Determination of polycyclic aromatic hydrocarbons in sediment by liquid chromatography-atmospheric pressure photoionization-mass spectrometry.

We describe a method for the simultaneous determination of 12 kinds of polycyclic aromatic hydrocarbons (PAHs) in sediment based on liquid chromatography-atmospheric pressure photoionization-mass spectrometry (LC/APPI/MS). The method consists of PAH extractions by ultrasonics, clean-up by a solid-phase extraction procedure and determination by LC/APPI/MS. The limits of the determination for PAHs in sediment using the proposed method ranged from 0.06 to 0.9 mg/kg. PAHs were detected by this method in sediment samples on the mg/kg level.     

An all-solid-state tunable 214.5-nm continuous-wave light source by using two-stage frequency doubling of a diode laser

3 and β-BaB₂O₄ crystals. The power of the generated 214.5-nm light amounts to more than 100 μW. This light source will be used for laser cooling of Cd⁺ ions. Received: 4 August 1997/Revised version: 28 October 1997     

Isotope-selected measurements of the velocity-controlled Yb atomic beam

1 S₀→¹P₁ and ¹P₁→¹D₂ transitions were employed in this scheme. This method enabled precise measurement of the velocity distribution with the isotope selection and a higher resolution than our previous measurements using only the ¹S₀→¹P₁ transition. This technique was applied to the measurement of the Yb atomic beam whose velocity distribution was optically perturbed and compressed by radiation pressure. Received: 10 June 1996/Revised version: 19 July 1996     

Stereospecific,photochemical rearrangement of 1,1′-spirobiindene and 1,1′-spirobi[benzindene]S

The photochemical rearrangement, of optically active 3,3′-di-t-butyl-1,1?spirobiindene and ?1,1′-spirobi[benzindene]s afforded, respectively, 5,7-di-t-butylbenzo[c]fluorene and its dibenzo derivatives with high stereospecificity.     

Formation of a highly ordered dot array of surface micelles of a block copolymer via liquid crystal-hybridized self-assembly

A highly ordered dot array pattern of surface micelles on water is formed by a spread monolayer of an amphiphilic block copolymer, polystyrene-block-poly(4-vinylpyridine) (PS-4VP), via hybridization with a liquid crystal molecule, 4'-pentyl-4-cyanobiphenyl (5CB), on water. Simple co-spreading of PS-4VP with 5CB provides a flat homogeneous monolayer of PS-4VP on water without the aggregation of PS blocks. With increasing surface pressure, well-defined dots of the PS blocks start to grow and are arrayed in a highly ordered hexagonal structure. The exact coincidence of the surface pressure-area curves for the hybrid monolayer in the compression and expansion processes confirms that the flat spread monolayer and the dot array are formed on water in the equilibrium state by a self-assembly process.     

High Resolution FTIR Spectroscopy of DCCCl: Anharmonic Resonances in the nu(1) and nu(2) Bands

High-resolution infrared spectra of the nu(1) and nu(2) bands of DCCCl were observed using Bruker IFS 120HR Fourier transform spectrometers at resolutions of 0.0044 and 0.0035 cm(-1), respectively. For the DCC(35)Cl isotopomer, the nu(1) as well as the nu(2) band was found to be heavily perturbed. Detailed analyses revealed that the nu(1) state is in resonance with the l=0 substate of the nu(3)+4nu(4) state and that the nu(2) state is in resonance with the l=0 substate of the nu(3)+4nu(5) state. The rotational constants played a key role in identifying the perturbing states. In contrast, for the DCC(37)Cl isotopomer, the rotational structures of the nu(1) and nu(2) states are almost regular but slightly perturbed by interactions with the nu(3)+4nu(4) and nu(3)+4nu(5) states, respectively. The constants of resonances as well as the molecular constants for the nu(1), nu(2), nu(3)+4nu(4) and nu(3)+4nu(5) states were determined. Copyright 2001 Academic Press.     

Effect of spiroconjugation on the UV and CD spectra of 1,1′-spirobiindene

U.v. and c.d. spectra of 1,1′-spirobiindene were theoretically explained based on the composite molecule method. The effect of spiroconjugation was shown to appear markedly in the ¹L_a region of indene, making a large splitting of this band, as was expected from PE spectra.     

Synthesis and properties of polyurethanes derived from bis-N-hydroxyimides and diisocyanates

Polyurethanes were synthesized by polyaddition reaction of bis-N-hydroxyimides and diisocyanates. The reactions were carried out in an aprotic polar solvent such as dimethylacetamide or N-methyl-2-pyrrolidone, and the polymers with inherent viscosities of up to 1.32 dl/g were obtained. These polyurethanes were found to exhibit high reactivity toward nucleophiles such as water and amines, which brought about rapid reduction of viscosity. The stabilities against heat and exposure to sunlight were also studied.     

Aerobic oxidative dehydrogenation of coordinated imidazoline units of pincer ruthenium complex

A new pincer ruthenium complex (1; [RuL¹(tpy)](PF₆); L¹ = 1,3-di(2-imidazoline-2-yl)benzene, tpy = 2,2′:6′,2″-terpyridine) having a κ³NCN pincer ligand with two imidazoline units and related ruthenium complexes were synthesized and characterized. The imidazoline units of 1 were oxidized in air to give an imidazole-ligated pincer complex (2; [RuL²(tpy)](PF₆); L² = 1,3-di(2-imidazolyl)benzene). Results of the ¹H NMR spectroscopic and cyclic voltammetric studies of the complexes indicate that the σ-donor character of the pincer ligand of 1 induces the Ru-promoted oxidative dehydrogenation of coordinated imidazoline moieties to imidazole units with oxygen in air.     

Fluid Permeability in Stratified Unconsolidated Particulate Bed

Fluid permeability of polydisperse particulate bed with finite thickness has been examined. On the assumption of creeping flow, the permeability of monodisperse particles with arbitrary arrangement is calculated by means of Stokesian dynamics approach in which the interaction between individual particles and interstitial fluid is described by multipole expansion of the Oseen tensor. We have extended such calculation method to polydisperse particulate systems which have not so dense structures (up to particle volume fraction ${\phi \sim}$ 0.2). The particles are located infinitely in space and their interaction has been taken into account by Ewald summation technique. For the spatial distribution of polydisperse particles, we consider locally stratified particulate beds and define stratification degree as a parameter which apparently and mathematically represents the thickness of the mixing region of different-sized particles. The permeability profiles in the particulate beds with different stratification degree show the dependence of local permeability on the spatial and size distribution of particles. Consequently, the calculation results indicate that the permeability of non-uniform polydisperse particulate bed can be predicted by integrating the local permeation resistance which is determined by the local specific surface area.