GSTDTAP

浏览/检索结果: 共6条,第1-6条 帮助

已选(0)清除 条数/页:   排序方式:
Field-resolved infrared spectroscopy of biological systems 期刊论文
NATURE, 2020, 577 (7788) : 52-+
作者:  Pupeza, Ioachim;  Huber, Marinus;  Trubetskov, Michael;  Schweinberger, Wolfgang;  Hussain, Syed A.;  Hofer, Christina;  Fritsch, Kilian;  Poetzlberger, Markus;  Vamos, Lenard;  Fill, Ernst;  Amotchkina, Tatiana;  Kepesidis, Kosmas V.;  Apolonski, Alexander;  Karpowicz, Nicholas;  Pervak, Vladimir;  Pronin, Oleg;  Fleischmann, Frank;  Azzeer, Abdallah;  Zigman, Mihaela;  Krausz, Ferenc
收藏  |  浏览/下载:30/0  |  提交时间:2020/07/03

The proper functioning of living systems and physiological phenotypes depends on molecular composition. Yet simultaneous quantitative detection of a wide variety of molecules remains a challenge(1-8). Here we show how broadband optical coherence opens up opportunities for fingerprinting complex molecular ensembles in their natural environment. Vibrationally excited molecules emit a coherent electric field following few-cycle infrared laser excitation(9-12), and this field is specific to the sample'  s molecular composition. Employing electro-optic sampling(10,12-15), we directly measure this global molecular fingerprint down to field strengths 10(7) times weaker than that of the excitation. This enables transillumination of intact living systems with thicknesses of the order of 0.1 millimetres, permitting broadband infrared spectroscopic probing of human cells and plant leaves. In a proof-of-concept analysis of human blood serum, temporal isolation of the infrared electric-field fingerprint from its excitation along with its sampling with attosecond timing precision results in detection sensitivity of submicrograms per millilitre of blood serum and a detectable dynamic range of molecular concentration exceeding 10(5). This technique promises improved molecular sensitivity and molecular coverage for probing complex, real-world biological and medical settings.


  
Layered nanocomposites by shear-flow-induced alignment of nanosheets 期刊论文
NATURE, 2020, 580 (7802) : 210-+
作者:  Rollie, Clare;  Chevallereau, Anne;  Watson, Bridget N. J.;  Chyou, Te-yuan;  Fradet, Olivier;  McLeod, Isobel;  Fineran, Peter C.;  Brown, Chris M.;  Gandon, Sylvain;  Westra, Edze R.
收藏  |  浏览/下载:58/0  |  提交时间:2020/07/03

Layered nanocomposites fabricated using a continuous and scalable process achieve properties exceeding those of natural nacre, the result of stiffened matrix polymer chains confined between highly aligned nanosheets.


Biological materials, such as bones, teeth and mollusc shells, are well known for their excellent strength, modulus and toughness(1-3). Such properties are attributed to the elaborate layered microstructure of inorganic reinforcing nanofillers, especially two-dimensional nanosheets or nanoplatelets, within a ductile organic matrix(4-6). Inspired by these biological structures, several assembly strategies-including layer-by-layer(4,7,8), casting(9,10), vacuum filtration(11-13) and use of magnetic fields(14,15)-have been used to develop layered nanocomposites. However, how to produce ultrastrong layered nanocomposites in a universal, viable and scalable manner remains an open issue. Here we present a strategy to produce nanocomposites with highly ordered layered structures using shear-flow-induced alignment of two-dimensional nanosheets at an immiscible hydrogel/oil interface. For example, nanocomposites based on nanosheets of graphene oxide and clay exhibit a tensile strength of up to 1,215 +/- 80 megapascals and a Young'  s modulus of 198.8 +/- 6.5 gigapascals, which are 9.0 and 2.8 times higher, respectively, than those of natural nacre (mother of pearl). When nanosheets of clay are used, the toughness of the resulting nanocomposite can reach 36.7 +/- 3.0 megajoules per cubic metre, which is 20.4 times higher than that of natural nacre  meanwhile, the tensile strength is 1,195 +/- 60 megapascals. Quantitative analysis indicates that the well aligned nanosheets form a critical interphase, and this results in the observed mechanical properties. We consider that our strategy, which could be readily extended to align a variety of two-dimensional nanofillers, could be applied to a wide range of structural composites and lead to the development of high-performance composites.


  
Range margin populations show high climate adaptation lags in European trees 期刊论文
GLOBAL CHANGE BIOLOGY, 2019
作者:  Frejaville, Thibaut;  Vizcaino-Palomar, Natalia;  Fady, Bruno;  Kremer, Antoine;  Garzon, Marta Benito
收藏  |  浏览/下载:17/0  |  提交时间:2020/02/17
climate margin  ecological optima  growth  intraspecific trait variation  local adaptation  natural species'  distribution range  plasticity  tree height  
Status and trends of fire activity in southern California yellow pine and mixed conifer forests 期刊论文
FOREST ECOLOGY AND MANAGEMENT, 2019, 441: 20-31
作者:  Nigro, Katherine;  Molinari, Nicole
收藏  |  浏览/下载:15/0  |  提交时间:2019/11/26
Southern California  Fire return interval  Burn severity  Fire size  Natural range of variation  Yellow pine  Mixed conifer  
A common garden experiment examining light use efficiency and heat sum to explain growth differences in native and exotic Pinus taeda 期刊论文
FOREST ECOLOGY AND MANAGEMENT, 2018, 425: 35-44
作者:  Albaugh, Timothy J.;  Fox, Thomas R.;  Maier, Chris A.;  Campoe, Otavio C.;  Rubilar, Rafael A.;  Cook, Rachel L.;  Raymond, Jay E.;  Alvares, Clayton A.;  Stape, Jose L.
收藏  |  浏览/下载:14/0  |  提交时间:2019/04/09
Absorbed light  Density  Genotype  Natural range  Vapor pressure deficit  
Spatial and temporal dimensions of fire activity in the fire-prone eastern Canadian taiga 期刊论文
GLOBAL CHANGE BIOLOGY, 2017, 23 (3)
作者:  Erni, Sandy;  Arseneault, Dominique;  Parisien, Marc-Andre;  Begin, Yves
收藏  |  浏览/下载:15/0  |  提交时间:2019/04/09
extreme weather  fire overlaps  fire size  fire-free intervals  fuel feedback  natural range of variability  predictability of boreal forest-age mosaics  top-down vs. bottom-up drivers of fire activity