Electron and phonon effects in superconducting tunnel detectors of x-radiation

Nb/Al/AlO_x/Nb superconducting tunnel junctions were investigated in the role of x-ray detectors. Amplitude spectra of pulses arising upon irradiation of tunnel junctions of different sizes by ⁵⁵Mn x-radiation were recorded at a temperature T=1.4 K. We also analyzed the temporal shape of the pulses. We considered the influence of diffuse motion of nonequilibrium quasiparticles, the inverse tunneling effect, and exchange of 2Δ phonons between electrodes, on the characteristics of the tunnel detectors. It is shown that phonon processes can bring about changes in the amplitude, duration, and polarity of the signal. Fiz. Tverd. Tela (St. Petersburg) 41, 1168–1175 (July 1999)     

Assigning vibrational polyads using relative equilibria: application to ozone

We demonstrate how relative equilibria of a vibrating molecule, which are families of principal periodic orbits otherwise known as nonlinear normal modes, can be used to describe the global polyad structure of vibrational energy levels. The classical action integral n(E) computed along these orbits at different energies E corresponds to the polyad quantum number n so that the energy En of different relative equilibria describes the splitting of n-polyads. Further information on the internal polyad structure can be driven from the stability analysis of relative equilibria. We use the ozone molecule as a concrete example where n-polyads or "hyperpolyads" should be distinguished from the well-known polyads of the 1:1 stretching mode resonance; the stretching polyads are structural elements of hyperpolyads. We give dynamical interpretation of the relation between relative equilibria and n-polyads based on the normal form reduction in the limit of small vibrations near the equilibrium.     

Kinetics and Mechanism of the Dissolution of Gold in Solutions of Thiocarbamide

The kinetics and mechanism of the dissolution of metallic gold in solutions of thiocarbamide in the presence of iron(III) were investigated. The dependence of the dissolution rate of gold on the pH of the solution and the ratio of the concentrations of iron(III) and thiocarbamide was determined, and the optimum conditions for the dissolution of gold were determined. The first-order rate constant for the dissolution of gold and the equilibrium constants for the formation of the complex cations Au[SC(NH₂)₂]⁺ ₂ and the formation of formamide disulfide S₂C₂(NH)₂(NH₂)₂ were calculated.     

Stress-deformed state of a semi-infinite ice sheet under the action of a moving load

Komsomol'sk on Don. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fiziki, No. 5, pp. 112–117, September–October, 1994.     

关于微积分解题的两个注记

微积分是理工科大学生的一门非常重要的基础课.给出了微积分中求未定式极限时需注意采取的一个措施及由微分方程的通解求相应的微分方程的一般方法,并给出了算例.     

Effect of Mg doping on morphology,photocatalytic activity and related biological properties of Zn1−xMgxO nanoparticles

The objective of this study is to synthesize ZnO and Mg doped ZnO (Zn_1−xMg_xO) nanoparticles via the sol-gel method, and characterize their structures and to investigate their biological properties such as antibacterial activity and hemolytic potential.Nanoparticles (NPs) were synthesized by the sol-gel method using zinc acetate dihydrate (Zn(CH₃COO)₂.2H₂O) and magnesium acetate tetrahydrate (Mg(CH₃COO)₂.4H₂O) as precursors. Methanol and monoethanolamine were used as solvent and sol stabilizer, respectively. Structural and morphological characterizations of Zn_1−xMg_xO nanoparticles were studied by using XRD and SEM-EDX, respectively. Photocatalytic activities of ZnO and selected Mg-doped ZnO (Zn_1−xMg_xO) nanoparticles were investigated by degradation of methylene blue (MeB). Results indicated that Mg doping (both 10% and 30%) to the ZnO nanoparticles enhanced the photocatalytic activity and a little amount of Zn0.90 Mg0.10 O photocatalyst (1.0 mg/mL) degraded MeB with 99% efficiency after 24 h of irradiation under ambient visible light. Antibacterial activity of nanoparticles versus Escherichia coli ( E. coli ) was determined by the standard plate count method. Hemolytic activities of the NPs were studied by hemolysis tests using human erythrocytes. XRD data proved that the average particle size of nanoparticles was around 30 nm. Moreover, the XRD results indicatedthat the patterns of Mg doped ZnO nanoparticles related to ZnO hexagonal wurtzite structure had no secondary phase for x ≤ 0.2 concentration. For 0 ≤ x ≤ 0.02, NPs showed a concentration dependent antibacterial activity against E. coli . While Zn_0.90Mg_0.10 O totally inhibited the growth of E. coli , upper and lower dopant concentrations did not show antibacterial activity.     

Enhancement of Second-Harmonic Generation in a Micropillar Resonator Due to the Engineered Destructive Interference

JETP Letters - We show that engineering the cavity aspect ratio of AlGaAs micropillar resonator allows for the two orders of magnitude increase in the efficiency of second harmonic generation at...     

The Use of Pulse Nuclear Magnetic Resonance for Studying the Mechanism of Solvation Separation of Natural Bitumen

A mechanism of deasphalting and fractionation of Ashal'chinsk natural bitumen with acetone was studied by pulse NMR. The features of distribution of components of the initial material in acetone solutions in deasphalting and also structural variations in the colloidal system resulting in separation of fractions when water is added in portions to the solution were studied. The structural-group composition of the separation products was characterized on the basis of NMR and IR data.