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排序方式: 共有2397条查询结果,搜索用时 31 毫秒
1.
Emir Mujanović Bojan Zajec Andraž Legat Tadeja Kosec Janez Kovač Gregor Mori Stefan Hönig Gerald Zehethofer 《工业材料与腐蚀》2021,72(3):421-433
Immersion tests with different stainless steels have been performed, while the pH was stepwise decreased and then increased again. During 8.5-day exposure, the depassivation and repassivation pH values as a function of pitting resistance equivalent number were determined. There is always a gap between both pH values (depassivation and repassivation), indicating that for every steel, there are conditions where an existing passive layer can be maintained but cannot be rebuilt after depassivation. In such environments, the passive layer is thicker, consisting mainly of molybdenum and iron rich oxides, while chromium is dissolved. Usually, depending on conditions, the passive layer is more chromium-rich, especially the inner layer. This is relevant, for example, for acidizing jobs in oil and gas industry, proving that repassivation after acidizing will happen promptly, when the pH is increased again. 相似文献
2.
Preliminary results on a single‐crystal nickel‐based superalloy indicated that hot corrosion can occur at temperatures as low as 550°C, where liquid formation, generally believed to be responsible for Type II hot corrosion, is not predicted. Additional tests were conducted on pure‐nickel samples at 650°C and below to more clearly elucidate the mechanism of this very low‐temperature hot corrosion. Environments in dry air and O2‐(2.5, 10, 100, and 1000) ppm SO2 were studied. Based on the results obtained, a solid‐state corrosion mechanism was inferred. The mechanism relies on the formation of a previously unreported compound phase, which was identified using transmission electron microscope analysis that indicated the stoichiometry of Na2Ni2SO5. Furthermore, it was nanocrystalline in structure and metastable. It was deduced that the Na2Ni2SO5 formation was responsible for the rapid nickel transport required for the observed accelerated corrosion process. Moreover, its eventual decomposition resulted in a mixed product of porous NiO with embedded particles of Na2SO4. Application of the proposed mechanism to nickel‐based alloys is discussed. 相似文献
3.
Václava Hazuková Jeffrey R. Johansen Gerald V. Sgro 《Journal of Great Lakes research》2019,45(1):98-108
We conducted a validation of the Planktonic Diatom Index (PDI) to demonstrate the utility of a water quality index for the monitoring of Lake Erie's nearshore pelagial zone. Using a large, independent dataset from the Western and Central Basins of Lake Erie for validation ensures realistic assessment of the performance of the index. Diatom-based biomonitoring allows for the inference of integrative information about water quality based on diatom species composition. The PDI is based on the assumption that phosphorus, an established proxy for eutrophication, is instrumental in the structuring of diatom communities. In this study, PDI scores and measured total phosphorus were significantly correlated (r2?=?0.34, r2?=?0.63 outliers removed). However, when samples were considered on a basin-wide basis, the PDI scores were not significantly predicted by measured total phosphorus in the Western Basin. We suggest that snapshot phosphorus measurements are less likely to represent the overall condition in the highly variable, eutrophic Western Basin. When multiple phosphorus measurements were averaged over time, the relationship with the integrative PDI scores was more apparent (r2?=?0.52). Through validation with an independent dataset, we show that the PDI is likely a monitoring tool that provides a robust assessment of water quality in the pelagial zone of the nearshore waters in Lake Erie. 相似文献
4.
Suman K. Das Elke Stadelmeyer Silvia Schauer Anna Schwarz Heimo Strohmaier Thiery Claudel Rudolf Zechner Gerald Hoefler Paul W. Vesely 《International journal of molecular sciences》2015,16(4):8555-8568
Lipolysis is the biochemical pathway responsible for the catabolism of cellular triacylglycerol (TG). Lipolytic TG breakdown is a central metabolic process leading to the generation of free fatty acids (FA) and glycerol, thereby regulating lipid, as well as energy homeostasis. The precise tuning of lipolysis is imperative to prevent lipotoxicity, obesity, diabetes and other related metabolic disorders. Here, we present our finding that miR-124a attenuates RNA and protein expression of the major TG hydrolase, adipose triglyceride lipase (ATGL/PNPLA2) and its co-activator comparative gene identification 58 (CGI-58/ABHD5). Ectopic expression of miR-124a in adipocytes leads to reduced lipolysis and increased cellular TG accumulation. This phenotype, however, can be rescued by overexpression of truncated Atgl lacking its 3''UTR, which harbors the identified miR-124a target site. In addition, we observe a strong negative correlation between miR-124a and Atgl expression in various murine tissues. Moreover, miR-124a regulates the expression of Atgl and Cgi-58 in murine white adipose tissue during fasting as well as the expression of Atgl in murine liver, during fasting and re-feeding. Together, these results point to an instrumental role of miR-124a in the regulation of TG catabolism. Therefore, we suggest that miR-124a may be involved in the regulation of several cellular and organismal metabolic parameters, including lipid storage and plasma FA concentration. 相似文献
5.
Gerald S. Poplin Timothy L. McMurry Jason L. Forman Thomas Hartka Gwansik Park Greg Shaw Jangho Shin Hyung joo Kim Jeff Crandall 《Accident; analysis and prevention》2015
Injuries to the hollow organs of the lower digestive system carry substantial risk of complication due to infection and blood loss, and commonly require invasive abdominal surgery to diagnose and treat. The causes of, and risk factors for, lower abdomen injury in automobile collisions are poorly understood. The goal of this study was to investigate the risk factors and potential mechanisms of hollow-organ, lower abdomen injury in belted automobile occupants in frontal collisions. 相似文献
6.
Daniel Boon Loong Teh Akshaya Bansal Chou Chai Tan Boon Toh Robert Alan Jappy Tucker Gil Gerald Lasam Gammad Yanzhuang Yeo Zhendong Lei Xiang Zheng Fengyuan Yang John S. Ho Nagarjun Bolem Bing Cheng Wu Muthu Kumar Gnanasammandhan Lissa Hooi Gavin Stewart Dawe Camilo Libedinsky Wei-Yi Ong Barry Halliwell Edward Kai-Hua Chow Kah-Leong Lim Yong Zhang Brian K. Kennedy 《Advanced materials (Deerfield Beach, Fla.)》2020,32(29):2001459
Near-infrared (NIR) activatable upconversion nanoparticles (UCNPs) enable wireless-based phototherapies by converting deep-tissue-penetrating NIR to visible light. UCNPs are therefore ideal as wireless transducers for photodynamic therapy (PDT) of deep-sited tumors. However, the retention of unsequestered UCNPs in tissue with minimal options for removal limits their clinical translation. To address this shortcoming, biocompatible UCNPs implants are developed to deliver upconversion photonic properties in a flexible, optical guide design. To enhance its translatability, the UCNPs implant is constructed with an FDA-approved poly(ethylene glycol) diacrylate (PEGDA) core clad with fluorinated ethylene propylene (FEP). The emission spectrum of the UCNPs implant can be tuned to overlap with the absorption spectra of the clinically relevant photosensitizer, 5-aminolevulinic acid (5-ALA). The UCNPs implant can wirelessly transmit upconverted visible light till 8 cm in length and in a bendable manner even when implanted underneath the skin or scalp. With this system, it is demonstrated that NIR-based chronic PDT is achievable in an untethered and noninvasive manner in a mouse xenograft glioblastoma multiforme (GBM) model. It is postulated that such encapsulated UCNPs implants represent a translational shift for wireless deep-tissue phototherapy by enabling sequestration of UCNPs without compromising wireless deep-tissue light delivery. 相似文献
7.
Paulo A. C. Lopes José A. B. Gerald 《International Journal of Adaptive Control and Signal Processing》2021,35(7):1370-1387
The mirror-modified filtered-x least mean squares (MMFxLMS ) algorithm is a variation of the FxLMS algorithm with online secondary path modeling that cannot diverge due to secondary path modeling errors. However, problems may occur when the ambient noise is not limited due to insufficient modeling power. This work shows that under a frequency domain analysis without ambient noise, the MMFxLMS algorithm is always stable, and expressions for the maximum residual noise level at any given time are obtained. It is also shown that, under the same context, convergence to the minimum residual noise is guaranteed. Still, convergence can be much slower for high secondary path modeling errors than that of the LMS or MFxLMS algorithms. Simulations confirm these results. 相似文献
8.
Christine Bandl Nina Krempl Gerald Berger-Weber Wolfgang Kern Walter Friesenbichler 《应用聚合物科学杂志》2021,138(30):50714
Easy and residue-free demolding is an everlasting topic in the plastics processing industry. Typically, facile ejection of the produced parts from the mold is provided by separation agents (silicon sprays, surface coatings). In this work, a perfluoroalkyl-based organosilane coating is applied to exchangeable substrates of an injection mold. Besides the simple application, the coating can also be restored easily in a procedure based on flame treatment. Coating and recoating are proven by contact angle measurements with water, while the anti-adhesive effect and the related relief during demolding are evaluated using a special measuring device in an instrumented two-plate injection mold. The results reveal that the organosilane layer reduces the demolding forces and the resulting static friction coefficient by 50%. Furthermore, multiple recoating significantly improves the durability of the anti-adhesive coating. Based on these findings, the easily applicable and renewable organosilane coating represents a suitable alternative to conventional release coatings. 相似文献
9.
Cemernek David Cemernek Sandra Gursch Heimo Pandeshwar Ashwini Leitner Thomas Berger Matthias Klösch Gerald Kern Roman 《Journal of Intelligent Manufacturing》2022,33(6):1561-1579
Journal of Intelligent Manufacturing - Continuous casting is the most important route for the production of steel today. Due to the physical, mechanical, and chemical components involved in the... 相似文献
10.
This research addresses the fracture mechanical analysis of two commercially available polyoxymethylene homopolymer resins. Two types of experiments are used: monotonic fracture toughness tests and cyclic fatigue crack growth tests. The resulting total lifetimes in the fatigue crack growth tests are split up into the appropriate parts of crack growth initiation and fatigue crack propagation. Fracture surfaces of monotonic and cyclic tests are analyzed using light microscopy and scanning electron microscopy. Besides the mechanical tests, the morphology within the used compact tension specimens is examined in detail by using differential scanning calorimetry, small‐ and wide‐angle X‐ray scattering, and polarized light microscopy. The results are analyzed and discussed, considering observations in the previous studies published in the literature. It is shown that both materials can be well analyzed using linear elastic fracture mechanics and their fracture mechanical properties are presented in conjunction with a detailed documentation of the microstructure. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40831. 相似文献