Effect of annealing on photovoltaic properties and microstructure of conventional and inverted organic solar cells using active bilayer based on liquid‐crystal semiconducting polymer and fullerene

Conventional and inverted organic solar cells of poly[9,9‐dioctyl‐fluorene‐co‐bithiophene] (F8T2) as liquid‐crystal semiconducting polymer and fullerene as electron acceptor were fabricated and characterized. An effect of thermal treatment of the films on annealing condition near glass transition was investigated for tuning optimization and improving the photovoltaic and optical properties. Annealing treatment below the glass transition improved the photovoltaic performance and carrier diffusion in crystal growth of active layer. The X‐ray diffraction patterns indicate a crystalline structure with molecular order of F8T2 in crystal index, 100 as a layer distance between sheets of F8T2 chains. The photovoltaic properties were based on molecular interactions with molecular ordering in active layer at crystal state. As the photovoltaic mechanisms, the F8T2 thin film as p‐type semiconducting polymer worked for electron‐donor layer to support light‐induced generation, carrier diffusion and charge transfer near interface in active layer. Copyright © 2014 John Wiley & Sons, Ltd.     

Structure and properties of biaxially stretched poly(ethylene terephthalate) sheets

Huge numbers of PET (poly[ethylene terephthalate]) bottles are produced in the world. Especially in Japan, the number of hot-fillable PET bottles used is extremely large and is still increasing. This type of bottle is generally manufactured by the heat-set method using hot molds after stretch-blow molding. Herein, we examined how the PET sheet stretching condition affects the PET heat-shrinkage behavior at 85°C, which is the hot-filling temperature. Sheets stretched at a higher temperature and higher speed had higher thermal stability for a wider range of draw ratios. This is because those sheets have a higher crystallinity and relaxed amorphous regions. The higher stretch speed gives the sheet a higher crystallinity with self heat generation during rapid deformation. A higher stretch temperature makes the molecular segments relaxed.     

A High-Frequency Resonant Inverter Using Current-Vector Control Scheme and Its Performance Evaluations

The authors introduce a new configuration of resonant-type high-frequency inverter having inherent fast control response of the output power and variable-voltage variable-frequency (VVVF) capability. The circuit is composed of a parallel combination of two series-resonant inverters with common input and output terminals. Both inverter units are operated at synchronous frequency and with an adjustable phase difference from 0° to 180°, allowing control of the output power from full to null power, respectively. Operation of this inverter is explained and computer-simulated operating waveforms and characteristic curves are shown in terms of normalized control variables and circuit parameters. A prototype inverter using Power MOSFET modules has been originally tested with a high-frequency induction heating and melting load to demonstrate experimentally the proposed control principle and the steady-state inverter performances under parallel tuned load conditions.     

Nondestructive Quantitative Evaluation of Porosity Volume Distribution in Aluminum Alloy Die Castings by Fractal Analysis

The nondestructive and three-dimensional quantitative evaluation of porosity in aluminum alloy die castings is proposed to identify whether the predominant cause of pore formation is shrinkage or entrapped gas. The validity of this method of evaluation was shown by comparing two different regions with different ratios of pores formed by shrinkage and gas. It was shown that the proposed evaluation can be used as a quantitative indication of porosity.     

Load-adaptive frequency tracking control implementation oftwo-phase resonant inverter for ultrasonic motor

The operating principles of newly developed ultrasonic motors (USMs) that are attractive as compact and high-torque actuators are described. A two-phase high-frequency resonant inverter for driving the USM is presented. The unique operating characteristics of the USM are examined using the inverter. Two principles of resonant frequency tracking control strategy, one concerned with a sensor interface scheme mounted on the USM and a second sensorless interface scheme based on electromechanical conversion theory, are described. These control methods are realized by analog-oriented signal processing and the PLL technique. The revolving speed control obtained by this inverter-fed USM system with two types of resonant frequency tracking control methods is illustrated and discussed using an experimental breadboard     

60-GHz-band coplanar MMIC active filters

This paper presents the design and performance of 60-GHz-band coplanar monolithic microwave integrated circuit (MMIC) active filters. To compensate for the loss of the passive filter, a resonator composed of a quarter-wavelength line is terminated by a circuit with a constant negative resistance over a wide frequency band. Cross-coupling is introduced to make the attenuation poles on both sides of the passband. We develop two types of two-stage filter: one with medium bandwidth and the other with narrow bandwidth. The former shows an insertion loss of 3.0 dB with a 3-dB bandwidth of 2.6 GHz and a rejection of larger than 20 dB at a 3-GHz separation from a center frequency of 65.0 GHz. This filter also shows a noise figure of 10.5 dB. The latter filter shows an insertion loss of 2.8 dB with a 10-dB bandwidth of 2.1 GHz at a center frequency of 65.0 GHz. It also shows an output power of 5.0 dBm at a 1-dB compression point. The loss variation due to temperature variation is successfully compensated using a gate bias control circuit. The size of the MMIC filters is 2.5 mm/spl times/1.1 mm.     

Organic–Inorganic Hybrid Hollow Nanoparticles Suppress Oxidative Stress and Repair Damaged Tissues for Treatment of Hepatic Fibrosis

Current therapeutic options for the treatment of liver fibrosis are limited, and transplantation is often the only effective option for end‐stage fibrotic diseases. To overcome this problem, a nanoparticle‐based treatment as an alternative to transplantation is developed. Multifunctional organic–inorganic hybrid hollow nanoparticles (HNPs) containing silibinin are synthesized by mixing precursors in ammonia water at 60 °C for 1 min. The HNPs are mainly composed of siloxanes and disulfides and have surface thiols. The disulfides are cleaved by intracellular glutathione and reduced to thiols, leading to the deformation of the HNPs. Silibinin molecules are released through the cracks formed by HNP deformation. Furthermore, the HNPs suppress the generation of hydroxyl radicals, a major cause of liver fibrosis, via sulfenylation reactions of HNP thiols. Retinol‐modified HNPs target Kupffer cells and hepatic stellate cells, which are essential for hepatic fibrogenesis. The combined suppression of hydroxyl radical generation and release of silibinin using the HNPs decreases the proportion of fibrotic tissues and improves hepatic function. The therapeutic efficacy is greater than can be achieved by the suppression of hydroxyl radical generation alone and the injection of silibinin alone. Thus, HNPs are promising for the treatment of liver fibrosis.