Inclusion complexation of octaethyl-p-tert-butylcalix[8]arene octaacetate with methylene blue and control of its inclusion ability by alkali metal cations

The equilibrium constants for the inclusion complexation of octaethyl-p-tert-butylcalix[8]arene octaacetate (Calix-B8-EA) with methylene blue (MB) were determined spectrophotometrically. Calix-B8-EA, which has a flexible hydrophilic pseudo-cavity formed by polyfunctional esters on the lower rim, is an effective receptor for alkali and alkaline-earth cations, and its ester carbonyl group forms the complex with metal cations. We have examined the ability to include the organic molecule (methylene blue (MB)) into the upper main cavity of Calix-B8-EA formed the complex of alkali metal cations with ester carbonyl groups on the lower rim. It was found that Calix-B8-EA forms a 1:1 inclusion complex of MB with the upper main cavity and, in the presence of excess alkali metal cations, the association constants increase with an increase in the size of the metal cations complexed with the polyfunctional groups on the lower rim. Further, the structure of the inclusion complex of MB with cation-complexed Calix-B8-EA is characterized by 2D ROESY-NMR measurements. Based on the results, we have demonstrated the control of the inclusion ability by changing the portal size of the calixarene cavity.     

40 Gb/s, secure optical communication based upon fast reconfigurable time domain spectral phase en/decoding with 40 Gchip/s optical code and symbol overlapping

We propose and experimentally demonstrate a 40 Gb/s secure optical communication system with on-off-keying (OOK) modulation format by using a time domain spectral phase en/decoding scheme, which employs a highly dispersive element and high-speed phase modulator for introducing significant symbol overlapping for both the encoded and incorrectly decoded noiselike signals to enhance the information security against eavesdropping using a power detector. The influence of dispersion and chip modulation rate on the symbol overlapping of the incorrectly decoded signal has been analytically investigated and experimentally verified. Security enhancement for 40 Gb/s OOK data using fast reconfigurable 40 Gchip/s optical codes with code lengths of up to 1024 has been demonstrated and compared with a 10 Gb/s system.     

Synthesis of monodispersed cubic magnetite particles through the addition of small amount of Fe into Fe(OH)2 suspension

Magnetite particles were synthesized through a process including dissolution of Fe(OH)₂ and precipitation of an oxidized phase in aqueous solution. The Fe³⁺ ion was added at the beginning of the synthesis to accelerate the formation of magnetite, control the particle size and improve the monodispersibility. It was found that the addition of Fe³⁺ ion affected the nucleation and the formation of magnetite particles significantly. Magnetite nanoparticles with small particle size and narrow size distribution were obtained. Furthermore, high magnetic properties were obtained in small particle size. The particle size and magnetic properties increased through the increase of Fe²⁺/Fe³⁺ ratio.     

Ab initio molecular orbital study of Fe(CO) n (n = 1–3)

Geometry optimization was performed for the ground states of FeCO, Fe(CO)₂, and Fe(CO)₃ at various levels of ab initio calculations, and the bond lengths and dissociation energies obtained were in reasonable agreement with experimental results. The nature of bonding was studied for these molecules using a complete-active-space self-consistent-field method. From the Mulliken population analysis, it was found that the traditional donation and back donation mechanism is valid for these molecules, including Fe(CO)₃, which has a pyramidal structure. Received: 27 September 1999 / Accepted: 13 January 2000 / Published online: 19 April 2000     

Synthesis of end‐functionalized poly(phenylacetylene)s with well‐characterized palladium catalysts

End‐functionalized poly(phenylacetylene)s were synthesized by the polymerization of phenylacetylene (PA) using the well‐defined palladium catalysts represented as [(dppf)PdBr(R)] {dppf = 1,1′‐bis(diphenylphosphino)ferrocene}. The Pd catalysts having a series of R groups such as o‐tolyl, mesityl, C(Ph)?CPh₂, C₆H₄‐o‐CH₂OH, C₆H₄‐p‐CN, and C₆H₄‐p‐NO₂ in conjunction with silver triflate polymerized PA to give end‐functionalized poly(PA)s bearing the corresponding R groups in high yields. The results of IR and NMR spectroscopies and MALDI‐TOF mass analyses proved the introduction of these R groups at one end of each polymer chain. The poly(PA) bearing a hydroxy end group was applied as a macroinitiator to the synthesis of a block copolymer composed of poly(PA) and poly(β‐propiolactone) moieties. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Development of ion transportation, extraction and neutralization systems for atomic beam resonance method

A device that produces a low-energy and largely spin polarized RI beam based on the atomic beam resonance method (RIABR) has been developed. We have performed measurements of stopping and drifting an incoming RI ion beam in a gas chamber, extraction of the ions into a vacuum region, and neutralization of the extracted low-energy ion beam. The drift efficiency of RI ions in a gas and the extraction efficiency at a Laval-type glass nozzle were found to be 0.72±0.04 and 0.033, respectively. The result of the experiment for the neutralization is also discussed.     

Automated optimization of split ratio in capillary gas chromatography

An electronic gas-flow controller system called Advanced Flow Control (AFC), which controls not only carrier gas pressure at the column inlet but also the total gas flow including the split flow, was designed and evaluated. BASIC programming of repetitive analyses of standard mixtures under varied split ratios and pressure programs allowed automated optimization of those conditions for the desired column loading and resolution between adjacent peaks.     

Universal generation of higher-order multiringed Laguerre-Gaussian beams by using a spatial light modulator

Laguerre-Gaussian (LG) beams of various higher-order radial modes are generated by using a reflective phase-only liquid crystal on silicon (LCOS) spatial light modulator (SLM). Because of the LCOS SLM's phase-modulation characteristic of a wide spatial bandwidth, a phase modulation scheme effectively generates higher-order LG beams of up to the fifth-order radial mode. We also perform correlation analyses between the observed and the theoretical two-dimensional mode profiles to universally obtain correlation coefficients of more than 0.946, which suggest mode generations of high quality.