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66-417: A shackle is also the similarly shaped piece of metal used with a locking mechanism in padlocks . A carabiner is a type of shackle used in mountaineering . With a larger "O" shape to the loop, this shackle can take loads from many directions without developing as much side load . However, the larger shape to the loop does reduce its overall strength. Also referred to as an anchor shackle. Also known as

132-479: A chain shackle , D-shackles are narrow shackles shaped like a loop of chain, usually with a pin or threaded pin closure. D-shackles are very common and most other shackle types are a variation of the D-shackle. The small loop can take high loads primarily in line. Side and racking loads may twist or bend a D-shackle. This longer version of a D-shackle is used to attach halyards to sails , especially sails fitted with

198-503: A headboard such as on Bermuda rigged boats. Headboard shackles are often stamped from flat strap stainless steel, and feature an additional pin between the top of the loop and the bottom so the headboard does not chafe the spliced eye of the halyard. A pin shackle is closed with an anchor bolt and cotter pin, in a manner similar to a clevis . It is for this reason they are often referred to, in industrial jargon, as clevises . Pin shackles can be inconvenient to work with, at times, as

264-436: A relative density of 1.44 (0.052 lb/in ). The polymer owes its high strength to the many inter-chain bonds. These inter-molecular hydrogen bonds form between the carbonyl groups and N H centers. Additional strength is derived from aromatic stacking interactions between adjacent strands. These interactions have a greater influence on Kevlar than the van der Waals interactions and chain length that typically influence

330-410: A stamped & riveted switch lock that was so economical that many railroads stopped using the popular cast hearts and went with this new stamped shell lock body design. Many lock manufacturers made this very popular style of lock. In 1877 Yale & Towne was granted a patent for a padlock that housed a stack of levers and had a shackle that swung away when unlocked. It was a notable design because

396-444: A "shroud" covering the shackle, which is an extension of the body around the shackle to protect the shackle from getting sheared or cut. In the early 1920s, Harry Soref started Master Lock off with the first laminated padlock. Plates that were punched from sheet metal were stacked and assembled. Holes that were formed in the middle of the plates made room to accommodate the locking mechanism. The entire stack of plates, loaded with

462-436: A $ 5 million grant to research the use of the fabric in bullet-proof vests. Kevlar 149 was invented by Jacob Lahijani of Dupont in the 1980s. Kevlar is synthesized in solution from the monomers 1,4- phenylene -di amine ( para -phenylenediamine ) and terephthaloyl chloride in a condensation reaction yielding hydrochloric acid as a byproduct. The result has liquid-crystalline behavior, and mechanical drawing orients

528-717: A 90° twist so the top of the loop is perpendicular to the pin. One of the uses for this shackle include attaching the jib halyard block to the mast , or the jib halyard to the sail, to reduce twist on the luff and allow the sail to set better. Modern strong fibers such as PBO ( IUPAC name: poly(p-phenylene-2,6-benzobisoxazole), aramids ( Kevlar , Technora , Twaron ), Vectran , carbon fibers , ultra-high-molecular-weight polyethylene (UHMWPE, Dyneema, Spectra) and other synthetic fibers are used to make extra strong ropes which can also be tied into lockable loops called soft shackles . According to sailmagazine.com, "a soft shackle can handle just about every function performed by

594-419: A cross-hole in the threaded end a cotter pin can be used. One disadvantage of wire is that mousing can introduce galvanic corrosion because of material differences; it is especially bad when used in places where the shackle is exposed to air and water. Nylon is not recommended for use where significant movement of the shackle is expected. A twist shackle is usually somewhat longer than the average, and features

660-426: A disk rotated by the key enters a notch cut into the shackle to block it from moving) or lever tumblers (where a portion of the bolt that secures the shackle enters the tumblers when the correct key is turned in the lock). Padlocks with integrated locking mechanisms are characterized by a design that does not allow disassembly of the padlock. They are usually older than padlocks with modular mechanisms and often require

726-426: A key component in their construction. Other military uses include bulletproof face masks and spall liners used to protect the crews of armoured fighting vehicles . Nimitz -class aircraft carriers use Kevlar reinforcement in vital areas. Civilian applications include: high heat resistance uniforms worn by firefighters, body armour worn by police officers, security, and police tactical teams such as SWAT . Kevlar

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792-403: A liberal coating of lanolin or a heavy grease is not out of place on any and all threads. A shackle key or metal marlinspike are useful tools for loosening a tight nut . For safety, it is common to mouse a threaded shackle to keep the pin from coming loose. This is done by looping mousing wire or a nylon zip tie through the hole in the pin and around the shackle body. For pins that have

858-581: A metal shackle, in many cases better. Soft shackles articulate better, don’t rattle around when not under load, don’t chew up toe rails or beat up masts and decks, don’t hurt when they whack you on the head, are easier to undo and don’t have pins that fall overboard at a critical moment". A modern rope can lift as heavy loads as a steel wire 3 times as thick and much heavier. Metal shackles may be preferred because soft shackles can be cut by sharp edges, burned, or deteriorate in some environments. One disadvantage of soft shackles made of Dyneema and other modern fibers

924-670: A nuisance by local authorities. Kevlar Kevlar (para-aramid) is a strong, heat-resistant synthetic fiber , related to other aramids such as Nomex and Technora . Developed by Stephanie Kwolek at DuPont in 1965, the high-strength material was first used commercially in the early 1970s as a replacement for steel in racing tires. It is typically spun into ropes or fabric sheets that can be used as such, or as an ingredient in composite material components. Kevlar has many applications, ranging from bicycle tires and racing sails to bulletproof vests , all due to its high tensile strength-to-weight ratio ; by this measure it

990-553: A padlock; it is combined with the noun lock , from Old English loc , related to German loch , "hole". There are padlocks dating to the Roman Era, 500 BC – 300 AD . They were known in early times by merchants traveling the ancient trade routes to Asia, including China. Padlocks have been used in Europe since the middle La Tène period , subsequently spreading to the Roman world and

1056-483: A price range much higher than average cost of basketball shoes. It was also used in the laces for the Adidas F50 adiZero Prime football boot. Several companies, including Continental AG , manufacture cycle tires with Kevlar to protect against punctures. Folding-bead bicycle tires, introduced to cycling by Tom Ritchey in 1984, use Kevlar as a bead in place of steel for weight reduction and strength. A side effect of

1122-473: A sailor's harness tether or to attach spinnaker sheets . Note: When this type of shackle is used to release a significant load, it will work rather poorly (hard to release) and is likely to have the pin assembly or the split ring fail. The pin is threaded and one leg of the shackle is tapped . The pin may be captive , which means it is mated to the shackle, usually with a wire. The threads may gall if overtightened or have been corroding in salty air, so

1188-471: A shackle that slid out of the body instead of swinging away. Although machining metal was a method that was available to lock makers since the early 19th century, it was not economically feasible to do so until the very early 20th century when electrical generation and distribution became widespread. Some of the earliest padlocks (c. 1905) that were made from a machined block of cast or extruded metal resemble today's modern padlock. Corbin and Eagle were one of

1254-593: A wider range of uses than padlocks because they have a variable length of the locking mechanism, only limited by the length of the cable. When the cable is bent and passed through the hole, it can be locked to the desired length. A quantitative measure of a padlock's tensile strength and resistance to forced and surreptitious entry can be determined with tests developed by organizations such as ASTM , Sold Secure (United Kingdom), CEN (Europe), and TNO (The Netherlands). Images of closed padlocks (sometimes physical padlocks) are sometimes used to indicate that something

1320-420: Is a fast action fastener which can be implemented single-handedly. It uses a spring-activated locking mechanism to close a hinged shackle, and can be unfastened under load. This is a potential safety hazard, but can also be extremely useful at times. The snap shackle is not as secure as any other form of shackle, but can come in handy for temporary uses or in situations which must be moved or replaced often, such as

1386-869: Is also found as a braid layer used on the outside of hose assemblies, to add protection against sharp objects. Some cellphones (including the Motorola RAZR Family , the Motorola Droid Maxx , OnePlus 2 and Pocophone F1 ) have a Kevlar backplate, chosen over other materials such as carbon fiber due to its resilience and lack of interference with signal transmission. The Kevlar fiber/epoxy matrix composite materials can be used in marine current turbines (MCT) or wind turbines due to their high specific strength and light weight compared to other fibers. Aramid fibers are widely used for reinforcing composite materials, often in combination with carbon fiber and glass fiber . The matrix for high performance composites

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1452-422: Is five times stronger than steel. It is also used to make modern marching drumheads that withstand high impact; and for mooring lines and other underwater applications. A similar fiber called Twaron with the same chemical structure was developed by Akzo in the 1970s; commercial production started in 1986, and Twaron is manufactured by Teijin . Poly-paraphenylene terephthalamide (K29) – branded Kevlar –

1518-412: Is no longer a key in the traditional sense, but is unlocked through mobile phone Bluetooth , near-field communication (NFC), and fingerprint. Unlike active electronic padlocks, passive electronic padlocks do not require electricity which makes their use environment more extensive. The passive electronic lock can be unlocked with an electronic key which needs to be programmed. Steel cable padlocks have

1584-663: Is secure or inaccessible. A widely known example is on the Web , where data in secure transactions is encrypted using public-key cryptography ; some web browsers display a locked padlock icon while using the HTTPS protocol. Love locks are physical padlocks attached to fixtures such as bridges, gates, and monuments by sweethearts to declare their love for each other is permanent. This practice perhaps originated in Serbia . In some popular tourist locations, huge numbers of such padlocks are treated as

1650-409: Is slightly stronger at low temperatures. At higher temperatures the tensile strength is immediately reduced by about 10–20%, and after some hours the strength progressively reduces further. For example: enduring 160 °C (320 °F) for 500 hours, its strength is reduced by about 10%; and enduring 260 °C (500 °F) for 70 hours, its strength is reduced by about 50%. Kevlar is often used in

1716-440: Is their susceptibility to be weakened by heat, also heat caused by friction. It is advisable to subject it to medium level loads for a while to remove any slack that may cause friction heat when loaded to its maximum. The stopping knot of a soft shackle may be a true lover's knot , a diamond knot , a double line celtic button knot or a chinese button knot (ABOK #600, ABOK #601, ABOK #603 doubled as one tail-end reverse-trails

1782-440: Is used in rope and in cable, where the fibers are kept parallel within a polyethylene sleeve. The cables have been used in suspension bridges such as the bridge at Aberfeldy, Scotland . They have also been used to stabilize cracking concrete cooling towers by circumferential application followed by tensioning to close the cracks. Kevlar is widely used as a protective outer sheath for optical fiber cable , as its strength protects

1848-401: Is used to manufacture gloves, sleeves, jackets, chaps and other articles of clothing designed to protect users from cuts, abrasions and heat. Kevlar-based protective gear is often considerably lighter and thinner than equivalent gear made of more traditional materials. It is used for motorcycle safety clothing , especially in the areas featuring padding such as the shoulders and elbows. In

1914-421: Is usually epoxy resin . Typical applications include monocoque bodies for Formula 1 cars, helicopter rotor blades, tennis , table tennis , badminton and squash rackets , kayaks , cricket bats , and field hockey , ice hockey and lacrosse sticks. Kevlar 149, the strongest fiber and most crystalline in structure, is an alternative in certain parts of aircraft construction. The wing leading edge

1980-495: Is usually a resin poured onto the Kevlar to make the head airtight, and a nylon top layer to provide a flat striking surface. This is one of the primary types of marching snare drum heads. Remo 's Falam Slam patch is made with Kevlar and is used to reinforce bass drum heads where the beater strikes. Kevlar is used in the woodwind reeds of Fibracell. The material of these reeds is a composite of aerospace materials designed to duplicate

2046-550: The NA48 experiment at CERN to separate a vacuum vessel from a vessel at nearly atmospheric pressure, both 192 cm (76 in) in diameter. The window has provided vacuum tightness combined with reasonably small amount of material (only 0.3% to 0.4% of radiation length ). Kevlar is a well-known component of personal armor such as combat helmets , ballistic face masks , and ballistic vests . The PASGT helmet and vest that were used by United States military forces used Kevlar as

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2112-874: The National Science and Technology Museum , early Chinese padlocks were mainly " key -operated locks with splitting springs, and partially keyless letter combination locks ". Padlocks were made from bronze, brass, silver, and other materials. The use of bronze was more prevalent for the early Chinese padlocks. Padlocks with spring tine mechanisms have been found in York, England, at the Jorvik Viking settlement, dated 850 AD. Smokehouse locks, designed in England , were formed from wrought iron sheet and employed simple lever and ward mechanisms. These locks afforded little protection against forced and surreptitious entry. Contemporary with

2178-526: The Przeworsk and Chernyakhov cultures . Roman padlocks had a long bent rod attached to the case, and a shorter piece which could be inserted into the case. Przeworsk and Chernyakhov padlocks had a sleeve attached to the case, and a long bent rod which could be inserted into the case and the sleeve. Padlocks have been used in China since the late Eastern Han dynasty (25–220 AD). According to Hong-Sen Yan, director of

2244-455: The 1870s, lock makers realized they could successfully package the same locking mechanism found in cast heart locks into a more economical steel or brass shell instead of having to cast a thick metal body. These lock shells were stamped out of flat metal stock, filled with lever tumblers, and then riveted together. Although more fragile than the cast hearts, these locks were attractive because they cost less. In 1908, Adams & Westlake patented

2310-498: The 1950s. Today, other countries are still manufacturing this style of padlock. Contemporary with the Scandinavian padlock, were the "cast heart" locks, so called because of their shape. A significantly stronger lock than the smokehouse and much more resistant to corrosion than the Scandinavian, the hearts had a lock body sand cast from brass or bronze and a more secure lever mechanism. Heart locks had two prominent characteristics: one

2376-407: The bolt will need to be secured to the shackle body to avoid its loss, usually with a split pin or seizing wire. A more secure version used in crane rigging features the combination of a securing nut (hardware) located alongside the cotter pin. Pin shackles are practical in many rigging applications where the anchor bolt is expected to experience some rotation. As the name implies, a snap shackle

2442-400: The bow's user. To date, the only manufacturer of this type of bow is CodaBow . Kevlar is also presently used as a material for tailcords (a.k.a. tailpiece adjusters), which connect the tailpiece to the endpin of bowed string instruments. Kevlar is sometimes used as a material on marching snare drums. It allows for an extremely high amount of tension, resulting in a cleaner sound. There

2508-487: The cable from damage and kinking. When used in this application it is commonly known by the trademarked name Parafil. Kevlar was used by scientists at Georgia Institute of Technology as a base textile for an experiment in electricity-producing clothing. This was done by weaving zinc oxide nanowires into the fabric. If successful, the new fabric will generate about 80 milliwatts per square meter. A retractable roof of over 60,000 sq ft (5,600 m ) of Kevlar

2574-437: The carcinogenic properties associated with asbestos. Wicks for fire dancing props are made of composite materials with Kevlar in them. Kevlar by itself does not absorb fuel very well, so it is blended with other materials such as fiberglass or cotton . Kevlar's high heat resistance allows the wicks to be reused many times. Kevlar is sometimes used as a substitute for Teflon in some non-stick frying pans. Kevlar fiber

2640-463: The edge of the disc. When locked, the discs passed through cut-outs on the shackle. The key rotated each disk until the notches, placed along the edge of each tumbler in different places, lined up with the shackle, allowing the shackle to slide out of the body. The McWilliams company received a patent for these locks in 1871. The "Scandinavian" design was so successful that JHW Climax & Co. of Newark, New Jersey continued to make these padlocks until

2706-452: The eye around the neck of the button. Padlock Padlocks are portable locks usually with a shackle that may be passed through an opening (such as a chain link , or hasp staple) to prevent use , theft , vandalism or harm . The term padlock is from the late fifteenth century. The prefix pad- is thought to be related to the Latin ped which may refer to the portability of

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2772-438: The field of cryogenics for its low thermal conductivity and high strength relative to other materials for suspension purposes. It is most often used to suspend a paramagnetic salt enclosure from a superconducting magnet mandrel in order to minimize any heat leaks to the paramagnetic material. It is also used as a thermal standoff or structural support where low heat leaks are desired. A thin Kevlar window has been used by

2838-474: The first lock makers to machine a solid block of metal and insert a relatively new pin tumbler mechanism and a sliding shackle into the holes machined into the body. This style of padlock was both strong and easy to manufacture. Many machined body padlocks were designed to be disassembled so that locksmiths could easily fit the locks to a certain key. The machined body padlocks are still very popular today. The process of machining allows many modern padlocks to have

2904-520: The first time. It launched the Elite II Series, with enhancements to its earlier version of basketball shoes by using Kevlar in the anterior as well as the shoe laces . This was done to decrease the elasticity of the tip of the shoe in contrast to the nylon conventionally used, as Kevlar expanded by about 1% against nylon which expanded by about 30%. Shoes in this range included LeBron, HyperDunk and Zoom Kobe VII. However these shoes were launched at

2970-583: The folding bead is a reduction in shelf and floor space needed to display cycle tires in a retail environment, as they are folded and placed in small boxes. Kevlar has also been found to have useful acoustic properties for loudspeaker cones, specifically for bass and mid range drive units. Additionally, Kevlar has been used as a strength member in fiber optic cables such as the ones used for audio data transmissions. Kevlar can be used as an acoustic core on bows for string instruments . Kevlar's physical properties provide strength, flexibility, and stability for

3036-411: The idea developed: "We folded it over a couple of times and shot at it. The bullets didn't go through." In tests, they strapped Kevlar onto anesthetized goats and shot at their hearts, spinal cords, livers and lungs. They monitored the goats' heart rate and blood gas levels to check for lung injuries. After 24 hours, one goat died and the others had wounds that were not life threatening. Shubin received

3102-404: The levers were sub-assembled into a "cartridge" that could be slid into a cast brass body shell. The assembly would remain together by means of two taper pins passed through the shell and cartridge. This design gave the commercial padlock market a serviceable, rekeyable padlock. About twenty years later Yale made another "cartridge" style padlock that employed their famous pin tumbler mechanism and

3168-533: The lock parts in it, was riveted together. This padlock was popular for its low cost and impact-resistant laminated plate design. Today, many lock makers copy this very efficient and successful design. A padlock is composed of a body, shackle , and locking mechanism. The typical shackle is a U-shaped loop of metal (round or square in cross-section) that encompasses what is being secured by the padlock (e.g., chain link or hasp). Generally, most padlock shackles either swing away (typical of older padlocks) or slide out of

3234-401: The middle of the 19th century, "Scandinavian" style locks, or "Polhem locks", invented by the eponymous Swedish inventor Christopher Polhem , became a more secure alternative to the prevailing smokehouse and screw locks. These locks had a cast iron body that was loaded with a stack of rotating disks. Each disk had a central cutout to allow the key to pass through them and two notches cut out on

3300-486: The more expensive hemp . It is one of the main materials used for paraglider suspension lines. It is used as an inner lining for some bicycle tires to prevent punctures. In table tennis , plies of Kevlar are added to custom ply blades, or paddles, in order to increase bounce and reduce weight. Tennis racquets are sometimes strung with Kevlar. It is used in sails for high performance racing boats. In 2013, with advancements in technology, Nike used Kevlar in shoes for

3366-400: The other, emerging tail-ends preferably buried in the opposing main part as it emerges together from the knot for Chinese finger trap attachment). Another preferred stopping knot is a two rope combined wall+crown+wall+crown knot (a two string rose knot ). The latter ones with the added thickness of the returning tail ends have the advantage of less of a sharp curvature at their weakest spot,

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3432-467: The padlock body when in the unlocked position. Less common designs include a straight, circular, or flexible (cable) shackle. Some shackles split apart and come together to lock and unlock. There are two basic types of padlock locking mechanisms: integrated and modular. Integrated locking mechanisms directly engage the padlock's shackle with the tumblers. Examples of integrated locking mechanisms are rotating disks (found in "Scandinavian" style padlocks where

3498-473: The polymer chains in the fiber's direction. Hexamethylphosphoramide (HMPA) was the solvent initially used for the polymerization , but for safety reasons, DuPont replaced it by a solution of N -methyl-pyrrolidone and calcium chloride. As this process had been patented by Akzo (see above) in the production of Twaron , a patent war ensued. Kevlar production is expensive because of the difficulties arising from using concentrated sulfuric acid , needed to keep

3564-547: The properties of other synthetic polymers and fibers such as ultra-high-molecular-weight polyethylene . The presence of salts and certain other impurities, especially calcium , could interfere with the strand interactions and care is taken to avoid inclusion in its production. Kevlar's structure consists of relatively rigid molecules which tend to form mostly planar sheet-like structures rather like silk protein. Kevlar maintains its strength and resilience down to cryogenic temperatures (−196 °C (−320.8 °F)): in fact, it

3630-528: The smokehouse padlocks and originating in the Slavic areas of Europe, "screw key" padlocks opened with a helical key that was threaded into the keyhole . The key pulled the locking bolt open against a strong spring. Padlocks that offered more key variance were the demise of the screw lock. Improved manufacturing methods allowed the manufacture of better padlocks that put an end to the Smokehouse around 1910. Around

3696-466: The sport of fencing it is used in the protective jackets, breeches, plastrons and the bib of the masks. It is increasingly being used in the peto , the padded covering which protects the picadors ' horses in the bullring. Speed skaters also frequently wear an under-layer of Kevlar fabric to prevent potential wounds from skates in the event of a fall or collision. In kyudo , or Japanese archery , it may be used for bow strings , as an alternative to

3762-404: The tumblers or to service the lock. Modular locking mechanism cylinders frequently employ pin , wafer , and disc tumblers . Padlocks with modular mechanisms are usually automatic, or self-locking (that is, the key is not required to lock the padlock) Combination locks do not use keys. Instead, the lock opens when its wheels are lined up correctly to display the correct combination . A padlock

3828-528: The use of a key to lock. The more modern modular locking mechanisms, however, do not directly employ the tumblers to lock the shackle. Instead, they have a plug within the "cylinder" that, with the correct key, turns and allows a mechanism, referred to as a "locking dog" (such as the ball bearings found in American Lock Company padlocks) to retract from notches cut into the shackle. Padlocks with modular locking mechanisms can often be taken apart to change

3894-425: The water-insoluble polymer in solution during its synthesis and spinning . Several grades of Kevlar are available: The ultraviolet component of sunlight degrades and decomposes Kevlar, a problem known as UV degradation , and so it is rarely used outdoors without protection against sunlight. When Kevlar is spun , the resulting fiber has a tensile strength of about 3,620 MPa (525,000 psi) , and

3960-486: The way nature constructs cane reed. Very stiff but sound absorbing Kevlar fibers are suspended in a lightweight resin formulation. Kevlar is sometimes used in structural components of cars, especially high-value performance cars such as the Ferrari F40 . The chopped fiber has been used as a replacement for asbestos in brake pads . Aramids such as Kevlar release less airborne fibres than asbestos brakes and do not have

4026-438: Was "cloudy, opalescent upon being stirred, and of low viscosity " and usually was thrown away. However, Kwolek persuaded the technician, Charles Smullen, who ran the spinneret , to test her solution, and was amazed to find that the fiber did not break, unlike nylon . Her supervisor and her laboratory director understood the significance of her discovery and a new field of polymer chemistry quickly arose. By 1971, modern Kevlar

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4092-520: Was a key part of the design of the Olympic Stadium, Montreal for the 1976 Summer Olympics . It was spectacularly unsuccessful, as it was completed 10 years late and replaced just 10 years later in May 1998 after a series of problems. Kevlar can be found as a reinforcing layer in rubber bellows expansion joints and rubber hoses , for use in high temperature applications, and for its high strength. It

4158-477: Was a spring-loaded cover that pivoted over the keyhole to keep dirt and insects out of the lock that was called a "drop". The other was a point formed at the bottom of the lock so a chain could be attached to the lock body to prevent the lock from getting lost or stolen. Cast heart locks were very popular with railroads for locking switches and cars because of their economical cost and excellent ability to open reliably in dirty, moist, and frozen environments. Around

4224-570: Was introduced. However, Kwolek was not very involved in developing the applications of Kevlar. In 1971, Lester Shubin , who was then the Director of Science and Technology for the National Institute for Law Enforcement and Criminal Justice, suggested using Kevlar to replace nylon in bullet-proof vests. Prior to the introduction of Kevlar, flak jackets made of nylon had provided much more limited protection to users. Shubin later recalled how

4290-455: Was invented by John I. W. Carlson in 1931 (a patent was granted in November 1934) that has both a combination on one side and a key on the other. Electronic padlocks are categorized as either "active" or "passive" electronic padlocks. Active electronic padlocks are divided into rechargeable electronic padlocks and replaceable battery electronic padlocks. The key of this type of electronic padlock

4356-481: Was invented by the Polish-American chemist Stephanie Kwolek while working for DuPont, in anticipation of a gasoline shortage. In 1964, her group began searching for a new lightweight strong fiber to use for light, but strong, tires. The polymers she had been working with, poly-p-phenylene-terephthalate and polybenzamide, formed liquid crystals in solution, something unique to polymers at the time. The solution

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