scholarly journals Corrosion of an Implanted Medical Device: Rare-Earth Magnet Case Study

2013 ◽  
Vol 19 (S2) ◽  
pp. 1834-1835
Author(s):  
E.P. Guyer ◽  
B. Pound ◽  
S. Crane

Extended abstract of a paper presented at Microscopy and Microanalysis 2013 in Indianapolis, Indiana, USA, August 4 – August 8, 2013.

Author(s):  
Sophia Kalantzakos

In 2010, because of a geopolitical incident between China and Japan, seventeen elements of the periodic table known as rare earths became notorious overnight. An “unofficial” and temporary embargo of rare-earth shipments to Japan alerted the world to China’s near monopoly position on the production and export of these indispensable elements for high-tech, defense, and renewable energy sources. A few months before the geopolitical confrontation, China had chosen to substantially cut export quotas of rare earths. Both events sent shockwaves across the markets, and rare-earth prices skyrocketed, prompting reactions from industrial nations and industry itself. The rare-earth crisis is not a simple trade dispute, however. It also raises questions about China’s use of economic statecraft and the impacts of growing resource competition. A detailed and nuanced examination of the rare-earth crisis provides a significant and distinctive case study of resource competition and its spill-over geopolitical effects. It sheds light on the formulation, deployment, longevity, effectiveness, and, perhaps, shortsightedness of policy responses by other industrial nations, while also providing an example of how China might choose to employ instruments of economic statecraft in its rise to superpower status.


2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Yucan Zheng ◽  
Zhihua Zhang ◽  
Kunlong Yan ◽  
Hongmei Guo ◽  
Mei Li ◽  
...  

Abstract Background The aim of this study was to characterize patients who ingested multiple rare-earth magnets, reveal the harm of rare-earth magnet foreign bodies in the digestive tract, and develop a clinical management algorithm. Methods This was a retrospective review of patients with rare-earth magnet foreign bodies in the digestive tract admitted to a university-affiliated pediatric medical center in China, between January 2016 and December 2019; the subset of medical data evaluated included clinical symptoms, signs, treatments and outcomes. Results A total of 51 cases were included in this study, including 36(70.6%) males and 15(29.4%) females. The magnets were passed naturally in 24(47.1%) patients and removed by intervention in 27(52.9%) patients, including 5(9.8%) cases by endoscopy and 22(43.1%) cases by surgery. Twenty-two (43.1%)cases had gastrointestinal obstruction, perforation, and fistula. Compared with the non-surgical group, the time of the surgical group from ingestion to arriving at the hospital was longer([80(5–336) vs 26(2–216)]hours, p < 0.001) while there was no significant difference in the mean age or the number of magnets swallowed. Conclusions Magnets are attractive to children, but lead to catastrophic consequences including gastrointestinal obstruction, perforation, and surgical interventions when ingested multiple magnets. Endoscopic resection should be urgently performed in the presence of multiple magnets as early as possible within 24 h, even in asymptomatic patients.


2004 ◽  
Vol 51 (3) ◽  
pp. 160-164
Author(s):  
Ken-ichi Machida ◽  
Masahiro Itoh ◽  
Masahiro Masuda ◽  
Seiji Kojima

2020 ◽  
Vol 7 ◽  

A three-dimensional field solution is presented foraxially polarized permanent magnet cylinders. The fieldcomponents are expressed in terms of finite sums of elementaryfunctions and are easily programmable. They can be used todetermine the operating point of rare-earth magnet cylinders.They are also useful for performing rapid parametriccalculations of field strength as a function of materialproperties and dimensions. The field components aredeveloped for different magnet arrangements by taking intoaccount the back iron. Also the method of images is used. Usingthe field equations, three-dimensional analytical expressionsare derived for computing the magnetic force between axiallypolarized permanent-magnet cylinders for different magneticarrangements. The field calculated results are in goodagreement with the experimental data.


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