Ultrasonic Technique for Assessment of the Rim Tightness of Hydro Generator Rotor

At the hydroelectric unit No. 11 of the Nizhnekamsk hydroelectric power plant, the filling wedges of a rotor were investigated by ultrasound in the free st     

Magnetic-field effect on the rheological properties of strontium ferrite suspensions

The effect of a magnetic field and surfactants on the rheological properties of strontium ferrite suspensions has been studied. An applied magnetic field is shown to raise the suspension viscosity, which is attributable to the formation of three-dimensional chain structures made up of ferrite particles. After the magnetic field is removed, these structures do not fully break down, which leads to hysteretic behavior of the suspension viscosity. The introduction of polyelectrolytes reduces the viscosity of the suspension both in a magnetic field and after the field is removed. This is due to the formation of an electrical double layer on the particle surface, which reduces interparticle friction and the strength of the three-dimensional structures. The results of this study may be useful in devising processes for enhancing the texture and density of highly anisotropic strontium ferrite materials produced by wet pressing.     

Alcohol oxidase- and formaldehyde dehydrogenase-based enzymatic methods for formaldehyde assay in fish food products

For Gadoid fishes, formaldehyde can be generated in tissues in huge amounts during endogenous enzymatic degradation of natural osmoprotectant trimethylamine-N-oxide. This paper describes two enzymatic methods for assay of formaldehyde in fish food products using alcohol oxidase (AOX) and formaldehyde dehydrogenase (FdDH) isolated from the thermotolerant methylotrophic yeast Hansenula polymorpha. AOX-based method exploits an ability of the enzyme to oxidise a hydrated form of formaldehyde to formic acid and hydrogen peroxide monitored in peroxidase-catalysed colorimetric reaction. In FdDH-based method, a monitored coloured formazane is formed from nitrotetrazolium salt during reduction by NADH, produced in formaldehyde-dependent reaction. It was demonstrated an applicability of both methods for assay of formaldehyde in fish products. The optimal protocols for analysis procedures have been elaborated and analytical parameters of both enzymatic methods have been established. The both methods were demonstrated that some fish products (hake and cod) contain high formaldehyde concentrations (up to 100 mg/kg wet weight).