bluuebunny/crossref_metadata_2025 huggingface dataset:
Optical regulation by localized states of Cu2+ ions with highly sensitive to trap density and thermalization in manganese-doped perovskite nanocrystals
Authors: Zhang Wenxia , Zeng Fujia , Wang Yuchan , Wu Daofu , Chen Guanghao , Wang Zhen , Niu Xianghong , Tang Xiaosheng
Published: February 2024

Mn2+-doped perovskites nanocrystals (NCs) have already been extensively studied in fascinating optical, electronic, and magnetic properties. Such interesting traits make them paid considerable attention in light emitting diodes, solar cells, etc. However, the underlying thermal and photophysical processes governing the overall charge carrier dynamics in Mn-doped NCs are far from clear. Herein, trap concentration and thermalization-dependent optical properties of Mn–Cu co-doped CsPbCl3 NCs were investigated via using steady-state, time-resolved PL spectra, variable-temperature PL spectra, and ultrafast transient absorption spectra. The combined experimental and theoretical studies reveal that Cu2+, as an effective hole trap, can trap the holes from Mn2+ and emit the holes to Mn2+ level at lighter and higher doping, respectively. Moreover, this hole trap is highly thermally sensitive, which is responsible for the abnormal thermal effect of Mn2+ emission with increasing temperature. These findings demonstrate an approach of charge regulation through ion doping, which is meaningful for fabricating efficient photoelectric materials and devices.
A novel ultrasonic method for measuring minute sinusoidal displacement by network analyzer
Authors: Komatsu Yuya , Mori Shohei , Arakawa Mototaka , Kanai Hiroshi
Published: February 2024

We developed a method for generating continuous sinusoidal displacements of an object to estimate viscoelastic parameters. However, the amplitude of the displacement caused by the ultrasonic excitation force under safe guidelines was small (a few micrometers), and it was difficult to stably measure the displacement. Therefore, to stably measure the amplitude of sinusoidal displacement as small as the order of micrometers, we proposed a novel method using a network analyzer. Ultrasonic waves were irradiated using an ultrasonic transducer to an object vibrating sinusoidally. The S parameter of the first reflected wave received from the surface of the object was measured using a network analyzer. The S parameter and the inverse Fourier transform were formulated theoretically, and the amplitude of the sinusoidal displacement of the object was estimated from the amplitude characteristics of the inverse Fourier-transformed signal. The proposed method was applied to measure sinusoidal displacements on the order of micrometers from 10 to 300 Hz on an object using a water tank experiment. The obtained sinusoidal displacement agreed well with the reference values measured using a laser displacement meter. The proposed method can accurately measure minute sinusoidal displacements that occur on an object.
A method for measuring soil water content based on principal component analysis
Authors: Chai Jin , Ling Zhenbao , Wang Yi , Dong Ran , Zheng Yuhao , Qi Jiangtao
Published: February 2024

Principal component analysis (PCA) has been applied in many aspects. To address the problem of measuring water content in soil, this paper proposes a method to measure soil water content based on the PCA. We used PCA to reduce the dimension of the data and processed the soil amplitude ratio frequency response spectra. First, we designed the measuring device and measured the soil amplitude ratio frequency response data of different water content, then we used the PCA to extract features from the frequency response spectra of different water contents, established a relationship model of soil water content, and finally, we solved the model, the maximum error between the calculation results and the actual water content was no more than 0.85%. Subsequently, we carried out experimental verification, and we measured six kinds of soil with known water content by this method. The experimental results showed that the maximum error did not exceed 1.16%, and the average error was 0.71%. Thus, the proposed method can provide a useful way of measuring soil water content.
Asymmetric flapping of a multi-segmented elastic structure
Authors: Song Minho , Yoo Janggon , Kim Daegyoum
Published: February 2024

Motivated by the propulsion of animals using articulated bodies, this study experimentally investigates the deformation and torque generation of a multi-segmented structure undergoing flapping motion. The segmented structure consists of multiple rigid segments connected in a line through elastic sheets functioning as elastic hinges. To enhance the asymmetry in the deflection of the segmented structure between the power and recovery strokes, the elastic hinges are designed to bend only one way from their original position. To characterize the deflection profile of the segmented structure, new definitions are proposed for the effective bending stiffness of the entire structure and the dimensionless speed representing the relative magnitude of the fluid force acting on the structure to its internal bending force. These two quantities are used to determine the tip deflection adjusted by the discrete profile. Two typical deflection responses during the recovery stroke are identified, namely, an in-phase response and a delayed response. The difference in these deflection responses causes substantial changes in torque and thrust generation, particularly during the early stage of the subsequent power stroke. An evaluation of the torque and thrust generation performance, in terms of the net cyclic value and the degree of asymmetry between the two strokes, reveals the optimal model design and operation conditions of the segmented structure.
Record peak current density of over 1500 kA/cm2 in highly scaled AlN/GaN double-barrier resonant tunneling diodes on free-standing GaN substrates
Authors: Liu Fang , Xue JunShuai , Yao JiaJia , Wu GuanLin , Li ZuMao , Liu RenJie , Guo Zhuang , Zhang Kai , Zhang JinCheng , Hao Yue
Published: February 2024

This work demonstrates high-performance AlN/GaN double-barrier resonant tunneling diodes (RTDs) with high peak current density grown by plasma-assisted molecular beam epitaxy on c-plane free-standing GaN substrates, featuring stable and repeatable negative differential resistance (NDR) characteristics at room temperature. By scaling down the barrier thickness of AlN barrier and the lateral mesa size of collector, the record peak current density of 1551 kA/cm2 is achieved along with a peak-to-valley current ratio (PVCR) of 1.24, which is attributed to the reduced resonant tunneling time under thinner AlN barrier and the suppressed external incoherent valley current by reducing the dislocation number contained in the RTD device with the smaller size of collector. By statistically analyzing the NDR performance of RTD devices with different thicknesses of AlN barrier, the average peak current density increases from 145.7 to 1215.1 kA/cm2, while the average PVCR decreases from 1.45 to 1.1, correspondingly, accompanying with a decreased peak voltage from 6.89 to 5.49 V, with downscaling the AlN barrier thickness from 1.5 to 1.25 nm. The peak current density obtained in this work is the highest value among all the reported nitride-based RTDs up until now while maintaining high PVCR value simultaneously, which illustrates that ultra-scaled RTD based on vertical quantum-well structure and lateral collector size is a valuable approach for the development of nitride-based RTDs with excellent NDR characteristics and reveals their great potential applications in high-frequency oscillation sources and high-speed switch circuits.
FP3D: A code for calculating 3D magnetic field and particle motion
Authors: Jiang P. Y. , Feng Z. C. , Yu G. D. , Fu G. Y.
Published: February 2024

An efficient numerical code FP3D has been developed to calculate particle orbits and evaluate particle confinement in 3D magnetic fields including stellarators and tokamaks with 3D fields. The magnetic field is either calculated from coils directly or obtained from equilibrium codes. FP3D has been verified with the 3D equilibrium code Variational Moments Equilibrium Code [Hirshman and Whitson, Phys. Fluids 26, 3553–3568 (1983)] for magnetic field calculation and with the drift-kinetic code Stellarator Fokker–Planck Iterative Neoclassical Conservative Solver [Landreman et al., Phys. Plasmas 21(4), 042503 (2014)] for neoclassical transport. The code has been applied successfully to the National Compact Stellarator Experiment stellarator [Nelson et al., Fusion Eng. Des. 66, 169–174 (2003)] for the calculation of neoclassical transport coefficient with the 3D magnetic field obtained directly from coils. FP3D is also used to calculate ripple losses in the tokamak Experimental Advanced Superconducting Tokamak [Y. Wan, Plasma Sci. Technol. 8(3) (2006)].
Two-step growth of alumina nanoparticle decorated graphene oxide surfaces: Effect on photocatalytic activity
Authors: Verma Shankee , Santra Bisweswar , Chattaraj Ananya , Samanta Atanu , Chowdhury Suman , Srivastava Sachin , Sagdeo Archna , Kanjilal Aloke , Katharria Yashpal S.
Published: February 2024

As water pollution is increasing due to industrialization, there is a high demand for easy-processing photocatalytic materials to clean wastewater. Here, the improvement in the photocatalytic dye degradation effect of graphene oxide (GO) surfaces, made of ultra-sonication assisted modified Hummer's method, is demonstrated with increasing alumina (Al2O3) concentration in the range of 4–30 wt. %. Scanning electron microscopy and x-ray diffraction results suggest a gradual increment in crystalline Al2O3 nanoparticles (NPs) by reducing GO, in good agreement with the first-principles calculations. Moreover, x-ray photoelectron spectroscopy reveals the appearance of oxygenated functional groups with increasing Al2O3 concentration, leading to the formation of defect-rich GO as demonstrated by Raman spectroscopy. Ultraviolet-visible spectroscopy further reflects a maximum reduction in the optical bandgap from 1.88 to 1.56 eV up to a concentration of 15 wt. % Al2O3. Interestingly, the methylene blue degradation efficiency of GO under ultraviolet irradiation is also found to be improved from 45% to 64% with 15 wt. % Al2O3, whereas the formation of Al2O3 NPs in the range of 100–300 nm with 30 wt. % Al2O3 is found to be detrimental for photocatalytic activity.
Suppressing substrate oxidation during plasma-enhanced atomic layer deposition on semiconductor surfaces
Authors: Bienek Oliver , Rieth Tim , Kühne Julius , Fuchs Benedikt , Kuhl Matthias , Wagner Laura I. , Todenhagen Lina M. , Wolz Lukas , Henning Alex , Sharp Ian D.
Published: February 2024

Plasma-enhanced atomic layer deposition (PE-ALD) is widely employed in microelectronics, energy, and sensing applications. Typically, PE-ALD processes for metal oxides utilize remote inductively coupled plasmas operated at powers of >200 W, ensuring a sufficient flux of oxygen radicals to the growth surface. However, this approach often leads to significant oxidation of chemically sensitive substrates, including most technological semiconductors. Here, we demonstrate that plasma powers as low as 5 W can effectively suppress substrate oxidation while maintaining the structural, optical, and electronic quality of the films. Specifically, we investigate the growth of titanium oxide (TiOx) using two commonly used metalorganic precursors, titanium isopropoxide and tetrakis(dimethylamino)titanium. Films deposited with 5 and 300 W oxygen plasma power are nearly indiscernible from one another, exhibiting significantly lower defect concentrations than those obtained from thermal ALD with H2O. The low plasma power process preserves desired physical characteristics of PE-ALD films, including large optical constants (n > 2.45 at 589 nm), negligible defect-induced sub-bandgap optical absorption (α < 102 cm−1), and high electrical resistivity (>105 Ω cm). Similar behavior, including suppressed interface oxidation and low defect content, is observed on both Si and InP substrates. As an example application of this approach, the assessment of InP/TiOx photocathodes and Si/TiOx photoanodes reveals a significant improvement in the photocurrent onset potential in both cases, enabled by suppressed substrate oxidation during low power PE-ALD. Overall, low power PE-ALD represents a generally applicable strategy for producing high quality metal oxide thin films while minimizing detrimental substrate reactions.
On the dynamics of the turbulent flow past a three-element wing
Authors: Montalà R. , Lehmkuhl O. , Rodriguez I.
Published: February 2024

A comprehensive analysis of the unsteady flow dynamics past the 30P30N three-element high lift wing is performed by means of large eddy simulations at different angles of attack (α = 5°, 9°, and 23°) and at a Reynolds number of Rec=750 000 (based on the nested chord). Results are compared with experimental and numerical investigations, showing a quantitatively good agreement and, thus, proving the reliability and accuracy of the present simulations. Within the slat and main coves, large recirculation bubbles are bounded by shear layers, where the onset of turbulence is triggered by Kelvin–Helmholtz instabilities. In the energy spectrum of the velocity fluctuations, the footprint of these instabilities is detected as a broadband peak; its frequency being moved toward lower values as the angle of attack increases. Kelvin–Helmholtz vortices roll-up and break down into small scales that eventually impinge into the slat and main coves lower surfaces. The slat impingement shows to be more prominent, and hence, larger velocity and pressure fluctuations are observed. The impingement strength diminishes with the angle of attack in both coves, while higher fluctuations are originated on the slat and main respective suction sides, leading to larger boundary layers. This is associated with the displacement of the stagnation point with the angle of attack. Another salient feature observed is the laminar-to-turbulent flow transition in the main and flap leading edges although the average location of this transition seems to not be affected by the angle of attack. Tollmien–Schlichting instabilities precede this transition, with the disturbances amplified by the inviscid mode at low angles of attack, while at α=23°, the local Reynolds number on the main suction side is incremented and the viscous mode becomes important. The analysis shows that the turbulent wake formed at the trailing edge of all elements dominates the dynamics downstream. This is especially true at the higher angle of attack, where a large region of velocity deficit above the flap is observed, thus indicating the onset of stall conditions.
Determination of in-plane surface directions in scanning probe microscopy images
Authors: Kyeyune Bob , Olbrich Reinhard , Rahe Philipp , Reichling Michael
Published: February 2024

We describe an approach to determine the in-plane crystallographic surface directions in scanning probe microscopy (SPM) images. This method is based on a one-time characterization of the SPM instrument with an appropriate test sample and is exemplified by the analysis of non-contact atomic force microscopy (NC-AFM) images on surfaces whose natural cleavage occurs along {111} planes. We introduce a two-dimensional rotation matrix relating the crystallographic surface directions known from an analysis of the macroscopic crystal to the directions in the NC-AFM images. The procedure takes into account rotations and mirror axes resulting from sample mounting, the SPM scanner rotation, the choice of scan direction, as well as data processing, storage, and display. We demonstrate the practicability of the approach by determining the [112̄] direction in topographic images of a CeO2(111) film grown on a Si(111) wafer and atomic resolution images of CaF2(111) with an instrument based on the beetle-type scanner.
Direct numerical simulation of oblique-wave transition in concave boundary layer
Authors: Wang Ying , Zhou Teng , Yan Chao , Shen Qing
Published: February 2024

Investigation of transition in a concave boundary layer is conducted via three-dimensional direct numerical simulation at Mach 3. The model consists of a flat plate and a concave plate, connected smoothly. The development of the boundary layer in the unperturbed flow is computed initially. It is found that the boundary layer thickness rapidly increases due to the separation bubble, caused by an adverse pressure gradient. Subsequently, spanwise vortices are generated by the Kelvin–Helmholtz instability, which develops within the strong shear layer. Then, a pair of oblique waves is introduced at the inlet of the computational domain through suction and blowing slot to examine the impact of oblique waves on transition and separation of the concave plate boundary layer. The investigation reveals that oblique waves significantly reduce the separation bubble and the boundary layer thickness and weaken the Kelvin–Helmholtz instability. Oblique waves generate streamwise vortices, while high-amplitude oblique waves lead to a three-dimensional checkerboard structure and staggered Λ vortices. The findings demonstrate that oblique breakdown can advance to a fully developed turbulent boundary layer, hence operating as a relevant mechanism for transition in supersonic concave boundary layers.
Dissimilar thermal transport properties in κ-Ga2O3 and β-Ga2O3 revealed by homogeneous nonequilibrium molecular dynamics simulations using machine-learned potentials
Authors: Wang Xiaonan , Yang Jinfeng , Ying Penghua , Fan Zheyong , Zhang Jin , Sun Huarui
Published: February 2024

The lattice thermal conductivity (LTC) of Ga2O3 is an important property due to the challenge in the thermal management of high-power devices. In this work, we develop machine-learned neuroevolution potentials (NEPs) for single-crystalline β−Ga2O3 and κ−Ga2O3 and demonstrate their accuracy in modeling thermal transport properties. Combining NEP-driven homogeneous non-equilibrium molecular dynamics simulations with tensor analysis, we determine the spatial distributions of LTCs for two Ga2O3 crystals, showing dissimilar thermal behaviors. Specifically, β−Ga2O3 shows isotropic thermal transport properties, with the LTCs along [100], [010], and [001] directions being predicted to be 10.3±0.2, 19.9±0.2, and 12.6±0.2 W/(m K), respectively, consistent with previous experimental measurements. For κ−Ga2O3, our predictions suggest nearly isotropic thermal transport properties, with the LTCs along [100], [010], and [001] being estimated to be 4.5±0.1, 3.9±0.1, and 4.0±0.1 W/(m K). The reduced LTC of κ−Ga2O3 vs β−Ga2O3 stems from its restricted low-frequency phonons up to 5 THz. Furthermore, we find that the β phase exhibits a typical temperature dependence slightly stronger than ∼T−1, whereas the κ phase shows a weaker temperature dependence, ranging from ∼T−0.5 to ∼T−0.7.
Enantioselective control in chiral crystallization of ethylenediamine sulfate using optical trapping with circularly polarized laser beams
Authors: Sugiyama Teruki , Lin Tung-Ming , Su Hao-Tse , Cheng An-Chieh , Sasaki Keiji
Published: February 2024

In this study, we conducted successful experiments on ethylenediamine sulfate (EDS), an organic compound, to investigate its enantioselectivity in chiral crystallization. We employed optical trapping with circularly polarized laser beams, using a continuous wave laser at 1064 nm. By focusing the laser at the air–solution interface of a heavy water-saturated EDS solution, the formation of sub-micrometer-sized chiral EDS crystals was verified. Two generated enantiomorphs (d-crystal and l-crystal) were identified by the rotating analyzer method. The enantioselectivity in the chiral crystallization of EDS was assessed through 30 to 60 times experiments conducted under various conditions of laser powers and polarization modes, utilizing the count of generated crystals for each enantiomorph in the evaluation. Circularly polarized lasers at a specific power created an imbalance in the generation probability of the enantiomorphs, resulting in crystal enantiomeric excess values of 23% and −30%. The enantioselectivity mechanism was explored from two perspectives: refractive index differences of two enantiomorphs and 3D helical optical forces. Study of the thermodynamic mechanism was insufficient to explain the outcomes. Conversely, the 3D helical optical force mechanism revealed that the forces acting on EDS clusters in solution induced helical fluid motion, driving EDS nucleation, with the helicity of fluid motion determining the crystal’s chirality. This approach will present new insights into chirality in industrial and research fields, with potential applications in regard to improving optical resolution and addressing the origin of homochirality.
Ultraviolet laser-driven ultra-high transverse voltage in Bi-2201 thin films
Authors: Cheng W. P. , He Y. D. , Wei R. H. , Hu L. , Song W. H. , Cai C. B. , Zhu X. B. , Sun Y. P.
Published: February 2024

The development of high-performance optically induced voltage materials represents a significant challenge within the realm of optical detection. The constraints posed by low induced voltage and extended response times have impeded the practical applicability of optical and thermal radiation detectors. In this investigation, we propose the utilization of superconducting Bi2Sr2CuOy (Bi-2201) as a pulsed laser-induced voltage material, revealing the emergence of notable transverse voltage signals in tilted thin films. A noteworthy peak voltage of 25.12 V is attained upon exposure to ultraviolet pulsed laser (248 nm), with a rapid rise time of merely 60 ns. Furthermore, we establish an empirical equation specific to our laser detection heterostructure, serving as a benchmark for Bi-2201-based laser detection systems. These findings introduce a promising avenue for the expanded practical applications of high-temperature superconductors.
Unusual tilted growth and epitaxial relationship of NaCl B1-structured NiO and CrN on r-plane Al2O3
Authors: A. F. Lahiji Faezeh , Paul Biplab , le Febvrier Arnaud , Eklund Per
Published: February 2024

Epitaxial NiO and CrN thin films were deposited on a single-crystal Al2O3(11¯02) (r-plane sapphire) using magnetron sputtering. The two materials were intentionally deposited into two different deposition chamber designs and under different conditions (temperature, pressure, gases, and energy of sputtered particles). Despite the differences in the deposition condition and material system, both materials had the same feature with uncommon tilted epitaxial growth. Through an in-depth x-ray diffraction analysis of the NaCl (B1)-structured materials on r-plane sapphire, the full twin domain epitaxial relations were determined and can be described as (110)NaCl(B1)∥(44¯03)Al2O3 and [11¯2]NaCl(B1)∥[1¯1¯20]Al2O3. This relationship differs from the previously observed orientation of (100)NaCl(B1)∥(11¯02)Al2O3 and [100]NaCl(B1)∥[101¯0]Al2O3. These results are of general relevance for the growth of the extended NaCl (B1)-structured cubic material family onto a r-plane sapphire substrate where similar epitaxial growth can be expected.
Observation of band gap bowing effect vanishing in graded-composition monolayer Mo1−xWxS2 alloy
Authors: Zhao Weiwei , Zheng Ting , Cui Yueying , Song Junming , Liu Hongwei , Lu Junpeng , Ni Zhenhua
Published: February 2024

Over the past decade, tremendous effort has been put into developing 2D semiconductor materials with a tunable bandgap by alloying different individual components. However, the bandgap bowing effect has hindered the ability to arbitrary control the emission of these alloys. In this study, we report the chemical vapor deposition growth of a graded-composition Mo1−xWxS2 monolayer alloy, in which the photoluminescence emission energy exhibits nearly linear variation in the bandgap, indicating the vanishing of the bandgap bowing effect. Polarized Raman measurements show that the polarization is composition dependent, and a large symmetry breaking occurs at the point where the bandgap bowing effect vanishes. This suggests that the vanishing of the bowing effect may be attributed to the symmetry breaking induced by compressive strain. Our findings demonstrate a significant advancement in the synthesis of alloys for future use.
Influence of coaxiality on internal mixing of coflow generated droplets
Authors: Ge Han , Chen Jiawang , Wang Yuhong , Wang Chizhong
Published: February 2024

Efficient internal mixing stands as a pivotal requirement for droplet-based micro-reactors/micro-mixers facilitated by microfluidic systems. Among the various methods for their production, capillary-generated droplets emerge as a notable approach. Understanding the role of coaxiality within coflow microfluidic devices in influencing internal mixing remains a crucial aspect for optimizing these systems. Coaxiality within inserted cylindrical capillaries significantly affects mixing efficiency according to our experimental observations. Through numerical simulations, the intricate mixing dynamics of reagents inside droplet generated via a coflow capillary microfluidic system has been investigated. We demonstrate that coaxiality profoundly impacts the initial distribution of disperse phases within droplets, shaping subsequent internal mixing dynamics. Contrary to previous assumptions, our findings highlight the substantial impact of marginal deviations in coaxiality, around 20%, on optimizing mixing efficiency. This challenges prior beliefs and emphasizes the nuanced role of coaxiality in microfluidic systems. These insights advance our understanding of coaxiality's critical influence on enhancing mixing efficiency within coflow microfluidic devices, paving the way for improved design strategies and applications in diverse scientific fields.
Parametric effects on Richtmyer–Meshkov instability of a V-shaped gaseous interface within linear stage
Authors: Wu-Wang Hongzhi , Liu Changwen , Xiao Zuoli
Published: February 2024

The Richtmyer–Meshkov instability of a V-shaped air/SF6 gaseous interface is numerically studied via a high-order finite difference scheme and a localized artificial diffusivity method. The oblique angle of the interface ranges from 20° to 75°, and the incident shock Mach number varies from 1.05 to 1.75. The wave patterns and the vortex structures are visualized during the interface evolution. A cavity is observed at the spike fingertip when the oblique angle decreases, which proves to be formed due to Mach reflection of the transmitted shock through velocity decomposition. By analyzing the linear growth rates of the interface, a modified empirical model for the reduction factor is suggested with model coefficients acquired by linear fitting for different Mach numbers. With shock polar analysis (SPA) method and visualization of the wave configuration, a criterion is proposed to explain the non-monotonic dependence of the linear growth rate on the oblique angle. In addition, Mach number effects on the linear growth rate are discussed by the SPA method, especially the anomalous behavior of the Mach 1.05 case.
Quantification of the sheet resistance between two-dimensional semiconductors and semi-metals by a contact-end-resistance method
Authors: Zhu Wen , Li Yida , Feng Xuewei
Published: February 2024

Semi-metal presents an extremely promising method for establishing an ohmic contact with near-quantum-limit contact resistance (Rc) in two-dimensional material (2DM) transistors. However, the physical mechanisms occurring at the interface between 2DMs and semi-metals, which contribute to Rc reduction, are not yet well understood. Leveraging on the contact-end-resistance model applied to the transfer length method structure, we conduct a quantitative and comprehensive characterization of the molybdenum disulfide (MoS2) contact interface with various contact metals. The sheet resistance beneath the semi-metal contact (Rsk) is found to be two orders of magnitude smaller than the sheet resistance of the channel (Rsh), validating the electron doping effect of semi-metals on MoS2 contact areas. Among semi-metals studied, including bismuth (Bi), antimony (Sb), and their alloy, Bi results in the highest electron doping density and the lowest Rsk of 764 Ω/◻, leading to an improvement in Rc down to 526 Ω μm. This work provides a perspective toward the physical mechanisms beneath the semi-metal induced Rc reduction, setting a strong foundation for devising strategies to lower the Rc in 2D-based devices.
Turbulent flow in an I–L junction: Impacts of the pipe diameter ratio
Authors: Zhao L. , Chen J. , Duan G.
Published: February 2024

Pipeline junction plays a pivotal role in fluid mixing for biomedical, chemical, and industrial processes. This study introduces an I–L junction for pipeline systems, fostering concurrent flow between branch-pipe injection and the main pipe bulk flow. In contrast to the conventional T-junction with perpendicular injection, the I–L design demonstrates high potential in mitigating vibration-induced fatigue risks, given an optimal branch-to-main pipe diameter ratio, rd. Using unsteady Reynolds-averaged Navier–Stokes equations, the study assesses fluid mixing across a broad range of rd (1/12–1/2.5). The streamline geometry undergoes a transition from well-defined symmetric vortices to unsteady oscillations when the pipe diameters diverge beyond 1/4, arising from vortex shedding in the wake of the branch pipe. Despite the conventional T-junction showing a more homogeneous velocity distribution in the streamwise direction, its turbulent kinetic energy (TKE, both modeled and calculated from the resolved-scale velocities) near the junction is an order of magnitude larger, implying high overall inhomogeneity in the flow. The TKE decays rapidly to an equivalent level compared to the proposed I–L junction approaching discharge, indicating that the peaking of TKE in the T-junction does not significantly contribute to enhanced fluid mixing. Conversely, it can likely result in harmful vibrations inside the pipeline. While the turbulence statistics remain qualitatively unchanged for rd<1/4, an enlarged discrepancy in pipe diameters beyond rd<1/6 yields more favorable mean surface pressure coefficient, CP¯. The results provide insights into pipeline design, recommending an optimal pipe diameter ratio for enhanced mixing of successively collected fluids while retaining improved system reliability.
Competitive behavior between the piezoelectric and piezoresistive effects in monolayer WS2 photodetector
Authors: Pei Yongfeng , Kang Yufan , He Dong , Zhou Xinyi , Ma MingJun , Jiang Changzhong , Li Wenqing , Xiao Xiangheng
Published: February 2024

The strain induced piezoelectric and piezoresistive effects have been regarded as promising methods to regulate the photoelectric properties of two-dimensional transition metal dichalcogenides. However, the distinction between the influence of piezoelectric and piezoresistive effects on devices is ambiguous. Here, piezo-phototronic photodetectors based on monolayer WS2 were fabricated to investigate the competitive behavior of the piezoelectric and piezoresistive effects. We have shown that the piezoresistive effect dominates the photocurrent enhancement through narrowing the bandgap under small strain. With increasing strain, the influence of piezoelectric effect became more and more obvious, and it dominated the photo-induced carrier transport behavior through polarization charges accumulated at the metal–semiconductor contact interface when the strain exceeded 0.78%. Under the strain condition, the modulation of strain on photocurrent reached as high as 1400%.
Spectroscopic observation of Feshbach resonances in the tellurium dimer anion
Authors: Yan Shuaiting , Zhang Rui , Lu Yuzhu , Ning Chuangang
Published: February 2024

We report on the high-resolution photodetachment spectroscopy of the cryogenically cooled anionic tellurium dimer (Te2−). The high-resolution resonant photoelectron spectrum yields an accurate electron affinity of 16 689.7(92) cm−1 or 2.0693(11) eV for Te2. Two resonant states of Te2− anions have been identified, positioned at 1092(17) cm−1 below and 250(11) cm−1 above the photodetachment threshold, respectively. The spectra of resonant two-photon detachment (R2PD) and autodetachment from a specific vibrational level through a Feshbach resonance exhibit notable non-Franck–Condon behaviors. Using the spectroscopic data from the current experiment, the equilibrium bond distances and spectroscopic constants of the ground state and two electronically excited states of Te2− were determined.
Bimodal surface lattice resonance sensing based on asymmetric metasurfaces
Authors: Li Liye , Wu Wengang
Published: February 2024

The surface lattice resonance (SLR) is a prominent mechanism to produce ultranarrow spectrum line shape, which can enhance the localized electric field and restrain radiation losses. However, the present research mainly focuses on the single-mode SLR and does not involve the multiplexing and higher-order SLRs. To promote the practicability of SLR, we propose bimodal reflection-type SLRs excited by the natural light based on three kinds of asymmetric optical metasurfaces systemically, which are applied to refractive index sensing with high figures of merit (FoMs) experimentally. The rectangular lattice metasurface breaks the C4 symmetry and produces concurrently (±1, 0) and (0, ±1) order SLRs, with FoMs of 33.50 and 28.85, respectively. In addition, the metasurface composed of two different patches belongs to a spatial multiplexing design and can also realize nearly identical SLR responses. Furthermore, the asymmetric dimer metasurface excites two SLRs with distinct orders meanwhile, where the high-order SLR originates from the trapping of the corresponding Rayleigh anomaly waves. The above-mentioned metasurface designs have flexibility and regularity, whose resonance wavelengths, sensitivities, and bimodal combinations can be attained at will by tuning period lengths, arranging different patches, or forming a dimer meta-atom. The research takes a significant step for bimodal SLR development and application, especially in the sensing field.
Spectral tweezers: Single sample spectroscopy using optoelectronic tweezers
Authors: Zaman Mohammad Asif , Wu Mo , Ren Wei , Jensen Michael A. , Davis Ronald W. , Hesselink Lambertus
Published: February 2024

A scheme that combines optoelectronic tweezers (OET) with spectroscopic analysis is presented. Referred to as spectral tweezers, the approach uses a single focused light beam that acts both as the trapping beam for OET and the probe beam for spectroscopy. Having simultaneous manipulation and spectral characterization ability, the method is used to isolate single micro-samples from clusters and perform spectral measurements. Experimental results show that a characteristic spectral signature can be obtained for a given sample. The proposed approach can be easily integrated into the optical setups used for conventional OETs with only a few additional optical components, making it a convenient tool for bio-analytical applications.
Compact sum-of-products form of the molecular electronic Hamiltonian based on canonical polyadic decomposition
Authors: Sasmal Sudip , Schröder Markus , Vendrell Oriol
Published: February 2024

We propose an approach to represent the second-quantized electronic Hamiltonian in a compact sum-of-products (SOP) form. The approach is based on the canonical polyadic decomposition of the original Hamiltonian projected onto the sub-Fock spaces formed by groups of spin–orbitals. The algorithm for obtaining the canonical polyadic form starts from an exact sum-of-products, which is then optimally compactified using an alternating least squares procedure. We discuss the relation of this specific SOP with related forms, namely the Tucker format and the matrix product operator often used in conjunction with matrix product states. We benchmark the method on the electronic dynamics of an excited water molecule, trans-polyenes, and the charge migration in glycine upon inner-valence ionization. The quantum dynamics are performed with the multilayer multiconfiguration time-dependent Hartree method in second quantization representation. Other methods based on tree-tensor Ansätze may profit from this general approach.
Pressure-drop and Trouton ratio for Oldroyd-B fluids in hyperbolic converging channels
Authors: Housiadas Kostas D. , Beris Antony N.
Published: February 2024

We present new theoretical developments on the incompressible viscoelastic flow of an Oldroyd-B fluid in a hyperbolic contracting symmetric channel. We show uniformity of the effect of viscoelasticity in hyperbolic planar and cylindrical axisymmetric geometries by revealing a modified Deborah number according to which the lubrication solutions for the pressure drop and the Trouton ratio are simplified. We also develop an expression for the Trouton ratio in terms of the fluid velocity at the midplane only, valid beyond the lubrication limit. Using the Newtonian velocity as a first approximation, we show the enhancement of the Trouton ratio with increasing the fluid elasticity.
Boosting cascade electron transfer in NiFe oxyhydroxide for overall water splitting
Authors: Xian Ming-Hua , Wan Hui , Wang Qiao-Ling , Xie Meng-Yuan , Shi Jinghui , Nie Jianhang , Li Bo , Ou-Yang Zhen-Yang , Huang Jia-Rong , Wang Di , Huang Gui-Fang , Hu Wangyu , Huang Wei-Qing
Published: February 2024

Nickel–iron oxyhydroxides are among the most active electrocatalysts, but their sluggish kinetic of oxygen evolution reaction (OER) limits the energy efficiency toward overall water splitting. Here, we present a “cascade electron transfer” strategy through spurring unidirectional electron transfer among different metal sites in Mn-doped FeNiOOH@FeNiP to boost OER and overall water splitting. The Mn doping induces a cascade electron transfer from Ni to Fe and then to Mn via metal-O-metal bridge, thus promoting the oxidation Ni and Fe centers, which in turn help charge transfer by increasing the covalency between metal-O bonds to optimize the bonding strength between metal and adsorbed oxygen species. Consequently, the optimal Mn–FeNiOOH@FeNiP delivers a fast OER kinetics (32.1 mV dec−1) along with a low overpotential of 215 mV@10 mA cm−2. Benefiting from the synergistic effect of high conductivity, large specific surface area, and favorable OER kinetics, the catalyst only requires a low cell voltage of 1.456 V to achieve 20 mA cm−2 for overall water splitting, superior to that of a commercial RuO2ǁPt/C catalyst.
Understanding the ant’s unique biting system can improve surgical needle holders
Authors: Wipfler Benjamin , Hoepfner Ole , Viebahn Felix , Weihmann Tom , Rieg Frank , Engelmann Carsten
Published: February 2024

Mechanical grasping and holding devices depend upon a firm and controlled grip. The possibility to improve this gripping performance is severely limited by the need for miniaturization in many applications, such as robotics, microassembly, or surgery. In this paper, we show how this gripping can be improved in one application (the endoscopic needle holder) by understanding and imitating the design principles that evolution has selected to make the mandibles of an ant a powerful natural gripping device. State-of-the-art kinematic, morphological, and engineering approaches show that the ant, in contrast to other insects, has considerable movement within the articulation and the jaw´s rotational axis. We derived three major evolutionary design principles from the ant’s biting apparatus: 1) a mobile joint axis, 2) a tilted orientation of the mandibular axis, and 3) force transmission of the adductor muscle to the tip of the mandible. Application of these three principles to a commercially available endoscopic needle holder resulted in calculated force amplification up to 296% and an experimentally measured one up to 433%. This reduced the amount of translations and rotations of the needle, compared to the needle’s original design, while retaining its size or outer shape. This study serves as just one example showing how bioengineers might find elegant solutions to their design problems by closely observing the natural world.
Multimodal neuro-nanotechnology: Challenging the existing paradigm in glioblastoma therapy
Authors: Kudruk Sergej , Forsyth Connor M. , Dion Michelle Z. , Hedlund Orbeck Jenny K. , Luo Jingqin , Klein Robyn S. , Kim Albert H. , Heimberger Amy B. , Mirkin Chad A. , Stegh Alexander H. , Artzi Natalie
Published: February 2024

Integrating multimodal neuro- and nanotechnology-enabled precision immunotherapies with extant systemic immunotherapies may finally provide a significant breakthrough for combatting glioblastoma (GBM). The potency of this approach lies in its ability to train the immune system to efficiently identify and eradicate cancer cells, thereby creating anti-tumor immune memory while minimizing multi-mechanistic immune suppression. A critical aspect of these therapies is the controlled, spatiotemporal delivery of structurally defined nanotherapeutics into the GBM tumor microenvironment (TME). Architectures such as spherical nucleic acids or poly(beta-amino ester)/dendrimer-based nanoparticles have shown promising results in preclinical models due to their multivalency and abilities to activate antigen-presenting cells and prime antigen-specific T cells. These nanostructures also permit systematic variation to optimize their distribution, TME accumulation, cellular uptake, and overall immunostimulatory effects. Delving deeper into the relationships between nanotherapeutic structures and their performance will accelerate nano-drug development and pave the way for the rapid clinical translation of advanced nanomedicines. In addition, the efficacy of nanotechnology-based immunotherapies may be enhanced when integrated with emerging precision surgical techniques, such as laser interstitial thermal therapy, and when combined with systemic immunotherapies, particularly inhibitors of immune-mediated checkpoints and immunosuppressive adenosine signaling. In this perspective, we highlight the potential of emerging treatment modalities, combining advances in biomedical engineering and neurotechnology development with existing immunotherapies to overcome treatment resistance and transform the management of GBM. We conclude with a call to action for researchers to leverage these technologies and accelerate their translation into the clinic.
The 10,000-year biocultural history of fallow deer and its implications for conservation policy
Authors: Baker Karis H. , Miller Holly , Doherty Sean , Gray Howard W. I. , Daujat Julie , Çakırlar Canan , Spassov Nikolai , Trantalidou Katerina , Madgwick Richard , Lamb Angela L. , Ameen Carly , Atici Levent , Baker Polydora , Beglane Fiona , Benkert Helene , Bendrey Robin , Binois-Roman Annelise , Carden Ruth F. , Curci Antonio , De Cupere Bea , Detry Cleia , Gál Erika , Genies Chloé , Kunst Günther K. , Liddiard Robert , Nicholson Rebecca , Perdikaris Sophia , Peters Joris , Pigière Fabienne , Pluskowski Aleksander G. , Sadler Peta , Sicard Sandra , Strid Lena , Sudds Jack , Symmons Robert , Tardio Katie , Valenzuela Alejandro , van Veen Monique , Vuković Sonja , Weinstock Jaco , Wilkens Barbara , Wilson Roger J. A. , Evans Jane A. , Hoelzel A. Rus , Sykes Naomi
Published: February 2024

Over the last 10,000 y, humans have manipulated fallow deer populations with varying outcomes. Persian fallow deer (Dama mesopotamica) are now endangered. European fallow deer (Dama dama) are globally widespread and are simultaneously considered wild, domestic, endangered, invasive and are even the national animal of Barbuda and Antigua. Despite their close association with people, there is no consensus regarding their natural ranges or the timing and circumstances of their human-mediated translocations and extirpations. Our mitochondrial analyses of modern and archaeological specimens revealed two distinct clades of European fallow deer present in Anatolia and the Balkans. Zooarchaeological evidence suggests these regions were their sole glacial refugia. By combining biomolecular analyses with archaeological and textual evidence, we chart the declining distribution of Persian fallow deer and demonstrate that humans repeatedly translocated European fallow deer, sourced from the most geographically distant populations. Deer taken to Neolithic Chios and Rhodes derived not from nearby Anatolia, but from the Balkans. Though fallow deer were translocated throughout the Mediterranean as part of their association with the Greco-Roman goddesses Artemis and Diana, deer taken to Roman Mallorca were not locally availableDama dama, butDama mesopotamica. Romans also initially introduced fallow deer to Northern Europe but the species became extinct and was reintroduced in the medieval period, this time from Anatolia. European colonial powers then transported deer populations across the globe. The biocultural histories of fallow deer challenge preconceptions about the divisions between wild and domestic species and provide information that should underpin modern management strategies.
The GATA transcriptional program dictates cell fate equilibrium to establish the maternal–fetal exchange interface and fetal development
Authors: Ghosh Ananya , Kumar Rajnish , Kumar Ram P. , Ray Soma , Saha Abhik , Roy Namrata , Dasgupta Purbasa , Marsh Courtney , Paul Soumen
Published: February 2024

The placenta establishes a maternal–fetal exchange interface to transport nutrients and gases between the mother and the fetus. Establishment of this exchange interface relies on the development of multinucleated syncytiotrophoblasts (SynT) from trophoblast progenitors, and defect in SynT development often leads to pregnancy failure and impaired embryonic development. Here, we show that mouse embryos with conditional deletion of transcription factors GATA2 and GATA3 in labyrinth trophoblast progenitors (LaTPs) have underdeveloped placenta and die by ~embryonic day 9.5. Single-cell RNA sequencing analysis revealed excessive accumulation of multipotent LaTPs upon conditional deletion of GATA factors. The GATA factor–deleted multipotent progenitors were unable to differentiate into matured SynTs. We also show that the GATA factor–mediated priming of trophoblast progenitors for SynT differentiation is a conserved event during human placentation. Loss of either GATA2 or GATA3 in cytotrophoblast-derived human trophoblast stem cells (human TSCs) drastically inhibits SynT differentiation potential. Identification of GATA2 and GATA3 target genes along with comparative bioinformatics analyses revealed that GATA factors directly regulate hundreds of common genes in human TSCs, including genes that are essential for SynT development and implicated in preeclampsia and fetal growth retardation. Thus, our study uncovers a conserved molecular mechanism, in which coordinated function of GATA2 and GATA3 promotes trophoblast progenitor-to-SynT commitment, ensuring establishment of the maternal–fetal exchange interface.