Hydro-geochemical characteristics and transformation processes of the Lena River Delta branches

Previous studies have shown that arctic river delta systems are areas of accumulation of geochemical substances at the sea-river mixing zone. In the Lena River Delta our previous work shows the tendencies of water runoff redistribution changes and heterogeneity of suspended supply distribution along the delta branches, accumulation and erosion zone in the different parts of the delta. Nevertheless, the processes of geochemical flow transformation in the subaerial deltas are so far underestimated. In order to close this gap, we sampled water, suspended and bottom sediments in the Lena River Delta in the summer seasons of 2010 and 2014. Most of the sampling points were tight to the profiles of hydrological measurements held in the delta and highlighted in Fedorova et al. [2015]. The results show that geochemical transformation of the Lena River runoff is taking place in the delta. The most active time for the transformation is the summer season due to the activity of sediment accumulation and biogeochemical processes. Hydrological conditions in the delta affect also its hydrogeochemical characteristics. Furcation of the delta branches affects the hydrodynamic conditions of different delta areas. The factors influencing the geochemical characteristics of the delta were identified on the base of geochemical indexes approach applied to sediments and statistical factor analysis. Based on geochemical indexes (Al/Na, Si/Al, Fe/Mn and Fe/Al ratios) similar conditions were determined for the main branch of the Lena, the upstream parts of Bykovskaya and Tumatskaya branches and in Olenekskaya branch near Chay-Tumus. Despite of high runoff the branches are characterized by element accumulation, which can be explained by decreasing of flow turbulence and specificity redox conditions in these areas. Bottom sediments are one of the most important indicators of geochemical transformation processes. The results of statistical factor analysis show three main factors for formation of the these geochemical conditions in the delta: 1. the general water flow of the Lena River, which is influenced by the lithogenous base of the river catchment, 2. the cryogenic condition of the Lena Delta (permafrost degradation processes and cryogenic weathering) and 3. biogeochemical transformation during redistribution of chemical water components , suspended matter and bottom sediments. Acknowledgements The research was supported by grant No. 14-05-00787 A of Russian Foundation for Basic Research References Fedorova, I.; Chetverova, A.; Bolshiyanov, D.; Makarov, A.; Boike, J.; Heim, B.; Morgenstern, A.; Overduin, P. P.; Wegner, C.; Kashina, V.; Eulenburg, A.; Dobrotina, E. and Sidorina, I. [2015]: Lena Delta hydrology and geochemistry: long-term hydrological data and recent field observations. Biogeosciences, 12(2):345–363, doi:10.5194/bg-12-345-2015

Genome-wide analysis of gene regulation mechanisms during Drosophila spermatogenesis

Background During Drosophila spermatogenesis, testis-specific meiotic arrest complex (tMAC) and testis-specific TBP-associated factors (tTAF) contribute to activation of hundreds of genes required for meiosis and spermiogenesis. Intriguingly, tMAC is paralogous to the broadly expressed complex Myb-MuvB (MMB)/dREAM and Mip40 protein is shared by both complexes. tMAC acts as a gene activator in spermatocytes, while MMB/dREAM was shown to repress gene activity in many cell types. Results Our study addresses the intricate interplay between tMAC, tTAF, and MMB/dREAM during spermatogenesis. We used cell type-specific DamID to build the DNA-binding profiles of Cookie monster (tMAC), Cannonball (tTAF), and Mip40 (MMB/dREAM and tMAC) proteins in male germline cells. Incorporating the whole transcriptome analysis, we characterized the regulatory effects of these proteins and identified their gene targets. This analysis revealed that tTAFs complex is involved in activation of achi, vis, and topi meiosis arrest genes, implying that tTAFs may indirectly contribute to the regulation of Achi, Vis, and Topi targets. To understand the relationship between tMAC and MMB/dREAM, we performed Mip40 DamID in tTAF- and tMAC-deficient mutants demonstrating meiosis arrest phenotype. DamID profiles of Mip40 were highly dynamic across the stages of spermatogenesis and demonstrated a strong dependence on tMAC in spermatocytes. Integrative analysis of our data indicated that MMB/dREAM represses genes that are not expressed in spermatogenesis, whereas tMAC recruits Mip40 for subsequent gene activation in spermatocytes. Conclusions Discovered interdependencies allow to formulate a renewed model for tMAC and tTAFs action in Drosophila spermatogenesis demonstrating how tissue-specific genes are regulated

Civic Participation in a Hybrid Regime: Limited Pluralism in Policymaking and Delivery in Contemporary Russia

Copyright © The Author(s). Published by Government and Opposition Limited and Cambridge University Press 2017. This article asks why the Russian government has developed new avenues for public participation in policymaking and delivery and assesses the extent to which these avenues introduce pluralism into these processes. Drawing on 50 interviews with individuals and citizens’ groups involved in either public consultative bodies or socially oriented NGOs, the article demonstrates the government’s desire to harness the knowledge and abilities of citizens and civic groups in place of state departments perceived to be bureaucratic and inefficient, while controlling and curtailing their participation. Arguing that these countervailing tendencies can be conceptualized as limited pluralism, a category elaborated by Juan Linz and Alfred Stepan, we show that citizens and civic groups are able to influence policy outcomes to varying extents using these mechanisms

New Synthetic Thrombin Inhibitors: Molecular Design and Experimental Verification

BACKGROUND: The development of new anticoagulants is an important goal for the improvement of thromboses treatments. OBJECTIVES: The design, synthesis and experimental testing of new safe and effective small molecule direct thrombin inhibitors for intravenous administration. METHODS: Computer-aided molecular design of new thrombin inhibitors was performed using our original docking program SOL, which is based on the genetic algorithm of global energy minimization in the framework of a Merck Molecular Force Field. This program takes into account the effects of solvent. The designed molecules with the best scoring functions (calculated binding energies) were synthesized and their thrombin inhibitory activity evaluated experimentally in vitro using a chromogenic substrate in a buffer system and using a thrombin generation test in isolated plasma and in vivo using the newly developed model of hemodilution-induced hypercoagulation in rats. The acute toxicities of the most promising new thrombin inhibitors were evaluated in mice, and their stabilities in aqueous solutions were measured. RESULTS: New compounds that are both effective direct thrombin inhibitors (the best K(I) was <1 nM) and strong anticoagulants in plasma (an IC(50) in the thrombin generation assay of approximately 100 nM) were discovered. These compounds contain one of the following new residues as the basic fragment: isothiuronium, 4-aminopyridinium, or 2-aminothiazolinium. LD(50) values for the best new inhibitors ranged from 166.7 to >1111.1 mg/kg. A plasma-substituting solution supplemented with one of the new inhibitors prevented hypercoagulation in the rat model of hemodilution-induced hypercoagulation. Activities of the best new inhibitors in physiological saline (1 µM solutions) were stable after sterilization by autoclaving, and the inhibitors remained stable at long-term storage over more than 1.5 years at room temperature and at 4°C. CONCLUSIONS: The high efficacy, stability and low acute toxicity reveal that the inhibitors that were developed may be promising for potential medical applications

Modelling evidence of stress concentration mitigation at the micro-scale in polymer composites by the addition of carbon nanotubes

A versatile two-scale model was developed to investigate the use of carbon nanotubes for re-distribution and, eventually, suppression of stress concentrations on the micro-level in fiber-reinforced composites. With this model a variety of CNT assemblies could be generated including CNTs dispersed in the matrix, grown on fibers or spatially organized in a network. The presence of CNTs in a composite was found to induce strong heterogeneity in stress fields. CNTs grown on fibers were shown to suppress stress concentrations at the fiber/matrix interface but to increase stresses in resin rich zones between the forests. Agglomerated CNTs were found to behave as stiff microscopic particles leading to additional stress magnification. A promising way to suppress stress concentrations without affecting stresses in the rest of the matrix was to position CNTs in a network that is interdependent with fiber positions.publisher: Elsevier articletitle: Modelling evidence of stress concentration mitigation at the micro-scale in polymer composites by the addition of carbon nanotubes journaltitle: Carbon articlelink: http://dx.doi.org/10.1016/j.carbon.2014.10.061 content_type: article copyright: Copyright © 2014 Elsevier Ltd. All rights reserved.status: publishe

Inter-fiber stresses in composites with carbon nanotube grafted and coated fibers

Deposition of carbon nanotubes (CNT) on fiber surfaces is a promising technique to add functionalities to polymer composites. Upon deformation, these CNTs generate local stress heterogeneities which may affect properties of the interphase and the composite. The stress disturbance depends on the morphology of deposited CNT assemblies also linked to a deposition technique. In the present work, two types of morphologies are investigated: (1) CNTs grown on fibers; and (2) CNTs deposited in fiber coatings. The difference in the two cases is the orientation of CNTs near the fiber interface: radial for grown CNTs and tangent for CNTs in the coatings. Different parameters including CNT length, morphology of the grafting and density of the coating are evaluated. The analysis is performed using a recently developed two-scale model. Results show that CNT grafted and coated fibers produce distinctly different interface stresses.publisher: Elsevier articletitle: Inter-fiber stresses in composites with carbon nanotube grafted and coated fibers journaltitle: Composites Science and Technology articlelink: http://dx.doi.org/10.1016/j.compscitech.2015.04.013 content_type: article copyright: Copyright © 2015 Elsevier Ltd. All rights reserved.status: publishe

Stress magnification due to carbon nanotube agglomeration in composites

© 2015 Elsevier Ltd. While poor dispersion of carbon nanotubes (CNTs) is often blamed for degradation of properties of CNT reinforced polymers and their composites, the evidence that CNT agglomerates generate stress concentrations is based on common sense and, to a large extent, indirect. The present study investigates the effect of CNT agglomerates on the inter-fiber stresses in a unidirectional fiber reinforced composite using a numerical approach. The two-scale model recently developed by the authors allows simulating realistic CNT agglomeration scenarios. A parametric study is performed focusing on the size and density of CNT agglomerates as well as on the degree of agglomeration from perfectly dispersed to partially and fully agglomerated states. The study concludes that CNT agglomerates of a higher density and bigger size produce higher stress concentrations. They also give rise to higher stresses at the fiber/matrix interface. The least disturbance on the stress fields is introduced by homogeneously dispersed CNTs.publisher: Elsevier articletitle: Stress magnification due to carbon nanotube agglomeration in composites journaltitle: Composite Structures articlelink: http://dx.doi.org/10.1016/j.compstruct.2015.07.069 content_type: article copyright: Copyright © 2015 Elsevier Ltd. All rights reserved.status: publishe

Can carbon nanotubes grown on fibers fundamentally change stress distribution in a composite?

In carbon fiber reinforced polymer composites the onset of damage occurs at the fiber/matrix interface, where stress concentrations are the highest due to the property mismatch of the two materials. This article reports results of a modelling study indicating that carbon nanotubes (CNTs) grown on fibers are effective in suppressing stress concentrations at the fiber/matrix interface. In the case of high density CNT forests, they can even fundamentally change a profile of the interfacial stress. The study is performed using a novel two-scale finite element model of a nano-engineered composite based on the embedded regions technique. © 2014 Elsevier Ltd. All rights reserved.publisher: Elsevier articletitle: Can carbon nanotubes grown on fibers fundamentally change stress distribution in a composite? journaltitle: Composites Part A: Applied Science and Manufacturing articlelink: http://dx.doi.org/10.1016/j.compositesa.2014.03.021 content_type: article copyright: Copyright © 2014 Elsevier Ltd. All rights reserved.status: publishe

Stress distribution around a broken carbon fibre and how it is affected by carbon nanotubes in the interface region

© 2018, © 2018 Informa UK Limited, trading as Taylor & Francis Group. We performed a numerical study to evaluate the influence of carbon nanotubes (CNTs) on the stress build-up in and around a broken fibre in a single carbon fibre/epoxy composite loaded longitudinally. The CNTs were located in the interface region and mimicked one of the two deposition techniques: 1) direct growth on the fibre or 2) dispersion in the fibre sizing. These techniques are known to produce different alignment, orientation and concentration of CNTs in a composite, which affect stress redistribution upon the fibre failure. The study was performed using a two-scale finite element model based on the embedded regions technique. The most significant effect on the stress build-up was found for CNTs aligned in the fibre direction. In this case, the crack opening displacement and the ineffective length were reduced by 15% and 28%, respectively, thus making the stress recovery in the broken fibre faster. In addition, the shear stress at the fibre-matrix interface decreased by a factor of two. These results indicate that hybridization of microscopic fibres with nanotubes aligned in the fibre direction is a promising strategy to influence the process of fibre fragmentation in a composite.status: publishe