Interface Orientation Research Articles

Emission Control by Molecular Manipulation of Double-Paddled Binuclear PtII Complexes at the Air-Water Interface.

Molecular functions depend on conformations and motions of the corresponding molecular species. An air-water interface is a suitable asymmetric field for the control of molecular conformations and motions under a small applied force. In this work, double-paddled binuclear PtII complexes containing pyrazole rings linked by alkyl spacers were synthesized and their orientations and emission properties dynamically manipulated at the air-water interface. The complexes emerge from water with concurrent variation of interface orientation of the planes of the PtII complexes from perpendicular to parallel during mechanical compression suggesting a unique 'submarine emission'. Phosphorescence of the complexes is quenched at the air-water interface prior to monolayer formation with intensities subsequently rapidly increasing during monolayer compression. These results indicate that asymmetric reactions and motions might be controlled by applying mechanical force at the air-water interface.

MOLECULAR DYNAMICS STUDIES ON THE STRENGTH PREDICTION OF INTERFACE BETWEEN AL-AL4C3 IN METAL MATRIX NANOCOMPOSITES

In this study, molecular dynamics simulations (MD) will be applied to modelling the Al4C3-aluminum interface in aluminum nanocomposite, Al4C3 is an interface that results from the shaker mill process which becomes a bridge that plays an important role in Carbon particles with Aluminium Matrix and Based on observations from the TEM characterization, it is found that the relationship between Al orientation to Al4C3 is (111) (002) (220). The characteristics of the interface between Aluminum matrix and Al4C3 will be analyzed using uniaxial tension and shear test simulation. The atomic potential used in this simulation is the embedded atomic method (EAM) for Al, empirical-order intermolecular potential (AIREBO) for C and lennard jones for the reaction of Al-C atom. The result shows that, the interface orientation is Al matrix (002) || Al4C3 (003) has the highest interface strength compared to Al matrix (111) || Al4C3 (003) and Al matrix (200) Interface orientation || Al4C3 (003). Results from the molecular dynamics simulations are also discussed with analytical results obtained experimental

MOLECULAR DYNAMICS STUDIES ON THE STRENGTH PREDICTION OF INTERFACE BETWEEN AL-AL4C3 IN METAL MATRIX NANOCOMPOSITES

In this study, molecular dynamics simulations (MD) will be applied to modelling the Al4C3-aluminum interface in aluminum nanocomposite, Al4C3 is an interface that results from the shaker mill process which becomes a bridge that plays an important role in Carbon particles with Aluminium Matrix and Based on observations from the TEM characterization, it is found that the relationship between Al orientation to Al4C3 is (111) (002) (220). The characteristics of the interface between Aluminum matrix and Al4C3 will be analyzed using uniaxial tension and shear test simulation. The atomic potential used in this simulation is the embedded atomic method (EAM) for Al, empirical-order intermolecular potential (AIREBO) for C and lennard jones for the reaction of Al-C atom. The result shows that, the interface orientation is Al matrix (002) || Al4C3 (003) has the highest interface strength compared to Al matrix (111) || Al4C3 (003) and Al matrix (200) Interface orientation || Al4C3 (003). Results from the molecular dynamics simulations are also discussed with analytical results obtained experimental

Effect of initial interface orientation on patterns produced by vibrational forcing in microgravity

When a container with two distinct fluids is subjected to vibrations in microgravity, the interface may undergo a variety of instabilities and develop towards a complex structure, as seen in recent parabolic flight experiments using both miscible and immiscible liquids. Among other things, the selected pattern depends on the frequency and amplitude of the forcing and, crucially, on its orientation with respect to the initial interface. In a parabolic flight experiment, this initial orientation is largely determined by the stage of the parabolic manoeuvre when the forcing is started and the residual gravity level during the period of microgravity. It plays a key role in the appearance of defects and irregularities during the evolution of the interface triggered by the frozen wave instability. Using numerical simulations, we systematically investigate the effect of initial interface orientation on pattern selection in microgravity for both miscible and immiscible fluids, and compare to available experiments. When the interface and the forcing are nearly aligned, the frozen wave instability is dominant, leading to the development of approximately regular columnar patterns. As the initial angle becomes more oblique, the frozen wave growth becomes more irregular and asymmetric and may involve thin auxiliary columns. Sufficiently large angles suppress the frozen wave instability and, depending on the container aspect ratio, may result in a simple two-column final state.

Influence of choice of substrate and film thickness on magneto-optical properties of SmFeO3 thin films

Herein, SmFeO3 thin films are prepared by using magnetron sputtering technology on quartz-glass and SrTiO3(STO)(1 0 0) substrates. The influence of film thickness and choice of substrate on film quality and growth orientation is studied in detail. Moreover, the impact of phase purity and growth orientation on optical, magnetic and magneto-optical properties is discussed. The results reveal that the film thickness and choice of substrate significantly influence the induced stresses at film/substrate interface and growth orientation of the annealed film. The as-fabricated SmFeO3 thin films have demonstrated highly crystalline structure, excellent transmittance and enhanced magneto-optical properties. Moreover, obvious anisotropy in magnetization and magneto-optical properties has been observed. The SmFeO3 films with excellent magneto-optical properties can be fabricated by selecting optimal film thickness and substrate. It is expected that SmFeO3 film is a promising material for integrated optical isolators and magneto-optical modulators.

Mesoscopic valley filter in graphene Corbino disk containing a p–n junction

The Corbino geometry allows one to investigate the propagation of electric current along a p–n interface in ballistic graphene in the absence of edge states appearing for the familiar Hall-bar geometry. Using the transfer matrix in the angular-momentum space we find that for sufficiently strong magnetic fields the current propagates only in one direction, determined by the magnetic field direction and the interface orientation, and the two valleys, K and K′, are equally occupied. Spatially-anisotropic effective mass may suppress one of the valley currents, selected by the external electric field, transforming the system into a mesoscopic version of the valley filter. The filtering mechanism can be fully understood within the effective Dirac theory, without referring to atomic-scale effects which are significant in proposals operating on localized edge states.

Electronic Structure Shift of Deeply Nanoscale Silicon by SiO2 versus Si3N4 Embedding as an Alternative to Impurity Doping

Conventional impurity doping of deep nanoscale silicon (dns-Si) used in ultra large scale integration (ULSI) faces serious challenges below the 14 nm technology node. We report on a new fundamental effect in theory and experiment, namely the electronic structure of dns-Si experiencing energy offsets of ca. 1 eV as a function of SiO$_2$- vs. Si$_3$N$_4$-embedding with a few monolayers (MLs). An interface charge transfer (ICT) from dns-Si specific to the anion type of the dielectric is at the core of this effect and arguably nested in quantum-chemical properties of oxygen (O) and nitrogen (N) vs. Si. We investigate the size up to which this energy offset defines the electronic structure of dns-Si by density functional theory (DFT), considering interface orientation, embedding layer thickness, and approximants featuring two Si nanocrystals (NCs); one embedded in SiO$_2$ and the other in Si$_3$N$_4$. Working with synchrotron ultraviolet photoelectron spectroscopy (UPS), we use SiO$_2$- vs. Si$_3$N$_4$-embedded Si nanowells (NWells) to obtain their energy of the top valence band states. These results confirm our theoretical findings and gauge an analytic model for projecting maximum dns-Si sizes for NCs, nanowires (NWires) and NWells where the energy offset reaches full scale, yielding to a clear preference for electrons or holes as majority carriers in dns-Si. Our findings can replace impurity doping for n/p-type dns-Si as used in ultra-low power electronics and ULSI, eliminating dopant-related issues such as inelastic carrier scattering, thermal ionization, clustering, out-diffusion and defect generation. As far as majority carrier preference is concerned, the elimination of those issues effectively shifts the lower size limit of Si-based ULSI devices to the crystalization limit of Si of ca. 1.5 nm and enables them to work also under cryogenic conditions.

A 3D Moment of Fluid method for simulating complex turbulent multiphase flows

This paper presents the moment of fluid method as a liquid/gas interface reconstruction method coupled with a mass momentum conservative approach within the context of numerical simulations of incompressible two-phase flows. This method tracks both liquid volume fraction and phase centroid for reconstructing the interface. The interface reconstruction is performed in a volume (and mass) conservative manner and accuracy of orientation of interface is ensured by minimizing the centroid distance between original and reconstructed interface. With two-phase flows, moment of fluid method is able to reconstruct interface without needing phase volume data from neighboring cells. The performance of this method is analyzed through various transport and deformation tests, and through simple two-phase flows tests that encounter changes in the interface topologies. Exhaustive mesh convergence study for the reconstruction error has been performed through various transport and deformation tests involving simple two-phase flows. It is then applied to simulate atomization of turbulent liquid diesel jet injected into a quiescent environment. The volume conservation error for the moment of fluid method remains small for this complex turbulent case.

Cohesion strength and fracture toughness of Mo-TiC interfaces

First principles calculations reveal that interface orientation plays a decisive role in determining the cohesion properties of Mo-TiC interfaces, i.e., the addition of TiC (111) surface to Mo (110) surface could increase the cohesion strength and toughness/ductility of Mo (110) surface, whereas TiC (100) surface would decrease the cohesion strength and toughness/ductility of Mo (100) or Mo (110) surface. The present calculated results are deeply understood in terms of electronic structure, agree well with experimental observations, and could clarify the two experimental controversies regarding the effects of TiC on cohesion strength and fracture toughness of Mo in the literature.

Long-Range Conformational Changes in Monoclonal Antibodies Revealed Using FPOP-LC-MS/MS.

Differences in conformational dynamics between two full-length monoclonal antibodies have been probed in detail using Fast Photochemical Oxidation of Proteins (FPOP) followed by proteolysis and LC-ESI-MS/MS analyses. FPOP uses hydroxyl radical labeling to probe the surface-accessible regions of proteins and has the advantage that the resulting covalent modifications are irreversible, thus permitting optimal downstream analysis. Despite the two monoclonal antibodies (mAbs) differing by only three amino acids in the heavy chain complementarity determining regions (CDRs), one mAb, MEDI1912-WFL, has been shown to undergo reversible self-association at high concentrations and exhibited poor pharmacokinetic properties in vivo, properties which are markedly improved in the variant, MEDI1912-STT. Identifying the differences in oxidative labeling between the two antibodies at residue level revealed long-range effects which provide a key insight into their conformational differences. Specifically, the amino acid mutations in the CDR region of the heavy chain resulted in significantly different labeling patterns at the interfaces of the CL-CH1 and CH1-CH2 domains, with the nonaggregating variant undergoing up to four times more labeling in this region than the aggregation prone variant, thus suggesting a change in the structure and orientation of the CL-CH1 interface. The wealth of FPOP and LC-MS data obtained enabled the study of the LC elution properties of FPOP-oxidized peptides. Some oxidized amino acids, specifically histidine and lysine, were noted to have unique effects on the retention time of the peptide, offering the promise of using such an analysis as an aid to MS/MS in assigning oxidation sites.

Automatic Identification of the Rock-Soil Interface and Solution Fissures From Optical Borehole Images Based on Color Features

For high-resolution borehole images obtained from digital panoramic borehole cameras, a method for recognizing the rock-soil interface and solution fissures based on color is proposed. Owing to the significantly different colors of geotechnical stratifications, such as the rock-soil interface and solution fissures, compared with bedrock, a self-adaptive geotechnical stratification detection model based on the hue, saturation, value (HSV) color space was established. A binarized image of the geotechnical stratification in the borehole was then obtained using this model. The binary image was filtered to depress the noise, and then segmented. The density of pixels in each segment was calculated to determine the depth, area, and orientation of the rock-soil interface and solution fissures, thereby identifying the geotechnical stratification in the borehole image. Verification of the method with many borehole images and comparisons with corresponding borehole radar images illustrates that it can accurately and quickly identify all rock-soil interfaces and solution fissures in a borehole. The proposed method provides a new automated, efficient, and reliable means of identifying borehole rock structures for engineering applications.

Role of the shell thickness in the core transformation of magnetic core(Fe)-shell(Au) nanoparticles

Fe-Au core-shell nanoparticles embedded in an amorphous alumina matrix are synthesized at high temperature using magnetron sputtering. The nanoparticles display a single-crystal Fe core covered by a crystalline Au shell epitaxially grown on the different core facets. The morphology of the grown nanoparticles is analyzed by transmission electron microscopy, while their structural details are resolved at the atomic scale using probe-corrected high-angle annular dark-field scanning transmission microscopy. Two different epitaxial relationships at the Au/Fe interface are observed at low Au coverage, whereas only one type of interface orientation remains when the shell thickness exceeds 3 monolayers (MLs). This leads to a drastic Fe core transformation from a Wulff shaped crystal towards a nanocube. This core transformation drives a surface reconstruction resulting in a combination of open and close-packed strain free facets, offering different opportunities for molecule binding. In addition, our experiments show that the magnetic properties of the Fe core are preserved by the Au shell and that the 10 nm size of the grown nanoparticles favors a superparamagnetic behavior, suitable for biomedical applications.

Shedding X-ray Light on the Interfacial Electrochemistry of Silicon Anodes for Li-Ion Batteries.

Electrochemical alloying reactions of group IV elements, such as Si, Ge, or Sn, with lithium provide a promising route to next-generation anode materials for lithium-ion batteries (LIBs) due to their high volumetric and gravimetric capacities. However, commercialization of these anodes is still sparse owing to quick capacity fading and limited Coulombic efficiency, which arise from large volume expansion leading to particle cracking and subsequent electrochemical inactivity. As a result, the solid electrolyte interphase (SEI), originating in the decomposition of the electrolyte upon battery operation outside the electrolyte's thermodynamic stability window, grows uncontrollably. While a large number of mitigation strategies have been developed, an improved nanometer level fundamental understanding of the (de)lithiation process and SEI formation, growth, and evolution is necessary to overcome these challenges. Toward this end, many experimental and theoretical approaches have been utilized but still provide an incomplete picture. This is due to the difficulty of investigating buried interfaces and interphases of lithiation products and thin SEI layers (nanometer-scale) in situ and with the desired nanometer accuracy. In this Account, we illustrate the utilization of in situ X-ray reflectivity (XRR) to provide nanometer-scale insights on the SEI nucleation, growth, and evolution, and well as the (de)lithiation process of Si electrodes. XRR is a nondestructive and surface- and interface-sensitive technique that allows for in situ investigations during battery operation under realistic electrochemical conditions. Insight into the system is provided via the surface-normal density profile, which is interpreted in terms of thickness, density, and roughness of individual surface layers, allowing monitoring of the interfacial morphology and chemistry evolution, through which the SEI growth and Si (de)lithiation process can be resolved. We utilized a model battery anode consisting of a native oxide terminated single crystalline Si wafer in half cell configuration with standard electrolyte in a specifically designed in situ XRR electrochemical cell. We have resolved the nucleation and formation process of the inner inorganic SEI and have observed two well-defined inorganic SEI layers on Si anodes: a bottom-SEI layer (adjacent to the electrode) formed via the lithiation of the native oxide and a top-SEI layer mainly consisting of the electrolyte decomposition product, LiF. This SEI layer grows during lithiation and contracts during delithiation. Further, our results show that the lithiation of crystalline Si (c-Si) is a layer-by-layer, reaction-limited, two-phase process with a well-defined phase boundary between LixSi lithiation product and c-Si; in contrast, the delithiation of LixSi and the lithiation of amorphous Si (a-Si) are reaction-limited, single-phase processes. Moreover, we resolved the influences of current density and the Si crystallographic orientation of the reaction interface on the (de)lithiation process. The implications of our findings are discussed with regard to battery performance.

The stability, fracture toughness and electronic structure at γ-Ni (101)/(Ti, Nb)C (110) interface: A first-principles investigation

(Ti, Nb)C particles reinforced Ni45 coatings were made by a fiber laser system. The atomic structure, interfacial stability, interfacial fracture toughness, electronic structure and bonding nature of γ-Ni/(Ti, Nb)C were systematically analyzed using first principles calculations. TEM results showed that the interface orientation relationship of γ-Ni/(Ti, Nb)C was [01¯0](202)//[001¯](220). For the γ-Ni/(Ti, Nb)C interfaces, the stacking sites have much influence than the substitution position of Ti, the center-site stacking interfaces shower higher adhesion work and lower interface energy, indicating the interfacial alloying or new phases were prone to formed. According to the interfacial fracture toughness results, the mechanical failure of γ-Ni/(Ti, Nb)C may initiate at the interface or close to γ-Ni rather than (Ti, Nb)C. The bonding behavior of γ-Ni/(Ti, Nb)C was a blend of covalent bond and partial ionic bond. The chemical bonding properties of interfacial atoms were also discussed in view of electronic structure and partial density of states (PDOS) results.

Development of novel Moving Wave Front image processing algorithm and microstructural quantification of Tungsten Heavy Alloy

Tungsten Heavy Alloy (WHA) is used in various aerospace applications. This alloy has a two-phase microstructure with a contiguous matrix dispersed with nearly spherical tungsten particles. The properties of this alloy depend on microstructural parameters such as tungsten particle size, tungsten-matrix and tungsten-tungsten interface. In this work, a novel Moving Wave Front (MWF) image processing algorithm was proposed for automatic detection of the interface boundary between coalesced tungsten particles. MWF algorithm was used to measure the size and orientation of the tungsten-tungsten interface from a two-dimensional montage of backscattered Scanning Electron Microscope images. The bivariate size-orientation distribution was measured for undeformed and deformed samples. The obtained distribution in 2D was used to estimate three dimensional size-orientation distribution. The evolution of the tungsten-tungsten interface in 3D was studied as a function of thermo-mechanical deformation. A characteristic evolution of the 3D size and orientation of the tungsten-tungsten interface with deformation was observed.

Quantitative analysis of Mo solute drag effect on ferrite and bainite transformations in Fe-0.4C-0.5Mo alloy

Mo addition is widely used to retard ferrite transformation and increase hardenability of steels. It has been well recognized that Mo segregation at ferrite/austenite interface induces solute drag effect (SDE) and reduces migration rate of ferrite/austenite interface while retardation by Mo is less obvious in bainite transformation. However, element segregation, solute drag effects and its interface character dependence have not been clarified quantitatively. Therefore, in the present study, amount of Mo segregation, energy dissipation during interface migration and interface orientation relationship (OR) in ferrite and bainite transformations in Fe-0.4%C-0.5%Mo (mass%) alloy have been investigated quantitatively. Mo segregation at interfaces with non K-S OR is more significant than that at interface with near K-S OR. Amount of Mo segregation at interface with non K-S OR increases with increase in transformation time investigated while energy dissipation decreases. The amount of Mo segregation and energy dissipation measured at non K-S interface coincides well with SDE model using optimized segregation energy and interface thickness. On the other hand, energy dissipation at bainite/austenite interface is large in spite of negligibly small Mo segregation, which is inconsistent with the SDE model.

Growth of narrow substrate temperature window on the crystalline quality of InN epilayers on AlN/Si(1 1 1) substrates using RF-MOMBE

Epitaxial InN films were grown on AlN/TMAl seed layer/Si(1 1 1) substrates in the range of temperature between 500 and 540 °C using pulsed-mode RF-MOMBE. The structural properties of the InN films were characterized using X-ray diffraction (XRD), field-emission scanning electron microscopy, and transmission electron microscopy (TEM). The electrical properties were characterized by Hall effect measurements. The results indicated that small changes in temperature significantly affect the quality of InN films. The XRD and TEM results indicated that the InN films grew oriented along the c-axis. Phi-scan XRD patterns indicated that the InN films grew epitaxially on the Si(1 1 1) substrates with the orientation relationship InN [1 1 −2 0]InN//[11 0]Si. When the substrate temperature at 530 °C, the TEM images indicated three-dimensional InN/AlN growth and growth rate was approximately 0.2 μm/h. The cross-sectional TEM images and SAD pattern showed a sharp InN/AlN interface and clear epitaxial orientation relationships of InN (−2 1 1 0)InN//(−2 1 1 0)AlN//(2 –2 0)Si, [0 0 0 1]InN//[0 0 0 1]AlN//[1 1 1]Si. The electron concentrations of the InN films were measured from 5.5 × 1019 to 1.3 × 1020 cm−3, and the mobility was measured from 116 to 360 cm2/V·s. The results indicate that controlling the substrate temperature is essential for engineering the growth of InN films on silicon wafers.

Study on the Structural Parameters and Response Characteristics of the Tilted Antenna of Directional Electromagnetic Wave Resistivity Measuring Instrument

The directional logging-while-drilling measurements enable to monitor the distance to formation boundaries and their orientation and facilitate proactive well placement, and thus can provide directionality information useful in detecting physical parameters such as bed boundaries, formation dip and formation azimuth, so the oil and gas recovery can be greatly improved. The characteristics of a kind of electromagnetic wave resistivity logging while drilling (LWD) tool with tilted antennas are computed via the magnetic-current-source dyadic Green’s function for horizontally stratified anisotropic media. The current characteristic at the formation interface of the tilted antennas is compared with that of the axial antenna, and how the LWD tool with tilted antennas to detect the formation interface position and orientation is revealed. The amplitude-attenuation and phase-shift characteristics of LWD tool with tilted antennas are analyzed, and how to design the angle of tilted antenna is presented. The relationship between the emitting frequency and emitting-receiving antenna space parameters is expounded, and the emitting-receiving antenna space parameter suitable for different frequencies is presented. The detection characteristic of the electromagnetic wave measuring instrument is studied. For the highly deviated well formation model, the directional response characteristics of the different relative dip angle isotropic and anisotropic formation are numerically simulated and analyzed. The directional response characteristics of the two kinds of coil arrangement (unilateral arrangement and symmetrical arrangement) are analyzed by numerical simulation, and the solution to reduce or eliminate the influence of the directional response of the isotropy on the directional response is obtained. The conclusions obtained by theoretical analysis and numerical simulation provide a guide for the instrument principle research and application.

In Situ Visualization of Interfacial Sodium Transport and Electrochemistry between Few‐Layer Phosphorene

AbstractFor rechargeable batteries, ionic transport within the electrode materials is a critical process that controls the rate capability and energy efficiency of the battery. Despite substantial studies, the atomistic observation of the interfacial ionic transport and electrochemical reactions occurring between the solid‐state electrodes is lacking. Here, in situ transmission electron microscopy (TEM) is used to deliberately design an unusual sample configuration, enabling dynamic observation of the sodium ionic transport within a single‐crystal nanostructure and between different few‐layer phosphorene nanosheets. An unhindered and reversible ionic shuttling between few‐layer phosphorene is directly observed in real time. In addition, it is found that sodium transport kinetics are closely related to the interface orientation and the intimate contact between solid electrodes plays a significant role in inhibiting dendrite growth. Furthermore, by fast TEM imaging with ≈40 ms resolution a unique stripe‐like sodium transport behavior is observed in phosphorene, and the multiple sodium ionic transport pathways at the interfaces with atomic spatial resolution are revealed. This work may supply enlightening insights into understanding the solid–solid interfacial electrochemistry between electrode materials.

ZnCr₂O₄ Inclusions in ZnO Matrix Investigated by Probe-Corrected STEM-EELS.

The ZnCr2O4/ZnO materials system has a wide range of potential applications, for example, as a photocatalytic material for waste-water treatment and gas sensing. In this study, probe-corrected high-resolution scanning transmission electron microscopy and geometric phase analysis were utilized to study the dislocation structure and strain distribution at the interface between zinc oxide (ZnO) and embedded zinc chromium oxide (ZnCr2O4) particles. Ball-milled and dry-pressed ZnO and chromium oxide (α-Cr2O3) powder formed ZnCr2O4 inclusions in ZnO with size ~400 nm, where the interface properties depended on the interface orientation. In particular, sharp interfaces were observed for ZnO [23]/ZnCr2O4 [10] orientations, while ZnO [110]/ZnCr2O4 [112] orientations revealed an interface over several atomic layers, with a high density of dislocations. Further, monochromated electron energy-loss spectroscopy was employed to map the optical band gap of ZnCr2O4 nanoparticles in the ZnO matrix and their interface, where the average band gap of ZnCr2O4 nanoparticles was measured to be 3.84 ± 0.03 eV, in contrast to 3.22 ± 0.01 eV for the ZnO matrix.