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Observation of Bose-Einstein condensates in an Earth-orbiting research lab 期刊论文
NATURE, 2020, 582 (7811) : 103-+
作者:  Yamamoto, Keisuke;  Venida, Anthony;  Yano, Julian;  Biancur, Douglas E.;  Kakiuchi, Miwako;  Gupta, Suprit;  Sohn, Albert S. W.;  Mukhopadhyay, Subhadip;  Lin, Elaine Y.;  Parker, Seth J.;  Banh, Robert S.;  Paulo, Joao A.;  Wen, Kwun Wah;  Debnath, Jayanta;  Kim, Grace E.;  Mancias, Joseph D.;  Fearon, Douglas T.;  Perera, Rushika M.;  Kimmelman, Alec C.
收藏  |  浏览/下载:48/0  |  提交时间:2020/07/03

Quantum mechanics governs the microscopic world, where low mass and momentum reveal a natural wave-particle duality. Magnifying quantum behaviour to macroscopic scales is a major strength of the technique of cooling and trapping atomic gases, in which low momentum is engineered through extremely low temperatures. Advances in this field have achieved such precise control over atomic systems that gravity, often negligible when considering individual atoms, has emerged as a substantial obstacle. In particular, although weaker trapping fields would allow access to lower temperatures(1,2), gravity empties atom traps that are too weak. Additionally, inertial sensors based on cold atoms could reach better sensitivities if the free-fall time of the atoms after release from the trap could be made longer(3). Planetary orbit, specifically the condition of perpetual free-fall, offers to lift cold-atom studies beyond such terrestrial limitations. Here we report production of rubidium Bose-Einstein condensates (BECs) in an Earth-orbiting research laboratory, the Cold Atom Lab. We observe subnanokelvin BECs in weak trapping potentials with free-expansion times extending beyond one second, providing an initial demonstration of the advantages offered by a microgravity environment for cold-atom experiments and verifying the successful operation of this facility. With routine BEC production, continuing operations will support long-term investigations of trap topologies unique to microgravity(4,5), atom-laser sources(6), few-body physics(7,8)and pathfinding techniques for atom-wave interferometry(9-12).


  
Balancing security, resilience, and sustainability of urban water supply systems in a desirable operating space 期刊论文
ENVIRONMENTAL RESEARCH LETTERS, 2020, 15 (3)
作者:  Krueger, Elisabeth H.;  Borchardt, Dietrich;  Jawitz, James W.;  Rao, P. Suresh C.
收藏  |  浏览/下载:26/0  |  提交时间:2020/07/02
sustainable governance  Capital Portfolio Approach (CPA)  water footprint  ecological footprint  coupled natural-human-engineered systems (CNHE)  poverty trap  rigidity trap  
Antagonistic cooperativity between crystal growth modifiers 期刊论文
NATURE, 2020, 577 (7791) : 497-+
作者:  Ma, Wenchuan;  Lutsko, James F.;  Rimer, Jeffrey D.;  Vekilov, Peter G.
收藏  |  浏览/下载:14/0  |  提交时间:2020/07/03

Inhibitor pairs that suppress the crystallization of haematin, which is a part of malaria parasites'  physiology, show unexpected antagonism due to attenuation of step pinning by kink blockers.


Ubiquitous processes in nature and the industry exploit crystallization from multicomponent environments(1-5)  however, laboratory efforts have focused on the crystallization of pure solutes(6,7) and the effects of single growth modifiers(8,9). Here we examine the molecular mechanisms employed by pairs of inhibitors in blocking the crystallization of haematin, which is a model organic compound with relevance to the physiology of malaria parasites(10,11). We use a combination of scanning probe microscopy and molecular modelling to demonstrate that inhibitor pairs, whose constituents adopt distinct mechanisms of haematin growth inhibition, kink blocking and step pinning(12,13), exhibit both synergistic and antagonistic cooperativity depending on the inhibitor combination and applied concentrations. Synergism between two crystal growth modifiers is expected, but the antagonistic cooperativity of haematin inhibitors is not reflected in current crystal growth models. We demonstrate that kink blockers reduce the line tension of step edges, which facilitates both the nucleation of crystal layers and step propagation through the gates created by step pinners. The molecular viewpoint on cooperativity between crystallization modifiers provides guidance on the pairing of modifiers in the synthesis of crystalline materials. The proposed mechanisms indicate strategies to understand and control crystallization in both natural and engineered systems, which occurs in complex multicomponent media(1-3,8,9). In a broader context, our results highlight the complexity of crystal-modifier interactions mediated by the structure and dynamics of the crystal interface.


  
UDW Annual FY13 Format 科技报告
来源:US Department of Energy (DOE). 出版年: 2014
作者:  Rose, Kelly;  Guthrie, George
收藏  |  浏览/下载:18/0  |  提交时间:2019/04/05
deepwater oil and gas  ultra-deepwater oil and gas  engineered natural systems  oil and natural gas  wellbore integrity  borehole cement  borehole/drilling design  extreme offshore systems  offshore hydrocarbon detection