Low-temperature specific heat of crystalline and amorphous Eu2(MoO4)3

The specific heat C _total of crystalline and amorphous Eu₂(MoO₄)₃ is measured in the temperature interval 4.5–30 K. The amorphous state is obtained by applying pressure ∼7 GPa at room temperature. It is found that the specific heat of the crystal at T⩽7.5 K is described by a cubic function of temperature, while the specific heat of the amorphous sample has a strongly non-Debye character in the entire experimental temperature interval. The curve of C _total for amorphous europium molybdate is analyzed in a model of soft atomic potentials, and it is shown that it agrees well with universal low-temperature anomalies of the specific heat of classical glasses obtained by quenching from the liquid. Pis’ma Zh. éksp. Teor. Fiz. 68, No. 8, 623–627 (25 October 1998)     

Interaction between indigo and adsorbed protein as a major factor causing backstaining during cellulase treatment of cotton fabrics

A model microassay system was developed to measure indigo backstaining on cotton fabrics in the presence of enzymes on a small laboratory scale. Backstaining indexes for 11 cellulase samples were measured, and the enzymes were ranked from lower to higher backstaining. Two multienzyme cellulase preparations were separated into fractions using chromatofocusing on a Mono P column. Adsorption ability and backstaining properties of purified enzyme fractions were studied. Evidence was obtained that protein adsorption on cotton fabrics is a crucial parameter causing backstaining (both for crude cellulase samples and purified enzyme components).     

Evaluation of cellulase preparations for hydrolysis of hardwood substrates

Seven cellulase preparations from Penicillium and Trichoderma spp. were evaluated for their ability to hydrolyze the cellulose fraction of hardwoods (yellow poplar and red maple) pretreated by organosolv extraction, as well as model cellulosic substrates such as filter paper. There was no significant correlation among hydrolytic performance on pretreated hardwood, based on glucose release, and filter paper activity. However, performance on pretreated hardwood showed significant correlations to the levels of endogenous β-glucosidase and xylanase activities in the cellulase preparation. Accordingly, differences in performance were reduced or eliminated following supplementation with a crude β-glucosidase preparation containing both activities. These results complement a previous investigation using softwoods pretreated by either organosolv extraction or steam explosion. Cellulase preparations that performed best on hardwood also showed superior performance on the softwood substrates.     

Determination of glucose and lactose in food products with the use of biosensors based on Berlin blue

The immobilization of enzymes into polyelectrolyte membranes with the use of organic solvents was applied to the development of the biosensing elements of biosensors. The following domestically produced preparations were used: the enzymes glucose oxidase and β-galactosidase and a perfluorosulfonated polymer. The compositions of mono-and bienzymic polyelectrolyte membranes were optimized. The glucose and lactose biosensors based on Berlin blue (as a signal transducer) and polyelectrolyte membranes exhibited high sensitivity, low detection limits, and fast response. The results of the analysis of milk whey in a flow-injection system that included biosensors completely correlated with measurement data obtained by a standard chromatographic technique.     

A principal component analysis of transmission spectra of wine distillates

A chemometric method of decomposing multidimensional data into a small-sized space, the principal component method, has been applied to the transmission spectra of vintage Moldovan wine distillates. A sample of 42 distillates aged from four to 7 years from six producers has been used to show the possibility of identifying a producer in a two-dimensional space of principal components describing 94.5% of the data-matrix dispersion. Analysis of the loads into the first two principal components has shown that, in order to measure the optical characteristics of the samples under study using only two wavelengths, it is necessary to select 380 and 540 nm, instead of the standard 420 and 520 nm, to describe the variability of the distillates by one principal component or 370 and 520 nm to describe the variability by two principal components.     

Isotope Effect on Diffusion in Nafion Studied by NMR Diffusometry

Applied Magnetic Resonance - The isotope effect H → D on diffusion in proton-exchange membrane Nafion 212 is investigated using 1H and 2H nuclear magnetic resonance (NMR)...     

Interference synthetic-aperture radars for routine monitoring of ocean phenomena

We consider the principles of radar sounding of the ocean surface using interferometers to reconstruct the level and velocity fields on the ocean surface. Likelihood functions are used to calculate the optimal algorithm of useful-signal isolation and the potential threshold sensitivity of interference synthetic-aperture radars with respect to the fields of the velocity and level of the ocean surface, depending on the instrumental, trajectory, and natural factors. The possibility to use space observations to reconstruct both small-scale fields of the altitude and the orbital velocity of energy-carrying wind waves and mesoscale fields, e.g., the field of altitudes of seismic gravity waves and the velocity field of geostrophic currents, is considered.