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The objective of this study is to establish the corrosion behaviour of the most important structural constituents of the aluminium alloy 2017 in orthophosphoric acid solutions containing heteropolyoxomolybdate, tungstate and vanadate. These are potential candidates for replacing toxic hexavalent chromium species in stripping solution for anodic coatings. The corrosion rate of the alloy is estimated with linear polarisation method. It decreases from 0.58 mA cm−2 in uninhibited solution to 0.10 mA cm−2 in a solution containing heteropolyoxomolybdate species. Microscopic studies reveal that heteropolyoxomolybdate species inhibit corrosion of the matrix and intermetallic Al15(Fe,Mn)3(Si,Cu)2 but not Mg2Si. Intermetallic Al2Cu remains not corroded. Heteropolyoxotungstate species virtually do not inhibit the corrosion of the alloy. The solution containing vanadium species is not stable with time and the corrosion rate is not determined. Nevertheless, corrosion of the matrix is inhibited, but intermetallics Al15(Fe,Mn)3(Si,Cu)2 together with Mg2Si are dissolved. X-ray photoelectron spectroscopy is used for examination of a corrosion product precipitated on the surface. 相似文献
103.
Elżbieta Dobrzyńska Dorota Kondej Joanna Kowalska Małgorzata Szewczyńska 《Indoor air》2021,31(6):1733-1758
Additive manufacturing, enabling rapid prototyping and so-called on-demand production, has become a common method of creating parts or whole devices. On a 3D printer, real objects are produced layer by layer, thus creating extraordinary possibilities as to the number of applications for this type of devices. The opportunities offered by this technique seem to be pushing new boundaries when it comes to both the use of 3D printing in practice and new materials from which the 3D objects can be printed. However, the question arises whether, at the same time, this solution is safe enough to be used without limitations, wherever and by everyone. According to the scientific reports, three-dimensional printing can pose a threat to the user, not only in terms of physical or mechanical hazards, but also through the potential emissions of chemical substances and fine particles. Thus, the presented publication collects information on the additive manufacturing, different techniques, and ways of printing with application of diverse raw materials. It presents an overview of the last 5 years’ publications focusing on 3D printing, especially regarding the potential chemical and particle emission resulting from the use of such printers in both the working environment and private spaces. 相似文献
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Lipp Natalia Dużmańska-Misiarczyk Natalia Strojny Agnieszka Strojny Paweł 《Virtual Reality》2021,25(2):279-292
Virtual Reality - Virtual reality can be used for educational purposes, particularly in demanding professions such as firefighting. Such virtual training may be useful for preparing trainees for... 相似文献
105.
Xiong Luo Lei Zhang Yiping Luo Zhuyun Cai Hua Zeng Tianlong Wang Zhiqing Liu Yixing Chen Xuexin Sheng Aquino Ernesto da Graça Mandlate Zifei Zhou Feng Chen Longpo Zheng 《Advanced functional materials》2023,33(26):2214036
The treatment of diabetic wound remains a big clinical challenge. Hydrogel that can provide physical barrier and humidity displays amazing potentials for managing the diabetic wounds healing. Herein, a new charge-driven self-assembled microsphere hydrogel scaffold (SMHS) is reported based on an electric charge interaction, by combining use of black phosphorus (BP)-contained chitosan methacryloyl (CS) microspheres with positive charge and basic fibroblast growth factor-contained hyaluronic acid methacryloyl (HA) microspheres with negative charge. The weak charge attraction among microspheres gives the SMHS the injectable characteristic. Due to the existence of BP, near-infrared (NIR) irradiation has obvious effects on the degradation and drug release behaviors of SMHS. Significantly, SMHS that combines the short-term physical (photothermal) intervention and long-term chemical (drug release) intervention may be promising in spatio-temporal regulation of regenerative microenvironment. SMHS with NIR irradiation (SMHS+NIR) can promote cell proliferation, cell migration, angiogenesis and macrophage polarization. Moreover, in diabetic rat skin wounds, SMHS+NIR significantly accelerates the wound healing process by simultaneously inhibiting the inflammatory response, promoting angiogenesis and tissues remodeling. The outcome of this research not only provides a biomaterial for diabetic wounds healing, but also demonstrates a new strategy for designing novel hydrogel-based biomaterials which have the free editing and combination functions. 相似文献
106.
Łukasz Jeż 《Algorithmica》2013,67(4):498-515
We give a memoryless scale-invariant randomized algorithm ReMix for Packet Scheduling that is e/(e?1)-competitive against an adaptive adversary. ReMix unifies most of previously known randomized algorithms, and its general analysis yields improved performance guarantees for several restricted variants, including the s-bounded instances. In particular, ReMix attains the optimum competitive ratio of 4/3 on 2-bounded instances. Our results are applicable to a more general problem, called Item Collection, in which only the relative order between packets’ deadlines is known. ReMix is the optimal memoryless randomized algorithm against adaptive adversary for that problem. 相似文献
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Kiwilsza Anna Milanowski Bartłomiej Drużbicki Kacper Coy L. Emerson Grzeszkowiak Mikołaj Jarek Marcin Mielcarek Jadwiga Lulek Janina Pajzderska Aleksandra Wąsicki Jan 《Journal of Porous Materials》2015,22(3):817-829
Journal of Porous Materials - Two mesoporous silica materials: MCM-41 and SBA-15 were applied as potential nanocarriers for poorly soluble drug—nimodipine. Drug incorporation was performed... 相似文献
110.
In the paper some results of the studies on parameters of capillary waves generated in 18H2N4WA type steel by means of light pulses of Nd3+ - glass laser with ultrasonic modulation of Q-factor of the optical resonator have been presented. 相似文献