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Topic Review
Metal Matrix Composites
Metal matrix composites (MMCs) present extraordinary characteristics, including high wear resistance, excellent operational properties at elevated temperature, and better chemical inertness as compared to traditional alloys. These properties make them prospective candidates in the fields of aerospace, automotive, heavy goods vehicles, electrical, and biomedical industries. MMCs are challenging to process via traditional manufacturing techniques, requiring high cost and energy. The laser-melting deposition (LMD) has recently been used to manufacture MMCs via rapid prototyping, thus, solving these drawbacks. Besides the benefits mentioned above, the issues such as lower ultimate tensile strength, yield strength, weak bonding between matrix and reinforcements, and cracking are still prevalent in parts produced by LMD. In this article, a detailed analysis is made on the MMCs manufactured via LMD. An illustration is presented on the LMD working principle, its classification, and dependent and independent process parameters. Moreover, a brief comparison between the wire and powder-based LMDs has been summarized. Ex- and in-situ MMCs and their preparation techniques are discussed. Besides this, various matrices available for MMCs manufacturing, properties of MMCs after printing, possible complications and future research directions are reviewed and summarized.
  • 2.8K
  • 18 May 2021
Topic Review
2012 Phenomenon
The 2012 phenomenon was a range of eschatological beliefs that cataclysmic or transformative events would occur around 21 December 2012. This date was regarded as the end-date of a 5,126-year-long cycle in the Mesoamerican Long Count calendar, and festivities took place on 21 December 2012 to commemorate the event in the countries that were part of the Maya civilization (Mexico, Guatemala, Honduras, and El Salvador), with main events at Chichén Itzá in Mexico and Tikal in Guatemala. Various astronomical alignments and numerological formulae were proposed for this date. A New Age interpretation held that the date marked the start of a period during which Earth and its inhabitants would undergo a positive physical or spiritual transformation, and that 21 December 2012 would mark the beginning of a new era. Others suggested that the date marked the end of the world or a similar catastrophe. Scenarios suggested for the end of the world included the arrival of the next solar maximum, an interaction between Earth and the supermassive black hole at the center of the galaxy, or Earth's collision with a mythical planet called Nibiru. Scholars from various disciplines quickly dismissed predictions of cataclysmic events as they arose. Mayan scholars stated that no classic Mayan accounts forecast impending doom, and the idea that the Long Count calendar ends in 2012 misrepresented Mayan history and culture. Astronomers rejected the various proposed doomsday scenarios as pseudoscience which is easily refuted by elementary astronomical observations.
  • 2.8K
  • 07 Nov 2022
Topic Review
History of Human Movement Studies
Knowing the genesis of ideas is important to understand why we are studying a topic. This topic review is an historical excursus about the origin of movement studies, following the ideas of Aristotle until positivism. The main ideas at the origin of biomechanical studies are historically reviewed, with special focus on the enlightment era. Key figures at the origin of movement studies were presented, together with the main ideas they introduced, most of which are still at the basis of modern research in the field of biomechanics. The entry can be of interest for all professionals working in the field of human and animal movement studies.
  • 2.8K
  • 29 Mar 2022
Topic Review
Development of Therapeutic Monoclonal Antibodies
We provide an overview of the challenges and advancements in the development of therapeutic monoclonal antibodies and antibody products.
  • 2.8K
  • 21 Sep 2021
Topic Review
DNA Barcoding
DNA barcoding is a method of species identification using a short section of DNA from a specific gene or genes. The premise of DNA barcoding is that, by comparison with a reference library of such DNA sections (also called "sequences"), an individual sequence can be used to uniquely identify an organism to species, in the same way that a supermarket scanner uses the familiar black stripes of the UPC barcode to identify an item in its stock against its reference database. These "barcodes" are sometimes used in an effort to identify unknown species, parts of an organism, or simply to catalog as many taxa as possible, or to compare with traditional taxonomy in an effort to determine species boundaries. Different gene regions are used to identify the different organismal groups using barcoding. The most commonly used barcode region for animals and some protists is a portion of the cytochrome c oxidase I (COI or COX1) gene, found in mitochondrial DNA. Other genes suitable for DNA barcoding are the internal transcribed spacer (ITS) rRNA often used for fungi and RuBisCO used for plants. Microorganisms are detected using different gene regions. The 16S rRNA gene for example is widely used in identification of prokaryotes, whereas the 18S rRNA gene is mostly used for detecting microbial eukaryotes. These gene regions are chosen because they have less intraspecific (within species) variation than interspecific (between species) variation, which is known as the "Barcoding Gap". Some applications of DNA barcoding include: identifying plant leaves even when flowers or fruits are not available; identifying pollen collected on the bodies of pollinating animals; identifying insect larvae which may have fewer diagnostic characters than adults; or investigating the diet of an animal based on its stomach content, saliva or feces. When barcoding is used to identify organisms from a sample containing DNA from more than one organism, the term DNA metabarcoding is used, e.g. DNA metabarcoding of diatom communities in rivers and streams, which is used to assess water quality.
  • 2.8K
  • 16 Nov 2022
Topic Review
Theory of Planned Behavior in Energy-Saving Behaviors
People with physical impairments can help solve energy problems by participating in diverse energy-saving behaviors, such as switching off lights or turning off an air conditioner when not in use; however, they may struggle to participate in some behaviors due to mobility impairments. An energy-saving behavior is an individual action that aims to reduce energy consumption and the negative environmental impacts of energy consumption and production. The theory of planned behavior (TPB), which was proposed by Ajzen in 1985, is an extension of the theory of reasoned action (TRA).
  • 2.8K
  • 30 Sep 2022
Topic Review
Deep Sea Fish
Deep-sea fish are animals that live in the darkness below the sunlit surface waters, that is below the epipelagic or photic zone of the sea. The lanternfish is, by far, the most common deep-sea fish. Other deep sea fishes include the flashlight fish, cookiecutter shark, bristlemouths, anglerfish, viperfish, and some species of eelpout. Only about 2% of known marine species inhabit the pelagic environment. This means that they live in the water column as opposed to the benthic organisms that live in or on the sea floor. Deep-sea organisms generally inhabit bathypelagic (1000–4000m deep) and abyssopelagic (4000–6000m deep) zones. However, characteristics of deep-sea organisms, such as bioluminescence can be seen in the mesopelagic (200–1000m deep) zone as well. The mesopelagic zone is the disphotic zone, meaning light there is minimal but still measurable. The oxygen minimum layer exists somewhere between a depth of 700m and 1000m deep depending on the place in the ocean. This area is also where nutrients are most abundant. The bathypelagic and abyssopelagic zones are aphotic, meaning that no light penetrates this area of the ocean. These zones make up about 75% of the inhabitable ocean space. The epipelagic zone (0–200m) is the area where light penetrates the water and photosynthesis occurs. This is also known as the photic zone. Because this typically extends only a few hundred meters below the water, the deep sea, about 90% of the ocean volume, is in darkness. The deep sea is also an extremely hostile environment, with temperatures that rarely exceed 3 °C (37.4 °F) and fall as low as −1.8 °C (28.76 °F) (with the exception of hydrothermal vent ecosystems that can exceed 350 °C, or 662 °F), low oxygen levels, and pressures between 20 and 1,000 atmospheres (between 2 and 100 megapascals).
  • 2.8K
  • 08 Nov 2022
Topic Review
Fungal decomposition of dead wood
Fungi create a nutritional niche for deadwood-eaters ------------------------------ Direct comparison of the amounts of essential nutrients and ergosterol in wood provides evidence that the changes in the stoichiometry of decaying dead wood are driven by the action of fungi. They infest dead wood to take advantage of the ample supply of an energy-rich substrate. However, to exploit this resource, these fungi must import an array of essential nutrients from outside of the dead wood. This nutritional enrichment of dead wood creates a nutritional niche for xylophages that allows them to grow, develop, and reach maturity. Therefore, xylophagous beetles (considered as “wood-eaters”) are unable to gather the necessary amounts of nutrients from pure dead wood to grow and mature, but instead must utilize fungal tissues. ------------------------------
  • 2.8K
  • 03 Nov 2020
Topic Review
Spray Drying for Oils Encapsulation
This is a entry focused on the application of spray drying technology for the edible oils encapsulation. This entry covered most of the relevant works have done recently on the encapsulation of oils by spray drying. The factors affecting the process of encapsulation and the application in food with the properties of the final product.The application of the spray drying technique in the food industry for the production of a broad range of ingredients has become highly desirable compared to other drying techniques. Recently, the spray drying technique has been applied extensively for the production of functional foods, pharmaceuticals and nutraceuticals. Encapsulation using spray drying is highly preferred due to economic advantages compared to other encapsulation methods. Encapsulation of oils using the spray drying technique is carried out in order to enhance the handling properties of the products and to improve oxidation stability by protecting the bioactive compounds. Encapsulation of oils involves several parameters—including inlet and outlet temperatures, total solids, and the type of wall materials—that significantly affect the quality of final product.
  • 2.8K
  • 19 Apr 2022
Topic Review
Bovine Colostrum in the Treatment of Cancer
Bovine colostrum (BC) has attracted the interest of numerous researchers investigating its anti-cancer potential in humans. Dressings loaded with BC are beneficial in treating chronic wounds and diabetic foot ulcers. Lactoferrin, a glycoprotein with potent anti-oxidant, anti-inflammatory, anti-cancer, and anti-microbial effects, is abundant in BC. The BC pills successfully promote the regression of low-grade cervical intraepithelial neoplasia when administered intravaginally. The biological, genetic, and molecular mechanisms driving BC remain to be determined. Oral BC supplements are generally well-tolerated, but some flatulence and nausea may happen. 
  • 2.8K
  • 21 Dec 2022
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