Incubation time based testing of materials

Some principal features of the behavior of materials subjected to pulsed actions are common for a number of seemingly quite different physical processes, such as dynamic fracture (starting cracks and scabbing), cavitation in liquids, and electrical breakdown in solids. In this paper, we analyze examples illustrating typical dynamic effects inherent in these processes. We propose a unified interpretation for the fracture of solids and liquids and electrical breakdown in insulators using the structural-time approach based on the concept of the fracture incubation time. The examples of different physical processes considered in the paper show the fundamental importance of investigating incubation processes preparing abrupt structural changes (fracture and phase transitions) in continua under intense pulsed actions. The fracture incubation time is evidently a universal basic characteristic of the dynamic strength and must become one of the main material parameters to be experimentally determined (measured).     

The polarized absorption spectrum of 5-methyl indole in polyethylene and polyvinylalcohol films

The stretched film technique has been used to resolve the two overlapping ¹L_a and ¹L_b transitions of indole. 5-Methyl indole was studied as a model compound in two polymer matrices, polyethylene (PE) and polyvinylalcohol (PVA). The directions of the transition moments with respect to the long molecular axis are found to be in PE − 10° and +22° for ¹L_a and ¹L_b, respectively. These angles are found to be −25° and +29° in PVA. ¹L_a has two prominent vibrations in PE at 2040 and 2895 cm⁻¹ from the origin. ¹L_b has four prominent vibrations in PE at 761, 1308, 1937 and 3196 cm⁻¹ from the origin. In PVA, ¹L_a has two prominent vibrations at 2149 and 2874 cm⁻¹ from the origin and ¹L_b has four prominent vibrations at 1049, 1352, 2229 and 3196 cm⁻¹ from the origin.     

Synthèse et structures cristallines de Cs3MI4NO3 (M = Zn,Co, Cd): Un exemple de substitution sélective

The compounds Cs₃MX₅ (M is a bivalent metal, and X an halogen) consist of Cs⁺, I⁻, and distorted (MI₄)²⁻ ions. The separate X⁻ ion suggests a possible substitution by another monovalent anion. The new compounds Cs₃MI₄NO₃ (M = Zn, Co, Cd) have been synthesized and characterized by X-ray diffraction. They are orthorhombic Pnma, a = 10.114(4), b = 11.601(5), c = 14.290(9) Å for Cs₃ZnI₄ NO₃; a = 10.078(8), b = 11.621(4), c = 14.262(6) Å for Cs₃CoI₄NO₃; a = 10.177(4), b = 11.784(5), c = 14.336(7) Å for Cs₃CdI₄NO₃; Z = 4. The crystal structures are described. The NO₃ groups surrounded by six Cs⁺ cations occupy the same sites as the separate I⁻ ion in the Cs₃MI₅ compounds.     

Phase transition phenomena induced by the successive appearances of new types of aggregation states of water molecules in the “l-dipalmitoylphosphatidylcholine-water” system

Thermal analysis of the aggregation state of water molecules m the “L-di-palmitoylphosphatidylcholine (DPPC)-water system revealed that in the low-temperature crystal phase below the sub-transition temperature, there are three kinds of interlamellar water, i.e., tightly, loosely, and more loosely bound water, which are incorporated between the bilayers of l-DPCC molecules, while the Lβ' gel phase lacks the third bound water molecule. Furthermore, we found that both the sub- and pre-transitions below the main transition temperature appear, for the first time, at water contents of around 11 and 18 g%, respectively, just at which point the new types of water structure occur. These findings indicate that the condition necessary for the appearance of these two kinds of phase transition is the existence of the characterized aggregation state of water molecules, that is, more loosely bound water for the sub-transition and bulk free water coexisting with the Lβ' gel phase for the pre-transition.     

Comparative infrared study of silicon and germanium nitrides

Silicon and germanium nitride (Si₃N₄ and Ge₃N₄) are isomorphic compounds. They have been studied in the β-phase which crystallises in the hexagonal system. The space group is P6₃/m (C_6h²).The IR transmission spectra of these two nitrides are very similar but the absorption frequencies of germanium nitride are shifted to the lower values in comparison with silicon nitride. We noted that the atomic mass effect is the only cause of this shift for the streching modes but not for the bending modes.     

Synthesis and structural characterisation of [Ru8(μ8-P)(μ2-η1,η6-CH2C6H5)(μ2-CO)2(CO)17]: example of phosphorus encapsulated in a square anti-prism of ruthenium atoms and of an unusual coordination mode for the benzyl group

Reaction of [Ru₃(CO)₁₂] with an equimolar amount of PPh₂H affords a range of products including an octaruthenium species [Ru₈(μ₈-P)(μ₂-η¹,η⁶-CH₂C₆H₅)(μ₂-CO)₂(CO)₁₇], in which, as established X-ray crystallographically, a phosphorus atom is encapsulated in a square anti-prism of ruthenium atoms and a benzyl group is coordinated to two of these rutheniums through all seven carbon atoms.     

D3-trishomocubanetrione synthesis and optical resolution

A large-scale synthesis for the title compound rac-1 based on 11-oxahexacyclo-[5.4.1.0^2,6.0^3,10.0^4,8.0^9,12] dodecan-5-one (12) as the key intermediate and an efficient procedure for the optical resolution of rac-1 via the diastereomeric ketals with (R,R)-2,3-butandiol are reported. The absolute configuration is established by correlating the optically pure (+)-trione ([α]_D +949°) with (-)-trishomocubane.