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Topic Review

Vinylidene Fluoride

1,1-difluoroethylene (VDF) is one of the major fluoromonomers, which are the feedstock for the production of various resins, rubbers membrane and paints. The polymers derived from VDF (PVDF) or co-polymers with unique chemical resistance, stability at elevated temperatures, oxidation resistance, weatherability, piezoelectricity, dielectric and thermoelectricity, find wide applications in areas including petrochemical, electronic and electrical, and fluorocarbon coating. VDF is the second largest product among fluorocarbons with an annual production capacity of above 53,000 tons. The demand for VDF is increasing rapidly. At present, in industry, VDF is usually produced via the dehydrochlorination of 1,1-difluoro-1-chloroethane (HCFC-142b) at reaction temperatures above 650 °C

3.5K
30 Oct 2020

Topic Review

Biological Degradation of Polymers

Biodegradable plastics can make an important contribution to the struggle against increasing environmental pollution through plastics. This entry provides an overview of the main environmental conditions in which biodegradation takes place and then presents the degradability of numerous polymers.

3.5K
23 Nov 2020

Topic Review

Climate Change Maladaptation

Maladaptation is caused by adaptation that fails to reduce vulnerability or inadvertently increases it. Maladaptation can be defined as: ''maladaptation occurs when short-term strategies increase vulnerability in the long term'' or ''action taken ostensibly to avoid or reduce vulnerability to climate change that impacts adversely on, or increase the vulnerability of other systems, sectors, or social groups.''

3.5K
29 Mar 2021

Topic Review

Comet Lake is Intel's codename for its 10th generation Core microprocessors. They are manufactured using Intel's third 14 nm Skylake process refinement, succeeding the Whiskey Lake U-series mobile processor and Coffee Lake desktop processor families. Intel announced low-power mobile Comet Lake-U CPUs on August 21, 2019, H-series mobile CPUs on April 2, 2020, desktop Comet Lake-S CPUs April 30, 2020, and Xeon W-1200 series workstation CPUs on May 13, 2020. Comet Lake processors and Ice Lake 10 nm processors are together branded as the Intel "10th Generation Core" family. Intel officially launched Comet Lake-Refresh CPUs on the same day as 11th Gen Core Rocket Lake launch. The low-power mobile Comet Lake-U Core and Celeron 5205U CPUs were discontinued on July 7, 2021.

3.5K
21 Nov 2022

Topic Review

Ibrexafungerp is a first-in-class IV/oral triterpenoid antifungal agent. Similar in mechanism of action to echinocandins, ibrexafungerp inhibits (1→3)-β-D-glucan synthase, a key component of the fungal cell wall, resulting in fungicidal activity against Candida spp. Ibrexafungerp demonstrates broad in vitro activity against Candida spp.,Aspergillus spp., dimorphic fungi Pneumocystis and other emerging yeasts and mold pathogens including azole and echinocandin-resistant isolates. It is currently in late clinical development for treatment and prevention of vulvovaginal candidiasis. Other ongoing trials include treatment of serious fungal infections, including, invasive candidiasis, Candida auris infections, invasive aspergillosis and refractory fungal disease in patients not responding to or who are intolerant to standard of care .

3.5K
17 Mar 2021

Topic Review Peer Reviewed

COVID-19 and Psychological Impact

The worldwide mental health burden associated to COVID-19. The psychological symptoms associated to COVID-19 can originate from three different sources: lockdowns, pandemic life and virus infection (both COVID-19 and post COVID-19 condition). Within the psychological symptoms it can be found: anxiety, depression, post-traumatic stress, fatigue and cognitive impairment (i.e., ’brain fog’, mental slowness, deficits in attention, executive functioning, working memory, learning, articulation, and/or psychomotor coordination). Plus, two psychological conditions associated to the COVID-19 pandemic have been coined so far by the World Health Organization: pandemic fatigue and post COVID-19 condition. The increase of psychological symptoms both in the general population and in frontline workers (especially health-care workers) generates an unprecedented number of psychological patients and it challenges national mental health systems.

3.5K
13 Apr 2022

Topic Review

Wetlands are a critical part of natural environments that offer a wide range of ecosystem services. In urban areas, wetlands contribute to the livability of cities through improving the water quality, carbon sequestration, providing habitats for wildlife species, reducing the effects of urban heat islands, and creating recreation opportunities.

3.5K
13 Jan 2022

Topic Review

Additive Manufacturing and Industry 4.0

We present a review on Additive Manufacturing and Industry 4.0 from business innovation and sustainability perspective.

3.5K
14 Apr 2021

Topic Review

Biosurfactants can play a significant role in the prevention, control and treatment of diseases caused by a range of pathogenic agents through various therapeutic, pharmaceutical, environmental and hygiene approaches.

3.5K
28 Jan 2021

Topic Review

Research in instability has focused on the analysis of muscle activation. This systematic entry was to analyze the effects of unstable devices on speed, strength and muscle power measurements administered in the form of controlled trials to healthy individuals in adulthood.

3.5K
27 Jan 2022

Topic Review

Operating Principles of Fiber Bragg Grating Sensors

Fiber Bragg gratings (FBG) sensors are increasingly commercially available and are, one of the most popular sensors from the fiber optic sensing family, having found use in a variety of industrial and research applications. A conventional FBG sensor is made up of a specially fabricated small and flexible segment imprinted into the core of a single-mode optical fiber.

3.5K
14 Dec 2022

Topic Review

The CNO cycle (for carbon–nitrogen–oxygen; sometimes called Bethe–Weizsäcker cycle after Hans Albrecht Bethe and Carl Friedrich von Weizsäcker) is one of the two known sets of fusion reactions by which stars convert hydrogen to helium, the other being the proton–proton chain reaction (p-p cycle), which is more efficient at the Sun's core temperature. The CNO cycle is hypothesized to be dominant in stars that are more than 1.3 times as massive as the Sun. Unlike the proton-proton reaction, which consumes all its constituents, the CNO cycle is a catalytic cycle. In the CNO cycle, four protons fuse, using carbon, nitrogen, and oxygen isotopes as catalysts, each of which is consumed at one step of the CNO cycle, but re-generated in a later step. The end product is one alpha particle (a stable helium nucleus), two positrons, and two electron neutrinos. There are various alternative paths and catalysts involved in the CNO cycles, all these cycles have the same net result: The positrons will almost instantly annihilate with electrons, releasing energy in the form of gamma rays. The neutrinos escape from the star carrying away some energy. One nucleus goes on to become carbon, nitrogen, and oxygen isotopes through a number of transformations in an endless loop. The proton–proton chain is more prominent in stars the mass of the Sun or less. This difference stems from temperature dependency differences between the two reactions; pp-chain reaction starts at temperatures around 4×106 K (4 megakelvin), making it the dominant energy source in smaller stars. A self-maintaining CNO chain starts at approximately 15×106 K, but its energy output rises much more rapidly with increasing temperatures so that it becomes the dominant source of energy at approximately 17×106 K. The Sun has a core temperature of around 15.7×106 K, and only 1.7% of 4He nuclei produced in the Sun are born in the CNO cycle. The CNO-I process was independently proposed by Carl von Weizsäcker and Hans Bethe in the late 1930s. The first reports of the experimental detection of the neutrinos produced by the CNO cycle in the Sun were published in 2020. This was also the first experimental confirmation that the Sun had a CNO cycle, that the proposed magnitude of the cycle was accurate, and that von Weizsäcker and Bethe were correct.

3.5K
03 Nov 2022

Topic Review

Harvesting and Processing Techniques on Black Tea Quality

Tea (Camellia sinensis) has grown for over 300 years and is recognized worldwide as among other well-renowned crops. The quality of black tea depends on plucking (method, standard, season, and intervals), withering and rolling (time and temperature), fermentation (time, temperature, and RH), drying (temperature and method), and storage conditions, which have a high influence on the final quality of black tea. At the rolling stage, the oxidation process is initiated and ends at the early drying stage until the enzymes that transform tea polyphenols into thearubigins (TRs) and theaflavins (TFs) are denatured by heat. By increasing fermentation time, TRs increased, and TF decreased. Each is liable for black tea’s brightness, taste, and color.

3.5K
29 Dec 2023

Topic Review

α-Lactalbumin (α-LA) is a small (Mr 14,200), acidic (pI 4-5), Ca2+-binding protein. α-LA is a regulatory component of lactose synthase enzyme system. α-LA is very important in infant nutrition since it constitutes a large part of the whey and total protein in human milk. The protein possesses a single strong Ca2+-binding site, which can also bind Mg2+, Mn2+, Na+, K+, and some other metal cations. It contains several distinct Zn2+-binding sites. Physical properties of α-LA strongly depend on the occupation of its metal binding sites by metal ions. In the absence of bound metal ions α-LA is in the molten globule-like state. The binding of metal ions, and especially of Ca2+, increases stability of α-LA against action of heat, various denaturing agents, and proteases, while the binding of Zn2+ to the Ca2+-loaded protein decreases its stability and causes its aggregation. The thermal unfolding of apo-α-LA takes place in the temperature region from 10 to 30 °C. The binding of Ca2+ under the conditions of low ionic strength shifts the thermal transition to higher temperatures by more than 40 °C. The binding of Mg2+, Na+, and K+ increases protein stability as well. The stronger an ion binds to the protein, the more pronounced the thermal transition shift. All four classes of surfactants (anionic, cationic, non-ionic, and zwitterionic) denature α-LA and the denaturation involves at least one intermediate. The position of any denaturation transition in α-LA (half-transition temperature, half-transition pressure, half-transition denaturant concentration) depends upon metal ion concentration in solution (especially if this metal ion is Ca2+). Therefore, values of denaturation temperature or urea or guanidine hydrochloride denaturing concentration are relatively meaningless for α-LA without specifying the metal ion content(s) and their solution concentration(s). At a neutral or slightly acidic pH at a physiological temperature, α-LA can associate with membranes. The conformations of the membrane-bound protein range from native-like to molten globule-like states. At a low pH, α-LA penetrates the interior of the negatively charged membranes and exhibits a molten globule conformation. Depending on external conditions, α-LA can form amyloid fibrils, amorphous aggregates, nanoparticles, and nanotubes. At pH 2, α-LA in the classical molten globule conformation can form amyloid fibrils. Some of these aggregated states of α-LA (nanoparticles, nanotubes) can be used in practical applications such as drug delivery to tissues and organs. The structure and self-assembly behavior of α-LA are governed by a subtle balance between hydrophobic and polar interactions and this balance can be finely tuned through the addition of selected substances. Small size nanoparticles of α-LA (100 to 200 nm) can be obtained with the use of various desolvating agents. Partially hydrolyzed α-LA can form nanotubes. α-LA and some of its fragments possess bactericidal and antiviral activities. Complexes of partially unfolded α-LA with oleic acid showed significant cytotoxicity to various tumor and bacterial cells. α-LA in such complexes plays a role of a delivery carrier of cytotoxic fatty acid molecules into tumor cells across the cell membrane. Cytotoxic protein–oleic acid complexes possess a common core-shell structure, where an oily core is made of a micellar oleic acid, whereas a proteinaceous shell, which stabilizes the oleic acid micelle, is formed from the flexible, partially unfolded proteins. These complexes called liprotides (lipids and partially denatured proteins), which are potential novel anti-tumorous drugs, can be considered as molten globular containers filled with the toxic oil.

3.5K
31 Aug 2020

Topic Review

The pudus (Mapudungun püdü or püdu, Spanish: pudú, Spanish pronunciation: [puˈðu]) are two species of South American deer from the genus Pudu, and are the world's smallest deer. The name is a loanword from Mapudungun, the language of the indigenous Mapuche people of central Chile and south-western Argentina. The two species of pudus are the northern pudu (Pudu mephistophiles) from Venezuela, Colombia, Ecuador, and Peru, and the southern pudu (Pudu puda; sometimes incorrectly modified to Pudu pudu) from southern Chile and south-western Argentina . Pudus range in size from 32 to 44 centimeters (13 to 17 in) tall, and up to 85 centimeters (33 in) long. The southern pudu is currently classified as near threatened, while the northern pudu is classified as Data Deficient in the IUCN Red List.

3.5K
20 Oct 2022

Topic Review

Big Data Analytics in COVID-19

The COVID-19 epidemic has caused a large number of human losses and havoc in the economic, social, societal, and health systems around the world. Controlling such epidemic requires understanding its characteristics and behavior, which can be identified by collecting and analyzing the related big data. Big data analytics tools play a vital role in building knowledge required in making decisions and precautionary measures. However, due to the vast amount of data available on COVID-19 from various sources, there is a need to review the roles of big data analysis in controlling the spread of COVID-19, presenting the main challenges and directions of COVID-19 data analysis, as well as providing a framework on the related existing applications and studies to facilitate future research on COVID-19 analysis.

3.5K
04 Jun 2021

Topic Review

Sovereign Citizen Movement

The sovereign citizen movement is a loose grouping of primarily American litigants, commentators, tax protesters, and financial-scheme promoters, who claim to be answerable only to their particular interpretations of the common law and to not be subject to any government statutes or proceedings. In the United States, they do not recognize U.S. currency and maintain that they are "free of any legal constraints". They especially reject most forms of taxation as illegitimate. Participants in the movement argue this concept in opposition to the idea of "federal citizens", who, they say, have unknowingly forfeited their rights by accepting some aspect of federal law. The doctrines of the movement resemble those of the freemen on the land movement more commonly found in the British Commonwealth, such as Australia and Canada. Many members of the sovereign citizen movement claim that the United States government is illegitimate. The sovereign citizen movement has been described as consisting of individuals who assert that the county sheriff is the most powerful law-enforcement officer in the country, with authority superior to that of any federal agent, elected official, or local law-enforcement official. The movement can be traced back to white-extremist groups like Posse Comitatus and the constitutional militia movement. It also includes members of certain self-declared "Moorish" sects. While the movement was originally associated with White supremacism, it now includes varying racial ideologies as well as a variety of people, most commonly white and African American. The Federal Bureau of Investigation (FBI) classifies some sovereign citizens ("sovereign citizen extremists") as domestic terrorists. In 2010, the Southern Poverty Law Center (SPLC) estimated that approximately 100,000 Americans were "hard-core sovereign believers", with another 200,000 "just starting out by testing sovereign techniques for resisting everything from speeding tickets to drug charges". In surveys conducted in 2014 and 2015, representatives of U.S. law enforcement ranked the risk of terrorism from the sovereign citizen movement higher than the risk from any other group, including Islamic extremists, militias, racists, and neo-Nazis. The New South Wales Police Force in Australia has also identified sovereign citizens as a potential terrorist threat.

3.5K
24 Nov 2022

Topic Review

Flow (Psychology)

In positive psychology, a flow state, also known colloquially as being in the zone, is the mental state in which a person performing some activity is fully immersed in a feeling of energized focus, full involvement, and enjoyment in the process of the activity. In essence, flow is characterized by the complete absorption in what one does, and a resulting transformation in one's sense of time. Named by the psychologist Mihály Csíkszentmihályi in 1975, the concept has been widely referred to across a variety of fields (and is particularly well recognized in occupational therapy), though the concept has been claimed to have existed for thousands of years under other names. The flow state shares many characteristics with hyperfocus. However, hyperfocus is not always described in a positive light. Some examples include spending "too much" time playing video games or becoming pleasurably absorbed by one aspect of an assignment or task to the detriment of the overall assignment. In some cases, hyperfocus can "capture" a person, perhaps causing them to appear unfocused or to start several projects, but complete few. Hyperfocus is often mentioned "in the context of autism, schizophrenia, and attention deficit hyperactivity disorder- conditions that have consequences on attentional abilities."

3.5K
30 Sep 2022

Topic Review

Adaptive Reuse of Abandoned School Buildings

School closures not only affect students and teachers; these spaces serve as anchor institutions providing social infrastructure for the sustained health of communities. While closed schools remove a critical community asset, these vacant buildings provide adaptive reuse opportunities for alternative social infrastructure and community resources.

3.5K
25 Dec 2023

Topic Review

Black Belt (Region of Alabama)

The Black Belt is a region of the U.S. state of Alabama. The term originally referred to the region's rich, black topsoil, much of it in the soil order Vertisols. The term took on an additional meaning in the 19th century, when the region was developed for cotton plantation agriculture, in which the workers were enslaved African Americans. After the American Civil War, many freedmen stayed in the area as sharecroppers and tenant farmers, continuing to comprise a majority of the population in many of these counties. The sociological definition of the "Black Belt," as related to the history of this cotton-dependent region, refers to a much larger region of the Southern United States, stretching from Delaware to Texas but centered on the Black Belt of uplands areas of Georgia, Alabama, Mississippi and Louisiana. In the antebellum and Jim Crow eras, the white elite of the Black Belt dominated Alabama state politics well into the 1960s. As in other Southern states, the white-dominated state legislature of Alabama passed laws and a constitution that created barriers to voter registration, essentially disfranchising most blacks and many poor whites. In addition, the state legislature did not redistrict congressional or state legislative districts after 1901 until it did so in the 1960s under US Supreme Court order. The white rural elite continued to dominate the state despite the rise of urbanized, industrial cities such as Birmingham, Alabama. Montgomery, the Black Belt's largest city, has been the capital of Alabama since 1846. Montgomery and Selma and other parts of the Black Belt were important centers of African-American public activism during the Civil Rights Movement from the 1950s to 1968. Since the black population gained the renewed ability to exercise their franchise after 1965 under the Voting Rights Act, they have largely supported Democratic Party candidates. This is in contrast to the majority-white areas of the state, where since the late 20th century, conservatives have largely shifted from the Democratic to the Republican Party.

3.5K
10 Oct 2022

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