Inhibition of tissue repair by spironolactone: role of mineralocorticoids in fibrous tissue formation

The complete removal of the fluorescent cysteine derivative 4-(aminosulfonyl)-7-fluoro-2,1,3-benzoxadiazole (ABD-F) from an intact protein has not been demonstrated even after extended treatment with a reducing agent. It has been suggested that this may be due to incomplete denaturation under the conditions employed. We were interested in investigating this phenomenon utilizing small peptides containing individual ABD-labeled cysteine residues. After incubating the fluorescent peptides in the presence of a reductant, it was shown that the ABD label could be completely removed from all of the cysteine-containing peptides investigated. Therefore, delabeling irreversibility is due to residual structure in proteins. Electrospray ionization mass spectrometry (ESI-MS) was used to determine the molecular mass of each peptide after removal of the ABD lavel. The ESI-MS data were consistent with the generation of a free sulfhydryl. The generation of the free sulfhydryl was further substantiated when a delabeled peptide was completely relabeled with ABD-F in the absence of reductant.     

A fast model for the simulation of non-round particles

This paper describes a new, computationally efficient model for the discrete element simulation of a certain class of non-round particles. The boundaries of the particles in this model are constructed from the circular segments of different radii in such a way that connections between these segments are continuous. As such, the model does not permit the simulation of arbitrarily shaped particles, but it does allow a wide enough variety of shapes to assess the effects of non-round shapes (in particular, particle interlocking) in an efficient manner. A direct test of the models performance demonstrates that the model is much more efficient than other models for non-round particles currently available and is less than two times slower than models for the same number of round particles.     

Reconstructing long time series of burned areas in arid grasslands of southern Russia by satellite remote sensing

Fire is an important natural disturbance process in many ecosystems, but humans can irrevocably change natural fire regimes. Quantifying long-term change in fire regimes is important to understand the driving forces of changes in fire dynamics, and the implications of fire regime changes for ecosystem ecology. However, assessing fire regime changes is challenging, especially in grasslands because of high intra- and inter-annual variation of the vegetation and temporally sparse satellite data in many regions of the world. The breakdown of the Soviet Union in 1991 caused substantial socioeconomic changes and a decrease in grazing pressure in Russia's arid grasslands, but how this affected grassland fires is unknown. Our research goal was to assess annual burned area in the grasslands of southern Russia before and after the breakdown. Our study area covers 19,000 km² in the Republic of Kalmykia in southern Russia in the arid grasslands of the Caspian plains. We estimated annual burned area from 1985 to 2007 by classifying AVHRR data using decision tree algorithm, and validated the results with RESURS, Landsat and MODIS data. Our results showed a substantial increase in burned area, from almost none in the 1980s to more than 20% of the total study area burned in both 2006 and 2007. Burned area started to increase around 1998 and has continued to increase, albeit with high fluctuations among years. We suggest that it took several years after livestock numbers decreased in the beginning of the 1990s for vegetation to recover, to build up enough fuel, and to reach a threshold of connectivity that could sustain large fires. Our burned area detection algorithm was effective, and captured burned areas even with incomplete annual AVHRR data. Validation results showed 68% producer's and 56% user's accuracy. Lack of frequent AVHRR data is a common problem and our burned area detection approach may also be suitable in other parts of the world with comparable ecosystems and similar AVHRR data limitations. In our case, AVHRR data were the only satellite imagery available far enough back in time to reveal marked increases in fire regimes in southern Russia before and after the breakdown of the Soviet Union.     

Analysis of the hydrodynamic state of the two-phase model of the solidifying weld metal

A robotic laser welding cell for stainless steel components, which includes a Cartesian robot, is described. The solution allows a drastic reduction in production times along with increased final quality compared to traditional welding technology, thus representing a particularly significant example of the advantages of the flexibility of a robot and the quality of the laser.     

Obtaining of silica nanopowders from natural hydrothermal solutions

Obtaining of nanodispersed silica powders from natural hydrothermal solutions is described. Hydrothermal solutions contain colloid silica forming as a result of the polycondensation of the molecules of orthosilicic acid. Via ultrafiltration with a membrane concentration of hydrothermal solutions, silica sols with SiO2 contents up to 600 g/dm³ (43.0 wt %) and particle radii of 29–135 nm are obtained. The silica powders with the specific surface area of 110–400 m²/g, average pore diameter of 3–10 nm, and pore volume of 0.2–0.3 cm³/g are obtained via the cryochemical vacuum-sublimation drying of sols with the use of liquid nitrogen. The particle size in the powders is in the range from 10 to 100 nm.     

On the stability of columns under stochastic loading taking into account nonlocal damping

Using an example of a column clamped at both ends, the stability of columns made of a material characterized by nonlocal damping is investigated. The column is subjected to axial forces that are deterministic and randomly vary in time. In the deterministic case, the stability is understood in Lyapunov??s sense; in the case of the stochastic formulation of the problem, the almost sure stability is considered. In either case, the method of the top Lyapunov exponent is used to analyze the stability.     

Spectrometric method of evaluating spent nuclear fuel characteristics

A spectrometric method of identifying spent fuel assemblies according to the type of fuel elements present in them is described. The method is based on the results of spectrometric measurements and subsequent analysis of the radiation from fission products and the characteristic radiation from uranium in the irradiated fuel. The fuel assemblies used in the VVR-2 and OR research reactors contained fuel elements of a different type, differing by the initial quantity of uranium contained in them. To prepare the spent fuel assemblies for shipment to a reprocessing facility after long-time storage in cool-down pools, the assemblies must be sorted according to the type of fuel elements present in them. The method developed for identifying the types of fuel elements in the irradiated fuel is based on the dependence of the intensity of the characteristic radiation from uranium on the uranium content in a fuel element. The degree of excitation of the characteristic radiation of uranium also depends on the intensity of the radiation from fission products, which is monitored during the spectrometric measurements performed on the irradiated fuel; ultimately, this makes it possible to sort the spent fuel assemblies.     

Simulation of Safe Methods for Performing Decontamination Work

Devices for obtaining gamma images have undergone extensive development in the last few years. Using such devices for examining radioactively contaminated equipment and enclosures makes it possible to develop maps of the distribution of the radioactive contamination. Knowing the radioactivity distribution it is possible to calculate the exposure dose rate at any point of the enclosure and therefore to simulate the safest methods for performing decontamination work. In the present paper, decontamination work is simulated for an enclosure of a nonoperating research reactor at the Russian Science Center Kurchatov Institute. This reactor was shutdown for decontamination and disassembly. It is shown that the worker dose loads can be substantially decreased by performing the decontamination work in the correct sequence.     

Evaluation of compositional intermixing at interfaces in Si(Ge)/Si1−x Gex heteroepitaxial structures grown by molecular beam epitaxy with combined sources of Si and GeH4

The main causes of the diffusion spreading of a solid-solution composition near the boundaries of the Si transport channel in a Si/Si_1?x Ge_x heterostructure grown by molecular-beam epitaxy combined with solid (Si) and gaseous (GeH₄) sources are considered. For the grown structures, the contributions from various mechanisms involved in forming the profile of the metallurgical boundary of the layer are compared and the effect of channel boundary spreading on the mobility of a two-dimensional electron gas in the channel is evaluated.