Porosity in type 316
L stainless steel cold spray coatings is studied from two different aspects. The first is to examine, for a given level of porosity, the effect of coating thickness on corrosion ...behaviour. Beyond a critical coating thickness the substrate is no longer attacked in polarisation tests, which has implications for coatings that contain some porosity (including some thermal spray coatings). The second aspect examined is to approximate the stainless steel particles as non-deforming, and apply the powder metallurgy practice of mixing particle size distributions to improve coating density. The results show that coatings sprayed using mixed particle size distributions can have similar properties to those sprayed using fine particles alone, but without the processing difficulties of fine particles such as inconsistent powder feeding or nozzle fouling.
► We address the issue of porosity in austenitic stainless steel coatings. ► These particles undergo little deformation on impact. ► With a small level of porosity, coatings beyond a critical thickness are protective. ► Mixing particle size distributions reduces coating porosity. ► This is a more practical approach than spraying with fine particles.
Abstract Parkinson's disease (PD) is a progressive neurological disorder that is often associated with various gastrointestinal (GI) symptoms. The link between the alteration of dopaminergic system ...and the symptoms of the GI tract in PD is complicated. To determine the changes in the dopaminergic system in the GI tract in PD, two kinds of rodent PD models were used in the present study. One was 6-hydroxydopamine (6-OHDA) -treated rats in which 6-OHDA was microinjected in the bilateral substantia nigra (SN). The other was 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) -treated mice in which MPTP was injected intraperitoneally. Immunofluorescence, reverse transcription (RT)-real time polymerase chain reaction (PCR) and Western blot were used to evaluate and compare the levels of mRNA and protein expression of tyrosine hydroxylase (TH) and dopamine transporter (DAT) in the GI tract between normal and rodent PD models, as well as between 6-OHDA-treated rats and MPTP-treated mice. The results indicated that TH- and DAT-positive cells were widely distributed in the GI tract. There were significant differences in TH and DAT expression in the GI tract between normal and PD models, as well as between 6-OHDA-treated rats and MPTP-treated mice. The protein levels of TH and DAT in the GI tract were significantly increased in 6-OHDA-treated rats, but the protein level of TH was significantly decreased in MPTP-treated mice. In addition, there was visible atrophy of gastric epithelial parietal cells in MPTP-treated mice, although the protein level of DAT was not significantly changed. The different alterations of dopaminergic system in the GI tract of the two kinds of PD models might underline the differences in GI symptoms in PD patients and might be correlated with the disease severity and disease process affecting the GI tract.
The midline pattern of sternal ossification characteristic of the Cretaceous enantiornithine birds is unique among the Ornithodira, the group containing birds, nonavian dinosaurs and pterosaurs. This ...has been suggested to indicate that Enantiornithes is not the sister group of Ornithuromorpha, the clade that includes living birds and their close relatives, which would imply rampant convergence in many nonsternal features between enantiornithines and ornithuromorphs. However, detailed comparisons reveal greater similarity between neornithine (i.e. crown group bird) and enantiornithine modes of sternal ossification than previously recognized. Furthermore, a new subadult enantiornithine specimen demonstrates that sternal ossification followed a more typically ornithodiran pattern in basal members of the clade. This new specimen, referable to the Pengornithidae, indicates that the unique ossification pattern observed in other juvenile enantiornithines is derived within Enantiornithes. A similar but clearly distinct pattern appears to have evolved in parallel in the ornithuromorph lineage. The atypical mode of sternal ossification in some derived enantiornithines should be regarded as an autapomorphic condition rather than an indication that enantiornithines are not close relatives of ornithuromorphs. Based on what is known about molecular mechanisms for morphogenesis and the possible selective advantages, the parallel shifts to midline ossification that took place in derived enantiornithines and living neognathous birds appear to have been related to the development of a large ventral keel, which is only present in ornithuromorphs and enantiornithines. Midline ossification can serve to medially reinforce the sternum at a relatively early ontogenetic stage, which would have been especially beneficial during the protracted development of the superprecocial Cretaceous enantiornithines.
We present experimental studies on ion acceleration using an 800-nm circularly polarized laser pulse with a peak intensity of 6.9×10^{19} W/cm^{2} interacting with an overdense plasma that is ...produced by a laser prepulse ionizing an initially ultrathin plastic foil. The proton spectra exhibit spectral peaks at energies up to 9 MeV with energy spreads of 30% and fluxes as high as 3×10^{12} protons/MeV/sr. Two-dimensional particle-in-cell simulations reveal that collisionless shocks are efficiently launched by circularly polarized lasers in exploded plasmas, resulting in the acceleration of quasimonoenergetic proton beams. Furthermore, this scheme predicts the generation of quasimonoenergetic proton beams with peak energies of approximately 150 MeV using current laser technology, representing a significant step toward applications such as proton therapy.
A totally new grain refiner, Al
2Y, for cast Mg alloys has been predicted using the recently developed edge-to-edge matching (E2EM) crystallographic model. An addition of 0.6–1.0
wt.% Al into the ...Mg–10
wt.% Y melt promotes the in situ formation of Al
2Y, which reduces the average grain size from about 180 to 36
μm. Active nucleation Al
2Y particles were reproducibly observed at the centres of many refined grains. The excellent grain-refining efficiency is comparable to that of Zr for the same alloy, but the thermal stability of the grains refined by Al
2Y is much higher than those refined by Zr up to a temperature of 550
°C for 48
h. The mechanisms of grain refinement and the superior thermal stability of the refined grains due to Al addition in the Mg–Y alloy are discussed based on the current experimental results.
Both inflammatory processes and glutamatergic systems have been implicated in the pathophysiology of mood-related disorders. However, the role of caspase-1, a classic inflammatory caspase, in ...behavioral responses to chronic stress remains largely unknown. To address this issue, we examined the effects and underlying mechanisms of caspase-1 on preclinical murine models of depression. We found that loss of caspase-1 expression in Caspase-1
knockout mice alleviated chronic stress-induced depression-like behaviors, whereas overexpression of caspase-1 in the hippocampus of wild-type (WT) mice was sufficient to induce depression- and anxiety-like behaviors. Furthermore, chronic stress reduced glutamatergic neurotransmission and decreased surface expression of glutamate receptors in hippocampal pyramidal neurons of WT mice, but not Caspase-1
mice. Importantly, pharmacological inhibition of caspase-1-interleukin-1β (IL-1β) signaling pathway prevented the depression-like behaviors and the decrease in surface expression of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs) in stressed WT mice. Finally, the effects of chronic stress on both depression- and anxiety-like behaviors can be mimicked by exogenous intracerebroventricular (i.c.v.) administration of IL-1β in both WT and Caspase-1
mice. Taken together, our findings demonstrate that an increase in the caspase-1/IL-1β axis facilitates AMPAR internalization in the hippocampus, which dysregulates glutamatergic synaptic transmission, eventually resulting in depression-like behaviors. These results may represent an endophenotype for chronic stress-induced depression.
Galectin-1 (Gal-1) is involved in several pathological activities associated with tumor progression and chemoresistance, however, the role and molecular mechanism of Gal-1 activity in hepatocellular ...carcinoma (HCC) epithelial-mesenchymal transition (EMT) and sorafenib resistance remain enigmatic. In the present study, forced Gal-1 expression promoted HCC progression and sorafenib resistance. Gal-1 elevated αvβ3-integrin expression, leading to AKT activation. Moreover, Gal-1 overexpression induced HCC cell EMT via PI3K/AKT cascade activation. Clinically, our data revealed that Gal-1 overexpression is correlated with poor HCC survival outcomes and sorafenib response. These data suggest that Gal-1 may be a potential therapeutic target for HCC and a biomarker for predicting response to sorafenib treatment.
The contrasting effect of compression on the ability of gas diffusion layer (GDL) in polymer electrolyte membrane fuel cell to conduct fluid, heat and electron implies that there is an optimal ...clamping force for cell performance. For a given GDL, understanding its associated optimal compression needs to know how its conductive ability changes with compressive pressure. In this paper we investigated the impact of compression on the effective diffusion coefficient and thermal conductivity of a carbon‐cloth GDL. The interior microstructures of the GDL under different compressions were acquired using X‐ray tomography; microscopic models were then developed to simulate gas diffusion and heat transfer in the microstructures in both in‐plane and through‐plane directions. The effective diffusion coefficient and thermal conductivity were calculated by volumetrically averaging the simulated gas diffusive and thermal flux rates at micron scale. The results show that both effective diffusion coefficient and thermal conductivity were anisotropic and their values in the in‐plane direction were higher than in the through‐plane direction. With porosity decreasing under the compression, the effective diffusion coefficient decreased faster in the through‐plane direction than in the in‐plane direction; the formula derived by Nam and Kaviany was capable of describing the change of the effective diffusion coefficient with porosity in the in‐plane direction but not in the through‐plane direction. For heat transfer, as the porosity decreased, the thermal conductivity increased faster in the through‐plane direction than in the in‐plane direction, and the increase in both directions could fit to the formula of Das et al.
Objectives: The platelet-to-lymphocyte ratio (PLR) is a predictive clinical biomarker for different cancers. However, the results of several studies investigating the association between the PLR and ...the prognosis of ovarian cancer have been inconclusive. Therefore, there is a need to conduct a meta-analysis to estimate the prognostic value of the PLR in ovarian cancer.
Methods: We searched the EMBASE, Medline, PubMed, and Web of Science databases to identify clinical studies that had evaluated the association between the PLR and ovarian cancer prognosis. Outcomes evaluated included overall survival (OS) and progression-free survival (PFS). We also analyzed PLR differences between malignant ovarian masses and the controls.
Results: Twelve relevant studies that comprised 2340 patients were selected for the meta-analysis. The results revealed that elevated PLR was significantly associated with poor OS (hazard ratio (HR) 1.63, 95% confidence interval (CI) 1.05-2.56, p < 0.01) and PFS (HR 1.61, 95% CI 1.03-2.51, p < 0.01). The PLRs in malignant cases were higher than in controls (mean difference = 63.57, 95% CI 39.47-87.66, p < 0.00001).
Conclusion: An elevated PLR is associated with poor prognosis in patients with ovarian cancer. The PLR could be employed as a prognostic marker in patients with ovarian cancer.
By means of surface mechanical attrition treatment, nanometer-sized grains (with an average size of 30±5nm) were generated in the surface layer of a single-phase AZ91D alloy. Transmission electron ...microscopy investigations showed that the strain-induced grain refinement process in AZ91D alloy includes three steps. At the initial stage twinning dominates the plastic deformation and divides the coarse grains into finer twin platelets. With increasing strain, double twins and stacking faults form and a number of dislocation slip systems are activated, including basal plane systems, prismatic plane systems and pyramidal plane systems. As a result of the dislocation slip along these systems and of the cross slips, high-density dislocation arrays are formed which further subdivide the twin platelets into subgrains. Obvious evidence of dynamic recrystallization were identified within the high-strain-energy subgrains with a further increase of strain, leading to the formation of nano-sized grains in the surface layer.
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