Simultaneous determination of five antioxidants in food by HPLC with fluorescence detection

An HPLC method with fluorescence detection was developed for the determination of propyl gallate, nordihydroguaiaretic acid, butylated hydroxyanisole (2- and 3-tert-butyl-4-hydroxyanisole), tert-butylhydroquinone and octyl gallate in edible oils and foods. The antioxidants in edible oil were isolated directly with acetonitrile saturated with n-hexane. The antioxidants in food were extracted with ethyl acetate and the extract was concentrated under vacuum. They were isolated from the residue with acetonitrile saturated with n-hexane. The acetonitrile layer was centrifuged at 5,000 rpm for 10 min. The HPLC separation was performed on a Symmetry C18 column (3.5 microns, 4.6 mm i.d. x 150 mm) using a mixture of 5% acetic acid-acetonitrile-methanol (4:3:3, v/v/v) as the mobile phase and monitored by using a fluorescence detector with time programming. Sample peaks were identified by comparison of the fluorescence spectra with those of antioxidant standards. Average recoveries of fortified antioxidants at 100 micrograms/g were 72.1-99.6%. Coefficients of variation were 0.7-7.2%.     

Numerical computation on the control of aerial flow by the magnetizing force in gravitational and nongravitational fields

Two-dimensional numerical computations were carried out in order to examine the effect of magnetizing force for the air in a cylindrical container with thermal and magnetic field gradients. In a gravitational field, the air was driven by both gravitational and magnetizing forces, and flow pattern and the heat transfer rate greatly depended on the axial position of the coil. Moreover, when the magnetizing and gravitational forces cancel out each other, convection became almost quiescent. On the other hand, the aerial flow was induced by the magnetizing force even in a nongravitational field, and the air behaved like an electrically conducting fluid.     

Crystallographic Orientation Dependence of the Schottky Properties of Au/SrTiO3 Junctions

Crystallographic orientation dependence of the Schottky properties of Au/Nb-doped SrTiO₃ (STO:Nb) junctions has been investigated using single crystals of STO:Nb (1 0 0) and (1 1 1). It is found from electrical properties that the Schottky barrier height (SBH) of the Au/STO:Nb junctions estimated from current density (J)-voltage (V) characteristics shows crystallographic orientation dependence, while the flat band voltage estimated from capacitance (C)-voltage (V) characteristics is independent of the orientation. Displacement currents originated from the junction capacitance have been clearly observed at reverse bias voltage even in a condition of dV/dt 8.75 × 10^–3 [V/s] because of large electrostatic permittivity of the STO, and the displacement currents also showed crystallographic orientation dependence. The different response in the electrical properties of the Schottky junctions suggests that electric properties of intrinsic low permittivity layers, which exist at Au/STO:Nb interfaces, have the crystallographic orientation dependence.     

Daily integrated generation scheduling for thermal,pumped‐storage,and cascaded hydro units and purchasing power considering network constraints

We have developed an innovative power generation scheduling method using quadratic programming (QP). The advantage of using our method is that it simultaneously solves unit commitment and economic load dispatch. We relax the binary variables of the unit state into continuous variables to apply QP to this problem. We also add a penalty term to converge the value of those variables to 0 or 1 to the objective function: the sum of the fuel costs and the start‐up costs. This penalty term depends on the per‐unit fuel cost. The possibility of its variable converging to zero increases as the cost increases. This method was applied to a test system of daily generation scheduling that consisted of 29 thermal units, two pumped‐storage units, four cascaded hydro units, and one transmission. The schedule satisfied all constraints, that is, load‐power balance, operation reserve, power flow, minimum up/down‐times, and fuel consumption. This result shows that the proposed method is effective. © 2011 Wiley Periodicals, Inc. Electr Eng Jpn, 175(1): 25–34, 2011; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21014     

Novel iridium complex and its copolymer with N-vinyl carbazole for electroluminescent devices

A novel iridium complex having the polymerizable functional group as one of the ligands, bis(2-phenylene pyridine) acrylate iridium lr(ppy)2Ac was synthesized as a phosphorescent dopant for electroluminescent (EL) devices. It has a photoluminescence spectrum peak at about 530 nm. EL devices were fabricated by doping lr(ppy)2Ac into host materials, such as BCP (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline) and poly(N-vinyl carbazole) (PVCz). Bright blue-green luminescence of about 12 000 cd/m2 was observed for an EL device having a structure of indium-tin oxide JTO)/1r(ppy)2Ac-doped TPD:PVCz/BCP/Alq3 [tris(8-hdroxyquinoline) aluniinuml/Mg:Ag. Furthermore, the iridium complex was copolymerized with N-vinyl carbazole (VCz) to form a random copolymer with a number average molecular weight of about 1000. An EL device using this hole-transport layer gave bright blue-green emission of more than 6000 cd/m2. These results indicate that lr(ppy)2Ae, especially its copolymer with VCz, can be a promising phosphorescent material for organic EL devices.     

Lower Irritation Potential of Laureth‐3 Carboxylate Amino Acid Salt

Sodium laureth sulfate and amino acid type surfactants have been categorized as low‐skin irritation chemicals based on results of previous skin irritation tests. However, detergent‐induced skin irritation still occurs. Detergents with a low‐skin irritation effect are required, since the number of cosmetics for sensitive skin has increased. Therefore, an in vitro method of testing the safety of cosmetics for sensitive skin is required. Skin irritation by anionic surfactants was investigated to determine the effect of laureth‐3 carboxylate (polyoxyethylene lauryl carboxymethyl ether) amino acid salt on skin irritation. In addition, sodium laureth sulfate and amino acid type surfactants, regarded as low‐irritation surfactants, were also tested for skin irritation. The skin irritation effect of laureth‐3 carboxylate lysine salt (Surfactant 1 ), sodium laureth sulfate (Surfactant 2 ), and sodium N‐lauroyl glutamate (Surfactant 3 ) were investigated using a reconstructed human cultured epidermal model, LabCyte EPI‐MODEL24 6D. Cell viabilities of cultured epidermal cells exposed to Surfactant 1 (5.0 % aq.), Surfactant 2 , and Surfactant 3 were 82.0, 45.0 and 19.1 %, respectively. There were significant differences in cell viability upon exposure to 5.0 % aqueous test solutions of the three test chemicals. The results of the current investigation indicate that Surfactant 1 has a low skin‐irritation effect.     

Oxygen Potential Measurement of Americium Oxide by Electromotive Force Method

The oxygen potentials of AmO_{2− x} were measured in the x range of 0.01–0.5 and the temperature range of 1000–1333 K by the electromotive force method. The oxygen potentials at 1333 K were −19.83 kJ/mol for x =0.019 and −319.1 kJ/mol for x =0.485, which were higher than those of CeO_{2− x} by approximately 200 kJ/mol for the corresponding x values. From the dependence of the oxygen potentials on x and temperature, a tentative phase diagram of Am–O system was proposed, which suggested the presence of the intermediate phases of Am₇O₁₂ and Am₉O₁₆ in the Am–O system.     

A High-Speed Optical Data Highway for Industrial Control Systems

Recent application of distributed control systems to large-and medium-scale industrial plants requires effective and high-speed communication among the control devices each other to ensure high-performance operation.     

Temperature control for the expansion of artificial DNA motif

The DNA, which forms a double helical conformation by the highly selective base-pairing rule with the width of 2 nm, is one of the polymers utilized as a template for nanoparticle assembly. Then, holiday junction structure, where two different DNA double strands intersect and replace each complement strand, is an important artificial motif for forming two-dimensional mesh-like DNA morphology. In this study, the two-dimensional sheet with the mesh-like conformation is formed and the growth of the DNA morphology is controlled by changing the temperature in the formation process. The influence of the cooling procedure on the formation process of the two-dimensional DNA sheet is observed by atomic force microscope, and the formation of double strands in the process is traced by absorption spectra. The spectroscopic results demonstrate that the two-dimensional DNA sheet is strongly dependent on the correlation between the applied cooling process and the melting temperature of double helical conformation, and that the growth of the two-dimensional DNA sheet can be manipulated by the cooling procedure. Further, we will show the size control of the DNA sheet by mixing the designed DNA which inhibits the growth of the DNA sheet.     

An experimental evaluation of spatial distribution for deeply penetrating protons in carbon material

The peak profile of the 4.8-MeV resonance by the ¹²C(p,p)¹²C reaction in backscattering geometry has been analyzed to examine two kinds of stragglings of proton, i.e. the depth straggling in the incoming path and the energy loss straggling in the outgoing path. The analysis, which is combined with existing theoretical treatments for the stopping process and the energy loss straggling, has made it possible to deduce the penetration depth and its spread at the resonance position in carbon materials. The present method, as a new tool for direct inspection of ion beams inside target material, is explained in detail.