Interfacial Distance Research Articles

Controllable Graphene/MoS2 Heterointerfaces by Perpendicular Surface Functionalization.

Surface chemistry and interface interactions profoundly influence the properties of two-dimensional (2D) materials and heterostructures. Therefore, developing methods to precisely control surfaces and interfaces is crucial for harnessing the properties and functions of 2D materials and heterostructures. Here, we developed a facile approach to tuning the interface distance and properties of graphene/MoS2 heterostructures (G/MoS2) by varying the functional groups attached to the surface of graphene bottom layer. We systematically investigated how different functionalized graphene bottom layers affect the interlayer distance, coupling between the interlayers, and optical properties of resulting G/MoS2 heterostructures. Our findings indicate that both the size and electron-withdrawing/donating properties of functional groups are pivotal in regulating charge transport properties, with size playing a particularly decisive role. Our approach demonstrates an efficient and flexible pathway to regulate the interlayer spacing and charge transport, highlighting the potential of engineering interface chemistry in optimizing properties of van der Waals heterostructures.

Tunable interfacial properties of monolayer GeSb2Te4 on metal surfaces

Abstract Atomically thin monolayer (ML) GeSb 2 Te 4 (GST) holds promising prospects in non-volatile memory applications because of its high non-homogeneous crystallization rate. In GST-based devices, the interaction between GST and metals is crucial, as it affects the electronic properties. Herein, based on first-principles calculations, we investigate the interaction and Schottky barrier height of contacts formed by the combination of ML GST with various metals. It is found that the interfaces of GST with Pt, Pd, Ir and W exhibit strong interaction, characterized by large binding energies ranging from 1.394 to 1.015 eV , and the interfaces between GST and Cu, Ag and Au display weak interaction. For the seven contacts, Ag and W form Ohmic contacts with ML GST, while Cu, Au, Pd, Ir, and Pt form n-type Schottky contacts, with Schottky barrier heights ranging from 0.029 to 0.353 eV . The strong Fermi level pinning at GST-metal interface is observed with a pinning factor of 0.378. Additionally, altering the interfacial distance and optimizing the layers of GST enable a transition from Ohmic contact to Schottky contact. These findings provide crucial guidance for the design and optimization of electronic devices based on phase change materials like GST.

Mechanical and Electrical Conductivity Properties of Graphene/Cu Interfaces: A Theoretical Insight.

For graphene/copper (Gr/Cu) composites, achieving high-quality interfaces between Gr and Cu (strong interfacial bonding strength and excellent electron transport performance) is crucial for enabling their widespread applications in electronic devices. This study employs first-principles calculations and the nonequilibrium Green's function method to systematically investigate the mechanical and electrical conductivity properties of Cu(111)/Gr/Cu(111) interfaces with various stacking sequences and different forms of Gr. For these interface systems, the binding energy, separation work, charge transfer, and electrical conductivity across the interface were obtained. The results show that the top-fcc interface exhibits superior interfacial properties, characterized by relatively high binding energy (-3.00 eV/C atom) and separation work (≥0.78 J/m2), a small interfacial distance (2.85 Å), and enhanced electron transport capacity (2.12 G0/nm2). A bilayer form of Gr significantly reduces electronic conductance across the Gr/Cu interface by nearly 2.46 orders of magnitude. Furthermore, point defects in Gr, especially single-vacancy defects, disrupt the traditional trade-offs between mechanical and electrical performance, simultaneously enhancing mechanical performance by 7.50-124.36% and electrical performance by 33.02%. Additionally, stress mechanisms have been proposed to further enhance the interfacial electrical conductivity of Gr/Cu composites. The present study provides a theoretical basis for exploring the engineering applications of Gr/Cu composite materials.

Magnetic Exchange Mechanism and Quantized Anomalous Hall Effect in Bi2Se3 Film with a CrWI6 Monolayer.

Magnetizing the surface states of topological insulators without damaging their topological features is a crucial step for realizing the quantum anomalous Hall (QAH) effect and remains a challenging task. The TI-ferromagnetic material interface system was constructed and studied by the density functional theory (DFT). A two-dimensional magnetic semiconductor CrWI6 has been proven to effectively magnetize topological surface states (TSSs) via the magnetic proximity effect. The non-trivial phase was identified in the Bi2Se3 (BS) films with six quantum layers (QL) within the CrWI6/BS/CrWI6 heterostructure. BS thin films exhibit the generation of spin splitting near the TSSs, and a band gap of approximately 2.9 meV is observed at the Γ in the Brillouin zone; by adjusting the interface distance of the heterostructure, we increased the non-trivial band gap to 7.9 meV, indicating that applying external pressure is conducive to realizing the QAH effect. Furthermore, the topological non-triviality of CrWI6/6QL-BS/CrWI6 is confirmed by the nonzero Chern number. This study furnishes a valuable guideline for the implementation of the QAH effect at elevated temperatures within heterostructures comprising two-dimensional (2D) magnetic monolayers (MLs) and topological insulators.

Nonvolatile Electric Control of Rashba Spin Splitting in Sb/In2Se3 Heterostructure.

Ferroelectric Rashba semiconductors (FRS) are highly demanded for their potential capability for nonvolatile electric control of electron spins. An ideal FRS is characterized by a combination of room temperature ferroelectricity and a strong Rashba effect, which has, however, been rarely reported. Herein, we designed a room-temperature FRS by vertically stacking a Sb monolayer on a room-temperature ferroelectric In2Se3 monolayer. Our first-principles calculations reveal that the Sb/In2Se3 heterostructure exhibits a clean Rashba splitting band near the Fermi level and a strong Rashba effect coupled to the ferroelectric order. Switching the electric polarization direction enhances the Rashba effect, and the flipping is feasible with a low energy barrier of 22 meV. This Rashba-ferroelectricity coupling effect is robust against changes of the heterostructure interfacial distance and external electric fields. Such a nonvolatile electrically tunable Rashba effect at room temperature enables potential applications in next-generation data storage and logic devices operated under small electrical currents.

Regulating the electronic and crystal structure of Na3V2(PO4)3 by pillar ionic substitution and p-type doping effects

Currently, low intrinsic conductivity seriously affects the development and large-scale application of Na3V2(PO4)3 (NVP). Herein, the binary K+/Mn2+ co-substituted Na2.96+xK0.04 V2-xMnx(PO4)3 (x = 0.005, 0, 0.01, 0.04) with enwrapped carbon nanotubes (CNTs) are synthesised. The incorporation of CNTs can form an effective conductive framework and provide more conductive paths, thus reducing the resistance of electron and ion migration thereby increasing the overall conductivity. Notably, replacing Na+ by pillar ion K+ with a larger radius can effectively strengthen the crystal structure of NVP, thus increasing the cycling stability of the battery. Besides, due to the differences in atomic radius and electronic structure between Mn2+ and V3+, this substitution can change the local environment of Na+ in the crystal, thus affecting its migration behaviour. Because of the larger ionic radius of Mn2+, it helps to increase the inter-facial distance in the crystal structure, which is favourable to promote the migration of Na+. Meanwhile, divalent Mn2+ occupying V3+ site can generate p-type doping effects, which introduces more hole carriers, thus increasing the intrinsic conductivity of the material. Accordingly, the optimized NVP/C@KMn0.01 achieves a capacity of 106.4 mAh g−1 at 1C, and maintains 98.1 mAh g−1 with a retention rate of 92.19 % after 230 cycles. At 15C, it reveals 106.1 mAh g−1 and keeps 82.5 mAh g−1 after 5800 cycles, corresponding to a capacity retention of 77.76 %. Furthermore, NVP/C@KMn0.01//CHC full cell delivers a high value of 155.0 mAh g−1 and enables to lighten the LED bulbs, indicating its excellent practical application prospects. The improved crystal structure of NVP/C@KMn0.01 is further verified by post-cycled XRD/SEM/XPS measurements.

Sulfur-Bridged Cationic Diazulenomethenes: Formation of Charge-Segregated Assembly with High Charge-Carrier Mobility.

Sulfur-bridged cationic diazulenomethenes were synthesized and exhibited high stability even under basic conditions due to the delocalization of positive charge over the whole π-conjugated skeleton. As a result of the effective delocalization and the absence of orthogonally oriented bulky substituents, the cationic π-conjugated skeletons formed a π-stacked array with short interfacial distances. A derivative with SbF6- as a counter anion formed a charge-segregated assembly in the crystalline state, rather than the generally favored charge-by-charge arrangement of oppositely charged species based on electrostatic interactions. Theoretical calculations suggested that the destabilization caused by electrostatic repulsion between two positively charged π-conjugated skeletons is compensated by the dispersion forces. In addition, the counter anion SbF6- played a role in regulating the molecular alignment through F⋯H-C and F-S interactions, which resulted in the charge-segregated alignment of the cationic π-skeletons. This characteristic assembled structure gave rise to a high charge-carrier mobility of 1.7 cm2 V-1 s-1 as determined using flash-photolysis time-resolved microwave conductivity.

First-principles calculation on the interfacial stability, electronic structure and fracture mechanism of NbN/AlN interface

The interfacial stability of NbN(111)/AlN(0001) including interfacial energy, Wad(work of adhesion) and electronic structure were studied by first-principles calculation. The N1-Nb-cen interface(constructed with N1-terminated AlN(0001) and Nb-terminated NbN(111)) is determined to be the most stable interface which has the smallest interfacial distance(1.11 Å) and largest Wad(15.04 J/m2) among the 28 considered interface models. The electronic structure and ideal tensile stress of the N1-Nb-cen, N2-Nb-top, Al2-N-top and Al1-Nb-cen interfaces were also investigated. The AlN surface has stronger ionic bond than that in NbN surface according to the analysis of Mulliken charges. The bonding feature of N1-Nb-cen interface is ionic with strong covalent, while the other three interfaces have mainly ionic bond. The ideal tensile stress of the N2-Nb-top interface is the largest (22.88 GPa) at the strain of 17 %, which is larger than that of N1-Nb-cen interface. The fracture will occur at the interface for the Al2-N-top and Al1-Nb-cen interfaces, while it occurs at the AlN interior for the N1-Nb-cen and N2-Nb-top interfaces, due to the Wad of the N1-Nb-cen and N2-Nb-top interfaces are larger than the other two interfaces and atomic stacking of AlN surface.

Critical charges for droplet collisions

Two micron-sized water droplets approaching each other do not always coalesce due to the cushioning effect of the air between them. When the droplets do not carry any electrical charges, one needs to consider the breakdown of hydrodynamics at very small scales to decide whether the droplets collide and coalesce or not. In contrast, two approaching droplets that are oppositely charged always coalesce if the charges are large enough. To find the charge for which the transition to charge-dominated collisions occurs, we computed the collision efficiency of charged, hydrodynamically interacting droplets settling in quiescent air, including the noncontinuum regime at small interfacial distances. For oppositely charged droplets, we find that the transition occurs when a saddle point of the relative droplet dynamics exits the region within which the continuum hydrodynamics breaks down. For cloud droplets with radii 16 and 20µm, we observe that the transition occurs at ∼103 elementary charges e. For charges smaller than this, we predict that the coalescence rate depends primarily upon the Knudsen number (Kn, the ratio of the mean-free-path of air to the mean droplet radius), whereas coalescence for much larger charges does not depend upon Kn. For droplets charged with the same polarity, we find the critical charge to be substantially larger (∼104e for the above radii) for reasons that we discuss. Published by the American Physical Society 2024

Unraveling interfacial thermal transport in β-Ga2O3/h-BN van der Waals heterostructures

As global power consumption rapidly increases with generation of significant amount of heat, efficient thermal management in electronic equipments becomes an urgent task, which requires a comprehensive understanding on thermal transport in heterostructures within devices. Here, we present detailed examination on the interfacial thermal transport of van der Waals (vdW) heterostructures, composed of β-Ga2O3 and hexagonal boron nitride (h-BN) multilayers. Through extensive molecular dynamics simulations, we show that the interfacial thermal conductance (ITC) of β-Ga2O3/h-BN system becomes as high as 136.8MWm−2K−1, and the high ITC value results from substantial phonon interaction across the interface. In addition to the pristine interface, the effect of structural modulation including strain, vacancies and substitutional defects in h-BN multilayers on the ITC is also analyzed, and it is demonstrated that there exists ranges of strain values and defect concentrations which increase the ITC, and that the enhanced ITC is the result of the interplay among the interfacial distance, the overlap in the phonon density of states and elastic mismatch between β-Ga2O3 and h-BN multilayers. These results not only provide insights into understanding interfacial phonon transport in vdW systems but also offer guiding principles for designing efficient heat dissipators in device applications.

In-situ measurements of contact evolution for fractal rough surfaces under normal compression

The contact interface plays a key role in the overall functionality and stability of structures. Understanding the evolution of the contact interface over time and its dependency on materials and load is crucial for functional integrity and operational safety assessment. In this study, we employ in-situ three-dimensional X-ray computed tomography (3DXRCT) to examine the creep behavior of 3D-printed surfaces exhibiting various roughness under constant normal compression. We observe that the overall contact area enlargement during the contact creep decreases with roughness amplitude and fractal dimension. The variation of interfacial separation distance is found to increase with roughness amplitude and decrease with fractal dimension. Correlation analysis reveals that the microcontact size played a more important role than the asperity shape in determining the microcontact enlargement. By examining the calculated interfacial strains extracted from XRCT measurements, significant deformations are found to occur at the non-contacting zones, indicating strong asperity interactions. This study offers high-resolution experimental measurements and unravels the asperity micromechanics for contact creep on rough surfaces, providing insights into understanding and optimizing the performance of rough interfaces.

Molecular Mechanisms of Sorbed Ion Effects during Boehmite Particle Aggregation.

Classical theories of particle aggregation, such as Derjaguin-Landau-Verwey-Overbeek (DLVO), do not explain recent observations of ion-specific effects or the complex concentration dependence for aggregation. Thus, here, we probe the molecular mechanisms by which selected alkali nitrate ions (Na+, K+, and NO3-) influence aggregation of the mineral boehmite (γ-AlOOH) nanoparticles. Nanoparticle aggregation was analyzed using classical molecular dynamics (CMD) simulations coupled with the metadynamics rare event approach for stoichiometric surface terminations of two boehmite crystal faces. Calculated free energy landscapes reveal how electrolyte ions alter aggregation on different crystal faces relative to pure water. Consistent with experimental observations, we find that adding an electrolyte significantly reduces the energy barrier for particle aggregation (∼3-4×). However, in this work, we show this is due to the ions disrupting interstitial water networks, and that aggregation between stoichiometric (010) basal-basal surfaces is more favorable than between (001) edge-edge surfaces (∼5-6×) due to the higher interfacial water densities on edge surfaces. The interfacial distances in the interlayer between aggregated particles with electrolytes (∼5-10 Å) are larger than those in pure water (a few Ångströms). Together, aggregation/disaggregation in salt solutions is predicted to be more reversible due to these lower energy barriers, but there is uncertainty on the magnitudes of the energies that lead to aggregation at the molecular scale. By analyzing the peak water densities of the first monolayer of interstitial water as a proxy for solvent ordering, we find that the extent of solvent ordering likely determines the structures of aggregated states as well as the energy barriers to move between them. The results suggest a path for developing a molecular-level basis to predict the synergies between ions and crystal faces that facilitate aggregation under given solution conditions. Such fundamental understanding could be applied extensively to the aggregation and precipitation utilization in the biological, pharmaceutical, materials design, environmental remediation, and geological regimes.

Abstract 905: ML quantification of tumor-Infiltrating lymphocytes distinguishes immune-phenotypes and reveals phenotypic heterogeneity

Abstract Immune phenotypes (IP), defined by the tumor-infiltrating lymphocyte (TIL) distribution within the tumor microenvironment (TME), is prognostic and predictive of treatment response. Here, machine learning (ML) models that characterize the TME were deployed in non-small cell lung cancer (NSCLC) and head and neck squamous cell carcinoma (HNSCC) to exhaustively label TILs directly from hematoxylin and eosin (H&E)-stained whole slide images (WSI), compute IP and quantify TIL distribution, tasks which are manually untenable. ML-powered TME models (PathAI, Boston, MA; commercially available as PathExplore™) for NSCLC and HNSCC that quantify tissue regions (e.g. tumor, epithelium, and stroma) and cells (e.g. lymphocytes) in H&E-stained WSI were deployed on 126 NSCLC and 103 HNSCC commercial samples. Ground truth CD3 and CD8 scores were obtained from paired immunohistochemically-stained WSI (HALO, Indica Labs, Albuquerque, NM). Inflamed, desert, or excluded IPs (based on data-driven cutoffs) were inferred from the mean TIL density in epithelium and stroma (slide-level IP, sIP), and from the fraction of “hot” patches in all 100um x 100um patches tiling the tumor and stroma areas (patch-level IP, pIP). TIL spatial distribution was measured by the Morisita-Horn index that computes the patch-wise overlap between TILs and cancer cells (MHI, ranging from 0 to 1), and epithelial-stromal interface distance index (EDI) indicating the hot stromal patch bias toward the epithelium (-EDI) or stroma (+EDI). ML-predicted TIL densities highly correlated with ground truth CD3+ and CD8+ cell densities (NSCLC/HNSCC CD3, CD8: tumor Pearson r= 0.88/0.85, 0.74/0.74; epithelium r= 0.76/0.71, 0.88/0.62; stroma r= 0.74/0.87, 0.61/0.76). High s- and pIP agreement was seen (NSCLC 93% and HNSCC 83%); 6/26 discordant cases were driven by TIL hotspots with high density (116%-310% of the cutoff) but few (median = 26%) hot patches in the epithelium. MHI was higher for the inflamed vs excluded IP (p < 0.0001 for NSCLC and HNSCC) and intra-group variability was high (NSCLC/HNSCC inflamed: 0.66±0.11/0.31±0.14, excluded: 0.51±0.12/0.26±0.17, desert: 0.48±0.09/0.28±0.17; mean±std). EDI was lowest and negative in inflamed IP but near zero in desert and excluded IP (NSCLC/HNSCC inflamed: -43±4um/-184±19um, excluded: 1.6±4um/-41±13um, desert: 18±4um/-14±13; mean±sem). Excluded and desert IPs had roughly equal + and - EDI cases (NSCLC +/-: 57/46; HNSCC +/-: 39/29). ML-powered IP prediction using TIL distribution enables accurate and rapid profiling of the TME using routine histopathology. pIPs were concordant with sIPs and highlight TIL heterogeneity. Spatial markers (MHI and EDI) reveal differences between IP classes and intra-group heterogeneity relevant for drug discovery and patient stratification. Investigating prognostic associations of these markers is a promising direction for future studies. Citation Format: Nhat Le, Bahar Rahsepar, Jennifer Hipp, Jake Conway, Ylaine Gerardin, Emma Krause, Ciyue Shen, Raymond Biju, Michael Nercessian, Nicholas Indorf, Sandrine Degryse, Miles Markey, Victoria Mountain, Pranjal Vaidya, William Wijaya, Aditee Shrotre, Patrick Caplazi, David Inzunza, Joann Palma, Erik Huntzicker, Catherine Tribouley, Diana Chen, Raluca Prediou, Francine Chen, Kevin Kolahi. ML quantification of tumor-Infiltrating lymphocytes distinguishes immune-phenotypes and reveals phenotypic heterogeneity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 905.

Dynamics of the Deformable Fluid Interface Interacting with an Approaching Solid under the Electrostatic Field.

A theoretical model was developed to describe the dynamics of a deformable fluid interface interacting with an approaching solid without contact by both the attractive electrostatic and van der Waals (i.e., vdW) interaction, analogous to the situation in the experiments by electric force microscopy (i.e., EFM) or electric-surface force apparatus (i.e., E-SFA) involved in the soft fluid interface. On the basis of this model, a numerical study of the deformation of the fluid interface, the force-vs-separation behavior, and the critical limiting conditions of contact has systematically been carried out. Our results show that the surface pressure induced by the electrostatic interaction plays a more prominent role in the deformation of the fluid interface than the vdW interaction does, and there exists a principal length scale associated with the relative strength of the electrostatic field to the surface tension, affecting the fluid interface shape under the electrostatic field. It was also shown that both the force-distance curves and the corresponding curves of fluid interface deformation peak versus distance for various electrostatic fields satisfy the universal scaling power law. Moreover, an analytical solution to the Euler-Lagrange differential equation governing the deformation of the fluid interface under the external electric field is obtained, and two extended formulas for explicitly describing the principal length scales that respectively characterize the lateral and longitudinal deformations of the fluid interface were determined.

Hydrogen Spillover Phenomenon at the Interface of Metal-Supported Electrocatalysts for Hydrogen Evolution.

ConspectusHydrogen spillover, as a well-known phenomenon for thermal hydrogenation, generally involves the migration of active hydrogen on the surface of metal-supported catalysts. For thermocatalytic hydrogenation, hydrogen spillover generally takes place from metals with superiority for dissociating hydrogen molecules to supports with strong hydrogen adsorption under a H2 environment with high pressures. The former can bring high hydrogen chemical potential to largely reduce the kinetic barrier of the migration of active hydrogen species from metals to supports. At the same time, the latter can make H* migration thermodynamically spontaneous. For these reasons, hydrogen spillover is a common interfacial phenomenon occurring on metal-supported catalysts during thermocatalysis. Recently, this phenomenon has been observed for the exceptionally enhanced electrocatalytic performance for hydrogen evolution and other electrocatalytic organic synthesis. Different from hydrogen spillover for thermocatalysis under high H2 pressure, hydrogen spillover for electrocatalysis involves the migration of active hydrogen species (H*) from metals with strong hydrogen adsorption to supports with weak hydrogen adsorption, thereby suffering from a thermodynamically unfavorable process accompanied by a high kinetic barrier. Thus, the occurrence of hydrogen spillover at the electrocatalytic interface is not easy, and successful cases are rare. Understanding the underlying nature of hydrogen spillover at the electrocatalytic interface of metal-supported catalysts is critical to the rational design of advanced electrocatalysts.In this Account, we provide in-depth insights into recent advances in hydrogen spillover at the electrocatalytic interface for a significantly enhanced hydrogen evolution performance. Electron accumulation at the metal-support interface induces severe interfacial H* trapping and is recognized as the main factor in the failed hydrogen spillover. Given this, we developed two novel strategies to promote the occurrence of hydrogen spillover at the electrocatalytic interface. These strategies include (i) the introduction of ligand environments to enrich the local hydrogen coverage on metals and lower the barrier for interfacial hydrogen spillover and (ii) the minimization of work function difference between metals and supports (ΔΦ) to relieve electron accumulation and lower the kinetic barrier for hydrogen spillover. Also, we summarize the previously reported strategy of shortening the metal-support interface distance to lower the kinetic barrier for interfacial hydrogen spillover. Afterward, some criteria and methodologies are proposed to identify the hydrogen spillover phenomenon at the electrocatalytic interface. Finally, the remaining challenges and future perspectives are also discussed. Based on this Account, we aim to provide new insights into electrocatalysis, particularly the targeted control of hydrogen spillover at the electrocatalytic interface, and then to offer guidelines for the rational design of advanced electrocatalysts.

Investigating Chain‐Like Core‐Shell Ge Nanowires Coated with Carbon Nanotubes Through Atomic Simulations: Implication for Improving Binding and Mechanical Properties

AbstractAtomic simulations within the classical mechanics' formalism are used to investigate the interfacial binding between carbon nanotubes (CNTs) and germanium nanowires (GeNWs) as well as the mechanical properties of the chain‐like coreshell germanium nanowires coated with CNTs. The simulations at the atomic scale provide the effect of temperature, systems’ cross–sectional diameter, interfacial distance, applied tension loading on their binding degree, and deformation behaviors. The simulation results reveal that the spacing between CNT and nanowires as well as the interfaces formed between them directly affect the thermal stability and the degree of interfacial bonding of the systems. The coreshell GeNWs coated with CNTs present significantly excellent mechanical properties. The Lode‐Nadai parameters and the atomic hydrostatic pressures on the atoms can be used to identify atoms’ bearing states in different regions and the stress‐transfer paths during different stages including elasticity, plasticity, and fracture of the confined systems.

In-situ construction of Z-scheme 2D/2D g-C3N4/BiOBr heterojunction with enhanced photocatalytic CO2 reduction

A novel series of g-C3N4/BiOBr (CN/BOB) Z-scheme heterojunction catalysts with two-dimensional/two-dimensional (2D/2D) morphology were synthesized by an in-situ hydrolysis method for photocatalytic CO2 reduction. Without adding any sacrificial agents or co-catalysts, the optimal CN/BOB heterostructure exhibits a boosted CO generation rate of 20.1 μmol·g-1·h-1 under the simulated solar light irradiation, severally being 1.7 and 3.7 times that of pristine BiOBr and g-C3N4. The enhanced performance principally benefit from the 2D/2D microstructure and Z-scheme heterojunction of photocatalysts. The intimate contact of 2D/2D morphology signifies more transmission channels and shorter transfer interface distance of photogenerated charges. While relevant characterizations and first-principles calculations jointly demonstrate that the Z-scheme heterojunction could significantly accelerate the spatial separation and transfer of photo-induced carriers, and evidently promote the redox ability of photocatalysts. The research furnishes a novel strategy to construct a promising bismuth oxyhalide based heterojunction catalyst for the application of photocatalytic CO2 reduction.

Investigating the binding and mechanical properties of carbon nanotube-encapsulated Si nanowires: A perspective from atomic simulations

Atomic simulations using classical mechanics formalism are used to investigate the interfacial binding between CNTs and silicon nanowires as well as mechanical properties of the CNTs encapsulated silicon nanowires systems. The simulations provide the effect of temperature, systems' cross-sectional radius, interfacial distance, applied tension on their binding degree and deformation behaviors. The simulation results reveal that the spacing and interfaces between CNT and nanowire significantly affect thermal stability and the degree of interfacial binding in the systems. The Lode-Nadai values' distributions in the systems provide insight into the loading states on the atoms both in CNTs and silicon nanowires during tension. The atomic hydrostatic pressures can be used to identify stress-transfer paths in the systems during the elasticity, plasticity, and fracture stages.

Color discrepancy of single-shade composites at different distances from the interface measured using cell phone images.

This study aimed to evaluate the impact of substrate color and interface distance on the color adjustment of 2 single-shade composites, Vittra APS Unique and Charisma Diamond One. Dual disc-shaped specimens were created using Vittra APS Unique or Charisma Diamond One as the center composite, surrounded by shaded composites (A1 or A3). Color measurements were taken with a spectrophotometer against a gray background, recording the color coordinates in the CIELAB color space. Illumination with a light-correcting device and image acquisition using a polarizing filter-equipped cell phone were performed on specimens over the same background. Image processing software was used to measure the color coordinates in the center and periphery of the inner composite and in the outer composite. The color data were then converted to CIELAB coordinates and adjusted using data from the spectrophotometer. Color differences (ΔE00) between the center/periphery of single-shade and outer composites were calculated, along with color changes in single-shade composites caused by different outer composites. Color differences for the inner composites surrounded by A1 and A3 were also calculated. Data were analyzed using repeated-measures analysis of variance (α = 0.05). The results showed that color discrepancies were lowest near the interface and when the outer composite was whiter (A1). Additionally, Charisma Diamond One exhibited better color adjustment ability than Vittra APS Unique. Color discrepancies between the investigated single-shade composites diminished towards the interface with the surrounding composite, particularly when the latter exhibited a lighter shade.

Effect of abutment type and creep behavior on the mechanical properties of implant restorations in the anterior region: A finite element analysis.

This study aimed to assess the effect of abutment variation and creep on dental implant restorations. Three finite element analysis (FEA) models of implant restorations were created, which were restored by conventional one-piece abutment (CA), hybrid abutment crown (HAC), and multi-unit abutment (MUA). The contacts were considered intimate (no friction), except for implant/abutment, abutment/screw, and abutment/screw/crown (HAC) attachments. The related mechanical parameters were used to improve the authenticity of the study. Instantaneous loads and constant loads (100 s) of 130 N were applied at a 30° angle to the palatal portion of the crown. Results were qualitatively and quantitatively evaluated using the equivalent von Mises stress, micro-gap distance of the implant-abutment interface (IAI), preload changes, and safety index. The stress state of each component differed depending on the restoration type, from CA and HAC to MUA. Implants and screws were the structures that suffered the most stress under instantaneous loads. Each metal structure exhibited a substantial decrease in stress during a constant loading period. The screws of the MUA abutment showed more preload loss (62.1 N) after constant loads for 100 s. MUA base produced less micro-gap (0.72 μm) at the IAI when it was compared with the CA group (0.93 μm) and HAC group (3.29 μm). The abutment type influences the mechanical properties and performance of implant restorations. The creep effect decreases the maximum stress level and increases the safety factors of each structure, indicating that stress-related mechanical complications may not occur more easily.