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Rewiring endogenous genes in CAR T cells for tumour-restricted payload delivery
Relaxation spectra of molecular glass formers probed by tandem Fabry–Perot interferometry and photon correlation spectroscopy: A critical re-assessment
Relaxation spectra of molecular glass formers measured by tandem Fabry–Perot interferometry (TFPI) and by photon correlation spectroscopy (PCS) are revisited from well above Tm down to Tg. We scrutinize the claim that a generic relaxation stretching is found close to Tg, while varying stretching is established at high temperatures. The TFPI spectra observed in this work reveal no change of the stretching over a large temperature range, and a Cole–Davidson susceptibility yields stretching parameters within βCD = 0.39–0.80. The spectra display a high-frequency excess wing contribution, which prohibits a single power law description of the high-frequency flank of the main relaxation. Corresponding PCS decays measured close to Tg display no change in the stretching either. Yet, the PCS spectra are overall broader than the TFPI spectra. They exhibit some variation and are superiorly described by a Kohlrausch function with βK = 0.52–0.73. Three of the eight systems significantly deviate from the previously reported generic relaxation function. We do not find indications that the spectral width changes within a narrow temperature interval to bridge the different stretching monitored by the two techniques. In addition to other possible explanations, we consider a sharp transition of the dynamics in the ns range not covered by the two techniques so far. Comparing PCS spectra of weakly polar liquids with their dielectric spectra, we find counterexamples of the claim that they become identical; the PCS spectra are narrower in these cases. Still, in this limit, the dielectric spectra display identical spectral shapes.
Design and implementation of a self-correcting non-retrodirective cross-eye jamming system using reference amplitude ratio and phase difference
Evaporation from spherical chitosan polymer gels
Water retention is an important feature in the design and use of biocompatible polymers, such as chitosan, which is often used as a hydrogel for biomedical and pharmaceutical applications. We study water evaporation from chitosan-based hydrogels both for gels in close proximity and for essentially isolated gels. We find that water evaporation from single gels is diffusive, as for pure water drops, but that it happens more slowly. We interpret this difference in terms of a steady-state where the equilibrium properties entering the problem are effectively lower. In the case of many gels, the evaporation process becomes one-dimensional due to water-vapor saturation of the local environment of the gels. Using an electric analogy, we model the transition between the two cases, ultimately illustrating pathways for tuning the water retention properties of polymer hydrogels.
Lightweight grape leaf disease recognition method based on transformer framework
Yielding of crystals toward the quasistatic limit: A slip-plane condensation transition
A novel scenario for the yielding of three-dimensional crystals in the quasistatic limit is presented. To this end, a face-centered cubic Lennard-Jones crystal under deformation and periodic boundary conditions is studied using Monte Carlo simulation in combination with successive umbrella sampling. As a reaction coordinate, a non-affinity parameter X is introduced. In terms of this parameter, the yielding of the crystal can be described as a phase transition, where at the system-size-dependent yield strain ɛ(y), a deformed crystal, the “N phase,” transforms into a nearly stress-free state, the “M phase.” The N–M phase transition is dominated by the long-ranged elasticity of the crystal. As a consequence, there are no mixed states of both phases. Moreover, the free energy barrier between them is not associated with interfacial contributions, but rather scales with the total volume V of the crystal, implying non-convexity of the X-dependent free energy F(X). On the path from the N to the M phase with increasing X, the free energy F(X) develops two kinks that are associated with jumps of a field conjugate to the non-affinity parameter X. At the first kink, corresponding to the maximum of F(X), there is the nucleation of a partial slip plane, associated with the formation of a stacking fault that is circumvented by a loop of Shockley partial dislocations. At the second kink, at a lower free energy, the dislocations are annihilated leaving behind the stacking fault around now fully developed slip planes. The resulting M phase is inhomogeneous with periodically repeating stacking faults around the fully developed slip planes (here, the distance between the slip planes is determined by the periodic boundary conditions and the initial orientation of the crystal in the simulation box).
Application of the metaheuristic algorithms to quantify the GSI based on the RMR classification
Spin crossover in metal–organic frameworks: A crystal embedded multi-reference study
Spin crossover (SCO) in transition metal (TM)-containing solid state materials remains a challenge for the electronic structure calculations as some of the electronic states may have a significant multi-reference character. The periodic effective Hamiltonian of crystal field (pEHCF) method accurately describes strong correlations in TM-containing crystalline systems. In this work, pEHCF has been applied to study the electronic structure of the high spin and low spin states in the Fe(pyridine)2Ni(CN)4 metal–organic framework (MOF). The relative energy of the spin states involved in SCO has been calculated, and the degeneracy line exhibiting a strong dependence on the distance between an Fe ion and the CN groups has been identified. The degeneracy line also displays a step-like dependence on the position of the pyridine ligands in the narrow interval of 2.08–2.10 Å, while outside this interval, the dependence is weak. Low-temperature paramagnetism of the Fe(pyridine)2Ni(CN)4 SCO-MOF has been explained by the triplet ground state of Ni in the square-planar coordination with the CN groups. The electronic structure of a recently synthesized Fe2(H0.67bdt)3 SCO-MOF has been also investigated. This MOF contains two types of Fe ions and exhibits unusual spin crossover behavior above room temperature. Our calculations confirm that in the temperature range of 300–423 K, Fe2 ions undergo a spin transition from quintet (S = 2) to singlet (S = 0), while Fe1 ions exist in the low-spin configuration in both initial (300 K) and final structures (423 K).
Publisher Correction: The impact of pre-existing aortic stenosis and mitral regurgitation on patients with acute myocardial infarction
Self-assembly and non-equilibrium phase coexistence in a binary granular mixture
We report the experimental observation of a square crystalline phase in a vibrated binary mixture of spherical grains. This structure spontaneously forms from a disordered state, consistently with predictions obtained in an equilibrium system with similar geometrical properties under conservative dynamics. By varying the area fraction, we also observe stable coexistence between a granular fluid and an isolated square crystal. Using realistic simulations based on the discrete element method and an idealized collisional model integrated via event-driven molecular dynamics, we not only reproduce experimental results but also help to gain further insights into the non-equilibrium phase coexistence. Through the direct phase coexistence method, we demonstrate that the system shows behavior highly similar to an equilibrium first-order phase transition. However, the crystal remains at a higher granular temperature than the fluid, which is a striking non-equilibrium effect. Through qualitative arguments and supported by kinetic theory, we elucidate the role of the coupling between local structure and energy transfer mechanisms in sustaining kinetic temperature gradients across the fluid–solid interface.
Publisher Correction: Characterization of aroma profiles and microbial communities of cigar tobacco leaves from different varieties and origins and their correlations analysis
Molecular dynamics of ice-active solutions at ice–water interfaces
Small molecules that interact strongly with water were the subject of this molecular dynamics (MD) study. These solutes include a cryoprotectant (DMSO), a polyalcohol [CH2(OH)2], carboxylic acid conjugates (HCOOH and HCOONa), an ammonium salt (NH4Cl), and two alkyl halide salts (NaCl and NaF). MD simulations were carried out for bulk supercooled liquids and solutions in contact with ice. Solute and water hydrogen bonding, orientational and translational order, and hydrogen bond jump dynamics were compared in bulk and as a function of distance from the solute molecules. Reverse non-equilibrium molecular dynamics simulations were used to determine interfacial widths, friction coefficients (κ) with ice, and solution phase viscosities (η). Ionic solutes were found to reduce orientational and translational ordering near the ice interfaces. However, in bulk liquids, we find a correlation between orientational ordering and the statistics of water hydrogen bonds—a donor–acceptor imbalance in water has the greatest impact on ordering in the bulk liquids. Although ionic solutions exhibited similar effects on the water structure, the effect on dynamics depends most directly on donor–acceptor imbalance. Solutes that are hydrogen bond acceptors were found to slow hydrogen bond lifetimes relative to hydrogen bond donors. We also observed a direct correlation between the liquid phase hydrogen-bond jump times and shear viscosity. Finally, of all the solutes studied, only DMSO and sodium formate exhibited increased friction at the ice–water interface.
Frequency-multiplexed tunable logic device based on terahertz graphene-integrated metamaterial composed of two circular ring resonator array
An instantaneous voice-synthesis neuroprosthesis
Thermochemical properties of anhydrous crystals and molten alkali metal halide salts from molecular simulations of phase-transferable polarizable force fields
Alkali halides find application not only under standard thermodynamic conditions but also at elevated temperatures, for example, in molten salt reactors or heat transfer and storage in solar applications. This study presents the temperature dependence of the thermochemical properties of their salts at normal pressure and temperatures ranging from 298.15 K up to the boiling points of the salts. The values were obtained using molecular simulations with polarizable DLM/2022-BK3 force fields. In most cases, our results show excellent agreement with experiments and often similar or better predictive capability compared to the most accurate polarizable models available in the literature developed for simulations of anhydrous alkali halides. Relatively worse predictions are observed for salts in which very small anions strongly polarize large cations. Our results for density, energy, chemical potential, and heat capacity of melts and crystals, and also melting temperatures, confirm the excellent phase transferability of the force fields used. They also serve as a substitute for missing experimental data for rubidium and cesium halides and highlight inaccuracies in some experimental data for the densities of LiBr, NaF, and NaBr crystals found in the literature.
Comparison of combined femoral nail and plate fixation versus dual plate fixation in the treatment of AO/OTA 33C distal femoral fractures
Neuromorphic heat transport effects in a molecular junction
Understanding energy transport at the nanoscale is an open and fundamental challenge in the molecular sciences with direct implications for the design of new electronics, computing devices, and materials. While nanoscale energy transport under steady-state conditions has been studied extensively, there is much less known about energy transport under time-dependent driving forces, particularly in the far-from-equilibrium regime. In this work, we use nonequilibrium molecular dynamics simulations and stochastic thermodynamics to investigate energy transport in a well-studied nanoscale system—a molecular junction—subjected to a time-periodic temperature gradient. The primary observation is that molecular junctions can exhibit heat transport hysteresis, a phenomenon in which the heat flux through a system depends not only on the instantaneous value of a time-dependent temperature bias but also on the temporal history of that bias. The presented findings illustrate that molecular junctions can exhibit the specific memory effect—heat transport hysteresis—that is essential for the design of thermal neuromorphic computers. This work elucidates a potential pathway toward the realization of such devices.
Reimagining falls prevention with insights from systems mapping on the use of millimetre-wave radar for remote health monitoring
Abstract Falls constitute a significant public health concern, demanding innovative solutions that transcend traditional methodologies. Current falls practice focuses on reactive post-fall assessment and management rather than proactive prevention and mitigation. We propose that millimetre-wave radar technology for real-time, continuous falls risk screening at home may address the limitations of current falls practice. To investigate the feasibility of this solution, we interviewed five experts in physiotherapy, falls prevention among older adults, and comprehensive geriatric assessment to identify the current state of play and potential for changes to falls practice. We applied a novel technique, systems mapping, to visually illustrate and analyse the interactions between components of current and proposed systems for addressing falls and constructed two conceptual maps: First, the current system was mapped by asking experts about the causal relationships between 15 system components. Second, to examine the feasibility of the proposed system, the components related to falls risk screening were replaced by radar-based home monitoring and experts were asked to re-evaluate the causal relationships between system components. Next, four scenarios (no fear of falling, no mobility limitation, maximising screening in the current system, maximising radar-based screening) were applied using the maps. Experts identified mobility deterioration and previous falls as key indicators of future falls, noting that increased screening in current practice could reduce risks but increase healthcare professionals’ workloads. Experts were positive about radar-based wireless home monitoring, believing it could reduce fall risks whilst reducing all fall-related costs. These findings suggest that, according to experts, millimetre-wave radar can be an effective solution in advancing falls prevention.
Nonlinear response from linear oscillators: Gas phase 2D action spectroscopy
There have been rapid developments in new spectroscopic methods to collect coherent multidimensional optical spectra using incoherent action-detection schemes such as fluorescence or photocurrents. Recently, we demonstrated the acquisition of two-dimensional infrared (2D IR) spectra of molecular ions cryogenically cooled in the gas phase measured from photodissociation of a weakly bound N2 “tag” molecule. Important differences exist between traditional multidimensional spectra and their action-based counterparts, which are now just being fully realized. Here, we apply standard nonlinear response theory in the pure-dephasing limit to model the cryogenic ion 2D IR spectra of the complex fac-Re(CO)3(CH3CN)3+ in the carbonyl stretch region. The simulated spectra show overall good agreement with the experiment and provide key insights into some of the unique characteristics of action-based 2D spectra. Notably, cryogenic ion 2D IR spectra only display bleaching features and inherent cross peaks between all excited vibrational modes. Action-based 2D IR spectra, therefore, can be measured even in the absence of anharmonicity and anharmonic coupling between modes. While the response from any single mode can be fully modeled from parameters measured in the linear spectrum, under multi-mode excitation both diagonal and cross-peak intensities also depend on the relative dipole moment orientations of other vibrational modes on the same molecule, a quantity not available from linear spectra and often not easily obtained in traditional nonlinear spectroscopy.