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1.
Hirohisa Yokota Kenji Kamoto Jun-ichi Igarashi Norihiko Mouri Yutaka Sasaki 《Optical Review》2002,9(1):9-12
A new configuration for an ASE reduction filter in EDFA repeaters for WDM optical transmission systems using optical fiber grating couplers (FGCs) was proposed and first demonstrated. The filtering characteristics of the proposed filter for amplified single wavelength signal and 2-channel WDM signals using EDFA were identified. It was found that the filter was effective to improve SNR in optical domain by reducing ASE noise. The required FGC characteristics for the filter were theoretically predicted under the condition that the total filter loss did not exceed 3 dB. More than 70% of drop efficiency was required in each FGC for the application of the proposed filter to an 8-channel WDM system using EDFA repeaters. 相似文献
2.
Jaime Pfretzschner Pedro Cobo Francisco Simón María Cuesta Alejandro Fernández 《Applied Acoustics》2006,67(1):62-73
Microperforated panels (MPPs) coupled to a rigid wall have been proposed recently as an alternative to porous absorbers in situations having concerns with bacterial contamination and small particles discharge, like food, pharmaceutical and microelectronic industries. There exists also an increasing interest for MPP absorbers in the transportation industry and civil engineering. In general, an optimally designed MPP with good broadband absorption requires many submillimetric holes distributed over a panel of also submillimetric thickness. Such thin plates or foils become so fragile that they need to be protected from mechanical damage. In this paper, an alternative strategy is investigated which allows the design of MPPs with panels of millimetric thickness while maintaining their acoustic performance. These absorbers, named microperforated insertion units (MIUs), avoid the structural problems of the classical MPPs. An assessment of the sound absorption properties of these structures is presented. Comparisons between calculations and measurements are also made under two experimental conditions: plane waves at normal incidence (impedance tube) and free field (anechoic room). 相似文献
3.
Ntaoleng M. Makunya Reinout Meijboom Alfred Muller 《Journal of organometallic chemistry》2005,690(18):4159-4167
Cyclopentadienyldicarbonylmethyliron, [CpFe(CO)2Me] (1), undergoes migratory carbonyl insertion under the influence of isosteric phosphine ligands P(4-FC6H4)3 and P(4-MeC6H4)3. The products of the reaction, [CpFe(CO)(COMe)P(4-FC6H4)3] (2a) and [CpFe(CO)(COMe)P(4-MeC6H4)3] (2b), were characterised by X-ray crystallography. In both structures, the iron atom adopts a pseudo octahedral coordination geometry. Fe-P bond distances are the same at 2.1932(8) Å in 2a and 2b, respectively. Thus, contrary to what was expected, X-ray data could not be used to quantitatively differentiate between the two phosphine ligands in 2a and 2b. Therefore, additional spectroscopic techniques such as IR and NMR were employed. Similarly, the Fe-C bond lengths of the carbonyl (Fe-CO) and acetyl (Fe-COMe) are 1.748(3) and 1.955(3) in 2a, and 1.744(3) and 1.951(3) Å in 2b, respectively.The migratory carbonyl insertion was studied by NMR, IR, and UV-vis spectroscopies to determine the mechanism and the rate law. Results from NMR spectroscopy show that the formation of the product is accompanied by oxidation of the corresponding phosphine ligand. An increase in the reactivity of migratory carbonyl insertion for P(4-MeC6H4)3 was observed when the solvent was changed from CH2Cl2 to MeCN. The kinetic data showed that P(4-MeC6H4)3 reacts faster than P(4-FC6H4)3. 相似文献
4.
A family of organic polychalcogenides with a common structure of RSeSxSeR (with x=1, 2, 3 and R=CH3, Ph, PhCH2, O2NC6H4CH2) as well as cyclic 5,5-dimethyl-1,2-dithia-3,7-diselenacycloheptane were synthesized in good yield and high purity from the reaction of Ph3CSxCl with corresponding diselenides in chloroform at room temperature. Mechanistic aspects of the insertion involving the formation of an intermediate (RSeSxCPh3) are discussed. 相似文献
5.
6.
We present an efficient entanglement purification protocol (EPP) with controlled-not (CNOT) gates and linear optics. With the CNOT gates, our EPP can reach a higher fidelity than the conventional one. Moreover, it does not require the fidelity of the initial mixed state to satisfy F>1/2. If the initial state is not entangled, it still can be purified. With the linear optics, this protocol can get pure maximally entangled pairs with some probabilities. Meanwhile, it can be used to purify the entanglement between the atomic ensembles in distant locations. This protocol may be useful in long-distance quantum communication. 相似文献
7.
《Journal of Coordination Chemistry》2012,65(1-3):249-259
Abstract The photochemical insertion of phenylacetylene with the “tied-back” dinuclear complex [(η5-C5H4)2SiMe2]Fe2(CO)2(μ-CO)2 (4) yields, by X-ray structural analysis, a dimetallacyclopentenone product entirely analogous to that obtained from the photochemical reaction of the alkyne with (η5 - C5H5)2Fe2(CO)2(μ-CO)2 (1). This result is interpreted as evidence for an alternative pathway for photochemical alkyne addition to 1. Attempts to identify the photochemical intermediates from 4 have been unsuccessful. A competition study between 1 and 4 indicates that photochemical alkyne insertion into 1 is preferred by approximate ratio of 2:1 over insertion into 4. 相似文献
8.
AbstractA convenient and efficient procedure for the synthesis of 2-substituted-6,7-dihydrobenzo[d]oxazol-4(5H)-ones and 2-aryl-6,7-dihydrobenzofuran-4(5H)-ones through a Rh2(OAc)4-catalyzed C≡X (X?=?N, C) insertion of cyclic 2-diazo-1,3-diketones with nitriles and aromatic alkynes has been developed. This reaction uses readily available starting materials and stable cyclic 2-diazo-1,3-diketone compounds, with desired products formed in good to high yields. A tentative mechanism involving a C≡X bond insertion and 1,5-dipolar electrocyclization/ring opening and cyclization sequence for this reaction is proposed. 相似文献
9.
Derek C. Church Jonathan K. Pokorski 《Angewandte Chemie (International ed. in English)》2020,59(28):11379-11383
Cell‐based therapies are gaining prominence in treating a wide variety of diseases and using synthetic polymers to manipulate these cells provides an opportunity to impart function that could not be achieved using solely genetic means. Herein, we describe the utility of functional block copolymers synthesized by ring‐opening metathesis polymerization (ROMP) that can insert directly into the cell membrane via the incorporation of long alkyl chains into a short polymer block leading to non‐covalent, hydrophobic interactions with the lipid bilayer. Furthermore, we demonstrate that these polymers can be imbued with advanced functionalities. A photosensitizer was incorporated into these polymers to enable spatially controlled cell death by the localized generation of 1O2 at the cell surface in response to red‐light irradiation. In a broader context, we believe our polymer insertion strategy could be used as a general methodology to impart functionality onto cell‐surfaces. 相似文献
10.
Mami Miyairi Tsuyoshi Taniguchi Tatsuya Nishimura Katsuhiro Maeda 《Angewandte Chemie (International ed. in English)》2020,59(35):14772-14780
An alternative reaction mechanism of the polymerization of diphenylacetylelnes using a catalytic system composed of tungsten(VI) chloride and tetraphenyltin has been proposed through the optimization of reaction conditions and investigation of the effect of the electronic nature of diphenylacetylene monomers on the polymerizability. The detailed structures of the polymers have been suggested by mass spectrometric analysis of the obtained polymers and oligomers, which suggested that a phenyl group of tetraphenyltin has been introduced to an initiating end of the polymer chain. Mass spectrometric analysis also provided information about the termination processes of the polymerization. The experimental results strongly suggested that the polymerization of diphenylacetylenes using tungsten(VI) chloride and tetraphenyltin proceeds through a migratory insertion mechanism rather than the long‐accepted metathesis mechanism. 相似文献