Differences in the electrorheological response of a particle suspension under direct current and alternating current electric fields

We have observed an unusual reduction of shear stress with increasing shear rate under direct current electric fields, for an electrorheological fluid composed of sulfonated poly(styrene-co-divinylbenzene) particles dispersed in silicone oil. At all shear rates, the shear stress under the electric field is larger than that in the absence of the field, indicating that there is still some field-induced agglomeration of the particles. In contrast, the behavior under alternating current electric fields is the Bingham-fluid-type response commonly observed with electrorheological fluids. It is suggested that the conventional dipole–dipole interaction approach based on simplified microstructural models would be unable to explain these phenomena. Received: 27 November 2000 Accepted: 22 May 2001     

Acidic properties of V2O5-WO3/ZrO2 catalysts

The adsorption of pyridine on V₂O₅−WO₃/ZrO₂ has been studied by FTIR. In V₂O₅/ZrO₂ (2 wt.%), the number of both Br?nsted and Lewis acidic sites increased with the addition of WO₃, while in V₂O₅/ZrO₂ (5 wt.%), Br?nsted sites increased and Lewis sites did not change.     

On a geometrical method of construction of maximal t-linearly independent sets

The problem of constructing a maximal t-linearly independent set in V(r; s) (called a maximal L_t(r, s)-set in this paper) is a very important one (called a packing problem) concerning a fractional factorial design and an error correcting code where V(r; s) is an r-dimensional vector space over a Galois field GF(s) and s is a prime or a prime power. But it is very difficult to solve it and attempts made by several research workers have been successful only in special cases.In this paper, we introduce the concept of a {Σ_α=1^kw_α, m; t, s}-min · hyper with weight (w₁, w₂,…, w_k) and using this concept and the structure of a finite projective geometry PG(n ? 1, s), we shall give a geometrical method of constructing a maximal L_t(t + r, s)-set with length t + r + n for any integers r, n, and s such that n ? 3, n ? 1 ? r₀ ? n + s ? 2 and r₁ ? 1, where r = (r₁ + 1)v_n?1 ? r₀ and $\text{v}{}_{\mathrm{n}}\text{=}\text{(s}{}^{\mathrm{n}}\text{? 1)}\text{(s ? 1)}$.     

Size-exclusion SPR sensor chip: application to detection of aggregation and disaggregation of biological particles

We propose a novel surface plasmon resonance (SPR) sensor chip with a microfabricated slit array. The microslit excludes micrometre-size objects larger than its slit size from the SPR sensing area, so that it functions as an in situ filter. We demonstrated the sensing of microparticles of different diameters using the chip, and the results show a successful size-exclusion effect. As a demonstration of the biological application, we performed the detection of aggregation and disaggregation of biological particles using sugar-chain-immobilized gold nanoparticles as a test sample.     

Quantum yields for Cl(2P(j)) atom formation from the photolysis of chlorofluorocarbons and chlorinated hydrocarbons at 193.3 nm

Cl(2P(3/2)) and Cl*(2P(1/2)) atoms produced from the photodissociation of chlorofluorocarbons (CFCs) and chlorinated hydrocarbons at 193.3 nm have been detected quantitatively by a technique of vacuum ultraviolet laser-induced fluorescence (VUV-LIF) spectroscopy at 135.2 and 134.7 nm for j = 1/2 and 3/2, respectively. The quantum yields for total Cl-atom formation in the 193.3 nm photolysis at 295 +/- 2 K have been determined to be 1.03 +/- 0.09, 1.01 +/- 0.08, 1.03 +/- 0.08, 1.03 +/- 0.10, 1.41 +/- 0.14, 1.02 +/- 0.08, and 0.98 +/- 0.08 for CF2Cl2, CFCl3, CH2Cl2, CHCl3, CCl4, CHFCl2, and CCl3CF3, respectively. Those results suggest that the single C-Cl bond rupture always occurs in the photolysis of these molecules except for CCl4. Formation of two Cl atoms partly takes place in the photodissociation of CCl4. The quantum yields for total Cl-atom formation in the 193.3 nm photolysis of CHBr2Cl and CHBrClCF3 are 0.27 +/- 0.02 and 0.28 +/- 0.02, respectively, which suggests that the C-Br bond rupture is a main channel in the photodissociation processes. The branching ratios between the spin-orbit states, Cl*(2P(1/2)) and Cl(2P(3/2)), have also been determined for the photodissociation of the chlorinated compounds at 193.3 nm. The UV photodissociation processes giving rise to formation of Cl(2P(j)) atoms from the chlorinated compounds studied here have been discussed.     

Acidity and Structure of Ca-Doped V2O5/ZrO2 Catalysts

Acidity and structure of Ca-doped V₂O₅/ZrO₂ catalysts have been studied by FTIR. Both Lewis and Brønsted acidity decreased with Ca loading. New surface vanadate species seemed to be formed by Ca addition.     

Sonochemical production of a carbon nanotube

Sonochemical production of a carbon nanotube has been studied. The carbon nanotube is produced by applying ultrasound to liquid chlorobenzene with ZnCl₂ particles and to o-dichlorobenzene with ZnCl₂ and Zn particles. It is considered that the polymer and the disordered carbon, which are formed by cavitational collapse in homogeneous liquid, are annealed by the inter-particle collision induced by the turbulent flow and shockwaves.     

The determination of vanadium in steel samples by x-ray fluorescence spectrometry after precipitation with 4-caprinoyl-3-methyl-1-phenyl-5-pyrazolone

Vanadium(V) is quantitatively precipitated from aqueous solution with 4-caprinoyl-3-methyl-1-phenyl-5-pyrazolone at pH 1, and collected as a film on a membrane for x-ray fluorescence spectrometry. The limit of detection is ca. 2 μg of vanadium. The procedure gave satisfactory results on standard steels containing 0.003–0.091% vanadium.