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951.
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Masami Shibukawa Reiko Eto Akiko Kira Fusae Miura Koichi Oguma Hideki Tatsumoto Hisako Ogura Akira Uchiumi 《Journal of chromatography. A》1999,830(2):3588-328
An HPLC method has been developed for separation and determination of long alkyl chain quaternary ammonium compounds. A column packed with a hydrophilic polymer packing, Shodex Asahipak GF-310 HQ, and a water–acetonitrile mixture containing 4,4′-bipyridyl and hydrochloric acid were used to depress hydrophobic adsorption of the quaternary ammonium compounds and increase the sensitivity of the conductometric detection with a micromembrane suppressor. Dodecyltrimethylammonium, cetyltrimethylammonium, tetradecyldimethylbenzylammonium and stearyltrimethylammonium ions can be completely separated from one another and quantified at 0.1 nmol level. 相似文献
955.
A multichannel spectral imaging system consisting of dichroic mirrors is proposed. The system is expected to have the highest signal-to-noise ratio (SNR) because of the largest optical throughput realized by the multichannel configurations for both imaging and spectrometry. A multichannel spectral imaging system with eight spectral bands was designed by the evolutionary algorithms and then fabricated. The SNR is studied and compared experimentally with those of other fast spectral imaging techniques. A time-sequence of spectral images of a super-continuum light beam is measured using the present system. The number of spectral channels of the system is limited chiefly by the difficulty in designing the arrangement of dichroic mirrors and the optical performance of those mirrors. These limitations restrict the number of spectral channels to approximately 16 at present. 相似文献
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957.
Masahiro Teraguchi Miyako Ohtake Hiroshi Inoue Akiko Yoshida Toshiki Aoki Takashi Kaneko Koji Yamanaka 《Journal of polymer science. Part A, Polymer chemistry》2005,43(11):2348-2357
We synthesized two kinds of chiral polystyrene‐based monoliths, which are macroporous gel with continuous open‐celled monolith structure. Thus, two chiral styrene monomers, (–)‐p‐[dimethyl(10‐pinanyl)silyl]styrene ((–)‐PSSt) and (–)‐p‐(menthoxycarbonyl)styrene ((–)‐MtSt]), were prepared and subjected to water‐in‐oil emulsion polymerization in the presence of divinylbenzene and AIBN. The macroporous structure of the obtained monoliths was directly confirmed by SEM observation. The obtained monoliths showed an optical resolution ability. That is, in the enantioselective adsorption using trans‐stilbene oxide, poly[(–)‐PSSt] monolith and poly[(–)‐MtSt] monoliths preferentially adsorbed (S,S)‐isomer [poly[(–)‐PSSt] monolith: α(S,S) = 1.49 (0.25 wt % acetone solution); poly[(–)‐MtSt] monolith: α(S,S) = 1.39 (0.25 wt % toluene solution)]. Depinanylsilylation of the poly[(?)‐PSSt] monolith and removal of menthyl groups from the poly[(–)‐MtSt] monolith were achieved by acid‐catalyzed scission of the Si? C bond and base‐catalyzed hydrolysis, respectively. In addition, de‐poly[(–)‐PSSt] and de‐poly[(–)‐MtSt] showed enantioselectivity ((S,S)‐isomer preferentially absorbed) in adsorption using trans‐stilbene oxide in spite of the absence of chiral substituents in the monoliths. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2348–2357, 2005 相似文献
958.
Ken‐Ichi Seno Akiko Date Shokyoku Kanaoka Sadahito Aoshima 《Journal of polymer science. Part A, Polymer chemistry》2008,46(13):4392-4406
The judicious choice of reaction conditions permitted living cationic polymerization of vinyl ethers with bulky and strongly interacting pendant groups, such as crystalline long alkyl chains and liquid crystalline mesogenic structures, using appropriate combinations of Lewis acids with added bases. Thus, well‐defined random and block copolymers with various pendants were also synthesized. Highly sensitive UCST‐type phase separation in various organic solvents was achieved employing crystallization of octadecyl pendants of homopolymers and random copolymers. This phase separation behavior is unusual for a polymer‐organic solvent system. Furthermore, thermally induced reversible physical gelation was conducted using this thermosensitive behavior. These specific pendants were very effective not only in organic media but also in water, in obtaining hydrogels with relatively low polymer concentrations. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4392–4406, 2008 相似文献
959.
A radio-frequency (RF) ion trap has been constructed for high resolution laser spectroscopy of metallic ions. Ions in externally
generated laser plasma have been directly introduced into the RF ion trap. An Nd:YAG laser is used to vaporize and ionize
sample metals placed behind a ring electrode. Both hyperbolic and cylindrical electrodes are successfully used for confinement
of the ions. Trapped ions are detected either with a quadrupole mass spectrometer or with a photomultiplier for the measurement
of laser-induced fluorescence. Metallic ions such as Ca+, Ba+, La+, Nd+, Tm+, Lu+, and Ta+ have been confined for the time range of several to 20 minutes in the presence of He buffer gas, and a doubly charged ion
Ba2+ for several seconds. Some ions like Nd+, Lu+, Hf+, and Ta+ are found to be highly reactive with background gaseous molecules. 相似文献
960.