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Topic Review
Institutional Entrepreneurship
Institutional entrepreneurship comprises the activities of agents who disrupt existing social institutions or create new ones, often to enable diffusion, especially of radical innovations, in a market. 
  • 6.0K
  • 25 Sep 2020
Topic Review
Procedures for Extraction of Anthocyanins from Different Food
Anthocyanins are water-soluble pigments characterized by various intense colors found in fruits and vegetables. The extraction and separation of anthocyanins from plants is important, especially due to the instability of plant anthocyanins, selecting and optimizing. Anthocyanins are prone to degradation by several factors, including pH, temperature, oxygen, water activity, co-pigments and enzymes. Unwanted compounds, such as sugars, proteins, lipids, acids and other flavonoids, can also be removed from plant material by appropriate extraction methods. The most used method for anthocyanin extraction is the conventional one, solid–liquid extraction, also known as solvent extraction, during which anthocyanins can be dissolved in polar solvents (methanol/glycolic acid and acetone), followed by their quantification, achieved by using spectrophotometry, the differential pH method, which is a rapid and convenient quantitative assay. Starting from this point, it has developed and there are many anthocyanin-extraction methods, such as conventional solvent extraction (CSE), enzyme-assisted extraction (EAE), fermentation extraction (FE), supercritical fluid extraction (SFE) (CO2) extraction, microwave-assisted extraction (MAE), ultrasonic-assisted extraction (UAE), high-hydrostatic-pressure extraction (HHPE) and pressurized-liquid extraction (PLE). One of the most frequent techniques for obtaining anthocyanins from plants is conventional solvent extraction. In order to meet the demands of safety and environmental sustainability, new extraction technologies with shorter extraction periods and higher yields have been developed (e.g., PLE, EFS, UAE, MAE, EAE, etc.).
  • 6.0K
  • 29 Nov 2022
Topic Review
Dosage Compensation
Dosage compensation is the process by which organisms equalize the expression of genes between members of different biological sexes. Across species, different sexes are often characterized by different types and numbers of sex chromosomes. In order to neutralize the large difference in gene dosage produced by differing numbers of sex chromosomes among the sexes, various evolutionary branches have acquired various methods to equalize gene expression among the sexes. Because sex chromosomes contain different numbers of genes, different species of organisms have developed different mechanisms to cope with this inequality. Replicating the actual gene is impossible; thus organisms instead equalize the expression from each gene. For example, in humans, females (XX) silence the transcription of one X chromosome of each pair, and transcribe all information from the other, expressed X chromosome. Thus, human females have the same number of expressed X-linked genes as do human males (XY), both sexes having essentially one X chromosome per cell, from which to transcribe and express genes. There are three main mechanisms of achieving dosage compensation which are widely documented in the literature and which are common to most species. These include random inactivation of one female X chromosome (as observed in Mus musculus; this is called X-inactivation), a two-fold increase in the transcription of a single male X chromosome (as observed in Drosophila melanogaster), and decreased transcription by half in both of the X chromosomes of a hermaphroditic organism (as observed in Caenorhabditis elegans). These mechanisms have been widely studied and manipulated in model organisms commonly used in the laboratory research setting. A summary of these forms of dosage compensation is illustrated below. However, there are also other less common forms of dosage compensation, which are not as widely researched and are sometimes specific to only one species (as observed in certain bird and monotreme species).
  • 6.0K
  • 31 Oct 2022
Topic Review
Permanent Magnet Linear Synchronous Motor
In high-end testing and manufacturing equipment, a trend exists whereby the traditional servo feed system with a ball screw and rotary motor will gradually be replaced by a direct drive system. The precision motion system driven by a permanent magnet linear synchronous motor (PMLSM) offers several advantages, including high speed, high acceleration, and high positioning accuracy. However, the operating precision of the feed device will be affected by the PMLSM robustness to nonlinear and uncertain disturbances, such as cogging force, friction, thermal effects, residual vibration, and load disturbance.
  • 6.0K
  • 29 Apr 2021
Topic Review
Lifestyle (Sociology)
Lifestyle is the interests, opinions, behaviours, and behavioural orientations of an individual, group, or culture. The term was introduced by Austrian psychologist Alfred Adler in his 1929 book, The Case of Miss R., with the meaning of "a person's basic character as established early in childhood". The broader sense of lifestyle as a "way or style of living" has been documented since 1961. Lifestyle is a combination of determining intangible or tangible factors. Tangible factors relate specifically to demographic variables, i.e. an individual's demographic profile, whereas intangible factors concern the psychological aspects of an individual such as personal values, preferences, and outlooks. A rural environment has different lifestyles compared to an urban metropolis. Location is important even within an urban scope. The nature of the neighborhood in which a person resides affects the set of lifestyles available to that person due to differences between various neighborhoods' degrees of affluence and proximity to natural and cultural environments. For example, in areas near the sea, a surf culture or lifestyle can often be present.
  • 6.0K
  • 13 Oct 2022
Topic Review
Emirate of Ras Al Khaimah
Ras Al Khaimah (RAK) (Arabic: رَأْس ٱلْخَيْمَة; IPA: [raʔs lˈxajma]), also spelled as Ras al Khaimah or Ras al-Khaimah, is one of the seven emirates that make up the United Arab Emirates (UAE). The city of Ras Al Khaimah, sometimes simply abbreviated to RAK City, is the capital of the emirate and home to most of the emirate's residents. It is linked to the medieval trading port of Julfar.[lower-alpha 1] Its name in English means "top of the tent". The emirate borders Oman's exclave of Musandam, and occupies part of the same peninsula. It covers an area of 2,486 km2 (960 sq mi) and has 64 km (40 mi) of beach coastline. As of 2015, the emirate had a population of about 345,000, of which about 31% were Emirati citizens. RAK city has two main areas - the Old Town and Nakheel - on either side of a creek that is home to mangroves and is framed by the North-Western Hajar Mountains. The emirate also consists of several villages and new gated residential developments, such as Al Hamra Village and Mina Al Arab. The emirate is served by Ras Al Khaimah International Airport. Its geography consists of a northern part (where Ras Al Khaimah City and most towns are situated) and a large southerly inland exclave (near the Dubai exclave of Hatta), and a few small islands in the Persian Gulf. Ras Al Khaimah has the most fertile soil in the country, due to a larger share of rainfall and underground water streams from the Hajar.
  • 6.0K
  • 10 Oct 2022
Topic Review
Reaction Mechanism of CO2 Methanation
The combustion of fossil fuels has led to a large amount of carbon dioxide emissions and increased greenhouse effect. Methanation of carbon dioxide can not only mitigate the greenhouse effect, but also utilize the hydrogen generated by renewable electricity such as wind, solar, tidal energy, and others, which could ameliorate the energy crisis to some extent. Highly efficient catalysts and processes are important to make CO2 methanation practical. Although noble metal catalysts exhibit higher catalytic activity and CH4 selectivity at low temperature, their large-scale industrial applications are limited by the high costs. Ni-based catalysts have attracted extensive attention due to their high activity, low cost, and abundance. At the same time, it is of great importance to study the mechanism of CO2 methanation on Ni-based catalysts in designing high-activity and stability catalysts.
  • 6.0K
  • 07 Mar 2022
Topic Review
Old Azeri Language
Old Azeri (Persian: آذری‌ باستان‎), also referred to as Azeri or Azari (Persian: آذری‎ Āḏarī [ɑːzæri]), is the extinct Iranian language that was once spoken in Azerbaijan (historic Azerbaijan, also known as Iranian Azerbaijan) before the Turkification of the Azeris. Some linguists believe the southern Tati varieties of Iranian Azerbaijan around Takestan such as the Harzandi and Karingani dialects to be remnants of Azeri. In addition, Old Azeri is known to have strong affinities with Talysh. Azeri was the dominant language in Azerbaijan before it was replaced by Azerbaijani, which is a Turkic language.
  • 6.0K
  • 30 Nov 2022
Topic Review
Surface Passivation
Passivation, in physical chemistry and engineering, refers to coating a material so it becomes "passive", that is, less readily affected or corroded by the environment. Passivation involves creation of an outer layer of shield material that is applied as a microcoating, created by chemical reaction with the base material, or allowed to build by spontaneous oxidation in the air. As a technique, passivation is the use of a light coat of a protective material, such as metal oxide, to create a shield against corrosion. Passivation of silicon is used during fabrication of microelectronic devices. In electrochemical treatment of water, passivation reduces the effectiveness of the treatment by increasing the circuit resistance, and active measures are typically used to overcome this effect, the most common being polarity reversal, which results in limited rejection of the fouling layer.[clarification needed] When exposed to air, many metals naturally form a hard, relatively inert surface layer, usually an oxide (termed the "native oxide layer") or a nitride, that serves as a passivation layer. In the case of silver, the dark tarnish is a passivation layer of silver sulfide formed from reaction with environmental hydrogen sulfide. (In contrast, metals such as iron oxidize readily to form a rough porous coating of rust that adheres loosely and sloughs off readily, allowing further oxidation.) The passivation layer of oxide markedly slows further oxidation and corrosion in room-temperature air for aluminium, beryllium, chromium, zinc, titanium, and silicon (a metalloid). The inert surface layer formed by reaction with air has a thickness of about 1.5 nm for silicon, 1–10 nm for beryllium, and 1 nm initially for titanium, growing to 25 nm after several years. Similarly, for aluminium, it grows to about 5 nm after several years. Surface passivation refers to a common semiconductor device fabrication process critical to modern electronics. It is the process by which a semiconductor surface such as silicon is rendered inert, and does not change semiconductor properties when it interacts with air or other materials. This is typically achieved by thermal oxidation, in which the material is heated and exposed to oxygen. In a silicon semiconductor, this process allows electricity to reliably penetrate to the conducting silicon below the surface, and to overcome the surface states that prevent electricity from reaching the semiconducting layer. Surface passivation by thermal oxidation is one of the key features of silicon technology, and is dominant in microelectronics. The surface passivation process was developed by Mohamed M. Atalla at Bell Labs in the late 1950s. It is commonly used to manufacture MOSFETs (metal-oxide-semiconductor field-effect transistors) and silicon integrated circuit chips (with the planar process), and is critical to the semiconductor industry. Surface passivation is also critical to solar cell and carbon quantum dot technologies.
  • 6.0K
  • 22 Nov 2022
Topic Review
Lipid Oxidation in Food Systems
Lipids are significant nutrients for humans and help many functional and regulatory activities in the human body, such as signal transduction, myelination, and synaptic plasticity. Lipids are also involved in the structural developments of the human body . In food, lipid content and fatty acid composition are the two critical congenital parameters to the susceptibility of food to oxidative changes. Lipid content and the fatty acid composition of fat of farm animals varies significantly depending on animal species and the diet. Lipid oxidation causes quality deterioration in food. Depending upon the reaction mechanisms and factors involved, lipid oxidation can be divided into autoxidation, photo-oxidation, and enzyme-catalyzed oxidation. Autoxidation is the most common process of lipid oxidation in foods and is divided into initiation, propagation, and termination stages. 
  • 6.0K
  • 01 Nov 2021
Topic Review
Chloramine
Chloramines are derivatives of ammonia by substitution of one, two or three hydrogen atoms with chlorine atoms: monochloramine (chloroamine, NH2Cl), dichloramine (NHCl2), and nitrogen trichloride (NCl3). The term chloramine also refers to a family of organic compounds with the formulas R2NCl and RNCl2 (where R is an organic group). Monochloramine (chloramine) is an inorganic compound with the formula NH2Cl. It is an unstable colorless liquid at its melting point of −66 °C (−87 °F), but it is usually handled as a dilute aqueous solution, in which form it is sometimes used as a disinfectant. Chloramine is too unstable to have its boiling point measured. It is listed as a tumorigen and mutagen. The wholesale cost in the developing world is about 13.80 to 18.41 U.S. dollars per 500 grams.
  • 6.0K
  • 16 Nov 2022
Topic Review
Temporal Envelope and Fine Structure
Temporal envelope (ENV) and temporal fine structure (TFS) are changes in the amplitude and frequency of sound perceived by humans over time. These temporal changes are responsible for several aspects of auditory perception, including loudness, pitch and timbre perception and spatial hearing. Complex sounds such as speech or music are decomposed by the peripheral auditory system of humans into narrow frequency bands. The resulting narrow-band signals convey information at different time scales ranging from less than one millisecond to hundreds of milliseconds. A dichotomy between slow "temporal envelope" cues and faster "temporal fine structure" cues has been proposed to study several aspects of auditory perception (e.g., loudness, pitch and timbre perception, auditory scene analysis, sound localization) at two distinct time scales in each frequency band. Over the last decades, a wealth of psychophysical, electrophysiological and computational studies based on this envelope/fine-structure dichotomy have examined the role of these temporal cues in sound identification and communication, how these temporal cues are processed by the peripheral and central auditory system, and the effects of aging and cochlear damage on temporal auditory processing. Although the envelope/fine-structure dichotomy has been debated and questions remain as to how temporal fine structure cues are actually encoded in the auditory system, these studies have led to a range of applications in various fields including speech and audio processing, clinical audiology and rehabilitation of sensorineural hearing loss via hearing aids or cochlear implants.
  • 6.0K
  • 12 Oct 2022
Topic Review
Nanodiamonds Synthesis Techniques
The "state-of-the-art" of the nanodiamonds synthesis techniques is reviewed with emphasis on the more recent one involving pulsed laser ablation. Production of NV centers inside the nanodiamonds and  post-production cleaning processes to remove residual graphite layers are also described.
  • 6.0K
  • 27 Oct 2020
Topic Review
Connectivity Architecture
Connectivity architecture connects main functional blocks or entities of a system with well-defined interfaces enabling interoperability, fluent data flows and information sharing in timely manner. Local connectivity architecture defines e.g. the architecture inside an autonomous ship. The wider-scale architecture includes geographically distributed entities such as vessels, databases, and remote operations centers.
  • 6.0K
  • 17 Aug 2020
Topic Review
Amygdala
The amygdala is one of the areas in the brain involved in the development of PTSD as the starting point for the process of activation of the hypothalamo–pituitary axis and the cascade of physiological responses to acute stress. An appropriate response to acute stress is a vital adaptive mechanism, but its prolongation causes various biopsychosocial (previously, psychosomatic) disorders. Chronic stress leads to higher expression of CRH/CRF in the CE and BLA, which has an anxiogenic effect.
  • 6.0K
  • 13 Jul 2021
Topic Review
Convergent Evolution
Convergent evolution is the independent evolution of similar features in species of different periods or epochs in time. Convergent evolution creates analogous structures that have similar form or function but were not present in the last common ancestor of those groups. The cladistic term for the same phenomenon is homoplasy. The recurrent evolution of flight is a classic example, as flying insects, birds, pterosaurs, and bats have independently evolved the useful capacity of flight. Functionally similar features that have arisen through convergent evolution are analogous, whereas homologous structures or traits have a common origin but can have dissimilar functions. Bird, bat, and pterosaur wings are analogous structures, but their forelimbs are homologous, sharing an ancestral state despite serving different functions. The opposite of convergence is divergent evolution, where related species evolve different traits. Convergent evolution is similar to parallel evolution, which occurs when two independent species evolve in the same direction and thus independently acquire similar characteristics; for instance, gliding frogs have evolved in parallel from multiple types of tree frog. Many instances of convergent evolution are known in plants, including the repeated development of C4 photosynthesis, seed dispersal by fleshy fruits adapted to be eaten by animals, and carnivory.
  • 6.0K
  • 24 Oct 2022
Topic Review
Poly(N-isopropylacrylamide)-Based Hydrogels
Poly(N-isopropylacrylamide) (PNIPAM) is a widely utilized negative thermosensitive polymer (as it has increased solubility with lowering of temperature, causing volume phase transition by forming hydrogen bonds) that has currently sparkled a lot of scientific inquisitiveness. Smart hydrogels based on PNIPAM demonstrate distinct thermoresponsive features close to a lower critical solution temperature (LCST) that enhance their capability in various biomedical applications such as drug delivery, tissue engineering, and wound dressings.
  • 6.0K
  • 29 Jul 2022
Topic Review
Electric Vehicle Charger Cybersecurity Vulnerabilities
Worldwide growth in electric vehicle use is prompting new installations of private and public electric vehicle supply equipment (EVSE). EVSE devices support the electrification of the transportation industry but also represent a linchpin for power systems and transportation infrastructures. Cybersecurity researchers have identified several vulnerabilities that exist in EVSE devices, communications to electric vehicles (EVs), and upstream services, such as EVSE vendor cloud services, third-party systems, and grid operators. 
  • 6.0K
  • 02 Jun 2022
Topic Review
ATtiny Microcontroller Comparison Chart
ATtiny (also known as TinyAVR) are a subfamily of the popular 8-bit AVR microcontrollers, which typically has fewer features, fewer I/O pins, and less memory than other AVR series chips. The first members of this family were released in 1999 by Atmel (later acquired by Microchip Technology in 2016).
  • 6.0K
  • 03 Nov 2022
Topic Review
Compartmental Models in Epidemiology
Compartmental models are a very general modelling technique. They are often applied to the mathematical modelling of infectious diseases. The population is assigned to compartments with labels – for example, S, I, or R, (Susceptible, Infectious, or Recovered). People may progress between compartments. The order of the labels usually shows the flow patterns between the compartments; for example SEIS means susceptible, exposed, infectious, then susceptible again. The origin of such models is the early 20th century, with important works being that of Ross in 1916, Ross and Hudson in 1917, Kermack and McKendrick in 1927 and Kendall in 1956 The models are most often run with ordinary differential equations (which are deterministic), but can also be used with a stochastic (random) framework, which is more realistic but much more complicated to analyze. Models try to predict things such as how a disease spreads, or the total number infected, or the duration of an epidemic, and to estimate various epidemiological parameters such as the reproductive number. Such models can show how different public health interventions may affect the outcome of the epidemic, e.g., what the most efficient technique is for issuing a limited number of vaccines in a given population.
  • 6.0K
  • 02 Dec 2022
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