Relative molar sensitivities of carnosol and carnosic acid with respect to diphenylamine allow accurate quantification of antioxidants in rosemary extract

We have been developing a high-performance liquid chromatography/photodiode array (HPLC/PDA) employing relative molar sensitivities (RMSs) and adopted it to the accurate quantification of carnosol (CL) and carnosic acid (CA) which are the antioxidants in rosemary extract. The method requires no references of CL or CA and instead uses RMSs with respect to diphenylamine (DPA) whose certified reference material is available from a reagent manufacturer. The molar and response ratios of the analytes to the reference in an artificial mixture of them were determined using ¹H-quantitative nuclear magnetic resonance spectroscopy (¹H-qNMR) and HPLC/PDA at a wavelength of 284 nm under isocratic condition, respectively, and then RMSs were calculated to be 0.111 for CL/DPA and 0.0809 for CA/DPA as averaged values in three HPLC–PDA instruments. The RMS values varied by up to 1.1% as relative standard deviation. To evaluate the performance of HPLC/PDA with the RMSs, the CL and CA contents in rosemary extracts were determined using DPA as a reference. The CL and CA contents were compared with those determined using calibration curves of CL and CA obtained by HPLC measurement of standard solutions prepared from their reagents whose absolute purities were determined using ¹H-qNMR. The differences between the two methods for CL and CA were ≤3% as relative error. This chromatographic method with RMSs allows a simple and reliable quantification when reference of the analyte is unavailable.     

Multiple layers of silicon-on-insulator islands fabrication byselective epitaxial growth

This paper presents for the first time, multiple layers of silicon-on-insulator (MLSOI) device islands fabricated using selective epitaxial growth (SEG) and epitaxial lateral overgrowth (ELO) techniques. MLSOI has the potential for ultra dense device integration. SOI device islands as small as 150 nm×150 nm, with thickness down to 40 nm have been fabricated. SOI device islands (5 μm×500 μm) in the second layer have shown no stacking faults in the 1290 islands inspected. To demonstrate the device quality material, fully depleted SOI (FD-SOI) P-MOSFET's were fabricated in the first layer SOI islands with gate lengths down to less than 170 nm. Typically they had low subthreshold leakage, below 0.2 pA/μm, and a subthreshold swing of 76 mV/dec was measured     

Anionic polymerization of vinylsilanes

Summary The anionic polymerization of dimethylphenylvinylsilane with sec-butyllithium/N,N,N,N-tetramethylethylenediamine (TMEDA) was investigated. The polymerization proceeded up to 100% yield and afforded the polymer having isomerized-structure units. The polymerization was accompanied by chain transfer reaction to the monomer and the polymerization rate in the presence of TMEDA was much lower than in the absence of TMEDA.     

An X-ray photo-electron spectroscopic study on the role of molybdenum in increasing the corrosion resistance of ferritic stainless steels in HC1

X-ray photo-electron spectroscopy has been used to investigate the correlation between composition of surface films and the beneficial effects of molybdenum addition to high purity, 30Cr ferritic stainless steels in improving the corrosion resistance properties in HCI. It has been found that the passive films formed consist mainly of hydrated chromium oxy-hydroxide and the composition of the films on 30Cr and 30Cr-2Mo stainless steels is essentially the same, except for the existence of a small amount of hexavalent molybdenum on the latter steel. The surface film formed in the active region contains a large amount of hexavalent molybdenum. The beneficial effects of molybdenum have been interpreted as follows: molybdenum eliminates the active surface sites through the formation of molybdenum oxy-hydroxide or molybdate on these site, on which it is difficult to form the stable passive film. This leads to the appearance of a homogeneous steel surface and to the formation of a homogeneous passive film.     

A thin layer including a carbon material improves the rate capability of an electric double layer capacitor

We present a new method to improve the rate capability of an electric double layer capacitor (EDLC) using a thin polymer layer having a high concentration of carbon material on a current collector (CLC). A novel thermocuring coating composed of a glycol-chitosan, a pyromellitic acid and a conductive carbon powder can form stable CLC on a metal foil current collector simply by spreading and curing at 160 °C for a couple of minutes. We compared the performance of some demonstration EDLC cells using three kinds of current collector: a conventional aluminum oxide foil for EDLC, an aluminum foil and an aluminum foil with CLC. The cell with the CLC had a much higher rate capability than the cell without CLC. Only the CLC cell was able to discharge at a current density of 500C. This cell shows a slight deterioration in capacity in a high temperature, continuous charging, life test, and the CLC has a suppressing effect on the internal resistance increase of EDLCs. The use of a CLC film current collector is one of the most effective and simple methods for the improvement of EDLC rate performance. In particular, a current collector consisting of aluminum foil coupled with a CLC promises to be a low cost alternative to the aluminum oxide foil commonly used in EDLCs.     

Behavior and mechanisms of Ni/ScSZ cermet anode deterioration by trace tar in wood gas in a solid oxide fuel cell

In order to determine both the criterion for diagnosing the deterioration of Ni/ScSZ cermet anodes in solid oxide fuel cells (SOFCs) by tar contaminants in wood gas and the tolerance limit of tar in wood gas for such anodes, the influence of tar concentration in wood gas on anode deterioration behavior was examined by means of scanning electron microscopy. We found that the anode degradation mechanism consisted of three phenomena: the disappearance of Ni particles, the destruction of sintered ScSZ, and carbon deposition. Furthermore, the Ni particle disappearance occurred at lower tar concentrations than did sintered ScSZ destruction and apparent carbon deposition. Therefore, we propose that the disappearance of Ni particles be set as the criterion for confirming deterioration of Ni/ScSZ cermet anodes in SOFCs by tar. On the basis of this criterion, the tolerance limit of toluene in fuel gas was determined to be 3 g/Nm³ when the operating temperature, steam to carbon molar ratio, and current density were 1073 K, 1, and 0.5 A/cm², respectively. The tolerance limit for tar for the fuel cell constructed herein was one to two orders of magnitude higher than that for internal combustion engines.     

Experimental attempts of sub-micrometer order size machining using micro-EDM

So far, parts larger than several micrometers can be machined by micro-electrical discharge machining (micro-EDM). However, with the growing demands for even smaller parts, sub-micrometer order machining or even nanometer order machining are increasingly required in various industrial areas. In order to meet these requirements, the study on sub-micrometer order manufacturing has become considerably important. In the present study, experimental attempts of sub-micrometer order size machining using micro-EDM was performed, in which the smallest possible size that can be achieved for machined parts was examined, and the factors affecting the manufacturing of sub-micrometer parts were investigated. The results showed that insufficient positioning accuracy, smallest discharge energy and the machined shape error due to the influence of gap control and thermal deformation are not suitable for sub-micrometer machining. Disregarding positioning accuracy and machined shape error, cemented tungsten carbide (WC) and cemented tungsten carbide made of super fine particles (SWC) are relatively better than tungsten (W) from the viewpoint of material structure and influence of residual stress. In particular, SWC is more suitable than WC because both crystal grains size and size of defects among grains are smaller. Setting the polarity of workpiece negative was found to contribute to achieving sub-micrometer machining if the material removal rate is disregarded. Based on these investigation results, sub-micrometer machining using SWC was attempted. The minimum diameter obtained was about 2.8 μm.     

ESCA study of the passive film on an extremely corrosion-resistant amorphous iron alloy

X-ray photoelectron spectroscopy was applied to study the composition of the passive film formed on an extremely corrosion resistant amorphous Fe-10at.%Cr-13at.%P-7at.%C alloy in 1 N HCl. The passive film consists mainly of hydrated chromium oxyhydroxide which is a common major constituent of passive films on crystalline stainless steels. The extremely high corrosion resistance of the amorphous alloy can only in part be attributed to the formation of a protective hydrated chromium oxyhydroxide film.     

The effect of local polarized domains of ferroelectric P(VDF/TrFE) copolymer thin film on a carbon nanotube field-effect transistor

We produced local polarized domains of ferroelectric P(VDF/TrFE) copolymer thin films on a carbon nanotube field-effect transistor (CN-FET) channel by atomic force microscopy (AFM). The drain current versus gate voltage (I(d)-V(g)) curves measured after forming the local polarized domains showed a shift in the threshold voltages. We also found that the amount of the shifts in the threshold voltages gradually decreased during the measurement of this characteristic over 100?h after forming the polarized domains. The mechanisms of the shifts in the threshold voltages and their decreasing behaviour were explained in terms of the excessive charges that were induced upon the formation of the polarized domains.