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81.
It is shown that timing jitter owing to the Gordon-Haus (G-H) effect of solitons that are compressed adiabatically in dispersion-decreasing fibers (DDF's) is approximately determined by total dispersion and initial conditions, which are independent of compression dynamics. As a result the established theory for G-H jitter is still applicable. Timing jitter near the levels predicted by theory is observed in pulses from a regeneratively mode-locked fiber laser compressed in a DDF. 相似文献
82.
Ultrashort-pulse fiber ring lasers 总被引:4,自引:0,他引:4
L.E. Nelson D.J. Jones K. Tamura H.A. Haus E.P. Ippen 《Applied physics. B, Lasers and optics》1997,65(2):277-294
Received: 18 February 1997/Revised version: 22 April 1997 相似文献
83.
A physical model based on the sound production mechanism of the sho is proposed with intention of applying it to sound synthesis. Time-domain simulation was done using this model, and effects of the tube length and blowing pressure on the sounding frequency and sounds spectra were investigated. The reed vibration, pressure variation inside the tube, and threshold blowing pressure for oscillation were measured by artificially blowing air into the sho. The experimental results are in acceptable agreement with simulation results in terms of the relationships between tube length and threshold pressure and between tube length and the sounding frequency. In addition, recorded sound waveforms and simulated ones have a common feature in the sense that high-frequency components of their spectra increase with increasing blowing pressure. Further, it is concluded that a sho reed acts as an "outward-striking valve." 相似文献
84.
Akikawa H Ajimura S Chrien RE Eugenio PM Franklin GB Franz J Gang L Imai K Khaustov P May M Pile PH Quinn B Rusek A Sasao J Sawafta RI Schmitt H Tamura H Tang L Tanida K Yuan L Zhou SH Zhu LH Zhu XF 《Physical review letters》2002,88(8):082501
With a germanium detector array (Hyperball), we observed two gamma-ray peaks corresponding to the two transitions (5/2(+)-->1/2(+) and 3/2(+)-->1/2(+)) in the (9)(Lambda)Be hypernucleus which was produced by the 9Be(K-,pi(-)) reaction. The energies of the gamma rays are 3029 +/- 2 +/- 1 keV and 3060 +/- 2 +/- 1 keV. The energy difference was measured to be 31.4(+2.5)(-3.6) keV, which indicates a very small Lambda-spin-dependent spin-orbit force between a Lambda and a nucleon. This is the smallest level splitting by far ever measured in a hypernucleus. 相似文献
85.
86.
In this paper, we introduced a method to measure grain rotation of nanomaterials under external stress using a high pressure diamond anvil cell and the Laue microdiffraction technique at a synchrotron facility. We used tungsten carbide marker crystals to investigate grain rotation activities of 3 and 500?nm nickel media. Our results show that the grain rotation of 3 and 500?nm nickel nanocrystals increase with pressure and finally rotation of 500?nm nickel tends to stop at a lower pressure/stress level than 3?nm nickel. 3?nm nickel nanocrystals show a higher rotation magnitude than 500?nm nickel nanocrystals. Our measurements show an effective method to study the grain rotation of nanomaterials especially in ultrafine nanocrystals. 相似文献
87.
Minoru Koyama Dr. Takafumi Kawakami Dr. Takashi Okazoe Prof. Dr. Kyoko Nozaki 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(46):10913-10917
Methacrylic esters, represented by methyl methacrylate (MMA), are widely used as commodity chemicals. Here, the one-pot synthesis of methacrylic esters from acetone, a haloform and alcohols in the presence of an organic base is described. Using DBU as the organic base for the reaction of acetone, chloroform and methanol in acetonitrile afforded MMA in 66 % yield. When the solvent was replaced by benzonitrile, the product MMA was successfully purified by distillation. Applicability of this process to various alcohols was also investigated to show ethyl, phenyl, CF3CH2, and n-C6F13CH2CH2 esters were obtained in moderate yields. The use of bromoform instead of chloroform resulted in the improvement of the yield, for example, methyl and n-C6F13CH2CH2 esters up to 81 and 70 %, respectively. The reaction with deuterated starting materials acetone-d6 and MeOH-d4, with DBU in acetonitrile afforded deuterated MMA (MMA-d8) in 70 % yield. 相似文献
88.
Prof. Dr. Yasuchika Hasegawa Takafumi Matsui Dr. Yuichi Kitagawa Dr. Takayuki Nakanishi Dr. Tomohiro Seki Prof. Dr. Hajime Ito Prof. Dr. Yuta Nakasaka Prof. Dr. Takao Masuda Prof. Dr. Koji Fushimi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(53):12308-12315
Oxygen-sensitive and near-infrared (NIR) luminescent YbIII coordination polymers incorporating ligands based on pyrene derivatives were synthesized: YbIII–TBAPy and YbIII–TIAPy (TBAPy: 1,3,6,8-tetrakis(p-benzoate)pyrene; TIAPy: 1,3,6,8-tetrakis(3,5-isophthalic acid)pyrene). The coordination structures of these materials have been characterized by means of electrospray ionization mass spectrometry, X-ray diffraction analysis, and thermogravimetric analysis. Moreover, the porous structure of YbIII–TIAPy has been evaluated by measuring its N2 adsorption isotherm. The NIR luminescence properties of YbIII–TBAPy and YbIII–TIAPy have been examined by acquiring emission spectra and determining emission lifetimes under air or argon and in vacuo. YbIII–TIAPy exhibited high thermal stability (with a decomposition temperature of 400 °C), intense luminescence (with an emission quantum yield under argon of 6.6 %), and effective oxygen-sensing characteristics. These results suggest that NIR luminescent YbIII coordination polymers prepared using pyrene derivatives could have applications in novel thermo-stable oxygen sensors. 相似文献
89.
90.
Youko Tamura Li Sheng Satoshi Nakazawa Tomoya Higashihara Mitsuru Ueda 《Journal of polymer science. Part A, Polymer chemistry》2012,50(20):4334-4340
A series of polystyrenes with phosphonic acid ( 5 ) via long alkyl side chains (4, 6, and 8 methylene units) were prepared by the radical polymerization of the corresponding diethyl ω‐(4‐vinylphenoxy)alkylphosphonates, followed by the hydrolysis with trimethylsilyl bromide. The resulting phosphonated polystyrene membranes had a high oxidative stability against Fenton's reagent at room temperature. The membranes prepared from 5 exhibited a very low water uptake, similar to that of Nafion 117 over the wide range of 30 to 80% relative humidity (RH). The proton conductivities of these membranes are lower than that of Nafion 117 in the range of 30 to 90% RH, but comparable or higher than those of the reported phosphonated polymers with higher IEC values, such as the phosphonated poly(N‐phenylacrylamide) (PDPAA, IEC: 6.72 mequiv/g) and fluorinated polymers with pendant phosphonic acids (M47, IEC: 8.5 mequiv/g), at low RH conditions despite the much lower IEC values (3.0–3.8 mequiv/g) of these membranes. These results suggest that the flexible pendant side chains of 5 would contribute to the formation of hydrogen‐bonding networks by considering the very low water uptake of these polymers. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 相似文献