Microchemical determination of lodate and iodide in sea waters by flow injection analysis

A flow injection analysis method for iodate and iodide in sea water is described. The system involves spectrophotometric detection based on the catalytic, fading effect of either iodate or iodide on the indicator reaction of iron (III) thiocyanate and nitrite. With and without an anion-exchange column in the flow conduit, the system allows the determination of iodate and total iodine, respectively; iodide can be found by difference. Both iodate-iodine and total iodine can be determined in the range 0.75 to 150 g/1 on the sea water basis with analysis times of 20 min for iodate-iodine and 9 min for total iodine. The RSDs are within 1.3% for both iodate and iodide. Results are presented for the determination of iodate and iodide in sea waters and some brines associated with natural methane gas evolution.     

Automated odor-sensing system based on plural semiconductor gas sensors and computerized pattern recognition techniques

Although odor is an inherent characteristic of chemical substances, no methods to measure or identify odor objectively have been available. A computerized method for classification and identification of odor is reported. Odors are detected by using eight semiconductor gas-sensor elements which have different sensing properties for gases; the output from the odor-detecting apparatus for a gas sample is represented by an 8-dimensional vector. The vectors for 30 substances were examined by clustering analysis and four obvious clusters were observed. These clusters corresponded to ethereal, etherealminty, ethereal-pungent and pungent substances.     

Co-L3 X-ray absorption near-edge structure analysis of Pr1−xCaxCoO3−δ and Pr1−xSrxCoO3−δ

The valence state of Co ions in Pr_1−xCa_xCoO_3−δ and Pr_1−xSr_xCoO_3−δ has been investigated by an analysis of the Co-L₃ X-ray absorption near-edge structure (XANES) profile. The observed intensity distributions of Co-L₃ XANES change continuously with increasing concentration of alkaline-earth ions. To investigate the origin of this change in the XANES profile, charge transfer multiplet calculations were carried out, which could successfully explain the change in the spectral profile; they also suggest that the valence state of Co ions in Pr_1−xCa_xCoO_3−δ and Pr_1−xSr_xCoO_3−δ is between 3+ and 4+ and increases gradually with the concentration of alkaline-earth ions.     

Intergrain ordering processes of YBa2Cu4O8 and related complex ceramic systems

Intergrain ordering phenomena of frustrated ceramic YBa₂Cu₄O₈ (Y124) and dual phase mixed ceramic containing CuO are studied by both magnetic and resistivity observations. Magnetically estimated intergrain ordering temperature T_c2 and zero-resistivity attainment temperature T_z are both decreased with CuO content. However, it is also revealed that mutual location of T_c2 and T_z is changed. For the mixed ceramic with torn intergrain network structure, T_z stays above T_c2, indicating local dissolution of frustration by cluster structure. On the other side, remaining resistivity tails blow T_c2, indicating intrinsic fluctuation effect on the resistivity caused by frustration in the ordered state. It is known then that, superconductive ceramic samples which is free from structural phase inhomogeneity is essential in order to clarify the frustration effect.     

On the first pontrjagin class of homotopy complex projective spaces

Let M ²ⁿ be a closed smooth manifold homotopy equivalent to the complex projective space ℂP(n). It is known that the first Pontrjagin class p ₁(M) of M ²ⁿ has the form (n+1+24α(M))u ² for some integer α(M) where u is a generator of H ²(M; ℤ). We prove that α(M) is even when n is even but not divisible by 64.     

Potential Operators in Weighted Herz-Type Spaces over Locally Compact Vilenkin Groups

Let G be a bounded locally compact Vilenkin group. We study the boundedness of potential operators and the maximal operators associated with them in the weighted Herz space, the weighted Hardy space and the weighted Herz-type Hardy space over G. We also discuss the boundedness of these operators on the weighted weak Lebesgue space and the weighted weak Herz space whose sharpness are also discussed. This revised version was published online in June 2006 with corrections to the Cover Date.     

Experimental study on turbulent natural convection heat transfer in water with sub-millimeter-bubble injection

Using thermocouples and a particle tracking velocimetry technique, temperature and velocity measurements are conducted to investigate flow and heat transfer characteristics of turbulent natural convection from a vertical heated plate in water with sub-millimeter-bubble injection. Hydrogen-bubbles generated by the electrolysis of water are used as the sub-millimeter-bubbles. In the turbulent region, the heat transfer deterioration occurs for a bubble flow rate Q = 33 mm³/s, while the heat transfer enhancement occurs for Q = 56 mm³/s. Temperature and velocity measurements suggest that the former is caused by a delay of the transition due to the bubble-induced upward flow. On the other hand, the latter is mainly due to two factors: one is the enhancement of the rotation of eddies in the outer layer, and the other is the increase in the gradient of the streamwise liquid velocity at the heated wall. These are caused by bubbles, which are located in the inner layer, rising at high speed.     

Retention behavior of monosaccharides and disaccharides on titania

Summary The ability of titania to recognize the position of hydroxyl groups was previously found to result from the formation of a chelate ring between a titanium ion and the two oxygen atoms of the hydroxyl group and carboxylate anion of 2-hydroxycarboxylic acids. We investigated how titania could recognize the position of hydroxyl group of monosaccharides and disaccharides. The retention behavior of monosaccharides and disaccharides on titania was found to be characteristic. Thus, sucrose was eluted much faster than the other sugars, whereas D-ribose, D-fructose and L-sorbose were most strongly retained on titania of all of the sugars tested. It is apparent that the sugars strongly retained on titania have an axial hydroxyl group or neighboring hydroxyl groups of the same conformation.     

Design and synthesis of a hydrophilic fluorescent derivatization reagent for carboxylic acids, 4-N-(4-N-aminoethyl)piperazino-7-nitro-2,1,3-benzoxadiazole (NBD-PZ-NH2), and its application to capillary electrophoresis with laser-induced fluorescence detection

A hydrophilic fluorescent derivatization reagent for fatty acids, 4-N-(4-N-aminoethyl)piperazino-7-nitro-2,1,3-benzoxadiazole (NBD-PZ-NH(2)), was designed and synthesized. NBD-PZ-NH(2) possesses not only a fluorophore and a reacting group but also a positive charge group and, thus, was hydrophilic and suitable for application to capillary electrophoresis. NBD-PZ-NH(2) reacted with fatty acids in the presence of triphenylphosphine (TPP) and 2,2'-dipyridyl disulfide (DPDS) at room temperature within 10 min. The derivatives were strongly fluoresced and were positively charged at pH below 3. The derivatives of C4-C20 fatty acids were separated within 10 min in 50% acetonitrile in water containing 30 mM ammonium acetate and 1.0 M acetic acid by capillary electrophoresis with laser-induced fluorescence (CE-LIF) detection. The detection limits attained were 6.5 nM (signal-to-noise ratio of 3). It is proposed that NBD-PZ-NH(2) is a prominent derivatization reagent for fatty acids which is suitable for CE-LIF application.