Zr(IV)?Fe(III), ?Ga(III), and ?Sn(IV) Binary Metal Complexes as Synergistic and Reusable Esterification Catalysts

Synergism in catalytic activity with the combined use of Hf(O‐i‐Pr)₄ or Zr(O‐i‐Pr)₄ and Fe(O‐i‐Pr)₃ for direct esterification and a very simple method for their extraction with ionic liquids for their recovery and reuse are described. This Zr(IV) Fe(III) complex is an environmentally benign catalyst due to its high turnover number, extremely mild Lewis acidity, low toxicity, reusability, and commercial availability at low cost.     

MDPSK-OFDM with highly power-efficient block codes forfrequency-selective fading channels

This paper investigates the performance of M-ary differential phase shift keying orthogonal frequency-division multiplexing (MDPSK-OFDM) systems employing peak power controlling block codes over frequency-selective Rayleigh fading channels. The block codes have a capability of both error correction and reduction of the peak-to-average power ratio (PAPR). To decode the block codes with reasonable complexity, the extended version of the ordered statistic decoding of Fossorier and Lin (see IEEE Trans. Inform. Theory, vol.41, p.1379-96, 1995) is utilized. The bit error rate performance of the block codes is evaluated over typical indoor radio channels by computer simulation and compared with that of the equivalent frequency diversity of the repetition codes. The significant coding gain and improvement of the irreducible error floor are observed under the constraint of the PAPR from 3 to 6 dB     

Shrinking patterns and phase coexistence of polymer gels

We have investigated the shrinking phase transition of slightly ionized poly(N-isopropylacrylamide) (NIPA) gels. The macroscopic conformation change was observed on the heating process in two different methods; a continuous heating process and an isothermal process. It was found that the macroscopic behavior can be characterized by several conformation changes, the phase coexistence (or ‘linked-dumplings’), the grain pattern, the bubble pattern, and the opaque phase. Those have correlations with the phase transition velocity. The heating conditions to determine the characteristic conformations and the stability of the phase coexistence were qualitatively discussed in terms of the classical phase separation model of nucleation and spinodal decomposition.     

Regulated plus and minus power supply using approximately 2DOF robust digital control

A plus and minus switching power supply is needed for many applications, for example an audio power supply. Since the changes in the output voltage of such loaded power amplifiers are large, the voltage of the power supply is also subject to large changes. In order to suppress these changes, a capacitor with a large capacity is usually used at the output end. If the capacities are reduced, the power supplies can be compacted. In this article, we show that the capacities can be reduced by using robust digital control using approximately 2DOF. The resulting controller is actually implemented on a digital signal processor (DSP). We show from experiments that the power supplies can be compacted by a robust controller.     

A One-Dimensional Propagation of Shock Wave Supported by Atmospheric Millimeter-Wave Plasma

A shock wave supported by an atmospheric breakdown plasma caused by a high-power millimeter-wave beam was studied. The shadow graph image in a shock tube visualized the one-dimensional shock-wave generated by the millimeter-wave breakdown in atmosphere for the first time. It was revealed that a normal shock wave propagated through the tube at the constant velocity while it was detached from the ionization front of the plasma whenever the propagation velocity of the ionization front was supersonic or subsonic. And it was visually clarified that the atmospheric millimeter-wave breakdown had the combined structure of the normal shock wave and the heating region of the millimeter-wave plasma. The measured pressure of the shock front was as equal as the normal shock which propagated at measured Mach number.     

Microwave atomic force microscope: MG63 osteoblast-like cells analysis on nanometer scale

In this paper, we report a non-invasive and non-destructive probing method for analyzing the MG63 osteoblast-like cells. High frequency microwave atomic force microscope (M-AFM) can be used to measure the surface topography and microwave image of MG63 cells simultaneously in one scanning process. Under the frequency modulation AFM mode, the M-AFM probe tip can scan above the cell surface, maintaining a constant stand-off distance and the created lateral forces were small enough as not to sweep away or deform the fragile biomolecules. By analyzing the results, quantification such as, the number and distribution of organelles and proteins of MG63 cells as well as their dimension and electrical property information can be characterized. The unique potentials of that M-AFM imaging biological substrates with no damaging manner and nanometer scale resolution, while the original structure and function of the biomolecules during the investigation are preserved, make this technique very attractive to biologists.     

Synthesis of Metal Oxide Particles Using Reaction Route from Rare-Earth Metal-EDTA Complexes

Highly dense, spherical yttria (Y₂O₃) and erbia (Er₂O₃) particles were synthesized from their corresponding metal-ethylenediaminetetraacetic (EDTA) complexes. The EDTA·Y·H and EDTA·Er·H complexes were prepared in powdered form. These complexes were used as the staring materials for synthesis of the Y₂O₃ and Er₂O₃ particles. The particles were synthesized using an H₂-O₂ flame produced with a commercial flame spray apparatus. Crystalline structure, surface and cross-sectional morphologies, and elemental distribution of the synthesized particles were investigated. It was confirmed that the crystalline phases of the Y₂O₃ and Er₂O₃ particles were homogeneous. In addition, the elemental distribution of the particles was uniform. These results indicate that dense, spherical particles of Y₂O₃ and Er₂O₃ have been synthesized with EDTA·Y·H and EDTA·Er·H complexes, respectively.     

Vibration suppression of boring bar by piezoelectric actuators and LR circuit

This paper presents the vibration suppression of a boring bar using piezoelectric actuators installed in the boring bar, and an inductor-resister (LR) circuit, which acts as a mechanical dynamic absorber. The frequency response function of the compliance was designed so that its real part is constrained to suppress regenerative chatter. The designed boring bar with an optimally tuned LR circuit was set on a lathe to evaluate its dynamic characteristic, and it was found that the chatter vibration was successfully suppressed in the cutting test.