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101.
Ikuo Ueta Ayako Mizuguchi Koji Fujimura Susumu Kawakubo Yoshihiro Saito 《Analytica chimica acta》2012
A novel needle-type sample preparation device was developed for the effective preconcentration of volatile organic compounds (VOCs) in indoor air before gas chromatography–mass spectrometry (GC–MS) analysis. To develop a device for extracting a wide range of VOCs typically found in indoor air, several types of particulate sorbents were tested as the extraction medium in the needle-type extraction device. To determine the content of these VOCs, air samples were collected for 30 min with the packed sorbent(s) in the extraction needle, and the extracted VOCs were thermally desorbed in a GC injection port by the direct insertion of the needle. A double-bed sorbent consisting of a needle packed with divinylbenzene and activated carbon particles exhibited excellent extraction and desorption performance and adequate extraction capacity for all the investigated VOCs. The results also clearly demonstrated that the proposed sample preparation method is a more rapid, simpler extraction/desorption technique than traditional sample preparation methods. 相似文献
102.
Waki T Nakanishi I Matsumoto K Kitajima J Chikuma T Kobayashi S 《Chemical & pharmaceutical bulletin》2012,60(1):37-44
The antioxidant activities of flavonoids and their glycosides were measured with the 2,2-diphenyl-1-picrylhydrazyl radical (DPPH radical, DPPH(·)) scavenging method. The results show that free hydroxyl flavonoids are not necessarily more active than O-glycoside. Quercetin and kaempferol showed higher activity than apigenin. The C- and O-glycosides of flavonoids generally showed higher radical scavenging activity than aglycones; however, kaempferol C3-O-glycoside (astragalin) showed higher activity than kaempferol. In the radical scavenging activity of flavonoids, it was expected that OH substitutions at C3 and C5 and catechol substitution at C2 of B ring and intramolecular hydrogen bonding between OH at C5 and ketone at C3 would increase the activity; however, the reasons have yet to be clarified. We here show that the radical scavenging activities of flavonoids are controlled by their absolute hardness (η) and absolute electronegativity (χ) as a electronic state. Kaempferol and quercetin provide high radical scavenging activity since (i) OH substitutions at C3 and C5 strikingly decrease η of flavones, (ii) OH substitutions at C3 and C7 decrease χ and η of flavones, and (iii) phenol or o-catechol substitution at C2 of B ring decrease χ of flavones. The coordinate r(χ,?η) as the electron state must be small to increase the radical scavenging activity of flavonoids. The results show that chemically soft kaempferol and quercetin have higher DPPH radical scavenging activity than chemically hard genistein and daidzein. 相似文献
103.
Tadatomi Shinohara Ikuo S. Sogami Masayuki Tanigawa Tsuyoshi Yoshiyama Hisashi Yamada Hideo Oka 《Phase Transitions》2013,86(8):875-886
Colloidal crystals can be formed of silica particles while those of titania particles are not known under the normal gravitational field, because of their high specific gravity. We found by the Kikuchi--Kossel diffraction technique that, when silica particles (diameter: D?=?170?nm; density: ρ?=?2.2?g cm?3) are mixed with titania particles (D?=?127?nm; ρ?=?3.9?g cm?3), colloidal crystals are formed. Colloidal crystals started out with body-centred-cubic structure and changed to face-centred-cubic structures after about 60 days. Transitions began from the bottom of the container. Thus, the transitions are considered to be due to gravitational sedimentation. It is significant that the crystal growth process, which has not been observed in one-component dispersions of the silica particles, was found using titania particles with a wide range of the practical applicability. 相似文献
104.
The 212 − 111 line of H2D+ at 2.363 THz that was detected toward Sgr B2 and identified based on a calculated line frequency has been measured in the laboratory precisely by using a tunable far-infrared spectrometer. All the available THz lines and known millimeter- and submillimeter-wave lines together with the combination differences derived from the infrared transitions are fitted to the Watson effective Hamiltonian. A set of improved molecular constants are obtained. 相似文献
105.
Aslina Pahrudin Arrozi Zulzikry Hafiz Abu Bakar Hiroyasu Taguchi Daijiro Yanagisawa Ikuo Tooyama 《Molecules (Basel, Switzerland)》2021,26(17)
Thioredoxin-interacting protein (TXNIP) is involved in multiple disease-associated functions related to oxidative stress, especially by inhibiting the anti-oxidant- and thiol-reducing activity of thioredoxin (TXN). Shiga-Y5 (SY5), a fluorine-19 magnetic resonance probe for detecting amyloid-β deposition in the brain, previously showed therapeutic effects in a mouse model of Alzheimer’s disease; however, the mechanism of action of SY5 remains unclear. SY5 passes the blood–brain barrier and then undergoes hydrolysis to produce a derivative, Shiga-Y6 (SY6), which is a TXNIP-negative regulator. Therefore, this study investigates the therapeutic role of SY5 as the prodrug of SY6 in the thioredoxin system in the brain of a mouse model of Alzheimer’s disease. The intraperitoneal injection of SY5 significantly inhibited TXNIP mRNA (p = 0.0072) and protein expression (p = 0.0143) induced in the brain of APP/PS1 mice. In contrast, the levels of TXN mRNA (p = 0.0285) and protein (p = 0.0039) in the brain of APP/PS1 mice were increased after the injection of SY5. The ratio of TXN to TXNIP, which was decreased (p = 0.0131) in the brain of APP/PS1 mice, was significantly increased (p = 0.0072) after the injection of SY5. These results suggest that SY5 acts as a prodrug of SY6 in targeting the thioredoxin system and could be a potential therapeutic compound in oxidative stress-related diseases in the brain. 相似文献
106.
The phase diagram and local structure of melt-spun amorphous (a-) Fe100−xYx (22?x?62) alloys were investigated using AC and DC magnetic and extended X-ray absorption fine structure (EXAFS) measurements. The a-Fe–Y system shows reentrant spin glass (RSG) behavior for 42?x?58 and spin glass (SG) behavior for 60?x. Two SG transition temperatures, Tg and Tf, were obtained in the RSG state. The Tg, Tf and Curie temperature TC decrease with increasing x, and the TC and Tg vanish at x=60. A new magnetic phase diagram for the melt-spun a-Fe100−xYx alloys was obtained from magnetic measurements for higher Y concentration. The magnetic states of the a-Fe100−xYx alloys change remarkably around x=60 and an EXAFS study revealed that the average atomic distance between nearest-neighboring Fe atoms changes at approximately x=60. 相似文献
107.
Ikuo Nishitani 《Archiv der Mathematik》2006,87(3):206-210
We show that a finitely embedded module M over a commutative ring R is Artinian if the factor module M/(0 :M P) is finitely embedded for every prime ideal P of R.
Received: 10 June 2005 相似文献
108.
109.
The Polarized lower-frequency infrared spectra (800–33 cm-1) of nylon 66 (α form), nylon 77 (γ form), and nylon 6 (both α and γ form) have been examined. The spectral changes which occur on complex formation of the polyamides with iodine-potassium iodide solution and on subsequent iodine desorption have been studied in relation to the changes in the polymer structures. On the basis of these results, most of the stronger bands have been reasonably assigned to the vibrations characteristic of the amide group and the methylene chain of the polyamides, and some new structure–frequency correlations have been established for the polymers. 相似文献
110.