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喜欢科学,偏爱自然科学。也喜欢技术,儿时喜围观打锡壶的和锔盆锔锅的。当过工人,当过兵,第二故乡是湖南、广西和广东。

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3D打印鲨鱼皮  

2014-07-07 10:50:12|  分类: 科学与技术 |  标签: |举报 |字号 订阅

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(1)

以往你如果想用一块鲨鱼皮来作研究的话,就不得不去抓一条鲨鱼。不过科学家们解决了这个问题,他们是用3D打印来代替的。

(25m35s)

Now, previously if you wanted a piece of shark skin to study we’d have to go and catch one. But scientists have solved that though by working out how to 3D print it instead.

(2)

这是美国哈佛大学的一个小组,他们通过3D打印的方式制造出一种人工版的鲨鱼皮。而且他们已经把它放入一个水箱中进行试验,以期了解更多鲨鱼如何游泳和它们的皮肤结构是如何让它们游得更快的。

——普通的鲨鱼皮是什么样?

鲨鱼不像其他鱼,它们有鱼鳞不过不是你见过的大而光亮的鱼鳞,而是许多几乎是金字塔形状的非常非常微小的,只是1毫米的若干分之一的小鳞片,称为肤齿。它们就像是粘在鲨鱼皮的外面,实际上鲨鱼皮摸上去非常粗糙。它们据认为能减少阻力,它们在水中能产生一种涡流,帮助鲨鱼游得更快。然而人们并不真正了解它在物理学意义上是如何起作用的,不了解为什么这些几乎如小钉子一般的东西在皮肤上就能帮助鲨鱼游得更快。

(28m59s)

This is a group at Harvard University in the US who has created an artificial sort of version of shark’s skin by 3D printing it. And they’ve been putting that in a tank of water and using it to try and learn more about how sharks swim and how the structure of their skin makes them swim faster.

-- What is normal shark skin like?

Sharks aren’t like other fish. They have scales but they are not big shiny scales like you see. It’s got these almost pyramid-shaped tiny, tiny, tiny fraction of a millimeter little scales called denticles that the sort of, stick out, it’s actually very rough to the touches in the shark’s skin. These kind of reduce drag and they think create a kind of vortex in the water and that helps the shark swim faster. But they don’t really, people don’t really know what’s going on in terms of the precise physics and why having all these tiny little spikes almost helps a shark swim faster.

(3)

他们使用了一片真的鲨鱼皮,用它在一台计算机上建立了一个模型,然后用这个模型作为3D打印机的样本。它制造出的皮肤就像一块非常柔韧可弯曲的如同皮肤的塑料,上面附着了这些硬得多的鱼鳞。这就是他们在后来在水箱试验中所用的鲨鱼皮。你可能会说,唉呀,为什么不用真鲨鱼皮呢?就用真鲨鱼皮来作试验不好吗?用人工鲨鱼皮的好处是你可以对结构进行微小的改变,然后在测量中看看会产生什么变化,你瞧,你可以修改并比较,这可以帮助你知晓并理解非常精密的生物结构。

——《化学世界》,英国皇家化学学会 2014/07

[注]:你也许会问为什么要用3D打印的方法呢?对鲨鱼皮的观察与仿制人们以前也努力过,但无法实现,因为鲨鱼的肤齿太微小了——约0.15毫米的长度,本身还有复杂的形状,一端嵌入在皮层中,有一定的活动度,每平方毫米好几十个……打印用到了两种材料。打印速度很慢,一个月只能打印几平方厘米。受当前3D打印精度的限制,他们现在打印的鲨鱼肤齿比真的要大许多,但即使如此测量发现确实有明显作用。BBC对此有过一个新闻报道,还有照片,可以参考一下:http://www.bbc.co.uk/news/science-environment-27409836

 (30m49s)

They took a piece of real shark skin and used that to create a model on a computer, which was then used as a template for the 3D printer. And that made this skin’s ___, which like a sheet very flexible bendy plastic like the skin with these much harder little scales on it. And that was what they used in their subsequent experiments in the tank. Now you could say: well, why not just take the shark skin and do with the shark skin? But the good thing about having an artificial one is that you can then change tiny elements of that structure and see what deference you make to the measurement you are making so as you see you can then manipulate and compare. And that is what can help you learn and understand more about the very precise biomechanics.

-- Chemistry World, The Royal Society of Chemistry, UK 2014/07

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