Identification of the odour-active aldehyde trans-4,5-epoxy-(E,Z)-2,7-decadienal in yuzu (Citrus junos Sieb. ex Tanaka)

Yuzu (Citrus junos Sieb. ex Tanaka) is a variety of sour citrus fruit that is popular in Japan. In this study, we investigated its aroma, which many people, especially in Japan, find appealing. Aroma extract dilution analysis was used to screen the odour-active compounds in the yuzu volatile oil. An unknown odorant with an albedo-like odour and a high flavour-dilution factor was detected. To identify this odorant, it was separated via flash column chromatography on silica gel and then fractionated by preparative high-performance liquid chromatography on a reverse-phase column. The volatile fraction, which contained a significant amount of the target unknown compound, was analysed by gas chromatography–mass spectrometry and gas chromatography–olfactometry to determine its mass spectrum, retention index, and odour quality. By comparing the resultant data with that of a synthesised authentic reference compound, it was evident that the unknown odorant was trans-4,5-epoxy-(E,Z)-2,7-decadienal (3); this is the first time that it has been identified as an odour-active unsaturated aldehyde in yuzu volatile oil. From the results of a model formation experiment, we propose that trans-4,5-epoxy-(E,Z)-2,7-decadienal originates from α-linolenic acid via 13(S)-hydroperoxy-(Z,E,Z)-9,11,15-octadecatrienoic acid (13(S)-HPOT), which is a lipoxygenase-induced oxidation product of α-linolenic acid.     

Fast Discharge Circuit for Longitudinally Excited CO2 Laser

In a longitudinally excited CO₂ laser with a short laser pulse, similarly to TEA and Q-switched CO₂ lasers, a fast discharge is very important. We investigated the use of a fast discharge circuit to obtain a high spike laser pulse in a longitudinally excited CO₂ laser. We compared a traditional capacitor-transfer circuit having a buffer capacitance of 700 pF with our direct-drive circuit in which the buffer capacitance is removed. The direct-drive circuit produced a fast discharge and a high spike laser pulse. We also investigated the effect of a resistance connected in parallel with the discharge tube to eliminate low discharge current after the main discharge. A low resistance of 1 kΩ or less acted as a shunt resistance. The shunt resistance was effective in decreasing the energy of the laser pulse tail at high gas pressure.     

Restraint method of voltage total harmonic distortion in distribution network by power conditioner systems using measured data from IT switches

The amount of distributed generation (DG) such as photovoltaic systems and wind power generator systems installed in distribution systems has been increasing because of reduction of the effects on the environment. However, harmonic problems in the distribution system are a concern in the context of increased connection of DGs through inverters and the spread of power electronics equipment. This paper proposes a method for the restraint of voltage total harmonic distortion (THD) in a whole distribution network by active filter (AF) operation of multiple power conditioner systems (PCSs). It also proposes a method for determination of the optimal gain of AF operation so as to minimize the maximum value of voltage THD in the distribution network by real‐time feedback control with measured data from information technology (IT) switches. In order to verify the validity of the proposed method, numerical calculations are carried out using an analytical model of a distribution network of interconnected DGs with PCSs. © 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 182(3): 19–29, 2013; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.22354     

Preparation of nitrogen-doped porous carbon by ammonia gas treatment and the effects of N-doping on water adsorption

Nitrogen-doped porous carbons (N-RFCC) were prepared by NH₃N₂ mixture gas treatment at high temperature during the carbonization process on resorcinol–formaldehyde cryogels. To show the role of N-doping on the adsorption behavior we carried out water adsorption, and it was found that the amount of water adsorbed is directly related to the nitrogen content over the low pressure region (P/P₀ < 0.3). Applying the theoretical water adsorption model, Horikawa–Do (HD) model, to the adsorption isotherms of N-RFCCs, we could analyze the effects of nitrogen-doping on the adsorption mechanism. Although the concentration of functional groups of N-RFCC is almost equal to that of the non-doped RFCC, which was measured by Boehm titration method, the water adsorbed amounts of N-RFCCs over the low pressure region were larger. This is due to part of the doped nitrogen atoms act as functional groups, contributing to the total concentration of functional groups. The saturated concentrations depend on the packing fraction of water molecules, which in turn depends on the pore size. The packing fractions of N-RFCCs are larger than those of RFCCs, and this could be attributed to the high affinity between water clusters and N-doped surfaces, resulting in a reduced hydrophobicity of the surface.     

Anti-Allergic Drug Suppressed Pancreatic Carcinogenesis via Down-Regulation of Cellular Proliferation

Pancreatic cancer is a fatal disease, and thus its chemoprevention is an important issue. Based on the recent report that patients with allergic diseases have a low risk for pancreatic cancer, we examined the potential chemopreventive effect of anti-allergic agents using a hamster pancreatic carcinogenesis model. Among the three anti-allergic drugs administered, montelukast showed a tendency to suppress the incidence of pancreatic cancer. Further animal study revealed a significantly decreased incidence of pancreatic cancer in the high-dose montelukast group compared with controls. The development of the pancreatic intraepithelial neoplasia lesions was also significantly suppressed. The Ki-67 labeling index was significantly lower in pancreatic carcinomas in the high-dose montelukast group than in controls. In vitro experiments revealed that montelukast suppressed proliferation of pancreatic cancer cells in a dose-dependent manner with decreased expression of phospho-ERK1/2. Montelukast induced G1 phase arrest. Conversely, leukotriene D₄ (LTD₄), an agonist of CYSLTR1, increased cellular proliferation of pancreatic cancer cells with an accumulation of phospho-ERK1/2. In our cohort, pancreatic ductal adenocarcinoma patients with high CYSLTR1 expression showed a significantly unfavorable clinical outcome compared with those with low expression. Our results indicate that montelukast exerts a chemopreventive effect on pancreatic cancer via the LTD₄–CYSLTR1 axis and has potential for treatment of pancreatic carcinogenesis.     

Tritium retention to the first wall of JT-60U

For economic and safety reasons, tritium (T) accumulation on plasma facing wall (PFW) of fusion reactor is strictly limited. In this study, T inventory in the graphite tiles used at the first wall of JT-60U was measured by a full combustion method. It was found that T was only retained near plasma facing surfaces sides of the tiles and the amount of retained T increased from <10¹¹ to <10¹³ T atoms/cm² with increasing the exposed discharge period of the tiles. Integrating the T retention with the total surface area of the outer first wall tiles, the fraction of retained T in that area was estimated to be 13% of the total T production. It was confirmed that these retained T were part of the energetic T produced by DD reactions without being replaced by HH discharges. Based on the retained fraction, the annual amount of T retention in the outer first wall of a demo-size reactor was calculated to be 360 g/burn-year at maximum. Even the value would be much less in the reactor, the accumulation of this kind of inventory could have significant contribution to the total T inventory.