bluuebunny/crossref_metadata_2025_split huggingface dataset:
Imperial straightening devices in disciplinary choices of academic knowledge production
Authors: Cushing-Leubner Jenna , Engman Mel M , Ennser-Kananen Johanna , Pettitt Nicole 
Published: November 2021

AbstractIn this piece, the authors question whether critical language research, in its complex collection of researcher choices, is possible beyond the discursive imaginary of critical academic scholarship. In other words, how do (allegedly) anticolonial efforts re-orient towards contribution to the imperial record? We present three vignettes, through which we grapple with the notion that researcher choice exists within the solipsism of academia. In doing so, we frame research and scholarship as a collection of choices, which we believe are better understood as a collection of fraught dilemmas. These dilemmas recognize that all academic scholarship production and its processes are birthed from, and serve, an epistemology of hierarchical social configurations, which serve empire maintenance and expansion. As critical language scholars who bring overlapping and distinct sociopolitical, geographic, and methodological positionalities, these autoethnographic narrative vignettes allow us to begin to see the landscape of researcher choice in the processes and projects of accumulating knowledge production. We identify imperial straightening devices for legitimization into the imperial archive and examine how they work to orient and re-orient critical language scholars towards the ideological and material production of the imperial archive.
Acute performance and physiological responses to upper‐limb multi‐set exercise to failure: Effects of external resistance and systemic hypoxia
Authors: Girard Olivier , Mariotti‐Nesurini Luca , Malatesta Davide 
Published: November 2021

ABSTRACTThis study quantified performance and physiological responses during multi‐set resistance exercise to failure at light versus moderate loads in normoxia and systemic hypoxia. On separate visits, fifteen resistance‐trained adults performed barbell biceps curl exercise trials (6 sets to failure, 2 min rest between sets) in four separate randomised conditions; i.e. in normoxia at 380 m above sea level or systemic hypoxia at ∼3800 m simulated altitude (inspired oxygen fraction = 20.9% and 12.9%, respectively) combined with two different intensity levels (30% and 70% of 1 repetition maximal or 1RM). Muscle activation (root mean square value calculated from surface electromyography) and oxygenation (integrated‐tissue saturation index derived from near‐infrared spectroscopy) were monitored for the biceps brachii muscle. The total number of repetitions before failure at 30% 1RM (122 ± 5 vs. 131 ± 5; P = 0.021), but not 70% 1RM (39 ± 1 vs. 41 ± 2; P = 0.313), was lower in hypoxia compared to normoxia. Root mean square activity of the biceps brachii muscle was higher for 70% 1RM compared to 30% 1RM (P < 0.001), while the increase in muscle activation from the first to the last set (P < 0.001) occurred independently of altitude (P > 0.158). Deoxygenation and reoxygenation responses were higher under hypoxic versus normoxic conditions at 70% 1 RM (P = 0.013 and P = 0.015) but not 30% 1RM (P = 0.528 and P = 0.384). During upper‐limb multi‐set resistance exercise to failure, exposure to acute normobaric hypoxia negatively impacts performance at light, but not moderate, loads. Overall, external resistance has more profound effects on physiological strain than hypoxic exposure per se.Highlights
The addition of acute systemic hypoxia negatively affects work performed at low, but not moderate, loads during upper‐limb resistance exercise to failure.
Hypoxic exposure, however, does not fundamentally alter muscle activation and oxygenation patterns.
Muscle activation and oxygenation responses in turn are more largely influenced by load lifted.
Photon boomerang in a nearly extreme Kerr metric
Authors: Page Don N 
Published: November 2021

Abstract
The Kerr rotating black hole metric has unstable photon orbits that orbit around the hole at fixed values of the Boyer–Lindquist coordinate r that depend on the axial angular momentum of the orbit, as well as on the parameters of the hole. For zero orbital axial angular momentum, these orbits cross the rotational axes at a fixed value of r that depends on the mass M and angular momentum J of the black hole. Nonzero angular momentum of the hole causes the photon orbit to rotate so that its direction when crossing the north polar axis changes from one crossing to the next by an angle I shall call Δϕ, which depends on the black hole dimensionless rotation parameter a/M = cJ/(GM
2) by an equation involving a complete elliptic integral of the first kind. When the black hole has a/M ≈ 0.994 341 179 923 26, which is nearly maximally rotating, a photon sent out in a constant-r direction from the north polar axis at r ≈ 2.423 776 210 035 73GM/c
2 returns to the north polar axis in precisely the opposite direction (in a frame nonrotating with respect to the distant stars), a photon boomerang.
On the uniqueness of inverse problems for the reduced wave equation with unknown embedded obstacles
Authors: Yang Jiaqing , Ding Meng , Liu Keji 
Published: November 2021

Abstract
In this paper, we consider inverse problems associated with the reduced wave equation on a bounded domain

Ω
⊂

R

N

(

N
⩾
2

)

for the case where unknown obstacles are embedded in the domain Ω. We show that, if both the leading and 0-order coefficients in the equation are a priori known to be piecewise constant functions, then both the coefficients and embedded obstacles can be simultaneously recovered in terms of the local Dirichlet-to-Neumann map defined on an arbitrary small open subset of the boundary ∂Ω. The method depends on a well-defined coupled PDE-system constructed for the reduced wave equations in a sufficiently small domain and the singularity analysis of solutions near the interface for the model.
Monitoring of physiological sounds with wearable device based on piezoelectric MEMS acoustic sensor
Authors: Qu Mengjiao , Chen Xuying , Yang Dengfei , Li Dongsheng , Zhu Ke , Guo Xishan , Xie Jin 
Published: November 2021

Abstract
Physiological mechano-acoustic signals play a pivotal role in medical diagnosis and fitness monitoring. Mechanical waves generated by natural physiological activities such as myocardial contraction, and vocal fold vibration, propagate through the tissues and fluids of the body and reveal characteristic signals of these events. Conventional methods such as stethoscope and electrocardiography (ECG) are not suitable for wearable mode and continuous monitoring. In this paper, we propose a wearable physiological sounds sensing device to monitor heart sound and detect speech and voice with high accuracy. The device consists of a MEMS (microelectromechanical systems) acoustic sensor and a low-noise amplification circuit, and both of them are packaged by silicone polymers with an air cavity to achieve conformal contact with human skin. The proposed device has advantages of light weight, sweatproof capability, resistant to noise and good stability. The wearable device has great potential in clinical diagnosis, healthcare, human-machine interaction and many other applications.
Physics of effective media in plastic polymer-composites using THz Time-Domain Spectroscopy
Authors: Singh Khushboo , Bandyopadhyay Aparajita , Sengupta Amartya 
Published: November 2021

Abstract
Polymer composites have been an integral part of our lives for centuries and their applicability has increased substantially with recent technological advancements. However, with the vast range of available fillers and polymer materials, it is crucial to have a priori knowledge of the physical and chemical properties of the materials for various applications. Hence, material characterization at different stages of production is one of the most important parts of product development and quality control. In this article, we have probed the optical behavior of a few polymer composites, with absorptive and dispersive guests, using THz time-domain spectroscopy. Subsequently, we used quasi-static effective medium theory to investigate the impact of absorptive and dispersive filler materials on the optical properties of the composites. This enables us to address the significance of filler properties on the detection limits of real-life composite compounds.
Electronic-structure evolution of SrFeO3–x
during topotactic phase transformation
Authors: Zhao Jiali , Chen Kaihui , Li Shi-En , Zhang Qinghua , Wang Jia-Ou , Guo Er-Jia , Qian Haijie , Gu Lin , Qian Tian , Ibrahim Kurash , Fan Zhen , Guo Haizhong 
Published: November 2021

Abstract
Oxygen-vacancy-induced topotactic phase transformation between the ABO2.5 brownmillerite structure and the ABO3 perovskite structure attracts ever-increasing attention due to the perspective applications in catalysis, clean energy field, and memristors. However, a detailed investigation of the electronic-structure evolution during the topotactic phase transformation for understanding the underlying mechanism is highly desired. In this work, multiple analytical methods were used to explore evolution of the electronic structure of SrFeO3−x
thin films during the topotactic phase transformation. The results indicate that the increase in oxygen content induces a new unoccupied state of O 2p character near the Fermi energy, inducing the insulator-to-metal transition. More importantly, the hole states are more likely constrained to the dx
2–y
2 orbital than to the d3z
2–r
2 orbital. Our results reveal an unambiguous evolution of the electronic structure of SrFeO3–x
films during topotactic phase transformation, which is crucial not only for fundamental understanding but also for perspective applications such as solid-state oxide fuel cells, catalysts, and memristor devices.
Coal gangue recognition using multichannel auditory spectrogram of hydraulic support sound in convolutional neural network
Authors: Chen Xu , Wang Shibo , Liu Houguang , Yang Jianhua , Liu Songyong , Wang Wenbo 
Published: November 2021

Abstract
Many data-driven coal gangue recognition (CGR) methods based on the vibration or sound of collapsed coal and gangue have been proposed to achieve automatic CGR, which is important for realizing intelligent top-coal caving. However, the strong background noise and complex environment in underground coal mines render this task challenging in practical applications. Inspired by the fact that workers distinguish coal and gangue from underground noise by listening to the hydraulic support sound, we propose an auditory model based CGR method that simulates human auditory recognition by combining an auditory spectrogram with a convolutional neural network (CNN). First, we adjust the characteristic frequency (CF) distribution of the auditory peripheral model (APM) based on the spectral characteristics of collapsed sound signals from coal and gangue and then process the sound signals using the adjusted APM to obtain inferior colliculus auditory signals with multiple CFs. Subsequently, the auditory signals of all CFs are converted into gray images separately and then concatenated into a multichannel auditory spectrum (MCAS) along the channel dimension. Finally, we input the MCAS as a feature map to the two-dimensional CNN, whose convolutional layers are used to automatically extract features, and the fully connected layer and softmax layer are used to flatten features and predict the recognition result, respectively. The CNN is optimized for the CGR based on a comparison study of four typical types of CNN structures with different network training hyperparameters. The experimental results show that this method affords an accurate CGR with a recognition accuracy of 99.5%. Moreover, this method offers excellent noise immunity compared with typically used CGR methods under various noisy conditions.
A layer-peeling method for signal trapping correction in planar LII measurements of statistically steady flames
Authors: Escudero F , Cruz J J , Liu F , Fuentes A 
Published: November 2021

Abstract
This work presents a layer-peeling (LP) algorithm to correct the signal trapping effect in planar laser-induced incandescence (LII) measurements of soot volume fraction. The method is based on measurements of LII signals captured by an intensified CCD camera at a series of parallel planes across a diffusion flame. A method based on presumed function (PF) of soot volume fraction is also proposed for comparison. The presented methods are numerically tested based on synthetic LII signals emitted from a simulated axisymmetric laminar diffusion flame using the CoFlame code. Numerical results showed that the LP method is able to correct the signal trapping effect, even for fairly large optical thicknesses and in a wide range of detection wavelengths. The correction decreases the relative errors induced by neglecting the trapping effect considerably. The signal trapping effect correction is less important for the determination of integrated soot quantities such as radially integrated soot volume fraction or total soot loading. Planar LII measurements were carried out and calibrated in order to test the method experimentally in a coflow flame. The LP, PF and a simplified analytical (SA) model were compared. The results indicate that the differences in soot volume fraction of 1 ppm or about 15% are obtained in zones of maximum soot loading of 6.5 ppm when the trapping effect is accounted for. Also, the LP and SA methods were found computationally efficient and accurate compared to the PF method. Although the study was performed in a canonical laminar axisymmetric flame, the proposed method can be applied to any statistically steady 3D flame.
One-dimensional cobalt oxide nanotubes with rich defect for oxygen evolution reaction
Authors: Miao Bo-Qiang , Liu Yi-Ming , Wang Tian-Jiao , Ding Yu , Chen Yu 
Published: November 2021

Abstract
For the electrochemcial hydrogen production, the oxygen evolution reaction (OER) is a pivotal half-reaction in water splitting. However, OER suffers sluggish kinetics and high overpotential, leading to the increase of overall energy consumption and decrease of the energy efficiency. In this work, high-quality cobalt oxide porous nanotubes (Co3O4-PNTs) are easily obtained by simple self-template approach. One-dimensional (1D) porous structure provides the large specific surface area, enough abundant active atoms and effective mass transfer. In addition, Co3O4-PNTs also own self-stability of 1D architecture, benefitting the their durability for electrocatalytic reaction. Thus, Co3O4-PNTs with optimal annealing temperature and time reveal the attractive alkaline OER performance (Tafel slope of 56 mV dec−1 and 323 mV overpotential at 10 mA cm−2), which outperform the Co3O4 nanoparticles and benchmark commercial RuO2 nanoparticles. Furthermore, Co3O4-PNTs also exhibit excellent OER durability for least 10 h at the 10 mA cm−2. Overall, Co3O4-PNTs with low cost can be serve as a highly reactive and economical catalyst for OER.
MgCo layered double hydroxide-based yolk shell polyhedrons as multifunctional sulfur mediator for lithium–sulfur batteries
Authors: Zhang Kai , Li You , Wang Hongyu , Zhang Zisheng , Liu Guihua , Zhang Yongguang 
Published: November 2021

Abstract
The development of efficient sulfur host materials to address the shuttle effect issues of lithium polysulfides (LiPSs) is crucial in the lithium–sulfur (Li–S) batteries but still challenging. In the present study, a novel yolk shell structured MgCo-LDH/ZIF-67 composite is designed as Li–S battery cathode. In this composite, the shell layer is MgCo layered double hydroxide constructed by partially etching ZIF-67 nanoparticle by Mg2+, and the core is the unreacted ZIF-67 particle. The unique yolk shell structure not only provides abundant pores for sulfur accommodation, but also facilitates the electrolyte penetration and ion transport. The ZIF-67 core exhibits strong polar adsorption to LiPSs through the Lewis acid-base interactions, and the micropores/mesoporous can further trap LiPSs. Meanwhile, the MgCo-LDH shell exposes enough sulfur-philic sites for enhancing chemisorption and catalyzes LiPSs conversion. As a result, when MgCo-LDH/ZIF-67 is used as sulfur host in the cathode, the cell achieves a high discharge capacity of 1121 mAh g−1 at 0.2 C, and an areal capacity of 5.0 mAh cm−2 under high sulfur loading of 5.8 mg cm−2. The S/MgCo-LDH/ZIF-67 electrode holds a promising potential for the development of Li–S batteries.
Vortex phase diagram in 1111-type CaFe0.89Co0.11AsF single crystal
Authors: Pan Yongqiang , Zhou Wei , Feng Jiajia , Yi Xiaolei , Xu Chunqiang , Wang Minghao , Zhou Nan , Shi Zhixiang 
Published: November 2021

Abstract
Studying the vortex properties in high-T
c superconductors is crucial for understanding the high-temperature superconducting mechanism. However, until now, only a few vortex studies have been performed in 1111-type iron-based superconductors due to their smaller-sized single crystals. In this study, we have synthesized millimeter-sized CaFe0.89Co0.11AsF single crystals by the self-flux method. A three-dimensional vortex nature was confirmed in the thermally activated flux flow region. Second, a magnetization peak was observed on the isothermal magnetization curves. Meanwhile, the dominant role of normal point pinning was also confirmed. Finally, the various phase boundaries of the vortex were determined based on an analysis of the resistivity and magnetization data, and a complete vortex phase diagram of CaFe0.89Co0.11AsF single crystals was established.
Actively-shielded ultrahigh field MRI/NMR superconducting magnet design
Authors: Wang Yaohui , Wang Qiuliang , Wang Hui , Chen Shunzhong , Hu Xinning , Liu Yang , Liu Feng 
Published: November 2021

Abstract
Active shielding technology has been widely applied to the superconducting magnetic resonance imaging (MRI) and nuclear magnetic resonance (NMR) magnets design, revealing excellent performance on the stray field control. For such a highly homogeneous field superconducting magnet design, an appropriate optimization strategy is essential to guarantee the magnetic field homogeneity in the central region and the expected 5 Gauss line range, especially for the ultrahigh field superconducting magnet. Based on the compensating field optimization method, an actively-shielded whole-body 14 T MRI magnet and an actively-shielded 1.3 GHz NMR magnet were presented, and detailed analyses were conducted to evaluate the feasibility of the designs. The developed magnet design method, coil pattern, wire arrangement, and stress/strain adjustment will be used to guide the corresponding project implementation.
Brownian motion and thermophoretic diffusion effects on the dynamics of MHD upper convected maxwell nanofluid flow past a vertical surface
Authors: Shah Nehad Ali , Tosin Oreyeni , Shah Rasool , Salah Bashir , Chung Jae Dong 
Published: November 2021

Abstract
The suspension of nanoparticles in the base fluid has been tested to improve the heat transfer properties of the fluid since solid metals are characterized with higher thermal conductivity than the convectional working fluid. This present work focuses on the suspension of nanoparticles into the upper convected Maxwell fluid model (UCM) so as to improve the heat transfer efficacy of the fluid. The governing partial differential equations and their related boundary conditions are transformed and parameterized by applying appropriate transformations into a system of non-linear ordinary differential equations and the series solutions are obtained through homotopy analysis method. The impact of various parameters on velocity, temperature and nanoparticles concentration profiles are reviewed and discussed. It is discovered that increasing the Brownian motion increases the thermal conductivity of fluid and hence promotes the effective movement of the nanoparticles.
Lateral and rotary light-drag enhancement in a vee+ladder configuration comprising a Rydberg state
Authors: Hamrah Gharamaleki Ali , Kevin Amir 
Published: November 2021

Abstract
The lateral and rotary light-drag effects in a four-level vee+ladder configuration comprising a Rydberg state as the topmost level is theoretically investigated. We found that it is difficult to obtain enhanced lateral and rotary light drags accompanied by suppressed absorption in the three-level vee and ladder configurations. However, in the proposed four-level vee+ladder configuration both lateral and rotary light drags are significantly enhanced as well as suppressing the absorption of the weak probe field via electromagnetically induced transparency (EIT). The profound impacts of the intensity of the controlling fields on both the lateral and rotary light drags are discussed. It is demonstrated that intensifying the controlling fields leads to enhancing the lateral and rotary light-drag effects accompanied by negligible probe field absorption. Furthermore, it is shown that light is dragged opposite of the direction of the host medium motion while the superluminal light propagation dominates. Nevertheless, the light is dragged along the same direction of the host medium motion in the subluminal propagation condition. In addition, we present the real quantities of all the parameters used in this study for future empirical investigations.
Overlap energy role investigation on location of π and π* electronic bands in α-graphyne
Authors: Ahmadi Mohammad Taghi , Rahmatpour Esmaeil , Rahmani Meisam 
Published: November 2021

Abstract
Graphyne with outstanding properties is a promising material in technological applications such as sensors and optoelectronic devices. In this study, relaxation effect in the form of overlap energy variation on π and π* bands location of α-graphyne is investigated. Overlap energy can be controlled by external parameters such as stress and applied electric field. The Eigen values of band energy for eight possible cases based on the tight-binding model is calculated and the intertwined effect of single and double bonds energies as an overlap energy parameter is discussed. Moreover, a comparative study is done through tight-binding model and density functional theory method, which supports the accuracy of the presented model. The remarkable properties of α-graphyne mentioned in this research and obtained results bring new hopes for using of this material in nanoelectronics and optoelectronics applications.
Searching for dark matter in the Sun using Hyper-Kamiokande
Authors: Bell Nicole F. , Dolan Matthew J. , Robles Sandra 
Published: November 2021

Abstract
We study the ability of the Hyper-Kamiokande (HyperK) experiment, currently under construction, to constrain a neutrino signal produced via the annihilation of dark matter captured in the Sun. We simulate upward stopping and upward through-going muon events at HyperK,
using Super-Kamiokande (SuperK) atmospheric neutrino results for validation, together with fully and partially contained events. Considering the annihilation of dark matter to various standard model final states, we determined the HyperK sensitivity to the dark matter spin-dependent scattering cross-section. We find that HyperK will improve upon current SuperK limits by a factor of 2–3, with a further improvement in sensitivity possible if systematic errors can be decreased relative to SuperK.