Direct Shocks in a Vibrationally Nonequilibrium Gas

Direct shocks in flows of a high-temperature diatomic gas with rotational and vibrational degrees of freedom are considered. Gas-dynamic parameters and populations of molecular vibrational levels behind a shock are studied for the case of disturbance of vibrational equilibrium in an incident flow.     

Influence of transfer,release, and absorption of energy on vortex properties of ideal fluids

The vortex properties of ideal fluid flows are examined. It is shown that the barotropy assumption in classical theorems of the conservation of vortex properties of a fluid can be replaced by the adiabaticity assumption. In that case, the connection between the formation and evolution of anomalous atmospheric phenomena and significant violations of adiabaticity in the movement of air masses can be traced.     

Effect of vibrational excitation of molecules on the velocity of sound in a high-temperature diatomic gas

A formula for the velocity of sound, which is valid not only for barotropic gases, is derived on the basis of methods of the kinetic theory of gases. This formula is specified for various stages of relaxation of a high-temperature diatomic gas in the approximation of the model of anharmonic oscillators. A dependence between the populations of vibrational levels of molecules and the velocity of sound is found. __________ Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 49, No. 3, pp. 28–34, May–June, 2008.     

Immobilization of chymotrypsin on silver nanoparticles

Russian Chemical Bulletin - The method of immobilization of chymotrypsin based on the reduction reaction of silver nitrate with sodium borohydride in an aqueous medium in the presence of the enzyme...     

Model Kinetic Equations and the Description of Gas Flows at Various Relaxation Stages

Various relaxation stages in high-velocity and high-temperature gases with physicochemical processes are considered on the basis of model kinetic equations. Macroscopic equations are derived in the zero approximation of the modified Chapman–Enskog method and expressions for the flow members of gas-dynamic equations in terms of intensive and extensive parameters are deduced. A formula for the velocity of sound (as the velocity of propagation of small perturbations) is derived using the parameter æ, which is not a constant under the considered conditions.     

Multi micro high performance liquid chromatography

Summary The purpose of the study was to develop a micro HPLC system with physically changeable selectivity. This was done using two series-coupled beds of chemically differing stationary phases in a packed fused silica column. The selectivity change, in fine repeatable steps, was possible by the stepwise moving of a tube oven, covering only 50% of this tandem column. Each step of selectivity started with a position change of the oven, thus heating up a fresh position of the more polar and the non-polar column bed. As the chromatogram is thus repeated under these new selectivity conditions, multiple chromatograms result. For this reason we call the technique Multi Micro HPLC. This very simple mode of operation provides an analytical tool for developing separation conditions and which allows optimizing for a given special sample and checking for one of the most critical problems in HPLC: unidentified peak overlapping. The selectivity changes are nonlinearly correlated with the oven position with regards to temperature field distribution and are greater than is possible by simple change of column temperature. Micropacked columns are ideal for quick temperature changes. Elevated temperatures in HPLC help to shorten analysis time. The concepts discussed above provide an explanation of how a normal, formerly chemically homogeneous, column can become very temperature sensitive after detoriation at the inlet. In fact the column has become an unintentional tandem column and peak positions tend to move erratically as its selectivity changes drastically by inhomogeneous temperature changes along the separation path.