Feb 19 2019
当龙虾在背面翻倒时，可以看到其尾巴的底面被分为一段片段，该段被半透明的膜连接在一起，与保护甲壳类动物的甲型覆盖物相比，该膜看起来很虚弱。
一部看似艰难的电影可以保护龙虾的腹部，因为动物在岩石海底横跨。（图片来源：麻省理工学院）
但是，工程师在麻省理工学院and others have found that this soft membrane is amazingly tough, with a microscopic, layered, plywood-like structure that makes it extremely tolerant to cuts and scratches. This deceptively tough film shields the lobster’s belly as the animal runs over the rocky seafloor.
此外，膜伸展到一定程度，这使龙虾可以从一侧到另一侧鞭打尾巴，从而使捕食者很难咀嚼尾巴或将其拉开。
这种灵活性是由于膜是由90％的水组成的天然水凝胶的事实。几丁质是几种壳和外骨骼中存在的纤维材料，构成了其余的大部分。
研究结果表明，龙虾膜是所有天然水凝胶（包括天然橡胶，胶原蛋白和动物皮）中最艰难的材料。该膜几乎与工业橡胶复合材料一样强，例如用于生产花园软管，输送带和汽车轮胎的膜。
龙虾的坚硬但弹性的膜可以作为设计更灵活的防弹衣的指南，特别是针对身体高度可移动的部位，例如肘部和膝盖。
我们认为这项工作可以激发灵活的装甲设计。如果您可以用这类材料制作盔甲，则可以自由移动关节，这会让您感到更舒适欧洲杯足球竞彩。
Ming Guo，MIT机械工程系D'Arbeloff职业发展助理教授
解释研究结果的完整论文已于2月14日在线发布Th在日记中Acta Materialia。（该期刊在1月31日发布了未校正的证明英石。纸。
灵活的保护
与访客一起去他的实验室晚餐后，郭开始调查龙虾膜的特性。
“He had never eaten lobster before, and wanted to try it，”郭回忆道。“While the meat was very good, he realized the belly’s transparent membrane was really hard to chew. And we wondered why this was the case。”
Although there has been much research dedicated to the lobster’s unique, armor-like shell, Guo discovered that there was limited knowledge about the crustacean’s softer tissues.
“当龙虾游泳时，他们会伸展和移动关节，然后将尾巴倒快，以逃离掠食者，”郭说。“They can’t be entirely covered in a hard shell—they need these softer connections. But nobody has looked at the membrane before, which is very surprising to us。”
因此，郭和他的团队开始描述奇异材料的属性。他们将每个膜分为薄片，每个膜进行多种实验测试。他们将一些切片放在小烤箱中干燥，然后测量其体重。从这些测量值中，他们预测了90％的龙虾膜由水组成，使其成为水凝胶材料。
他们将其他样品放入盐水中，以繁殖天然的海洋环境。他们通过将每个膜放入伸展样品的机器中，同时测量准确施加的力，对其中一些样品进行了机械测试。他们观察到该膜最初是柔软的，并且很容易扩展，直到达到其初始长度的两倍，此时，材料开始变硬，逐渐变得更坚硬，更耐伸展。
“This is quite unique for biomaterials，”郭指出。“对于许多其他坚硬的水凝胶，您越伸展，它们的柔和。这种应变的行为可以使龙虾灵活地移动，但是当发生不好的事情时，它们会变硬并保护自己。”
Lobster’s Natural Plywood
当龙虾在海底移动时，它可能会刮擦磨碎的岩石和沙子。科学家对龙虾膜对如此小的切割和划痕有多弹性感到好奇。他们使用小手术刀刮擦膜样品，然后以与完整膜相同的方式扩展它们。
We made scratches to mimic what might happen when they’re moving through sand, for example. We even cut through half the thickness of the membrane and found it could still be stretched equally far. If you did this with rubber composites, they would break。
Ming Guo，MIT机械工程系D'Arbeloff职业发展助理教授
After that, the scientists used electron microscopy to focus on the membrane’s microstructure. They observed a structure which was very analogous to plywood. Each membrane, measuring nearly a quarter of a millimeter thick, is made up of tens of thousands of layers. A single layer consists of countless numbers of chitin fibers, which looks like filaments of straw, all aligned at the same angle, precisely 36° offset from the layer of fibers on top. In the same way, plywood is usually made of three or more thin layers of wood, the grain of each layer is arranged perpendicular to the layers above and below.
“When you rotate the angle of fibers, layer by layer, you have good strength in all directions，”郭说。“人们一直在干燥材料中使用这种结构来进行缺陷。欧洲杯足球竞彩但这是第一次在天然水凝胶中看到。”
Under the supervision of Qin, the team also performed simulations to observe how a lobster membrane would respond to a simple cut if its chitin fibers were arranged like plywood, rather than in completely random orientations. In order to perform this, they initially simulated a single chitin fiber and assigned it certain mechanical properties like stiffness and strength. They subsequently mimicked millions of these fibers and compiled them into a membrane structure made up of either completely random fibers or layers of precisely oriented fibers, analogous to the actual lobster membrane.
拥有一个平台，使我们能够直接测试并展示几丁质纤维一旦将它们内置到各种体系结构中如何产生非常不同的机械性能，真是太神奇了。。
Zhao Qin, Research Scientist, Department of Civil and Environmental Engineering, MIT
At last, the scientists developed a small notch via both the random and layered membranes, and programmed forces to expand each membrane. The simulation envisioned the stress throughout each membrane.
“在随机膜中，压力全部相等，当您拉伸时，它会迅速破裂，”郭说。“我们发现分层结构不断伸展而伸展。”
“一个谜是如何指导几丁质纤维组装成如此独特的分层建筑以形成龙虾膜,” stated Qin. “我们正在努力理解这种机制，并认为此类知识对于开发创新的方式来管理微观结构的材料合成是有用的。”
According to Guo, the materials designed to imitate lobster membranes could not only be useful in flexible body armor but also in soft robotics and tissue engineering. At any event, the results throw new light on the survival of one of nature’s most resilient creatures.
我们认为，这种膜结构可能是龙虾在地球上生活超过1亿年的非常重要的原因。不知何故，这种骨折的耐受性确实帮助他们进化。
Ming Guo，MIT机械工程系D'Arbeloff职业发展助理教授
这项工作得到了中国国家自然科学基金会和聚合物材料工程的国家主要实验室的支持。欧洲杯足球竞彩欧洲杯线上买球