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141.
Mitsuhiko Miyazaki Ryuhei Ohara Kota Daigoku Kenro Hashimoto Jonathan R. Woodward Claude Dedonder Christophe Jouvet Masaaki Fujii 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2015,127(50):15304-15308
Hydrogen‐release by photoexcitation, excited‐state‐hydrogen‐transfer (ESHT), is one of the important photochemical processes that occur in aromatic acids and is responsible for photoprotection of biomolecules. The mechanism is described by conversion of the initial state to a charge‐separated state along the O(N)‐H bond elongation, leading to dissociation. Thus ESHT is not a simple H‐atom transfer in which a proton and a 1s electron move together. Here we show that the electron‐transfer and the proton‐motion are decoupled in gas‐phase ESHT. We monitor electron and proton transfer independently by picosecond time‐resolved near‐infrared and infrared spectroscopy for isolated phenol–(ammonia)5, a benchmark molecular cluster. Electron transfer from phenol to ammonia occurred in less than 3 picoseconds, while the overall H‐atom transfer took 15 picoseconds. The observed electron‐proton decoupling will allow for a deeper understanding and control of of photochemistry in biomolecules. 相似文献
142.
143.
Automatic analyzer for highly polar carboxylic acids based on fluorescence derivatization–liquid chromatography 下载免费PDF全文
Kenichiro Todoroki Tatsuki Nakano Yasuhiro Ishii Kanoko Goto Ryoko Tomita Toshihiro Fujioka Jun Zhe Min Koichi Inoue Toshimasa Toyo'oka 《Biomedical chromatography : BMC》2015,29(3):445-451
A sensitive, versatile, and reproducible automatic analyzer for highly polar carboxylic acids based on a fluorescence derivatization–liquid chromatography (LC) method was developed. In this method, carboxylic acids were automatically and fluorescently derivatized with 4‐(N,N‐dimethylaminosulfonyl)‐7‐piperazino‐2,1,3‐benzoxadiazole (DBD‐PZ) in the presence of 4‐(4,6‐dimethoxy‐1,3,5‐triazin‐2‐yl)‐4‐methylmorpholinium chloride by adopting a pretreatment program installed in an LC autosampler. All of the DBD‐PZ‐carboxylic acid derivatives were separated on the ODS column within 30 min by gradient elution. The peak of DBD‐PZ did not interfere with the separation and the quantification of all the acids with the exception of lactic acid. From the LC‐MS/MS analysis, we confirmed that lactic acid was converted to an oxytriazinyl derivative, which was further modified with a dimethoxy triazine group of 4‐(4,6‐dimethoxy‐1,3,5‐triazin‐2‐yl)‐4‐methylmorpholinium chloride (DMT‐MM). We detected this oxytriazinyl derivative to quantify lactic acid. The detection limits (signal‐to‐noise ratio = 3) for the examined acids ranged from 0.19 to 1.1 µm , which correspond to 95–550 fmol per injection. The intra‐ and inter‐day precisions of typical, highly polar carboxylic acids were all <9.0%. The developed method was successfully applied to the comprehensive analysis of carboxylic acids in various samples, which included fruit juices, red wine and media from cultured tumor cells. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
144.
Naohide Sakimura Takahiro Ohashi Kiyoshi Ohishi Toshimasa Miyazaki 《Optical Review》2014,21(5):578-584
Recently, the scaling up of the storage capacity and data transfer rate of digital storage media has been required. However, increasing in the storage capacity and transfer rate makes optical head control more difficult. Thus, a tracking control system for optical discs must exhibit a high degree of precision control. Consequently, a new two-stage feedforward control (TSFFC) system for high-precision control is proposed in this paper. The proposed system is constructed using two zero phase error tracking (ZPET) control systems based on error prediction and an error-based disturbance observer (EDOB) that uses a notch filter to suppress non periodic disturbances. The proposed control system is designed for DDU-1000 for digital versatile discs (DVDs). The experimental results demonstrate that the proposed system effectively suppresses tracking errors. 相似文献
145.
Natsuru Chikushi Emiko Ohara Ayako Hisama Hiroyuki Nishide 《Macromolecular rapid communications》2014,35(10):976-980
Network polymers of cobaltporphyrin derivatives are prepared by a facile click reaction via the Michael addition of acetoacetate‐substituted tetraphenyl cobaltporphyrin and tri‐ or tetra‐acrylates. The conversion is saturated for 1 h in the presence of a catalyst, which almost reaches the same gelation point of the formed network polymers. Deeply and homogeneously red‐colored membranes with a sub‐micrometer thickness are yielded on a porous supporting membrane. They are still tough even with a very high content of the rigid porphyrin residue. The oxygen permeability is high, at 10–100 Barrer, and the oxygen/nitrogen permselectivity (PO2/PN2) is significantly enhanced with the porphyrin content reaching 30, for the membranes with ca. 70 wt% porphyrin content.
146.
Mariko Kitajima Satoko Ohara Noriyuki Kogure Dammrong Santiarworn Hiromitsu Takayama 《Tetrahedron》2013
Six new β-carboline-type indole alkaloid glycosides, ophiorrhisides A–F (1–6), were isolated from Ophiorrhiza trichocarpon (Rubiaceae) collected in Thailand. Ophiorrhisides A (1) and B (2) possess a lactam function in the C ring and a unique biose residue in the molecule. Ophiorrhiside F (6) has a highly oxidized C ring with a 1,2-dicarbonyl function at C-5 and C-6 positions as well as a double bond between C-3 and C-14. 相似文献
147.
Koichi Inoue Nuntawat Prayoonhan Haruhito Tsutsui Tasuku Sakamoto Maiko Nishimura Toshimasa Toyo'oka 《Journal of separation science》2013,36(8):1356-1361
Dichlorprop is available for agricultural use as a chiral pesticide. In this study, the stereoselective determination of dichlorprop enantiomers in tea samples such as green, black, jasmine, and oolong was developed by ultra performance LC with fluorescence spectrometry after covalent chiral derivatization. The separation was achieved on an Acquity BEH C18 column with the mobile phase consisting of 0.1% formic acid in acetonitrile/water at a flow rate of 0.4 mL/min. In the covalent chiral derivatization using (S)‐(+)‐4‐(N,N‐dimethylaminosulfonyl)‐7‐(3‐aminopyrrolidin‐1‐yl)‐2,1,3‐benzoxadiazole, the peak resolution between the S and R‐dichlorprop enantiomers was 2.6. LODs and LOQs values were 10 and 50 ng/mL standard solution. The linearity of the calibration curves yielded the coefficients (r2 > 0.99, ranging from 0.05 to 5 μg/mL) of determination of each of the dichlorprop enantiomers. SPE extraction was used for the sample preparation of dichlorprop in various tea samples. Recoveries were in the range of 82.4–97.6% with associated precision values (within‐day: 82.4–95.8%, n = 6, and between‐day: 83.7–97.6% for 3 days) for repeatability and reproducibility. Based on this result, our method has been proven to be highly efficient and suitable for the routine assay of dichlorprop enantiomers in various tea samples. We propose that the ultra performance LC assay after covalent chiral derivatization would be the renewed tools in the era of chiral stationary platform for chiral pesticide residues in foods. 相似文献
148.
To improve the selectivity of closed cracks for objects other than cracks in ultrasonic imaging, we propose an extension of a novel imaging method, namely, subharmonic phased array for crack evaluation (SPACE) as well as another approach using the subtraction of responses at different external loads. By applying external static or dynamic loads to closed cracks, the contact state in the cracks varies, resulting in an intensity change of responses at cracks. In contrast, objects other than cracks are independent of external load. Therefore, only cracks can be extracted by subtracting responses at different loads. In this study, we performed fundamental experiments on a closed fatigue crack formed in an aluminum alloy compact tension (CT) specimen using the proposed method. We examined the static load dependence of SPACE images and the dynamic load dependence of linear phased array (PA) images by simulating the external loads with a servohydraulic fatigue testing machine. By subtracting the images at different external loads, we show that this method is useful in extracting only the intensity change of responses related to closed cracks, while canceling the responses of objects other than cracks. 相似文献
149.
Let G=(V,E) be an undirected graph with a node set V and an arc set E. G has k pairwise disjoint subsets T1,T2,…,Tk of nodes, called resource sets, where |Ti| is even for each i. The partition problem with k resource sets asks to find a partition V1 and V2 of the node set V such that the graphs induced by V1 and V2 are both connected and |V1∩Ti|=|V2∩Ti|=|Ti|/2 holds for each i=1,2,…,k. The problem of testing whether such a bisection exists is known to be NP-hard even in the case of k=1. On the other hand, it is known that if G is (k+1)-connected for k=1,2, then a bisection exists for any given resource sets, and it has been conjectured that for k?3, a (k+1)-connected graph admits a bisection. In this paper, we show that for k=3, the conjecture does not hold, while if G is 4-connected and has K4 as its subgraph, then a bisection exists and it can be found in O(|V|3log|V|) time. Moreover, we show that for an arc-version of the problem, the (k+1)-edge-connectivity suffices for k=1,2,3. 相似文献
150.
A conjugate numerical model proposed by Nakayama et al. for the steady problem of cooling a fluid flowing through a coiled
tube, has been successfully extended to investigate two distinctive thermal problems, namely, the transient cooling processes
associated with a beer dispenser, and the transient processes of heat storage and recovery associated with a packed bed saturated
with a molten salt. An axisymmetric numerical procedure is adopted for determining the velocity and temperature fields within
the chilled water bath of the beer dispenser. A simplified one-dimensional heat transfer model is introduced for coupling
the tube flow with the recirculating flow in the bath. A similar axisymmetric finite difference procedure is applied for the
heat transfer analysis of the packed bed saturated with a molten salt. For the heat recovery process, a one-dimensional heat
balance equation for the two-phase flow with a helically-coiled tube is introduced to update the wall surface temperatures,
which are needed to calculate the temperature field in the saturated packed bed. The numerical results for both thermal systems
associated with coiled tubes agree very well with the corresponding velocity and temperature data obtained from the experiments.
Received on 28 August 2000 / Published online: 29 November 2001 相似文献