A vector control system using a neutral-point-clamped voltage-source pwm inverter

This paper describes a vector control system of an induction machine using a neutral-point-clamped voltage-source inverter (NPC-VSI) that is one of the double series-connected inverters. The NPC-VSI is able to output five-level step-shaped line-to-line voltage without output transformers or reactors, and it may reduce harmonic currents corresponding to torque ripples. However, the NPC-VSI has a problem in that excessive high voltage is applied to switching devices when a neutral point of two dc capacitors of the NPC-VSI varies from the center of the dc link voltage, because the neutral point is floating. This paper proposes also a current controller to which the space vector theory is applied. This can reduce harmonic currents to one-fourth those of a conventional voltage-source inverter using six switching devices, and regulate the neutral point potential within a preset range. To simplify the current controller, information about voltage space vectors is given from the vector controller to the current controller. The validity of the current controller is confirmed by a prototype using an induction machine of 2.2 kW.     

Water splitting reaction on a polynaphthoquinone catalyst a polynaphthoquinone-SO2-I2 system for H2O decomposition

The water splitting reaction in a polynaphthoquinone-SO₂-I₂ system under mild conditions is reported. One mole H₂O was decomposed to form 2 moles HI and 1 mole H₂SO₄ by the following two successive hydrogen transfer reactions in conjunction with the redox cycle of quinones(Q)-hydroquinones(QH₂) in the polynaphthoquinone catalyst:

$\text{2H}{}_2\text{O +SO}{}_2\text{+ Q ? QH}{}_2\text{+ H}{}_2\text{SO}{}_4\text{, QH}{}_2\text{+ I}{}_2\text{? 2HI + Q}$

The hydrogen transfer reaction from H₂O to Q was accelerated by a factor of 3–5 by light irradiation and hence this system could work also as a hybrid thermochemical cycle. When the catalytic hydrogen transfer reactions on the polynaphthoquinone are combined with the thermal decompositions of HI(2 HI ? H₂ + I₂) and H₂SO₄ ($\text{H}{}_2\text{SO}{}_4\text{? H}{}_2\text{O + SO}{}_2\text{+}\text{1}\text{2}\text{O}{}_2$), a closed water splitting cycle for the hydrogen production could be constructed. The reaction mechanism is also discussed.     

Inter-laboratory evaluation studies for establishment of notified ELISA methods for allergic substances (buckwheat)

Inter-laboratory evaluation studies were conducted for the ELISA methods for allergic substances (buckwheat). Extracts of snack, bun and udon spiked with buckwheat standard protein at a level of 5-20 ng/mL as sample solutions were analyzed in replicate at 10 laboratories. Coefficients of variation (CVs) of the ELISA methods using a Buckwheat Protein ELISA Kit (Buckwheat kit) and a FASTKIT Buckwheat ELISA kit (Buckwheat ELISA kit) were mostly below 10%. Mean recoveries of the buckwheat standard protein from the food extracts were over 40% in the two ELISA methods. Repeatability relative standard deviations of buckwheat standard protein in three food extracts were in the ranges of 6.8-78.5% and 5.0-33.9% for the Buckwheat kit and the Buckwheat ELISA kit, respectively. Reproducibility relative standard deviations of buckwheat standard protein in three food extracts were 11.9-69.5% and 16.5-34.1% for the Buckwheat kit and the Buckwheat ELISA kit, respectively. The detection limits of both ELISA methods were 1 ng/mL in sample solutions. These results suggest that the notified ELISA methods are reliable and reproducible for the inspection of buckwheat protein levels in extracts of snack, bun and udon.     

Analysis of read-out operation in 1T2C-type ferroelectric memory cell

Abstract

A 1T2C-type ferroelectric memory cell, in which two ferroelectric capacitors with the same area are connected to the gate of an usual MOSFET with a SiO₂/Si interface, was fabricated and characterized. It was found that the memory window significantly changed by the device parameters, which means that the low voltage operation is possible if we optimize these parameters. The fabricated cell, is composed of a stacked gate structure of Pt/SBT/Pt/Ti/SiO₂/Si with the area ratio of the MOS capacitor to the ferroelectric capacitor of 6 or 10. Nonvolatile memory operation was confirmed, in which the current on/off ratio was larger than 3-order-of magnitude and the data retention time was longer than 6 × 10⁴ seconds.     

Preparation and characterisation of pigments based on mica coated with rare earth oxides

Muscovite from a Brazilian natural source was beneficiated using knife mills and an ultrasound treatment. It was possible to achieve mica with a particle size of below 100 and above 45 μm and a thickness of between 0.5 and 1 μm. This product could be used for the synthesis of intensely coloured pearlescent pigments based on muscovite covered with rare earth oxides (CeO₂, PrO₂ and Ce_0.95Pr_0.05O₂). Pigments were prepared by hydrolysis and characterised by X‐ray diffraction, thermal analyses (thermogravimetric/differential thermal) and scanning electron microscopy (MeV). The colour of the resulting pigments was analysed using the CIELab method, including a pearlescence index, and it showed the following colours: mica‐CeO₂, yellow; mica‐PrO₂, black; mica‐Ce_0.95Pr_0.05O₂, orange.     

Expression and Prognostic Significance of CD47–SIRPA Macrophage Checkpoint Molecules in Colorectal Cancer

Despite the confirmed anti-cancer effects of T-cell immune checkpoint inhibitors, in colorectal cancer (CRC) they are only effective in a small subset of patients with microsatellite-unstable tumors. Thus, therapeutics targeting other types of CRCs or tumors refractory to T-cell checkpoint inhibitors are desired. The binding of aberrantly expressed CD47 on tumor cells to signal regulatory protein-alpha (SIRPA) on macrophages allows tumor cells to evade immune destruction. Based on these observations, drugs targeting the macrophage checkpoint have been developed with the expectation of anti-cancer effects against T-cell immune checkpoint inhibitor-refractory tumors. In the present study, 269 primary CRCs were evaluated immunohistochemically for CD47, SIRPA, CD68, and CD163 expression to assess their predictive utility and the applicability of CD47–SIRPA axis-modulating drugs. Thirty-five percent of the lesions (95/269) displayed CD47 expression on the cytomembrane of CRC cells. CRCs contained various numbers of tumor-associated immune cells (TAIs) with SIRPA, CD68, or CD163 expression. The log-rank test revealed that patients with CD47-positive CRCs had significantly worse survival than CD47-negative patients. Multivariate Cox hazards regression analysis identified tubular-forming histology (hazard ratio (R) = 0.23), age < 70 years (HR = 0.48), and high SIRPA-positive TAI counts (HR = 0.55) as potential favorable factors. High tumor CD47 expression (HR = 1.75), lymph node metastasis (HR = 2.26), and peritoneal metastasis (HR = 5.80) were cited as potential independent risk factors. Based on our observations, CD47–SIRPA pathway-modulating therapies may be effective in patients with CRC.     

Modeling of natural sit-to-stand movement based on minimum jerk criterion for natural-like assistance and rehabilitation

Designing a sit-to-stand (STS) assistive system that mimics the normal transfer is important for improving the quality of life for elderly and mobility impaired people while reducing the burden on the caregivers. This paper presents a robotic-based STS assisting system that can provide assistance at the shoulder and the buttock. The minimum jerk criterion is used to model the natural STS motion. Anthropometry and characteristics of the natural STS motion are used to increase the simplicity and applicability of the STS motion model. This model can generate the shoulder and hip trajectories during STS. This enables the system to provide assistance either at the upper trunk or at the upper trunk and the hip simultaneously without inducing abnormal motion kinematics. The assisting system is used to assist subjects with different heights using the trajectories generated by the proposed motion model. In addition, the proposed trajectory is compared to the one that is resulted from a commercial lifter. The results show that the proposed method can accurately replicate the natural STS motion and results in a lower interaction force. Moreover, the subjects are more satisfied when they are assisted using the proposed method as indicated by the results of the post-experiment questionnaire.     

Analysis of Gibbs monolayer adsorbed at the toluene/water interface by UV-visible partial internal reflection spectrometry

Gibbs monolayers of lipophilic tetraphenylporphyrinatomanganese(III) and hydrophilic diacid of meso-tetrakis(4-sulfonatopheny)porphyrin adsorbed at the liquid-liquid interface have been analyzed by UV-visible external reflection (ER) and partial internal reflection (PIR) spectra measured at different angles of incidence. The angle-dependent ER and PIR spectra over the Brewster angles (thetaERB and thetaIRB) have readily been measured at the toluene/water interface. As preliminarily expected in our previous study, the present study has first proved that the reflection-absorbance of UV-visible PIR spectra quantitatively agrees with the theoretical calculations for the Gibbs monolayer over thetaIRB. In addition, it has also been proved that the absorbance of the PIR spectra is greatly enhanced in comparison to that of the ATR spectra. The enhancement is caused by an optical effect in the monolayer sandwiched between two phases of toluene and water that have different but refractive indices close to each other. This optical enhancement requires an optically perfect contact between the phases, which is difficult to prepare for a solid-solid contact. At the liquid/liquid interface, however, an ideal optical contact is easily realized, which makes the enhancement as much as the theoretical expectation. The PIR spectrometry will be recognized to be a new high-sensitive analytical tool to study Gibbs monolayer at the liquid/liquid interface.     

Dynamically modified, biospecific optical fiber sensor for riboflavin binding protein based on hydrophobically associated 3-octylriboflavin.

A new approach to the production of optical fiber sensors is described which is based on a dynamic modification procedure. In this approach, the optical fiber surface is rendered hydrophobic through the covalent attachment of a C18 moiety. Specific sensing ligands are then associated with this surface through either their inherent or designed hydrophobicity. To investigate the feasibility of the approach, an optical fiber sensor has been constructed for riboflavin binding protein in which 3-octylriboflavin is associated with the fiber surface. Fluorescence quenching occurs upon binding of the protein to the immobilized riboflavin derivative. The sensor possesses a minimum measurable quantity of 7.3 pmol of binding protein in a probe volume which is less than 10 microL. With this approach, the sensing surface was repetitively regenerated 15 times over a 1-h period with less than a 5% variation in sensor-to-sensor performance. The approach is general, and with minor variations it can be used in a variety of sensing situations.