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Design007-Oct2022

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OCTOBER 2022 I DESIGN007 MAGAZINE 61 vertical scale; using the proper termination components, the peak impedance was reduced by at least a factor of two. Conclusion Power planes provide a convenient means to connect multiple loads to a single power rail, but they introduce a series of modal reso- nances. e resonances can be suppressed by many bypass capacitors, or by using sufficiently thin dielectrics or by placing termination com- ponents along the plane periphery. DESIGN007 References 1. For an introductory overview and summary, see for instance, https://byjus.com/physics/maxwells- equations. 2. "Is Power Integrity the Next Black Magic?" Key- note webinar talk at E-learning By Cadence, April 12, 2021. 3. "Those Pesky Half-Wave Resonances," by Gus- tavo Blando, Signal Integrity Journal, Oct. 19, 2021. 4. "Microstrip antenna technology," by K.R. Carver and J.W. Mink, IEEE Transactions on Antennas and Propagation, AP-29, 1981, pp. 2-24. 5. Frequency Domain Characterization of Power Distribution Networks, Artech House, July 2007, ISBN-13: 978-1-59693-200-5. 6. "SUN's Experience with Thin and Ultra-Thin Laminates for Power Distribution Applications," DesignCon 2006, Santa Clara, CA, Feb. 6–9, 2006. 7. "Distributed Matched Bypassing for Power Dis- tribution Network," IEEE Tr. CPMT, August 2002. 8. "Impact of Power Plane Termination on System Noise," DesignCon 2021, San Jose, CA, Aug. 16–18, 2021. Istvan Novak is the principal sig- nal and power integrity engineer at Samtec with over 30 years of experience in high-speed digital, RF, and analog circuit and sys- tem design. He is a Life Fellow of the IEEE, author of two books on power integrity, and an instructor of signal and power integrity courses. He also provides a web- site that focuses on SI and PI techniques. To read past columns, click here. In a recent study, a team of scientists from Tokyo University of Science (TUS) and The Uni- versity of Tokyo in Japan reported a remarkably simple way to synthesize heterolayer coordi- nation nanosheets. Composed of the organic ligand, terpyridine, coordinating iron and cobalt, these nanosheets assemble themselves at the interface between two immiscible liquids in a peculiar way. To synthesize the heterolayer coordination nanosheets, the team first created the liquid-liq- uid interface to enable their assembly. They dis- solved tris(terpyridine) ligand in dichloromethane ( C H 2 C l 2 ) , a n o r g a n i c l i q u i d t h a t d o e s n o t m i x w i t h w a t e r. T h e y then poured a solution of water and ferrous tetrafluoroborate, an iron-containing chemi- cal, on top of the CH 2 Cl 2 . After 24 hours, the first layer of the coordina- tion nanosheet, bis(terpyridine)iron (or "Fe-tpy"), formed at the interface between both liquids. Following this, they removed the iron-contain- ing water and replaced it with cobalt-containing water. In the next few days, a bis(terpyridine) cobalt (or "Co-tpy") layer formed right below the iron-containing one at the liquid-liquid inter- face. The team made detailed observations of the heterolayer using various advanced techniques, such as scanning electron microscopy, X-ray pho- toelectron spectroscopy, atomic force micros- copy, and scanning transmission electron micros- copy. They found that the Co-tpy layer formed neatly below the Fe-tpy layer at the liquid-liquid interface. Moreover, they could control the thick- ness of the second layer depending on how long they left the synthesis process run its course. (Source: Tokyo University of Science) At the Water's Edge: Self-assembling 2D Materials at a Liquid-Liquid Interface

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