Best constants in Korn-Poincaré's inequalities on a slab

We establish the best constants in the Poincaré-type and the trace-type inequalities for the quadratic form $ \lambda ||\,{\rm div}\,{\rm u}\,||_{L^2 }^2 \, + \,2\,\mu \,||\,\,(\nabla {\rm u}\, + \,\nabla {\rm u}^{\rm T})/2\,||_{L^2 }^2 $ which is fundamental in elasticity theory, on the space of H¹ vector fields u on a slab vanishing on one or both of its sides. We similarly calculate those constants for the case of H¹ divergence-free vector fields. Our method, which is fairly general, has another practical application to the quadratic form ∑_j,k(a^jk?_ku, ?_ju)_L² with coefficients a ^jk = a^kj ε C in H¹ scalar functions u on a slab.     

Atomization Characteristic of Chromium on a Molybdenum Tube Atomizer by Electrothermal Atomic Absorption Spectrometry and Determination of Chromium in Biological Materials

Atomization characteristics of chromium have been studied by electrothermal atomic absorption spectrometry with a molybdenum tube atomizer. The appearance temperature (T_app) of chromium nitrate was 1300°C. TheT_appwas independent of the heating rate of atomizer, but the temperature at the peak of the Cr AA signal increased with the heating rate. A sensitive absorption chromium signal was obtained in pure argon purge gas. The chromium signal decreased as the ratio of hydrogen in the purge gas increased. The optimal gas flow rate was Ar 480 ml min⁻¹+ H₂20 ml min⁻¹because of the avoidance of oxidation of the atomizer. The absolute characteristic mass (the mass of element giving 0.0044 abs.) of chromium by the atomizer was 0.35 pg and the detection limit was 23 pg ml⁻¹(3S/N). The interferences caused by large amounts of interferents were evaluated. The addition of thiourea served to eliminate the severe interferences. The accuracies of the recommended method were considered almost satisfactory for the determination of chromium in biological materials, compared with the certified values of NIST materials. The recovery of spiked chromium in biological materials was in the range from 93.5 to 102%.     

Applicability of micellar electrokinetic chromatography to the analysis of estrogens in water

Estrone, beta-estradiol and ethynylestradiol spiked in water were extracted using solid-phase extraction (SPE) and then directly determined by micellar electrokinetic chromatography (MEKC) with online concentration (sweeping). A 350 mL original sample volume (10 nM each) was concentrated to 1 mL using SPE, and ca. 240 nL of this solution was injected onto an MEKC capillary column. After sweeping, the estrogen related compounds were detected using a commercial absorbance detection system with an LOD of 0.16-0.30 nM in the original sample.     

Measurement of butyltin contamination of water and sediment in Osaka Bay,Japan

The concentration of tributyltin (TBT) in surface water from Osaka Bay ranged from 0.023 to 0.061 µg l⁻¹ in 1989 and from not detected (ND) to 0.059 µg l⁻¹ in 1990 while the proportion of TBT as a percentage of the total butyltins (BTs) was more than 40%. The concentration of TBT was also surveyed in the Port of Osaka and the Yodo River basin. TBT levels were highest in the estuary (the Port of Osaka), followed by sea areas (Osaka Bay) and rivers (Yodo River basin). A fairly high correlation coefficient between TBT concentration and salinity in water from the estuary and the sea areas was observed. This result shows that the TBT in the estuary water is diluted by seawater. Generally, the TBT concentrations in the water columns were distributed uniformly and the composition of the BTs was also constant. TBT was detected in sediment from Osaka Bay in the range from ND to 0.023 mg kg⁻¹ dry weight with a high ratio of monobutyltin (MBT) to the total BTs. TBT in sediment core was also measured; its concentration decreased with core depth. It was estimated from these measurements that the release of TBT into Osaka Bay began in the 1960s. Copyright © 1998 John Wiley & Sons, Ltd.     

Applicability of micellar electrokinetic chromatography to the analysis of estrogens in water

Estrone, β-estradiol and ethynylestradiol spiked in water were extracted using solid-phase extraction (SPE) and then directly determined by micellar electrokinetic chromatography (MEKC) with online concentration (sweeping). A 350 mL original sample volume (10 nM each) was concentrated to 1 mL using SPE, and ca. 240 nL of this solution was injected onto an MEKC capillary column. After sweeping, the estrogen related compounds were detected using a commercial absorbance detection system with an LOD of 0.16–0.30 nM in the original sample. Received: 15 September 2000 / Revised: 16 November 2000 / Accepted: 20 November 2000     

Asymmetric synthesis of beta-lactams using chiral-memory effect on photochemical gamma-hydrogen abstraction by thiocarbonyl group

Optically active beta-lactams were synthesized via photochemical intramolecular gamma-hydrogen abstraction reaction of thioimides involving a highly-controlled chiral-memory effect.     

Effect of ligand substituents in olefin polymerisation by half-sandwich titanium complexes containing monoanionic iminoimidazolidide ligands-MAO catalyst systems

Various half-sandwich titanium complexes containing iminoimidazolidide ligands, CpTiCl(2)[1,3-R(2)(CH(2)N)(2)C=N] (1a-d) [R = Ph (a), 2,6-Me(2)C(6)H(3) (b), cyclohexyl (c), (t)Bu (d)], have been employed as the catalyst precursors for ethylene polymerisation, syndiospecific styrene polymerisation, and copolymerisation of ethylene with 1-hexene in the presence of MAO cocatalyst; 1d showed the highest catalytic activity for ethylene polymerisation whereas 1b showed the highest activity for syndiospecific styrene polymerisation.     

Ru-catalyzed β-selective and enantioselective addition of amines to styrenes initiated by direct arene-exchange

A catalytic β-selective addition of amines to styrenes proceeded in the presence of cationic Ru complexes combined with diphosphine ligands. In the reaction of α-methylstyrene, an enantioselective addition was achieved by using xylylBINAP.