Synthesis of Nitrogen Oxides in a Subthreshold Microwave Discharge in Air and in Air Mixtures with Methane

Plasma Physics Reports - A subthreshold discharge excited by a microwave beam in air at pressures close to atmospheric is studied as a plasmachemical method of nitrogen oxide (NOx) production. It...     

The Importance of Hauling Grounds in the Life of the Baikal Seals (Pusa sibirica Gmelin 1788, Pinnipedia): 1. Review

Biology Bulletin - The published information on the roles that summer hauling grounds play in the life cycle of the Baikal seal (Pusa sibirica Gmelin 1788) is reviewed and summarized. In the Baikal...     

EDTA reduces heavy metal impacts on Tribulus terrestris photosynthesis and antioxidants

The effects of EDTA application to heavy metal-polluted soil on phytoextraction of heavy metals, leaf anatomy, gas exchange parameters, enzyme activities of C₄ carbon cycle, antioxidant defense, and active compounds of Tribulus terrestris L. were evaluated. The addition of EDTA to the soil polluted with Cd and Pb markedly increased dry weight and Pb, Zn, and Cd contents in shoots. Plants responded to the action of EDTA by an increased stomatal conductance, photosynthetic and transpiration rates, water use efficiency, chlorophyll and carotenoid contents. The activities of C₄ carbon cycle enzymes simultaneously increased, thus concentrating CO₂ for enhanced CO₂ assimilation and providing NADPH for the antioxidant system. Antioxidants, such as ascorbate, reduced glutathione, and flavonoids, increased more in the shoots of T. terrestris after the addition of EDTA. The activities of guaiacol peroxidase, catalase, and the enzymes of the ascorbate-glutathione cycle enhanced significantly in the presence of EDTA. Increased activities of antioxidant enzymes suggest that they have some additive functions in the mechanism of metal tolerance. EDTA application lowered the activity of phenylalanine ammonia-lyase and the content of total phenols, MDA, hydrogen peroxide, dehydroascorbate, and lipid-soluble antioxidant capacity expressed as α-tocopherol. Increased levels of total radical-scavenging activity are in correspondence with the activity of water-soluble antioxidant compounds in T. terrestris tissues. The content of furostanol saponins protodioscin, prototribestin, and rutin increased as a result of EDTA addition. The results obtained allowed us to assume that applied EDTA reduced a negative heavy metal impact on puncture vine photosynthesis and antioxidant potential.     

Physiological and anatomical responses of wheat to induced dehydration and rehydration

Hydroponically grown wheat seedlings of two prominent Bulgarian cultivars (Katya and Prelom) were subjected to 48 h osmotic stress with PEG 8000 and were then rehydrated. The degree of stress was evaluated by monitoring relative water content, lipid peroxidation level, and accumulation of free proline and hydrogen peroxide in the leaves. Anatomy and ultrastructure of leaf tissue were observed under light microscopy. After imposition of stress, drought tolerant cultivar Katya displayed higher free proline content and significantly lower malondialdehyde and peroxide concentration in leaves than in the leaves of susceptible cultivar Prelom. After 24 h of rehydration Katya showed better ability to restore leaf water status and an apparent tendency towards recovery, whereas Prelom sustained higher levels of hydrogen peroxide, lipid peroxidation products and free proline and markedly low relative water content. Here, we have uncovered some of the characteristics displayed by cultivar Katya that enable it to survive and recover from severe osmotic stress. Interestingly, there was congruence between our results and the high level of cultivar Katya drought tolerance observed in the field.     

Simulated and experimental estimates of hydrodynamic drag from bio-logging tags

Drag force acting on swimming marine mammals is difficult to measure directly. Researchers often use simple modeling and kinematic measurements from animals, or computational fluid dynamics (CFD) simulations to estimate drag. However, studies that compare these methods are lacking. Here, computational simulation and physical experiments were used to estimate drag forces on gliding bottlenose dolphins (Tursiops truncatus). To facilitate comparison, variable drag loading (no-tag, tag, tag + 4, tag + 8) was used to increase force in both simulations and experiments. During the experiments, two dolphins were trained to perform controlled glides with variable loading. CFD simulations of dolphin/tag geometry in steady flow (1–6 m/s) were used to model drag forces. We expect both techniques will capture relative changes created by experimental conditions, but absolute forces predicted by the methods will differ. CFD estimates were within a calculated 90% confidence interval of the experimental results for all but the tag condition. Relative drag increase predicted by the simulation vs. experiment, respectively, differed by between 21% and 31%: tag, 4% vs. 33%; tag + 4, 47% vs. 68%; and tag + 8, 108% vs. 77%. The results from this work provide a direct comparison of computational and experimental estimates of drag, and provide a framework to quantify uncertainty.     

New ichnotaxon Megascolytinus zherikhini (Coleoptera: Curculionidae: Scolytinae) from upper cretaceous deposits of mongolia

Gallery systems of Scolytinae on a petrified Araucaria trunk fragment from the Late Cretaceous of Gobi, Mongolia, similar to those of extant members of the supertribe Hylesininae, but exceptionally large (estimated body length of the beetle about 20 mm), are described as a new ichnotaxon, Megascolytinus zheriknini.     

Non-identifiability of the Rayleigh damping material model in Magnetic Resonance Elastography

Magnetic Resonance Elastography (MRE) is an emerging imaging modality for quantifying soft tissue elasticity deduced from displacement measurements within the tissue obtained by phase sensitive Magnetic Resonance Imaging (MRI) techniques. MRE has potential to detect a range of pathologies, diseases and cancer formations, especially tumors. The mechanical model commonly used in MRE is linear viscoelasticity (VE). An alternative Rayleigh damping (RD) model for soft tissue attenuation is used with a subspace-based nonlinear inversion (SNLI) algorithm to reconstruct viscoelastic properties, energy attenuation mechanisms and concomitant damping behavior of the tissue-simulating phantoms. This research performs a thorough evaluation of the RD model in MRE focusing on unique identification of RD parameters, _μI${\mu }_I$ and _ρI${\rho }_I$.     

Three new species of Trissolcus ashmead (Hymenoptera: Platygastroidea: Scelionidae) from Bulgaria

Identification key of 20 species of the genus Trissolcus registered in Bulgaria is given. Three species, T. fuscus sp. n., T. simplex sp. n. and T. nigricans sp. n. are described as new for science.     

The effect of type I collagen and fibronectin on the morphology of human mesenchymal stromal cells in culture

Limited knowledge of the behavior of stem cells in culture seems to be one of the reasons for problems in their successful introduction to applied medicine. To address this issue, we studied in vitro interaction of human mesenchymal stromal cells (MSCs) with various substrates (plastic, type I collagen, fibronectin, and mixtures of these proteins at various ratios) for 16–18 h after cell plating. Several cell-morphology features, such as area, perimeter, spreading coefficient, and polarization coefficient were determined. It is shown that MSCs specifically respond to the substrate and consist of several groups. Collagen and fibronectin have opposite effects on polarization and spreading of the cells. Collagen preferably enhances polarization of the cells, whereas fibronectin stimulates proportional spreading of cells. The combined effect on the cells of the collagen-fibronectin mixture cannot be considered as a simple additive effect. We assume that variations in the ratio of ECM proteins may be one mechanism of a directed action on stem cells.