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

对冰的形成有一个基本的了解对许多领域都是至关重要的。然而，对于为什么某些物质会触发冰的形成，而另一些则不会，我们的了解非常有限。据认为，表面上可能只有几十平方纳米的特定位置负责成核，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描述，我们对它们的理解仍然非常贫乏。在这个博士项目中，学生将专注于通过利用利兹冰成核小组开发的独特设备和资源进行新颖的实验室实验，提高我们对冰成核的基本知识。该学生还将具有独特的优势，可以利用他们在以下领域的发现：云中冰的成核以及在冷冻保存期间控制生物样品中冰的形成。云中的冰核有助于定义地球上的生命，因为云在我们星球的气候和水文循环中发挥着核心作用，而冰核的控制是一系列领域的关键限制，例如为药物产品的高通量毒理学筛选提供细胞。目的:1。利用我们现有的配备高速相机的冷冻显微镜来确定成核位置，研究矿物样品薄片上的冰成核。测试这些部位对盐和酸的反应。我们知道盐可以增强或破坏冰的成核，但不明白其中的原因。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来探测引起冰核的地点的性质。4.潜在地利用什么使一个有效的冰成核位置的新知识，以便人工地创造可能用于控制冰成核的冰成核位置，如冷冻保存等应用。这将是一个与我们的合作伙伴冷冻保存公司互动的绝佳机会。可能会参加野外战役。虽然这个项目以实验室为重点，但我们将有机会参加世界各地的实地活动，在那里我们研究冰核。在过去的活动中，我们去过北极高地、巴巴多斯和冰岛等地。我们还为英国研究飞机（FAAM）和研究船工作。

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.