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HandWiki is the world's largest wiki-style encyclopedia dedicated to science, technology and computing. It allows you to create and edit articles as long as you have external citations and login account. In addition, this is a content management environment that can be used for collaborative editing of original scholarly content, such as books, manuals, monographs and tutorials.

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Cylinder Block
The cylinder block is an integrated structure comprising the cylinder(s) of a reciprocating engine and often some or all of their associated surrounding structures (coolant passages, intake and exhaust passages and ports, and crankcase). The term engine block is often used synonymously with "cylinder block" (although technically distinctions can be made between en bloc cylinders as a discrete unit versus engine block designs with yet more integration that comprise the crankcase as well). In the basic terms of machine elements, the various main parts of an engine (such as cylinder(s), cylinder head(s), coolant passages, intake and exhaust passages, and crankcase) are conceptually distinct, and these items can all be made as discrete pieces that are bolted together. Such construction was very widespread in the early decades of the commercialization of internal combustion engines (1880s to 1920s), and it is still sometimes used in certain applications where it remains advantageous (especially very large engines, but also some small engines). However, it is no longer the normal way of building most petrol engines and diesel engines, because for any given engine configuration, there are more efficient ways of designing for manufacture (and also for maintenance and repair). These generally involve integrating multiple machine elements into one discrete part, and doing the making (such as casting, stamping, and machining) for multiple elements in one setup with one machine coordinate system (of a machine tool or other piece of manufacturing machinery). This yields lower unit cost of production (and/or maintenance and repair). Today most engines for cars, trucks, buses, tractors, and so on are built with fairly highly integrated design, so the words "monobloc" and "en bloc" are seldom used in describing them; such construction is often implicit. Thus "engine block", "cylinder block", or simply "block" are the terms likely to be heard in the garage or on the street.
  • 5.2K
  • 28 Sep 2022
Topic Review
Cardiolipin
Cardiolipin (IUPAC name 1,3-bis(sn-3’-phosphatidyl)-sn-glycerol) is an important component of the inner mitochondrial membrane, where it constitutes about 20% of the total lipid composition. It can also be found in the membranes of most bacteria. The name "cardiolipin" is derived from the fact that it was first found in animal hearts. It was first isolated from beef heart in the early 1940s. In mammalian cells, but also in plant cells, cardiolipin (CL) is found almost exclusively in the inner mitochondrial membrane, where it is essential for the optimal function of numerous enzymes that are involved in mitochondrial energy metabolism.
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  • 28 Sep 2022
Topic Review
Natural Gas Processing
Natural gas processing plants, or fractionators, are used to purify the raw natural gas extracted from underground gas fields and brought up to the surface by gas wells. The processed natural gas, used as fuel by residential, commercial and industial consumers, is almost pure methane and is very much different from the raw natural gas.
  • 3.4K
  • 28 Sep 2022
Topic Review
Landslide Mitigation
Landslide mitigation refers to mass movement of rocks and other man-made activities on slopes with the goal of lessening the effect of landslides. Landslides can be triggered by many, sometimes concomitant causes. In addition to shallow erosion or reduction of shear strength caused by seasonal rainfall, landslides may be triggered by anthropic activities, such as adding excessive weight above the slope, digging at mid-slope or at the foot of the slope. Often, individual phenomenon join together to generate instability over time, which often does not allow a reconstruction of the evolution of a particular landslide. Therefore, landslide hazard mitigation measures are not generally classified according to the phenomenon that might cause a landslide. Instead, they are classified by the sort of slope stabilization method used: Each of these methods varies somewhat with the type of material that makes up the slope.
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  • 29 Sep 2022
Topic Review
Melanin
Melanin (/ˈmɛlənɪn/ (listen); from Greek: μέλας, romanized: melas, lit. 'black, dark') is a broad term for a group of natural pigments found in most organisms. Eumelanin is produced through a multistage chemical process known as melanogenesis, where the oxidation of the amino acid tyrosine is followed by polymerization. The melanin pigments are produced in a specialized group of cells known as melanocytes. Functionally, eumelanin serves as protection against UV radiation. Melanin (neuromelanin) functions as the catalyst of all cellular functions within an organism. There are five basic types of melanin: eumelanin, pheomelanin, neuromelanin, allomelanin and pyomelanin. The most common type is eumelanin, of which there are two types— brown eumelanin and black eumelanin. Pheomelanin, which is produced when melanocytes are malfunctioning due to derivation of the gene to its recessive format is a cysteine-derivative that contains polybenzothiazine portions that are largely responsible for the of red yellow tint given to some skin or hair colors. Neuromelanin is found in the brain. Research has been undertaken to investigate its efficacy in treating neurodegenerative disorders such as Parkinson's. Allomelanin and pyomelanin are two types of nitrogen-free melanin. In the human skin, melanogenesis is initiated by exposure to UV radiation, causing the skin to darken. Eumelanin is an effective absorbent of light; the pigment is able to dissipate over 99.9% of absorbed UV radiation. Because of this property, eumelanin is thought to protect skin cells from UVA and UVB radiation damage, reducing the risk of folate depletion and dermal degradation. It is considered that exposure to UV radiation is associated with increased risk of malignant melanoma, a cancer of melanocytes (melanin cells). Studies have shown a lower incidence for skin cancer in individuals with more concentrated melanin, i.e. darker skin tone.
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  • 28 Sep 2022
Topic Review
Incidents in the Life of Madame Blavatsky
Incidents in the Life of Madame Blavatsky: compiled from information supplied by her relatives and friends is a book originally published in 1886 in London; it was compiled by a member of the Theosophical Society A. P. Sinnett, the first biographer of H. P. Blavatsky (née Hahn). He describes the many unusual incidents in her life, beginning from her childhood in Russia and asserts that she has been with "an early connection with the supernatural world;" he says about her short unlucky marriage and "decade of extensive global travels," about her period of learning in Tibet, and the "criticism she received about some of her 'phenomena' and practices."
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  • 06 Oct 2022
Topic Review
Anonymous Web Browsing
Anonymous web browsing refers to the utilization of the World Wide Web that hides a user's personally identifiable information from websites visited. The current popular application for anonymous browsing is the Tor Browser.
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  • 28 Sep 2022
Topic Review
Unsaturated Fat
An unsaturated fat is a fat or fatty acid in which there is at least one double bond within the fatty acid chain. A fatty acid chain is monounsaturated if it contains one double bond, and polyunsaturated if it contains more than one double bond. Where double bonds are formed, hydrogen atoms are subtracted from the carbon chain. Thus, a saturated fat has no double bonds, has the maximum number of hydrogens bonded to the carbons, and therefore is "saturated" with hydrogen atoms. In cellular metabolism, unsaturated fat molecules contain somewhat less energy (i.e., fewer calories) than an equivalent amount of saturated fat. The greater the degree of unsaturation in a fatty acid (i.e., the more double bonds in the fatty acid) the more vulnerable it is to lipid peroxidation (rancidity). Antioxidants can protect unsaturated fat from lipid peroxidation.
  • 2.3K
  • 28 Sep 2022
Topic Review
Writing Therapy
Writing therapy is a form of expressive therapy that uses the act of writing and processing the written word as therapy. Writing therapy posits that writing one's feelings gradually eases feelings of emotional trauma. Writing therapeutically can take place individually or in a group and it can be administered in person with a therapist or remotely through mailing or the Internet. The field of writing therapy includes many practitioners in a variety of settings. The therapy is usually administered by a therapist or counselor. Several interventions exist online. Writing group leaders also work in hospitals with patients dealing with mental and physical illnesses. In university departments they aid student self-awareness and self-development. When administered at a distance, it is useful for those who prefer to remain personally anonymous and are not ready to disclose their most private thoughts and anxieties in a face-to-face situation. As with most forms of therapy, writing therapy is adapted and used to work with a wide range of psychoneurotic issues, including bereavement, desertion and abuse. Many of these interventions take the form of classes where clients write on specific themes chosen by their therapist or counsellor. Assignments may include writing unsent letters to selected individuals, alive or dead, followed by imagined replies from the recipient, or a dialogue with the recovering alcoholic's bottle of alcohol.
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  • 28 Sep 2022
Topic Review
Ex Nihilo
Ex nihilo is Latin for "out of nothing": when phrased as ex nihilo nihil fit, "nothing comes from nothing", it means that the universe was formed from eternal matter; as creatio ex nihilo, "creation out of nothing", it means that matter is not eternal but had to be created by some eternal uncaused cause, frequently defined as God. Creation ex nihilo is a theistic answer to the question of how the universe comes to exist: the Big Bang theory, by contrast, is a scientific theory; it offers no explanation of cosmic existence but only a description of the first few moments of that existence.
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  • 28 Sep 2022
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