GSTDTAP

浏览/检索结果: 共22条,第1-10条 帮助

已选(0)清除 条数/页:   排序方式:
NASA确定重要概念研究项目推进地球科学研究 快报文章
地球科学快报,2024年第11期
作者:  刘文浩
Microsoft Word(16Kb)  |  收藏  |  浏览/下载:2325/1  |  提交时间:2024/06/10
NASA  concept studies of missions  earth observation  
Learning from generations of sustainability concepts* 期刊论文
ENVIRONMENTAL RESEARCH LETTERS, 2020, 15 (8)
作者:  Downing, Andrea S.;  Chang, Manqi;  Kuiper, Jan J.;  Campenni, Marco;  Haeyhae, Tiina;  Cornell, Sarah E.;  Svedin, Uno;  Mooij, Wolf
收藏  |  浏览/下载:32/0  |  提交时间:2020/08/18
planetary boundaries concept  sustainable development  safe operating space  cassandra'  s dilemma  consumer-resource model  resource-consumer-producer-waste model  
Nearest neighbours reveal fast and slow components of motor learning 期刊论文
NATURE, 2020, 577 (7791) : 526-+
作者:  Kollmorgen, Sepp;  Hahnloser, Richard H. R.;  Mante, Valerio
收藏  |  浏览/下载:16/0  |  提交时间:2020/07/03

A new method for analysing change in high-dimensional data is based on nearest-neighbour statistics and is applied here to song dynamics during vocal learning in zebra finches, but could potentially be applied to other biological and artificial behaviours.


Changes in behaviour resulting from environmental influences, development and learning(1-5) are commonly quantified on the basis of a few hand-picked features(2-4,6,7) (for example, the average pitch of acoustic vocalizations(3)), assuming discrete classes of behaviours (such as distinct vocal syllables)(2,3,8-10). However, such methods generalize poorly across different behaviours and model systems and may miss important components of change. Here we present a more-general account of behavioural change that is based on nearest-neighbour statistics(11-13), and apply it to song development in a songbird, the zebra finch(3). First, we introduce the concept of '  repertoire dating'  , whereby each rendition of a behaviour (for example, each vocalization) is assigned a repertoire time, reflecting when similar renditions were typical in the behavioural repertoire. Repertoire time isolates the components of vocal variability that are congruent with long-term changes due to vocal learning and development, and stratifies the behavioural repertoire into '  regressions'  , '  anticipations'  and '  typical renditions'  . Second, we obtain a holistic, yet low-dimensional, description of vocal change in terms of a stratified '  behavioural trajectory'  , revealing numerous previously unrecognized components of behavioural change on fast and slow timescales, as well as distinct patterns of overnight consolidation(1,2,4,14,15) across the behavioral repertoire. We find that diurnal changes in regressions undergo only weak consolidation, whereas anticipations and typical renditions consolidate fully. Because of its generality, our nonparametric description of how behaviour evolves relative to itself-rather than to a potentially arbitrary, experimenter-defined goal(2,3,14,16)-appears well suited for comparing learning and change across behaviours and species(17,18), as well as biological and artificial systems(5).


  
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.


  
Senolytic CAR T cells reverse senescence-associated pathologies 期刊论文
NATURE, 2020, 583 (7814) : 127-+
作者:  Cortez, Jessica T.;  Montauti, Elena;  Shifrut, Eric;  Gatchalian, Jovylyn;  Zhang, Yusi;  Shaked, Oren;  Xu, Yuanming;  Roth, Theodore L.;  Simeonov, Dimitre R.;  Zhang, Yana;  Chen, Siqi;  Li, Zhongmei;  Woo, Jonathan M.;  Ho, Josephine;  Vogel, Ian A.
收藏  |  浏览/下载:86/0  |  提交时间:2020/07/03

Cellular senescence is characterized by stable cell-cycle arrest and a secretory program that modulates the tissue microenvironment(1,2). Physiologically, senescence serves as a tumour-suppressive mechanism that prevents the expansion of premalignant cells(3,4)and has a beneficial role in wound-healing responses(5,6). Pathologically, the aberrant accumulation of senescent cells generates an inflammatory milieu that leads to chronic tissue damage and contributes to diseases such as liver and lung fibrosis, atherosclerosis, diabetes and osteoarthritis(1,7). Accordingly, eliminating senescent cells from damaged tissues in mice ameliorates the symptoms of these pathologies and even promotes longevity(1,2,8-10). Here we test the therapeutic concept that chimeric antigen receptor (CAR) T cells that target senescent cells can be effective senolytic agents. We identify the urokinase-type plasminogen activator receptor (uPAR)(11)as a cell-surface protein that is broadly induced during senescence and show that uPAR-specific CAR T cells efficiently ablate senescent cells in vitro and in vivo. CAR T cells that target uPAR extend the survival of mice with lung adenocarcinoma that are treated with a senescence-inducing combination of drugs, and restore tissue homeostasis in mice in which liver fibrosis is induced chemically or by diet. These results establish the therapeutic potential of senolytic CAR T cells for senescence-associated diseases.


Chimeric antigen receptor (CAR) T cells targeting uPAR, a cell-surface protein that is upregulated on senescent cells, eliminate senescent cells in vitro and in vivo and reduce liver fibrosis in mice.


  
Preparation of cyclohexene isotopologues and stereoisotopomers from benzene 期刊论文
NATURE, 2020, 581 (7808) : 288-+
作者:  Shimazaki, Yuya;  Schwartz, Ido;  Watanabe, Kenji;  Taniguchi, Takashi;  Kroner, Martin;  Imamoglu, Atac
收藏  |  浏览/下载:33/0  |  提交时间:2020/07/03

The hydrogen isotopes deuterium (D) and tritium (T) have become essential tools in chemistry, biology and medicine(1). Beyond their widespread use in spectroscopy, mass spectrometry and mechanistic and pharmacokinetic studies, there has been considerable interest in incorporating deuterium into drug molecules(1). Deutetrabenazine, a deuterated drug that is promising for the treatment of Huntington'  s disease(2), was recently approved by the United States'  Food and Drug Administration. The deuterium kinetic isotope effect, which compares the rate of a chemical reaction for a compound with that for its deuterated counterpart, can be substantial(1,3,4). The strategic replacement of hydrogen with deuterium can affect both the rate of metabolism and the distribution of metabolites for a compound(5), improving the efficacy and safety of a drug. The pharmacokinetics of a deuterated compound depends on the location(s) of deuterium. Although methods are available for deuterium incorporation at both early and late stages of the synthesis of a drug(6,7), these processes are often unselective and the stereoisotopic purity can be difficult to measure(7,8). Here we describe the preparation of stereoselectively deuterated building blocks for pharmaceutical research. As a proof of concept, we demonstrate a four-step conversion of benzene to cyclohexene with varying degrees of deuterium incorporation, via binding to a tungsten complex. Using different combinations of deuterated and proteated acid and hydride reagents, the deuterated positions on the cyclohexene ring can be controlled precisely. In total, 52 unique stereoisotopomers of cyclohexene are available, in the form of ten different isotopologues. This concept can be extended to prepare discrete stereoisotopomers of functionalized cyclohexenes. Such systematic methods for the preparation of pharmacologically active compounds as discrete stereoisotopomers could improve the pharmacological and toxicological properties of drugs and provide mechanistic information related to their distribution and metabolism in the body.


Cyclohexene isotopologues and stereoisotopomers with varying degrees of deuteration are formed by binding a tungsten complex to benzene, which facilitates the selective incorporation of deuterium into any position on the ring.


  
Short-range order and its impact on the CrCoNi medium-entropy alloy 期刊论文
NATURE, 2020, 581 (7808) : 283-+
作者:  Tan, Hwei-Ee;  Sisti, Alexander C.;  Jin, Hao;  Vignovich, Martin;  Villavicencio, Miguel;  Tsang, Katherine S.;  Goffer, Yossef;  Zuker, Charles S.
收藏  |  浏览/下载:16/0  |  提交时间:2020/07/03

Traditional metallic alloys are mixtures of elements in which the atoms of minority species tend to be distributed randomly if they are below their solubility limit, or to form secondary phases if they are above it. The concept of multiple-principal-element alloys has recently expanded this view, as these materials are single-phase solid solutions of generally equiatomic mixtures of metallic elements. This group of materials has received much interest owing to their enhanced mechanical properties(1-5). They are usually called medium-entropy alloys in ternary systems and high-entropy alloys in quaternary or quinary systems, alluding to their high degree of configurational entropy. However, the question has remained as to how random these solid solutions actually are, with the influence of short-range order being suggested in computational simulations but not seen experimentally(6,7). Here we report the observation, using energy-filtered transmission electron microscopy, of structural features attributable to short-range order in the CrCoNi medium-entropy alloy. Increasing amounts of such order give rise to both higher stacking-fault energy and hardness. These findings suggest that the degree of local ordering at the nanometre scale can be tailored through thermomechanical processing, providing a new avenue for tuning the mechanical properties of medium- and high-entropy alloys.


Metal alloys consisting of three or more major elemental components show enhanced mechanical properties, which are now shown to be correlated with short-range order observed with electron microscopy.


  
An engineered PET depolymerase to break down and recycle plastic bottles 期刊论文
NATURE, 2020, 580 (7802) : 216-+
作者:  Zhao, Evan Wenbo;  Liu, Tao;  Jonsson, Erlendur;  Lee, Jeongjae;  Temprano, Israel;  Jethwa, Rajesh B.;  Wang, Anqi;  Smith, Holly;  Carretero-Gonzalez, Javier;  Song, Qilei;  Grey, Clare P.
收藏  |  浏览/下载:101/0  |  提交时间:2020/07/03

Present estimates suggest that of the 359 million tons of plastics produced annually worldwide(1), 150-200 million tons accumulate in landfill or in the natural environment(2). Poly(ethylene terephthalate) (PET) is the most abundant polyester plastic, with almost 70 million tons manufactured annually worldwide for use in textiles and packaging(3). The main recycling process for PET, via thermomechanical means, results in a loss of mechanical properties(4). Consequently, de novo synthesis is preferred and PET waste continues to accumulate. With a high ratio of aromatic terephthalate units-which reduce chain mobility-PET is a polyester that is extremely difficult to hydrolyse(5). Several PET hydrolase enzymes have been reported, but show limited productivity(6,7). Here we describe an improved PET hydrolase that ultimately achieves, over 10 hours, a minimum of 90 per cent PET depolymerization into monomers, with a productivity of 16.7 grams of terephthalate per litre per hour (200 grams per kilogram of PET suspension, with an enzyme concentration of 3 milligrams per gram of PET). This highly efficient, optimized enzyme outperforms all PET hydrolases reported so far, including an enzyme(8,9) from the bacterium Ideonella sakaiensis strain 201-F6 (even assisted by a secondary enzyme(10)) and related improved variants(11-14) that have attracted recent interest. We also show that biologically recycled PET exhibiting the same properties as petrochemical PET can be produced from enzymatically depolymerized PET waste, before being processed into bottles, thereby contributing towards the concept of a circular PET economy.


Computer-aided engineering produces improvements to an enzyme that breaks down poly(ethylene terephthalate) (PET) into its constituent monomers, which are used to synthesize PET of near-petrochemical grade that can be further processed into bottles.


  
General synthesis of two-dimensional van der Waals heterostructure arrays 期刊论文
NATURE, 2020: 368-+
作者:  Bloch, Joel S.;  Pesciullesi, Giorgio;  Boilevin, Jeremy;  Nosol, Kamil;  Irobalieva, Rossitza N.;  Darbre, Tamis;  Aebi, Markus;  Kossiakoff, Anthony A.;  Reymond, Jean-Louis;  Locher, Kaspar P.
收藏  |  浏览/下载:81/0  |  提交时间:2020/07/03

Two-dimensional van der Waals heterostructures (vdWHs) have attracted considerable interest(1-4). However, most vdWHs reported so far are created by an arduous micromechanical exfoliation and manual restacking process(5), which-although versatile for proof-of-concept demonstrations(6-16) and fundamental studies(17-30)-is clearly not scalable for practical technologies. Here we report a general synthetic strategy for two-dimensional vdWH arrays between metallic transition-metal dichalcogenides (m-TMDs) and semiconducting TMDs (s-TMDs). By selectively patterning nucleation sites on monolayer or bilayer s-TMDs, we precisely control the nucleation and growth of diverse m-TMDs with designable periodic arrangements and tunable lateral dimensions at the predesignated spatial locations, producing a series of vdWH arrays, including VSe2/WSe2, NiTe2/WSe2, CoTe2/WSe2, NbTe2/WSe2, VS2/WSe2, VSe2/MoS2 and VSe2/WS2. Systematic scanning transmission electron microscopy studies reveal nearly ideal vdW interfaces with widely tunable moire superlattices. With the atomically clean vdW interface, we further show that the m-TMDs function as highly reliable synthetic vdW contacts for the underlying WSe2 with excellent device performance and yield, delivering a high ON-current density of up to 900 microamperes per micrometre in bilayer WSe2 transistors. This general synthesis of diverse two-dimensional vdWH arrays provides a versatile material platform for exploring exotic physics and promises a scalable pathway to high-performance devices.


A general strategy for the synthesis of two-dimensional van der Waals heterostructure arrays is used to produce high-performance electronic devices, showing the potential of this scalable approach for practical technologies.


  
Metabolites released from apoptotic cells act as tissue messengers 期刊论文
NATURE, 2020
作者:  Chica, Daniel G.;  He, Yihui;  McCall, Kyle M.;  Chung, Duck Young;  Pak, Rahmi O.;  Trimarchi, Giancarlo;  Liu, Zhifu;  De Lurgio, Patrick M.;  Wessels, Bruce W.;  Kanatzidis, Mercouri G.
收藏  |  浏览/下载:32/0  |  提交时间:2020/07/03

Caspase-dependent apoptosis accounts for approximately 90% of homeostatic cell turnover in the body(1), and regulates inflammation, cell proliferation, and tissue regeneration(2-4). How apoptotic cells mediate such diverse effects is not fully understood. Here we profiled the apoptotic metabolite secretome and determined its effects on the tissue neighbourhood. We show that apoptotic lymphocytes and macrophages release specific metabolites, while retaining their membrane integrity. A subset of these metabolites is also shared across different primary cells and cell lines after the induction of apoptosis by different stimuli. Mechanistically, the apoptotic metabolite secretome is not simply due to passive emptying of cellular contents and instead is a regulated process. Caspase-mediated opening of pannexin 1 channels at the plasma membrane facilitated the release of a select subset of metabolites. In addition, certain metabolic pathways continued to remain active during apoptosis, with the release of only select metabolites from a given pathway. Functionally, the apoptotic metabolite secretome induced specific gene programs in healthy neighbouring cells, including suppression of inflammation, cell proliferation, and wound healing. Furthermore, a cocktail of apoptotic metabolites reduced disease severity in mouse models of inflammatory arthritis and lung-graft rejection. These data advance the concept that apoptotic cells are not inert cells waiting for removal, but instead release metabolites as '  good-bye'  signals to actively modulate outcomes in tissues.


Apoptotic cells communicate with neighbouring cells by the regulated release of specific metabolites, and a cocktail of select apoptotic metabolites reduces disease severity in mouse models of inflammatory arthritis and lung transplant rejection.