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Topic Review
Halogen Bonds
A halogen bond occurs when there is evidence of a net attractive interaction between an electrophilic region associated with a halogen atom in a molecular entity and a nucleophilic region in another, or the same, molecular entity.
  • 4.6K
  • 08 Dec 2020
Topic Review
Halt and Catch Fire
In computer engineering, Halt and Catch Fire, known by the assembly mnemonic HCF, is an idiom referring to a computer machine code instruction that causes the computer's central processing unit (CPU) to cease meaningful operation, typically requiring a restart of the computer. It originally referred to a fictitious instruction in IBM System/360 computers, making a joke about its numerous non-obvious instruction mnemonics. With the advent of the MC6800, a design flaw was discovered by the programmers. Due to incomplete opcode decoding, two illegal opcodes, 0x9D and 0xDD, will cause the program counter on the processor to increment endlessly, which renders the processor useless. Those codes have been unofficially named HCF. During the design process of MC6802, engineers originally planned to remove this instruction, but kept it as-is for testing purposes. As a result, HCF was officially recognized as a real instruction. Later, HCF became a humorous catch-all term for instructions that may freeze a processor, including intentional instructions for testing purposes, and unintentional illegal instructions. Some are considered hardware defects, and if the system is shared, a malicious user can execute it to launch a denial-of-service attack. In the case of real instructions, the implication of this expression is that, whereas in most cases in which a CPU executes an unintended instruction (a bug in the code) the computer may still be able to recover, in the case of an HCF instruction there is, by definition, no way for the system to recover without a restart. The expression "catch fire" is a facetious exaggeration of the speed with which the CPU chip would be switching some bus circuits, causing them to overheat and burn.
  • 4.6K
  • 04 Nov 2022
Topic Review
A Message from Earth (2008)
A Message from Earth (AMFE) is a high-powered digital radio signal that was sent on 9 October 2008 towards Gliese 581c, a large terrestrial extrasolar planet orbiting within the Gliese 581 system. The signal is a digital time capsule containing 501 messages that were selected through a competition on the social networking site Bebo. The message was sent using the RT-70 radar telescope. The signal will reach the planet Gliese 581c in early 2029. More than half a million people including celebrities and politicians participated in the AMFE project, which was the world's first digital time capsule where the content was selected by the public. As of 1 February 2018, the message has traveled 62.43 trillion kilometers of the total 192 trillion kilometers, which is 33.5% of the distance to the Gliese 581 system. On 13 February 2015, scientists (including David Grinspoon, Seth Shostak, and David Brin) at an annual meeting of the American Association for the Advancement of Science, discussed Active SETI and whether transmitting a message to possible intelligent extraterrestrials in the Cosmos was a good idea; That same week, a statement was released, signed by many in the SETI community, that a "worldwide scientific, political and humanitarian discussion must occur before any message is sent". However neither Frank Drake, nor Seth Shostak signed this appeal. On 28 March 2015, a related essay with some different point of view was written by Seth Shostak and published in The New York Times .
  • 4.6K
  • 21 Oct 2022
Topic Review
Type 69 RPG
The Type 69 85mm rocket propelled grenade (RPG), made by Norinco, is a Chinese variant of the Soviet RPG-7. First introduced in 1972, the Type 69 is a common individual anti-tank weapon in service with the PLA. More advanced grenade rounds were developed in the 1980s and 1990s to meet the requirements of modern battlefields. Eventually, the aging Type 69 RPG family was replaced by modern anti-tank weapon systems developed by China such as Type 89 and Type 08.
  • 4.6K
  • 08 Nov 2022
Topic Review
Modern Power Systems
Modern power systems include various technological innovations such as distributed renewable energy sources, energy storage devices, electric vehicle charging stations and advanced communication systems. Since many of these components are owned and managed by private entities, the planning and management of modern power systems is gradually changing, and is becoming a great challenge for utility companies and regulators. 
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  • 16 Jun 2021
Topic Review
C3 to CAM Photosynthesis Transition
Global climate change and population growth are persistently posing threats to natural resources (e.g., freshwater) and agricultural production. Crassulacean acid metabolism (CAM) evolved from C3 photosynthesis as an adaptive form of photosynthesis in hot and arid regions. It features the nocturnal opening of stomata for CO2 assimilation, diurnal closure of stomata for water conservation, and high water-use efficiency.
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  • 08 Sep 2023
Topic Review
Transparent Solar Windows
Many modern glass and window products are based on metal-dielectric coatings, which can control properties such as thermal emissivity, heat gain, colour, and transparency. These can also enable solar energy harvesting through PV integration, if the glazing structure is purpose-designed, to include luminescent materials and special microstructures. Recently, significant progress has been demonstrated in building integrated transparent solar windows, which are expected to add momentum towards the development of smart cities. These window systems are, at present in 2019, the only type of transparent and clear construction materials capable of providing significant energy savings in buildings, simultaneously with renewable energy generation.
  • 4.6K
  • 09 Oct 2024
Topic Review
Mekong
The Mekong, or Mekong River, is a trans-boundary river in East Asia and Southeast Asia. It is the world's twelfth longest river and the sixth longest in Asia. Its estimated length is 4,909 km (3,050 mi), and it drains an area of 795,000 km2 (307,000 sq mi), discharging 475 km3 (114 cu mi) of water annually. From the Tibetan Plateau the river runs through China , Myanmar, Laos, Thailand, Cambodia, and Vietnam. The extreme seasonal variations in flow and the presence of rapids and waterfalls in the Mekong make navigation difficult. Even so, the river is a major trade route between western China and Southeast Asia.
  • 4.6K
  • 25 Nov 2022
Topic Review
Household Food Waste in Bangkok
Food waste (FW) is one of the world’s major crises in both developed and developing countries. Up to 1.3 billion tons of food across the globe is thrown away each year, accounting for one third of all food produced for human consumption and presenting tremendous social, economic, and environmental challenges. In Thailand, FW causes a significant problem when it comes to waste management, particularly in metropolitan areas. Studies conducted between 2005 and 2009 indicated that FW made up the greatest proportion of all waste collected in Bangkok at between 42% and 45%. This waste was generated in households and was usually thrown away into garbage bins, to be collected and buried in landfills by governmental and private sector companies.
  • 4.6K
  • 04 Aug 2021
Topic Review
Distributed Machine Learning in Edge Computing
Distributed edge intelligence is a disruptive research area that enables the execution of machine learning and deep learning (ML/DL) algorithms close to where data are generated. Since edge devices are more limited and heterogeneous than typical cloud devices, many hindrances have to be overcome to fully extract the potential benefits of such an approach (such as data-in-motion analytics).
  • 4.6K
  • 20 Apr 2022
Topic Review
Hydraulic Accumulators in Hydraulic Systems
Electric motors used in industrial machines and devices, as well as internal combustion engines (ICE) used in vehicles, mobile machines, and marine devices, participate in the transformation of mechanical power into hydraulic power. In power transmission, hydraulic drive systems have a high power density. Hydraulic pumps, as energy sources in hydraulic drive systems, are widely used due to their high working pressure and high flow rate. The hydraulic accumulator (HA) is a device that is used to store energy in the hydraulic system in the form of pressure energy. 
  • 4.6K
  • 14 Sep 2023
Topic Review
Textile Recycling
Textile reuse consists of the various methods of prolonging the useful service life of textile products from one owner to another. Renting, trading, swapping, borrowing, and inheriting are commonly practiced, which are facilitated by second-hand stores, garage sales, online stores and flea markets, and charities. On the other hand, textile recycling refers to reprocessing pre-consumer and post-consumer textile waste for use in new textile or non-textile products. Various textile recycling technologies such as fiber regeneration, conversion of textile waste into insulation/building materials, fermentation, anaerobic digestion, composting, and thermal recovery are available and progressively improved. Textile reuse and recycling offer environmental sustainability and can reduce environmental impact by reducing the use of virgin textile fiber and avoiding processes further downstream in the textile product life cycle. 
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  • 28 Mar 2022
Topic Review
N-Acetylcysteine in Trichotillomania
N-acetylcysteine (NAC) (C5H9NO3S) is the acetylated precursor of the amino acid L-cysteine and functions as a glutamate modulator and antioxidant. It is widely known as a mucolytic, an antidote for acetaminophen overdose, and a nephroprotective agent for contrast administration. Trichotillomania (TTM), excoriation disorder, onychophagia, and onychotillomania are categorized as body focused repetitive behavior (BFRB) disorders, causing damage to the skin, hair, and/or nails with clinically significant psychosocial consequences.
  • 4.6K
  • 13 Jun 2022
Biography
Robert Kearns
Robert William Kearns PhD (March 10, 1927 – February 9, 2005) was an American engineer, educator and inventor who invented the intermittent windshield wiper systems used on most automobiles from 1969 to the present. His first patent for the invention was filed on December 1, 1964. Kearns won one of the best known patent infringement cases against Ford Motor Company (1978–1990) and a case a
  • 4.6K
  • 23 Nov 2022
Topic Review
Intermarium
Intermarium (Polish: Międzymorze, Polish pronunciation: [mʲɛnd͡zɨˈmɔʐɛ]) was a geopolitical project conceived by politicians in successor states of the former Polish–Lithuanian Commonwealth in several iterations, some of which anticipated the inclusion as well of other, neighboring states. The proposed multinational polity would have extended across territories lying between the Baltic, Black and Adriatic Seas, hence the name meaning "Between-Seas". Prospectively a federation of Central and Eastern European countries, the post-World War I Intermarium plan pursued by Polish leader and former political prisoner of the Russian Empire, Józef Piłsudski (1867–1935), sought to recruit to the proposed federation the Baltic states (Lithuania, Latvia, Estonia), Finland , Belarus, Ukraine, Hungary, Romania, Yugoslavia and Czechoslovakia. The Polish name Międzymorze (from między, "between"; and morze, "sea"), meaning "Between-Seas", was rendered into Latin as "Intermarium." The proposed federation was meant to emulate the Polish–Lithuanian Commonwealth, stretching from the Baltic Sea to the Black Sea, that, from the end of the 16th century to the end of the 18th, had united the Kingdom of Poland and the Grand Duchy of Lithuania. Intermarium complemented Piłsudski's other geopolitical vision, Prometheism, whose goal was the dismemberment of the Russian Empire and that Empire's divestment of its territorial acquisitions. Intermarium was, however, perceived by some Lithuanians as a threat to their newly established independence, and by some Ukrainians as a threat to their aspirations for independence, and while France backed the proposal, it was opposed by Russia and by most other Western powers. Within two decades of the failure of Piłsudski's grand scheme, all the countries that he had viewed as candidates for membership in the Intermarium federation had fallen to the Soviet Union or Nazi Germany, except for Finland (which suffered some territorial losses in the 1939–40 Winter War with the Soviet Union).
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  • 19 Oct 2022
Topic Review
Dromomania
Dromomania was a historical psychiatric diagnosis whose primary symptom was uncontrollable urge to walk or wander. Dromomania has also been referred to as travelling fugue. Non-clinically, the term has come to be used to describe a desire for frequent traveling or wanderlust.
  • 4.6K
  • 01 Nov 2022
Topic Review
Methods for Electric Energy Accumulation
The daily non-uniform power demand is a serious problem in power industry. In addition, recent decades show a trend for the transition to renewable power sources, but their power output depends upon weather and daily conditions. These factors determine the urgency of energy accumulation technology research and development. The presence of a wide variety of energy storage mechanisms leads to the need for their classification and comparison as well as a consideration of possible options for their application in modern power units.
  • 4.6K
  • 23 Dec 2022
Topic Review
Dental Plaque
Dental plaque is a community of microorganisms found on the surface of teeth or other hard surfaces like dentures and embedded in a matrix of polymers of both host and bacterial origin.
  • 4.6K
  • 23 Sep 2021
Topic Review
Evolution of the Domesticated Cat
The domestic cat originated from Near-Eastern and Egyptian populations of the African wildcat, Felis sylvestris lybica. The family Felidae, to which all living feline species belong, arose about ten to eleven million years ago. This family is divided into eight major phylogenetic lineages. The domestic cat is a member of the Felis lineage. A number of investigations have shown that all domestic varieties of cats come from a single species of the Felis lineage, Felis catus. Variations of this lineage are found all over the world and up until recently scientists have had a hard time pinning down exactly which region gave rise to modern domestic cat breeds. Scientists believed that it was not just one incident that led to the domesticated cat but multiple, independent incidents at different places that led to these breeds. More complications arose from the fact that the wildcat population as a whole is very widespread and very similar to one another. These variations of wild cat can and will interbreed freely with one another when in close contact, further blurring the lines between taxa. Recent DNA studies, advancement in genetic technologies, and a better understanding of DNA and genetics as a whole has helped make discoveries in the evolutionary history of the domestic cat.
  • 4.6K
  • 25 Nov 2022
Topic Review
Papaverine and Its Mechanism of Action
Papaverine has been proven to be a high-value opioid alkaloid in the field of therapeutics either in solitude or in combination with other metabolites/molecules. Pharmacological research has revealed that papaverine demonstrates a variety of biological activities, including activity against erectile dysfunction, postoperative vasospasms, and pulmonary vasoconstriction, as well as antiviral, cardioprotective, anti-inflammatory, anticancer, neuroprotective, and gestational actions.
  • 4.6K
  • 07 Apr 2023
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