bluuebunny/crossref_metadata_2025 huggingface dataset:
Transitions between surface force- and inertia-dominant contact dynamics regimes in high-speed scanning probe microscopy
Authors: Dey S. , Kartik V.
Published: May 2023

In contact mode scanning probe microscopy (SPM), the microcantilever probe’s dynamics are governed by the (short-range) surface interaction forces, where the tip is “always-in-contact” with the sample. In intermittent contact modes such as “tapping” or bimodal SPM, on the other hand, these are governed by the frequency of the microcantilever’s own external excitation. However, when contact mode is employed with high scan speeds (for “video-rate” SPM), we see intermittent transitions—within a single oscillation cycle—between the “always-in-contact” regime and another which is dominated by the microcantilever’s inertia. We find—through experiments and physical modeling—that the fast in-plane motion of the sample relative to the probe results in a high surface excitation frequency v/λ (and its harmonics), which excite the microcantilever’s out-of-plane eigenmodes and cause it to “break free” of the surface and “overshoot” and “parachute.” The impacts of the tip that consequently occur upon the sample inject energy over a wide frequency band into the higher eigenmodes, especially when operating in a low dissipation ambient environment. The microcantilever, then, exhibits phenomena such as eigenmode switching, sidebands, and fractional and combination resonances; such behavior is not seen in, say, tapping mode SPM, since, there, energy is injected at an externally-determined temporal rate. This article investigates the transition from the dynamics of the microcantilever at low speeds to that exhibited at high speeds. The model for dynamic contact loss is validated against the experiments and can be used to propose mitigation of such dynamics in order to achieve high-resolution imaging.
Development of NOTCH, an all-electron, beyond-NDDO semiempirical method: Application to diatomic molecules
Authors: Wang Zikuan , Neese Frank
Published: May 2023

In this work, we develop a new semiempirical method, dubbed NOTCH (Natural Orbital Tied Constructed Hamiltonian). Compared to existing semiempirical methods, NOTCH is less empirical in its functional form as well as parameterization. Specifically, in NOTCH, (1) the core electrons are treated explicitly; (2) the nuclear–nuclear repulsion term is calculated analytically, without any empirical parameterization; (3) the contraction coefficients of the atomic orbital (AO) basis depend on the coordinates of the neighboring atoms, which allows the size of AOs to depend on the molecular environment, despite the fact that a minimal basis set is used; (4) the one-center integrals of free atoms are derived from scalar relativistic multireference equation-of-motion coupled cluster calculations instead of empirical fitting, drastically reducing the number of necessary empirical parameters; (5) the (AA|AB) and (AB|AB)-type two-center integrals are explicitly included, going beyond the neglect of differential diatomic overlap approximation; and (6) the integrals depend on the atomic charges, effectively mimicking the “breathing” of AOs when the atomic charge varies. For this preliminary report, the model has been parameterized for the elements H–Ne, giving only 8 empirical global parameters. Preliminary results on the ionization potentials, electron affinities, and excitation energies of atoms and diatomic molecules, as well as the equilibrium geometries, vibrational frequencies dipole moments, and bond dissociation energies of diatomic molecules, show that the accuracy of NOTCH rivals or exceeds those of popular semiempirical methods (including PM3, PM7, OM2, OM3, GFN-xTB, and GFN2-xTB) as well as the cost-effective ab initio method Hartree–Fock-3c.
234 nm far-ultraviolet-C light-emitting diodes with polarization-doped hole injection layer
Authors: Kolbe Tim , Knauer Arne , Rass Jens , Cho Hyun Kyong , Hagedorn Sylvia , Bilchenko Fedir , Muhin Anton , Ruschel Jan , Kneissl Michael , Einfeldt Sven , Weyers Markus
Published: May 2023

Far-ultraviolet-C (far-UVC) light-emitting diodes (LEDs) with an emission wavelength of 234 nm with different polarization-doped AlGaN hole injection layers (HILs) are compared regarding their emission power, voltage, and leakage current. The influence of the thickness of the polarization-doped layer (PDL), an additional Mg doping of the PDL, as well as a combination of a PDL with a conventionally Mg-doped AlGaN HIL will be discussed. The different PDL thicknesses show nearly no influence on the emission power or voltage. However, the leakage current of the LEDs below the turn-on voltage decreases with an increasing thickness of the PDL. In contrast, an additional Mg doping of the PDL ([Mg] ∼ 1.5 × 1019 cm−3) results in a fivefold decrease in the emission power at an unchanged voltage and leakage current. Finally, a combination of a PDL and a conventionally Mg-doped AlGaN layer ([Mg] ∼ 1.5 × 1019 cm−3) as a HIL shows also a similar emission power and voltage compared to the single PDL, but the leakage current increases. Based on these optimizations, 234 nm LEDs were realized with a maximum external quantum efficiency of 1% at 20 mA, an emission power of 4.7 mW, and a voltage of 9.0 V at 100 mA. This shows that the polarization doping concept is well suited to realize far-UVC LEDs with improved performance compared to LEDs with a conventionally Mg-doped p-side.
Topological ventilated sound switch from acoustic Su-Schrieffer–Heeger model
Authors: Li Qinhong , Xiang Xiao , Wang Li , Huang Yingzhou , Wu Xiaoxiao
Published: May 2023

In the last two decades, the emergence of acoustic metamaterials has offered previously unimaginable possibilities for extraordinary control of sound waves. For example, various extremely light-weight sound attenuation systems based on metamaterials and phononic crystals have been demonstrated. Equipped with reconfigurability, such systems will provide the on-demand controls of the passage or stopping of sound waves and are often called acoustic switches or sound switches. However, so far, no ventilated sound switch has been proposed, which can realize both satisfying sound transmission and ventilation. In this work, we demonstrate a topological ventilated sound switch achieving switchable transmission. This switch is based on the one-dimensional acoustic Su-Schrieffer–Heeger model, which leads to the appearance of the topological interface states, and the sound can be turned on or off with the desired ventilation performance. With only one topological unit, the high transmission ratio (∼20 dB) before and after switch has been demonstrated in both simulations and experiments. It should have potential applications in areas of the acoustic engineering where both specific frequency sound transmission and ventilation are required.
Giant magnetostriction effect in LaFe12B6 metamagnet
Authors: Diop L. V. B. , Prokleška J. , Isnard O.
Published: May 2023

We investigate the complex magnetic behavior of LaFe12B6 by means of magnetostriction, and thermal expansion measurements in applied fields of up to 14 T, elucidating the interplay between crystal lattice and spins. As main results, we have discovered a remarkably large negative thermal expansion (NTE) and giant magnetostriction in this itinerant-electron system. Of particular interest are the low-temperature magnetostriction isotherms (T ≤ 5 K) all of which reach saturation discontinuously, by way of ultrasharp multistep transitions. These are rather unusual kind of first-order phase transitions. By contrast, the field-dependent magnetostriction varies smoothly at temperatures exceeding 5 K. A huge positive magnetostrictive effect of ΔV/V (20 K, 14 T) = 0.87% accompanies the field-induced first-order metamagnetic transition. In the vicinity of the Curie point, a magnetically driven giant NTE phenomenon with an average linear thermal expansion coefficient αL = −27 × 10−6 K−1 is observed.
Thermal environment impact on HfOx RRAM operation: A nanoscale thermometry and modeling study
Authors: West Matthew P. , Pavlidis Georges , Montgomery Robert H. , Athena Fabia Farlin , Jamil Muhammad S. , Centrone Andrea , Graham Samuel , Vogel Eric M.
Published: May 2023

As the demand for computing applications capable of processing large datasets increases, there is a growing need for new in-memory computing technologies. Oxide-based resistive random-access memory (RRAM) devices are promising candidates for such applications because of their industry readiness, endurance, and switching ratio. These analog devices, however, suffer from poor linearity and asymmetry in their analog resistance change. Various reports have found that the temperature in RRAM devices increases locally by more than 1000 K during operation. Therefore, temperature control is of paramount importance for controlling their resistance. In this study, scanning thermal microscopy is used to map the temperature of Au/Ti/HfOx/Au devices at a steady power state and to measure temperature dynamics of the top electrode above the filament location during both resistive switching loops and voltage pulsing. These measurements are used to verify the thermal parameters of a multiphysics finite elements model. The model is then used to understand the impact of thermal conductivities and boundary conductances of constituent materials on resistance change during the first reset pulse in RRAM devices. It is found that the resistance change can be reduced significantly when the temperature in the titanium capping layer is reduced. We find that the greatest temperature reduction and, therefore, the lowest resistance change in the device are afforded by capping layers with increased thermal conductivities. This work links thermal properties to the resistance change in RRAM devices, providing critical insights into engineering devices with improved switching dynamics.
A hybrid stochastic configuration interaction–coupled cluster approach for multireference systems
Authors: Filip Maria-Andreea , Thom Alex J. W.
Published: May 2023

The development of multireference coupled cluster (MRCC) techniques has remained an open area of study in electronic structure theory for decades due to the inherent complexity of expressing a multiconfigurational wavefunction in the fundamentally single-reference coupled cluster framework. The recently developed multireference-coupled cluster Monte Carlo (mrCCMC) technique uses the formal simplicity of the Monte Carlo approach to Hilbert space quantum chemistry to avoid some of the complexities of conventional MRCC, but there is room for improvement in terms of accuracy and, particularly, computational cost. In this paper, we explore the potential of incorporating ideas from conventional MRCC—namely, the treatment of the strongly correlated space in a configuration interaction formalism—to the mrCCMC framework, leading to a series of methods with increasing relaxation of the reference space in the presence of external amplitudes. These techniques offer new balances of stability and cost against accuracy, as well as a means to better explore and better understand the structure of solutions to the mrCCMC equations.
Lossless imaging based on a donut-like optical sparse aperture metalens
Authors: Dong Yangeng , Sun Ti , Hu Jingpei , Lin Yu , Zeng Aijun , Huang Huijie , Wang Chinhua , Jiang Chunping
Published: May 2023

The optical sparse aperture approach has been shown to have significant potential in enlarging the aperture size and enhancing the imaging resolution of metalenses. However, because of frequency loss caused by the sparsity and dispersion of sparse aperture arrays, the stitch method for conventional optical sparse aperture metalenses has a non-uniform imaging resolution at different azimuth angles and cannot achieve the same resolution as the corresponding full-aperture metalens. Here, we design and demonstrate the application of a donut-like optical sparse aperture metalens with a lossless imaging property using a shear design method. This metalens has a diffraction-limited resolution of 153 lp/mm for all azimuth angles, which allows us to circumvent the non-uniform imaging resolution of the conventional optical sparse aperture metalens at different azimuth angles and enables us to achieve full resolution. Furthermore, noise resistance in practical images is achieved because of the improved modulation transfer function in the high-frequency region. Such a metalens without frequency loss has significant application potential in the fields of integrated optical systems, lightweight imaging devices, and wearable optics.
Matsubara dynamics approximation for generalized multi-time correlation functions
Authors: Videla Pablo E. , Batista Victor S.
Published: May 2023

We introduce a semi-classical approximation for calculating generalized multi-time correlation functions based on Matsubara dynamics, a classical dynamics approach that conserves the quantum Boltzmann distribution. This method is exact for the zero time and harmonic limits and reduces to classical dynamics when only one Matsubara mode is considered (i.e., the centroid). Generalized multi-time correlation functions can be expressed as canonical phase-space integrals, involving classically evolved observables coupled through Poisson brackets in a smooth Matsubara space. Numerical tests on a simple potential show that the Matsubara approximation exhibits better agreement with exact results than classical dynamics, providing a bridge between the purely quantum and classical descriptions of multi-time correlation functions. Despite the phase problem that prevents practical applications of Matsubara dynamics, the reported work provides a benchmark theory for the future development of quantum-Boltzmann-preserving semi-classical approximations for studies of chemical dynamics in condensed phase systems.
Spatial, spectral, and temporal properties of laser-induced plasma in air near an aqueous solution and comparison with ambient air
Authors: Helfman D. , Litwinowicz S. , Meng S. , Morgan T. J. , Hüwel L.
Published: May 2023

Laser-induced breakdown and subsequent plasma are produced in ambient air in the proximity of an aqueous surface using a Nd:YAG Q-switched laser at 1064 nm with a pulse width of 9 ns and a delivered focused input energy of 170 mJ. The distance between the focal point of a 10 cm convex lens and the aqueous surface is 4 mm with laser propagation perpendicular to the surface. Using an intensified CCD camera attached to a 1-m spectrometer, spatial and wavelength-resolved plasma emission data are obtained for delay times after breakdown ranging from 50 ns to 10 μs with a gate window typically 5 ns. Plasma electron density is determined by applying Lorentzian fitting and FWHM extraction to three Stark-broadened spectral lines: N II 3P-3Do multiplet (593.85 nm), Hα (656.27 nm), and the Na D doublet (589.00 and 589.59 nm). One-dimensional spatially resolved measurements of the total emission intensity and electron density are obtained by binning the camera image along the laser axis in intervals of 250 μm and are reported as a function of time from 50 ns to 10 μs. Two plasmas are ignited from a single laser pulse; one from laser breakdown at the water surface and the other a few nanoseconds later from laser-induced air breakdown at the focal point of 4 mm above the water surface. Comparisons between the evolution of the air plasma near and far from the water surface are presented along with data for the water surface plasma itself.
In-plane anisotropic photoelectric property of
α
-In2Se3 based phototransistor
Authors: Cai Chuanyang , Ling Shiyu , Hou Pengfei
Published: May 2023

Contributing to excellent photoelectric property, the tunable bandgap and intercorrelated in-plane and out-of-plane ferroelectric polarization simultaneously, α-In2Se3 has great potential in the applications of optoelectronic devices and photo-controlled devices, like memories, sensors, and synapses. However, little attention is paid to the in-plane anisotropic photoelectric property of α-In2Se3, which may restrict its competitiveness in application of designing and fabrication of optoelectronic devices and photo-controlled devices. Herein, multi-layered α-In2Se3 based phototransistors with eight terminals are prepared, and its in-plane anisotropic photodetection is investigated. By comparing the dark current (Idark), photocurrent (Iph), responsivity (R), external quantum efficiency (EQE), and specific detectivity (D*), in-plane anisotropic photoelectric property of multi-layered α-In2Se3 is demonstrated, and the Idark, Iph, R, EQE, and D* anisotropic ratios are up to 163.76, 480.59, 480.59, 480.59, and 58.8, respectively. The carrier mobility and the in-plane ferroelectric polarization are the two main factors determining the in-plane anisotropic photoelectric property. The excellent in-plane anisotropic photoelectric property makes α-In2Se3 a promising candidate as an in-plane anisotropic semiconductor for high-sensitivity optoelectronic and photo-controlled applications.
Transition moments beyond the electric-dipole approximation: Visualization and basis set requirements
Authors: van Horn Martin , List Nanna Holmgaard , Saue Trond
Published: May 2023

In the simulation of x-ray absorption spectroscopy, the validity of the electric-dipole approximation comes into question. Three different schemes exist to go beyond this approximation: the first scheme is based on the full semi-classical light–matter interaction, whereas the latter two schemes, referred to as the generalized length and velocity representation, are based on truncated multipole expansions. Even though these schemes have been successfully implemented in several quantum chemistry codes, their basis set requirements remained largely unknown. Here, we assess basis set requirements of these three schemes. We have considered 1s1/2 and 7s1/2 → 7p1/2 transitions in the radium atom, representative of core and valence excitations, respectively, and carried out calculations with dyall.aeXz (X = 2, 3, 4) basis sets at the four-component relativistic TD-HF level of theory. Our basis set study was greatly facilitated by the generation and visualization of radial distributions of transition moment densities, allowing for a straightforward comparison with equivalent finite-difference calculations. Pertaining to the truncated interaction, we find that the length representation electric multipole is the easiest to converge, requiring the dyall.ae2z basis for low-order multipoles and the dyall.ae4z basis at higher orders. The magnetic multipole moments follow a similar trend although they are more difficult to converge. The velocity representation electric multipoles are the most difficult to converge: at high orders, the dyall.ae3z and dyall.ae4z basis sets introduce artificial peaks and oscillations, which increase the overall error. These artifacts are associated with linear dependence issues in the small component space of larger basis sets. The full interaction operator, however, does not suffer from these problems, and we therefore recommend its use in the simulation of x-ray spectroscopy.
Collective dynamics and self-motions in the van der Waals liquid tetrahydrofuran from meso- to inter-molecular scales disentangled by neutron spectroscopy with polarization analysis
Authors: Arbe Arantxa , Nilsen Gøran J. , Devonport Mark , Farago Bela , Alvarez Fernando , Martínez González José A. , Colmenero Juan
Published: May 2023

By using time-of-flight neutron spectroscopy with polarization analysis, we have separated coherent and incoherent contributions to the scattering of deuterated tetrahydrofuran in a wide scattering vector (Q)-range from meso- to inter-molecular length scales. The results are compared with those recently reported for water to address the influence of the nature of inter-molecular interactions (van der Waals vs hydrogen bond) on the dynamics. The phenomenology found is qualitatively similar in both systems. Both collective and self-scattering functions are satisfactorily described in terms of a convolution model that considers vibrations, diffusion, and a Q-independent mode. We observe a crossover in the structural relaxation from being dominated by the Q-independent mode at the mesoscale to being dominated by diffusion at inter-molecular length scales. The characteristic time of the Q-independent mode is the same for collective and self-motions and, contrary to water, faster and with a lower activation energy (≈1.4 Kcal/mol) than the structural relaxation time at inter-molecular length scales. This follows the macroscopic viscosity behavior. The collective diffusive time is well described by the de Gennes narrowing relation proposed for simple monoatomic liquids in a wide Q-range entering the intermediate length scales, in contraposition to the case of water.
Blocking polysulfide by physical confinement and catalytic conversion of SiO2@MXene for Li–S battery
Authors: Zhang Chaoyue , Feng Junan , Guo Xin , Zhang Jinqiang , Zhang Wenxue , Zhang Lixue , Song Jianjun , Shao Guangjie , Wang Guoxiu
Published: May 2023

Lithium–sulfur (Li–S) batteries have attracted increasing attention for next-generation energy storage systems with a high energy density and low cost. However, the practical applications have been plagued by the sluggish reaction kinetics and the shuttle effect of lithium polysulfides (LiPSs). Herein, core–shell SiO2@Ti3C2Tx MXene (SiO2@MX) hollow spheres are constructed as multifunctional catalysts to boost the performance of Li–S batteries. The dual-polar and dual-physical properties of SiO2 core and MXene shell provide multiple defense lines to the shuttle effect by chemical and physical confinement to LiPSs. Density functional theory calculations prove that Ti3C2Tx MXene and SiO2 enable the stronger trapping ability of LiPSs and the fast Li2S decomposition process. With this strategy, the robust SiO2@MX/S electrodes deliver superior electrochemical performances, including a high capacity of 1263 mAh g−1, and remarkable cycling stability with an ultralow capacity decay of 0.04% per cycle over 1000 cycles at 1 C. This work highlights the significance of core-shell dual-polar structural sulfur catalysts for practical application in advanced Li–S batteries.
Coherence-limited digital control of a superconducting qubit using a Josephson pulse generator at 3 K
Authors: Castellanos-Beltran M. A. , Sirois A. J. , Howe L. , Olaya D. , Biesecker J. , Benz S. P. , Hopkins P. F.
Published: May 2023

Compared to traditional semiconductor control electronics (TSCE) located at room temperature, cryogenic single flux quantum (SFQ) electronics can provide qubit measurement and control alternatives that address critical issues related to scalability of cryogenic quantum processors. Single-qubit control and readout have been demonstrated recently using SFQ circuits coupled to superconducting qubits. Experiments where the SFQ electronics are co-located with the qubit have suffered from excess decoherence and loss due to quasiparticle poisoning of the qubit. A previous experiment by our group showed that moving the control electronics to the 3 K stage of the dilution refrigerator avoided this source of decoherence in a high-coherence three-dimensional transmon geometry. In this paper, we also generate the pulses at the 3 K stage but have optimized the qubit design and control lines for scalable two-dimensional transmon devices. We directly compare the qubit lifetime T1, coherence time T2*, and gate fidelity when the qubit is controlled by the Josephson pulse generator (JPG) circuit vs the TSCE setup. We find agreement within the daily fluctuations for T1 and T2*, and agreement within 10% for randomized benchmarking. We also performed interleaved randomized benchmarking on individual JPG gates demonstrating an average error per gate of 0.46% showing good agreement with what is expected based on the qubit coherence and higher-state leakage. These results are an order of magnitude improvement in gate fidelity over our previous work and demonstrate that a Josephson microwave source operated at 3 K is a promising component for scalable qubit control.
Non-impact effects in the absorption spectra of HCl diluted in CO2, air, and He: Measurements and predictions
Authors: Tran Ha , Li Gang , Ngo Ngoc Hoa , Ebert Volker
Published: May 2023

Non-impact effects in the absorption spectra of HCl in various collision-partners are investigated both experimentally and theoretically. Fourier transform spectra of HCl broadened by CO2, air, and He have been recorded in the 2-0 band region at room temperature and for a wide pressure range, from 1 to up to 11.5 bars. Comparisons between measurements and calculations using Voigt profiles show strong super-Lorentzian absorptions in the troughs between successive lines in the P and R branches for HCl in CO2. A weaker effect is observed for HCl in air, while for HCl in He, Lorentzian wings are in very good agreement with measurements. In addition, the line intensities retrieved by fitting the Voigt profile on the measured spectra decrease with the density of the perturber. This perturber-density dependence decreases with the rotational quantum number. For HCl in CO2, the decrease in the retrieved line intensity can reach 2.5% per amagat for the first rotational quantum numbers. This number is about 0.8% per amagat for HCl in air, while for HCl in He, no density dependence of the retrieved line intensity is observed. Requantized classical molecular dynamics simulations have been performed for HCl–CO2 and HCl–He in order to simulate the absorption spectra for various perturber-density conditions. The density dependence of the intensities retrieved from the simulated spectra and the predicted super-Lorentzian behavior in the troughs between lines are in good agreement with experimental determinations for both HCl–CO2 and HCl–He. Our analysis shows that these effects are due to incomplete or ongoing collisions, which govern the dipole auto-correlation function at very short times. The effects of these ongoing collisions strongly depend on the details of the intermolecular potential: they are negligible for HCl–He but significant for HCl–CO2 for which a line-shape model beyond the impact approximation will be needed to correctly model the absorption spectra from the center to the far wings.
Execution of stored programs by a rapid single-flux-quantum random-access-memory-embedded bit-serial microprocessor using 50-GHz clock frequency
Authors: Tanaka Masamitsu , Sato Ryo , Fujimaki Akira , Takagi Kazuyoshi , Takagi Naofumi
Published: May 2023

We have demonstrated the execution of several programs stored in an instruction memory by a rapid single-flux-quantum bit-serial 8-bit microprocessor named CORE e2h. We employed a minimal instruction set architecture composed of 13 instructions based on the reduced instruction set computer. We integrated a 128-bit instruction memory and a 128-bit data memory with an arithmetic logic unit, two registers, a program counter, an instruction register, and a controller unit on a single chip. The bit-serial operation was performed by an on-chip clock generator, while the system clocks are provided from room-temperature electronics. The CORE e2h was made up of 11 000 Nb/AlOx/Nb Josephson junctions and fabricated with the Advanced Industrial Science and Technology 10-kA/cm2, 9-Nb-layer process. We obtained the correct results for all the executed programs, including the integer division, the two kinds of summation algorithms, the Euclidean algorithm, and finding the greatest divisor. These test programs contained a single or nested double loop, and the maximum number of executed instructions was 205. We confirmed the stable operation with the DC bias margins of around 10% at 50-GHz for different test programs. The measured electric power consumption was 2.5 mW at 4.2 K, and the estimated computing power was 500 × 106 instructions/s.
Data-driven Reynolds-averaged turbulence modeling with generalizable non-linear correction and uncertainty quantification using Bayesian deep learning
Authors: Tang Hongwei , Wang Yan , Wang Tongguang , Tian Linlin , Qian Yaoru
Published: May 2023

The past few years have witnessed a renewed blossoming of data-driven turbulence models. Quantification of the concomitant modeling uncertainty, however, has mostly been omitted, and the generalization performance of the data-driven models is still facing great challenges when predicting complex flows with different flow physics not seen during training. A robust data-driven Reynolds-averaged turbulence model with uncertainty quantification and non-linear correction is proposed in this work with the Bayesian deep neural network. In this model, the Reynolds stress tensor is decomposed into linear and non-linear parts. The linear part is taken as the usual linear eddy viscosity model while the non-linear counterpart is learned by a Bayesian deep neural network. Independent tensor bases of invariants and tensors constituted by mean strain rate tensor and rotation rate tensor are embedded into the neural network to effectively consider key turbulence features in different flows. The proposed model is well validated through numerical simulations of four canonical flows that significantly deviate in geometrical configurations and/or Reynolds numbers from those in the training data. With the non-linear corrections of embedded invariants and tensors representing key features of turbulence, the proposed model not only improves the predictive capabilities of Reynolds-averaged turbulence models on the same mesh but also has better generalization performance when simulating complex turbulent flows with large scale separation. In addition, this model allows us to quantitatively demonstrate the confidence interval of the predicted flow quantities that are originated from the model itself.
Solution-processed bismuth sulfide incorporated with zinc for high-gain and low-noise photodetection
Authors: Fang Xiangming , Jia Zhenglin , Yang Yujie , Li Ruiming , Huang Huiming , Lin Qianqian
Published: May 2023

Bismuth sulfide possesses an extremely high absorption coefficient, a relatively small bandgap, and high charge carrier mobility, which are favorable for photovoltaics and photodetection. However, the device performance of binary Bi2S3 is still limited by the poor charge transport and complicated trap features caused by the stoichiometric imbalance, as both sulfur vacancy and bismuth vacancy could result in tremendous trap states. In this work, we incorporate a small amount of extrinsic elements in the solution-processed Bi2S3 thin films and systematically investigate the influence of extrinsic doping on the charge transport properties of Bi2S3 thin films via time-resolved microwave conductivity and field-effect transistors. We also fabricate photodetectors based on these Zn2+ incorporated Bi2S3 thin films and achieve state-of-the-art device performance, including relatively high on/off ratio, high responsivity, and extremely low dark current and noise, which is promising for next-generation solution-processed photodetection.
Primary spray breakup from a nasal spray atomizer using volume of fluid to discrete phase model
Authors: Shrestha Kendra , Van Strien James , Fletcher David F , Inthavong Kiao
Published: May 2023

Spray atomization process involves complex multi-phase phenomena. Abundant literature and validation of spray modeling for industrial applications like fuel injection in internal combustion and turbine jet engines are available. However, only a handful of studies, primarily limited to discrete phase modeling, of low-pressure applications, such as nasal spray exists. This study aims to provide insight into the external and near-nozzle spray characterization of a continuous spray and establishes good validation against the experiment. A three-dimensional (3D) x-ray scanner was used to extract the internal nasal spray nozzle geometry which was reconstructed to build a 3D computational model. A novel volume-of-fluid to discrete phase transition model was used to track the liquid phase and its transition to droplets, which was based on the shape and size of the liquid lumps. In this study, an early pre-stable and stable phase of spray plume development was investigated. Qualitative and quantitative analyses were carried out to validate the computational model. A liquid column exited a nozzle which distorted at its base with advancement in time and eventually formed a hollow-cone liquid sheet. It then disintegrated due to instability that produced fluctuations to form ligaments resulting in secondary breakup. This study provides in-depth understanding of liquid jet disintegration and droplet formation, which adds value to future nasal spray device designs and techniques to facilitate more effective targeted nasal drug delivery.
Neotype kuramite optoelectronic memristor for bio-synaptic plasticity simulations
Authors: Dong Xiaofei , Wei Wenbin , Sun Hao , Li Siyuan , Chen Jianbiao , Chen Jiangtao , Zhang Xuqiang , Zhao Yun , Li Yan
Published: May 2023

Memristive devices with both electrically and optically induced synaptic dynamic behaviors will be crucial to the accomplishment of brain-inspired neuromorphic computing systems, in which the resistive materials and device architectures are two of the most important cornerstones, but still under challenge. Herein, kuramite Cu3SnS4 is newly introduced into poly-methacrylate as the switching medium to construct memristive devices, and the expected high-performance bio-mimicry of diverse optoelectronic synaptic plasticity is demonstrated. In addition to the excellent basic performances, such as stable bipolar resistive switching with On/Off ratio of ∼486, Set/Reset voltage of ∼−0.88/+0.96 V, and good retention feature of up to 104 s, the new designs of memristors possess not only the multi-level controllable resistive-switching memory property but also the capability of mimicking optoelectronic synaptic plasticity, including electrically and visible/near-infrared light-induced excitatory postsynaptic currents, short-/long-term memory, spike-timing-dependent plasticity, long-term plasticity/depression, short-term plasticity, paired-pulse facilitation, and “learning-forgetting-learning” behavior as well. Predictably, as a new class of switching medium material, such proposed kuramite-based artificial optoelectronic synaptic device has great potential to be applied to construct neuromorphic architectures in simulating human brain functions.
Multistate spectral-tunable manipulation of mid-infrared emissivity using Sb2S3/GST/VO2
Authors: Chen Fangqi , Liu Yang , Liu Xiaojie , Zheng Yi
Published: May 2023

Conventional thermal emission that exhibits spectral selectivity relies on micro/nanostructures, such as gratings, photonic crystals, photonic cavities, nanoantennas, and metamaterials. By utilizing advanced micro/nanofabrication techniques to modify the structural parameters of the micro/nanostructures, it is possible to create wavelength-selective thermal emitters that span from THz to the visible range. Nonetheless, static micro/nanostructures do not offer flexible tunability in terms of thermal emissivity. In this Letter, we report a conceptual design of a multistate multilayered structure using a combination of three phase change materials: VO2, Ge2Sb2Te5, and Sb2S3. By controlling the temperature, the phase change materials will be in different phase states, rendering the multilayered structure six feasible thermal states with tunable spectra in the mid-infrared range. The impact of layer thickness is investigated. Polarization independence and angle insensitivity are exhibited until a large incident angle. This multilayered thermal structure is lithography-free and industrially scalable, showing great potential for programmable photonics and thermal sensors.
Comparative metabolomics analysis shows key metabolites as potential biomarkers for selection of beef fat colour
Authors: Tian Rugang , Kharrati-Koopaee Hamed , Asadollahpour Nanaie Hojjat , Wang Xiao , Zhao Meng , Li Hui , Li Yuan , Zhang Hao , Esmailizadeh Ali , Bottema Cynthia D. K.
Published: May 2023

Context Fat colour is one of the most important economic traits in the marketing of beef. There are many factors that affect fat colour, such as breed, age, diet and gender. Fat colour is observed in different ranges of colours, including white, yellow and brown. The main issue with improving fat colour is that consumer preferences of fat colour vary across the globe. Therefore, investigating the metabolic mechanisms of fat colour may provide new biomarkers for phenotyping, so as to develop effective selection strategies to achieve the locally desired fat colour. Aims This study aimed to perform a comparative metabolic analysis between white and yellow fat from crossbred cattle so as to identify potential biomarkers for the selection of fat colour and to better understand the metabolism of white and yellow fat depots. Methods Carcass samples of subcutaneous fat were collected from crossbred cattle (Simmental × Mongolian cattle) and scored for fat colour. Liquid chromatography–mass spectrophotometry analysis of extracted metabolites from the subcutaneous fat of six animals with white fat and six animals with yellow fat was performed. Key results The comparison between metabolites of white and yellow fat colour samples indicated that there were five categories of 235 significant metabolites, which included hydrocarbons, lipids and lipid-like molecules, organic acids and their derivatives, organic oxygen compounds and organoheterocyclic compounds. The principal-component analysis illustrated that yellow and white fat samples can be classified in groups; however, the metabolites of white fat samples showed greater variation than those in the yellow fat. In the white fat, there were 163 metabolites that had a higher relative abundance than in yellow fat and 72 that had a lower relative abundance than in yellow fat. 3-Hydroxyoctanoic acid, anethofuran, 9,10-DiHODE, furanoeremophilane, pregeijerene, N-glycolylneuraminic acid, and glycocholic acid were identified as the metabolites that differed the most in abundance between the white and yellow fat samples. Conclusions This study has provided insights into the metabolic differences between white and yellow fat depots and identified key metabolites associated with beef fat colour. Implications This study has provided potential biomarkers that may be useful for selection of beef fat colour in live animals.
Syndecan-4 is a maestro of gastric cancer cell invasion and communication that underscores poor survival
Authors: Poças Juliana , Marques Catarina , Gomes Catarina , Otake Andreia Hanada , Pinto Filipe , Ferreira Mariana , Silva Tiago , Faria-Ramos Isabel , Matos Rita , Ribeiro Ana Raquel , Senra Emanuel , Cavadas Bruno , Batista Sílvia , Maia Joana , Macedo Joana A. , Lima Luís , Afonso Luís Pedro , Ferreira José Alexandre , Santos Lúcio Lara , Polónia António , Osório Hugo , Belting Mattias , Reis Celso A. , Costa-Silva Bruno , Magalhães Ana
Published: May 2023

Gastric cancer is a dominating cause of cancer-associated mortality with limited therapeutic options. Here, we show that syndecan-4 (SDC4), a transmembrane proteoglycan, is highly expressed in intestinal subtype gastric tumors and that this signature associates with patient poor survival. Further, we mechanistically demonstrate that SDC4 is a master regulator of gastric cancer cell motility and invasion. We also find that SDC4 decorated with heparan sulfate is efficiently sorted in extracellular vesicles (EVs). Interestingly, SDC4 in EVs regulates gastric cancer cell-derived EV organ distribution, uptake, and functional effects in recipient cells. Specifically, we show that
SDC4
knockout disrupts the tropism of EVs for the common gastric cancer metastatic sites. Our findings set the basis for the molecular implications of SDC4 expression in gastric cancer cells and provide broader perspectives on the development of therapeutic strategies targeting the glycan-EV axis to limit tumor progression.
Phosphorylation sites are evolutionary checkpoints against liquid–solid transition in protein condensates
Authors: Ranganathan Srivastav , Dasmeh Pouria , Furniss Seth , Shakhnovich Eugene
Published: May 2023

Assemblies of multivalent RNA-binding protein fused in sarcoma (FUS) can exist in the functional liquid-like state as well as less dynamic and potentially toxic amyloid- and hydrogel-like states. How could then cells form liquid-like condensates while avoiding their transformation to amyloids? Here, we show how posttranslational phosphorylation can provide a “handle” that prevents liquid–solid transition of intracellular condensates containing FUS. Using residue-specific coarse-grained simulations, for 85 different mammalian FUS sequences, we show how the number of phosphorylation sites and their spatial arrangement affect intracluster dynamics preventing conversion to amyloids. All atom simulations further confirm that phosphorylation can effectively reduce the β-sheet propensity in amyloid-prone fragments of FUS. A detailed evolutionary analysis shows that mammalian FUS PLDs are enriched in amyloid-prone stretches compared to control neutrally evolved sequences, suggesting that mammalian FUS proteins evolved to self-assemble. However, in stark contrast to proteins that do not phase-separate for their function, mammalian sequences have phosphosites in close proximity to these amyloid-prone regions. These results suggest that evolution uses amyloid-prone sequences in prion-like domains to enhance phase separation of condensate proteins while enriching phosphorylation sites in close proximity to safeguard against liquid–solid transitions.
Chemiexcitation and melanin in photoreceptor disc turnover and prevention of macular degeneration
Authors: Lyu Yanan , Tschulakow Alexander V. , Wang Kun , Brash Douglas E. , Schraermeyer Ulrich
Published: May 2023

Age-related macular degeneration, Stargardt disease, and their

Abca4
-/-

mouse model are characterized by accelerated accumulation of the pigment lipofuscin, derived from photoreceptor disc turnover in the retinal pigment epithelium (RPE); lipofuscin accumulation and retinal degeneration both occur earlier in albino mice. Intravitreal injection of superoxide (O
2
•–
) generators reverses lipofuscin accumulation and rescues retinal pathology, but neither the target nor mechanism is known. Here we show that RPE contains thin multi-lamellar membranes (TLMs) resembling photoreceptor discs, which associate with melanolipofuscin granules in pigmented mice but in albinos are 10-fold more abundant and reside in vacuoles. Genetically over-expressing tyrosinase in albinos generates melanosomes and decreases TLM-related lipofuscin. Intravitreal injection of generators of O
2
•–
or nitric oxide (
•
NO) decreases TLM-related lipofuscin in melanolipofuscin granules of pigmented mice by ~50% in 2 d, but not in albinos. Prompted by evidence that O
2
•–
plus
•
NO creates a dioxetane on melanin that excites its electrons to a high-energy state (termed “chemiexcitation”), we show that exciting electrons directly using a synthetic dioxetane reverses TLM-related lipofuscin even in albinos; quenching the excited-electron energy blocks this reversal. Melanin chemiexcitation assists in safe photoreceptor disc turnover.
Fame through surprise: How fame-seeking mass shooters diversify their attacks
Authors: Succar Rayan , Barak Ventura Roni , Belykh Maxim , Wei Sihan , Porfiri Maurizio
Published: May 2023

Mass shootings are becoming more frequent in the United States, as we routinely learn from the media about attempts that have been prevented or tragedies that destroyed entire communities. To date, there has been limited understanding of the modus operandi of mass shooters, especially those who seek fame through their attacks. Here, we explore whether the attacks of these fame-seeking mass shooters were more surprising than those of others and clarify the link between fame and surprise in mass shootings. We assembled a dataset of 189 mass shootings from 1966 to 2021, integrating data from multiple sources. We categorized the incidents in terms of the targeted population and shooting location. We measured “surprisal” (often known as “Shannon information content”) with respect to these features, and we scored fame from Wikipedia traffic data—a commonly used metric of fame. Surprisal was significantly higher for fame-seeking mass shooters than non-fame-seeking ones. We also registered a significant positive correlation between fame and surprisal controlling for the number of casualties and injured victims. Not only do we uncover a link between fame-seeking behavior and surprise in the attacks but also we demonstrate an association between the fame of a mass shooting and its surprise.
ATG5 selectively engages virus-tethered BST2/tetherin in an LC3C-associated pathway
Authors: Judith Delphine , Versapuech Margaux , Bejjani Fabienne , Palaric Marjory , Verlhac Pauline , Kuster Aurelia , Lepont Leslie , Gallois-Montbrun Sarah , Janvier Katy , Berlioz-Torrent Clarisse
Published: May 2023

Bone marrow stromal antigen 2 (BST2)/tetherin is a restriction factor that reduces HIV-1 dissemination by tethering virus at the cell surface. BST2 also acts as a sensor of HIV-1 budding, establishing a cellular antiviral state. The HIV-1 Vpu protein antagonizes BST2 antiviral functions via multiple mechanisms, including the subversion of an LC3C-associated pathway, a key cell intrinsic antimicrobial mechanism. Here, we describe the first step of this viral-induced LC3C-associated process. This process is initiated at the plasma membrane through the recognition and internalization of virus-tethered BST2 by ATG5, an autophagy protein. ATG5 and BST2 assemble as a complex, independently of the viral protein Vpu and ahead of the recruitment of the ATG protein LC3C. The conjugation of ATG5 with ATG12 is dispensable for this interaction. ATG5 recognizes cysteine-linked homodimerized BST2 and specifically engages phosphorylated BST2 tethering viruses at the plasma membrane, in an LC3C-associated pathway. We also found that this LC3C-associated pathway is used by Vpu to attenuate the inflammatory responses mediated by virion retention. Overall, we highlight that by targeting BST2 tethering viruses, ATG5 acts as a signaling scaffold to trigger an LC3C-associated pathway induced by HIV-1 infection.
MWF of the corpus callosum is a robust measure of remyelination: Results from the ReBUILD trial
Authors: Caverzasi Eduardo , Papinutto Nico , Cordano Christian , Kirkish Gina , Gundel Tristan J. , Zhu Alyssa , Akula Amit Vijay , Boscardin W. John , Neeb Heiko , Henry Roland G. , Chan Jonah R. , Green Ari J.
Published: May 2023

Myelin repair is an unrealized therapeutic goal in the treatment of multiple sclerosis (MS). Uncertainty remains about the optimal techniques for assessing therapeutic efficacy and imaging biomarkers are required to measure and corroborate myelin restoration. We analyzed myelin water fraction imaging from ReBUILD, a double-blind, randomized placebo-controlled (delayed treatment) remyelination trial, that showed a significant reduction in VEP latency in patients with MS. We focused on brain regions rich in myelin. Fifty MS subjects in two arms underwent 3T MRI at baseline and months 3 and 5. Half of the cohort was randomly assigned to receive treatment from baseline through 3 mo, whereas the other half received treatment from 3 mo to 5 mo post-baseline. We computed myelin water fraction changes occurring in normal-appearing white matter of corpus callosum, optic radiations, and corticospinal tracts. An increase in myelin water fraction was documented in the normal-appearing white matter of the corpus callosum, in correspondence with the administration of the remyelinating treatment clemastine. This study provides direct, biologically validated imaging-based evidence of medically induced myelin repair. Moreover, our work strongly suggests that significant myelin repair occurs outside of lesions. We therefore propose myelin water fraction within the normal-appearing white matter of the corpus callosum as a biomarker for clinical trials looking at remyelination.