The connection analysis between the dilution of the deposited Fe-Cr-V-Mo-C layer by the basic metal and the parameters of its microstructure

In this work, the structure of the Fe-Cr-V-Mo-C coatings received by plasma transferred arc cladding was investigated. Coatings were deposited on plates with a thickness of 10 mm and made from constructional steel (steel 20). The correlation analysis of relationships between dilution of the deposited layers by the basic metal and the parameters of their microstructure was carried out. The parameters were as follows: volume fraction, a size, a shape factor, the distance between particles, the number of particles of vanadium carbide, volume fraction of the eutectic on the basis of carbide M[7]C[3] and the distances between its colonies, as well as the volume fraction of the [alpha]-phase in the alloy matrix

Plasma Ion Implantation of Silk Biomaterials Enabling Direct Covalent Immobilization of Bioactive Agents for Enhanced Cellular Responses

Silk fibroin isolated from Bombyx mori cocoons is a promising material for a range of biomedical applications, but it has no inherent cell-interactive domains, necessitating functionalization with bioactive molecules. Here we demonstrate significantly enhanced cell interactions with silk fibroin biomaterials in the absence of biofunctionalization following surface modification using plasma immersion ion implantation (PIII). Further, PIII treated silk fibroin biomaterials supported direct covalent immobilization of proteins on the material surface in the absence of chemical cross-linkers. Surface analysis after nitrogen plasma and PIII treatment at 20 kV revealed that the silk macromolecules are significantly fragmented, and at the higher fluences of implanted ions, surface carbonization was observed to depths corresponding to that of the ion penetration. Consistent with the activity of radicals created in the treated surface layer, oxidation was observed on contact with atmospheric oxygen and the PIII treated surfaces were capable of direct covalent immobilization of bioactive macromolecules. Changes in thickness, amide and nitrile groups, refractive index, and extinction coefficient in the wavelength range 400-1000 nm as a function of ion fluence are presented. Reactions responsible for the restructuring of the silk surface under ion beam treatment that facilitate covalent binding of proteins and a significant improvement in cell interactions on the modified surface are proposed

Plasma Activation of Microplates Optimized for One-Step Reagent-Free Immobilization of DNA and Protein

Activated microplates are widely used in biological assays and cell culture to immobilize biomolecules, either through passive physical adsorption or covalent cross-linking. Covalent attachment gives greater stability in complex biological mixtures. However, current multistep chemical activation methods add complexity and cost, require specific functional groups, and can introduce cytotoxic chemicals that affect downstream cellular applications. Here, we show a method for one-step linker-free activation of microplates by energetic ions from plasma for covalent immobilization of DNA and protein. Two types of energetic ion plasma treatment were shown to be effective: plasma immersion ion implantation (PIII) and plasma-activated coating (PAC). This is the first time that PIII and PAC have been reported in microwell plates with nonflat geometry. We confirm that the plasma treatment generates radical-activated surfaces at the bottom of wells despite potential shadowing from the walls. Comprehensive surface characterization studies were used to compare the PIII and PAC microplate surface composition, wettability, radical density, optical properties, stability, and biomolecule immobilization density. PAC plates were found to have more nitrogen and lower radical density and were more hydrophobic and more stable over 3 months than PIII plates. Optimal conditions were obtained for high-density DNA (PAC, 0 or 21% nitrogen, pH 3–4) and streptavidin (PAC, 21% nitrogen, pH 5–7) binding while retaining optical properties required for typical high-throughput biochemical microplate assays, such as low autofluorescence and high transparency. DNA hybridization and protein activity of immobilized molecules were confirmed. We show that PAC activation allows for high-density covalent immobilization of functional DNA and protein in a single step on both 96- and 384-well plates without specific linker chemistry. These microplates could be used in the future to bind other user-selected ligands in a wide range of applications, for example, for solid phase polymerase chain reaction and stem cell culture and differentiation

Asperities and barriers on the seismogenic zone in North Chile: state-of-the-art after the 2007 Mw 7.7 Tocopilla earthquake inferred by GPS and InSAR data

The Mw 7.7 2007 November 14 earthquake had an epicentre located close to the city of Tocopilla, at the southern end of a known seismic gap in North Chile. Through modelling of Global Positioning System (GPS) and radar interferometry (InSAR) data, we show that this event ruptured the deeper part of the seismogenic interface (30–50 km) and did not reach the surface. The earthquake initiated at the hypocentre and was arrested ~150 km south, beneath the Mejillones Peninsula, an area already identified as an important structural barrier between two segments of the Peru–Chile subduction zone. Our preferred models for the Tocopilla main shock show slip concentrated in two main asperities, consistent with previous inversions of seismological data. Slip appears to have propagated towards relatively shallow depths at its southern extremity, under the Mejillones Peninsula. Our analysis of post-seismic deformation suggests that small but still significant post-seismic slip occurred within the first 10 d after the main shock, and that it was mostly concentrated at the southern end of the rupture. The post-seismic deformation occurring in this period represents ~12–19 per cent of the coseismic deformation, of which ~30–55 per cent has been released aseismically. Post-seismic slip appears to concentrate within regions that exhibit low coseismic slip, suggesting that the afterslip distribution during the first month of the post-seismic interval complements the coseismic slip. The 2007 Tocopilla earthquake released only ~2.5 per cent of the moment deficit accumulated on the interface during the past 130 yr and may be regarded as a possible precursor of a larger subduction earthquake rupturing partially or completely the 500-km-long North Chile seismic gap

Multidimensional analyses reveal modulation of adaptive and innate immune subsets by tuberculosis vaccines

We characterize the breadth, function and phenotype of innate and adaptive cellular responses in a prevention of Mycobacterium tuberculosis infection trial. Responses are measured by whole blood intracellular cytokine staining at baseline and 70 days after vaccination with H4:IC31 (subunit vaccine containing Ag85B and TB10.4), Bacille Calmette-Guerin (BCG, a live attenuated vaccine) or placebo (n = ~30 per group). H4:IC31 vaccination induces Ag85B and TB10.4-specific CD4 T cells, and an unexpected NKTlike subset, that expresses IFN-γ, TNF and/or IL-2. BCG revaccination increases frequencies of CD4 T cell subsets that either express Th1 cytokines or IL-22, and modestly increases IFNγ-producing NK cells. In vitro BCG re-stimulation also triggers responses by donor-unrestricted T cells, which may contribute to host responses against mycobacteria. BCG, which demonstrated efficacy against sustained Mycobacterium tuberculosis infection, modulates multiple immune cell subsets, in particular conventional Th1 and Th22 cells, which should be investigated in discovery studies of correlates of protection

Depositional architecture, provenance, and tectonic/eustatic modulation of Miocene submarine fans in the Shikoku Basin: Results from Nankai Trough Seismogenic Zone Experiment

Seismostratigraphy, coring, and logging while drilling during Integrated Ocean Drilling Program Expeditions 319, 322, and 333 (Sites C0011/C0012) show three Miocene submarine fans in the NE Shikoku Basin, with broadly coeval deposits at Ocean Drilling Program Site 1177 and Deep Sea Drilling Project Site 297 (NW Shikoku Basin). The sediment dispersal patterns have major implications for paleogeographies at that time. The oldest, finer-grained (Kyushu) fan has sheet-like geometry; quartz-rich flows were fed mostly from an ancestral landmass in the East China Sea. During prolonged hemipelagic mud deposition at C0011-C0012 (~12.2 to 9.1 Ma), sand supply continued at Sites 1177 and 297. Sand delivery to much of the Shikoku Basin halted during a phase of sinistral strike slip to oblique plate motion, after which the Daiichi Zenisu Fan (~9.1 to 8.0 Ma) was fed by submarine channels. The youngest fan (Daini Zenisu; ~8.0 to 7.6 Ma) has sheet-like geometry with thick-bedded, coarse-grained pumiceous sandstones. The pumice fragments were fed from a mixed provenance that included the collision zone of the Izu-Bonin and Honshu Arcs. The shift from channelized to sheet-like flows was favored by renewal of relatively rapid northward subduction, which accentuated the trench as a bathymetric depression. Increased sand supply appears to correlate with long-term eustatic lowstands of sea level. The stratigraphic position and 3-D geometry of the sandbodies have important implications for subduction-related processes, including the potential for focused fluid flow and fluid overpressures above and below the plate boundary fault: In sheet-like sands, pathways for fluid flow have greater horizontal permeability compared with those in channel sands

Interactions between deformation and fluids in the frontal thrust region of the NanTroSEIZE transect offshore the Kii Peninsula, Japan: Results from IODP Expedition 316 Sites C0006 and C0007

Integrated Ocean Drilling Program (IODP) Expedition 316 Sites C0006 and C0007 examined the deformation front of the Nankai accretionary prism offshore the Kii Peninsula, Japan. In the drilling area, the frontal thrust shows unusual behavior as compared to other regions of the Nankai Trough. Drilling results, integrated with observations from seismic reflection profiles, suggest that the frontal thrust has been active since similar to 0.78-0.436 Ma and accommodated similar to 13 to 34% of the estimated plate convergence during that time. The remainder has likely been distributed among out-of-sequence thrusts further landward and/or accommodated through diffuse shortening. Unlike results of previous drilling on the Nankai margin, porosity data provide no indication of undercompaction beneath thrust faults. Furthermore, pore water geochemistry data lack clear indicators of fluid flow from depth. These differences may be related to coarser material with higher permeability or more complex patterns of faulting that could potentially provide more avenues for fluid escape. In turn, fluid pressures may affect deformation. Well-drained, sand-rich material under the frontal thrust could have increased fault strength and helped to maintain a large taper angle near the toe. Recent resumption of normal frontal imbrication is inferred from seismic reflection data. Associated decollement propagation into weaker sediments at depth may help explain evidence for recent slope failures within the frontal thrust region. This evidence consists of seafloor bathymetry, normal faults documented in cores, and low porosities in near surface sediments that suggest removal of overlying material. Overall, results provide insight into the complex interactions between incoming materials, deformation, and fluids in the frontal thrust region

The imperative for controlled mechanical stresses in unraveling cellular mechanisms of mechanotransduction

BACKGROUND: In vitro mechanotransduction studies are designed to elucidate cell behavior in response to a well-defined mechanical signal that is imparted to cultured cells, e.g. through fluid flow. Typically, flow rates are calculated based on a parallel plate flow assumption, to achieve a targeted cellular shear stress. This study evaluates the performance of specific flow/perfusion chambers in imparting the targeted stress at the cellular level. METHODS: To evaluate how well actual flow chambers meet their target stresses (set for 1 and 10 dyn/cm(2 )for this study) at a cellular level, computational models were developed to calculate flow velocity components and imparted shear stresses for a given pressure gradient. Computational predictions were validated with micro-particle image velocimetry (μPIV) experiments. RESULTS: Based on these computational and experimental studies, as few as 66% of cells seeded along the midplane of commonly implemented flow/perfusion chambers are subjected to stresses within ±10% of the target stress. In addition, flow velocities and shear stresses imparted through fluid drag vary as a function of location within each chamber. Hence, not only a limited number of cells are exposed to target stress levels within each chamber, but also neighboring cells may experience different flow regimes. Finally, flow regimes are highly dependent on flow chamber geometry, resulting in significant variation in magnitudes and spatial distributions of stress between chambers. CONCLUSION: The results of this study challenge the basic premise of in vitro mechanotransduction studies, i.e. that a controlled flow regime is applied to impart a defined mechanical stimulus to cells. These results also underscore the fact that data from studies in which different chambers are utilized can not be compared, even if the target stress regimes are comparable

The Enterovirus 71 A-particle Forms a Gateway to Allow Genome Release: A CryoEM Study of Picornavirus Uncoating

Since its discovery in 1969, enterovirus 71 (EV71) has emerged as a serious worldwide health threat. This human pathogen of the picornavirus family causes hand, foot, and mouth disease, and also has the capacity to invade the central nervous system to cause severe disease and death. Upon binding to a host receptor on the cell surface, the virus begins a two-step uncoating process, first forming an expanded, altered "A-particle", which is primed for genome release. In a second step after endocytosis, an unknown trigger leads to RNA expulsion, generating an intact, empty capsid. Cryo-electron microscopy reconstructions of these two capsid states provide insight into the mechanics of genome release. The EV71 A-particle capsid interacts with the genome near the icosahedral two-fold axis of symmetry, which opens to the external environment via a channel ~10 Å in diameter that is lined with patches of negatively charged residues. After the EV71 genome has been released, the two-fold channel shrinks, though the overall capsid dimensions are conserved. These structural characteristics identify the two-fold channel as the site where a gateway forms and regulates the process of genome release. © 2013 Shingler et al