Nanoscience News (<front>)

Sampling using Diffusion Processes

I will discuss a class of diffusion-based algorithms to draw samples from high-dimensional probability distributions given their unnormalized densities. Ideally, the method can transport samples from a Gaussian distribution to a specified target distribution in finite time. The stochastic interpolants framework used to derive a diffusion process, and also involves solving certain Hamilton-Jacobi-Bellman PDEs. These are solved using the theory of forward-backward stochastic differential equations (FBSDE) together with machine learning-based methods. Numerical experiments illustrating that the algorithm will also be discussed. This is joint work with Anand Jerry George.

• Speaker: Dr Nicolas Macris, EPFL
• Wednesday 12 February 2025, 14:00-15:00
• Venue: MR5, CMS Pavilion A.
• Series: Information Theory Seminar; organiser: Prof. Ramji Venkataramanan.

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Modelling sea ice dynamics using brittle dynamics: impact in pack ice and marginal ice zones

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

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

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

• Speaker: Guillaume Boutin (Nansen Environmental and Remote Sensing Center)
• Wednesday 29 January 2025, 14:00-15:00
• Venue: BAS Seminar Room 1; https://ukri.zoom.us/j/97264211524.
• Series: British Antarctic Survey - Polar Oceans seminar series; organiser: Dr Birgit Rogalla.

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Chlorosome-mimetic nanoreactors (Ru-Chlos) are created by the confined aggregation of photosensitive ruthenium-polypyridyl-silane monomers, which exhibit superior photocatalytic ability under acidic conditions without consuming oxygen. The photocatalytic activity of Ru-Chlos is impeded by the light-responsive disassembly of Ru-bridged matrix. Ru-Chlos-based combined therapy evokes strong immunogenic cell death effects and advances of efficient and safe light-controllable cancer photoimmunotherapy.

Abstract

Photocatalytic therapy for hypoxic tumors often suffers from inefficiencies due to its dependence on oxygen and the risk of uncontrolled activation. Inspired by the oxygen-independent and precisely regulated photocatalytic functions of natural light-harvesting chlorosomes, chlorosome-mimetic nanoreactors, termed Ru-Chlos, are engineered by confining the aggregation of photosensitive ruthenium-polypyridyl-silane monomers. These Ru-Chlos exhibit markedly enhanced photocatalytic performance compared to their monomeric counterparts under acidic conditions, while notably bypassing the consumption of oxygen or hydrogen peroxide. The photocatalytic activity of Ru-Chlos is finely tunable through light-responsive disassembly of the Ru-bridged matrix, with tunability governed by pre-irradiation duration. Utilization of Ru-Chlos loading prodrug [2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)] (ABTS) for phototherapy facilitates the generation of toxic radicals (oxABTS) and the photocatalytic conversion of endogenous NADH to NAD+, inducing oxidative stress in hypoxic cancer cells. Simultaneously, the light-responsive degradation of Ru-Chlos produces Ru-based toxins that further contribute to the therapeutic effect. This dual-action mechanism elicits potent immunogenic cell death effects and significantly enhances antitumor efficacy with the aid of a PD-l blockade. These biomimetic chlorosomes highlight their potential to advance oxygen-independent photocatalytic nanoreactors with controlled activity for novel cancer photoimmunotherapy strategies.

A multifunctional skin adhesive patch that strategically integrates heterogeneous phase change elements in a tessellated configuration is presented. This patch simultaneously provides remarkable skin adhesion, dynamic motion adaptability, the ability to integrate bulky electronics, on-demand damage-free detachment, low skin contact impedance, a high signal-to-noise ratio, and precise wireless health monitoring.

Abstract

Skin-interfaced electronics have emerged as a promising frontier in personalized healthcare. However, existing skin-interfaced patches often struggle to simultaneously achieve robust skin adhesion, adaptability to dynamic body motions, seamless integration of bulky devices, and on-demand, damage-free detachment. Here, a hybrid strategy that synergistically combines these critical features within a thin, flexible patch platform is introduced. This design leverages shape memory polymers (SMPs) arranged in a tessellated array, comprising both rigid and compliant SMPs. This configuration enables exceptional deformability, motion adaptability, and ultra-strong, repeatable skin adhesion while offering on-demand adhesion control. Furthermore, the design facilitates the seamless integration of bulky electronics without compromising skin adhesion. By incorporating sizeable electronics including signal acquisition circuits, sensors, and a battery, it is demonstrated that the proposed tessellated patch can be securely mounted on the skin, accommodate dynamic body motions, precisely detect physiological signals with an outstanding signal-to-noise ratio (SNR), wirelessly transmit data, and be effortlessly released from the skin.

Advanced Materials, Volume 37, Issue 4, January 29, 2025.

Biomimetic Chlorosomes

Photocatalytic therapy suffers from inefficiencies due to its reliance on oxygen and the attendant risk of unregulated activation. In article number 2413385, Wen Sun, Chao Yang, Wen-fei Dong, and their colleagues present a Chlorosome-mimetic nanoreactor (Ru-Chlos), made by aggregating ruthenium-polypyridyl-silane monomers, showing great photocatalytic ability in acidic conditions without oxygen consumption, and its photocatalytic activity of Ru-Chlos can be impeded by the light-responsive disassembly.

3D Printing

A novel organic ink based on egg albumen and saccharides is developed to create sacrificial supports for gelatin-based hydrogel prints. The cover photo shows biogel scaffolds with tunable pore size down to 0.4 mm, enabled by selective support removal. This allows printing of complex-shaped biodegradable joint-like vacuum actuators with 60° maximum bending angle at 0.23 s response time. More details can be found in article number 2409403 by Martin Kaltenbrunner and co-workers.

Solid-State Electrolytes

In article number 2410402, Jianwen Liang, Xueliang Sun, Xiaona Li, and co-workers present a pioneering and universal strategy for the hydrate-assisted synthesis of LiAlOCl solid-state electrolytes, enabling the kilogram-scale synthesis of low-cost aluminum-based chloroxides. The oxychloride SSEs contain large amounts of amorphous [Al a O b Cl c ](2b+c−3a)− components, achieving faster local mobility of lithium ions. The technology is expected to promote the industrial application of high specific energy all-solid-state batteries.

Ultrafast Symmetry Control

In article 2414196, Burak Guzelturk and co-workers reveal an ultrafast symmetry change upon photoexcitation in PbS quantum dots using time-resolved structural techniques. The magnitude of symmetry change is tunable by quantum dot surface chemistry, opening a pathway to designed phase changes for applications in data storage, computing, and sensing in the future.

Spatiotemporal Programmable 3D Chiral Blue Phase Patterns

In article number 2411988, Wenjie Yang, Chenglin Zheng, Jingxia Wang, and co-workers propose a method for spatiotemporal control of inkjet printing 3D chiral patterns in blue phase liquid crystals (BPLCs). Spontaneous ink diffusion in dual-chiral polymer-templated BPLCs enables programmable evolution of photonic bandgaps, and spatial chiral modes. The study quantitatively links ink diffusion kinetics to 3D optical diffraction of BPLCs, offering potential applications in time-temperature indicators, multidimensional encryption, and advanced optical sensor devices.

MicroRNA Sponge

The illustration depicts a tetrahedral RNA sponge constructed using a DNA framework, capable of simultaneously carrying three microRNA inhibitors. It can adsorb target microRNA molecules and deplete reactive oxygen species. This modulation alters the inflammatory state, promoting the transition of M1 macrophages to M2 macrophages, thereby alleviating pulmonary inflammatory damage and restoring microenvironmental homeostasis. More details can be found in article number 2414336 by Taoran Tian, Yunfeng Lin, and co-workers.

Ultraflexible Vertical Organic Electrochemical Transistors

Ultra-flexible, skin-conformable vertical-structure organic electrochemical transistors adhere seamlessly to the epidermis, enabling highly sensitive monitoring of physiological signals at ultra-low voltages. Their exceptional flexibility and strong skin adherence support accurate signal detection, driving advancements in non-invasive health monitoring applications. More details can be found in article number 2410444 by Myung-Han Yoon, Sungjun Park, and co-workers.

Motion-Adaptive Tessellated Skin Patches

In article number 2412271, Jae Joon Kim, Hoon Eui Jeong, and co-workers develop a multifunctional skin adhesive patch that integrates phase change elements in a tessellated configuration. This patch simultaneously provides remarkable skin adhesion, dynamic motion adaptability, the ability to integrate bulky electronics, on-demand damage-free detachment, low skin contact impedance, a high signal-to-noise ratio, and precise wireless health monitoring.

Energy Environ. Sci., 2024, 17,2468-2479
DOI: 10.1039/D4EE00062E, PaperLin Ma, Travis P. Pollard, Marshall A. Schroeder, Chao Luo, Ye Zhang, Glenn Pastel, Longsheng Cao, Jiaxun Zhang, Vadim Shipitsyn, Yan Yao, Chunsheng Wang, Oleg Borodin, Kang Xu
By employing 3,5-bis(trifluoromethyl) pyrazole (TFMP) as an electrolyte additive in both aqueous and non-aqueous mediums, a versatile interphase strategy is achieved. This facilitates stable Zn anodes with improved efficiency and longer cycling life.
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Energy Environ. Sci., 2024, 17,2576-2587
DOI: 10.1039/D3EE04556K, PaperYan Zhang, Zhaokun Wang, Yanrui Pan, Hao Yu, Zuohang Li, Chen Li, Su Wang, Yue Ma, Xixi Shi, Hongzhou Zhang, Dawei Song, Lianqi Zhang
The development of PFGPE is conducive to achieving excellent performance for carbonate ester and ether based Li-SPAN batteries.
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Energy Environ. Sci., 2024, 17,2530-2540
DOI: 10.1039/D3EE04354A, Paper Open Access &nbsp This article is licensed under a Creative Commons Attribution 3.0 Unported Licence.Mikkel Juelsholt, Jun Chen, Miguel A. Pérez-Osorio, Gregory J. Rees, Sofia De Sousa Coutinho, Helen E. Maynard-Casely, Jue Liu, Michelle Everett, Stefano Agrestini, Mirian Garcia-Fernandez, Ke-Jin Zhou, Robert A. House, Peter G. Bruce
The charge storage mechanism in LiNiO2 in Li-ion batteries is still under debate. Here, we show that trapped O2 forms during delithiation in LiNiO2, accommodated by Ni vacancies, which form in the Ni layer.
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Conspiracy beliefs and interpersonal relationships

Anecdotal reports in the media and on forums such as Reddit’s r/QAnonCasualties suggest that relationships can suffer when one person in the relationship believes in conspiracy theories. People commonly report having “lost” a loved one who has fallen down a “rabbit hole” of false beliefs. However, despite all the anecdotal evidence, very little empirical research has examined the consequences of conspiracy theories for people’s interpersonal relationships. In this talk, we present three lines of research in which we address this issue. First, we report the results of a qualitative study in which respondents described their broken relationships with close others who believe in conspiracy theories. We next report a set of cross-sectional and experimental studies in which we found that people perceived their existing relationships, and anticipated their future relationships, to be less satisfactory with conspiracy believers compared to conspiracy non-believers. Finally, we report a set of experimental studies using fictitious dating profiles, in which participants reported a lower likelihood of starting new relationships with conspiracy believers compared to conspiracy non-believers. Overall, these findings suggest that conspiracy beliefs can be detrimental for people’s interpersonal relationships. We highlight the need for further research on this topic and discuss potential factors that could prevent relationships being eroded by conspiracy beliefs.

• Speaker: Daniel Toribio Florez (University of Kent)
• Wednesday 05 February 2025, 15:00-16:00
• Venue: Ground Floor Lecture Theatre, Department of Psychology, Downing Site, Cambridge.
• Series: Social Psychology Seminar Series (SPSS); organiser: Yara Kyrychenko.

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CANCELLED: How do we protect the democratic information environment in an AI-powered world? Tackling online harms with computational social science and AI

THIS TALK IS CANCELLED

2023-2024 was a peak year of concern over AI safety, highlighted at the UK AI Safety Summit in Bletchley Park, the creation of AI safety institutes across the world, and concerns raised by technology experts over AI-powered threats to democracy and existential risks brought by the fast pace of AI development. This talk will scrutinise the claims that have been made regarding threats from AI to democratic life in an online world. It will report research that suggests that hype over AI is having its own independent effect, that targeted political persuasion may be less effective than has been claimed, that smaller models can be as persuasive as larger models and that AI itself may be part of the solution to AI-powered harms. Research suggests that the real threats to society and democracy may come from long-running shifts in the information environment, where people start mistrusting all information and are increasingly fearful of expressing political opinions in online settings. AI and computational social science researchers will need to find new ways of understanding, measuring and mitigating these threats.

• Speaker: Helen Margetts (University of Oxford)
• Wednesday 29 January 2025, 13:00-14:00
• Venue: Ground Floor Lecture Theatre, Department of Psychology, Downing Site, Cambridge.
• Series: Social Psychology Seminar Series (SPSS); organiser: Yara Kyrychenko.

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