bluuebunny/crossref_metadata_2025 huggingface dataset:
Genes and sites under adaptation at the phylogenetic scale also exhibit adaptation at the population-genetic scale
Authors: Latrille Thibault , Rodrigue Nicolas , Lartillot Nicolas
Published: March 2023

Adaptation in protein-coding sequences can be detected from multiple sequence alignments across species or alternatively by leveraging polymorphism data within a population. Across species, quantification of the adaptive rate relies on phylogenetic codon models, classically formulated in terms of the ratio of nonsynonymous over synonymous substitution rates. Evidence of an accelerated nonsynonymous substitution rate is considered a signature of pervasive adaptation. However, because of the background of purifying selection, these models are potentially limited in their sensitivity. Recent developments have led to more sophisticated mutation–selection codon models aimed at making a more detailed quantitative assessment of the interplay between mutation, purifying, and positive selection. In this study, we conducted a large-scale exome-wide analysis of placental mammals with mutation–selection models, assessing their performance at detecting proteins and sites under adaptation. Importantly, mutation–selection codon models are based on a population-genetic formalism and thus are directly comparable to the McDonald and Kreitman test at the population level to quantify adaptation. Taking advantage of this relationship between phylogenetic and population genetics analyses, we integrated divergence and polymorphism data across the entire exome for 29 populations across 7 genera and showed that proteins and sites detected to be under adaptation at the phylogenetic scale are also under adaptation at the population-genetic scale. Altogether, our exome-wide analysis shows that phylogenetic mutation–selection codon models and the population-genetic test of adaptation can be reconciled and are congruent, paving the way for integrative models and analyses across individuals and populations.
Mechanistic analysis of a novel membrane-interacting variable loop in the pleckstrin-homology domain critical for dynamin function
Authors: Khurana Himani , Baratam Krishnakanth , Bhattacharyya Soumya , Srivastava Anand , Pucadyil Thomas J.
Published: March 2023

Classical dynamins are best understood for their ability to generate vesicles by membrane fission. During clathrin-mediated endocytosis (CME), dynamin is recruited to the membrane through multivalent protein and lipid interactions between its proline-rich domain (PRD) with SRC Homology 3 (SH3) domains in endocytic proteins and its pleckstrin-homology domain (PHD) with membrane lipids. Variable loops (VL) in the PHD bind lipids and partially insert into the membrane thereby anchoring the PHD to the membrane. Recent molecular dynamics (MD) simulations reveal a novel VL4 that interacts with the membrane. Importantly, a missense mutation that reduces VL4 hydrophobicity is linked to an autosomal dominant form of Charcot-Marie-Tooth (CMT) neuropathy. We analyzed the orientation and function of the VL4 to mechanistically link data from simulations with the CMT neuropathy. Structural modeling of PHDs in the cryo-electron microscopy (cryo-EM) cryoEM map of the membrane-bound dynamin polymer confirms VL4 as a membrane-interacting loop. In assays that rely solely on lipid-based membrane recruitment, VL4 mutants with reduced hydrophobicity showed an acute membrane curvature-dependent binding and a catalytic defect in fission. Remarkably, in assays that mimic a physiological multivalent lipid- and protein-based recruitment, VL4 mutants were completely defective in fission across a range of membrane curvatures. Importantly, expression of these mutants in cells inhibited CME, consistent with the autosomal dominant phenotype associated with the CMT neuropathy. Together, our results emphasize the significance of finely tuned lipid and protein interactions for efficient dynamin function.
Shear rate sensitizes bacterial pathogens to H
2
O
2
stress
Authors: Padron Gilberto C. , Shuppara Alexander M. , Sharma Anuradha , Koch Matthias D. , Palalay Jessica-Jae S. , Radin Jana N. , Kehl-Fie Thomas E. , Imlay James A. , Sanfilippo Joseph E.
Published: March 2023

Cells regularly experience fluid flow in natural systems. However, most experimental systems rely on batch cell culture and fail to consider the effect of flow-driven dynamics on cell physiology. Using microfluidics and single-cell imaging, we discover that the interplay of physical shear rate (a measure of fluid flow) and chemical stress trigger a transcriptional response in the human pathogen
Pseudomonas aeruginosa
. In batch cell culture, cells protect themselves by quickly scavenging the ubiquitous chemical stressor hydrogen peroxide (H
2
O
2
) from the media. In microfluidic conditions, we observe that cell scavenging generates spatial gradients of H
2
O
2
. High shear rates replenish H
2
O
2
, abolish gradients, and generate a stress response. Combining mathematical simulations and biophysical experiments, we find that flow triggers an effect like “wind-chill” that sensitizes cells to H
2
O
2
concentrations 100 to 1,000 times lower than traditionally studied in batch cell culture. Surprisingly, the shear rate and H
2
O
2
concentration required to generate a transcriptional response closely match their respective values in the human bloodstream. Thus, our results explain a long-standing discrepancy between H
2
O
2
levels in experimental and host environments. Finally, we demonstrate that the shear rate and H
2
O
2
concentration found in the human bloodstream trigger gene expression in the blood-relevant human pathogen
Staphylococcus aureus
, suggesting that flow sensitizes bacteria to chemical stress in natural environments.
Bivalent molecular mimicry by ADP protects metal redox state and promotes coenzyme B
12
repair
Authors: Gouda Harsha , Mascarenhas Romila , Ruetz Markus , Yaw Madeline , Banerjee Ruma
Published: March 2023

Control over transition metal redox state is essential for metalloprotein function and can be achieved via coordination chemistry and/or sequestration from bulk solvent. Human methylmalonyl-Coenzyme A (CoA) mutase (MCM) catalyzes the isomerization of methylmalonyl-CoA to succinyl-CoA using 5′-deoxyadenosylcobalamin (AdoCbl) as a metallocofactor. During catalysis, the occasional escape of the 5′-deoxyadenosine (dAdo) moiety leaves the cob(II)alamin intermediate stranded and prone to hyperoxidation to hydroxocobalamin, which is recalcitrant to repair. In this study, we have identified the use of bivalent molecular mimicry by ADP, coopting the 5′-deoxyadenosine and diphosphate moieties in the cofactor and substrate, respectively, to protect against cob(II)alamin overoxidation on MCM. Crystallographic and electron paramagnetic resonance (EPR) data reveal that ADP exerts control over the metal oxidation state by inducing a conformational change that seals off solvent access, rather than by switching five-coordinate cob(II)alamin to the more air stable four-coordinate state. Subsequent binding of methylmalonyl-CoA (or CoA) promotes cob(II)alamin off-loading from MCM to adenosyltransferase for repair. This study identifies an unconventional strategy for controlling metal redox state by an abundant metabolite to plug active site access, which is key to preserving and recycling a rare, but essential, metal cofactor.
Structural modification of TA2/Q355B composite interface and study of TiC stability mechanism
Authors: Lei Xiaoling , Ding Wenhong , Hu Ying , Wu Mengxian , Hou Huadong
Published: March 2023

Constructing different titanium/steel composite interface structures and stabilising the TiC layer at 950°C through structural modification, the coexistence of multiple brittle phases at the composite interface was reduced and discussed the formation mechanism. Through structure modulation, the organisation of the bonding interface near the Ti side transformed into α-Ti, and the bond strength significantly increased to 290 MPa. Break through the rolling temperature should be limited to below 850°C, and the rolling temperature increases to 950°C. The bonding interface is transformed from discontinuous TiC and aggregated Fe2Ti particles to a uniform and continuous TiC layer at 850 and 900°C. Achieving a regulated TiC layer thickness of 180–190 nm inhibited Fe2Ti and FeTi production.
Unequal-mass boson-star binaries: initial data and merger dynamics
Authors: Evstafyeva Tamara , Sperhake Ulrich , Helfer Thomas , Croft Robin , Radia Miren , Ge Bo-Xuan , Lim Eugene A
Published: March 2023

We present a generalisation of the curative initial data construction derived for equal-mass compact binaries in Helferet al(2019Phys. Rev.D99044046; 2022Class. Quantum Grav.39074001) to arbitrary mass ratios. We demonstrate how these improved initial data avoid substantial spurious artifacts in the collision dynamics of unequal-mass boson-star binaries in the same way as has previously been achieved with the simpler method restricted to the equal-mass case. We employ the improved initial data to explore in detail the impact of phase offsets in the coalescence of equal- and unequal-mass boson star binaries.
Energy dependence of the Rb 52S1/2–52P1/2 noble-gas collision shift
Authors: Kettering Hunter , Camparo James
Published: March 2023

For more than a century the study of optical-resonance collision shifts in thermal atomic vapors has provided a window into atom/atom and atom/molecule interactions at low energies (i.e. ∼30 meV). Overall, the agreement between theory and experiment has been good, suggesting that an understanding of these interactions at low energies is well in hand. Here, we present evidence that this is not the case. Using an isoclinic-point method we measure the energy dependence of the Rb D1 collision shift in the noble gases (NGs): He, Ne, Ar, Kr and Xe. While agreement between theory and experiment is quite good for the heavy NGs, it is quite poor for the lighter ones: He and Ne. In the case of Rb/He, not only are the theoretical values in gross disagreement with one another, but they are also in significant disagreement with experiment.
A methodology to generate crystal-based molecular structures for atomistic simulations
Authors: Negre Christian F A , Alvarado Andrew , Singh Himanshu , Finkelstein Joshua , Martinez Enrique , Perriot Romain
Published: March 2023

We propose a systematic method to construct crystal-based molecular structures often needed as input for computational chemistry studies. These structures include crystal ‘slabs’ with periodic boundary conditions (PBCs) and non-periodic solids such as Wulff structures. We also introduce a method to build crystal slabs with orthogonal PBC vectors. These methods are integrated into our code, Los Alamos Crystal Cut (LCC), which is open source and thus fully available to the community. Examples showing the use of these methods are given throughout the manuscript.
Ferromagnetic resonance excited by interfacial microwave electric field: the role of current-induced torques
Authors: Deka Angshuman , Rana Bivas , Otani YoshiChika , Fukuma Yasuhiro
Published: March 2023

Excitation of magnetization dynamics in magnetic materials, especially in ultrathin ferromagnetic films, is of utmost importance for developing various ultrafast spintronics devices. Recently, the excitation of magnetization dynamics, i.e. ferromagnetic resonance (FMR) via electric field-induced modulation of interfacial magnetic anisotropies, has received particular attention due to several advantages, including lower power consumption. However, several additional torques generated by unavoidable microwave current induced because of the capacitive nature of the junctions may also contribute to the excitation of FMR apart from electric field-induced torques. Here, we study the FMR signals excited by applying microwave signal across the metal-oxide junction in CoFeB/MgO heterostructures with Pt and Ta buffer layers. Analysis of the resonance line shape and angular dependent behavior of resonance amplitude revealed that apart from voltage-controlled in-plane magnetic anisotropy (VC-IMA) torque a significant contribution can also arises from spin-torques and Oersted field torques originating from the flow of microwave current through metal-oxide junction. Surprisingly, the overall contribution from spin-torques and Oersted field torques are comparable to the VC-IMA torque contribution, even for a device with negligible defects. This study will be beneficial for designing future electric field-controlled spintronics devices.
A reduced self-calibrating method for rotary table error motions
Authors: Keller F , Stein M
Published: March 2023

A novel method for the determination of rotary table errors with six degrees of freedom on coordinate measuring machines and machine tools is introduced. The method is based on the measurement of an uncalibrated circular ball plate in different rotational positions on the rotary table, which is also referred to as the three-rosette method. The novel procedure allows the number of measurement positions to be reduced significantly compared to the complete three-rosette method, while the measurement uncertainty still remains sufficiently small. The method relies on error separation and is self-calibrating, which means that no external reference is required. The sophisticated design of a new ball plate allows rotary table errors to be determined in angular steps of only 5∘.
Heterogeneous sensing for target tracking: architecture, techniques, applications and challenges
Authors: Li Zhize , Liu Jun , Chen Kezhou , Gao Xiang , Tang Chenshuo , Xie Chao , Lu Xu
Published: March 2023

Target-tracking applications are promising and possess great theoretical and practical significance, though the research faces great challenges. With the development of multi-modal depth-sensing technology, a large number of scholars have proposed various target-tracking methods based on heterogeneous sensing and demonstrated great results. This review provides an overview of the techniques involved in target tracking in the different layers of the network as well as a comprehensive analysis of the research progress in heterogeneous sensing techniques in each layer. First, this review introduces the single sensing scheme and heterogeneous sensing scheme in the physical layer. Second, we present the heterogeneous communication technologies and heterogeneous optimization methods for communication protocols in the network layer. Third, we combine several typical heterogeneous-sensor target-tracking applications and analyze the applications of cloud computing, edge computing, big data and blockchain technologies. Finally, we discuss the challenges and future direction of heterogeneous-sensor target-tracking methods.
A compact Scheimpflug lidar imaging instrument for industrial diagnostics of flames
Authors: Dominguez Armand , Borggren Jesper , Xu Can , Otxoterena Paul , Försth Michael , Leffler Tomas , Bood Joakim
Published: March 2023

Scheimpflug lidar is a compact alternative to traditional lidar setups. With Scheimpflug lidar it is possible to make continuous range-resolved measurements. In this study we investigate the feasibility of a Scheimpflug lidar instrument for remote sensing in pool flames, which are characterized by strong particle scattering, large temperature gradients, and substantial fluctuations in particle distribution due to turbulence. An extinction coefficient can be extracted using the information about the transmitted laser power and the spatial extent of the flame. The transmitted laser power is manifested by the intensity of the ‘echo’ from a hard-target termination of the beam located behind the flame, while the information of the spatial extent of the flame along the laser beam is provided by the range-resolved scattering signal. Measurements were performed in heptane and diesel flames, respectively.
Development of hypothetico-deductive skills in an ISLE-based lab taught by novice instructors
Authors: Buggé Danielle , Rutberg Joshua , Ahmed Sheehan H , Zisk Robert , Jammula Diane
Published: March 2023

The Investigative Science Learning Environment (ISLE) approach to learning and teaching holds as one of its core tenets that students should learn physics by engaging in the same processes through which physicists develop new knowledge. One key skill necessary for this is hypothetico-deductive reasoning. In this study, we explored how the experience and familiarity of a lab instructor with the ISLE approach impacted students’ development of key scientific abilities related to making and testing hypotheses.
Reduced ITO for transparent superconducting electronics
Authors: Batson Emma , Colangelo Marco , Simonaitis John , Gebremeskel Eyosias , Medeiros Owen , Saravanapavanantham Mayuran , Bulovic Vladimir , Keathley P Donald , Berggren Karl K
Published: March 2023

Absorption of light in superconducting electronics is a major limitation on the quality of circuit architectures that integrate optical components with superconducting components. A 10 nm thick film of a typical superconducting material like niobium can absorb over half of any incident optical radiation. Instead, we propose using superconductors that are transparent to the wavelengths used elsewhere in the system. In this paper, we investigated reduced indium tin oxide (ITO) as a potential transparent superconductor for electronics. We fabricated and characterized superconducting wires of reduced ITO. We also showed that a

10

n
m

thick film of this material would only absorb about 1%–20% of light between 500 and 1700 nm.
Numerical simulations of electromagnetic behavior in CORC cable based on a modified

H−ϕ

formulation
Authors: Shan Shouhong , Wang Sijian , Yong Huadong , Zhou Youhe
Published: March 2023

Alternating current (AC) losses have an important effect on the stable operation of high-temperature superconductors (HTSs). Researchers have proposed many formulations to estimate AC losses based on finite element methods, such as

T

−

A

formulation,

H

formulation and

H

−
ϕ

formulation. In this paper, in order to simulate complicated multi-layer conductor on round core (CORC) cable with transport current, a modified

H

−
ϕ

formulation is proposed to calculate AC losses in complicated HTS structures. The formulation, which is easy to implement and has fast computation speed, is verified by comparing the calculation results with the existing formulations and experiments. The electromagnetic behavior of CORC cables and a helical coil wound by a three-layer CORC cable is investigated with a modified

H

−
ϕ

formulation. The numerical results show the non-uniformity of the losses and currents in the different layers of the CORC cable. Furthermore, the effects of the external magnetic field on the distribution of the transport current are also discussed.
Probing the percolation in the quantum anomalous Hall insulator
Authors: He Mengyun , Huang Yu , Sun Huimin , Fu Yu , Zhang Peng , Wang Kang L , He Qing Lin
Published: March 2023

The percolation plays an essential role in the physics of plateau transition, localization, and breakdown in quantum Hall (QH) systems. In practice, it always exists probably due to sample imperfections and has to be addressed before realizing the full potentials of topological electronics and qubits. Here, we investigate the cause, distribution, and number of the percolation in a quantum anomalous Hall (QAH) insulator of an anti-Hall bar geometry with two perimeters, which allows for probing both the inter- and intra-perimeter percolations by injecting currents into either or both perimeters. We discover the dual-QAH effect with opposite chiralities from these two perimeters, which exhibits linear modulations by the currents applied to both perimeters. By solving the formulation of such modulations with the Landauer–Büttiker formalism, the distribution and number of the inter-perimeter percolative channels could be identified. Strikingly, a dissipative constituent is detected in the transport of the QAH state, as revealed by the linear scalings in longitudinal conductivities versus the sum of currents injected to both perimeters, similar to that in the trivial-insulating state. Such a behavior unveils the quasi-2D nature of the intra-perimeter percolation, which superimposes onto and perturbs the dissipationless chiral edge transport. The formation of percolations is ascribed to the joint effect of the electric field, finite conductivity, and sample imperfections.
A DFT study of structural and electronic properties of some B12-based compounds under hydrostatic pressure
Authors: Özcan Merve , Cabuk Suleyman
Published: March 2023

Using both standard DFT and GW approaches provided by VASP, we calculated in detail the structural properties and electronic band structures of α-B12 and some B12-based compounds in the rhombohedral structure. In addition, the changes in all physical properties calculated under hydrostatic pressure in the range of 0–350 GPa were investigated using the standard DFT method. It was observed that the lattice parameter and bond length values of α-B12 and some B12-based compounds examined in the pressure range of 0–350 GPa decreased, while the rhombohedral angle values of the compounds except α-B12 increased. In the results obtained from the electronic characterization at ambient pressure, it was seen that the B13C2 and B13N2 compounds showed metallic properties, while the other compounds showed semiconductor properties. The variation of the indirect and direct band gaps of the compounds with pressure was investigated. While the electronic band gap of B12O2 increases with increasing pressure, the electronic band gap of other compounds with semiconductor properties tends to decrease with pressure. All computation results were compared with available other theoretical and experimental results in the literature.
The evolution of the out-of-phase dipole beams in the repulsive defect photonic moiré lattice with saturable self-focusing nonlinearity media
Authors: Lu Weiguang , Qin Yali , Zhou Shu , Ren Hongliang
Published: March 2023

We demonstrate in a numerical manner the intriguing transmission of the out-of-phase (OOP) dipole beams in the repulsive defect photonic moiré lattice with rotation angle

θ
=
arctan

(

3
/
4

)

and defect depth

ε
=
−
0.5

under saturable self-focusing nonlinearity. Photonic moiré lattices, that are created by two mutually rotated square patterns with a relative rotation angle

θ

. We introduce a single-site repulsive defect in periodic photonic moiré lattices, and excite this site with the OOP dipole beams. We reveal that the OOP dipole beams undergoes two evolution stages during propagation, for the first time to our knowledge. It is shown that the OOP dipole beams maintain stable propagation over a certain distance in the first stage, which depends on the defect depth. Then the energy of the OOP dipole beams flows between its two spots, exhibiting periodic-like oscillation in the second stage, along with discussion about the effect of defect depth on the stable propagation distance of the OOP dipole beams, one finds that the stable propagation distance decreases linearly with increasing defect depth

ε

. At the same time, we perform a polynomial fit between the oscillation period of the OOP dipole beams and the defect depth

ε

. These two fitting curves fully demonstrate that the repulsive defect can profoundly affect the propagation behavior of the OOP dipole beams. Our results may provide novel insights into the localization and oscillation of beams in defect structures.
Microneurography as a minimally invasive method to assess target engagement during neuromodulation
Authors: Verma Nishant , Knudsen Bruce , Gholston Aaron , Skubal Aaron , Blanz Stephan , Settell Megan , Frank Jennifer , Trevathan James , Ludwig Kip
Published: March 2023

Objective. Peripheral neural signals recorded during neuromodulation therapies provide insights into local neural target engagement and serve as a sensitive biomarker of physiological effect. Although these applications make peripheral recordings important for furthering neuromodulation therapies, the invasive nature of conventional nerve cuffs and longitudinal intrafascicular electrodes (LIFEs) limit their clinical utility. Furthermore, cuff electrodes typically record clear asynchronous neural activity in small animal models but not in large animal models. Microneurography, a minimally invasive technique, is already used routinely in humans to record asynchronous neural activity in the periphery. However, the relative performance of microneurography microelectrodes compared to cuff and LIFE electrodes in measuring neural signals relevant to neuromodulation therapies is not well understood. Approach. To address this gap, we recorded cervical vagus nerve electrically evoked compound action potentials (ECAPs) and spontaneous activity in a human-scaled large animal model—the pig. Additionally, we recorded sensory evoked activity and both invasively and non-invasively evoked CAPs from the great auricular nerve. In aggregate, this study assesses the potential of microneurography electrodes to measure neural activity during neuromodulation therapies with statistically powered and pre-registered outcomes (https://osf.io/y9k6j). Main results. The cuff recorded the largest ECAP signal (p < 0.01) and had the lowest noise floor amongst the evaluated electrodes. Despite the lower signal to noise ratio, microneurography electrodes were able to detect the threshold for neural activation with similar sensitivity to cuff and LIFE electrodes once a dose-response curve was constructed. Furthermore, the microneurography electrodes recorded distinct sensory evoked neural activity. Significance. The results show that microneurography electrodes can measure neural signals relevant to neuromodulation therapies. Microneurography could further neuromodulation therapies by providing a real-time biomarker to guide electrode placement and stimulation parameter selection to optimize local neural fiber engagement and study mechanisms of action.
Reflectance and fluorescence characteristics of PTFE coated with TPB at visible, UV, and VUV as a function of thickness
Authors: Haefner J. , Fahs A. , Ho J. , Stanford C. , Guenette R. , Adams C. , Almazán H. , Álvarez V. , Aparicio B. , Aranburu A.I. , Arazi L. , Arnquist I.J. , Auria-Luna F. , Ayet S. , Azevedo C.D.R. , Bailey K. , Ballester F. , Benlloch-Rodríguez J.M. , Borges F.I.G.M. , Bounasser S. , Byrnes N. , Cárcel S. , Carrión J.V. , Cebrián S. , Church E. , Conde C.A.N. , Contreras T. , Cossío F.P. , Denisenko A.A. , Dey E. , Díaz G. , Dickel T. , Escada J. , Esteve R. , Felkai R. , Fernandes L.M.P. , Ferrario P. , Ferreira A.L. , Foss F.W. , Freitas E.D.C. , Freixa Z. , Generowicz J. , Goldschmidt A. , Gómez-Cadenas J.J. , González R. , Grocott J. , Hafidi K. , Hauptman J. , Henriques C.A.O. , Hernando Morata J.A. , Herrero-Gómez P. , Herrero V. , Ho P. , Ifergan Y. , Jones B.J.P. , Kekic M. , Labarga L. , Larizgoitia L. , Lebrun P. , Lopez Gutierrez D. , López-March N. , Madigan R. , Mano R.D.P. , Martín-Albo J. , Martínez-Lema G. , Martínez-Vara M. , Marques A.P. , Meziani Z.E. , Miller R. , Mistry K. , Molina-Canteras J. , Monrabal F. , Monteiro C.M.B. , Mora F.J. , Muñoz Vidal J. , Navarro K. , Novella P. , Nuñez A. , Nygren D.R. , Oblak E. , Odriozola-Gimeno M. , Palmeiro B. , Para A. , Querol M. , Redwine A.B. , Renner J. , Rivilla I. , Rodríguez J. , Rogero C. , Rogers L. , Romeo B. , Romo-Luque C. , Santos F.P. , dos Santos J.M.F. , Simón A. , Sorel M. , Teixeira J.M.R. , Toledo J.F. , Torrent J. , Usón A. , Veloso J.F.C.A. , Vuong T.T. , Waiton J. , White J.T.
Published: March 2023

Polytetrafluoroethylene (PTFE) is an excellent diffuse reflector widely used in light collection systems for particle physics experiments. In noble element systems, it is often coated with tetraphenyl butadiene (TPB) to allow detection of vacuum ultraviolet scintillation light. In this work this dependence is investigated for PTFE coated with TPB in air for light of wavelengths of 200 nm, 260 nm, and 450 nm. The results show that TPB-coated PTFE has a reflectance of approximately 92% for thicknesses ranging from 5 mm to 10 mm at 450 nm, with negligible variation as a function of thickness within this range. A cross-check of these results using an argon chamber supports the conclusion that the change in thickness from 5 mm to 10 mm does not affect significantly the light response at 128 nm. Our results indicate that pieces of TPB-coated PTFE thinner than the typical 10 mm can be used in particle physics detectors without compromising the light signal.
Vectorized PoCA algorithm for faster image reconstruction for Muon Tomography
Authors: Sehgal Raman
Published: March 2023

Muon Tomography is a promising technique for detecting the presence of high atomic number (Z) material, using naturally available cosmic muons. The reconstruction algorithms used in Muon Tomography need to process a considerably high number of muon tracks to reconstruct the image of the object under test. This makes the image reconstruction process computation-intensive and time-consuming.
The algorithms to process the muon tracks are event-based algorithms, where all the events are independent and can be processed in any order. The traditional form of parallelism tries to distribute a small segment of work to multiple computing cores, but does not utilize the data level parallelism. The event-based algorithm can be processed on vector architecture and can provide a path to better utilize the data level parallelism. This approach provides another level of parallelism on standard computers without the need for specialized hardware. In this paper, we have tried to exploit the vector architecture provided by the current generation of CPUs to implement the vectorized version of Point of Closest Approach (PoCA) reconstruction algorithm for Muon Tomography. Results are presented using different vector instruction sets, for single-precision and double-precision calculations.
Diatom-inspired stiffness optimization for plates and cellular solids
Authors: Breish Firas , Hamm Christian , Kienzler Reinhold
Published: March 2023

Diatoms, a class of aquatic autotrophic microorganisms, are characterized by silicified exoskeletons with highly complex architectures. These morphologies have been shaped by the selection pressure that the organisms have been subjected to during their evolutionary history. Two properties which are highly likely to have contributed to the evolutionary success of current diatom species are lightweightness and structural strength. Thousands of diatom species are present in water bodies today, and although each has its unique shell architecture, a strategy that is common across species is the uneven and gradient solid material distribution across their shells. The aim of this study is to present and evaluate two novel structural optimization workflows inspired by material grading strategies in diatoms. The first workflow mimics the Auliscus intermidus diatoms’ surface thickening strategy and generates continuous sheet structures with optimal boundaries and local sheet thickness distributions when applied to plate models subjected to in-plane boundary conditions. The second workflow mimics the Triceratium sp. diatoms’ cellular solid grading strategy, and produces 3D cellular solids with optimal boundaries and local parameter distributions. Both methods are evaluated through sample load cases, and prove to be highly efficient in transforming optimization solutions with non-binary relative density distributions into highly performing 3D models.
Estimation of Traction Energy Consumption of Urban Service Buses in an Intermediate Andean City
Authors: Castillo-Calderón Jairo , Carrión Jaura Rubén , Sinche Diego Díaz , Panchana Bryan
Published: March 2023

The purpose of this work is to estimate the traction energy consumption of public transport buses in the urban sector of the city of Loja, Ecuador. Initially, with a data logger device, connected to the OBDII port, the speed and position variables of the transport units are acquired in real time, at a frequency of 1 Hz, during 25 round trips on 3 bus lines with the highest passenger flow; the effects of the slope profile are considered. To avoid information bias, 25 different HINO AK bus units, with different drivers, are monitored on full daily working days, where traffic is variable; different mass of the bus is defined in the three lines, based on historical data of the average number of passengers. Then, based on the fundamental theory of vehicle dynamics, the traction energy consumption of the buses is obtained in Matlab Simulink. For this purpose, a typical driving cycle (TDC) is de-fined, through a deterministic method, for both the outbound and the return trip of each line. The results highlight a higher traction energy consumption on line L8, with 50.36 kWh, where 52.43% is associated with slope resistance, 35.76% inertia resistance, 10.06% rolling resistance and 1.75% aerodynamic resistance. These findings represent a starting point for subsequent studies, in this Andean city, related to electromobility in mass transportation systems.
Energy Harvesting System with Solar Panels to Supply Low Power Electronic Devices
Authors: Cumbajín Myriam , Sánchez Patricio , Núñez Maritza , Gordón Carlos
Published: March 2023

Solar panels allow acquiring energy from the environment which can be stored for Energy Harvesting purposes. The objective of this work is to design, simulate and characterize different configurations in the harvesting stage, constituted by solar panels for energy harvesting systems of low consumption, identifying the most adequate arrangement to achieve the highest amount of energy together with the conversion stage. The methodology used has been design, simulation in Matlab-Simulink software and characterization with mini solar panels. The developed system consists of 3 stages which are: energy harvesting, DC-DC converter, and storage, focusing on the Energy Harvesting stage. The results obtained in simulation of 4.8V and 160 mA, and measurement of 4.60V and 134.5mA show that the mixed configuration is the one that presents better results in both voltage and current, concluding that the simulated and measured values are very close obtaining an error of 0.05% and 0.16% in voltage and current respectively and an output voltage of the converter of up to 26V. Finally, these results are very promising for Energy Harvesting applications.
Medium Range Ordering in liquid Al-based alloys: towards a machine learning approach of solidification
Authors: Jarry P , Jakse N
Published: March 2023

Ab initio molecular dynamic simulations of liquid Al93Cr7 and Al83Zn10Cr7 alloy have evidenced the presence of an icosahedral short range order (iSRO) which develops into icosahedral medium range order (iMRO) as the melt is undercooled. This atomic arrangement accounts for the presence of Dynamic Heterogeneities characterized by Al fast-dynamics regions and Cr-rich slow-dynamics regions. Characterisation of the medium range order was carried out by a direct connectivity approach. However, given the small size of the simulation (256 atoms), such characterisation remains partial. In order to better describe both iMRO formation and more dilute alloys closer to industrial compositions, a new modelling strategy has been initiated to allow in the long term for large-scale atomic-level simulations. Molecular Dynamics (MD) of million to billion atoms may indeed lead to meaningful results. Exploitation of such large amounts of MD-generated big data can be carried out by means of Machine Learning (ML) tools which provide relevant and powerful analysis methods. An unsupervised ML approach based on topological descriptors using persistent homology concepts is proposed to reveal the structural features of atomic arrangements without a priori knowledge on the studied system. This approach has been applied so far to pure Al melts. Both translational and orientational orderings are thus evidenced together with nucleation pathways, whose revealed features are beyond the hypotheses of the Classical Nucleation Theory.
Microstructural transition and grain selection across the wire/powder interface in hybrid additive manufacturing
Authors: Ushakov I , Aaddi A , Wursthorn J , Daloz D
Published: March 2023

Hybrid additive manufacturing is a promising process to produce Nickel-based alloy complex parts and builds, respecting high deposition rates during wire deposition and geometrical precision by powder deposition in laser DED process. This combination of processes should allow producing large parts with geometrically complex structures, not achievable by other technologies. Nevertheless, hybrid transitions of this type are not well described in the literature, in terms of microstructure establishment and grain selection across the interface, geometrical form of interface, and their potential influence on mechanical properties. Microstructure development across the interface wire/powder will be presented in this work with interface characterization by optical microscopy and EBSD. Grains selection across several powder layers in the hybrid wall, microstructure analysis will be presented for both wire and powder depositions.
Influence of nanoparticles on melting and solidification during a Directed Energy Deposition process analysed by simulation
Authors: Zheng G , Laqua R , Rey P , Salgueiro M , Gipperich M , Riepe J , Jakumeit J
Published: March 2023

Additive Manufacturing is a strategic tool for industrial applications. When large size structural parts are targeted, high deposition rates are important and Directed Energy Deposition (DED) is a preferred technique. A metal wire is melted by laser light and deposit on a substrate or already solidified material. Due to the small size of the melting zone, a detailed experimental analysis of the process is very difficult and simulation is an important tool to understand the manufacturing process and the influence of process and material parameter. Here the influence of the nanocomposite reinforcement on the deposition process are investigated by simulation single line tracks. A three-phase melting and solidification simulation methodology has been used to investigate the melting and solidification during DED printing of single line tracks of different wire materials. The approach uses the finite-volume method and arbitrary polyhedral control volumes to solve the governing equations. Heating of the wire by laser light is tackled using a volumetric heat source describing the specific absorption of the laser power by the metal wire. The influence of melting and solidification on the initially uniform nanocomposite distribution during the printing process is simulated using a Lagrangian approach. Firstly, simulations for steel ST 52-3 (1.0570) were performed for different process parameter settings and compared to experimental results of deposition width, height and form to validate the simulation approach. The method is then applied to Ti6Al4V wires with and without nanocomposites added to the wire material. Adding nanocomposites changes the melting and solidification behaviour of the wire materials. The influence of these changes of the material properties on the deposition process under different process conditions is analysed by simulation.
Rapid solidification during welding of duplex stainless steels – in situ measurement of the chemical concentration by Laser-Induced Breakdown Spectroscopy (LIBS)
Authors: Quackatz L , Griesche A , Kannengiesser T
Published: March 2023

Duplex stainless steels (DSS) are frequently used, especially in applications requiring high strength combined with high corrosion resistance in aggressive media. Examples include power plant components and maritime structures. During welding of these steels, local variations in chemical composition can occur. This results in ferritization of the material and negatively affects the mechanical properties of the components. In this work, tungsten inert gas (TIG) welding experiments were performed with DSS. Chemical composition analysis was realized in situ by using Laser Induced Breakdown Spectroscopy (LIBS). The aim of the work is to quantitatively measure the chemical composition in the weld seam of various DSS and to identify possible influences of welding parameters on the microstructure of the material. The chemical concentrations of the main alloying elements Cr, Ni, Mn on the surface of the sample during the welding process and the cooling process were measured. Mn and Ni are austenite stabilizers and their content increases during welding by using certain high alloyed filler material. Spectra were recorded every 1.3 s at a spacing of approximately 2 mm. During the cooling process the location of the measurement was not changed. The LIBS method is proofed to be suitable for the quantitative representation of the chemical compositions during the welding process.
Thermomechanical analysis of the solidification of fused cast alumina-zirconia-silica refractory blocks
Authors: Houdard T , Cabodi I , Vespa P , Pigeonneau F , Gandin C-A
Published: March 2023

Cooling history of fused cast Alumina-Zirconia-Silica (AZS) refractory blocks is recorded with thermocouples. Postmortem investigations are performed including hot tears. Discussion about solidification path is done with the purpose to better understand phenomena occurring during casting. Heat transfer simulations are compared with recorded temperature histories. Mechanical outputs from THERCAST® are analyzed, revealing the possibility to calibrate the risk of hot tears formation by considering a cumulated strain based criterion.
Modeling the Fluid Flow for Recent Solidification Experiments in Microgravity Electromagnetic Levitation
Authors: Bracker G P , Hyers R W
Published: March 2023

Microgravity electromagnetic levitation provides a unique processing environment for solidification experiments. The contactless processing allows for greater access to the undercooled region of the melt by isolating the sample from its environment and reducing the available heterogeneous nucleation to consistently achieve deep undercoolings. In the ISS-EML, a variety of solidification studies have investigated the relationship between nucleation temperature and flow conditions in metallic melts. These studies include recent work by Kelton et al. in which the coupled flux nucleation model was used to explore solidification in supercooled liquids using glass forming alloys: Vit106, Cu50Zr50, and Ti39.5Zr39.5Ni21. The relationship between fluid flow and nucleation is also a critical factor in recent experiments investigating dynamic nucleation. Unexplained solidification events occurred during both Spacelab Missions IML-2, MSL-1R, and ISS-EML. These experiments encompassed both steady and transient, accelerating flows. Repeatable, anomalous solidification was observed in both flow conditions. The conditions are consistent with dynamic nucleation, which relies heavily on the flow conditions within the sample for nucleation to occur. During these experiments, flow is not directly observable; however, magnetohydrodynamic models allow the flow to be calculated using the properties of the melt and the experimental conditions. These models provide key insights into the flow conditions and the impacts of flow on nucleation in these experiments.
High-precision solidification simulation by estimating heat transfer coefficients through data assimilation
Authors: Natsume Y , Oikawa T , Ohno M
Published: March 2023

Solidification analysis is important for accurately predicting casting processes. A high-precision casting simulation requires accurate data of the physical properties of materials and heat transfer parameters. In particular, the heat transfer coefficient is a major parameter influencing the casting simulation results. Because the heat transfer coefficient is not uniquely determined by the material, it is typically estimated by trial and error, which requires considerable time for accurate estimations. Therefore, we developed a method to quickly estimate the heat transfer coefficient in a casting process by combining data assimilation and solidification simulations. With this method, the time-dependent heat transfer coefficient can be estimated in an appropriate and easy manner. To reproduce the 3D temperature distribution in a casting with high accuracy, we developed a method to estimate multiple heat transfer coefficients simultaneously by combining data assimilation and 3D solidification simulation. Al–5 mass% Si alloy was cast into a sand mold with a casting size of 30 mm × 30 mm × 100 mm, and the temperature was measured at five points in the casting to obtain a cooling curve. Two cooling curves corresponding to locations of 5 mm from the casting wall were used to estimate the two heat transfer coefficients on the side and bottom surfaces, which were simultaneously estimated by data assimilation. The results confirmed that all the five cooling curves could be reproduced with a high accuracy and that high-precision casting simulation was possible.
The effect of Sr modification on the eutectic structure of AlSi7Mg alloys at different purity levels
Authors: Gursoy Ozen , Timelli Giulio
Published: March 2023

The effect of different Sr levels on the solidification path and the microstructure of the Al-Si eutectic in AlSi7Mg alloys at 3 different levels of purity (high purity, commercial purity, and secondary alloy) was investigated. Thermal analysis technique was performed to obtain the cooling curves and characteristic temperatures of the eutectic reactions. Microstructural investigations were carried out to study the variation of the eutectic structure due to Sr addition and alloy’s purity. The results indicate how the commercially pure alloy shows the highest nucleation and growth temperatures among the unmodified alloys, while the secondary alloy has the lowest ones. Sr addition decreases the characteristic eutectic temperatures. Even though the growth temperature is similar after Sr modification in the commercial and high purity alloys, this last shows a finest eutectic structure. Different levels of Sr are required to fully modify the eutectic of the AlSi7Mg alloy at different purity grade.
On the role of interfacial segregation on graphite shape in cast irons
Authors: Lacaze J
Published: March 2023

Understanding spheroidal graphite growth in cast irons is a long standing problem for which several mechanisms have been proposed. During the last decade, observations using transmission electron microscopy added new information about the stacking of graphite layers, leading eventually to propose other mechanisms than previously thought of such as repeated 2D-nucleation of new growth blocks and their lateral extension at the surface of the spheroids. Furthermore, it has been recently realized that elements known to strongly affect graphite shape are also those that are surface active. This is illustrated here in the case of antimony which is known to lead to spheroidal graphite degeneration when added at some tens of ppm. Using atomic resolution microscopy, segregation of antimony could be evidenced at the graphite/matrix interface of both spheroids and protuberances. This strongly suggests that accumulation of antimony repelled magnesium from the graphite surface until growth of spiky protuberances replaced spheroidal growth.