Browse Articles

Finite element analysis for pullout resistance and progressive failure of strip anchors in strain softening marine soils

Decoherence dynamics in molecular qubits: Exponential, Gaussian and beyond

In this work, we examine how the structure of system–bath interactions can determine commonly encountered temporal decoherence patterns, such as Gaussian and exponential decay, in molecular and other qubits coupled to a thermal bosonic bath. The analysis, based on a pure dephasing picture that admits analytical treatment, shows that decoherence, in general, is neither purely Gaussian nor exponential but rather the exponential of oscillatory functions, with periods determined by the bath’s frequencies. For initially unentangled qubit-bath states, Gaussian decay is always present at early times. It becomes increasingly dominant with increasing temperature, qubit–bath interaction strength, and bath correlation time. Initial system–bath entanglement that arises due to displacement in the position of the bath states preserves the Gaussian decay. By contrast, strict exponential decay arises only in very specific models that we isolate. However, it becomes dominant for times longer than the bath correlation time or for early times when there is initial entanglement due to momentum displacement of the bath states. For molecular electronic decoherence, the long-time exponential regime plays a limited role as it emerges after most coherence is lost. Thus, the Gaussian decay provides a more suitable (albeit imperfect) model of such decoherence. Furthermore, we discuss the connection between electronic decoherence dynamics and electronic spectroscopic line shape theory, where Gaussian spectral peaks correspond to Gaussian coherence decay and Lorentzian peaks correspond to exponential coherence decay. We find that Gaussian spectral peaks, usually associated with inhomogeneous broadening, can emerge from the entangling unitary system–bath dynamics even when there is no inhomogeneity in the initial conditions.

The DYT6 dystonia causative protein THAP1 is responsible for proteasome activity via PSMB5 transcriptional regulation

Abstract The proteasome plays a pivotal role in protein degradation, and its impairment is associated with various pathological conditions, including neurodegenerative diseases. It is well understood that Nrf1 coordinates the induction of all proteasome genes in response to proteasome dysfunction. However, the molecular mechanism regulating the basal expression of the proteasome remains unclear. Here we identify the transcription factor THAP1, the causative gene of DYT6 dystonia, as a regulator of proteasome activity through a genome-wide genetic screen. We demonstrated that THAP1 directly regulates the expression of the PSMB5 gene, which encodes the central protease subunit β5. Depletion of THAP1 disrupts proteasome assembly, leading to reduced proteasome activity and the accumulation of ubiquitinated proteins. These findings uncover a regulatory mechanism for the proteasome and suggest a potential role for proteasome dysfunction in the pathogenesis of dystonia.

Structural, chemical, and electronic control in Co–SiNx granular metals for high-pass filter applications

Granular metals, consisting of nanoscale conducting and insulating regions, have been studied for more than 50 years for fundamental and applied research. Granular metals exhibit non-linear conductivity vs frequency behavior, consistent with the universal power law response, and have recently been suggested for high-pass filter applications. Here, we report that cobalt–silicon nitride (Co–SiNx) granular metals with optimized sputter conditions and post-growth annealing exhibit an exceptional 109 increase in conductivity at 1 MHz compared to the DC conductivity. The improved frequency response is correlated with structural and chemical improvements examined via scanning transmission electron microscopy and x-ray photoemission spectroscopy. While we focus on improvements for high-pass filter applications, the structural, chemical, and electronic control demonstrated here will benefit a variety of granular metal and nanoparticle applications.

Changes in long-term life expectancy and years of life lost following the Great East Japan Earthquake in Fukushima Prefecture

Abstract Prolonged evacuation after disasters increases the risks of diseases and challenges in healthcare access. This study aimed to analyze changes in life expectancy (LE) and years of life lost (YLL) in Fukushima Prefecture after the Great East Japan Earthquake. LE and YLL were calculated based on a dataset of 276,314 deaths in Fukushima Prefecture from January 2006 to December 2018 and were aggregated and compared in three time periods: 2006–2010, 2012–2015, and 2016–2018. LE and YLL were obtained using a life table method, focusing on four major causes of death: heart diseases, cerebrovascular diseases, pneumonia, and cancers. The overall LE for both males and females in Fukushima prefecture showed an increasing trend in all three periods. Notably, in 2012–2015, the increase in LE and YLL due to cancer was greater in areas with evacuation zones compared to those without evacuation zones. In contrast, in 2016–2018, a notable decrease in YLL due to cerebrovascular diseases for both males and females and due to heart diseases for males was observed in areas with evacuation zones compared to areas without. LE continued to rise in Fukushima Prefecture despite the significant long-term impact of the disaster on the population. Post-disaster changes in LE and YLL differed between areas with and without evacuation zones, suggesting that implementation of effective measures and policies in the region contributed to a successful recovery. This study may be crucial for evaluating future health measures and conditions in Fukushima Prefecture.

Photoelectron–remnant interaction effect on remnant wavefunction in low-kinetic energy electron detachment events

Low-kinetic energy photoelectron detachment experiments have revealed the unexpected dependence of transition intensities on photon energy, which is hypothesized to result from time-dependent coupling between low-kinetic energy photoelectrons and the remnant molecule. This study explores how the kinetic energy and detachment axis of the photoelectron influence the interaction and modify the final remnant electronic structure. Using real-time simulations on several model systems (H2, NO, N2, and C2 hydrocarbons), this study demonstrates that electron–remnant interactions are strongly dependent on the detachment orientation, electron kinetic energy, and remnant electronic structure. The results reveal that higher kinetic energies lead to significant nonadiabatic transitions, while lower kinetic energies yield more adiabatic behavior. While generally lower kinetic energies show prolonged electron–remnant interactions, the extent of temporal and spatial interactions does not necessarily vary linearly with the kinetic energy, and the final remnant electronic structure is found to be very sensitive to the exact nature of the photoelectron–remnant interactions. In addition, the point charge model employed for the photoelectron provides a useful approach for the deconvolution of more complete simulations to provide deeper insights into the specific photoelectron–remnant interactions that determine the eventual remnant wavefunction. The findings underscore the importance of considering both temporal and spatial electron dynamics in understanding low-kinetic energy photodetachment processes and provide a foundation for a further exploration of electron–molecule interactions in the low-energy regime.

Model-constrained deep learning for online fault diagnosis in Li-ion batteries over stochastic conditions

Impacts of silicon carbide defects on electrical characteristics of SiC devices

With more than thirty years of research and development until commercialization, performance, reliability, and robustness of silicon carbide (SiC) based devices have been improved significantly due to drastic reduction in crystal defects from the well-controlled processes of crystal growth and device fabrication. It is crucial to investigate the effects of SiC crystal defects on the electrical characteristics of devices. Here, an up-to-date development of the correlation between crystal defects of SiC with electrical performance of the devices has been reviewed. The effect of defects on the electrical parameters of the device and the failure mechanism are discussed, and the development of SiC in recent years is prospected.

Fairness identification of large language models in recommendation

Erratum: “Modeling of collision-induced excitation and quenching of atomic nitrogen” [J. Chem. Phys. 161, 014104 (2024)]

Morphology of ejecta features from the impact on asteroid Dimorphos

Abstract Hypervelocity impacts play a significant role in the evolution of asteroids, causing material to be ejected and partially reaccreted. However, the dynamics and evolution of ejected material in a binary asteroid system have never been observed directly. Observations of Double Asteroid Redirection Test (DART) impact on asteroid Dimorphos have revealed features on a scale of thousands of kilometers, including curved ejecta streams and a tail bifurcation originating from the Didymos system. Here we show that these features result naturally from the dynamical interaction of the ejecta with the binary system and solar radiation pressure. These mechanisms may be used to constrain the orbit of a secondary body, or to investigate the binary nature of an asteroid. Also, they may reveal breakup or fission events in active asteroids, and help determine the asteroid’s properties following an impact event. In the case of DART, our findings suggest that Dimorphos is a very weak, rubble-pile asteroid, with an ejecta mass estimated to be in the range of (1.1-5.5)×107 kg.

Enhancing interfacial thermal transport by nanostructures: Monte Carlo simulations with <i>ab initio</i> phonon properties

Recent experiments have indicated that employing nanostructures can enhance interfacial heat transport, but the mechanism by which different structural morphologies and dimensions contribute to the full-spectrum phonon interfacial transport remains unclear. In this paper, a multiscale method to study the thermal transfer at nanostructured interfaces is developed by combining the density functional calculation, Monte Carlo simulation, and diffuse mismatch method. The changes in the transport paths and contributions to the thermal conductance of different frequency phonons caused by the changes in the nanostructure morphology and size are investigated. The results show that, compared to the triangular and trapezoidal nanostructures, rectangular nanostructures are more beneficial in enhancing the probability of the reflected phonons encountering the interface and, thus, the phonon interfacial transmittance. The nanostructure makes the interfacial heat flow extremely heterogeneous, with significant transverse heat flow occurring at the sidewalls, resulting in a new thermal conduction pathway. The phenomena of multiple reflections and double transmission together lead to the existence of the optimal dimension that maximizes the nanostructure’s enhancement effect on interfacial heat transfer. The optimal nanostructure width is 100 nm when the height is 100 nm and the maximum interfacial thermal conductance enhancement ratio is 1.31. These results can guide the design of heat transfer enhancement structures at the interface of the actual high-power chips.

The superoxide dismutase mimetic TEMPOL modulates nicotine-induced hyperlocomotor activity and nicotine-taking behavior in male rats

On the entanglement of chromophore and solvent orbitals

Among various types of chromophore–solvent interactions, the entanglement of chromophore and solvent orbitals, when significant, can cause the chromophore frontier orbitals to spread over to nearby solvent molecules, introducing partial charge-transfer character to the lowest excitations of the chromophore and lowering the excitation energies. While highly intuitive, the physical details of such orbital entanglement effects on the excitation energies of chromophores have yet to be fully explored. Here, using two well-known biochromophores (oxyluciferin and p-hydroxybenzyledene imidazolinone) as examples, we show that the chromophore–solvent orbital entanglements can be elucidated using two quantum mechanical embedding schemes: density matrix embedding theory and absolutely localized molecular orbitals. However, there remains a great challenge to incorporate the orbital entanglement effect in combined quantum mechanical molecular mechanical (QM/MM) calculations, and we hope that our findings will stimulate the development of new methods in that direction.

Evaluation of Cas13d as a tool for genetic interaction mapping

Abstract Mapping genetic interactions (GIs) is crucial for understanding genetic network complexity. In this study, we investigate the utility of Cas13d, a CRISPR system targeting RNA, for GI mapping and compare it to Cas9 and Cas12a, two DNA nucleases commonly used for GI mapping. We find that Cas13d induces faster target gene perturbation and generates more uniform cell populations with double perturbations than Cas9 or Cas12a. We then encounter Cas13d gRNA-gRNA interference when concatenating gRNAs targeting different genes into one gRNA array, which we overcome by a dual promoter gRNA expression strategy. Moreover, by concatenating three gRNAs targeting the same gene into one array, we are able to maximize the Cas13d-mediated knockdown effects. Combining these strategies enhances proliferation phenotypes while reducing library size and facilitates reproducible quantification of GIs in oncogenic signaling pathways. Our study highlights the potential of Cas13d for GI mapping, promising advancements in understanding therapeutically relevant drug response pathways.

Modeling carrier trapping at semiconductor/dielectric interfaces based on first-principles calculations of nonradiative capture

We demonstrate a quantitative framework to evaluate a nonradiative capture process with multiphonon emission in a semiconductor/dielectric heterostructure, mediated by a tunneling process. In addition to evanescent tunneling decay, the presence of an internal electric field modifies the relative energy depth of the carrier trap depending on the distance, modulating the overall capture behavior. We quantitatively derive the capture rate based on the parameters of the device structure (gate voltage, threshold voltage, dielectric material thickness, and temperature). We benchmark the formalism for the case of a Si/SiO2 heterostructure, using an isolated Si dangling bond in α-quartz as a prototype defect in silica. We find that the calculated capture coefficients show a nonmonotonic trend as a function of distance of the defect from the interface, due to countervailing trends in capture barrier and wave-function decay. The predicted capture rates are in reasonable agreement with experimentally measured capture time constants, showing promise for the application of this compact model.

Goos–Hänchen shift of inelastically scattered spin-wave beams and cascade nonlinear magnon processes

Abstract We study, using micromagnetic simulations, the inelastic scattering of spin-wave beams on edge-localized spin-wave modes in a thin ferromagnetic film. In the splitting and confluence processes, the new spin-wave beams are generated with frequencies shifted by the edge-mode frequency. We report that inelastically scattered spin-wave beams in both processes not only change their direction of propagation but also undergo lateral shifts along the interface, analogous to the Goos–Hänchen effect known in optics. These shifts of inelastically scattered beams, for a few special cases described in the paper, can be in the range of several wavelengths, which is larger than the Goos–Hänchen shift of elastically reflected beam. Unexpectedly, at selected frequencies, we found a significant increase in the value of the lateral shifts of the scattered spin-wave beams formed in the confluence process. We show that this effect is associated with the cascading nonlinear processes taking place at the edge of the film and involving the primary edge spin wave. Our results make an important contribution to the understanding of the nonlinear nature of spin waves and provide a way to exploit it in signal processing with magnons.

The vibrational wavepackage dynamics and phase modulation via the resonant Rydberg states in molecules

The observation of vibrational coherence has become significant because it reflects the spatial and temporal localization of a nucleus in a specific mode and characterizes energy flow and multiple kinetic relaxations in chemical dynamics. Vibrational coherence in the S1 state of 2,4-difluoroanisole has been investigated in real time by femtosecond time-resolved photoelectron spectroscopy and time-of-flight mass spectroscopy. Quantum beats of superpositions exhibit temporal oscillations with a frequency of 78 cm−1. Combining the structure computations, oscillations derive from the structure change from planar to nonplanar geometry, which correspond the coherence wavepackets moving from the Franck–Condon region toward the minimum point of the potential energy surface, elucidating the energy flows following the excitation of 2,4-difluoroanisole in the S1 state. The phases of the quantum beat via the resonant Rydberg states exhibit a shift of π rad. The vibrational coherent phase modulation via the resonant Rydberg states will facilitate the chemical coherence control in complex molecular systems.

The anti-GD2 monoclonal antibody naxitamab plus GM-CSF for relapsed or refractory high-risk neuroblastoma: a phase 2 clinical trial

Abstract In this single-arm, non-randomized, phase 2 trial (NCT03363373), 74 patients with relapsed/refractory high-risk neuroblastoma and residual disease in bone/bone marrow (BM) received naxitamab on Days 1, 3, and 5 (3 mg/kg/day) with granulocyte-macrophage colony-stimulating factor (Days -4 to 5) every 4 weeks, until complete response (CR) or partial response (PR) followed by 5 additional cycles every 4 weeks. Primary endpoint in the prespecified interim analysis was overall response (2017 International Neuroblastoma Response Criteria). Among 26 responders (CR + PR) in the efficacy population (N = 52), 58% had refractory disease, and 42% had relapsed disease. Overall response rate (ORR) was 50% (95% CI: 36-64%), and CR and PR were observed in 38% and 12%, respectively. With the 95% CI lower limit for ORR exceeding 20%, the primary endpoint of overall response was met. Patients with evaluable bone disease had a 58% (29/50) bone compartment response (CR, 40%; PR, 18%). BM compartment response was 74% (17/23; CR, 74%). One-year overall survival and progression-free survival (secondary endpoints) were 93% (95% CI: 80-98%) and 35% (95% CI: 16-54%), respectively. Naxitamab-related Grade 3 adverse events included hypotension (58%) and pain (54%). Overall, naxitamab demonstrated clinically meaningful efficacy with manageable safety in patients with residual neuroblastoma in bone/BM.

Systematic investigation of anomalous Hall effect in Fe–Pt composition-spread epitaxial films for magnetic sensor application

Magnetic field sensors based on the anomalous Hall effect (AHE) require a magnetic thin film with high anomalous Hall resistivity (ρyxA) and moderate perpendicular uniaxial magnetic anisotropy (Ku) to achieve both a large linear sensitivity and a dynamic range (DR) adaptable for various applications. In this study, we fabricate Fe1−xPtx(0≤x≤1) composition-spread epitaxial thin films and systematically investigate the composition dependence of the AHE, aiming to achieve high sensitivity for the magnetic field sensors. We also explore the underlying physical mechanism of the AHE in the Fe–Pt binary system. Structural analysis reveals the [001]-oriented epitaxial growth, featuring distinct phases of A2-Fe, L12-Fe3Pt, L10-FePt, and L12-FePt3 as increasing x along with their mixed-phases, except for the Pt-rich region. Among the entire Fe1−xPtx, an off-stoichiometric Fe-rich composition Fe0.70Pt0.30 exhibits the highest ρyxA of 4.5 μΩ cm with a linear response to the external magnetic field and a DR of 600 mT, yielding a high sensitivity of 8 μΩ cm/T. The DR can be tuned in a wide range from 600 to 1400 mT by changing the Fe:Pt composition ratio, which is attributed to the variation in Ku and magnetization in the Fe–Pt binary alloy system. The anomalous Hall conductivity (AHC) shows an oscillatory variation with composition x, with the largest AHC of 1261 S/cm observed for Fe0.70Pt0.30. The theoretical calculation of the AHC for A2-Fe and L12-Fe3Pt, including the analysis of the density of states for the off-stoichiometric compositions, suggests that the overall variation in AHC with x can be mostly explained by an intrinsic mechanism and the electron doping effect introduced by Pt addition. Theoretical analysis supports that the highest sensitivity obtained in Fe0.70Pt0.30 originates from the large intrinsic AHC (1759 S/cm) predicted for L12-Fe3Pt.