bluuebunny/crossref_metadata_2025 huggingface dataset:
Low-frequency sound-absorbing metasurface constructed by a membrane-covered and coiled Helmholtz resonator
Authors: Xu Qishan , Qiao Jing , Zhang Guangyu , Li Longqiu
Published: February 2023

Achieving broadband absorption of sound waves below 500 Hz with materials of sub-wavelength thickness is significant but still a great challenge in academia and industries. Here, we present and theoretically analyze an airtight sound-absorbing metasurface constructed by a membrane-covered and coiled Helmholtz resonator. It is discovered that the metasurface possesses a near-perfect absorption with a working wavelength approximately 33.6 times greater than the total thickness, which stems from synthetic modulation on acoustic reactance brought by the membrane, air gap formed behind the membrane, and a coiled channel. Furthermore, on-demand broadband absorption below 500 Hz is achieved by parallel assemblies consisting of four subunits. An excellent agreement between measurements and predictions confirms the validity of the proposed structures. The airtight construction also broadens its application scenarios compared to the common perforated absorbers with open pores directly exposed to external environments. Our design provides a new structure paradigm for low-frequency sound absorption.
Interband transition probing of coherent acoustic phonons of gold/metal oxide core–shell nanoparticles
Authors: Wang Lijie , Oppermann Malte , Puppin Michele , Bauer Benjamin , Chow Tsz Him , Wang Jianfang , Chergui Majed
Published: February 2023

We present ultrafast spectroscopic investigations of the coherent acoustic vibrations of Au/SiO2 and Au/TiO2 core–shell nanoparticles (NPs) upon excitation of the Au surface plasmon resonance. The oscillations are detected in the region of the interband transitions of Au in the deep-ultraviolet, where they appear in the form of intensity modulations with no changes in the spectra. For the Au/SiO2 NPs, the oscillation period (typically ∼10 ps) is similar to that of bare Au NPs having a size identical to that of the core, implying a negligible coupling of the core with the shell. For Au/TiO2 NPs, significantly slower (∼20 ps) oscillations appear, whose period is identical to that of a bare gold NP having the same total diameter, implying that the Au/TiO2 NPs can be treated as a single object. This may due to the strong chemical interaction at the gold/TiO2 interface. Finally, the amplitude modulations are a consequence of the modifications of the band structure of the Au NP, resulting from the strain due to the phonons, which may affect the joint density of states.
Initial decomposition mechanisms of 2,4,6-triamino-1,3,5-trinitrobenzene (TATB) and their kinetic isotope effect
Authors: Steele Brad A.
Published: February 2023

2,4,6-triamino-1,3,5-trinitrobenzene (TATB) is an insensitive High Explosive (HE) that is widely studied to better understand the physical properties of safety and sensitivity of HE. A dominant initial decomposition mechanism of TATB is believed to be a dehydration reaction that forms mono- and di-furazans, although other mechanisms have been reported. In this work, seven initial decomposition mechanisms were modeled with ab initio simulations to calculate its free energy barriers, decomposition rates, and kinetic isotope effects. The energy barrier for mono-benzofurazan mechanisms was found to be high, >61 kcal/mol in the gas phase; however, the reaction energy can decrease significantly in a disordered condensed state. The predicted kinetic isotope effect ratio of the furazan mechanism was found to be kh/kd≈ 1.41 at 600 K, in agreement with the experiment. The NO2 scission mechanism was found to be an entropy-driven mechanism because the free energy barrier decreased significantly with temperature, making it the most energetically favorable mechanism at high temperatures in the gas phase. The results provide a better understanding of the atomistic decomposition mechanisms of TATB and may be useful for improving models of safety and sensitivity.
Understanding multi-regime detonation development for hydrogen and syngas fuels
Authors: Pan J. , Yi D. , Wang L. , Liang W. , Shu G. , Wei H.
Published: February 2023

Autoignition and detonation development are foundational events in the combustion community and are fundamentally relevant to engine knocking and detonation propulsion. Autoignition-induced reaction front propagation modes have been extensively investigated, addressing the role of thermal and concentration inhomogeneities. In this work, we have further investigated the nonmonotonic response of detonation development to temperature gradients for low-carbon fuels (hydrogen and syngas) and have found additional detonation regimes, which can depict the panorama of reaction front propagation modes. Results show that separate detonation regimes can be observed when hotspot sizes are below some critical thresholds, with the first corresponding to the known “Bradley detonation peninsula” and the second newly identified featuring broader detonation regions. Despite this, distinct combustion characteristics are observed in the demarcation of detonation regimes between hydrogen and syngas fuels. Specifically, the upper branch of the first detonation regimes for hydrogen is sensitive to temperature gradients at various hotspot sizes, while it exhibits similar behaviors in the lower branch of the second one for syngas, which results in narrower detonation regions. Meanwhile, hydrogen possesses a larger critical hotspot size compared to syngas, and the underlying mechanism is ascribed to the chemical reactivity when hotspot autoignition and the difference of energy density between hotspot interior and exterior. Finally, various detonation regimes are summarized in dimensionless detonation diagrams, in which hydrogen and syngas show similar distributions of detonation peninsula. Despite this, those distinctions in the detonation characteristics between hydrogen and syngas can still be manifested quantitatively. The current work can provide useful insights into knocking inhabitation and detonation promotion.
Epitaxial growth and scanning tunneling microscopy of LiV2O4 thin films on SrTiO3(111)
Authors: Schweizer T. F. , Niemann U. , Que X. , He Q. , Zhou L. , Kim M. , Takagi H. , Huang D.
Published: February 2023

LiV2O4 is a mixed-valent spinel oxide and one of a few transition-metal compounds to host a heavy fermion phase at low temperatures. Although numerous experimental studies have attempted to elucidate how its 3d electrons undergo giant mass renormalization, spectroscopic probes that may provide crucial hints, such as scanning tunneling microscopy (STM), remain to be applied. A prerequisite is atomically flat and pristine surfaces, which, in the case of LiV2O4, are difficult to obtain by the cleavage of small, three-dimensional crystals. We report the epitaxial growth of LiV2O4 thin films with bulklike properties on SrTiO3(111) via pulsed laser deposition and stable STM imaging of the LiV2O4(111) surface. The as-grown films were transferred ex situ to a room-temperature STM, where subsequent annealing with optional sputtering in ultrahigh vacuum enabled compact islands with smooth surfaces and a hexagonal 1 × 1 atomic lattice to be resolved. Our STM measurements provide insights into the growth mechanisms of LiV2O4 on SrTiO3(111) as well as demonstrate the feasibility of performing surface-sensitive measurements of this heavy fermion compound.
Resolvent-based analysis of hypersonic turbulent boundary layers with/without wall cooling
Authors: Sandberg Richard D.
Published: February 2023

The ability of the low-rank approximation of hypersonic turbulent boundary layers with/without wall cooling is examined with the linear resolvent operator in a compressible form. The freestream Mach number of the base flow is 5.86, and the friction Reynolds number is 420. The wall-to-recovery temperature ratio is set as 1.0 and 0.25, respectively, corresponding to an adiabatic wall condition and a cold-wall condition. Different from the resolvent analysis of incompressible turbulent boundary layers, the optimal response mode in the wave-parameter space exhibits a relatively subsonic and a relatively supersonic region [Bae et al., “Resolvent-based study of compressibility effects on supersonic turbulent boundary layers,” J. Fluid Mech. 883, A29 (2020)], divided by the freestream relative Mach number of unity. The features of energy distribution of the optimal response mode in space and scales are examined, and the energy spectra of streamwise velocity and temperature fluctuations, carried by the optimal response mode, are discussed with typical subsets of streamwise and spanwise wavelengths. This reveals the dynamics of the near-wall small-scale and outer larger-scale motions and the distinction in the relatively subsonic/supersonic region. Moreover, the coherent structures, including the velocity and temperature streaks, quasi-streamwise vortices, and large-scale/very-large-scale motions, are identified in the optimal response mode. Special attention is paid to the effects of wall cooling.
Hirota bilinear method and multi-soliton interaction of electrostatic waves driven by cubic nonlinearity in pair-ion–electron plasmas
Authors: Batool Nazia , Masood W. , Siddiq M. , Alrowaily Albandari W. , Ismaeel Sherif M. E. , El-Tantawy S. A.
Published: February 2023

Multi-soliton interaction of nonlinear ion sound waves in a pair-ion–electron (PIE) plasma having non-Maxwellian electrons including Kappa, Cairns, and generalized two spectral index distribution functions is studied. To this end, a modified Korteweg–de Vries (mKdV) equation is obtained to investigate the ion-acoustic waves in a PIE plasma at a critical plasma composition. The effects of temperature and density ratios and the non-Maxwellian electron velocity distributions on the overtaking interaction of solitons are explored in detail. The results reveal that both hump (positive peak) and dip (negative peak) solitons can propagate for the physical model under consideration. Two and three-soliton interactions are presented, and the novel features of interacting compressive and rarefactive solitons are highlighted. The present investigation may be useful in laboratory plasmas where PIE plasmas have been reported.
Bioprospecting for and the applications of halophilic acidophiles in bioleaching operations
Authors: Corbett Melissa K. , Watkin Elizabeth L. J.
Published: February 2023

The economic recovery of metals from sulfide ores has become a topic of increasing interest due to the escalating demand for critical minerals and the reducing grade of available ores. Bioleaching is the use of acidophilic iron and sulfur-oxidising microorganisms to facilitate the extraction of base metals from primary sulfide ores and tailings. One significant issue limiting the use of bioleaching is the availability of freshwater due to the sensitivity of these microbes to chloride. The use of saline tolerant acidophilic iron- and-sulfur oxidising microorganisms will go a long way to addressing this issue. There are three possible means of sourcing suitable microorganisms; adaptation, genetic engineering and bioprospecting, with bioprospecting showing the greatest possibilities. Bioprospecting in search of native organisms for bioleaching operations has led researchers to numerous locations around the world and the isolation of iron- and sulfur-oxidising acidophiles that are capable of tolerating high levels of salinity has been of particular interest in these investigations.
A synthetic porphyrin as an effective dual antidote against carbon monoxide and cyanide poisoning
Authors: Mao Qiyue , Zhao Xuansu , Kiriyama Akiko , Negi Shigeru , Fukuda Yasutaka , Yoshioka Hideki , Kawaguchi Akira T. , Motterlini Roberto , Foresti Roberta , Kitagishi Hiroaki
Published: February 2023

Simultaneous poisoning by carbon monoxide (CO) and hydrogen cyanide is the major cause of mortality in fire gas accidents. Here, we report on the invention of an injectable antidote against CO and cyanide (CN
–
) mixed poisoning. The solution contains four compounds: iron(III)porphyrin (Fe
III
TPPS, F), two methyl-β-cyclodextrin (CD) dimers linked by pyridine (Py3CD, P) and imidazole (Im3CD, I), and a reducing agent (Na
2
S
2
O
4
, S). When these compounds are dissolved in saline, the solution contains two synthetic heme models including a complex of F with P (hemoCD-P) and another one of F with I (hemoCD-I), both in their iron(II) state. hemoCD-P is stable in its iron(II) state and captures CO more strongly than native hemoproteins, while hemoCD-I is readily autoxidized to its iron(III) state to scavenge CN
–
once injected into blood circulation. The mixed solution (hemoCD-Twins) exhibited remarkable protective effects against acute CO and CN
–
mixed poisoning in mice (~85% survival vs. 0% controls). In a model using rats, exposure to CO and CN
–
resulted in a significant decrease in heart rate and blood pressure, which were restored by hemoCD-Twins in association with decreased CO and CN
–
levels in blood. Pharmacokinetic data revealed a fast urinary excretion of hemoCD-Twins with an elimination half-life of 47 min. Finally, to simulate a fire accident and translate our findings to a real-life scenario, we confirmed that combustion gas from acrylic cloth caused severe toxicity to mice and that injection of hemoCD-Twins significantly improved the survival rate, leading to a rapid recovery from the physical incapacitation.
Rotational dive into the water clusters on a simple sugar substrate
Authors: Steber Amanda L. , Temelso Berhane , Kisiel Zbigniew , Schnell Melanie , Pérez Cristóbal
Published: February 2023

Most biomolecular activity takes place in aqueous environments, and it is strongly influenced by the surrounding water molecules. The hydrogen bond networks that these water molecules form are likewise influenced by their interactions with the solutes, and thus, it is crucial to understand this reciprocal process. Glycoaldehyde (Gly), often considered the smallest sugar, represents a good template to explore the steps of solvation and determine how the organic molecule shapes the structure and hydrogen bond network of the solvating water cluster. Here, we report a broadband rotational spectroscopy study on the stepwise hydration of Gly with up to six water molecules. We reveal the preferred hydrogen bond networks formed when water molecules start to form three-dimensional (3D) topologies around an organic molecule. We observe that water self-aggregation prevails even in these early stages of microsolvation. These hydrogen bond networks manifest themselves through the insertion of the small sugar monomer in the pure water cluster in a way in which the oxygen atom framework and hydrogen bond network resemble those of the smallest three-dimensional pure water clusters. Of particular interest is the identification, in both the pentahydrate and hexahydrate, of the previously observed prismatic pure water heptamer motif. Our results show that some specific hydrogen bond networks are preferred and survive the solvation of a small organic molecule, mimicking those of pure water clusters. A many-body decomposition analysis of the interaction energy is also performed to rationalize the strength of a particular hydrogen bond, and it successfully confirms the experimental findings.
Elevated dementia risk, cognitive decline, and hippocampal atrophy in multisite chronic pain
Authors: Zhao Wenhui , Zhao Lei , Chang Xiangyu , Lu Xuejing , Tu Yiheng
Published: February 2023

Numerous studies have investigated the impacts of common types of chronic pain (CP) on patients’ cognitive function and observed that CP was associated with later dementia. More recently, there is a growing recognition that CP conditions frequently coexist at multiple body sites and may bring more burdens on patients’ overall health. However, whether and how multisite CP (MCP) contributes to an increased risk of dementia, compared to single-site CP (SCP) and pain-free (PF), is largely unclear. In the current study, utilizing the UK Biobank cohort, we first investigated dementia risk in individuals (n = 354,943) with different numbers of coexisting CP sites using Cox proportional hazards regression models. We then applied generalized additive models to investigate whether MCP leads to excessive deterioration of participants’ (n = 19,116) cognition and brain structure. We found that individuals with MCP were associated with significantly higher dementia risk, broader and faster cognitive impairment, and greater hippocampal atrophy than both PF individuals and those with SCP. Moreover, the detrimental effects of MCP on dementia risk and hippocampal volume aggravated along with the number of coexisting CP sites. Mediation analyses further revealed that the decline of fluid intelligence in MCP individuals was partially mediated by hippocampal atrophy. Our results suggested that cognitive decline and hippocampal atrophy interact biologically and may underlie the increased risk of dementia associated with MCP.
Robust machine learning segmentation for large-scale analysis of heterogeneous clinical brain MRI datasets
Authors: Billot Benjamin , Magdamo Colin , Cheng You , Arnold Steven E. , Das Sudeshna , Iglesias Juan Eugenio
Published: February 2023

Every year, millions of brain MRI scans are acquired in hospitals, which is a figure considerably larger than the size of any research dataset. Therefore, the ability to analyze such scans could transform neuroimaging research. Yet, their potential remains untapped since no automated algorithm is robust enough to cope with the high variability in clinical acquisitions (MR contrasts, resolutions, orientations, artifacts, and subject populations). Here, we present
SynthSeg
+
, an AI segmentation suite that enables robust analysis of heterogeneous clinical datasets. In addition to whole-brain segmentation,
SynthSeg
+
also performs cortical parcellation, intracranial volume estimation, and automated detection of faulty segmentations (mainly caused by scans of very low quality). We demonstrate
SynthSeg
+
in seven experiments, including an aging study on 14,000 scans, where it accurately replicates atrophy patterns observed on data of much higher quality.
SynthSeg
+
is publicly released as a ready-to-use tool to unlock the potential of quantitative morphometry.
Size- and position-dependent cytoplasm viscoelasticity through hydrodynamic interactions with the cell surface
Authors: Najafi Javad , Dmitrieff Serge , Minc Nicolas
Published: February 2023

Many studies of cytoplasm rheology have focused on small components in the submicrometer scale. However, the cytoplasm also baths large organelles like nuclei, microtubule asters, or spindles that often take significant portions of cells and move across the cytoplasm to regulate cell division or polarization. Here, we translated passive components of sizes ranging from few up to ~50 percents of the cell diameter, through the vast cytoplasm of live sea urchin eggs, with calibrated magnetic forces. Creep and relaxation responses indicate that for objects larger than the micron size, the cytoplasm behaves as a Jeffreys material, viscoelastic at short timescales, and fluidizing at longer times. However, as component size approached that of cells, cytoplasm viscoelastic resistance increased in a nonmonotonic manner. Flow analysis and simulations suggest that this size-dependent viscoelasticity emerges from hydrodynamic interactions between the moving object and the static cell surface. This effect also yields to position-dependent viscoelasticity with objects initially closer to the cell surface being harder to displace. These findings suggest that the cytoplasm hydrodynamically couples large organelles to the cell surface to restrain their motion, with important implications for cell shape sensing and cellular organization.
On the identification of hyperhydrated sodium chloride hydrates, stable at icy moon conditions
Authors: Journaux Baptiste , Pakhomova Anna , Collings Ines E. , Petitgirard Sylvain , Boffa Ballaran Tiziana , Brown J. Michael , Vance Steven D. , Chariton Stella , Prakapenka Vitali B. , Huang Dongyang , Ott Jason , Glazyrin Konstantin , Garbarino Gaston , Comboni Davide , Hanfland Michael
Published: February 2023

Sodium chloride is expected to be found on many of the surfaces of icy moons like Europa and Ganymede. However, spectral identification remains elusive as the known NaCl-bearing phases cannot match current observations, which require higher number of water of hydration. Working at relevant conditions for icy worlds, we report the characterization of three “hyperhydrated” sodium chloride (SC) hydrates, and refined two crystal structures [2NaCl·17H
2
O (SC8.5); NaCl·13H
2
O (SC13)]. We found that the dissociation of Na
+
and Cl
−
ions within these crystal lattices allows for the high incorporation of water molecules and thus explain their hyperhydration. This finding suggests that a great diversity of hyperhydrated crystalline phases of common salts might be found at similar conditions. Thermodynamic constraints indicate that SC8.5 is stable at room pressure below 235 K, and it could be the most abundant NaCl hydrate on icy moon surfaces like Europa, Titan, Ganymede, Callisto, Enceladus, or Ceres. The finding of these hyperhydrated structures represents a major update to the H
2
O–NaCl phase diagram. These hyperhydrated structures provide an explanation for the mismatch between the remote observations of the surface of Europa and Ganymede and previously available data on NaCl solids. It also underlines the urgent need for mineralogical exploration and spectral data on hyperhydrates at relevant conditions to help future icy world exploration by space missions.
Species coexistence by wide constant size spacing
Authors: Pimm Stuart L. , Diamond Jared , Bishop K. David
Published: February 2023

We consider the distribution of fruit pigeons of the genera
Ptilinopus
and
Ducula
on the island of New Guinea. Of the 21 species, between six and eight coexist inside humid lowland forests. We conducted or analyzed 31 surveys at 16 different sites, resurveying some sites in different years. The species coexisting at any single site in a single year are a highly nonrandom selection of the species to which that site is geographically accessible. Their sizes are both much more widely spread and more uniformly spaced than in random sets of species drawn from the locally available species pool. We also present a detailed case study of a highly mobile species that has been recorded on every ornithologically explored island in the West Papuan island group west of New Guinea. That species’ rareness on just three well-surveyed islands within the group cannot be due to an inability to reach them. Instead, its local status decreases from abundant resident to rare vagrant in parallel with increasing weight proximity of the other resident species.
Different functions of ‘rā’ in New Persian
Authors: Rasekh-Mahand Mohammad , Parizadeh Mehdi
Published: February 2023

Persian has a polyfunctional case marker, ‘rā’, which diachronically varies greatly in the range
of functions it covers. In this paper, we give an account of different case functions of ‘rā’, in New Persian, an
era from the 8th century (C.E.) to present. To analyze the functionality of ‘rā’ in different texts, we selected
78 books from the New and Contemporary Persian eras and studied one thousand tokens of ‘rā’ from each century.
The data show that ‘rā’ has been a polyfunctional case marker in New Persian, marking about 13 different case
roles. Its main role was to mark direct objects, and gradually it has become its sole function in Contemporary Persian. However,
during the time span, some of the ‘rā’-marked roles remained constant and some of them replaced
‘rā’ with other adpositions. We follow a historical semantic map approach as a typological grid to examine
our data. The findings show that ‘rā’ has shifted from animate to inanimate concepts gradually. While in the 12th
century about 750 out of 1000 (about 75%) roles marked with ‘rā’ were animate, it has decreased to about 400 out
of 1000 (about 42%) in the 19th century and less than 30% in the 20th century. Our data show that ‘rā’ has not
gone further to mark inanimate relations, and it has gone toward core case roles, specifically direct object.
Retinoic acid signaling during priming licenses intestinal CD103+ CD8 TRM cell differentiation
Authors: Qiu Zhijuan , Khairallah Camille , Chu Timothy H. , Imperato Jessica N. , Lei Xinyuan , Romanov Galina , Atakilit Amha , Puddington Lynn , Sheridan Brian S.
Published: February 2023

CD8 tissue-resident memory T (TRM) cells provide frontline protection at barrier tissues; however, mechanisms regulating TRM cell development are not completely understood. Priming dictates the migration of effector T cells to the tissue, while factors in the tissue induce in situ TRM cell differentiation. Whether priming also regulates in situ TRM cell differentiation uncoupled from migration is unclear. Here, we demonstrate that T cell priming in the mesenteric lymph nodes (MLN) regulates CD103+ TRM cell differentiation in the intestine. In contrast, T cells primed in the spleen were impaired in the ability to differentiate into CD103+ TRM cells after entry into the intestine. MLN priming initiated a CD103+ TRM cell gene signature and licensed rapid CD103+ TRM cell differentiation in response to factors in the intestine. Licensing was regulated by retinoic acid signaling and primarily driven by factors other than CCR9 expression and CCR9-mediated gut homing. Thus, the MLN is specialized to promote intestinal CD103+ CD8 TRM cell development by licensing in situ differentiation.
Tuning the Mottness in Sr3Ir2O7 via Bridging Oxygen Vacancies
Authors: Xu Miao , Zou Changwei , Gong Benchao , Jia Ke , Ye Shusen , Hao Zhenqi , Liu Kai , Shi Youguo , Lu Zhong-Yi , Cai Peng , Wang Yayu
Published: February 2023

The electronic evolution of Mott insulators into exotic correlated phases remains puzzling, because of electron interaction and inhomogeneity. Introduction of individual imperfections in Mott insulators could help capture the main mechanism and serve as a basis to understand the evolution. Here we utilize scanning tunneling microscopy to probe the atomic scale electronic structure of the spin-orbit-coupling assisted Mott insulator Sr3Ir2O7. It is found that the tunneling spectra exhibit a homogeneous Mott gap in defect-free regions, but near the oxygen vacancy in the rotated IrO2 plane the local Mott gap size is significantly enhanced. We attribute the enhanced gap to the locally reduced hopping integral between the 5d electrons of neighboring Ir sites via the bridging planar oxygen p orbitals. Such bridging defects have a dramatic influence on local bandwidth, thus provide a new way to manipulate the strength of Mottness in a Mott insulator.
Einstein and Jordan-frame covariant Hamiltonians for F(R) gravity and their canonical relationships
Authors: Klusoň J , Matouš B
Published: February 2023

This paper is devoted to the analysis of the covariant canonical formalism ofF(R) gravity in Einstein frame. We also find canonical transformation between covariant canonical formulation ofF(R) gravity in Jordan frame and Einstein frames and we also determine corresponding generating function.
Proposal for Zeeman slowing of Rb2 molecules in a supersonic beam, inducing internal cooling
Authors: Alejandro Lefrán Torres Manuel , Fernandes Passagem Henry , Rodríguez Fernández David , da Costa Paul Eduardo , Adan Mojica Casique Cristian , Dulieu Olivier , Bouloufa-Maafa Nadia , Gustavo Marcassa Luis
Published: February 2023

We present a theoretical proposal on Zeeman slowing of a Rb2 supersonic beam, relying on transitions between rovibrational levels of the

X
1

Σ
g
+

electronic ground-state and the

B

1

Π

u

electronic excited state. Translational cooling is induced by optical transitions from

v
X

⩽
13
,

J
X

⩽
13

to

v
B

=
0

involving P (

J
B

=

J
X

−
1

) and Q (

J
B

=

J
X

) branches. This is achieved by shaping the spectrum of broadband laser sources, in addition to two single-frequency laser sources addressing the

X
1

Σ
g
+

(

v

X

=
2
,
3
,

J

X

=
1
)
→

B

1

Π

u

(

v

B

=
0
,

J
B

=
1
)

transitions. Our Monte–Carlo simulations indicate that the velocity of the molecules can be slowed from 500 m s−1 down to a few m s−1 by a Zeeman slower with a 1.2 m length, after scattering about 150 000 photons. At the end of the slowing process, half of the molecules are internally cooled, predicted to be in the

v

X

=
2
,
3
,

J
X

=
1

ground-state levels. A final optical pumping step transferring the population to the

v

X

=
0
,

J
X

=
1

ground-state level could produce a molecular beam exiting the Zeeman slower which is cold in all the translational, vibrational, and rotational degrees of freedom. Such an approach could potentially be a great interest for cooling down a large class of molecular species.
Rapid forecasting of hydrogen concentration based on a multilayer CNN-LSTM network
Authors: Shi Yangyang , Ye Shenghua , Zheng Yangong
Published: February 2023

Gas sensors with rapid response are desirable in many safety applications. Reducing the response time of gas sensors is a challenging task. Computing a part of the initial temporal signals of gas sensors based on neural networks is an effective and powerful method for forecasting sensors’ output. To rapidly and robust forecasting hydrogen concentration, a sensor array is composed of a temperature and humidity sensor, and two hydrogen sensors. A neural network combined with convolutional neural networks and long-short-term memory networks is proposed to fuse temporal signals of the sensor array to forecast hydrogen concentrations. The structure of the neural network is optimized by increasing its depth. For the optimal neural network, the lowest mean absolute percent error is about 12.8% by computing initial 30 s of transient signals within 300–400 s response curves, the predicted mean absolute error is 1158 ppm in the testing range of 18 000 ppm. When the time span of initial transient signals of the sensor array increase to 150 s for the computing, the mean absolute percent error decreases to 5.7%. This study verifies the potential and effectiveness of the neural network for concentration forecasting by computing the temporal signals of the sensors.
Study on abnormal gait and fall warning method using wearable sensors and a human musculoskeletal model
Authors: Jia Xiaohui , Li Jiarui , Liu Jinyue , Li Tiejun , Yang Hua
Published: February 2023

An accurate and timely prediction of falls in a complex environment is vital for population groups such as workers, the elderly, and power-assisted exoskeleton wearers. Enhancing the universality of fall warning methods has been regarded as one of the primary challenges in the field of precise anomaly detection and fall prediction. To address this issue, a gait abnormality detection and fall warning method is proposed in this paper. First, a wearable data acquisition system integrated with inertial measurement units and capacitive plantar pressure sensors is used to obtain real data on feet. Second, a human musculoskeletal model is built in AnyBody software to obtain simulation data on feet. By comparison, the effectiveness of the simulation model is verified and the characteristics of abnormal gait are determined. Third, a backpropagation network is cleverly combined with the hidden Markov model. The cooperation of neural network and probabilistic model is employed to detect the abnormal gait sequence before falling and make a first-level fall warning. Then, a mapping model between the real and simulation plantar pressures is constructed using a multiple linear regression algorithm to weaken the difference of stability thresholds of different people and conduct second-level fall warning. Finally, two common fall patterns, tripping and slipping, are used to test the proposed fall waring method. The average sensitivity, specificity, and accuracy of the gait anomaly detection and stability judgment are used as evaluation metrics. The results indicate that the proposed method achieves average sensitivity, specificity, and accuracy of 100%, 97%, and 98.5%, and of 100%, 96%, and 98%, on tripping and slipping patterns, respectively. Moreover, the proposed method could assess pedestrian stability and provide fall warnings of more than 300 ms before a fall occurs.
Significance of the inclined magnetic field on the water-based hybrid nanofluid flow over a nonlinear stretching sheet
Authors: Algehyne Ebrahem A , Al-Bossly Afrah , Alduais Fuad S , Almusawa Musawa Yahya , Saeed Anwar
Published: February 2023

This work addresses a theoretical exploration of the water-based hybrid nanofluid flow over a nonlinear elongating surface. The flow is taken under the effects of Brownian motion and thermophoresis factors. Additionally, the inclined magnetic field is imposed in the present study to investigate the flow behavior at different angle of inclination. Homotopy analysis approach is used for the solution of modeled equations. Various physical factors, which are encountered during process of transformation, have been discussed physically. It is found that the magnetic factor and angle of inclination have reducing impacts on the velocity profiles of the nanofluid and hybrid nanofluid. The nonlinear index factor has direction relation with the velocity and temperature of the nanofluid and hybrid nanofluid flows. The thermal profiles of the nanofluid and hybrid nanofluid are augmented with the increasing thermophoretic and Brownian motion factors.

C
u
O
−

H

2

O

nanofluid flow has enhanced heat transfer rate than

A
g
−

H

2

O

nanofluid flow. On the other hand, the

C
u
O
−
A
g
/

H

2

O

hybrid nanofluid has better thermal flow rate than

C
u
O
−

H

2

O

and

A
g
−

H

2

O

nanofluids. From this table it has noticed that, Nusselt number has increased by 4% for silver nanoparticles whereas for hybrid nanofluid this incrimination is about 15%, which depicts that Nusselt number is higher for hybrid nanoparticles.
High pointwise emergence via saturated sets
Authors: Hou Xiaobo , Lin Wanshan , Tian Xueting
Published: February 2023

In this article, we prove that the set of points whose pointwise emergence have same degree in

[
1
,
∞
]

with repect to polynomial has strong dynamical complexity in sense of entropy, residuality and density, and distributional chaos for a β-shift, a C
1 diffeomorphism having a nontrival homoclinic class, or a

C

1
+
α

diffeomorphism preserving a hyperbolic ergodic measure. In this process, we construct nonempty compact connected set with fixed box-counting dimension in the space of invariant measures. Then combining with the relation between pointwise emergence of saturated set and box-counting dimension, we get the goal from two frameworks about dynamical complexity of saturated set. One framework was introduced by C. Pfister and W. Sullivan and can be applicable to transitive Anosov diffeomorphisms, mixing expanding maps, β-shifts, transitive subshifts of finite type, mixing sofic subshifts, and mixing S-gap shifts. The other framework is applicable to general homoclinic classes and diffeomorphisms preserving hyperbolic ergodic measures. We also get some combined observations with irregular set.
Locally maximising orbits for the non-standard generating function of convex billiards and applications
Authors: Bialy Misha , Tsodikovich Daniel
Published: February 2023

Given an exact symplectic map T of a cylinder with a generating function H satisfying the so-called negative twist condition,

H

12

>
0

, we study the locally maximising orbits of T, that is, configurations which are local maxima of the action functional

∑
n

H
(

q
n

,

q

n
+
1

)

. We provide a necessary and sufficient condition for a configuration to be locally maximising. Using it, we consider a situation where T has two generating functions with respect to two different sets of symplectic coordinates. We suggest a simple geometric condition which guarantees that the set of locally maximising orbits with respect to both of these generating functions coincide. As the main application we show that the two generating functions for planar Birkhoff billiards satisfy this geometric condition. We apply it to get the following result: consider a centrally symmetric curve γ, for which the Birkhoff billiard map has a rotational invariant curve α of four-periodic orbits. We prove that a certain L
2-distance between γ and its ‘best approximating’ ellipse can be bounded from above in terms of the measure of the complement of the set filled by locally maximising orbits lying between α and the boundary of the phase cylinder. Moreover, this estimate is sharp, giving an effective version of a recent result on Birkhoff conjecture for centrally symmetric curves (Bialy and Mironov 2022 Ann. Math.
196 389–413). We also get a similar bound for arbitrary curves γ, that relates the measure of the complement of the set of locally maximising orbits with the L
2-distance between γ and its ‘best approximating’ circle.
A feasibility study on removing lipid deposition in atherosclerotic plaques with ultrasound-assisted laser ablation
Authors: Singh Rohit , Ebersole Koji C , Yang Xinmai
Published: February 2023

Objective. Atherosclerosis is the buildup of fats, cholesterol, and other substances on the inner walls of arteries. It can affect arteries of heart, brain, arms, legs, pelvis and kidney, resulting in ischemic heart disease, carotid artery disease, peripheral artery disease and chronic kidney disease. Laser-based treatment techniques like laser atherectomy can be used to treat many common atherosclerostic diseases. However, the use of laser-based treatment remains limited due to the high risk of complications and low efficiency in removing atherosclerostic plaques as compared with other treatment methods. In this study, we developed a technology that used high intensity focused ultrasound to assist laser treatment in the removal of the lipid core of atherosclerotic plaques.Approach. The fundamental mechanism to disrupt atherosclerostic plaque was to enhance the mechanical effect of cavitation during laser/ultrasound therapy. To promote cavitation, spatiotemporally synchronized ultrasound bursts of 2% duty cycle at 0.5 MHz and nanosecond laser pulses at 532 nm wavelength were used. Experiments were first performed on pig belly fat samples to titrate ultrasound and laser parameters. Then, experiments were conducted on human plaque samples, where the lipid depositions of the plaques were targeted.Main results. Our results showed that fat tissue could be removed with an ultrasound peak negative pressure (PNP) of 2.45 MPa and a laser radiant exposure as low as 3.2 mJ mm−2. The lipid depositions on the atherosclerostic plaques were removed with laser radiant exposure of 16 mJ mm−2in synchronizing with an ultrasound PNP of 5.4 MPa. During all the experiments, laser-only and ultrasound-only control treatments at the same energy levels were not effective in removing the lipid.Significance. The results demonstrated that the addition of ultrasound could effectively reduce the needed laser power for atherosclerotic plaque removal, which will potentially improve treatment safety and efficiency of current laser therapies.
Applicability of LPBF for producing Cu-11Al-5Ni-4Fe wt.% with shape memory properties
Authors: Guerra C , Ramos-Grez J A , La Fé-Perdomo I , Castillo A , Walczak M
Published: February 2023

The Cu-11Al-5Ni-4Fe wt% alloy was consolidated by additive manufacturing (AM) to determine the method applicability for producing shape memory alloy. The alloy was researched through compressive stress in three conditions: commercial (COM) (cast), as-built (AB), and AB heat treated (quenched). The results demonstrated that the AB sample acquired a reasonable superelasticity (SE) at room temperature (∼4%), which was improved to 6% after quenching. The COM sample damping capacity was better at high temperatures (350 °C) due to slip system activation at low stress (near 600 MPa), which resulted in a higher deformation energy dissipation. Due to the residual stress and null slip activation, the AB samples showed low damping capacity and low permanent strain at any temperature; however, they showed greater degree of SE. The AM technique of laser powder bed fabrication is concluded to be a viable option for producing printed parts with SE and damping properties.
A DFT modulated analysis of manganese doped graphene nanoribbons as a potential material for sensing of highly toxic gases CO, PH3 and SbH3
Authors: R Jyoti , Chauhan Moondeep , Kashyap Rajiv , Singh Mehar , Choudhary B C , Sharma Ramesh K
Published: February 2023

A theoretical Density-functional theory (DFT) study has been carried out to explore the interaction of highly toxic gases carbon monoxide (CO), phosphine (PH3) and stibine (SbH3) with pristine (AGNR) and manganese (Mn) doped armchair graphene nanoribbon (AGNR-Mn). The adsorption behaviour of these gases has been analyzed by calculating the binding distance, adsorption energy (Eads), band structure, density of state spectrum, and current-voltage characteristics. In the case of AGNR, the highest Eads = −0.19 eV has been observed for the CO gas. The Mn doping leads to the high stability and substantial improvement in adsorption performance due to covalent interaction with gas molecules. The enhancement in adsorption energy by 19, 26 and 23 times for CO, PH3 and SbH3 respectively has been observed using AGNR-Mn instead of AGNR. The adsorption of these gases shows a considerable enhancement in the DOS around Fermi level. Furthermore, using I-V characteristics, the response of all these gases is observed and it has been found that the response of PH3 and SbH3 gas to AGNR-Mn are 48% and 45% respectively. These findings indicate that the AGNR-Mn system can be explored as a highly sensitive material for potential gas sensing of PH3 and SbH3.
High-speed Focal Plane Wave Front Sensing with an Optical Chopper
Authors: Gerard Benjamin L. , Dillon Daren , Cetre Sylvain , Jensen-Clem Rebecca
Published: February 2023

Focal plane wave front sensing and control is a critical approach to reducing noncommon path errors between a conventional astronomical adaptive optics (AO) wave front sensor (WFS) detector and a science camera. However, in addition to mitigating noncommon path errors, recent focal plane wave front sensing techniques have been developed to operate at speeds fast enough to enable “multi-WFS” AO, where residual atmospheric errors are further corrected by a focal plane WFS. Although a number of such techniques have been recently developed for coronagraphic imaging, here we present one designed for noncoronagraphic imaging. Utilizing conventional AO system components, this concept additionally requires (1) a detector imaging the focal plane of the WFS light source and (2) a pupil plane optical chopper device that is the noncommon path to the first WFS and is synchronized to the focal plane imager readout. These minimal hardware requirements enable the temporal amplitude modulation to resolve the sine ambiguity of even wave-front modes for low, mid, and high wave front spatial frequencies. Similar capabilities have been demonstrated with classical phase diversity by defocusing the detector, but such techniques are incompatible with simultaneous science observations. This optical chopping technique, however, enables science imaging at up to 50% duty cycle. We present both simulations and laboratory validation of this concept on SEAL, the Santa Cruz Extreme AO Laboratory testbed.
Magnetic island formation and rotation braking induced by low-Z impurity penetration in an EAST plasma
Authors: Zeng Shiyong , Zhu Ping , Zhou Ruijie , Xu Ming
Published: February 2023

Recent observations of the successive formations of the

4

/

1
,
3

/

1

, and

2

/

1

magnetic islands as well as the subsequent braking of the

2

/

1

mode during a low-Z impurity penetration process in EAST experiments are well reproduced in our 3D resistive MHD simulations. The enhanced parallel current perturbation induced by impurity radiation predominately contributes to the tearing mode growth, and the

2

/

1

island rotation is mainly damped by the impurity accumulation as results of the influence from high n modes.
Processing diagram for powder bed additive manufacturing
Authors: Koleva E , Kolev G , Koleva L
Published: February 2023

This paper presents the developed software for processing parameter simulation and optimization of powder bed additive manufacturing by concentrated energy beams. The simulations are realized by implementation of a normalized processing diagram and analytical model simulating heating of powder layers by a moving linear heat source. Their implementation is demonstrated for electron beam or laser additive manufacturing of industrial alloys. The developed software and the processing diagram provide a useful reference and methodology to support the selection of appropriate processing parameters during the early development stages of concrete powder bed additive manufacturing technology, building production digital twins or development of integrated process management system.
Atomic layer etching of nanowires using conventional reactive ion etching tool
Authors: Khan M B , Shakeel Sh , Richter K , Ghosh S , Erbe A , Georgiev Yo M
Published: February 2023

Innovative material and processing concepts are needed to further enhance the performance of complementary metal-oxide-semiconductor (CMOS) transistors-based circuits as the scaling limits are being reached. To supplement that, we report on the development of an atomic layer etching (ALE) process to fabricate small and smooth nanowires using a conventional dry etching tool. Firstly, a negative tone resist (hydrogen silsesquioxane) is spin-coated on Silicon Germanium-on-insulator (SiGeOI) samples and electron beam lithography is performed to create nanopatterns. These patterns act as an etch mask and are transferred into the SiGeOI layer using an inductively-coupled plasma reactive ion etching (ICP-RIE) process. Subsequently, an SF6 and Ar+ based ALE process is employed to smoothen the nanowires and reduce their widths. SF6 modifies the surface of the samples, while in the next step Ar+ removes the modified surface. To investigate the effect of this process on the nanowire width, several ALE cycles are performed. The etched features are inspected using scanning electron microscopy. With the increasing number of ALE cycles, a reduction in the width is observed. An etch per cycle of 1.1 Å is obtained.
A comprehensive study on the microstructure of plasma spraying coatings after electron beam remelting
Authors: St Węglowski M , Śliwiński P , Dymek S , Kalemba-Rec I , Kapuściński M , Wrona A , Kustra K
Published: February 2023

One of the most popular thermal spraying technology is atmospheric plasma spraying (APS). However, it should be noted, that numerous imperfections in the APS surface layers can be occurred. The porosity, microcracks as well as lamellar microstructure occurred. Moreover, the adhesion of the coating is limited. However, the reduction of porosity and other imperfections by remelting process can be eliminated. The laser or electron beams for remelting are the most popular technologies. Mainly, power of the beam and travelling speed influence on the thickness and the final properties of the remelted coatings. In the paper, the electron beam (EB) process for remelting of plasma spraying surface layers in relation to microstructure is presented. The Ni20%Cr + 30%Re APS coating on stainless steel substrate 316Ti grade by electron beam was remelted. The effect of remelting process on microstructure was presented. The light microscopy (LM) as well as scanning electron microscopy (SEM) and energy disperse spectroscopy (EDS) for microstructure analysis of APS coatings after EB remelting were used. The results show that the APS coatings subjected EB remelted becomes much denser. Moreover, the porosity was reduced and the chemical composition of the coatings after remelting became homogeneous.