Theory and Simulation of Liquids, Solutions, and Nucleation Processes

液体、溶液和成核过程的理论和模拟

• 批准号: RGPIN-2018-04762
• 负责人: Patey, Grenfell
• 金额: $ 6.99万
• 依托单位: University of British Columbia
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=748042
• 关键词: Theory; Simulation; Liquids; Solutions; Nucleation

Crystal nucleation from melts or solution is an important process that occurs practically everywhere in our surrounding environment. The nucleation of ice crystals in liquid water, and of common salts such as NaCl (rock salt) from solution are important examples considered in this proposal. The normal freezing point of water is 0 oC, but pure water can be supercooled to near -35 oC before freezing occurs. This means that essentially all ice nucleation on earth or in the atmosphere is facilitated by contact with a foreign body. This process is called heterogeneous nucleation, and the foreign body is termed an ice nucleus. Heterogeneous ice nucleation is an important process in the atmosphere because ice nucleation by atmospheric aerosols results in ice clouds, which in turn influence the global climate. Although heterogeneous ice nucleation has long been a subject of investigation, little is known about the microscopic nature of a good ice nucleus. This absence of knowledge is mainly because the small sizes and fast times relevant to nucleation are not easily accessible by current experiments. The proposed research will employ computer simulations to examine these questions. Computer simulations can be viewed as "experiments'' on representative models of real systems, which allow us to follow physical processes at the molecular level. This is a very powerful approach which yields a microscopic understanding of physical phenomena that is not otherwise available. We will use molecular dynamics simulations to examine particularly important atmospheric aerosols, such clays and other mineral particles, as well as to obtain a deeper understanding of the general factors that influence heterogeneous ice nucleation. We will also employ molecular simulation to investigate the crystallization of salts and other molecular solids from solution. The purpose is again to probe the underlying mechanisms of crystal birth, and identify the crystal and solution properties which enhance or inhibit crystal nucleation and growth. The state and function of many physical and biological systems depends on a balance between moieties that interact favourably with water (hydrophilic) and those that do not (hydrophobic). Molecules that have both hydrophilic and hydrophobic parts are called amphiphilic. We will explore how competing hydrophilic and hydrophobic interactions influences the nanoscale structure of several model solutions containing amphiphilic solutes. This work promises new insight into why some small molecules function more effectively than others as protein denaturants. Denaturants are molecules that cause proteins to change their structure to a less compact (unfolded) state in aqueous solution.

熔体或溶液中的晶体成核是一个重要的过程，几乎在我们周围的环境中随处发生。液态水中冰晶的成核以及溶液中氯化钠（岩盐）等普通盐的成核是本提案考虑的重要例子。水的正常冰点为 0 oC，但纯水在结冰前可过冷至 -35 oC 附近。这意味着地球上或大气中的所有冰核基本上都是通过与异物接触来促进的。这个过程称为异质成核，异物称为冰核。非均质冰核形成是大气中的一个重要过程，因为大气气溶胶的冰核形成冰云，进而影响全球气候。尽管异质冰核长期以来一直是研究的主题，但人们对良好冰核的微观性质知之甚少。这种知识的缺乏主要是因为当前的实验不容易获得与成核相关的小尺寸和快速时间。拟议的研究将采用计算机模拟来研究这些问题。计算机模拟可以被视为对真实系统的代表性模型的“实验”，它使我们能够在分子水平上跟踪物理过程。这是一种非常强大的方法，可以产生对物理现象的微观理解，这是其他方法无法获得的。我们将利用分子动力学模拟来研究特别重要的大气气溶胶，例如粘土和其他矿物颗粒，并更深入地了解影响异质冰成核的一般因素。我们还将利用分子模拟来研究盐和盐的结晶。其他分子目的再次是探究晶体诞生的潜在机制，并确定增强或抑制晶体成核和生长的晶体和溶液特性。许多物理和生物系统的状态和功能取决于各部分之间的平衡。与水发生良好的相互作用（亲水性），而与水不发生相互作用（疏水性）。同时具有亲水部分和疏水部分的分子称为两亲分子。我们将探索竞争性亲水性和疏水性相互作用如何影响几种含有两亲性溶质的模型溶液的纳米级结构。这项工作为为什么一些小分子作为蛋白质变性剂比其他小分子更有效地发挥作用提供了新的见解。变性剂是导致蛋白质在水溶液中将其结构改变为不太紧凑（展开）状态的分子。