Silk

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Silk is a natural protein fiber, some shapes that can be woven into textiles. The silk protein fibers consist primarily of fibroin and are produced by certain insect larvae to form a cocoon. The most famous silk is obtained from the cocoon of the mulberry silkworm larvae Bombyx mori which is preserved in captivity (sericulture). The appearance of silk sparkles due to the prismal structure is like a triangle of silk fibers, which allows the silk fabric to refract the incoming light at different angles, resulting in different colors.

Silk is produced by some insects, such as silkworms but generally only silkworms that have been used for textile fabrication. There are several studies on other types of silk, which differ at the molecular level. Silk is primarily produced by insect larvae undergoing complete metamorphosis, but some insects such as web crawlers and crickets generate silk throughout their lives. Silk production also occurs in Hymenoptera (bees, wasps, and ants), silverfish, dragonfly, thrips, aphis, beetles, lacewings, fleas, flies, and pests. Other types of arthropods produce silk, especially various arachnids such as spiders.

Video Silk

Etymology

The word sutra comes from Old English: sioloc , from Ancient Greece: ? ?????? , translit.Ãƒ, s? rikÃƒÆ'Ã‚Â³s , "sutra", finally from an Asian source - compare Mandarin s? "silk", Manchurian sirghe , Mongolian sirkek .

Maps Silk

History

Wild silk

Several types of wild silk, which are produced by caterpillars other than mulberry silkworms, have been known and used in China, South Asia, and Europe since ancient times. However, the scale of production is always much smaller than for the cultivated sutras. There are several reasons for this: first, they differ from the domesticated varieties and colors and are therefore less uniform; second, cocoons that congregate in the wild usually have pupae emerging from them before being discovered so that the silk threads that form the cocoon have torn to be shorter; and thirdly, many wild cocoons are covered with a layer of minerals that prevent attempts to take long silk strands. Thus, the only way to get a suitable silk to be spun into textiles in areas where commercial silk is not cultivated is by boring and labor-intensive carding.

Commercial silk comes from a silkworm cocoon, which is grown to produce white silk threads without minerals on the surface. The cocoon is killed by dipping it in boiling water before the adult moth appears or by stabbing it with a needle. All these factors contribute to the whole cocoon's ability to break down as a thread, allowing a much stronger fabric to be woven from silk. Wild silk also tends to be more difficult to color than silk from cultivated silkworms. A technique known as demineralization allows the mineral layers around the cocoons of wild silk moths to be removed, leaving only the color variability as a barrier to creating a commercial silk industry based on wild silk in parts of the world where wild silk moths flourish, as in Africa and South America.

The genetic modification of the cultivated silk worm is used to facilitate the production of more useful types of silk.

China

Silk was first developed in ancient China.

The earliest example of the sutra has been found in the tomb at the Jiahu Neolithic site in Henan, and dates back 8,500 years. The silk cloth from 3630 BC was used as a wrapper for a child's body from Yangshao cultural site at Qingtaicun in Xingyang, Henan.

The legend gives credit for developing silk to a Chinese queen, Leizu (Hsi-Ling-Shih, Lei-Tzu). Silk was originally reserved for the Chinese Emperors for their own use and gifts for others, but spread gradually through Chinese culture and commerce both geographically and socially, and then to many areas of Asia. Due to its texture and luster, silk quickly became a popular luxury fabric in many areas accessible to Chinese merchants. Silk is in great demand, and became the principal of pre-industrial international trade. In July 2007, archaeologists discovered intricate woven and dyed silk textiles in a tomb in Jiangxi province, dated to the Eastern Zhou Dynasty some 2,500 years ago. Although historians have suspected the long history of the formative textile industry in ancient China, the discovery of this silk textile using the "intricate technique" of weaving and coloring provides direct evidence for silk dated before the invention of Mawangdui and other sutras originating from the Han Dynasty (202 BC-220 M).

The sutras are described in the chapter on mulberry planting by Si Shengzhi of West Han (206 BC - 9 AD). There is a survival calendar for silk production in East Han documents (25-220 AD). Two other works known to the silk from the Han period are gone. The first proof of long-distance silk trade is the silk findings in the Egyptian mummy hair of the 21st dynasty, c.1070 BC. The silk trade reaches as far as the subcontinent of India, the Middle East, Europe, and North Africa. This trade is so vast that a series of major trade routes between Europe and Asia came to be known as the Silk Road.

The Emperor of China sought to keep knowledge of the secrets of sericulture to defend the Chinese monopoly. Nonetheless sericulture reached Korea with the help of technology from China around 200 BC, the ancient Khotan Kingdom in 50 AD, and India in 140 AD.

In the ancient era, silk from China was the most profitable and sought after luxury traded throughout the Eurasian continent, and many civilizations, such as ancient Persia, benefited economically from commerce.

Chinese silk-making process

India

Silk has a long history in India. It is known as Resham in eastern and northern India, and Pattu in southern India. Recent archaeological findings in Harappa and Chanhu-daro show that sericulture, using wild silk threads from native caterpillar species, existed in South Asia during the Indus Valley Indigenous Civilization (now in Pakistan) in pairs between 2450 BC and 2000 BC, while "hard and evidence fast "for silk production in China dates back to about 2570 BC. Shelagh Vainker, a silk expert at the Ashmolean Museum in Oxford, who saw evidence for silk production in China "significantly earlier" from 2500-2000 BC, points out, "people from Indus civilizations either harvest silkworm cocoons or trade with people people who do it, and they know a lot about the sutras. "

India is the second largest silk producer in the world after China. About 97% of raw mulberry sutras come from five Indian states, namely, Andhra Pradesh, Karnataka, Jammu and Kashmir, Tamil Nadu and West Bengal. North Bangalore, the upcoming site of Ramanagara and Mysore's "Silk City" worth $ 20 million, contributes to the majority of silk production in Karnataka.

In Tamil Nadu, mulberry cultivation is concentrated in the districts of Coimbatore, Erode, Tiruppur, Salem and Dharmapuri. Hyderabad, Andhra Pradesh, and Gobichettipalayam, Tamil Nadu, is the first location to have an automatic silk milling unit in India.

India is also the largest silk consumer in the world. The tradition of wearing silk saris for weddings and other lavish ceremonies is a habit in Assam and the southern part of India. Sutra is considered a symbol of the kingdom, and, historically, silk is used mainly by the upper classes. The silk and sari garments produced in Kanchipuram, Pochampally, Dharmavaram, Mysore, Arani to the south, Banaras to the north, Bhagalpur and Murshidabad to the east are well known. In northeastern Assam state, three different types of silk are produced, collectively called Assam sutras: Muga, Eri and Pat sutras. Muga, gold silk, and Eri are produced by the original silkworm only for Assam.

Thai

Silk is produced throughout the year in Thailand by two types of silkworms, Bombycidae and wild saturniidae. Most of the production is after the rice harvest in the southern and northeastern part of the country. Women traditionally weave silk in the hands of looms and give skill to their daughters, because weaving is considered a sign of maturity and eligibility for marriage. Thai silk textiles often use intricate patterns in different colors and styles. Most parts of Thailand have their own distinctive silk. Single filament yarns are too thin for self-use so women combine many threads to produce thicker, more useful fibers. They do this by pulling the yarn to the wooden shaft to produce a uniform strand of raw silk. This process takes about 40 hours to produce half a kilogram of silk. Many local operations use machines shaken for this task, but some silk threads are still rolled up. The difference is that hand-rolled yarns produce three levels of silk: two fine grades ideal for light fabrics, and thicker grades for heavier materials.

Silk fabrics soaked in very cold water and bleached before immersion to remove natural yellow dye from Thai silk thread. To do this, the spindle of silk thread is immersed in a large tub of hydrogen peroxide. After being washed and dried, the silk is woven in a traditional hand-operated loom.

Bangladesh

Rajshahi Division of north Bangladesh is the center of the country silk industry. There are three types of silk produced in this region: mulberry, endi and tassar. The Bengali sutra is the main item of international trade for centuries. It was known as the Ganges silk in medieval Europe. Bengal is a leading silk exporter between the 16th and 19th centuries.

Ancient Mediterranean

In Odyssey, 19.233, when Odysseus, while pretending to be someone else, was asked by Penelope about her husband's clothes, he said that he wore a "shimmering shirt like dried onion skin" (varies with translation, translation literally here) that can refer to the quality of the sparkling silk fabric. Aristotle writes of Coa vestis , a wild silk textile from Kos. Marine silk from certain large sea shells is also appreciated. The Roman Empire knew and traded in silk, and Chinese silk was a luxury with the highest prices imported by them. During the reign of Tiberius emperor, a luxury law was passed that prohibited men wearing silk clothes, but this proved ineffective. The Augusta Historia mentions that the 3rd century emperor, Elagabalus, was the first Romans to wear pure silk clothes, whereas his habit of using silk/cotton or silk/linen blends. Despite the popularity of silk, the secret of silk-making only reached Europe around AD 550, through the Byzantine Empire. Legend has it that monks working for the Emperor Justinian I smuggled silkworm eggs into Constantinople using a vacuum from China. All of the high-quality looms and weavers are located within the Great Palace complex in Constantinople, and the fabric produced is used in imperial robes or diplomacy, as a gift to foreign officials. The rest is sold at very high prices.

Middle East

In the Torah, a red cloth called in Hebrew "sheni tola'at" ??? ????? - literally "crimson of the worm" - described as being used in purification ceremonies, such as those following leprosy (Leviticus 14), in addition to cedar and hyssop (za'atar). Leading scientists and medieval translators of Jewish sources and Bible books into Arabic, Rabbi Saadia Gaon, translate this phrase explicitly as "red silk" - ???? ???? ???? ????.

In Islamic teachings, Muslim men are forbidden to wear silk. Many religious jurists believe that the reason behind the ban lies in avoiding clothes for men who can be considered feminine or luxurious. There is a dispute over the number of silk fabrics may consist of (for example, whether a small piece of decorative silk on a cotton cotton is allowed or not) for it to be lawful for men to wear, but the dominant opinion of most Muslim scholars is that the use of silk by men banned. Modern clothing has raised a number of issues, including, for example, the ability to wear silk ties, which are masculine clothing items.

Although there is a ban on silk for men, silk retains its popularity in the Islamic world because of its ability for women, and because of the presence of non-Muslim communities. Moor Muslims brought silk with them to Spain during the conquest of the Iberian Peninsula.

Medieval and modern Europe

Italy was the most important silk producer during the Middle Ages. The first center to introduce silk production to Italy was the city of Catanzaro during the 11th century in the region of Calabria. The Catanzaro Sutra supplies almost all of Europe and is sold in large markets in the port of Reggio Calabria, to Spanish merchants, Venetians, Genovese and the Netherlands. Catanzaro became the world's lace capital with a huge silkworm breeding facility that produces all the ropes and linen used in the Vatican. The city is famous in the world for its fabulous silk, velvet, damask and brocade making.

Another important center is the Italian city of Lucca in which most of it is financed through silk production and silk trade, beginning in the 12th century. Other Italian cities involved in silk production are Genoa, Venice, and Florence.

The Silk Exchange in Valencia from the fifteenth century - where earlier in 1348 also perval was traded as a kind of silk - illustrating the strength and richness of one of the great Mediterranean trading cities.

Silk was produced and exported from the provinces of Granada, Spain, especially the Alpujarras region, until Moriscos, whose industry, was expelled from Granada in 1571.

Since the 15th century, silk production in France has centered around the city of Lyon where many mechanical tools for mass production were first introduced in the 17th century.

James I sought to build silk production in England, bought and planted 100,000 mulberry trees, some on land adjacent to Hampton Court Palace, but they were a species that did not fit in with the silk worm, and the attempt failed. In 1732 John Guardivaglio founded a silk throwing company at the Logwood plant in Stockport; in 1744, Burton Mill was founded in Macclesfield; and at 1753 the Old Mill was built in Congleton. These three cities remained the center of the UK silk throw industry until the silk throwing was replaced by spinning silk waste. The British company also established a silk filament in Cyprus in 1928. In England in the mid-20th century, raw silk was produced at Lullingstone Castle in Kent. Silkworms were raised and rolled under the direction of Zoe Lady Hart Dyke, then moved to Ayot St Lawrence in Hertfordshire in 1956.

North America

King James I introduced the growing sutras to the American colonies around 1619, as if to prevent tobacco planting. The Shaker in Kentucky adopted this exercise. In the 19th century a new effort in the silk industry began with European-born workers in Paterson, New Jersey, and the city became a silk center in the United States. Manchester, Connecticut emerged as the center of the silk industry in America from the late 19th to mid 20th century. The Cheney Brothers Historic District features a refurbished factory as an apartment and includes a nearby museum.

World War II disrupted the silk trade of Asia, and the price of silk increased dramatically. The US industry started looking for replacements, which led to the use of synthetics such as nylon. Synthetic silk has also been made from lyocell, a type of cellulose fiber, and is often difficult to distinguish from native silk (see more spider silk on synthetic silk).

Malaysia

In Terengganu, now part of Malaysia, the second generation of silkworms has been imported since 1764 for the country's silk textile industry, especially songket. However, since the 1980s, Malaysia was no longer involved in sericulture but planted mulberry trees.

Vietnamese

In Vietnamese legend, silk appeared in the sixth dynasty HÃƒÆ'Ã‚Â¹ng V ?? ng.

Seidentraum - silk fabric organic non-violent Ahimsa bioseide ...

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Production process

The silk production process is known as sericulture. The whole process of silk production can be divided into several steps that are usually handled by different entities. Raw silk extraction begins by cultivating silkworms on mulberry leaves. Once the worms begin to pupae in their cocoon, these are dissolved in boiling water for individual long fibers to be extracted and put into a spinning roll.

To produce 1 kg of silk, 104 kg of mulberry leaf should be eaten by 3000 silkworms. It takes about 5000 silkworms to make pure silk kimono. Major silk producers are China (54%) and India (14%). Other statistics:

The environmental impact of silk production has great potential when compared to other natural fibers. Assessment of the life cycle of Indian silk production indicates that the production process has a large carbon and water footprint, mainly due to the fact that it is fiber derived from animals and more inputs such as fertilizer and water are required per unit of fiber produced.

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Properties

Physical properties

The silk fibers of the Bombyx mori caterpillar have a triangular cross section with rounded corners, 5-10 m wide. The fibroin-heavy chain consists mainly of beta-sheets, due to the order of repetition of 59-mer amino acids with some variation. The average surface of the fibrils reflects light in many corners, giving the silk a natural glow. The cross-section of other silkworms may vary in shape and diameter: such as the crescent moon for Anaphe and long slices for tussah . Silkworm fibers are naturally extruded from two silkworm glands as a pair of primary filaments (brin), attached to each other, with sericin proteins that act like glue, to form a bave. Bave diameter for tussah silk can reach 65 m. See references cited for cross-sectional SEM photographs.

Silk has a smooth and soft texture that is not slippery, unlike many synthetic fibers.

Silk is one of the strongest natural fibers, but loses up to 20% of its strength when wet. It has a good moisture return of 11%. The elasticity is moderate to poor: if it extends even in small quantities, it remains stretched. It can weaken if exposed to too much sun. It may also be attacked by insects, especially if left dirty.

One example of a durable silk trait on top of other fabrics is shown by the restoration of the 1840 silk garb from the wreckage of 1782: 'The most durable article found is silk; for besides pieces of robes and lace, a pair of black satin trousers, and a large satin vest with flap, stand, which is perfectly silk, but the lining is completely gone... from the threads given way... No clothing from wool fabric found. '

Silk is a poor conductor of electricity and thus susceptible to static cling. Silk has high emissivity for infrared light, making it feel cool to touch.

Unwashed silk chiffs can shrink to 8% due to loosening of the fiber macro structure, so silk should be washed before garment construction, or cleaned dry. Dry cleaning may still shrink the chiffon up to 4%. Sometimes, this shrinkage can be reversed by steaming gently with a press cloth. There is virtually no gradual shrinkage or depreciation due to molecular level deformation.

Natural and synthetic silk is known to manifest piezoelectric properties in proteins, probably because of its molecular structure.

Silkworm silk is used as a standard for denier, linear density measurement on fiber. Silkworm silk therefore has a linear density of about 1 nest, or 1.1 dtex.

Chemical Properties

Silk emitted by silkworms consists of two main proteins, sericin and fibroin, fibroin being the structural center of silk, and the serecin becomes the sticky material around it. Fibroin consists of the amino acid Gly-Ser-Gly-Ala-Gly-Ala and forms a pleated beta sheet. Hydrogen bonds are formed between chains, and side chains are formed above and below the plane of the hydrogen bonding network.

The high proportion (50%) of glycine allows strict packing. This is because the glycine R group is only hydrogen and is not sterically restricted. The addition of alanine and serine makes the fiber strong and resistant to solving. This tensile strength is due to the many interceded hydrogen bonds, and when stretching forces are applied to these many bonds and they do not break.

Silk is resistant to most mineral acids, except sulfuric acid, which dissolves them. It is yellowed by sweat. Chlorine bleach will also destroy the silk fabric.

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Variant

Fiber Silk Regeneration

RSF is produced by silkworm cocoons, leaving the structure of the molecule intact. The silk fibers dissolve into a yarn-like structure known as microfibrils. The resulting solution is extruded through a small opening, causing the microfibrils to recombine into a single fiber. The resulting material is reportedly twice as stiffer than silk.

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Apps

Clothing

Silk absorbent makes it comfortable to wear in warm weather and when active. Its low conductivity makes warm air close to the skin during cold weather. It is often used for clothing such as shirts, ties, blouses, formal wear, high fashion clothing, upholstery, underwear, pajamas, robes, clothes, sun dresses, and Eastern folk costumes. For practical use, silk is excellent as a protective clothing from many biting insects that usually puncture clothes, such as mosquitoes and horse riding.

Fabrics often made of silk include charmeuse, habutai, chiffon, taffeta, crepe de chine, dupioni, noil, tussah, and shantung, among others.

Furniture

The attractive and hanging silk luster makes it suitable for many furniture applications. These are used for coatings, wall coverings, window treatments (if mixed with other fibers), carpets, beds and wall hangings.

Industry

Silk has many industrial and commercial uses, such as parachutes, bicycle tires, filler quilts and artillery munitions bags.

Medicine

The special fabrication process removes the outer sericin layer from the silk, which makes it suitable as a non-absorbable surgical sutura. This process has also recently led to the introduction of specialist silk underwear, which has been used for skin conditions including eczema. New uses and manufacturing techniques have been found for silk to make everything from disposable cups to drug delivery systems and holograms.

Biomaterial

Silk has been considered a luxury textile since 3630 BC. However, it began to function as well as biomedical materials for stitches in operations a few decades ago. In the last 30 years, it has been widely studied and used as a biomaterial, which refers to the material used for medical applications in organisms, due to its excellent properties, including exceptional mechanical properties, comparative biocompatibility, melodic degradation rate in vitro and in vivo , it is easy to load mobile growth factors (eg BMP-2), and the ability to be processed into several other formats such as films, gels, particles, and scaffolds. The silk of Bombyx mori , a type of silkworm, is the most studied silk.

The sutra derived from Bombyx mori is generally made of two parts: fibroin fiber silk containing 25kDa light chain and heavy chain 350kDa (or 390kDa) connected by single disulfide bond and glue such as protein, sericin, consisting of 25 to 30 percent by weight. Silk fibroin contains a hydrophobic Beta block, interrupted by a small hydrophilic group. And the beta sheets contribute a lot to the high mechanical strength of the silk fibers, which reach 740 MPa, dozens of times of poly (lactic acid) and hundreds of times the collagen. This impressive mechanical strength has made silk fibroin extremely competitive for applications in biomaterials. Indeed, silk fibers have found their way into engineering tendon tissue, where mechanical properties are essential. In addition, the mechanical properties of silk from various types of silkworms vary widely, which gives more options for their use in tissue engineering.

Most products are made from weak and fragile regeneration silk, with only ~ 1-2% of the original mechanical strength of silk fibers due to the absence of appropriate secondary and hierarchical structures,

Biocompatibility

Biocompatibility, ie the ability to level what silk will cause the immune response, is clearly an important issue for biomaterials. Biocompatibility of silk emerged during its increasing clinical use. Indeed, wax or silicon is commonly used as a coating to avoid fraying and potential immune responses when silk fibers function as stitching materials. Despite the lack of detailed characterization of silk fibers, such as the extent of sericin removal, the surface chemical properties of the coating material, and the processes used, make it difficult to determine the real immune response of silk fibers in the literature, it is generally believed that sericin is the major cause of the immune response. Thus, the removal of sericin is an important step to ensure biocompatibility in the application of silk biomaterials. However, further studies failed to demonstrate clearly the contribution of sericin to the inflammatory response based on isolated sericin and sericin biomaterials. In addition, silk fibroin showed an inflammatory response similar to that in vitro plastic tissue culture when assessed with human mesenchymal stem cells (hMSCs) or lower than collagen and PLA when planting MSC mice with silk fibroin film in vivo. Thus, appropriate degumming and sterilization will ensure the biocompatibility of silk fibroin, which is further validated by in vivo experiments in rats and pigs. There are still concerns about the long-term safety of silk-based biomaterials in the human body, in contrast to these promising results. Although silk sutures work well, they exist and interact in limited periods depending on wound recovery (several weeks), much shorter than in tissue engineering. Other concerns arise from biodegradation because the biocompatibility of silk fibroin does not necessarily guarantee the biocompatibility of decomposed products. In fact, different immune response rates and diseases have been triggered by degraded fibroin products.

Biodegradability

Biodegradability (also known as biodegradation) - the ability to be disintegrated by biological approaches, including bacteria, fungi, and cells - is another important property of current biomaterials. Biodegradable materials can minimize patient pain from surgery, especially in tissue engineering, no need surgery to lift scaffold implants. Wang et al. showed in vivo degradation of sutra through aqueous 3-D scaffolds implanted into Lewis mice. Enzymes are the means used to achieve silk degradation in vitro. Protease XIV of Streptomyces griseus and -chymotrypsin from bovine pancreases are two popular enzymes for silk degradation. In addition, gamma radiation, as well as cell metabolism, can also regulate silk degradation.

Compared to synthetic biomaterials such as polyglycols and polylactides, silk is clearly advantageous in some aspects of biodegradation. Acid degradation products of polyglycides and polylactides will decrease the pH of the surrounding environment and thus affect cell metabolism, which is not a problem for silk. In addition, silk material can maintain strength during the desired period from week to month as required by mediating content from beta sheets.

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Cultivation

Silk moths lay eggs on specially prepared paper. Hatching eggs and caterpillars (silkworms) are given fresh mulberry leaves. After about 35 days and 4 times the mollus, the caterpillars are 10,000 times heavier than when they hatch and are ready to start turning the cocoon. A straw frame is placed on a caterpillar tray, and each caterpillar begins to rotate the cocoon by moving its head in a pattern. The two glands produce liquid silk and force through the opening in the head called the spinneret. Liquid silk coated sericin, water-soluble gum, and hardened when in contact with air. In 2-3 days, the caterpillar rotates about 1 mile from the filament and is completely encased in a cocoon. The silk farmers then heat the cocoon to kill them, causing some people to morpheme into moths to breed the next generation of caterpillars. The harvested cocoon is then soaked in boiling water to soften the sericin that holds the silk fibers together in a cocoon. The fibers are then removed to produce a continuous thread. Because one thread is too delicate and fragile for commercial use, anywhere from three to ten strands is turned together to form a silk thread.

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Animal rights

When the process of harvesting the silk from a cocoon kills the larvae by boiling it, sericulture has been criticized by welfare and animal rights activists. Mohandas Gandhi is very critical of the production of silk based on Ahimsa's philosophy which led to the promotion of cotton and silk Ahimsa, a kind of wild silk made from wild and semi-wild silk moths.

Because silk cultivation kills silkworms, it may be painful, People for the Ethical Treatment of Animals (PETA) encourage people not to buy silk items.

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References

6 DIY Hacks That Tell You How to Remove Water Stains from Silk

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Source cited

Hill, John E. 2004. Western Society of WeilÃƒÆ'Ã‚Â¼e ?? by Yu Huan ?? : Chinese Account of the Third Century Composed between 239 and 265 AD. English annotated translation draft. Appendix E.
Magie, David. 1924. The Historia of Augusta Life of Heliogabalus . Loeb Classical Texts No. 140: Harvard University Press.ISBNÃƒ, 978-0674991552.

src: www.salvatori.it

External links

Sutra reference by Roman and Byzantine writers
A series of maps depicting global silk trade
Traditional silk history in martial arts uniform
Silkworm cultivation in classrooms for educational purposes (with photos)
New thread in insect silk fabric | physorg.com

Source of the article : Wikipedia

Silk

Senin, 18 Juni 2018

Silk

Video Silk

Etymology

Maps Silk