bluuebunny/crossref_metadata_2025 huggingface dataset:
Utility of Dual-Energy CT in Abdominal Interventions
Authors: Tripathy Tara Prasad , Patel Ranjan , Chandel Karamvir , Mukund Amar
Published: January 2022

Dual-energy computed tomography (DECT) is an emerging CT technique based on data acquisition at two different settings. Various postprocessing techniques generate different sets of images, each with unique advantages. With DECT, it is possible to obtain virtual unenhanced images from monochromatic reconstructions and attenuation maps of different elements, thereby improving the detection and characterization of a variety of lesions. Presently, DECT is widely used to evaluate pulmonary embolism, characterize abdominal masses, determine the composition of urinary calculi, and detect tophi in gout. CT angiography is an essential prerequisite for endovascular intervention. DECT allows a better quality of angiographic images with a lesser dose of contrast. Various postprocessing techniques in DECT also help in a better evaluation of response to locoregional therapy. Virtual noncontrast images and iodine map differentiate residual or recurrent tumors from intrinsically hyperdense materials. Superior metallic artifact reduction allows better evaluation of vascular injuries adjacent to bony fractured fragments or previously deployed embolization coils. In addition to metal artifacts reduction, virtual monochromatic spectral imaging could further mitigate metal artifacts during CT-guided biopsy, providing an improved depiction of lesions and safe and versatile access for long puncture pathways. This article reviews and illustrates the different applications of DECT in various abdominal interventions. Familiarity with the capabilities of DECT may help interventional radiologists to improve their practice and ameliorate patient care.
Augmenting a colour lexicon
Authors: Mylonas Dimitris , Caparos Serge , Davidoff Jules
Published: January 2022

Languages differ markedly in the number of colour terms in their lexicons. The Himba, for example, a remote culture in Namibia, were reported in 2005 to have only a 5-colour term language. We re-examined their colour naming using a novel computer-based method drawing colours from across the gamut rather than only from the saturated shell of colour space that is the norm in cross-cultural colour research. Measuring confidence in communication, the Himba now have seven terms, or more properly categories, that are independent of other colour terms. Thus, we report the first augmentation of major terms, namely green and brown, to a colour lexicon in any language. A critical examination of supervised and unsupervised machine-learning approaches across the two datasets collected at different periods shows that perceptual mechanisms can, at most, only to some extent explain colour category formation and that cultural factors, such as linguistic similarity are the critical driving force for augmenting colour terms and effective colour communication.
CLPVG: Circular limited penetrable visibility graph as a new network model for time series
Authors: Xuan Qi , Zhou Jinchao , Qiu Kunfeng , Xu Dongwei , Zheng Shilian , Yang Xiaoniu
Published: January 2022

A visibility graph transforms time series into graphs, facilitating signal processing by advanced graph data mining algorithms. In this paper, based on the classic limited penetrable visibility graph method, we propose a novel mapping method named circular limited penetrable visibility graph, which replaces the linear visibility line in limited penetrable visibility graph with nonlinear visibility arc for pursuing more flexible and reasonable mapping of time series. Tests on degree distribution and some common network features of the generated graphs from typical time series demonstrate that our circular limited penetrable visibility graph can effectively capture the important features of time series and show higher robust classification performance than the traditional limited penetrable visibility graph in the presence of noise. The experiments on real-world time-series datasets of radio and electroencephalogram signals also suggest that the structural features provided by a circular limited penetrable visibility graph, rather than a limited penetrable visibility graph, are more useful for time-series classification, leading to higher accuracy. This classification performance can be further enhanced through structural feature expansion by adopting subgraph networks. All of these results demonstrate the effectiveness of our circular limited penetrable visibility graph model.
Some Liouville-type theorems for the stationary density-dependent Navier–Stokes equations
Authors: Liu Pan , Liu Genqian
Published: January 2022

This paper is devoted to the Liouville-type theorems for the 3D stationary density-dependent Navier–Stokes equations, without any integrability assumption on ∇u. More precisely, we prove that the velocity field u, being in some Lorentz spaces, must be zero, provided the density ρ is essentially bounded.
An in-plane omnidirectional piezoelectric wind energy harvester based on vortex-induced vibration
Authors: Li Shen , He Xuefeng , Li Jiajie , Feng Zhiqiang , Yang Xiaokang , Li Jinghua
Published: January 2022

Variations in the wind direction over time mean that it is essential to improve the directional adaptability of wind energy harvesters (WEHs) based on wind-induced vibration (WIV) to expand their application potential. Several multi-directional WIV WEHs have been reported in the literature but most of them are not omnidirectional. In particular, no mathematical model has been proposed for omnidirectional WIV WEHs to date. In this Letter, an in-plane omnidirectional piezoelectric WEH with a cylindrical shell, acting as a bluff body and supported by internal piezoelectric composite beams, is proposed. It is deduced that the omnidirectionality of wind energy harvesting can be enhanced by improving the isotropies of the aerodynamic force, stiffness, and electromechanical conversion. For a WEH with three semicircular-shaped supporting beams, a mathematical model suitable for arbitrary wind directions in the horizontal plane was derived. Simulations show that the WEH's stiffness and electromechanical conversion are approximately isotropic. Simulations and experiments demonstrate that the wind direction's effect on the total power is small. The ratio of the experimental minimum to maximum total power is 0.88 at 9 m/s, verifying that the device is an in-plane omnidirectional harvester. An omnidirectionality index including contributions from all directions is proposed with the value of 0.86 at 9 m/s for the prototype. The proposed device configuration and design method may serve as a reference for the development of omnidirectional WIV WEHs.
Faradaic-free electrokinetic nucleic acid amplification (E-NAAMP) using localized on-chip high frequency Joule heating
Authors: Yost Jarad , Gagnon Zachary
Published: January 2022

We present a novel Faradaic reaction-free nucleic acid amplification (NAA) method for use with microscale liquid samples. Unlike previous Joule heating methods where the electrodes produce electrolysis gaseous by-products and require both the electrodes be isolated from a sample and the venting of produced electrolysis gas, our electrokinetic Nucleic Acid Amplification (E-NAAMP) method alleviates these issues using a radio frequency (RF) alternating current electric field. In this approach, a pair of microscale thin film gold electrodes are placed directly in contact with a nucleic acid reaction mixture. A high frequency (10–40 MHz) RF potential is then applied across the electrode pair to induce a local Ohmic current within the sample and drive the sample temperature to increase by Joule heating. The temperature increase is sustainable in that it can be generated for several hours of constant use without generating any pH change to the buffer or any microscopically observable gaseous electrolysis by-products. Using this RF Joule heating approach, we demonstrate successful direct thermal amplification using two popular NAA biochemical reactions: loop-mediated isothermal amplification and polymerase chain reaction. Our results demonstrate that a simple microscale electrode structure can be used for thermal regulation for NAA reactions without observable electrolytic reactions, minimal enzyme activity loss and sustained (>50 h use per device) continuous operations without electrode delamination. As such, E-NAAMP offers substantial miniaturization of the heating elements for use in microfluidic or miniaturized NAA reaction systems.
Main modes of microfilament particles deformation in rough channels
Authors: Sabrio Alexandra , Rasoulzadeh Mojdeh
Published: January 2022

The fate and transport of microfilaments in complex structured porous systems are largely affected by the geometry of the irregular pore space in these media. Local features of fluid flow, including local flow instabilities, vorticities, stagnant zones, and reverse flows, which result from the spatially varying pore throat size and altering shear stresses along the channel due to the presence of rough walls, can cause various modes of deformation of filaments and them being carried in reverse direction of the general fluid flow. Furthermore, the buildup of microfilaments along the channel can clog the pore space and rearrange the flow in the channel. In this study, we focus on investigating the role of channel wall roughness on the motion and deformation of five deformable filaments flowing in a channel filled with fluid. A bead-spring model is used for the filament model. At low Reynolds numbers, roughness simply increases the length of the path line along which the filament is being transported. Moreover, at higher Reynolds numbers, the filament closer to the walls can get stuck in the dead flow zones within the rough geometry peaks. The filaments closer to the centerline of the channel undergo less deformation compared to those located closer to the walls. A larger Reynolds number or a more rough geometry of the walls can result in a more wiggly form of the filament. Intermediate roughness and a medium Reynolds number result in more of a hairpin-like filament shape.
Chlorophyll a de-excitation pathways in the LHCII antenna
Authors: Ruban Alexander V. , Saccon Francesco
Published: January 2022

Photosystem II (PSII) uses light energy to split water into protons, electrons, and oxygen, ultimately sustaining heterotrophic life on Earth. The major light harvesting complex in plants (LHCII) is packed with chlorophylls and carotenoids and is the main supplier of excitation energy to PSII reaction centers. The protein scaffold acts as a programmed solvent for the pigments in LHCII, tuning their orientations while at the same time impeding concentration quenching to ensure efficient storage of excitation energy by chlorophylls. However, under stress, the very fuel of PSII, solar photons, can damage its delicate inner components and hamper photosynthesis. In a crucial regulatory strategy in plants, LHCII evolved a flexible design that allows it to switch between light-harvesting and dissipative conformations, thereby safely releasing the excess energy that is absorbed into heat. Several mechanisms have been proposed to explain chlorophyll de-excitation pathways in LHCII, such as chlorophyll–chlorophyll charge transfer states, resonance energy transfer from chlorophylls to a carotenoid S1 state, and chlorophyll–carotenoid reductive energy transfer. This Perspective critically assesses the listed proposals, addressing both the physical mechanism of quenching and the nature of the quenching pigment. These hypotheses are then discussed in the context of state-of-the-art biochemical, physiological, and genetic knowledge to scrutinize their likeliness to occur in the native thylakoid membranes.
Optimized microwave sensing in broad frequency range by a fiber diamond probe
Authors: Bai Ruixin , Yang Fan , Liu Pei , Gao Tianran , Zhou Li , Yin Xiaohan , Zhu Xinyue , Ma Wenhao , He Feiyue , Chen Nuocheng , Sun Yue , Ma Jingting , Yu Tian , Du Guanxiang
Published: January 2022

Diamond based quantum sensing is a fast-emerging field with both scientific and technological importance. The nitrogen-vacancy (NV) center, a crystal defect in diamond, is a unique model system for microwave sensing application due to its excellent photo-stability, long spin coherence time in ambient conditions. In this work, we systematically optimized the measurement parameters for microwave sensing. The system noise is analyzed, and 1/f noise is suppressed by introducing a differential algorithm. The gain of avalanche photodiode and the gating window of the pulsed fluorescence is optimized to further suppress the noise floor. The decoherence of spin is characterized by varying the duration of the laser and microwave. The minimal detectable power on a standard microstrip is characterized with sampling time down to 1 ms, showing flat frequency dependence. The results have important implications toward fast measurement of broadband microwave power, especially in the field of IC testing and radar signal processing under intense electromagnetic interference.
Conductive SiO2/HfO2 distributed Bragg reflector achieved by electrical breakdown and its application in GaN-based light emitters
Authors: Cui Mei , Guo Chenyu , Yang Zhenhai , Chen Li , Dai Yijun , Xu Houqiang , Guo Wei , Ye Jichun
Published: January 2022

Owing to the excellent optical reflectivity with wavelength tunability, dielectric distributed Bragg reflectors (DBRs) have attracted considerable interest in GaN-based light emitters. Yet, the non-conductive nature of the dielectric DBRs prevents current from passing through, leading to a current crowding effect and hampering dielectric DBRs from unlocking their full potential. In this paper, a conductive dielectric DBR was fabricated utilizing the electrical breakdown (EBD) technique. With the help of optical simulations, excellent optical properties were demonstrated by optimizing the structural designs with a high reflectivity of 98.3% at 450 nm based on 5.5 pairs SiO2/HfO2 DBRs. The outstanding electrical behaviors after the EBD process were verified by current–voltage curves and conductive atomic force microscopy characterization. Moreover, conductive mechanisms of this type of dielectric DBR were elaborated by comparing the EBD behaviors with different metal electrodes, suggesting that metal filaments play an important role in forming the conducting channels. Besides, 450 nm-emission with conductive 5.5 pairs SiO2/HfO2 DBR was successfully prepared, which proves that a conductive DBR can be successfully applied to GaN-based light-emitting devices. The conductive DBR presented in this work contributes to the acceleration of the development of high-power GaN-based solid-state light emitters.
Stabilizations and field-driven core reversals of magnetic vortices in Fe3Sn2 disks
Authors: Wu Yaodong , Jiang Jialiang , Wang Yihao , Li Junbo , Xiong Yimin , Kong Lingyao
Published: January 2022

A magnetic vortex is a structure with a polarized core surrounded by an in-plane spin swirl and was first reported in easy-plane disks. Here, we explore the effects of the disk thickness, temperature, and out-of-plane field on the magnetic vortex stabilization and core reversals in Kagome uniaxial ferromagnetic Fe3Sn2 disks. Magnetic ground domains in Fe3Sn2 disks turn from stripes to vortices after decreasing the disk thickness or temperature as the easy-plane anisotropy wins the competition with the uniaxial magnetocrystalline anisotropy. Topological transformations from charge Q=−1/2 vortices at a zero field to Q=−1 skyrmion-like configurations at a high out-of-plane field were identified in cooperation with micromagnetic simulations. Thus, our results promote future vortex-based spintronic applications.
Dynamics of Brownian Janus rods at a liquid–liquid interface
Authors: Hossain Mohammad T. , Gates Ian D. , Natale Giovanniantonio
Published: January 2022

Amphiphilic Janus nanoparticles exhibit higher interfacial activity and adsorb more strongly to fluid interfaces than homogeneous nanoparticles of similar sizes. Taking advantage of both shape and chemical anisotropy on the same particle, Janus particles offer rich self-assembly possibilities for nanotechnology. By using dissipative particle dynamics simulation, the translational diffusion of Janus nanoparticles at the interface between two immiscible fluids is investigated. The particle aspect ratio affects both particle's translational thermal motion and the average orientation of the particle with respect to the interface at equilibrium. This behavior is also linked to the interfacial tension of the system. Our findings provide fundamental insights into the dynamics and self-assembly of anisotropic Brownian particles at interfaces.
Infrared-based visualization of exhalation flows while wearing protective face masks
Authors: Koroteeva E. , Shagiyanova A.
Published: January 2022

Since the onset of the COVID-19 pandemic, a large number of flow visualization procedures have been proposed to assess the effect of personal protective equipment on respiratory flows. This study suggests infrared thermography as a beneficial visualization technique because it is completely noninvasive and safe and, thus, can be used on live individuals rather than mannequins or lung simulators. Here, we examine the effect of wearing either of three popular face coverings (a surgical mask, a cloth mask, or an N95 respirator with an exhalation valve) on thermal signatures of exhaled airflows near a human face while coughing, talking, or breathing. The flow visualization using a mid-wave infrared camera captures the dynamics of thermal inhomogeneities induced by increased concentrations of carbon dioxide in the exhaled air. Thermal images demonstrate that both surgical and cloth face masks allow air leakage through the edges and the fabric itself, but they decrease the initial forward velocity of a cough jet by a factor of four. The N95 respirator, on the other hand, reduces the infrared emission of carbon dioxide near the person's face almost completely. This confirms that the N95-type mask may indeed lead to excessive inhalation of carbon dioxide as suggested by some recent studies.
Growth and morphology of thin epitaxial Pd films on Au(001) film grown on Fe-buffered MgO(001) substrate
Authors: Kawagoe T. , Suga S.
Published: January 2022

We have investigated the growth of thin Pd films on a Au(001) surface, which was a Au(001) film grown on a Fe-buffered MgO(001) substrate, at 290 K up to 4 monolayer (ML) thickness and the effect of post-annealing (PA) at 470 K. The surface morphology and structure are determined using scanning tunneling microscopy (STM) and low-energy electron diffraction (LEED). The LEED patterns of the as-grown and PA films indicate that the Pd(001) films grow epitaxially on the Au(001) surface with noticeable in-pain lattice expansion of 4.5% relative to the bulk Pd, indicating a tensely strained tetragonal deformation. The Pd film does not grow in the layer-by-layer growth mode at 290 K. Instead, numerous Pd islands grow anisotropically along the 〈110〉 direction. The surface morphology of the films improves significantly after the PA at 470 K due to the coalescence of the elongated Pd islands. Consequently, the room temperature growth of the Pd layers followed by PA at 470 K enables us to fabricate the high-quality epitaxial Pd(001) film, which has large and atomically flat terraces without Au segregation. Additional Pd growth up to 8 ML thickness onto such 4 ML PA films kept at 470 K is also studied by STM. This specific three-step method facilitates the quasi-layer-by-layer growth and opens a chance for practical use in the future.
Shock temperatures and melting curve of an Fe–Ni–Cr alloy up to 304 GPa
Authors: Gan Bo , Li Jun , Wu Qiang , Jiang Gang , Geng Hua Y. , Tan Ye , Zhou Xianming , Sekine Toshimori , Gao Zhipeng , Zhang Youjun
Published: January 2022

The melting temperatures of Fe–Ni alloys and their densities in the liquid state at relevant pressure–temperature (P–T) conditions present in the core are of great importance for understanding the composition and thermal structure of the Earth's core. We measured shock temperatures of the Fe–11Ni–18Cr (wt. %) alloy up to ∼304 GPa using a special target configuration, a quasi-spectral pyrometer, and velocimeter diagnostics in a two-stage light-gas gun. The present results show that Fe–11Ni–18Cr starts to melt at the pressure of 210 (8) GPa and 4700 (300) K and completes at the pressure of 280 (10) GPa and 5250 (350) K under shock loading, which is ∼1000 K lower than some previous shock temperature measurements. The melting temperatures of the Fe–11Ni–18Cr alloy are 4100 (250) K and 5500 (450) K at the pressures present at the core-mantle boundary (∼136 GPa) and inner-core boundary (∼330 GPa), respectively, which are slightly lower than that of pure iron. Combined with the previous results of the pressure–density measurements at Hugoniot states, our results indicate that the presence of limited amounts of Ni and Cr into Fe has a minor effect on its melting curve and density in the liquid state, suggesting that sufficient light elements are required in the outer core to satisfy both the core density deficit and the reduced melting temperature.
A physical mechanism of heterogeneity and micro-metastasis in stem cells, cancer cells, and cancer stem cells
Authors: Yu Chong , Liu Qiong , Wang Jin
Published: January 2022

Heterogeneity is ubiquitous in stem cells (SC), cancer cells (CS), and cancer SC (CSC). This heterogeneity manifests in the form of diverse sub-populations of SC, CS, and CSC with self-renewal and unique regeneration capacity. Moreover, the progeny of CSC possess multiple plasticity and cancerous characteristics. Many studies have demonstrated that cancer heterogeneity is among the greatest obstacles to successful anti-cancer therapy. This leads to incomplete therapy and transitory efficacy. Furthermore, numerous micro-metastases lead to the spread of tumor cells widely across the body; this is the beginning of metastasis. Epigenetic processes (DNA methylation and histone remodification) represent sources of heterogeneity. In this study, we develop a mathematical model to quantify the heterogeneity of SC, CS, and CSC, taking into consideration both genetic and epigenetic effects. We reveal the roles and physical mechanisms of heterogeneity in SC, CSC, and cancer cells. Under the adiabatic regime (relatively fast regulatory binding and effective coupling among genes), seven native states (SC, CSC, cancer, premalignant, normal, lesion, and hyperplasia) emerge. Under the non-adiabatic regime (relatively slow regulatory binding and effective weak coupling among genes), SC, CS, CSC, and differentiated states emerge and become diffusive, partially explaining the origin of heterogeneity. In other words, slow regulatory binding that mimics epigenetic effects can give rise to heterogeneity. Moreover, we calculated the entropy production rate and Fano factor, which can be used to quantify the thermodynamic cost and the degrees of the variations or the fluctuations as the parameter ω (representing the speed of regulatory binding/unbinding relative to the synthesis/degradation) changes. Elucidating the origins of heterogeneity and the dynamical relationships between intra-tumoral cells has a clear clinical significance and will improve the understanding of the cellular basis of treatment response, therapeutic resistance, and cancer metastasis.
High-efficiency array-level MRAM parameters extraction with the device-in-series test structure
Authors: Zhang Zeyu , Gao Shifan , Zhao Yi , Yang Xiaolei , Zhao Jiankun , He Shikun
Published: January 2022

The precise extraction of magnetic tunnel junction parameters at device level is important for understanding the weak point and its root cause in the stack design, which allows for future developments. The related variability is also vital for a reliable memory technology. Current test methods, however, are limited either to the material level or low efficiency. In this work, a device-in-series structure is proposed that directly monitors the statistical properties of the devices. This allows for a massively parallel measurement and, in this way, permits an accurate, high-efficiency testing with the device-to-device variability embedded intrinsically. Based on this method, we studied the temperature dependence of spin-transfer torque magnetoresistive random access memory’s retention from 12 to 300 K, using a statistical domain wall switching model. The synthetic antiferromagnetic layers are more immune to the temperature change, compared with the free layer. The magnetoresistance is found to be a convex function of the temperature below 100 K, which contrasts the single-device measurements. The results show that as the temperature decreases, the domain wall shrinks and the zero-field energy barrier still increases.
Dielectric nanoparticle suspensions for increased electrostatic forces
Authors: Frankforter Kevin J. , Ludois Daniel C. , Klingenberg Daniel J.
Published: January 2022

Dielectric suspensions of nanoparticles for electrostatic force production applications have been developed. To avoid viscosity increases due to the electrorheological effect, aliphatically coated BaTiO3 nanoparticles were synthesized and mixed with n-decane to form concentrated dielectric suspensions. The synthesis and characterization of the nanoparticles and the suspensions are described. The increased electrostatic force on electrodes due to the increased relative permittivity of the dielectric suspensions is verified with force test stand measurements, consistent with a standard electrostatic model.
Analysis of preconcentration patterns in microfluidic ion concentration polarization devices
Authors: Gholinejad Majid , Jabari Moghadam Ali , Mousavi Shaegh Seyed Ali
Published: January 2022

The analysis of governing parameters on the preconcentration of charged analytes is of utmost importance for ion concentration polarization-based devices. The interaction between applied voltage and microchannel length, i.e., the electric field, can be used to obtain optimum operation of ion concentration polarization (ICP) in terms of enrichment factor. In this paper, the affecting parameters of ICP were studied numerically and experimentally to investigate the preconcentrating behavior of analytes upon applying voltage. We showed that applying different electric fields changes the accumulation patterns of the preconcentrated analytes. We classified the patterns for the first time based on the range of electric fields as no preconcentration, dispersed, protruded, and focused preconcentration. In addition, the analysis of the effect of buffer concentration on enrichment factor revealed that unlike the electric field, the buffer concentration only affects the enrichment factor without influencing the preconcentrated analyte pattern. The results demonstrated that by decreasing the buffer concentration, the enrichment factor is increased. The comparison of the experimental findings with the numerical results, obtained from COMSOL Multiphysics®, manifested acceptable correspondence. The findings of this study can be used for further optimization, to develop high-performance ICP devices in biomedical and analytical applications.
Nonlinear quantum interferometric spectroscopy with entangled photon pairs
Authors: Asban Shahaf , Chernyak Vladimir Y. , Mukamel Shaul
Published: January 2022

We develop closed expressions for a time-resolved photon counting signal induced by an entangled photon pair in an interferometric spectroscopy setup. Superoperator expressions in Liouville-space are derived that can account for relaxation and dephasing induced by coupling to a bath. Interferometric setups mix matter and light variables non-trivially, which complicates their interpretation. We provide an intuitive modular framework for this setup that simplifies its description. Based on the separation between the detection stage and the light–matter interaction processes, we show that the pair entanglement time and the interferometric time-variables control the observed physics time scale. Only a few processes contribute in the limiting case of small entanglement time with respect to the sample response, and specific contributions can be singled out.
Wall shear stress and wall heat flux in a supersonic turbulent boundary layer
Authors: Tong Fulin , Dong Siwei , Lai Jiang , Yuan Xianxu , Li Xinliang
Published: January 2022

We report the characteristics of wall shear stress (WSS) and wall heat flux (WHF) from direct numerical simulation (DNS) of a spatially developing zero-pressure-gradient supersonic turbulent boundary layer at a free-stream Mach number M∞ = 2.25 and a Reynolds number Reτ = 769 with a cold-wall thermal condition (a ratio of wall temperature to recovery temperature Tw/Tr = 0.75). A comparative analysis is performed on statistical data, including fluctuation intensity, probability density function, frequency spectra, and space–time correlation. The root mean square fluctuations of the WHF exhibit a logarithmic dependence on Reτ similar to that for the WSS, the main difference being a larger constant. Unlike the WSS, the probability density function of the WHF does not follow a lognormal distribution. The results suggest that the WHF contains more energy in the higher frequencies and propagates downstream faster than the WSS. A detailed conditional analysis comparing the flow structures responsible for extreme positive and negative fluctuation events of the WSS and WHF is performed for the first time, to the best of our knowledge. The conditioned results for the WSS exhibit closer structural similarities with the incompressible DNS analysis documented by Pan and Kwon [“Extremely high wall-shear stress events in a turbulent boundary layer,” J. Phys.: Conf. Ser. 1001, 012004 (2018)] and Guerrero et al. [“Extreme wall shear stress events in turbulent pipe flows: Spatial characteristics of coherent motions,” J. Fluid Mech. 904, A18 (2020)]. Importantly, the conditionally averaged flow fields of the WHF exhibit a different mechanism, where the extreme positive and negative events are generated by a characteristic two-layer structure of temperature fluctuations under the action of a strong Q4 event or a pair of strong oblique vortices. Nevertheless, we use the bi-dimensional empirical decomposition method to split the fluctuating velocity and temperature structures into four different modes with specific spanwise length scales, and we quantify their influence on the mean WSS and WHF generation. It is shown that the mean WSS is mainly related to small-scale structures in the near-wall region, whereas the mean WHF is associated with the combined action of near-wall small-scale structures and large-scale structures in the logarithmic and outer regions.
Self-powered energy-harvesting magnetic field sensor
Authors: Hu Lizhi , Wu Hanzhou , Zhang Qianshi , You Haoran , Jiao Jie , Luo Haosu , Wang Yaojin , Gao Anran , Duan Chungang
Published: January 2022

Driven largely by the recent growth in the Internet of Things, there is a rapid surge in the demand for low-powered or self-powered sensors and devices. Here, we report a fully self-powered magnetic sensor system based on the magnetoelectric (ME) effect. This device consists of both a field-detection element and a power-generation element, which are designed using magnetostrictive Metglas amorphous ribbons and piezoelectric PMN-PT single crystal plates, respectively. The ME laminates for energy harvesting exhibit a giant resonance magnetic responsivity of 350 nC/Oe at 15 kHz. The magnetic-field sensing element shows a linear response with a high resolution up to 32 nT, and the magnetic-harvest element can reach a power of 48.68 mW/Oe at an optimum load resistance of 5 kΩ. The self-powered sensor system has shown excellent capability to convert magnetic energy into electrical energy, as demonstrated in powering a small electronic screen. The high sensitivity and power generation of our system suggest potential applications in sustainable intelligent sensor networks.
Path integral description of semiflexible active Brownian polymers
Authors: Eisenstecken Thomas , Winkler Roland G.
Published: January 2022

Semiflexible polymers comprised of active Brownian particles (ABPOs) exhibit intriguing activity-driven conformational and dynamical features. Analytically, the generic properties of ABPOs can be obtained in a mean-field description applying the Gaussian semiflexible polymer model. In this article, we derive a path integral representation of the stationary-state distribution function of such ABPOs, based on the stationary-state distribution function of the normal mode amplitudes following from the Langevin equation of motion. The path integral includes characteristic semiflexible polymer contributions from entropy and bending energy, with activity dependent coefficients, and, in addition, activity-induced torsional and higher order correlations along the polymer contour. Focusing on a semiflexible polymer approximation, we determine various properties such as the tangent-vector correlation function, effective persistence length, and the mean-square end-to-end distance. The latter reflects the characteristic features of ABPOs, and good quantitative agreement is obtained with the full solution for larger activities, specifically for flexible polymers. Moreover, the approximation indicates the relevance of torsional and higher order contour correlations for the ABPO conformations. In general, the ABPO path integral illustrates how colored noise (active fluctuations) affects semiflexible polymer conformations in comparison to white noise thermal fluctuations.
Kaolinite colloidal suspensions under the influence of sodium dodecyl sulfate
Authors: Abbasi Moud Aref , Hatzikiriakos Savvas G.
Published: January 2022

Rheological properties of kaolinite particle suspensions in water were studied in the presence of sodium dodecyl sulfate (SDS). The characterization of slightly and strongly sonicated samples revealed the impact of particle initial clustering and agglomeration on their flow behavior; findings revealed that sonicated samples exhibit a stronger network. The influence of kaolinite concentration, sonication, and SDS loading on the apparent slip of kaolinite suspensions was also studied. The presence of SDS molecules prevents particle aggregation and network formation, which leads to a gradual reduction in yield stress. Through a suggested spatial hindrance mechanism, adding SDS above the minimum amount for micelle formation also stops network formation. Finally, it was found that increasing the concentration of kaolinite and sonication reduces the apparent slip, whereas increasing the surfactant concentration increases slip significantly. As a result of shear-induced migration, adding surfactant causes the interface to deplete and thus exhibit apparent slip.
Anomalous heating in a colloidal system
Authors: Kumar Avinash , Chétrite Raphaël , Bechhoefer John
Published: January 2022

Significance

A cold system normally takes longer to warm up than a cool system. Yet recent theoretical studies have suggested that the reverse may sometimes be possible. Here, using a colloidal particle in a heat bath, we present experimental evidence for this inverse Mpemba effect. By carefully choosing the energy landscape, we can make the cold system heat up exponentially faster than the heating rate of cool systems. While similar behavior has been seen in systems that cool down—the Mpemba effect—we find that entropic effects generally make anomalous heating harder to observe than anomalous cooling.
Thermochronologic constraints on the origin of the Great Unconformity
Authors: McDannell Kalin T. , Keller C. Brenhin , Guenthner William R. , Zeitler Peter K. , Shuster David L.
Published: January 2022

Significance

The Great Unconformity involves a common gap of hundreds of millions to billions of years in the geologic record. The cause of this missing time has long eluded explanation, but recently two opposing hypotheses claim either a glacial or a plate tectonic origin in the Neoproterozoic. We provide thermochronologic evidence of rock cooling and multiple kilometers of exhumation in the Cryogenian Period in support of a glacial origin for erosion contributing to the composite basement nonconformity found across the North American interior. The broad synchronicity of this cooling signal at the continental scale can only be readily explained by glacial denudation.
The endoplasmic reticulum chaperone BiP is a closure-accelerating cochaperone of Grp94
Authors: Huang Bin , Sun Ming , Hoxie Reyal , Kotler Judy L. M. , Friedman Larry J. , Gelles Jeff , Street Timothy O.
Published: January 2022

Significance

The endoplasmic reticulum (ER) is the site at which secreted proteins (such as the hormone insulin) and membrane-bound proteins are folded. ATP-dependent chaperones within the ER help proteins fold. This study describes how two key ER chaperones, BiP and Grp94, work together at a molecular level. BiP binds to Grp94, which enables Grp94 to change conformation and hydrolyze ATP. In short, BiP provides a signal to switch on Grp94 conformational changes that are required to help other proteins fold. This finding helps explain how two chaperones can work together collaboratively in protein folding. Because BiP and Grp94 are members of highly conserved chaperone families, these findings may provide insight into chaperone-assisted protein folding beyond the ER.
Un-supervised learning for blind image deconvolution via Monte-Carlo sampling
Authors: Li Ji , Nan Yuesong , Ji Hui
Published: January 2022

Deep learning has been a powerful tool for solving many inverse imaging problems. The majority of existing deep-learning-based solutions are supervised on an external dataset with many blurred/latent image pairs. Recently, there has been an increasing interest on developing dataset-free deep learning methods for image recovery without any prerequisite on external training dataset, including blind deconvolution. This paper aims at developing an un-supervised learning method for blind image deconvolution, which does not call any training sample yet provides very competitive performance. Based on the re-parametrization of latent image using a deep network with random weights, this paper proposed to approximate the maximum-a posteriori estimator of the blur kernel using the Monte-Carlo (MC) sampling method. The MC sampling is efficiently implemented by using dropout and random noise layer, which does not require conjugate model as traditional variational inference does. Extensive experiments on popular benchmark datasets for blind image deconvolution showed that the proposed method not only outperformed existing non-learning methods, but also noticeably outperformed existing deep learning methods, including both supervised and un-supervised ones.
Compressed superhydrides: the road to room temperature superconductivity
Authors: Du Mingyang , Zhao Wendi , Cui Tian , Duan Defang
Published: January 2022

Room-temperature superconductivity has been a long-held dream and an area of intensive research. The discovery of H3S and LaH10 under high pressure, with superconducting critical temperatures (T
c) above 200 K, sparked a race to find room temperature superconductors in compressed superhydrides. In recent groundbreaking work, room-temperature superconductivity of 288 K was achieved in carbonaceous sulfur hydride at 267 GPa. Here, we describe the important attempts of hydrides in the process of achieving room temperature superconductivity in decades, summarize the main characteristics of high-temperature hydrogen-based superconductors, such as hydrogen structural motifs, bonding features, electronic structure as well as electron–phonon coupling etc. This work aims to provide an up-to-date summary of several type hydrogen-based superconductors based on the hydrogen structural motifs, including covalent superhydrides, clathrate superhydrides, layered superhydrides, and hydrides containing isolated H atom, H2 and H3 molecular units.
Boron and nitrogen co-doped carbon nanospheres for supercapacitor electrode with excellent specific capacitance
Authors: Yang Yaqi , Shao Ziqiang
Published: January 2022

At present, carbon materials derived from biomass precursors have many limitations in the field of energy storage. In this study, boron and nitrogen (B/N) co-doped carbon nanospheres are successfully prepared by emulsion crosslinking method using chitosan and boric acid as raw materials. After carbonization at high temperature, the carbon nanospheres can be facilely prepared with controllable particle size, showing excellent structural stability and sphericity. In addition, the heteroatoms co-doping endows the carbon nanospheres with large specific surface area, high graphitization degree and excellent electrochemical performance. Applying the carbon nanospheres for supercapacitors, the specific capacitance can reach up to 336.7 F g−1 at a current density of 1 A g−1. Even after 10,000 cycles, the Coulomb efficiency and specific capacitance still remain at 98.61% and 96.8%, respectively, demonstrating the great promise of B/N co-doped carbon nanospheres for the state-of-the-art supercapacitor electrodes applications.
An effective formaldehyde gas sensor based on oxygen-rich three-dimensional graphene
Authors: Zhang Shu , Pang Jinbo , Li Yufen , Ibarlucea Bergoi , Liu Yu , Wang Ting , Liu Xiaoyan , Peng Songang , Gemming Thomas , Cheng Qilin , Liu Hong , Yang Jiali , Cuniberti Gianaurelio , Zhou Weijia , Rümmeli Mark H
Published: January 2022

Three-dimensional (3D) graphene with a high specific surface area and excellent electrical conductivity holds extraordinary potential for molecular gas sensing. Gas molecules adsorbed onto graphene serve as electron donors, leading to an increase in conductivity. However, several challenges remain for 3D graphene-based gas sensors, such as slow response and long recovery time. Therefore, research interest remains in the promotion of the sensitivity of molecular gas detection. In this study, we fabricate oxygen plasma-treated 3D graphene for the high-performance gas sensing of formaldehyde. We synthesize large-area, high-quality, 3D graphene over Ni foam by chemical vapor deposition and obtain freestanding 3D graphene foam after Ni etching. We compare three types of strategies—non-treatment, oxygen plasma, and etching in HNO3 solution—for the posttreatment of 3D graphene. Eventually, the strategy for oxygen plasma-treated 3D graphene exceeds expectations, which may highlight the general gas sensing based on chemiresistors.
Optimized laser ion acceleration at the relativistic critical density surface
Authors: Göthel Ilja , Bernert Constantin , Bussmann Michael , Garten Marco , Miethlinger Thomas , Rehwald Martin , Zeil Karl , Ziegler Tim , Cowan Thomas E , Schramm Ulrich , Kluge Thomas
Published: January 2022

An effort to achieve high-energetic ion beams from the interaction of ultrashort laser pulses with a plasma, volumetric acceleration mechanisms beyond target normal sheath acceleration have gained attention. A relativistically intense laser can turn a near critical density plasma slowly transparent, facilitating a synchronized acceleration of ions at the moving relativistic critical density front. While simulations promise extremely high ion energies in this regime, the challenge resides in the realization of a synchronized movement of the ultra-relativistic laser pulse (

a
0

≳

30) driven reflective relativistic electron front and the fastest ions, which imposes a narrow parameter range on the laser and plasma parameters. We present an analytic model for the relevant processes, confirmed by a broad parameter simulation study in 1D- and 3D-geometry. By tailoring the pulse length and plasma density profiles at the front side, we can optimize the proton acceleration performance and extend the regions in parameter space of efficient ion acceleration at the relativistic density surface.
Lamination method for improved polarization-leakage current relation in HfO2-based metal/ferroelectric/insulator/semiconductor structure
Authors: Kim Yeonwoo , Min Kyung Kyu , Yu Junsu , Kwon Daewoong , Park Byung-Gook
Published: January 2022

Ever since the ferroelectricity of complementary metal-oxide semiconductor (CMOS) compatible HfO2-based materials was discovered, numerous studies have been conducted on their ferroelectric (FE) properties and device applications. In particular, pure-HfO2 FE materials without external doping have attracted considerable attention owing to their excellent robustness against variation because variations that appear in conventional doped-HfO2 FEs are not observed in electrical characteristics induced by dopant fluctuations in pure-HfO2 FEs. Studies on metal/FE/insulator/semiconductor (MFIS) stack are required to apply the ferroelectricity of pure-HfO2 to memory devices that are completely compatible with Si-based CMOS processes. In pure-HfO2 based MFIS stacks, the polarization tends to reduce with increasing thickness of the HfO2, although the leakage current diminishes. To overcome the tradeoff between the polarization and leakage current with respect to the thickness of the HfO2, an Al2O3 layer was inserted between the HfO2 layers to form a laminated FE structure. By employing the laminated FE, leakage current was effectively suppressed by the Al2O3 and lower HfO2 layers, and polarization was enhanced by the FE sum of the upper and lower HfO2 layers. Therefore, an MFIS structure with maximized polarization and minimized leakage current was successfully demonstrated using laminated FE. In addition, the feasibility of the proposed MFIS with laminated FE for nonvolatile memory device applications was confirmed by verifying the multistate operations of a FE tunnel junction.
A continuous broadband electromagnetic energy harvester based on amplitude and phase adjustments
Authors: Xu Lei , Xiang Zhihai
Published: January 2022

Broadening the bandwidth of vibration energy harvesters is a critical issue for their practical implementations. Although utilizing multi-degree-of-freedoms is a frequently used solution to widen the operating frequency range, the resultant effective bandwidth could consist of discrete peaks (existing local minimum points lower than the half-power level) if the modal amplitudes have large differences at different frequencies. To solve these problems, we designed a new electromagnetic multi-modal energy harvester, which works in a broad and continuous low-frequency bandwidth. This is achieved by attaching the magnet and the coil to a compliant frame integrated with two different kinked beams, respectively. In this way, the voltage can be generated in a continuous and wide frequency range by adjusting the amplitudes and phases of the magnet and the coil in different modes according to a proposed design requirement. Finite element results and experimental results are in good agreement with each other, which validate the performance of the proposed harvester. The experimental results demonstrate that the half-power bandwidth can be achieved in the range of 15.0 Hz and the maximum peak power is 1.56 mW at the center frequency of 40.5 Hz under base excitation of the root-mean-square acceleration of 0.24 g. The broadband and high power density feature are also validated in a random excitation test, so that this harvester has great potential for practical applications.