Interface Orientation Research Articles

Riding the Wave: Unveiling the Conformational Waves from RBD of SARS-CoV-2 Spike Protein to ACE2.

The binding affinity between angiotensin-converting enzyme 2 (ACE2) and the receptor-binding domain (RBD) plays a crucial role in the transmission and reinfection of SARS-CoV2. Here, microsecond molecular dynamics simulations revealed that point mutations in the RBD domain induced conformational transitions that determined the binding affinity between ACE2 and RBD. These structural changes propagated through the RBD domain, altering the orientation of both ACE2 and RBD residues at the binding site. ACE2 receptor shows significant structural heterogeneity, whereas its binding to the RBD domain indicates a much greater degree of structural homogeneity. The receptor was more flexible in its unbound state with the binding of RBD domains inducing structural transitions. The structural heterogeneity observed in the ACE2 unbound form plays a role in the promiscuity of viral entry, as it may allow the receptor to interact with various related and unrelated ligands. Furthermore, rigidity may be important for stabilizing the complex and ensuring the proper orientation of the RBD-binding interface with ACE2. The greater structural homogeneity observed in the ACE2-RBD complex revealed the effectiveness of neutralizing antibodies and vaccines that are primarily directed toward the RBD-binding interface. The binding of the B38 monoclonal antibody revealed restricted conformational transitions in the RBD and ACE2 receptors, attributed to its potent binding interaction.

Achieving excellent strength-ductility combination in Co60.8-xNi39.2Alx eutectic medium-entropy alloys

In this study, we design and prepare three eutectic medium-entropy alloys (EMEAs) with the composition of Co60.8-xNi39.2Alx (x = 19, 21.6 and 24). All three alloys exhibit a FCC-B2 dual-phase structure, which evolves from hypoeutectic to eutectic and then to hypereutectic with increasing Al content. The Co39.2Ni39.2Al21.6 EMEA demonstrates a complete lamellar eutectic structure with fine and disperse ordered L12 precipitations in the FCC phase, while the nano-scale strip L10 martensite is present in the B2 phase. The Co39.2Ni39.2Al21.6 EMEA exhibits an exceptional combination of strength and ductility, with high yield strength and elongation that are superior to other FCC-B2 dual-phase EMEA reported in the past five years. The superior ductility was related to the stable K–S interface orientation during the deformation process and the transformation-induced plasticity effect in B2 phases. The high strength is derived from the interface strengthening effect of the FCC-B2 interfaces. Moreover, the hindering of dislocation slipping by the ordered L12 precipitates and the Lomer-Cottrell locks in the FCC lamellar can also enhance the strength of the alloy. These findings have important implications for the structural design of eutectic high/medium-entropy alloys.

In situ observation of coalescence of nuclei in colloidal crystal-crystal transitions

Coalescence of nuclei in phase transitions significantly influences the transition rate and the properties of product materials, but these processes occur rapidly and are difficult to observe at the microscopic scale. Here, we directly image the coalescence of nuclei with single particle resolution during the crystal-crystal transition from a multilayer square to triangular lattices. The coalescence process exhibits three similar stages across a variety of scenarios: coupled growth of two nuclei, their attachment, and relaxation of the coalesced nucleus. The kinetics vary with nucleus size, interface, and lattice orientation; the kinetics include acceleration of nucleus growth, small nucleus liquefaction, and generation/annihilation of defects. Related mechanisms, such as strain induced by nucleus growth and the lower energy of liquid-crystal versus crystal-crystal interfaces, appear to be common to both atomic and colloidal crystals.

Influence of interface orientation and surface quality on structural and mechanical properties of SS316L/IN718 block produced using directed energy deposition

Functionally graded materials manufactured by additive manufacturing technologies reached high interest in additive manufacturing community over the last decades. High potential of additively manufactured multi-materials was demonstrated by many studies over the last 10 years. Most of the studies dealing with functionally graded materials had one common sign, which is the chemical composition gradient being controlled in the building direction of the final product. Hence, the multi-material interface is mostly situated in horizontal plane (XY) of the product. However, due to a complex geometry of the product, it is not always possible or desirable to achieve certain interface orientation and multi-material interface might incline from the ideal horizontal plane. Typically, corner zones, where interface orientation changes suddenly from horizontal to vertical orientation, are the most critical locations. Therefore, investigation of the interface orientation is important in order to establish the additive manufacturing limitation for certain applications. The current study revealed that the interface inclination has significant influence on the amount and distribution of formed defects at the materials interfaces. Furthermore, it was shown that the interface surface quality in terms of as-deposited surface or machined surface can significantly affects the defects formation. The effect of defects on the tensile specimen's elongation was significant, which based on the interface angle dropped over more than 70%.

The construction of lattice-matched CdS-Ag2S heterojunction photocatalysts: High-intensity built-in electric field effectively boosts bulk-charge separation efficiency

The built-in electric field of heterojunction can effectively promote carrier separation and transfer. While, its interface orientation is often random, leading to lattice mismatch and high resistance, thus limiting the efficiency of interfacial charge transfer. Herein, the lattice-matched heterojunction (CdS-Ag2S) was constructed by ion-exchange epitaxial growth. The results of surface photovoltage spectroscopy (SPV), transient photovoltage spectroscopy (TPV), and time-resolved photoluminescence (TRPL) show that the lattice-matched heterojunction has higher charge separation efficiency and longer photogenerated carrier lifetime than that of lattice-mismatched one. The lattice-matched CdS-Ag2S has a high built-in electric field (BIEF) value of 103.42 and a bulk-charge separation (BCS) efficiency of 68.71%, which is about three times higher than that of the lattice-mismatched heterojunction (CdS-Ag2S-M). In addition, the photodegradation efficiency of CdS-Ag2S towards norfloxacin (NOR) was also 3.4 times higher than that of CdS-Ag2S-M. The above results and density functional theory (DFT) calculations indicate that improving the lattice matching at the heterojunction is beneficial for establishing a high-intensity built-in electric field and effectively promoting bulk-charge separation efficiency, thus achieving excellent photocatalytic performance. This work provides an essential reference for the research of high-performance heterojunction photocatalysts.

Structure, stability and defect energetics of interfaces formed between conventional and transformed phases in Cu–Nb layered nanocomposite

Layered nanocomposite material having fcc-bcc interface with Kurdjumov-Sachs interface orientation relation has shown great potential as radiation resistant structural material for future fusion energy reactors. The superior radiation resistant properties of this material are attributed to it’s special fcc-bcc interface structure. In this study we have reported a stable interface between conventional bcc phase of Nb and transformed bcc phase of Cu. This bcc-bcc interface is found to be stable from both strain-energy and dynamical stability analysis. We have also shown that the bcc-bcc interface has different defect energetics behaviour compared to previously reported fcc-bcc interface which has a negative impact on the self annihilation property of the material against radiation induced defects. These aspects should be carefully considered in the future design of robust layered material for extreme radiation environment.

Influence of HCP/BCC interface orientation on the tribological behavior of Zr/Nb multilayer during nanoscratch: A combined experimental and atomistic study

Influence of HCP/BCC interface orientation on the tribological behavior of Zr/Nb multilayer during nanoscratch: A combined experimental and atomistic study

Molecular Dynamics Investigation of the Effect of the Interface Orientation on the Intensity of Titanium Dissolution in Crystalline and Amorphous Aluminum

The influence of the interface orientation on the intensity of dissolution of titanium in crystalline and amorphous aluminum is studied by molecular dynamics simulation. The following four orientations of the Ti–Al interface with respect to the Ti (hcp) and Al (fcc) lattices are considered: (1) (0001):(111), (2) (0001):(001), (3) (101¯0101¯0):(111), and (4) (101¯1101¯1):(001). The interface orientation is found to influence the intensity of dissolution of titanium in aluminum, which increases for the accepted designations in the order 1–2–3–4. An important phenomenon in this case turns out to be the formation of a thin (2–3 atomic planes thick) crystalline layer in aluminum, which repeats the crystal lattice of titanium, at the initial stage of dissolution. At a temperature below the melting point of aluminum, a grain boundary parallel to the interface forms behind this layer. At temperatures above the melting point of aluminum, this crystalline layer is preserved, but its thickness decreases gradually as the temperature increases. For aluminum in an amorphous state at temperatures below its melting point, the dissolution of titanium occurs at almost the same intensity as in the crystalline state of aluminum, which is explained by the formation of a similar crystalline layer in aluminum at the interface in all cases.

Molecular Dynamics Investigation of the Effect of the Interface Orientation on the Intensity of Titanium Dissolution in Crystalline and Amorphous Aluminum

Molecular Dynamics Investigation of the Effect of the Interface Orientation on the Intensity of Titanium Dissolution in Crystalline and Amorphous Aluminum

Molecular dynamics study of nano-indentation deformation behavior of Al/Al90Sm10 nanolaminate.

Molecular dynamics-based investigation has been carried out to simulate the nano-indentation loading in crystalline Al-amorphous Al90Sm10 metallic glass (MG) with an aim to investigate the effect orientation of crystalline-amorphous (C/A) interface orientation on the nano-indentation behavior of the C/A Al-Al90Sm10 nanolaminate for varying indenter speeds. Post-analysis techniques like adaptive-common neighbor analysis (a-CNA), atomic strain, dislocation extraction algorithm (DXA), and Voronoi polyhedral analysis (VP) have been employed to capture the structural evolution during simulated nano-indentation loading. C/A Al-Al90Sm10 nanolaminate with C/A interface orientated perpendicular to the indenter exhibits the presence of elastic regime followed by plastic curve, whereas load versus depth curve behaves plastically since the beginning in case of C/A Al-Al90Sm10 nanolaminate with C/A interface orientated parallel to the indenter. The dislocation density growth is slower in case of C/A Al-Al90Sm10 nanolaminate with C/A interface orientated perpendicular to the indenter attributed to the sinking of dislocations into MG counterpart of the nanolaminate, thereby triggering shear transformation zone activation. Whereas, the dislocation generation is delayed in case of C/A Al-Al90Sm10 nanolaminate with C/A interface orientated parallel to the indenter by virtue of amorphous Al90Sm10 MG coating on crystalline Al but is extensive and rapid. The disintegration of ICO-like structures and mixed clusters and growth of crystal-like clusters is discernible in C/A Al-Al90Sm10 nanolaminate with C/A interface orientated perpendicular to the indenter. On the other hand, the VP population exhibits cyclic variation in C/A Al-Al90Sm10 nanolaminate with C/A interface orientated parallel to the indenter. A transformation pathway of VPs has been mapped out for C/A Al-Al90Sm10 nanolaminate under nano-indentation loading. The simulations have been carried out by employing Molecular Dynamics using the Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) platform. Post-analysis techniques like adaptive-common neighbor analysis (a-CNA), atomic strain, dislocation extraction algorithm (DXA), and Voronoi polyhedral analysis (VP) have been employed to capture the structural evolution during simulated nano-indentation loading.

The necessity of others: Entrepreneurial self-efficacy, TMT collective efficacy, CEO-TMT interface, and entrepreneurial orientation.

Entrepreneurial orientation is the key factor for enterprises to obtain competitive advantages in dynamic circumstances. Thus, prior studies established the effect of psychological factors, for instance, entrepreneurial self-efficacy on entrepreneurial orientation using social cognitive theory. However, prior studies presented two main opposite views consisting of a positive and negative relationship between entrepreneurial self-efficacy and entrepreneurial orientation as well as providing no alleyway to enrich this relationship. We join the conversation on the positive linkage and argue on the essence of exploring the black box mechanisms to strengthen enterprises' entrepreneurial orientation. We employed the social cognitive theory and collected 220 valid responses from CEOs and TMTs from 10 enterprises in the high-tech industrial development zones of nine provinces in China to clarify the effect of top management team (TMT) collective efficacy, and CEO-TMT interface on the link between entrepreneurial self-efficacy and entrepreneurial orientation. Our findings show that entrepreneurial self-efficacy positively affects entrepreneurial orientation. In addition, we found that a higher level of TMT collective efficacy strengthens the positive relationship between entrepreneurial self-efficacy and entrepreneurial orientation. Moreover, we discovered differential moderating effects. First, CEO-TMT interface positively affects entrepreneurial orientation when it interacts with TMT collective efficacy and entrepreneurial self-efficacy. Second, CEO-TMT interface has a significant negative indirect effect on entrepreneurial orientation, when it only interacts with TMT collective efficacy. Our study enriches the entrepreneurial orientation literature by positioning TMT collective efficacy and CEO-TMT interface as social cognitive mechanisms underlying the development of entrepreneurial self-efficacy and entrepreneurial orientation nexus. Thus, we open a window of opportunities for CEOs and decision-makers to maintain a sustainable position in the market, grasping more opportunities in uncertain conditions via timely entries into new markets and maintaining pre-existing ones.

Microstructure-based prediction of UHPC's tensile behavior considering the effects of interface bonding, matrix spalling and fiber distribution

Ultra-high performance concrete (UHPC) is an ideal construction material to cut down carbon emissions due to its superior mechanical performance and durability. It is important to clarify the relationship between the microstructure and the overall tensile response of UHPC. In this paper, a microstructure-based multiscale framework is proposed to predict the stress-strain curve of UHPC under tensile load. The linear elastic stage is obtained by estimating the effective properties with the multi-level homogenization scheme based on the microstructure. The strain hardening and tension softening processes in the tensile curve are predicted with a statistical micromechanical damage model, where the characteristics of steel fibers are considered, including the effects of slip-softening, residual bonding strength of the fiber/matrix interface, matrix spalling and fiber orientation distribution. Comparisons with existing test results and previous models demonstrate the feasibility of using this multiscale framework to predict the overall tensile response of UHPC, especially the tension softening branch. Finally, the effects of interface parameters, matrix spalling degree, fiber orientation distribution, hydration degree and water/binder ratio on the tensile response of UHPC are evaluated and discussed with the proposed framework.

The effect of interface orientation on deformation behavior of Cu/Al multilayer during tensile process

The effect of interface orientation on deformation behavior of Cu/Al multilayer during tensile process

Revealing the interface properties of the Ti2AlC/TiAl composite from a first principles investigation

In order to systematically study the interface properties of Ti2AlC/TiAl composite from an atomic perspective, based on the interface orientation relations obtained by the high resolution transmission electron microscope technique, the work of adhesion, interface energy and electronic structure of 24 Ti2AlC/TiAl interface models with different terminations, different stacking sites, and different stacking sequences were calculated using the first principles calculation. The results show that the orientation relationship can be simplified to Ti2AlC(0001)/TiAl(111); the surface energy of 7-layer TiAl(111) is 1.71 J/m2, the surface energy at the Ti2AlC(0001)-Al is the lowest (most stable) in the Al-rich and Ti-rich environments; among the 24 interface models, C-hcp-hollow-BCA has the largest work of adhesion (9.7180 J/m2) implying the strongest interface bonding strength, and Al-fcc-hollow-ACB has the smallest interface energy (0.3644 J/m2) meaning the strongest interface stability; while Ti(Al)-hcp-hollow-BAC is considered to be the most ideal interface structure, combining strong interface bonding strength and stability due to its high work of adhesion (3.9679 J/m2) and low interface energy (0.8630 J/m2), and the interface bonding at Ti(Al)-hcp-hollow-BAC is mainly from Ti-Ti metallic bonds and Ti-Al covalent bonds through the analysis of electronic structure.

Microstructure and Texture of a Spinel Corona Around a Basalt Hosted Corundum Xenocrystal

AbstractThe microstructural and textural characteristics of a spinel corona that formed around a faceted corundum xenocrystal by reaction with the hosting basaltic melt in the Siebengebirge volcanic field demonstrate that the crystallographic and shape preferred orientation of spinel is influenced by the orientation of the reaction interface with respect to the corundum crystal lattice. The spinel roughly shows the common topotactic orientation relationships with corundum, where one of the $\{111\}_{Spl}$ planes is parallel to the (0001)$_{Crn}$ plane, and three of the $\{110\}_{Spl}$ planes are parallel to the $\{10\overline {1}0\}_{Crn}$ planes. In detail, there are subtle but systematic deviations from this topotactic relationship due to small rotations about the c-axis and/or an a-axis of corundum. The former is observed when the corundum c-axis is closely parallel to the interface plane, while the latter require a corundum a-axis orientation perpendicular to the interface. In this case, the preferred sense of rotation depends on the sign of the a-axis direction, irrespective of the spinel growth direction being parallel or antiparallel to this axis. Additionally, the selection of either one or both of two spinel twin variants that equally fulfill the topotactic orientation relationship depends on the orientation of the corundum-spinel interface with respect to the lattices of both the corundum and the spinel. Finally, also the grain boundary character is controlled by the interface orientation and the corundum lattice. Despite the differences between corona segments, the nature of these textures are persistent along and across each segment. We emphasize that all these microstructural and textural features are ascribed to the period of spinel growth in magmatic environment. The extent to which prominent slip planes in spinel are aligned parallel with the corundum-spinel interface seems to be of crucial importance for the nature of the spinel texture and microstructure, indicating that the activity of dislocations pertaining to these slip systems ease the accommodation of lattice misfit across the corundum-spinel interface. By comparison with experimentally grown spinel layers, we infer predominantly interface reaction controlled growth of the studied spinel corona.

Orientation of the stream interface in CIRs

Corotating Interaction Regions (CIRs) are complex structures in the Heliosphere that arise from the interaction of fast and slow solar wind streams. The interface between fast and slow solar wind is called the stream interface, which often has considerable north-south tilt. We apply a sliding window correlation method on multi-spacecraft data in order to obtain the time delay between the spacecraft. Using these time delays and in-situ solar wind velocity measurements, we can shift the positions of two spacecraft, and, together with the position of the reference spacecraft, we can reconstruct the spatial orientation of the stream interface. We examined four CIRs from two different solar sources at the beginning of 2007 using ACE, WIND, and STEREO-A spacecraft data. The gradually increasing distance between STEREO-A and the other spacecraft provides an opportunity to determine the effects of spacecraft separation on the quality of the results. In three out of the four events, the determined planes generally follow the Parker spiral in the ecliptic, their off-ecliptic tilt is determined by the position of the source of the high-speed stream. For the fourth event, STEREO-A was probably too far away for this method to be successfully applied.

Atomic and Electronic Structures of the Interfaces between Perovskite La0.75Sr0.25MnO3 and Brownmillerite SrCoO2.5

Epitaxial thin films composed of perovskite and brownmillerite oxides have received increasing attention because of the novel phenomena found in these systems. Herein, the atomic and electronic structures of the La0.75Sr0.25MnO3/SrCoO2.5 interface have been studied using first‐principles calculations. From the perspective of polarity compensation, three types of possible interface models are constructed, which have different interface terminations or orientation relationship. In the model where the [100] direction of SrCoO2.5 is parallel to the interface, the interface is polar. The way to compensate polarity is atomic reconstruction. For the model with the [100] direction of SrCoO2.5 perpendicular to the interface, there are two possible interface terminations. One is nonpolar. The other is polar, but its polarity can be compensated by electronic redistribution, i.e., the valence change of Mn from +3 to +4 at the interface, as consistently revealed by the change of the bond valence sums and magnetic moments of Mn ions. For this model with electronic redistribution, accompanied by the valence change, the MnO6 octahedra near the interface have the largest distortion compared with the other two models. The density of states around Fermi level and the magnetic coupling across the interface are also discussed.

Explaining the origin of the orientation of the front transformation in spin-transition crystals

Preferred orientations of the macroscopic high-spin (HS) low-spin (LS) interfaces appearing in spin transition molecular crystals during their phase transitions are explained through the study of a generalized 3D version of the electroelastic model accounting for an anisotropic change of the lattice parameters, $a, b$, and $c$ at the transition. The investigations are performed at 0 K by analyzing the energy landscape of a lattice made of two HS and LS phases, separated by a tilted interface with variable orientation, $\ensuremath{\theta}$ as a function of the anisotropy ratio, $\ensuremath{\lambda}=\frac{\mathrm{\ensuremath{\Delta}}b}{\mathrm{\ensuremath{\Delta}}a}=\frac{\mathrm{\ensuremath{\Delta}}b}{\mathrm{\ensuremath{\Delta}}c}$, where $\mathrm{\ensuremath{\Delta}}x={x}_{\mathrm{HS}}\ensuremath{-}{x}_{\mathrm{LS}}$ is the lattice misfit along $x\phantom{\rule{4pt}{0ex}}(\phantom{\rule{0.16em}{0ex}}=a,b,c)$ direction between HS and LS states. For large $\ensuremath{\lambda}<0$, the $\ensuremath{\theta}$ dependence of the relaxed total elastic energy depicts a symmetric double-well structure with two stable positions, ${\ensuremath{\theta}}_{\mathrm{min}}$, and an unstable orientation ${\ensuremath{\theta}}_{\mathrm{max}}={90}^{\ensuremath{\circ}}$. Beyond a critical value, ${\ensuremath{\lambda}}_{C}^{\ensuremath{-}}<0$, only one minimum subsists at $\ensuremath{\theta}={90}^{\ensuremath{\circ}}$, thus recalling the behavior of an order parameter of a 2nd order phase transition. On increasing $\ensuremath{\lambda}$, this minimum survives until a second threshold value ${\ensuremath{\lambda}}_{C}^{+}>0$ above which, the elastic energy recovers a double well configuration with two new preferential interface orientations, highlighting the existence of a re-entrant phenomenon. We demonstrate that the behavior of ${\ensuremath{\theta}}_{\mathrm{min}}$ versus $\ensuremath{\lambda}$ follows the same universality class as that of a second-order phase transition, for which we calculate the critical exponents $\ensuremath{\beta}$ and $\ensuremath{\nu}$ through a finite size scaling analysis. Overall, these investigations reveal that in switchable molecular solids with anisotropic unit cell deformation between the LS and HS states, there exists a stress-free interface orientation ensuring their integrity upon a large number of thermal cycles or loads during their practical utilization

Molecular dynamics study of defect evolutions and mechanical properties of W/Fe semi-coherent interfaces under irradiation

Molecular dynamic simulation has been performed to systematically investigate defect evolutions and mechanical properties of W/Fe semi-coherent interfaces under irradiation. For the simulation of damage cascades, a recently published EAM potential by our group has been first corrected using the universal potential of ZBL. On this basis, the dislocation loop evolutions and stress-strain curves of the irradiated W(110)/Fe(110) and W(100)/Fe(100) semi-coherent interfaces are derived. It has been found that interstitial atoms of pure W and Fe seriously accumulate with the increasing of irradiation times. Surprisingly, the formation of semi-coherent interfaces can trap the interstitials, and consequently inhibit the dislocation loop nucleation in W and Fe bulks to improve the irradiation resistance. The fundamental effects of interface orientation are also disscussed, and give a deep understanding of mechanical properties of W/Fe interfaces under irradiation.

A new model of a molecular rotor in the oscillating electric field

In the framework of classical electrostatics, the rotation of an adsorbed polar molecule near a plane interface between two homogeneous insulators under the influence of an external electric field E is considered. The molecule is treated as a permanent point dipole, which polarizes the interface and interacts with the induced image charges. It has been shown that a molecular rotor can emerge for an arbitrary (not normal or parallel to the interface) orientation of the field E.