School of Physical Sciences

I’ll be giving a broad overview of the decision procedures we have been building for bitvector reasoning in Lean, with both fixed and infinite width. Time permitting, I shall sketch the design and mechanization strategy of the infinite width decision procedure, since the core involves verifying a cute model checking algorithm (k-induction), with games to be played to hook in a SAT solver into the tactic loop.

Note: work done in collaboration with the wider Lean community, and effort led by the Lean FRO : Henrik Boving, Kim Morisson, and Leo de Moura.

=== Hybrid talk ===

Join Zoom Meeting https://cam-ac-uk.zoom.us/j/87143365195?pwd=SELTNkOcfVrIE1IppYCsbooOVqenzI.1

Meeting ID: 871 4336 5195

Passcode: 541180

• Speaker: Siddharth Bhat (University of Cambridge)
• Thursday 23 January 2025, 17:00-18:00
• Venue: MR14 Centre for Mathematical Sciences.
• Series: Formalisation of mathematics with interactive theorem provers ; organiser: Anand Rao Tadipatri.

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Rechargeable batteries have been an integral part of the portable electronics revolution and are now playing a critical role in transport and grid applications to help mitigate climate change. However, these applications come with different sets of challenges. New technologies are being investigated and fundamental science is key to producing non-incremental advances and to develop new strategies for energy storage and conversion.

This talk will focus on our own work to develop NMR , MRI and new optical methods that allow devices to be probed while they are operating, from the local, to particle and then cell level. This allows transformations of the various cell materials to be followed under realistic conditions without having to disassemble and take apart the cell. Starting with local structure and dynamics, as measured by NMR , I will then show – with the optical methods – how the different dynamics can result in different intercalation mechanisms. A good example is our work on LiCoO2, where via optical approaches we were able to directly visualize movement of phase fronts as lithium is removed and inserted into this material. I will discuss our work on the application of electron spin resonance and dynamic nuclear polarization (DNP) NMR to graphitic anode materials and lithium metal batteries, to understand battery degradation. Finally, new results on extremely high-rate batteries will be outlined and extensions of our new metrologies to study a wider range of electrochemical systems will be described.

14:00-15:00hrs Three 20 minute presentations. 15:00-15:30 Coffee break. 15:30-16:30 Professor Dame Clare P. Grey - Departmental Seminar

• Speaker: Professor Dame Clare P. Grey, FRS, DBE + 3 Researcher Presentations
• Friday 31 January 2025, 14:00-16:30
• Venue: Dept of Chemistry, (BMS) Bristol Myers Squibb Lecture Theatre.
• Series: Chemistry Departmental-wide lectures; organiser: Xani Thorman.

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I give an (unnecessary long-winded) introduction to the 2HDM+a searches with the ATLAS detector. A large-scale effort to investigate and constrain benchmarks with a wide range of competitive signatures is presented. A particular focus is given to the mono-Higgs searches.

• Speaker: Dr. Nikolai Fomin, University of Cambridge
• Tuesday 21 January 2025, 11:00-12:00
• Venue: Ryle Seminar Room.
• Series: Cavendish HEP Seminars; organiser: Dr. Aashaq Shah.

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Bubble dynamics and cavitation have traditionally been studied in the context of underwater acoustics and, more recently, biomedical applications. I will discuss how the deformation and flow fields generated by acoustically-driven bubbles can be used to drive self-assembly of novel microstructures in complex fluids. Bubble dynamics driven at ultrasonic frequencies probe time scales as short as 10ˉ³−10ˉ⁶ s, comparable to the smallest relaxation time scales for complex fluids containing suspended particles or macromolecules. I will describe how, in this dynamical regime, dynamic capillary interactions arise between colloidal particles adsorbed at a fluid interface, producing particle networks that dominate the mechanics of these complex interfaces under flow. I will also describe a new flow-induced mechanism caused by bubble dynamics, that produces ordered microstructures in colloidal gels. This mechanism can enable energy-efficient processing methods of colloidal-gel materials, including inks, battery electrodes, construction materials. I will also discuss the emerging approach of using bubble dynamics to probe the high-frequency viscoelastic properties of complex fluids and soft materials, which has brought together the communities of cavitation and rheology to address new challenges in characterization of soft materials.

Cassyni Link below:

https://cassyni.com/events/AyG2QQDJ3FQqksbaTP2zAh

• Speaker: Professor Valeria Garbin, Delft University of Technology
• Friday 07 February 2025, 16:00-17:00
• Venue: Fluid Mechanics Webinar Series.
• Series: Fluid Mechanics (DAMTP); organiser: Professor Grae Worster.

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Abstract not available

• Speaker: Maleeha Khawaja (Bristol)
• Tuesday 18 March 2025, 14:30-15:30
• Venue: MR13.
• Series: Number Theory Seminar; organiser: Jef Laga.

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Abstract not available

• Speaker: Siqi Yang (LSGNT)
• Tuesday 11 March 2025, 14:30-15:30
• Venue: MR13.
• Series: Number Theory Seminar; organiser: Jef Laga.

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Abstract not available

• Speaker: Chris Wutrich (Nottingham)
• Tuesday 04 March 2025, 14:30-15:30
• Venue: MR13.
• Series: Number Theory Seminar; organiser: Rong Zhou.

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Abstract not available

• Speaker: Daniel Li Huerta (MPIM)
• Tuesday 25 February 2025, 14:30-15:30
• Venue: MR13.
• Series: Number Theory Seminar; organiser: Rong Zhou.

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Abstract not available

• Speaker: Andrew Graham (Oxford)
• Tuesday 18 February 2025, 14:30-15:30
• Venue: MR13.
• Series: Number Theory Seminar; organiser: Rong Zhou.

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While density functional theory (DFT) remains the standard for accurate simulation of nuclear magnetic resonance (NMR) spectra, its computational cost remains prohibitive. Use of DFT for structural confirmation is only justified where it offers substantial time savings over the experiment, such as total synthesis of natural products. Neural networks are a promising solution for simpler molecules, but published examples cannot estimate the prediction uncertainty.

By incorporating uncertainty estimation into an existing neural network, we can confirm the structure from its NMR spectrum 100,000 times faster than using DFT , with calculations completed in milliseconds rather than hours. Large-scale combinatorial studies show that our approach matches accuracy of DFT -based DP5 analysis and exceeds the sensitivity of simple error analysis. Analysis of 24 misassigned natural product structures demonstrates the generalisability of the method and equal performance to that of DFT .

We are now exploring the potential of the new method for automated structure revision and interpretation of 1H NMR spectra.

• Speaker: Ruslan Kotlyarov, University of Cambridge
• Wednesday 29 January 2025, 14:30-15:00
• Venue: Unilever Lecture Theatre, Yusuf Hamied Department of Chemistry.
• Series: Theory - Chemistry Research Interest Group; organiser: Lisa Masters.

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The world of synthetic organic chemistry has made significant strides in discovering new medicines, materials, and fine chemicals. However, there is a major aspect that has been overlooked for years – the reactor itself. In this talk, we will explore the potential of flow chemistry to advance synthetic organic chemistry through technological innovation. By harnessing the power of flow chemistry, chemists can unlock unique reactivity and selectivity, enabling them to push the boundaries of what is possible.[1] Not only does flow chemistry make new synthetic routes achievable, it can fast-track them from the lab to large scale production.[2] At our research group, we are committed to advancing the field by developing automated and flow-based reaction technologies that reduce manual labor, increase reproducibility, and accelerate reaction discovery. Our focus on flow chemistry has led to exciting developments in methodological advancements, including photocatalysis, fluorine chemistry, and bioconjugation chemistry. In this talk, we aim to showcase the potential of flow chemistry and how it can team up with methodological development to take synthetic organic chemistry to the next level. We will highlight the perks of flow chemistry, from improving reaction efficiency to enabling the discovery of new chemical reactions. Our ultimate goal is to inspire chemists to adopt this innovative technology and unlock new possibilities for synthetic organic chemistry.

[1] Capaldo, L.; Wen, Z. and Noël, T. A field guide to flow chemistry for synthetic organic chemists. Chem. Sci., 2023, 14, 4230-4247. [2] D.A. Zondag, S.; Mazzarella, D. and Noël, T. Scale-Up of Photochemical Reactions: Transitioning from Lab Scale to Industrial Production. Annu. Rev. Chem. Biomol. Eng., 2023, 14, 283-300.

• Speaker: Professor Timothy Noël (University of Amsterdam, Van 't Hoff Institute for Molecular Sciences)
• Thursday 10 April 2025, 14:00-15:00
• Venue: Dept. of Chemistry, Wolfson Lecture Theatre.
• Series: Synthetic Chemistry Research Interest Group; organiser: pd552.

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Abstract not available

• Speaker: Henrique Magri Marçon, University of Cambridge
• Wednesday 29 January 2025, 15:00-15:30
• Venue: Unilever Lecture Theatre, Yusuf Hamied Department of Chemistry.
• Series: Theory - Chemistry Research Interest Group; organiser: Lisa Masters.

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Abstract not available

• Speaker: Ruslan Kotlyarov, University of Cambridge
• Wednesday 29 January 2025, 14:30-15:00
• Venue: Unilever Lecture Theatre, Yusuf Hamied Department of Chemistry.
• Series: Theory - Chemistry Research Interest Group; organiser: Lisa Masters.

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The van-der-Waals antiferromagnets TMPS3 , where TM = Transition Metal, form an ideal playground for tuning both low-dimensional magnetic and electronic properties . These are layered honeycomb antiferromagnetic Mott insulators, long studied as near-ideal 2D magnetic systems with a rich landscape of competing interactions and a variety of magnetic properties across the family. I will give an overview of my work using high pressure as a continuous tuning parameter to control the dimensionality of these materials. Due to the weak physical inter-planar forces in such van-der-Waals materials, pressure gives us clean and selective control over the interplanar spacing and hence interactions.

I will present magnetic, structural and electrical transport results and compare the behaviour of Fe-, V-, Mn- and NiPS3 as we tune them towards 3D structures – and Mott transitions from insulator to metal. I show multiple enigmatic features in electrical transport in this ‘strange metal’ high pressure regime. I will focus in particular upon our recent ultra-high pressure neutron scattering results, which have unveiled an enigmatic form of short-range magnetic order in metallic FePS3. This phase is particularly important as it most likely forms a precursor to superconductivity, and the direct observation of magnetism here completely overturns the existing wisdom in the literature of a spin-crossover transition as the Fe local environment changes. I will contrast these measurements with our recent equivalent results on sister compound FePSe3, in which superconductivity has in fact recently been observed.

Finally I will describe our recent efforts to engineer magnetic frustration into this lattice, and discuss muon-spin-rotation measurements on some members of the family which give interesting hints towards complex magnetic behaviour.

• Speaker: Dr. Matthew Coak (School of physics and astronomy, University of Birmingham)
• Wednesday 22 January 2025, 11:15-12:00
• Venue: Mott Seminar Room (531), Cavendish Laboratory, Department of Physics.
• Series: Quantum Matter Seminar; organiser: Mads Fonager Hansen.

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The reduction of atmospheric reactive nitrogen (Nr) and sulfur (Sr) species is a key objective for air quality control policies as they contribute to the formation of PM2 .5, which has significant effects on human health and climate, and their deposition affects ecosystem productivity. The chemical climate for Nr and Sr pollution has undergone dramatic changes in the past two decades. Therefore, it is necessary to update our understanding of global Nr and Sr chemistry and investigate their mitigation under current atmospheric conditions. Since a range of emission sources and atmospheric chemical and physical processes contribute to Nr and Sr concentrations, atmospheric chemistry transport models (ACTMs) are essential tools to identify the key processes controlling their impacts and effective mitigation. In this talk, I will present my research on global modelling of Nr and Sr species using the EMEP MSC -W ACTM coupled with WRF meteorology. Firstly, I will introduce the model-measurement comparisons of reduced nitrogen (RDN), oxidized nitrogen (OXN), and oxidized sulfur (OXS) species covering 10 monitoring networks worldwide that measure surface concentrations and wet deposition. Secondly, I will summarize our global analysis of current Nr and Sr gas-aerosol partitioning and regional budgets. This analysis quantitatively demonstrates that successful control of SO2  and NOx emissions has resulted in atmospheric NH3  excess in many areas, leading to a new significance of alkaline air, with adverse impacts on ecosystems. Finally, I will present our work that quantifies the sensitivities of emissions reductions for mitigating PM2 .5 and N and S deposition. This work highlights a global picture of the effectiveness of NH3 , NOx, and SOx emissions reductions for mitigating both concentrations and deposition of Nr and Sr pollutants.

• Speaker: Dr Yao Ge, Yusuf Hamied Department of Chemistry, University of Cambridge
• Tuesday 18 March 2025, 11:00-12:00
• Venue: Chemistry Dept, Unilever Lecture Theatre and Zoom.
• Series: Centre for Atmospheric Science seminars, Chemistry Dept.; organiser: Dr Megan Brown.

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Stratospheric aerosol injection (SAI) is a proposed method of cooling the planet and reducing the impacts of climate change by adding a layer of small particles to the high atmosphere where they would reflect a fraction of incoming sunlight. While it is likely that SAI could reduce global temperature, it has many serious risks and would not perfectly offset climate change. For SAI to be effective, injection would need to take place in the stratosphere. The height of the transition to the stratosphere decreases with latitude, from around 17km near the equator to 8km near the poles. The required injection height would therefore also decrease for higher latitude injection. In this talk, I will present simulations of SAI in an earth system model, UKESM , which quantify how impacts would vary with the injection location and timing, focusing on low-altitude high-latitude injection strategies. Our results suggest that SAI could meaningfully cool the planet even if limited to using existing large jets and injecting at around 13km altitude, if this injection is in the high latitudes during spring and summer. However, relative to a more optimal deployment with novel aircraft at 20km, this strategy requires three times more sulphur dioxide injection and so would strongly increase some side-effects.

• Speaker: Alistair Duffey, PhD Student at University College London, Earth Sciences
• Tuesday 04 February 2025, 11:00-12:00
• Venue: Chemistry Dept, Unilever Lecture Theatre and Zoom.
• Series: Centre for Atmospheric Science seminars, Chemistry Dept.; organiser: Yao Ge.

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Abstract not available

• Speaker: Tristan Stérin (Maynooth University, Ireland) and Maja Kądziołka
• Thursday 13 March 2025, 17:00-18:00
• Venue: MR14 Centre for Mathematical Sciences.
• Series: Formalisation of mathematics with interactive theorem provers ; organiser: Anand Rao Tadipatri.

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Abstract not available

• Speaker: Tristan Stérin (Maynooth University, Ireland) and Maja Kądziołka
• Thursday 13 March 2025, 17:00-18:00
• Venue: MR14 Centre for Mathematical Sciences.
• Series: Formalisation of mathematics with interactive theorem provers ; organiser: Anand Rao Tadipatri.

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=== Hybrid talk ===

Join Zoom Meeting https://cam-ac-uk.zoom.us/j/87143365195?pwd=SELTNkOcfVrIE1IppYCsbooOVqenzI.1

Meeting ID: 871 4336 5195

Passcode: 541180

• Speaker: Andrew Yang (Imperial College, London)
• Thursday 08 May 2025, 17:00-18:00
• Venue: MR14 Centre for Mathematical Sciences.
• Series: Formalisation of mathematics with interactive theorem provers ; organiser: Anand Rao Tadipatri.

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Sea ice dynamics are highly complex and generally poorly resolved by sea ice models. This is problematic, as they modulate the amount of momentum exchanged between the atmosphere and the ocean in polar regions, as well as play a key role in heat and light fluxes through the opening/closing of sea ice leads. A solution to improve simulated sea ice dynamics is to use a brittle rheology to represent the mechanical behaviour of sea ice. Such rheology is included in the sea ice model neXtSIM, and we demonstrated its ability to capture the observed characteristics and complexity of fine-scale sea ice deformations.Here, we present two cases where we coupled this sea ice model to better understand the role of ice dynamics in ice-ocean interactions.

In the first case, we set up a 12km resolution ocean—sea-ice coupled model, using OPA , the ocean component of NEMO . We investigate the sea ice mass balance of the model for the period 2000-2018. We estimate the contribution of leads and polynyas to winter ice production. We find this contribution to add up from 25% to 35% of the total ice growth in pack ice in winter, showing a significant increase over the 18 years covered by the model simulation.

In the second case, we focus on the marginal ice zone (MIZ) and couple neXtSIM with the wave model WAVEWATCH III . We investigate how wave-induced breakup impacts sea ice dynamics in the MIZ . We show how, using the “damage” quantity that is at the core of the brittle rheology framework, we can represent the loss of ice strength associated with wave-induced breakup, and how breakup can increase the mobility of the thickest ice in the MIZ after storms. For both cases, we will also discuss briefly how using a brittle sea ice model could impact the modelling of Antarctic sea ice using preliminary results from a new configuration.

• Speaker: Guillaume Boutin (Nansen Environmental and Remote Sensing Center)
• Wednesday 29 January 2025, 14:00-15:00
• Venue: BAS Seminar Room 1; .
• Series: British Antarctic Survey - Polar Oceans seminar series; organiser: Dr Birgit Rogalla.

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