Anion Constructor for Atomic-Scale Engineering of Antiperovskite Crystals for Electrochemical Reactions

Among the Pt group metals, Pd has been considered the most efficient for application in electrocatalysts as an alternative to Pt. Despite the comparable electrochemical activities of Pd and Pd-metal alloys, they are vulnerable to liquid acidic electrolytes, leading to degradation of catalytic activity. Pd–Ni alloys have been used to enhance catalytic activity because the electronic structure of Pd can be easily changed by adding Ni. In other studies, N atoms have been introduced for more stable M–Ni catalysts by inducing the formation of Ni₄N species; however, the structural analysis and the role of nitrogen have not been fully understood yet. Herein, the Pd–Ni alloy nitride with a unique crystal structure shows a promising catalytic activity for oxygen reduction reaction (ORR). The nitride PdNi nanoparticles have a novel monolithic antiperovskite structure of chemical formula (Pd_xNi_1−x)NNi₃. The unique antiperovskite crystal (Pd_xNi_1−x)NNi₃ possesses superior ORR activity and stability, originating from the downshifted d-band center of the monolayer Pd/antiperovskite surface and the lower formation energy of the antiperovskite core nanocrystal. Consequently, (Pd_xNi_1−x)NNi₃, as a Pt-free Pd-based electrocatalyst, overcomes the stability issue of Pd under acidic conditions by achieving 99-times higher mass activity than commercial Pd/C, as shown by the durability test.     

Tailoring of Ligand-Off Nanoparticles Inks for Thin p-Type Oxide Overlayers Formation with Maintaining Intact Halide Perovskite

In n-i-p halide perovskite solar cells (HPSCs), the development of p-type oxides is one of the most noteworthy approaches as hole transport materials (HTMs) for long-term stability and mass production. However, the deposition of oxide HTMs through a solution process over the perovskite layer without damage to the perovskite layer remains a major challenge. Here, the colloidal dispersion of ligand-off NiO nanoparticles (NPs) to form the HTM overlayer on perovskite using appropriate solvents that do not damage the underlying perovskite layer is reported. Monodispersed NiO NPs are synthesized using oleylamine (OLA) ligands via the solvothermal method, and the OLA ligands are then removed to form ligand-off NiO NPs. Based on the Hansen solubility theory, appropriate mixed solvents are found for both the dispersion of NiO NPs without ligands and coating without perovskite damage. The colloidal dispersion form a compact and uniform NiO NPs layer of 30 nm thickness on the perovskite layer, allowing n-SnO₂/Halide/p-NiO HPSCs to be successfully fabricated. The HPSC shows a record power conversion efficiency under one sun illumination for an n-i-p oxide/halide/oxide structure and excellent thermal stability maintaining 98% of the initial efficiency for 580 h under 85 °C and 10% relative humidity condition.     

Enhancement on stability criteria for linear systems with interval time-varying delays

In this paper, the problem of stability for linear systems with interval time-varying delays is investigated. By constructing a suitable augmented Lyapunov-Krasovskii functional and utilizing Wirtinger-based integral inequality, two sufficient conditions for guaranteeing the asymptotic stability of the concerned systems are derived within the framework of linear matrix inequalities (LMIs). The superiority and validity of the proposed criteria are verified by comparing maximum delay bounds under various conditions via two numerical examples.     

Effect of pre-treatment polishing on fabrication of anodic aluminum oxide using commercial aluminum alloy

Aluminum anodizing is a process in which metal is oxidized with an electrochemical method to make a metallic oxide. Because it can be used to manufacture an Anodic aluminum oxide (AAO) with dozens to hundreds of nanoscale pores that are vertically and uniformly arranged, it is widely applied in a variety of fields. In particular, most of the pre-treatment methods in the anodic oxidation processes using a high-purity aluminum adopt surface treatment through electrolyte polishing. In this study, complex polishing was performed using an abrasive film and Magnetorheological (MR) fluid for a commercial aluminum alloy to produce a uniform porous oxidized aluminum. The surface roughness and surface integrity were analyzed after each process to investigate the production behavior of AAO in relation to the pre-treatment of the surface. In addition, a study was conducted on the nano-pore production by the anodizing process in accordance with the pre-treatment polishing, in terms of the work-hardening and residual stress. Thus, in the anodic oxidation process, it was possible to generate uniform nano-pores when surface integrity including surface roughness and residual stress distribution of the aluminum alloys are excellent. Test results showed that the polishing process using the MR fluid did not generate process scratches and pits, but could effectively remove the work-hardening and compressive residual stress, proving that MR fluid polishing method is a suitable pre-treatment process to produce nano-pores in the anodizing process.

     

Microstructure and Oxidation-Resistant Property of Sol-Gel-Derived ZrO2-Y2O3 Films Prepared on Austenitic Stainless Steel Substrates

The effect of Y₂O₃ addition to the oxidation resistance of sol-gel-derived zirconia films coated on austenitic stainless steel substrates was examined. The oxidation weight gain measurement and XRD analyses of oxides showed that addition of Y₂O₃ reduces oxide formation. TEM observations revealed that the films are joined to the substrates via an amorphous layer with concentrated Si, and the layer grew thicker by adding Y₂O₃ or elevating the firing temperature. Lattice constants of the films were shown to be more expanded than the zirconia powders prepared from the coating liquids.     

Stability and Stabilization Criteria for Sampled-data Control System via Augmented Lyapunov-Krasovskii Functionals

International Journal of Control, Automation and Systems - This paper proposes improved stability and stabilization conditions for sampled-data systems. Some newly augmented Lyapunov-Krasovskii...     

Barrier reduction and current transport mechanism in Pt/n-InP Schottky diodes using atomic layer deposited ZnO interlayer

Modification of interface properties in Pt/n-InP Schottky contacts with atomic layer deposited ZnO interlayer (IL) (5 and 10 nm) has been carried out and the electrical properties were investigated using current–voltage (I–V) and capacitance–voltage (C–V) techniques. The insertion of ZnO IL in the Pt/n-InP interface reduced the effective barrier height. The barrier heights from C–V method were higher with respect to those from I–V method. The interface state density for 5 nm thick ZnO was higher than that for 10 nm thick ZnO. The barrier heights according to thermionic field emission model showed much closer to those from C–V method. Surface passivation and interfacial dipole were suggested to modulate the Schottky barrier at the Pt/ZnO/n-InP interface.

     

A New Venture Performance Model in the Korean Information and Telecommunications Industry

In this paper, we investigate on the determinants of new venture performance empirically and suggest a new venture performance model in the Korean Information and Telecommunications (IT) industry. A total of seven hypotheses is established and tested using a combination of factor analysis, cluster analysis, analysis of variance, and correlation analysis. Ninety‐two sample ventures in the Korean IT industry were investigated and analyzed to test hypotheses. We found that new ventures performance depends on their environment, strategy, internal resources factors, and, most importantly, two‐way and three‐way interactions of these factors. These findings could be interpreted as supporting the general strategy theory that when environment and internal resources are fitted, performance might be maximized and, further, strategy is the means that make internal resources and environment fit. The venture performance model presented in this paper can explain how new ventures achieve their successes. The strategic implications to the venture firms are also discussed.     

Electrochemical characteristics of electrospun La0.6Sr0.4Co0.2Fe0.8O3−δ-Gd0.1Ce0.9O1.95 cathode

The poor activity of cathode materials for electrochemical reduction of oxygen in intermediate and low temperature regime (<700 °C) is a key obstacle to reduced-temperature operation of solid oxide fuel cells (SOFCs). In our previous work, the direct methane fuel cell exhibits approximately 1 W cm⁻² at 650 °C in hydrogen atmosphere without any functional layers when the electrospun LSCF–GDC cathode was applied into the La₂Sn₂O₇–Ni–GDC anode-supported cell, which is approximately two times higher performance than 0.45 W cm⁻² of the cell with the conventional LSCF–GDC cathode. For detailed analysis of the fibrous cathode, the symmetrical cells with the electrospun and conventional LSCF–GDC cathode are fabricated, and then their electrochemical characteristics are measured by using electrochemical impedance spectroscopy (EIS). Each resistance contribution is determined by equivalent circuit consisting of a series resistance (R_s) and three arcs to describe the polarization resistance of the cathode. Total polarization resistance of the electrospun LSCF–GDC cathode is approximately two times lower than that of the conventional LSCF–GDC cathode at 650 °C, which is attributed to fibrous microstructures and large amount of pores in 100–200 nm. The results correspond to the difference in the cell performances obtained from our previous work.     

Dual lectin-based size sorting strategy to enrich targeted N-glycopeptides by asymmetrical flow field-flow fractionation: profiling lung cancer biomarkers

A dual lectin-based size sorting and simultaneous enrichment strategy for selectively isolating N-linked glycopeptides was developed using asymmetrical flow field-flow fractionation (AF4). AF4 is an elution-based method for separating biological macromolecules that has been utilized for the separation of lectin-glycopeptide complexes formed by mixing serum peptides with lectin cocktails according to the difference in diffusion coefficients. It has also been used for simultaneous depletion of nonglycosylated peptides. The dual lectin-based enrichment method was applied to proteolytic peptides from lung cancer serum samples with two lectins (WGA, GlcNAc-specific, and SNA, Sia-specific), and the whole mixture was separated by AF4. The lectin-glycopeptide complex fractions collected during AF4 separation were endoglycosidically digested with PNGase F. The resulting deamidated glycopeptides were analyzed by nanoflow liquid chromatography-electrospray ionization-tandem mass spectrometry (nLC-ESI-MS-MS) to semiquantitatively profile the N-linked glycopeptides from the sera of lung cancer patients and healthy controls. The AF4 enrichment strategy coupled with nLC-ESI-MS-MS identified 16/24 (up/down-regulated by at least 10-fold compared to normal sera) N-linked glycopeptides from a WGA complex fraction of lung cancer sera and 18/3 from a SNA fraction.