Particulate matter (PM) is the principal component of air pollution. PM includes a range of particle sizes, such as coarse, fine, and ultrafine particles. Particles that are <100 nm in diameter are ...defined as ultrafine particles (UFPs). UFPs are found to a large extent in urban air as both singlet and aggregated particles. UFPs are classified into two major categories based on their source. Typically, UFPs are incidentally generated in the environment, often as byproducts of fossil fuel combustion, condensation of semivolatile substances or industrial emissions, whereas nanoparticles are manufactured through controlled engineering processes. The primary exposure mechanism of PM is inhalation. Inhalation of PM exacerbates respiratory symptoms in patients with chronic airway diseases, but the mechanisms underlying this response remain unclear. This review offers insights into the mechanisms by which particles, including UFPs, influence airway inflammation and discusses several mechanisms that may explain the relationship between particulate air pollutants and human health, particularly respiratory health. Understanding the mechanisms of PM-mediated lung injury will enhance efforts to protect at-risk individuals from the harmful health effects of air pollutants.
High strength and ductility and vehicle's weight reduction are key issues for improving fuel efficiency in automotive industries. In addition, structural reinforcement components require high yield ...strength because the prevention or minimization of deformation is more important than the absorption of impact energy. In this study, new ultra-high-strength duplex lightweight Fe-0.5C-12Mn-7Al-(0,3)Cu (wt%) steels have been developed by varying annealing temperature. Here, Cu, an austenite stabilizer, not only raises the austenite volume fraction but also delays the recrystallization due to a solute drag effect, while it promotes the formation of Cu-rich B2 particles and Cu-segregated interfacial layers. The steels show the planar slip and fine dislocation substructures (Taylor lattices) as desirable deformation mechanisms. Non-shearable Cu-rich B2 particles, solid solution hardening of Cu, and delayed recrystallization greatly improve the yield strength (∼1 GPa) and strain hardening. Through these unique and excellent tensile properties together with weight saving of 10.4%, the present work provides a desirable possibility for applications to automotive reinforcement components preferentially requiring an excellent yield-to-tensile ratio.
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Hydrogen embrittlement (HE) has become an important issue in ultra-strong automotive steel applications. The addition of Mo to commercial 32MnB5 hot-stamping steel is preferred to enhance the ...strength levels with little ductility loss. However, the effects of solute Mo on HE have been rarely studied for developing 32MnB5 steel, and most studies on the alloying of Mo for interfacial cohesion have been conducted theoretically by calculating the cohesive energies in the Fe lattice. In this study, 0.15 wt.% Mo was added to the 32MnB5 steel and the resistance to HE was evaluated experimentally via electrochemical H-charging. The H-charged reference steel shows a large ductility loss (50–79%) after H-charging, while the addition of Mo significantly reduces the loss (17–26%) with sufficient post-elongation, indicating a higher resistance to HE. This is because the solute Mo decreases the H diffusivity, resulted from the high H affinity and repulsive strain field owing to the large atomic size of Mo. The direct observation of crack propagation reveals that the H-induced crack path changes from the prior austenite grain boundaries (PAGBs) to the grain interiors of H-enhanced slip planes. This is attributed to the reduced H- and strain-localization on the PAGBs by the solute Mo and the enhanced grain-boundary cohesion by Mo segregation. This work thus demonstrates the beneficial effects of the addition of Mo on the tensile properties and the intrinsic resistance to HE for the development of ultra-high-strength steels.
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It is essential to characterize the cellular properties of mesenchymal stem cell populations to maintain quality specifications and control in regenerative medicine. Biofunctional materials have been ...designed as artificial matrices for the stimulation of cell adhesion and specific cellular functions. We have developed recombinant maltose‐binding protein (MBP)‐fused proteins as artificial adhesion matrices to control human mesenchymal stem cell (hMSC) fate by using an integrin‐independent heparin sulfate proteoglycans‐mediated cell adhesion. In this study, we characterize cell adhesion‐dependent cellular behaviors of human adipose‐derived stem cells (hASCs) and human bone marrow stem cells (hBMSCs). We used an MBP‐fused basic fibroblast growth factor (MF)‐coated surface and fibronectin (FN)‐coated surface to restrict and support, respectively, integrin‐mediated adhesion. The cells adhered to MF exhibited restricted actin cytoskeleton organization and focal adhesion kinase phosphorylation. The hASCs and hBMSCs exhibited different cytoplasmic projection morphologies on MF. Both hASCs and hBMSCs differentiated more dominantly into osteogenic cells on FN than on MF. In contrast, hASCs differentiated more dominantly into adipogenic cells on MF than on FN, whereas hBMSCs differentiated predominantly into adipogenic cells on FN. The results indicate that hASCs exhibit a competitive differentiation potential (osteogenesis vs. adipogenesis) that depends on the cell adhesion matrix, whereas hBMSCs exhibit both adipogenesis and osteogenesis in integrin‐mediated adhesion and thus hBMSCs have noncompetitive differentiation potential. We suggest that comparing differentiation behaviors of hMSCs with the diversity of cell adhesion is an important way to characterize hMSCs for regenerative medicine.
A recombinant protein was designed to generate a novel cell adhesion mechanism. We found marked differences between human adipose‐derived stem cells and human bone marrow stem cells in cellular behavior and differentiation, depending on the cell adhesion mechanism.
Background Individual studies have suggested the utility of fractional exhaled nitric oxide (F eno ) measurement in detecting cough-variant asthma (CVA) and eosinophilic bronchitis (EB) in patients ...with chronic cough. Objective We sought to obtain summary estimates of diagnostic test accuracy of F eno measurement in predicting CVA, EB, or both in adults with chronic cough. Methods Electronic databases were searched for studies published until January 2016, without language restriction. Cross-sectional studies that reported the diagnostic accuracy of F eno measurement for detecting CVA or EB were included. Risk of bias was assessed with Quality Assessment of Diagnostic Accuracy Studies 2. Random effects meta-analyses were performed to obtain summary estimates of the diagnostic accuracy of F eno measurement. Results A total of 15 studies involving 2187 adults with chronic cough were identified. F eno measurement had a moderate diagnostic accuracy in predicting CVA in patients with chronic cough, showing the summary area under the curve to be 0.87 (95% CI, 0.83-0.89). Specificity was higher and more consistent than sensitivity (0.85 95% CI, 0.81-0.88 and 0.72 95% CI, 0.61-0.81, respectively). However, in the nonasthmatic population with chronic cough, the diagnostic accuracy to predict EB was found to be relatively lower (summary area under the curve, 0.81 95% CI, 0.77-0.84), and specificity was inconsistent. Conclusions The present meta-analyses indicated the diagnostic potential of F eno measurement as a rule-in test for detecting CVA in adult patients with chronic cough. However, F eno measurement may not be useful to predict EB in nonasthmatic subjects with chronic cough. These findings warrant further studies to validate the roles of F eno measurement in clinical practice of patients with chronic cough.
Although steel has been the workhorse of the automotive industry since the 1920s, the share by weight of steel and iron in an average light vehicle is now gradually decreasing, from 68.1 per cent in ...1995 to 60.1 per cent in 2011 (refs 1, 2). This has been driven by the low strength-to-weight ratio (specific strength) of iron and steel, and the desire to improve such mechanical properties with other materials. Recently, high-aluminium low-density steels have been actively studied as a means of increasing the specific strength of an alloy by reducing its density. But with increasing aluminium content a problem is encountered: brittle intermetallic compounds can form in the resulting alloys, leading to poor ductility. Here we show that an FeAl-type brittle but hard intermetallic compound (B2) can be effectively used as a strengthening second phase in high-aluminium low-density steel, while alleviating its harmful effect on ductility by controlling its morphology and dispersion. The specific tensile strength and ductility of the developed steel improve on those of the lightest and strongest metallic materials known, titanium alloys. We found that alloying of nickel catalyses the precipitation of nanometre-sized B2 particles in the face-centred cubic matrix of high-aluminium low-density steel during heat treatment of cold-rolled sheet steel. Our results demonstrate how intermetallic compounds can be harnessed in the alloy design of lightweight steels for structural applications and others.
The weldability is one of the key factors governing applications of TWinning-Induced Plasticity (TWIP) steels to automotive industries demanding high economy, environmental friendliness, and high ...performance. During spot welding of Zn-coated Al-containing TWIP steel sheets, liquid metal embrittlement (LME) frequently occurs by Zn infiltration into grain boundaries to form cracks, but the direct observation and detailed analysis of LME cracking are quite difficult because it occurs instantaneously within a second. Here in the present study, the LME was investigated by detailed microstructural evolutions of small Zn infiltrations or cracks as well as formation behavior of various intermetallic phases. In the heat-affected zone, the applied tensile stress and spot-welding heat tore down a diffusion-inhibiting Fe2Al5 layer formed between the Zn-coated layer and the TWIP steel substrate, and formed Zn-containing ferrite (α-Fe(Zn)) particles on the steel surface which provided paths for liquid Zn infiltration. α-Fe(Zn) particles played critical roles in accelerating the LME by reducing the ductility because they were brittle due to high contents of Zn and Al. In the present Al-containing TWIP steels, the increase in welding current generally aggravates the LME.
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