Liquid-Liquid-Gas Triphasic Hydrogenation of Bicarbonate to Formate in a Continuous Flow Tubular Reactor

Multiphasic reaction of bicarbonate hydrogenation to form formate using homogeneous Ru PNP pincer catalyst in a continuous flow tubular reactor is reported. The reaction system consists of three phases. Catalyst is dissolved in toluene while potassium bicarbonate is dissolved in water. The significance of efficient mixing among the organic phase, aqueous phase and gaseous hydrogen to improve hydrogenation reaction by using different inert packing materials is studied by operando visualization and also quantitatively discussed. The bicarbonate conversion of up to 67% is achieved after optimization of important reaction and reactor parameters. The designed reactor setup comprised of effective recycling system that recycles the catalyst with >99% activity.     

Control and Performance of a Transformerless Cascade PWM STATCOM With Star Configuration

This paper presents a three-phase transformerless cascade pulsewidth-modulation (PWM) static synchronous compensator (STATCOM) intended for installation on industrial and utility power distribution systems. It proposes a control algorithm that devotes itself not only to meeting the demand of reactive power but also to voltage balancing of multiple galvanically isolated and floating dc capacitors. The control algorithm based on a phase-shifted carrier modulation strategy is prominent in having no restriction on the cascade number. Experimental waveforms verify that a 200-V 10-kVA cascade PWM STATCOM with star configuration has the capability of inductive to capacitive (or capacitive to inductive) operation at the rated reactive power of 10 kVA within 20 ms while keeping the nine dc mean voltages controlled and balanced even during the transient state.     

Utilization of oxygen flask combustion method for the determination of mercury and sulfur in coal

By use of oxygen flask combustion (OFC), a rapid and convenient determination method for mercury (Hg) and sulfur (S) in coal was developed. For the determination of Hg in coal, the OFC method with a KMnO₄ solution as an absorbent was carried out, and the resulting solution was analyzed by cold vapor atomic fluorescence spectrometry (CVAFS). For six certified reference material coals, the Hg concentrations obtained by this method were in good accordance with the certified or reference values. In addition, nine brands of Japanese standard coals (SS coals) were analyzed by the present method, and the data were compared to those from the authentic microwave-acid digestion (MW-AD) method. For the determination of total S in coal, the OFC method with H₂O₂ solution as an absorbent followed by ICP-AES or precipitation titration was successfully applied.     

Viscoelastic properties of polystyrene–poly(vinyl methyl ether) blends in oscillatory and steady shear flows near the phase separation temperature

Viscoelastic properties of a polystyrene-poly(vinyl methyl ether) blend were measured in oscillatory and steady shear flows near the phase separation temperature. In the one-phase region, the viscoelastic properties are independent of the type of flow and flow geometry, and their shear and frequency dependences are the same as those of homopolymers. When phase separation occurred, a change in viscoelastic properties was observed in all types of flow and flow geometries, and they are different in the different types of flow and/or different flow geometries in the two-phase region. In the shear rate dependence of viscosity of the polymer blend in the two-phase region at quiescence, a plateau region was observed, in which the shear viscosity can be regarded as the zero shear viscosity of the homogenized polymer blend at that temperature.     

Harmonic power detection based on the pq theory and its applications

Harmonic interference problems generated by bulk semiconductor power converters become more serious in power systems with their wide use in industrial applications. Shunt passive filters consisting of LC tuned filters or shunt active filters using PWM inverters have been used to suppress harmonic currents in distribution systems. To install the passive or active filters, it is necessary to find exactly a dominant harmonic source in distribution feeders. A harmonic power on each phase and order at a receiving terminal has been investigated by using a digital power meter including an FFT analyzer. However, the conventional detection method has a problem in that it is difficult to discuss exactly harmonic power flow because the detected harmonic power is much smaller compared with a fundamental active power at the receiving terminal. In this paper, the harmonic power in three phases, which can be detected on real time, is defined by applying the pq theory. Next, it is verified by a digital simulation that the proposed method can discuss harmonic flows more easily than the conventional method. As a result, it is more simple and precise to find the harmonic source. Moreover, measurement errors of the harmonic power are revealed quantitatively, and the validity of the proposed method is demonstrated by digital simulation.     

Evaluation of biological responses to polymeric biomaterials by RT-PCR analysis III: study of HSP 70, 90 and 47 mRNA expression

In this study, in order to analyze how cells recognize biomaterials, mRNA was evaluated on various substrates as shown in the attached HeLa S3 cells. The expressed Heat-Shock Protein (HSP) 70A, 70B, 90 and 47 mRNA were isolated and detected using the RT-PCR method. As a result, 70B, 90 and 47 mRNA expressions varied with differences in the hydrophilicity hydrophobicity of the substrates. HSP mRNAs outcome was induced significantly in the HeLa S3 cells that had adhered onto the hydrophilic surfaces. On the other hand, in the cells that had adhered to the hydrophobic surfaces, HSP mRNAs expressions were low. In the non-adhered HeLa S3 cells the tendency found in HSP 70B and HSP 47 mRNA's expressions was the same as that found in adhered cells, while there were no significant differences in the HSP 90 mRNA expression among either of the samples. We have concluded that HSP mRNAs expression is an important marker in the study of cell-polymer interactions.     

Electronic States of Natural and Metal-ion Doped DNA

Electronic states of pristine and metal ion doped salmon DNA’s are studied with EPR and SQUID. Intrinsically no EPR signal is observed in purified salmon DNA, consistent with a semiconducting nature of the pristine DNA, but inconsistent with a metal or a superconductor as reported previously. Although we obtained successfully the divalent metal ion-DNA complexes with one-dimensional array of ions located in between the bases of a base pair, substantial EPR signal except for the case of 3d transition metal ions is not observed. This leads to the conclusion that divalent metal ions counterbalances two phosphate anions instead of Na counter ions in B-DNA, which contradicts the metallic behavior reported previously (A. Rakitin, et al., PRL 86, 3670 (2001)). A comment will also be given on the recent report: “Intrinsic Low Temperature Paramagnetism in B-DNA” (S. Nakamae et al., PRL 94, 248102 (2005)).     

Analysis of harmonic propagation in a power distribution system: An application of a distributed constant‐circuit model

This paper discusses harmonic propagation and damping in a long‐distance distribution feeder having many capacitors for power factor correction, and presents harmonic damping characteristics of a shunt active filter based on voltage detection. A distributed constant‐circuit model for the feeder is derived to perform analysis with the focus on harmonic propagation and damping. As a result, it is clarified by theory and experiment that harmonic propagation throughout the feeder can be mitigated by installing the active filter, which acts as a harmonic terminator, on the end terminal of the feeder. © 2002 Scripta Technica, Electr Eng Jpn, 139(1): 73–81, 2002; DOI 10.1002/eej.1148     

A zero-current-switching based three-phase pulse width modulation inverter

With the remarkable progress of switching devices, the switching frequency of a voltage-source PWM inverter has become higher and higher. A high-frequency PWM inverter gives great benefits in the reduction of current ripples and acoustic noises. However, high-frequency hard switching causes the increase of switching losses and EMI to be solved. The authors propose a zero-current-switching based three-phase PWM inverter which has small resonant circuits on the ac side. The current flowing in a switching device is a sum of the resonant current and the load current. Since the switching device is turned on and off at zero current, the switching losses and electromagnetic noises are greatly reduced. This paper described the principle of the zero current switching operation, the design of the resonant circuits and the control scheme for the new soft switching inverter. Moreover, it shows interesting experimental results obtained by the zero-current-switching PWM inverter which drives an induction motor of 2.2 kW.