Feed aggregator

Title to be confirmed

Abstract not available

• Speaker: Prof Pedram Hassanzedeh, University of Chicago
• Friday 16 May 2025, 16:00-17:00
• Venue: MR2.
• Series: Fluid Mechanics (DAMTP); organiser: Professor Grae Worster.

Add to your calendar or Include in your list

PhD Students' talks

Abstract not available

• Speaker: Speakers listed in abstract in due course
• Friday 30 May 2025, 16:00-17:00
• Venue: MR2.
• Series: Fluid Mechanics (DAMTP); organiser: Professor Grae Worster.

Add to your calendar or Include in your list

Numerical simulations of multiphase flows with various complexities

Abstract not available

• Speaker: Prof Omar Matar, Imperial College London
• Friday 06 June 2025, 16:00-17:00
• Venue: https://cassyni.com/s/fmws.
• Series: Fluid Mechanics (DAMTP); organiser: Professor Grae Worster.

Add to your calendar or Include in your list

From Wall-Climbing Active Colloids to self-assembly of Magnetotactic Bacteria

The observation of flocks of birds, schools of fish, and swarms of bees reveals captivating examples of collective behavior in nature. Over the past decade, physicists have unveiled intriguing features in such systems, giving rise to both spectacular phenomena and fundamental questions. In this presentation, we will first explore active wetting phenomena in a suspension of self-propelled Janus colloids near a vertical wall. While classical capillary rise is governed by equilibrium surface tension, active fluids challenge this paradigm. We investigate whether analogous interfacial effects emerge in non-phase-separated active sediments, uncovering how self-propulsion modifies wetting behavior. By studying the interaction between a non-phase-separated active sediment and a wall, we uncover how self-propulsion alters wetting-like behavior, offering insights into the role of activity in interfacial processes. In the second part, we turn to magnetotactic bacteria— microswimmers equipped with intracellular magnetic nanoparticles, enabling directed motion along magnetic fields. These bacteria exhibit dual sensitivity, responding not only to magnetic fields (magnetotaxis) but also to oxygen gradients (aerotaxis), which drives them to form dense, dynamic bands. We demonstrate how the interplay of magnetic steering, chemical gradients, and hydrodynamic interactions leads to rich self-organization.

• Speaker: Prof Cottin-Bizonne, Université Lyon
• Friday 23 May 2025, 16:00-17:00
• Venue: MR2.
• Series: Fluid Mechanics (DAMTP); organiser: Professor Grae Worster.

Add to your calendar or Include in your list

Energy Environ. Sci., 2025, Accepted Manuscript
DOI: 10.1039/D5EE00736D, PaperFang Cao, Xinfeng Dai, Di Tian, Yingchen Peng, Jun Yin, Jing Li, Ye Yang, Nanfeng Zheng, Binghui Wu
In n-i-p halide perovskite solar cells (PSCs), replacing organic p-type semiconductors with inorganic alternatives offers significant potential for enhancing long-term stability. While nickel oxide (NiOx) gained prominence as a hole...
The content of this RSS Feed (c) The Royal Society of Chemistry

Gravitational Wave Signatures of Dark Matter in Neutron Star Mergers

Binary neutron star mergers provide insights into strong-field gravity and the properties of ultra-dense nuclear matter. These events offer the potential to search for signatures of physics beyond the standard model, including dark matter. We present the first numerical-relativity simulations of binary neutron star mergers admixed with dark matter, based on constraint-solved initial data. Modeling dark matter as a non-interacting fermionic gas, we investigate the impact of varying dark matter fractions and particle masses on the merger dynamics, ejecta mass, post-merger remnant properties, and the emitted gravitational waves. Our simulations suggest that the dark matter morphology – a dense core or a diluted halo – may alter the merger outcome. Scenarios with a dark matter core tend to exhibit a higher probability of prompt collapse, while those with a dark matter halo develop a common envelope, embedding the whole binary. Furthermore, gravitational wave signals from mergers with dark matter halo configurations exhibit significant deviations from standard models when the tidal deformability is calculated in a two-fluid framework neglecting the dilute and extended nature of the halo. This highlights the need for refined models in calculating the tidal deformability when considering mergers with extended dark matter structures. These initial results provide a basis for further exploration of dark matter’s role in binary neutron star mergers and their associated gravitational wave emission and can serve as a benchmark for future observations from advanced detectors and multi-messenger astrophysics.

• Speaker: Violetta Sagun, University of Southampton
• Friday 30 May 2025, 13:00-14:00
• Venue: MR9/Zoom.
• Series: DAMTP Friday GR Seminar; organiser: Xi Tong.

Add to your calendar or Include in your list

TBC

Abstract not available

• Speaker: Benjamin Elder, Imperial College London
• Friday 16 May 2025, 13:00-14:00
• Venue: MR20/Zoom.
• Series: DAMTP Friday GR Seminar; organiser: Xi Tong.

Add to your calendar or Include in your list

TBC

Abstract not available

• Speaker: Robbie Hennigar, Durham University
• Friday 09 May 2025, 13:00-14:00
• Venue: MR9/Zoom.
• Series: DAMTP Friday GR Seminar; organiser: Xi Tong.

Add to your calendar or Include in your list

A Spacetime Interpretation of the Confluent Heun Functions in Black Hole Perturbation Theory

In Black Hole Perturbation Theory, confluent Heun functions appear as solutions to the radial Teukolsky equation, which governs perturbations in black hole spacetimes. While these functions are typically studied for their analytic properties, their connection to the underlying spacetime geometry has received less attention. In this talk, I will propose a spacetime interpretation of the confluent Heun functions, demonstrating how their behaviour near their singular points reflects the structure of key surfaces in Kerr spacetimes. By interpreting homotopic transformations of these functions as changes in the spacetime foliation, I will establish a connection between these solutions and various regions of the black hole’s global structure. I will also explore their relationship with the hyperboloidal formulation of the radial Teukolsky equation.

• Speaker: Marica Minucci, Bohr Inst., Copenhagen
• Friday 06 June 2025, 13:00-14:00
• Venue: Potter room/Zoom.
• Series: DAMTP Friday GR Seminar; organiser: Xi Tong.

Add to your calendar or Include in your list

Title to be confirmed

Abstract not available

• Speaker: Speaker to be confirmed
• Friday 30 May 2025, 14:00-15:00
• Venue: MR12, Centre for Mathematical Sciences.
• Series: Statistics; organiser: Qingyuan Zhao.

Add to your calendar or Include in your list

Title to be confirmed

Abstract not available

• Speaker: Professor Kim Jelfs, Imperial College London
• Wednesday 05 November 2025, 14:30-15:30
• Venue: Unilever Lecture Theatre, Yusuf Hamied Department of Chemistry.
• Series: Theory - Chemistry Research Interest Group; organiser: Lisa Masters.

Add to your calendar or Include in your list

The thermo-electric-mechanical coupling strategy proposed here predicts the feasibility of Ni2SbTe2 and NiTe2 as ideal TEbMs for (Bi,Sb)2Te3 and Bi2(Te,Se)3, based on three-phase thermodynamic equilibrium, electrical resistivity, and CTE compatibility. The fabricated TE generators demonstrate a third-party-verified conversion efficiency of 7.1% and a power density of 0.49 W cm−2 when the hot-side temperature is 523 K, with negligible degradation over 200 h.

Abstract

The long-term stability of thermoelectric generators, including those based on Bi2Te3, is hindered by the lack of ideal thermoelectric barrier materials (TEbMs). Conventional selection methods for TEbMs mainly rely on trial-and-error, which is time-consuming and does not reveal the underlying mechanisms. In this study, a new design principle for selecting TEbMs based on thermo–electric–mechanical coupling is proposed. By combining the phase diagram predictions with the thermal expansion coefficients and electrical resistivities of the potential reactants, the Ni2SbTe2 and NiTe2 compounds are identified as ideal TEbMs for (Bi,Sb)2Te3 and Bi2(Te,Se)3, respectively, leading to interfaces with high thermal stability, low contact resistivity, and high strength. The fabricated thermoelectric generator achieves a competitive conversion efficiency of 7.1% and a power density of 0.49 W cm−2 at hot-side and cold-side temperatures of 523 and 296 K, respectively. Moreover, performance degradation is negligible after 200 h of cycling. This work demonstrates progress toward stable high-performance service, provides the foundation for applications in low-grade heat recovery, and offers new insights for more thermoelectric generators.

To elucidate the mechanism of morphology regulation in the blade-coated active layer to obtain high efficiency, three analogous acceptors (Y6, L8-BO, and L8-BO-4Cl) are systematically compared. Benefiting from the unique molecular packing of L8-BO-4Cl and its weak molecule-interaction with toluene, the air-blade-coated D18/L8-BO-4Cl-based device yields an outstanding power-conversion efficiency of 19.31%.

Abstract

Understanding the unique features of photovoltaic materials in high-performance blade-coated organic solar cells (OSCs) is critical to narrow the device performance difference between spin-coating and blade-coating methods. In this work, it is clarified that the molecular packing of acceptor and molecule-solvent interaction plays an essential role in determining the photovoltaic performance of blade-coated layer-by-layer OSCs. It is demonstrated that the unique dimer packing feature of L8-BO-4Cl can lead to lower excited energy (∆E S1) and dominant J-aggregates in the blade-coated film compared to the analogs of Y6 and L8-BO. Meanwhile, the weaker molecule-solvent interaction between L8-BO-4Cl and toluene is in favor of forming prominent J-aggregation in blade-coated film, contributing to a more compact π-stacking than Y6 and L8-BO. Additionally, the blade-coated D18/L8-BO-4Cl film shows more defined interpenetrating networks with clearer donor-acceptor interfaces than D18/Y6 and D18/L8-BO, facilitating improved charge extraction and suppressed charge recombination. As a result, the air-blade-coated layer-by-layer device based on D18/L8-BO-4Cl yields a remarkable power-conversion efficiency (PCE) of 19.31% without any additive and post-treatment, while much lower PCEs of 7.01% and 16.47% are obtained in the device based on D18/Y6 and D18/L8-BO, respectively. This work offers an effective approach to developing highly efficient air-blade-coated layer-by-layer OSCs.

Light-based biofabrication is typically performed with single wavelength light sources and within benchtop devices. This work demonstrates FaSt-Light (Fiber-assisted Structured Light) as a new approach to achieve multiwavelength image projection using flexible image guide fibers, which enables a variety of applications for in situ biofabrication.

Abstract

Light-based biofabrication techniques have revolutionized the field of tissue engineering and regenerative medicine. Specifically, the projection of structured light, where the spatial distribution of light is controlled at both macro and microscale, has enabled precise fabrication of complex three dimensional structures with high resolution and speed. However, despite tremendous progress, biofabrication processes are mostly limited to benchtop devices which limit the flexibility in terms of where the fabrication can occur. Here, a Fiber-assisted Structured Light (FaSt-Light) projection apparatus for rapid in situ crosslinking of photoresins is demonstrated. This approach uses image-guide fiber bundles which can project bespoke images at multiple wavelengths, enabling flexibility and spatial control of different photoinitiation systems and crosslinking chemistries and also the location of fabrication. Coupling of different sizes of fibers and different lenses attached to the fibers to project small (several mm) or large (several cm) images for material crosslinking is demonstrated. FaSt-Light allows control over the cross-section of the crosslinked resins and enables the introduction of microfilaments which can further guide cellular infiltration, differentiation, and anisotropic matrix production. The proposed approach can lead to a new range of in situ biofabrication techniques which improve the translational potential of photofabricated tissues and grafts.

In the past few years, self-assembled molecules (SAMs) have ushered in a new era of interface engineering for perovskite solar cells. Herein, the recent progresses of co-SAM, namely two SAMs with synergy, are comprehensively summarized and analyzed, focusing on topics including deposition methods and design principles, while further challenges about mechanisms, materials, and applications are also outlined.

Abstract

Perovskite solar cells (PSCs) have rapidly gained prominence as a leading candidate in the realm of solution-processable third-generation photovoltaic (PV) technologies. In the high-efficiency inverted PSCs, self-assembled monolayers (SAMs) are often used as hole-selective layers (HSLs) due to the advantages of high transmittance, energy level matching, low non-radiative recombination loss, and tunable surface properties. However, SAMs have been recognized to suffer from some shortcomings, such as incomplete coverage, weak bonding with substrate or perovskite, instability, and so on. The combination of different SAMs or so-called co-SAM is an effective strategy to overcome this challenge. In this Perspective, the latest achievements in molecule design, deposition method, working principle, and application of the co-SAM are discussed. This comprehensive overview of milestones in this rapidly advancing research field, coupled with an in-depth analysis of the improved interface properties using the co-SAM approach, aims to offer valuable insights into the key design principles. Furthermore, the lessons learned will guide the future development of SAM-based HSLs in perovskite-based optoelectronic devices.

Advanced Materials, Volume 37, Issue 17, April 28, 2025.

Biomimetic Isotropic Omnidirectional Intelligent Strain Sensor

Inspired by human fingerprints, an isotropic omnidirectional strain sensor in a heterogeneous skin-compatible soft substrate is proposed. The design as an involute of a circle structure achieves hypersensitivity and enables intelligent direction discrimination ability for applications in healthcare, soft robotics and more. More details can be found in article number 2420322 by Muzi Xu, Luigi G. Occhipinti and co-workers.

Phase Transformation of Titanium Diselenide Devices

In article number 2418557, Wen-Wei Wu, and co-workers systematically investigate the phase transformation of titanium diselenide devices using in-situ transmission electron microscopy. Their study reveals a bias-induced phase transformation driven by titanium self-intercalation, transitioning from hexagonal TiSe2 to the orthorhombic Ti9Se2 conducting phase. These findings offer valuable insights into the structural and electronic dynamics of 1T-TiSe2, highlighting its potential for future applications in charge-density-waves-based devices.

Light-Driven Artificial Cell Micromotors

Light-driven artificial cell-based micromotors (Vesical@MoS2-ATPase) are developed for the treatment of degenerative osteoarthritis. The motors combined with ATPase can be directed to the inflammation site under light conditions and continuously release ATP for repairing damaged chondrocytes. More details can be found in article number 2416349 by Fei Peng, Yingfeng Tu, and co-workers.

Light-Driven Micromachines with Motion Transfer in 3D

In article number 2417742, Shuailong Zhang, Jiafang Li, and co-workers present light-driven multi-component micromachines that facilitate 3D motion transfer across different planes. These micromachines, fabricated using standard photolithography combined with direct laser writing, are assembled and actuated via programmable light patterns within an optoelectronic tweezers system. Utilizing charge-induced repulsion and dielectrophoretic levitation effects, the micromachines enable highly efficient mechanical rotation and effective inter-component motion transfer in three dimensions.