Nanoscience News (<front>)

Physical-Layer Security of Satellite Communications Links

In recent years, building and launching satellites has become considerably cheaper, making satellite systems more accessible to an expanding user base. This accessibility has led to a diverse array of applications—such as navigation, communications, and earth observation—that depend on satellites. However, hardware limitations and operational considerations often render cryptographic solutions impractical for these systems. Furthermore, the availability of low-cost software-defined radios has made signal capture, injection, and interference attacks more attainable for a wider range of potential attackers.

Therefore, mitigations must be developed for satellites that have already been launched without adequate protections in place. This talk introduces some of our research into how satellite systems are vulnerable, as well as ways to protect these systems.

Bio:

Simon Birnbach is a Senior Research Associate and a Royal Academy of Engineering UK IC Postdoctoral Research Fellow in the Systems Security Lab of Professor Ivan Martinovic in the Department of Computer Science at the University of Oxford. He specialises in the security of cyber-physical systems, with a focus on smart home, aviation, and aerospace security.

• Speaker: Simon Birnbach, University of Oxford
• Tuesday 18 February 2025, 14:00-15:00
• Venue: Webinar & GN06, Computer Laboratory, William Gates Building..
• Series: Computer Laboratory Security Seminar; organiser: Tina Marjanov.

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The exceptional zero conjecture for GL(3)

If E is an elliptic curve over Q with split multiplicative reduction at p, then the p-adic L-function associated with E vanishes at s=1 independently of whether the complex L-function vanishes. In this case, one has an “exceptional zero formula” relating the first derivative of the p-adic L-function to the complex L-function multiplied by a certain L-invariant. This L-invariant can be interpreted in several ways—on the automorphic side for example, L-invariants parameterise part of the p-adic local Langlands correspondence for GL(2)(Q_p).

In this talk, I will discuss an exceptional zero formula for (not necessarily essentially self-dual) regular algebraic, cuspidal automorphic representations of GL(3) which are Steinberg at p. The formula involves an automorphic L-invariant constructed by Gehrmann. Joint work with Daniel Barrera and Chris Williams.

• 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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Synchronization in Navier-Stokes turbulence and its role in data-driven modeling

In Navier-Stokes (NS) turbulence, large-scale turbulent flows determine small-scale flows; in other words, small-scale flows are synchronized to large-scale flows. In 3D turbulence, previous numerical studies suggest that the critical length separating these two scales is determined by the Kolmogorov length. In this talk, I will introduce our theoretical framework for characterizing synchronization phenomena [1]. Specifically, it provides a computational method for the exponential rate of convergence to the synchronized state, and identifies the critical length based on the NS equations via the “transverse” Lyapunov exponent. I will also discuss the synchronization property of 2D NS turbulence and how it differs from the 3D case [2]. These insights into synchronization and critical length scales are essential for developing machine-learning closure models for turbulence, in particular their stable reproducibility [3]. Finally, I will illustrate how “generalized” synchronization is crucial for predicting chaotic dynamics [4].

[1] M. Inubushi, Y. Saiki, M. U. Kobayashi, and S. Goto, Characterizing small-scale dynamics of Navier-Stokes turbulence with transverse Lyapunov exponents: A data assimilation approach, Phys. Rev. Lett. 131, 254001 (2023).

[2] M. Inubushi and C. P. Caulfield (in preparation).

[3] S. Matsumoto, M. Inubushi, and S. Goto, Stable reproducibility of turbulence dynamics by machine learning, Phys. Rev. Fluids 9, 104601 (2024).

[4] A. Ohkubo and M. Inubushi, Reservoir computing with generalized readout based on generalized synchronization, Sci. Rep. 14, 30918 (2024).

• Speaker: Professor Masanobu Inubushi, Tokyo University of Science
• Friday 14 February 2025, 16:00-17:00
• Venue: MR2.
• Series: Fluid Mechanics (DAMTP); organiser: Professor Grae Worster.

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Energy Environ. Sci., 2025, Accepted Manuscript
DOI: 10.1039/D4EE05936K, PaperLin Li, Fagui Dong, PengPeng Miao, Nan He, Bingsen Wang, Xisheng Sun, Jie Miao, Haonan Wang, Dawei Tang
Moisture energy harvesting, which directly converts atmospheric moisture into electricity, emerges as a transformative solution for sustainable power generation. However, freezing-induced ion migration blockage in moisture-electricity generators (MEGs) remains a...
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Utilizing meticulously protected ether molecules, an intermolecular-reinforced ether-based electrolyte is presented to well stabilize the aggressive NaNi1/3Fe1/3Mn1/3O2 cathode at a high cut-off voltage of 4.2 VNa. With this electrolyte, a high-voltage aAhmpere-hour-level pouch cell based on the cathode and hard carbon anode shows excellent long-term cycling stability with 82.8% capacity retention after 800 cycles.

Abstract

To fulfill the requirements for practical applications, it is urgent to boost the gravimetric energy density of sodium-ion batteries. An effective way is to increase the charging voltage of O3-type layered cathodes preferably to 4.2 V versus Na/Na+ (VNa). Nevertheless, it is extremely challenging to achieve stable cycling of the cathodes at such a high cut-off voltage. Here a novel electrolyte strategy to design an intermolecular-reinforced electrolyte (IRE) is presented, utilizing meticulously protected ether molecules, which facilitates stable high-voltage cycling of the commercially viable NaNi1/3Fe1/3Mn1/3O2 (NFM). While the NFM with the IRE exhibits a high specific capacity of ≈158 mAh g−1 at 4.2 VNa (130 mAh g−1 at 4.0 VNa), the aggressive cathode surface can still be effectively stabilized by the formation of favorable thin and inorganic-rich cathode−electrolyte interfaces. Remarkably, under a high cut-off voltage of 4.2 VNa, an industrial ampere-hour-level NFM||hard carbon pouch cell with the IRE electrolyte shows an excellent long-term cycling stability with 82.8% capacity retention after 800 cycles, largely outperforming the localized high-concentration electrolyte (82.9% after 200 cycles).

This article presents a non-destructive molecular encoding approach using hierarchical array of functionalized graphene-based sensors for spatiotemporal analysis of volatile signaling molecules. Combined with deep learning, this method enables real-time imaging and genetic profiling of organoids, deciphering molecular production pathways through specific enzymes and metabolic routes and advancing precision diagnostics and personalized medicine without harmful staining or sample destruction.

Abstract

Organoids mimic human organ function, offering insights into development and disease. However, non-destructive, real-time monitoring is lacking, as traditional methods are often costly, destructive, and low-throughput. In this article, a non-destructive chemical tomographic strategy is presented for decoding cyto-proteo-genomics of organoid using volatile signaling molecules, hereby, Volatile Organic Compounds (VOCs), to indicate metabolic activity and development of organoids. Combining a hierarchical design of graphene-based sensor arrays with AI-driven analysis, this method maps VOC spatiotemporal distribution and generate detailed digital profiles of organoid morphology and proteo-genomic features. Lens- and label-free, it avoids phototoxicity, distortion, and environmental disruption. Results from testing organoids with the reported chemical tomography approach demonstrate effective differentiation between cyto-proteo-genomic profiles of normal and diseased states, particularly during dynamic transitions such as epithelial-mesenchymal transition (EMT). Additionally, the reported approach identifies key VOC-related biochemical pathways, metabolic markers, and pathways associated with cancerous transformations such as aromatic acid degradation and lipid metabolism. This real-time, non-destructive approach captures subtle genetic and structural variations with high sensitivity and specificity, providing a robust platform for multi-omics integration and advancing cancer biomarker discovery.

By virtue of the tailor-made Pt electronic configuration and excellently corrosion-resistant carbon support, the O-PtCo@GCoNC integrating PtCo intermetallic with a Pt-rich shell and highly graphitized carbon exhibits significantly enhanced ORR activity and stability, attaining outstanding performance in H2/air PEMFC, outstripping the United States Department of Energy 2025 target.

Abstract

Exploiting robust and high-efficiency electrocatalysts for sluggish oxygen reduction reaction (ORR) is essential for proton exchange membrane fuel cells (PEMFCs) toward long-term operation for practical applications, yet remains challenging. Herein, the ordered PtCo intermetallic is reported with a Pt-rich shell loaded on a highly graphitized carbon carrier (O-PtCo@GCoNC) prepared by an impregnation annealing strategy. Systematic X-ray spectroscopic, operando electrochemical techniques and theoretical calculations reveal that thanks to the synergistic interaction of the core–shell PtCo intermetallic structure with a tailor-made Pt electronic configuration and highly graphitized carbon, O-PtCo@GCoNC exhibits significantly enhanced activity and stability toward ORR. Crucially, O-PtCo@GCoNC delivers a much-enhanced mass activity of 0.83 A mgPt −1 at 0.9 V versus reversible hydrogen electrode (RHE) in 0.1 m HClO4, which only drops by 26.5% after 70 000 cycles (0.6–1.0 V vs RHE), and 10.8% after 10 000 cycles (1.0–1.5 V vs RHE), apparently overmatching Pt/C (0.19 A mgPt −1, 73.7%, and 63.1%). Moreover, O-PtCo@GCoNC employed as the cathode catalyst in H2/air PEMFC achieves a superb peak power density (1.04 W cm−2 at 2.06 A cm−2), outperforming that of Pt/C (0.86 W cm−2 at 1.79 A cm−2). The cell voltage loss at 0.8 A cm−2 is 28 mV after 30 000 cycles, outstripping the United States Department of Energy 2025 target.

TADF sensitizers targeting deep-blue emitters are designed by combining the advantages of short-range and long-range charge-transfer excited states. The resulting sensitizers enable high-performance deep-blue OLEDs with BT. 2020 blue gamut together with external quantum efficiency approaching 40%.

Abstract

The hyperfluorescence (HF) technology holds great promise for the development of high-quality organic light-emitting diodes (OLEDs) for their excellent color purity, high efficiency, and low-efficiency roll-off. Sensitizer plays a crucial role in the performance of HF devices. However, designing sensitizers with simultaneous high photoluminescence quantum yield (PLQY), rapid radiative decay (k r), and fast reverse intersystem crossing rate (k RISC) poses a great challenge, particularly for the thermally activated delayed fluorescence (TADF) sensitizers targeting deep-blue HF device. Herein, by introducing a boron-containing multi-resonance-type acceptor into the multi-tert-butyl-carbazole encapsulated benzene molecular skeleton, two TADF emitters featuring hybridized multi-channel charge-transfer pathways, including short-range multi-resonance, weakened through-bond, and compact face-to-face through-space charge-transfer. Benefiting from the rational molecular design, the proof-of-concept sensitizers exhibit simultaneous rapid k r of 5.3 × 107 s−1, fast k RISC up to 5.9 × 105 s−1, a PQLY of near-unity, as well as ideal deep-blue emission in both solution and film. Consequently, the corresponding deep-blue HF devices not only achieve chromaticity coordinates that fully comply with the latest BT. 2020 standards, but also showcase record-high maximum external quantum efficiencies nearing 40%, along with suppressed efficiency roll-off.

Efficient and robust temporal signal analysis is crucial for diverse fields, including medicine, finance, and telecommunications. Traditional techniques struggle with efficiency issues when handling complex temporal signals, primarily due to hardware and architectural limitations. This perspective explores the methods, features, applications, and potential of emerging materials and computing paradigms in temporal signal analysis.

Abstract

In the era of relentless data generation and dynamic information streams, the demand for efficient and robust temporal signal analysis has intensified across diverse domains such as healthcare, finance, and telecommunications. This perspective study explores the unfolding landscape of emerging materials and computing paradigms that are reshaping the way temporal signals are analyzed and interpreted. Traditional signal processing techniques often fall short when confronted with the intricacies of time-varying data, prompting the exploration of innovative approaches. The rise of emerging materials and devices empowers real-time analysis by processing temporal signals in situ, mitigating latency concerns. Through this perspective, the untapped potential of emerging materials and computing paradigms for temporal signal analysis is highlighted, offering valuable insights into both challenges and opportunities. Standing on the cusp of a new era in computing, understanding and harnessing these paradigms is pivotal for unraveling the complexities embedded within the temporal dimensions of data, propelling signal analysis into realms previously deemed inaccessible.

A new strategy to spatially confine oxygen vacancy (VO ) is demonstrated in the homo-interface of anatase TiO2. The confined VO in anatase TiO2 not only exhibits metallic behavior with high carrier density and electron mobility, but also promotes photocarrier lifetime. This synthetic strategy emphasizes how sub-bandgap energy levels in confined imperfections influence the kinetics of light-driven catalytic reactions.

Abstract

Light-driven energy conversion devices call for the atomic-level manipulation of defects associated with electronic states in solids. However, previous approaches to produce oxygen vacancy (VO ) as a source of sub-bandgap energy levels have hampered the precise control of the distribution and concentration of VO . Here, a new strategy to spatially confine VO at the homo-interfaces is demonstrated by exploiting the sequential growth of anatase TiO2 under dissimilar thermodynamic conditions. Remarkably, metallic behavior with high carrier density and electron mobility is observed after sequential growth of the TiO2 films under low pressure and temperature (L-TiO2) on top of high-quality anatase TiO2 epitaxial films (H-TiO2), despite the insulating properties of L-TiO2 and H-TiO2 single layers. Multiple characterizations elucidate that the VO layer is geometrically confined within 4 unit cells at the interface, along with low-temperature crystallization of upper L-TiO2 films; this 2D VO layer is responsible for the formation of in-gap states, promoting photocarrier lifetime (≈300%) and light absorption. These results suggest a synthetic strategy to locally confine functional defects and emphasize how sub-bandgap energy levels in the confined imperfections influence the kinetics of light-driven catalytic reactions.

This work presents a photochemical synthetic route for bandgap engineering of metal halide perovskite quantum dots. Utilizing a material-efficient microfluidic platform, the underlying mechanism of the photo-induced anion exchange reaction (PIAER) of metal halide perovskite quantum dots is unveiled and first instance of the PIAER-enabled synthesis of high-performing CsPbI3 NCs is reported.

Abstract

Over the past decade, lead halide perovskite (LHP) nanocrystals (NCs) have attracted significant attention due to their tunable optoelectronic properties for next-generation printed photonic and electronic devices. High-energy photons in the presence of haloalkanes provide a scalable and sustainable pathway for precise bandgap engineering of LHP NCs via photo-induced anion exchange reaction (PIAER) facilitated by in situ generated halide anions. However, the mechanisms driving photo-induced bandgap engineering in LHP NCs remain not fully understood. This study elucidates the underlying PIAER mechanisms of LHP NCs through an advanced microfluidic platform. Additionally, the first instance of a PIAER, transforming CsPbBr3 NCs into high-performing CsPbI3 NCs, with the assistance of a thiol-based additive is reported. Utilizing an intensified photo-flow microreactor accelerates the anion exchange rate 3.5-fold, reducing material consumption 100-fold compared to conventional batch processes. It is demonstrated that CsPbBr3 NCs act as photocatalysts, driving oxidative bond cleavage in dichloromethane and promoting the photodissociation of 1-iodopropane using high-energy photons. Furthermore, it is demonstrated that a thiol-based additive plays a dual role: surface passivation, which enhances the photoluminescence quantum yield, and facilitates the PIAER. These findings pave the way for the tailored design of perovskite-based optoelectronic materials.

In this work, it is demonstrated that controlling metal halide precursors' reactivity with organic additives during nucleation and growth enables the synthesis of InSb CQDs with narrow size distributions. Alkanethiol resurfacing facilitates efficient ligand exchange and integration into n-i-p photodiodes, exhibiting 10¹2 Jones detectivity, 33% EQE at 1380 nm, and >19 h of operational stability.

Abstract

InSb colloidal quantum dots (CQDs) hold promise in short-wave infrared sensing; however, their synthesis presents ongoing challenges, particularly in achieving precise size control – this is the result of poorly controlled reactivity among the precursors. Herein, the use of alkyl-phosphine and amine-based organic additives to control the reactivity of In and Sb precursors during the nucleation and growth of CQDs is developed. This interplay between organic additive and precursors enables the synthesis of InSb CQDs having narrowed size distributions; and bandgaps tunable across the 1.2–1.5 µm spectral range; all this leading to peak-to-valley ratios >1.4 in absorption spectra. The CQDs are surface-terminated with a mixture of oleylamine, halides, and oxide-like species, and this hinders ligand exchange reactions and subsequent integration into photodiodes. We therefore resurface the CQDs with alkanethiols, displacing the native ligands via an acid-base mechanism, an approach that removes oxide species. Using a layer-by-layer fabrication process, the ligands of the resurfaced InSb CQDs are exchanged with short organic and halide ligands and incorporated films into n-i-p photodiode structures. The resultant devices exhibit a detectivity of 10¹2 Jones, an external quantum efficiency (EQE) of 33% at 1380 nm, and T90 operating stability of >19 h under continuous illuminated operation.

Biological systems are very responsive to changes in stiffness, influencing important processes, and diseases in humans. Here, a novel method to dynamically and reversibly control hydrogel stiffness through interactions with poly (ethylene glycol) (PEG) is presented. By exposing hydrogels to PEG solutions at different concentrations and sizes, hydrogel stiffness can be tuned, in turn affecting cell properties.

Abstract

Cells are highly responsive to changes in their mechanical environment, influencing processes such as stem cell differentiation and tumor progression. To meet the growing demand for materials used for high throughput mechanotransduction studies, simple means of dynamically adjusting the environmental viscoelasticity of cell cultures are needed. Here, a novel method is presented to dynamically and reversibly control the viscoelasticity of naturally derived polymer hydrogels through interactions with poly (ethylene glycol) (PEG). Interactions between PEG and hydrogel polymers, possibly involving hydrogen bonding, stiffen the hydrogel matrices. By dynamically changing the PEG concentration of the solution in which polymer hydrogels are incubated, their viscoelastic properties are adjusted, which in turn affects cell adhesion and cytoskeletal organization. Importantly, this effects is reversible, providing a cost-effective and simple strategy for dynamically adjusting the viscoelasticity of polymer hydrogels. This method holds promise for applications in mechanobiology, biomedicine, and the life sciences.

Tissue-repairing macrophages compromise radiotherapy-induced antitumor immunity. An alkaline adjuvant (MgAl-based hydrotalcite, bLDH) reverses the situation. After engendering macrophages to phagocytose irradiated cancer cells, bLDH is administrated and improves the cross-presentation of engulfed tumor antigens over tenfold. bLDH limits the activity of phagolysosomal proteases and enables direct major histocompatibility complex class I antigen presentation in phagosome to improve precision radioimmunotherapy.

Abstract

Failures of radiotherapy (RT) in adaptive antitumor immunomodulation often associate with recruited tissue-repairing macrophages. Although training these macrophages to phagocytose post-RT cancer cells reverses their protumoral performance, engulfed tumor antigens are severely underrated. In fact, regulating the processing and presentation of tumor antigens, a key determinant of tumor immunogenicity, can fundamentally affect adaptive immune responses. Here it is reported that a simple Alum-like adjuvant (MgAl-based hydrotalcite, bLDH) improves radioimmunotherapy via inducing antigen cross-presentation by macrophages, independent of phenotypes. It is identified that cytidine monophosphate guanosine oligodeoxynucleotide engenders macrophages to phagocytose irradiated cancer cells. However, as semiprofessional antigen-presenting cells, macrophages possess powerful proteolytic function that is detrimental to antigen presentation. The administration of alkaline bLDH intriguingly relieves the activity of phagolysosomal proteases with acidic pH optima by preventing phagosomal acidification resulting from the vacuolar-type ATPase proton pump. The adjuvant-modulated phagolysosomes thus limit antigen degradation and enhance tumor antigen cross-presentation over tenfold. To examine from an in vivo breast tumor model, trained macrophages successfully cross-prime antigen-specific CD8+ T cells and curb RT-associated metastasis. The findings propose to pay close attention to the effect of adjuvants on precision immunotherapy and highlight the positive contribution of cross-presenting macrophages in radioimmunotherapy.

Energy Environ. Sci., 2025, Accepted Manuscript
DOI: 10.1039/D4EE05879H, PaperZhinan Zhang, Yinghao Xu, Shaofu Wang, Chuan Peng, Peiran Liu, Shengjie Du, Dexin Pu, Xingzhong Zhao, Ming-Hui Shang, Guojia Fang, Zhenhua Yu
Up to now, the trade-off between passivation and transport for 2-dimensional (2D)/3-dimensional (3D) perovskite heterojunctions is a challenge to simultaneously maximize open-circuit voltage (VOC) and fill factor (FF). Here, we...
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Energy Environ. Sci., 2025, Accepted Manuscript
DOI: 10.1039/D4EE05319B, PaperShujie Qu, Fu Yang, Hao Huang, Yiyi Li, Changxu Sun, Qiang Zhang, Shuxian Du, Luyao Yan, Zhineng Lan, Zhiwei Wang, Tongtong Jiang, Peng Cui, Xi-Cheng Ai, Meicheng Li
Utilizing self-assembled monolayer (SAM) of [4-(3,6-Dimethyl-9H-carbazol-9-yl)butyl]phosphonic acid as the interfacial layer on NiOx (Me-4PACz) has been proven to be a feasible approach to improve photovoltaic performance of inverted perovskite solar...
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Nature Materials, Published online: 12 February 2025; doi:10.1038/s41563-024-02111-8

Deformation twinning, a key deformation mechanism that is rarely explored in superhard materials, is shown to be activated in cubic boron nitride and other cubic covalent materials under a loading-specific twinning criterion.

Nature Materials, Published online: 12 February 2025; doi:10.1038/s41563-024-02108-3

The thermal transport properties of Eshelby twisted van der Waals GeS nanowire are investigated as model systems for thermal transport. The thermal conductivity of these systems are found to display anomalous behaviour with thermal conductivity with decreased nanowire diameter.

Title to be confirmed

Abstract not available

• Speaker: Jeremy Hahn (Cambridge)
• Wednesday 05 March 2025, 10:30-11:30
• Venue: CMS, MR15.
• Series: Differential Geometry and Topology Seminar; organiser: Oscar Randal-Williams.

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Volcanic fissure localisation and lava delta formation: Modelling of volcanic flows undergoing rheological evolution

In this talk, I will present two volcanologically motivated modelling problems. In the first, I will detail how thermoviscous localisation of volcanic eruptions is influenced by the irregular geometry of natural volcanic fissures. Fissure eruptions typically start with the opening of a linear fissure that erupts along its entire length, following which activity localises to one or more isolated vents within a few hours or days. Previous work has proposed that localisation can arise through a thermoviscous fingering instability driven by the strongly temperature dependent viscosity of the rising magma. I will show that, even for relatively modest variations of the fissure width, a non-planar geometry supports strongly localised steady states, in which the wider parts of the fissure host faster, hotter flow, and the narrower parts of the fissure host slower, cooler flow. This geometrically-driven localisation differs from the spontaneous thermoviscous fingering localisation observed in planar geometries, and is potentially more potent for parameter values relevant to volcanic fissures.

The second problem concerns lava delta formation. A lava delta arises when a volcanic lava flow enters a body of water, extending the pre-eruption shoreline via the creation of new, relatively flat land. A combination of cooling induced rheological changes and the reduction in gravitational driving forces controls the morphology and evolution of the delta. I will present shallow-layer continuum models for this process, highlighting how different modes of delta formation manifest in different late-time behaviours. In particular, I will derive a steady state shoreline extent when the delta formation is driven only by buoyancy forces, and late time similarity solutions for the evolution of the shoreline when the viscous lava fragments and forms `hyaloclastic’ debris on contact with the water.

• Speaker: Jesse Taylor-West (Bath)
• Monday 17 March 2025, 13:00-14:00
• Venue: MR3, CMS.
• Series: Quantitative Climate and Environmental Science Seminars; organiser: Dr Kasia Warburton.

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