Behavior of interfacial micro-defects in aluminum and its oxide film

In this dissertation, numerical simulation was used to calculate the equilibrium solution composition of cylindrical nanopores in surface oxide films as a step to evaluate their possible roles in the breakdown of protective oxide films. The solution composition of such nanopores is of interest from a corrosion perspective, since they play prominent roles in several mechanisms for the breakdown of passive films leading to pitting corrosion. The chemical composition of the pore solution would determine whether rapid dissolution at the pore could initiate. The effects of nanoscale pore dimensions, solution pH and adsorbing ion borate concentration on the solution composition in the pore were examined. Additionally, the behavior of interfacial voids in aluminum and voids in aluminum oxide films, of interest as corrosion initiation sites, was investigated using Atomic Force Microscopy (AFM), Transmission Electron Microscopy, and Positron Annihilation Spectroscopy (PAS). TEM successfully detected circular voids with size of ~50 nm in anodic films. The depth profiles of voids in the oxide film were also obtained from AFM images after different extents of oxide stripping. The result demonstrated that oxide voids are formed at the metal-film interface during anodic oxide growth, likely as a result of the oxidation of metal atoms. The result also suggested that metallic voids are formed repeatedly at certain sites on the metal surface

Comparison of the effects of Tripterygii totorum and sulfasalazine on rheumatoid arthritis: A retrospective cohort study

Purpose: To compare, in a retrospective study, the effects and safety profiles of Tripterygii totorum and sulfasalazine in patients with rheumatoid arthritis (RA) following 24 weeks of treatment. Methods: RA patients (n = 164) who were treated with Tripterygii totorum or sulfasalazine from August 2012 to February 2016 were included in this study. The major end-point was ≥ 20 % improvement as per American College of Rheumatology (ACR) criterion (ACR 20 response) after 24 weeks. Moreover, ACR 50 and ACR 70 responses were studied. The safety parameters investigated comprised of adverse events, vital signs, as well as hematological and biochemical indices (blood counts, electrolyte levels, and kidney and liver function). Results: At 24 weeks, ACR 20 response was 57.32 % in patients on Tripterygii totorum, while the corresponding value in patients on sulfasalazine was 39.02 % (p = 0.02). In the Tripterygii totorum group, ACR 50 response was 41.46 %, while ACR 70 response was 29.27 %. In sulfasalazine group, ACR 50 response was identified in 26.83 % of the patients, while ACR 70 response was seen in 21.95 % of patients. Adverse events were greater in the Tripterygii totorum group than in sulfasalazine group. Conclusion: These results suggest that Tripterygii Totorum significantly mitigates RA, with a tolerable safety profile. However, there is need for long-term or controlled trials to ascertain the therapeutic potential of Tripterygii totorum in RA. Keywords: Traditional Chinese medicine, Tripterygii totorum, Sulfasalazine, Rheumatoid arthriti

Effect of Impurities on Interfacial Void Formation in Aluminum

The effect of impurities on formation of interfacial metallic voids, during uniform dissolution of aluminum in 1 M NaOH, was investigated. These voids are thought to act as initiation sites for pitting corrosion, and were previously shown to be formed by NaOH dissolution. Samples of three different bulk purities were compared: 99.98, 99.997, and 99.9995%. Positron annihilation spectroscopy and atomic force microscopy revealed that nanometer-scale voids were formed by dissolution in each foil. For each sample, the void volume fraction interpreted from these measurements increased to a maximum during dissolution, and then declined. As the purity increased, more extensive dissolution was required to produce voids. Accumulation of near-surface Cu and Fe impurities during dissolution was characterized using Rutherford backscattering spectrometry. The results suggested a possible general correlation of void volume fraction with copper surface concentration. Processes involving near-surface copper impurities may then at least partly control the formation of voids. © 2004 The Electrochemical Society. All rights reserved

Behavior of interfacial micro-defects in aluminum and its oxide film

In this dissertation, numerical simulation was used to calculate the equilibrium solution composition of cylindrical nanopores in surface oxide films as a step to evaluate their possible roles in the breakdown of protective oxide films. The solution composition of such nanopores is of interest from a corrosion perspective, since they play prominent roles in several mechanisms for the breakdown of passive films leading to pitting corrosion. The chemical composition of the pore solution would determine whether rapid dissolution at the pore could initiate. The effects of nanoscale pore dimensions, solution pH and adsorbing ion borate concentration on the solution composition in the pore were examined. Additionally, the behavior of interfacial voids in aluminum and voids in aluminum oxide films, of interest as corrosion initiation sites, was investigated using Atomic Force Microscopy (AFM), Transmission Electron Microscopy, and Positron Annihilation Spectroscopy (PAS). TEM successfully detected circular voids with size of ~50 nm in anodic films. The depth profiles of voids in the oxide film were also obtained from AFM images after different extents of oxide stripping. The result demonstrated that oxide voids are formed at the metal-film interface during anodic oxide growth, likely as a result of the oxidation of metal atoms. The result also suggested that metallic voids are formed repeatedly at certain sites on the metal surface.</p

Selection of logging-based TOC calculation methods for shale reservoirs: A case study of the Jiaoshiba shale gas field in the Sichuan Basin

Various methods are available for calculating the TOC of shale reservoirs with logging data, and each method has its unique applicability and accuracy. So it is especially important to establish a regional experimental calculation model based on a thorough analysis of their applicability. With the Upper Ordovician Wufeng Fm-Lower Silurian Longmaxi Fm shale reservoirs as an example, TOC calculation models were built by use of the improved ΔlgR, bulk density, natural gamma spectroscopy, multi-fitting and volume model methods respectively, considering the previous research results and the geologic features of the area. These models were compared based on the core data. Finally, the bulk density method was selected as the regional experimental calculation model. Field practices demonstrated that the improved ΔlgR and natural gamma spectroscopy methods are poor in accuracy; although the multi-fitting method and bulk density method have relatively high accuracy, the bulk density method is simpler and wider in application. For further verifying its applicability, the bulk density method was applied to calculate the TOC of shale reservoirs in several key wells in the Jiaoshiba shale gas field, Sichuan Basin, and the calculation accuracy was clarified with the measured data of core samples, showing that the coincidence rate of logging-based TOC calculation is up to 90.5%–91.0%

Effect of Impurities on Interfacial Void Formation in Aluminum

The effect of impurities on formation of interfacial metallic voids, during uniform dissolution of aluminum in 1 M NaOH, was investigated. These voids are thought to act as initiation sites for pitting corrosion, and were previously shown to be formed by NaOH dissolution. Samples of three different bulk purities were compared: 99.98, 99.997, and 99.9995%. Positron annihilation spectroscopy and atomic force microscopy revealed that nanometer-scale voids were formed by dissolution in each foil. For each sample, the void volume fraction interpreted from these measurements increased to a maximum during dissolution, and then declined. As the purity increased, more extensive dissolution was required to produce voids. Accumulation of near-surface Cu and Fe impurities during dissolution was characterized using Rutherford backscattering spectrometry. The results suggested a possible general correlation of void volume fraction with copper surface concentration. Processes involving near-surface copper impurities may then at least partly control the formation of voids. © 2004 The Electrochemical Society. All rights reserved.This article is from Journal of the Electrochemical Society 151 (2004): B227–B232, doi:10.1149/1.1666148. Posted with permission.</p

Effect of Impurities on Interfacial Void Formation in Aluminum

The effect of impurities on formation of interfacial metallic voids, during uniform dissolution of aluminum in 1 M NaOH, was investigated. These voids are thought to act as initiation sites for pitting. Foils of three different bulk purities were used: 99.98% (3N), 99.997% (4N), and 99.9995% (5N). Positron Annihilation Spectroscopy (PAS) and Atomic Force Microscopy (AFM) revealed that nm-scale voids were formed by dissolution in each foil. The void volume fraction increased to a maximum during dissolution, at a time which increased with foil purity. The concurrent accumulation of near-surface Cu and Fe impurities during caustic etching was characterized using Rutherford backscattering spectrometry (RBS). For the three foils, a correlation of void volume fraction with Cu surface concentration was suggested. Processes involving Cu impurities may then at least partly control the formation of voids.The archival version of this work was published in R. Huang, K. R. Hebert, T. Gessmann, and K. G. Lynn “Effect of Impurities on Interfacial Void Formation on Aluminum During Dissolution Processes,” in Critical Factors in Localized Corrosion IV, P. Schmuki, S. Virtanen and G. S. Frankel, Editors, PV 2002-24, 359-367, The Electrochemical Society Proceedings Volume Series, Pennington, NJ (2003).</p

Curcumin Inhibits Proliferation and Epithelial-Mesenchymal Transition in Lens Epithelial Cells through Multiple Pathways

Background. Posterior capsule opacification (PCO), a complication of extracapsular lens extraction surgery that causes visual impairment, is characterized by aberrant proliferation and epithelial-mesenchymal transition (EMT) of lens epithelial cells (LECs). Curcumin, exerting inhibitive effects on cell proliferation and EMT in cancer, serves as a possible antidote towards PCO. Methods. Cellular proliferation of LECs after treatment of curcumin was measured with MTT assay and flow cytometry. The transcriptional and expressional levels of proteins related to proliferation and EMT of LECs were quantified by western blotting and real-time PCR. Results. Curcumin was found to suppress the proliferation of LECs by inducing G2/M arrest via possible inhibition of cell cycle-related proteins including CDK1, cyclin B1, and CDC25C. It had also inactivated proliferation pathways involving ERK1/2 and Akt pathways in LECs. On the other hand, curcumin downregulated the EMT of LECs through blocking the TGF-β/Smad pathway and interfering Notch pathway which play important roles in PCO. Conclusions. This study shows that curcumin could suppress the proliferation and EMT in LECs, and it might be a potential therapeutic protection against visual loss induced by PCO