Abstract At the glass transition, a liquid transforms into an amorphous solid. Despite minimal structural rearrangements, this transition is accompanied by a dramatic dynamical slowdown. These features render the transition’s experimental determination and theoretical understanding challenging. Here we introduce a new framework that uses two-particle correlations and a model-free theoretical description to investigate the dynamics of glass-forming colloidal suspensions indirectly. Using the fluctuation-dissipation theorem, we relate equilibrium thermal fluctuations of pairs of tracer particles to the underlying response properties of the system. We measure the correlated motion of tracer particles caused by the solvent at short timescales and find three distinct signatures signalling the onset of the glass transition. The correlations in the thermal motions of tracer pairs exhibit a changing decay behaviour with their relative distance; a length scale related to this decay steeply increases; and a notable sign reversal is observed in specific correlations. Our findings establish a connection between the colloidal glass transition and the breaking of the translational symmetry in the dispersion medium, thereby revealing fundamental aspects of the glass transitions.

Bacterial flagellar swarming enables dense microbial populations to migrate collectively across surfaces, often resulting in emergent, coordinated behaviors. However, probing the underlying energetics of swarming at the single-cluster level remains a challenge. Here, we combine optical tweezers and multiparticle tracking within a stochastic thermodynamic framework to characterize the active motility of confined Proteus mirabilis clusters. Using the photon momentum method to directly measure trapping forces, we show that swarming clusters generate persistent, dissipative flows indicative of nonequilibrium stationary motility within confined solenoidal mesostructures. These flagellar rotational dynamics break detailed balance in mesoscopic force space and exceed the limits of passive friction, as evidenced by force-velocity correlations and vortex-like circulations. By coarse-graining cluster trajectories into an active Brownian phase space, we quantify the work performed by bacterial swarms at cooperative coupling to thermal fluctuations, resulting in dissipative Ohmic-like currents overcoming conservative trapping. Our findings establish a generalizable approach to quantify collective motility and energetic dissipation in active bacterial clusters under confinement, offering insights into the physical principles governing microbial cooperativity.

Mitochondria are essential organelles that govern energy metabolism, redox balance, and cell survival; their dysfunction is implicated in a wide range of pathologies, including neurodegenerative disorders, cardiovascular diseases, metabolic syndromes, and cancer. Despite their significance as therapeutic targets, the unique structural and electrochemical properties of mitochondria, particularly the impermeable inner mitochondrial membrane and high membrane potential pose major challenges for the targeted delivery of therapeutic agents. Recent advances in biomaterials have spotlighted peptide-polymer conjugates as versatile platforms, capable of navigating intracellular barriers and achieving precise mitochondrial localization. These hybrid systems combine the physicochemical tunability of polymers with the biofunctionality of peptides, enhancing cellular uptake, endosomal escape, and suborganelle trafficking. The incorporation of stimuli-responsive elements further enables spatiotemporal control of cargo release in response to intracellular cues such as pH shifts, thermal fluctuations, redox gradients, or enzymatic activity. Such systems are especially promising for mitochondrial gene and protein delivery, offering improved selectivity, reduced systemic toxicity, and the potential to restore mitochondrial function under pathological conditions. This review showcases advanced strategies in stimuli-responsive peptide-polymer systems for mitochondria-targeted delivery, highlighting how their smart, responsive functions enable precise, controllable therapeutic interventions and drive the development of next-generation, transformative biomaterials in precision nanomedicine.

Lipid membranes are often regarded as passive barriers, yet their nonlinear dielectric response remains poorly understood. Using all-atom molecular dynamics, we show that fully hydrated dipalmitoylphosphatidylcholine bilayers exhibit relaxor ferroelectric-like behavior under time-dependent electric fields. Unlike crystalline relaxors, which are bipolar and display little remanent polarization, lipid bilayers exhibit a unipolar polarization response: even an alternating current field produces persistent, asymmetric polarization. The underlying free-energy landscape contains two distinct minima, a nonpolarized state and a unipolarly polarized state, between which stochastic thermally activated transitions occur. Directionally resolved Van Hove analysis reveals pronounced anisotropy arising from out-of-plane electric dipole alignment, interleaflet coupling, and lateral polarization domains. Each field cycle nucleates polarization at distinct sites and monitors their relaxation, marking a crossover from thermal fluctuations to field-sustained polarization. Remarkably, these polarized domains persist after field removal, generating long-lived, spatially coherent dipolar patterns that encode nanoscale polarization memory. Potassium chloride amplifies these effects via dielectric screening and a modified hydration structure, enhancing electric dipole flexibility and cooperativity. Together, these results establish protein-free bilayers as nonlinear, history-dependent dielectrics capable of sustaining field-tunable electromechanical coupling, providing an emergent physical foundation for nanoscale information storage and memory phenomena reminiscent of short- and long-term plasticity in soft neuromorphic systems.

In atomic force microscopy (AFM), the detection of interactions between the probe tip and the sample surface is the basis of topography imaging. It is crucial to minimize the tip-sample interaction to prevent deformation or damage to soft biological macromolecules in AFM imaging. Here, a scanning mode of AFM was developed to image soft biological macromolecules with a sub-10 pN load force. In this scanning mode, the reduction in the thermal fluctuation of the cantilever was monitored at subnanometer tip-sample separations, where interaction with the sample begins to influence cantilever behavior. The height of the sample was controlled such that the magnitude of the thermal fluctuation of the cantilever remained constant. The magnitudes of the fluctuations and forces in this scanning mode were formulated within the framework of statistical mechanics. It was estimated that the repulsive force acting between the probe tip and sample surface originated largely from the entropic effect of the reduction in cantilever fluctuation. Two proteins (GroEL and bacteriorhodopsin) were imaged to demonstrate the capability of this scanning mode for acquiring topography with a marginal load force. The fragile double-ring structure of GroEL was preserved after repeated scans. The flexible C-terminal region of bacteriorhodopsin was clearly visualized. Thus, the presented AFM imaging mode is highly noninvasive for soft and fragile biological macromolecules.

Dewetting, a phenomenon studied for over a century, has broad applications across diverse areas. When thin metal films deposited on flat substrates are heated, they undergo dewetting and typically form nanoparticles whose size and spacing are influenced by parameters such as film thickness, substrate surface energy, annealing temperature, and surface diffusion kinetics. In conventional dewetting, these factors often result in broad particle size distributions and irregular interparticle spacings due to uncontrolled thermal fluctuations and instabilities. Controlling dewetting to produce high-density nanoparticles with narrow size distributions and single-digit nanometre interparticle separations is a very difficult task and requires complex and expensive fabrication techniques. Here, a scalable, cost-effective method for producing high-density and low-dispersity metal nanoparticles on various substrates with flat, curved, and microtextured surfaces is presented. By creating a confined environment with a Polydimethylsiloxane (PDMS) layer atop the film during dewetting, pure metal and alloy nanoparticles with high density, low size variation, and high purity are obtained. Theoretical analysis suggests that the elasticity and reduced surface tension of PDMS lower the energy associated with surface fluctuations, which in turn reduces particle size. This approach provides a straightforward route for fabricating low-dispersity, high-density nanoparticles through a simple confined-dewetting method, with widespread applications.

Thermal Fluctuations Expose Hidden Mechanical Couplings in Proteins

The two-dimensional carbon nitride with the stoichiometric formula C3N exhibits higher basal plane reactivity toward gas molecules than graphene. Its edges, which are an inherent feature of experimentally synthesized structures, are expected to be more reactive toward oxygen and offer a promising avenue for improving surface chemistry and electronic properties under oxidative environments. However, the stable edge structures and O2-driven edge oxidation mechanism of the C3N monolayer remain unexplored. With the combination of first-principles calculations and ab initio atomistic thermodynamics, we have identified 135 thermodynamically stable edge oxidation configurations and determined the oxidation phase diagrams over broad ranges of temperature and pressure in O2 atmospheres for four C3N edge types: armchair all-carbon (ACC), armchair mixed carbon-nitrogen (ACN), zigzag all-carbon (ZCC), and zigzag mixed carbon-nitrogen (ZCN). It is demonstrated that all edges are readily oxidized by the atomic O and O2 compared to the C3N basal plane, forming CO, N-O, and nondissociatively chemisorbed O2 species, with ACC and ZCC edges being more susceptible to oxidation than ACN and ZCN edges. Increasing O2 pressure raises the edge oxygen density, leading to the transformation of stable edge oxidation structure from the atomic O-dominant configuration to the mixture of O and the chemisorbed O2 configuration. Using ab initio molecular dynamics simulations, we reveal three distinct edge oxidation mechanisms, including a two-step oxidation, concerted reactions involving two nondissociatively chemisorbed O2, and O3 formation via interaction between an O2 and a nondissociatively chemisorbed O2. These reactions are all spontaneous at room temperature, with the first two being barrierless and the third having a low barrier on the order of thermal fluctuation. Furthermore, the electronic properties can be tuned by the edge oxidation density. This work elucidates the stable oxidized edge structures and oxidation pathways of C3N, highlighting its high edge reactivity and providing a potential strategy for electronic property engineering in carbon nitride materials.

Stress is an essential component of our lives. It helps to us to keep alert, stay motivated, and adapt to new and challenging situations. However, it is also a leading cause of poor mental wellbeing. Investigating psychological stress is essential to improving both the physical and mental health of the general population. Current methods often rely on self-report and physically invasive (contact) measures which can lack objectivity and ecological validity. Thermal imaging is emerging as a powerful objective, continuous, and physically non-invasive (non-contact) tool to investigate psychological stress through changes in nasal skin temperature. Yet there remain gaps in our understanding of thermal ranges, thermal recovery, and thermal associations with perceived stress in the healthy population. We present a new protocol, employing continuous thermal video to measure nasal temperature fluctuations during stress induction in healthy adults. Results indicate that induced psychological stress significantly decreases nasal temperature compared with a white noise baseline, and a social stress task elicited a significantly stronger nasal temperature decrease from baseline compared with a cognitive stress task. Although perceived stress was not associated with nasal thermal fluctuations, perceived somatic anxiety symptoms did significantly relate with nasal temperature change. These findings reveal new insight into the psychological and physiological human stress experience. The continuous, non-contact and objective benefits of thermal imaging makes it uniquely placed to contribute to real-world health applications, including translation to clinical and nonverbal populations across the lifespan.

Agro-industrial facilities host processes and products that are highly sensitive to thermal fluctuations. Given the projected increase in air temperatures in tropical regions due to climate change, improving indoor thermal conditions in these facilities has become critically important. Conventional cooling systems are widely used to maintain adequate indoor temperatures; however, they are associated with high energy consumption. In this context, Ground Source Heat Pump (GSHP) technology emerges as a promising alternative to reduce cooling loads by exchanging heat with the ground. This study evaluates the reductions in cooling energy consumption and the return on investment of a GSHP system integrated with conventional cooling system, considering a prototype agro-industrial room located in two ecotones of the Brazilian Midwest: the Amazon Forest (AF) and Brazilian Savanna (BS). Building energy simulations were performed using EnergyPlus software v. 9 under current climate conditions and climate change scenarios for 2050 and 2080. Initially, the prototype room was conditioned using a conventional HVAC system; subsequently, a GSHP system was integrated to enhance energy efficiency and reduce energy demand. Under current conditions, cooling energy demand in the BS and AF ecotones is projected to increase by 16.5% and 18.3% by 2050, and by 24.5% and 23.5% by 2080, respectively. The payback analysis indicates that the average return on investment improves under future climate scenarios, decreasing from 14.5 years under current conditions to 10.13 years in 2050 and 9.86 years in 2080. The findings contribute to understanding the thermal resilience and economic feasibility of ground-coupled heat exchangers as a sustainable strategy for mitigating climate change impacts in the agro-industrial sector.

Efficient exciton dissociation and charge separation at donor/acceptor interfaces as well as balanced charge transport within each phase are critical for advancing next-generation organic photovoltaics. In this work, we study a trifluoromethyl-substituted nonfullerene acceptor (NFA), Y2CF3, whose central-core fluorinated side chain modification induces favorable crystal packing and markedly improves device performance (Cho et al., J. Am. Chem. Soc., 147, 758 (2025)). Combining molecular dynamics simulations and density functional theory calculations, we comprehensively describe the electronic processes and charge transport in PM6:Y2CF3 blends and compare them to the benchmark PM6:Y6 blends. Y2CF3 shows a red-shifted singlet local exciton (1LE) energy but nearly unchanged charge transfer (1CT) energies, narrowing the 1LE-1CT gap and enabling rapid conversion as precursor of charge separated states. Enhanced electron transfer rates among Y2CF3 molecules arise from strong terminal-terminal interactions as dominantly found in the Y2CF3 crystal structure. Thermal fluctuations are found to substantially enhance the hole transport rates in PM6, narrowing the disparity between electron and hole transport. These findings clarify how targeted side chain fluorination at the NFA core can optimize packing, charge separation, transport, and OPV efficiency.

Abstract We investigate the spin-polarized ballistic transport in a three-terminal Zigzag graphene nanoribbon (ZGNR) device using a tight binding model, non-equilibrium Green function formalism within the Landauer–Büttiker framework. We study the transmission spectrum, density of states, I – V characteristics, spin-resolved conductance and spin current by varying ribbon geometries and an out-of-plane Zeeman field. In absence of magnetization, transport is dominated by subband quantization and resonant edge states, with pronounced dependence on ribbon width and length while the introduction of a Zeeman field offers spin-selective transport and inducing half-metallic behavior, particularly in narrower ribbons, highlighting the interplay between quantum confinement, edge-localized states and spin-dependent interactions. Moreover, we found Fabry–Pérot-like interference in conductance spectrum and bias-driven mode activation with strong spin filtering effects. The spin current is found to be tunable via magnetic field and gate voltage. Also, it remains stable under thermal fluctuations, demonstrating suitability for room-temperature operation. Finally, the energy and width dependence of the Fano factor reveals distinct quantum interference features and spin-polarized transport signatures. These findings indicate the potential of the three-terminal ZGNR based device for scalable and gate-controllable spintronic applications.

We study pseudogap behavior in a metal near an antiferromagnetic instability and apply the results to electron-doped cuprates. We associate pseudogap behavior with thermal magnetic fluctuations and compute the fermionic self-energy along the Fermi surface in a weak pseudogap regime, which we justify. We analyze the spectral function as a function of frequency (energy distribution curves, EDC) and momentum (momentum distribution curves, MDC). We show that the EDC display pseudogap behavior with peaks at a finite frequency at all momenta. On the other hand, MDC peaks disperse within the pseudogap, ending at a gossamer Fermi surface. We analyze magnetically-mediated superconductivity and show that in a weak pseudogap regime thermal fluctuations almost cancel out in the gap equation. We favorably compare our results with recent ARPES studies.

Magnetic skyrmions, topologically protected spin textures, are promising candidates for information carriers in metallic racetrack memories, where data bits are encoded by their spatial arrangement. Conventional skyrmion-based racetracks employ binary encoding through inter-skyrmion spacing in one-dimensional nanostrips, yet maintaining precise spacing remains challenging due to thermal fluctuations, noise, and material defects. To overcome this limitation, we propose a dual-lane racetrack architecture separated by an engineered domain wall. Micromagnetic simulations demonstrate that this design offers several critical advantages: (1) Topological repulsion from the domain wall effectively confines skyrmions to their respective lanes, eliminating cross-lane migration. (2) The motion dynamics of skyrmions in one lane exhibit minimal interference from those in the adjacent lane, owing to the topological repulsion from the domain wall that ensures a sufficiently large inter-lane spacing to weaken dipole interactions. (3) The structure enables programmable operations, including skyrmion sorting, directional transport, and controlled annihilation.

As the largest cryogenic superconducting platform in China and even Asia, the Shanghai High-intensity Ultrafast X-ray Facility (SHINE) highly depends on the stable operation of 1.3 GHz superconducting accelerating modules in a 2 K superfluid helium environment. This paper elaborates on the key control technologies developed and successfully applied to ensure the smooth aging process of superconducting modules in the cryogenic experiments of the SHINE injector section. To address the issue of thermal load fluctuations caused by the dynamic changes in RF power during the aging process, a dynamic power compensation algorithm based on real-time cavity pressure feedback was proposed and implemented. Meanwhile, a multi-variable coupled PID control strategy was adopted to achieve high-precision stability of the helium tank liquid level (±1%) and cavity pressure (±10 Pa). Experimental results show that this integrated control scheme effectively suppresses the risk of quenching caused by thermal disturbances, significantly improving the aging efficiency and operational reliability of the superconducting modules. This lays a solid technical foundation for the commissioning and long-term stable operation of the superconducting systems of SHINE and similar large-scale scientific facilities.

Particles diffusing near interfaces face anisotropic resistance to motion due to hydrodynamic interactions. While this has been extensively studied near hard interfaces since the works of Lorentz and Brenner, our understanding of diffusion near soft, thermally fluctuating interfaces remains limited. Previous studies have predominantly focused on particles much larger than the molecular scale at which thermal fluctuations become important. In this work, we numerically investigate the dynamics of individual solvent molecules near a thermally fluctuating lipid membrane, a canonical soft interface in biology. We observe that the diffusive motion of solvent molecules near the fluctuating membrane is slightly enhanced compared to a flat rigid interface and significantly more so than near an undulated rigid interface. This enhancement in diffusive motion arises from spontaneous momentum exchanges between the moving membrane and adjacent molecules, promoting mixing. Notably, this dispersion effect overcomes geometric trapping that slows diffusion near the rigid undulated interface. Our analysis reveals that the momentum transfer near the fluctuating membrane is so efficient that it resembles an effective slip boundary condition over a length scale equal to the fluctuation height. These molecular-scale mechanisms differ from those of larger particles, where hydrodynamic memory and elasticity effects can be at play as they relax over timescales comparable to significant diffusive motion. Our findings advance understanding of enhanced diffusive motion and promoted mixing near soft fluctuating membranes involved in diverse biological processes and soft-matter technologies containing natural and model cell membranes.

Active particles under soft confinement such as droplets or vesicles present intriguing phenomena, as collective motion emerges alongside the deformation of the environment. A model is employed to systematically investigate droplet morphology and particle distribution in relation to activity and concentration, revealing that active particles have the capacity to induce enhanced shape fluctuations in the droplet interface with respect to the thermal fluctuations, aligning with recent experimental observations. A rich phase behaviour can be identified with two different mechanism of droplet breakage.

We report high-resolution measurements of thermal fluctuations in microwave and mechanical resonators using a dual-channel readout system. The latter comprises a low-noise amplifier, an I/Q-mixer, and a cross-correlator. We discovered that, under certain conditions, the intrinsic fluctuations of the low-noise amplifier, which are common to both channels of the readout system, are averaged out when computing the voltage noise cross-spectrum between the mixer's outputs. The suppression of the amplifier's technical fluctuations significantly improves the contrast of the thermal noise peaks exhibited by the resonators. Thus, for the room-temperature-stabilized 9 GHz sapphire-loaded cavity resonator, we observed more than 16 dB improvement in the thermal noise peak contrast relative to the single-channel measurements. The ability of the dual-channel readout system to discriminate between the broad- and narrow-band fluctuations may benefit the search for dark matter, which relies on the use of cryogenic microwave resonators.

ABSTRACT The sensitivity of optomechanical sensors is fundamentally constrained by the combined effects of shot noise and quantum back‐action. Here we show that the joint action of cross‐Kerr nonlinearity and an optical parametric amplifier (OPA) can effectively suppress these noises. By tailoring the cross‐Kerr strength, the force‐sensing sensitivity can surpass the standard quantum limit (SQL), while an optimal driving power broadens the detection bandwidth. We further find that the system becomes unstable when the detuning falls below . Importantly, the inclusion of an OPA enhances robustness against thermal fluctuations, allowing the sensitivity of force measurement to surpass the SQL even at temperatures up to 300 K. A detailed noise analysis reveals that cross‐Kerr nonlinearity predominantly suppresses back‐action noise, whereas the OPA provides a strong reduction of shot noise. These results establish a promising hybrid strategy for realizing optomechanical sensors that combine high sensitivity with thermal resilience, with broad applications ranging from medical diagnostics to gravitational‐wave astronomy.

The melting of two-dimensional systems is a fundamental challenge in condensed matter physics, where topological defects and thermal fluctuations play a key role. This work uses molecular dynamics simulations to investigate the melting of particles interacting via the Gay-Berne potential in the weak anisotropy regime (1.0 ≤ k ≤ 1.2). We demonstrate that the melting mechanism depends critically on the particle aspect ratio. For weak anisotropy (k < 1.15), the system follows a hybrid Bernard-Krauth scenario, featuring a continuous crystal-to-hexatic transition, followed by a first-order hexatic-to-isotropic liquid transition. At k ≥ 1.15, the system switches to the full Berezinskii-Kosterlitz-Thouless-Halperin-Nelson-Young scenario with two continuous Berezinskii-Kosterlitz-Thouless transitions. Introducing binary mixtures of particles with different anisotropies suppresses the first-order transition, stabilizing the continuous melting pathway. Therefore, weak shape anisotropy serves as a fundamental switching parameter governing the universal melting behavior of two-dimensional systems.