Crosslinked acrylic pressure‐sensitive adhesives. II. Effect of humidity on the crosslinking reaction

The effect of humidity during storage on the crosslinking reactions of isocyanate groups was investigated with attenuated total reflectance Fourier transform infrared spectroscopy with pressure‐sensitive adhesives composed of poly[ethyl acrylate‐co‐(2‐ethylhexyl acrylate)‐co‐(2‐hydroxyethyl methacrylate)] as a base resin and polyisocyanate as a crosslinker. A peak‐resolving analysis of the amide II region revealed four bands. According to an analysis of the Fourier transform infrared spectra of the model compounds, these four bands were assigned to free urethane linkages, hydrogen‐bonded urethane linkages, free urea linkages, and hydrogen‐bonded urea linkages. As expected, storage under humid conditions led to the formation of free and hydrogen‐bonded urea linkages corresponding to the promotion of isocyanate consumption. Peak resolution of the amide II region was found to be a reasonable way of monitoring urethane and urea linkages during crosslinking reactions. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3039–3045, 2003     

Reduction mechanism of tioglycolic acid on keratin fibers using microspectrophotometry and FT-Raman spectroscopy

In order to investigate the reduction mechanism of thioglycolic acid (TG) on the keratin fibers, cross-sectional samples of white human hair treated with TG were prepared. The heterogeneous reaction between TG and keratin fibers involving the diffusion of TG into human hair was analyzed at the molecular level using microspectrophotometry and FT-Raman spectroscopy. The diffusion of TG into human hair clearly increased by increasing the treatment time and by raising pH. The TG relative concentration and the disconnected relative concentration of disulfide (–SS–) groups at various depths of the hair samples with pH 9.0 were in good agreement, indicating that the reaction rate (the disconnection of –SS– groups) was faster than the diffusion rate of TG into human hair. From these experiments, we demonstrated that TG diffuses gradually beyond the cuticle region, and toward the inside of the cortex region along with the disconnection of –SS– groups.     

Suppression control method for torque vibration of three-phase HB-type stepping motor utilizing feedforward control

This paper proposes a method to reduce the vibration of the three-phase HB-type stepping motor with cogging torque by the feedforward compensation control. The compensation signal to suppress the vibration of the motor frame is obtained by the repetitive controller installing an online Fourier transformer and utilizing an acceleration sensor attached to the motor frame or an acoustic sensor such as a microphone placed close to the frame. The sensor is used only for the acquisition of the feedforward compensation data. The feedforward compensation signal at an arbitrary operating point is derived from the amplitude and phase data of the frequency components and the operating point data. Compensation data obtained by the repetitive controller is applied to the operating point changed by reference frequency and load condition in steady state. The compensation signal for the new operating point will be generated from compensation data utilizing polynomial equation approximation and linear interpolation method. The effectiveness of this proposed method is confirmed by the experimental results.     

Recovery of fluorocarbons in Japan as a measure for abating global warming

The objective of this study is to evaluate the potential for recovering fluorocarbons as measures for the abatement of global warming. In this study, we focused on the three different kinds of fluorocarbons: CFCs, HCFCs and HFCs, and targeted refrigerant use because of the availability of relevant data. We first estimated future fluorocarbon emissions from the targeted appliances; we next compared those emissions in the units of CO₂ equivalent to the level of CO₂ emissions in 1990 from a quantitative point of view. As the result of this study, it was found that fluorocarbon emissions in 1999 and 2010 would be equal to approximately 7 and 3% of the level of CO₂ emissions in 1990 respectively. Moreover, if we implement a 100% recovery rate in every recovery route, we can reduce a large amount of emissions which correspond to approximately 2–5% of the level of CO₂ emissions in 1990, even if we take into account the energy-related CO₂ emissions by the transportation and decomposition of fluorocarbons.     

Preparation of gold nanoparticles (GNP) aqueous suspensions by a new method involving Tiron

A new method is proposed to produce gold nanoparticles (GNP) by in situ reduction of a gold salt dissolved in water. The reducing agent used is Tiron instead of the citrate anion most often mentioned in literature. The influence of various parameters has been investigated, such as the content of Tiron with respect to that of the precursor of gold HAuCl₄, or the initial pH of the solution after mixing of reactants. It is shown that Tiron also exerts a positive influence as a dispersant, which impedes agglomeration of gold nanoparticles. The typical average size of GNP synthesized in the present work is close to 7 nm.     

Characteristics of a far-infrared molecular laser optically pumped by a high-power CO2 laser

A molecular far-infrared (FIR) laser optically pumped by a high-power CO₂ laser, which is a powerful source for testing detectors and mixers and for FIR spectroscopy, is constructed and the performance is examined through experiments. At frequencies between 580GHz and 4.25THz, FIR output power is more than 20～30m W by pumping power of 35～81W. Amplitude stability of ±3% is obtained at 100m W output at 2.52THz for over 30 minutes when the FIR tube is cooled at 5°C by a chiller. As an application to testing mixers, FIR laser lines up to 4.25 THz are detected by Schottky barrier diodes (SBD). Further, using a SBD, performance of absolute frequency stability at 693GHz of HCOOH oscillation is measured by harmonic mixing with a 115.5GHz millimeter wave from a phase-locked Gunn oscillator. The resultant center-frequency stability is 100kHz per 10 minutes.     

Ossifying epithelioid hemangioendothelioma

A case of small epithelioid hemangioendothelioma encapsulated by an egg-shaped bony shell composed of newly formed mature lamellar bone is presented. A nodule measuring 10 x 5 x 5 mm was excised from inside of the right cheek muscle of a 46-year-old man. Histopathologically, the nodule consisted mainly of round-to-short spindled epithelioid cells with round nuclei and occasional cytoplasmic vacuoles associated with some foci of osseous metaplasia. Characteristically, egg shell-like lamellar bone enclosed this lesion showing well-circumscribed appearance. The main component cells were immunohistochemically stained positive for factor VIII-related antigen, CD 34, UEA-1, and vimentin, and proved to be vascular endothelial cells. The term ossifying epithelioid hemangioendothelioma is proposed for this unique lesion. This type of epithelioid hemangioendothelioma has not been previously reported to our knowledge, and differentiation from ossifying fibromyxoid tumor of soft parts is considered to be important.     

Trajectory design considering derivative of jerk for head-positioning of disk drive system with mechanical vibration

In this paper, we propose a novel design method of target trajectory for high-speed and high-precision head positioning of a hard disk drive (HDD) system. To realize smooth acceleration and deceleration, the derivative of jerk is considered not to activate any mechanical vibrations. We applied the well-known optimal control theory to fix the initial and terminal conditions. Moreover, we show that various performances can be improved by introducing time-varying weighting coefficients. Some experimental results using a 2.5-in HDD are shown to verify the effectiveness of the proposed method.     

Use of a YAP1 overexpression cassette conferring specific resistance to cerulenin and cycloheximide as an efficient selectable marker in the yeast Saccharomyces cerevisiae.

Drug-resistance markers for yeast transformation are useful because they can be applied to strains without auxotrophic mutations. However, they are susceptible to technical difficulties, namely lower transformation efficiency and the appearance of drug-resistant mutants without the marker. To avoid these problems, we have constructed a phosphoglycerate kinase (PGK) promoter-driven YAP1 expression cassette, called PGKp-YAP1. Yeast cells containing PGKp-YAP1 were resistant to cycloheximide, a protein synthesis inhibitor, and also to cerulenin, a fatty acid synthesis inhibitor, but not to other drugs tested. The transformation efficiency of PGKp-YAP1 using cerulenin selection was comparable to that using a URA3 auxotrophic marker when low concentrations of cerulenin were used. Non-transformed drug-resistant colonies did appear on the low-concentration cerulenin plates. However, these non-transformed colonies could easily be identified, based on their cycloheximide sensitivity and/or their resistance to aureobasidin A to which the transformants were sensitive. Therefore, the dual drug resistance of PGKp-YAP1 could be used as an effective selection for PGKp-YAP1 recipient cells. The PGKp-YAP1 marker was used to disrupt the LYS2 gene and to transform an industrial yeast strain, indicating that this marker can be used for efficient and reliable gene manipulations in any Saccharomyces cerevisiae strain.     

Regenerating-mode low-speed operation of sensorless induction motor drive with adaptive observer

Speed estimation methods for sensorless induction motor drives can be divided into two groups. One is based on information about fundamental components of stator currents and voltages. The other is based on high-frequency components injection in stator voltages or currents. The latter may operate stably under zero frequency, which occurs in regenerating mode at low speeds. It, however, causes loss increasing and torque ripple. The former is difficult to operate under zero frequency. The authors propose a stable method categorized in the former group even in regenerating mode at low speeds. The proposed method is based on an adaptive flux observer. First, a new observer gain design is shown. Next, a method avoiding zero-frequency operation with controlling a rotor flux level is proposed.