bluuebunny/crossref_metadata_2025 huggingface dataset:
Electron Diffraction-Based Techniques for 2D Layered Materials
Authors: Patra Abhinandan , Rout Chandra Sekhar
Published: December 2022

Unravelling of the various crystallographic hitches of variety of nanomaterials and their bulk equivalents were accomplished through vigorous electron diffraction-based characterization techniques since the 19th century. Scanning Electron Microscopy (SEM), Energy dispersive X-Ray analysis (EDAX) and Transmission Electron Microscopy (TEM) are the salient characterization techniques that are being extensively casted-off in solid state physics and nanotechnology for the better insight assessment of the emerging low dimensional materials. Mainly, In SEM, the reflected or knocked-off electrons furnishes the comprehensive view of the surface morphology and its composition, whereas in case of TEM, the transmitted electrons hands over the information regarding the crystal structure, morphology, strain properties, phase distribution of the pigments, and its compositional elements. With all the consistencies and variances, conjointly both these electron diffraction-based techniques are exclusively utilized for a lot of advanced studies on the comprehensive interpretation and analysis which includes in-situ high resolution imaging of the modern two-dimensional materials to find out the crystal defects, bonding and various electronic and optical properties. Therefore, this chapter reviews different types of electron diffraction techniques and its physical significance, basic principle, modus operandi, instrumentation and plentiful applications along with the future outlooks.
SOBA: Development and testing of a soluble oligomer binding assay for detection of amyloidogenic toxic oligomers
Authors: Shea Dylan , Colasurdo Elizabeth , Smith Alec , Paschall Courtnie , Jayadev Suman , Keene C. Dirk , Galasko Douglas , Ko Andrew , Li Ge , Peskind Elaine , Daggett Valerie
Published: December 2022

The formation of toxic Amyloid β-peptide (Aβ) oligomers is one of the earliest events in the molecular pathology of Alzheimer’s Disease (AD). These oligomers lead to a variety of downstream effects, including impaired neuronal signaling, neuroinflammation, tau phosphorylation, and neurodegeneration, and it is estimated that these events begin 10 to 20 y before the presentation of symptoms. Toxic Aβ oligomers contain a nonstandard protein structure, termed α-sheet, and designed α–sheet peptides target this main-chain structure in toxic oligomers independent of sequence. Here we show that a designed α–sheet peptide inhibits the deleterious effects on neuronal signaling and also serves as a capture agent in our soluble oligomer binding assay (SOBA). Pre-incubated synthetic α–sheet-containing Aβ oligomers produce strong SOBA signals, while monomeric and β-sheet protofibrillar Aβ do not. α–sheet containing oligomers were also present in cerebrospinal fluid (CSF) from an AD patient versus a noncognitively impaired control. For the detection of toxic oligomers in plasma, we developed a plate coating to increase the density of the capture peptide. The proof of concept was achieved by testing 379 banked human plasma samples. SOBA detected Aβ oligomers in patients on the AD continuum, including controls who later progressed to mild cognitive impairment. In addition, SOBA discriminated AD from other forms of dementia, yielding sensitivity and specificity of 99% relative to clinical and neuropathological diagnoses. To explore the broader potential of SOBA, we adapted the assay for a-synuclein oligomers and confirmed their presence in CSF from patients with Parkinson’s disease and Lewy body dementia.
Cross-section continuity of definitions of angular momentum
Authors: Chen Po-Ning , Paraizo Daniel E , Wald Robert M , Wang Mu-Tao , Wang Ye-Kai , Yau Shing-Tung
Published: December 2022

We introduce a notion of ‘cross-section continuity’ as a criterion for the viability of definitions of angular momentum, J, at null infinity: If a sequence of cross-sections,

, of null infinity converges uniformly to a cross-section

, then the angular momentum, J

n
, on

should converge to the angular momentum, J, on

. The Dray–Streubel (DS) definition of angular momentum automatically satisfies this criterion by virtue of the existence of a well defined flux associated with this definition. However, we show that the one-parameter modification of the DS definition proposed by Compere and Nichols—which encompasses numerous other alternative definitions—does not satisfy cross-section continuity. On the other hand, we prove that the Chen–Wang–Yau definition does satisfy the cross-section continuity criterion.
XUV ionization of the H2 molecule studied with attosecond angular streaking
Authors: Serov Vladislav V , Kheifets Anatoli S
Published: December 2022

We study orientation and two-center interference effects in attosecond time-resolved photoionization of the H2 molecule. Time resolution of extreme-ultraviolet ionization of H2 is gained through the phase retrieval capability of attosecond angular streaking demonstrated earlier by Kheifets et al (2022 Phys. Rev. A 106 033106). Once applied to H2, this technique delivers an anisotropic phase and time delay which both depend sensitively on the molecular axis orientation. In addition, the photoelectron momentum distribution displays a very clear two-center interference pattern. When the interference formula of Walter and Briggs (1999 J. Phys. B 32 2487) is applied, an effective photoelectron momentum appears to be greater than the asymptotic momentum at the detector. This effect is explained by a molecular potential well surrounding the photoemission center.
Increase output of vibration energy harvester by a different piezoelectric mode and branch structure design
Authors: Qin Weiyang , Liu Qi , Wang Yuansheng , Xie Zhongliang , Zhou Zhiyong
Published: December 2022

In this study, we improve the performance of vibration energy harvesting by adopting a different working mode of piezoelectric material. We propose a harvester that is composed of an inverted beam and a branch structure. The branch can produce an amplified inertial force under vibration and passes it to a lead zirconate titanate (PZT) sheet. The resultant force acts on the PZT sheet as a dynamic normal force, not as a dynamic flexural one in the classical harvester. This change can increase the output significantly. First, the theoretical model is established and solved. The results show that the design can induce a super-harmonic vibration and produce a large output. Then, the validation experiments are carried out. The experimental results prove the occurrence of super-harmonic vibration and show that under weak stochastic excitation the branch structure can promote the electric output significantly. For a stochastic excitation of PSD = 0.06 g2 Hz−1, the average power of the novel harvester can reach 0.344 mW by a small PZT sheet with the dimensions of

24
×
6
×
0.2

 m

m

3

. This study may provide a novel scheme in improving the vibration energy harvesting efficiency.
Mean model of the dielectric barrier discharge plasma actuator including photoionization
Authors: Shaygani Afshin , Adamiak Kazimierz
Published: December 2022

A numerical algorithm is proposed for simulation of the dielectric barrier discharge plasma actuators including photo-ionization. The computational bottleneck related to a very long computing time has been circumvented by suppressing the discharge pulses and proposing a mean discharge model. It incorporates an artificial damping term into the electron transport equation to suppress the formation of pulses, which significantly accelerates the simulation. Based on the fluid description of three generic species: electrons, positive and negative ions, the model accounts for the drift, diffusion, and reaction terms. The reaction coefficients are extracted from the Boltzmann equation considering the local field approximation. A self-sustained discharge is achieved by including photo-ionization during the positive voltage phase, and the secondary electron emission from the metal surface, during the negative voltage phase. The proposed methodology compromises the computational burdens of the first-principle approaches and inadequacy of the simplistic models in incorporating the problem physics. The accuracy of the proposed methodology has been validated by comparing the computational and experimental data for the electrical and flow characteristics of a laboratory actuator.
Multifunctional acoustic metamaterial for air ventilation, broadband sound insulation and switchable transmission
Authors: Xiao Zhenqian , Gao Penglin , He Xiao , Qu Yegao , Wu Linzhi
Published: December 2022

Noise reduction and other manipulation of sound waves has been a major concern in science and engineering. Here, we propose a ventilated soundproof acoustic metamaterial consisting of resonant cavities arranged around a central air passage. This metamaterial can accomplish strong sound insulation performance. The transmission loss is larger than 30 dB within a wide frequency range (625–1695 Hz) due to the prohibited band. More intriguingly, we discover that rotating the opening, somewhat like an acoustic switch, can directly control the sound transmission of the deaf band. This is particularly useful for opening a narrow but high transmission window at the frequency of interest, which provides a new degree of freedom for sound control. Through band structure analysis and effective parameter calculation, we discover the sound insulation mechanism of the ventilated metamaterial and reveal the underlying mechanism of the switchable narrow-band sound transmission. Beyond the 1D study, the proposed acoustic metamaterial is expanded to a 3D soundproof metacage. We find that the sound insulation performance and switchable sound transmission phenomena are still retained for the metacage. The results reported here may inspire more exploration of sound barriers and multifunctional applications, such as innovative building facades for noise reduction and logic components for acoustic circuits.
Two-dimensional chalcogenide-based ferromagnetic semiconductors
Authors: Wu Yanling , Li Jun , Liu Yong
Published: December 2022

Two-dimensional (2D) magnetic materials draw an enormous amount of attention due to their novel physical properties and potential spintronics device applications. Room-temperature ferromagnetic (FM) semiconductors have long been pursued in 2D magnetic materials, which show a long range magnetic order down to atomic-layer thickness. The intrinsic ferromagnetism has been predicted in a series of 2D materials and verified in experiments and the magnetism can be modulated by multiple physical fields, exhibiting promising application prospects. In this review, we overview several types of 2D chalcogenide-based FM semiconductors discovered in recent years. We summary and compare their basic physical properties, including the crystal structures, electronic structures, and mechanical stability. The 2D magnetism can be described by several physical models. We also focus on the recent progresses about theoretical prediction of FM semiconductors and experimental observation of external-field regulation. Most of investigations have shown that 2D chalcogenide-based FM semiconductors have relatively high Curie temperature (T

c

) and structural stability. These materials are promising to realize the room-temperature ferromagnetism in atomic-layer thickness, which is significant to design spintronics devices.
Terahertz magnetic excitation in antiferromagnets: atomistic spin simulations versus a coupled pendulum model
Authors: Zheng Cuixiu , Chen Xing , Zhou Sai , Liu Yaowen
Published: December 2022

Understanding and manipulating of the antiferromagnetic (AF) ultrafast spin dynamics in antiferromagnets (AFMs) is a crucial importance issue because of the promising applications in terahertz spintronic devices. In this study, an analytical theory extended from the classic coupled pendulum model has been developed to describe the intrinsic magnetic excitation of AFMs. The derived frequency dispersion of the AF resonances has been further checked by using the atomistic-level Landau–Lifshitz–Gilbert simulations. We show that the rutile crystalline AFM MnF2 possess two separate resonance modes at low magnetic fields: high frequency mode with right-handed polarization and low frequency mode with left-handed polarization. In the absence of magnetic field, these two resonance modes could degenerate into a single resonance state. When the applied magnetic field is higher than the spin-flip field, the system behaves a quasi-ferromagnetic mode. Both quantitative and qualitative agreement with atomistic simulation results confirm the theoretical picture of the AF resonance dynamics. This study provides a simple but physical understanding of the ultrafast dynamics of AF excitations.
On a fluid–structure interaction problem for plaque growth
Authors: Abels Helmut , Liu Yadong
Published: December 2022

We study a free-boundary fluid–structure interaction problem with growth, which arises from the plaque formation in blood vessels. The fluid is described by the incompressible Navier–Stokes equations, while the structure is considered as a viscoelastic incompressible neo-Hookean material. Moreover, the growth due to the biochemical process is taken into account. Applying the maximal regularity theory to a linearization of the equations, along with a deformation mapping, we prove the well-posedness of the full nonlinear problem via the contraction mapping principle.
Active vector models generalising 3D Euler and electron–MHD equations
Authors: Chae Dongho , Jeong In-Jee
Published: December 2022

We introduce an active vector system, which generalises both the 3D Euler equations and the electron–magnetohydrodynamic equations (E–MHD). We may as well view the system as singularised systems for the 3D Euler equations, in which case the equations of (E–MHD) correspond to the order two more singular one than the 3D Euler equations. The generalised surface quasi-geostrophic equation (gSQG) can be also embedded into a special case of our system when the unknown functions are constant in one coordinate direction. We investigate some basic properties of this system as well as the conservation laws. In the case when the system corresponds up to order one more singular than the 3D Euler equations, we prove local well-posedness in the standard Sobolev spaces. The proof crucially depends on a sharp commutator estimate similar to the one used for (gSQG) in Chae et al (2012 Commun. Pure Appl. Math.
65 1037–66). Since the system covers many areas of both physically and mathematically interesting cases, one can expect that there are various related problems to be investigated, parts of which are discussed here.
Exploring students’ perceptions of learning equilibrium concepts through making Bulan kites
Authors: Anantanukulwong Roseleena , Pongsophon Pongprapan , Chiangga Surasak , Tan Aik-Ling
Published: December 2022

This study reports students’ perceptions of learning the physics concepts of equilibrium through making Bulan kites. The Bulan kite encompasses indigenous knowledge related to the teachings and ideas found in Islam. After a workshop where students (n = 109) made the Bulan kite under the tutelage of a local expert, students (n = 12) were interviewed to distil their thoughts of the learning experience and their understanding of the concepts. The interviews were transcribed and content analysis was carried out. The findings indicate that students were able to make connections between the ideas of equilibrium and the art of kite construction which is based on indigenous knowledge. The kite making process also presented students with opportunities to be more aware of the value of local indigenous knowledge and motivated them in physics learning. We also discussed how indigenous knowledge can be incorporated meaningfully into physics learning.
A climbers pendulum fall
Authors: O’Shea Michael J
Published: December 2022

We analyse a lead climber pendulum fall, a fall that can occur after the climber traverses horizontally away from their highest anchor. The model is based on a spring pendulum with a nonlinear component and incorporates air resistance. The resulting set of equations can be solved numerically using an Excel spreadsheet that is easily implemented by a student. The maximum tension and speed during the fall were calculated for a real dynamic climbing rope. The inclusion of rope elasticity can, under the right conditions, lead to a speed at the bottom of the swing that is less than that found for a stiff rope. The path of the climber is not closed as they swing back and forth, and we analyse radial oscillations to gain further insight. For multiple swings, the air resistance is important for removing energy from the system.
Wireless at its origin
Authors: Riccardi P , Prete G , Chiappetta F , Meringolo C
Published: December 2022

This work discusses a didactic path aimed at revisiting the first experiments on the transmission and detection of electromagnetic waves, performed by Guglielmo Marconi at the end of the 19th century. With very simple materials it is possible to set-up apparatus that allow to illustrate practically the simple physical picture of wireless telegraphy, and in particular the role of monopole antennas and ground connections, first introduced by Guglielmo Marconi to increase the distance between the transmitter and the receiver. Retracing in the classroom the first steps of the beginning and the advent of radio communications is important for both science education and the students’ understanding of the connected world we live in.
Fast 3D kernel computation method for positron range correction in PET
Authors: Li Chong , Scheins Jürgen , Tellmann Lutz , Issa Ahlam , Wei Long , Shah N Jon , Lerche Christoph
Published: December 2022

Objective. The positron range is a fundamental, detector-independent physical limitation to spatial resolution in positron emission tomography (PET) as it causes a significant blurring of underlying activity distribution in the reconstructed images. A major challenge for positron range correction methods is to provide accurate range kernels that inherently incorporate the generally inhomogeneous stopping power, especially at tissue boundaries. In this work, we propose a novel approach to generate accurate three-dimensional (3D) blurring kernels both in homogenous and heterogeneous media to improve PET spatial resolution. Approach. In the proposed approach, positron energy deposition was approximately tracked along straight paths, depending on the positron stopping power of the underlying material. The positron stopping power was derived from the attenuation coefficient of 511 keV gamma photons according to the available PET attenuation maps. Thus, the history of energy deposition is taken into account within the range of kernels. Special emphasis was placed on facilitating the very fast computation of the positron annihilation probability in each voxel. Results. Positron path distributions of 18F in low-density polyurethane were in high agreement with Geant4 simulation at an annihilation probability larger than 10−2 ∼ 10−3 of the maximum annihilation probability. The Geant4 simulation was further validated with measured 18F depth profiles in these polyurethane phantoms. The tissue boundary of water with cortical bone and lung was correctly modeled. Residual artifacts from the numerical computations were in the range of 1%. The calculated annihilation probability in voxels shows an overall difference of less than 20% compared to the Geant4 simulation. Significance. The proposed method is expected to significantly improve spatial resolution for non-standard isotopes by providing sufficiently accurate range kernels, even in the case of significant tissue inhomogeneities.
Evaluation of raw segmental bioelectrical impedance variables throughout anterior cruciate ligament reconstruction rehabilitation
Authors: Cleary Christopher J , Weir Joseph P , Vopat Bryan G , Herda Ashley A
Published: December 2022

Background. Raw bioelectrical impedance analysis (BIA) variables are related to physical function in healthy and diseased populations. Therefore, BIA may be an insightful, noninvasive method of assessment to track following anterior cruciate ligament reconstruction (ACLR). Objectives. Evaluate phase angle, reactance and impedance at 50 kHz (PhA50, Xc50, and Z
50, respectively) in the operative (OP) and non-operative (NOP) limbs during ACLR rehabilitation. Approach. Seventeen patient (12 M, 5 F; 18.8 ± 4.8 years) clinic reports were evaluated prior to ACLR (PRE), two- (2 W), six- (6 W), and twelve-weeks (12 W) post-ACLR and at return to sport testing (RTS). Setting. All observations occurred during the participant’s physical therapy visits. Measurements. A multi-frequency BIA device measured segmental PhA, Xc, and Z. Linear mixed effects models were used to assess any leg and time interaction and changes over leg and time, independently. Any interactions or main effects were considered significant at p < 0.05. Main results. Significant leg x time interactions were observed for each variable. PhA50 and Xc50 of NOP were higher (p < 0.001) than OP at each time point by an average of by 0.9° and 4.9 Ω, respectively. In OP, PhA50 and Xc50 decreased from PRE to 2 W and increased from 6 to 12 W and 12 W to RTS (p < 0.01, for all). At RTS, PhA50 and Xc50 were similar to PRE in OP (p > 0.05). For Z
50, the OP leg did not change over time (p > 0.05). Z
50 was greater in NOP at 2 and 6 W (p < 0.01, for both). There were differences in PhA50 in NOP between PRE and 6 W and from 6 W to RTS (p < 0.05 for both). Xc50 did not change (p > 0.05), and Z
50 PRE was lower than at 2 W (p < 0.05). Significance. A multi-frequency BIA device can detect changes in segmental BIA variables following ACLR.
Investigation of the synergistic effects of ICRF + NBI heating in EAST plasma discharges
Authors: Song Chengyi , Wu Bin , Gong Xueyu , Wang Ji , Chen Yuqing , Hao Baolong , Ti Ang , Wang Shouxin , He Liang , Zhong Guoqiang , Yin Lan , Li Jun , Cui Zhiwei , Huang Qianhong , Zhong Yijun , Xie Yahong , Xie Yuanlai
Published: December 2022

Following an upgrade of the neutral beam injection (NBI) system, obvious synergy between combined NBI and ion cyclotron resonance frequency (ICRF) heating was observed in recent experiments conducted at EAST. To investigate the effects of beam-ions accelerated by radiofrequency (RF) wave, analyses are performed by using TRANSP code based on the experimental results. The calculated results argue that only a small fraction of the ICRF power is absorbed by the beam ions in the ICRF + NBI synergistic heating of the (H)D plasma. To enhance the beam–RF interactions in synergistic heating and achieve high plasma performance of EAST, different experimental conditions, including multiple injection powers and diverse beam injection options, were explored. Beam injected fast ions are passing particles, trapped particles observed when synergy heating between ICRF and NBI. In particular, by varying the injection direction of the beam ions it was observed that more tangential beam yields better synergy in comparison with more perpendicular beam. The neutron emission rate of D–D fusion in tokamaks is improved and less fast ion loss is produced with tangential NBI + ICRF heating. Also, the effect of the ratio P
ICRF/P
NBI on ICRF + NBI combined heating is demonstrated, the higher power boosts the fusion enhancement. The study of the performed synergistic heating provides an important reference for the subsequent combined NBI + ICRF heating experiments on EAST.
2D-imaging of absolute OH and H2O2 profiles in a He–H2O nanosecond pulsed dielectric barrier discharge by photo-fragmentation laser-induced fluorescence
Authors: van den Bekerom Dirk , Tahiyat Malik M , Huang Erxiong , Frank Jonathan H , Farouk Tanvir I
Published: December 2022

Pulsed dielectric barrier discharges (DBD) in He–H2O and He–H2O–O2 mixtures are studied in near atmospheric conditions using temporally and spatially resolved quantitative 2D imaging of the hydroxyl radical (OH) and hydrogen peroxide (H2O2). The primary goal was to detect and quantify the production of these strongly oxidative species in water-laden helium discharges in a DBD jet configuration, which is of interest for biomedical applications such as disinfection of surfaces and treatment of biological samples. Hydroxyl profiles are obtained by laser-induced fluorescence (LIF) measurements using 282 nm laser excitation. Hydrogen peroxide profiles are measured by photo-fragmentation LIF (PF-LIF), which involves photo-dissociating H2O2 into OH with a 212.8 nm laser sheet and detecting the OH fragments by LIF. The H2O2 profiles are calibrated by measuring PF-LIF profiles in a reference mixture of He seeded with a known amount of H2O2. OH profiles are calibrated by measuring OH-radical decay times and comparing these with predictions from a chemical kinetics model. Two different burst discharge modes with five and ten pulses per burst are studied, both with a burst repetition rate of 50 Hz. In both cases, dynamics of OH and H2O2 distributions in the afterglow of the discharge are investigated. Gas temperatures determined from the OH-LIF spectra indicate that gas heating due to the plasma is insignificant. The addition of 5% O2 in the He admixture decreases the OH densities and increases the H2O2 densities. The increased coupled energy in the ten-pulse discharge increases OH and H2O2 mole fractions, except for the H2O2 in the He–H2O–O2 mixture which is relatively insensitive to the additional pulses.
Sterilization of Salmonella typhimurium and Staphylococcus aureus in different cold-chain environments by combining NO
x
mode and O3 mode air discharges
Authors: Chen Min , Yan Jinwei , Feng Yue , Liu Dingxin , Wang Zifeng , Liu Linbo , Huang Lingling , Guo Li , Zhang Jingyao , Liu Chang , Rong Mingzhe
Published: December 2022

Cold-chain transport has been suggested to be an important means for the cross-regional transmission of pathogenic microorganisms. In this study, NO
x
mode and O3 mode air discharges were combined by mixing effluent gases for sterilization in several cold-chain environments. It was found that the mixed gas effectively inactivated Salmonella typhimurium and Staphylococcus aureus in 1–4 mm thick ice layers at different temperatures (−20/−40/−80 °C) within 10 min, which is a significantly stronger effect than that of the effluent gas of either the NO
x
mode or the O3 mode discharge alone. This can be attributed to the high-valence reactive nitrogen species such as N2O5. Our findings provide a promising sterilization strategy to curb the spread of infectious diseases in cold-chain environments.
Simultaneous determination of source term and the initial value in the space-fractional diffusion problem by a novel modified quasi-reversibility regularization method
Authors: Wen Jin , Ren Xue-Juan , Wang Shi-Juan
Published: December 2022

This paper deals with an inverse problem of determining source term and initial data simultaneously for a space-fractional diffusion equation in a strip domain, with the aid of extra measurement data at a fixed time. The uniqueness results are obtained by a simple trick based on the linear property of the proposed equation. Since this problem is ill-posed, a modified quasi-reversibility method is obtained by employing the Fourier transform. Error estimates for source term and initial value are obtained from a suitable parameter choice rule. Finally, several numerical examples show that the proposed regularization method is effective and stable.
Experimental investigation on the impacting and freezing characteristics of water droplets on a PDMS-decorated superhydrophobic aluminum alloy surface
Authors: Peng Huaqiao , Shi Tao , Yang Hanming , Liu Yourui , Wang Qiang , Su Zhengliang , Xia Zuxi
Published: December 2022

Due to the potential applications of superhydrophobic surfaces in water-repelling and anti-icing, it is of great interest to study the impacting and freezing processes of water droplets on superhydrophobic surfaces. In this study, the process of a water droplet impacting the PDMS-decorated superhydrophobic aluminum alloy (denoted as Al-PDMS) surface was studied, and the influences of a water droplet falling height and volume were systemically investigated with a high-speed camera. The results indicate that the impacting process can be categorized into four states, which are mainly affected by the dropping height. The bouncing processes of water droplets on horizontal superhydrophobic surfaces are studied by defining spreading factor α and rebounding factor β. Furthermore, the effect of the inclination angle φ of the superhydrophobic plate on the impacting behavior was investigated. The freezing processes of water droplets on superhydrophobic surfaces were also studied. The results showed that the delayed-icing time decreases with decreasing test plate temperature. Additionally, the volume and height of the frozen portion of the water droplets during freezing were investigated, and the movement characteristic of the freezing front was analyzed.
Giant and strain-tunable interfacial magnetic anisotropy in MgO-based magnetic heterostructures with heavy atoms insertion
Authors: Hu Yue , Yan Shiming , Jin Deyou , Qiao Wen , Bai Ru , Zhou Tiejun
Published: December 2022

MgO-based magnetic heterostructures with interfacial magnetic anisotropy has attracted increasing attention due to its application in building high-density magnetic random access memories. A large and tunable interfacial magnetic anisotropy constant (Ki) is required for high thermal stability and flexible data writability. In this study, the Ki of Fe/MgO, Fe/Pt/MgO, and Fe/Ir/MgO heterostructures with strains from −4.5% to 4.5% were calculated by ab initio electronic structure calculations. It has been found that the Fe/Pt/MgO and Fe/Ir/MgO where the Pt and Ir monolayers are inserted in the interface possess Ki of 2.415 mJ m−2 and −4.468 mJ m−2, which are much larger by several times than that (0.840 mJ m−2) of the Fe/MgO. In particular, the out-of-plane Ki from the interfacial Pt atoms in Fe/Pt/MgO is as high as 5.978 mJ m−2. The magnetic anisotropy of these structures can be significantly manipulated by strain. Combining second-order perturbation theory, the origin of these behaviors has been analyzed by layer-resolved, orbital-resolved, and k-resolved Ki. The spin-flip terms of d

z
2/d

yz
orbitals in the interfacial layer are mainly responsible for the out-of-plane Ki and its variation with strain. This work provides a useful guide for the design of high and tunable magnetic anisotropy in the MgO-based magnetic heterostructures.
Testing Lorentz invariance of gravity in the Standard-Model Extension with GWTC-3
Authors: Niu Rui , Zhu Tao , Zhao Wen
Published: December 2022

Successful detection of gravitational waves has presented a new avenue to explore the nature of gravity. With the cumulative catalog of detected events, we can perform tests on General Relativity from various aspects with increasing precision.
In this work, we focus on Lorentz symmetry during propagation of gravitational waves.
Considering the dispersion relation in the gauge-invariant linearized gravity sector of the Standard-Model Extension, the anisotropy, birefringence, and dispersion effects will be induced during propagation of gravitational waves because of the Lorentz violating modification, and cause dephasings in waveform received by detectors.
With the distorted waveform, we perform full Bayesian inference with confident events in the last gravitational wave catalog. We consider two cases associated with the lowest mass dimension d = 5,6 which are supposed to have the most significant effects, and place the constraints on the expansion coefficients characterizing the Lorentz violating behavior which have 16 independent components for d = 5 and 18 components for d = 6.
We do not find any evidence for Lorentz violation in the gravitational wave data, the constraints on the coefficients are on the order of 10-15 m for d = 5 and 10-10 m2 for d = 6 respectively.
A novel power-combination method using a time-reversal pulse-compression technique
Authors: Lu Xi-Cheng , Tian Jin , Zhang Rong-Wei , Wang Hai-Bo , Qiu Yang
Published: December 2022

The electromagnetic time-reversal (TR) technique has the characteristics of spatiotemporal focusing in a time-reversal cavity (TRC), which can be used for pulse compression, thus forming an electromagnetic pulse with high peak power. A time-reversed pulse-compression method in a single channel has high pulse compression gain. However, single channel pulse compression can only generate limited gain. This paper proposes a novel TR power-combination method in a multichannel TRC to obtain higher peak power based on TR pulse-compression theory. First, the TR power-combination model is given, and the crosstalk properties of the associated channel and the influence of the reversal performance are studied. Then, the power-combination performances for the TR pulse compression, such as combined signal to noise ratio (SNR) and combined compression gain, are analyzed by numerical simulation and experimental methods. The results show that the proposed method has obvious advantages over pulse-compression methods using a single channel cavity, and is more convenient for power combination.
Multiferroic monolayers VOX (X = Cl, Br, I): Tunable ferromagnetism via charge doping and ferroelastic switching
Authors: Yang Hong-Chao , Liu Peng-Cheng , Mu Liu-Yu , Li Ying-De , Han Kai , Qiu Xiao-Le
Published: December 2022

The fascinating properties arising from the interaction between different ferroic states of two-dimensional (2D) materials have inspired tremendous research interest in the past few years. Under the first-principles calculations, we predict the coexistence of antiferromagnetic and ferroelastic states in VOX (X = Cl, Br, I) monolayers. The results illustrate that the VOX monolayers exhibit indirect bandgap characteristics, i.e., their gaps decrease with the halide elements changing from Cl to I. The ground states of all these VOX monolayers are antiferromagnetic (AFM) with the magnetic moments contributed by the V 3d electrons. Furthermore, the magnetic ground state changing from AFM to ferromagnetism (FM) can be realized by doping carriers. In addition, the moderate ferroelastic transition barrier and reversible switching signal ensure their high performances of nonvolatile memory devices. Our findings not only offer an ideal platform for investigating the multiferroic properties, but also provide candidate materials for potential applications in spintronics.
Expected measurement precision of the branching ratio of the Higgs boson decaying to the di-photon at the CEPC*
Authors: Guo Fangyi , Fang Yaquan , Li Gang , Lou Xinchou
Published: December 2022

This paper presents the prospects of measuring

in three Z decay channels

using the baseline detector with

GeV at the Circular Electron Positron Collider (CEPC). Simulated Monte Carlo events were generated and scaled to an integrated luminosity of 5.6 ab–1 to mimic the data. Extrapolated results to 20 ab–1 are also reported. The expected statistical precision of these measurements after combining three channels of Z boson decay was 7.7%. With some preliminary estimation on the systematical uncertainties, the total precision is 7.9%. The performance of the CEPC electro-magnetic calorimeter (ECAL) was studied by smearing the photon energy resolution in simulated events in the

channel. In the present ECAL design, the stochastic term in resolution plays the dominant role in the precision of Higgs measurements in the

channel. The impact of the resolution on the measured precision of

as well as the optimization of the ECAL constant and stochastic terms were studied for further detector design.
Gravitational Wave Radiation from Newborn Accreting Magnetars
Authors: Cheng Quan , Zheng Xiao-Ping , Fan Xi-Long , Huang Xi
Published: December 2022

The observed electromagnetic radiation from some long and short gamma-ray bursts, and neutron stars (NSs), and the theoretical models proposed to interpret these observations together point to a very interesting but confusing problem, namely, whether fall-back accretion could lead to dipole field decay of newborn NSs. In this paper, we investigate the gravitational wave (GW) radiation of newborn magnetars with a fall-back disk formed in both the core-collapse of massive stars and the merger of binary NSs. We make a comparison of the results obtained with and without fall-back accretion-induced dipole-field decay (FADD) involved. Depending on the fall-back parameters, initial parameters of newborn magnetars, and models used to describe FADD, FADD may indeed occur in newborn magnetars. Because of the low dipole fields caused by FADD, the newborn magnetars will be spun up to higher frequencies and have larger masses in comparison with the non-decay cases. Thus the GW radiation of newborn accreting magnetars would be remarkably enhanced. We propose that observation of GW signals from newborn magnetars using future GW detectors may help to reveal whether FADD could occur in newborn accreting magnetars. Our model is also applied to the discussion of the remnant of GW170817. From the post-merger GW searching results of Advanced LIGO and Advanced Virgo we cannot confirm the remnant is a low-dipole-field long-lived NS. Future detection of GWs from GW170817-like events using more sensitive detectors may help to clarify the FADD puzzle.
Mechanically controlled robotic gripper with bistability for fast and adaptive grasping
Authors: Cai Xianyang , Tang Bin
Published: December 2022

This paper presents a novel bistable gripper inspired by the closure motion found in the jaw of a hummingbird. With a bistable characteristic, the robotic gripper can grasp objects rapidly without applying continuous external force. The bistable gripper comprises a linkage-driven mechanism and two bionic jaws consisting of thin elastic polyvinyl chloride sheets with two clamped ends connected by a hinge. The shape of the thin sheets was modeled and optimized using geometric analysis, and the morphing processes of the bionic jaw were analyzed using finite element simulations and experiments. Furthermore, we explored the motion characteristics of the clamps during the snap-through and snap-back processes and divided the motion into two phases: delay and snap. Force and response time tests show that the proposed bistable gripper can achieve fast bending within milliseconds under a low pull force during the snap phase. Grasping experiments demonstrated that the proposed robotic gripper is adaptable for grasping objects of various shapes and weights. After grasping, the bistable gripper can release the target by pulling the actuating rod and automatically return to the open state. This study reveals the unique bending mechanism of thin sheets that can be exploited for fast, versatile, and adaptive grasping. The bistable gripper exhibits the potential to reduce energy consumption and simplify control when performing tasks in unstructured environments such as space and underwater.
Effect of moisture content on the microscopic properties of amorphous cellulose: a molecular dynamics simulations
Authors: Jiang Kaixiang , Yan Zhe , Fang Wenjuan , Zhang Youqiang
Published: December 2022

Performance degradation of cellulose and cellulose-based materials caused by water is an inevitable problem in application processes. In most studies, this was attributed to the fracture and rebuilding of the hydrogen bond network in the system; however, limited attention was paid to the movement, aggregation state, and specific property evolution of cellulose and water during this process. In this study, based on molecular dynamics simulations, the effects of moisture content on the microscopic properties of cellulose are investigated, including the mechanical properties, diffusion coefficient, glass transition temperature, microscopic motion of water molecules, and preferred hydration sites on cellulose. The results show that the mechanical properties of the system increase and then decrease as the water content in the system increases. When the moisture content is 4%, the mechanical properties of cellulose are the best, and the elastic modulus and shear modulus increase by 7.6% and 9.4%, respectively, compared with those of dry cellulose. The glass transition temperature of the system with 4% moisture content increases by 72 K compared with that of dry cellulose. The mean square displacement and diffusion coefficient of water in the system is affected by the water molecules’ polymerisation state and the free water content. In the entire range of water contents studied, hydroxyl groups O2, O3, and O6 of cellulose dominate the reaction with water compared with acetal oxygens O4 and O5. In the system with 4% moisture content, the number of water molecules around the glycosidic bonds O4 are the most minor and cause the least damage to the cellulose structure. A critical water content point of 4% is recommended, and this result is expected to provide a reference for maintaining the excellent and stable properties of cellulose and cellulose-based materials.
Towards advanced divertor configurations on the J-TEXT tokamak
Authors: LIANG Yunfeng , CHEN Zhipeng , WANG Nengchao , CHENG Zhifeng , KNIEPS Alexander , ZHOU Song , RAO Bo , XU Shuai , DREWS Philipp , ZHANG Xiaolong , WANG Hao , WANG Zhaosu , YANG Jie , XU Xin , HUA Jiankun , YANG Qinghu , YAN Wei , LI Cunkai , YANG Yutong , LI Shuhao , LIU Shaocheng , NIE Lin , LONG Ting , LIAO Liang , WANG Fuqiong , SUZUKI Yasuhiro
Published: December 2022

Developing advanced magnetic divertor configurations to address the coupling of heat and particle exhaust with impurity control is one of the major challenges currently constraining the further development of fusion research. It has therefore become the focus of extensive attention in recent years. In J-TEXT, several new divertor configurations, including the high-field-side single-null poloidal divertor and the island divertor, as well as their associated fundamental edge divertor plasma physics, have recently been investigated. The purpose of this paper is to briefly summarize the latest progress and achievements in this relevant research field on J-TEXT from the past few years.
Qade: solving differential equations on quantum annealers
Authors: Criado Juan Carlos , Spannowsky Michael
Published: December 2022

We present a general method, called Qade, for solving differential equations using a quantum annealer. One of the main advantages of this method is its flexibility and reliability. On current devices, Qade can solve systems of coupled partial differential equations that depend linearly on the solution and its derivatives, with non-linear variable coefficients and arbitrary inhomogeneous terms. We test this through several examples that we implement in state-of-the-art quantum annealers. The examples include a partial differential equation and a system of coupled equations. This is the first time that equations of these types have been solved in such devices. We find that the solution can be obtained accurately for problems requiring a small enough function basis. We provide a Python package implementing the method at gitlab.com/jccriado/qade.
Multi-response optimization of process and reinforcement parameters of hybrid reinforced Al matrix composites using Taguchi- Grey relational analysis
Authors: Ashebir Demeke Abay , Mengesha Getinet Asrat , Sinha Devendra Kumar , Bereda Yodit Birhanu
Published: December 2022

Hybrid aluminum matrix composites (HAMCs) are a new class of advanced composite and hybrid materials that can be customized and engineered to achieve specific properties for specific applications in specific environments. HAMCs are popular in the transportation industry due to their reduced cost and fuel consumption as compared to conventional materials. This research article has mainly focused on multi-response optimization through an L16 orthogonal array experimental design employing Taguchi-based Grey Relational Analysis. It was intended to explore the influence of tetra hybrid reinforced HAMCs synthesized using pure Al matrix with fixed wt% of primary reinforcements (5 wt% SiC and 5 wt% Al2O3) and varying wt% of secondary reinforcements such as (0.5, 2.5, 4.5, and 6.5) wt% of Gr and (0.5, 2.5, 4.5, and 6.5) wt% of SCBA on physicomechanical properties of HAMCs when milling time, compaction pressure, and sintering temperature were varied. The Taguchi-Grey’s relational analysis gave the optimal combination of the process and reinforcement parameters for both the physical and the mechanical properties such as milling time (5 h.), compaction pressure (55 MPa), sintering temperature (450 °C), Gr content (0.5 wt%), and SCBA content (4.5 wt%). At the optimum parameter settings, the average density, porosity, hardness, compressive strength, and ultimate tensile strength were 2.5118 gm cm−3, 0.8653%, 4228.45 MPa, 343.33 MPa, and 1516.41 MPa, respectively. The utilization of Taguchi and GRA methods have significantly confirmed that the influence of compaction pressure was highest among the all the other four parameters. The newly synthesized tetra hybrid reinforced HAMCs have shown superior physicomechanical properties compared to pure Al, and single as well as double reinforced HAMCs. Therefore, it is anticipated that the newly developed tetra hybrid reinforced AMC material will be utilized in heavy-duty, aerospace, medical, automotive, marine, and other applications.
Impact of the COVID-19 pandemic on the carbon footprint of a Philippine university
Authors: Cortes Aiza , dos Muchangos Letícia , Tabornal Krissa Joy , Tolabing Hans Diether
Published: December 2022

The Philippines entered its most prolonged lockdown in 2020 when the coronavirus disease (COVID-19) became a pandemic. Additionally, there has been a shift from physical to online classes at all education levels. Against this backdrop, the restrictions imposed on the education sector could have environmental impacts, including on the carbon emission structure. Here, we compare the carbon footprint before and during the pandemic, determine how the pandemic changed the activities that directly affected carbon emissions, and present reduction methods to minimise emissions in the new normal. We calculated emissions before and during the pandemic to achieve these goals, using the data obtained from University of the Philippines (UP) Cebu. The total CO2 emissions of UP Cebu in 2019 were estimated to be 1420.7 tCO2e, which did not significantly differ from the 2018 emissions. In 2020, the total CO2 emissions were estimated to be 555.8 tCO2e, equivalent to a 60.9% decrease from the 2019 emissions. The per capita emissions in UP Cebu for 2019 and 2020 were estimated to be 0.9 tCO2e and 0.3 tCO2e, respectively—both below the national average. The pandemic caused a significant decrease in emissions per activity, except for fuel-related emissions which increased by 305.8%. In the post-COVID-19 world, especially when in-person classes return, UP Cebu must consider concrete strategies to curb its emissions. Specific decarbonisation methods for each activity were simulated and discussed. The results and reduction strategies presented are relevant to UP Cebu and other higher education institutions in the Philippines and Asia with the same characteristics.