There is an exciting possibility to decentralize ammonia synthesis for fertilizer production or energy storage without carbon emission from H2 obtained from renewables at small units operated at ...lower pressure. However, no suitable catalyst has yet been developed. Ru catalysts are known to be promoted by heavier alkali dopants. Instead of using heavy alkali metals, Li is herein shown to give the highest rate through surface polarisation despite its poorest electron donating ability. This exceptional promotion rate makes Ru–Li catalysts suitable for ammonia synthesis, which outclasses industrial Fe counterparts by at least 195 fold. Akin to enzyme catalysis, it is for the first time shown that Ru–Li catalysts hydrogenate end‐on adsorbed N2 stabilized by Li+ on Ru terrace sites to ammonia in a stepwise manner, in contrast to typical N2 dissociation on stepped sites adopted by Ru–Cs counterparts, giving new insights in activating N2 by metallic catalysts.
Lithium treatment: Introduction of Li+ on Ru‐based catalysts can polarize and stabilize adsorbed dinitrogen on the metal surface, which facilitates the non‐dissociative pathway to produce ammonia under mild conditions. The Li–Ru catalysts are suitable for new green ammonia synthesis at lower pressure, and many times better than the commercial Fe counterparts.
Abstract
A digital-coding programmable metasurface (DCPM) is a type of functional system that is composed of subwavelength-scale digital coding elements with opposite phase responses. By configuring ...the digital coding elements, a DCPM can construct dynamic near-field image patterns in which the intensity of each pixel of the image can be dynamically and independently modulated. Thus, a DCPM can perform both spatial and temporal modulations. Here, this advantage is used to realize multichannel direct transmissions of near-field information. Three points are selected in the near-field region to form three independent channels. By applying various digital phase codes on the DCPM, independent binary digital symbols defined by amplitude codes (namely, weak and strong amplitudes) are transmitted through the three channels. The measured near-field distributions and temporal transmissions of the system agree with numerical calculations. Compared with the conventional multichannel transmission, the proposed mechanism achieves simultaneous spatial and temporal modulations by treating DCPM as an energy radiator and information modulator, thereby enduing DCPM with high potential in near-field information processing and communications.
Long non-coding RNAs (LncRNAs) have recently emerged as vital regulators in the development and progression of hepatocellular carcinoma (HCC), providing new opportunities as novel therapeutic ...targets. Here we identified the lncRNA NIFK-AS1 as being highly expressed in HCC tissues and cells and showed this up-regulation resulted from METTL3-dependent m
6
A methylation. Functionally, knockdown of NIFK-AS1 inhibited the proliferation, colony formation, migration, and invasion of HCC cells. Moreover, these effects were elicited though AKT1 and we uncovered a ceRNA network involving an NIFK-AS1/miR-637/AKT1 axis with downstream effects on HCC progression involving regulation of MMP-7 and MMP-9 expression. From the clinical perspective, we showed that knockdown of NIFK-AS1 sensitized HCC cells to sorafenib through the up-regulation of the drug transporters OATP1B1 and OATP1B3. Clinical investigations showed HCC patients with low NIFK-AS1 expression benefited from sorafenib therapy and this phenomenon was reproduced in patient-derived tumor xenograft models (PDX) comparing HCC with low and high expression of NIFK-AS1. Taken together, these results suggest an essential role for NIFK-AS1 in HCC progression and promote NIFK-AS1 as a new therapeutic target and predictor of sorafenib benefit in HCC patients.
Abstract
Lithium is a fragile but crucial chemical element in the Universe, and exhibits interesting and complex behaviors. Thanks to the mass of spectroscopic data from the Large Sky Area ...Multi-Object Fiber Spectroscopic Telescope (LAMOST) medium-resolution survey (MRS), we can investigate the lithium abundances in a large and diverse sample of stars, which could bring vital help in studying the origin and evolution of lithium. In this work, we use the Li
i
6707.8 Å line to derive the lithium abundance through a template-matching method. A catalog of precise lithium abundance is presented for 795,384 spectra corresponding to 455,752 stars from the LAMOST MRS Data Release 9. Comparing our results with those of external high-resolution references, we find good consistency with a typical deviation of
σ
A
(Li) ∼ 0.2 dex. We also analyze the internal errors using stars that have multiple LAMOST MRS observations, which will reach as low as 0.1 dex when the signal-to-noise ratio of the spectra is >20. Besides, our result indicates that a small fraction of giant stars still exhibit a surprisingly high lithium content, and 967 stars are identified as Li-rich giants with
A
(Li) > 1.5 dex, accounting for ∼2.6% of our samples. If one takes into account the fact that nearly all stars deplete lithium during the main sequence, then the fraction of Li-rich stars may far exceed 2.6%. This new catalog covers a wide range of stellar evolutionary stages from pre-main sequence to giants, and will provide help to the further study of the chemical evolution of lithium.
Widespread tree species cover large geographical areas and play important roles in various vegetation types. Understanding how these species responded to historical climatic changes is important for ...understanding community assembly mechanisms with evolutionary and conservation implications. However, the location of refugial areas and postglacial history of widespread trees in East Asia remain poorly known. We combined microsatellite data (63 populations, 1756 individuals) and ecological niche modeling to examine the range‐wide population diversity, genetic structure, and historical demography of a pioneer tree species, Asian white birch (Betula platyphylla Suk.) across East Asia. We found a north‐to‐south trend of declining genetic diversity and five clusters, corresponding to geographical regions. Different clusters were inferred to have diverged through Pleistocene climatic oscillations and have different expansion routes, leading to genetic admixture in some populations. Ecological niche models indicated that the distribution of B. platyphylla during the last glacial maximum still had a large latitude span with slight shifts toward southeast, and northern populations had more variable distribution ranges than those in the south during later climatic oscillations. Our results reflect the relatively stable distribution through the last glacial–interglacial cycles and recent multidirectional expansion of B. platyphylla, providing new hypotheses for the response pattern of widespread tree species to climate change. The gradual genetic pattern from northeast to southwest and alternative distribution dynamics possibly resulted from environmental differences caused by latitude and topographic heterogeneity.
We recovered for the first time a detailed demographic history of Betula platyphylla across the range of the species. Multiple refugia with different distribution dynamics were detected in both northern and southern parts of the range. In contrast to previous studies, we found multidirectional recolonization routes and an increase in genetic diversity with latitude.
Abstract
One of the purposes of taking spectra for millions of stars through the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) medium-resolution survey (MRS) is to obtain the ...elemental abundances, so that one can trace the origin and evolution for the element of interests. Lithium is one of such elements of great importance, which exhibits many puzzling behaviors. Investigating the lithium abundances to a uniquely large sample of stars is essential to understand its origin and evolution. In this paper, we present the lithium abundances obtained from the LAMOST MRS spectra calculated by the template-matching method. Our data set consists of 294,857 spectra that corresponds to 165,479 stars with a resolution power of Δ
λ
/
λ
∼ 7500. We compared the lithium abundances derived from our work with those using the high-resolution spectra and found a good consistence. The errors of lithium abundances are discussed. Our results suggest that the distribution of lithium abundances show two clear peaks at +2.6 and +1.0 dex, respectively. This sample is potentially important for investigating physical mechanisms occurring inside stars that alter the surface lithium abundance.
Increasing evidence shows that dysregulation of microRNAs (miRNAs) is involved in malignant transformation. We investigated the clinical significance of miR-650 and its involvement in chemoresistance ...to docetaxel. Our results showed that the relative expression level of miR-650 was significantly higher in LAD tissues than in corresponding nontumor tissues and high level of miR-650 expression was found to be significantly associated with high incidence of lymph node metastasis, advanced clinical stage and poor prognosis of LAD patients. Univariate and multivariate analyses indicated that high miR-650 expression was an independent prognostic factor for survival. Also, we found that the level of miR-650 in LAD tissues was correlated with the response of patients to docetaxel-based chemotherapy. Silencing of miR-650 could increase the in vitro sensitivity of docetaxel-resistant LAD cells to docetaxel, while upregulation of miR-650 decreased the sensitivity of parental LAD cells to docetaxel both in vitro and in vivo. Additionally, silencing of miR-650 could enhance the caspase-3-dependent apoptosis, which might be correlated with the decreased ratio of Bcl-2/Bax. Further researches suggested that inhibitor of growth 4 (ING4) was a direct target of miR-650. Downregulated or upregulated ING4 expression could partially rescue the effects of miR-650 inhibitor or mimics in docetaxel-resistant or parental LAD cells. Furthermore, we found that ING4 was upregulated in docetaxel-responding LAD tissues, and its expression was inversely correlated with miR-650. Thus, miR-650 is a novel prognostic marker in LAD and its expression is a potential indicator of chemosensitivity to docetaxel-based chemotherapy regimen.
The development of connected and automated vehicle (CAV) techniques brings an upcoming revolution to traffic management. The control of CAVs in potential conflict areas such as on-ramps and ...intersections will be complex to traffic management when considering their deployment. There is still a lack of a general framework for dispatching CAVs in these bottlenecks, which is expected to ensure safety, traffic efficiency, and energy consumption in real time. This study aimed to fill the technique gap, and a comprehensive cooperative intelligent driving framework is put forward to study the problem, which can be used in both on-ramp and intersection scenarios. Based on a multi-objective evolutionary algorithm, CAVs are denoted as a sequence to be searched in solution space, while a multitask learning neural network with adaptive loss function is implemented for optimization target feedback to surrogate the simulation test procedure. The simulation results show that the proposed framework can get satisfying performance with low time and energy consumption. It can reduce time consumption by up to 16.51% for the on-ramp scenario and 9.8% for the intersection scenario, while reducing energy consumption by up to 16.39% and 11.39% for the two scenarios. Meanwhile, an analysis of computation time is carried out, illuminating the flexibility and controllability of the new strategy.
Abstract
The Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) Low Resolution Spectroscopic Survey (LRS) provides massive spectroscopic data on M-type stars, and the derived stellar ...parameters could bring vital help to various studies. We adopt the ULySS package to perform
χ
2
minimization with model spectra generated from the MILES interpolator and determine the stellar atmospheric parameters for the M-type stars from LAMOST LRS Data Release 8. Comparison with the stellar parameters from the APOGEE Stellar Parameter and Chemical Abundance Pipeline (ASPCAP) suggests that most of our results have good consistency. For M dwarfs, we achieve dispersions better than 74 K, 0.19 dex, and 0.16 dex for
T
eff
,
log
g
, and Fe/H, while for M giants, the internal uncertainties are 58 K, 0.32 dex, and 0.26 dex, respectively. Compared to ASPCAP we also find a systematic underestimation of Δ
T
eff
= −176 K for M dwarfs and a systematic overestimation of
Δ
log
g
= 0.30 dex for M giants. However, such differences are less significant when we make a comparison with common stars from other literature, which indicates that systematic biases exist in the difference between ASPCAP and other measurements. A catalog of 763,136 spectra corresponding to 616,314 M-type stars with derived stellar parameters is presented. We determine the stellar parameters for stars with
T
eff
higher than 2900 K, with
log
g
from −0.24 dex to 5.9 dex. The typical precisions are 45 K, 0.25 dex, and 0.22 dex, for
T
eff
,
log
g
, and Fe/H, respectively, which are estimated from duplicate observations of the same stars.
Abstract Highly r -process-enhanced (RPE) stars are rare and usually metal poor (Fe/H < −1.0), and they mainly populate the Milky Way halo and dwarf galaxies. This study presents the discovery of a ...relatively bright ( V = 12.72), highly RPE ( r -II) star (Eu/Fe = +1.32, Ba/Eu = −0.95), LAMOST J020623.21+494127.9. This star was selected from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope medium-resolution ( R ∼ 7500) spectroscopic survey; follow-up high-resolution ( R ∼ 25,000) observations were conducted with the High Optical Resolution Spectrograph installed on the Gran Telescopio Canarias. The stellar parameters ( T eff = 4130 K, log g = 1.52, Fe/H = −0.54, ξ = 1.80 km s −1 ) have been inferred taking into account nonlocal thermodynamic equilibrium effects. The abundances of Ce/Fe, Pr/Fe, and Nd/Fe are +0.19, +0.65, and +0.64, respectively, relatively low compared to the Solar r -process pattern normalized to Eu. This star has a high metallicity (Fe/H = −0.54) compared to most other highly RPE stars and has the highest measured abundance ratio of Eu to H (Eu/H = +0.78). It is classified as a thin-disk star based on its kinematics and does not appear to belong to any known stream or dwarf galaxy.
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