Defect Engineering in Ambipolar Layered Materials for Mode-Regulable Nociceptor

Defect engineering represents a significant approach for atomically thick 2D semiconductor material development to explore the unique material properties and functions. Doping-induced conversion of conductive polarity is particularly beneficial for optimizing the integration of layered electronics. Here, controllable doping behavior in palladium diselenide (PdSe₂) transistor is demonstrated by manipulating its adatom-vacancy groups. The underlying mechanisms, which originate from reversible adsorption/desorption of oxygen clusters near selenide vacancy defects, are investigated systematically via their dynamic charge transfer characteristics and scanning tunneling microscope analysis. The modulated doping effect allows the PdSe₂ transistor to emulate the essential characteristics of photo nociceptor on a device level, including firing signal threshold and sensitization. Interestingly, electrostatic gating, acting as a neuromodulator, can regulate the adaptive modes in nociceptor to improve its adaptability and perceptibility to handle different danger levels. An integrated artificial nociceptor array is also designed to execute unique image processing functions, which suggests a new perspective for extension of the promise of defect engineered 2D electronics in simplified sensory systems toward use in advanced humanoid robots and artificial visual sensors.     

Corrosion of Mg alloys EV31A,WE43B,and ZE41A in chloride- and sulfate-containing solutions saturated with magnesium hydroxide

This study studied corrosion in 0.1 M Na₂SO₄, 0.1 M NaCl, and 0.6 M NaCl, all saturated with Mg(OH)₂, using weight loss, hydrogen evolution, and electrochemical measurements. Corrosion was similar in all cases. Nevertheless, the corrosion rates were alloy-dependent, were somewhat lower in 0.1 M Na₂SO₄ than in 0.1 M NaCl, and increased with NaCl concentration. The corrosion damage morphology was similar for all solutions; the extent correlated with the corrosion rate. The corrosion rates evaluated by the electrochemical methods were lower than those evaluated from hydrogen evolution, consistent with the Mg corrosion mechanism involving the unipositive Mg⁺ ion.     

Assessment of thermochemically stable apatite La10(SiO4)6O3 as electrolyte for solid oxide fuel cells

Apatite-type lanthanum silicate with a formula of La₁₀(SiO₄)₆O₃ is a potential candidate electrolyte for SOFC system because of its high ionic conductivity and low activation energy. Pure La₁₀(SiO₄)₆O₃ powder was prepared by solid state reaction and using a suitable thermal pretreatment (1000 °C/5 h) of the as-purchased La₂O₃ powder. Materials characterization, thermal behaviors, and electrical properties of La₁₀(SiO₄)₆O₃ samples were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and two-point probe DC conductivity. A pure La₁₀(SiO₄)₆O₃ pellet was prepared at the sintering process of 1600 °C and 2.5 h with a high relative sintered density of 96.91%. The existence of secondary phases in La₁₀(SiO₄)₆O₃ pellet resulted in a lower conductivity than that of pure La₁₀(SiO₄)₆O₃ pellet. Eight-hour reduction-resistant stability tests under reducing atmosphere at the elevated temperature of pure La₁₀(SiO₄)₆O₃ prepared in this study shows a good thermochemical stability as compared to the well-developed 8 mol% Y₂O₃ stabilized ZrO₂ (8YSZ).     

Ink drop filling by a slot coating die for an electrowetting display panel

Ink drops have to be filled into the square cells for an electrowetting display panel. Several ink solutions such as dodecane, tetradecane, and hexadecane were used as test liquids. These fluids have viscosities less than 4 mPas and surface tensions between 23.3 and 26 mN/m and contact angles less than 50°. A slot coating die was employed to deliver these liquids to fill up the square cells. The effects of several parameters such as coating thickness and coating speed were examined. Operating windows inside which the stable filling is possible could be found for these liquids. Several defects were observed outside the operating windows. A flow visualization technique was applied to observe the fluid motion in the coating bead region, particularly the movements of upstream and downstream menisci, the mechanism of liquid filling was discussed.     

Three-dimensional molecular dynamics study of aperture shape effect on nanojet ejection

Three-dimensional molecular dynamics (MD) simulations of nanojet ejection with different aperture shapes are reported. The simulations use the Lennard-Jones 12-6 (LJ) potential to describe the intermolecular interaction. Using non-equilibrium MD, argon nanojet ejection is simulated under vacuum conditions. According to the analysis, different aperture shapes influence the ejection processes. The ejection speeds were 23.7 and 63.2?m/s respectively in the simulation. The speed of spurting atoms in type A nanojet was slower than the other types and it became more obvious when the process time increased. The variations in velocity, density, pressure, and temperature were found with the aid of MD. The liquid temperatures were set at 50, 100, 150, and 200?K, respectively, to examine nanojet break-up characteristics. The liquid temperature inside the nanojet was found to be a factor that induce break-up. A higher temperature led to faster nanojet break-up.     

Annealing effects on the optical and morphological properties of ZnO nanorods on AZO substrate by using aqueous solution method at low temperature

Vertically aligned ZnO nanorods (NRs) on aluminum-doped zinc oxide (AZO) substrates were fabricated by a single-step aqueous solution method at low temperature. In order to optimize optical quality, the effects of annealing on optical and structural properties were investigated by scanning electron microscopy, X-ray diffraction, photoluminescence (PL), and Raman spectroscopy. We found that the annealing temperature strongly affects both the near-band-edge (NBE) and visible (defect-related) emissions. The best characteristics have been obtained by employing annealing at 400°C in air for 2 h, bringing about a sharp and intense NBE emission. The defect-related recombinations were also suppressed effectively. However, the enhancement decreases with higher annealing temperature and prolonged annealing. PL study indicates that the NBE emission is dominated by radiative recombination associated with hydrogen donors. Thus, the enhancement of NBE is due to the activation of radiative recombinations associated with hydrogen donors. On the other hand, the reduction of visible emission is mainly attributed to the annihilation of OH groups. Our results provide insight to comprehend annealing effects and an effective way to improve optical properties of low-temperature-grown ZnO NRs for future facile device applications.     

A study of the corrosion behavior of doubly-coated iron powder after compaction

Iron powder was coated with phosphate and polysiloxanes for anti-corrosion and insulation. Whether these coating layers sustain the hydraulic pressure of compaction was investigated. Electrochemical measurements were applied on the compacts comprising surface-coated iron powders to understand the performance of the coating layers undergone a series of compaction pressure. As phosphate coating was applied, the corrosion resistance was obviously enhanced; nevertheless, as the compaction pressure exceeded a threshold, the corrosion resistance dropped greatly due to the formation of cracks in the phosphate layer, suggesting the phosphate layer was brittle and could not bear high pressure. As a phosphate layer and a polymeric coating layer of amino polysiloxane were in turn applied, the corrosion resistance of the doubly-coated iron powder in the salt bath declined since the ammonium group absorbed chloride ions and deteriorated the anti-corrosion ability. After salt-fog treatment, the compacts with the grafted silane tended to form the rust layer with akaganeite phase while these without grafted silane did not, attesting that the polysiloxane did attract chloride ions. Interestingly, with the existence of polysiloxane, the cracking of the phosphate layer was effectively avoided. The polysiloxane layer could protect the underneath phosphate layer from cracking. Moreover, with the increase of compaction pressure, the corrosion resistance of the doubly-coated iron powder gradually increased due to the densification of the polysiloxane layer, which consequently hindered the chloride ions from diffusion into the surface of the iron particle.     

8-Alkylcoumarins from the Fruits of Cnidium monnieri Protect against Hydrogen Peroxide Induced Oxidative Stress Damage

Three new 8-alkylcoumarins, 7-O-methylphellodenol-B (1), 7-methoxy-8-(3-methyl-2,3-epoxy-1-oxobutyl)chromen-2-one (2), and 3′-O-methylvaginol (3), together with seven known compounds (4–10) were isolated from the fruits of Cnidium monnieri. Their structures were determined by detailed analysis of spectroscopic data and comparison with the data of known analogues. All the isolates were evaluated the cytoprotective activity by MTS cell proliferation assay and the results showed that all the three new 8-alkylcoumarins exhibited cytoprotective effect on Neuro-2a neuroblastoma cells injured by hydrogen peroxide.     

Simulation study on acoustic streaming and convective cooling in blood vessels during a high-intensity focused ultrasound thermal ablation

This study investigates the influence of blood vessels on temperature distribution during high-intensity focused ultrasound (HIFU) ablation of liver tumors. A three-dimensional acoustics-thermal-fluid coupling model is simulated to compute the temperature field in the hepatic cancerous region. The model is based on the linear Westervelt and bioheat equations as well as the non-linear Navier–Stokes equations for the liver parenchyma and blood vessels. The effect of acoustic streaming is also taken into account in the present HIFU simulation study. We found from this three-dimensional coupling study that in large blood vessel both the convective cooling and acoustic streaming can significantly change the temperature field and thermal lesion near blood vessels.     

Non-immersive Ultrasound Scanning and Inspection of Internal Defects Using a Water Droplet Coupling Device

This paper investigates a method for conducting conventional ultrasound image scanning (C-scan) in a non-immersive manner. An ultrasound coupling device is developed to couple a focusing ultrasound transducer with a sample under test through a water droplet. The transducer is immersed in a chamber filled with water. A hole-opening at the chamber’s bottom surface and a polymer film sealing the hole allow focused ultrasound to pass and reach the sample through a water droplet. An ultrasound scanning system is constructed and used for carrying out C-scan on two different samples containing pre-fabricated internal defects. By comparing the images obtained from using both conventional water immersion method and the proposed water-droplet coupling method, we demonstrate the feasibility and capability of this new type of non-immersive ultrasound image scanning method.