| 1. |
|
|
| 2. |
|
|
| 3. |
- Yu, ChaoQing, et al.
(författare)
-
Managing nitrogen to restore water quality in China
- 2019
-
Ingår i: Nature. - : Nature Publishing Group. - 0028-0836 .- 1476-4687. ; 567:7749, s. 516-520
-
Tidskriftsartikel (refereegranskat)abstract
- The nitrogen cycle has been radically changed by human activities(1). China consumes nearly one third of the world's nitrogen fertilizers. The excessive application of fertilizers(2,3) and increased nitrogen discharge from livestock, domestic and industrial sources have resulted in pervasive water pollution. Quantifying a nitrogen 'boundary'(4) in heterogeneous environments is important for the effective management of local water quality. Here we use a combination of water-quality observations and simulated nitrogen discharge from agricultural and other sources to estimate spatial patterns of nitrogen discharge into water bodies across China from 1955 to 2014. We find that the critical surface-water quality standard (1.0 milligrams of nitrogen per litre) was being exceeded in most provinces by the mid-1980s, and that current rates of anthropogenic nitrogen discharge (14.5 +/- 3.1 megatonnes of nitrogen per year) to fresh water are about 2.7 times the estimated 'safe' nitrogen discharge threshold (5.2 +/- 0.7 megatonnes of nitrogen per year). Current efforts to reduce pollution through wastewater treatment and by improving cropland nitrogen management can partially remedy this situation. Domestic wastewater treatment has helped to reduce net discharge by 0.7 +/- 0.1 megatonnes in 2014, but at high monetary and energy costs. Improved cropland nitrogen management could remove another 2.3 +/- 0.3 megatonnes of nitrogen per year-about 25 per cent of the excess discharge to fresh water. Successfully restoring a clean water environment in China will further require transformational changes to boost the national nutrient recycling rate from its current average of 36 per cent to about 87 per cent, which is a level typical of traditional Chinese agriculture. Although ambitious, such a high level of nitrogen recycling is technologically achievable at an estimated capital cost of approximately 100 billion US dollars and operating costs of 18-29 billion US dollars per year, and could provide co-benefits such as recycled wastewater for crop irrigation and improved environmental quality and ecosystem services.
|
|
| 4. |
- Björling, Marcus, et al.
(författare)
-
Warm carbon coat reduces friction
- 2014
-
Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 505:7483, s. 264-
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- A coating material made of carbon reduces friction not just by providing a slippery surface, but also by keeping the points of contact warm. Marcus Björling at Luleå University of Technology in Sweden and his team coated steel balls with ``diamond-like-carbon'' - a material in which carbon atoms have a bonding pattern similar to that of diamond. They rolled the balls against a metal disk with an oil lubricant in between, and showed that the carbon coating acts as an insulator, lowering the viscosity of the lubricant and thus reducing the fricion between the ball and the disk. These findings could encourage the development of lubricant coatings made from insulating materials.
|
|
| 5. |
- Boustras, Georgios, et al.
(författare)
-
Fires: fund research for citizen safety
- 2017
-
Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 551:7680, s. 300-300
-
Tidskriftsartikel (refereegranskat)
|
|
| 6. |
|
|
| 7. |
- Heurlin, Magnus, et al.
(författare)
-
Continuous gas-phase synthesis of nanowires with tunable properties.
- 2012
-
Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 492:7427, s. 90-94
-
Tidskriftsartikel (refereegranskat)abstract
- Semiconductor nanowires are key building blocks for the next generation of light-emitting diodes, solar cells and batteries. To fabricate functional nanowire-based devices on an industrial scale requires an efficient methodology that enables the mass production of nanowires with perfect crystallinity, reproducible and controlled dimensions and material composition, and low cost. So far there have been no reports of reliable methods that can satisfy all of these requirements. Here we show how aerotaxy, an aerosol-based growth method, can be used to grow nanowires continuously with controlled nanoscale dimensions, a high degree of crystallinity and at a remarkable growth rate. In our aerotaxy approach, catalytic size-selected Au aerosol particles induce nucleation and growth of GaAs nanowires with a growth rate of about 1 micrometre per second, which is 20 to 1,000 times higher than previously reported for traditional, substrate-based growth of nanowires made of group III-V materials. We demonstrate that the method allows sensitive and reproducible control of the nanowire dimensions and shape--and, thus, controlled optical and electronic properties--through the variation of growth temperature, time and Au particle size. Photoluminescence measurements reveal that even as-grown nanowires have good optical properties and excellent spectral uniformity. Detailed transmission electron microscopy investigations show that our aerotaxy-grown nanowires form along one of the four equivalent〈111〉B crystallographic directions in the zincblende unit cell, which is also the preferred growth direction for III-V nanowires seeded by Au particles on a single-crystal substrate. The reported continuous and potentially high-throughput method can be expected substantially to reduce the cost of producing high-quality nanowires and may enable the low-cost fabrication of nanowire-based devices on an industrial scale.
|
|
| 8. |
- Jacobsson, Daniel, et al.
(författare)
-
Interface dynamics and crystal phase switching in GaAs nanowires
- 2016
-
Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 531:7594, s. 317-322
-
Tidskriftsartikel (refereegranskat)abstract
- Controlled formation of non-equilibrium crystal structures is one of the most important challenges in crystal growth. Catalytically grown nanowires are ideal systems for studying the fundamental physics of phase selection, and could lead to new electronic applications based on the engineering of crystal phases. Here we image gallium arsenide (GaAs) nanowires during growth as they switch between phases as a result of varying growth conditions. We find clear differences between the growth dynamics of the phases, including differences in interface morphology, step flow and catalyst geometry. We explain these differences, and the phase selection, using a model that relates the catalyst volume, the contact angle at the trijunction (the point at which solid, liquid and vapour meet) and the nucleation site of each new layer of GaAs. This model allows us to predict the conditions under which each phase should be observed, and use these predictions to design GaAs heterostructures. These results could apply to phase selection in other nanowire systems.
|
|
| 9. |
- Nerini, Francesco Fuso
(författare)
-
Use SDGs to guide climate action
- 2018
-
Ingår i: Nature. - : NATURE PUBLISHING GROUP. - 0028-0836 .- 1476-4687. ; 557:7703, s. 31-31
-
Tidskriftsartikel (refereegranskat)
|
|
| 10. |
- Nielsen, Jens B, 1962
(författare)
-
METABOLISM: A stress-coping strategy for yeast cells
- 2019
-
Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 572:7768, s. 184-185
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Stressed yeast cells take up the amino acid lysine and reprogram their metabolism to free up supplies of a stress-relieving molecule. Lysine uptake therefore increases the tolerance of yeast cells to stress. See LETTER P.249
|
|
