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In this study, a resonant-type smooth impact drive mechanism (R-SIDM) actuator fabricated with lead-free piezoelectric materials was investigated. There is high demand for compact high-power actuators, and ultrasonic motors are a promising way to meet these requirements because of their high power density. The R-SIDM actuator is a type of linear ultrasonic motor that is driven with a quasi-saw-shaped displacement excited by a combination of two resonant sinusoidal waves. The advantage of the R-SIDM actuator is its low heat generation compared with that of conventional SIDM actuators because of its resonant drive operation. A previously proposed R-SIDM used a transducer composed of lead zirconate titanate (PZT), which has excellent piezoelectric properties but is harmful to the environment. Therefore, in the presently proposed R-SIDM actuator, PZT was replaced by the lead-free piezoelectric ceramic (K,Na,Li)NbO 3 (KNLN). The actuator was used to rotate a bearing rotor to measure the driving performance, and a driving speed of 53 mm/s with no load and a maximum thrust force of 69 mN were obtained.

This study verifies the effectiveness of a dynamic resonant frequency control system for transducers. This system enables the resonant frequency of the transducer to match the driving frequency. In general, the resonant frequency of an ultrasonic transducer is fixed based on its design and material properties. Therefore, it is difficult to actively control the frequency when driving the transducer. However, for high-power piezoelectric actuators, it is important to control the ratio of the fundamental and higher-order resonant frequency of the longitudinal vibration precisely at 1:2. A high-power and high mechanical quality factor (high-Q) ultrasonic transducer requires precise control of its resonant frequency. However, the resonant frequency may shift due to changes in boundary conditions or non-linear phenomena in piezoelectric vibration while driving the ultrasonic transducer. To maintain the resonant frequency ratio of the ultrasonic transducer at 1:2, we propose to dynamically control the resonant frequency ratio constant. In this study, we made two main proposals to our dynamic resonant frequency control system. One is the stepped structure of the transducer, and the other is the completely automatic control. In the stepped structure, a Langevin transducer was designed to have a resonant frequency ratio of almost 1:2 for the first and third longitudinal mode in the initial condition. Additionally, this structure could achieve control of only one of two resonant frequencies of the transducer. For the utterly automatic control system, piezoelectric elements were introduced for controlling the resonant frequency ratio precisely. For this propose, switching the electrical boundary conditions of these piezoelectric elements was carried out by MOSFETs connected to the ultrasonic transducer and control its optimum duty ratio automatically by our feedback system. This system realized dynamic control of the resonant frequency. As a result, the resonant frequency of the transducer matched the driving frequency in the frequency band from 23.23 kHz to 23.93 kHz. It was also confirmed that the shape of the excited non-sinusoidal waveform could be controlled by using resonant frequency control.

This paper proposes a wireguide-driving piezoelectric actuator for narrow space driving such as in endoscopic devices. Conventional wireguide-driving actuators use torsional or bending vibration. We examined a resonant-type smooth impact drive mechanism (R-SIDM) utilizing longitudinal vibration as the driving principle. The longitudinal vibration is resistant to outside disturbances. Different to conventional smooth impact drive mechanism (SIDM) actuators, R-SIDM actuators use the resonant effect. The quasi-saw-shaped displacement is excited by combining two resonant vibrations with a frequency ratio of 1:2. This driving principle allows lower input voltage compared to that of the conventional SIDM. As the driving source, a step-shaped Langevin transducer was fabricated. With this step-shaped design, the longitudinal resonant frequency ratio f 3 / f 1 could be adjusted to 2. At the tip of this transducer, an aluminum wireguide was attached to excite a quasi-saw-shaped vibration at the end tip. The length of the wireguide was designed to match the resonant frequencies of the transducer. It was confirmed that a bearing rotor (diameter: 10 mm) could be rotated. As we expected, a quasi-saw-shaped vibration was excited, and we could measure a non-loaded driving speed of 176 mm/s and a maximum load of 0.47 N for a 100 V p – p input voltage and a 6.0 N preload.

Background A variety of N-glycans attached to protein are known to involve in many important biological functions. Endoplasmic reticulum (ER) and Golgi localized enzymes are responsible to this template-independent glycan synthesis resulting glycoforms at each asparagine residues. The regulation mechanism such glycan synthesis remains largely unknown. Methodology/Principal Findings In order to investigate the relationship between glycan structure and protein conformation, we analyzed a glycoprotein of Drosophila melanogaster, chaoptin (Chp), which is localized in photoreceptor cells and is bound to the cell membrane via a glycosylphosphatidylinositol anchor. Detailed analysis based on mass spectrometry revealed the presence of 13 N-glycosylation sites and the composition of the glycoform at each site. The synthetic pathway of glycans was speculated from the observed glycan structures and the composition at each N-glycosylation site, where the presence of novel routes were suggested. The distribution of glycoforms on a Chp polypeptide suggested that various processing enzymes act on the exterior of Chp in the Golgi apparatus, although virtually no enzyme can gain access to the interior of the horseshoe-shaped scaffold, hence explaining the presence of longer glycans within the interior. Furthermore, analysis of Chp from a mutant (RNAi against dolichyl-phosphate α-d-mannosyltransferase), which affects N-glycan synthesis in the ER, revealed that truncated glycan structures were processed. As a result, the distribution of glycoforms was affected for the high-mannose-type glycans only, whereas other types of glycans remained similar to those observed in the control and wild-type. Conclusions/Significance These results indicate that glycan processing depends largely on the backbone structure of the parent polypeptide. The information we obtained can be applied to other members of the LRR family of proteins.

For the purpose of identification of “plate-out” matters from polyvinylchloride compound by using laser microprobe mass analyzer (LAMMA), a quartz wool sampling technique was invented for a trace amount of “plate-out” matters from a roller. Particulate matters attached to the quartz wool by scratching off from “plate-out” matters on the roller were investigated. Among di-octylphthalate, calcium stearate, zinc stearate, di-buthyl-tin-maleate and ST-210 in the compound, it was found that calcium stearate adhered preferentially on the roller from the compound.

Laser microprobe mass spectrometry (LMMS) was applied to coal fly-ash particles prefractionated to homogeneous composition with respect to particle size and density. For major elements, semiquantitative results (