bluuebunny/crossref_metadata_2025 huggingface dataset:
Bioinspired enzyme-powered microswimmer for pH-sensitive locomotion in the gastric mucus
Authors: Aghaei Elika , Jannesari Ghomsheh Mehryar , Behrouzi Kamyar , Jafari Azadeh , Raisee Dehkordi Mehrdad
Published: August 2023

Helicobacter pylori penetrates the gastric mucus by producing ammonia with urease, which locally raises the pH and turns the nearby gel into a solution. Here, we mimic this strategy by proposing an enzyme-powered microswimmer in the gastric mucus in one- and two-enzyme configurations. The surface-immobilized urease is considered the primary enzyme, which turns the gel into a viscous solution, while in some cases, a secondary enzyme is also coated and transforms the solution into the gel. The viscous solution and the gel are modeled as a Newtonian fluid and a Brinkman medium, respectively. A “binary” or “zero-one” coating pattern is established in which the “one” regions are coated with urease while the “zero” regions are coated with the second enzyme or are not coated. A parameter formulates the coating by specifying which part of the microswimmer’s half is coated with the first enzyme. Owing to this pattern, a winglet of the viscous solution is created for each half of the microswimmer. The diffusion of urease combines these two winglets to create a fluid pocket around the microswimmer, similar to H. pylori, but the second enzyme inhibits the development of this fluid pocket. The creation of the winglets and the pressure difference between the two sides propel the microswimmer in the mucus. The two-enzyme configuration better maintains the pressure difference by isolating the two winglets and reducing the symmetry. We obtain optimal coating parameters for each configuration to simultaneously create solution regions and maintain the pressure difference around the microswimmer.
Experimental study of underwater explosions below a free surface: Bubble dynamics and pressure wave emission
Authors: Li Ming-Kang , Wang Shi-Ping , Zhang Shuai , Sagar Hemant
Published: August 2023

The current work experimentally studies the complex interaction between underwater explosion (UNDEX) bubbles and a free surface. We aim to reveal the dependence of the associated physics on the key factor, namely, the dimensionless detonation depth γ (scaled by the maximum equivalent bubble radius). Four typical bubble behavior patterns are identified with the respective range of γ: (i) bubble bursting at the free surface, (ii) bubble jetting downward, (iii) neutral collapse of the bubble, and (iv) quasi-free-field motion. By comparison of the jet direction and the migration of the bubble centroid, a critical value of γ is vital for ignoring the effects of the free surface on UNDEX bubbles. Good agreements are obtained between the experimental data and Zhang equation [Zhang et al., “A unified theory for bubble dynamics,” Phys. Fluids 35, 033323 (2023)]. Additionally, the dependence of the pressure signals in the flow field on γ is investigated. The peak pressure, impulse, and energy dissipation in the UNDEX are investigated.
All-plasmonic-metal chiral nanostructures fabricated by circularly polarized light
Authors: Ishida Takuya , Isawa Akitoshi , Kuroki Shuki , Kameoka Yuri , Tatsuma Tetsu
Published: August 2023

Chiral plasmonic nanostructures, which would be applied to enantioselective sensors and metasurfaces, can be prepared in an enantioselective manner by irradiation with circularly polarized light (CPL). However, their resonance sites have been covered with non-plasmonic, dielectric moieties. Here, we prepared all-silver chiral plasmonic nanostructures on a glass plate in one-step by irradiating 380–450 nm right- or left-CPL to an aqueous solution containing Ag+ and citrate ions. Achiral or racemic Ag nanoparticles with anisotropic geometry are deposited on a glass plate by photochemical electron transfer from citrate to Ag+ in the initial phase. The deposited nanoparticles are grown into chiral structures under CPL via generation of an electric field with chiral distributions. An achiral Ag nanoplate array was also grown under 600–700 nm CPL into chiral nanostructure arrays on the basis of hot electron reduction of Ag+.
Dynamics of a wall-mounted cantilever plate under low Reynolds number transverse flow in a two-dimensional channel
Authors: Kumar Vivek , Assam Ashwani , Prabhakaran Deepu
Published: August 2023

The present work numerically investigates the dynamics of an elastic two-dimensional cantilever plate fixed at the bottom wall of a channel carrying flow using an open-source multi-physics computational fluid dynamics solver, SU2. Chief non-dimensional parameters, viz., Cauchy number (Ca), channel height, and mass ratio, are explored to predict the structural response of the plate interacting with the laminar parabolic profile in the channel at relatively low Reynolds numbers (Re=20−120). For a steady inflow, we show the existence of two distinctive modes of plate flexural oscillations, namely, F1 and F2, where the plate attains self-sustained periodic oscillations close to its first and second natural frequencies, respectively, for discrete ranges of Ca and three static modes, namely, S1, S2, and S3 for the other ranges of Ca in which steady-state configuration is obtained. The physical reasons underpinning the flow-induced oscillations and static shapes are examined using scaling arguments. F1 oscillations are shown to be vortex-induced oscillations, which get suppressed at low enough channel height, owing to higher viscous dissipation. Additionally, the window of F1 zone was found to shift to lower Ca with an increase in the mass ratio. Increasing the Reynolds number was found to cause the F1 zone to diminish in size, and beyond a critical Reynolds number, F1 was completely suppressed. On the other hand, F2 oscillations, which are shown to be induced by an unsteady drag force, are found to exist throughout the range of Re considered in the study.
Hundred-femtosecond-level concise optical time delay measurement system based on linear optical sampling
Authors: Zhang Yufei , Chen Ziyang , Yu Dongrui , Niu Jialin , Chen Xing , Guo Hong
Published: August 2023

Fiber-delay measurement is one of the key fundamental technologies in numerous fields. Here, we propose and experimentally demonstrate a high-precision and concise optical time delay measurement system based on the technique of linear optical sampling, reaching the precision better than 100 fs under averaging. The use of only two optical frequency combs without locking the carrier-envelope-offset frequency greatly simplifies the structure of the time-delay measurement system. We also experimentally investigate the current limitations on the precision of the system. The timing jitter noises of two sources are mainly non-common mode and are both restricted to the frequency sources. Our results indicate that the proposed device can measure fiber length fluctuations below 10 µm, paving the way for further analyses of the external disturbances on the fiber link.
Effect of intrinsic vacancies on the electromagnetic properties of half-doped Sm0.5Ca0.5MnO3 manganites studied by positron annihilation
Authors: Huang S. J. , Liu J. D. , Pan Z. W. , Zhang H. J. , Ye B. J.
Published: August 2023

Mixed valence manganites are potential functional materials due to their unique electromagnetic properties. In this work, half-doped ceramics with the perovskite structure Sm0.5Ca0.5MnO3 polycrystalline samples are synthesized by the solid-state reaction method in open air at different final sintering temperatures. Structures and particle sizes are studied by x-ray diffraction and scanning electron microscopy, respectively. Positron annihilation spectroscopy and density-functional theory calculations are used to characterize the intrinsic vacancies in the bulk. Thereafter, the effect of vacancies on the magnetic and magnetoresistance (MR) properties is investigated. We find that Mn monovacancies (VMn) exist in the bulk among all the samples, and the concentration of VMn is different. We suggest a possible defect model that can be well applied to explain the phenomena of their electromagnetic properties. The transition temperature of the charge-order state (TCO) and ferromagnetic and anti-ferromagnetic (TN) are most likely related to the concentration of VMn and the particle sizes or pore sizes, respectively. The glass spin state transition temperature seems to be independent of the defect concentration and type. The metal conductive behavior does not appear in a high magnetic field and at low temperatures, which may be caused by the presence of a high concentration of VMn in the bulk and oxygen-related defects in the boundary, and the double exchange interaction is suppressed. At temperatures below TN and under a weak magnetic field, the MR is related to the total defect concentration. In addition, the high concentration of VMn is unfavorable for obtaining a high MR value.
A tunable liquid crystal polarization converter based on hybrid alignment with a deeply rubbed polyimide surface
Authors: Zhou Zuowei , Li Senhao , Xu Miao
Published: August 2023

This work demonstrates a tunable liquid crystal polarization converter (LCPC) constructed using two conductive glass substrates that are treated with homogeneous alignment and azimuthal alignment, respectively. The azimuthal alignment surface is deeply rubbed to enhance the alignment performance to tilted LC molecules compared with the homogeneous alignment surface. The LC layer initially presents twisted-azimuthal texture, which is capable of converting linear polarization to azimuthal (radial) polarization when the polarization direction of incident light is set parallel (perpendicular) to the homogenously aligned LC directors. If the LC molecules are tilted in an electric field, the tilted LC molecules will be realigned by the azimuthal alignment surface with deep rubbing grooves and present azimuthal texture, which can convert linear polarization to axial polarization. Additionally, increasing the voltage enables the LC molecules to reorientate along the electric field and lose converting effect, and such an operation can switch off the LCPC.
Comparison study of fluid thermal boundary-bulk behaviors in the close-to-critical region under different property trends
Authors: Zhang Rui , Chen Lin
Published: August 2023

The high-efficiency energy system based on the utilization of supercritical CO2 has been widely developed in recent years to meet the growing demands of clean energy and the elimination of CO2 emissions. Within this field, the design of the corresponding equipment requires an understanding of the thermodynamic behavior of supercritical fluid affected by the singular thermophysical properties. The analysis of this study is based on the asymptotic expansion of hydrodynamic equations and the thermophysical properties characterized by the exponential trends. The asymptotic model finds the wave and diffusion modes valid within the bulk region in second-order and within the boundary layer region (BLR) in first-order, respectively. Main findings include: (1) The wave mode is found in the bulk region with the wave celerity Γ. When the critical point is approached, Γ decreases from (γ0Mac0/κT0)0.5 = 1 to [(γ0–1)Mac0/κT0]0.5, which; (2) The diffusion mode found in BLR is characterized by non-dimensional diffusion coefficient ζ. This coefficient has the same behavior as thermal diffusivity, which is enlarged by thermal conductivity but weakened by isobaric specific heat. (3) Mass transport from BLR to bulk leads to the generation of the thermal wave, which can be measured by mass transport coefficient Mb=ζβp. Mb also characterizes the magnitude of the thermal wave as u2=Mb(Tb1)z|z=0 (that is, 0.17 mm/s when ϕ=10−4). The behavior of Mb is similar to one of ζ. However, the effect of cp is limited; (4) Two different modes of viscosity are identified. The increase in viscosity leads to the change of viscous stress mode from the second order to the first order, which also leads to a decrease in mass transport.
The dynamic response of floating offshore wind turbine platform in wave–current condition
Authors: Li Xiang , Xiao Qing , Wang Enhao , Peyrard Christophe , Gonçalves Rodolfo T.
Published: August 2023

In this paper, the fluid–structure interaction of floating offshore wind turbine (FOWT) platforms under complex ocean conditions is investigated using OpenFOAM and in-house developed models. Two types of FOWT platform, i.e., a semi-submersible platform and a barge platform, are studied for their dynamic responses to either wave or current. The results reveal that a semi-submersible platform exhibits larger cross-flow motion and lock-in phenomenon, while a barge platform experiences smaller motion with no significant lock-in within the velocity range examined. The combined wave–current conditions are further studied for the semi-submersible platform, with different angles between wave and current, the current speeds, and wave parameters. Unlike other investigations focusing on colinear wave–current interaction, in which the waves usually mitigate vortex-induced motion (VIM); here, we find that waves might lead to an enhanced VIM with a large angle between current and wave. The evaluation on the interaction effect factor shows that the largest wave height in the lock-in region does not lead to the most dangerous scenario, herein, the largest platform motion. Instead, a smaller wave height with a large wave period can induce even larger motion.
On the stability of a charged rotating liquid droplet in plasma
Authors: Sang Zhuo-Cheng , Miao Yang , Khrapak Sergey A. , Du Cheng-Ran
Published: August 2023

The instability condition of a charged liquid dust particle (droplet) immersed in a plasma is considered theoretically. Both charging process and rotation effect are incorporated in the model. The dependence of the critical charge on the droplet radius is obtained for the regimes of fast and slow fragmentation.
Assessment of deep levels with selenium concentration in Cd1–xZnxTe1–ySey room temperature detector materials
Authors: Kleppinger Joshua W. , Chaudhuri Sandeep K. , Nag Ritwik , Roy Utpal N. , James Ralph B. , Mandal Krishna C.
Published: August 2023

Incorporation of Se into Cd1−xZnxTe (CZT) to form the quaternary compound semiconductor Cd1−xZnxTe1–ySey (CZTS) has proven to be an effective solution for compensating the major flaws associated with CZT, including poor homogeneity and high concentrations of electronically active deep levels that limit the performance of CZT detectors. In order to investigate how deep levels are affected by the Se concentration in CZTS, we performed photoinduced current transient spectroscopy (PICTS) measurements on CZTS crystals grown by the traveling heater method (THM) with 10% atomic Zn and varying atomic percentage of Se from 1.5% to 7.0%. The PICTS scans for up to 4% Se showed an exponential reduction in the capture cross section of deep levels associated with Te secondary phases in conjunction with an increase in a deep level positioned near the mid-gap, which initially increases the electron trapping time before degrading again at higher Se concentrations. The PICTS peaks present in 7% Se were anomalous relative to the other crystals and are expected to originate from transition metal impurities found in the lower-purity CdSe precursor material.
On the robustness and accuracy of large-eddy simulation in predicting complex internal flow of a gas-turbine combustor
Authors: Qiao Zheng , Chen Yu , Wan Kaidi , Lv Yu
Published: August 2023

The objective of this study is to evaluate the effects of numerical and model setups on the large-eddy simulation (LES) predictive capability for the internal flow of a propulsion-relevant configuration. The specific focus is placed on assessing the LES technique with lower mesh resolutions, which is of technological relevance to practical industrial design. A set of Riemann flux formulations and commonly used subgrid-scale models are considered in this work to produce a hierarchy of LES setups with different dissipation effects (both numerically and physically). The LES results obtained from different setups are compared qualitatively in terms of the key flow characteristics and evaluated quantitatively against the experimental measurements. The error landscape is generated to reveal the predictive qualities of different LES setups. The study shows that the choice of numerical flux formulation plays a prominent role in governing the general flow patterns, while the effect of subgrid-scale model is mainly manifested in transient flow characteristics, such as vortex breakdown and swirl-induced vortical structures. Based on the error analysis, it is found that lower dissipative LES setup is not always beneficial to the LES accuracy. This is in contrast to the commonly accepted understanding in literature for the LES, which was established solely with canonical flow configurations.
Re-spreading behavior of droplet impact on superhydrophobic surfaces at low Weber numbers
Authors: Luo Jia , Chu Fuqiang , Zhang Jun , Wen Dongsheng
Published: August 2023

Despite extensive research on droplet impact behavior on superhydrophobic surfaces at high Weber numbers, there remains limited understanding of their dynamics at low Weber numbers, particularly during the retraction stage. In this study, we investigate the dynamic characteristics of droplet impact on superhydrophobic surfaces and reveal a unique re-spreading behavior during the retraction stage at smaller Weber numbers. A critical Weber number to trigger the re-spreading is identified as 4.9. A dimensionless analysis of the impact force, characterized by the dimensionless pressure, shows that the re-spreading phenomenon is the result of the competition between the inward motion driven by inertial effect and the outward expansion caused by the capillary oscillations on the contact line, which occurs only at low Weber numbers. Such a study offers insights into the dynamic characteristics of droplet impact on superhydrophobic surfaces at low Weber numbers and is of high implications for a number of related applications, such as trickle bed reactors and defrosting/deicing.
Direct thrust measurements of 2U-sized bi-directional wave plasma thruster
Authors: Shumeiko Andrei I. , Telekh Victor D.
Published: August 2023

The results of direct thrust measurements of the thruster with multiple thrust vectoring capability utilizing Kr are presented. The thruster is a 2U size system. The tested bi-directional plasma thruster consists of the thruster head, inbuilt rf generator creating 9 MHz current applied to the antenna, inbuilt power supply for the set of electromagnets, and thruster control system. The thruster head consists of the set of electromagnets, open-ended gas discharge chamber, and antenna. During thrust measurements, the magnitude and configuration of the external static magnetic field, the propellant flow rate, and the power modes of the rf generator are changed. The magnitude of the magnetic field in current units is adjusted in the range of 3…5 A. The propellant flow rate is adjusted in the range of 2…100 sccm. The power modes of the rf generator are adjusted in the range of 50…250 where the value 250 corresponds to a power of 100 W. The dynamic background pressure in the vacuum chamber is 0.1 Pa at 100 sccm. Two specific thrust modes are defined: the high thrust mode (∼7 mN) and the high specific impulse mode (∼900 s).
Wideband optical edge detection based on dielectric metasurface
Authors: Bi Xinyi , Guo Xuyue , Wu Xuanguang , Fan Xinhao , Wei Bingyan , Wen Dandan , Liu Sheng , Zhao Jianlin , Li Peng
Published: August 2023

Optical image edge detection manifests itself as the advantages of fast speed, low energy consumption, parallel operation, and large information capacity, playing a crucial role in object and image recognition in the realms of biology, medicine, and artificial intelligence. In this paper, a dielectric metasurface that can achieve object edge detection in the full visible band is proposed. By combining two optical differential methods referring to spatial spectrum-dependent transmission function and 4f system-based spatial spectrum phase shift, a tetratomic macropixel metasurface that enables polarization-correlated interference based on dual geometric phase modulation is designed, which can achieve object edge detection under 473, 530, and 633 nm wavelengths, and even under white light conditions. This coherent filtering metasurface operator provides a flexible approach for achieving wideband two-dimensional edge detection.
Study of micro-scale flow characteristics under surface acoustic waves
Authors: Zhao Siyu , Liu Zhaomiao , Ren Yanlin , Zheng Nan , Chen Rui , Cai Fanming , Pang Yan
Published: August 2023

As an effective tool for contactless manipulation of submicrometer scale objects, the controllability of acoustic streaming velocity and flow field morphology determines the accuracy of object migration and the completeness of three dimensional (3D) imaging. This paper proposes an equivalent acoustic streaming driving force model that is applicable to both two dimensional (2D) and 3D calculations and constructs a numerical method for submicrometer microsphere migration and rotation velocity in acoustic streaming. The results show that the relationship between the peripheral vortex size Lp/wc and the relative acoustic streaming velocity vas/vf satisfies Lp/wc = 0.125vas/vf0.36 under certain geometrical conditions. Reducing the spatial confinement and increasing the inter-vortex distance will increase the energy release efficiency, reduce the pressure gradient distribution and convective dissipation rates, increase the vortex intensity and radiation range, and consequently, increase the vortex characteristic size. In complex 3D vortex flow fields, suspended objects are affected by velocity distributions and exhibit motions such as cross-flow lines and rotation. For larger vortex structure sizes, full 3D imaging is more favorable due to the increased rotation speed and period of motion along the orbit of the submicrometer microspheres. This study helps us to reveal the modulation mechanism of acoustic streaming field flow characteristics, enrich the basic theory of alternating orbital motion and forces on objects in vortex structures, and provide guidance for acoustic flow-based contactless object manipulation.
Effects of blockage ratio on the propagation characteristics of hydrogen-rich gas rotating detonation
Authors: Qiu Han , Bai Qiaodong , Han Jiaxiang , Zhang Shijian , Weng Chunsheng
Published: August 2023

The propagation characteristics of a hydrogen-rich gas/air rotating detonation wave (RDW) were investigated for different blockage ratios (BRs). Two rotating detonation chamber (RDC) widths were used in combination with different RDC exit widths to obtain different RDC BRs. The variations in the RDW propagation modes and wave velocities at different BRs and equivalence ratios (ERs) were studied and analyzed. The experimental results show that four types of RDW propagation modes can be obtained (single wave, single wave/counter-double waves hybrid mode, triple waves, and unstable triple waves) by changing the BRs and ERs. For BR > 0.64, the RDW exhibits a triple waves mode. The RDC width also affects the RDW propagation mode. The results show that at low BRs, the change in the RDW propagation mode owing to the injection pressure difference is the main influence mechanism. As the BR increases, the influence of the reflected shock wave from the exit of the RDC increases, which plays an important role in the generation of the triple waves mode. The stability of RDW propagation can be improved by appropriately increasing the blockage ratio in the RDC. The 26 mm RDC width at BR = 0 results in a maximum wave velocity of 1933.8 m/s. Moreover, the stability of the RDW propagation is poor at low and high BRs.
Voltage-controlled magnetic anisotropy based physical unclonable function
Authors: Meo Andrea , Garzón Esteban , De Rose Raffaele , Finocchio Giovanni , Lanuzza Marco , Carpentieri Mario
Published: August 2023

We design a spintronic physical unclonable function (PUF) based on sub-100 nm voltage-controlled magnetic anisotropy hybrid magnetic tunnel junctions (VCMA-MTJs). This complementary metal-oxide-semiconductor VCMA-MTJ (CMOS/VCMA-MTJ) PUF architecture was evaluated by combining micromagnetic simulations, Verilog-A modeling, and circuit-level simulations. The PUF architecture, comprising four 16 rows × 16 columns arrays, demonstrates effective read and write operations using conventional voltage sensing that are orders of magnitudes lower than previous spintronic-based PUFs. This study proves the potential of the proposed solution in security applications based on hardware authentication.
Cold-water pollution impacts on two ‘warm-water’ riverine fish: interactions of dam size and life-history requirements
Authors: Koehn John D. , Todd Charles R. , Wootton Henry
Published: August 2023

Context Temperature regulates most ecological processes in freshwater ecosystems. Anthropogenic changes to natural thermal regimes, especially cold water released from stratified impoundments (cold-water pollution, CWP), is a widespread and major threat to fish populations globally. Aims Because mitigation options for CWP are often expensive, we aimed to provide robust ecological evidence to inform expenditure. Methods We modelled population responses to CWP remediation for two warm-water fish species (Murray cod and golden perch) downstream of two impoundments (Copeton and Pindari dams) in the semi-arid northern Murray–Darling Basin, Australia. Key results Predicted populations of both species were severely affected by CWP at both sites; however, impacts were species- and site-specific. Effects were greater on golden perch than Murray cod because of their higher temperature requirements for spawning. Predicted spawning opportunities decreased by 77–100% for golden perch and by 38–92% for Murray cod. The larger Copeton Dam had greater impacts than did the smaller Pindari Dam. Conclusions Remediation of CWP can help restore populations and meeting the needs of golden perch may benefit a range of other species. Implications Globally, CWP is a serious threat to warm-water fishes that may compromise and even nullify other restoration efforts. However, restoration may be impeded by current low abundances, angler harvest and restrictions to fish passage.
An illusion of predictability in scientific results: Even experts confuse inferential uncertainty and outcome variability
Authors: Zhang Sam , Heck Patrick R. , Meyer Michelle N. , Chabris Christopher F. , Goldstein Daniel G. , Hofman Jake M.
Published: August 2023

Traditionally, scientists have placed more emphasis on communicating inferential uncertainty (i.e., the precision of statistical estimates) compared to outcome variability (i.e., the predictability of individual outcomes). Here, we show that this can lead to sizable misperceptions about the implications of scientific results. Specifically, we present three preregistered, randomized experiments where participants saw the same scientific findings visualized as showing only inferential uncertainty, only outcome variability, or both and answered questions about the size and importance of findings they were shown. Our results, composed of responses from medical professionals, professional data scientists, and tenure-track faculty, show that the prevalent form of visualizing only inferential uncertainty can lead to significant overestimates of treatment effects, even among highly trained experts. In contrast, we find that depicting both inferential uncertainty and outcome variability leads to more accurate perceptions of results while appearing to leave other subjective impressions of the results unchanged, on average.
Determining Riemannian manifolds from nonlinear wave observations at a single point
Authors: Tzou Leo
Published: August 2023

We show that on an a-priori unknown Riemannian manifold (M, g), measuring the source-to-solution map for the semilinear wave equation at a single point determines its topological, differential, and geometric structure.
Positive Jacobian constraints for elliptic boundary value problems with piecewise-regular coefficients arising from multi-wave inverse problems
Authors: Capdeboscq Yves , Dai Tianrui
Published: August 2023

Multi-wave inverse problems are indirect imaging methods using the interaction of two different imaging modalities. One brings spatial accuracy, and the other contrast sensitivity. The inversion method typically involve two steps. The first step is devoted to accessing internal datum of quantities related to the unknown parameters being observed. The second step involves recovering the parameters themselves from the internal data. To perform that inversion, a typical requirement is that the Jacobian of fields involved does not vanish. A number of authors have considered this problem in the past two decades, and a variety of methods have been developed. Existing techniques require Hölder continuity of the parameters to be reconstructed. In practical applications, the medium may present embedded elements, with distinct physical properties, leading to discontinuous coefficients. In this article we explain how a Jacobian constraint can be imposed in the piecewise regular case, when the physical model is a divergence form second order linear elliptic boundary value problem.
Experimental study on acoustic-induced microbubbles fusion
Authors: Jin Shaobo , Cao Na , Ye Guoyong , Wang Pengpeng , Dong Shizhang , Liu Zenghao
Published: August 2023

Droplets/microbubbles fusion technology is a key technology for many biochemical medical applications. Here, an acoustic-controlled approach to drive microbubble fusion based on focused surface acoustic wave (FSAW) is presented. When passing through the arc-shaped channel, adjacent microbubbles will decelerate, contact, and fuse induced by the FSAWs. Due to the cooperation of the FSAW and the arc-shaped flow channel structure, the microbubbles are more easily captured and fused with the adjacent microbubbles. The effects of input voltage and pressure input parameters on the microbubble fusion are studied. Relying on electrical input parameters, microbubble fusion can be effectively achieved, providing a new idea for precise gas fuse control. The regulation of the microbubbles fusion by FSAW is revealed, showing potential in the applications of the precise control of gases on a microfluidic chip.
Bottom-up micromachined PZT film-based ultrasonic microphone with compressible parylene tube
Authors: Huang Chung-Hao , Feng Guo-Hua
Published: August 2023

This paper reports on a micromachined ultrasonic microphone using a bottom-up fabrication scheme. Starting with a 4 μm-thick titanium foil as the substrate, each functional film and key element was added to the foil substrate to complete the ultrasonic microphone. The piezoelectric lead zirconate titanate film hydrothermally grown on the patterned substrate with low residual stress effectively deflected the unimorph-sensing cantilever array of the microphone under ultrasound pressure. The created cantilever array structure secured on a 250 μm-thick SU8 hollow plate formed an ultrasonic microphone plate that was tested with a sensitivity of −60 dBV Pa−1 at 21 kHz (with 0 dB gain amplification) and an operation bandwidth of 5–55 kHz. Different thicknesses of parylene films ranging from 0.5 to 2 μm overlaid over the entire sensing region and converted the cantilever-to-diaphragm-structured microphone for further investigation. An enhanced result was observed when the deposited parylene film thickness was in the submicron range. The sensitivity of the microphone can be further enhanced by up to 33% by adding a parylene-film-made compressible tube to act as a Helmholtz resonator (HR). The HR model was discussed and compared with the experimental results. The output amplitude of the developed microphone assembled with the compressible tube demonstrates a 15 dB increase compared to that of a commercial capacitive MEMS ultrasonic microphone.
Tunable Rydberg–Rydberg transitions in helium with reduced sensitivity to dc electric fields by two-colour microwave dressing
Authors: Brown L L , Hogan S D
Published: August 2023

The difference in the static electric dipole polarizabilities of the

1

s

55

s

3

S

1

and

1

s

56

s

3

S

1

Rydberg levels in helium has been eliminated by dressing the atom with a microwave field near resonant with the single-photon

1

s

55

s

3

S

1

→
1

s

55

p

3

P

J

transition. For an

2.82

m
V

c
m

−
1

amplitude dressing field, detuned by

2
π
×
10

M
H
z

from the zero-field

1

s

55

s

3

S

1

→
1

s

55

p

3

P

2

transition frequency, the dc Stark shift of the two-photon

1

s

55

s

3

S

1

→
1

s

56

s

3

S

1

transition between these states remained within

±
15

k
H
z

for electric fields up to

∼

60

m
V

c
m

−
1

. This transition was probed by single-color two-photon microwave spectroscopy, and by two-color two-photon spectroscopy with one strong additional dressing field and a weak probe field. For all measurements, the transition frequencies and Stark shifts were compared, and found to be in excellent quantitative agreement with the results of Floquet calculations of the energy-level structure of the Rydberg states in the presence of the dressing fields and applied dc electric fields. The two-color microwave dressing scheme demonstrated, with one field applied to null the differential polarizability of the Rydberg–Rydberg transition, and the second exploited to allow the two-photon transition to be employed to achieve tunable absorption of single-photons from a weak probe field, will facilitate improved coherence times and tunable single-photon absorption in hybrid cavity QED experiments with Rydberg atoms and superconducting microwave circuits.
Surface modification of aramid fiber by cascade process with atmospheric plasma and TDI grafting
Authors: Du Yijun , Chen Shuo , Li Peng , Deng Yu , Chen Weijiang , Zhou Jun , Gu Chen
Published: August 2023

Aramid fiber (AF)/epoxy composites are often used as mechanical and insulating materials for ultra-high voltage gas-insulated switchgear (GIS) insulation pull rods. However, the product performance is believed to be restricted by the poor adhesion between AF and the resin matrix, affecting the operation reliability of GIS. In this work, a cascade process was applied to modify the AF surface to improve interfacial behavior. The AF was first treated with air dielectric barrier discharge at atmospheric pressure to obtain a rough surface and then reacted with toluene-2,4-diisocyanate (TDI) to introduce polar functional groups onto the surface. The plasma discharge power and treatment time were investigated as major parameters, and the aging effect was studied. The modified AF was characterized by scanning electron microscope, Fourier transform infrared spectrometer, x-ray photoelectron spectroscopy, atomic force microscope, and filament yarn tensile test. The interfacial behavior of the AF/epoxy composite was analyzed by interfacial shear strength (IFSS) test of micro-bond specimen and interlaminar shear strength (ILSS) test of Naval Ordnance Laboratory rings. Experimental results showed that polar functional groups were introduced onto the AF surface. The IFSS and ILSS of AF/epoxy composite were increased by 32.8% and 20.2% at most, respectively, and the tensile strength of the AF was mostly preserved. Moreover, with the increase in plasma discharge power, the interfacial strength of the modified AF/epoxy interface increased firstly and then decreased. The AF modified by TDI retained a relatively good modification effect after aging for some time. This study presents a cascade process for the AF surface modification with simplicity, effectiveness, and resource-saving, which is suitable for industrial applications.
Direct current arc quenching performance of a model electric fuse equipped with SiO2 sand and additive silicone resin as an arc quenching medium: the effect of a vaporized silicone decomposition mixture on transient arc resistance
Authors: Takenaka W , Kodama N , Yokomizu Y , Nakamura K , Shimizu H
Published: August 2023

Most high-power electric fuses installed in DC distributions of automobiles employ silica sand (chemical formula SiO2) as arc quenching material to implement the limitation and subsequent interruption of high direct currents. This paper on arc quenching material describes the effects of the addition of silicone resin (chemical formula C2H6SiO) on SiO2 sand, based on the resistance of an arc discharge in SiO2 vapor mixed with silicone resin vapor. The measurement results obtained for the fuse operation of a model electric fuse show that the addition of silicone resin, e.g. an even coating of silicone resin on the surface of a Cu fuse element, attains a shorter arc quenching time. This phenomenon is subsequently explained based on the rise effect of an arc column resistance achieved by mixing with silicone vapor decomposition. The chemical compositions of high-temperature SiO2 vapor mixed with C2H6SiO vapor decomposition are evaluated to show the predominant chemical species at 30 000 K–5000 K for several C2H6SiO vapor concentrations,

X

C
H

. The results obtained for

X

C
H

of 10%–50% reveal that a H atom originating from C2H6SiO is present at high molar fractions above 0.1 over a wide temperature range of 12 000 K–5000 K. Further evaluations of the electrical resistivity

ρ

R

for the high-temperature vapor show that mixing with C2H6SiO vapor contributes to a rise in

ρ

R

at temperatures of 10 000 K–6000 K. A contribution analysis of the

ρ

R

reveals that the rise effect of the

ρ

R

is accomplished chiefly by the presence of a H atom that has dissociated from C2H6SiO.
P-doped porous carbon from camellia shell for high-performance room temperature sodium–sulfur batteries
Authors: Peng Xiangqi , Tang Kejian , Zhang Ziying , Hu Jian , Li Guohao , Wang Jie , Xie Xiuqiang , Zhang Nan , Wu Zhenjun
Published: August 2023

Room-temperature sodium–sulfur batteries are still hampered by severe shuttle effects and sluggish kinetics. Most of the sulfur hosts require high cost and complex synthesis process. Herein, a facile method is proposed to prepare a phosphorous doped porous carbon (CSBP) with abundant defect sites from camellia shell by oxidation pretreatment combined with H3PO4 activation. The pretreatment can introduce pores and adjust the structure of biochar precursor, which facilitates the further activation of H3PO4 and effectively avoids the occurrence of large agglomeration. Profiting from the synergistic effects of physical confinement and doping effect, the prepared CSBP/S cathode delivers a high reversible capacity of 804 mAh g−1 after 100 cycles at 0.1 C and still maintains an outstanding capacity of 458 mAh g−1 after 500 cycles at 0.5 C (1 C = 1675 mA g−1). This work provides new insights into the rational design of the microstructures of carbon hosts for high-performance room temperature sodium–sulfur batteries.
Eco-friendly triboelectric nanogenerator based on degradable rape straw powder for monitoring human movement
Authors: Wang Xiucai , Hu Naijian , Yang Jia , Lin Rongkui , Chen Jianwen , Yu Xinmei , Zhu Wenbo , Zhang Minggao , Wang Ting
Published: August 2023

Green energy from the surrounding environment has great potential for reducing environmental pollution and sustainable development. Triboelectric nanogenerators (TENGs) are of great interest as they can easily harvest mechanical energy from the environment. Here, we present a triboelectric nanogenerator (RS-TENG) based on rape straw (RS), which was developed from a film composed of waste RS and polyvinyl alcohol (PVA). Due to the high content of carbonyl, hydroxyl and amino acid functional groups in RS, the ability of RS/PVA to lose electrons is increased. The proposed RS-TENG device with a size of 6.25 cm2 exhibits open circuit voltage (78 V), short circuit current (5.3 μA) performance under uniform external stress at a frequency of 3.5 Hz and 10 N in the cylinder motor. 104.5 μW was obtained with a load resistance of 25 MΩ. Results obtained from degradability tests revealed that the RS/PVA film was able to degrade over a period of 30 d (In PBS solution). The RS-TENG produces a significantly high current signal under conditions of finger bending, elbow movements, and foot tapping. Practical tests of the RS-TENG have shown that it is a promising sensing device that will be widely used in the future.
Validity and reliability of a commercial wearable sensor system for measuring spatiotemporal gait parameters in a post-stroke population: the effects of walking speed and asymmetry
Authors: Lanotte Francesco , Shin Sung Yul , O’Brien Megan K , Jayaraman Arun
Published: August 2023

Objective.Commercial wearable sensor systems are a promising alternative to costly laboratory equipment for clinical gait evaluation, but their accuracy for individuals with gait impairments is not well established. Therefore, we investigated the validity and reliability of the APDM Opal wearable sensor system to measure spatiotemporal gait parameters for healthy controls and individuals with chronic stroke.Approach.Participants completed the 10 m walk test over an instrumented mat three times in different speed conditions. We compared performance of Opal sensors to the mat across different walking speeds and levels of step length asymmetry in the two populations.Main results. Gait speed and stride length measures achieved excellent reliability, though they were systematically underestimated by 0.11 m s−1and 0.12 m, respectively. The stride and step time measures also achieved excellent reliability, with no significant errors (median absolute percentage error <6.00%,p> 0.05). Gait phase duration measures achieved moderate-to-excellent reliability, with relative errors ranging from 4.13%–21.59%. Across gait parameters, the relative error decreased by 0.57%–9.66% when walking faster than 1.30 m s−1; similar reductions occurred for step length symmetry indices lower than 0.10.Significance. This study supports the general use of Opal wearable sensors to obtain quantitative measures of post-stroke gait impairment. These measures should be interpreted cautiously for individuals with moderate-severe asymmetry or walking speeds slower than 0.80 m s−1.
On CO2 conversion in discharges in CO2–N2 mixtures
Authors: Babaeva N Yu , Naidis G V , Popov N A
Published: August 2023

Recent results on the efficiency of CO2 conversion in discharges in CO2–N2 mixtures are discussed. Conditions are considered when the dominating conversion mechanism is dissociation of CO2 molecules in collisions with nitrogen molecules in several electronically excited states. Its efficiency is determined by the values of dissociation yields in these collisions. Knowledge of dissociation yields for various N2 excited states is rather poor. In this paper, the effects of variation of these yields on the conversion efficiency are evaluated. Comparison of the obtained estimates with available experimental data allows ascertaining the yield values.
Particle simulation on the ion acceleration in vacuum arc discharge
Authors: Song Mengmeng , Zhou Qianhong , Yang Wei , Sun Qiang , Dong Ye , Zhang Hantian , Wang Ziming
Published: August 2023

The supersonic ion jet generated in vacuum arc plasma has numerous applications, but the ion acceleration mechanism is incompletely understood. In this paper, a one-dimensional spherical vacuum arc discharge model is established, and the ion acceleration from vacuum breakdown to steady arc stage is investigated using particle-in-cell direct simulation Monte Carlo method. The results show that a potential hump exists and locates about

1
μ

m

far away from the cathode, but the potential drop provides a small contribution to the ion acceleration. A potential valley forms near the plasma–vacuum boundary and propagates towards the anode as the plasma expands during the vacuum breakdown stage. The ion mounting this valley experiences continuous acceleration by the dynamic electric field of the potential valley. As the plasma reaches the anode, a steady arc stage is gradually build-up, and the potential valley disappears. Consequently, the maximum mean ion velocity decreases. The source dominating the ion acceleration in this stage is turned into the electron–ion Coulomb collision.
LiDB: Database of molecular radiative lifetimes for plasma processes
Authors: Owens Alec , He Tiantian , Hanicinec Martin , Hill Christian , Mohr Sebastian , Tennyson Jonathan
Published: August 2023

LiDB is a newly developed database of molecular vibrational and vibronic state radiative lifetimes. It has been created with the aim of enabling radiative effects to be properly captured in low-temperature plasma models. Datasets have been generated for 36 molecules using comprehensive and highly accurate molecular line lists from the ExoMol spectroscopic database. The main data output of LiDB is radiative lifetimes at vibrational state resolution. Partial lifetimes, which give information on the dominant decay channels in a molecule, are also provided. LiDB is freely available to the scientific community and is hosted at www.exomol.com/lidb. Users can dynamically view molecular datasets or use a specially-designed application programming interface to make data requests. LiDB will continue to expand in the future by adding more molecules, important isotopologues, and neutral and singly-charged atomic species.
Evaluation of insulating behavior by Pb substitution and pressure-induced superconductivity in La2O2Bi3−
x
Pb1+
x
S6
Authors: Jha Rajveer , Jaroslav Valenta , Tsujii Naohito , Naka Takashi , Kawahata Takeshi , Kawashima Chiduru , Takahashi Hiroki , Mori Takao , Mizuguchi Yoshikazu
Published: August 2023

We report synthesis, characterization, and physical properties of layered bismuth-sulfide compounds La2O2Bi3−x
Pb1+x
S6. We synthesized a new La2O2Bi3PbS6 compound, whose crystal structure is similar to those of the La2O2Bi3AgS6 superconductor or La2O2Bi2Pb2S6 (insulator) with a four-layer-type conducting layer. The crystal structure of La2O2Bi3PbS6 is characterized in a tetragonal P4/nmm space group, and the lattice parameters are a = 4.084(1) Å and c = 19.71(2) Å. The obtained La2O2Bi3PbS6 sample exhibits narrow gap semiconductor (metallic-like) transport behavior with an anomaly near the 160 K. A metallic-like to insulator transition has been observed through Pb substitution, with increasing x in La2O2Bi3−x
Pb1+x
S6. Furthermore, we applied external pressure for x = 0 and observed pressure-induced superconductivity. The onset of superconductivity appeared at 0.93 GPa, and the highest transition temperature was 3.1 K at 2.21 GPa.