bluuebunny/crossref_metadata_2025 huggingface dataset:
Ultrafast time-resolved structural changes of thin-film ferromagnetic metal heated with femtosecond optical pulses
Authors: Li Runze , Elsayed-Ali H. E. , Chen Jie , Dhankhar Dinesh , Krishnamoorthi Arjun , Rentzepis Peter M.
Published: August 2023

As a classic ferromagnetic material, nickel has been an important research candidate used to study dynamics and interactions of electron, spin, and lattice degrees of freedom. In this study, we specifically chose a thick, 150 nm ferromagnetic nickel (111) single crystal rather than 10–20 nm thin crystals that are typically used in ultrafast studies, and we revealed both the ultrafast heating within the skin depth and the heat transfer from the surface (skin) layer to the bulk of the crystal. The lattice deformation after femtosecond laser excitation was investigated by means of 8.04 keV subpicosecond x-ray pulses, generated from a table-top laser-plasma based source. The temperature evolution of the electron, spin, and lattice was determined using a three temperature model. In addition to coherent phonon oscillations, the blast force and sonic waves, induced by the hot electron temperature gradient, were also observed by monitoring the lattice contractions during the first couple of picoseconds after laser irradiation. This study further revealed the tens of picoseconds time required for heating the hundred nanometer bulk of the Ni (111) single crystals.
Status of research on non-conventional technology assisted single-point diamond turning
Authors: Chen Zhuang , Chen Guangjun , Yu Zhiwei , Huang Jiashuai , Wei Hong
Published: August 2023

With the increasing use of difficult-to-machine materials in aerospace applications, machining requirements are becoming ever more rigorous. However, traditional single-point diamond turning (SPDT) can cause surface damage and tool wear. Thus, it is difficult for SPDT to meet the processing requirements, and it has significant limitations. Research indicates that supplementing SPDT with unconventional techniques can, importantly, solve problems due to the high cutting forces and poor surface quality for difficult-to-machine materials. This paper first introduces SPDT and reviews research into unconventional techniques for use with SPDT. The machining mechanism is discussed, and the main advantages and disadvantages of various methods are investigated. Second, hybrid SPDT is briefly described, which encompasses ultrasonic-vibration magnetic-field SPDT, ultrasonic-vibration laser SPDT, and ultrasonic-vibration cold-plasma SPDT. Compared with the traditional SPDT method, hybrid SPDT produces a better optical surface quality. The current status of research into unconventional techniques to supplement SPDT is then summarized. Finally, future development trends and the application prospects of unconventional assisted SPDT are discussed.
Effects of simulated zero gravity on adhesion, cell structure, proliferation, and growth behavior, in glioblastoma multiforme
Authors: Altaie Saifaldeen , Alrawi Amera
Published: August 2023

All life on Earth has evolved under the influence of continuous gravity, and methods have been developed to balance this influence with the biological evolution of organisms at the cellular and system levels. However, when exposed to zero gravity in space, the balance between cell structure and external forces is destroyed, resulting in changes at the cellular level (e.g., cell morphology, adhesion, viability, apoptosis, etc.), and understanding the molecular mechanism of cell response to zero gravity will help to cope with diseases that rely on mechanical response. Therefore, biological research in space and zero gravity is a unique step in developing the best anti-cancer treatments, which is a great challenge to humanity. In this study, multicellular glioma cancer cells from a brain tumor in a 72-year-old Iraqi patient were subjected to simulated zero gravity for 24 h, and the results showed that most of the cells lost their adhesion, which is considered to be the first step toward cell apoptosis. In addition to the formation of multicellular spheroids, the results also showed that the inhibition rate for cell death was 32% in comparison to the control cells. Moreover, the cells showed a clear change in their cellular morphology and growth behavior. These results give new hope for fighting cancer distinctively, and such a treatment method has no side effects in comparison to traditional chemical and radiological ones.
Forming blood vessels from pluripotent stem cell
Authors: Green Leigh Ann
Published: August 2023

An in vitro method to study in vivo vascular development.
An 18.3 MJ charging and discharging pulsed power supply system for the space plasma environment research facility (SPERF): the subsystem for the magnetic mirror coil
Authors: E Peng , Guan Jian , Ma Xun , Ling Wenbin , Deng Weijun , Ding Mingjun , Kang Chuanhui , Zhao Juan , Li Hongtao , Tong Weiming , Li Liyi
Published: August 2023

The magnetic reconnection process relevant to that at the magnetotail is one of the research contents of the Space Plasma Environment Research Facility, which is under construction at the Harbin Institute of Technology in China. Two magnetic mirror sub-coils placed symmetrically in the vertical direction and connected in series cooperate with a dipole coil to generate a magnetic field environment similar to the Earth’s magnetotail. A capacitor-based pulsed power supply (PPS) system with a modular design is developed to excite two magnetic mirror sub-coils to generate a magnetic field with a magnetic flux density of not less than 200 G at the center of the two sub-coils. The PPS should deliver a pulsed current with a peak of more than 8 kA, and the duration of the current not be less than 95% of the peak over 5 ms to two magnetic mirror sub-coils when the charging voltage is not less than 20 kV. In addition, the duration from the peak to 10% of the peak is not more than 130 ms. The detailed design of the PPS is discussed in this paper, and a test method is designed to reduce the risk of damage to the wires and the connection between the wires and the coaxial cables of the PPS when the PPS discharges at a higher charging voltage. Finally, the discharge test of the PPS is carried out to verify the design of the PPS.
A tunable clamshell cavity for wavelike dark matter searches
Authors: Braggio C. , Carugno G. , Di Vora R. , Ortolan A. , Ruoso G. , Seyler D.
Published: August 2023

Here, we present a frequency tuning mechanism for microwave cavities designed for axion dark matter searches and show that it provides a range of at least 200 MHz for the fundamental mode TM010 resonant at ∼10 GHz. The apparatus is based on a clamshell cavity, with the two semi-cells held together at a fixed joint while the other side opens to tune the frequency of the resonant modes. Measurements of the cavity frequencies and quality factor were taken at liquid helium temperature as the aperture was increased incrementally to ∼2°. We show that the frequency shift is approximately linear with respect to the angle of aperture with no mode crossings present for an aperture less than 2°. Furthermore, the form factor and quality factor of the TM010 mode remain relatively constant throughout the tuning as predicted by simulation.
Observation of topological corner states in a D4-symmetric square lattice of split-ring resonators
Authors: Bobylev Daniel A. , Tikhonenko Dmitry I. , Khanikaev Alexander B. , Gorlach Maxim A. , Zhirihin Dmitry V.
Published: August 2023

Topological states offer an increased versatility in disorder-robust localization of electromagnetic waves at the edges and corners of photonic structures. In most of the cases, such properties are achieved due to the appropriate lattice symmetry. Here, by contrast, we explore an alternative design strategy where the topological states in a simple square lattice are tailored due to the orientation of non-centrosymmetric split-ring resonators comprising the meta-structure. We numerically predict the emergence of the nontrivial topological properties and confirm our prediction by fabricating the structure and observing the localized edge and corner states experimentally.
Coupled smoothed particle hydrodynamics and discrete element method for simulating coarse food particles in a non-Newtonian conveying fluid
Authors: Savari Chiya , Barigou Mostafa
Published: August 2023

A Lagrangian particle-based numerical framework based on smoothed particle hydrodynamics (SPH) coupled with a discrete element method (DEM) was used to simulate the flow behavior of coarse food particles in a non-Newtonian conveying fluid in a horizontal pipe. Nearly neutrally buoyant nearly spherical calcium-alginate particles were used as model food particles. The capability of the SPH–DEM methodology was successfully validated in non-Newtonian single-phase as well as in two-phase particle–liquid flows by comparing the local phase velocity flow field, radial particle distribution, and particle passage times with experimental Lagrangian measurements obtained by a technique of positron emission particle tracking. The simulations also yielded accurate predictions of flow pressure drop. In addition, detailed information was afforded on local particle spin, fluid pressure, and carrier fluid vorticity. The results demonstrate the high capability of the proposed numerical framework to predict the complex features of complex particle–liquid flows in pipes.
Effects of duty ratio on liquid- and polymer-surface treatment by a unipolar microsecond-pulsed helium atmospheric-pressure plasma jet
Authors: Bae Jin Hee , Mun Jong Jin , Seong Min Jeong , Kim Sun Ja , Joh Hea Min , Chung T. H.
Published: August 2023

Effects of duty ratio of a unipolar microsecond-pulsed helium atmospheric-pressure plasma jet (APPJ) on liquid- and polymer-surface treatments were investigated. In addition, changes in the plasma plume length, gas temperature, excitation temperature, discharge current, absorption power, and optical emission spectra were examined by varying the other operating parameters, such as applied voltage and additive flow of oxygen or water vapor. As an example of liquid sample, de-ionized water (DW) was exposed to an APPJ, and the concentrations of the reactive species generated in the DW were measured as functions of the operating parameters. Polycarbonate, polypropylene, and polymethylmethacrylate were employed as exemplary substrate materials to investigate the effect of plasma treatment on polymeric surfaces. The APPJ treatment increased the surface energy and changed the wetting characteristics of the surface from hydrophobic to hydrophilic. X-ray photoelectron spectroscopy results showed that a short-time plasma treatment with He and/or He/O2, He/H2O affects the surface wettability owing to the introduction of polar groups.
Point vortex dynamics on Kähler twistor spaces
Authors: Hohloch S. , Muarem G.
Published: August 2023

In this paper, we provide tools to study the dynamics of point vortex dynamics on CPn and the flag manifold F1,2(C3). These are the only Kähler twistor spaces arising from four-manifolds. We give an explicit expression for Green’s function on CPn, which enables us to determine the Hamiltonian H and the equations of motions for the point vortex problem on CPn. Moreover, we determine the momentum map μ:F1,2(C3)→su*(3) on the flag manifold.
Spectral localizer for line-gapped non-Hermitian systems
Authors: Cerjan Alexander , Koekenbier Lars , Schulz-Baldes Hermann
Published: August 2023

Short-ranged and line-gapped non-Hermitian Hamiltonians have strong topological invariants given by an index of an associated Fredholm operator. It is shown how these invariants can be accessed via the signature of a suitable spectral localizer. This numerical technique is implemented in an example with relevance to the design of topological photonic systems, such as topological lasers.
Capture of small clusters by ligand–solvent interaction
Authors: Zhang Ming-Yu , Liu An-An , Jiao Luyang , Zhang Shuhan , Jiang Lin-Han , Kong Xianglei , Pang Dai-Wen
Published: August 2023

Clusters are considered to become increasingly significant for elaborating the nanocrystal’s formation mechanism. However, capturing the clusters with high chemical potential is challenging because of the lack of effective strategies. In this work, the key role of ligand–solvent interaction has been revealed for the stabilization of clusters in silver telluride synthesis. The Flory interaction coefficient that comprehensively regards the temperature and dispersion, polarity, and hydrogen bonding of the solvent has been used to evaluate the ligand–solvent interaction and thus assist in the design of synthetic systems. Small silver telluride clusters have been successfully captured, and the composition of the smallest cluster is determined as Ag7Te8(SCy)2 (SCy represents the ligand). This work provides new insights into the design of cluster/nanocrystal synthesis systems and paves the way to revealing the mechanism of precursor–cluster–nanocrystal conversion.
Short-range order in amorphous oxygen-deficient TaOx thin films and its relation to electrical conductivity
Authors: Amrani Tamir , Basha Adham , Azulay Amram , Levi George , Kohn Amit , Goldfarb Ilan
Published: August 2023

Thin films of tantalum oxide hold promising functional properties for electronic applications such as resistive random-access memory. For this aim, correlating the structure and charge transport properties of oxygen-deficient derivatives is crucial. Here, using electron scattering measurements from nanoscale volumes in a transmission electron microscope (TEM), we report how oxygen content affects short-range order in amorphous TaOx thin films, where 1.34 ≤ x ≤ 2.50. By extracting the bond lengths, we observe that the dominant type of Ta–Ta distances change with decreasing oxygen content from next-nearest-neighbor, ∼3.8 Å, to nearest-neighbor, ∼3 Å. We relate this decrease to the Ta–O polyhedral network within the film, namely decreasing oxygen content increases the presence of TaO5 at the expense of TaO6 polyhedra. The reduction in oxygen content is accompanied by a significant reduction of electrical resistivity of the films from over 4.3 × 103 to (4 ± 0.05)×10−3 Ω × cm. In particular, we observe a sharp percolative decrease in resistivity of three orders of magnitude, at x ∼ 1.9. Ta oxidation states, measured by x-ray photoelectron spectroscopy, suggest that the main polyhedral building block within the TaO2.5 film is TaO6, while in oxygen-deficient films, the relative fractions of TaO5 polyhedra and metallic Ta increase. At even lower oxygen content, x ∼ 1.34, TEM and x-ray diffraction detect crystallites of Ta with cubic and metastable tetragonal structures. We propose that TaO5 polyhedra and Ta crystallites increase conductivity due to direct bonding of Ta atoms, as manifested by nearest-neighbor Ta–Ta bond length, thus enabling conductive paths for charge transport.
Investigation of drag reduction mechanism for blunt bodies with plasma spikes
Authors: Zhang Weilin , Ding Baozheng , Shi Zhiwei , Shu Yanlin , Sun Fengtao
Published: August 2023

The two main problems in hypersonic vehicles are wave drag and aerodynamic heating. This work proposes a novel method for drag reduction by combining spikes with the plasma synthetic jet actuator (PSJA). Numerical simulations are performed to better understand the drag reduction mechanism with an incoming flow at Mach 6. The results suggest that the flow field is affected primarily by the diffracted wave and synthetic jet. The maximum drag reduction reaches 47.7% with the plasma spike compared with the opposing jet. A better drag reduction effect is achieved when increasing the energy density of the PSJA, while the propagation velocity of the diffracted wave remains constant. A wider and faster jet is obtained with a larger PSJA orifice diameter. However, the control time of the jet shortens. A mode conversion occurs when the orifice diameter is 1 mm. Furthermore, the maximum drag reduction rate increases from 37.6% to 49.0% when the length diameter ratio (L/D) increases from 0.5 to 1.5. The effect of spike length on drag reduction decreases gradually at greater lengths.
Development of the self-modulation instability of a relativistic proton bunch in plasma
Authors: Verra L. , Wyler S. , Nechaeva T. , Pucek J. , Bencini V. , Bergamaschi M. , Ranc L. , Zevi Della Porta G. , Gschwendtner E. , Muggli P. ,   AWAKE Collaboration, Agnello R. , Ahdida C. C. , Amoedo C. , Andrebe Y. , Apsimon O. , Apsimon R. , Arnesano J. M. , Blanchard P. , Burrows P. N. , Buttenschön B. , Caldwell A. , Chung M. , Cooke D. A. , Davut C. , Demeter G. , Dexter A. C. , Doebert S. , Elverson F. A. , Farmer J. , Fasoli A. , Fonseca R. , Furno I. , Gorn A. , Granados E. , Granetzny M. , Graubner T. , Grulke O. , Guran E. , Henderson J. , Kedves M. Á. , Kim S.-Y. , Kraus F. , Krupa M. , Lefevre T. , Liang L. , Liu S. , Lopes N. , Lotov K. , Calderon M. Martinez , Mazzoni S. , Moon K. , Morales Guzmán P. I. , Moreira M. , Pakuza C. , Pannell F. , Pardons A. , Pepitone K. , Poimendidou E. , Pukhov A. , Ramjiawan R. L. , Rey S. , Rossel R. , Saberi H. , Schmitz O. , Senes E. , Silva F. , Silva L. , Spear B. , Stollberg C. , Sublet A. , Swain C. , Topaloudis A. , Torrado N. , Tuev P. , Turner M. , Velotti F. , Verzilov V. , Vieira J. , Weidl M. , Welsch C. , Wendt M. , Wing M. , Wolfenden J. , Woolley B. , Xia G. , Yarygova V. , Zepp M.
Published: August 2023

Self-modulation is a beam–plasma instability that is useful to drive large-amplitude wakefields with bunches much longer than the plasma skin depth. We present experimental results showing that, when increasing the ratio between the initial transverse size of the bunch and the plasma skin depth, the instability occurs later along the bunch, or not at all, over a fixed plasma length because the amplitude of the initial wakefields decreases. We show cases for which self-modulation does not develop, and we introduce a simple model discussing the conditions for which it would not occur after any plasma length. Changing bunch size and plasma electron density also changes the growth rate of the instability. We discuss the impact of these results on the design of a particle accelerator based on the self-modulation instability seeded by a relativistic ionization front, such as the future upgrade of the Advanced WAKefield Experiment.
High resolution electronic spectroscopy of uranium mononitride, UN
Authors: Le Anh T. , Bai Xi-lin , Heaven Michael C. , Steimle Timothy C.
Published: August 2023

The isoelectronic molecules UN and UO+ are known to have Ω = 3.5 and Ω = 4.5 ground states, respectively (where Ω is the unsigned projection of the electronic angular momentum along the internuclear axis). A ligand field theory model has been proposed to account for the difference [Matthew and Morse, J. Chem. Phys. 138, 184303 (2013)]. The ground state of UO+ arises from the U3+(5f3(4I4.5))O2− configuration. Owing to the higher nominal charge of the N3− ligand, the U3+ ion in UN is stabilized by promoting one of the 5f electrons to the more polarizable 7s orbital, reducing the repulsive interaction with the ligand and rendering U3+(5f27s(4H3.5))N3− the lowest energy configuration. In the present work, we have advanced the characterization of the UN ground state through studies of two electronic transitions, [18.35]4.5-X(1)3.5 and [18.63]4.5-X(1)3.5, using sub-Doppler laser excitation techniques with fluorescence detection. Spectra were recorded under field-free conditions and in the presence of static electric or magnetic fields. The ground state electric dipole moment [μ = 4.30(2) D] and magnetic ge-factor [2.160(9)] were determined from these data. These values were both consistent with the 5f27s configurational assignment. Dispersed fluorescence measurements were used to determine vibrational constants for the ground and first electronically excited states. Electric dipole moments and magnetic ge-factors are also reported for the higher-energy electronically excited states.
Magnetic collimation system for improving ion trap loading efficiency
Authors: Telnov E. Yu , Borisyuk P. V. , Bukharskii N. D. , Korneev Ph. A. , Trichev K. K. , Cherepanov P. A.
Published: August 2023

This work considers a solenoid-based magnetic collimation system for improving the efficiency of ion trap loading with ions created by laser ablation. We discuss a physical model of ion beam collimation in such a system, provide qualitative analytical estimates of its collimation characteristics, develop a numerical model of ion collimation based on a test-particle approach, and describe a real experimental setup where the proposed approach is effectively employed to collimate 232Th3+ and 88Sr1+ ions. The experimental results are compared with the results of the performed numerical modeling. The observed inconsistencies between the two are discussed, and their possible explanations are suggested.
Non-Markov models of single-molecule dynamics from information-theoretical analysis of trajectories
Authors: Song Kevin , Park Raymond , Das Atanu , Makarov Dmitrii E. , Vouga Etienne
Published: August 2023

Whether single-molecule trajectories, observed experimentally or in molecular simulations, can be described using simple models such as biased diffusion is a subject of considerable debate. Memory effects and anomalous diffusion have been reported in a number of studies, but directly inferring such effects from trajectories, especially given limited temporal and/or spatial resolution, has been a challenge. Recently, we proposed that this can be achieved with information-theoretical analysis of trajectories, which is based on the general observation that non-Markov effects make trajectories more predictable and, thus, more “compressible” by lossless compression algorithms. Toy models where discrete molecular states evolve in time were shown to be amenable to such analysis, but its application to continuous trajectories presents a challenge: the trajectories need to be digitized first, and digitization itself introduces non-Markov effects that depend on the specifics of how trajectories are sampled. Here we develop a milestoning-based method for information-theoretical analysis of continuous trajectories and show its utility in application to Markov and non-Markov models and to trajectories obtained from molecular simulations.
The interfacial modes and modal causality in a dispersed bubbly turbulent flow
Authors: Liu Yanchao , Wang Wenkang , Yang Guang , Nemati Hassan , Chu Xu
Published: August 2023

While data-driven analysis has demonstrated significant success in single-phase flow systems, its application to multi-phase flows has been relatively limited with fewer examples. In this study, we present a modal analysis and modal causality analysis of dispersed bubbly turbulent flow, with the aim of providing new insights into the interfacial gas–liquid interaction. Our study employs an in-house coupled level-set volume-of-fluid solver, which is combined with a modified fast Fourier transforms algorithm to perform interface-resolved direct numerical simulations in a turbulent channel flow with 96 bubbles occupying 5.4% volume. In the downward flow orientation, we observe that bubbles are mainly clustered in the channel center, producing pseudo-turbulence with isotropic characteristics. We apply the proper orthogonal decomposition method to the phase-resolved, three-dimensional velocity field, radius of the bubble as well as the surface tension force in order to extract the dominant modes. Notably, our results reveal the presence of two energetic modes in both the gas and liquid phases, as well as the interface, namely, the vortex-ring mode and the quadrupolar mode. We further investigate the causal relationship across the gas–liquid interface using the modal information transfer entropy. Our findings demonstrate a strong causality between the gas phase and the surface tension, whereas the causality between the liquid phase and surface tension is comparatively weak due to the multi-scale characteristics of the turbulent fields. Overall, our novel approach to investigating the interfacial gas–liquid interaction in dispersed bubbly turbulent flow provides valuable insights that enhance physical understanding and could lead to improved flow control and efficiency in a range of industrial processes. The identification of previously unidentified energetic modes using the POD method has the potential to advance research in this field, with potential implications for future design of control strategies in complex systems.
Effect of the surface peak-valley features on droplet splash dynamics
Authors: Jiao Yunlong , Zhu Yongqing , Wang Zhaochang , Hu Xidong , Guo Yuhang , Ji Jiawei , Liu Kun
Published: August 2023

In this study, we fabricated two types of functional surfaces with the same roughness (Sa) but entirely opposite surface morphological features, which are defined as the positively skewed surface filled with protruding cylinder array (Ssk > 0) and the negatively skewed surface filled with circular pit array (Ssk < 0). The effect of surface morphology peak-valley features on droplet splash is analyzed, and the formation mechanism of the prompt splash and corona splash is also indicated based on the Kelvin–Helmholtz instability. Our results demonstrate that, under the same roughness conditions of Sa, the interaction between the liquid lamellae and the thin air layer is much stronger on the negatively skewed surface, which would inhibit droplet spreading and promote the generation of droplet splash. Increasing the depth of microstructures, resulting in more pronounced peak-valley features, has been found to facilitate both prompt and corona splash phenomena to some extent. Additionally, it is found that the ease of splash formation on each surface is related to the initial spreading speed variation, with the degree of reduction in the initial spreading speed indirectly reflecting the instability of the liquid lamellae. The findings from our study contribute to the development of advanced surface engineering strategies for controlling droplet splash and enhancing the performance of various industrial applications.
Nature’s search for a quiet place
Authors: Gabor Nathaniel M. , Kistner-Morris Jed , Stewart Benjamin W.
Published: August 2023

The predominance of green terrestrial plants stems from chlorophyll’s absorbance wavelengths. Those spectral selections ensure consistent energy harvesting and avoid photo-oxidative stress.
Evaluating an implementation of the Australian National Guidelines for the On-Screen Display of Discharge Summaries
Authors: Mahera Masarrat , Rodda Hamish , Monypenny Nick , Wembridge Paul
Published: August 2023

Objective The objective of this study was to evaluate changes in the inclusion of pertinent information on electronic discharge summaries (eDS) after implementation of a revised template and electronic medical record (EMR) workflow. Methods A retrospective medical record audit of eDS at three metropolitan hospitals was undertaken for adult inpatient encounters in June 2021 (pre-intervention, n = 100) and June 2022 (post-intervention, n = 100). The eDS were evaluated against 16 components listed in the Australian National Guidelines for the On-Screen Display of Discharge Summaries. Nine components were further broken down to between two and 11 sub-components. Sub-analysis compared a hospital with full EMR to pooled results from hospitals with hybrid EMRs. Components and sub-components were evaluated for inclusion only; accuracy or relevance of the information was not assessed. Results Inclusion of three out of 16 components (presentation details: 47% vs 62%, problems and diagnosis: 61% vs 86% and recipient details: 82% vs 93%) and eight out of 36 sub-components (discharge destination, principal diagnosis, history of presenting complaint, infection risk, pressure injury, screening and/or diagnosis of delirium and GP phone number and address) was higher in the post-intervention group (all P < 0.05). Reduced eDS information inclusion in the post-intervention group was observed for discharge date and falls risk only (both P < 0.05). Reporting of falls history decreased at the hospital with full EMR (71% vs 20% P < 0.001) but not at hospitals utilising hybrid EMRs (24% vs 30% P = 0.5). Conclusion The intervention was associated with improved inclusion of pertinent information as described in the Australian National Guidelines for the On-Screen Display of Discharge Summaries.
Natural selection has driven the recurrent loss of an immunity gene that protects
Drosophila
against a major natural parasite
Authors: Arunkumar Ramesh , Zhou Shuyu Olivia , Day Jonathan P. , Bakare Sherifat , Pitton Simone , Zhang Yexin , Hsing Chi-Yun , O’Boyle Sinead , Pascual-Gil Juan , Clark Belinda , Chandler Rachael J. , Leitão Alexandre B. , Jiggins Francis M.
Published: August 2023

Polymorphisms in immunity genes can have large effects on susceptibility to infection. To understand the origins of this variation, we have investigated the genetic basis of resistance to the parasitoid wasp
Leptopilina boulardi
in
Drosophila melanogaster.
We found that increased expression of the gene
lectin-24A
after infection by parasitic wasps was associated with a faster cellular immune response and greatly increased rates of killing the parasite.
lectin-24A
encodes a protein that is strongly up-regulated in the fat body after infection and localizes to the surface of the parasite egg. In certain susceptible lines, a deletion upstream of the
lectin-24A
has largely abolished expression. Other mutations predicted to abolish the function of this gene have arisen recurrently in this gene, with multiple loss-of-expression alleles and premature stop codons segregating in natural populations. The frequency of these alleles varies greatly geographically, and in some southern African populations, natural selection has driven them near to fixation. We conclude that natural selection has favored the repeated loss of an important component of the immune system, suggesting that in some populations, a pleiotropic cost to
lectin-24A
expression outweighs the benefits of resistance.
The genomic landscape of swine influenza A viruses in Southeast Asia
Authors: Zeller Michael A. , Ma Jordan , Wong Foong Ying , Tum Sothyra , Hidano Arata , Holt Hannah , Chhay Ty , Sorn San , Koeut Dina , Seng Bunnary , Chao Sovanncheypo , Ng Giselle G. K. , Yan Zhuang , Chou Monidarin , Rudge James W. , Smith Gavin J. D. , Su Yvonne C. F.
Published: August 2023

Swine are a primary source for the emergence of pandemic influenza A viruses. The intensification of swine production, along with global trade, has amplified the transmission and zoonotic risk of swine influenza A virus (swIAV). Effective surveillance is essential to uncover emerging virus strains; however gaps remain in our understanding of the swIAV genomic landscape in Southeast Asia. More than 4,000 nasal swabs were collected from pigs in Cambodia, yielding 72 IAV-positive samples by RT-qPCR and 45 genomic sequences. We unmasked the cocirculation of multiple lineages of genetically diverse swIAV of pandemic concern. Genomic analyses revealed a novel European avian-like H1N2 swIAV reassortant variant with North American triple reassortant internal genes, that emerged approximately seven years before its first detection in pigs in 2021. Using phylogeographic reconstruction, we identified south central China as the dominant source of swine viruses disseminated to other regions in China and Southeast Asia. We also identified nine distinct swIAV lineages in Cambodia, which diverged from their closest ancestors between two and 15 B.P., indicating significant undetected diversity in the region, including reverse zoonoses of human H1N1/2009 pandemic and H3N2 viruses. A similar period of cryptic circulation of swIAVs occurred in the decades before the H1N1/2009 pandemic. The hidden diversity of swIAV observed here further emphasizes the complex underlying evolutionary processes present in this region, reinforcing the importance of genomic surveillance at the human–swine interface for early warning of disease emergence to avoid future pandemics.
Folding stabilities of ribosome-bound nascent polypeptides probed by mass spectrometry
Authors: Tan Ruiyue , Hoare Margaret , Welle Kevin A. , Swovick Kyle , Hryhorenko Jennifer R. , Ghaemmaghami Sina
Published: August 2023

The folding of most proteins occurs during the course of their translation while their tRNA-bound C termini are embedded in the ribosome. How the close proximity of nascent proteins to the ribosome influences their folding thermodynamics remains poorly understood. Here, we have developed a mass spectrometry–based approach for determining the stabilities of nascent polypeptide chains using methionine oxidation as a folding probe. This approach enables quantitative measurement subglobal folding stabilities of ribosome nascent chains within complex protein mixtures and extracts. To validate the methodology, we analyzed the folding thermodynamics of three model proteins (dihydrofolate reductase, chemotaxis protein Y, and DNA polymerase IV) in soluble and ribosome-bound states. The data indicate that the ribosome can significantly alter the stability of nascent polypeptides. Ribosome-induced stability modulations were highly variable among different folding domains and were dependent on localized charge distributions within nascent polypeptides. The results implicated electrostatic interactions between the ribosome surface and nascent polypeptides as the cause of ribosome-induced stability modulations. The study establishes a robust proteomic methodology for analyzing localized stabilities within ribosome-bound nascent polypeptides and sheds light on how the ribosome influences the thermodynamics of protein folding.
Strengthening the argument for a large Greater India
Authors: Meng Jun , Gilder Stuart A. , Tan Xiaodong , Li Xin , Li Yalin , Luo Hui , Suzuki Noritoshi , Wang Zihao , Chi Yuchen , Zhang Chunyang , Wang Chengshan
Published: August 2023

The Sangdanlin section in southern Tibet represents a geologic Rosetta stone to constrain the initiation of the India–Asia collision from its sedimentary and paleomagnetic records. However, geoscientists have arrived at fundamentally divergent interpretations surrounding the age of the strata and its paleomagnetic record. Here, we report paleontologic, petrographic, and paleomagnetic data from the Sangdanlin section that recognize the sequence as a thrust complex containing interlaced Barremian–Albian (Early Cretaceous) and Paleocene strata, each separated by thrust faults. Recognizing two complexly interwoven formations of distinctly different ages contradicts a continuous stratigraphic superposition. Assigning an Early Cretaceous, instead of Paleocene, age to the units collected for paleomagnetic data revises paleogeographic models thereby supporting a large (2,000 to 3,000 km) extent of Greater India, with collision initiating at 55 ± 5 Ma in the western Himalayas. A contiguous plate in the Neotethys Ocean precludes that Asia’s southern margin was built through a succession of accreted terrains.
Analysis of the complex between MBD2 and the histone deacetylase core of NuRD reveals key interactions critical for gene silencing
Authors: Leighton Gage O. , Shang Shengzhe , Hageman Sean , Ginder Gordon D. , Williams David C.
Published: August 2023

The nucleosome remodeling and deacetylase (NuRD) complex modifies nucleosome positioning and chromatin compaction to regulate gene expression. The methyl-CpG-binding domain proteins 2 and 3 (MBD2 and MBD3) play a critical role in complex formation; however, the molecular details of how they interact with other NuRD components have yet to be fully elucidated. We previously showed that an intrinsically disordered region (IDR) of MBD2 is necessary and sufficient to bind to the histone deacetylase core of NuRD. Building on that work, we have measured the inherent structural propensity of the MBD2-IDR using solvent and site-specific paramagnetic relaxation enhancement measurements. We then used the AlphaFold2 machine learning software to generate a model of the complex between MBD2 and the histone deacetylase core of NuRD. This model is remarkably consistent with our previous studies, including the current paramagnetic relaxation enhancement data. The latter suggests that the free MBD2-IDR samples conformations similar to the bound structure. We tested this model of the complex extensively by mutating key contact residues and measuring binding using an intracellular bioluminescent resonance energy transfer assay. Furthermore, we identified protein contacts that, when mutated, disrupted gene silencing by NuRD in a cell model of fetal hemoglobin regulation. Hence, this work provides insights into the formation of NuRD and highlights critical binding pockets that may be targeted to block gene silencing for therapy. Importantly, we show that AlphaFold2 can generate a credible model of a large complex that involves an IDR that folds upon binding.
Atomic Valley Filter Effect Induced by an Individual Flower Defect in Graphene
Authors: Zhang Yu , Liu Rong , Zhou Lili , Zhang Can , Yang Guoyuan , Wang Yeliang , He Lin
Published: August 2023

Owing to the bipartite nature of honeycomb lattice, the electrons in graphene host valley degree of freedom, which gives rise to a rich set of unique physical phenomena including chiral tunneling, Klein paradox, and quantum Hall ferromagnetism. Atomic defects in graphene can efficiently break the local sublattice symmetry, and hence, have significant effects on the valley-based electronic behaviors. Here we demonstrate that an individual flower defect in graphene has the ability of valley filter at the atomic scale. With the combination of scanning tunneling microscopy and Landau level measurements, we observe two valley-polarized density-of-states peaks near the outside of the flower defects, implying the symmetry breaking of the K and K′ valleys in graphene. Moreover, the electrons in the K valley can highly penetrate inside the flower defects. In contrast, the electrons in the K′ valley cannot directly penetrate, instead, they should be assisted by the valley switch from the K′ to K. Our results demonstrate that an individual flower defect in graphene can be regarded as a nanoscale valley filter, providing insight into the practical valleytronics.
All-optical birth time measurement of circularly polarized attosecond pulses
Authors: Zeng Qi , Deng Yimin , Cao Wei , Lu Peixiang
Published: August 2023

The advancement of attosecond science has made circularly polarized attosecond pulses increasingly essential. Despite ongoing research on their generation, few studies have explored methods of characterizing these pulses. To address this issue, we propose an all-optical technique for measuring the birth time of circularly polarized attosecond pulses generated by crossing two counter-rotating circularly polarized pulses in a noncollinear geometry. By introducing a weak second-harmonic to alter the phase of the electron trajectories, the even and odd high harmonics (HHs) are separated spatially, allowing one to determine the birth time of the attosecond pulses from the modulation of the even harmonics as a function of delay between the perturbing and driving fields. The spatial isolation of the even harmonic allows extending the method to the characterization of isolated attosecond pulse, which is challenging for existing in-situ methods. It provides deeper insight into the control and generation of circularly polarized HHs in both time and space domains, which will benefit circular dichroism attosecond metrology.
Modeling on magnetization behavior of ferromagnetic material during cyclic deformation
Authors: Bai Jiawei , Jin Ke , Kou Yong
Published: August 2023

In this paper, a nonlinear magneto-mechanical coupling constitutive model is established to describe the magnetization behavior of ferromagnetic materials under cyclic elastoplastic deformation. The critical state is introduced into the hysteretic magneto-mechanical model. In the critical state, the magnetization rates of loading and unloading are different. A new nonlinear plastic effective magnetic field is proposed by considering the effect of pinning sites caused by cross slip dislocation to describe the magnetization behavior under asymmetric cyclic loading. The softening factor and activation condition of plastic modulus parameter are introduced based on the cyclic plastic constitutive model to describe the decrease of plastic modulus. A new magnetization model for ferromagnetic materials under cyclic plastic deformation is established by combining the magneto-mechanical coupling model with the cyclic plastic constitutive model. Compared with the experiments and existing models, it is shown that the proposed model can capture the deformation and magnetization behavior well under cyclic loading.
Tunable valley splitting in two-dimensional CrBr3/VSe2 van der Waals heterostructure under strains and electric fields
Authors: Liang Xuesong , Sun Jin , Yu Zhizhou
Published: August 2023

Valleytronics opens up fascinating opportunities for using the valley degree of freedom in information storage and quantum computation. Here, based on the first-principles calculations, we investigate the effects of biaxial strains and electric fields on the magnetic, electronic, and valleytronic properties of two-dimensional CrBr3/VSe2 van der Waals (vdW) heterostructure consisting of two ferromagnetic monolayers. An interlayer magnetic phase transition from parallel to antiparallel is found when a compressive strain exceeds

−
2
%

or a tensile strain exceeds 4% is applied, while the interlayer magnetic configuration remains parallel under perpendicular electric fields. The valley splitting in the conduction bands is significantly enhanced by a compressive strain or an electric field pointing from the VSe2 to the CrBr3 layer. Specifically, a large valley splitting about 30.8 meV is obtained in the system with antiparallel interlayer magnetic configurations under a compressive strain of

−
4
%

, which is more than three times that of pristine CrBr3/VSe2 heterostructure. Our findings provide new insights into the future valleytronic applications for two-dimensional magnetic vdW heterostructures.
Robust monocular visual inertial odometry in γ radioactive environments using edge-based point features
Authors: Wang Hai , Zhang Hua , Deng Hao , Fu Meiqi
Published: August 2023

In the γ radioactive environment, high-energy photons induce degradation of the image sensor, which effects feature detection and tracking in the Visual Inertial Odometry (VIO) algorithm and deteriorates its localization performance. To address this issue, in this work, we propose a monocular VIO method using edge-based point features. To mitigate the effects of radiation noise, firstly, in the image preprocessing module, the median filter is used for real-time image denoising. Secondly, in the data association module, both Shi-Tomasi and edge-based point features are detected. The edge-based point feature is the endpoint or corner point in the salient edge map, which is more robust to radiation noise. Then, the bi-directional motion parallaxes and the RANdom SAmple Consensus (RANSAC) method are exploited to reject outliers. Finally, the point features measurements and Inertial Measurement Unit (IMU) pre-integration measurements are added into a tightly-coupled sliding window optimization VIO framework for localization estimation. The proposed method is verified by synthetic and real γ radioactive environment datasets. The experimental results show that the proposed method achieves more accurate and robust localization than the state-of-the-art VIO approaches in the γ radioactive environments.
Photon motion and weak gravitational lensing in black-bounce spacetime*
Authors: Sarikulov Furkat , Atamurotov Farruh , Abdujabbarov Ahmadjon , Khamidov Vokhid
Published: August 2023

The effect of spacetime curvature on photon motion may offer an opportunity to propose new tests on gravity theories. In this study, we investigate and focus on the massless (photon) particle motion around black-bounce gravity. We analyze the horizon structure around a gravitational compact object described by black-bounce spacetime. The photon motion and the effect of gravitational weak lensing in vacuum and plasma are discussed, and the shadow radius of the compact object is also studied in black-bounce spacetime. Additionally, the magnification of the image is studied using the deflection angle of light rays.
Narrowband EUV Sc/Si Multilayer for the Solar Upper Transition Region Imager at 46.5 nm
Authors: Qi Runze , Wu Jiali , Yu Jun , He Chunling , Jiang Li , Yu Yue , Zhang Zhe , Huang Qiushi , Zhang Zhong , Wang Zhanshan
Published: August 2023

The transition region is the key region between the lower solar atmosphere and the corona, which has been limitedly understood by human beings. Therefore, the Solar Upper Transition Region Imager (SUTRI) was proposed by Chinese scientists and launched in 2022 July. Right now, the first imaging observation of the upper transition region around 46.5 nm has been carried out by SUTRI. To ensure the spectral and temporal resolution of the SUTRI telescope, we have developed a narrowband Sc/Si multilayer. Based on the extreme ultraviolet (EUV) reflectivity measurements, the multilayer structure has been modified for ensuring the peak position of reflectivity was at 46.5 nm. Finally, the narrowband Sc/Si multilayer was successfully deposited on the hyperboloid primary mirror and secondary mirrors. The deviation of multilayer thickness uniformity was below than 1%, and the average EUV reflectivity at 46.1 nm was 27.8% with a near-normal incident angle of 5°. The calculated bandwidth of the reflectivity curve after primary and secondary mirrors was 2.82 nm, which could ensure the requirements of spectral resolution and reflectivity of SUTRI telescope to achieve its scientific goals.
3DT-CM: A Low-complexity Cross-matching Algorithm for Large Astronomical Catalogues Using 3d-tree Approach
Authors: Mu Yifei , Yu Ce , Sun Chao , Li Kun , Zhang Yajie , Wei Jizeng , Xiao Jian , Wang Jie
Published: August 2023

Location-based cross-matching is a preprocessing step in astronomy that aims to identify records belonging to the same celestial body based on the angular distance formula. The traditional approach involves comparing each record in one catalog with every record in the other catalog, resulting in a one-to-one comparison with high computational complexity. To reduce the computational time, index partitioning methods are used to divide the sky into regions and perform local cross-matching. In addition, cross-matching algorithms have been adopted on high-performance architectures to improve their efficiency. But the index partitioning methods and computation architectures only increase the degree of parallelism, and cannot decrease the complexity of pairwise-based cross-matching algorithm itself. A better algorithm is needed to further improve the performance of cross-matching algorithm. In this paper, we propose a 3d-tree-based cross-matching algorithm that converts the angular distance formula into an equivalent 3d Euclidean distance and uses 3d-tree method to reduce the overall computational complexity and to avoid boundary issues. Furthermore, we demonstrate the superiority of the 3d-tree approach over the 2d-tree method and implement it using a multi-threading technique during both the construction and querying phases. We have experimentally evaluated the proposed 3d-tree cross-matching algorithm using publicly available catalog data. The results show that our algorithm applied on two 32-core CPUs achieves equivalent performance than previous experiments conducted on a six-node CPU-GPU cluster.