial palp of an insect, and the spinous processes of successive vertebrae in a vertebral column. Male and female reproductive organs are homologous if they develop from the same embryonic tissue, as do the ovaries and testicles of mammals including humans. Sequence homology between protein or DNA sequences is similarly defined in terms of shared ancestry. Two segments of DNA can have shared ancestry because of either a speciation event (orthologs) or a duplication event (paralogs). Homology among proteins or DNA is inferred from their sequence similarity. Significant similarity is strong evidence that two sequences are related by divergent evolution from a common ancestor. Alignments of multiple sequences are used to discover the homologous regions. Homology remains controversial in animal behaviour, but there is suggestive evidence that, for example, dominance hierarchies are homologous across the primates.
  • 7.4K
  • 10 Oct 2022
Topic Review
2D-MoS2
Two-dimensional (2D) materials are generally defined as crystalline substances with a few atoms thickness.Two-dimensional transition metal dichalcogenide (2D-TMDs) semiconducting (SC) materials have exhibited unique optical and electrical properties. The layered configuration of the 2D-TMDs materials is at the origin of their strong interaction with light and the relatively high mobility of their charge carriers, which in turn prompted their use in many optoelectronic applications, such as ultra-thin field-effect transistors, photo-detectors, light emitting diode, and solar-cells. Generally, 2D-TMDs form a family of graphite-like layered thin semiconducting structures with the chemical formula of MX2, where M refers to a transition metal atom (Mo, W, etc.) and X is a chalcogen atom (Se, S, etc.). The layered nature of this class of 2D materials induces a strong anisotropy in their electrical, chemical, mechanical, and thermal properties. In particular, molybdenum disulfide (MoS2) is the most studied layered 2D-TMD.
  • 7.4K
  • 28 Sep 2021
Topic Review
Artemisia vulgaris L. (common mugwort)
Artemisia vulgaris L. (common mugwort) is a species with great importance in the history of medicine and was called the “mother of herbs” in the Middle Ages. It is a common herbaceous plant that exhibits high morphological and phytochemical variability depending on the location it occurs. This species is well known almost all over the world. Its herb—Artemisiae vulgaris herba—is used as a raw material due to the presence of volatile oil, flavonoids, and sesquiterpene lactones and their associated biological activities. The European Pharmacopoeia has listed this species as a potential homeopathic raw material. Moreover, this species has been used in traditional Chinese, Hindu, and European medicine to regulate the functioning of the gastrointestinal system and treat various gynecological diseases. The general aim of this review was to analyze the progress of phytochemical and pharmacological as well as professional scientific studies focusing on A. vulgaris. Thus far, numerous authors have confirmed the beneficial properties of A. vulgaris herb extracts, including their antioxidant, hepatoprotective, antispasmolytic, antinociceptive, estrogenic, cytotoxic, antibacterial, and antifungal effects. In addition, several works have reviewed the use of this species in the production of cosmetics and its role as a valuable spice in the food industry. 
  • 7.4K
  • 05 Nov 2020
Topic Review
Urban Sociology
Urban sociology is the sociological study of life and human interaction in metropolitan areas. It is a normative discipline of sociology seeking to study the structures, environmental processes, changes and problems of an urban area and by doing so provide inputs for urban planning and policy making. In other words, it is the sociological study of cities and their role in the development of society. Like most areas of sociology, urban sociologists use statistical analysis, observation, social theory, interviews, and other methods to study a range of topics, including migration and demographic trends, economics, poverty, race relations and economic trends. Urban sociology is one of the oldest sub-disciplines of sociology dating back to the mid-nineteenth century. The philosophical foundations of modern urban sociology originate from the work of sociologists such as Karl Marx, Ferdinand Tönnies, Émile Durkheim, Max Weber and Georg Simmel who studied and theorized the economic, social and cultural processes of urbanization and its effects on social alienation, class formation, and the production or destruction of collective and individual identities. These theoretical foundations were further expanded upon and analyzed by a group of sociologists and researchers who worked at the University of Chicago in the early twentieth century. In what became known as the Chicago School of sociology the work of Robert Park, Louis Wirth and Ernest Burgess on the inner city of Chicago revolutionized not only the purpose of urban research in sociology, but also the development of human geography through its use of quantitative and ethnographic research methods. The importance of the theories developed by the Chicago School within urban sociology have been critically sustained and critiqued but still remain one of the most significant historical advancements in understanding urbanization and the city within the social sciences. The discipline may draw from several fields, including cultural sociology, economic sociology, and political sociology.
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  • 01 Nov 2022
Topic Review
Polyethylene Glycol
Lately, polyethylene glycol with nanoparticles has been demarcated as an innovative class of phase change materials with conceivable uses in the area of convective heat transfer. The amplified thermal conductivity of these nanoparticle enhanced phase change materials (PCMs) over the basic fluids (e.g., polyethylene glycol—PEG) is considered one of the driving factors for their improved performance in heat transfer.
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  • 08 Jan 2021
Topic Review
Mesoamerican Genetic Studies
Mesoamerica is a historically and culturally defined geographic area comprising current central and south Mexico, Belize, Guatemala, El Salvador, and border regions of Honduras, western Nicaragua, and northwestern Costa Rica. The permanent settling of Mesoamerica was accompanied by the development of agriculture and pottery manufacturing (2500 BCE–150 CE), which led to the rise of several cultures connected by commerce and farming. Hence, Mesoamericans probably carried an invaluable genetic diversity partly lost during the Spanish conquest and the subsequent colonial period. Mesoamerican ancient DNA (aDNA) research has mainly focused on the study of mitochondrial DNA in the Basin of Mexico and the Yucatán Peninsula and its nearby territories, particularly during the Postclassic period (900–1519 CE). 
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  • 24 Nov 2020
Topic Review
Proofs Involving the Moore–Penrose Inverse
In linear algebra, the Moore–Penrose inverse is a matrix that satisfies some but not necessarily all of the properties of an inverse matrix. This article collects together a variety of proofs involving the Moore–Penrose inverse.
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  • 01 Dec 2022
Topic Review
Pathophysiology of Sepsis
Sepsis is a life-threatening condition characterized by an uncontrolled inflammatory response to an infectious agent and its antigens. Immune cell activation against the antigens causes severe distress that mediates a strong inflammatory response in vital organs. Sepsis is responsible for a high rate of morbidity and mortality in immunosuppressed patients. 
  • 7.4K
  • 13 Mar 2023
Topic Review
(ε, δ)-Definition of Limit
In calculus, the (ε, δ)-definition of limit ("epsilon–delta definition of limit") is a formalization of the notion of limit. The concept is due to Augustin-Louis Cauchy, who never gave a formal (ε, δ) definition of limit in his Cours d'Analyse, but occasionally used ε, δ arguments in proofs. It was first given as a formal definition by Bernard Bolzano in 1817, and the definitive modern statement was ultimately provided by Karl Weierstrass. It provides rigor to the following informal notion: the dependent expression f(x) approaches the value L as the variable x approaches the value c if f(x) can be made as close as desired to L by taking x sufficiently close to c.
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  • 22 Nov 2022
Topic Review
Biblical Cosmology
Biblical cosmology is the biblical writers' conception of the cosmos as an organised, structured entity, including its origin, order, meaning and destiny. The Bible was formed over many centuries, involving many authors, and reflects shifting patterns of religious belief; consequently, its cosmology is not always consistent. Nor do the biblical texts necessarily represent the beliefs of all Jews or Christians at the time they were put into writing: the majority of those making up Hebrew Bible or Old Testament in particular represent the beliefs of only a small segment of the ancient Israelite community, the members of a late Judean religious tradition centered in Jerusalem and devoted to the exclusive worship of Yahweh. The ancient Israelites envisaged a universe made up of a flat disc-shaped Earth floating on water, heaven above, underworld below. Humans inhabited Earth during life and the underworld after death; there was no way that mortals could enter heaven, and the underworld was morally neutral; only in Hellenistic times (after c. 330 BCE) did Jews begin to adopt the Greek idea that it would be a place of punishment for misdeeds, and that the righteous would enjoy an afterlife in heaven. In this period too the older three-level cosmology in large measure gave way to the Greek concept of a spherical earth suspended in space at the center of a number of concentric heavens. The opening words of the Genesis creation narrative (Genesis 1:1–26) sum up the biblical editors' view of how the cosmos originated: "In the beginning God created the heavens and the earth"; Yahweh, the God of Israel, was solely responsible for creation and had no rivals, implying Israel's superiority over all other nations. Later Jewish thinkers, adopting ideas from Greek philosophy, concluded that God's Wisdom, Word and Spirit penetrated all things and gave them unity. Christianity in turn adopted these ideas and identified Jesus with the Logos (Word): "In the beginning was the Word, and the Word was with God, and the Word was God" (John 1).
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  • 11 Jan 2024
Topic Review
Bio-Composites
Bio-composites are degradable, renewable, non-abrasive, and non-toxic, with comparable properties to those of synthetic fiber composites and used in many applications in various fields. Naturals fibers are abundant and have low harvesting costs with adequate mechanical properties. Hazards of synthetic fibers, recycling issues, and toxic byproducts are the main driving factors in the research and development of bio-composites. Bio-composites are fabricated by combining natural fibers in a matrix material. The matrix material can be biodegradable, non-biodegradable, or synthetic. Synthetic matrix materials, along with natural fibers, are used to form hybrid bio-composites.
  • 7.4K
  • 09 Mar 2021
Topic Review
Metal Oxide Applications
Metal oxides play a key role in environmental remediation.
  • 7.4K
  • 08 Dec 2020
Topic Review
May 20: Vasco da Gama Reaches India
Vasco da Gama’s arrival in Calicut, India on May 20, 1498, marked the first time a European reached India by sea, successfully navigating around the Cape of Good Hope and across the Indian Ocean. This event opened a direct maritime trade route between Europe and Asia, breaking the centuries-old overland monopoly held by Middle Eastern and Venetian traders. It initiated an era of European exploration, imperial expansion, and global maritime dominance, especially for Portugal.
  • 7.4K
  • 20 May 2025
Topic Review
Infrared Heating Applications in Food Processing
Infrared (IR) technology is highly energy-efficient, less water-consuming, and environmentally friendly compared to conventional heating. Further, it is also characterized by homogeneity of heating, high heat transfer rate, low heating time, low energy consumption, improved product quality, and food safety. Infrared technology is used in many food manufacturing processes, such as drying, boiling, heating, peeling, polyphenol recovery, freeze-drying, antioxidant recovery, microbiological inhibition, sterilization grains, bread, roasting of food, manufacture of juices, and cooking food. 
  • 7.4K
  • 17 Dec 2021
Topic Review
Socioeconomic and Environmental Impacts of High-Speed Rail
Countries considering high-speed rail (HSR) developments face enormous challenges because of their high deployment cost, environmental obstacles, political opposition, and their potentially adverse effects on society. Nevertheless, HSR services are importantly sustainable that can have positive and transformative effects on the economic growth of a nation. 
  • 7.4K
  • 22 Nov 2021
Topic Review
Solubility of Oxygen and Hydrogen in Water
Produced by photosynthesis, oxygen (O2) is a fundamentally important gas in biological systems, playing roles as a terminal electron receptor in respiration and in host defence through the creation of reactive oxygen species (ROS). Hydrogen (H2) plays a role in metabolism for some organisms, such as at thermal vents and in the gut environment, but has a role in controlling growth and development, and in disease states, both in plants and animals.
  • 7.4K
  • 28 Feb 2024
Topic Review
Plasma Treatment for Seed Germination and Plant Growth
Low-temperature atmospheric pressure plasma has been used in various fields such as plasma medicine, agriculture, food safety and storage, and food manufacturing. In the field of plasma agriculture, plasma treatment improves seed germination, plant growth, and resistance to abiotic and biotic stresses, allows pesticide removal, and enhances biomass and yield.
  • 7.4K
  • 27 May 2022
Biography
Fritz Haber
Fritz Haber (9 December 1868 – 29 January 1934) was a German[1] chemist who received the Nobel Prize in Chemistry in 1918 for his invention of the Haber–Bosch process, a method used in industry to synthesize ammonia from nitrogen gas and hydrogen gas. This invention is of importance for the large-scale synthesis of fertilizers and explosives. The food production for half the world's current
  • 7.4K
  • 28 Nov 2022
Topic Review
Criticism of Facebook
Facebook (and parent company Meta Platforms) has been the subject of criticism and legal action. Criticisms include the outsize influence Facebook has on the lives and health of its users and employees, as well as Facebook's influence on the way media, specifically news, is reported and distributed. Notable issues include Internet privacy, such as use of a widespread "like" button on third-party websites tracking users, possible indefinite records of user information, automatic facial recognition software, and its role in the workplace, including employer-employee account disclosure. The use of Facebook can have negative psychological effects that include feelings of sexual jealousy, and stress, a lack of attention, and social media addiction that in some cases is comparable to drug addiction. Facebook's operations have also received coverage. The company's electricity usage, tax avoidance, real-name user requirement policies, censorship policies, handling of user data, and its involvement in the United States PRISM surveillance program have been highlighted by the media and by critics. Facebook has come under scrutiny for 'ignoring' or shirking its responsibility for the content posted on its platform, including copyright and intellectual property infringement, hate speech, incitement of rape, violence against minorities, terrorism, fake news, Facebook murder, crimes, and violent incidents live-streamed through its Facebook Live functionality. The company and its employees have also been subject to litigation cases over the years, with its most prominent case concerning allegations that CEO Mark Zuckerberg broke an oral contract with Cameron Winklevoss, Tyler Winklevoss, and Divya Narendra to build the then-named "HarvardConnection" social network in 2004, instead allegedly opting to steal the idea and code to launch Facebook months before HarvardConnection began. The original lawsuit was eventually settled in 2009, with Facebook paying approximately $20 million in cash and 1.25 million shares. A new lawsuit in 2011 was dismissed. Some critics point to problems which they say will result in the demise of Facebook. Facebook has been banned by several governments for various reasons, including Syria, China, Iran and Russia.
  • 7.4K
  • 14 Oct 2022
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