University of Massachusetts Amherst

About: University of Massachusetts Amherst is a education organization based out in Amherst Center, Massachusetts, United States. It is known for research contribution in the topics: Population & Galaxy. The organization has 37274 authors who have published 83965 publications receiving 3834996 citations. The organization is also known as: UMass Amherst & Massachusetts State College.

Tunable band gaps in bilayer transition-metal dichalcogenides

Abstract: We investigate band-gap tuning in bilayer transition-metal dichalcogenides by external electric fields applied perpendicular to the layers. Using density functional theory, we show that the fundamental band gap of MoS${}_{2}$, MoSe${}_{2}$, MoTe${}_{2}$, and WS${}_{2}$ bilayer structures continuously decreases with increasing applied electric fields, eventually rendering them metallic. We interpret our results in the light of the giant Stark effect and obtain a robust relationship, which is essentially characterized by the interlayer spacing, for the rate of change of band gap with applied external field. Our study expands the known space of layered materials with widely tunable band gaps beyond the classic example of bilayer graphene and suggests potential directions for fabrication of novel electronic and photonic devices.

Promoting Interspecies Electron Transfer with Biochar

Abstract: Biochar, a charcoal-like product of the incomplete combustion of organic materials, is an increasingly popular soil amendment designed to improve soil fertility. We investigated the possibility that biochar could promote direct interspecies electron transfer (DIET) in a manner similar to that previously reported for granular activated carbon (GAC). Although the biochars investigated were 1000 times less conductive than GAC, they stimulated DIET in co-cultures of Geobacter metallireducens with Geobacter sulfurreducens or Methanosarcina barkeri in which ethanol was the electron donor. Cells were attached to the biochar, yet not in close contact, suggesting that electrons were likely conducted through the biochar, rather than biological electrical connections. The finding that biochar can stimulate DIET may be an important consideration when amending soils with biochar and can help explain why biochar may enhance methane production from organic wastes under anaerobic conditions.

First X-Ray Scattering Studies on Electrostatically Levitated Metallic Liquids: Demonstrated Influence of Local Icosahedral Order on the Nucleation Barrier

Abstract: To explain the unusual stability of undercooled liquids against crystallization, Frank hypothesized that the local structures of undercooled liquids contain a significant degree of icosahedral short-range order, which is incompatible with long-range periodicity. We present here the first direct experimental demonstration of Frank's complete hypothesis, showing a correlation between the nucleation barrier and a growing icosahedral short-range order with decreasing temperature in a Ti39.5Zr39.5Ni21 liquid. A new experimental facility, BESL (Beamline Electrostatic Levitation), was developed to enable the synchrotron x-ray structural studies on deeply undercooled, reactive liquids.

Sea Level Rise and Implications for Low Lying Islands, Coasts and Communities

Abstract: Do Not Cite, Quote or Distribute 4-1 Total pages: 139 1 Chapter 4: Sea Level Rise and Implications for Low Lying Islands, Coasts and Communities 2 3 Coordinating Lead Authors: Michael Oppenheimer (USA), Bruce Glavovic (New Zealand), Tuhin Ghosh 4 (India) 5 6 Lead Authors: Amro Abd-Elgawad (Egypt), Rongshuo Cai (China), Miguel Cifuentes-Jara (Costa Rica), 7 Rob Deconto (USA), John Hay (Cook Islands), Jochen Hinkel (Germany), Federico Isla (Argentina), 8 Alexandre K. Magnan (France), Ben Marzeion (Germany), Benoit Meyssignac (France), Zita Sebesvari 9 (Hungary), AJ Smit (South Africa), Roderik van de Wal (Netherlands) 10 11 Contributing Authors: Maya Buchanan (USA), Gonéri Le Cozannet (France), Catia Domingues 12 (Australia), Virginie Duvat (France), Tamsin Edwards (UK), Miguel D. Fortes (Philippines), Thomas 13 Frederikse (Netherlands), Jean-Pierre Gattuso (France), Robert Kopp (USA), Erwin Lambert (Netherlands), 14 Elizabeth McLeod (USA), Mark Merrifield (USA), Siddharth Narayan (US), Robert J. Nicholls (UK), 15 Fabrice Renaud (UK), Jonathan Simm (UK), Jon Woodruff (USA), Poh Poh Wong (Singapore), Siyuan Xian 16 (USA) 17 18 Review Editors: Ayako Abe-Ouchi (Japan), Kapil Gupta (India), Joy Pereira (Malaysia) 19 20 Chapter Scientist Maya Buchanan (USA) 21 22 Date of Draft: 20 April 2018 23 24 Notes: TSU Compiled Version 25 26