Why is cotton in everything? - Michael R. Stiff

2,267,357 views ・ 2020-01-23

TED-Ed


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翻译人员: Jiasi Hao 校对人员: Harper Chang
00:06
Centuries ago, the Inca developed ingenuous suits of armor
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几个世纪前, 印加人发明了一种独特的盔甲,
00:11
that could flex with the blows of sharp spears and maces,
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这种盔甲能够随着锋利长矛 和狼牙棒的打击而弯曲,
00:15
protecting warriors from even the fiercest physical attacks.
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从而保护士兵免受于 哪怕是最猛烈的物理攻击。
00:20
These hardy structures were made not from iron or steel,
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这些坚固的结构 并不是由铁或钢制成的,
00:24
but rather something unexpectedly soft: cotton.
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而是由一个极其柔软的材料制成: 棉花。
00:28
These thickly woven, layered quilts of cotton
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这些厚厚编织、层层堆叠的棉花
00:31
could distribute the energy from a blow across a large surface area,
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能够将击打的力量 分散在一块较大的表面积,
00:36
shielding warriors without restricting their mobility.
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因此在保护士兵的同时, 也不会局限他们的活动能力。
00:40
These seemingly contradictory features—
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这些看似相互矛盾的特性——
00:42
strength and flexibility, softness and durability—
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强硬度和灵活性、 柔软度和耐用性,
00:46
have their roots in the intricate biology of the nearly invisible cotton fiber.
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来源于复杂生物学中 肉眼几乎无法看见的棉纤维。
00:52
These fibers begin life deep within a cotton flower,
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这些纤维的生命始于
棉花花朵表面的种籽。
00:56
on the surface of a seed.
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00:58
As many as 16,000 fibers will festoon a single seed,
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一个种子中能被 多达 16,000 根的纤维充斥,
01:03
bulging from the seed’s surface like miniature water balloons.
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宛如迷你水气球, 从种子表面向外膨胀。
01:07
Each cotton fiber, no matter how large it grows,
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不论长成多大个, 每根棉纤维
01:10
is made of just one cell.
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01:13
That cell has multiple layers of cell wall.
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这种细胞有好几层细胞壁。
01:16
After a few days, the sides of the first layer,
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几天后,第一层细胞壁,
亦称为初生细胞壁,
01:20
called the primary cell wall,
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01:22
stiffen, pushing cell growth in one direction
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变硬,向一个方向推动细胞生长,
01:25
and causing the fiber to elongate.
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从而使纤维被拉长。
01:28
The fiber elongates quickly for about 16 days.
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在 16 天左右的时间, 纤维被快速拉长。
01:32
Then it begins the next stage: strengthening the cell wall.
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其后,它便进入下一个生长阶段: 强化细胞壁。
01:36
It does this by making more of the carbohydrate cellulose.
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这是通过产生更多的 碳水化合物纤维素来完成的。
01:40
Cellulose will make up 34% of the cell wall at this stage
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在这一阶段,该纤维素 占细胞壁构成成分的 34%,
且占比仍旧快速上升。
01:45
and swiftly increases.
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这一生长促使 对现有细胞壁纹理的抵触,
01:47
This new growth also reinforces the cell wall
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01:50
by going against the grain of the existing wall.
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因此也强化了细胞壁。
01:53
The strengthened wall is more rigid, restricting further growth.
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被强化的细胞壁变得更加坚硬, 会限制其进一步生长。
这意味着如果纤维素过早 改变细胞壁结构,
01:58
That means if the fiber remodels its walls too early,
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棉花纤维就会很短,
02:01
it will be short,
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02:02
and ultimately make rough, weak fabrics.
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最终只能产出粗糙且易破的布料。
02:05
But if cell wall strengthening begins too late,
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但如果细胞壁强化阶段开始得过晚,
02:08
the wall won’t be sturdy enough—
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那层细胞壁就会不够坚固,
02:10
producing fibers that are too weak to hold fabrics together well.
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生成的纤维会过为柔弱, 难以很好地将布料合成。
理想的生长条件是:
02:15
In ideal growing conditions—
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适宜的温度、水、肥料、 害虫防治,还有光线。
02:17
with the right temperature, water, fertilizer, pest control, and light—
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02:23
a cotton fiber can grow up to 3.6 centimeters long
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这样,一根棉纤维 可以生长至长 3.6 厘米,
02:28
with only a 25 micrometer width.
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宽仅为 25 微米。
细长且高品质的纤维 相较于短且质量较次的纤维,
02:32
Long, fine fibers can wrap around one another
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02:35
better than shorter, less fine fibers,
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能更好地缠绕彼此。
02:37
which means those long, fine fibers make stronger threads
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这表示那些细长且高品质的 纤维能够制造出更坚韧的棉线,
02:41
that hang together better as fabric.
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编织成更好的面料。
02:44
Cotton with these qualities has diverse uses—
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因为棉花的特性, 它们被广泛使用,
02:47
from soft textiles to the U.S. dollar bill,
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从柔软的纺织品到美元纸钞——
内含 75% 的棉成分。
02:50
which is 75% cotton.
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在下一个棉花纤维 成长的关键阶段,
02:53
The next crucial stage of the cotton fiber’s growth
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大量纤维素在次生细胞壁内
02:56
begins as it thickens its secondary cell wall
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02:59
by depositing large quantities of cellulose into the secondary layer.
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堆积并从而强化细胞壁。
纤维素的重量占比上升, 超过纤维净重的 90% 。
03:04
Cellulose goes on to make up over 90% of the fiber’s weight.
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03:08
The more cellulose that gets deposited,
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越多纤维素堆积,
03:10
the denser that secondary layer becomes—
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次生细胞壁 就变得更紧实——
03:13
and this determines the strength of the final fiber.
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这决定了最终棉花纤维的强度。
03:16
This stage is essential for developing long-lasting material
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对于后阶段是否能产出 经久耐用的材料,比如 T 恤,
这一生长阶段至关重要。
03:20
for the likes of, say, a t-shirt.
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03:22
The garment’s capacity to withstand years of washing and wear
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一件成衣经受多年穿洗的能力
03:26
is largely determined by the density of that secondary cell wall.
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很大程度上 取决于次生细胞壁的密度。
03:30
On the other hand,
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从另一方面来说,
03:31
its softness is strongly influenced by the length of the fiber,
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成衣的柔软性 主要受到棉纤维长度的影响,
03:35
established with the remodeling of the primary wall layer.
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而纤维长度是由 初生细胞壁重塑的。
03:40
Finally, after about 50 days, the fiber is fully grown.
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终于,在大约 50 天后, 纤维生长完毕。
03:44
The living matter within the cell dies off,
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细胞死亡,
03:47
leaving behind only the cellulose.
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只留下纤维素。
03:50
The dried cotton seed pod, or boll, that surrounds the fibers cracks open,
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包裹纤维的干燥的 棉籽荚,也叫棉铃裂开了,
03:55
unveiling a burst of several thousand fiber cells in a fluffy mass.
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露出一簇簇柔软蓬松的纤维细胞。
04:01
The thread-like fibers we see— thinner than a human hair—
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我们看到的丝状纤维—— 比人类毛发还要细——
04:05
are the remains of those dense, dried out walls of cellulose.
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是那些紧实干燥的 纤维素壁(原细胞壁)的残留物。
04:09
Tens of thousands of these fibers spun into yarn
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数以万计的这些纤维被纺织成纱线,
随后继续加工生产为各种东西, 从面料织物,到咖啡过滤器、尿布,
04:13
will go on to make everything from fabric, to coffee filters, diapers,
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04:17
and fishing nets.
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还有渔网。
04:19
And with the help of modern science,
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利用现代科学的帮助,
04:21
cotton might soon be softer, stronger, and more resilient than ever
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调整营养、气候和基因等学科因素,
科研人员正在研究如何优化棉花生长。
04:26
as researchers investigate how to optimize its growth
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04:29
based on nutrients, weather conditions, and genetics.
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棉花可能在不久将来 变得更柔软、更坚硬,以及更有韧性。
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