EAGER/Collaborative Research: Understanding How Enamel Prism Lattices Promote a Remarkable Combination of Fracture and Wear Resistance in Grazing Mammal Dentitions

EAGER/合作研究：了解牙釉质棱镜晶格如何促进放牧哺乳动物牙列的抗折性和耐磨性的显着组合

• 批准号: 1937088
• 负责人: Brandon Krick
• 金额: $ 6.65万
• 依托单位: Lehigh University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-08-01 至 2020-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1937088&HistoricalAwards=false
• 关键词: EAGER; Collaborative; Research; Understanding; How

Fracture and wear are common issues in engineering - to the extent that the terms "worn," "fractured," and "broken" are generally synonymous with the end-of-utility of devices. In many cases, traditional materials fail to meet the complex, simultaneous performance requirements that would be ideal for next generation engineering systems. The enamel of the teeth of grazing animals represents one of nature's most remarkable biological materials -- a ceramic-like composite showing exceptional strength, toughness, wear-resistance, and ability to slow crack propagation. This is an important set of properties for a structure that is key to long-term survival in these animals - as functional teeth are required for feeding. This EArly-Concept Grant for Exploratory Research (EAGER) project will study these damage-tolerant biomaterials using a combination of evolutionary biology, biomechanics, and materials science. Results and methods from this research will be of considerable interest to investigators in many disciplines, including engineering, materials science, evolutionary biology, ecology, comparative anatomy, mammalogy, and paleontology. The research will also support the development of novel, sustainable materials with improved wear and fracture behavior. Graduate students will be involved in this truly interdisciplinary project and learn how the various fields can work together to tackle challenging questions. This research will also introduce a more effective, evolutionary approach for exploring nature for biomimetic examples.The goal of this interdisciplinary research is to specifically understand the biomechanical form, function and performance of enamel lattices, known as Modified Radial Enamel (MRE), in the grinding teeth of large herbivorous mammals. Samples will be obtained from numerous species, including equines (horses), bovids (e.g. bison and cattle) and suids (e.g. warthogs). This study will specifically focus on how these animals' teeth endure tens to hundreds of millions of high stress contact loading cycles and impacts while chewing tough and abrasive plant matter, such as grasses whose roots are laden with hard, fracture-promoting sediment inclusions. The underlying hypothesis is that MRE is an evolutionarily optimized compromise for: 1) incredible fracture resistance due to prism arrangements that localize damage and strategically control crack direction; 2) unexpected strength and toughness made possible by compliant proteinaceous prism sheaths that circumvent hydroxyapatite's inherent brittleness; and 3) wear resistance conveyed through hard, hyper-mineralized, oriented enamel prisms. The project will investigate this hypothesis through two objectives. First, the study will use an evolutionary biology approach to identify the ancestral enamel fabric character states to MRE that independently evolved in horses, bovids and warthogs. From this information, it will be possible to readily identify the specific evolutionary modifications to the enamel fabrics that enabled grinding and identify living species that can be used to undertake comparative biomechanical assessment. Second, the project will investigate the structure-property relationships of the enamel across multiple length scales by comprehensively characterizing the material properties using micro-and nano-mechanical tools, spectroscopy, and advanced electron microscopy. Teeth of grinding species with MRE will be compared with close relatives that retain the ancestral enamel fabrics, thereby revealing the salient anatomical changes that enabled the optimized combination of biomechanical properties.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

断裂和磨损是工程中的常见问题-在某种程度上，术语“磨损”、“断裂”和“断裂”通常与器械的使用寿命终止同义。在许多情况下，传统材料无法满足下一代工程系统理想的复杂、同步的性能要求。食草动物牙齿的釉质代表了自然界最显着的生物材料之一--一种陶瓷状的复合材料，显示出非凡的强度、韧性、耐磨性和减缓裂纹传播的能力。这是这些动物长期生存的关键结构的一组重要特性-因为功能性牙齿是进食所必需的。 EARLY概念探索性研究资助（EAGER）项目将结合进化生物学，生物力学和材料科学来研究这些耐损伤生物材料。这项研究的结果和方法将引起许多学科研究人员的极大兴趣，包括工程学、材料科学、进化生物学、生态学、比较解剖学、哺乳动物学和古生物学。该研究还将支持开发具有改善的磨损和断裂行为的新型可持续材料。研究生将参与这个真正的跨学科项目，并学习各个领域如何共同解决具有挑战性的问题。 这项跨学科研究的目标是具体了解大型草食性哺乳动物磨牙中釉质晶格（称为改性放射状釉质（MRE））的生物力学形式、功能和性能。 将从许多种属中获得样本，包括马科动物（马）、牛科动物（例如野牛和牛）和猪科动物（例如疣猪）。这项研究将特别关注这些动物的牙齿如何承受数千万到数亿次高应力接触载荷循环和冲击，同时咀嚼坚韧和研磨性的植物物质，例如根部充满坚硬，促进生长的沉积物夹杂物的草。潜在的假设是MRE是针对以下方面的进化优化的折衷：1）由于棱柱布置而产生的令人难以置信的抗断裂性，所述棱柱布置使损伤局部化并策略性地控制裂纹方向; 2）通过顺应性蛋白质棱柱鞘而实现的意外的强度和韧性，所述顺应性蛋白质棱柱鞘规避了羟基磷灰石的固有脆性;以及3）通过硬的、超矿化的、定向的釉质棱柱传递的耐磨性。该项目将通过两个目标调查这一假设。 首先，该研究将使用进化生物学方法来识别在马、牛科动物和疣猪中独立进化的MRE的祖先釉质织物特征状态。从这些信息中，将有可能很容易地确定特定的进化修改的搪瓷织物，使研磨和识别活的物种，可用于进行比较生物力学评估。 其次，该项目将通过使用微纳米机械工具，光谱学和先进的电子显微镜全面表征材料特性，研究釉质在多个长度尺度上的结构-性能关系。MRE研磨物种的牙齿将与保留祖先釉质织物的近亲进行比较，从而揭示显着的解剖学变化，使生物力学性能的优化组合。该奖项反映了NSF的法定使命，并已被认为值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。