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191.
A kinetic study has been made of the gas phase, I2-catalyzed decomposition of (CH3)2S at 630–650 K. Some I2 is consumed initially, reaching a steady-state concentration. The initial major products are CH4 and CH2S together with small amounts of CH3SCH2I, CH3I, HI, and CS2. The initial reaction corresponds to a pseudo-equilibrium: accompanied by: and which brings (I2) into steady state and a final complex reaction: From the initial rate of I2 loss it is possible to obtain Arrhenius parameters for the iodination: We measure k1, (644 K) = 150 L/mol s and from both the Arrhenius plot and independent estimates A1 (644 K) = 1011.2 ± 0.3 L/mol s. Thus, E1 = 26.7 ± 1 kcal/mol. From the steady-state I2 concentration, an assumed mechanism and the known rate parameters for the CH3I/HI system. It is possible to deduce KA (644) = 3.8 × 10?2 with an uncertainty of a factor of 2. Using an estimated ΔS (644) = 4.2 ± 1.0 e.u. we find ΔHA (644) = 7.0 ± 1.1 kcal. With 〈ΔCPA〉644 = 1.2 this becomes: ΔHA(298) = 6.6 ± 1.1 kcal/mol. Then ΔH (CH3SCH2I) = 6.3 ± 1 kcal/mol. Making the assumption that E?1 = 1.0 ± 0.5 kcal/mol we find ΔH (644) = 25.7 ± 0.7 kcal/mol and with 〈ΔCPI〉 = 1.2; ΔH = 25.3 ± 0.8 kcal/mol. This gives ΔH (CH3S?H2) = 35.6 ± 1.0 kcal/mol and DH (CH3SCH2? H) = 96.6 ± 1.0 kcal/mol. This then yields Eπ(CH2S) = 52 ± 3 kcal. From the observed rate of pressure increase in the system and the preceding data k3, is calculated for the step CH3SCH2 → CH3 + CH2S. From an estimated A-factor E3 is deduced and from the overall thermochemistry values for k?3 and E?3. A detailed mechanism is proposed for the I-atom catalyzed conversion of CH2S to CS2 + CH4. 相似文献
192.
G. Ning S. Aditya P. Shum L. Cheng H. Dong 《Applied physics. B, Lasers and optics》2008,90(1):137-140
We propose novel photonic microwave multi-tap filters using a section of Hi-Bi fiber in a round-trip configuration, together
with their application in a 20 km single mode fiber (SMF) radio-over-fiber (RoF) link. We demonstrate for the first time that
the effect of chromatic dispersion in these multi-tap filters can be reduced in an RoF link when a linearly chirped fiber
Bragg grating (FBG) is adopted. This result can be used to combat radio frequency power fading in an RoF link. The configurations
are free from optical coherent interference and phase noise. Measured results show 3-tap filters with notch rejections greater
than 35 dB and suppression of the level of secondary sidelobes by adjusting a polarization controller.
PACS 42.81.-I; 42.81.Gs; 07.50.Qx 相似文献
193.
In this survey, we first present a brief overview of logical algebras. We then discuss concepts of single-valued neutrosophic $K$-subalgebras, single-valued neutrosophic soft $K$-algebras and single-valued neutrosophic topological $K$-algebras. Moreover, we discuss various fundamental concepts which include interior, closure, $C{_5}$-connectivity, super connectivity, compactness and Hausdorffness of single-valued neutrosophic topological $K$-algebras. 相似文献
194.
In [Jain, S.: Array codes in the generalized-Lee-RT-pseudo-metric (the GLRTP-metric), to appear in Algebra Colloq.], Jain introduced a new pseudo-metric on the space Matm×s(Zq), the module space of all m × s matrices with entries from the finite ring Zq, generalized the classical Lee metric [Lee, C. Y.: Some properties of non-binary error correcting codes. IEEE Trans. Inform. Theory, IT-4, 77- 82 (1958)] and array RT-metric [Rosenbloom, M. Y., Tsfasman, M. A.: Codes for m-metric. Prob. Inf. Transm., 33, 45-52 (1997)] and named this pseudo-metric as the Generalized-Lee-RT-Pseudo-Metric (or the GLRTP-Metric). In this paper, we obtain some lower bounds for two-dimensional array codes correcting CT burst array errors [Jain, S.: CT bursts from classical to array coding. Discrete Math., 308-309, 1489-1499 (2008)] with weight constraints under the GLRTP-metric. 相似文献
195.
R. Pittini J. X. Shen Y. Oka W. Ossau Kai Shum 《Physica E: Low-dimensional Systems and Nanostructures》2000,6(1-4)
We report on a field-dependent photoluminescence (PL) emission rate for the transitions between band states in modulation-doped CdTe/Cd1−xMgxTe single quantum wells in the integer quantum Hall region. The recombination time observed for the magneto-PL spectra varies in concomitance with the integer quantum Hall plateaus. Furthermore, different PL decay times were observed for the two circular polarizations, i.e. for the transitions between the Zeeman split subbands of the Landau levels. We analyzed the data in comparison with the experimentally determined spin polarization of the conduction electrons and the Zeeman splitting of the valence band. Furthermore, we discuss the relevance of the spin polarization of the conduction electrons, the electron–hole exchange interaction and the spin-flip processes of the hole states for the PL decay time. 相似文献
196.
Single SOA based all-optical adder assisted by optical bandpass filter: Theoretical analysis and performance optimization 总被引:1,自引:0,他引:1
Jianji Dong Songnian Fu Xinliang Zhang P. Shum Liren Zhang Jing Xu Dexiu Huang 《Optics Communications》2007,270(2):238-246
A simple and compact configuration of all-optical adders implemented with a single semiconductor optical amplifier (SOA) and optical bandpass filter (OBF) is presented in this paper. A comprehensive SOA model is put forward to investigate the output characteristics of the all-optical adders. The numerical simulation results demonstrate the influence of these key parameters, including input pulse peak power, pulsewidth, repetition rate, and OBF characteristics. Moreover some design rules are extracted for the proper selection of these parameters so as to ensure optimum performance. The obtained results confirm the feasibility of our configuration. 相似文献
197.
Let G be a finite group and H a subgroup of G. Then H is said to be S-permutable in G if HP = PH for all Sylow subgroups P of G. Let HsG be the subgroup of H generated by all those subgroups of H which are S-permutable in G. Then we say that H is S-embedded in G if G has a normal subgroup T and an S-permutable subgroup C such that T ∩ H HsG and HT = C. Our main result is the following Theorem A. A group G is supersoluble if and only if for every non-cyclic Sylow subgroup P of the generalized Fitting subgrou... 相似文献
198.
We report, for the first time to our knowledge, the presence of concentration-induced nonuniform power in tunable erbium-doped fiber lasers. A theoretical model is proposed with pair-induced quenching taken into account. We obtain good agreement between numerical and experimental results of a high-concentration erbium-doped fiber ring laser with a large tuning range of over 100 nm. These findings are useful for the design of lasers with doped fibers. 相似文献
199.
200.
Received February 18, 2005 We report the fabrication of phase-shifted long-period fiber gratings by use of a CO2 laser with a surface deformation technique and a point-by-point method. Due to periodicities that are structurally induced by a heat source and refractive-index modulation caused by a perturbational photoelastic effect, the results of thermal testing show a grating temperature coefficient of 28 pm/ degrees C at a range from 22 to 180 degrees C, indicating that the band rejections of the grating that is formed remain unchanged in their resonant strengths even at temperatures up to the fictive point of fiberglass. It is found for what is believed to be the first time that such a grating possesses an anomalous strain behavior of resonance with -1.52 x 10(-4) dB/muepsilon for the right notch and 7.05 x 10(-5) dB/muepsilon for the left notch. 相似文献