Edge Plane Research Articles

Three-dimensional micro-X-ray topography using focused sheet-shaped X-ray beam

X-ray topography is a powerful method for analyzing crystal defects and strain in crystalline materials non-destructively. However, conventional X-ray topography uses simple X-ray diffraction images, which means depth information on defects and dislocations cannot be obtained. We have therefor developed a novel three-dimensional micro-X-ray topography technique (3D μ-XRT) that combines Bragg-case section topography with focused sheet-shaped X-rays. The depth resolution of the 3D μ-XRT depends mainly on the focused X-ray beam size and enables non-destructive observation of internal defects and dislocations with an accuracy on the order of 1 μm. The demonstrative observation of SiC power device chips showed that stacking faults, threading screw, threading edge, and basal plane dislocations were clearly visualized three-dimensionally with a depth accuracy of 1.3 μm. 3D μ-XRT is a promising new approach for highly sensitive and non-destructive analysis of material crystallinity in a three-dimensional manner.

Carbon nanospikes have improved sensitivity and antifouling properties for adenosine, hydrogen peroxide, and histamine.

Carbon nanospikes (CNSs) are a new nanomaterial that has enhanced surface roughness and surface oxide concentration, increasing the sensitivity for dopamine detection. However, CNS-modified electrodes (CNSMEs) have not been characterized for other neurochemicals, particularly those with higher oxidation potentials. The purpose of this study was to evaluate CNSMEs for the detection of adenosine, hydrogen peroxide (H2O2), and histamine. The sensitivity increased with CNSs, and signals at CNSMEs were about 3.3 times higher than CFMEs. Normalizing for surface area differences using background currents, CNSMEs show an increased signal of 4.8 times for adenosine, 1.5 times for H2O2, and 2 times for histamine. CNSMEs promoted the formation of secondary products for adenosine and histamine, which enables differentiation from other analytes with similar oxidation potentials. CNSs also selectively enhance the sensitivity for adenosine and histamine compared to H2O2. A scan rate test reveals that adenosine is more adsorption-controlled at CNS electrodes than CFMEs. CNSMEs are antifouling for histamine, with less fouling because the polymers formed after histamine electrooxidation do not adsorb due to an elevated number of edge planes. CNSMEs were useful for detecting each analyte applied in brain slices. Because of the hydrophilic surface compared to CFMEs, CNSMEs also have reduced biofouling when used in tissue. Therefore, CNSMEs are useful for tissue measurements of adenosine, hydrogen peroxide, and histamine with high selectivity and low fouling.

On the modelling of ground-board mounted microphones for outdoor noise measurements

This paper presents a boundary element method for calculating the sound pressure level on and above a ground-board placed on an infinite ground plane with constant impedance. This method uses the Green's function for the Helmholtz equation in a half-space bounded by an infinite impedance plane and therefore avoids the complications which occur when modeling the ground as a finite impedance plane (which results in diffraction from the edges of the ground plane). Two formulations are presented: the first one models a finite thickness ground-board, whilst the second one models a zero-thickness ground-board with the upper surface coplanar with the ground plane. The method is validated against an equivalent finite element method simulation and example calculations are presented for typical ground-board designs used for outdoor noise measurements on different ground impedance planes and incidence angles. It is shown that the sound pressure level on the upper surface of a ground-board placed on a non-rigid ground can vary significantly and that this variation is dependant on the ground impedance, angle of incidence and frequency. These findings are consistent with previous investigations and highlight the fact that noise measurements made using ground-board mounted microphones on a non-rigid ground are dependant on the impedance of the surrounding ground surface. The method presented in this paper could be used to develop corrections to straightforwardly account for this effect.

Three patterns for identifying the posterior plane of a lenticule during SMILE

PurposeTo describe three patterns of posterior plane edge identification in small-incision lenticule extraction and to prevent lenticule mis-dissection.MethodsFemtosecond laser application was performed for small-incision lenticule extraction (SMILE) by one surgeon. The surgical videos of SMILE were recorded and re-watched by the surgeon after operation.ResultsSmall-incision lenticule extraction was performed in 52 eyes of 28 patients, and no patient had cap-lenticular adhesion. Three patterns of posterior plane of lenticule were noticed when the surgical videos were re-watched. A “double lines” attached to the dissector were visible, signifying the reflective tape of the edge of the lenticule and the cap. During the expansion of the posterior lamellar separation, a fusiform opening between the lenticule edge and the underlying matrix layer was assumed to be a “leaf sign.” With some unintentional operation, the posterior lamella was pushed away from the surgeon. The edge of the lenticule away from the anatomical part, the marking of the femtosecond laser cut, and the edge of the cap layer showed three reflective bands, which formed a “triple lines.” The “double lines,” “leaf sign,” and “triple lines” were observed in 30 eyes (57.7%), 21 eyes (40.4%), and 1 eye (1.9%), respectively.ConclusionThese three signs cover possible situations and provide visual landmarks to identify the correct dissection of the posterior plane, which can help shorten the learning curve of novice doctors.

Differential depression of calcium lignosulfonate on chalcopyrite and molybdenite flotation with collector kerosene

Molybdenite is the main mineral for molybdenum extraction, which coexists with chalcopyrite in porphyry copper deposits. However, the separation of molybdenite from chalcopyrite by flotation uses large amounts of toxic depressants, causing financial, health and environmental concerns. In this study, an environmentally friendly depressant, calcium lignosulfonate, with a low price was explored to depress chalcopyrite in the presence of kerosene, a collector widely used to float molybdenite. Adsorption isotherms of calcium lignosulfonate on chalcopyrite and molybdenite surfaces and contact angles of chalcopyrite, molybdenite’s basal planes and edge planes in the absence and presence of calcium lignosulfonate and kerosene were determined to understand the adsorptions of calcium lignosulfonate on heterogeneous chalcopyrite and molybdenite surfaces and the subsequent interactions with kerosene. It was found that calcium lignosulfonate effectively depressed chalcopyrite flotation, but had little depression effect on molybdenite because the adsorption density of calcium lignosulfonate on chalcopyrite was significantly higher than that on molybdenite. Calcium lignosulfonate molecules were uniformly adsorbed on chalcopyrite and molybdenite despite the heterogeneous surfaces. In fact, calcium lignosulfonate adsorbed on polar metal ion sites of chalcopyrite surfaces, blocking the adsorption of kerosene from adsorbing on hydrophobic sulphur-rich phases. Analogously, calcium lignosulfonate adsorbed on polar edge planes of molybdenite with little interference with the adsorption of kerosene on hydrophobic basal planes.

A Theoretical and Experimental Square-Wave Voltammetric Study of Ascorbic Acid in Light of Multi-Step Electron Transfer Mechanism

A detailed theoretical and experimental study of the complex redox mechanism of ascorbic acid in aqueous phosphate buffer solution (pH = 7.3) by square-wave voltammetry is presented. Experimental square-wave voltammograms at edge plane pyrolytic graphite electrode consist of a typical irreversible peak for a direct two-step electrode oxidation of the ascorbic acid. The complex mechanism of oxidation of the ascorbic acid was represented by a theoretical model for E1C’E2C mechanism. Morphology of theoretical square-wave voltammograms greatly depended on different specific parameters of the model. This feature was used to make the best fit between experimental and theoretical voltammograms for 2 different step potentials, which resulted in revelation of all specific parameters (standard electrochemical rate constant, diffusion coefficient, electron transfer coefficient and rate constants for both chemical reactions) of the model. Therefore, we showed that using only square-wave voltammetry, both experimentally and theoretically, it is possible to make a detailed study of the complex oxidation of ascorbic acid and further enlighten its redox mechanism.

Square-wave voltammetry of human blood serum

A study on voltammetric analysis of blood serum diluted in a phosphate buffer is presented using advanced square-wave voltammetry at an edge plane pyrolytic graphite electrode. The results demonstrate that even in a complex medium like human blood serum, electrochemical characterization can be achieved through the use of advanced voltammetric techniques in conjunction with an appropriate commercially available electrode, such as the edge plane pyrolytic graphite electrode, which boosts superior electrocatalytic properties. Without undergoing any chemical treatment of the serum sample, the square-wave voltammetry technique reveals, for the first time, the electrode reactions of uric acid, bilirubin, and albumin in a single experiment, as represented by well-defined, separated, and intense voltammetric signals. All electrode processes are surface-confined, indicating that the edge plane sites of the electrode serve as an ideal platform for the competitive adsorption of electroactive species, despite the extensive chemical complexity of the serum samples. The speed and differential nature of square-wave voltammetry are crucial for obtaining an outstanding resolution of the voltammetric peaks, maintaining the quasi-reversible nature of the underlying electrode processes, while reducing the impact of follow-up chemical reactions that are coupled to the initial electron transfer for all three detected species, and minimizing fouling of the electrode surface.

Nonlinear compression behavior research of molded pulp material

The molded pulp material is a popular environmentally friendly material, and many countries are strengthening its application in packaging. This paper aims at the molded pulp material’s mechanical properties. A compression test, which fits the actual work conditions is applied. And then use the standard linear solid (SLS) model to analyze the properties. The results show that the mechanical properties of molded pulp material are significantly different between the surface plane and the side plane, due to the layered distribution of the fibers. In the SLS model curve fitting results, the stiffness of the parallel spring element under edge plane load is significantly greater than that under surface plane load. This indicates long-term stable loads are more suitable for materials designed with loads parallel to the surface, the dynamic vibration energy needs to be designed on the material’s surface.

Raman Spectroscopy of the Trapezoidal Bi2O2Se

AbstractThe 2D Bi2O2Se has recently attracted significant interest with large Hall mobility at low temperature due to the depressed electron–phonon scattering. However, the phonon properties of Bi2O2Se are not well explored, and some Raman modes are under debate. Here, substrate engineering is used to grow an unexplored trapezoidal Bi2O2Se, which facilitates the Raman measurements in different orientation planes. Two additional Raman modes at 55 and 429 cm−1 are detected on the slope of the trapezoid besides the 159 and 362 cm−1 modes found on the top plane of the trapezoidal Bi2O2Se. Based on the polarized Raman spectroscopy, density functional theory calculations, and group theory analysis, the Raman modes of 55, 159, 362, and 429 cm−1 are assigned to the Eg, A1g, B1g, and Eg modes, respectively. There are two distinct types of angle‐resolved polarized Raman spectroscopy for the A1g mode on the top and edge planes of Bi2O2Se, which can be used to determine the crystal orientation unambiguously. Furthermore, strong thermal anisotropy is found in the top and edge planes of trapezoidal Bi2O2Se, as reflected from the first‐order temperature coefficient of A1g phonon mode. The novel growth strategy and interesting anisotropic phonon properties may open up potential applications of Bi2O2Se in nanoelectronics.

Ultrafine NiFe-Based (Oxy)Hydroxide Nanosheet Arrays with Rich Edge Planes and Superhydrophilic-Superaerophobic Characteristics for Oxygen Evolution Reaction.

NiFe-based (oxy)hydroxides are the benchmark catalysts for the oxygen evolution reaction (OER) in alkaline medium, however, it is still challenging to control their structures and compositions. Herein, molybdates (NiFe(MoO4 )x ) are applied as unique precursors to synthesize ultrafine Mo modified NiFeOx Hy (oxy)hydroxide nanosheet arrays. The electrochemical activation process enables the molybdate ions (MoO4 2- ) in the precursors gradually dissolve, and at the same time, hydroxide ions (OH- ) in the electrolyte diffuse into the precursor and react with Ni2+ and Fe3+ ions in confined space to produce ultrafine NiFeOx Hy (oxy)hydroxides nanosheets (<10nm), which are densely arranged into microporous arrays and maintain the rod-like morphology of the precursor. Such dense ultrafine nanosheet arrays produce rich edge planes on the surface of NiFeOx Hy (oxy)hydroxides to expose more active sites. More importantly, the capillary phenomenon of microporous structures and hydrophilic hydroxyl groups induce the superhydrophilicity and the rough surface produces the superaerophobic characteristic for bubbles. With these advantages, the optimized catalyst exhibits excellent performance for OER, with a small overpotential of 182mV at 10mA cm-2 and long-term stability (200h) at 200mA cm-2 . Theoretical calculations show that the modification of Mo enhances the electron delocalization and optimizes the adsorption of intermediates.

Detection and effects of lack of fusion defects in Hastelloy X manufactured by laser powder bed fusion

Laser Powder Bed Fusion (L-PBF) is increasingly used for the manufacturing of complex metal parts. A major hurdle for L-PBF to manufacture critical parts is the lack of knowledge about the effects of inner material defects on the material properties. This paper presents a new method to manufacture specimens with inner lack of fusion (LOF) defects and to detect and localize them simultaneously by the in-process monitoring tool Optical Tomography (OT). The presence of defects at locations indicated by OT was verified through Computed Tomography analyses. Correlative metallographic preparation of the processed specimens showed LOF defects with their main extent within the build plane and sharp edges. Moreover, microstructural investigations revealed a fine globular grain structure and coarse dendritic segregations in the area, influenced by the defect. Correlations between the LOF defects analyzed in the microstructure and corresponding OT indications were established. Tensile tests and high cycle fatigue tests were performed on defective and non-defective material to evaluate the effects of LOF defects on the material properties of Hastelloy® X manufactured by L-PBF. While a minor influence of the LOF defects on static material properties was identified, the fatigue life of the defective specimens was significantly reduced.

Macro-superlubricity in sputtered MoS2-based films by decreasing edge pinning effect

AbstractTo date, MoS2 can only be achieved at microscale. Edge pinning effect caused by structure defects is the most obvious barrier to expand the size of structural superlubricity to macroscale. Herein, we plan to pin edge planes of MoS2 with nanospheres, and then the incommensurate structure can be formed between adjacent rolling nanoparticles to reduce friction. The sputtered MoS2 film was prepared by the physical vapor deposition (PVD) in advance. Then enough Cu2O nanospheres (∼40 nm) were generated in situ at the edge plane of MoS2 layers by liquid phase synthesis. An incommensurate structure (mismatch angle (θ) = 8°) caused by MoS2 layers was formed before friction. The friction coefficient of the films (5 N, 1,000 r/min) was ∼6.0×10−3 at the most. During friction, MoS2 layers pinned on numerous of Cu2O nanoparticles reduced its edge pinning effect and decreased friction. Moreover, much more incommensurate was formed, developing macro-superlubricity.

Compact dual-band MIMO monopole dual-antenna system for 5G laptops

AbstractThe study aimed to present a dual-band 5G multi-input multi-output monopole dual-antenna system, which was configured on the upper edge of the display ground plane for laptops. The dual-antenna unit is a 29 × 2 × 3 mm3three-dimensional structure with two antennas of the same structure and size, consisting of a fed monopole antenna and a shorted monopole antenna. The antennas are arranged 4 mm apart, side by side in the same direction, to form a dual-antenna unit. Such a configuration allows the feeding points of the two antennas to be separated by the shorting point of the shorted monopole antenna, and the shorting point of the low-frequency resonant path (the shorted monopole antenna) of the two antennas to be larger than a quarter of the wavelength of the low frequency with appropriate bending. The strong current will be concentrated near the shorting point of the shorted monopole antenna when the low-frequency mode is excited, and the current flow from the ground to the feeding point of the other antenna will be reduced, achieving the isolation which is better than 10 dB in measurement between the two antennas without adopting any isolation element. The envelope correlation coefficients calculated from the measured complex E-field radiation patterns are all smaller than 0.12, which can cover the 5G dual-band operations of 3300–3600 and 4800–5000 MHz, and the measured antenna efficiencies can reach more than 40%, which are well suited for multiple antenna applications.

Evaluation of RETRO-Mapping for electrophysiological features including direction of plane activity during atrial fibrillation using multipolar catheters in humans.

A quantifiable, automated standard of analyzing heart rhythm has long eluded cardiologists due, in part, to the limitations in technology and the ability to analyze large electrogram datasets. In this proof-of-concept study, we propose new measures to quantify plane activity in atrial fibrillation (AF) using our Representation of Electrical Tracking of Origin (RETRO)-Mapping software. We recorded 30 s segments of electrograms at the lower posterior wall of the left atrium using a 20-pole double loop catheter (AFocusII). The data were analyzed with the custom RETRO-Mapping algorithm in MATLAB. Thirty secondsegments were analyzed for number of activation edges, conduction velocity (CV), cycle length (CL), activation edge direction, and wavefront direction. These features were compared across 34 613 plane edges in three types of AF: persistent AF treated with amiodarone (11 906 wavefronts), persistent AF without amiodarone (14 959 wavefronts), and paroxysmal AF (7748 wavefronts). Change in activation edge direction between subsequent frames and change in overall wavefront direction between subsequent wavefronts were analyzed. All activation edge directions were represented across the lower posterior wall. The median change in activation edge direction followed a linear pattern for all three types of AF with R2 = 0.932 for persistent AF treated without amiodarone, R2 = 0.942 for paroxysmal AF, and R2 = 0.958 for persistent AF treated with amiodarone. All medians and the standard deviation error bars remained below 45° (suggesting all activation edges were traveling within a 90° sector, a criterion for plane activity). The directions of approximately half of all wavefronts (56.1% for persistent without amiodarone, 51.8% for paroxysmal, 48.8% for persistent with amiodarone) were predictive of the directions of the subsequent wavefront. RETRO-Mapping can measure electrophysiological features of activation activity and this proof-of-concept study suggests that this can be extended to the detection of plane activity in three types of AF. Wavefront direction may have a role in future work for predicting plane activity. For this study, we focused more on the ability of the algorithm to detect plane activity and less the differences between the types of AF. Future work should be in validating these results with a larger data set and comparing with other types of activation such as rotational, collision, and focal. Ultimately, this work can be implemented in real-time for prediction of wavefronts during ablation procedures.

Wet-Spun Porous Carbon Microfibers for Enhanced Electrochemical Detection.

We present a novel copolymer-based, uniform porous carbon microfiber (PCMF) formed via wet-spinning for significantly improved electrochemical detection. Carbon fiber (CF), fabricated from a polyacrylonitrile (PAN) precursor, is commonly used in batteries or for electrochemical detection of neurochemicals due to its biplanar geometry and desirable edge plane sites with high surface free energy and defects for enhanced analyte interactions. Recently, the presence of pores within carbon materials has presented interesting electrochemistry leading to detection improvements; however, there is currently no method to uniformly create pores on a carbon microfiber surface impacting a broad range of electrochemical applications. Here, we synthesized controllable porous carbon fibers from a spinning dope of the copolymers PAN and poly(methyl methacrylate) (PMMA) in dimethylformamide via wet spinning for the first time. PMMA serves as a sacrificial block introducing macropores of increased edge-plane character on the fiber. Methods were optimized to produce porous CFs at similar dimensions to traditional CF. We prove that an increase in porosity enhances the degree of disorder on the surface, resulting in significantly improved detection capabilities with fast-scan cyclic voltammetry. Local trapping of analytes at porous geometries enables electrochemical reversibility with improved sensitivity, linear range of detection, and measurement temporal resolution. Overall, we demonstrate the utility of a copolymer synthetic method for PCMF fabrication, providing a stable, controlled macroporous fiber framework with enhanced edge plane character. This work will significantly advance fundamental investigations of how pores and edge plane sites influence electrochemical detection.

Environmental effects on nanoscale friction at graphite basal plane and step edge

Graphite is typically regarded as a good solid lubricant, but its effectiveness as a lubricant can vary depending on environmental conditions. Since macroscopic contact with graphite involves both basal planes and step edges of micro- or nano-crystalline particulates, it is critical to understand their individual contributions to the environment-dependent friction. To that end, this study used atomic force microscopy with a Si probe to investigate the effect of adsorption of water and n-pentanol from the gas phase on the nanoscale friction of the basal plane and step edge of graphite. The results showed that as the ambient humidity increases, friction on the basal plane increases monotonically, while friction at the step edge first increases and then decreases. Additionally, when n-pentanol is adsorbed, the friction of both basal plane and step edge decreases. These findings could be correlated with the isotherm and structure of the adsorbed molecules in the sliding interface, which alters the degree of commensurate interactions between the probe and the basal plane, as well as the transient chemical interactions between the probe and the step edge.

Nanoarchitecture factors of solid electrolyte interphase formation via 3D nano-rheology microscopy and surface force-distance spectroscopy

The solid electrolyte interphase in rechargeable Li-ion batteries, its dynamics and, significantly, its nanoscale structure and composition, hold clues to high-performing and safe energy storage. Unfortunately, knowledge of solid electrolyte interphase formation is limited due to the lack of in situ nano-characterization tools for probing solid-liquid interfaces. Here, we link electrochemical atomic force microscopy, three-dimensional nano-rheology microscopy and surface force-distance spectroscopy, to study, in situ and operando, the dynamic formation of the solid electrolyte interphase starting from a few 0.1 nm thick electrical double layer to the full three-dimensional nanostructured solid electrolyte interphase on the typical graphite basal and edge planes in a Li-ion battery negative electrode. By probing the arrangement of solvent molecules and ions within the electric double layer and quantifying the three-dimensional mechanical property distribution of organic and inorganic components in the as-formed solid electrolyte interphase layer, we reveal the nanoarchitecture factors and atomistic picture of initial solid electrolyte interphase formation on graphite-based negative electrodes in strongly and weakly solvating electrolytes.

Compact Sub 6 GHz Slot Multiantenna System for 5G Laptops

A sub 6 GHz dual-band closed-slot multiantenna system for 5G laptops is proposed in this paper. It was installed in a clearance space, with dimensions og 217 × 3 mm2 and 1 mm away from the upper edge of the screen ground plane. The dimensions of the clearance space were the same as those of a multisystem consisting of six antennas. The dimensions of the single closed-slot antenna were 32 × 3 mm2 (0.368 λ × 0.034 λ, where λ equals the free-space wavelength of 3450 MHz. The antenna was coupled to an asymmetric T-shaped feed-in section equipped with a chip capacitor for exciting one-half and full wavelength resonance modes of the closed-slot to encompass sub 6 GHz 3300-3600 MHz and 4800-5000 MHz dual-band operations. The design of the antenna features a long and straight slot to generate the high-order mode of the closed slot in the high-frequency (4800-5000 MHz) band (not the low-frequency (3300-3600 MHz) multiplier band). Its structure is simple, and the width of its slot is only 3 mm. The antennas were arranged to be 5 mm apart in the same direction and in parallel to form a six-antenna system in order to utilize the weak electric fields located at the two closed ends of the closed-slot structure when the closed slot was excited. It showed excellent envelope correlation coefficients (ECCs) and isolation performance without the installation of isolation elements. The measured fractional bandwidth of the antenna was 10.15% and 6.73% at the center frequencies of 3450 MHz and 4900 MHz, respectively. Its measured isolation was always over 10 dB, and the efficiency was between 46% and 76%. The ECCs of the system calculated from the measured complex E-field radiation pattern were all below 0.2, which means that it is ideal for use in laptop devices with a high screen-to-body ratio and a metal back cover.

“Edge/Basal Plane Half-Reaction Separation” Mechanism of Two-Dimensional Materials for Photocatalytic Water Splitting

Two-dimensional (2D) materials are long considered as potential candidates for photocatalytic water splitting, but their applications are limited by high electron–hole recombination probability, low solar-to-hydrogen (STH) efficiencies, or “catalyst poisoning” issues. Herein, we propose an “edge/basal plane half-reaction separation” mechanism of 2D photocatalysts for water splitting with superior photocatalytic efficiency. As a proof-of-concept, we design a group of stable and potentially exfoliable 2D rhodium chalcogenide halide (RhXY, X = S, Se, Te; Y = Cl, Br, I) photocatalysts with band gap values from 1.93 to 2.71 eV and suitable band edges. The half-reactions for photocatalytic water splitting, i.e., hydrogen/oxygen evolution reaction (HER/OER), prefer to happen on the edge and basal planes of RhXY, respectively, and RhSCl, RhSeCl, and RhSeBr can also trigger HER and OER simultaneously without sacrificial reagents or cocatalysts. This work paves the way for the rational design of 2D photocatalysts with spatially separated half-reactions.

Decoupling Technique Based on Field Distribution on Ground Plane for WLAN MIMO Antenna Applications

An efficiently-decoupling method for multiple-input multiple-output (MIMO) antenna systems is proposed in this paper. A planar-modified monopole antenna operating at the WLAN band is chosen as the antenna unit. The antenna structure is based on the printed circuit board technique. By observing and analyzing the ground plane’s field distribution generated by high-order modes, it is found that several stable minimum current points can be excited along the edges of the ground plane. In doing so, a high isolation can be obtained if the other antenna is placed at one of these points. The measured results and simulated results have a good agreement with each other, which well validates the proposed design concept. In addition, compared with the traditional decoupling technology, this method can improve the isolation between antennas without adding additional structures, which has excellent practicality in wireless communication system applications.