Effect of MgO and K2O on High-Al Silicon–Manganese Alloy Slag Viscosity and Structure

The viscosity, melting proprieties, and molten structure of the high-Al silicon–manganese slag of SiO2–CaO–25 mass% Al2O3–MgO–MnO–K2O system with a varying MgO and K2O content were studied. The results show that with the increase in MgO content from 4 to 10 mass%, the measured viscosity and flow activation energy decreases, but K2O has an effect on increasing those of slags. However, the melting temperature increases due to the formation of high-melting-point phase spinel. Meanwhile, Fourier transform infrared (FTIR) and X-ray photoelectron spectra (XPS) were conducted to understand the variation of slag structure. The O2− dissociates from MgO can interact with the O0 within Si–O or Al–O network structures, corresponding to the decrease in the trough depth of [SiO4] tetrahedral and [AlO4] tetrahedral. However, when K2O is added into the molten slag, the K+ can accelerate the formation of [AlO4] tetrahedra, resulting in the increase in O0 and O− and the polymerization of the structure.

Impairment of Flow-Sensitive Inwardly Rectifying K + Channels via Disruption of Glycocalyx Mediates Obesity-Induced Endothelial Dysfunction

Objective: To determine if endothelial dysfunction in a mouse model of diet-induced obesity and in obese humans is mediated by the suppression of endothelial Kir (inwardly rectifying K + ) channels. Approach and Results: Endothelial dysfunction, observed as reduced dilations to flow, occurred after feeding mice a high-fat, Western diet for 8 weeks. The functional downregulation of endothelial Kir2.1 using dominant-negative Kir2.1 construct resulted in substantial reductions in the response to flow in mesenteric arteries of lean mice, whereas no effect was observed in arteries of obese mice. Overexpressing wild-type–Kir2.1 in endothelium of arteries from obese mice resulted in full recovery of the flow response. Exposing freshly isolated endothelial cells to fluid shear during patch-clamp electrophysiology revealed that the flow-sensitivity of Kir was virtually abolished in cells from obese mice. Atomic force microscopy revealed that the endothelial glycocalyx was stiffer and the thickness of the glycocalyx layer reduced in arteries from obese mice. We also identified that the length of the glycocalyx is critical to the flow-activation of Kir. Overexpressing Kir2.1 in endothelium of arteries from obese mice restored flow- and heparanase-sensitivity, indicating an important role for heparan sulfates in the flow-activation of Kir. Furthermore, the Kir2.1-dependent component of flow-induced vasodilation was lost in the endothelium of resistance arteries of obese humans obtained from biopsies collected during bariatric surgery. Conclusions: We conclude that obesity-induced impairment of flow-induced vasodilation is attributed to the loss of flow-sensitivity of endothelial Kir channels and propose that the latter is mediated by the biophysical alterations of the glycocalyx.

Effect of Solid Additives on the Rheological Property of Nitroglycerin Plasticized Nitrocellulose

The rheological properties of energetic materials comprising nitroglycerin plasticized nitrocellulose were studied using rheological tests in a parallel plate rheometer. The Carreau-Yasuda equation was applied to calculate the zero-shear viscosity, and the dependence of solid additives, temperature and solvent content on zero-shear viscosity was developed. One can study flow characteristics of the energetic materials by observing the zero-shear viscosity instead of the effect of solid additives, temperature and solvent content. Additionally, the relationship between zero-shear viscosity and additives concentration was studied. The Kissinger-Akahira-Sunose (KAS) method was used to obtain the viscous flow activation energy, and the equation to describe the relationship between solid additives concentration and viscous flow activation energy was represented. The Zero-Shear Viscosity (ZSV) test showed that temperature was the predominant effect on the ZSV value at low solvent content, as the concentration of solid additives increased, the ZSV value decreased at low solvent content but increased at high one, however, there is an opposite trend when graphene concentration is above 0.1%. The viscous flow activation energy showed different changing trends with solid concentration that increased at different solvent content. The master curves were obtained by Time-Temperature Equivalence Principle, the viscosity prediction model has been established and showed a good agreement with the experimental data, compared with the test results, the viscosity prediction model is more accurate at low temperature (15°C-25°C). The obtained knowledge of the different equations will form a contribution to the research on extrusion process of this energetic material containing Cyclotrimethylenetrinitramine (RDX) and graphene, and the results obtained by this research have certain practical significance of the extrusion process for this energetic material.

Latrophilins are essential for endothelial junctional fluid shear stress mechanotransduction

Endothelial cell (EC) responses to fluid shear stress (FSS) are crucial for vascular development, adult physiology and disease. PECAM1 is an important transducer but earlier events remain poorly understood. We therefore investigated heterotrimeric G proteins in FSS sensing. Knockdown (KD) in ECs of single Gα proteins had little effect but combined depletion of Gαi and Gαq/11 blocked all known PECAM1-dependent responses. Re-expression of Gαi2 and Gαq but not Gαi1 and Gαi3 rescued these effects. Sequence alignment and mutational studies identified that K307 in Gαi2 and Gq/11 (Q306 in Gαi1/3), determines participation in flow signaling. We developed pull-down assays for measuring Gα activation and found that this residue, localized to the GPCR interface, determines activation by FSS. We developed a protocol for affinity purification of GPCRs on activated Gα’s, which identified latrophilins (ADGRLs) as specific upstream interactors for Gαi2 and Gq/11. Depletion of latrophilin-2 blocked EC activation of Gαi2 and Gαq, downstream events in vitro, and flow-dependent vascular morphogenesis in zebrafish embryos. Surprisingly, latrophilin-2 depletion also blocked flow activation of two additional pathways activated at cell-cell junctions, Smad1/5 and Notch1, independently of Gα proteins. Latrophilins are thus central mediators of junctional shear stress mechanotransduction via Gα protein-dependent and -independent mechanisms.

Effects of viscous flow activation energies and viscosities on waterborne light-diffusion dip-coatings

Purpose This paper aims to prepare good waterborne light-diffusion dip-coatings (WLDDC) for the glass lampshade inner walls of LED lamp tubes, the effects of viscosities and viscous flow activation energies on these dip-coatings were investigated. Design/methodology/approach The WLDDC were prepared using white pigments, light-diffusion agents, additives and an acrylic emulsion. The dip-coatings were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy and a digital rotational viscometer, respectively. The effects of shear rates, temperatures and solids contents on the viscosities of the dip-coatings were studied. The viscous flow activation energies of these dip-coatings and the emulsion were calculated, compared and studied, respectively. Findings The results showed that the non-Newtonian behaviors of these dip-coatings were more prominent than that of the acrylic emulsion. When the temperature was maintained to be a constant and the shear rate was increased, the viscosity decreased and the shear stress increased. When the shear rate was maintained to be a constant, the viscosity decreased with increasing temperatures. The viscous flow activation energies of these dip-coatings decreased with the increasing shear rates. The higher solid contents of WLDDC were, the more its viscosity would decrease with the increasing shear rates, the more prominent its non-Newtonian behaviors would show. Practical implications A sample of good WLDDC with balanced properties was illustrated. Originality/value This investigation benefits to investigate waterborne environment-friendly dip-coatings for the inner glass walls of lamp tubes. This research provides an approach to optimize the viscosity parameters of light-diffusion dip-coatings.

Activation of Smad 2/3 signaling by low shear stress mediates artery inward remodeling

RationaleBlood vessel remodeling in response to changes in tissue demand is an important aspect of fitness and is often compromised in vascular disease. Endothelial cell (EC) sensing of fluid shear stress (FSS) governs vessel remodeling to maintain FSS at a specific magnitude or set point in healthy vessels.ObjectiveThe purpose of this study was to understand how shear stress-regulated Smad 2/3 contributes to artery remodeling.Methods and ResultsWe found that shear stress induces Smad 2/3 phosphorylation, nuclear translocation, and gene expression in ECs. Nuclear translocation and gene expression are maximal at low and decrease at high FSS. Reducing flow in the mouse carotid by ligation of branch vessels induces Smad2 nuclear localization in vivo. Activation of Smad 2/3 by FSS requires the Type I TGFβ family receptor Alk5 and the transmembrane protein Neuropilin-1. Flow activation of Smad 2/3 is mediated by increased sensitivity to BMP9 but not BMP10 or TGFβ. By contrast, flow activation of Smad 1/5 is maximal at physiological FSS and requires BMP9 or 10 binding to Alk1 and Endoglin. EC-specific deletion of Alk5 in mice blocks low flow-induced inward remodeling after carotid ligation.ConclusionsTogether, these data elucidate a novel pathway that mediates low flow-induced inward artery remodeling. These results may be relevant to inward remodeling in diseased vessels where Smad 2/3 is activated by pathological stimuli.

Research on Polymer Viscous Flow Activation Energy and Non-Newtonian Index Model Based on Feature Size

The viscous flow activation energy and non-Newtonian index properties of polymer based on feature size were studied through a series of experiments on the rheological properties of amorphous polymer polymethyl methacrylate (PMMA), semi-crystalline polymer polypropylene (PP), and crystalline polymer high-density polyethylene (HDPE) using capillary die with hole diameters of φ0.3 mm, φ0.5 mm, φ1.0 mm, and φ2.0 mm. The results show that the viscous flow activation energy of PMMA decreases with the feature size under microscopic scale. And the viscous flow activation energy of PP and HDPE increases with hole diameters of the die. Under macroscopic scale, the difference in viscous flow activation energy of all polymer materials is significantly reduced with hole diameters of the die. For the non-Newtonian index of the three polymer materials, it decreases with the feature size under the microscopic scale while it increases or does not change with the feature size under the macroscopic scale. At the same time, for different high polymer materials, the viscous flow activation energy model (SVAE model) and non-Newtonian index model (SNNE model) based on feature size were established. Finally, the accuracy and effectiveness of the SVAE model and the SNNE model are verified by comparing with the traditional model and reference data. The viscous flow activation energy and non-Newtonian index values of the polymer material can be calculated conveniently and accurately.