Construction of nonlocal linear vibration models using a computer algebra system

In the paper, on the examples of a string and beam, resonance vibrations in linear elastic systems that result from nonlocal boundary conditions (even if external forces are lacking) are considered. Formulas of exact solutions of the corresponding boundary-value problems are presented. These formulas are used for evaluation of the solutions and for construction of plots. Computer algebra system Mathematica was used for derivation and analysis of the exact solutions and for development of software packages designed for evaluation of the derived formulas and solution visualization. The authors believe that results of this study can be used to explain the causes for the vibration of the Tacoma and Volgograd bridges in 1940 and 2010, respectively.     

Abiotic nitrogen reduction on the early Earth

The production of organic precursors to life depends critically on the form of the reactants. In particular, an environment dominated by N2 is far less efficient in synthesizing nitrogen-bearing organics than a reducing environment rich in ammonia. Relatively reducing lithospheric conditions on the early Earth have been presumed to favour the generation of an ammonia-rich atmosphere, but this hypothesis has not been studied experimentally. Here we demonstrate mineral-catalysed reduction of N2, NO2- and NO3- to ammonia at temperatures between 300 and 800 degrees C and pressures of 0.1-0.4 GPa-conditions typical of crustal and oceanic hydrothermal systems. We also show that only N2 is stable above 800 degrees C, thus precluding significant atmospheric ammonia formation during hot accretion. We conclude that mineral-catalysed N2 reduction might have provided a significant source of ammonia to the Hadean ocean. These results also suggest that, whereas nitrogen in the Earth's early atmosphere was present predominantly as N2, exchange with oceanic, hydrothermally derived ammonia could have provided a significant amount of the atmospheric ammonia necessary to resolve the early-faint-Sun paradox.     

Influence of temperature on phase separation in the ternary systems [Th(NO3)4(TBP)2]-decane-third organic component

The phase diagrams of ternary systems [Th(NO₃)₄(TBP)₂]-decane-third organic component (n-butanol, n-octanol, isobutanol, dimethylhexanol, chloroform, carbon tetrachloride, o-dichlorobenzene, tri-n-butyl phosphate, o-xylene, toluene, and linear carboxylic acids) were studied in the temperature range 288.15–333.15 K. These diagrams contain the fields of homogeneous solutions and the field of separation into two liquid phases (I, II). Phase I is enriched in Th(NO₃)₄(TBP)₂ and third component and phase II is enriched in decane. The phase separation is not appreciably influenced by temperature. In phase separation, the third component is predominantly concentrated in phase I, in spite of the fact that the third component and decane have infinite mutual solubility at all the temperatures. The composition of the ternary systems in the critical point is dependent on the kind of the third component.     

Prediction of solid solution formation in glass

Translated from Steklo i Keramika, No. 2, pp. 9–10, February, 1992.     

The Use of Biochar as Filler in Polyurea Lubricants

Chemistry and Technology of Fuels and Oils - The possibility of using biochar of plant origin as filler in polyurea plastic greases was studied, and its effect on their performance was...