Abstract
Flooded plants experience impaired gas diffusion underwater, leading to oxygen deprivation (hypoxia). The volatile plant hormone ethylene is rapidly trapped in submerged plant cells and is ...instrumental for enhanced hypoxia acclimation. However, the precise mechanisms underpinning ethylene-enhanced hypoxia survival remain unclear. We studied the effect of ethylene pretreatment on hypoxia survival of Arabidopsis (Arabidopsis thaliana) primary root tips. Both hypoxia itself and re-oxygenation following hypoxia are highly damaging to root tip cells, and ethylene pretreatments reduced this damage. Ethylene pretreatment alone altered the abundance of transcripts and proteins involved in hypoxia responses, root growth, translation, and reactive oxygen species (ROS) homeostasis. Through imaging and manipulating ROS abundance in planta, we demonstrated that ethylene limited excessive ROS formation during hypoxia and subsequent re-oxygenation and improved oxidative stress survival in a PHYTOGLOBIN1-dependent manner. In addition, we showed that root growth cessation via ethylene and auxin occurred rapidly and that this quiescence behavior contributed to enhanced hypoxia tolerance. Collectively, our results show that the early flooding signal ethylene modulates a variety of processes that all contribute to hypoxia survival.
The early flooding signal ethylene contributes to forthcoming hypoxia stress by modulating a plethora of processes including reactive oxygen species amelioration and growth cessation.
A new measurement of the reactor antineutrino flux and energy spectrum by the Daya Bay reactor neutrino experiment is reported. The antineutrinos were generated by six 2.9 GWth nuclear reactors and ...detected by eight antineutrino detectors deployed in two near（560 m and 600 m flux-weighted baselines） and one far（1640 m flux-weighted baseline） underground experimental halls. With 621 days of data, more than 1.2 million inverse beta decay（IBD） candidates were detected. The IBD yield in the eight detectors was measured, and the ratio of measured to predicted flux was found to be 0.946±0.020（0.992±0.021） for the Huber＋Mueller（ILL＋Vogel） model. A 2.9σ deviation was found in the measured IBD positron energy spectrum compared to the predictions. In particular, an excess of events in the region of 4–6 MeV was found in the measured spectrum, with a local significance of 4.4σ. A reactor antineutrino spectrum weighted by the IBD cross section is extracted for model-independent predictions.
Context.
The evolution of galaxies depends on their interaction with the surrounding environment. Ultra-diffuse galaxies (UDGs) have been found in large numbers in clusters. We detected a few ...star-forming blobs in the VESTIGE survey, located at ∼5 kpc from a UDG, namely NGVS 3543, in association with an HI gas cloud AGC 226178, suggesting a recent interaction between this low-surface-brightness system and the surrounding cluster environment.
Aims.
We use a complete set of multi-frequency data including deep optical, UV, and narrow-band H
α
imaging and HI data to understand the formation process that gave birth to this peculiar system.
Methods.
For this purpose, we measured (i) the multi-wavelength radial surface brightness profiles of NGVS 3543 and compared them to the predictions of spectro-photometric models of galaxy evolution in rich clusters; and (ii) the aperture photometry of the blue regions in the vicinity of NGVS 3543 in order to determine their age and stellar mass.
Results.
Comparisons of the observations with evolutionary models indicate that NGVS 3543 has undergone a ram-pressure stripping that peaked ∼100 Myr ago, transforming a blue gas-rich UDG into a red gas-poor UDG. Star formation has taken place in the ram pressure stripped gas, the mass of which is ∼10
8
M
⊙
, forming star complexes with a typical age of ∼20 Myr and a stellar mass of ∼10
4
M
⊙
.
Conclusions.
These results suggest that we are observing for the first time the ongoing transformation of a gas-rich UDG into a red and quiescent UDG under the effect of a ram-pressure stripping event. The same process could explain the lack of star-forming UDGs in rich environments observed in several nearby clusters.
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A joint determination of the reactor antineutrino spectra resulting from the fission of 235U and 239Pu has been carried out by the Daya Bay and PROSPECT collaborations. This Letter reports the level ...of consistency of 235U spectrum measurements from the two experiments and presents new results from a joint analysis of both data sets. The measurements are found to be consistent. The combined analysis reduces the degeneracy between the dominant 235U and 239Pu isotopes and improves the uncertainty of the 235U spectral shape to about 3%. The 235U and 239Pu antineutrino energy spectra are unfolded from the jointly deconvolved reactor spectra using the Wiener-SVD unfolding method, providing a data-based reference for other reactor antineutrino experiments and other applications. This is the first measurement of the 235U and 239Pu spectra based on the combination of experiments at low- and highly enriched uranium reactors.
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CMK, CTK, FMFMET, IJS, NUK, PNG, UL, UM
Aluminum suppression of the α′ precipitate has been observed in eight model Fe–Cr–Al alloys with nominal compositions ranging from 11 to 20 wt% Cr and 4.5 to 6 wt% Al during long-term aging at 475 °C ...for up to 10,000 h. Fe–15Cr-4.5Al alloy reached the equilibrium state after aging for 10,000 h, in which the α′ phase evolution involved an integrated process of nucleation, growth, and coarsening. Meanwhile, no α-α′ phase separation occurred in the Fe–15Cr–6Al alloy during long-term aging at 475 °C. The α′ phase precipitated in the Fe–17Cr–6Al and Fe–20Cr–6Al alloys during the intermediate stage of aging, due to the inevitable composition fluctuation, and was eventually dissolved in the matrix in the later stages of aging. As such, a further increase in Al concentration (6 wt%) can strongly suppress the α′ precipitate in the equilibrium state. The equilibrium phase diagram of the Fe–Cr–Al system at 475 °C, which is based on the present work and previous literature, is expected to provide a more accurate reference for optimizing Fe–Cr–Al alloys for fuel cladding.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
► An oxidation torrefaction kinetics model was developed based on TGA data. ► Sawdust was torrefied in a fluidized bed reactor using oxygen-laden combustion flue gases. ► Torrefied sawdust was ...compressed into pellets of properties similar to regular pellets.
Oxidative torrefaction of sawdust with a carrier gas containing 3–6% O2 was investigated in a TG and a fluidized bed reactor, with the properties of the torrefied sawdust and pellets compared with traditional torrefaction without any O2, as well as the dry raw material. It is found that the oxidative torrefaction process produced torrefied sawdust and pellets of similar properties as normally torrefied sawdust and corresponding pellets, especially on the density, energy consumption for pelletization, higher heating value and energy yield. For moisture absorption and hardness of the torrefied pellets, the oxidative torrefaction process showed slightly poor but negligible performance. Therefore, it is feasible to use oxygen laden combustion flue gases as the carrier gas for torrefaction of biomass. Besides, torrefied sawdust can be made into dense and strong pellets of high hydrophobicity at a higher die temperature than normally used in the production of traditional control pellets.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Abstract
The prediction of reactor antineutrino spectra will play a crucial role as reactor experiments enter the precision era. The positron energy spectrum of 3.5 million antineutrino inverse beta ...decay reactions observed by the Daya Bay experiment, in combination with the fission rates of fissile isotopes in the reactor, is used to extract the positron energy spectra resulting from the fission of specific isotopes. This information can be used to produce a precise, data-based prediction of the antineutrino energy spectrum in other reactor antineutrino experiments with different fission fractions than Daya Bay. The positron energy spectra are unfolded to obtain the antineutrino energy spectra by removing the contribution from detector response with the Wiener-SVD unfolding method. Consistent results are obtained with other unfolding methods. A technique to construct a data-based prediction of the reactor antineutrino energy spectrum is proposed and investigated. Given the reactor fission fractions, the technique can predict the energy spectrum to a 2% precision. In addition, we illustrate how to perform a rigorous comparison between the unfolded antineutrino spectrum and a theoretical model prediction that avoids the input model bias of the unfolding method.
We present measurements of the galaxy luminosity and stellar mass function in a 3.71 deg super(2)(0.3 Mpc super(2)) area in the core of the Virgo Cluster, based on u* griz data from the Next ...Generation Virgo Cluster Survey (NGVS). The galaxy sample which consists of 352 objects brighter than Mg= ?9.13 mag, the 50% completeness limit of the survey reaches 2.2 mag deeper than the widely used Virgo Cluster Catalog and at least 1.2 mag deeper than any sample previously used to measure the luminosity function in Virgo. Using a Bayesian analysis, we find a best-fit faint-end slope of alpha= ?1.33 + or - 0.02 for the g-band luminosity function; consistent results are found for the stellar mass function and the luminosity function in the other four NGVS bandpasses. We discuss the implications for the faint-end slope of adding 92 ultracompact dwarfs (UCDs) previously compiled by the NGVS in this region to the galaxy sample, assuming that UCDs are the stripped remnants of nucleated dwarf galaxies. Under this assumption, the slope of the luminosity function (down to the UCD faint magnitude limit, Mg= ?9.6 mag) increases dramatically, up to alpha= ?1.60 + or - 0.06 when correcting for the expected number of disrupted non-nucleated galaxies. We also calculate the total number of UCDs and globular clusters that may have been deposited in the core of Virgo owing to the disruption of satellites, both nucleated and non-nucleated. We estimate that ~150 objects with Mg<,~ ?9.6 mag and that are currently classified as globular clusters might, in fact, be the nuclei of disrupted galaxies. We further estimate that as many as 40% of the (mostly blue) globular clusters in the Virgo core might once have belonged to such satellites; these same disrupted satellites might have contributed ~40% of the total luminosity in galaxies observed in the core region today. Finally, we use an updated Local Group galaxy catalog to provide a new measurement of the luminosity function of Local Group satellites, alpha= ?1.21 + or - 0.05, which is only 1.7sigma shallower than measured in the core of the Virgo Cluster.
Fossilized embryos from the late Neoproterozoic and earliest Phanerozoic have caused much excitement because they preserve the earliest stages of embryology of animals that represent the initial ...diversification of metazoans. However, the potential of this material has not been fully realized because of reliance on traditional, non-destructive methods that allow analysis of exposed surfaces only, and destructive methods that preserve only a single two-dimensional view of the interior of the specimen. Here, we have applied synchrotron-radiation X-ray tomographic microscopy (SRXTM), obtaining complete three-dimensional recordings at submicrometre resolution. The embryos are preserved by early diagenetic impregnation and encrustation with calcium phosphate, and differences in X-ray attenuation provide information about the distribution of these two diagenetic phases. Three-dimensional visualization of blastomere arrangement and diagenetic cement in cleavage embryos resolves outstanding questions about their nature, including the identity of the columnar blastomeres. The anterior and posterior anatomy of embryos of the bilaterian worm-like Markuelia confirms its position as a scalidophoran, providing new insights into body-plan assembly among constituent phyla. The structure of the developing germ band in another bilaterian, Pseudooides, indicates a unique mode of germ-band development. SRXTM provides a method of non-invasive analysis that rivals the resolution achieved even by destructive methods, probing the very limits of fossilization and providing insight into embryology during the emergence of metazoan phyla.
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DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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