Damping caused by fatigue in porous 316L steel

An analysis of the effect of microcracks in porous metals on amplitude-dependent internal friction (ADIF) is carried out. A mathematical model is developed, which takes into account an initial distribution of microcracks lengths defining subsequent crack growth during cycling. Using the Dugdale model, the linear density of microplastic zones at the tips of the microcracks is obtained as a function of applied stress and porosity. Resulting simulations of internal friction are compared with corresponding experimental data.     

Raman imaging of fluid inclusions in garnet from UHPM rocks (Kokchetav massif, Northern Kazakhstan)

In this work, we will report a combined experimental and theoretical study on molecular and vibrational structure of N,N'-di(p-thiazole)formamidine (DpTF). DpTF has been synthesized and characterized by elemental analysis, FT-IR, FT-Raman, 1H NMR, 13C NMR spectroscopy and X-ray single crystal diffraction. The FT-IR and FT-Raman spectra of DpTF were recorded in the solid phase. The optimized geometry was calculated by HF and B3LYP methods using 6-31G(d) basis set. The FT-IR and FT-Raman spectra of DpTF was calculated at the HF/B3LYP/6-31G(d) level and were interpreted in terms of potential energy distribution (PED) analysis. The scaled theoretical wavenumber showed very good agreement with the experimental values. A detailed interpretation of the infrared and Raman spectra of DpTF was reported. On the basis of vibrational analyses, the thermodynamic properties of the title compound at different temperatures have been calculated, revealing the correlations between Cp,m°, Sm°, Hm° and temperatures. Furthermore, molecular electrostatic potential maps (MESP) and total dipole moment properties of the compound have been calculated.     

Enantioselective addition of diethyl malonate to ω-nitrostyrenes in the presence of cobalt and manganese complexes with N,N′-dibenzyl-(1S,2S)-cyclohexane-1,2-diamine

Enantioselective addition of diethyl malonate to nitrostyrene and para-chloronitrostyrene is catalyzed by cobalt and manganese complexes with N,N??-dibenzyl-(1S,2S)-cyclohexane-1,2-diamine generated in situ. Enantiomeric excess of the (R)-isomers in the reaction products is 66?C87%.     

Effect of the matrix composition on the activity of metal oxide catalysts in CVD synthesis of carbon nanotubes

Citrate-nitrate method was used to synthesize (Fe,Co)/MgO-Al₂O₃, (Fe,Mo)/MgO-Al₂O₃, and (CoMo)/MgO-Al₂O₃ catalysts for production of carbon nanotubes. Multi-walled nanotubes were formed on these catalysts by catalytic pyrolysis of a propane-butane mixture.     

Unsteady flows with a constant total pressure,described by the equations of ideal magnetohydrodynamics

Exact solutions of the equations of ideal magnetohydrodynamics describing the class of unsteady flows of an electrically conducting fluid with a constant total pressure are constructed. The solutions are written in the Lagrange coordinate system; arbitrariness in its choice was used to parameterize magnetic field lines. The wide functional arbitrariness the solutions provide a significant variation in the picture of the described fluid motions. An example of unsteady flow of an ideal electrically conducting fluid in a cylindrical channel with fixed magnetic tubes is given.     

Observation of high-energy electrons from a metal target irradiated by protons with a mean energy of 25 keV

Electrons with abnormally high energies of up to 16 keV are detected from an iron target irradiated by ions (H⁺, Fe⁺, Fe²⁺, Fe³⁺) with energies ranging from 20 to 100 keV from the plasma of a high-power femtosecond laser pulse with an intensity of 10¹⁶ J/(s cm²). These electrons indicate that the energy of an incident ion is almost completely transferred to an electron knocked out of the target. In a range of 6–16 keV, the spectrum of electrons knocked out of the K shell of iron atoms by protons with an energy of 22 ± 2 keV is quasi-exponential with an exponent of 4 keV. For 8-keV electrons, the double differential cross section for ionization by such protons is estimated as 10^?7 b/(eV sr).     

Transformations of allylamine and N-allylacetamide on triosmium cluster complexes with hemilabile ligands

The cluster complexes (μ-H)Os₃(μ-OCR)(СО)₁₀ (R = Me (1); R = Ph (2)) catalyze the allylic rearrangement of N-allylacetamide at room temperature. Microwave irradiation greatly (by more than several thousand-fold) accelerates the reaction between the solution of 2 and allylacetamide. The interaction of cluster 2 with allylamine both at room and elevated temperatures results in cleavage of the C–N bond and coordination of the allylic fragment to one of the osmium atoms with the formation of Os₃(CO)₉(μ,η²-OC-Ph)(η³-C₃H₅) (4) cluster.     

Effect of electric fields on the dynamics of silicon microhardness changes induced by low-intensity β irradiation

Decelerating effect of electric fields on silicon microhardness changes induced by low-intensity (I = 10.4 × 10⁴ cm^?2 s^?1) β irradiation has been revealed. The threshold character of the electric field effect is found (the effect is absent at electric fields E < 350 V cm^?1).     

New Ways of Detecting Cracks,Delaminations, and Other Defects in Materials and Objects via High Frame-Rate Thermal Imaging

A number of advanced nondestructive thermographic tools are described that are based on the video recording of surfaces using thermal imaging cameras in which infrared radiation is induced by shortterm heating with an electric current or a stream of hot air. The tools allow the detection of cracks, delaminations, gaps, and other types of defects both inside and outside the shell of a structure that cannot be reached for direct inspection.     

Effect of Low-Amplitude Load Oscillations on Stiffness and Hardness for Al and W in Loaded Nanocontacts

The effect low-amplitude oscillations have on the mechanical properties of Al and W in nanocontacts is studied by means of continuous stiffness measurements (CSM). It is established that the additional superpositioning of oscillations until a critical amplitude is reached has no effect on the mechanisms, kinetics, or plastic deformation of a material. The threshold amplitudes and frequencies of such oscillations are determined for Al (2.5 nm) and W (3.5 nm).