Cracking the problem of heterogeneous nucleation: identifying the sites responsible for ice nucleation

对于一系列领域来说，对冰的形成有一个基本的了解是至关重要的。然而，我们对某些物质为什么会触发冰的形成，而其他物质为什么不会的了解非常有限。人们认为，可能只有几十纳米平方的表面上的特定位置是成核的原因，但这些位置只能占据表面的10%-10%。因此，它们非常难以识别和表征，我们对它们的理解仍然非常糟糕。在这个博士项目中，学生将专注于通过利用利兹冰核小组开发的独特设备和资源进行新颖的实验室实验来提高我们关于冰核形成的基本知识。学生还将处于独特的地位，利用他们在以下领域的发现：云中冰的成核和低温保存期间生物样本中冰的形成的控制。云中的冰成核有助于定义地球上的生命，因为云在我们星球的气候及其水循环中发挥着核心作用，而控制冰成核是一系列领域的关键限制，例如为药品的高通量毒理学筛选提供细胞。目的：1.利用我们现有的配有高速相机的冷冻显微镜来研究矿物样品薄片上的冰核作用，以确定成核点。测试这些站点对盐和酸存在的反应。我们知道盐类可以促进或抑制冰核的形成，但不知道为什么。酸可以使成核位点失活，但将这种失活与表面性质的变化联系起来以前从未做过。3.使用先进的成像技术探测导致冰核的地点的性质。4.有可能利用关于什么是有效的冰核形成部位的新知识，人为地创造冰核形成部位，可用于在诸如低温保存等应用中控制冰核形成。这将是与我们的合作伙伴冷冻保存公司互动的绝佳机会。有可能参加一场实地活动。虽然这个项目是以实验室为重点的，但我们将有机会参加世界各地的现场活动，在那里我们研究冰核。在过去的活动中，我们曾前往北极高地、巴巴多斯和冰岛等地。我们还在英国研究飞机(FAAM)和研究船上工作。

A fundamental understanding of the formation of ice is critical for a range of fields. However, we have very limited knowledge of why certain materials trigger the formation of ice, while others do not. It is thought that specific sites on surfaces which are perhaps just a few 10s of nanometers squared are responsible for nucleation, but these sites can occupy only 10-10 % of the surface. Hence, they are incredibly difficult to identify and characterise and our understanding of them remains extremely poor.In this PhD project the student will focus on improving our basic knowledge of ice nucleation through novel laboratory experimentation utilising the unique equipment and resources which have been developed in the Leeds Ice Nucleation Group. The student will also be uniquely positioned to exploit their discoveries in the fields of: nucleation of ice in clouds and the control of the formation of ice in biological samples during cryopreservation. Ice nucleation in clouds helps define life on Earth since clouds play a central role in our planet's climate and its hydrological cycle, while the control of ice nucleation is a key limitation in a range of areas, such as the supply of cells for the high throughput toxicology screening of pharmaceutical products. Objectives:1. Identify nucleation sites using our existing cryo-microscope equipped with a high speed camera to study ice nucleation on thin sections of mineral samples.2. Test the response of these sites to the presence of salts and acids. We know that salts can either enhance or deactivate ice nucleation, but do not understand why. Acids can deactivate nucleation sites, but linking this deactivation to changes in surface properties has never been done before. 3. Use advanced imaging techniques to probe the properties of the sites which cause ice nucleation. 4.Potentially use the new knowledge of what makes an effective ice nucleation site in order to artificially create ice nucleation sites which might be used for the control of ice nucleation in applications such as cryopreservation. This would be an excellent opportunity to interact with our partner cryopreservation company.5. Potentially take part in a field campaign. While this project is laboratory focused, there will be opportunities to take part in field campaigns around the world where we study ice nucleation. In past campaigns we have travelled to the high Arctic, Barbados and Iceland, amongst other places. We also work on the UK research aircraft (FAAM) and research ships.