Showing papers by "Yuki Yoshida published in 2010"
TL;DR: A novel rhodium-catalyzed linear codimerization of alkyl phenyl ketenes with internal alkynes to dienones and a novel synthesis of furans by an unusual cycloaddition of diaryl ketenes as well as other reactions proceed smoothly with the same r Rhodium catalyst, RhCl(PPh3)3.
Abstract: A novel rhodium-catalyzed linear codimerization of alkyl phenyl ketenes with internal alkynes to dienones and a novel synthesis of furans by an unusual cycloaddition of diaryl ketenes with internal alkynes have been developed. These reactions proceed smoothly with the same rhodium catalyst, RhCl(PPh3)3, and are highly dependent on the structure and reactivity of the starting ketenes.
10 citations
TL;DR: By reformulating the system model using the widely linear representation and employing the auxiliary variable resampling (AVR) technique for estimation of the imperfections, the blind MPF detector is successfully modified to cope with the analog imperfections.
Abstract: Recently, the marginalized particle filter (MPF) has been applied to blind symbol detection problems over selective fading channels. The MPF can ease the computational burden of the standard particle filter (PF) while offering better estimates compared with the standard PF. In this paper, we investigate the application of the blind MPF detector to more realistic situations where the systems suffer from analog imperfections which are non-linear signal distortion due to the inaccurate analog circuits in wireless devices. By reformulating the system model using the widely linear representation and employing the auxiliary variable resampling (AVR) technique for estimation of the imperfections, the blind MPF detector is successfully modified to cope with the analog imperfections. The effectiveness of the proposed MPF detector is demonstrated via computer simulations.
4 citations
TL;DR: In this paper, a new tantalum-based catalyst was proposed for the selective trimerization of ethylene without the use of aluminum compounds or alkylating organometallic reagents.
Abstract: The oligomerization of ethylene is of considerable scientific and industrial interest as a route to linear and branched alkenes. Linear alkenes, especially 1-hexene, are key intermediates in the production of plasticizers, detergents, and surfactants, as well as comonomers for the production of linear lowdensity polyethylene (LLDPE), whereas branched alkenes are of interest as high-octane additives to motor fuel. In the traditional transition metal complex-catalyzed oligomerization of ethylene, the formation of alkene mixtures (C4–C16 alkenes) [4] is unavoidable due to a mathematical distribution (Schulz–Flory or Poisson). Therefore, specific alkenes must be obtained by fractional distillation. The known ethylene trimerization catalysts are based mainly on chromium compounds with nitrogen, oxygen, and/or sulfur ligands, as well as mono(cyclopentadienyl)titanium(II) complexes. Sen and co-workers reported the first simple “ligandless” tantalum-based catalyst, and Mashima and co-workers recently reported a modified tantalum catalyst using 3,6-bis(trimethylsilyl)-1,4-cyclohexadiene (BTCD) or its methyl derivative (MBTCD). Aside from Mashima’s catalyst, all of the trimerization catalysts reported to date have required large amounts of aluminum compounds such as methylaluminoxane (MAO) or other alkylating organometallic reagents such as (CH3)2Zn as a conventional catalyst activator. In sharp contrast, there are few examples of the trimerization of ethylene to branched C6 alkenes, isohexenes, and only two catalyst systems for this procedure, [NiBr2(PPh3)2]/ CH3AlCl2 [12] and [Pd(acac)2]/BF3·OEt2 (acac = acetylacetonate), [13] have been reported to date. We have previously developed several codimerizations and cotrimerizations of different alkenes with high atom efficiency. Among these, the unusual head-to-head dimerization of styrenes and linear codimerization of styrenes with ethylene proceeded smoothly with a zero-valent ruthenium catalyst, [Ru(h-cot)(h-dmfm)2] [15] (cot = 1,3,5-cyclooctatriene, dmfm = dimethyl fumarate), in the presence of primary alcohols to give (E)-1,4-diaryl-1-butenes and (E)-1-aryl-1-butenes, respectively, without aluminum compounds or alkylating organometallic reagents. We believe that these reactions proceed via ruthenacyclopentane intermediates derived from the oxidative cyclization of styrenes and/or styrenes with ethylene on an active ruthenium center. This result prompted us to develop a novel catalyst system for the selective trimerization of ethylene without the use of aluminum compounds or alkylating organometallic reagents. Firstly, the [Ru(h-cot)(h-dmfm)2]-catalyzed trimerization of ethylene (4.05 MPa) was examined in mesitylene at 110 8C for 24 h in the presence of 1-octanol to specifically give C6 alkenes (selectivity = 95 %, TON= 56), together with a small amount of butenes (selectivity = 5 %; Scheme 1). No alkenes larger than C8 were obtained at all.
3 citations
01 Dec 2010
TL;DR: In this paper, the authors demonstrate RZ-BPSK modulation format conversion based on fiber nonlinearity to suppress the effects of walk-off and parametric gain, and investigate the timing and dispersion tolerance at the bit rate of 107Gb/s.
Abstract: We experimentally demonstrate RZ-BPSK modulation format conversion based on fiber nonlinearity To suppress the effects of walk-off and parametric gain, we design the parameters of HNLF, probe and control pulses We investigate the timing and dispersion tolerance at the bit rate of 107Gb/s
31 Aug 2010
TL;DR: In this paper, the authors demonstrate RZ-BPSK modulation format conversion based on fiber nonlinearity, and investigate the timing and dispersion tolerance at the bit rate of 10.7Gb/s.
Abstract: We experimentally demonstrate RZ-BPSK modulation format conversion based on fiber nonlinearity. To suppress the effects of walk-off and parametric gain, we design the parameters of HNLF, probe and control pulses. We investigate the timing and dispersion tolerance at the bit rate of 10.7Gb/s