Tata Institute of Fundamental Research

Two-dimensional materials are a fertile ground for exploring quantum geometric phenomena, with Berry curvature and its first moment, the Berry curvature dipole, playing a central role in their electronic response. These geometric properties influence electronic transport and result in the anomalous and nonlinear Hall effects, and are typically controlled using static electric fields or strain. However, the possibility of modulating quantum geometric quantities in real-time remains unexplored. Here, we demonstrate the dynamic modulation of Berry curvature and its moments, as well as the generation of a pseudo-electric field and their coupling. By placing heterostructures on a membrane, we introduce oscillatory strain together with an in-plane AC electric field and measure Hall signals that are modulated at linear combinations of the frequencies of strain and electric field. We also present direct experimental and theoretical evidence for coupling between pseudo-electric field and quantum geometry that results in an unusual dynamic strain-induced Hall response. This approach opens up a new pathway for controlling quantum geometry on demand, moving beyond conventional static perturbations. The coupling of the pseudo-electric field with Berry curvature provides a framework for external electric field-free anomalous Hall response and opens new avenues for probing the topological properties.

While biocatalysisin ionic liquids (ILs) using a single enzymeis well known, the successful performance of enzyme cascade reactions(ECRs) using multiple enzymes in ILs is limited by the incompatiblestabilization of more than one enzyme in a single IL. Here, we introducean innovative approach where stoichiometric precision of ILs createspH-switchable media that dynamically modulate multienzyme microenvironmentsand maintain the functional integrity of ECR without requiring anyproximity-engineered scaffolds. Cholinium-based ILs, with phosphateand carboxylate anions, were synthesized with varying molar ratiosof cholinium to realize pH-switchable aqueous platforms for ECR. Usingglucose oxidase (GOx)–horseradish peroxidase as (HRP) an enzymaticcascade, we demonstrate that under optimized conditions aqueous solutionsof ILs significantly enhance both the individual enzyme (GOx and HRP)activities and ECR (GOx–HRP) efficiencies compared to the control,phosphate-buffered saline (PBS) (pH 7.4). Molecular docking, moleculardynamics simulations, UV–vis, and circular dichroism spectroscopystudies reveal that ILs are involved in soft interactions with enzymes,stabilizing catalytically favorable conformations, and protectingenzymes against thermal-stress. Remarkably, a 25-fold increase inthe ECR efficiency was achieved in 10 wt % of [Ch]2[PAA]through [Ch]2[PAA] assisted improved substrate channelingand reduced transition-state energy barriers. Moreover, an ∼16%increase in the half-life temperature (T50) of GOx–HRP cascade in the presence of 10 wt % [Ch]2[PAA] with an enhanced melting temperature (Tm) of the enzymes suggested improved thermal stability relativeto PBS. The results of improved enzyme stability in hydrated ILs werefurther investigated by the thermodynamic stability curves (ΔG vs T). Overall, this work provides abasis for multienzyme biocatalysis in aqueous solution of ILs withan accelerated ECR rate and improved thermodynamic stability, envisagingsustainable biocatalysis and metabolic engineering.

Abstract Across myriad habitats and diverse lifeforms, oxygen and mechanics are the most ubiquitously varying and profoundly influential environmental regulators. While physiological niches feature both varying oxygen levels and heterogeneous mechanics, laboratory experiments typically interrogate these as independent variables. Here, we show that combinatorial regimes defined by varying oxygen partial pressures and environmental mechanics—an oxo-mechanical cue—induce functionally-distinct cellular states in 3D ECM-like contexts. Single-cell morphometrics combined with multi-omics reveal that cellular response to oxygen deprivation depends on external mechanical milieus, whereas, cellular engagement with different mechanical microenvironments depends on oxygen availability. Independently perturbing both hypoxic signaling and cytoskeletal activity further reveals a reciprocal oxo-mechanical regulatory coupling, which operates by differentially altering the global chromatin accessibility for transcriptional regulation in response to specific combinations of oxygen partial pressures and external mechanical milieus. Together, our findings establish that a coupling between oxygen and mechanics drives the emergence of microenvironmentally-defined cell states.

Context. Radio halos are diffuse megaparsec-scale nonthermal radio sources located at the center of galaxy clusters. They trace relativistic particles and magnetic fields in the intra-cluster medium. The source of energy for their formation is believed to be the merging of galaxy clusters, which generates turbulence and reaccelerates aged electrons. Aims. We studied the diffuse radio emission, spectral properties, and the connection between thermal and nonthermal emission in the massive ( M 500 ∼ 7 × 10 14 M ⊙ ), dynamically disturbed galaxy clusters Abell 773 and Abell 1351. Methods. We combined observations from the LOFAR Two-meter Sky Survey Data Release 2 at 144 MHz and the new upgraded Giant Meterwave Radio Telescope at 650 MHz for both clusters. Archival XMM-Newton X-ray images were utilized to supplement our analysis. Results. We confirm that both clusters host a radio halo, each of which has a largest linear size of ∼2 Mpc. We measure an integrated spectral index ($ \alpha_{144}^{650} $) of ∼ − 1.0 for both clusters. Via point-to-point analysis, we show that the radio halo in A773 resembles a classical radio halo that follows a sublinear relation between radio and X-ray surface brightness. Conversely, A1351 exhibits a more complex and asymmetric radio halo that is embedded with several radio sources, including the brightest cluster galaxy, a tail galaxy, and the ridge. We find a deviation from the sublinear relation in the point-to-point analysis that is due to the presence of these contaminating radio sources.

The interplay between magnetic order, charge dynamics, and crystal field excitations underpins the emergent ground states of rare-earth intermetallics. Using time-domain terahertz spectroscopy, we probe this coupling in PrSi, a metallic ferromagnet. The optical response exhibits pronounced Drude-Smith behavior over a broad temperature range, indicating persistent carrier scattering. A classical Kondo-lattice model (CKLM) attributes this non-Drude conductivity to scattering of itinerant electrons by localized magnetic moments, persisting down to temperatures well below the magnetic ordering scale. At lower temperatures, beyond the scope of CKLM, our experiment reveals that the response is dominated by crystal field excitations, with sharp transitions at 0.6 and 1.54THz. The mode at 1.54THz shows a dynamic correlation with the onset of ferromagnetic order, marking the onset of a crystal-field-governed low temperatureregime.

Constraining the Epoch of Reionization (EoR) with physically motivated simulations is hampered by the high cost of conventional parameter inference. We present an efficient emulator-based framework that dramatically reduces this bottleneck for the photon-conserving semi-numerical code SCRIPT. Our approach combines (i) a reliable coarse-resolution MCMC to locate the high-likelihood region (exploiting the large-scale convergence of SCRIPT) with (ii) an adaptive, targeted sampling strategy to build a compact high-resolution training set for an artificial neural network based emulator of the model likelihood. With only ≈ 103 high-resolution simulations, the trained emulators achieve excellent predictive accuracy (R 2 ≈ 0.97–0.99) and, when embedded within an MCMC framework, reproduce posterior distributions from full high-resolution runs. Compared to conventional MCMC, our pipeline reduces the number of expensive simulations by a factor of ∼ 100 and lowers total CPU cost by up to a factor of ∼ 70, while retaining statistical fidelity. This computational speedup makes inference in much higher-dimensional models tractable (e.g., those needed to incorporate JWST and upcoming 21 cm datasets) and provides a general strategy for building efficient emulators for next generation of EoR constraints.