HPLC/PDA determination of carminic acid and 4-aminocarminic acid using relative molar sensitivities with respect to caffeine

To accurately determine carminic acid (CA) and its derivative 4-aminocarminic acid (4-ACA), a novel, high-performance liquid chromatography with photodiode array detector (HPLC/PDA) method using relative molar sensitivity (RMS) was developed. The method requires no analytical standards of CA and 4-ACA; instead it uses the RMS values with respect to caffeine (CAF), which is used as an internal standard. An off-line combination of ¹H-quantitative nuclear magnetic resonance spectroscopy (¹H-qNMR) and HPLC/PDA was able to precisely determine the RMSs of CA^274nm/CAF^274nm and 4-ACA^274nm/CAF^274nm. To confirm the performance of the HPLC/PDA method using RMSs, the CA and 4-ACA contents in test samples were tested using four different HPLC-PDA instruments and one HPLC-UV. The relative standard deviations of the results obtained from five chromatographs and two columns were less than 2.7% for CA^274nm/CAF^274nm and 1.1% for 4-ACA^274nm/CAF^274nm. The ¹H-qNMR method was directly employed to analyse the CA and 4-ACA contents in test samples. The differences between the quantitative values obtained from both methods were less than 5% for CA and 3% for 4-ACA. These results demonstrate that the HPLC/PDA method using RMSs to CAF is a simple and reliable quantification method that does not require CA and 4-ACA certified reference materials.     

Correlation between Cu (I)-complexes and filling of via cross sections by copper electrodeposition

In the manufacture of metal interconnects for semiconductor devices, trenches and vias in dielectric layers on the Si wafer are filled by copper electrodeposition. The acceleration of deposition at the bottom of trenches and vias is a key to the bottom-up filling of these high aspect ratio cavities. We report the detection of this acceleration effect by rotating ring disk electrode experiments. The Cu (I)-complex, which forms on the disk electrode, was captured as a current (I_ring) on the ring electrode. I_ring increased in periodic reverse pulse current mode, as compared to direct or pulse current. The periodic reverse pulse current produced the most bottom-up filling based on microscopic observations of via cross sections. I_ring increased with the additions of Cl⁻, which also produced greater bottom-up filling. I_ring increased with additions of SPS, which were also found to improve bottom-up filling.     

Synthesis of Substituted 2,2′‐Bipyridines and 2,2′:6′,2′′‐Terpyridines by Cobalt‐Catalyzed Cycloaddition Reactions of Nitriles and α,ω‐Diynes with Exclusive Regioselectivity

A variety of substituted 2,2′‐bipyridines were synthesized by a 1,2‐bis(diphenylphosphino)ethane (dppe)/cobalt chloride hexahydrate (CoCl₂⋅6 H₂O)/zinc‐catalyzed [2+2+2] cycloaddition reaction of diynes and nitriles, with all reactions exhibiting exclusive regioselectivity. Thus, symmetrical and unsymmetrical 1,6‐diynes and 2‐cyanopyridine reacted in the presence of 5 mol % of dppe, 5 mol % of CoCl₂⋅6 H₂O and 10 mol % of zinc powder to provide the corresponding 2,2′‐bipyridines. Under identical reaction conditions, 1‐(2‐pyridyl)‐1,6‐diynes and nitriles reacted smoothly with exclusive regioselectivity to produce 2,2′‐bipyridines in good yield. 2,2′‐Bipyridines were also obtained by the double [2+2+2] cycloaddition reaction of 1,6,8,13‐tetraynes with nitriles. Similarly, 2,2′:6′,2′′‐terpyridines were synthesized from 1‐(2‐pyridyl)‐1,6‐diyne and 2‐cyanopyridine. The regiochemistry observed can be explained by considering the electronic nature of cobaltacyclopentadiene intermediates and nitriles. A survey of the exclusive regiochemical trend gives reasonable credence to the synthetic potential of the present method.     

Multi-scale,multi-depth lithography using optical fibers for microfluidic applications

This paper proposes and demonstrates a method for multi-scale, multi-depth three-dimensional (3D) lithography. In this method, 3D molds for replicating microchannels are fabricated by passing a non-focused laser beam through an optical fiber, whose tip is immersed in a droplet of photopolymer. Line width is adjustable from 1 to 980 µm using eight kinds of optical fibers with different core diameters. The height of line drawing can be controlled by adjusting the distance between the tip of the optical fiber and a substrate. The surface roughness (R_a, R_z) of a single line and plane was evaluated. The method was employed to fabricate a 3D mold of a microchannel containing tandem chambers, which was then successfully replicated in PDMS. Multi-scale, multi-depth 3D lithography can provide a simple, flexible tool for producing PDMS microfluidic devices.     

Thermoacoustic effects of inviscid fluids

Thermoacoustic effects of inviscid fluids are studied with the use of linearized hydrodynamic equations. The heat flux and the acoustic energy source due to acoustic waves are related to entropy oscillations due to irreversible processes, and are evaluated for a plane wave in a long cylindrical tube with the boundary condition that the local oscillation of the temperature is absent at the wall surface. The heat flux and acoustic energy source obtained in the standing wave approximation give qualitative explanations of heat pumping and similar experiments and stability limits.     

Strain-Dependent Dynamic Properties of Remolded Sand-Clay Mixtures

A series of undrained cyclic torsional simple shear tests using hollow cylindrical torsional shear apparatus was carried out to investigate the dynamic shear moduli and damping properties of clayey specimens with various sand contents and plasticity indices. The clayey soils used were collected from various sites along the coast of west Japan. Among these clayey soils, a clay sample with intermediate plasticity and another with high plasticity were mixed with silica sand at different proportions in order to examine the dynamic properties of sand-clay mixtures. In addition, experiments were carried out on undisturbed and remolded natural clay specimens with various plasticities. The effects of plasticity, loading frequency and confining pressure on the strain dependent normalized shear modulus and damping ratio were examined. Based on the results, empirical correlations for predicting the normalized shear modulus and damping ratio of remolded sand-clay mixtures at various shear strain levels were proposed.     

Low methanol crossover and high performance of DMFCs achieved with a pore-filling polymer electrolyte membrane

We compared the performance of the membrane electrode assembly for direct methanol fuel cells (DMFCs) composed of a pore-filling polymer electrolyte membrane (PF membrane) with that composed of a commercial Nafion-117 membrane. In DMFC tests, the methanol crossover flux was 23% lower in the PF membrane than in the Nafion-117 membrane even though the thickness of the PF membrane was 43% that of Nafion-117. This led to a higher DMFC performance and the lower overpotential of the cathode of the PF membrane. Feeding an aqueous 10 M methanol solution at 50 °C produced a low cathode overpotential, as low as 0.40 V at 0.2 A in the PF membrane, whereas the potential was 0.65 V at 0.2 A in the Nafion-117 membrane. In contrast, the ohmic loss and anode overpotential were almost the same in the two membranes. We confirmed that a reduction in methanol crossover using the PF membrane results in lower cathode overpotential and higher DMFC performance. In addition, the electro-osmotic coefficient was estimated as 1.3 in the PF membrane and 2.6 in Nafion-117, based on a water mass-balance model and values showing that the PF membrane prevents the flooding of the cathode at a low gas flow rate using. A highly concentrated methanol solution can be applied as a fuel without decreasing DMFC performance using PF membranes.     

Development of event-specific quantitation method for GA21 maize, which is a gm event without CaMV35S promoter

A real-time PCR detection method was developed for event-specific quantitation of Roundup Ready maize, GA21. The developed PCR method was designed to amplify an artificial junction site between the native maize genome DNA and the recombinant DNA of GA21 maize, which provides only one target sequence per haploid of GA21 genome. Thus, the amplification efficiency of the event-specific target for GA21 became closely similar to the amplification of SSIIb, and the conversion factor (Cf) for the quantitation method was similar to the theoretical value. The developed method demonstrated better performance than the existing construct-specific method that has been used as a Japanese official method. The developed method can easily be combined with the real-time PCR targeting of the CaMV35S promoter, and the multiplexed method should be an effective screening method for GM maize.     

Laser‐addressed full‐color photo‐quality rewritable sheets based on thermochromic systems with leuco dyes

We have developed a laser‐addressed full‐color photographic quality rewritable sheet. The sheet was composed of a vertically stacked Cyan/Magenta/Yellow‐thermochromic system with a mixture of leuco dyes, developers and photothermal conversion agents in a polymer matrix. The sheet was simply manufactured by roll‐to‐roll (R2R) processes. Writing and erasing were performed by scan of near‐infrared laser light. It achieved full‐color photographic quality images with a wide color gamut with 70% coverage of the Specifications for Web Offset Publications (SWOP) standards and a high resolution of 426 ppi. Clear rewritability has also been confirmed. Non‐contact laser writing has other advantages in that it can create an image under a protection film, and it has form factor flexibility. We have developed a reliability model for high‐temperature storage and a light fastness test. This model showed a good agreement with experimental data, and the lifetime of an image was estimated to be over 8 years under ambient conditions. This technology will create applications for on‐demand rewritable image design while saving power and reducing the use of paper, which will eventually contribute to a sustainable society.     

Proposal of a high‐performance solid oxide fuel cell combined power generation system with carbon dioxide recovery

A new fossil‐fuel‐utilized high‐performance combined power generation system with liquefaction recovery of carbon dioxide is proposed. In the system, pure oxygen is used as the oxidant gas to prevent the mixture of nitrogen in the exhaust gas and to make the liquefaction recovery of carbon dioxide possible. Solid oxide fuel cell is selected as the topping cycle. The exhaust fuel gas of the solid oxide fuel cell is afterburned with its exhaust oxidant gas of pure oxygen and the heat of the combustion gas is utilized in the bottoming cycle. Nonequilibrium MHD/noble gas turbine cycle is selected as the bottoming cycle because the temperature of the combustion gas reaches about 2300 K. It is made clear through detailed examination of energy balance that the total thermal efficiency of the system using natural gas (methane) as the fuel reaches 63.24% (HHV) or 70.18% (LHV). This efficiency is very high as for the system with carbon dioxide recovery. The proposed system, therefore, has excellent performance, and further research and development is warranted. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 143(4): 12–21, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10146