bluuebunny/crossref_metadata_2025 huggingface dataset:
Hydrodynamic performance of a penguin wing: Effect of feathering and flapping
Authors: Prapamonthon Prasert
Published: June 2023

The penguin is the fastest underwater swimmer among the wing-propelled diving birds. To figure out the mechanism for its excellent swimming, the hydrodynamic performance of a penguin wing is numerically investigated using an immersed boundary method with the incompressible flow solver. This study examines the effects of feathering, flapping, and Strouhal number (St) under preset motion. Results indicate that feathering is the primary contributor to thrust generation. The change in angle of attack (AoA) can qualitatively reflect the change in lift but not thrust. Therefore, a new variable, angle of thrust (AoT, αT), is introduced to effectively reflect the change of thrust across different kinematic parameters. Optimal feathering amplitude balances the decrease in AoA and the increase in feathering angle to achieve the highest AoT and thrust. Excessive feathering amplitude degrades the leading-edge vortex to shear layers, transforms the pressure side to the suction side, and ultimately causes negative thrust (drag). Spatial analysis of the thrust shows that the outer three-fifths of the wing are the primary source of thrust, contributing 85.4% of thrust generation at optimal feathering amplitude. Flapping amplitude has little impact on the optimal feathering amplitude. The optimal feathering amplitude increases linearly with the St number in the scope of examination, leading to larger thrust but lower swimming efficiency. Thus, a dimensionless number, Stm, is introduced to describe the optimal wing motion. This work provides new insights into the propulsion mechanism of aquatic swimmers with flapping–feathering wings and helps design novel bio-inspired aquatic vehicles.
Tensile properties of ferromagnetic nanofilms on stretchable substrates: Links between multi-cracking and magnetic properties
Authors: Ben Mahmoud H. , Faurie D. , Renault P.-O. , Zighem F.
Published: June 2023

The influence of multi-cracking on the magnetic response of more (Co) or less (Ni78Fe22) magnetostrictive ferromagnetic nanofilms on flexible substrates has been studied by combining tensile tests with in situ magneto-optical Kerr effect magnetometry measurements, up to large strain (20%). The results show that the variations of the magnetic features are more significant in the elastic domain (before cracking), while they are slightly affected in the multi-cracking regime, linked to the fact that the stresses evolve relatively little in this regime. This results in a lesser modification of the magnetization curves of Ni78Fe22, which also means weak magnetostatic (dipolar) effects despite a very high crack density. This is very promising for the applicability of magnetic films in highly curved or stretched systems, especially using weakly magnetostrictive materials.
Updates to the DScribe library: New descriptors and derivatives
Authors: Laakso Jarno , Himanen Lauri , Homm Henrietta , Morooka Eiaki V. , Jäger Marc O. J. , Todorović Milica , Rinke Patrick
Published: June 2023

We present an update of the DScribe package, a Python library for atomistic descriptors. The update extends DScribe’s descriptor selection with the Valle–Oganov materials fingerprint and provides descriptor derivatives to enable more advanced machine learning tasks, such as force prediction and structure optimization. For all descriptors, numeric derivatives are now available in DScribe. For the many-body tensor representation (MBTR) and the Smooth Overlap of Atomic Positions (SOAP), we have also implemented analytic derivatives. We demonstrate the effectiveness of the descriptor derivatives for machine learning models of Cu clusters and perovskite alloys.
The vertical longitudinal magnetoresistance in a van der Waals thin film of WTe2
Authors: Liu Y. S. , Xiao H. , Zhang C. , Zhang C. W. , Shi Y. G. , Hu T. , Schneider C. M.
Published: June 2023

We report the magneto-transport measurements of thin film devices of the topological Weyl semimetal WTe2 with the applied current along and vertical to the in-plane directions. The device is composed of a van der Waals thin film of WTe2 sandwiched between top and bottom Au electrodes. At low temperatures, we observe not only a large unsaturated magnetoresistance and Shubnikov–de Haas oscillations with current in the in-plane direction but also a saturated vertical longitudinal magnetoresistance and quantum oscillations with current in the out-of-plane direction in a thin film of WTe2. Our work provides insight into the origin of the unsaturated magnetoresistance in WTe2 and may inspire non-planar engineering to reach higher integration in spintronics.
The influence of thermal cycling on the activation energy of conduction electrons and filament temperature in Pt/NiOx/Pt ReRAMs
Authors: Alagoz H. S. , Egilmez M. , Jung J. , Chow K. H.
Published: June 2023

We investigate the electrical and thermal conduction properties of low- (ON) and high-resistance (OFF) states in Pt/NiOx/Pt based unipolar ReRAM devices during cooling and warming cycles between 300 and 180 K. The conduction electron-trap activation energy was found to decrease upon warming. Although thermal cycling did not significantly affect the average resistance-temperature coefficient of the Pt diffused conductive filaments in the system, the ON-state resistance fluctuations increase at high temperatures, indicating that ambient temperature significantly affects the sizes of the formed filaments. The mechanism behind these thermally activated changes is discussed.
Using transfer coefficients to model series-connected multi-junction solar cells with radiative coupling
Authors: Strandberg Rune
Published: June 2023

When the quality of multi-junction solar cells becomes sufficiently high, radiative exchange of photons between cells must be included to properly model such devices. In this work, it is shown how constants called transfer coefficients can account for radiative coupling in series-connected multi-junction solar cells consisting of several sub-cells, which obey the single diode equation. The introduction of the transfer coefficients allows the relation between the voltage and current of the device to be expressed by a convenient closed-form expression that captures the general physics of radiatively coupled multi-junction cells analogous to how the single diode equation describes single-junction solar cells. Another advantage of this model is that it allows the short circuit current and open circuit voltage of radiatively coupled multi-junction cells to be easily calculated. The possibility of extending the model by including some non-idealities is briefly discussed.
Enhanced photocatalytic activity of liquid phase exfoliated WS2 nanosheets
Authors: Dahal Arjun
Published: June 2023

Due to their large surface area and novel electronic properties, tungsten disulfide (WS2) nanosheets are promising materials for potential photocatalysis applications. The fabrication of large-scale WS2 nanosheets is a fundamentally important step to realize their applications. The liquid phase exfoliation method, which involves the mechanical exfoliation of layered materials in a solvent, has proven to be a feasible technique for fabricating nanosheets with high yields. Here, we systematically examine the optimization of the fabrication of WS2 nanosheets by exfoliating the WS2 powder in isopropyl alcohol, a low boiling point solvent, using a low-power probe sonicator and ball milling method. We show that prolonged sonication produces a concentration as high as 0.64 mg/ml, and the same concentration can be fabricated in less than half the time if the bulk powder is ball milled prior to the sonication. An atomic force microscopy study reveals that the proportions of monolayers and bilayers can be significantly increased if the nanosheet dispersions are centrifuged at a higher speed or sonicated for a long time. The photodegradation measurements reveal that the decomposition rate of methyl orange with nanosheets is at least 10% higher than that with WS2 powder, suggesting that the photocatalytic activity of WS2 can be enhanced if it is reduced to nanosheets.
Spin current generation from an epitaxial tungsten dioxide WO2
Authors: Ueda Kohei , Fujii Hayato , Kida Takanori , Hagiwara Masayuki , Matsuno Jobu
Published: June 2023

We report on efficient spin current generation at room temperature in rutile-type WO2 grown on an Al2O3(0001) substrate. The optimal WO2 film has a (010)-oriented monoclinically distorted rutile structure with metallic conductivity due to 5d2 electrons, as characterized by x-ray diffraction, electronic transport, and x-ray photoelectron spectroscopy. By conducting harmonic Hall measurement in a Ni81Fe19/WO2 bilayer, we estimate two symmetries of the spin–orbit torque (SOT), i.e., dampinglike (DL) and fieldlike ones, to find that the former is larger than the latter. By comparison with the Ni81Fe19/W control sample, the observed DL SOT efficiency ξDL of WO2 (+0.174) is about two-thirds of that of W (−0.281) in magnitude, with a striking difference in their signs. The magnitude of the ξDL of WO2 exhibits a comparable value to those of widely reported Pt and Ta, and Ir oxide IrO2. The positive sign of the ξDL of WO2 can be explained by the preceding theoretical study based on the 4d oxides. These results highlight that the epitaxial WO2 offers a great opportunity of rutile oxides with spintronic functionalities, leading to future spin–orbit torque-controlled devices.
Effect of memory behavior on electric-field-induced phase transition and electrocaloric response in antiferroelectric ceramics
Authors: Li Junjie , Yin Ruowei , Hou Yuxuan , Su Xiaopo , Zhuo Fangping , Li Jianting , Zhang Xing , Wu Wenjuan , Li Lezhong , Bai Yang
Published: June 2023

Field-induced phase transition in antiferroelectric (AFE) materials always facilitates giant positive/negative electrocaloric (EC) responses for a promising cooling application, while it is not only associated with external field conditions but also applied field history, i.e., memory behavior. Herein, we demonstrate that memory behavior increases the likelihood of observing an EC response when the operating field is parallel to the pre-poling field, as compared to the antiparallel condition. Additionally, when the temperature is slightly above the AFE-ferroelectric (FE) phase transition temperature, the field-off process induces a two-step microstructure change, characterized by a rapid domain rotation followed by a slow phase transition, which finally produces an abnormal EC heat flow signal. Through a Landau theory analysis, this kinetic behavior is contributed to the competition between the ferroelectric (FE) order pinned by memory behavior and the thermal agitation favored AFE state. This work deepens the understanding of the phase transition in the ferroelectric system.
Polarization-insensitive composite gradient-index metasurface array for microwave power reception
Authors: Yang Qiang , Xiong Han , Deng Jia-Hao , Wang Ben-Xin , Peng Wen-Xiong , Zhang Huai-Qing
Published: June 2023

A composite gradient-index metasurface (C-GM) array for microwave power reception (MPR) operating at 5.8 GHz center frequency was introduced. The array is insensitive to the polarization of incident plane waves and possesses cosine gradient modulation characteristics, which can convert the incident plane waves into surface waves focused at the center of the array. The focused surface wave energy is then collected by an omnidirectional antenna and fed back to a single rectifier for radio frequency (RF) to direct current (DC) conversion, resulting in DC output. Simulation results show that the array can fully excite surface waves under different polarized plane wave excitations, and the omnidirectional antenna has good matching characteristics with the array, achieving an energy collection efficiency of 66.52%. The array was fabricated and measured, achieving an energy reception efficiency of 59.91% and an RF-DC conversion efficiency of 34.83%, which is consistent with the simulation results. The proposed C-GM array can capture higher electromagnetic power by simply increasing its size, without the need for additional rectifiers or complex matching networks, making it a flexible and efficient MPR solution for different application scenarios.
On the nonlinear dynamics of large scale dust-acoustic solitary waves in a superthermal bi-ion dusty ionospheric magnetoplasma
Authors: Shahzad M. , Imtiaz N. , Rizvi H. , Masood W. , Alrowaily Albandari W. , Ismaeel Sherif. M. E. , El-Tantawy S. A.
Published: June 2023

The purpose of this study is to examine the properties of the dust-acoustic solitary waves in a complex magnetoplasma made up of negatively charged moving dust grains in the lower ionospheric region and inertialess electrons and ions obeying Maxwell and kappa distributions, respectively. In this context, the reductive perturbation technique is carried out to obtain the Zakharov–Kuznetsov (ZK) equation within the given framework. The obtained evolution equation, i.e., ZK equation is transformed to a planar dynamical system for studying the qualitative behavior of the solitary waves. The impact of important physical parameters, such as the dust number density, ion concentration, ion temperature, superthermality, and the background magnetic field, on the profile of the nonlinear structures is numerically investigated. The findings may be utilized to comprehend the low-frequency irregularities that are detected in the lower ionosphere.
The use of rope bridges to study the colonisation of restored rainforest habitat by arboreal mammals
Authors: Heise-Pavlov Sigrid
Published: June 2023

This study tested the utility of a rope bridge across a road that traversed restored rainforest habitat (5–8 years old) to assess the use of these new habitats by arboreal mammals. Camera-trapping revealed common brushtail possums (Trichosurus vulpecula), green ringtail possums (Pseudochirops archeri) and Herbert River ringtail possums (Pseudochirulus herbertensis) used the rope bridge regularly while striped possums (Dactylopsila trivirgata), fawn-footed melomys (Melomys cervinipes), long-tailed pygmy-possums (Cercartetus caudatus) and Lumholtz’s tree-kangaroos (Dendrolagus lumholtzi) were recorded at the bridge accesses, but no crossings could be proven. No Lemuroid ringtail possums (Hemibelideus lemuroides) were recorded near the rope bridge. Differences in the use of the restored rainforest habitat and the crossing structure are likely to be caused by differences in the species’ reliance on features in mature forests, and their responses to rainforest edges. The results support the utility of canopy crossing structures to facilitate the use of restored habitat by arboreal mammals.
Harnessing αβ T cell receptor mechanobiology to achieve the promise of immuno-oncology
Authors: Reinherz Ellis L. , Hwang Wonmuk , Lang Matthew J.
Published: June 2023

T cell receptors (TCR) on cytolytic T lymphocytes (CTLs) recognize "foreign" antigens bound in the groove of major histocompatibility complex (MHC) molecules (H-2 in mouse and HLA in human) displayed on altered cells. These antigens are peptide fragments of proteins derived either from infectious pathogens or cellular transformations during cancer evolution. The conjoint ligand formed by the foreign peptide and MHC, termed pMHC, marks an aberrant cell as a target for CTL-mediated destruction. Recent data have provided compelling evidence that adaptive protection is achieved in a facile manner during immune surveillance when mechanical load consequent to cellular motion is applied to the bond formed between an αβ TCR and its pMHC ligand arrayed on a disease-altered cell. Mechanobiology maximizes both TCR specificity and sensitivity in comparison to receptor ligation in the absence of force. While the field of immunotherapy has made advances to impact the survival of cancer patients, the latest information relevant to T cell targeting and mechanotransduction has yet to be applied for T cell monitoring and treatment of patients in the clinic. Here we review these data, and challenge scientists and physicians to apply critical biophysical parameters of TCR mechanobiology to the medical oncology field, broadening treatment success within and among various cancer types. We assert that TCRs with digital ligand-sensing performance capability directed at sparsely as well as luminously displayed tumor-specific neoantigens and certain tumor-associated antigens can improve effective cancer vaccine development and immunotherapy paradigms.
Prolonged thermocline warming by near-inertial internal waves in the wakes of tropical cyclones
Authors: Gutiérrez Brizuela Noel , Alford Matthew H. , Xie Shang-Ping , Sprintall Janet , Voet Gunnar , Warner Sally J. , Hughes Kenneth , Moum James N.
Published: June 2023

Turbulence-enhanced mixing of upper ocean heat allows interaction between the tropical atmosphere and cold water masses that impact climate at higher latitudes thereby regulating air–sea coupling and poleward heat transport. Tropical cyclones (TCs) can drastically enhance upper ocean mixing and generate powerful near-inertial internal waves (NIWs) that propagate down into the deep ocean. Globally, downward mixing of heat during TC passage causes warming in the seasonal thermocline and pumps 0.15 to 0.6 PW of heat into the unventilated ocean. The final distribution of excess heat contributed by TCs is needed to understand subsequent consequences for climate; however, it is not well constrained by current observations. Notably, whether or not excess heat supplied by TCs penetrates deep enough to be kept in the ocean beyond the winter season is a matter of debate. Here, we show that NIWs generated by TCs drive thermocline mixing weeks after TC passage and thus greatly deepen the extent of downward heat transfer induced by TCs. Microstructure measurements of the turbulent diffusivity (

κ

) and turbulent heat flux (
J

q

) in the Western Pacific before and after the passage of three TCs indicate that mean thermocline values of

κ

and
J

q

increased by factors of 2 to 7 and 2 to 4 (95% confidence level), respectively, after TC passage. Excess mixing is shown to be associated with the vertical shear of NIWs, demonstrating that studies of TC–climate interactions ought to represent NIWs and their mixing to accurately capture TC effects on background ocean stratification and climate.
Conformational switching and flexibility in cobalamin-dependent methionine synthase studied by small-angle X-ray scattering and cryoelectron microscopy
Authors: Watkins Maxwell B. , Wang Haoyue , Burnim Audrey , Ando Nozomi
Published: June 2023

Cobalamin-dependent methionine synthase (MetH) catalyzes the synthesis of methionine from homocysteine and 5-methyltetrahydrofolate (CH
3
-H
4
folate) using the unique chemistry of its cofactor. In doing so, MetH links the cycling of
S
-adenosylmethionine with the folate cycle in one-carbon metabolism. Extensive biochemical and structural studies on
Escherichia coli
 MetH have shown that this flexible, multidomain enzyme adopts two major conformations to prevent a futile cycle of methionine production and consumption. However, as MetH is highly dynamic as well as both a photosensitive and oxygen-sensitive metalloenzyme, it poses special challenges for structural studies, and existing structures have necessarily come from a “divide and conquer” approach. In this study, we investigate
E. coli
MetH and a thermophilic homolog from
Thermus filiformis
using small-angle X-ray scattering (SAXS), single-particle cryoelectron microscopy (cryo-EM), and extensive analysis of the AlphaFold2 database to present a structural description of the full-length MetH in its entirety. Using SAXS, we describe a common resting-state conformation shared by both active and inactive oxidation states of MetH and the roles of CH
3
-H
4
folate and flavodoxin in initiating turnover and reactivation. By combining SAXS with a 3.6-Å cryo-EM structure of the
T. filiformis
MetH, we show that the resting-state conformation consists of a stable arrangement of the catalytic domains that is linked to a highly mobile reactivation domain. Finally, by combining AlphaFold2-guided sequence analysis and our experimental findings, we propose a general model for functional switching in MetH.
Rapid production of kilogram-scale graphene nanoribbons with tunable interlayer spacing for an array of renewable energy
Authors: Liu Fan , Hu Yi , Qu Zehua , Ma Xin , Li Zaifeng , Zhu Rui , Yan Yan , Wen Bihan , Ma Qianwen , Liu Minjie , Zhao Shuang , Fan Zhanxi , Zeng Jie , Liu Mingkai , Jin Zhong , Lin Zhiqun
Published: June 2023

Graphene nanoribbons (GNRs) are widely recognized as intriguing building blocks for high-performance electronics and catalysis owing to their unique width-dependent bandgap and ample lone pair electrons on both sides of GNR, respectively, over the graphene nanosheet counterpart. However, it remains challenging to mass-produce kilogram-scale GNRs to render their practical applications. More importantly, the ability to intercalate nanofillers of interest within GNR enables in-situ large-scale dispersion and retains structural stability and properties of nanofillers for enhanced energy conversion and storage. This, however, has yet to be largely explored. Herein, we report a rapid, low-cost freezing–rolling–capillary compression strategy to yield GNRs at a kilogram scale with tunable interlayer spacing for situating a set of functional nanomaterials for electrochemical energy conversion and storage. Specifically, GNRs are created by sequential freezing, rolling, and capillary compression of large-sized graphene oxide nanosheets in liquid nitrogen, followed by pyrolysis. The interlayer spacing of GNRs can be conveniently regulated by tuning the amount of nanofillers of different dimensions added. As such, heteroatoms; metal single atoms; and 0D, 1D, and 2D nanomaterials can be readily in-situ intercalated into the GNR matrix, producing a rich variety of functional nanofiller-dispersed GNR nanocomposites. They manifest promising performance in electrocatalysis, battery, and supercapacitor due to excellent electronic conductivity, catalytic activity, and structural stability of the resulting GNR nanocomposites. The freezing–rolling–capillary compression strategy is facile, robust, and generalizable. It renders the creation of versatile GNR-derived nanocomposites with adjustable interlay spacing of GNR, thereby underpinning future advances in electronics and clean energy applications.
A multifunctional copper single-atom electrocatalyst aerogel for smart sensing and producing ammonia from nitrate
Authors: Li Panpan , Liao Ling , Fang Zhiwei , Su Gehong , Jin Zhaoyu , Yu Guihua
Published: June 2023

Despite modern chemistry’s success in providing affordable fertilizers for feeding the population and supporting the ammonia industry, ineffective nitrogen management has led to pollution of water resources and air, contributing to climate change. Here, we report a multifunctional copper single-atom electrocatalyst-based aerogel (Cu SAA) that integrates the multiscale structure of coordinated single-atomic sites and 3D channel frameworks. The Cu SAA demonstrates an impressive faradaic efficiency of 87% for NH
3
synthesis, as well as remarkable sensing performance with detection limits of 0.15 ppm for NO
3
−
and 1.19 ppm for NH
4
+
. These multifunctional features enable precise control and conversion of nitrate to ammonia in the catalytic process, facilitating accurate regulation of the ammonium and nitrate ratios in fertilizers. We thus designed the Cu SAA into a smart and sustainable fertilizing system (SSFS), a prototype device for on-site automatic recycling of nutrients with precisely controlled nitrate/ammonium concentrations. The SSFS represents a forward step toward sustainable nutrient/waste recycling, thus permitting efficient nitrogen utilization of crops and mitigating pollutant emissions. This contribution exemplifies how electrocatalysis and nanotechnology can be potentially leveraged to enable sustainable agriculture.
Indexing turn-beginnings in Norwegian Sign Language conversation
Authors: Ferrara Lindsay
Published: June 2023

It is well known that signers and speakers routinely produce finger points during interaction. While the
referential functions of such finger points have received great attention from researchers, they are also used to manage
interactions between interlocutors. These functions are less understood and have received less research focus. The current study
helps to redress this gap in the literature by investigating how finger pointing is used to index and coordinate turn-beginnings
in a corpus of 11 semi-naturalistic (Norwegian) signed language conversations, involving between two to five signers (3.4 hours of
signing). The data was initially annotated in ELAN and then further qualitative analysis was conducted. This investigation
revealed that finger pointing effectively indexes previous and upcoming discourse, thereby binding sequences of conversational
moves and guiding their trajectory, helping signers to coordinate turn transitions and interaction as it unfolds.
« Sarà primavera dai ». L’uso della particelladaiin italiano e in dialetto trevigiano
Authors: Pauletto Franco , Ursi Biagio
Published: June 2023

This conversation analytic study aims to describe the actions performed by speakers of Italian and Trevigiano – a northern Italian dialect – by using the particledaiin everyday conversations. Our analyses draw on a corpus of formal and informal phone calls, wheredaiappears as preface and at the end of turns that initiate new courses of action, at the end of some responsive turns (or Turn-Constructional Units) and in post-expansions (that is, turns in third position). The actions embodied by these turns – requests, proposals and assessments – have in common the momentary deontic imbalance in favor of the speaker, who tells, asks or proposes to the coparticipant to do something. The particle also accompanies assessments of events to which the speaker has no direct experience (thus from an epistemically subordinate position). This study highlights the fuzziness of the boundaries between deontic and epistemic rights in everyday talk.
Powder flowability characterisation at preheating temperature in additive manufacturing
Authors: Zhang Jiangtao , Liu Peng
Published: June 2023

The powder spreading process is usually performed at preheating temperature in powder-bed-based additive manufacturing (AM). Thus, the powder flowability characterisation at preheating temperature is important for powder spreading processes. However, devices for traditional powder flowability characterising methods are mainly designed for specific conditions at room temperature and cannot consider the effect of temperature on powder flowability. In this work, an experimental platform with a heated rotating drum was set up and a high-speed camera was used to record powder avalanche processes in a heated rotating drum for the powder flowability characterisation at preheating temperature. Nylon and stainless steel powder flowability at different temperatures was assessed by the statistical analysis of avalanche angle, avalanche time, arithmetic mean deviation and surface linearity of powder surface profile. Four parameters provide a good characterisation of powder flowability. The results can provide guidance for the powder flowability characterisation method at preheating temperature in AM.
“11 for Health” in China – Effects on physical fitness in 9–11‐year‐old schoolchildren
Authors: Li Zhen , Krustrup Peter , Randers Morten Bredsgaard , Xu Bo , Yang Weixin , Huang Zhixiong , Mao Lijuan
Published: June 2023

Previous studies have shown that the school‐based physical activity programme entitled “11 for Health” has been effective in improving the physical fitness, well‐being and overall health profile of European children. The main purpose of the present study was to examine whether the “11 for Health” programme can have a positive impact on the physical fitness of primary school pupils in China. A total of 124 primary school pupils aged 9–11 years were included in the experiment, randomly divided into the experimental group (EG, n = 62) and the control group (CG, n = 62). EG carried out three weekly 35‐minute sessions of small‐sided football for a total of 11 weeks. All data were analysed by a mixed ANOVA with the Student–Newman–Keuls post hoc test. The results showed greater improvements (p<0.001) in EG than CG in relation to systolic blood pressure (−2.9 vs +2.0 mmHg). Moreover, greater improvements (all p<0.05) were observed in postural balance (13 vs 0%), standing long jump (5.0 vs 0.5%), 30‐metre sprint (4.1 vs 1.3%) and Yo‐Yo IR1C running performance (17% vs 6%). In both EG and CG, physical activity enjoyment was observed to be higher (P<0.05) compared to the start of the intervention with increases of 3.7 and 3.9 AU respectively. In conclusion, the study revealed that the “11 for Health” programme has positive effects on aerobic and muscular fitness, and it appears to be a relevant tool in the physical activity promotion in the Chinese school system.
A multi-dimensional nonlinear optimisation method for the TianQin constellation
Authors: Zhang Zheng , Gu Defeng , Zhang Xuefeng , Ye Bobing , Ding Yangyu , Wei Chunbo , Shao Kai , Zhu Jubo
Published: June 2023

TianQin is a geocentric space-based gravitational wave detecting mission that relies on three drag-free spacecraft with a mean inter-spacecraft distance of approximately 1.7 × 105 km. Considering the efficiency requirement of orbit optimisation, we apply a gradient descent method based on variational gradient calculation and the damped Newton iterative method to find the most stable solution of the constellation near the given initial position and velocity of the spacecraft. The efficiency was improved and the number of orbital integrals required for gradient calculation was significantly reduced by over 83%. Based on this optimisation method, we analysed the influence of perturbation on the stability of the TianQin constellation, and Moon’s three-body perturbation was the main factor. In addition, the influence of the orbit elements on the optimisation results was studied. The influence of the initial mean anomaly can be ignored, and the stability of the optimised constellation decreases with an increase in the semi-major axis. Working in the ‘3 months on +3 months off’ observation scheme for 2 years, the optimisation result is the ideal direction when the normal direction of the orbital plane of the TianQin constellation points to RXJ0806.3 + 1527.
Scale invariant curvature perturbations from a spontaneously decaying scalar field
Authors: Lieu R , Shi C-H
Published: June 2023

The evolution of superhorizon curvature perturbations in a two-component interacting Universe is considered. It is found that adiabatic modes conserve the total curvature perturbation

ζ

, unless there are stages in which the rate of dissipation of one component into another is not constant. Moreover, our result shows that when the rate is varying it is possible for ‘isocurvature’ perturbations generated during reheating to alter the amplitude of an adiabatic curvature mode even when the mode is outside the horizon. Specifically, if an indefinitely large rate Γ for massive particles decaying into photons develops rapidly amid vanishingly small initial values (before decay) of the total curvature

ζ
i

and Newtonian potential

Φ
i

, such that the product

Γ

ζ
i

and

Γ

Φ
i

become a pair of finite and universal constants for all superhorizon scales afterwards, Harrison–Zel’dovich scale-invariant power spectrum could be synthesized from a homogeneous state without inflation at all.
Role of polarization switching and domain patterns in the enhanced piezoelectric characteristics of a Pb-free ferroelectric system
Authors: Roy Pranab Kumar , Priya K Shanmuga , Nayak Sanjib , Murugavel P
Published: June 2023

The Pb-free piezoelectric BaTi1−x
Sn
x
O3 system is a promising environmentally friendly ceramic due to its superior piezoresponse properties. The enhanced piezoresponse of this system has a strong correlation with its microscopic and macroscopic characteristics. In this work, the effects of structural and microstructural evolution on the piezoelectric properties of a BaTi0.97Sn0.03O3 (BST) compound are explored. Structural and piezoelectric analysis elucidates that the samples experiencing a field induced tetragonal to orthorhombic phase transformation exhibit better piezoresponse. In addition, the domain configurations have a strong correlation with the synthesis conditions, where the distribution of lamellar and/or stripe types of domain patterns show enhancement in comparison to those of labyrinth type with increase in sintering temperature. Rayleigh analysis confirms that the increase in the irreversible nature of non-180° domain walls can improve the d
33 values of the BST samples. Overall, the results illustrate that the stripe domain configurations and field induced polarization switching from tetragonal to orthorhombic phase favour superior piezoresponse in the samples.
Polarization-sensitive-metasurface-based microwave computational ghost imaging
Authors: He Yuchen , Yu Jianming , Zhu Shitao , Chen Xiaoming , Zhang Anxue , Xu Zhuo
Published: June 2023

Conventional multi-transmitter-based microwave computational ghost imaging (MCGI) systems have suffered from radiation source errors due to the limitation of unit performance in arrays. Radiation source errors can cause inaccuracy of the reference radiation field in MCGI, which will reduce the reconstruction quality of the target image. In this paper, a detailed error analysis of radiation sources in MCGI systems is conducted. The relationships between radiation source errors, reference radiation field and imaging results are determined. Furthermore, to mitigate the influence of radiation source error and other problems in conventional MCGI systems, such as high cost, complex design and implementation, and the interference between array elements, an improved MCGI method based on a broadband polarization-sensitive-metasurface is proposed. The metasurface in this work can modulate the incident signal and distribute the reflected signal randomly in space. Therefore, by changing the polarization angle of the radiation signal, a time-space independent signal is produced, which can achieve better detection effects in the application system. A series of simulations and experiments are performed to validate the analysis results and evaluate the proposed method’s performance. The results show that the target information can be effectively obtained by the proposed method.
Dark photon effect on the rare kaon decay KL⃗π0νν¯
Authors: Wang Xuan-Gong , Thomas A W
Published: June 2023

We present an analysis of the effect of a dark photon on the rare kaon decayKL→π0νν¯. All relevant couplings of the dark photon to the standard model particles are derived explicitly in terms of the dark photon mass and the mixing parameter. We find that the dark photon yields no more than a few percent correction to the standard model branching ratioBr(KL→π0νν¯)in the region of interest.
A phase transition model in dual-amorphous water undergoing liquid–liquid transition
Authors: Li Peizhao , Lu Haibao , Fu Yong-Qing
Published: June 2023

An in-depth understanding of liquid–liquid phase transition (LLPT) in condensed water will gain insight into anomalous behaviors of dual-amorphous condensed water. Despite numerous experimental, molecular simulation, and theoretical studies, it is yet to achieve a widely accepted consensus with convinced evidence in the condensed matter physics for two-state liquid–liquid transition of water. In this work, a theoretical model is proposed based on the Avrami equation, commonly used to describe first-order phase transitions, to elucidate complex homogeneous and inhomogeneous condensation from high-density liquid (HDL) water to low-density liquid (LDL) water for both pure and ionic dual-amorphous condensed water. This model unifies the coupling effects of temperature and electrolyte concentration based on the new theoretical framework. The Adam–Gibbs theory is then introduced to characterize the synergistic motion and relaxation behavior of condensed water. Variations in the configurational entropy under electrostatic forces are further explored, and an analytical 2D cloud chart is developed to visualize the synergistic effect of temperature and electrolyte concentration on the configurational entropy of ionic water. The constitutive relationships among viscosity, temperature, and electrolyte concentration are derived to analyze their synergistic effects under different condensation fractions of LDL and HDL. The Stokes–Einstein relation and free volume theory are further used to analyze diffusion coefficients and densities (or apparent density) during both pure and ionic LLPT. Finally, theoretical results obtained from these models are compared with experimental results reported in literature to validate the accuracy and applicability of the proposed models, which offer significant benefits and advancements in effectively predicting physical property changes of dual-amorphous condensed water.
Health risks from radioactive particles on Cumbrian beaches near the Sellafield nuclear site
Authors: Harrison John D , Oatway Wayne B , Brown Iain K , Hopewell John W
Published: June 2023

A monitoring programme, in place since 2006, continues to recover radioactive particles (<2 mm diameter) and larger objects from the beaches of West Cumbria. The potential risks to members of the public using the beaches are mainly related to prolonged skin contact with or the inadvertent ingestion of small particles. Most particles are classified as either ‘beta-rich’ or ‘alpha-rich’ and are detected as a result of their caesium-137 or americium-241 content. Beta-rich particles generally also contain strontium-90, with 90Sr:137Cs ratios of up to about 1:1, but typically <0.1:1. Alpha-rich particles contain plutonium isotopes, with Pu:241Am α ratios usually around 0.5–0.6:1. ‘Beta-rich’ particles have the greatest potential to cause localised skin damage if held in stationary contact with the skin for prolonged periods. However, it is concluded that only particles of >106Bq of 137Cs, with high 90Sr:137Cs ratios, would pose a significant risk of causing acute skin ulceration. No particles of this level of activity have been found. Inadvertent ingestion of a particle will result in the absorption to blood of a small proportion of the radionuclide content of the particle. The subsequent retention of radionuclides in body organs and tissues presents a potential risk of the development of cancer. For ‘beta-rich’ particles with typical activities (mean 2 × 104 Bq 137Cs, Sr:Cs ratio of 0.1:1), the estimated committed effective doses are about 30 µSv for adults and about 40 µSv for 1 year old infants, with lower values for ‘alpha-rich’ particles of typical activities. The corresponding estimates of lifetime cancer incidence following ingestion for both particle types are of the order of 10−6 for adults and up to 10−5 for infants. These estimates are subject to substantial uncertainties but provide an indication of the low risks to members of the public.
Quantitative gas property measurements by filtered Rayleigh scattering: a review
Authors: Ground Cody R , Hunt Robin L , Hunt Gregory J
Published: June 2023

Filtered Rayleigh scattering (FRS) is a laser-based diagnostic technique used to nonintrusively quantify various thermodynamic properties of a light-scattering gas. The backbone of FRS is the molecular filtering of Rayleigh scattered light. This concept was initially introduced by the atmospheric LIDAR community before being adopted within the aerospace research field in the early 1990s. Since then, FRS has matured into a versatile quantitative diagnostic tool and has found use in a variety of flow regimes ranging from sub- to supersonic speeds in both reacting and nonreacting environments. This adoption can be attributed to the wealth of information that can be obtained via FRS, including the gas density, pressure, temperature, velocity, species composition, or, in some cases, several of these properties at once. This article reviews the current state of FRS methodology in recovering such gas properties. As knowledge of the fundamentals of Rayleigh scattering and spectral light filtering is crucial to the design of an FRS experiment, we begin by briefly reviewing these areas. Subsequently, we conduct a survey of experimental design strategies, assumptions, and data reduction methods used to measure different gas properties using FRS. We conclude the review with a short discussion on quantification of experimental uncertainty and future trends in FRS.
Super-resolution reconstruction method of ground penetrating radar signals based on wavelet theory and its application in reverse time migration
Authors: Liu Xianjun , Ling Tonghua , He Wenchao , Zhang Liang , Bin Yu , Hua Fei , Liu Wenjun
Published: June 2023

The finite difference time domain (FDTD) method was used to solve the Maxwell’s equation to obtain the reverse time migration (RTM) of ground penetrating radar (GPR) signals, namely, the FDTD-RTM. In order to ensure that the correct numerical solution of iterative calculation was achieved, it was necessary to obtain high-resolution signals, which greatly limits the applicability of FDTD-RTM in engineering. Based on the characteristics of wavelet multi-resolution analysis, this study proposed a super-resolution signal reconstruction method to improve signal resolution, with the view to completely solving the problem of FDTD-RTM limitation caused by insufficient signal sampling using GPR. The results of electromagnetic simulation showed that the signals reconstructed by the above method were highly similar to the signals sampled with the same resolution. On this basis, reverse time migration electromagnetic simulation and physical model tests were designed. The results of both experiments showed that the under-sampled GPR signals could achieve FDTD-RTM following super-resolution reconstruction, and that the migration imaging results of the target were basically consistent with the design scheme. The signal super-resolution reconstruction method based on the wavelet theory was thus shown to successfully achieve the overall application of FDTD-RTM in GPR signal analysis.
Ab-initio study about the electronic structure, optical, and transport properties of novel AIn2O4 (A = Ca, Sr, and Na) materials
Authors: Gul Banat , Salman Khan Muhammad , Khan Gulzar , Ahmad Hijaz
Published: June 2023

Here, using first-principles calculations within the framework of density functional theory, we reported results relating to the structural stability, electronic, optical, and thermoelectric properties of AIn2O4 (A = Ca, Sr, and Na) spinel oxides. Among the three materials CaIn2O4, and NaIn2O4 have a direct bandgap semiconductor nature, whereas the SrIn2O4 shows an indirect bandgap semiconductor nature. These materials’ broad energy bandgaps reveal that the bonds present are strongly covalent in nature. The results of the band structures are also strongly supported by the calculated density of states for the three materials, which also validates their semiconducting nature. Our calculated density of states plots shows an overall similarity trend, indicating that the top of the valence bands in the CaIn2O4 materials originate primarily from the p-states and for SrIn2O4, and NaIn2O4 are due to the s-states of the oxygen anions. Additionally, the linear optical constants like the complex dielectric function, the refractive index, the electron energy loss function, the absorption coefficient, and the reflectivity spectra of these novel spinel oxides are computed and examined in detail for their possible applications in optoelectronic devices. The thermoelectric transport parameters were also calculated, and the findings obtained are presented in depth, indicating that these materials are suitable for thermoelectric device applications. Essentially, the present effort must assist the progress of discrete and integrated semiconductor device applications.
Dynamic residual Kaczmarz method for noise reducing reconstruction in magnetic particle imaging
Authors: Zhang Peng , Liu Jie , Li Yimeng , Zhu Tao , Yin Lin , An Yu , Zhong Jing , Hui Hui , Tian Jie
Published: June 2023

Objective. Here, we propose a dynamic residual Kaczmarz (DRK) method as an improved reconstruction method for magnetic particle imaging (MPI) to achieve a better reconstruction quality from high-noise signals. Approach. Based on the Kaczmarz (KZ) method, we introduced a residual vector to select parts of the low-noise equations for reconstruction. In each iteration, a low-noise subset was formulated based on the residual vector. Thus, the reconstruction converged to an accurate result with less noise. Main Results. To evaluate the performance of the proposed method, it was compared with classical Kaczmarz-type methods and state-of-the-art regularization models. The numerical simulation results demonstrate that the DRK method can achieve better reconstruction quality than all other comparison methods at similar noise levels. It can acquire a signal-to-background ratio (SBR) that is five times higher than that of classical Kaczmarz-type methods at a 5 dB noise level. Furthermore, the DRK method can acquire up to 0.7 structural similarity (SSIM) indicators at a 5 dB noise level when combined with the non-negative fused Least absolute shrinkage and selection operator (LASSO) regularization model. In addition, a real experiment based on the OpenMPI data set validated that the proposed DRK method can be applied to real data and perform well. Significance. The experimental results demonstrate that the proposed DRK method can significantly improve the reconstruction quality of MPI when the signals contain high noise. It has the potential to be applied to MPI instruments that contain high signal noise, such as human-sized MPI instruments. It is beneficial for expanding the biomedical applications of MPI technology.
Cross-correlation power spectra and cosmic birefringence of the CMB via photon-neutrino interaction
Authors: Mohammadi Roohollah , Khodagholizadeh Jafar , Sadegh Mahdi , Vahedi Ali , Xue S.S.
Published: June 2023

In the context of the standard model of particles, the weak interaction of cosmic
microwave background (CMB) and cosmic neutrino background (CνB), can generate non-vanishing TB and EB power spectra in the order of one loop forward scattering, in the presence of scalar perturbation, which is in contrast
with the standard scenario cosmology.
Comparing our results with the current experimental data may provide, significant information about the nature of CνB, including CMB-CνB forward scattering for TB, TE, and EB power spectra. To this end, different cases were studied, including Majorana CνB and Dirac CνB. On the other hand, it was shown that the mean opacity due to cosmic neutrino background could behave as an anisotropic birefringent medium and change the linear polarization rotation angle. Considering the contributions from neutrino and anti-neutrino forward scattering with CMB photons (in the case of Dirac neutrino), we introduce relative neutrino and anti-neutrino density asymmetry (δν
= Δnν
/nν
= nν
-nν̅
/nν
). Then, using the cosmic birefringence angle reported by the Planck data release β = 0.30° ± 0.11° (68%C.L.), some constraints can be put on δν
. Also, the value of cosmic birefringence due to Majorana CνB medium is estimated at about β|
ν
≃ 0.2 rad. In this respect, since Majorana neutrino and anti-neutrino are exactly the same, both CB contributions will be added together. However, this value is at least two orders larger than the cosmic birefringence angle reported by the Planck data release, β = 0.30° ± 0.11° (68%C.L.). Finally, we shortly discussed this big inconsistency. It is noteworthy that to calculate the contribution of photon-neutrino forward scattering for cosmic birefringence, we just consider the standard model of particles and the standard scenario of cosmology.