Morpho-Physiological approach to the paracellular route for salivary secretion by isolated perfused submandibular gland

A part of the salivary components are shifted from the blood via a trans- and/ or paracellular route. The isolated, arterially perfused, salivary glands (submandibular and parotid glands) were used to assess paracellular transport functionally and morphologically. In the present study, the hydrostatic pressure of the perfusion was changed and the fluid secretion and paracellular transport of fluorescent dye in the isolated perfused submandibular gland were examined. The present findings lead to the conclusion that part of the paracellular transport could be driven by hydrostatic pressure, and that fluid movement drags the solutes

EpiChIP: gene-by-gene quantification of epigenetic modification levels

The combination of chromatin immunoprecipitation with next-generation sequencing technology (ChIP-seq) is a powerful and increasingly popular method for mapping protein–DNA interactions in a genome-wide fashion. The conventional way of analyzing this data is to identify sequencing peaks along the chromosomes that are significantly higher than the read background. For histone modifications and other epigenetic marks, it is often preferable to find a characteristic region of enrichment in sequencing reads relative to gene annotations. For instance, many histone modifications are typically enriched around transcription start sites. Calculating the optimal window that describes this enrichment allows one to quantify modification levels for each individual gene. Using data sets for the H3K9/14ac histone modification in Th cells and an accompanying IgG control, we present an analysis strategy that alternates between single gene and global data distribution levels and allows a clear distinction between experimental background and signal. Curve fitting permits false discovery rate-based classification of genes as modified versus unmodified. We have developed a software package called EpiChIP that carries out this type of analysis, including integration with and visualization of gene expression data

Plastic yielding and tensile strength of near-micrometer grain size pure iron

In order to investigate the influence on mechanical properties of grain size in the near-micrometer regime, samples of Fe with nearly full density were prepared using the spark plasma sintering (SPS) technique with average grain sizes of 1.0 mu m, 2.6 mu m and 4.0 mu m. In each of these samples the resulting sintered material was in a nearly fully-recrystallized condition with a random texture. The mechanical properties of the samples were examined via tensile testing. A strong dependence of the tensile flow characteristics on the average grain size was observed in this size regime, with the 1.0 mu m grain-size sample showing a very high strength, but no uniform elongation and a large yield drop developed in the 2.6 mu m grain-size sample. Analysis of the grain size dependence of yield strength suggests a positive Hall-Petch deviation from the expected grain boundary strengthening in the SPS Fe samples, assuming a typical range of values for the grain boundary strength (Hall-Petch coefficient). Pre-compression of the 2.6 mu m grain-size prior to tensile testing sample results in a removal of the yield drop and a corresponding large decrease in the yield stress by as much as 145 MPa. The observations suggest that the positive Hall-Petch deviation seen previously in the near-micrometer regime for fully recrystallized Al and Cu may also be present in Fe, and highlight the likely importance of dislocation source hardening in this grain size regime

Excellent tensile properties and deformation mechanisms in a FeCoNi-based medium entropy alloy with dual-heterogeneous structures

A dual-heterogeneous structure with both heterogeneous grain structure and coherent L1(2) nano-precipitate was obtained in a (FeCoNi)(86)Al7Ti7 medium-entropy alloy (MEA) after cold rolling, critical annealing, and aging treatments. The volume fraction of the L1(2) phase is found to increase from 0% to 34.5% after aging treatment, resulting in severer heterogeneity. The unaged samples of (FeCoNi)(86)Al7Ti7 MEA are found to have a much better synergy of strength and ductility as compared to the FeCoNi MEA. Moreover, the tensile properties for the aged samples of (FeCoNi)(86)Al7Ti7 MEA with dual-heterogeneous structures are even better than those for the corresponding unaged samples. The hetero-deformation-induced hardening plays a more important role in the aged samples than in the unaged samples, producing a higher density of geometrically necessary dislocations. High density dislocations are discovered in grain interiors for the aged samples and the deformation is dominated by the planar slip in the unaged samples. Meanwhile, a high density of dislocations are observed inside L1(2) nano-precipitates; thus, L1(2) nano-precipitates can be sheared by dislocations, indicating that L1(2) nano-precipitates are strong but deformable. The strong interactions between dislocations and L1(2) nano-precipitates should provide additional strain hardening for better tensile properties in the aged samples

Excellent dynamic properties and corresponding deformation mechanisms in a microband-induced plasticity steel with dual-heterogeneous structure

A dual-heterogeneous structure with dual phases and heterogeneous grains was designed in a high Mn microband-induced-plasticity (MBIP) steel. The heterogeneous structured sample exhibits similar dynamic shear yield strength, while exhibiting enhanced dynamic uniform shear strain and dynamic shear toughness by 36 % and 47 %, respectively, as compared to the homogeneous structured sample. The strain hardening mechanisms contributing to the excellent dynamic shear properties in the heterogeneous structured sample have been revealed. Firstly, the superior hetero-deformation-induced hardening capability of the heterogeneous structured sample arises from a higher density of geometrically necessary dislocations induced in each phase. Secondly, a pronounced strain rate effect is observed in body-centered cubic (BCC) grains and face-centered cubic (FCC) ultra-fine grains, leading to an elevated level of strain rate sensitivity. Finally, the MBIP effect is also observed in FCC coarse grains under dynamic loading. Moreover, the MBIP effect in FCC ultra-fine grains is more likely to occur at high strain rates due to the emergence of single-wall domain boundaries, which is not observed during quasi-static tensile testing. The present results provide new routes for designing impact-tolerant structures in advanced metals and alloys

Strain Rate Effect on Tensile Behavior for a High Specific Strength Steel: From Quasi-Static to Intermediate Strain Rates

The strain rate effect on the tensile behaviors of a high specific strength steel (HSSS) with dual-phase microstructure has been investigated. The yield strength, the ultimate strength and the tensile toughness were all observed to increase with increasing strain rates at the range of 0.0006 to 56/s, rendering this HSSS as an excellent candidate for an energy absorber in the automobile industry, since vehicle crushing often happens at intermediate strain rates. Back stress hardening has been found to play an important role for this HSSS due to load transfer and strain partitioning between two phases, and a higher strain rate could cause even higher strain partitioning in the softer austenite grains, delaying the deformation instability. Deformation twins are observed in the austenite grains at all strain rates to facilitate the uniform tensile deformation. The B2 phase (FeAl intermetallic compound) is less deformable at higher strain rates, resulting in easier brittle fracture in B2 particles, smaller dimple size and a higher density of phase interfaces in final fracture surfaces. Thus, more energy need be consumed during the final fracture for the experiments conducted at higher strain rates, resulting in better tensile toughness

Cooperative Multi-RIS Communications for Wideband mmWave MISO-OFDM Systems

International audienceReconfigurable intelligent surfaces (RISs) can shape the wireless environment for enhancing the communication performance. In this letter, we propose a cooperative multi-RIS assisted transmission scheme for a millimeter-wave multi-antenna orthogonal frequency division multiplexing system. We first put forward a delay matching based scheme for simultaneously estimating the multipath channels and the transmission delays of distributed RISs, which requires limited training overhead and feedback. Based on this scheme, we obtain a closed-form solution for the RIS phase shift. Then, we derive an analytical expression of the downlink rate, which is proved to increase logarithmically with the square number of RIS reflecting elements. Simulations are conducted to verify these observations