bluuebunny/crossref_metadata_2025 huggingface dataset:
A laser powder bed fusion system for operando synchrotron x-ray imaging and correlative diagnostic experiments at the Stanford Synchrotron Radiation Lightsource
Authors: Martin Aiden A. , Wang Jenny , DePond Philip J. , Strantza Maria , Forien Jean-Baptiste , Gorgannejad Sanam , Guss Gabriel M. , Thampy Vivek , Fong Anthony Y. , Weker Johanna Nelson , Stone Kevin H. , Tassone Christopher J. , Matthews Manyalibo J. , Calta Nicholas P.
Published: April 2022

Laser powder bed fusion (LPBF) is a highly dynamic multi-physics process used for the additive manufacturing (AM) of metal components. Improving process understanding and validating predictive computational models require high-fidelity diagnostics capable of capturing data in challenging environments. Synchrotron x-ray techniques play a vital role in the validation process as they are the only in situ diagnostic capable of imaging sub-surface melt pool dynamics and microstructure evolution during LPBF-AM. In this article, a laboratory scale system designed to mimic LPBF process conditions while operating at a synchrotron facility is described. The system is implemented with process accurate atmospheric conditions, including an air knife for active vapor plume removal. Significantly, the chamber also incorporates a diagnostic sensor suite that monitors emitted optical, acoustic, and electronic signals during laser processing with coincident x-ray imaging. The addition of the sensor suite enables validation of these industrially compatible single point sensors by detecting pore formation and spatter events and directly correlating the events with changes in the detected signal. Experiments in the Ti–6Al–4V alloy performed at the Stanford Synchrotron Radiation Lightsource using the system are detailed with sufficient sampling rates to probe melt pool dynamics. X-ray imaging captures melt pool dynamics at frame rates of 20 kHz with a 2 µm pixel resolution, and the coincident diagnostic sensor data are recorded at 470 kHz. This work shows that the current system enables the in situ detection of defects during the LPBF process and permits direct correlation of diagnostic signatures at the exact time of defect formation.
Effects of nanoparticle size and shape in clathrin-mediated endocytosis
Authors: Xu Wu , Liu Xuheng , Liu Xiaohu
Published: April 2022

Nanoparticles have been extensively adopted to deliver therapeutic drug molecules to cells through clathrin-mediated endocytosis (CME). The size and shape of nanoparticles are important factors in the design of a drug delivery system. Both the clathrin coat and actin force induce the bending of the membrane during CME. However, due to the complex coupled effects of size, shape, and surface properties, nanoparticle shape effects are difficult to elucidate through experiments. Herein, we establish a comprehensive framework considering both the actin force and the dynamic assembly of the clathrin coat. To explore the effect of the nanoparticle size and shape on CME, we construct a clathrin coat growth model with actin force feedback. The clathrin coat growth model, nanoparticle internalization efficiency, and transportation efficiency are discussed through numerical analysis. The transportation efficiency is defined by the energy cost of the cell absorbing unit dose target drug. Numerical results illustrate that the proposed clathrin coat growth model is consistent with the actual physiological process, especially for CME considering receptor-mediated effects. The elliptical nanoparticle exhibits higher internalization and transportation efficiencies. A larger nanoparticle has lower internalization efficiency but higher transportation efficiency. Our results demonstrate that the internalization and transportation efficiencies of nanoparticles with an intermediate aspect ratio are higher than those with low or high aspect ratios. Our model provides insight into the intrinsic mechanism of CME and useful guidance for the practical design of the size and shape of nanoparticles for biopharmaceutical research.
A qPlus-based scanning probe microscope compatible with optical measurements
Authors: Cheng Bowei , Wu Da , Bian Ke , Tian Ye , Guo Chaoyu , Liu Kaihui , Jiang Ying
Published: April 2022

We design and develop a scanning probe microscope (SPM) system based on the qPlus sensor for atomic-scale optical experiments. The microscope operates under ultrahigh vacuum and low temperature (6.2 K). In order to obtain high efficiency of light excitation and collection, two front lenses with high numerical apertures (N.A. = 0.38) driven by compact nano-positioners are directly integrated on the scanner head without degrading its mechanical and thermal stability. The electric noise floor of the background current is 5 fA/Hz1/2, and the maximum vibrational noise of the tip height is below 200 fm/Hz1/2. The drift of the tip–sample spacing is smaller than 0.1 pm/min. Such a rigid scanner head yields small background noise (oscillation amplitude of ∼2 pm without excitation) and high quality factor (Q factor up to 140 000) for the qPlus sensor. Atomic-resolution imaging and inelastic electron tunneling spectroscopy are obtained under the scanning tunneling microscope mode on the Au(111) surface. The hydrogen-bonding structure of two-dimensional (2D) ice on the Au(111) surface is clearly resolved under the atomic force microscope (AFM) mode with a CO-terminated tip. Finally, the electroluminescence spectrum from a plasmonic AFM tip is demonstrated, which paves the way for future photon-assisted SPM experiments.
Diffusiophoresis in a near-critical binary fluid mixture
Authors: Fujitani Youhei
Published: April 2022

We consider placing a rigid spherical particle into a binary fluid mixture in the homogeneous phase near the demixing critical point. The particle surface is assumed to have a short-range interaction with each mixture component and to attract one component more than the other. Owing to large osmotic susceptibility, the adsorption layer, where the preferred component is more concentrated, can be of significant thickness. This causes a particle motion under an imposed composition gradient. Thus, diffusiophoresis emerges from a mechanism which has not been considered so far. We calculate how the mobility depends on the temperature and particle size.
Improved capillary rheometry for viscous Newtonian filaments
Authors: Balakrishna Subramaniam , Schultz William W.
Published: April 2022

The efficacy of the kinematic differential analysis of McCarroll et al. [“Differential analysis of capillary breakup rheometry for Newtonian liquids,” J. Fluid Mech. 804, 116 (2016)], expanding on McKinley and Tripathi [“How to extract the Newtonian viscosity from capillary breakup measurements in a filament rheometer,” J. Rheol. 44, 653 (2000)], to evaluate the surface tension to viscosity ratio for Newtonian filaments is examined. The analysis is valid during and after stretch, while the latter is traditionally applied after cessation of stretch as the midfilament radius approaches zero. Through numerical simulations, the evaluation of viscosity is investigated for two common stretch histories: (a) the ramp function and (b) the modified step strain. The challenges with stretch are twofold: rapid stretch (large capillary number) results in a nearly cylindrical filament with a rapid change near the plate that challenges the one-dimensional (1D) approximation, while slow stretch results in a nearly static solution with limited viscous information. We examine the capillary number-aspect ratio parameter space and find the ramp function with small stretching speeds optimal. Hence, the most accurate measurements are taken while the filament is being stretched.
Light-induced trap emptying revealed by intensity-dependent quantum efficiency of organic solar cells
Authors: Liraz Dan , Cheng Pei , Yang Yang , Tessler Nir
Published: April 2022

Revisiting the intensity-dependent quantum efficiency (IDQE) technique in the context of non-fullerene acceptors, we find that at forward-bias conditions, the response exhibits what seems to be anomalous behavior that is not consistent with light excitation induced trap filling. Analysis based on the Shockley–Read–Hall model leads to the conclusion that the contacts cause the traps to be completely full in the dark. The role of the light excitation is to half-empty the traps, and thus, the “anomalous” behavior is created. By fitting the IDQE at several bias levels, we find that the trapping is consistent with multiphonon capture by a state close to the middle of the gap. As trap-assisted recombination is a significant loss mechanism, it is essential to fully monitor it for indoor applications as well as to cross the single junction 20% power conversion efficiency limit.
Laser-frequency stabilization with differential single-beam saturated absorption spectroscopy of 4He atoms
Authors: Wang Bowen , Peng Xiang , Wang Haidong , Liu Yang , Guo Hong
Published: April 2022

Differential single-beam saturated-absorption spectroscopy (DSSAS) is proposed to stabilize lasing frequency and suppress Doppler-broadened background and common-mode optical noise. The spectral first-derivative demodulated signal of metastable He4 atoms is used as an error signal to stabilize a fiber laser around 1083 nm. Experimental results show that, compared with existing non-DSSAS frequency stabilization, DSSAS stabilization produces better stability and lower fluctuations, especially for frequency-noise-corrupted lasers. In DSSAS stabilization, for data acquired over 7000 s, the root mean square frequency fluctuation of the fiber laser is 16.4 kHz, and the frequency stability described by the modified Allan deviation is 4.1 × 10−12 at 100 s. Even for a defective laser with poor frequency stability, the proposed scheme demonstrates experimentally high capability of noise suppression and reduces the frequency fluctuations by two orders of magnitude. Given its simplicity and compact design, frequency stabilization by DSSAS is promising for quantum-sensor applications, such as atomic magnetometers, atomic gyroscopes, and atomic clocks.
Development and integration of photonic Doppler velocimetry as a diagnostic for radiation driven experiments on the Z-machine
Authors: Swanson K. J. , Jaar G. S. , Mayes D. C. , Mancini R. C. , Ivanov V. V. , Astanovitskiy A. L. , Dmitriev O. , Klemmer A. W. , De La Cruz C. , Dolan D. , Porwitzky A. , Loisel G. P. , Bailey J. E.
Published: April 2022

Plasma density measurements are key to a wide variety of high-energy-density (HED) and laboratory astrophysics experiments. We present a creative application of photonic Doppler velocimetry (PDV) from which time- and spatially resolved electron density measurements can be made. PDV has been implemented for the first time in close proximity, ∼6 cm, to the high-intensity radiation flux produced by a z-pinch dynamic hohlraum on the Z-machine. Multiple PDV probes were incorporated into the photoionized gas cell platform. Two probes, spaced 4 mm apart, were used to assess plasma density and uniformity in the central region of the gas cell during the formation of the plasma. Electron density time histories with subnanosecond resolution were extracted from PDV measurements taken from the gas cells fielded with neon at 15 Torr. As well, a null shot with no gas fill in the cell was fielded. A major achievement was the low noise high-quality measurements made in the harsh environment produced by the mega-joules of x-ray energy emitted at the collapse of the z-pinch implosion. To evaluate time dependent radiation induced effects in the fiber optic system, two PDV noise probes were included on either side of the gas cell. The success of this alternative use of PDV demonstrates that it is a reliable, precise, and affordable new electron density diagnostic for radiation driven experiments and more generally HED experiments.
Isentropic plasma sheath model for improved fidelity
Authors: Sahu Rupali , Tropina Albina , Miles Richard
Published: April 2022

A model is developed for a collisionless plasma sheath assuming isentropic electrons in contrast to the standard isothermal electron assumption. This approach is enabled by the approximation of a Maxwellian electron velocity distribution function across the sheath, which is justified by near wall measurements. The conservation of entropy leads to a modified Boltzmann relation and a modified Bohm criterion. The predicted floating sheath potential is in excellent agreement with experimental data. Takamura's model for a space-charge limited plasma sheath near an emissive surface is also modified for isentropic electrons and with that modification agrees well with numerical results from a full fluid plasma model.
Fully coupled modeling of two-phase fluid flow and geomechanics in ultra-deep natural gas reservoirs
Authors: Shen Weijun , Ma Tianran , Li Xizhe , Sun Baojiang , Hu Yong , Xu Jianchun
Published: April 2022

Efficiently and accurately understanding the fluid flow behavior in ultra-deep natural gas reservoirs is very challenging due to the complex geological environment and the intricate gas properties at high pressure. In this study, a fully coupled fluid flow and geomechanical model was developed to simulate complex production phenomena in ultra-deep natural gas reservoirs. Stress-dependent porosity and permeability models were applied, and then the governing equations of the model were incorporated into COMSOL Multiphysics. Furthermore, the model was verified by the reservoir depletion from the Keshen gas field in China, and the effects of reservoir properties and geomechanics on gas production were discussed. The results showed that the reservoir pressure and water saturation exhibited a significant funnel-shaped decline during the reservoir depletion. The higher relative permeability of the gas phase results in more methane gas production, thereby reducing the average pore pressure and gas saturation near the wellhead. When considering geomechanical effects, the production behavior significantly changes. The predictive value of gas production was higher when the reservoir rock deformation was ignored. The gas production exhibited strong positive correlations with reservoir porosity, fracture permeability, elastic modulus, and Poisson's ratio. Larger porosity, elastic modulus, and Poisson's ratio resulted in smaller deformation, while a smaller fracture permeability leads to larger deformation in ultra-deep natural gas reservoirs.
Resistively loaded coplanar waveguide for microwave measurements of induced carriers
Authors: Freeman M. L. , Lu Tzu-Ming , Engel L. W.
Published: April 2022

We describe the use of a coplanar waveguide (CPW) whose slots are filled with a resistive film, a resistively loaded CPW (RLCPW), to measure two-dimensional electron systems (2DESs). The RLCPW applied to the sample hosting the 2DES provides a uniform metallic surface serving as a gate to control the areal charge density of the 2DES. As a demonstration of this technique, we present measurements on a Si metal–oxide–semiconductor field-effect transistor and a model that successfully converts microwave transmission coefficients into conductivity of a nearby 2DES capacitively coupled to the RLCPW. We also describe the process of fabricating the highly resistive metal film required for fabrication of the RLCPW.
A versatile setup for studying size and charge-state selected polyanionic nanoparticles
Authors: Raspe K. , Müller M. , Iwe N. , Wolf R. N. , Oelßner P. , Martinez F. , Schweikhard L. , Meiwes-Broer K.-H. , Tiggesbäumker J.
Published: April 2022

Using the example of metal clusters, an experimental setup and procedure is presented, which allows for the generation of size and charge-state selected polyanions from monoanions in a molecular beam. As a characteristic feature of this modular setup, the further charging process via sequential electron attachment within a three-state digital trap takes place after mass-selection. In contrast to other approaches, the rf-based concept permits access to heavy particles. The procedure is highly flexible with respect to the preparation process and potentially suitable for a wide variety of anionic species. By adjusting the storage conditions, i.e., the radio frequency, to the change in the mass-to-charge ratio, we succeeded in producing clusters in highly negative charge states, i.e., Ag8007−. The capabilities of the setup are demonstrated by experiments extracting electronic and optical properties of polyanionic metal clusters by analyzing the corresponding photoelectron spectra.
Charge-encoded multi-photoion coincidence for three-body fragmentation of CO2 in the strong laser fields
Authors: Zhang Shuai , Wang Xincheng , Jiang Wenbin , Zhang Yizhu , Jiang Yuhai , Zhu Zhiyuan
Published: April 2022

The photoion–photoion coincidence (PIPICO) is a simple and effective approach for the selection of correlated fragments in a specific dissociating channel in molecules. We propose here a charge-encoded multi-photoion coincidence (cMUPICO) method, in analogy to traditional PIPICO, however in which the charge of individual fragments is taken into account. The cMUPICO method allows for clearly displaying coincident channels for dissociation channels containing three more fragments with unequal charge states, invisible in the traditional PIPICO. As a demonstration, three-body fragmentation dynamics of CO2 in strong IR laser fields is analyzed, and 11 dissociation channels are effectively identified, five of which are first found with cMUPICO. The present results show that cMUPICO is a powerful and practical tool for distinguishing various dissociation channels with multiply charged multi-photoions.
Nonlocal symmetries and Darboux transformations of the Camassa–Holm equation and modified Camassa–Holm equation revisited
Authors: Li Nianhua , Tian Kai
Published: April 2022

By the nonlocal symmetry approach, Hernández-Heredero and Reyes [J. Phys. A: Math. Theor. 42, 182002 (2009)] and Bies et al. [J. Math. Phys. 53, 073710 (2012)] obtained Darboux Transformations (DTs) of the Camassa–Holm equation and the modified Camassa–Holm equation. However, the wave function does not appear in their DTs explicitly. We introduce wave functions to the DTs and show how they are related to the binary DT of the first negative flow in the Korteweg–de Vries (KdV) hierarchy. Furthermore, we connect nonlocal symmetries of the Camassa–Holm equation and the modified Camassa–Holm equation with those of the negative KdV equation and the negative modified KdV equation, respectively.
Menisci evaporation of electrokinetic liquid-film flows within inclined micro-confinements
Authors: Dhar Purbarun , Jana Rupayan
Published: April 2022

In this article, we consider the electrohydrodynamics of drainage and evaporation induced transport behavior of a liquid meniscus draining along an inclined micro-confinement. The film-flow-hydrodynamics is altered by the application of electrokinetic constraints and directionality either by aiding or opposing the gravity driven flow. This behavior, in turn, morphs the nature of the meniscus formed and the direction and magnitude of the interfacial flow velocity. Consequently, the Stefan flow in the vapor diffusion layer and the thermal gradient across the liquid film are morphed, leading to changed meniscus evaporation kinetics and film dry-out regimes. The film distribution, dry-out lengths, and Nusselt numbers are deduced from a detailed theoretical analysis incorporating the hydrodynamics, heat and mass transfer aspects. We further show that a non-dimensional local film number, of the form ρgsinθδ02/σ, may be proposed to efficiently design and develop such microfluidic systems to obtain desired heat and mass transfer rates within microscale thermofluidic devices. The findings may hold significance for efficient development of evaporative microfluidic systems, reactors, and micro-devices that operate on principles of chemical drying, deposition, and analysis.
Numerical analysis of electro-convection in dielectric liquids with residual conductivity
Authors: Huang Junyu , Wu Jian , Du Zhonglin , Vázquez Pedro A. , Pérez Alberto T.
Published: April 2022

Injection-induced electro-convection (EC) of dielectric liquids is a fundamental problem in electrohydrodynamics. However, most previous studies with this type of EC assume that the liquid is perfectly insulating. By perfectly insulating, we mean an ideal liquid with zero conductivity, and in this situation, the free charges in the bulk liquid originate entirely from the injection of ions. In this study, we perform a numerical analysis with the EC of dielectric liquids with a certain residual conductivity based on a dissociation–injection model. The spatiotemporal distributions of the flow field, electric field, and positive/negative charge density in the parallel plate configuration are solved utilizing the finite volume method. It is found that the residual conductivity inhibits the onset of EC flow, as well as the strength of the flow field. The flow features and bifurcations are studied in various scenarios with three different injection strengths in the strong, medium, and weak regimes. Three distinct bifurcation sequences with abundant features are observed by continually increasing or decreasing the electric Reynolds number. The present study shows that the residual conductivity significantly affects the bifurcation process and the corresponding critical point of EC flows.
Kinematic stability and simulations of the variational two-fluid model for slug flow
Authors: Clausse A. , Chetty K. , Buchanan J. , Ram R. , Lopez de Bertodano M.
Published: April 2022

The two-fluid short-wave theory (TF-SWT) mode of the one-dimensional two-fluid model (TFM) [A. Clausse and M. Lopez de Bertodano, “Natural modes of the two-fluid model of two-phase flow,” Phys. Fluids 33, 033324 (2021)] showed that the incompressible kinematic and Kelvin–Helmholtz instabilities are the source of the long-standing ill-posed question. Here, the stability of the short wave mode is analyzed to obtain an unstable incompressible well-posed TFM for vertical slug flow, where inertial coupling and drag play the key role. Then, a computational method is implemented to perform non-linear simulations of slug waves. Linear stability analyses, i.e., characteristics and dispersion, of a variational TF-SWT for vertical slug flows are presented. The current TFM is constituted with a lumped-parameter model of inertial coupling between the Taylor bubble and the liquid. A characteristic analysis shows that this conservative model is parabolic, and it provides a base upon which other models can be constructed, including short-wave damping mechanisms, like vortex dynamics. The dispersion analysis shows that depending on the interfacial drag, the problem can be kinematic unstable. A new kinematic condition in terms of the inertial coupling and the interfacial drag is derived that is consistent with previous theoretical and experimental results. The material waves, which are predicted by linear stability theory, then develop into nonlinear slug waveforms that are captured by the numerical simulations. These and the horizontal stratified flow waves of previous research illustrate the TFM capability to model interfacial structures that behave like waves. Otherwise, when the physics of the TF-SWT waves is ignored, the model is ill-posed.
A concept of a broadband inverted geometry spectrometer for the Second Target Station at the Spallation Neutron Source
Authors: Mamontov E. , Boone C. , Frost M. J. , Herwig K. W. , Huegle T. , Lin J. Y. Y. , McCormick B. , McHargue W. , Stoica A. D. , Torres P. , Turner W.
Published: April 2022

BWAVES is an acronym for Broadband Wide-Angle VElocity Selector spectrometer, indicating that a novel WAVES (Wide-Angle VElocity Selector) device will be used to select the velocity/wavelength of the detected neutrons after they are scattered by the sample. We describe a conceptual design of BWAVES, a time-of-flight broadband inverted-geometry neutron spectrometer for the Second Target Station at the Spallation Neutron Source operated by Oak Ridge National Laboratory. Being the first inverted geometry spectrometer where the energy of the detected neutrons can be chosen by a WAVES device mechanically, irrespective of the limitations imposed by the crystal analyzers or filters, BWAVES will feature a uniquely broad, continuous dynamic range of measurable energy transfers, spanning 4.5 decades. This will enable measurements of both vibrational and relaxational excitations within the same, continuous scattering spectra. Novel approaches that are necessary for the implementation of a WAVES device at the BWAVES spectrometer will result in a spectrometer with the design and characteristics much different from those displayed by the neutron spectrometers in existence today.
Experimental study of cavitating vortex rope and water column separation in a pump turbine
Authors: He Xianghui , Yang Jiandong , Yang Jiebin , Hu Jinhong , Peng Tao
Published: April 2022

During the transient processes in load rejection in a pumped-storage system, water column separation (WCS) can occur in the draft tube when the local pressure is less than the vapor pressure. The reverse water hammer due to water column bridging affects the safety of the unit and the tailrace tunnel. However, what are the conditions that trigger WCS? What is the physical mechanism? These questions have not been elucidated experimentally. Therefore, it is necessary to investigate the conditions that lead to WCS and the impact of the reverse water hammer generated by WCS bridging on the stability of the unit. In this study, a semi-open test rig was modified by installing a variable-frequency pump to reduce the static pressure, resulting in a cavitation vortex in the draft tube. The static pressure and the water hammer pressure derived from load rejection cause the pressure at the draft tube wall to fall below the vapor pressure for some time, interrupting the flow in the draft tube. This is a typical case of WCS in a pump turbine. If the pressure in the draft tube does not remain at the minimum pressure for long enough, imperfect water column separation may occur with bubble groups. The amplitude of the pressure pulsations during the initial and development stages was (−0.2 m, 0.2 m). It was 4.96% of the initial static pressure. Thus, the pressure fluctuations have a negligible effect on WCS.
A heaving system with two separated oscillating water column units for wave energy conversion
Authors: Wang Chen , Zheng Siming , Zhang Yongliang
Published: April 2022

A theoretical model based on the linear potential theory is presented for two heaving oscillating water column (OWC) devices separated by a gap. The model includes relative motion and phase control between the devices and trapped water columns, and the hydrodynamic performance of the dual-OWC system thence evaluated. Matching conditions are employed along the common interfaces, and the power take-off model and motion equations of the OWC devices are incorporated into the solution procedure. At the top of each chamber, a Wells turbine is installed to extract wave power. To achieve the optimal overall power extraction performance, a numerical strategy of successive approximation is utilized to seek the optimal turbine damping combinations for the separated units. The effects of lip-wall draft and chamber breadth on the performance of a fully-free heaving dual-OWC system are explored. In view of the deficiency of a fully-free heaving system, two alternative optimization strategies are proposed, one focusing on the control of relative motion and phase between the water columns and the heaving devices, the other on utilizing resonance phenomenon inside the gap, achieved by tuning imposed linear spring constants and gap distance, respectively. It is shown that the control between heave motion of devices and water columns inside the chambers is beneficial for extracting more power over a broader range of wave frequencies. Moreover, enhanced extraction is likely over a wider range of wave conditions when the gap distance to wavelength triggers a sloshing mode inside the gap.
Modeling of repetitively pulsed low-pressure CO2 discharges
Authors: Naidis G. V. , Babaeva N. Yu.
Published: April 2022

A model of repetitively pulsed low-pressure CO2 discharges is developed. In the framework of this model, plasma characteristics (electric field, electron density, gas temperature, and vibrational temperature of the asymmetric mode) are calculated both during the pulses and in the afterglow periods. The CO2 conversion factor in repetitively pulsed discharges is calculated. Results of computation of plasma parameters and of the conversion factor agree with available experimental data.
The effect of medium viscosity and particle volume fraction on ultrasound directed self-assembly of spherical microparticles
Authors: Noparast S. , Guevara Vasquez F. , Raeymaekers B.
Published: April 2022

Ultrasound directed self-assembly (DSA) allows organizing particles dispersed in a fluid medium into user-specified patterns, driven by the acoustic radiation force associated with a standing ultrasound wave. Accurate control of the spatial organization of the particles in the fluid medium requires accounting for medium viscosity and particle volume fraction. However, existing theories consider an inviscid medium or only determine the effect of viscosity on the magnitude of the acoustic radiation force rather than the locations where particles assemble, which is crucial information to use ultrasound DSA as a fabrication method. We experimentally measure the deviation between locations where spherical microparticles assemble during ultrasound DSA as a function of medium viscosity and particle volume fraction. Additionally, we simulate the experiments using coupled-phase theory and the time-averaged acoustic radiation potential, and we derive best-fit equations that predict the deviation between locations where particles assemble during ultrasound DSA when using viscous and inviscid theory. We show that the deviation between locations where particles assemble in viscous and inviscid media first increases and then decreases with increasing particle volume fraction and medium viscosity, which we explain by means of the sound propagation velocity of the mixture. This work has implications for using ultrasound DSA to fabricate, e.g., engineered polymer composite materials that derive their function from accurately organizing a pattern of particles embedded in the polymer matrix.
Dynamics of a drop floating in vapor of the same fluid
Authors: Benilov E. S.
Published: April 2022

Evaporation of a liquid drop surrounded by either vapor of the same fluid, or vapor and air, is usually attributed to vapor diffusion, which, however, does not apply to the former setting, as pure fluids do not diffuse. The present paper puts forward an additional mechanism, one that applies to both settings. It is shown that disparities between the drop and vapor in terms of their pressure and chemical potential give rise to a flow. Its direction depends on the vapor density and the drop's size. In undersaturated or saturated vapor, all drops evaporate, but in oversaturated (yet thermodynamically stable) vapor, there exists a critical radius: smaller drops evaporate, whereas larger drops act as centers of condensation and grow. The developed model is used to estimate the evaporation time of a drop floating in saturated vapor. It is shown that, if the vapor-to-liquid density ratio is small, so is the evaporative flux; as a result, millimeter-sized water drops at temperatures lower than 70 °C survive for days. If, however, the temperature is comparable (but not necessarily close) to its critical value, such drops evaporate within minutes. Micron-sized drops, in turn, evaporate within seconds for all temperatures between the triple and critical points.
Avian diversity and abundance across years: consistent patterns in forests but not grasslands on Viti Levu, Fiji
Authors: Naikatini Alivereti N. , Keppel Gunnar , Brodie Gilianne , Kleindorfer Sonia
Published: April 2022

Context Habitat loss is a global problem and in Fiji >50% of the land area once covered by forests has been converted to grasslands and agricultural land. About 99% of Fiji’s endemic biodiversity and 80% of the land bird species have been identified as forest species. Aims In this study, we compare forest and grassland sites and test for consistency in avian diversity, abundance, foraging guild, and distribution status (endemic, native, introduced to Fiji) over a 5-year period (2016–2020). Methods We surveyed bird communities using the point count method with a 100 m radius and 7-min observation period per site. Key results A one-way analysis of similarities (ANOSIM) analysis showed significant differences in species composition and bird abundance between the forested habitats and grassland habitats. A general linear model test showed significant differences in foraging guild composition and distribution status between forested and grassland habitats. There were no significant differences between the three forested sites (primary montane forest, secondary old-growth forest, old-growth mahogany plantations with regenerating native species), while grassland sites had stronger annual change in species composition. Implications Forest cover, irrespective of whether these forests are of primary or secondary nature, therefore plays an important role in maintaining the native and endemic land bird species and other biodiversity in oceanic island ecosystems such as Viti Levu Island, Fiji.
Unidirectional mannitol synthesis ofAcinetobacter baumanniiMtlD is facilitated by the helix–loop–helix-mediated dimer formation
Authors: Tam Heng-Keat , König Patricia , Himpich Stephanie , Ngu Ngoc Dinh , Abele Rupert , Müller Volker , Pos Klaas M.
Published: April 2022

Significance

Mannitol biosynthesis is essential forAcinetobacter baumanniito cope with osmotic stress. Currently, onlyPseudomonas putida,Acinetobacter baylyi, andA. baumanniiare able to de novo synthesize mannitol by a structurally unique bifunctional mannitol-1-phosphate dehydrogenase/phosphatase (AbMtlD). The molecular mechanism of reduction and dephosphorylation of fructose-6-phosphate to mannitol is highly dependent on the substrate shuffling from one protomer to the other protomer by a unique helix–loop–helix domain–mediated dimer formation, thus ensuring unidirectional and efficient biosynthesis of mannitol. These observations support an evolutionary adaptation of AbMtlD by fusion of dehydrogenase and phosphatase domains to facilitate efficient unidirectional enzymatic production of mannitol, unifying regulatory control and minimizing the intracellular concentration of toxic mannitol-1-phosphate during salt stress.
Phenotype-Based Threat Assessment
Authors: Yang Jing , Eslami Mohammed , Chen Yi-Pei , Das Mayukh , Zhang Dongmei , Chen Shaorong , Roberts Alexandria-Jade , Weston Mark , Volkova Angelina , Faghihi Kasra , Moore Robbie K. , Alaniz Robert C. , Wattam Alice R. , Dickerman Allan , Cucinell Clark , Kendziorski Jarred , Coburn Sean , Paterson Holly , Obanor Osahon , Maples Jason , Servetas Stephanie , Dootz Jennifer , Qin Qing-Ming , Samuel James E. , Han Arum , van Schaik Erin J. , de Figueiredo Paul
Published: April 2022

Significance

Assessing the threat posed by bacterial samples is fundamentally important to safeguarding human health. Whole-genome sequence analysis of bacteria provides a route to achieving this goal. However, this approach is fundamentally constrained by the scope, the diversity, and our understanding of the bacterial genome sequences that are available for devising threat assessment schemes. For example, genome-based strategies offer limited utility for assessing the threat associated with pathogens that exploit novel virulence mechanisms or are recently emergent. To address these limitations, we developed PathEngine, a machine learning strategy that features the use of phenotypic hallmarks of pathogenesis to assess pathogenic threat. PathEngine successfully classified potential pathogenic threats with high accuracy and thereby establishes a phenotype-based, sequence-independent pipeline for threat assessment.
Structural conservation among variants of the SARS-CoV-2 spike postfusion bundle
Authors: Yang Kailu , Wang Chuchu , White K. Ian , Pfuetzner Richard A. , Esquivies Luis , Brunger Axel T.
Published: April 2022

Significance

Emergence of viral pathogens necessitates new approaches to study viral fusion and entry into host cells. A key step in mediating fusion involves the formation of a six-helix bundle within the spike protein. Rapid structural characterization of this state has been difficult, hindering understanding of emerging variants. We developed a method to efficiently determine high-resolution bundle structures by molecular scaffolding and cryogenic electron microscopy. Using this method, we determined bundle structures of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants. These structures reveal local effects of mutations on HR1HR2 interactions but global conservation of the bundle architecture among SARS-CoV-2 variants. We predict that inhibitors disrupting the postfusion bundle might be broadly efficacious against variants and even more distantly related lethal viruses.
Protective role of chaperone-mediated autophagy against atherosclerosis
Authors: Madrigal-Matute Julio , de Bruijn Jenny , van Kuijk Kim , Riascos-Bernal Dario F. , Diaz Antonio , Tasset Inmaculada , Martín-Segura Adrián , Gijbels Marion J. J. , Sander Bianca , Kaushik Susmita , Biessen Erik A. L. , Tiano Simoni , Bourdenx Mathieu , Krause Gregory J. , McCracken Ian , Baker Andrew H. , Jin Han , Sibinga Nicholas E. S. , Bravo-Cordero Jose Javier , Macian Fernando , Singh Rajat , Rensen Patrick C. N. , Berbée Jimmy F. P. , Pasterkamp Gerard , Sluimer Judith C. , Cuervo Ana Maria
Published: April 2022

Significance

Cardiovascular diseases remain the leading cause of death worldwide, with atherosclerosis being the most common source of clinical events. Metabolic changes with aging associate with concurrent increased risk of both type 2 diabetes and cardiovascular disease, with the former further raising the risk of the latter. The activity of a selective type of autophagy, chaperone-mediated autophagy (CMA), decreases with age or upon dietary excesses. Here we study whether reduced CMA activity increases risk of atherosclerosis in mouse models. We have identified that CMA is up-regulated early in response to proatherogenic challenges and demonstrate that reduced systemic CMA aggravates vascular pathology in these conditions. We also provide proof-of-concept support that CMA up-regulation is an effective intervention to reduce atherosclerosis severity and progression.
Exploring the predictive validity of an interpreting aptitude test battery
Authors: Liu Yubo , Zhang Wei
Published: April 2022

This study explores the validity of a battery of interpreting aptitude tests comprising the SynCloze test, the
Negative Affectivity Scale and the Inventory of Learning Styles in predicting the interpreting performance of Chinese interpreting
trainees. The aptitude test battery was conducted at the beginning of the first semester for 68 post-graduate interpreting
students in four Chinese interpreter training programs. English-Chinese (E-C) and Chinese-English (C-E) consecutive interpreting
(CI) tests that measure the interpreting proficiency of the participants were conducted at the end of the semester. The results of
the correlation and regression analysis indicated that the SynCloze test enjoyed statistically significant predictive power for
both directions of CI and that its predictive power was stronger for C-E CI (β = 0.70) than for E-C CI
(β = 0.48); negative affectivity was found to be a statistically significant predictor for E-C CI
(β = −0.21) but not for C-E CI. Neither the meaning-directed nor the reproduction-directed learning style
could predict interpreting performance. The implications of the findings are discussed in relation to interpreter selection and
training.
miR-374a-5p regulates inflammatory genes and monocyte function in patients with inflammatory bowel disease
Authors: Perez-Sanchez Carlos , Barbera Betancourt Ariana , Lyons Paul A. , Zhang Zinan , Suo Chenqu , Lee James C. , McKinney Eoin F. , Modis Louise K. , Ellson Christian , Smith Kenneth G.C.
Published: April 2022

MicroRNAs are critical regulators of gene expression controlling cellular processes including inflammation. We explored their role in the pathogenesis of inflammatory bowel disease (IBD) and identified reduced expression of miR-374a-5p in IBD monocytes that correlated with a module of up-regulated genes related to the inflammatory response. Key proinflammatory module genes, including for example TNFα, IL1A, IL6, and OSM, were inversely correlated with miR-374a-5p and were validated in vitro. In colonic biopsies, miR-374a-5p was again reduced in expression and inversely correlated with the same inflammatory module, and its levels predicted subsequent response to anti-TNF therapy. Increased miR-374a-5p expression was shown to control macrophage-driven inflammation by suppressing proinflammatory mediators and to reduce the capacity of monocytes to migrate and activate T cells. Our findings suggest that miR-374a-5p reduction is a central driver of inflammation in IBD, and its therapeutic supplementation could reduce monocyte-driven inflammation in IBD or other immune-mediated diseases.
Noise equivalent power of a NbTiN-Al-based kinetic inductance detector for terahertz sensing
Authors: Su R F , Shi L L , Zhou T , Yao B Z , Wu J B , Tu X C , Jia X Q , Kang L , Jin B B , Wang H B , Chen J , Wu P H
Published: April 2022

We have designed and fabricated a superconducting hybrid NbTiN-Al kinetic inductance detector (KID) over a broad band centered at 4.3 THz. The detector sensitivity is characterized by changing the bath temperature in a dark environment. Both amplitude and phase readouts are performed. The measured electrical noise equivalent power for phase readout is about 2.6 × 10−18 W · Hz−0.5 at 200 mK. This ultra-sensitive KID, which enables large arrays with frequency domain multiplexing, is promising for imaging instruments in space-based far-infrared observatories.
Dynamical analysis of diversity lump solutions to the (2+1)-dimensional dissipative Ablowitz–Kaup–Newell–Segure equation
Authors: Ma Hongcai , Gao Yidan , Deng Aiping
Published: April 2022

The lump solution is one of the exact solutions of the nonlinear evolution equation. In this paper, we study the lump solution and lump-type solutions of (2+1)-dimensional dissipative Ablowitz–Kaup–Newell–Segure (AKNS) equation by the Hirota bilinear method and test function method. With the help of Maple, we draw three-dimensional plots of the lump solution and lump-type solutions, and by observing the plots, we analyze the dynamic behavior of the (2+1)-dimensional dissipative AKNS equation. We find that the interaction solutions come in a variety of interesting forms.
Fusing atomic W states with Rydberg superatom
Authors: Zhang W Y , Liu Y L , Ji Y Q , Dong L , Xiu X M
Published: April 2022

Quantum entanglement is the basic resource of quantum information processing and quantum computation, especially multi-partite entanglement. The simple and efficient generation of multi-partite entanglement has always been one of the hot topics of scholars. In this paper, we propose a qubit-loss-free fusion scheme for generation of large-scale entangled W states with Rydberg superatom. By sending two superatoms belonging to a k-atom W states and a l-atom W states, respectively, into a cavity, we may obtain a (k + l)-atom W states via detecting the cavity state after interaction. The numerical simulation analysis shows that the fidelity is robust against both spontaneous emission of superatoms and decay of the cavity. In addition, the feasibility analysis indicates this scheme can also be realized in experiment.
Surface electron doping induced double gap opening in T
d-WTe2
Authors: Li Qi-Yuan , Lv Yang-Yang , Xu Yong-Jie , Zhu Li , Zhao Wei-Min , Chen Yanbin , Li Shao-Chun
Published: April 2022

By using scanning tunneling microscopy, we investigated the electronic evolution of T
d-WTe2 via in-situ surface alkali K atoms deposition. The T
d-WTe2 surface is electron doped upon K deposition, and as the K coverage increases, two gaps are sequentially opened near Fermi energy, which probably indicates that two phase transitions concomitantly occur during electron doping. The two gaps both show a dome-like dependence on the K coverage. While the bigger gap shows no prominent dependence on the magnetic field, the smaller one can be well suppressed and thus possibly corresponds to the superconducting transition. This work indicates that T
d-WTe2 exhibits rich quantum states closely related to the carrier concentration.
Electron emission induced by keV protons from tungsten surface at different temperatures
Authors: Zeng Li-Xia , Zhou Xian-Ming , Cheng Rui , Liu Yu , Zhang Xiao-An , Xu Zhong-Feng
Published: April 2022

The electron emission yield is measured from the tungsten surface bombarded by the protons in an energy range of 50 keV–250 keV at different temperatures. In our experimental results, the total electron emission yield, which contains mainly the kinetic electron emission yield, has a very similar change trend to the electronic stopping power. At the same time, it is found that the ratio of total electron emission yield to electronic stopping power becomes smaller as the incident ion energy increases. The experimental result is explained by the ionization competition mechanism between electrons in different shells of the target atom. The explanation is verified by the opposite trends to the incident energy between the ionization cross section of M and outer shells.
Temperature dependence of spin pumping in YIG/NiO(x)/W multilayer
Authors: Ni Lijun , Wang Wenqiang , Jin Lichuan , Ye Jiandong , Gong Hehe , Zhan Xiang , Chen Zhendong , Zhang Longlong , Dai Xingze , Li Yao , Zhang Rong , Yang Yi , Zhang Huaiwu , Liu Ronghua , Chen Lina , Xu Yongbing
Published: April 2022

We report the temperature dependence of the spin pumping effect for Y3Fe5O12 (YIG, 0.9 μm)/NiO (t
NiO)/W (6 nm) (t
NiO = 0 nm, 1 nm, 2 nm, and 10 nm) heterostructures. All samples exhibit a strong temperature-dependent inverse spin Hall effect (ISHE) signal I
c and sensitivity to the NiO layer thickness. We observe a dramatic decrease of I
c with inserting thin NiO layer between YIG and W layers indicating that the inserting of NiO layer significantly suppresses the spin transport from YIG to W. In contrast to the noticeable enhancement in YIG/NiO (t
NiO ≈ 1–2 nm)/Pt, the suppression of spin transport may be closely related to the specific interface-dependent spin scattering, spin memory loss, and spin conductance at the NiO/W interface. Besides, the I
c of YIG/NiO/W exhibits a maximum near the T
N of the AF NiO layer because the spins are transported dominantly by incoherent thermal magnons.
From Einstein to Boscovich
Authors: Anderton Roger J
Published: April 2022

The connections of Boscovich’s theory to Einstein’s relativity and Einstein’s quest for a final theory is explored.