Rotational Orientation Research Articles

Texture evolution during multi-pass cold rolling and annealing of Ti-2Al-1.5Mn alloy

In this contribution, the underlying mechanisms of microstructure evolution and texture development during the cold rolling and annealing of a Ti-2Al-1.5Mn alloy were investigated and elucidated comprehensively. As a result of the heightened dislocation density and grain boundary, the hardness ascended as the successive reductions applied. However, the annealing treatment reinstated the structure through complete recrystallization. During cold working, the dominant basal <a> and prismatic <a> glide inclined the c-axis and <101̅0> axis towards the compressive direction and the rolling direction (RD), respectively. The primary rolled orientation consisted of <101̅0> fiber, the orientation of {1̅21̅3}<101̅0> with Euler angle {10°, 45°, 0°}and {1̅21̅7}<101̅0> with Euler angle {5°, 25°, 0 °} were predominant. Schmid Factor (SF) analysis and orientation rotation related to various textures demonstrated that basal <a> slipping resulted in a descendingϕangle in the Bunge system and <101̅0> pole parallel to the RD was the stable orientation. It was revealed that the recrystallized grains preponderantly exhibited textures inherited from the rolled matrix, but a new T-type texture also emerged. This implies that both the strain-induced boundary migration (SIBM) mechanism and selective grain growth, which nucleates at different sites, manipulate the annealing process. The study enhances our comprehension of texture evolution mechanisms involved in the plastic forming and helps ascertain the most effective operational parameters for producing high-performance titanium plates.

Twin domain and antiphase boundaries in microcrystals of Κ-phase Ga2O3

The structural properties of twin domain boundaries (TDB) and antiphase boundaries (APB) in individual thin, hexagonal prismatic microcrystals of κ-Ga2O3 grown on GaN/sapphire template with HVPE were investigated with electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM). The microcrystals were composed from the domains with three in-plane 120° rotational orientations. It was found that every individual twin domain contains a parallel array of APBs of a high density stretched in the [010] direction. APBs possess steps or interruption and can form double oppositely shifted spatially separated layers (APB dipoles). TDBs on majority of their length are incoherent being not strictly flat and serve as the border for the APBs interruptions. Panchromatic cathodoluminescence mapping of the microcrystals revealed that not all TDBs and APBs reduced its intensity. The interruptions and steps of APBs were proposed to be the main origin of the excess charged carrier recombination. A model of the atomic structure in the vicinity of the defects is proposed and the assumption about the formation of local high strain regions and dangling bonds was made.

A Tutorial on Retroreflectors and Arrays Used in Satellite and Lunar Laser Ranging

The present paper discusses the basics of retroreflector theory and the manner in which they are combined in arrays to service the laser tracking of artificial satellites and the Moon. We begin with a discussion of the relative advantages and disadvantages of solid versus hollow cube corners and the functional dependence of their optical cross-sections and far-field patterns on cube diameter. Because of velocity aberration effects, the design of an array for a particular space mission depends on many factors, including the desired range accuracy and the satellite’s orbital altitude, velocity, and pass geometry relative to the tracking station. This generally requires the individual retroreflectors in the array to be “spoiled” by perturbing one or more of the 90-degree angles that define a perfect cube corner, or alternatively, by adding a curved surface to a hollow cube. In order to obtain adequate return signal strengths from all points along the satellite path, the rotational orientation of the retroreflectors within the array may need to be varied or “clocked”. Possible approaches to developing millimeter-accuracy arrays with both large cross-sections and ultrashort satellite signatures are discussed, as are new designs proposed to replace aging reflectors on the Moon. Finally, we briefly discuss methods for laser ranging beyond the Moon.

Spatial visualization as the strongest spatial reasoning autistic student

Abstract spatial reasoning is the strongest reasoning of autistic students. In this study, we want to identify the spatial reasoning of autistic students based on the categories of spatial reasoning (spatial visualization, mental rotation, and spatial orientation) and level of reasoning (abstract and concrete). A total of 46 autistic students and 46 non-autistic students participated as subjects. All subjects were given 6 types of spatial reasoning tests which included all three categories and levels of spatial reasoning. The results that autistic students have an advantage in the abstract spatial visualization category while non-autistic students have an advantage in the concrete spatial visualization category. These results indicate specifically that abstract spatial visualization is the strongest spatial reasoning possessed by autistic students. Thus, this study provides a new picture of students' spatial reasoning ability in terms of the reasoning category and the level of reasoning.

Effects of mental rotation on map representation in orienteers-behavioral and fNIRS evidence.

Taking orienteering as an example, this study aimed to reveal the effects of mental rotation on orienteers' map representation and their brain processing characteristics. Functional near-infrared spectroscopic imaging (fNIRS) was used to explore the behavioral performance and cortical oxyhemoglobin concentration changes of map-represented cognitive processing in orienteering athletes under two task conditions: normal and rotational orientation. Compared to that in the normal orientation, athletes' task performance in the rotated orientation condition was significantly decreased, as evidenced by a decrease in correct rate and an increase in reaction time; in the normal orientation condition, blood oxygen activation in the dorsolateral prefrontal lobe was significantly greater than that in the ventral prefrontal lobe, which was significantly correlated with the correct rate. With rotating orientation, the brain oxygen average of each region of interest was enhanced, and the brain region specifically processed was the ventral prefrontal lobe, specifically correlating with the correct rate. Mental rotation constrains the map representation ability of athletes, and map representation in rotational orientation requires more functional brain activity for information processing. Ventral lateral prefrontal lobe activation plays an important role in the map representation task in rotational orientation.

Characterizing the origin band spectrum of isoquinoline with resonance enhanced multiphoton ionization and electronic structure calculations.

We report the experimental resonance enhanced multiphoton ionization spectrum of isoquinoline between 315 and 310nm, along with correlated electronic structure calculations on the ground and excited states of this species. This spectral region spans the origin transitions to a π-π* excited state, which previous work has suggested to be vibronically coupled with a lower lying singlet n-π* state. Our computational results corroborate previous density functional theory calculations that predict the vertical excitation energy for the n-π* state to be higher than the π-π* state; however, we find an increase in the C-N-C angle brings the n-π* state below the energy of the π-π* state. The calculations find two out-of-plane vibrational modes of the n-π* state, which may be brought into near resonance with the π-π* state as the C-N-C bond angle increases. Therefore, the C-N-C bond angle may be important in activating vibronic coupling between the states. We fit the experimental rotational contour with a genetic algorithm to determine the excited state rotational constants and orientation of the transition dipole moment. The fits show a mostly in-plane polarized transition, and the projection of the transition dipole moment in the a-b plane is about 84° away from the a axis. These results are consistent with the prediction of our electronic structure calculations for the transition dipole moment of the π-π* excited state.

Analysis of Child’s Spatial Ability

This study analyzed how the spatial ability of children in the first and second grades of elementary school appeared. The key components of spatial ability are mental rotation, spatial visualization, and spatial orientation, which serve as spatial ability. The research results are as follows. Children performed spatial orientation the best and had the most difficulty with mental rotation. And there was a significant difference in spatial ability by age, but there was no significant difference in gender and the interaction effect between age and gender. As a result of analysis by component, there was no significant difference in age and gender in mental rotation and spatial visualization, and there was no significant difference in the interaction between age and gender. Spatial orienting was found to have a significant difference in age, but there was no significant difference in gender, and there was no significant difference in the interaction between age and gender. The results of this study will be able to serve as basic data for interventions that can learn how to effectively learn spatial abilities and think by diagnosing children's spatial ability.

An investigation of Middle School Students Spatial Reasoning Skills

In recent years, there has been a growing interest in spatial reasoning as a component of mathematics education, with many countries incorporating it into their mathematics curriculum. The study of spatial reasoning in the learning areas of geometry presents an essential opportunity for improvement of students within the realm of mathematics education. The purpose of this survey research is to examine middle school students spatial reasoning skills. A study was conducted to analyze the spatial reasoning skills of 947 middle school students. The Spatial Reasoning Test was utilized to assess the sub-components of spatial visualization, spatial orientation, and mental rotation. Based on the results, there was no significant difference between male and female students in relation to their overall test scores. However, a statistically significant difference was observed when analyzing the scores of the sub-components and grade levels. Anticipated outcomes of the investigation are expected to provide support and guidance for the preparation of educational tasks and instruction aimed at enhancing students’ spatial reasoning abilities.

Exploring avibactam and relebactam inhibition of Klebsiella pneumoniae carbapenemase D179N variant: role of the Ω loop-held deacylation water.

Klebsiella pneumoniae carbapenemase-2 (KPC-2) presents a clinical threat as this β-lactamase confers resistance to carbapenems. Recent variants of KPC-2 in clinical isolates contribute to concerning resistance phenotypes. Klebsiella pneumoniae expressing KPC-2 D179Y acquired resistance to the ceftazidime/avibactam combination affecting both the β-lactam and the β-lactamase inhibitor yet has lowered minimum inhibitory concentrations for all other β-lactams tested. Furthermore, Klebsiella pneumoniae expressing the KPC-2 D179N variant also manifested resistance to ceftazidime/avibactam yet retained its ability to confer resistance to carbapenems although significantly reduced. This structural study focuses on the inhibition of KPC-2 D179N by avibactam and relebactam and expands our previous analysis that examined ceftazidime resistance conferred by D179N and D179Y variants. Crystal structures of KPC-2 D179N soaked with avibactam and co-crystallized with relebactam were determined. The complex with avibactam reveals avibactam making several hydrogen bonds, including with the deacylation water held in place by Ω loop. These results could explain why the KPC-2 D179Y variant, which has a disordered Ω loop, has a decreased affinity for avibactam. The relebactam KPC-2 D179N complex revealed a new orientation of the diazabicyclooctane (DBO) intermediate with the scaffold piperidine ring rotated ~150° from the standard DBO orientation. The density shows relebactam to be desulfated and present as an imine-hydrolysis intermediate not previously observed. The tetrahedral imine moiety of relebactam interacts with the deacylation water. The rotated relebactam orientation and deacylation water interaction could potentially contribute to KPC-mediated DBO fragmentation. These results elucidate important differences that could aid in the design of novel β-lactamase inhibitors.

Chern number transition of quantum anomalous hall phases in kagome TM3Te4 (TM = Ti, Cr) monolayers by manipulating magnetization orientation

The development of quantum anomalous hall (QAH) insulator with high transition temperature is the key to realize practical applications in future quantum technology and spintronics. Here, we predicted two stable two-dimensional kagome structures, Ti3Te4 and Cr3Te4, and found that both of them are intrinsic QAH insulators, using density functional theory calculations. In the absence of spin–orbit coupling (SOC), both systems display ferromagnetism (FM) Weyl semimetal states. Remarkably, Ti3Te4 monolayer is revealed to be a robust ferromagnetic half metal with high Curie temperature (TC) of 403 K. When the SOC effect occurs, it spontaneously creates QAH states with large nontrivial bandgap and chiral edge states. As a result, the Ti(Cr)3Te4 monolayer is changed to be QAH insulators with Chern number C = ±1 by rotation of magnetization orientation. In addition, the phase change from FM QAH insulator to antiferromagnetic insulator can be manipulated by applying external strains. Moreover, a high-Chern number phase (C = 2) arises by building Ti3Te4/MoS2/Ti3Te4 heterostructure. Meanwhile, the topological phase transition can be well recurred by using a spinless three-band tight-binding (TB) model. The findings present ways to realize potential QAH insulators with high transition temperatures.

Revealing the interface-mediated dislocation behavior and its role in delocalizing strain band in laminated aluminum

This study investigated the plastic deformation behavior of fine-/coarse-grained laminated aluminum (Al) via in-situ tensile test coupled with digital image correlation (DIC) and electron backscatter diffraction (EBSD), aiming to unveil the relation between local strain behavior and dislocation mechanisms. The local strain analysis found that strain localization bands generating in hard but brittle fine-grained layers are effectively impeded under the constraint of neighboring coarse-grained layers. With the aid of novel misorientation mapping method, the dislocation structures, distinguished from those in the coarse grain interior, were found to be predominant within the propagation path of localized strain band. These interface-mediated slip systems, which are responsible for suppressing the strain band propagation, were further analyzed by integrating the dislocation structures and local orientation rotations. The dominant role of such mutual interactions between strain delocalization and dislocation behaviors in improving the strength-ductility synergy was also discussed. These findings are important for understanding the deformation behaviors of heterogeneous multi-layered metals, and also provide guidance for designing high-performance layered metals by regulating local strain behavior and underlying dislocation mechanisms.

Statistics of tidal and deformation eigenvalue fields in the primordial Gaussian matter distribution: the two-dimensional case

ABSTRACT We study the statistical properties of the eigenvalues of the primordial tidal and deformation tensor for two-dimensional random Gaussian cosmic density fields. With the tidal and deformation tensors, Hessians of the gravitational and velocity potential, being Gaussian, the eigenvalue fields are distinctly non-Gaussian. We extend the Doroshkevich formula for the joined distribution of eigenvalues to two-dimensional fields and evaluate the two- and three-point correlation functions. In addition, we assess the number densities of singular points of the eigenvalue fields and find their corresponding two- and three-point correlation functions. The incentive for the present study is based on our interest in developing a fully analytical theory for the structure and dynamics of the cosmic web. The tidal forces and the resulting mass element deformation shape the prominent anisotropic wall-like and filamentary components of the cosmic web. Less well-known is that the web-like spatial pattern is already recognizable in the primordial tidal and deformation eigenvalue field. Against the full phase-space assessment of structure formation in the Universe, the caustic skeleton theory entails an analytical framework for the non-linear evolution of the cosmic web. It accomplishes this by describing the folding of the dark matter sheet and quantifying the emerging caustic singularities, which are fully specified by the spatial properties of the deformation eigenvalues and eigenvectors. Finally, the eigenvalues of the primordial tidal tensor are crucial in the generation of the angular momentum of galaxies. Understanding their spatial distribution is a critical element in predicting the resulting rotation amplitude and orientation.

Incoherent Energy Transfer between the Baseplate and FMO Protein Explored at Ideal Geometries.

The Förster resonance energy transfer (FRET) between the Fenna-Matthews-Olson (FMO) protein complex and the chlorosomal baseplate (CBP) is investigated by using an idealized model. This simplified model is based on crystal structure and molecular dynamics conformations. Some of the further input, such as the transition dipole moments, was extracted from earlier molecular-level simulations. The resulting model mimics the effects of the relative position between the CBP and the FMO complex on the corresponding FRET efficiency under ideal conditions, involving about 1.3 billion FRET calculations per investigated model. In this idealized model and employing some approximations, it is found that FRET efficiency is almost completely independent of the FMO trimer orientation (displacement, distance, and rotation), despite FMO and CBP being highly structured complexes. Even removing individual FMO BChl triples will only reduce the FRET efficiency by up to 8.6%. An FMO containing only the least efficient BChl triple will retain about 25% of the FRET efficiency of a full FMO complex. In addition to its proposed function as an energetic funnel, FMO is thus identified to act as a highly robust spatial funnel for CBP excitation harvesting, independent of the mutual CBP-FMO orientation.

Patient-specific commissural alignment for ACURATE neo2 implantation in degenerated surgical bioprostheses.

Valve-in-valve TAVI to treat failing surgical aortic valves (SAVs) is increasingly performed, and commissural alignment is a key technical aspect in such procedures. Surgeons optimize valve alignment, accounting for potential coronary eccentricity and achieving a patient-specific optimized commissural orientation, representing the ideal target for TAVI alignment. Therefore, here we present a dedicated stepwise valve-in-valve implantation technique using the ACURATE neo2. In a specific SAV postoverlap view, isolating one surgical post to the right of the screen representing the target for alignment, rotational orientation of the TAVI commissures, matching the SAV orientation, is achieved and verified before implantation. This technique has been tested in a patient-specific three-dimensionally-printed aortic root anatomy, attached to a pulsatile flow simulator, allowing for native-like simulation of coronary cannulations under fluoroscopy, and enabling detailed assessment with fluoroscopic as well as direct videographic visualization. Furthermore, the technique is exemplified by providing an educational clinical case example.

Distal Tibiofibular Malreduction in Ankle Fractures Received Fibula Plate and Syndesmotic Screw Fixation.

The aim of the study was to examine the effect of the position of the plate and syndesmotic screw on postoperative tibiofibular joint malreductions in cases where the syndesmotic screw is inserted through the hole of the anatomically locked lateral distal fibula plate. Thirty patients (13 female and 17 male patients) with postoperative computed tomographic scans were examined retrospectively. Patient information (eg, tibiofibular congruence measured from postoperative computed tomographic scans, the anterior and posterior tibiofibular distance at axial sections, the presence and orientation of fibular rotation, the presence of tibiofibular intraarticular piece, the angle between the syndesmotic screw and incisural line, the placement of the plate, and the localization of the screw on the fibula in axial images) was recorded. Those with fibular internal rotation had a lower syndesmotic screw-incisural line angle (SIA) (P = .001).There was a very strong negative significant correlation between the tibiofibular angle and SIA (rho, -0.780; P = .001). The median tibiofibular angle was found to be higher in cases with the fibula plate placed anteriorly (P = .009).The median SIA was found to be lower in cases with the fibula plate placed anteriorly (P = .004).The rate of placement of syndesmotic screw in the anterior third of the fibula was found to be high in cases with the fibula plate placed anteriorly (P = .049). In ankle fractures treated with insertion of a syndesmotic screw through the plate, the orientation of the syndesmotic screw in the axial plane and the position of the plate may be associated with the incidence of postoperative syndesmosis malreduction.

Impact of Bileaflet Mechanical Mitral Valve Orientation on Pannus Overgrowth.

Pannus overgrowth is a chronic inflammatory process that can cause valve dysfunction and threaten the durability of prosthetic valves. Bileaflet mechanical mitral valve can be implanted in either an anatomical (parallel to the anatomical axis) or nonanatomical (perpendicular or oblique to the anatomical axis) orientation. The effect of the rotational orientation of the bileaflet mechanical mitral valve on excessive pannus enlargement is unknown. The present study compared the effect of bileaflet mechanical mitral valve orientation on pannus overgrowth. The study included patients who underwent bileaflet mechanical mitral valve replacement for rheumatic mitral valve stenosis. The pannus formation was confirmed by reexamining all transesophageal echocardiography images in the picture archiving and communication systems between May 2017 and April 2021. The primary aim of this study was the development of pannus overgrowth. Patients were divided into 2 groups based on their implantation orientation of the bileaflet mechanical mitral valve. Pannus overgrowth was found in 26 patients (56.5%) in the anatomical orientation group and 71 patients (74.7%) in the nonanatomical orientation group (P = 0.03). Anatomical orientation reduced the development of pannus overgrowth (odds ratio [OR] = 0.39, P = 0.04), and double left heart valve replacement increased the development of pannus overgrowth (OR = 2.73, P = 0.04). Pannus overgrowth was less common in bileaflet mechanical mitral valves implanted in the anatomical orientation.

Dynamic modeling of Haidinger's brush phenomenon and analysis of the cornea effect based on the model

Starting from the dynamic feature of the vision process and taking into account the time constants of the polarization-dependent process of cones, this study proposed a physical model that can mathematically describe the transient nature of Haidinger’s brushes (HB). A saturated exponential growth function was proposed to describe the dynamic process, and the corresponding formulas were derived and discussed. The sensitivities of both static and rotating HB were considered in the model, and the visibility of HB was also investigated. Additionally, the impact of the cornea on the visions of HB was examined by using this model. Analytical results reveal that there exist two types of patterns in the rotating HB phenomenon. The visual perception of the rotating HB is related to the magnitude and interaction of these two patterns, as well as the corneal phase shift. The rotation orientation reversal at large corneal phase shifts observed by some researchers can also be explained by the model. The results are consistent with experimental observations and might help with the clinical diagnosis of macula disorders and corneal abnormalities.

Frustration-induced magnetic bimerons in transition metal halide CoX2 (X = Cl, Br) monolayers

With the field of two-dimensional (2D) magnetic materials expanding rapidly, noncollinear topological magnetic textures in 2D materials are attracting growing interest recently. As the in-plane counterpart of magnetic skyrmions, magnetic bimerons have the same topological advantages, but are rarely observed in experiments. Employing first-principles calculations and Monte Carlo simulations, we predict that the centrosymmetric transition metal halide CoX2 (X = Cl, Br) monolayers can be promising candidates for observing the frustration-induced bimerons. These bimerons crystallize into stable triangular lattice under an appropriate magnetic field. Compared to the skyrmions driven by the Dzyaloshinskii-Moriya interaction or the long-ranged magnetic dipole-dipole interactions, these frustration-induced bimerons have much smaller size and flexible tunability. Furthermore, the biaxial strain provides an effective method to tune the frustration and thereby to tune the bimeron lattice. In detail, for CoCl2 monolayer, tensile strain can be applied to generate bimeron lattice, further shrink bimeron size and increase the density of bimerons. For CoBr2 monolayer with inherent bimeron lattice state, a unique orientation rotation of bimeron lattice controlled by compressive strain is predicted.

Quantifying the Impacts of the Angle of Attack on the Morphology of Atmospheric von Kármán Vortex Streets

AbstractA mesoscale model is used to systematically investigate how the incoming flow incidence angle affects the development of atmospheric von Kármán vortex streets for non‐axisymmetric islands. The analysis is focused on an event observed on the leeward side of Guadalupe Island. By keeping the synoptic conditions the same, several simulations are performed for rotated orientations of the island topography, which correspond to a change in the angle of attack (AoA) relative to the upstream flow. The asymmetry of the vortex shedding and the role of the leading and trailing edge are in line with what was observed in laboratory von Kármán vortex streets past a flat plate. The eddies become larger with increasing AoA while the shedding frequency decreases, and the asymmetry between cyclonic and anticyclonic eddies weakens. Cyclonic vortices are more developed and stronger under typical conditions when they are shed from the trailing edge. We also demonstrate that the wake asymmetry is fundamentally between trailing‐edge and leading‐edge eddies rather than between cyclonic and anticyclonic eddies.

γ′-size effect on the deformation microstructure and texture in a Ni-based superalloy using in-situ neutron diffraction

The γ′-size effect on the evolution of microstructure and grain rotation during tensile deformation in a polycrystalline Ni-based superalloy was investigated by in-situ neutron diffraction technique. Diffraction profile analysis was employed to evaluate the dislocation density and deformed subgrain size distribution, revealing that alloys with fine and coarse γ′ possess dislocation shearing and Orowan dislocation bypassing, respectively. The high strain hardening in the coarse γ′ specimen is attributed to the more pronounced accelerated accumulation of dislocations compared to the fine γ′ specimen. Moreover, the specimen with coarse γ′ precipitate exhibits a lower orientation rotation rate, resulting in weaker <111> and <100> fiber texture components upon tensile straining. The use of neutron diffraction combined with electron microscopy provided multiscale insights into the deformation microstructure and changes in the lattice orientation.