bluuebunny/crossref_metadata_2025 huggingface dataset:
Integrated control of edge localized modes and divertor flux using mixed toroidal harmonic resonant magnetic perturbations in EAST
Authors: Ma Qun , Sun You-Wen , Jia Man-Ni , Gu Shuai , Wu Xue-Min , Xie Peng-Cheng , Paz-Soldan Carlos , Liang Yun-Feng , Zhong Fang-Chuan , Wang Liang , Ding Fang , Zhang Bin , Shi Tong-Hui , Shen Biao , Wang Hui-Hui , Zhang Ling , Wang Yu-Min , Zang Qing , Li Ying-Ying , Liu Yue-Qiang , Wan Bao-Nian
Published: December 2023

Mixed harmonic resonant magnetic perturbations (RMPs) for integrated edge localized modes (ELMs) and divertor flux control are demonstrated in EAST target plasmas of low input torque and normalized beta βN∼ 1.7–1.9, which are close to the equivalent value in ITER high Q operation. The applied RMPs are designed to combine a static harmonic of the toroidal mode number n = 3 with a static or rotating harmonic of n = 2. ELM suppression is achieved without a drop of plasma energy confinement, and tungsten concentration is effectively reduced during the application of RMPs. With mixed harmonics, the toroidal varying steady state heat and particle fluxes on the divertor target can be modified with the rotating n = 2 harmonic, which agrees with the numerical modeling of three-dimensional magnetic topology, with plasma responses being taken into account. ELM suppression correlates with the times of larger n = 3 response with mixed n = 2 and n = 3 RMPs. The mixture of harmonics and the rotating n = 2 harmonic does not require additional coil current because the variation is only in the upper-lower coil current phase space. These results further affirm the effectiveness of integrated ELM and divertor flux control using RMPs with mixed harmonics and improve the understanding of the role of plasma responses in ELM suppression.
Trap-integrated fluorescence detection with silicon photomultipliers for sympathetic laser cooling in a cryogenic Penning trap
Authors: Wiesinger M. , Stuhlmann F. , Bohman M. , Micke P. , Will C. , Yildiz H. , Abbass F. , Arndt B. P. , Devlin J. A. , Erlewein S. , Fleck M. , Jäger J. I. , Latacz B. M. , Schweitzer D. , Umbrazunas G. , Wursten E. , Blaum K. , Matsuda Y. , Mooser A. , Quint W. , Soter A. , Walz J. , Smorra C. , Ulmer S.
Published: December 2023

We present a fluorescence-detection system for laser-cooled 9Be+ ions based on silicon photomultipliers (SiPMs) operated at 4 K and integrated into our cryogenic 1.9 T multi-Penning-trap system. Our approach enables fluorescence detection in a hermetically sealed cryogenic Penning-trap chamber with limited optical access, where state-of-the-art detection using a telescope and photomultipliers at room temperature would be extremely difficult. We characterize the properties of the SiPM in a cryocooler at 4 K, where we measure a dark count rate below 1 s−1 and a detection efficiency of 2.5(3)%. We further discuss the design of our cryogenic fluorescence-detection trap and analyze the performance of our detection system by fluorescence spectroscopy of 9Be+ ion clouds during several runs of our sympathetic laser-cooling experiment.
Crumpled graphene with graded interlayer spacing for high-rate Na+ storage
Authors: Liu Xiaoxu , DIN HASEEB UD , Zhang Man , Sheng Dawei , Chao Dongliang , Shen Zexiang
Published: December 2023

In electrode preparation, graphene-based electrodes usually form a uniaxially oriented stacking structure, which limits the Na+ diffusion in graphene electrodes for sodium-ion batteries (SIBs). In this work, a crumpled graphene (CG) anode with graded interlayer spacings was synthesized, and CG exhibits high-rate performance for SIBs. The CG has a folding microstructure like a paper clip that facilitates rapid adsorption/desorption of Na+ on its surface so that the diffusion kinetics of Na+ could be improved. The x-ray absorption fine structure and transmission electron microscope proved the mechanism of Na+ co-adsorption and explained the reason for its high-rate performance. When the three-dimensional CG is used as the anode of SIBs, it has a high-rate performance of 146 mAh g−1 with the current density increasing to 1 A g−1, and CG still maintained about 79 mAh g−1 after 1000 cycles at 0.5 A g−1 with good structural stability.
Anomalous negative resistance in SrTaO3 thin film: The nonuniform electronic state with possible superconductivity around 40 K
Authors: Li Yao , Xi Zhongnan , Wang Yuqi , Liu Zhiyu , Zheng Shuhan , Liu Meifeng , Ma Zhen , Zhang Yongjun , Wang Xiuzhang , Li Hong , Deng Yu , Yang Yurong , Liu Jun-Ming , Wu Di
Published: December 2023

Transition metal oxides provide opportunities to induce and modulate the superconducting state, due to the delicate interplay between charge, spin, orbital, and lattice order. In this work, 5d transition metal oxide SrTaO3 films were deposited by pulsed laser deposition, and an anomalous negative resistance was observed. The negative resistance can be ascribed to the nonuniform conductivity, associated with nonuniform electronic states in the SrTaO3 thin films, as confirmed by conductive atomic force microscopy and x-ray photoelectron spectroscopy. Moreover, a sharp drop in the resistance together with a decrease in magnetization was observed at around 40 K. This might imply a possible superconducting state. The negative resistance can be well explained based on an equivalent circuit comprising normal and superconductive states, also supporting the possible superconducting state in SrTaO3 thin films. This work promotes the exploring and revealing of the mechanism in tantalates superconductivity.
High-resolution spectroscopic imaging of atoms and nanoparticles in thin film vaporization
Authors: Engels D. J. , Meijer R. A. , Schubert H. K. , van der Zande W. J. , Ubachs W. , Versolato O. O.
Published: December 2023

We introduce a spectroscopic absorption imaging method in the UV regime (225–400 nm) to study tin vapor created by irradiating a thin film with a low intensity 108 W cm−2 nanosecond laser pulse, a case inspired by current developments around “advanced target shaping” in industrial laser-produced plasma sources for extreme ultraviolet light. The 4-ns-time-resolved, 10-μm-spatial-resolution images contain a 10-cm−1-resolution spectrum of the vapor in each pixel 100 ns after the vaporization. The images allow us to reveal a homogeneous temperature profile throughout the vapor of around 3000 K. We obtain a density map of the atoms (with a peak density of 5 × 1018 cm−3) and nanoparticles (1012 cm−3 for the best fitting 20 nm radius case), which both are shown to be present in the vapor. For each free atom, approximately three appear to be clustered in nanoparticles, and this composition is invariant over space and density. The density and temperature maps of the free atoms are combined to estimate the electron density (peaking at 1013 cm−3) in the vapor.
Substantial toughening by thick nanoscale amorphous intergranular films in nanocrystalline materials
Authors: Huang Yijing , Qin Feng , Dai Kaiqing , Chen Shaohua , Li Jiejie , Li Jianjun
Published: December 2023

Amorphous intergranular films (AIFs) have been proven in experiments to improve the damage tolerance of nanocrystalline materials. However, a quantitative study is still lacking. Molecular dynamics simulations were performed here to investigate the effect of CuNb AIFs on the fracture toughness of nanocrystalline Nb. In order to clarify the role of AIFs, a bicrystal Nb model with one straight symmetrical tilt grain boundary and a mode-I crack in one of the grains was constructed, in which the AIF effect was introduced by replacing the normal grain boundary with a CuNb AIF. Then, AIF thickness-dependent tensile deformation of the bicrystal Nb samples was simulated. The work-of-fracture, which is defined as the released strain energy due to the newly generated unit area in the crack during stretching, was employed to quantify the fracture toughness of the bicrystal systems. The results show that the fracture toughness of the AIF sample can be tripled due to the blunted crack tip and the relieved stress concentration at the crack tip as compared to the AIF-free one that exhibits a brittle crack propagation behavior. Also, the thicker the AIFs, the more pronounced this reinforcing effect. More importantly, it is found that there exists a critical AIF width of 1.7 nm, below which the crack will eventually break through the AIF, and above which the crack failed to do this. It is revealed that the enhanced fracture toughness originated from the transformation of brittle crack propagation to abundant dislocation emission from AIFs.
Large enhancement of spin–orbit torques under a MHz modulation due to phonon–magnon coupling
Authors: Zhang Hanying , Zhao Qianwen , Jiang Baiqing , Wang Yuan , Xie Tunan , Lou Kaihua , Xia ChaoChao , Bi C.
Published: December 2023

The discovery of spin–orbit torques (SOTs) generated through the spin Hall or Rashba effects provides an alternative write approach for magnetic random-access memory (MRAM), igniting the development of spin orbitronics in recent years. Quantitative characterization of SOTs highly relies on the SOT-driven ferromagnetic resonance (ST-FMR), where a modulated microwave current is used to generate ac SOTs and the modulation frequency is usually less than 100 kHz (the limit of conventional lock-in amplifiers). Here, we have investigated the SOT of typical SOT material/ferromagnet bilayers in an extended modulation-frequency range, up to MHz, by developing the ST-FMR measurement. Remarkably, we found that the measured SOTs are enhanced about three times in the MHz range, which cannot be explained according to the present SOT theory. We attribute the enhancement of SOT to additional magnon excitations due to phonon–magnon coupling, which is also reflected in the slight changes of resonant field and linewidth in the acquired ST-FMR spectra, corresponding to the modifications of effective magnetization and damping constant, respectively. Our results indicate that the write current of SOT-MRAM may be reduced with the assistance of phonon–magnon coupling.
Ultrathin film optical coatings for all-optical mathematical operations with ultrahigh numerical aperture
Authors: Wei Ran , Zhang Jihua , Jalil Sohail A , Elkkabash Mohamed , Guo Chunlei
Published: December 2023

Optical analog computation is garnering increasing attention due to its innate parallel processing capabilities, swift computational speeds, and minimal energy requirements. However, traditional optical components employed for such computations are usually bulky. Recently, there has been a substantial shift toward utilizing nanophotonic structures to downsize these bulky optical elements. Nevertheless, these nanophotonic structures are typically realized in planar subwavelength nanostructures, demanding intricate fabrication processes and presenting limitations in their numerical apertures. In this study, we present a three-layer thin-film optical coating different from the conventional Fabry–Pérot nanocavity. Our design functions as a real-time Laplacian operator for spatial differentiation, and it remarkably boasts an ultrahigh numerical aperture of up to 0.7, enabling the detected edges to be sharper and have closely matched intensities. We also experimentally demonstrate its capacity for effective edge detection. This ultracompact and facile-to-fabricate thin-film spatial differentiator holds promising prospects for applications in ultrafast optical processing and biomedical imaging.
Experimental investigation of the dynamic evolution of cavity during the free water-exit of a high-pressure venting vehicle
Authors: Zhang Qing-Sen , Ming Fu-Ren , Liu Xiang-Ju , Liu Wen-Tao , Zhang A-Man
Published: December 2023

The underwater vehicle is subjected to complex hydrodynamic loads during water-exit process, which seriously affect the structural strength and water-exit stability of the vehicle. This paper investigates the effect of high-pressure venting conditions on the dynamic evolution characteristics of the cavity during the completely free water-exit of a vehicle based on self-designed experiments. Some novel phenomena are found in the experiment, and the hypothesis of constant acceleration is established to explain the formation mechanism. The results reveal that the reentrant jet is the main factor influencing the pattern of cavity development and causes great differences between the partial and supercavity states. The balance between the initial cavity volume increase and the gas leakage rate results in the fact that increasing the launch Froude number in the partial cavity state does not cause significant changes in the cavity size. There is a stable interval between 0.0038 and 0.03 for the effect of gas entrainment coefficient on the development of the cavity. The influence of the launch Froude number on the cavity morphology varies within different gas entrainment coefficient ranges. Besides, six patterns of cavity closure are found for free water-exit conditions. The coupling closure pattern of reentrant jet and interaction vortex tube is the most stable during the water-exit process. The stable development intervals of cavity closure pattern and cavity morphology are roughly the same. The present study aims to provide a reference for the active venting flow control of the vehicle during water-exit.
DIII-D's role as a national user facility in enabling the commercialization of fusion energy
Authors: Buttery R. J. , Abrams T. , Casali L. , Greenfield C. M. , Groebner R. , Holcomb C. T. , Hong S. , Jaervinen A. , Leonard A. , McLean A. , Osborne T. , Pace D. C. , Park J. M. , Petty C. C. , Shafer M. , Sips A. C. C. ,   DIII-D Team
Published: December 2023

The path to fusion in the United States requires partnership between public and private sector. While the private sector provides the vigor to take some of the major steps necessary, there is a depth of expertise and capability in the public sector that is vital to resolving feasible approaches. As an open national user facility, DIII-D provides a crucial testbed to develop the required new technologies and approaches in relevant conditions. It has unparalleled potential to meet this challenge, thanks to its extreme flexibility and world leading diagnostics. This provides a basis to rapidly develop solutions that project to future reactors with confidence. The program has thus been redeveloped to enable public and private sector engagement and testing of new concepts. A new technology program has been launched to resolve plasma interacting technologies. With modest heating upgrades, the facility can confront the crucial “Integrated Tokamak Exhaust and Performance” gap, to resolve core, exhaust and technology solutions together. The device is also being redeveloped as a training facility, with dedicated student run time, a mentorship program, and open access to all opportunity roles, part of wider efforts to diversify and open pathways through inclusion, access, and equity. This exciting agenda is enabling scientists and technology researchers to pioneer the solutions needed for a Fusion Pilot Plant (FPP) and ITER this decade. As a national user facility, DIII D has singular potential to provide the tools, teams, and insight necessary, to do its part in moving the United States rapidly toward the commercialization of fusion energy.
Pelton turbine jet flow investigations using laser Doppler velocimetry
Authors: Khan Firoz , Kumar Arun
Published: December 2023

Hydropower is a sustainable and clean renewable energy source. The Pelton turbine is an impulse type of hydraulic turbine and operates under high head and low discharge. It comprises an injector, which converts high-pressure water into kinetic energy as a high-speed free surface water jet that impinges on the runner generating power coupled with an electric generator. The water is highly accelerated in the nozzle, which produces turbulent kinetic energy in the jet flow. Before impinging on the runner, the surrounding air is entrained into the jet, which causes the jet dispersion. The effective conversion of water energy into mechanical energy and the quality of a jet depend significantly on the uniformity of the jet. However, the jet encounters instabilities and non-uniformity caused by secondary flow and turbulence. Jet surface and velocity distribution do not remain symmetric. Investigation of the jet's velocity profile and turbulence intensities is important to understand the flow behavior and improvements in the design of injector. In this study, the experimental investigation of the jet has been performed using the laser Doppler velocimetry (LDV) system. The turbulent intensity and instantaneous velocity of the jet are analyzed at different locations along the jet flow. The velocity wake zone occurs around the center of the jet, which diminishes in the axial direction of the jet, with non-dimensional jet velocities values 0.91, 0.92, and 0.94 at x/Do of 0.5, 1, and 2 for ∼98% nozzle opening. The secondary flow velocity magnitude is larger for 90°–60° injector jet flow than for 90°–50°. The jet velocity profile obtained from the LDV has been compared with computational fluid dynamics analysis.
Symmetry-breaking response of a flexible splitter plate attached to a circular cylinder in uniform flow
Authors: Sahu Tulsi Ram , Furquan Mohd , Mittal Sanjay
Published: December 2023

Static and dynamic fluid–structure interaction of a flexible plate behind a stationary cylinder in uniform flow is explored for a body-to-fluid mass ratio of 10. Steady flow-structure computations for Re = 150, based on the diameter of cylinder and free-stream speed, reveal four regimes with respect to increasing flexibility of the plate. The plate does not undergo any lateral deflection in regime 1 beyond which it undergoes a symmetry-breaking bifurcation causing it to spontaneously deflect laterally. The curvature is of the same sign along the entire length of plate in regime 2 while it changes sign along the plate in regime 3. The lateral deflection, however, is still maximum at the plate tip. The location of maximum deflection moves away from the plate tip in regime 4. The evolution of flow structures including the strength of various standing vortices, with flexibility, is studied. The role of reattachment of flow on the surface of the plate and the modification of the pressure distribution is explored. The critical Re, beyond which the splitter plate spontaneously achieves a deflected shape, decreases with increase in flexibility. It is estimated to be Re = 122.33 for the limiting case of an infinitely flexible plate. Computations for dynamic fluid–structure interaction reveal several regimes of lock-in with different natural vibration modes of the plate and related hysteresis. No lateral bias in the time-averaged deflection is found during lock-in; it occurs in the desynchronization regime that precedes the lock-in regime with second mode. For the mass ratio considered, the bias in the static and dynamic simulations start at the same flexibility.
Decomposed defect formation energy for analysis of doping process: The case of n-type and p-type doping of β-FeSi2
Authors: Chai Jun , Ming Chen , Sun Yi-Yang
Published: December 2023

Defect formation energy governs the thermodynamics of a specific dopant within the host material. Here, we introduce an approach to decomposing the defect formation energy into intuitive components, each representing a distinct physical step in the process of defect formation. Through this approach, we illustrate that adhering solely to conventional criteria, such as ionic radius, may overlook potential dopants. Taking β-FeSi2, a promising high-temperature thermoelectric material, as an example, we demonstrate that non-intuitive chemical interactions can play a more significant role in lowering the defect formation energy. As a result, Ir on Fe site is found to exhibit unexpected low defect formation energy among the 26 candidate dopants and has been employed in experiment to enhance the thermoelectric figure of merit of n-type β-FeSi2. The understanding gained from this work could be of general interest for addressing the doping limit issue for other potential thermoelectric materials.
Anisotropic hole transport along [0001] and [112¯0] direction in p-doped (101¯0) GaN
Authors: Lin Yingying , Wang Jia , Pristovsek Markus , Honda Yoshio , Amano Hiroshi
Published: December 2023

The anisotropic hole transport along [0001] and [112¯0] in the p-doped (101¯0) GaN layer was compared for layers grown on bulk (101¯0) GaN substrates and on (101¯0) sapphire. The sheet resistance along [0001] was 1.1 times larger on GaN substrates and even 1.2 times larger on sapphire than that along [112¯0]. The anisotropic hole transport on bulk GaN substrates is due to the anisotropy of the hole’s effective mass and the different contribution of carriers in different bands, whereas the larger anisotropy for GaN on sapphire is also due to additional scattering at stacking faults. The annealing process of metal Mg applied to the m-plane p-type GaN successfully results in a robust p-type ohmic contact, functioning as a p++ layer.
Self-tuning Hamiltonian Monte Carlo for accelerated sampling
Authors: Christiansen Henrik , Errica Federico , Alesiani Francesco
Published: December 2023

The performance of Hamiltonian Monte Carlo simulations crucially depends on both the integration timestep and the number of integration steps. We present an adaptive general-purpose framework to automatically tune such parameters based on a local loss function that promotes the fast exploration of phase space. We show that a good correspondence between loss and autocorrelation time can be established, allowing for gradient-based optimization using a fully differentiable set-up. The loss is constructed in such a way that it also allows for gradient-driven learning of a distribution over the number of integration steps. Our approach is demonstrated for the one-dimensional harmonic oscillator and alanine dipeptide, a small protein commonly used as a test case for simulation methods. Through the application to the harmonic oscillator, we highlight the importance of not using a fixed timestep to avoid a rugged loss surface with many local minima, otherwise trapping the optimization. In the case of alanine dipeptide, by tuning the only free parameter of our loss definition, we find a good correspondence between it and the autocorrelation times, resulting in a >100 fold speedup in the optimization of simulation parameters compared to a grid search. For this system, we also extend the integrator to allow for atom-dependent timesteps, providing a further reduction of 25% in autocorrelation times.
Prediction of fluorescence quantum yields using the extended thawed Gaussian approximation
Authors: Wenzel Michael , Mitric Roland
Published: December 2023

Spontaneous emission and internal conversion rates are calculated within harmonic approximations and compared to the results obtained within the semi-classical extended thawed Gaussian approximation (ETGA). This is the first application of the ETGA in the calculation of internal conversion and emission rates for real molecular systems, namely, formaldehyde, fluorobenzene, azulene, and a dicyano-squaraine dye. The viability of the models as black-box tools for prediction of spontaneous emission and internal conversion rates is assessed. All calculations were done using a consistent protocol in order to investigate how different methods perform without previous experimental knowledge using density functional theory (DFT) and time-dependent DFT (TD-DFT) with B3LYP, PBE0, ωB97XD, and CAM-B3LYP functionals. Contrasting the results with experimental data shows that there are further improvements required before theoretical predictions of emission and internal conversion rates can be used as reliable indicators for the photo-luminescence properties of molecules. We find that the ETGA performs rather similar to the vertical harmonical model. Including anharmonicities in the calculation of internal conversion rates has a moderate effect on the quantitative results in the studied systems. The emission rates are fairly stable with respect to computational parameters, but the internal conversion rate reveals itself to be highly dependent on the choice of the spectral line shape function, particularly the width of the Lorentzian function, associated with homogeneous broadening.
Co-effect of hydrophobicity and cavities on flow characteristics at microscale
Authors: Fang Weidong , Yu Zhan , Wu Hanxiao , Tao Zhi , Li Haiwang , Xu Tiantong , Huang Yi , Li Murun , Liu Xiao
Published: December 2023

Flowing characteristics of drag reduction are experimentally and numerically investigated with a combination of hydrophobic coating and various cavities in polydimethylsiloxane microchannels. Two typical types of cavities with different geometrical parameters, rectangular and triangular, are studied with a wide range of Reynolds numbers from 0 to 300. A promising hydrophobic processing method is proposed based on a comprehensive performance on surface morphology, water repellency, and structural distortion. In this method, hydrofluoric acid (40 wt. %) is adopted and the corrosion time is set to 5 min. The velocity field and streamlines are acquired by the micro-particle image velocimetry system and numerical models to explain the flow patterns in particular. The slip length is measured as 13.38 μm in the hydrophobic straight channel. For rectangular cavities, the drag reduction rate reaches nearly 14.1% under no-slip condition and 33.2% under slip condition. A critical turning point of the co-effect is found by numerical results when the slip length is about 15 μm, which is also determined by the cavities. The convergent and divergent angles of triangular cavities play a critical role in the pressure drop due to the competition of the vortex and flow impingement. A nonlinear model is developed based on the numerical results to predict Poiseuille number with the relevant important variables for a two-dimensional microchannel. Our results reveal the fundamental physics of flowing characteristics with the co-design of hydrophobicity and microstructures, predicting a composite design method for widespread applications in microfluids.
Photoresponsive peptide materials: Spatiotemporal control of self-assembly and biological functions
Authors: Matsuura Kazunori , Inaba Hiroshi
Published: December 2023

Peptides work as both functional molecules to modulate various biological phenomena and self-assembling artificial materials. The introduction of photoresponsive units to peptides allows the spatiotemporal remote control of their structure and function upon light irradiation. This article overviews the photoresponsive peptide design, interaction with biomolecules, and applications in self-assembling materials over the last 30 years. Peptides modified with photochromic (photoisomerizable) molecules, such as azobenzene and spiropyran, reversibly photo-controlled the binding to biomolecules and nanostructure formation through self-assembly. Photocleavable molecular units irreversibly control the functions of peptides through cleavage of the main chain and deprotection by light. Photocrosslinking between peptides or between peptides and other biomolecules enhances the structural stability of peptide assemblies and complexes. These photoresponsive peptides spatiotemporally controlled the formation and dissociation of peptide assemblies, gene expressions, protein–drug interactions, protein–protein interactions, liposome deformation and motility, cytoskeleton structure and stability, and cell functions by appropriate light irradiation. These molecular systems can be applied to photo-control biological functions, molecular robots, artificial cells, and next-generation smart drug delivery materials.
Electron lifetime and diffusion coefficient in dopant-free p-type distributed polarization doped AlGaN
Authors: Kumabe Takeru , Kawasaki Seiya , Watanabe Hirotaka , Honda Yoshio , Amano Hiroshi
Published: December 2023

Minority carrier properties in dopant-free p-type distributed polarization doped (DPD) AlGaN layers were investigated on the basis of the forward-biased current density–voltage (J–V) characteristics of p–n+ diodes. The fabricated p-DPD AlGaN/n+–AlGaN:Si diodes exhibited ideal electrical characteristics despite the absence of acceptor atoms in the p-type layer. The extracted Shockley–Read–Hall lifetime exceeded 300 ps, which was longer than that reported for p-GaN:Mg on GaN substrates with a similar acceptor concentration (20–50 ps). Moreover, the electron diffusion coefficient was about 20 cm2 s−1 at any temperature, which was convincing in terms of the electron mobility in DPD layers. The results suggest that p-DPD AlGaN has more desirable minority carrier properties than conventional p-GaN:Mg, particularly for bipolar device applications.
Unstable spray pattern and cooling performance of cryogen spray coupled with cold air jet: An experimental study
Authors: Tian Jiameng , Chen Yiqi , He Changqiu , Wang Zhentao , Qenawy Mohamed , Wang Junfeng , Chen Bin , Xiong Junhui
Published: December 2023

This study focuses on the interactions between cryogen spray cooling (CSC) and cold air jet (CAJ), as well as the heat transfer performance upon CAJ-CSC impingement assisted for laser dermatology. CAJ is found to collapse downstream spray on the windward side, enhancing fluctuations of R1234yf spray width. Standard deviation (SD) distribution identifies that fluctuations at nozzle exit are attributed to ambient-to-spray interactions, which is also confirmed by the proper orthogonal decomposition (POD) analysis. The third POD mode highlights jet-to-spray interactions on the windward side of spray, yielding an enhanced instability by 1.72 times when CAJ flow rate (Q) increases from 4 to 8 m3/h. The closer location to the spray center on the same radial side corresponds to a faster thermal response and a lower temperature drop (ΔT). ΔT on the windward side decreases due to the considerable CAJ-induced droplet swarm drift. The heat transfer degrades on the leeward side due to the thermal gas boundary layer originating from the inclined CAJ sweep. Nevertheless, the CAJ with a small flow rate (4 m3/h) enhances the heat transfer at spray center, yielding a minimum surface temperature of −32.3 °C. Comparative investigation indicates R134a has superior cooling performance but more significant instabilities inside spray plume. R1234yf serves a relatively stable sub-cooling region within a radial distance of ±1 mm from spray center characterized by low spray fluctuations and high temperature drops at Q = 4 m3/h. Substitution of R1234yf for R134a still needs heat transfer enhancement for clinical considerations.
Block2: A comprehensive open source framework to develop and apply state-of-the-art DMRG algorithms in electronic structure and beyond
Authors: Zhai Huanchen , Larsson Henrik R. , Lee Seunghoon , Cui Zhi-Hao , Zhu Tianyu , Sun Chong , Peng Linqing , Peng Ruojing , Liao Ke , Tölle Johannes , Yang Junjie , Li Shuoxue , Chan Garnet Kin-Lic
Published: December 2023

block2 is an open source framework to implement and perform density matrix renormalization group and matrix product state algorithms. Out-of-the-box it supports the eigenstate, time-dependent, response, and finite-temperature algorithms. In addition, it carries special optimizations for ab initio electronic structure Hamiltonians and implements many quantum chemistry extensions to the density matrix renormalization group, such as dynamical correlation theories. The code is designed with an emphasis on flexibility, extensibility, and efficiency and to support integration with external numerical packages. Here, we explain the design principles and currently supported features and present numerical examples in a range of applications.
A noninvasive measurement technique for the initial bending stiffness of an arterial wall
Authors: Zhang Yixing , Ai Jun , Shi Mingxing , Ma Yinji
Published: December 2023

Vascular disease poses a significant threat to human health. Effective detection methods for quantifying noninvasive arterial wall stiffness enable the early identification of populations exhibiting arteriosclerosis tendencies, providing substantial value for vascular disease prevention and treatment. However, current methods for evaluating arterial stiffness rely on simple tangent stiffness, which is affected by blood pressure fluctuations. This study utilizes a collapse model to investigate arterial deformation and pulse wave propagation under transmural pressure with different arterial wall thicknesses and material properties. Based on the pressure–area relationship of collapsed blood vessels, the relationship between pulse wave velocity and initial bending stiffness at the collapsed state is derived. A method is, then, proposed to evaluate the arterial wall bending stiffness incorporating cuff and photoplethysmography technology for assessing arteriosclerosis. This method is verified through a collapse experiment with a rubber tube and employed in measuring the initial bending stiffness of a human radial artery in vivo. The implementation of this measurement method facilitates vascular stiffness measurements beyond the restriction of tangent modulus and blood pressure changes, offering a quantitative evaluation of arterial wall stiffness. The technique can, therefore, amplify the precision and dependability of preliminary arteriosclerosis lesion diagnostic procedures.
Bismuth-doping induced red-shifted spectral response of homo-epitaxial MAPbBr3 photodiodes
Authors: Xu Yubing , Wang Xin , Pan Yuzhu , Chai ShunJie , Wu Jie , Wang Mengrou , Perveen Abida , Onwudiwe Damian Chinedu , Talaighil Razika Zair , Bae Byung Seong , Zhu Ying , Chen Jing , Lei Wei
Published: December 2023

Perovskite single crystals (PSCs) photodiodes with p–n junctions have been widely studied due to their effective blocking of injected current with barriers and quickly separating the electrons and hole pairs with a built-in electric field. Here, we report a solution-processed epitaxial (SPE) growth method to fabricate p–n photodiodes based on MAPbBr3 PSCs. In the structure of the MAPbBr3 PSCs, bismuth donor doping will change the conduction type from p-type to n-type and redshift the absorption edge along with the increase in Bi concentration. Therefore, this work successfully fabricates the p–n photodiodes with homo-epitaxial Bi-doped (n-type) MAPbBr3 layers grown on the surface of undoped (p-type) MAPbBr3 PSCs substrates through the SPE growth method. The p–n photodiodes achieve a tunable spectral response by simply adjusting the Bi doping concentrations of homo-epitaxial MAPbBr3 layers. The spectral response peaks redshift from 559 to 601 nm, with an increasing Bi doping level of 0% to 15%.
Quantum states of physical domains in molecular systems: A three-state model approach
Authors: Bochicchio Roberto C. , Maulén Boris
Published: December 2023

The physical regions (domains or basins) within the molecular structure are open systems that exchange charge between them and, consequently, house a fractional number of electrons (net charge). The natural framework describing the quantum states for these domains is the density matrix (DM) in its grand-canonical version, which corresponds to a convex expansion into a set of basis states of an integer number of electrons. In this report, it is shown that the solution for these quantities is supported by the DM expansion into three states of different numbers of particles: the neutral and two (edge) ionic states. The states and the average number of particles in the domains (fractional occupation population) are determined by the coefficients of the expansion in terms of the fundamental transference magnitudes, revealing the donor/acceptor character of the domains by which the quantum accessible states are discussed.
Regulating phase behavior of nanoparticle assemblies through engineering of DNA-mediated isotropic interactions
Authors: Mao Runfang , Minevich Brian , McKeen Daniel , Chen Qizan , Lu Fang , Gang Oleg , Mittal Jeetain
Published: December 2023

Self-assembly of isotropically interacting particles into desired crystal structures could allow for creating designed functional materials via simple synthetic means. However, the ability to use isotropic particles to assemble different crystal types remains challenging, especially for generating low-coordinated crystal structures. Here, we demonstrate that isotropic pairwise interparticle interactions can be rationally tuned through the design of DNA shells in a range that allows transition from common, high-coordinated FCC-CuAu and BCC-CsCl lattices, to more exotic symmetries for spherical particles such as the SC-NaCl lattice and to low-coordinated crystal structures (i.e., cubic diamond, open honeycomb). The combination of computational and experimental approaches reveals such a design strategy using DNA-functionalized nanoparticles and successfully demonstrates the realization of BCC-CsCl, SC-NaCl, and a weakly ordered cubic diamond phase. The study reveals the phase behavior of isotropic nanoparticles for DNA–shell tunable interaction, which, due to the ease of synthesis is promising for the practical realization of non-close-packed lattices.
A species’ response to spatial climatic variation does not predict its response to climate change
Authors: Perret Daniel L. , Evans Margaret E. K. , Sax Dov F.
Published: December 2023

The dominant paradigm for assessing ecological responses to climate change assumes that future states of individuals and populations can be predicted by current, species-wide performance variation across spatial climatic gradients. However, if the fates of ecological systems are better predicted by past responses to in situ climatic variation through time, this current analytical paradigm may be severely misleading. Empirically testing whether spatial or temporal climate responses better predict how species respond to climate change has been elusive, largely due to restrictive data requirements. Here, we leverage a newly collected network of ponderosa pine tree-ring time series to test whether statistically inferred responses to spatial versus temporal climatic variation better predict how trees have responded to recent climate change. When compared to observed tree growth responses to climate change since 1980, predictions derived from spatial climatic variation were wrong in both magnitude and direction. This was not the case for predictions derived from climatic variation through time, which were able to replicate observed responses well. Future climate scenarios through the end of the 21st century exacerbated these disparities. These results suggest that the currently dominant paradigm of forecasting the ecological impacts of climate change based on spatial climatic variation may be severely misleading over decadal to centennial timescales.
The exceptional form and function of the giant bacterium
Ca.
Epulopiscium viviparus revolves around its sodium motive force
Authors: Sannino David R. , Arroyo Francine A. , Pepe-Ranney Charles , Chen Wenbo , Volland Jean-Marie , Elisabeth Nathalie H. , Angert Esther R.
Published: December 2023

Epulopiscium
spp. are the largest known heterotrophic bacteria; a large cigar-shaped individual is a million times the volume of
Escherichia coli
. To better understand the metabolic potential and relationship of
Epulopiscium
sp. type B with its host
Naso tonganus
, we generated a high-quality draft genome from a population of cells taken from a single fish. We propose the name
Candidatus
Epulopiscium viviparus to describe populations of this best-characterized
Epulopiscium
species. Metabolic reconstruction reveals more than 5% of the genome codes for carbohydrate active enzymes, which likely degrade recalcitrant host-diet algal polysaccharides into substrates that may be fermented to acetate, the most abundant short-chain fatty acid in the intestinal tract. Moreover, transcriptome analyses and the concentration of sodium ions in the host intestinal tract suggest that the use of a sodium motive force (SMF) to drive ATP synthesis and flagellar rotation is integral to symbiont metabolism and cellular biology. In natural populations, genes encoding both F-type and V-type ATPases and SMF generation via oxaloacetate decarboxylation are among the most highly expressed, suggesting that ATPases synthesize ATP and balance ion concentrations across the cell membrane. High expression of these and other integral membrane proteins may allow for the growth of its extensive intracellular membrane system. Further, complementary metabolism between microbe and host is implied with the potential provision of nitrogen and B vitamins to reinforce this nutritional symbiosis. The few features shared by all bacterial behemoths include extreme polyploidy, polyphosphate synthesis, and thus far, they have all resisted cultivation in the lab.
Hyperactive Rac stimulates cannibalism of living target cells and enhances CAR-M-mediated cancer cell killing
Authors: Mishra Abhinava K. , Rodriguez Melanie , Torres Alba Yurani , Smith Morgan , Rodriguez Anthony , Bond Annalise , Morrissey Meghan A. , Montell Denise J.
Published: December 2023

The 21kD GTPase Rac is an evolutionarily ancient regulator of cell shape and behavior. Rac2 is predominantly expressed in hematopoietic cells where it is essential for survival and motility. The hyperactivating mutation Rac2E62Kalso causes human immunodeficiency, although the mechanism remains unexplained. Here, we report that in Drosophila, hyperactivating Rac stimulates ovarian cells to cannibalize neighboring cells, destroying the tissue. We then show that hyperactive Rac2E62Kstimulates human HL60-derived macrophage-like cells to engulf and kill living T cell leukemia cells. Primary mouse Rac2+/E62Kbone-marrow-derived macrophages also cannibalize primary Rac2+/E62KT cells due to a combination of macrophage hyperactivity and T cell hypersensitivity to engulfment. Additionally, Rac2+/E62Kmacrophages non-autonomously stimulate wild-type macrophages to engulf T cells. Rac2E62Kalso enhances engulfment of target cancer cells by chimeric antigen receptor-expressing macrophages (CAR-M) in a CAR-dependent manner. We propose that Rac-mediated cell cannibalism may contribute to Rac2+/E62Khuman immunodeficiency and enhance CAR-M cancer immunotherapy.
Recovering intestinal redox homeostasis to resolve systemic inflammation for preventing remote myocardial injury by oral fullerenes
Authors: Jia Wang , Sun Jiacheng , Cao Xinran , Xu Yuan , Wu Zhanfeng , Zhou Chen , Huo Jiawei , Su Shenge , Zhen Mingming , Wang Chunru , Bai Chunli
Published: December 2023

The unbalanced immune state is the dominant feature of myocardial injury. However, the complicated pathology of cardiovascular diseases and the unique structure of cardiac tissue lead to challenges for effective immunoregulation therapy. Here, we exploited oral fullerene nanoscavenger (OFNS) to maintain intestinal redox homeostasis to resolve systemic inflammation for effectively preventing distal myocardial injury through bidirectional communication along the heart–gut immune axis. Observably, OFNS regulated redox microenvironment to repair cellular injury and reduce inflammation in vitro. Subsequently, OFNS prevented myocardial injury by regulating intestinal redox homeostasis and recovering epithelium barrier integrity in vivo. Based on the profiles of transcriptomics and proteomics, we demonstrated that OFNS balanced intestinal and systemic immune homeostasis for remote cardioprotection. Of note, we applied this principle to intervene myocardial infarction in mice and mini-pigs. These findings highlight that locally addressing intestinal redox to inhibit systemic inflammation could be a potent strategy for resolving remote tissue injury.
hGRAD: A versatile “one-fits-all” system to acutely deplete RNA binding proteins from condensates
Authors: Arnold Benjamin , Riegger Ricarda J. , Okuda Ellen Kazumi , Slišković Irena , Keller Mario , Bakisoglu Cem , McNicoll François , Zarnack Kathi , Müller-McNicoll Michaela
Published: December 2023

Nuclear RNA binding proteins (RBPs) are difficult to study because they often belong to large protein families and form extensive networks of auto- and crossregulation. They are highly abundant and many localize to condensates with a slow turnover, requiring long depletion times or knockouts that cannot distinguish between direct and indirect or compensatory effects. Here, we developed a system that is optimized for the rapid degradation of nuclear RBPs, called hGRAD. It comes as a “one-fits-all” plasmid, and integration into any cell line with endogenously GFP-tagged proteins allows for an inducible, rapid, and complete knockdown. We show that the nuclear RBPs SRSF3, SRSF5, SRRM2, and NONO are completely cleared from nuclear speckles and paraspeckles within 2 h. hGRAD works in various cell types, is more efficient than previous methods, and does not require the expression of exogenous ubiquitin ligases. Combining SRSF5 hGRAD degradation with Nascent-seq uncovered transient transcript changes, compensatory mechanisms, and an effect of SRSF5 on transcript stability.
Vortex circular airy beams through leaky-wave antennas
Authors: Benedetti Alessio , Comite Davide , Fuscaldo Walter , Baccarelli Paolo , Galli Alessandro , Burghignoli Paolo
Published: December 2023

A novel method to design leaky-wave antennas radiating vortex cylindrical Airy beams at microwave frequencies is here presented. Two different approaches are adopted to produce waves with a nonzero orbital angular momentum (OAM): one based on a bull’s eye design excited by a uniform circular array of vertical coaxial probes with proper azimuthal phase delay, and one based on a single coaxial feeder exciting a multi-spiral radiator. Both of them take advantage of backward radial propagation of cylindrical leaky waves promoting circular Airy beams with vortex patterns. The OAM state can be changed by either varying the probe phasing or the number of spiral units. A reference profile is designed under transverse-electric and transverse-magnetic excitation independently. Numerical full-wave analysis are performed using different angular states to validate the antenna design, as well to highlight the different advantages of the two alternative design approaches.
Real-time detection and localization method for weld seam of narrow butt joint based on semantic segmentation
Authors: Chen Xinyu , Ma Qihao , He Zhuzhen , Sun Xiaoyu , Ren Yan
Published: December 2023

Structured light measurement is widely used in welding seam tracking because of its high precision and robustness. For the narrow butt joint, the positioning method by reconstructing the weld contour is not suitable for the welding of the narrow butt joint because it is difficult for the laser stripe to produce obvious deformation when projected to the weld. In this study, high-quality images with laser stripes and narrow butt joints are captured by the improved structured light vision sensor, which is equipped with an auxiliary light source. A two-step processing framework, including semantic segmentation and groove positioning, is raised to locate the feature point of the narrow butt joint. Firstly, we design the strip pooling ENet (SP-ENet), a real-time network specifically designed to accurately segment narrow weld images. Our proposed network outperforms other classical segmentation networks in terms of segmentation accuracy and proves to be highly suitable for the detection of narrow butt joint welds. Secondly, a combining method of random sample consensus (RANSAC) and iterative fitting to calculate the sub-pixel coordinates of weld feature points accurately. Finally, a trajectory smoothing model based on the Kalman filter is proposed to reduce the trajectory jitter. The above methods were tested on a self-built robotic welding experimental platform. Experimental results show that the proposed method can be used for real-time detection and positioning of narrow butt joints. The positioning trajectory is smooth, with most positioning errors less than 2 pixels. The mean tracking error reaches 0.207 mm, which can meet the practical welding requirements.