Molecular Dynamic Assessment of Carbon Nanotube Drag In Physiologic Conditions

生理条件下碳纳米管阻力的分子动态评估

• 批准号: 8513992
• 负责人: ADRIN GHARAKHANI
• 金额: $ 7.53万
• 依托单位: APPLIED SCIENTIFIC RESEARCH
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-07-19 至 2015-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8513992
• 关键词: Accounting; Address; Adoption; Aerosols; Air; Caliber; Carbon Nanotubes; Communities; Computer software; Data; Dependence; Deposition; Development; Drug Formulations; Environmental Health; Exposure to; Fiber; Future; Health; Heart; Human; Humidity; Journals; Length; Link; Liquid substance; Literature; Lung; Measurement; Measures; Mechanics; Modeling; Motion; Nanotubes; Outcome; Particulate; Physiological; Production; Property; Publications; Relative (related person); Research; Respiratory System; Respiratory tract structure; Review Literature; Risk; Series; Shapes; Solid; Toxic effect; Ultrafine; Upper respiratory tract; Water; base; density; experience; exposed human population; fibrogenesis; interest; literature survey; manufacturing process; molecular dynamics; nanomaterials; nanoscale; particle; respiratory; simulation; supercomputer; symposium; tool; ultrafine particle

DESCRIPTION (provided by applicant): The growing ubiquity of carbon nanotubes (CNTs) has raised serious concerns about the potential human health and environmental implications of ultrafine particles in general, and manufactured nanomaterials in particular. To this end, while significant research is conducted to ascertain the material toxicity of nanotubes and their potential, for example, to stimulate pulmonary fibrogenesis, aerosol dynamics simulation tools can serve as a valuable complementary asset to investigate the link between the respiratory flow, the ensuing dynamics of nanotubes in the respiratory tracts, and the eventual deposition of CNTs on the respiratory system walls. A typical outcome of such an analysis would be an estimate of how deep, and at what concentration levels and distributions, CNTs of various sizes and types would penetrate in the respiratory tract under physiologic flow conditions. At the heart of a successful nanotube dynamics simulation lies the availability of accurate models for forces experienced by the nanotube. The dominant forces in the nanometer scale are drag and Brownian motion, where the former is the focus of this proposal. An order of magnitude analysis of the length scales reveals that, depending on the size and orientation of the CNT with respect to the freestream, there may be two flow regimes of relevance to CNT drag - free-molecule and transition. Yet, a review of the literature reveals an absence of drag formulae for nanotubes in these flow regimes. To address this critical and unmet CNT dynamics modeling need, the Specific Aim proposed for this project is to perform a series of Molecular Dynamics simulations of air flow over CNTs under physiologically realistic conditions, and to obtain the drag on the CNT as a function of the relative humidity of the respiratory tract; the flow rate; the inclination angle of the CNT with respect to the streamwise direction; as well as the CNT diameter, chirality, aspect ratio, and end effects. The simulation data will be analyzed and reduced into a drag coefficient function. The results will be presented at an aerosol-related conference and subsequently submitted to (aerosol) journals for publication so as to make the drag coefficient function available to the wider scientific community; thereby, enabling future aerosol dynamics simulations of CNT flow in dry or moist air.

描述（由申请人提供）：碳纳米管（CNT）的日益普及引起了人们对超细颗粒（特别是人造纳米材料）潜在人类健康和环境影响的严重关注。为此，虽然进行了大量研究来确定纳米管的材料毒性及其潜力，例如刺激肺纤维化，但气溶胶动力学模拟工具可以作为有价值的补充资产来研究呼吸流、随后的呼吸流之间的联系。纳米管在呼吸道中的动力学，以及碳纳米管最终沉积在呼吸系统壁上。这种分析的典型结果是估计不同尺寸和类型的碳纳米管在生理流动条件下穿透呼吸道的深度、浓度水平和分布。成功的纳米管动力学模拟的核心在于纳米管所经历的力的精确模型的可用性。纳米尺度的主导力是阻力和布朗运动，前者是本提案的重点。对长度尺度的数量级分析表明，根据 CNT 相对于自由流的尺寸和方向，可能存在与 CNT 阻力相关的两种流动状态 - 自由分子和过渡。然而，对文献的回顾表明，在这些流态下缺乏纳米管的阻力公式。为了满足这一关键且未满足的 CNT 动力学建模需求，该项目提出的具体目标是在生理真实条件下对 CNT 上的气流进行一系列分子动力学模拟，并获得 CNT 上的阻力作为呼吸道相对湿度；流量；倾向 CNT相对于流向的角度；以及 CNT 直径、手性、长径比和末端效应。模拟数据将被分析并简化为阻力系数函数。研究结果将在气溶胶相关会议上公布，随后提交给（气溶胶）期刊发表，以使阻力系数函数可供更广泛的科学界使用；因此，未来可以对干燥或潮湿空气中的碳纳米管流动进行气溶胶动力学模拟。