C1 高級 美國腔 2124 分類 收藏
開始影片後,點擊或框選字幕可以立即查詢單字
字庫載入中…
回報字幕錯誤
Centuries ago, the Inca developed ingenious suits of armor that could flex with the blows of sharp spears and maces, protecting warriors from even the fiercest physical attacks.
These hardy structures were made not from iron or steel, but rather something unexpectedly soft: Cotton.
These thickly woven, layered quilts of cotton could distribute the energy from a blow across a large surface area, shielding warriors without restricting their mobility.
These seemingly contradictory features, strength and flexibility, softness and durability, have their roots in the intricate biology of the nearly invisible cotton fiber.
These fibers begin life deep within a cotton flower, on the surface of a seed.
As many as 16,000 fibers will festoon a single seed, bulging from the seed's surface like miniature water balloons.
Each cotton fiber, no matter how large it grows, is made of just one cell.
That cell has multiple layers of cell wall.
After a few days, the sides of the first layer, called the primary cell wall, stiffen, pushing cell growth in one direction and causing the fiber to elongate.
The fiber elongates quickly for about 16 days.
Then it begins the next stage: strengthening the cell wall.
It does this by making more of the carbohydrate cellulose.
Cellulose will make up 34 percent of the cell wall at this stage and swiftly increases.
This new growth also reinforces the cell wall by going against the grain of the existing wall.
The strengthened wall is more rigid, restricting further growth.
That means if the fiber remodels its walls too early, it will be short, and ultimately make rough, weak fabrics.
But if cell wall strengthening begins too late, the wall won't be sturdy enough, producing fibers that are too weak to hold fabrics together well.
In ideal growing conditions with the right temperature, water, fertilizer, pest control, and light, a cotton fiber can grow up to 3.6 centimeters long with only a 25 micrometer width.
Long, fine fibers can wrap around one another better than shorter, less fine fibers, which means those long, fine fibers make stronger threads that hang together better as fabric.
Cotton with these qualities has diverse uses, from soft textiles to the U.S. dollar bill, which is 75 percent cotton.
The next crucial stage of the cotton fiber's growth begins as it thickens its secondary cell wall by depositing large quantities of cellulose into the secondary layer.
Cellulose goes on to make up over 90 percent of the fiber's weight.
The more cellulose that gets deposited, the denser that secondary layer becomes.
And this determines the strength of the final fiber.
This stage is essential for developing long-lasting material for the likes of, say, a t-shirt.
The garment's capacity to withstand years of washing and wear is largely determined by the density of that secondary cell wall.
On the other hand, its softness is strongly influenced by the length of the fiber, established with the remodeling of the primary wall layer.
Finally, after about 50 days, the fiber is fully grown.
The living matter within the cell dies off, leaving behind only the cellulose.
The dried cotton seed pod, or boll, that surrounds the fibers cracks open, unveiling a burst of several thousand fiber cells in a fluffy mass.
The thread-like fibers we see—thinner than a human hair—are the remains of those dense, dried out walls of cellulose.
Tens of thousands of these fibers spun into yarn will go on to make everything from fabric, to coffee filters, diapers, and fishing nets.
And with the help of modern science, cotton might soon be softer, stronger, and more resilient than ever as researchers investigate how to optimize its growth based on nutrients, weather conditions, and genetics.
The cotton from your favorite t-shirt likely begin its life in America, China or India.
How did they get from there to your bag?
Find out in this video.
提示:點選文章或是影片下面的字幕單字,可以直接快速翻譯喔!

載入中…

載入中…

【TED-Ed】當我「棉」同在一起?為何什麼都有棉花? (Why is cotton in everything? - Michael R. Stiff)

2124 分類 收藏
Seraya 發佈於 2020 年 1 月 24 日    Seraya 翻譯    adam 審核
看更多推薦影片
  1. 1. 單字查詢

    在字幕上選取單字即可即時查詢單字喔!

  2. 2. 單句重複播放

    可重複聽取一句單句,加強聽力!

  3. 3. 使用快速鍵

    使用影片快速鍵,讓學習更有效率!

  4. 4. 關閉語言字幕

    進階版練習可關閉字幕純聽英文哦!

  5. 5. 內嵌播放器

    可以將英文字幕學習播放器內嵌到部落格等地方喔

  6. 6. 展開播放器

    可隱藏右方全文及字典欄位,觀看影片更舒適!

  1. 英文聽力測驗

    挑戰字幕英文聽力測驗!

  1. 點擊展開筆記本讓你看的更舒服

  1. UrbanDictionary 俚語字典整合查詢。一般字典查詢不到你滿意的解譯,不妨使用「俚語字典」,或許會讓你有滿意的答案喔