Shigeru Kurosawa

Oscillating frequency of piezoelectric quartz crystal in solutions

Oscillating frequencies of a piezoelectric crystal were measured in various solutions. One side of the crystal surface was coated with a silicon sealant. This coating was useful for measuring the oscillation of crystals in solutions for a wide range of products of density (ϱ) and viscosity (η) and in electrolyte solutions. For measurement in solutions, the frequency change depended on the circuit used, whereas for measurements in air the circuit did not influence the frequency change. All experimental data showed that the frequency change from pure water, ΔFw, followed ΔFw = − K(√ϱη − √ϱwηw) except for electrolyte and polymer solutions, where K is a proportionality constant, ηw the density of pure water and ηw the viscosity of water.

Adsorption and desorption of F(ab′)2Anti-hIgG on plasma-polymerized allylamine thin film: The application of the film to immunoassay

The plasma-polymerization technique can easily modify the characteristics of the surface of materials. Here, allylamine thin film was formed on a flat glass plate (referred to as ALAM(GLA)) by plasma-polymerization. Adsorption of F(ab′)2anti-human IgG (hIgG) onto ALAM(GLA) and desorption of the protein from ALAM(GLA) were investigated. ALAM(GLA) was used as a solid phase in two-site immunoradiometric assay (IRMA) of human serum IgG. The following results were obtained: (i) The adsorption of F(ab′)2anti-hIgG onto ALAM(GLA) or GLA was a Langmuir type. The binding constant (a) and the saturation concentration (b) for the protein onto ALAM(GLA) were 5.6 × 105 l mol−1 and 264.2 nmol m−2, respectively. For GLA,a andb were 3.5 × 105 l mol−1 and 26.1 nmol m−2, respectively. The saturated level of ALAM(GLA) was about 10 times larger than that of GLA. (ii) The within-lot coefficient of variation (CV) of the adsorption of F(ab′)2anti-hIgG onto ALAM(GLa) was 1.1–3.7% (n = 8) and the between-lot CV was 3.5% (n = 3). (iii) The adsorption of F(ab′)2anti-hIgG was independent of the power of glow-discharge in plasma-polymerization. (iv) The surface of ALAM(GLA) was as flat and smooth as that of GLA. (v) The desorption of and the exchange of F(ab′)2anti-hIgG adsorbed onto ALAM(GLA) was small. (vi) The ALAM film was transparent for visible light from 400 to 800 nm. (vii) The values of IgG in human sera measured by the two-site IRMA using ALAM(GLA) as a solid phase were compared with those obtained with laser nephelometry (LNM); the correlation coefficient was 0.929 (P < 0.01) and the equation for the line of regression wasY = 0.801 X + 1.35.

Resonant frequency of a piezoelectric quartz crystal in contact with solutions

Abstract The resonant frequency of a piezoelectric crystal was determined by transmission measurements. The simple principle of this resonance method is that a transmission is measured at varying frequencies with a two-port transmission line system containing parallel resistance. Previous workers formulated the resonant frequency of a quartz crystal and the equation derived indicated that the frequency is dependent on (ρη) 1 2 and F 3 2 b , where ρ, η and F b are the density and viscosity of the solution and the fundamental frequency of the quartz crystal, respectively. The resonance method was applied to solutions of varying (ρη) 1 2 , and it is concluded that the equation holds for a wide range of different solutions. The resonance method is advantageous in solutions over the widely used conventional oscillation method because the range of (ρη) 1 2 for possible measurements is much wider.

Detection of actomyosin depolymerization with a piezoelectric quartz crystal

Abstract A resonance method was previously proposed to measure the frequency change of piezoelectric quartz crystals [S. Kurosawa et al., Anal. Chim. Acta , 274 (1993) 209]. The ordinary method which incorporates the crystal into an oscillator circuit is here referred to as the oscillation method. Viscosity changes during the depolymerization of actomyosin can be detected by a piezoelectric quartz crystal because its frequency change is sensitive to the viscosity in a solution. This change is not detectable by the oscillation method (using TTL circuit), but may be detected by the resonance method using a ‘spectrum analyzer’, which shortens the analysis time, compared with the technique described earlier.

Plasma-polymerized membrane electrode selective for lipophilic cations

Abstract With use of the plasma-polymerization technique, a thin membrane of ammonium tetraphenylborate (NH 4 TPB) was prepared. Results of elemental analysis and infrared and X-ray photoelectron spectra indicated that the essential structure of the monomer may remain. The membrane was formed on a Millipore membrane as the support. The membrane was impregnated with a water-immiscible organic solvent, such as dioctyl phthalate, o -nitrophenyl octyl ether or nitrobenzene. The e.m.f, generated between two solutions of lipophilic cations separated by the organic solvent-wetted membrane followed the Nernst equation in a concentration range between 10 −6 and 10 −2 M . The lipophilic cations used were tetraphenylphosphonium, quaternary ammonium and alkaloids. Since the ion exchanger itself was polymerized, its leakage was completely inhibited and the lifetime of the electrode was prolonged. No change in the calibration curve was observed after 6 months when the electrode was stored in distilled water.

Detection of actomyosin depolymerization by piezoelectric quartz crystal: Possibility for development of a meat-freshness sensor

Abstract Frequency changes of a piezoelectric quartz crystal were observed with the resonance method (S. Kurosawa et al., Anal. Chim. Acta, 274 (1993) 209–217), when actomyosin from fresh carp was depolymerized by addition of ATP (adenosine 5′-triphosphate). On the other hand, no frequency changes were observed when long-stored actomyosin was used, suggesting that the present system may be applicable for a meat-freshness sensor. We failed to observe the frequency changes with the ordinary method (oscillation method) which incorporates the crystal into an oscillator circuit.

Ab initio molecular orbital study on monofluorination reaction of hydrofluorocarbons over cobalt trifluoride

Theoretical studies on monofluorination reactions of hydrofluorocarbons (HFCs) over CoF 3 were carried out by ab initio molecular orbital calculation. The energy of radical intermediates in monofluorination was determined. The results obtained are consistent with the experimental regioselectivity of monofluorination for geminal-difluoro HFCs of C 2 ∼ C 4 over CoF 3