Abstract
1
T
-TaS
2
undergoes successive phase transitions upon cooling and eventually enters an insulating state of mysterious origin. Some consider this state to be a band insulator with interlayer ...stacking order, yet others attribute it to Mott physics that support a quantum spin liquid state. Here, we determine the electronic and structural properties of 1
T
-TaS
2
using angle-resolved photoemission spectroscopy and X-Ray diffraction. At low temperatures, the 2π/2c-periodic band dispersion, along with half-integer-indexed diffraction peaks along the
c
axis, unambiguously indicates that the ground state of 1
T
-TaS
2
is a band insulator with interlayer dimerization. Upon heating, however, the system undergoes a transition into a Mott insulating state, which only exists in a narrow temperature window. Our results refute the idea of searching for quantum magnetism in 1
T
-TaS
2
only at low temperatures, and highlight the competition between on-site Coulomb repulsion and interlayer hopping as a crucial aspect for understanding the material’s electronic properties.
A regional synthesis of organic carbon (OC) burial was conducted using a comprehensive data set to reveal some of the key drivers and human multi‐stressors controlling OC burial and transport in the ...Eastern China Marginal Seas (ECMS). Both OC and Δ14C values of suspended particulate matter (SPM) in the Changjiang River, were significantly higher than estuarine mobile‐muds, suggesting selective decay of more labile younger OC from both marine and terrestrial sources and the accumulation of more recalcitrant older OC. Some of this decay is likely to be associated with iron‐redox cycling in mobile‐muds. In contrast, OC, δ13C, and Δ14C values increased along the Yellow River sediment dispersal pathway, indicating adding of young marine OC and less decay of terrestrial OC. OC burial efficiency in mud areas in the Bohai Sea (∼43%) was significantly higher than those in the Yellow (∼11%) and East China Seas (∼16%), owing to rapid deposition. Burial flux of biospheric OC in mud areas of the ECMS is 7.00 ± 0.79 Mt yr−1, corresponding to atmospheric CO2 drawdown by silicate weathering in major river drainage basins of mainland China. The burial flux of petrogenic OC was estimated to be 0.81 ± 0.25 Mt yr−1, accounting for >1.9% of total burial in the global ocean. While the ECMS is an important OC sink, river damming has greatly reduced OC burial. Thus, the overall impact on anthropogenically altered river‐dominated marginal seas remains an important and rapidly changing component of the coastal ocean carbon budget.
Plain Language Summary
A comprehensive regional synthesis of organic carbon (OC) burial and its drivers, were investigated across the Eastern China Marginal Seas (ECMS). Variation of OC content and carbon isotopic composition from suspended particulate matter to mobile muds, in Changjiang sediment dispersal pathways, indicated selective decomposition of younger more labile marine and terrestrial OC, which resulted in the accumulation of older more recalcitrant OC. However, continuous adding of young marine OC, with little loss of terrestrial OC, in Yellow River sediment dispersal pathway, resulted in more recalcitrant terrestrial OC buried in this relatively more quiescent sedimentary regime. Burial efficiencies of OC from different sources in the ECMS were mainly controlled by OC reactivity and sediment mixing dynamics. The ECMS is an important sink of both petrogenic and biospheric OC over a timescale of ∼100 years. However, dam building in river basins has reduced sediment loads of the Changjiang and Yellow Rivers, which will continually decrease OC burial in the ECMS for decades to come. The changing residence time and redox pathways in these sedimentary regimes, partly controlled by increasing human stressors in the ECMS, are expected to have an important impact on rates of OC turnover and burial in marginal seas.
Key Points
Aging of terrestrial organic carbon in the Changjiang sedimentary system is more intense than that in the Yellow River sedimentary system
More efficient burial of organic carbon in the quiescent Bohai and Yellow Seas mud areas compared to East China Sea mobile muds
The Eastern China Marginal Seas are important OC sinks in terms of both petrogenic and biospheric OC burial fluxes
Fast radio bursts (FRBs) are highly dispersed, millisecond-duration radio bursts1-3. Recent observations of a Galactic FRB4-8 suggest that at least some FRBs originate from magnetars, but the origin ...of cosmological FRBs is still not settled. Here we report the detection of1,863 bursts in 82 h over 54 days from the repeating source FRB 20201124A (ref.9). These observations show irregular short-time variation ofthe Faraday rotation measure (RM), which scrutinizes the density-weighted line-of-sight magnetic field strength, of individual bursts during the first 36 days, followed by a constant RM. We detected circular polarization in more than half of the burst sample, including one burst reaching a high fractional circular polarization of 75%. Oscillations in fractional linear and circular polarizations, as well as polarization angle as a function of wavelength, were detected. All of these features provide evidence for a complicated, dynamically evolving, magnetized immediate environment within about an astronomical unit (au; Earth-Sun distance) ofthe source. Our optical observations of its Milky-Way-sized, metal-rich host galaxy10-12 show a barred spiral, with the FRB source residing in a low-stellar-density interarm region at an intermediate galactocentric distance. This environment is inconsistent with a young magnetar engine formed during an extreme explosion of a massive star that resulted in a long gamma-ray burst or superluminous supernova.
To identify the association between the expression of lncRNA NEAT1 and clinicopathological characteristics of patients with HCC, and to explore the prognostic significance of lncRNA NEAT1 in ...predicting prognosis of HCC.
We retrospectively reviewed 86 patients with HCC (35 female, 51 male) managed in our institution between 2009 and 2014. The expression level of lncRNA NEAT1 was detected by real-time PCR. Prognostic factors were evaluated using Kaplan–Meier curves and Cox proportional hazards models.
For the entire cohort of 86 patients, we showed that the expression level of NEAT1 was significantly higher in HCC tissues compared with non-tumorous tissues and NEAT1 was increased obviously in the HCC cell lines including SMMC-7721, Huh-7 and Hep3B (P < 0.001). MTT assay showed that si-NEAT1 remarkably inhibited the cell proliferation in three HCC cell lines. Moreover, over-expression of lncRNA NEAT1 was closely related to liver cirrhosis (P = 0.026), microvascular invasion (MVI) (P = 0.023), and TNM stage (P = 0.017). After adjusting for competing risk factors, we identified that expression level of lncRNA NEAT1 was an independently risk factor associated with the prognosis of patients with HCC (P = 0.031).
In this study, we found NEAT1 expressed significantly higher in HCC tissues compared with non-tumorous tissues. Overexpression of lncRNA NEAT1 was an independently risk factor associated with the prognosis of patients with HCC.
A novel compact high-flux neutron generator with a pitcher-catcher configuration based on laser-driven collisionless shock acceleration (CSA) is proposed and experimentally verified. Different from ...those that previously relied on target normal sheath acceleration (TNSA), CSA in nature favors not only acceleration of deuterons (instead of hydrogen contaminants) but also increasing of the number of deuterons in the high-energy range, therefore having great advantages for production of high-flux neutron source. The proof-of-principle experiment has observed a typical CSA plateau feature from 2 to 6 MeV in deuteron energy spectrum and measured a forward neutron flux with yield 6.6×10^{7} n/sr from the LiF catcher target, an order of magnitude higher than the compared TNSA case, where the laser intensity is 10^{19} W/cm^{2}. Self-consistent simulations have reproduced the experimental results and predicted that a high-flux forward neutron source with yield up to 5×10^{10} n/sr can be obtained when laser intensity increases to 10^{21} W/cm^{2} under the same laser energy.
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•Nonlinear vibrations a simply supported piezoelectric rectangular plate are analyzed.•Primary parametric resonance and 1:3 internal resonance are considered.•Governing equation of motion for the ...composite piezoelectric rectangular plate is derived.•A two-degree-of-freedom nonlinear system is obtained.•Numerical results illustrate the existence of the periodic and chaotic motions.
The nonlinear vibrations and chaotic motions of a simply supported symmetric cross-ply composite laminated piezoelectric rectangular plate subjected to the transverse and in-plane excitations are analyzed in the case of primary parametric resonance and 1:3 internal resonance. It is assumed that different layers of the symmetric cross-ply composite laminated piezoelectric rectangular plate are perfectly bonded to each other and with piezoelectric actuator layers embedded in the plate. Based on the Reddy’s third-order shear deformation plate theory, the nonlinear governing equation of motion for the composite laminated piezoelectric rectangular plate is derived by using the Hamilton’s principle. The Galerkin’s approach is employed to discretize the partial differential governing equation to a two-degree-of-freedom nonlinear system under combined the parametric and external excitations. The method of multiple scales is utilized to obtain the four-dimensional averaged equation. Numerical method is used to find the bifurcation diagram, the periodic and chaotic motions of the composite laminated piezoelectric rectangular plate. The numerical results illustrate the existence of the periodic and chaotic motions in the averaged equation. It is found that the chaotic responses are especially sensitive to the forcing and the parametric excitations. The influences of the transverse, in-plane and piezoelectric excitations on the bifurcations and chaotic behaviors of the composite laminated piezoelectric rectangular plate are investigated numerically.
To investigate the potential effect of 3-n-butylphthalide (NBP) pretreatment on the cerebral ischemia/reperfusion injury in rats and the relevant mechanism.
A total of 90 rats was divided into three ...groups: Sham operation group (Sham group), ischemia-reperfusion group (I-R group), and NBP pretreatment group (NBP group 75 mg·kg-1·d-1 gavage). Pre-treatment was given once a day within 1 week before establishing the rat model of cerebral ischemia-reperfusion injury. The middle cerebral artery occlusion (MACO) rat models were established with the improved Longa-Zea method on the 7th day after ischemia for 2 h and reperfusion for 24 h in all the rats. We detected the cerebral infarction, the pathologic change of brain, the apoptosis of nerve cell, the production levels of reactive oxygen species (ROS), the content of malonaldehyde (MDA) and the activity of superoxide dismutase (SOD), the water content and the permeability of blood-brain barriers (BBB). In addition, we also observed the expressions of mitogen-activated protein kinase (MAPK, p-38, JNK, ERK1/2) and cleaved caspase-3 in the hippocampus tissues.
Compared with Sham group, we discovered that NBP significantly reduced infarction area, cell apoptosis, BBB damage and water content. Further, we found that NBP could also decrease ROS and MDA, and increase SOD activity in brain tissues of rats with a cerebral ischemia-reperfusion injury. Moreover, results showed that NBP also inhibited the levels p38 and JNK.
NBP protected the cerebral from I/R injury, providing ideas for the expansion of clinical adaptability of NBP and possible approaches for its application.
Polymorphism occurs widely in pharmaceutical solids, and must be thoroughly studied during product development. Twenty-four years after ritonavir (RTV) Form II materialized, we report a new ...polymorph, Form III, discovered via melt crystallization. Form III has a unique PXRD pattern, Raman spectrum, lower melting point and heat of fusion, compared to the known polymorphs, Form I and Form II. It is the least stable form, monotropically, among the three polymorphs. Form III differs from Form I and Form II in molecular conformation and hydrogen bonding motifs in crystal lattice. Nucleation from RTV supercooled liquid is slow, and selected Form III exclusively. The discovery of RTV Form III demonstrates the importance of crystal nucleation studies. Crystallization from supercooled liquids should be incorporated as part of polymorph screening workflow.
Fifty‐five 48‐h PM2.5 samples were collected from March 2003 to January 2004 at Changdao, a resort island in Bohai Sea/Yellow Sea in Northern China. Sulfate, nitrate and ammonium accounted for 54 ± ...9% of the PM2.5 mass concentration (annual average 47 μg m−3) while organic matter and K+ contributed to 27 ± 7% and 7 ± 7% of the total mass, respectively. The ratios of SO42− to NO3− mass concentrations could be divided into two regimes and demarcated at nitrate concentration of 5 μg m−3. In the low NO3− regime, NO3−, SO42− and EC were well correlated to K+, and the estimated contributions of NO3−, SO42− and EC from biomass burning were 50 ± 27%, 38 ± 24% and 47 ± 27%, respectively. These correlations substantially decreased in the high NO3− regime reflecting fossil fuel combustion and formation of ammonium nitrate and the estimated contributions of NO3−, SO42− and EC from biomass burning were 16 ± 12%, 28 ± 18% and 27 ± 16%, respectively. In most samples, the equivalent ratios of total anion to total cation concentrations were greater than unity, suggesting that the aerosols were acidic. When H+ > 0, a moderately good linear correlation of the estimated aerosol acidity H+ with the water‐soluble organic carbon (WSOC) was observed with R2 = 0.70 and an increase of H+ by 100 neq m−3 would increase 1.2 μg m−3 WSOC in PM2.5. When H+ > 0, an increase of H+ by 100 neq m−3 would increase 1.4 μg m−3 of secondary organic carbon (SOC) in PM2.5. Moreover, the correlation analysis result suggested that 60% of the estimated SOC (on average) in PM2.5 were water‐soluble.
Key Points
Two regimes were derived based on the sulfate to nitrate ratio
Acidic aerosol can enhance the formation of secondary organic carbon
Contribution of biomass burning to particulate matter varied from 10 to 50%
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