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Quasi-periodic metamaterials combine stiffness and large-strain deformability, overcoming limitations of traditional stretching-dominated periodic designs that are prone to global buckling instabilities and catastrophic layer collapses. By leveraging non-uniform force chains, they achieve high isotropic stiffness, stable deformation, and remarkable failure resistance. Supported by numerical and experimental results, these advances open pathways for low-density applications in impact resistance and energy absorption.

Architected materials achieve unique mechanical properties through precisely engineered microstructures that minimize material usage. However, a key challenge of low-density materials is balancing high stiffness with stable deformability up to large strains. Current microstructures, which employ slender elements such as thin beams and plates arranged in periodic patterns to optimize stiffness, are largely prone to instabilities, including buckling and brittle collapse at low strains. This challenge is here addressed by introducing a new class of aperiodic architected materials inspired by quasicrystalline lattices. Beam networks derived from canonical quasicrystalline patterns, such as the Penrose tiling in two dimensions and icosahedral quasicrystals (IQCs) in three dimensions, are shown to create stiff, stretching-dominated topologies with non-uniform force chain distributions, effectively mitigating the global instabilities observed in periodic designs through distributed localized buckling instabilities. Numerical and experimental results confirm the effectiveness of these designs in combining stiffness and stable deformability at large strains, representing a significant advancement in the development of low-density metamaterials for applications requiring high impact resistance and energy absorption. These results demonstrate the potential of deterministic quasi-periodic topologies to bridge the gap between periodic and random structures, while branching toward uncharted territory in the property space of architected materials.

A broadband polycrystalline lithium niobate platform is developed for highly versatile and scalable fabrication of nonlinear metasurfaces. This work demonstrates simultaneous second harmonic generation and wavefront-shaping via a metalens on this platform. The high effective optical nonlinearity enables broadband frequency doubled light focusing for power density enhancement from near-ultraviolet to near-infrared spectral range.

Miniaturizing nonlinear optical components is essential for integrating advanced light manipulation into compact photonic devices, enabling scalable and cost-effective applications. While monocrystalline lithium niobate thin films advance nonlinear nanophotonics, their high inertness limits the design of top-down fabricated nanostructures. A versatile bottom-up fabrication method based on nanoimprint lithography is presented for achieving polycrystalline lithium niobate nanostructures and demonstrate its significant potential for nonlinear metasurfaces. The fabrication enables nearly vertical features and aspect ratios of up to 6 combined, which we combine with a novel solution-derived material with high effective second-order nonlinearity d eff of 5 pm V−1. On this platform, second-harmonic focusing is demonstrated over a broad spectral range from near-ultraviolet to near-infrared, increasing the nonlinear signal intensity by up to 34 times. This method enables the first lithium niobate metalens and expands the field of nonlinear metasurfaces by providing a low-cost, highly scalable fabrication method for engineered nonlinear nanostructures.

Cancer metastasis begins with intravasation, a complex process involving cancer-endothelial interactions. INVADE (Intravasation-on-µDevice), a biomimetic microfluidic platform enables high-throughput analysis of intravasation under controlled conditions. This system reveals distinct invasion modes, an epithelial-mesenchymal transition (EMT) - mesenchymal-epithelial transition (MET) switch, and endothelial suppression of mesenchymal traits. It also uncovers bilateral signaling, highlighting dynamic cancer-endothelial crosstalk with implications for metastasis research. .

Cancer metastasis begins with intravasation, where cancer cells enter blood vessels through complex interactions with the endothelial barrier. Understanding this process remains challenging due to the lack of physiologically relevant models. Here, INVADE (Intravasation-on-µDevice), a biomimetic microfluidic platform, is presented, enabling high-throughput analysis of cancer cell intravasation under controlled conditions. This engineered platform integrates 23 parallel niche chambers with an endothelialized channel, providing both precise microenvironmental control and optical accessibility for real-time visualization. Using this platform, distinct intravasation mechanisms are uncovered: MCF-7 cells exhibit collective invasion, while MDA-MB-231 cells demonstrate an interactive mode with three functionally distinct subpopulations. A previously unknown epithelial-mesenchymal transition (EMT) and mesenchymal-epithelial transition (MET) switch is We discovered during intravasation, where MDA-MB-231 cells initially increase Vimentin expression before undergoing a 2.3 fold decrease over 96 h alongside a 1.5 fold increase in epithelial cell adhesion molecule (EpCAM). Remarkably, endothelial cells directly suppress cancer cell mesenchymal properties, as evidenced by a 4.6 fold reduction in Vimentin expression compared to mono-cultures. Additionally, bilateral cancer-endothelial interactions are revealed, aggressive cancer cells induce significant intercellular adhesion molecule-1 (ICAM-1) upregulation in endothelium. The INVADE platform represents an engineering advancement for studying complex cell–cell interactions with implications for understanding metastatic mechanisms.

A recent article by Barnes and co-workers reported an experimental re-evaluation of earlier work on photoisomerization reactions inside optical cavities under conditions of strong light-matter coupling. They correctly highlight the importance of controlling irradiation conditions from sample to sample where optical cavities are involved. This comment aims to emphasize the great lengths the original study went to ensure exactly this.

Recently, an article by Barnes and co-workers reported an in-depth experimental re-evaluation of the earlier work on photoisomerization reactions inside optical cavities under conditions of strong light-matter coupling. That earlier work, which constituted the first demonstration of ‘polaritonic chemistry’, associated cavity-induced modifications of photoisomerization rates with the emergence of strong light-matter coupling (and the formation of polaritonic states). Barnes and co-workers instead found that cavity-induced changes in light absorption can account for changes in the photochemical reaction rates. While Barnes and co-workers correctly highlight the importance of controlling irradiation conditions from sample to sample where optical cavities are involved, this comment aims to emphasize the great length the original study went to ensure exactly this. The original experimental methods are summarized to point out the significant differences between them and those conducted by Barnes and co-workers. Furthermore, the importance of monochromatic photoexcitation at an isosbestic point rather than using broadband (UV through to IR) irradiation, as well as the careful control for photon flux reaching the molecular layer in all samples, as per the original work, is discussed. Further examination of important issues facing this new and developing domain of Physical Chemistry, is anticipated.

A time-division multiplexing physical unclonable function (TDM-PUF) label based on multicolor phosphorescent carbon dots (CDs) is proposed, which leverages the variations in wavelengths and lifetimes of the phosphorescent CDs to construct time-resolved multidimensional cryptographic protocols. This study provides a competitive anti-counterfeiting label and inspires the development of novel anti-counterfeiting strategies.

Phosphorescent materials offer a promising approach to information encryption due to their long luminescence lifetimes and high signal-to-noise ratios. However, fixed phosphorescent patterns are vulnerable to imitation over time, limiting their effectiveness in advanced encryption. Here, a time-division multiplexing physical unclonable function (TDM-PUF) label utilizing multicolor phosphorescent carbon dots (CDs) is proposed that leverages variations in wavelength and lifetime to construct time-resolved, multidimensional cryptographic protocols. Efficient multi-color phosphorescence in CDs is achieved by enhancing intersystem crossing, suppressing non-radiative transitions through confinement effects, and regulating emission spectra via energy transfer. The random spatial distribution and unpredictable emissions of phosphorescent CDs significantly enhance the complexity of the PUF system, thereby fortifying its defenses against mimicry attacks. Furthermore, this PUF system exhibits multiple optical responses over time, allowing correct information recognition only at specified time nodes, achieving time-resolved anti-counterfeiting. Finally, by segmenting PUF labels based on emission color and time channels, non-overlapping multicolor and multi-time segments are achieved, enabling highly secure time-division multiplexed encryption. The study provides a competitive anti-counterfeiting label and inspires the development of novel anti-counterfeiting strategies.

Understanding the complex interplay between local structure and physical properties is a key challenge in high entropy oxide (HEO) research, particularly concerning electronic transport. This work demonstrates the profound influence of local chemical inhomogeneity and underlying epitaxial strain on the electronic transport properties of HEO thin film with perovskite structure, paving pathways to tailor electronic properties in high-entropy regime.

Understanding the electronic transport properties of thin films of high-entropy oxide (HEO), having multiple elements at the same crystallographic site, is crucial for their potential electronic applications. However, very little is known about the metallic phase of HEOs even in bulk form. This work delves into the interplay between global and local structural distortion and electronic properties of single crystalline thin films of (La0.2Pr0.2Nd0.2Sm0.2Eu0.2)NiO3, which exhibit metal-insulator transition under tensile strain. Employing electron microscopy and elemental resolved electron energy loss spectroscopy, we provide direct evidence of nanoscale chemical inhomogeneities at the rare-earth site, leading to a broad distribution of Ni–O–Ni bond angles. However, the octahedral rotation pattern remains the same throughout. The metallic phase consists of insulating patches with more distorted Ni–O–Ni bond angles, responsible for higher resistance exponents with increased compositional complexity. Moreover, a rare, fully metallic state of HEO thin film is achieved under compressive strain. We further demonstrate a direct correlation between the suppression of the insulating behavior and increased electronic hopping. Our findings provide a foundation for exploring Mott-Anderson electron localization physics in the high-entropy regime.

A core-shell perovskite composite with a highly durable electrochemical activity for oxygen catalysis is developed as an air electrode for reversible protonic ceramic cells (RPCCs) via a unique solid-state reaction. This work also demonstrates a new pathway to developing highly durable air electrode materials for RPCCs technology, accelerating RPCCs’ commercialization.

Reversible protonic ceramic cells (RPCCs) offer a promising pathway to efficient and reversible energy conversion, accelerating the global shift to renewables. However, the RPCCs’ commercialization faces limitations in air electrode materials. Traditional cobalt-based perovskite air electrodes, while effective, suffer from high cost and environmental concerns. Alternative materials, such as SrFeO3-δ (SF)-based perovskites, offer potential, yet durability issues, including thermal-expansion mismatch and mechanical instability, hinder their practical application. Here, a unique solid-state reaction between SF and negative-thermal-expansion (NTE) material is demonstrated to yield a core-shell perovskite composite as a highly durable RPCCs air electrode. Specifically, by calcining a mixture of SF and an NTE material, ZrW2O8 (ZWO), the in situ incorporation of ZWO into the SF lattice is achieved, resulting in a non-closed core-shell composite, comprising single perovskite SraFebZrcWdO3-δ (SP-SFZW) core and B-site cation ordered double perovskite SrxFeyZrmWnO6-δ (DP-SFZW) shell. Both SP-SFZW and DP-SFZW serve as oxygen catalysts, while DP-SFZW shell additionally acts as a thermal expansion suppressor and mechanical support structure, effectively mitigating electrode cracking and delamination from other cell components during RPCC operation. Consequently, the composite electrode demonstrates comparable catalytic activity to SF, coupled with significantly enhanced durability. This work illustrates a novel approach for developing robust RPCCs air electrode.

An AEM-derived proton acceptor-electron donor mechanism is proposed in RuO2 by constructing an interstitial-substitutional mixed solid solution structure (C,Ta-RuO2), in which the interstitial C as the proton acceptor decreases the deprotonation energy barrier, while the substitutional Ta as the electron donor weakens the Ru─O bond covalency, thereby breaking the activity-stability trade-off of RuO2 in acidic OER.

The acidic oxygen evolution reaction (OER) electrocatalysts for proton exchange membrane electrolyzer (PEMWE) often face a trade-off between activity and stability due to inherent linear relationship and overoxidation of metal atoms in highly oxidative environments, while following the conventional adsorbate evolution mechanism (AEM). Herein, a favorable AEM-derived proton acceptor-electron donor mechanism (PAEDM) is proposed in RuO2 by constructing interstitial-substitutional mixed solid solution structure (denoted as C,Ta-RuO2), which can effectively break the activity-stability trade-off of RuO2 in acidic OER. In situ spectroscopy experiments and theoretical calculations reveal that the interstitial C as the proton acceptor reduces the deprotonation energy barrier, enhancing catalytic activity, while the substitutional Ta as the electron donor donates electrons to the Ru sites via bridging oxygen, weakening the Ru─O bond covalency and preventing over-oxidation of surface Ru, thereby ensuring long-term stability. Under the guidance of this mechanism, the optimized C,Ta-RuO2 simultaneously achieves far low overpotential (η10 = 171 mV) and ultra-long stability (over 1300 h) for the acidic OER. More remarkably, a homemade PEMWE using C,Ta-RuO2 as the anode also shows high water splitting performance (1.63 V@1 A cm−2). This work supplies a novel strategy to guide future developments on efficient OER electrocatalysts toward water oxidation.

Breaking Quantum Confinement in Yb3⁺-Doped ZnSe QDs: Surface-energy engineering enables scalable growth beyond the exciton Bohr radius with high-purity blue emission (453 nm), narrow full width at half maximum (FWHM) of 46 nm, and exceptional photoluminescence quantum yield (PLQY) of 67.5%.

Large ZnSe quantum dots (QDs) with an emission peak ≈450 nm hold significant promise for display technologies. However, achieving efficient pure-blue emission through the enlargement of ZnSe nanocrystals remains a significant challenge. In this study, a breakthrough is reported in growing large-size ZnSe QDs well beyond the exciton Bohr radius through Yb3+ doping strategy. Yb3+ doping reduces the surface energy of the ZnSe (220) crystal plane and alleviates interface strain in the ZnSe/ZnS structure, enabling the QDs to grow larger while maintaining enhanced crystal stability. The resulting Yb: ZnSe/ZnS QDs exhibit pure-blue emission at 453 nm, with a full width at half maximum (FWHM) of 46 nm and a high photoluminescence quantum yield (PLQY) of 67.5%. When integrated into quantum dot light-emitting diodes (QLEDs), the devices display electroluminescence (EL) at 455 nm, with an external quantum efficiency (EQE) of 1.35%, and a maximum luminance of 1337.08 cd m−2.

A heterogeneous microgel–hydrogel hybrid is developed to construct a multiscale vascular network through embedded bioprinting and guided vascular morphogenesis. With a high density of hepatocytes, a bioengineered thick vascularized liver tissue model achieves a rapid and promising functional compensation in rats with 85% hepatectomy via direct vascular integration, providing a theraputi paradigm for physiological-related engineered tissue in animals with acute disease.

3D bioprinting of liver tissue with high cell density (HCD) shows great promise for restoring function in cases of acute liver failure, where a substantial number of functional cells are required to perform essential physiological tasks. Direct vascular anastomosis is critical for the successful implantation of these bioprinted vascularized tissues into the host vasculature, allowing for rapid functional compensation and addressing various acute conditions. However, conventional hydrogels used to encapsulate high-density cells often lack the mechanical properties needed to withstand the shear forces of physiological blood flow, often resulting in implantation failure. In this study, a heterogeneous microgel–hydrogel hybrid is developed to carry HCD hepatocytes and support the embedded bioprinting of hierarchical vascular structures. By optimizing the ratio of microgel to biomacromolecule, the covalently crosslinked network offers mechanical integrity and enables direct vascular anastomosis, ensuring efficient nutrient and oxygen exchange. The bioprinted thick, vascularized constructs, containing HCD hepatocytes, are successfully implanted in rats after 85% hepatectomy, leading to swift functional recovery and prolonged survival. This study presents a strategy to enhance regenerative therapy outcomes through advanced bioprinting and vascular integration techniques.

The α-FAPbI3 perovskite, ideal for high-efficiency solar cells, suffers from impurity phases causing defects and instability. Using FAI/MASCN vapors repairs impurities into α-FAPbI3, enhancing charge transport and morphology. This achieves 26.05% efficiency, with large-area devices (24.52% for 1 cm2, 22.35% for 17.1 cm2). Cyclic repair retains 94.3% efficiency after two cycles, significantly boosting device durability.

The photoactive α-phase of formamidinium lead iodide perovskite (α-FAPbI3) is regarded as one of the ideal materials for high-efficiency perovskite solar cells (PSCs) due to its superior optoelectronic properties. However, during the deposition of α-FAPbI3 perovskite films, the presence of impurity phases, such as PbI2 and δ-FAPbI3, can cause the formation of inherent defects, which leads to suboptimal charge transport and extraction properties, as well as inadequate long-term stability in the film's morphology and structure. To address these issues, an impurity phase repair strategy is employed using FAI/MASCN mixed vapors to convert the impurity phases into light-absorbing α-FAPbI3. Meanwhile, this recrystallization process also facilitates the recovery of its characteristic morphology, thereby improving efficiency and enhancing the durability of PSCs. This approach promotes the PSCs to obtain an efficiency of 26.05% (with a certified efficiency of 25.67%, and steady-state PCE of 25.41%). Additionally, this approach is suitable for the fabrication of large-area devices, obtaining a 1 cm2 device with a PCE of 24.52% and a mini-module (with an area of 17.1 cm2) with a PCE of 22.35%. Furthermore, it is found that this strategy enables cyclic repair of aged perovskite films, with the perovskite solar cells retaining ≈ 94.3% of their initial efficiency after two cycles of repair, significantly enhancing the lifetime of the perovskite solar cells.

A self-assembled interface orthogonal strategy is first applied to construct pseudo-planar heterojunction organic photovoltaics with controllable vertical gradient distribution morphology. Introducing low surface-energy N2200 to self-assemble molecular layer on PM6 surface overcomes erosion effect and modulates phase morphology, thus achieving the highest efficiency of 19.86% via air-printing process.

Precisely regulating vertically distributed morphology by blade-coating process is crucial to realize high-performance large-scale pseudo-planar heterojunction organic photovoltaics (OPVs). However, the thermodynamic motion and random diffusion of donor/acceptor (D/A) generated from the differences in surface energy and concentration during sequentially blade-coating process will cause great challenges for obtaining ideal active layer morphology. Herein, this study have proposed a self-assembled interface orthogonal strategy by introducing low surface energy guest (N2200) to form protective layer on PM6 surface, which counteracts erosion from orthogonal solution of acceptor to enhance continuity of D/A phases, thus promoting directional carrier migration and effectively suppressing energetic disorder. Finally, N2200-modified device achieves the highest power conversion efficiency (PCE) of 19.86%, and large-area module (16.94 cm2) exhibits exceptional PCE (16.43%). This investigation presents innovative insights into morphology issue triggered by molecular motion and provides an effective method for air-printing large-scale OPVs with precisely controlled morphology based on non-halogenated solvent.

A novel copper-sulfur-nitrogen cluster Cu8SN is synthesized by using a strong anchoring ability protective ligand (2-mercaptopyrimidine) and a relatively weak monodentate tert-butyl mercaptan ligand. Then, a precise thermal-resection strategy is applied to only peel the targeted weak ligands off, which induces a structural transformation of the initial Cu8SN cluster into a new and more stable Cu–S–N cluster (Cu8SN–T). Cu8SN–T exhibits greatly enhanced light-harvesting abilities and full-spectrum responsive overall CO2 photoreduction with ≈100% CO2-to-CO selectivity.

Atomically precise copper clusters are desirable as catalysts for elaborating the structure–activity relationships. The challenge, however, lies in their tendency to sinter when protective ligands are removed, resulting in the destruction of the structural integrity of the model system. Herein, a copper-sulfur-nitrogen cluster [Cu8(StBu)4(PymS)4] (denoted as Cu8SN) is synthesized by using a mixed ligand approach with strong chelating 2-mercaptopyrimidine (PymSH) ligands and relatively weak monodentate tert-butyl mercaptan ligands. A precise thermal-resection strategy is applied to selectively peel only the targeted weak ligands off, which induces a structural transformation of the initial Cu8 cluster into a new and more stable Cu–S–N cluster [Cu8(S)2(PymS)4] (denoted as Cu8SN-T). The residual bridging S2− within the metal core forms asymmetric Cu-S species with a near-infrared (NIR) response, which endows Cu8SN-T with the capability for full-spectrum responsive CO2 photoreduction, achieving a ≈100% CO2-to-CO selectivity. Especially for NIR-driven CO2 reduction, it has a CO evolution of 42.5 µmol g−1 under λ > 780 nm. Importantly, this work represents the first NIR light-responsive copper cluster for efficient CO2 photoreduction and opens an avenue for the precise manipulation of metal cluster structures via a novel thermolysis strategy to develop unprecedented functionalized metal cluster materials.

Mike Gordon’s Higher-Order Logic (HOL) is one of the most important logical foundations for interactive theorem proving. The standard semantics of HOL , due to Andrew Pitts, employs a downward closed universe of sets, and interprets HOL ’s Hilbert choice operator via a global choice function on the universe.

In this talk, I introduce a natural Henkin-style notion of general model corresponding to the standard models. By following the Henkin route of proving completeness, I discover an enrichment of HOL deduction that is sound and complete w.r.t. these general models. Variations of my proof also yield completeness results for weaker deduction systems located between standard and (fully) enriched HOL deduction, relative to less constrained models.

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• Speaker: Andrei Popescu (University of Sheffield)
• Thursday 15 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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• Speaker: Yashar Ahmadian; Nandini Shiralkar
• Tuesday 15 April 2025, 15:00-16:30
• Venue: CBL Seminar Room, Engineering Department, 4th floor Baker building.
• Series: Computational Neuroscience; organiser: .

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• Speaker: Lukas pertl
• Monday 12 May 2025, 17:00-17:45
• Venue: Lecture Theatre 2, Computer Laboratory, William Gates Building.
• Series: Foundation AI; organiser: Pietro Lio.

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• Speaker: Rajalakshmi Nandakumar, Cornell University
• Tuesday 03 June 2025, 16:00-17:00
• Venue: Online.
• Series: Mobile and Wearable Health Seminar Series; organiser: Cecilia Mascolo.

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• Speaker: Paul Röttger (Bocconi University)
• Friday 16 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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The growing demand for data centre resources and the slower evolution of their hardware have led to clusters operating at high utilisation. In this talk, I will examine how current schedulers perform under such conditions. I will discuss how centralised schedulers struggle to scale under high load due to the significant network traffic caused by continuously transferring up-to-date node data. Conversely, distributed schedulers scale well but lack a global cluster view, leading to suboptimal task allocations. As a result, existing schedulers impose up to three times longer wait times on tail tasks, which increases job completion times.

I will then introduce our work on decentralised scheduling, focusing on performance, scalability, and load balancing. These schedulers have been largely under-explored due to their design complexity. However, we demonstrate that Murmuration, our job-aware decentralised scheduler, achieves high performance under both normal and high load despite its simple approach using approximate load information. It reduces communication overhead between nodes and schedulers while still achieving balanced cluster load distribution. By the end of this talk, I hope to convince you that decentralised schedulers with approximate knowledge strike the right balance between performance and scalability, making them a practical solution for today’s highly utilised data centres.

Bio: Smita Vijayakumar recently completed her PhD from the Department of Computer Science and Technology at the University of Cambridge, under the supervision of Evangelia Kalyvianaki. As a part of her thesis, she developed a novel decentralised scheduling framework to reduce tail task latencies in highly utilised data centres. She has over twelve years of industry experience working on networking, cloud computing, and distributed systems. She also has an MS from The Ohio State University, where her work investigated cloud resource allocation to bottleneck stages for processing streaming applications. Her research has been published in top-tier conferences, and also as a book. She has also been actively involved in mentoring, teaching, and community leadership, including founding Women Who Go, India.

• Speaker: Smita Vijayakumar, Systems Research Group, Cambridge University Computer Laboratory
• Thursday 01 May 2025, 15:00-16:00
• Venue: Computer Lab, FW11 and Online (MS Teams link below).
• Series: Computer Laboratory Systems Research Group Seminar; organiser: Richard Mortier.

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