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Topic Review
Customer Centricity
Firms are increasingly organized around the client. At the same time, there is customer pressure on green and sustainable organizations. This entry joint this two stand points in a sustainable view.
  • 10.7K
  • 03 Mar 2023
Topic Review
Applications of polydimethylsiloxane (PDMS) in Engineering
Polydimethylsiloxane (PDMS) is an elastomer with excellent optical, electrical and mechanical properties, which makes it well-suited for several engineering applications. Due to its biocompatibility, PDMS is widely used for biomedical purposes. Some properties can be improved by adding additives.
  • 10.7K
  • 12 Jan 2022
Topic Review
Chalk
Chalk is a soft, white, porous, sedimentary carbonate rock, a form of limestone composed of the mineral calcite. Calcite is an ionic salt called calcium carbonate or CaCO3. It forms under reasonably deep marine conditions from the gradual accumulation of minute calcite shells (coccoliths) shed from micro-organisms called coccolithophores. Flint (a type of chert) is very common as bands parallel to the bedding or as nodules embedded in chalk. It is probably derived from sponge spicules or other siliceous organisms as water is expelled upwards during compaction. Flint is often deposited around larger fossils such as Echinoidea which may be silicified (i.e. replaced molecule by molecule by flint). Chalk, as seen in Cretaceous deposits of Western Europe, is unusual among sedimentary limestones in the thickness of the beds. Most cliffs of chalk have very few obvious bedding planes unlike most thick sequences of limestone such as the Carboniferous Limestone or the Jurassic oolitic limestones. This may indicate very stable conditions over tens of millions of years. Chalk has greater resistance to weathering and slumping than the clays with which it is usually associated, thus forming tall, steep cliffs where chalk ridges meet the sea. Chalk hills, known as chalk downland, usually form where bands of chalk reach the surface at an angle, so forming a scarp slope. Because chalk is well jointed it can hold a large volume of ground water, providing a natural reservoir that releases water slowly through dry seasons.
  • 10.7K
  • 29 Nov 2022
Topic Review
Vitamin D Synthesis and Metabolism
Vitamin D, conventionally considered a nutrient, is a potent hormone regulating many physiological functions. Vitamin D exists as a prohormone that needs to be transformed into biologically active products that bind to their cognate nuclear receptors to regulate diverse physiological processes.
  • 10.7K
  • 13 Apr 2022
Topic Review
Digital Protective Relay
In utility and industrial electric power transmission and distribution systems, a digital protective relay is a computer-based system with software-based protection algorithms for the detection of electrical faults. Such relays are also termed as microprocessor type protective relays. They are functional replacements for electro-mechanical protective relays and may include many protection functions in one unit, as well as providing metering, communication, and self-test functions.
  • 10.7K
  • 09 Oct 2022
Topic Review
Antenna Gain
In electromagnetics, an antenna's power gain or simply gain is a key performance number which combines the antenna's directivity and electrical efficiency. In a transmitting antenna, the gain describes how well the antenna converts input power into radio waves headed in a specified direction. In a receiving antenna, the gain describes how well the antenna converts radio waves arriving from a specified direction into electrical power. When no direction is specified, gain is understood to refer to the peak value of the gain, the gain in the direction of the antenna's main lobe. A plot of the gain as a function of direction is called the gain pattern or radiation pattern. Antenna gain is usually defined as the ratio of the power produced by the antenna from a far-field source on the antenna's beam axis to the power produced by a hypothetical lossless isotropic antenna, which is equally sensitive to signals from all directions. Usually this ratio is expressed in decibels, and these units are referred to as decibels-isotropic (dBi). An alternative definition compares the received power to the power received by a lossless half-wave dipole antenna, in which case the units are written as dBd. Since a lossless dipole antenna has a gain of 2.15 dBi, the relation between these units is [math]\displaystyle{ \mathrm{Gain(dBd)} = \mathrm{Gain(dBi)} - 2.15 }[/math]. For a given frequency, the antenna's effective area is proportional to the power gain. An antenna's effective length is proportional to the square root of the antenna's gain for a particular frequency and radiation resistance. Due to reciprocity, the gain of any reciprocal antenna when receiving is equal to its gain when transmitting. Directive gain or directivity is a different measure which does not take an antenna's electrical efficiency into account. This term is sometimes more relevant in the case of a receiving antenna where one is concerned mainly with the ability of an antenna to receive signals from one direction while rejecting interfering signals coming from a different direction.
  • 10.7K
  • 10 Oct 2022
Topic Review
The Transition to Adulthood
The transition to adulthood is a process that brings childhood to an end and turns the individual into a young adult. This process is characterised by the acquisition of new roles for young people, roles linked to the development of personal autonomy that culminate in their emotional and functional independence.
  • 10.7K
  • 31 Aug 2021
Topic Review
Brilliant Blue FCF
Brilliant Blue FCF (Blue 1) is a synthetic organic compound used primarily as a blue colorant for processed foods, medications, dietary supplements, and cosmetics. It is classified as a triarylmethane dye and is known under various names, such as FD&C Blue No. 1 or Acid Blue 9. It is denoted by E number E133 and has a color index of 42090. It has the appearance of a blue powder and is soluble in water and glycerol, with a maximum absorption at about 628 nanometers. It is one of the oldest FDA-approved color additives and is generally considered nontoxic and safe.
  • 10.7K
  • 17 Nov 2022
Topic Review
Probability Sampling and Non Probability Sampling
There are two types of sampling methods namely: probability sampling and non-probability sampling. Each of these methods includes different types of techniques of sampling. Non-probability Sampling includes Quota sampling, Snowball sampling, Judgment sampling, and Convenience sampling, furthermore,  Probability Sampling includes Simple random, Stratified random, Cluster sampling, Systematic sampling and Multi stage sampling. 
  • 10.7K
  • 18 Feb 2022
Topic Review
Luffa Natural Fiber Composites
Natural fiber composites (NFCs) are an evolving area in polymer sciences. Fibers extracted from natural sources hold a wide set of advantages such as negligible cost, significant mechanical characteristics, low density, high strength-to-weight ratio, environmental friendliness, recyclability, etc. Luffa cylindrica, also termed luffa gourd or luffa sponge, is a natural fiber that has a solid potential to replace synthetic fibers in composite materials in diverse applications like vibration isolation, sound absorption, packaging, etc. Recently, many researches have involved luffa fibers as a reinforcement in the development of NFC, aiming to investigate their performance in selected matrices as well as the behavior of the end NFC.
  • 10.7K
  • 25 Sep 2020
Topic Review
Smart Textile Materials
In the last three decades, the development of new kinds of textiles, so-called smart and interactive textiles, has continued unabated. Smart textile materials and their applications are set to drastically boom as the demand for these textiles have been increasing with the emergence of new fibers, new fabrics, and innovative processing technologies. Moreover, people are eagerly demanding washable, flexible, lightweight, and robust e-textiles. These features depend on the properties of the starting material, the post-treatment, and the integration techniques. In this work, a comprehensive review has been conducted on the integration techniques of conductive materials in and onto a textile structure. The review showed that an e-textile can be developed by applying a conductive component on the surface of a textile substrate via plating, printing, coating, and other surface techniques, or by producing a textile substrate from metals and inherently conductive polymers via the creation of fibers and construction of yarns and fabrics with these. In addition, conductive filament fibers or yarns can be also integrated into conventional textile substrates during the fabrication like braiding, weaving, and knitting or as a post-fabrication of the textile fabric via embroidering. Additionally, layer-by-layer 3D printing of the entire smart textile components is possible, and the concept of 4D could play a significant role in advancing the status of smart textiles to a new level.
  • 10.7K
  • 29 Sep 2021
Topic Review
Barack Obama "Hope" Poster
The Barack Obama "Hope" poster is an image of US president Barack Obama designed by American artist Shepard Fairey. The image was widely described as iconic and came to represent Obama's 2008 presidential campaign. It is a stylized stencil portrait of Obama in solid red, beige and (light and dark) blue, with the word "progress", "hope", or "change" below (and other words in some versions). Fairey based the design on a photo taken by former Associated Press (AP) freelance photographer Mannie Garcia. He created the design in a day and printed it first as a street poster. It was then widely distributed—both as a digital image and other paraphernalia—during the 2008 election season, with approval from the Obama campaign. By July 2008, Sticker Robot had printed over 200,000 vinyl "Hope" stickers, 75% of which had been given away to support the cause. The image became one of the most widely recognized symbols of Obama's campaign, spawning many variations and imitations, including some commissioned by the Obama campaign. In January 2009, after Obama had won the election, Fairey's mixed-media stenciled portrait version of the image was acquired by the Smithsonian Institution for its National Portrait Gallery. Later that month, the photograph that Fairey based the poster on was identified and the AP began negotiations for compensation. Fairey sued for a declaratory judgment that his poster was a fair use of the photograph. The parties settled out of court in January 2011. In February 2012, Fairey pleaded guilty to destroying and fabricating evidence showing that he had used the photograph; in September, he was sentenced to two years of probation, 300 hours of community service, and a fine of $25,000.
  • 10.7K
  • 29 Sep 2022
Topic Review
Shenyang J-31
The Shenyang J-31 (or "FC-31 fifth Generation Multi-Purpose light Fighter") also known as the "Gyrfalcon" (鹘鹰), or "Falcon Hawk" by some military enthusiasts, is a twin-engine, mid-size fifth-generation jet fighter currently under development by Shenyang Aircraft Corporation. The fighter has also been referred to as the "F-60" or "J-21 Snowy Owl" (雪鸮) in some media reports. Its official name is Shenyang FC-31; J-xx nomenclatures in the Chinese military are reserved to programs launched and financed by the army, while this plane was developed by a state-owned company.
  • 10.7K
  • 10 Nov 2022
Topic Review
Travis (Chimpanzee)
Travis (October 21, 1995 – February 16, 2009) was a male common chimpanzee (Pan troglodytes) who, in February 2009, mauled his owner's friend in Stamford, Connecticut. He blinded her, severed several body parts and lacerated her face. He was shot dead by a police officer. As an animal actor, Travis had appeared in several television shows and commercials, including spots for Pepsi and Old Navy. He had also appeared on The Maury Povich Show, The Man Show, and a television pilot that featured Sheryl Crow and Michael Moore.
  • 10.7K
  • 07 Nov 2022
Topic Review
Year
A year is the orbital period of a planetary body, for example, the Earth, moving in its orbit around the Sun. Due to the Earth's axial tilt, the course of a year sees the passing of the seasons, marked by change in weather, the hours of daylight, and, consequently, vegetation and soil fertility. In temperate and subpolar regions around the planet, four seasons are generally recognized: spring, summer, autumn and winter. In tropical and subtropical regions, several geographical sectors do not present defined seasons; but in the seasonal tropics, the annual wet and dry seasons are recognized and tracked. A calendar year is an approximation of the number of days of the Earth's orbital period, as counted in a given calendar. The Gregorian calendar, or modern calendar, presents its calendar year to be either a common year of 365 days or a leap year of 366 days, as do the Julian calendars; see below. For the Gregorian calendar, the average length of the calendar year (the mean year) across the complete leap cycle of 400 years is 365.2425 days. The ISO standard ISO 80000-3, Annex C, supports the symbol a (for Latin annus) to represent a year of either 365 or 366 days. In English, the abbreviations y and yr are commonly used. In astronomy, the Julian year is a unit of time; it is defined as 365.25 days of exactly 86,400 seconds (SI base unit), totalling exactly 31,557,600 seconds in the Julian astronomical year. The word year is also used for periods loosely associated with, but not identical to, the calendar or astronomical year, such as the seasonal year, the fiscal year, the academic year, etc. Similarly, year can mean the orbital period of any planet; for example, a Martian year and a Venusian year are examples of the time a planet takes to transit one complete orbit. The term can also be used in reference to any long period or cycle, such as the Great Year.
  • 10.6K
  • 14 Oct 2022
Topic Review
Smart Water Grids
Smart water grids are urban water infrastructure enhanced through a variety of interconnected devices with the ability to collect and share data with both other devices and data centres. Typically this is done through the use of Internet of Things technology. Some of these devices also have the capacity to make decisions, in a centralised and/or decentralised manner, and to perform physical actions on the water infrastructure that lead to optimal operation and control. Smart water grids can, therefore, be understood as an instance of cyber-physical systems. In the case of water distribution management, in addition to classical objectives such as pressure, quality and leakage control; smart water grids also seek energy efficiency and explore water reuse systems.
  • 10.6K
  • 26 Feb 2021
Topic Review
SLC35B1 is AXER
To fulfil its role in protein biogenesis, the endoplasmic reticulum (ER) depends on the Hsp70 chaperone BiP that requires a constant ATP-supply. While the original biochemical approaches established hallmarks of the ATP transport into the ER, such as nucleotide selectivity, affinity, and antiport mode, the more recent live-cell imaging methods employing sensitive, localized molecular probes identified the low abundant ATP/ADP exchanger in the membrane of the human ER. Our screen of gene expression datasets for member(s) of the family of solute carriers that are co-expressed with BiP and are ER membrane proteins identified SLC35B1 as a potential candidate. Heterologous expression of SLC35B1 in E. coli revealed that SLC35B1 is highly specific for ATP and ADP and acts in antiport mode, two of four characteristics it shared with the ATP transport activity, which is present in rough ER membranes. Moreover, depletion of SLC35B1 from HeLa cells reduced ER ATP levels and, therefore, BiP activity, which implied that SLC35B1 mediates ATP uptake into the ER plus ADP release from the ER in vivo. Thus, human SLC35B1 provides ATP to the ER and was named ATP/ADP exchanger in the ER membrane or AXER. Furthermore, we characterized a regulatory circuit that is able to maintain the ATP supply in the ER ad hoc and was termed ER low energy response or lowER. Recent work by others confirmed the role and mode of action of AXER and also suggested a possible scenario for long term adjustments (termed CaATiER). Most recently, the structure of AXER was solved and allowed the deduction of its molecular mechanism. Thus, the dust has settled on the discovery of AXER.
  • 10.6K
  • 08 Sep 2025
Topic Review
Bias Temperature Instability of MOSFETs
CMOS technology dominates the semiconductor industry, and the reliability of MOSFETs is a key issue. Negative bias temperature instability (NBTI) and positive bias temperature instability (PBTI) mainly degrade the performance of pMOSFETs and nMOSFETs, respectively. 
  • 10.6K
  • 13 May 2022
Topic Review
Intergalactic Space
Outer space, or simply space, is the expanse that exists beyond the Earth and between celestial bodies. Outer space is not completely empty—it is a hard vacuum containing a low density of particles, predominantly a plasma of hydrogen and helium, as well as electromagnetic radiation, magnetic fields, neutrinos, dust, and cosmic rays. The baseline temperature of outer space, as set by the background radiation from the Big Bang, is 2.7 kelvins (−270.45 °C; −454.81 °F). The plasma between galaxies accounts for about half of the baryonic (ordinary) matter in the universe; it has a number density of less than one hydrogen atom per cubic metre and a temperature of millions of kelvins. Local concentrations of matter have condensed into stars and galaxies. Studies indicate that 90% of the mass in most galaxies is in an unknown form, called dark matter, which interacts with other matter through gravitational but not electromagnetic forces. Observations suggest that the majority of the mass-energy in the observable universe is dark energy, a type of vacuum energy that is poorly understood. Intergalactic space takes up most of the volume of the universe, but even galaxies and star systems consist almost entirely of empty space. Outer space does not begin at a definite altitude above the Earth's surface. However, the Kármán line, an altitude of 100 km (62 mi) above sea level, is conventionally used as the start of outer space in space treaties and for aerospace records keeping. The framework for international space law was established by the Outer Space Treaty, which entered into force on 10 October 1967. This treaty precludes any claims of national sovereignty and permits all states to freely explore outer space. Despite the drafting of UN resolutions for the peaceful uses of outer space, anti-satellite weapons have been tested in Earth orbit. Humans began the physical exploration of space during the 20th century with the advent of high-altitude balloon flights. This was followed by manned rocket flights and, then, manned Earth orbit, first achieved by Yuri Gagarin of the Soviet Union in 1961. Due to the high cost of getting into space, manned spaceflight has been limited to low Earth orbit and the Moon. On the other hand, unmanned spacecraft have reached all of the known planets in the Solar System. Outer space represents a challenging environment for human exploration because of the hazards of vacuum and radiation. Microgravity also has a negative effect on human physiology that causes both muscle atrophy and bone loss. In addition to these health and environmental issues, the economic cost of putting objects, including humans, into space is very high.
  • 10.6K
  • 23 Nov 2022
Topic Review
Social Structure
Social structure refers to the patterned arrangements of social relationships, institutions, and norms that shape and guide human behavior within a society. It encompasses both formal institutions, such as government and education, and informal norms, roles, and values that govern social interactions. Social structure provides a framework for understanding the organization and functioning of societies, influencing individuals' opportunities, behaviors, and relationships within social contexts.
  • 10.6K
  • 02 Feb 2024
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