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Palladium is the most prominent material in both scientific and industrial research on gas storage, purification, detection, and catalysis due to its unique properties as a catalyst and hydrogen absorber. Advancing the dynamic optical phenomena of palladium reacting with hydrogen, transduction of the gas-matter reaction into light-matter interaction is attempted to visualize the dynamic surface chemistry and reaction behaviors. The simple geometry of the metal-dielectric-metal structure, Fabry–Perot etalon, is employed for a colorimetric reactor, to display the catalytic reaction of the exposed gas via water-film/bubble formation at the dielectric/palladium interface. The adsorption/desorption behavior and catalytic reaction of hydrogen and oxygen on the palladium surface display highly repeatable and dramatic color changes based on two distinct water formation trends: the foggy effect by water bubbles and the whiteout effect by water film formation. Simulations and experiments demonstrate the robustness of the proposed Fabry–Perot etalon as an excellent platform for monitoring the opto-physical phenomena driven by heterogeneous catalysis. [ABSTRACT FROM AUTHOR]

The explosive demand for a wide range of data processing has sparked interest towards a new logic gate platform as the existing electronic logic gates face limitations in accurate and fast computing. Accordingly, optoelectronic logic gates (OELGs) using photodiodes are of significant interest due to their broad bandwidth and fast data transmission, but complex configuration, power consumption, and low reliability issues are still inherent in these systems. Herein, we present a novel all-in-one OELG based on the bipolar spectral photoresponse characteristics of a self-powered perovskite photodetector (SPPD) having a back-to-back p+-i-n-p-p+ diode structure. Five representative logic gates ("AND", "OR", "NAND", "NOR", and "NOT") are demonstrated with only a single SPPD via the photocurrent polarity control. For practical applications, we propose a universal OELG platform of integrated 8 × 8 SPPD pixels, demonstrating the 100% accuracy in five logic gate operations irrelevant to current variation between pixels. The authors present a novel all-in-one optoelectronic logic gates based on the bipolar spectral photo-response characteristics of self-powered perovskite photodetector. Five representative logic gates are demonstrated with only a single detector via photocurrent polarity control. [ABSTRACT FROM AUTHOR]

Composite materials (CMs) based on activated carbon fiber material (ACFM) modified with oxygen-containing transition metal compounds (MnO2, Ni(OH)2, and Co(OH)2) by using colloid electrophoresis are studied. All prepared CMs have higher capacitance than the individual parental materials, with the CM ACFM-Ni(OH)2 exhibiting the maximum capacitance (~380 F g-1). Changes in the capacitances of ACFM and prepared ACFM-based CMs induced by potential cycling, the time of exposure to electrolyte solution, and potential scan rate are investigated. The capacitances of all CMs are found to increase with the number of cycles, but tend to decrease at higher potential scan rates. [ABSTRACT FROM AUTHOR]

Understanding charge transfer processes between graphene and functional materials is crucial from the perspectives of fundamental sciences and potential applications, including electronic devices, photonic devices, and sensors. In this study, we present the charge transfer behavior of graphene and amine-rich polyethyleneimine (PEI) upon CO2 exposure, which was significantly improved after introduction of hygroscopic polyethylene glycol (PEG) in humid air. By blending PEI and PEG, the number of protonated amine groups in PEI was remarkably increased in the presence of water molecules, leading to a strong electron doping effect on graphene. The presence of CO2 gas resulted in a large change in the resistance of PEI/PEG-co-functionalized graphene because of the dramatic reduction of said doping effect, reaching a maximum sensitivity of 32% at 5,000 ppm CO2 and an applied bias of 0.1 V in air with 60% relative humidity at room temperature. This charge transfer correlation will facilitate the development of portable graphene-based sensors for real-time gas detection and the extension of the applications of graphene-based electronic and photonic devices. [ABSTRACT FROM AUTHOR]

Variation of the specific capacitance of electrodes made of activated carbon-fiber material depending on the number of voltammetric cycles is studied. The specific capacitances of electrodes fabricated by different methods are measured in relation to the number of voltammetric cycles. The dependence curves of the material capacitance with reference to the time of residence in electrolyte and to the potential sweep rate are obtained. A viable explanation of the observed patterns is proposed. [ABSTRACT FROM AUTHOR]

Influence of gravel segregation on gluing solution distribution in a realistic railway ballasts is investigated numerically. The rheological characteristics of the gluing solution are accounted for by using a coupled elasto-visco-plastic stress model with an asymptotic time increasing viscosity. The realistic railway ballast is accomplished by using the vertex identification technique, in which the regulations of the gravel composition in ballast practice are followed. Specifically, a uniformly distributed one and a segregated one induced by the difference in gravel size and gravel shape are generated. The rheological model of the gluing solution and twofold ballasts are incorporated into the finite element code of ANSYS $$^{\copyright }$$ to study the flow characteristics and time-dependent solidification of the gluing solution. Relatively concrete vertical and lateral gravel-gravel adhesion in twofold ballasts can be generated by using denser network arrangement of the gluing solution; the vertical penetration in the uniform ballast is slightly deeper than that in the segregated ballast, while a slightly reverse tendency in the lateral extension near the upper and central parts appears. However, the difference in the solidified gluing solution distributions in both ballasts is essentially insignificant, indicating that the influence of the gravel segregation needs not necessary to be taken into account in gluing practice when percolation is not taken into account. [ABSTRACT FROM AUTHOR]

In this article, the properties of composites based on activated carbon-fiber material of UVIS-AK-V-240 brand and an oxygen-containing compound of transition metals (MnO, Ni(OH), Co(OH)) obtained by anaphoresis from colloidal solution containing the corresponding compounds were investigated. It was determined that composites together possessed a higher capacitance than did the initial components individually. The maximum specific capacitance was obtained on the UVIS-Ni(OН)2 composite (~370-380 F/g). For all the investigated materials, the specific capacitance increases with a decrease in the potential scan rate. It was determined that the materials obtained by the sol-gel method possess mixing and cataphoresis inferior to the value of the specific capacitance of the materials obtained by anaphoresis-by up to around four orders of magnitude, depending on the method of their obtaining. On the basis of micrographs of composite materials, it was shown that the shape, structure, and distribution of precipitate by the fiber and volume of material depend on the composition and solution concentration. [ABSTRACT FROM AUTHOR]

In this work, the effect of the synthesis conditions on exfoliated graphite and its properties was investigated. Exfoliated graphite was obtained via thermal reduction of graphite oxide at temperatures of 250-350°C. The influence of the synthesis conditions (temperature and heating rate) on the properties of exfoliated graphite (product yield, bulk density, specific surface area, specific capacitance and others) was determined via direct experimental design method. The ability to use exfoliated graphite in supercapacitors was determined on the basis of the specific capacitance data. The highest specific capacitance of exfoliated graphite was found to be 129 F/g. [ABSTRACT FROM AUTHOR]

Graphite nanoplatelets treated with nitric acid of different concentrations were studied. The initial graphite nanoplatelets were prepared by ultrasonication of exfoliated graphite. The samples were examined by scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, and FTIR and Raman spectroscopy and were tested as electrode materials for supercapacitors. [ABSTRACT FROM AUTHOR]

We present a holey titanium dioxide (TiO) film combined with a periodically aligned ZnO nanorod layer (ZNL) for maximum light utilization in dye-sensitized solar cells (DSCs). Both the holey TiO film and the ZNL were simultaneously fabricated by imprint technique with a mold having vertically aligned ZnO nanorod (NR) array, which was transferred to the TiO film after imprinting. The orientation of the transferred ZNL such as laid, tilted, and standing ZnO NRs was dependent on the pitch and height of the ZnO NRs of the mold. The photoanode composed of the holey TiO film with the ZNL synergistically utilized the sunlight due to enhanced light scattering and absorption. The best power conversion efficiency of 8.5 % was achieved from the DSC with the standing ZNL, which represented a 33 % improvement compared to the reference cell with a planar TiO. [ABSTRACT FROM AUTHOR]

The effect of conditions of electrochemical deposition of manganese oxide (overall current density, solution concentration) on physico-chemical properties of the obtained carbon-oxide composite materials (mass of deposited manganese (IV) oxide, specific capacity of the composite) is studied. Electrophoresis is used to obtain composite materials with different composition: up to 19 wt % of the MnO additive with respect to the mass of the initial activated carbon fiber. The specific capacity of the obtained composite materials is 16 to 131 F/g. [ABSTRACT FROM AUTHOR]

Graphite oxide is synthesized using various reaction parameters. Stagewise evaluation of graphite oxidation dynamics in the course of synthesis is carried out using the method of sample collection and thermogravimetric analysis. Thermally expanded graphite with high texture characteristics was obtained from graphite oxide. Properties of graphite oxide and thermally expanded graphite were determined using scanning electron microscopy, X-ray diffraction, thermogravimetry, differential scanning calorimetry, energy dispersive spectroscopy, and low-temperature adsorption of nitrogen. The values of capacity of supercapacitors based on graphite oxide and expanded graphite are found. [ABSTRACT FROM AUTHOR]

We fabricated a novel in-line conductive atomic force microscopy (C-AFM), which can analyze the resistive failures and examine process variance with an exact-positioning capability across the whole wafer scale in in-line DRAM fabrication process. Using this in-line C-AFM, we introduced a new, non-destructive diagnosis for resistive failure in mobile DRAM structures. Specially, we focused on the self-aligned contact (SAC) process, because the failure of the SAC process is one of the dominant factors that induces the degradation of yield performance, and is a physically invisible defect. We successfully suggested the accurate pass mark for resistive-failure screening in the fabrication of SAC structures and established that the cause of SAC failures is the bottom silicon oxide layer. Through the accurate pass mark for the SAC process configured by the in-line C-AFM analyses, we secured a good potential method for preventing the yield loss caused by failures in DRAM fabrication. [ABSTRACT FROM AUTHOR]

Distribution of copper in its electrodeposition from a sulfuric acid solution onto fibrous carbon electrodes with electrical conductivity varying across their thickness, the deposition rate of copper, and the current efficiency by copper were studied in relation to the electrolysis duration, electrical conductivity of the electrode, geometric current density, and solution flow rate. The main factors governing the distribution of copper across the electrode thickness and the electrolysis parameters beginning from the process onset till the 'clogging' of a part of the electrode by the metal were determined. [ABSTRACT FROM AUTHOR]

The effect of the fiber surface state of a carbon fiber fabric on the parameters of copper electro-plating from a sulfate solution (the copper current efficiency, the electroplating rate, and the deposit distribution in the depth of electrode) is studied. The surface state of fibers was changed by preliminarily polarizing the carbon fiber fabric in electrolyte solutions. The change in the specific conductivity and weight of the carbon fiber fabric, as well as the surface state of oxides and the morphology of the copper deposit, depending on the conditions of electrode polarization was studied. [ABSTRACT FROM AUTHOR]

Simulation of granular particles is an important tool in many fields. However, simulation of particles of complex shapes remains largely out of reach even in two-dimension. One of the major hurdles is the difficulty in representing particles in an efficient, flexible, and accurate manner. By representing particles as convex polyhedrons which are themselves the intersection of a set of half spaces, we develop a method that allows one to efficiently carry out key operations, including particle–particle and particle–container wall overlapping detection, precise identification of the overlapping region, particle shifting, particle rotation, and others. The simulation of packing 1,000 particles into a container takes only a few minutes with this approach. We further demonstrate the potential of this approach with a simulation that re-generates the “Brazil nut” phenomenon by mixing and shaking particles of two different sizes. [ABSTRACT FROM AUTHOR]

The order of the authors in the original version of this article was unfortunately incorrect on the first page and the first page of the ESM.Instead of Myungwoo Son1, Yusin Pak1, Sang-Soo Chee1, Francis Malar Auxilia1, Kihyeun Kim1, Byung-Kee Lee2, Sungeun Lee2, Sun Kil Kang2, Chaedeok Lee2, Jeong Soo Lee2, Ki Kang Kim3, Yun Hee Jang4, Byoung Hun Lee1, Gun-Young Jung1 (✉), and Moon-Ho Ham1 (✉)It should read Kihyeun Kim1,§, Myungwoo Son1,§, Yusin Pak1, Sang-Soo Chee1, Francis Malar Auxilia1, Byung-Kee Lee2, Sungeun Lee2, Sun Kil Kang2, Chaedeok Lee2, Jeong Soo Lee2, Ki Kang Kim3, Yun Hee Jang4, Byoung Hun Lee1, Gun-Young Jung1 (✉), and Moon-Ho Ham1 (✉) [ABSTRACT FROM AUTHOR]

Flexible In-Ga-ZnO (IGZO) thin film transistor (TFT) on a polyimide substrate is produced by employing a thermally stable SA7 organic material as the multi-functional barrier and dielectric layers. The IGZO channel layer was sputtered at Ar:O2 gas flow rate of 100:1 sccm and the fabricated TFT exhibited excellent transistor performances with a mobility of 15.67 cm2/Vs, a threshold voltage of 6.4 V and an on/off current ratio of 4.5 × 105. Further, high mechanical stability was achieved by the use of organic/inorganic stacking of dielectric and channel layers. Thus, the IGZO transistor endured unprecedented bending strain up to 3.33% at a bending radius of 1.5 mm with no significant degradation in transistor performances along with a superior reliability up to 1000 cycles. [ABSTRACT FROM AUTHOR]