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Field-induced Multi-Q⃗ States in a Pyrochlore Heisenberg Magnet

In this talk, I will present a recent work on the J1-J3b classical Heisenberg model on the pyrochlore lattice in the presence of a magnetic field. We construct exact ground states of the model, which are non-coplanar multi-Q⃗ spin configurations with a large magnetic unit cell. Using linear spin wave theory, we show that entropy favours these multi-Q⃗ states at low temperatures in high magnetic fields. This is confirmed by Monte Carlo simulations, which we also use to map out a phase diagram. Lastly, we calculate the zero-temperature dynamical structure factor. Besides the usual Goldstone modes associated with the ordering Q⃗s, we find high-intensity gapless modes at momenta where there are no Bragg peaks.

• Speaker: Cecilie Glittum (Helmholtz-Zentum Berlin)
• Thursday 27 March 2025, 14:00-15:30
• Venue: TCM Seminar Room.
• Series: Theory of Condensed Matter; organiser: Bo Peng.

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Surgical data using LLMs

Abstract not available

• Speaker: Hugo Georgenthum
• Friday 21 March 2025, 17:00-17:45
• Venue: Lecture Theatre 2, Computer Laboratory, William Gates Building.
• Series: Foundation AI; organiser: Pietro Lio.

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Asymmetry in Supposedly Equivalent Facts: Pre-training Bias in Large Language Models

Understanding and mitigating hallucinations in Large Language Models (LLMs) is crucial for ensuring reliable content generation. While previous research has primarily focused on “when” LLMs hallucinate, our work explains “why” and directly links model behaviour to the pre-training data that forms their prior knowledge. Specifically, we demonstrate that an asymmetry exists in the recognition of logically equivalent facts, which can be attributed to frequency discrepancies of entities appearing as subjects versus objects. Given that most pre-training datasets are inaccessible, we leverage the fully open-source OLMo series by indexing its Dolma dataset to estimate entity frequencies. Using relational facts (represented as triples) from Wikidata5M, we construct probing datasets to isolate this effect. Our experiments reveal that facts with a high-frequency subject and a low-frequency object are better recognised than their inverse, despite their logical equivalence. The pattern reverses in low-to-high frequency settings, and no statistically significant asymmetry emerges when both entities are high-frequency. These findings underscore the influential role of pre-training data in shaping model predictions and provide insights for inferring the characteristics of pre-training data in closed or partially closed LLMs.

• Speaker: Zifeng Ding (University of Cambridge)
• Friday 09 May 2025, 12:00-13:00
• Venue: Room FW26 with Hybrid Format. Here is the Zoom link for those that wish to join online: https://cam-ac-uk.zoom.us/j/4751389294?pwd=Z2ZOSDk0eG1wZldVWG1GVVhrTzFIZz09.
• Series: NLIP Seminar Series; organiser: Suchir Salhan.

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“Imaging the Immune System in Tissue Repair”

This Cambridge Immunology and Medicine Seminar will take place on Thursday 8 May 2025, starting at 4:00pm, in the Ground Floor Lecture Theatre, Jeffrey Cheah Biomedical Centre (JCBC)

Speaker: Professor Paul Kubes, Cumming School of Medicine, University of Calgary

Title: “Imaging the Immune System in Tissue Repair”

Abstract: Using a very simple model of tissue injury where a thermal probe is touched to the surface of a tissue and kills about 1000 cells has unveiled a very complex series of immune events that lead to complete repair in tissues like the liver.  Neutrophils enter the site, clear the debris and leave again via the vasculature while monocytes and iNKT cells surround the injury and slowly the monocytes convert to a repair phenotype before entering and working with stellate cells to help to return the structure back to homeostasis.  The outer compartment where the mesothelium has to regrow requires that peritoneal macrophages attach to the injury site take on a repair phenotype with the help of peritoneal mast cells and aid in repair. Some of these same principles apply to chronic injury  and cancer. 

Host: Tim Halim, CRUK Cambridge

Refreshments will be available following the seminar.

• Speaker: Professor Paul Kubes, Cumming School of Medicine, University of Calgary
• Thursday 08 May 2025, 16:00-17:00
• Venue: Lecture Theatre, Jeffrey Cheah Biomedical Centre, Cambridge Biomedical Campus.
• Series: Cambridge Immunology Network Seminar Series; organiser: Ruth Paton.

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The sluggish water-splitting step hinders the advancement of alkaline hydrogen evolution reaction (HER), making the design of efficient water-splitting active sites critical. The MgO x and MoO y on the atomically thin Ru metallene can cooperatively promote the adsorption–dissociation of water molecules, greatly promoting the efficiency of alkaline HER.

Abstract

Ruthenium (Ru) is considered as a promising catalyst for the alkaline hydrogen evolution reaction (HER), yet its weak water adsorption ability hinders the water splitting efficiency. Herein, a concept of introducing the oxygenophilic MgO x and MoO y species onto amorphous Ru metallene is demonstrated through a simple one-pot salt-templating method for the synergic promotion of water adsorption and splitting to greatly enhance the alkaline HER electrocatalysis. The atomically thin MgO x and MoO y species on Ru metallene (MgO x /MoO y -Ru) show a 15.3-fold increase in mass activity for HER at the potential of 100 mV than that of Ru metallene and an ultralow overpotential of 8.5 mV at a current density of 10 mA cm−2. It is further demonstrated that the MgO x /MoO y -Ru-based anion exchange membrane water electrolyzer can achieve a high current density of 100 mA cm−2 at a remarkably low cell voltage of 1.55 V, and exhibit excellent durability of over 60 h at a current density of 500 mA cm−2. In situ spectroscopy and theoretical simulations reveal that the co-introduction of MgO x and MoO y enhances interfacial water adsorption and splitting by promoting adsorption on oxidized Mg sites and lowering the dissociation energy barrier on oxidized Mo sites.

Efficiency and scintillation velocity are critical for high-energy and medical physics. These parameters, typically conflicting in conventional scintillators, are simultaneously optimized by exploiting the giant oscillator strength of CsPbBr3 nanocrystals, leading to radiatively accelerated (multi)excitonic emission with unity efficiency without detrimental light transport losses in polymeric nanocomposites. This opens up interesting developments in fast-timing radiation detection based on colloidal nanocrystals.

Abstract

Efficiency and emission rate are two traditionally conflicting parameters in radiation detection, and achieving their simultaneous maximization can significantly advance ultrafast time-of-flight (ToF) technologies. In this study, it is demonstrated that this goal is attainable by harnessing the giant oscillator strength (GOS) inherent to weakly confined perovskite nanocrystals, which enables superradiant scintillation under mildly cryogenic conditions that align seamlessly with ToF technologies. It is shown that the radiative acceleration due to GOS encompasses both single and multiple exciton dynamics arising from ionizing interactions, further enhanced by suppressed non-radiative losses and Auger recombination at 80 K. The outcome is ultrafast scintillation with 420 ps lifetime and light yield of ≈10 000 photons/MeV for diluted NC solutions, all without non-radiative losses. Temperature-dependent light-guiding experiments on test-bed nanocomposite scintillators finally indicate that the light-transport capability remains unaffected by the accumulation of band-edge oscillator strength due to GOS. These findings suggest a promising pathway toward developing ultrafast nanotechnological scintillators with optimized light output and timing performance.

Atomic layer modulation is instrumental in optimizing catalytic kinetics for obtaining highly active photocatalysts. A precise atomic layer regulation strategy is proposed to realize the individual modulation of the surface In–S layer in ZnIn2S4, which creates deeper hybridized electronic states of Ni 3d–S 3p to optimize H* adsorption/desorption and maximize surface catalytic benefits for the hydrogen evolution reaction.

Abstract

Solar-driven hydrogen production is significant for achieving carbon neutrality but is limited by unsatisfactory surface catalytic reaction kinetics. Layer regulation can impact carrier transmission or catalytic behavior, but the specific effects on the oxygen or hydrogen evolution reaction (OER or HER) remain unclear, and atomic layer level modulation for maxing HER is challenging. Here the distinct roles of modulated Zn–S or In–S surface layers in ZnIn2S4 (ZIS) for the OER and HER, respectively, are disentangled. Moreover, the extensive characterizations and computational results demonstrate that stressful environments enable individual modulation and introduce Ni into the surface In–S layer rather than the easily alterable Zn–S layer, creating deeper hybridized electronic states of Ni 3d–S 3p, optimizing H* adsorption/desorption, and maximizing surface catalytic benefits for the HER. Consequently, the optimized ZIS exhibited a photocatalytic hydrogen production rate of up to 18.19 mmol g−1 h−1, ≈32 times higher than pristine ZIS. This investigation expands the application scenarios of ultrasonic technology and inspires other precise control types, such as defects and crystal plane engineering, etc.

The schematic representation highlights the essential components for developing a 3D bioprinted glioblastoma model. It includes key microenvironmental factors, biomaterials, and crosslinking techniques. The integration of bioprinting strategies with GBM-on-a-chip models enables the creation of dynamic, physiologically relevant models. A Quality-by-Design (QbD) roadmap can ensure consistent 3D bioprinting models focusing on critical bioprinting processes and material properties.

Abstract

Conventional in vitro models fail to accurately mimic the tumor in vivo characteristics, being appointed as one of the causes of clinical attrition rate. Recent advances in 3D culture techniques, replicating essential physical and biochemical cues such as cell–cell and cell–extracellular matrix interactions, have led to the development of more realistic tumor models. Bioprinting has emerged to advance the creation of 3D in vitro models, providing enhanced flexibility, scalability, and reproducibility. This is crucial for the development of more effective drug treatments, and glioblastoma (GBM) is no exception. GBM, the most common and deadly brain cancer, remains a major challenge, with a median survival of only 15 months post-diagnosis. This review highlights the key components needed for 3D bioprinted GBM models. It encompasses an analysis of natural and synthetic biomaterials, along with crosslinking methods to improve structural integrity. Also, it critically evaluates current 3D bioprinted GBM models and their integration into GBM-on-a-chip platforms, which hold noteworthy potential for drug screening and personalized therapies. A versatile development framework grounded on Quality-by-Design principles is proposed to guide the design of bioprinting models. Future perspectives, including 4D bioprinting and machine learning approaches, are discussed, along with the current gaps to advance the field further.

The application of 2D perovskite materials in indoor photovoltaic field is studied. By constructing DJ/RP perovskite heterojunction, an optimal balance between defect passivation and carrier transport is achieved. Ultimately, the 2D PSCs attain a PCE of 30.30%, with working stability improved by a factor of 20 compared to 3D PSCs, demonstrating their significant potential in future indoor photovoltaic technology.

Abstract

2D perovskite materials are ideal candidates for indoor photovoltaic (IPV) applications due to their tunable bandgap, high absorption coefficients, and enhanced stability. However, attaining uniform crystallization and overcoming low carrier mobility remain key challenges for 2D perovskites, limiting their overall performance. In this study, a 2D perovskite light-absorbing layer is constructed using a Dion–Jacobson (DJ)-phase EDA(FA)4Pb5I16 (n = 5) and introduced butylammonium iodide (BAI) for interface modification, thereby creating a novel DJ/Ruddlesden–Popper (RP) dual 2D perovskite heterostructure. By adjusting the thickness of the BAI-based perovskite layer, the relationship between interfacial defect states and carrier mobility is investigated under varying indoor light intensities. The results indicate that, by achieving a balance between interfacial defect passivation and carrier transport, the optimized 2D perovskite device reaches a power conversion efficiency (PCE) of 30.30% and an open-circuit voltage (VOC) of 936 mV under 1000 lux (3000 K LED). 2D-DJ/RP perovskite IPV exhibits a twentyfold increase in T90 lifetime compared to 3D perovskite devices. It is the first time to systematically study 2D perovskites in IPV applications, demonstrating that rationally designed and optimized 2D perovskites hold significant potential for fabricating high-performance indoor PSCs.

This study reports the discovery of a stable γ-phase in Cu6Te3- x S1+ x , achieving high thermoelectric performance with a Seebeck coefficient up to 200 µVK⁻¹ and ultralow thermal conductivity (≈0.25 Wm⁻¹K⁻¹). The material eliminates phase transitions, exhibits a zT of ≈1.1 at 500 K, and offers a cost-effective, eco-friendly alternative for waste heat recovery and cooling applications.

Abstract

Copper-based chalcogenides are cost-effective and environmentally friendly thermoelectric (TE) materials for waste heat recovery. Despite demonstrating excellent thermoelectric performance, binary Cu2 X (X = S, Se, and Te) chalcogenides undergo superionic phase transitions above room temperature, leading to microstructural evolution and unstable properties. In this work, a new γ-phase of Cu6Te3- x S1+ x (0 < x ≤ 1) is discovered, a narrow-bandgap semiconductor with outstanding thermoelectric performance and high stability. By substituting Te with S in metallic Cu6Te3S, the crystal symmetry is modified and structural phase transitions are eliminated. The γ-phase exhibits a significantly higher Seebeck coefficient of up to 200 µVK−1 compared to 8.8 µVK−1 for Cu6Te3S at room temperature due to optimized carrier concentration and increased effective mass. Cu6Te3- x S1+ x materials also demonstrate ultralow thermal conductivity (≈0.25 Wm−1K−1), which, in concert with improved power factors, enables a high zT of ≈1.1 at a relatively low temperature of 500 K. Unlike most Cu-based chalcogenides, the γ-phase exhibits excellent transport property stability across multiple thermal cycles, making it a cost-effective and eco-friendly alternative to Bi2Te3-based materials. The developed Cu6Te3- x S1+ x is a promising candidate for thermoelectric converters in waste heat recovery, and its potential can be further extended to cooling applications through carrier concentration tuning.

Anisotropic microcarriers (AMs) have gained prominence for their morphological versatility. This review synthesizes two decades of advances in AM development, from fabrication strategies to multifunctional biomedical applications (cell coculture, multidrug delivery, tissue scaffolds, and 3D bioprinting). Systematic analysis of morphology-dependent effects underscores opportunities for optimizing AM utilization and establishing morphology-driven innovation frameworks in biomedicine.

Abstract

Anisotropic microcarriers (AMs) have attracted increasing attention. Although significant efforts have been made to explore AMs with various morphologies, their full potential is yet to be realized, as most studies have primarily focused on materials or fabrication methods. A thorough analysis of the interactional and interdependent relationships between these factors is required, along with proposed countermeasures tailored for researchers from various backgrounds. These countermeasures include specific fabrication strategies for various morphologies and guidelines for selecting the most suitable AM for certain biomedical applications. In this review, a comprehensive summary of AMs, ranging from their fabrication methods to biomedical applications, based on the past two decades of research, is provided. The fabrication of various morphologies is investigated using different strategies and their corresponding biomedical applications. By systematically examining these morphology-dependent effects, a better utilization of AMs with diverse morphologies can be achieved and clear strategies for breakthroughs in the biomedical field are established. Additionally, certain challenges are identified, new frontiers are opened, and promising and exciting opportunities are provided for fabricating functional AMs with broad implications across various fields that must be addressed in biomaterials and biotechnology.

A full-scale field-free perpendicular magnetization switching driven by spin-orbit torque (SOT) is achieved by employing an ultrathin type-II Dirac semimetal, Pt3Sn. The generation of unconventional SOT is attributed to the spin texture of the topological surface state on the Pt3Sn (111) surface with a z-polarized spin component. This study positions the Dirac semimetals, such as Pt3Sn, as promising spin sources for integration into advanced spintronic devices.

Abstract

Spin-orbit torque (SOT) induced by current is a promising approach for electrical manipulation of magnetization in advancing next-generation memory and logic technologies. Conventional SOT-driven perpendicular magnetization switching typically requires an external magnetic field for symmetry breaking, limiting practical applications. Recent research has focused on achieving field-free switching through out-of-plane SOT, with the key challenge being the exploration of new spin source materials that can generate z-polarized spins with high charge-to-spin conversion efficiency, structural simplicity, and scalability for large-scale production. This study demonstrates field-free perpendicular switching using an ultrathin type-II Dirac semimetal Pt3Sn layer with a topological surface state. Density functional theory calculations reveal that the unconventional SOT originates from a spin texture with C3v symmetry, leading to significant z-polarized spin accumulation in the Pt3Sn (111) surface, enabling the deterministic switching of perpendicular magnetization. These results highlight the potential of Dirac semimetals like Pt3Sn as scalable and efficient spin sources, facilitating the development of low-power, high-density spintronic memory and logic devices.

This study introduces a multimodal nonlinear microscopy approach using upconverting nanoparticles (UCNPs) under continuous-wave excitation. The UCNPs exhibit high-order nonlinear optical responses, enabling deep-tissue 3D imaging, video-rate wide-field imaging, and depth-selective photomodulation. High-resolution in vivo imaging of mouse cerebrovascular networks is demonstrated, highlighting the potential for cost-effective bioimaging and targeted phototherapy applications.

Abstract

Nonlinear microscopy provides excellent depth penetration and axial sectioning for 3D imaging, yet widespread adoption is limited by reliance on expensive ultrafast pulsed lasers. This work circumvents such limitations by employing rare-earth doped upconverting nanoparticles (UCNPs), specifically Yb3+/Tm3+ co-doped NaYF4 nanocrystals, which exhibit strong multimodal nonlinear optical responses under continuous-wave (CW) excitation. These UCNPs emit multiple wavelengths at UV (λ ≈ 450 nm), blue (λ ≈ 450 nm), and NIR (λ ≈ 800 nm), whose intensities are nonlinearly governed by excitation power. Exploiting these properties, multi-colored nonlinear emissions enable functional imaging of cerebral blood vessels in deep brain. Using a simple optical setup, high resolution in vivo 3D imaging of mouse cerebrovascular networks at depths up to 800 µmm is achieved, surpassing performance of conventional imaging methods using CW lasers. In vivo cerebrovascular flow dynamics is also visualized with wide-field video-rate imaging under low-powered CW excitation. Furthermore, UCNPs enable depth-selective, 3D-localized photo-modulation through turbid media, presenting spatiotemporally targeted light beacons. This innovative approach, leveraging UCNPs' intrinsic nonlinear optical characteristics, significantly advances multimodal nonlinear microscopy with CW lasers, opening new opportunities in bio-imaging, remote optogenetics, and photodynamic therapy.

A finger-shaped tactile sensor inspired by human fingers is developed, capable of simultaneous normal and shear force detection and 98.33% accurate material identification. Integrated into a robot hand and arm system, it enables real-time detection of gripping force, material identification, advancing haptic sensing in robotics.

Abstract

Multimodal tactile perception is crucial for advancing human–computer interaction, but real-time multidimensional force detection and material identification remain challenging. Here, a finger-shaped tactile sensor (FTS) based on the triboelectric effect is proposed, capable of multidirectional force sensing and material identification. The FTS is composed of an external material identification section and an internal force sensing section. Three materials are embedded into the surface of the silicone shell in the fingerpad, forming single-electrode sensors for material identification. In the force sensing section, the silicone shell's outer surface is coated with conductive silver paste as a shielding layer. The inner wall has four silicone microneedle arrays and a silicone bump, while five silver electrodes are coated on the internal polylactic acid skeleton. The components connect via interlocking structures near the fingernail, allowing localized contact and separation between the silicone shell and skeleton, enabling force direction detection through signals from the five electrodes. Additionally, the outer sensors achieve 98.33% accuracy in recognizing 12 materials. Furthermore, integrated into a robotic hand, the FTS enables real-time material identification and force detection in an intelligent sorting environment. This research holds great potential for applications in tactile perception for intelligent robotics.

Surgical data using LLMs

Abstract not available

• Speaker: Speaker to be confirmed
• Friday 21 March 2025, 17:00-17:45
• Venue: Lecture Theatre 2, Computer Laboratory, William Gates Building.
• Series: Foundation AI; organiser: Pietro Lio.

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Self or non-self? Detection of nucleic acids in the endolysosome

This Cambridge Immunology and Medicine Seminar will take place on Thursday 1 May 2025, starting at 4:00pm, in the Ground Floor Lecture Theatre, Jeffrey Cheah Biomedical Centre (JCBC)

Speaker: Professor Veit Hornung, Gene Center and Department of Biochemistry, University of Munich

Title: ‘Self or non-self? Detection of nucleic acids in the endolysosome’

Abstract: A central function of our innate immune system is to detect microbial pathogens by the presence of their nucleic acid genomes or their transcriptional or replicative activity. In mammals, a receptor-based system – represented by pattern recognition receptors (PRRs) – is primarily responsible for the detection of “non-self” nucleic acids. In recent years, tremendous progress has been made in identifying the key sensing and signaling components required for this complex task. The first group of PRRs identified as nucleic acid sensing receptors are the toll-like receptors (TLRs). TLRs are expressed as transmembrane receptors with their ligand binding domain facing either the extracellular space or the luminal compartment. A distinct evolutionary subset of TLRs is located in the endolysosomal compartment, which in the human system includes TLR7 , TLR8 and TLR9 . While TLR9 recognizes single-stranded DNA with unmethylated CG motifs, which are indeed suppressed in the host genome, TLR7 and TLR8 have evolved to recognize RNA degradation products. Although there has been considerable research on RNA -sensing TLRs, our understanding of their capability to differentiate between non-self and self-RNA remains limited, particularly considering the prevalence of self-RNA in the endolysosomal compartment. In this talk, I will provide an update on our recent work on this topic and present some novel insights into how TLR7 and TLR8 discriminate self from non-self.

Host: Felix Randow, MRC -LMB, Cambridge

Refreshments will be available following the seminar.

• Speaker: Prof. Dr. Veit Hornung, Gene Center Munich
• Thursday 01 May 2025, 16:00-17:00
• Venue: Max Perutz Lecture Theatre, MRC LMB, Francis Crick Avenue, Cambridge CB2 0QH .
• Series: Cambridge Immunology Network Seminar Series; organiser: Ruth Paton.

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Raphael Mattiuz, Post-doctoral Fellow in Immunobiology, Mount Sinai

This Cambridge Immunology and Medicine Seminar will take place on Thursday 4 April 2025, starting at 4:00pm, in the Ground Floor Lecture Theatre, Jeffrey Cheah Biomedical Centre (JCBC)

Speaker: Raphael Mattiuz, Post-doctoral Fellow in Immunobiology, Mount Sinai

Title: TBC

Host:

Refreshments will be available following the seminar.

• Speaker: Raphael Mattiuz, Post-doctoral Fellow in Immunobiology, Mount Sinai
• Thursday 10 April 2025, 13:00-14:00
• Venue: Lecture Theatre, Jeffrey Cheah Biomedical Centre, Cambridge Biomedical Campus.
• Series: Cambridge Immunology Network Seminar Series; organiser: Ruth Paton.

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Joint ChemBio and Synthesis RIG Seminar - Chemical Biology Tools for Measuring Drug Delivery

Abstract not available

• Speaker: Joshua Kritzer (Tufts University)
• Friday 23 May 2025, 14:00-15:00
• Venue: Dept. of Chemistry, Wolfson Lecture Theatre.
• Series: Synthetic Chemistry Research Interest Group; organiser: Jasmine Mitchell.

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Energy Environ. Sci., 2025, Accepted Manuscript
DOI: 10.1039/D5EE00430F, Paper Open Access &nbsp This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence.Junpeng Sun, Jialong Shen, Huadong Qi, Mei Sun, Yuhang Lou, Yu Yao, Xianhong Rui, Yu Shao, Xiaojun Wu, Hai Yang, Yan Yu
Lithium-rich manganese-based oxides (LRMO) are a promising next-generation candidate cathode material, offering a high discharge capacity exceeding 300 mAh g−1. This exceptional capacity is attributed to the synergistic redox activity...
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Energy Environ. Sci., 2025, Accepted Manuscript
DOI: 10.1039/D5EE00149H, PaperZezhang Wang, Tianfei Xu, Nan Li, Zhen Chang, Jing Shan, Yong Wang, Minfang Wu, Fengwei Xiao, Shengzhong Frank Liu, Wanchun Xiang
Inverted inorganic perovskite solar cells (PSCs) are ideal top cells for tandem configurations due to their ideal bandgap and excellent thermal stability. However, water-induced rapid crystallization during inorganic perovskite film...
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