Light can be coupled into propagating electromagnetic surface waves at a metal-dielectric interface known as surface plasmon polaritons (SPPs). This process has traditionally faced challenges in the ...polarization sensitivity of the coupling efficiency and in controlling the directionality of the SPPs. We designed and demonstrated plasmonic couplers that overcome these limits using polarization-sensitive apertures in a gold film. Our devices enable polarization-controlled tunable directional coupling with polarization-invariant total conversion efficiency and preserve the incident polarization information. Both bidirectional and unidirectional launching of SPPs are demonstrated. The design is further applied to circular structures that create radially convergent and divergent SPPs, illustrating that this concept can be extended to a broad range of applications.
Fast radio bursts (FRBs) are millisecond-duration radio transients
of unknown origin. Two possible mechanisms that could generate extremely coherent emission from FRBs invoke neutron star ...magnetospheres
or relativistic shocks far from the central energy source
. Detailed polarization observations may help us to understand the emission mechanism. However, the available FRB polarization data have been perplexing, because they show a host of polarimetric properties, including either a constant polarization angle during each burst for some repeaters
or variable polarization angles in some other apparently one-off events
. Here we report observations of 15 bursts from FRB 180301 and find various polarization angle swings in seven of them. The diversity of the polarization angle features of these bursts is consistent with a magnetospheric origin of the radio emission, and disfavours the radiation models invoking relativistic shocks.
Nearly 500 basidiomycetous yeast species were accepted in the latest edition of The Yeasts: A Taxonomic Study published in 2011. However, this number presents only the tip of the iceberg of yeast ...species diversity in nature. Possibly more than 99 % of yeast species, as is true for many groups of fungi, are yet unknown and await discovery. Over the past two decades nearly 200 unidentified isolates were obtained during a series of environmental surveys of yeasts in phyllosphere and soils, mainly from China. Among these isolates, 107 new species were identified based on the phylogenetic analyses of nuclear ribosomal DNA (rDNA) D1/D2 domains of the large subunit (LSU), the small subunit (SSU), and the internal transcribed spacer region including the 5.8S rDNA (ITS) and protein-coding genes both subunits of DNA polymerase II (RPB1 and RPB2), the translation elongation factor 1-α (TEF1) and the mitochondrial gene cytochrome b (CYTB), and physiological comparisons. Forty-six of these belong to 16 genera in the Tremellomycetes (Agaricomycotina). The other 61 are distributed in 26 genera in the Pucciniomycotina. Here we circumscribe eight new genera, three new families and two new orders based on the multi-locus phylogenetic analyses combined with the clustering optimisation analysis and the predicted similarity thresholds for yeasts and filamentous fungal delimitation at genus and higher ranks. Additionally, as a result of these analyses, three new combinations are proposed and 66 taxa are validated.
Polar metals by geometric design Kim, T H; Puggioni, D; Yuan, Y ...
Nature (London),
2016-May-05, 2016-05-05, 20160505, Letnik:
533, Številka:
7601
Journal Article
Recenzirano
Gauss's law dictates that the net electric field inside a conductor in electrostatic equilibrium is zero by effective charge screening; free carriers within a metal eliminate internal dipoles that ...may arise owing to asymmetric charge distributions. Quantum physics supports this view, demonstrating that delocalized electrons make a static macroscopic polarization, an ill-defined quantity in metals--it is exceedingly unusual to find a polar metal that exhibits long-range ordered dipoles owing to cooperative atomic displacements aligned from dipolar interactions as in insulating phases. Here we describe the quantum mechanical design and experimental realization of room-temperature polar metals in thin-film ANiO3 perovskite nickelates using a strategy based on atomic-scale control of inversion-preserving (centric) displacements. We predict with ab initio calculations that cooperative polar A cation displacements are geometrically stabilized with a non-equilibrium amplitude and tilt pattern of the corner-connected NiO6 octahedral--the structural signatures of perovskites--owing to geometric constraints imposed by the underlying substrate. Heteroepitaxial thin-films grown on LaAlO3 (111) substrates fulfil the design principles. We achieve both a conducting polar monoclinic oxide that is inaccessible in compositionally identical films grown on (001) substrates, and observe a hidden, previously unreported, non-equilibrium structure in thin-film geometries. We expect that the geometric stabilization approach will provide novel avenues for realizing new multifunctional materials with unusual coexisting properties.
Globally, there are more than 500,000 new infections with drug-resistant tuberculosis each year. In this trial involving patients with rifampin-resistant tuberculosis, a shorter, more intense course ...of treatment (9 to 11 months) was found to be noninferior to a standard 20-month regimen.
Cambridge quantum network Dynes, J. F.; Wonfor, A.; Tam, W. W. -S. ...
npj quantum information,
11/2019, Letnik:
5, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Abstract
Future-proofing current fibre networks with quantum key distribution (QKD) is an attractive approach to combat the ever growing breaches of data theft. To succeed, this approach must offer ...broadband transport of quantum keys, efficient quantum key delivery and seamless user interaction, all within the existing fibre network. However, quantum networks to date either require dark fibres and/or offer bit rates inadequate for serving a large number of users. Here we report a city wide high-speed metropolitan QKD network—the Cambridge quantum network—operating on fibres already populated with high-bandwidth data traffic. We implement a robust key delivery layer to demonstrate essential network operation, as well as enabling encryption of 100 Gigabit per second (Gbps) simultaneous data traffic with rapidly refreshed quantum keys. Network resilience against link disruption is supported by high-QKD link rates and network link redundancy. We reveal that such a metropolitan network can support tens of thousands of users with key rates in excess of 1 kilobit per second (kbps) per user. Our result hence demonstrates a clear path for implementing quantum security in metropolitan fibre networks.
The microRNA miR-125b is multi-faceted, with the ability to function as a tumor suppressor or an oncogene, depending on the cellular context. To date, the pro-apoptotic role of miR-125b and its ...underlying mechanisms are unexplored. In this study, both gain- and loss-of-function experiments revealed that miR-125b expression not only induced spontaneous apoptosis in various cell lines derived from the liver, lung and colorectal cancers, but also sensitized cancer cells to diverse apoptotic stimuli, including nutrient starvation and chemotherapeutic treatment. Furthermore, downregulation of miR-125b was a frequent event in hepatocellular carcinoma (HCC) tissues, and the miR-125b level was positively associated with the rate of apoptosis in HCC tissues. Subsequent investigations identified Mcl-1, Bcl-w and interleukin (IL)-6R as direct targets of miR-125b. Restoration of miR-125b expression not only diminished the expression of Mcl-1 and Bcl-w directly but also indirectly reduced the Mcl-1 and Bcl-xL levels by attenuating IL-6/signal transducer and activator of transcription 3 signaling. Consistent with these findings, introduction of miR-125b reduced the mitochondrial membrane potential and promoted the cleavage of pro-caspase-3. These data indicate that miR-125b may promote apoptosis by suppressing the anti-apoptotic molecules of the Bcl-2 family and miR-125b downregulation may facilitate tumor development by conferring upon cells the capability to survive under conditions of nutrient deprivation and chemotherapeutic treatment. Our findings highlight the importance of miR-125b in the regulation of apoptosis and suggest miR-125b as an attractive target for anti-cancer therapy.
Aims
To purify and characterize the biosurfactants produced by Achromobacter sp. HZ01.
Methods and Results
After fermentation, one biosurfactant was successfully purified from the fermentation broth ...of strain HZ01 by centrifugation, extraction using ethyl acetate, silica gel chromatography and reversed phase–high performance liquid chromatography. The critical micelle concentration (CMC) of the biosurfactant and the effects of temperatures, pH and salinities on its stability were determined. Fourier transform infrared spectroscopy, analysis of fatty acids and amino acids and mass spectrometry were used to characterize the biosurfactant. The maximum production yield of the crude biosurfactant reached to 6·84 g l−1 after incubation for 96 h. Except the favourable adaptability to a wide range of temperatures, pH and salinities, the biosurfactant with a CMC value of 48 mg l−1 could efficiently emulsify diverse hydrophobic compounds. The chemical formula of this biosurfactant was confirmed to be CH3‐(CH2)17‐CHO‐CH2‐CO‐Gly‐Gly‐Leu‐Met‐Leu‐Leu, in which the oxygen atom of group CHO linked to the last amino acid (Leu), a structure had never been reported before.
Conclusions
The purified biosurfactant is a novel cyclic lipopeptide.
Significance and Impact of the Study
One novel lipopeptide was purified and characterized. The novel biosurfactant exhibited good potential applications, such as bioremediation.
Global Carbon Budget 2020 Friedlingstein, Pierre; O'Sullivan, Michael; Jones, Matthew W ...
Earth system science data,
12/2020, Letnik:
12, Številka:
4
Journal Article
Recenzirano
Odprti dostop
Accurate assessment of anthropogenic carbon dioxide (CO2) emissions and
their redistribution among the atmosphere, ocean, and terrestrial biosphere
in a changing climate – the “global carbon budget” ...– is important to
better understand the global carbon cycle, support the development of
climate policies, and project future climate change. Here we describe and
synthesize data sets and methodology to quantify the five major components
of the global carbon budget and their uncertainties. Fossil CO2
emissions (EFOS) are based on energy statistics and cement production
data, while emissions from land-use change (ELUC), mainly
deforestation, are based on land use and land-use change data and
bookkeeping models. Atmospheric CO2 concentration is measured directly
and its growth rate (GATM) is computed from the annual changes in
concentration. The ocean CO2 sink (SOCEAN) and terrestrial
CO2 sink (SLAND) are estimated with global process models
constrained by observations. The resulting carbon budget imbalance
(BIM), the difference between the estimated total emissions and the
estimated changes in the atmosphere, ocean, and terrestrial biosphere, is a
measure of imperfect data and understanding of the contemporary carbon
cycle. All uncertainties are reported as ±1σ. For the last
decade available (2010–2019), EFOS was 9.6 ± 0.5 GtC yr−1 excluding the cement carbonation sink (9.4 ± 0.5 GtC yr−1 when the cement carbonation sink is included), and
ELUC was 1.6 ± 0.7 GtC yr−1. For the same decade, GATM was 5.1 ± 0.02 GtC yr−1 (2.4 ± 0.01 ppm yr−1), SOCEAN 2.5 ± 0.6 GtC yr−1, and SLAND 3.4 ± 0.9 GtC yr−1, with a budget
imbalance BIM of −0.1 GtC yr−1 indicating a near balance between
estimated sources and sinks over the last decade. For the year 2019 alone, the
growth in EFOS was only about 0.1 % with fossil emissions increasing
to 9.9 ± 0.5 GtC yr−1 excluding the cement carbonation sink (9.7 ± 0.5 GtC yr−1 when cement carbonation sink is included), and ELUC was 1.8 ± 0.7 GtC yr−1, for total anthropogenic CO2 emissions of 11.5 ± 0.9 GtC yr−1 (42.2 ± 3.3 GtCO2). Also for 2019, GATM was
5.4 ± 0.2 GtC yr−1 (2.5 ± 0.1 ppm yr−1), SOCEAN
was 2.6 ± 0.6 GtC yr−1, and SLAND was 3.1 ± 1.2 GtC yr−1, with a BIM of 0.3 GtC. The global atmospheric CO2
concentration reached 409.85 ± 0.1 ppm averaged over 2019. Preliminary
data for 2020, accounting for the COVID-19-induced changes in emissions,
suggest a decrease in EFOS relative to 2019 of about −7 % (median
estimate) based on individual estimates from four studies of −6 %, −7 %,
−7 % (−3 % to −11 %), and −13 %. Overall, the mean and trend in the
components of the global carbon budget are consistently estimated over the
period 1959–2019, but discrepancies of up to 1 GtC yr−1 persist for the
representation of semi-decadal variability in CO2 fluxes. Comparison of
estimates from diverse approaches and observations shows (1) no consensus
in the mean and trend in land-use change emissions over the last decade, (2)
a persistent low agreement between the different methods on the magnitude of
the land CO2 flux in the northern extra-tropics, and (3) an apparent
discrepancy between the different methods for the ocean sink outside the
tropics, particularly in the Southern Ocean. This living data update
documents changes in the methods and data sets used in this new global
carbon budget and the progress in understanding of the global carbon cycle
compared with previous publications of this data set (Friedlingstein et al.,
2019; Le Quéré et al., 2018b, a, 2016, 2015b, a, 2014,
2013). The data presented in this work are available at https://doi.org/10.18160/gcp-2020 (Friedlingstein et al., 2020).
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