Phase relations for a sound wave at its reflection and transmission through a plane layer

A property never considered before in acoustics is established: in the case of a sound wave incidence on a plane layer bordered by two liquid media with identical elastic properties, the phase difference between the reflected and transmitted waves is equal to π/2 irrespective of the physical constants of the layer and the media contacting it, as well as of the frequency of the incident wave.     

Morphological transformations of native petroleum emulsions. I. Viscosity studies

Emulsions of water in as-recovered native crude oils of diverse geographical origin evidently possess some common morphological features. At low volume fractions varphi of water, the viscosity behavior of emulsions is governed by the presence of flocculated clusters of water droplets, whereas characteristic tight gels, composed of visually monodisperse small droplets, are responsible for the viscosity anomaly at varphi approximately 0.4-0.5. Once formed, small-droplet gel domains apparently retain their structural integrity at higher varphi, incorporating/stabilizing new portions of water as larger-sized droplets. The maximum hold-up of disperse water evidently is the close-packing limit of varphi approximately 0.74. At higher water contents (up to varphi approximately 0.83), no inversion to O/W morphology takes place, but additional water emerges as a separate phase. The onset of stratified flow (W/O emulsion gel + free water) is the cause of the observed viscosity decrease, contrary to the conventional interpretation of the viscosity maximum as a reliable indicator of the emulsion inversion point.     

Crystal structure and magnetic properties of a new heterometallic complex of Pd(II)-Cu(II) with 1-aminoethylidene-1,1-diphosphonic acid

A heterometallic complex of Pd(II)-Cu(II) with 1-aminoethylidene-1,1-diphosphonic (AEDP) acid (C₄H₂₂CuN₂O₁₆P₄Pd) _n (I) is synthesized. Single crystals of compound I are obtained; its crystal structure is determined by X-ray crystallography. The crystals are orthorhombic, space group Pbcn, a = 18.366(3) Å, b = 9.7661(17) Å, c = 20.198(4) Å, V = 3622.8(11) ų, Z = 8, d _x = 2.376 g/cm³. The compound crystallizes as a coordination polymer; the square environment of Pd(II) is formed by nitrogen atoms of amino groups and oxygen atoms of phosphonic groups, while at two non-equivalent copper atoms the octahedral environment is formed by oxygen atoms of phosphonic groups and water molecules. The crystal structure of compound I is characterized by the formation of a branched network of hydrogen bonds. Based on the analysis of the temperature dependence of the magnetic susceptibility it is found that for the heterometallic complex of Pd(II)-Cu(II) with AEDP antiferromagnetic interactions between the paramagnetic centers are dominant.     

Detonation nanodiamonds as catalysts of steam reforming of ethanol

Physicochemical properties and catalytic performance of detonation nanodiamonds were studied. Original samples of nanodiamonds and nanodiamonds modified by hydrogen, oxygen, and nitric acid with hydrogen peroxide and infrared-treated were investigated. The catalyst structure and morphology were examined by transmission electron microscopy and IR spectroscopy. All the investigated catalysts were active in the steam reforming of ethanol. The correlation of catalytic properties with composition and structure of the described systems is discussed. The specific surface area of nanodiamonds is changed insignificantly upon modification.     

Synthesis,structure, and ESR spectra of the new heteronuclear complex {Li4(VO)2[(OOC)2C(H)Bu]4(H2O)8}·H2O

The reaction of an aqueous solution of vanadyl sulfate VOSO₄·3H₂O, butylmalonic acid (H₂Bumal = C₄H₁₀(COOH)₂), and lithium carbonate at pH ～4–5 gave crystals of the complex Li₄(VO)₂(Bumal)₄(H₂O)₈]·H₂O (1). The structure of complex 1 was established by X-ray diffraction analysis. The molecule of complex 1 consists of two mononuclear bischelate dianionic units {VO(Bumal)₂(H₂O)} linked by four lithium ions to form the hexanuclear heterometallic {V₂Li₄} structure. The crystals and an ethanolic solution of compound 1 were studied by ESR spectroscopy.     

Head-on collision of two spherical shock waves. Interaction of laser sparks in a gas

Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 5, pp. 133–137, September–October, 1990.