Amplification of the vibrational motion of bodies in a stratified liquid

The motion in a liquid of a body having a vibrational degree of freedom may be accompanied by instability, namely, an excitation of vibrations through the energy of translational motion [1]. The possibility of such an instability is basically due to the emission of a vibrational component in the region of the ship angle _s, which satisfies the condition cos _s = U_ph/U, where U is the velocity of the translational motion and U_ph is the phase velocity of the wave at the given frequency. The motion of a small sphere (on an elastic spring parallel to the interface of two liquids) was examined in [1], and the importance of taking the viscosity and nonlinear effects into account was noted. Allowance for these factors is necessary in order to draw any realistic conclusions about the thresholds and nature of the aforementioned instabilitv. This question is examined in the present article in the context of a two-dimensional model of the motion of a circular cylinder perpendicular to its generator and parallel to the interface of two liquids of different densities (Fig. 1) under the action of a given force applied to the cylinder through a two-dimensional elastic spring. Such a model provides a greater understanding of the problem and enables the aforementioned questions to be examined analytically. In the present case the moving body is equivalent to a dipole source of the typeq=-Q (U+U cos t) z+H (x-Ut-a sin t) where U_v = a, Q = 2R², so that QU is the dipole moment corresponding to uniform motion of the cylinder. This expression is true for waves with wavelengths much greater than R.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza., No. 4, pp. 87–93, July–August, 1984.In conclusion, I wish to thank L. A. Ostrovskii for his valuable comments and discussion of the results.     

Intermolecular synergy effect on the inhibiting action of N-phenacylmethylquinolinium halides

The intermolecular synergy effect of N-phenacylmethylquinolinium halides on the corrosion of steel in 3 M H₂SO₄ solutions was studied.     

Inhibiting action of 1-phenacylmethyl-2-R-quinolinium bromides at steel acid corrosion

Inhibiting action of 1-phenacetylmethyl-2-R-quinolinium bromides at acid corrosion of steel was studied.     

Transformation of Short Waves in a Nonuniform Flow Field on the Ocean Surface. The Effect of Wind Growth Rate Modulation

We develop a model of transformation of the short surface wave spectrum in the presence of a nonuniform flow on a water surface, in which the modulation of wind-wave growth rate is taken into account. The model of a turbulent near-water atmospheric layer is used to calculate the modulated growth rate. In this model, turbulent stresses in the wind are described using a gradient approximation with model eddy viscosity specified with allowance for the known laboratory experiments. The examples of short-wave modulation in the presence of nonuniform flows on a water surface, originating from ripples and intense internal waves, are considered. It is shown that deformations of the wind-velocity profile and its long-wavelength perturbation due to the nonlinear interaction between the wind surface waves and the wind has a significant effects on the short-wave growth rate and its modulation. In the case of ripples, this deformation reduces to an increase in the roughness parameter of the wind-velocity profile and to a velocity-profile modulation with ripple period. The modulated growth rate is calculated within the framework of a quasi-linear model of surface-wave generation by a turbulent wind, in which the hypothesis of random phases of the wind-wave field is used. The amplitude and phase of the hydrodynamical modulation transfer function are calculated within the framework of the relaxation model. The calculation results are in reasonable agreement with the available experimental data. A model described by the combined Korteweg–de Vries equation is used to study a surface flow field generated by intense internal waves. The internal-wave parameters are takes from the results of the COPE experiment. We calculate the wind growth-rate dependences on the wave-train phase for the cases of downwind and upwind propagation of an internal wave. The calculation results agree qualitatively with experimental data.     

Analysis of bicarbonate,phosphate and other anions in saliva by capillary electrophoresis with capacitively coupled contactless conductivity detection in diagnostics of gastroesophageal reflux disease

Bicarbonate and phosphate constitute major salivary buffering components, and their importance consists in the neutralization of acidic gastric contents during reflux episodes. In this work, capillary electrophoresis with capacitively coupled contactless conductivity detector was applied for the analysis of bicarbonate, phosphate, and another inorganic (chloride, nitrite, nitrate, sulfate, thiocyanate) and organic anions (acetate, butyrate) to evaluate their levels in saliva. The background electrolytes of different composition and pH between 6.02–9.41 were assessed for the bicarbonate and phosphate determination by comparison of the real analyses of a model solution with the simulation by PeakMaster software. The optimized background electrolyte was composed of 10 mM 2-(N-morpholino)ethanesulfonic acid, 20 mM arginine, and 30 µM cetyltrimethylammonium bromide, pH 8.95. Using this BGE, the anion levels were compared in saliva from 20 patients suffering from gastroesophageal reflux disease (GERD) and saliva from 12 healthy subjects. Bicarbonate levels were significantly elevated in saliva from GERD patients suggesting the possible applicability of bicarbonate as a biomarker in non-invasive diagnostics of GERD by CE-C⁴D.     

Inhibiting action of N-phenacylmethylheterylazolium bromides under conditions of acid steel corrosion

Inhibiting action of N-phenacylmethylheterylazolium bromides based on imidazole, benzimidazole, benzthiazole, and their mixtures with potassium iodide, urotropin, or paraform on the steel corrosion in 3 M H₂SO₄ solutions was studied.     

Displacement of the free surface of a fluid during flow over a cylinder

Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 4, pp. 48–51, July–August, 1988.     

Comparative effect of N-decyl- and N-phenacylmethylpyridinium bromides in acid corrosion of steel

Comparative analysis of inhibitory effect of N-decyl and N-phenacylmethylpyridinium bromides and their mixtures with potassium chloride, bromide, and iodide, and also with urotropin and paraform was carried out at corrosion of steel 08 KP in 3 M H₂SO₄ solutions.