GSTDTAP

浏览/检索结果: 共5条,第1-5条 帮助

已选(0)清除 条数/页:   排序方式:
Single-chain heteropolymers transport protons selectively and rapidly 期刊论文
NATURE, 2020, 577 (7789) : 216-+
作者:  Jiang, Tao;  Hall, Aaron;  Eres, Marco;  Hemmatian, Zahra;  Qiao, Baofu;  Zhou, Yun;  Ruan, Zhiyuan;  Couse, Andrew D.;  Heller, William T.;  Huang, Haiyan;  de la Cruz, Monica Olvera;  Rolandi, Marco;  Xu, Ting
收藏  |  浏览/下载:20/0  |  提交时间:2020/07/03

Precise protein sequencing and folding are believed to generate the structure and chemical diversity of natural channels(1,2), both of which are essential to synthetically achieve proton transport performance comparable to that seen in natural systems. Geometrically defined channels have been fabricated using peptides, DNAs, carbon nanotubes, sequence-defined polymers and organic frameworks(3-13). However, none of these channels rivals the performance observed in their natural counterparts. Here we show that without forming an atomically structured channel, four-monomer-based random heteropolymers (RHPs)(14) can mimic membrane proteins and exhibit selective proton transport across lipid bilayers at a rate similar to those of natural proton channels. Statistical control over the monomer distribution in an RHP leads to segmental heterogeneity in hydrophobicity, which facilitates the insertion of single RHPs into the lipid bilayers. It also results in bilayer-spanning segments containing polar monomers that promote the formation of hydrogen-bonded chains(15,16) for proton transport. Our study demonstrates the importance of the adaptability that is enabled by statistical similarity among RHP chains and of the modularity provided by the chemical diversity of monomers, to achieve uniform behaviour in heterogeneous systems. Our results also validate statistical randomness as an unexplored approach to realize protein-like behaviour at the single-polymer-chain level in a predictable manner.


  
Ice front blocking of ocean heat transport to an Antarctic ice shelf 期刊论文
NATURE, 2020, 578 (7796) : 568-+
作者:  Alexandrov, Ludmil B.;  Kim, Jaegil;  Haradhvala, Nicholas J.;  Huang, Mi Ni;  Ng, Alvin Wei Tian;  Wu, Yang;  Boot, Arnoud;  Covington, Kyle R.;  Gordenin, Dmitry A.;  Bergstrom, Erik N.;  Islam, S. M. Ashiqul;  Lopez-Bigas, Nuria;  Klimczak, Leszek J.;  McPherson, John R.;  Morganella, Sandro;  Sabarinathan, Radhakrishnan;  Wheeler, David A.;  Mustonen, Ville;  Getz, Gad;  Rozen, Steven G.;  Stratton, Michael R.
收藏  |  浏览/下载:44/0  |  提交时间:2020/05/13

The front of the Getz Ice Shelf in West Antarctica creates an abrupt topographic step that deflects ocean currents, suppressing 70% of the heat delivery to the ice sheet.


Mass loss from the Antarctic Ice Sheet to the ocean has increased in recent decades, largely because the thinning of its floating ice shelves has allowed the outflow of grounded ice to accelerate(1,2). Enhanced basal melting of the ice shelves is thought to be the ultimate driver of change(2,3), motivating a recent focus on the processes that control ocean heat transport onto and across the seabed of the Antarctic continental shelf towards the ice(4-6). However, the shoreward heat flux typically far exceeds that required to match observed melt rates(2,7,8), suggesting that other critical controls exist. Here we show that the depth-independent (barotropic) component of the heat flow towards an ice shelf is blocked by the marked step shape of the ice front, and that only the depth-varying (baroclinic) component, which is typically much smaller, can enter the sub-ice cavity. Our results arise from direct observations of the Getz Ice Shelf system and laboratory experiments on a rotating platform. A similar blocking of the barotropic component may occur in other areas with comparable ice-bathymetry configurations, which may explain why changes in the density structure of the water column have been found to be a better indicator of basal melt rate variability than the heat transported onto the continental shelf(9). Representing the step topography of the ice front accurately in models is thus important for simulating ocean heat fluxes and induced melt rates.


  
Combined Effects of Mean Flow and Turbulence on Sediment Pickup Rate 期刊论文
WATER RESOURCES RESEARCH, 2020, 56 (2)
作者:  Cheng, N. S.;  Wei, M. X.;  Chiew, Y. M.;  Lu, Y. S.;  Emadzadeh, A.
收藏  |  浏览/下载:19/0  |  提交时间:2020/07/02
Sediment pickup rate  densimetric Froude number  turbulence  sediment transport  obstructed flow  
Coupling Radioactive Waste Glass Dissolution Measurements in Generic Groundwaters With Reactive Transport Modeling of Repository Scenarios 期刊论文
WATER RESOURCES RESEARCH, 2019
作者:  Iwalewa, T. M.;  Farnan, I.
收藏  |  浏览/下载:14/0  |  提交时间:2019/11/27
radioactive waste glass  dissolution rate  groundwater  reactive transport model  radionuclide  geological repository  
An improved numerical model suggests potential differences of wind-blown sand between on Earth and Mars 期刊论文
JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES, 2017, 122 (11)
作者:  Bo, T. L.;  Fu, L. T.;  Liu, L.;  Zheng, X. J.
收藏  |  浏览/下载:5/0  |  提交时间:2019/04/09
Mars  wind-blown sand  lift-off speed  lift-off angle  transport rate  saturation time