Physical modeling of seismic source generation in failure of fault asperities

A series of full-scale experiments was performed to study the influence of impact loads on the parameters of seismic vibrations initiated in variable friction. The study was conducted on a test setup Tribo which is a movable concrete slab modeling an allochthon on a rough plane of the Angara fault segment in Baikal region. Contact interactions of asperities in the slip zone were recorded using strain and load measuring equipment and four seismic stations Baykal-7HR widely used for recording earthquakes. The proposed physical modeling method and obtained results can be of interest for the development of new physical models of differently scaled sources of seismic energy dissipation in tectonic faults and can be useful for seismological studies, related data interpretation, and improvement of extended forecast of rock bursts and earthquakes.     

Effect of drying temperature on sizes and morphology of goethite nanoparticles

The morphology, structure, and size distribution of goethite nanoparticles, which are obtained by chemical precipitation of iron salt and alkali in aqueous solutions with different surfactants and are dried at 100°C and room temperature, have been investigated in order to develop technology for obtaining goethite (α-FeOOH) nanoparticles of minimum sizes. It is found that the samples dried at a temperature of 100°C have a different phase state and increased sizes as compared to the samples dried at room temperature.     

Chemical alterations to murine brain tissue induced by formalin fixation: implications for biospectroscopic imaging and mapping studies of disease pathogenesis

Understanding biochemical mechanisms and changes associated with disease conditions and, therefore, development of improved clinical treatments, is relying increasingly on various biochemical mapping and imaging techniques on tissue sections. However, it is essential to be able to ascertain whether the sampling used provides the full biochemical information relevant to the disease and is free from artefacts. A multi-modal micro-spectroscopic approach, including FTIR imaging and PIXE elemental mapping, has been used to study the molecular and elemental profile within cryofixed and formalin-fixed murine brain tissue sections. The results provide strong evidence that amino acids, carbohydrates, lipids, phosphates, proteins and ions, such as Cl(-) and K(+), leach from tissue sections into the aqueous fixative medium during formalin fixation of the sections. Large changes in the concentrations and distributions of most of these components are also observed by washing in PBS even for short periods. The most likely source of the chemical species lost during fixation is the extra-cellular and intra-cellular fluid of tissues. The results highlight that, at best, analysis of formalin-fixed tissues gives only part of the complete biochemical "picture" of a tissue sample. Further, this investigation has highlighted that significant lipid peroxidation/oxidation may occur during formalin fixation and that the use of standard histological fixation reagents can result in significant and differential metal contamination of different regions of tissue sections. While a consistent and reproducible fixation method may be suitable for diagnostic purposes, the findings of this study strongly question the use of formalin fixation prior to spectroscopic studies of the molecular and elemental composition of biological samples, if the primary purpose is mechanistic studies of disease pathogenesis.     

Biotransformations of Anticancer Ruthenium(III) Complexes: An X‐Ray Absorption Spectroscopic Study

An anti‐metastatic drug, NAMI‐A ((ImH)[Ru^IIICl₄(Im)(dmso)]; Im=imidazole, dmso=S‐bound dimethylsulfoxide), and a cytotoxic drug, KP1019 ((IndH)[Ru^IIICl₄(Ind)₂]; Ind=indazole), are two Ru‐based anticancer drugs in human clinical trials. Their reactivities under biologically relevant conditions, including aqueous buffers, protein solutions or gels (e.g, albumin, transferrin and collagen), undiluted blood serum, cell‐culture medium and human liver (HepG2) cancer cells, were studied by Ru K‐edge X‐ray absorption spectroscopy (XAS). These XAS data were fitted from linear combinations of spectra of well‐characterised Ru compounds. The absence of XAS data from the parent drugs in these fits points to profound changes in the coordination environments of Ru^III. The fits point to the presence of Ru^IV/III clusters and binding of Ru^III to S‐donor groups, amine/imine and carboxylato groups of proteins. Cellular uptake of KP1019 is approximately 20‐fold higher than that of NAMI‐A under the same conditions, but it diminishes drastically after the decomposition of KP1019 in cell‐culture media, which indicate that the parent complex is taken in by cells through passive diffusion.     

On block Gaussian sketching for the Kaczmarz method

Numerical Algorithms - The Kaczmarz algorithm is one of the most popular methods for solving large-scale over-determined linear systems due to its simplicity and computational efficiency. This...     

Vanadium Speciation by XANES Spectroscopy: A Three‐Dimensional Approach

A library of X‐ray absorption near‐edge structure (XANES) spectroscopic data for V^V, V^IV and V^III complexes with a broad range of biologically relevant ligand has been used to demonstrate that three‐dimensional plots of key XANES parameters (pre‐edge and edge energies; pre‐edge and white line intensities) can be used for the prediction of V oxidation states and coordination numbers in biological or environmental matrices. The reliability of the technique has been demonstrated by re‐analysis of the published XANES data for a V^V‐dependent bromoperoxidase.     

Participation of an enimine methyl group in cyclization with PC13

Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 490–491, February, 1989.