Estimation of surface roughness effect on spectral characteristics of tone signals propagating along stationary paths in a shallow sea

Scattering of a tonal low-frequency (up to 400 Hz) acoustic signal on a rough surface during its propagation along stationary paths in a shallow water area is considered. A calculation technique of estimating the spectral power density of the signal scattered at wind waves (reverberation) given an arbitrary angular distribution of the wind wave is developed based on the Bragg scattering model. The obtained results are compared with the results of numerical simulation of resonant sound scattering at surface perturbations according to an algorithm proposed by the authors, as well as with the results of experimental investigations.     

The spatio-temporal structure of wideband acoustic pulses in shallow sea

We study the influence of a bottom-sediment layer on the spatio-temporal structure of wideband acoustic pulses in shallow sea. The shallow sea is modeled as a uniform liquid layer above a layer of liquid sediments located on an elastic half-space. The influence of various acoustic parameters of the problem, in particular the thickness of the sedimentary layer, damping parameters, etc. on the structure of wideband pulses is considered. We analyze the features of constructive mode interference due to which the spatial structure of the pulses takes the form of beams.     

Comparison of the Structural Features of Micron and Submicron Vaterite Particles and Their Efficiency for Intranasal Delivery of Anesthetic to the Brain

Crystallography Reports - Nanostructured spherical calcium carbonate particles with average sizes of 3.8 µm and 550 nm have been fabricated. Optimal conditions for adsorption of central...     

Assessment of conformational ensemble sizes necessary for specific resolutions of coverage of conformational space

The size of conformational ensembles required for regular coverage of the conformational space of druglike molecules was examined. Using the conformer generation program Omega, the number of regularly distributed conformers (NRC) of flexible compounds was determined as a function of the root-mean-square deviation (RMSD) resolution of coverage. A regression equation was developed predicting the NRC of a molecule as a function of RMSD. The model yielded R(2) of 0.91 for both training and test sets, which consisted of 3414 and 3352 compounds, respectively. Utilizing 14 504 ligands from the Protein Data Bank with experimentally determined 3-D conformations, the regression equation was applied to the estimation of the NRC and the success rate of reproduction of experimental conformations from a theoretical conformation ensemble as a function of RMSD and flexibility was explored.     

Sorption-spectrometric determination of palladium and gold using silica chemically modified with dipropyl disulfide groups

It has been found that silica chemically modified with dipropyl disulfide groups (DPDSS) quantitatively extracts palladium(II) from solutions in the acidity range from 4 M HCl to pH 4 and gold(III) in the range from 1 M HCl to pH 2 with a partition coefficient at the level of n × 10⁴ cm³/g. The adsorption of palladium(II) and gold(III) at room temperature is highly selective, whereas non-ferrous and other platinum metals are not adsorbed. Sorption-atomic absorption, sorption-ICP-atomic emission, and sorption-photometric methods for the determination of palladium and gold have been developed using DPDSS. The accuracy of the methods was tested by the analysis of certified reference samples.     

Phase conjugation in an acoustic waveguide

A method for holographic observation of sound sources and passive inhomogeneities in acoustic waveguides is proposed. The method is based on the principle of coherent phase conjugation. A possibility of visual observation of both sound sources and stationary inhomogeneities of different kinds is experimentally verified.     

Antitumor effects of binuclear ferrocene derivatives

On the basis of an earlier model of chemical carcinogenesis, the antitumor activity of the mono-, bi- and poly-nuclear ferrocene derivatives ferricenium tri-iodide (1), ferricenium tetrachloroferrate (2), 1, 1′-diethylferricenium triiodide: (3), N-(ferrocenylmethyl)hexamethylenetetramine tetrafluoroborate (4), bis(ferrocenylmethyl)benzotriazolium tetrafluoroborate (5), bis(ferrocenyl-α-ethyl)benzotriazolium tetrafluoroborate (6) and bis(ferrocenylmethyl)-2-methylbenzimidazolium tetrafluoroborate (7), and the oligomer (—Fc—CH₂—Fc^+˙—CH₂—)_7–8^? (PF₆)_7–8 (8) was studied in vivo (Fc?C₁₀H₈Fe). The tumor models studied included MCH-11 (mouse sarcoma induced by methylcholantrene), P-815 (mouse mastocytoma of DBA/2 origin) and virus-induced Raucher leukemia (RLV). The cytotoxic effects of these preparations were examined against in vitro cultured normal murine cells (line L-929). The binuclear ferrocene derivatives 5, 6 and 7 inhibited the development of experimental tumors in mice. Ferricenium tri-iodide (1) was effective in Rauscher leukemia. Kinetic dependencies for most complexes had a two-phase character: the region of inhibition of tumorogenesis was followed by a region in which the complexes accelerated the development of this process. The link between the structure of compounds 1–8 and their antitumor effects is discussed.