Perpendicular Mode Research Articles

Atomic-Level Insights into the Adsorption of Methyl-Substituted Quinoxalinones on Fe(110): A Dispersion-Corrected DFT Analysis.

Corrosion of metallic equipment is a critical issue across various industries, necessitating the development of advanced protective strategies. This study utilized dispersion-corrected density functional theory (DFT) with Becke-Johnson D3(BJ) to examine the atomic-level adsorption of quinoxalinones on Fe(110) surfaces, focusing on optimizing substitution strategies to enhance corrosion inhibition. Three quinoxalinones, quinoxalin-2(1H)-one (QNO), 3-methylquinoxalin-2(1H)-one (QNOM), and 3,7-dimethylquinoxalin-2(1H)-one (QNO2M), were investigated in various configurations and protonation states. Protonated quinoxalinones demonstrated a stronger surface affinity, primarily interacting through oxygen atoms and conjugated systems, with greater energetic stability compared to neutral molecules, driven by enhanced electrostatic interactions and charge transfer mechanisms. The parallel adsorption configuration was more stable than the perpendicular mode, which in some adsorption systems did not form bonds with the iron surface. Notably, the presence of methyl substitutions did not significantly enhance adsorption strength; QNO exhibited higher energetic stability due to reduced steric interference, which maintained its planarity. Projected density of states (PDOS), electron density difference (EDD), and electron localization function (ELF) analyses confirmed the importance of charge transfer between quinoxalinone active sites and the 3d orbitals of iron in stabilizing the adsorption of molecules. These findings underscore the importance of judicious quinoxalinone functionalization to preserve their efficacy as corrosion inhibitors.

Controlled Growth of Single-Walled Carbon Nanotube Films by Iron-assisted Floating Solid Catalyst Chemical Vapor Deposition.

Single-walled carbon nanotube (SWNT) films, with exciting electronic properties are increasingly important for next-generation technologies. Here, an Iron-assisted floating solid catalyst chemical vapor deposition (IA-FSCCVD) method is developed for the controlled growth of high-quality and high-purity SWNT films. Titanium carbide nanoparticles with a high melting point are used as the solid catalysts, which provide a stable template for SWNT growth through the perpendicular growth mode. Trace amounts of iron are introduced to increase the efficiency of SWNT growth. Gas chromatography measurements and density functional theory show that the gas-phase iron acts as a pre-cracking assistance for the carbon source, promoting the growth of SWNTs. Carbon nanotube films with a high quality (average IG/ID = 166) are successfully prepared, a small diameter deviation (mean diameter of 1.6nm), and a high content of SWNTs (97%) using the IA-FSCCVD platform. This work provides a powerful way to prepare the carbon nanotube aggregates with a controlled structure.

The optical properties of nano-structural α-Fe2O3 dependence on the shape.

Three different crystal morphologies of α-Fe2O3, including uniform hexagonal, square, and rhombic shapes, were prepared according to the aqueous-thermal reaction. The hexagonal-shaped α-Fe2O3 was enclosed by the 104 plane, while the square and rhombic structures were enclosed by the 110 plane. Two absorption peaks at 455 and 532 cm-1 were found for the perpendicular (⊥) modes, and one absorption peak at 650 cm-1 appeared for the parallel (||) mode for hexagon-shaped α-Fe2O3 during analysis by Fourier-transform infrared spectroscopy. However, the peaks of square- and rhombic-shaped α-Fe2O3 for perpendicular (⊥) mode blueshifted, and the former two peaks merged together forming a broad band at approximately 480 cm-1. For Raman spectra determination, the peaks arose from the Brillouin zone center, and two additional peaks were observed at 660 and 1320 cm-1, belonging to 1 longitudinal optical (1LO) and 2 longitudinal optical (2LO) modes. All three materials exhibited higher intensities when excited at a wavelength of 633 cm-1. Furthermore, in the polarization state, the centers of all peak positions slightly shifted for hexagon-shaped α-Fe2O3, but all peak positions for square-shaped and rhombic-shaped α-Fe2O3 exhibited a significant blueshift. The structure of hexagon-shaped α-Fe2O3 was relatively tolerant regarding the polarization properties of vibration modes; however, the symmetry of crystal square-shaped and rhombic-shaped α-Fe2O3 changed, subsequently revealing different optical properties. RESEARCH HIGHLIGHTS: The hexagon-shaped, square-shaped, and rhombic-shaped α-Fe2O3 enclosed by different planes were synthesized. The Fourier Transform Infrared spectrometer peaks of α-Fe2O3 depended on their hexagon, square and rhombic shapes. Compared with hexagon-shaped α-Fe2O3, the Raman peaks for square and rhombi ones significantly shifted. The hexagon-shaped α-Fe2O3 is relatively tolerant regarding the polarization properties.

Integrating Dynamic Network Analysis with AI for Enhanced Epitope Prediction in PD-L1:Affibody Interactions.

Understanding binding epitopes involved in protein-protein interactions and accurately determining their structure are long-standing goals with broad applicability in industry and biomedicine. Although various experimental methods for binding epitope determination exist, these approaches are typically low throughput and cost-intensive. Computational methods have potential to accelerate epitope predictions; however, recently developed artificial intelligence (AI)-based methods frequently fail to predict epitopes of synthetic binding domains with few natural homologues. Here we have developed an integrated method employing generalized-correlation-based dynamic network analysis on multiple molecular dynamics (MD) trajectories, initiated from AlphaFold2Multimer structures, to unravel the structure and binding epitope of the therapeutic PD-L1:Affibody complex. Both AlphaFold2 and conventional molecular dynamics trajectory analysis were ineffective in distinguishing between two proposed binding models, parallel and perpendicular. However, our integrated approach, utilizing dynamic network analysis, demonstrated that the perpendicular mode was significantly more stable. These predictions were validated using a suite of experimental epitope mapping protocols, including cross-linking mass spectrometry and next-generation sequencing-based deep mutational scanning. Conversely, AlphaFold3 failed to predict a structure bound in the perpendicular pose, highlighting the necessity for exploratory research in the search for binding epitopes and challenging the notion that AI-generated protein structures can be accepted without scrutiny. Our research underscores the potential of employing dynamic network analysis to enhance AI-based structure predictions for more accurate identification of protein-protein interaction interfaces.

Correction of Aero-Optical Effect with Blow–Suction Control for Hypersonic Vehicles

High-speed turbulence induces significant aero-optical effects that severely disrupt the functionality of imaging systems of hypersonic vehicles. In this study, the aero-optical correction of various jet cooling modes is investigated using a Terminal High Altitude Area Defense (THAAD)-like seeker model and the imaging impact of high-speed flow field and flow control on the optical window is analyzed by the Delayed Detached Eddy Simulation (DDES) method. The findings reveal that a jet mode parallel to the window exhibits better cooling effectiveness compared to a perpendicular jet mode along the body axis; however, it introduces additional wavefront distortion, leading to degraded imaging quality. Although micro-vortex generators (MVGs) can reduce density fluctuations near the window from a refractive index perspective, they do not effectively mitigate wavefront distortion or improve window cooling efficiency. Finally, incorporating suction control, a comprehensive flow control solution, significantly improves the flow field structure near the window, resulting in a more uniform temperature distribution and reduced wavefront distortion. Applying this flow control method results in a 14.7% reduction in wavefront distortion at 3 Ma and an approximately 20% maximum value reduction at 5 Ma. This study proposes a novel and comprehensive flow control method to effectively mitigate the aero-optical effect in hypersonic flows, providing a new avenue for subsequent researchers in this field.

Analysis of hyperbolic magneto-hydrodynamic [HMHD] wave propagation through neutrino-coupled plasma

By using the Hyperbolic Magneto Hydrodynamic model, we investigated the propagation dynamics of a neutrino-coupled plasma system, with the influence of Hall current, rotation, viscosity and finite electrical resistivity. The general dispersion relation is obtained from the perturbed equations for both the Jean’s and neutrino beam instability. The effect of different parameters has been discussed in both parallel and perpendicular modes of wave propagation. The Jean’s instability condition is modified due to the presence of Hall current, Magnetic field and neutrino in both modes of propagation. The growth rate of the neutrino beam is affected by Hall current, viscosity magnetic field and rotation in both propagating modes. We also show the effect of different parameters on the growth rate of a neutrino-coupled plasma system through a graphical presentation.

Dispersion Analysis of Perpendicular Modes Using a Hybrid Two-Trace Two-Dimensional (2T2D) Smart Error Sum.

Using linear dichroism theory, one would assume that a z-cut of a uniaxial crystal is equivalent to an x-cut to determine the perpendicular component of the dielectric tensor and the corresponding oscillator parameters. However, Fresnel's equations show that the effect of interfaces in the form of the continuity relations of the different components of the electric field must be considered. A consequence of the continuity relations is that perpendicular modes increase less significantly in strength with increasing angle of incidence than expected. This is a consequence of the fact that it is the inverse of the perpendicular component of the dielectric function that increasingly becomes important with a growing angle of incidence. An inverse dielectric function, however, has typically much smaller values than the dielectric function. An additional consequence is that perpendicular modes are blueshifted and coupled in such a way that oscillator strength is transferred to the higher wavenumber mode. Thus, the spectral signatures of perpendicular modes are often weak and masked by the parallel modes when two modes overlap. Accordingly, to enable dispersion analysis, it is suggested to use a hybrid of the conventional residual sum of squares and the two-trace two-dimensional (2T2D) smart error sum, which can correct systematic multiplicable errors in the experimental spectrum. As demonstrated for fresnoite (Ba2TiSi2O8), this is an important step toward determining the perpendicular component of the dielectric tensor and the corresponding oscillator parameters using dispersion analysis, since asynchronous 2T2D correlation spectra are, in particular, sensitive to perpendicular modes.

Study on the bending and dimensional behavior of honeycomb latticed ONYX composite material

Engineering, architecture, and transportation all use honeycomb structures in various ways. Latticing, made possible by additive manufacturing (AM), may significantly speed up the creation of adaptable structures. The current study focuses on assessing the impact of various three-dimensional (3D)-printing features on the flexural behavior and dimensional studies of the honeycomb latticed micro-carbon fiber reinforced nylon (ONYX) material. The experiment is performed by varying the levels of 3D-printing features like layer thickness (LT), infill geometry (IG), build direction (BD), shell count (SC), and infill percentage (IP) to measure the bending strength, length deviation, and lattice surface morphology variation. The experimental results show that, the peak flexural strength of 79.84 MPa is attained with specimen fabricated at 0.1 mm LT, 50% IP, 0° BD, rectilinear IG, and SC of 3. And moreover, these respective 3D-printing feature levels resulted in an improved surface morphology on the latticed specimens. The length deviation results clearly depict that specimen fabricated at lower LT of 0.1 mm, higher SC of 3, rectilinear IG, 0° BD, and higher IP of 50% consequences in accurate profile with a lower length deviation of 0.117 mm. The fractography results clearly implies that the 0° oriented latticed ONYX composite results in a progressive fracture and results in higher bending stress. On the other hand, the 45° and 90° oriented latticed ONYX materials undergo tilted fracture and perpendicular mode of fracture, respectively. From that it is concluded that, the triangular-shaped honeycomb latticed ONYX materials are suitable for the development of brackets for the portable cameras, medical, and dental appliances like prosthetics for lightweight splints in postsurgery.

Photo-strain induced magnetoresistance modulation in magnetoelectric heterostructure-based devices

The electric-field control of magnetic dynamics and magnetization in magnetoelectric (ME) heterostructures holds promise for energy-efficient beyond-CMOS devices. However, such techniques entail a high-saturation operational electric field near the device breakdown voltage and introduce complexity due to the requirement for electrical contacts. This study circumvents this issue by light-induced magnetoresistance (MR) modulation in a Ni/PMN-PT ME heterostructure driven by photo-strain-induced internal electric field. Reduced MR, especially in the perpendicular mode, is observed, signifying a localized reduction in the external magnetic field required for magnetization alignment, as elucidated by Langevin function analysis. The proposed method could facilitate better integration and scalability of ME-based spintronic devices, paving the way for low-power beyond-CMOS technologies.

The Hunt for Perpendicular Magnetic Field Measurements in Plasma

The one consistent technique for remotely estimating the magnetic field in plasma has been Faraday rotation. It is only sensitive to the portion of the vector parallel to the propagation path. We show how to remotely detect the portion of the vector that is perpendicular using a modified measurement. Isolating this electromagnetic propagation wave mode to measure the magnetic field enables us to (i) study more about the magnetic field vector in plasma, (ii) reduce error in total electron content measurements, and (iii) discover new magnetic field information from archived data sets. The Appleton–Hartree equation is used to verify a new approach to calculating the phase change to an electromagnetic wave propagating through a plasma at frequencies larger than the gyrofrequency, the cyclotron frequency, and the upper hybrid frequency. Focusing on the perpendicular propagation modes, the simplified equation for the integrated path effect from a perpendicular magnetic field is calculated. The direction of the perpendicular component is unknown, because the magnetic field is squared. Isolating the magnetic term in the equation with dual frequency waves is shown. We also show how to eliminate the magnetic field contribution to total electron content measurements with a similar approach. In combination with Faraday rotation, the degeneracy of the magnetic field vector direction is reduced to a cone configuration.

Mixing temperature optimization and modification mechanism of medical masks modified asphalt: Insights from computational chemistry

Masks modified asphalt (MMA) offers a solution to pollution caused by discarded medical masks. Mixing temperature plays a crucial role in storage stability and even rheological performance of MMA. Traditional selection method overly relies on trial-and-error experiment, neglecting the convenience offered by computational chemistry. Furthermore, previous literature lacks precise elucidation of MMA’s physical modification mechanism, especially concerning the binding mode and energy composition. To address these issues, the optimal mixing temperature for MMA was recommended based on molecular dynamics. The rationality of recommended temperature was validated through laboratory tests, simultaneously investigating the impact of heating time. Fluorescence microscopy and multi-band spectroscopy were employed to acquire the microstructure. Binding modes in MMA were determined using binding sites exploration, evaluating the energy composition of each binding mode through quantum chemistry. The interaction mechanism was explained based on surface properties of isolated molecules. Results indicated that 170℃ was the recommended optimal mixing temperature derived from mixing free energy and Flory-Huggins interaction parameter. The fluctuations in softening point difference (ΔTR&B) and separation ratio (RS) concurrently tended towards stability, thereby validating the reliability of recommended temperature. Moreover, even after 72 h heating, MMA prepared at recommended temperature remained within a reasonable range concerning ΔTR&B, RS, and microscopic structure. Perpendicular, parallel, toroidal, and spherical modes emerged in MMA. Perpendicular and parallel modes exhibited the highest binding energies, while circular mode demonstrated the lowest. Binding energy is primarily governed by van der Waals interaction, attributed to the dominance of dispersion term on MMA’s molecular surface. Besides, due to the presence of polycyclic aromatic hydrocarbons in asphalt molecules, electrostatic interaction contributed to specific molecular bindings.

A DFT study on 2X- imidazole derivatives (X = OH, NH2, and SH) as corrosion inhibitors on Cu surfaces: Tautomerism effect

Adsorption of different tautomers of 2-hydroxy, 2-amino, and 2-mercapto imidazole as corrosion inhibitors on the (1 1 1), (1 1 0), and (1 0 0) copper surfaces in parallel and perpendicular modes are compared and evaluated by the DFT approach. Among different tautomers, imidazole with thiol, thione, and 1 H-imidazole-2-amine in imine form exhibited the best inhibition efficiency. Also, the quantum chemical descriptors and interaction energy magnitudes, as well as PDOSs, were calculated and used to evaluation of the interaction of organic molecules with the copper surfaces. In addition, Cu (1 1 0) showed the best protection in combination with imidazole derivatives.

Anisotropic gypsum scaling of corrugated polyvinylidene fluoride hydrophobic membrane in direct contact membrane distillation

Membrane distillation (MD) technology has gained a lot of attention for treatment of geothermal brine, high salinity waste streams. However, mineral scaling remains a major challenge when treating complex high-salt brines. The development of surface-patterned superhydrophobic membranes is one of the core strategies to solve this problem. We prepared flat sheet membranes (F-PVDF) and hydrophobic membranes with micron-scale corrugated pattern (C-PVDF) using a phase separation method. Their scaling behavior was systematically evaluated using calcium sulfate solutions and the impact of the feed flow was innovatively investigated. Although C-PVDF shows higher contact angle and lower sliding angle than F-PVDF, the scaling resistance of C-PVDF in the perpendicular flow direction has worst scaling resistance. Although the nucleation barrier of the corrugated membrane is the same at both parallel and perpendicular flow directions based on the traditional thermodynamic nucleation theory, experimental observations show that the C-PVDF has the best scaling resistance in the parallel flow direction. A 3D computational fluid dynamics (CFD) model was used and the hydrodynamic state of the pattern membranes was assessed as a determinant of the scaling resistance. The corrugated membrane with parallel flow mode (flow direction in parallel to the corrugation ridge) induces higher fluid velocity within the channel, which mitigated the deposition of crystals. While in the perpendicular flow mode (flow direction in perpendicular to the corrugation ridge), the solutions confined in the corrugated grooves due to vortex shielding, which aggravates the scaling. These results shed light on the mechanism of scaling resistance of corrugated membranes from a hydrodynamic perspective and reveal the mechanism of anisotropy exhibited by corrugated membranes in MD.

Unravelling crystal growth of nanoparticles.

Crystal growth from nanoscale constituents is a ubiquitous phenomenon in biology, geology and materials science. Numerous studies have focused on understanding the onset of nucleation and on producing high-quality crystals by empirically sampling constituents with different attributes and varying the growth conditions. However, the kinetics of post-nucleation growth processes, an important determinant of crystal morphology and properties, have remained underexplored due to experimental challenges associated with real-space imaging at the nanoscale. Here we report the imaging of the crystal growth of nanoparticles of different shapes using liquid-phase transmission electron microscopy, resolving both lateral and perpendicular growth of crystal layers by tracking individual nanoparticles. We observe that these nanoscale systems exhibit layer-by-layer growth, typical of atomic crystallization, as well as rough growth prevalent in colloidal systems. Surprisingly, the lateral and perpendicular growth modes can be independently controlled, resulting in two mixed crystallization modes that, until now, have received only scant attention. Combining analytical considerations with molecular dynamics and kinetic Monte Carlo simulations, we develop a comprehensive framework for our observations, which are fundamentally determined by the size and shape of the building blocks. These insights unify the understanding of crystal growth across four orders of magnitude in particle size and suggest novel pathways to crystal engineering.

Large Anomalous Frequency Shift in Perpendicular Standing Spin Wave Modes in BiYIG Films Induced by Thin Metallic Overlayers.

Interface-driven effects on magnon dynamics are studied in magnetic insulator-metal bilayers using Brillouin light scattering. It is found that the Damon-Eshbach modes exhibit a significant frequency shift due to interfacial anisotropy generated by thin metallic overlayers. In addition, an unexpectedly large shift in the perpendicular standing spin wave mode frequencies is also observed, which cannot be explained by anisotropy-induced mode stiffening or surface pinning. Rather, it is suggested that additional confinement may result from spin pumping at the insulator-metal interface, which results in a locally overdamped interface region. These results uncover previously unidentified interface-driven changes in magnetization dynamics that may be exploited to locally control and modulate magnonic properties in thin-film heterostructures.

Possible interplay of tangential and perpendicular modes in the growth of Fe-filled carbon nanotubes

Boundary layer chemical vapour synthesis is a fabrication approach which exploits random fluctuations within the viscous boundary layer established between a laminar flow of pyrolyzed ferrocene and a rough substrate, to yield iron filled radial carbon nanotubes (CNTs).

Engineering omniphobic corrugated membranes for scaling mitigation in membrane distillation

Membrane scaling is unavoidable when treating highly concentrated and even supersaturated brine in the continuous membrane distillation (MD) process. Omniphobic membranes with higher nucleation energy barriers could partially mitigate the membrane scaling. Herein, we fabricated omniphobic corrugated membranes to further alleviate membrane scaling via the synergistic effects of omniphobicity and corrugation on the membrane surface. The scaling behaviors of omniphobic flat membrane (#PVDF-FF), omniphobic corrugated membrane (#PVDF-CF) at parallel (PL) and perpendicular (PD) modes were investigated. Different modes represented the relative position between the feed flow direction and the pattern of corrugated membrane. The results showed that the modified corrugated membranes had water contact angles over 150° and anti-wettability against low surface tension liquids. Compared to #PVDF-FF, #PVDF-CF at the PL mode exhibited a better slippery property while the PD-mode #PVDF-CF had higher slippery resistance. The membrane omniphobicity was confirmed to be effective against membrane scaling when treating a 3.5 wt% NaCl feed solution. However, the scaling resistance of #PVDF-CF at both PL and PD modes was much better than that of #PVDF-FF when 25 wt% NaCl or 20 mM supersaturated gypsum solutions were used as feeds. The better anti-scaling properties of PL-mode #PVDF-CF should be attributed to a higher flow rate and shorter residence time of feed flow parallel to the corrugated patterns, as well as the alleviated concentration polarization. The turbulent effect induced by the perpendicular feed flow on the corrugated patterns and the consequent alleviation of concentration polarization endowed the PD-mode #PVDF-CF with the best scaling resistance.

Resonant phonon-magnon interactions in freestanding metal-ferromagnet multilayer structures

We analyze resonant magneto-elastic interactions between standing perpendicular spin wave modes (exchange magnons) and longitudinal acoustic phonon modes in free-standing hybrid metal-ferromagnet bilayer and trilayer structures. Whereas the ferromagnetic layer acts as a magnetic cavity, all metal layers control the frequencies and eigenmodes of acoustic vibrations. The here proposed design allows for achieving and tuning the spectral and spatial modes overlap between phonons and magnons that results in their strong resonant interaction. Realistic simulations for gold-nickel multilayers show that sweeping the external magnetic field should allow for observing resonantly enhanced interactions between individual magnon and phonon modes in a broad range of frequencies spanning from tens of GHz up to several hundreds of GHz, which can be finely tuned through the multilayer design. Our results would enable the systematic study and the deep understanding of resonantly enhanced magneto-elastic coupling between individual phonon and magnon modes up to frequencies of great contemporary fundamental and applied interest.

Linearly coupled transverse vibrations of tensioned bolts

In this study an analytical model for linear coupling between the two perpendicular transverse vibration modes in a tightened bolt is presented. The model shows an excellent fit with the experimental data suggesting that the coupling is dominantly linear. An experiment is performed to support the linearity claim. Two physical scenarios that could justify the theoretical model is given, one scenario involves asymmetric boundary stiffness and the other one measurements imperfection in location. This work is motivated by its application in structural health monitoring techniques, in particular those based on measuring transverse vibrations of bolts and other beam-like components.

Tunable magnon antibunching via degenerate three-wave mixing in a hybrid ferromagnet–superconductor system

We propose a scheme for achieving magnon antibunching in a hybrid ferromagnet–superconductor system, where the magnons excited in two yttrium iron garnet (YIG) spheres couple the different levels of a cyclic three-level superconducting qubit by eliminating two perpendicular microwave cavity modes. With the aid of the three-level system, we find that the magnon antibunching can be achieved in a weak coupling regime via the degenerate three-wave mixing process. Moreover, it is found that the magnon antibunching inside a YIG2 sphere can be effectively regulated by manipulating the YIG1 sphere, for instance, the coupling strength of the YIG1 sphere and qubit and the driving strengths of the system. This work provides an alternative scheme for constructing the single magnon source based on the ferromagnet–superconductor technology and is conducive to studying the quantum properties of magnons.