A novel low‐power gate driver architecture for large 8 K 120 Hz liquid crystal display employing IGZO technology

A novel low‐power gate driver architecture was developed for large 8 K 120 Hz liquid crystal display panel. For this application, not only high‐speed driving but also low power consumption is required. We employed a high mobility In‐Ga‐Zn‐O, dual V_GL level driving method, and gate driver circuit driven by DC supply. The simulation results show that our proposals meet 8 K 120 Hz driving requirements. Also, we have fabricated a prototype panel and confirmed both high‐speed driving and low power consumption.     

Dynamic percolation phenomenon of poly(methyl methacrylate)/surface fluorinated carbon black composite

The electrical resistivity of polymer filled with conductive filler, such as carbon black (CB) particles, is greatly decreased by incorporating the conductive filler. This is called the percolation phenomenon and the critical CB concentration is called the percolation threshold concentration (Φ*). For CB particle–filled insulating polymer composite at lower than Φ*, the conductive CB network is constructed in the polymer matrix when the composite is maintained at a temperature higher than the glass‐transition temperature or the melting temperature of the polymer matrix. This phenomenon is called dynamic percolation and the time to reach the substantial decrease in resistivity is called percolation time (t_p). To investigate the relationship between the dynamic percolation process and the surface state of CB particles, we used three kinds of carbon black particles such as original carbon black (CB0) and fluorinated carbon black (FCB010 and FCB025)–filled poly(methyl methacrylate) (PMMA). It was observed that the dynamic percolation curves for CB0‐filled PMMA and FCB‐filled PMMA composites shifted to a shorter percolation time with increases in both the annealing temperature and the filler concentration. However, the dynamic percolation curves of FCB‐filled PMMA showed a gradually decreasing trend compared to that of CB0‐filled PMMA composites. The activation energy calculated from an Arrhenius plot of the t_p against the inverse of the annealing temperature was decreased by surface fluorine treatment. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1151–1155, 2003     

Structure and properties of highly stereoregular isotactic poly(methyl methacrylate) and syndiotactic poly(methyl methacrylate) blends treated with supercritical CO2

The structure and properties of highly stereoregular isotactic poly(methyl methacrylate) (it-PMMA) and syndiotactic poly(methyl methacrylate) (st-PMMA) blends with crystalline stereocomplex formed by supercritical CO₂ treatment at temperatures ranging from 35 to 130 °C were investigated by means of differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), and dynamic mechanical analysis (DMA) measurements. The melting temperature, T_m, and the heat of fusion, ΔH_m, had maximum values at about 200 °C and 25 J/g, respectively. The degree of crystallinity evaluated by WAXD ranged in value from 32 to 38%. The fringed-micellar stereocomplex crystallites were formed in case of treatment temperatures below 90 °C, and the orderliness perpendicular to the helix axis of the fringed-micellar crystallites was considered to be increased with increasing treatment temperature. In case of treatment temperature of 130 °C, the fringed-micellar crystallites and the lamellar crystallites with high orderliness parallel to the helix axis coupled with the perpendicular orderliness were formed, and the respective double endothermic peaks, T_m¹ and T_m³, were observed in DSC due to the melting of the two kinds of stereocomplex crystallites. The it-PMMA/st-PMMA blends containing the fringed-micellar crystallites maintained high values of storage modulus, E′, up to higher temperature compared with the amorphous blends. The E′ of the blend treated with CO₂ at 130 °C decreased twice at temperatures corresponding to T_m¹ and T_m³.     

ALKALINE HYDROLYSIS OF N-BUTYL ACETATE

The hydrolysis of n-butyl acetate with aqueous sodium hydroxide solution was studied in an agitated vessel with a flat interface. The observed overall reaction rates were analyzed in view of mass transfer accompanied by the (1,1)-th order irreversible reaction. The reaction kinetics and relevant physical properties were clarified.     

Application of accelerators for the research and development of scintillators

We introduce experimental systems which use accelerators to evaluate scintillation properties such as scintillation intensity, wavelength, and lifetime. A single crystal of good optical quality is often unavailable during early stages in the research and development (R&D) of new scintillator materials. Because of their beams' high excitation power and/or low penetration depth, accelerators facilitate estimation of the properties of early samples which may only be available as powders, thin films, and very small crystals. We constructed a scintillation spectrum measurement system that uses a Van de Graaff accelerator and an optical multichannel analyzer to estimate the relative scintillation intensity. In addition, we constructed a scintillation time profile measurement system that uses an electron linear accelerator and a femtosecond streak camera or a microchannel plate photomultiplier tube followed by a digital oscilloscope to determine the scintillation lifetimes. The time resolution is approximately 10 ps. The scintillation spectra or time profiles can be obtained in a significantly shorter acquisition time in comparison with that required by conventional measuring systems. The advantages of the systems described in this study can significantly promote the R&D of novel scintillator materials.     

Visualization of PWM Strategy for a Direct Matrix Converter During Input and Output Voltage Periods

This paper presents a visualization of the PWM strategy of a matrix converter during input and output voltage periods. General relations for the duty cycles based on the input current references and the output voltage references are derived. Because the input current references and the output voltage references are treated as continuous values in the time domain, the PWM strategy can be extended to the input and output voltage periods from the control period treated as constant values. At a low carrier frequency compared with the actual frequency, the PWM patterns that reduce the number of commutations for switching loss reduction can be visualized. The PWM strategy can be directly evaluated by using the waveforms of the input current and the output voltage. In the transient state with change of the output voltage reference, the output voltage and input current can be visualized. The effectiveness of the visualization of the PWM strategy has been verified by comparison with the experimental waveforms.     

Selective hydrogen generation from real biomass through hydrothermal reaction at relatively low temperatures

The effect of additives, such as an inorganic alkali and a nickel catalyst, on the hydrothermal process was examined to generate hydrogen from biomass with high selectivity at relatively low temperatures around 400 °C. At first, a cellulose sample as model biomass was subjected to the hydrothermal process at 400 °C under 25 MPa in the presence of an alkali (Na₂CO₃) and a nickel catalyst (Ni/SiO₂). The combination of these two additives led not only to highly efficient generation of hydrogen but also to effective dissolution of CO₂ into an alkaline liquid layer. Here the molar yields of gas products from the cellulose sample were compared with the equilibrium quantities obtained using a thermodynamics calculation software. Furthermore, the hydrothermal process of real biomass, such as wood chips, organic fertilizer and food waste, in the presence of both the two additives resulted in highly selective production of hydrogen even at 400 °C.     

Systematic Control of Structural Changes in GeO2 Glass Induced by Femtosecond Laser Direct Writing

We report the structural changes inside germania glass induced by femtosecond laser pulses. Inspection by polarization microscopy and secondary electron microscopy indicate that the periodic nanostructures consist of oxygen defects such as ODCs (oxygen deficient centers) and NBOHCs (nonbridging oxygen hole centers) for laser pulse energy less than 0.2 μJ. However, the glass network was dissociated and O₂ molecules were generated for laser pulse energy greater than 0.4 μJ. Two different structural changes, form‐birefringence and dissociation, were induced in GeO₂ glass, depending on the laser pulse energy. The form‐birefringence exhibited by the nanogratings in GeO₂ glass is larger than that in SiO₂ glass for pulse energy less than 0.2 μJ, as the density of nanovoids enclosed by ODCs in GeO₂ glass is higher than that in SiO₂ glass. Arrhenius plots of the phase retardation caused by the nanogratings in GeO₂ and SiO₂ indicate that the oxygen defects are relaxed at a temperature 100°C above the glass‐transition temperature.     

Modification of a hydrophobic-ligand-containing porous sheet using tri-n-octylphosphine oxide,and its adsorption/elution of bismuth ions

A neutral extractant, tri-n-octylphosphine oxide (TOPO), was used to chemically modify a porous sheet, with a final density of 1.0 mmol/g. First, glycidyl methacrylate (GMA) was graft-polymerized onto a porous polyethylene sheet with an average pore diameter, porosity, and thickness of 1.2 μm, 75%, and 2.0 mm, respectively. Second, an octadecane thiol group was introduced into the poly-GMA graft chain. Third, TOPO was deposited on the graft chain via a hydrophobic interaction. Bismuth chloride solution (BiCl₃ in 0.15 M HNO₃) was forced through the pores of the TOPO-modified porous sheet. The equilibrium binding capacity for bismuth was 0.19 mmol/g. Bismuth ions bound to TOPO were quantitatively eluted with 11 M HNO₃.