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181.
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183.
Ozone has become the oxidant of choice for water disinfection, especially in large water treatment facilities. This paper describes a fast and sensitive method for the determination of ozone content by reaction with photoactivated chromotropic acid (CA, 4,5-dihydroxynaphthalene-2,7-disulfonic acid), which results in intense chemiluminescence (CL). Freshly ozonated water from a recirculating ozonizer/reservoir is injected into a carrier stream of deionized water in the flow-injection mode. This flow mixes with a stream of photoactivated CA solution in a spiral cell placed directly on top of an inexpensive miniature (8 mm diameter active area) photomultiplier tube (PMT). Alkaline CA is photoactivated by passing it through a FEP-Teflon® coil (residence time ∼ 50 s) wrapped around a 1 W UV lamp emitting at 254 nm; without photoactivation, the signal is ∼70-fold lower. The S/N = 3 limit of detection for aqueous ozone is 3 μg l−1 and good response slope is obtained up to an ozone concentration of 1.4 mg l−1, the highest that could be made in this study. The response obeyed a quadratic equation with r2 = 0.9984. No interference from permanganate ion is observed. The proposed system was applied to the monitoring of ozonation status of a playa lake water that exhibited significant ozone demand. 相似文献
184.
Masao Shiozaki Yukiko Watanabe Toshio Kaneko Daisuke Tanaka Shin-ichi Kurakata 《Tetrahedron》2005,61(21):5101-5122
Lipid A analogues containing glucose in substitution for glucosamine on the reducing end were synthesized, and the inhibitory activities on LPS-induced TNFα production (LPS-antagonistic activity) in vitro using human whole blood cells were measured. The IC50 values (nM) of these ten compounds, 8, 14, 21, 31, 40, 51, 57, 62, 67 and 72, were 11.2, 15.4, 2.7, 0.1, 0.4, 1.3, 3.2, 3.2, 1.4 and 14.4, respectively. And also inhibitory activities (ID50) on TNFα production toward galactosamine loaded C3H/HeN mice in vivo of compounds 21, 31, 57, 62 and 67 were measured. The values of these compounds were 0.29, 0.50, 0.61, not dose-dependent and 0.33 mg/kg, respectively. 相似文献
185.
Kittaka S Takahara S Yamaguchi T Funel MC 《Langmuir : the ACS journal of surfaces and colloids》2005,21(4):1389-1397
The dynamics of water molecules in the layered vanadium pentoxide hydrate, V(2)O(5).nH(2)O, were studied by quasi-elastic neutron scattering (QENS) measurements. Heterogeneity of the dynamic properties was confirmed by alpha-relaxation model analysis. Translational diffusion of monolayer and double-layer water molecules is by site-to-site diffusion and is reduced relative to that of bulk water. Water molecules lose their mobility markedly and solidify with decreasing temperature. However, mobile water remains at 253 K. Rotational diffusion coefficients are unaffected by confinement and are very similar to the bulk values determined at temperatures in the range 253-298 K. The dynamic speed characterized by QENS is much faster than that expected from the data determined by deuterium NMR (DNMR) measurements at low temperatures. 相似文献
186.
Itoh T Shichi T Yui T Takagi K 《Langmuir : the ACS journal of surfaces and colloids》2005,21(8):3217-3220
The present investigation reports on the significant differences observed in the efficiency of the polymerization depending on the odd- or even-numbered methylene chains of diacetylenecarboxylates, CH3(CH2)(m-1)C[triple bond]C-C[triple bond]C(CH2)(n-1)CO2- (mono-[m,n]), incorporated in layered double hydroxide (LDH) clay. Upon gamma-ray irradiation of the diacetylenecarboxylates, or mono-[m,n], in LDH clay, polymer hybrids or poly-[m,n]/LDH, which exhibited coloring from light orange to violet, were obtained. The color of the poly-[m,n]/LDH hybrids was strongly dependent on the extent of the polymerization degrees. Moreover, the polymerization degrees were controlled by the number of methylene spacers n between the carboxyl and diacetylene groups. An odd-numbered n for the methylene chain of mono-[m,n] was found to be the determining factor in the efficient polymerization of these self-assembling aggregates within the interlayers of LDH clay. 相似文献
187.
188.
Scharlemann and Thompson introduced an invariant (K,) Q/2Z forthe pair of a knot K in the 3-sphere and an unknotting tunnel for K. The paper studies the relationship between the invariant(K, ) of a (1,1)-knot and the distance of its (1,1)-splittingintroduced by the author. 相似文献
189.
Kiyoshi Bannai Takeshi Toru Takeo Ba Toshio Tanaka Noriaki Okamura Kenzo Watanabe Seizi Kurozumi 《Tetrahedron letters》1981,22(15):1417-1420
Stable analogues of PGI2, 7-hydroxy- and 7-acetoxy-PGI2, were synthesized from protected PGI2 methyl ester via sulfoxides , through stereocontrolled sulfoxide-sulfenate rearrangement. 相似文献
190.
Tetrathiafulvalen (TTF) and tetraselenafulvalen (TSF) salts with diorganochloro-stannate anions, [TTF][SnEt2Cl3] (1), [TTF]2[SnPh2Cl4] (2), [TTF]3[SnEt2Cl4] (3), [TTF]3.3[SnPh2Cl4] (4), [TSF]2[SnPh2Cl4] (5) and [TSF]3.3[SnPh2Cl4] (6), were prepared by the reactions of [TTF or TSF]3[BF4]2 with SnR2Cl2 (R = Et or Ph) in the presence of [Ph3PCH2Ph]Cl and by electrocrystallization of TTF or TSF in acetonitrile containing SnR2Cl2 and [Ph3PCH2Ph]Cl. All the salts behave as semiconductors with electrical resistivities of the order of 10–108 Ω cm as compacted samples at 25°C. Electronic reflectance spectra of the simple salts 1, 2 and 5, show a band due to the dimeric(TTF+)2 or (TSF+)2 unit in the 12,200–12,800-cm?1 region. The complex salt 3 exhibits a TTF+/TTF° charge-transfer (CT) band at 8700 cm?1, and the remaining complex salts, 4 and 6, both display CT bands between the radical cations and between the radical cation and the neutral donor molecule. The crystal structure of 3 was determined by a single-crystal X-ray diffraction. The tetragonal crystal, space group I4cm, has cell dimensions a = 11.710(3) Å, c = 25.242(7) Å, and Z = 4. The structure was solved by the heavy-atom method and refined to a final R value of 0.082 for 479 independent reflections with >F° > 3σ(F). TTF molecules exist as trimers, in which a slight lateral shift from the eclipsed TTF overlap occurs, although TTF molecules are arranged with equal spacing between them. The trimer units are located perpendicularly to each other, forming a two-dimensional layer. The [SnEt2Cl4]2? anion is disordered with respect to the two SnEt and two SnCl bonds. 相似文献