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A redroot pigweed (Amaranthus retroﬂexus L.) population (HN-02) collected from Nenjiang County, Heilongjiang Province, exhibited multiple resistance to fomesafen and nicosulfuron. The purposes of the study were to characterize both the herbicide resistance status of an HN-02 population for ALS and PPO inhibitors, the response to other herbicides and to investigate the target site-based mechanism governing fomesafen and nicosulfuron resistance. Three mutations, Ala-205-Val and Trp-574-Leu mutations in the ALS gene and an Arg-128-Gly mutation in the PPX2 gene, were identified in individual resistant plants. An HN-02F1-1 subpopulation homozygous for the Ala-205-Val and Arg-128-Gly mutations was generated, and whole-plant experiments confirmed multiple resistance to PPO inhibitors (fomesafen, fluoroglycofen-ethyl and acifluorfen) and ALS inhibitors (IMI, SU and TP) in the HN-02F1-1 plants, which presented resistance index (RI) values ranging from 8.3 to 110; however, these plants were sensitive to flumioxazin, fluroxypyr-meptyl and 2,4-D butylate. In vitro ALS enzyme activity assays revealed that, compared with ALS from susceptible plants, ALS from the HN-02F1-1 plants was 15-, 28- and 320-fold resistant to flumetsulam, nicosulfuron and imazethapyr, respectively. This study determines the first case of multiple resistance to PPO and ALS inhibitors in A. retroﬂexus, and the TSR mechanism was provided by Ala-205-Val and Arg-128-Gly mutations in the ALS gene and PPX2 gene, respectively. In particular, the Ala-205-Val mutation was found to endow resistance to three classes of ALS inhibitors: TP, SU, and IMI.
Wildfires are sensitive to climate change, but their response to changes in temperature and precipitation on long timescales is still disputed. In this study, we present a ~9.4 ka black carbon mass sedimentation rate (BCMSR) record from Lake Ximenglongtan (XMLT), southwestern China, to elucidate the Holocene fire regime and its linkages to climatic conditions. The results indicate that the regional fire activity was low during the early Holocene (before 7.6 cal ka BP), increased notably at 7.6 cal ka BP, and continued to increase gradually during the mid- to late Holocene until 2.2 ka. The episodes of higher fire occurrence reflected by higher BCMSR over the last 2.2 ka might be more likely related to the intensified human activities. The cool and humid climate during the early Holocene limited the spread of fire, while warming and drying at ~7.6 cal ka BP triggered higher fire occurrence. Instead of temperature, changes in precipitation dominated fire regime variation during the mid- to late Holocene. On millennial timescales, we suggest that Holocene fire variability has been predominantly controlled by the combined effects of Northern Hemisphere (NH) summer and winter insolation that influenced monsoonal precipitation and fire season temperature, respectively. Indian Ocean Dipole (IOD) events may also have affected fire incidence through influencing monsoon intensity.
Schizophrenia is a complex mental disorder with high heritability and polygenic inheritance. Multimodal neuroimaging studies have also indicated that abnormalities of brain structure and function are a plausible neurobiological characterisation of schizophrenia. However, the polygenic effects of schizophrenia on these imaging endophenotypes have not yet been fully elucidated.
To investigate the effects of polygenic risk for schizophrenia on the brain grey matter volume and functional connectivity, which are disrupted in schizophrenia.
Genomic and neuroimaging data from a large sample of Han Chinese patients with schizophrenia (N = 509) and healthy controls (N = 502) were included in this study. We examined grey matter volume and functional connectivity via structural and functional magnetic resonance imaging, respectively. Using the data from a recent meta-analysis of a genome-wide association study that comprised a large number of Chinese people, we calculated a polygenic risk score (PGRS) for each participant.
The imaging genetic analysis revealed that the individual PGRS showed a significantly negative correlation with the hippocampal grey matter volume and hippocampus–medial prefrontal cortex functional connectivity, both of which were lower in the people with schizophrenia than in the controls. We also found that the observed neuroimaging measures showed weak but similar changes in unaffected first-degree relatives of patients with schizophrenia.
These findings suggested that genetically influenced brain grey matter volume and functional connectivity may provide important clues for understanding the pathological mechanisms of schizophrenia and for the early diagnosis of schizophrenia.
Agetolites is a problematic Late Ordovician genus possessing traits of both tabulate and rugose corals. The presence of numerous mural pores has often been considered to indicate a relation to tabulates, although an affinity to rugosans has also been proposed, based mainly on well-developed septa that alternate in length. To further consider the taxonomic position of Agetolites, growth characteristics of coralla representing three species from the Xiazhen Formation in South China are documented and assessed, focusing on modes of corallite increase. Three major modes of increase are recognized. By far the most common mode involves the development of an offset from a connective mural pore, without a clear relationship to a particular parent corallite. This mode of increase is usually associated with corner pores, but in one case occurs at a wall pore. The lateral mode of increase, which is relatively uncommon, is a typical feature in corallites along the boundary of intergrowths with stromatoporoids. The axial mode of increase is rare, occurring during rejuvenation of a damaged corallite or during regeneration following termination of a corallite. The mode of corallite increase that is characteristic of Agetolites, involving a connective mural pore and occurring without evidence of a particular parent, supports the interpretation that this genus is not a rugosan or a typical favositid tabulate. Mural pores are unknown in rugosans, and offsets arise from distinct parent corallites in favositids. The Ordovician genus Lichenaria, considered a representative of the most primitive stock of tabulate corals, shows the closest similarities with types of increase in Agetolites. Certain aspects of lateral and axial increase in Agetolites are comparable to features in a few more genera of Ordovician tabulates, further supporting a tabulate affinity. The phylogenetic relation of Agetolites to those and other tabulate genera, however, remains unresolved.
The micro-nano rough structure promotes the formation of superhydrophobic surfaces, while the formation of superoleophobic surfaces requires the support of re-entrant structures. Electrochemical etching and boiling water treatment methods were used to process the superoleophobic surface in the Al–Mg alloy substrate. The differences between the potential of the aluminum and the magnesium promoted the formation of the surface microstructure under the current stimulation, and the surface was formed into dense nanoscale needle-like coating after boiling water treatment. Scanning electron microscopy, energy dispersive spectroscopy, and contact angle measurement were performed to characterize the morphological features, chemical composition, and surface wettability, respectively. The so-prepared superoleophobic surfaces showed high contact angles and small sliding angles for water, ethylene glycol, and hexadecane. In addition, surface topography, reaction mechanism, and experimental parameters were also studied.
VISTA observed the Small Magellanic Cloud (SMC), as part of the VISTA survey of the Magellanic Clouds system (VMC), for six years (2010–2016). The acquired multi-epoch YJKs images have allowed us to probe the stellar populations to an exceptional level of detail across an unprecedented wide area in the near-infrared. This contribution highlights the most recent VMC results obtained on the SMC focusing, in particular, on the clustering of young stellar populations, on the proper motion of stars in the main body of the galaxy and on the spatial distribution of the star formation history.
The influence of tilt on flow reversals in two-dimensional thermal convection in rectangular cells with two typical aspect ratios,
and 2, are investigated by means of direct numerical simulations. For
, tilt tends to suppress flow reversals. However, it is found that flow reversals characterized by two main rolls are promoted by tilt for
, which are even observed for some cases of small Prandtl numbers (
) and large tilt angles (
). Different from level cases where the four corner rolls all have opportunities to grow and trigger a flow reversal, the reversals in an anticlockwise tilted cell with
are always led by the growth of the bottom-right or the top-left corner roll. Tilt is favourable for the growth of the bottom-right or the top-left corner roll and thus for breaking the balance between the two main rolls and triggering a flow reversal. The mode decomposition analysis shows that the appearance of the intermediate single-roll mode is crucial for reversals, and flow reversals in a tilted cell with
can be viewed as a mode competition process between single-roll mode and horizontally adjacent double-roll mode. They can only occur in a limited range of
where the two modes have comparable strength. Furthermore, the Nusselt numbers at the hot plate
and at the cold plate
behave differently during a flow reversal for
due to the preference of single corner roll growth.
The influences of non-Oberbeck–Boussinesq (NOB) effects on flow instabilities and bifurcation characteristics of Rayleigh–Bénard convection are examined. The working fluid is air with reference Prandtl number
and contained in two-dimensional rigid cavities of finite aspect ratios. The fluid flow is governed by the low-Mach-number equations, accounting for the NOB effects due to large temperature difference involving flow compressibility and variations of fluid viscosity and thermal conductivity with temperature. The intensity of NOB effects is measured by the dimensionless temperature differential
. Linear stability analysis of the thermal conduction state is performed. An
scaling of the leading-order corrections of critical Rayleigh number
and disturbance growth rate
due to NOB effects is identified, which is a consequence of an intrinsic symmetry of the system. The influences of weak NOB effects on flow instabilities are further studied by perturbation expansion of linear stability equations with regard to
, and then the influence of aspect ratio
is investigated in detail. NOB effects are found to enhance (weaken) flow stability in large (narrow) cavities. Detailed contributions of compressibility, viscosity and buoyancy actions on disturbance kinetic energy growth are identified quantitatively by energy analysis. Besides, a weakly nonlinear theory is developed based on centre-manifold reduction to investigate the NOB influences on bifurcation characteristics near convection onset, and amplitude equations are constructed for both codimension-one and -two cases. Rich bifurcation regimes are observed based on amplitude equations and also confirmed by direct numerical simulation. Weakly nonlinear analysis is useful for organizing and understanding these simulation results.
Due to an increasing number of nuclear reactors in operation, the radiocarbon (14C) released from nuclear power plants (NPPs) has become an important anthropogenic source of 14C. The examination of seasonal Δ14C and monthly Sr/Ca, Mg/Ca variations in a coral in Daya Bay (China) shows that NPPs located there have an impact on the Δ14C level and sea surface temperature (SST). The Mg/Ca variation was in good correlation with the Pacific Decadal Oscillation (PDO) before the operation of Ling’ao NPP in 2002, but this correlation became weak due to an abnormally higher SST after 2002. As illustrated by the Δ14C variation in the coral, there were two relative increases of Δ14C values in 1994 and 2002 when Daya Bay NPP and Ling’ao NPP began operations, respectively. The 14C released from NPPs, instead of oceanic circulation, is probably the primary factor on the Δ14C variation in Daya Bay during the NPPs’ operation. The relative increase in Δ14C value was ~80‰, which equals to ~18 Bq/kgC in specific activity. The seasonal variability in Δ14C value usually peaked in summer, the real reason of which was unknown. This study sheds light on how the NPPs influence the 14C content and SST in surrounding marine environment.
To determine the spray forming process parameters of 7075/Al–Si bimetallic gradient composite plate with two gas atomizers, a calculation model of the plate has been established by using the finite element software ANSYS. The effects of different motion trajectory, advance speed, swing cycle and spray center distance on shape, and silicon distribution of deposited plate have been simulated by the APDL programming language. The results show that a smooth and uniform surface is obtained when motion trajectory is in a regular jaggies mode. The deposited plate varies from platform to stepped shape with a center distance increasing from 20 mm to 50 mm; meanwhile, the width of the transition zone decreases gradually. As the period increases to 8 s, the silicon distribution of each layer presents a jagged fluctuation. Both the thickness of the deposited plate and the width of the transition zone decrease as the advance speed increases, except the silicon distribution. Finally, the modeling and simulation of the co-spray formed 7075/Al–Si bimetallic gradient composite plate are validated by experimental investigations and the simulation results are in good agreement with the actual results.
The composite Li-ion battery anode material of Fe2SiO4, Fe3O4, Fe3C (Fe-Si-O) and carbon nanotubes was prepared by a simple one-step reaction between ferrocene and tetraethyl orthosilicate. When cycled at 100 mA g-1, this material exhibited ever-increasing capacities and reached 588 mAh g-1 at the 280th cycle. At 500 mA g-1, a reversible capacity of 350 mAh g-1 was retained for 600 cycles. Compared with Fe3O4 materials, the Fe-Si-O/CNT exhibited superior long-term high-rate performance, which could mainly result from its enhanced stability and conductivities by introducing silicates and CNTs during the one-step synthesis.
An Al–10.83Zn–3.39Mg–1.22Cu–0.16Zr–0.16Sc alloy was produced using the spray deposition technology. The microstructure evolution within temperature ranging between 613 K and 733 K during hot pressing process at different initial strain rate was investigated in a transmission electron microscope (TEM). Partial resolution of the primary precipitates in the deposited microstructure, such as η-MgZn2 and Al3(ScZr), took place. Moreover, new secondary η-MgZn2 and Al3(ScZr) precipitated from the super saturated solid solution and their effects on the recrystallization were also analyzed. The Al3(ScZr) and η-MgZn2 precipitation can act as barriers for the movement of both dislocations and grain boundaries, which are the main factors for hindering the recrystallization. Additionally, the dislocation slide during hot deformation was also investigated in detail. The spray deposition Al–Zn–Mg–Cu alloy own the well deformability, and the typical perfect dislocations can be found in the hot deformation Al–Zn–Mg–Cu alloy.
Flow reversals in two-dimensional Rayleigh–Bénard convection led by non-Oberbeck–Boussinesq (NOB) effects due to large temperature differences are studied by direct numerical simulation. Perfect gas is chosen as the working fluid and the Prandtl number is 0.71 for the reference state. If NOB effects are included, the flow pattern
with only one dominant roll often becomes unstable by the growth of the cold corner roll, which sometimes results in cession-led flow reversals. By exploiting the vorticity transport equation, it is found that the asymmetries of buoyancy and viscous forces are responsible for the growth of the cold corner roll because both such asymmetries cause an imbalance between the corner rolls and the large-scale circulation (LSC). The buoyancy force near the cold wall increases and decreases near the hot wall originating from the temperature-dependent isobaric thermal expansion coefficient
if NOB effects are included. Moreover, the decreased dissipation due to lower viscosity is favourable for the growth of the cold corner roll, while the increased viscosity further suppresses the growth of the hot corner roll. Finally, it is found that the boundary layer near the cold wall plays an important role in the mass transport from LSC to corner rolls subject to mass conservation.
In light of government investment over the past decade, we explored the capacity for disaster response in Heilongjiang Province, identifying the factors that affect response capacity.
We surveyed 1257 medical staff in 65 secondary and tertiary hospitals in Heilongjiang province to explore their perceptions of disaster management capacity using a cross-sectional multistage, stratified cluster sampling method.
All tertiary hospitals (100%) and most secondary hospitals (93%) have documented disaster management plans that are regularly reviewed. In secondary hospitals, drills were less prevalent (76.7%) but the occurrence of simulated training exercises was closer to tertiary hospitals (86.0%). We noted that 95.4% of all hospitals have leadership groups responsible for disaster preparedness capacity building, but only 10.8% have a stockpiled network of reserve supplies.
Although response capacity has improved in Heilongjiang Province, vulnerabilities remain. We recommend that priorities should be targeted at preparedness capacity building, in terms of reliable and relevant operational response plans, the expansion of existing response mechanisms to oversee local education and scenario training, and to ensure there is sufficient access to protective equipment and materials, either held in reserve, or alternatively by activating resilient supply chain mechanisms. (Disaster Med Public Health Preparedness. 2018;12:176–183)
Due to the existence of invariant tori, chaotic sea and hyperbolic structures in higher dimensional phase space of a volume-preserving map, the diffusion route of chaotic orbits will be complicated. The velocity of diffusion will be very slow if the orbits are near an invariant torus. In order to realize this complicated diffusion phenomenon, in this paper we study the diffusion characters in the different regions, i.e., chaotic, hyperbolic and invariant tori’s regions. We find that for the three different regions, the diffusion velocities are different. The diffusion velocity in the vicinity of an invariant torus is the slowest one.
The current meta-analysis evaluated the association between vitamin B12 intake and blood vitamin B12 level and colorectal cancer (CRC) risk.
The PubMed and EMBASE databases were searched. A dose–response analysis was performed with generalized least squares regression, with the relative risk (RR) and 95 % CI as effect values.
The meta-analysis included seventeen studies.
A total of 10 601 patients.
The non-linear dose–response relationship between total vitamin B12 intake and CRC risk was insignificant (P=0·690), but the relationship between dietary vitamin B12 intake and CRC risk was significant (P<0·001). Every 4·5 μg/d increment in total and dietary vitamin B12 intake was inversely associated with CRC risk (total intake: RR=0·963; 95 % CI 0·928, 0·999; dietary intake: RR=0·914; 95 % CI 0·856, 0·977). The inverse association between vitamin B12 intake and CRC risk was also significant when vitamin B12 intake was over a dosage threshold, enhancing the non-linear relationship. The non-linear dose–response relationship between blood vitamin B12 level and CRC risk was insignificant (P=0·219). There was an insignificant association between every 150 pmol/l increment in blood vitamin B12 level and CRC risk (RR=1·023; 95 % CI 0·881, 1·187).
Our meta-analysis indicates that evidence supports the use of vitamin B12 for cancer prevention, especially among populations with high-dose vitamin B12 intake, and that the association between CRC risk and total vitamin B12 intake is stronger than between CRC risk and dietary vitamin B12 intake only.
Cavitation bubbles, which always exist in the diesel jet leaving the nozzle and in diesel droplets breaking up from the jet as a result of supercavitation of the diesel within the injection nozzle, increase the instability of jet and droplets in part due to the two-phase mixture, while the mechanism of this effect is still unclear. Cavitation bubble expansion within the diesel droplet has been simulated numerically based on the volume of fluid (VOF) method, and the control mechanism of bubble growth process is analyzed by Rayleigh-Plesset equation. The process of bubble growth is divided into three parts, including surface tension controlled domain, comprehensive competition controlled domain and inertial force controlled domain. During the first stage, cavitation bubble growth is controlled by the surface tension, and the decrease of the surface tension leads to the increase of the bubble growth rate. During the second stage, the bubble growth rate is controlled by the comprehensive competition of the surface tension, the inertial force and the viscous force. During the third stage, the process of bubble growth is majorly controlled by the inertial force.
A defect in the intestinal barrier is one of the characteristics of Crohn's disease (CD). The tight junction (TJ) changes and death of epithelial cells caused by intestinal inflammation play an important role in the development of CD. DHA, a long-chain PUFA, has been shown to be helpful in treating inflammatory bowel disease in experimental models by inhibiting the NF-κB pathway. The present study aimed at investigating the specific effect of DHA on the intestinal barrier function in IL-10-deficient mice. IL-10-deficient mice (IL-10− / −) at 16 weeks of age with established colitis were treated with DHA (i.g. 35·5 mg/kg per d) for 2 weeks. The severity of their colitis, levels of pro-inflammatory cytokines, epithelial gene expression, the distributions of TJ proteins (occludin and zona occludens (ZO)-1), and epithelial apoptosis in the proximal colon were measured at the end of the experiment. DHA treatment attenuated the established colitis and was associated with reduced infiltration of inflammatory cells in the colonic mucosa, lower mean histological scores and decreased levels of pro-inflammatory cytokines (IL-17, TNF-α and interferon-γ). Moreover, enhanced barrier function was observed in the DHA-treated mice that resulted from attenuated colonic permeability, rescued expression and corrected distributions of occludin and ZO-1. The results of the present study indicate that DHA therapy may ameliorate experimental colitis in IL-10− / − mice by improving the intestinal epithelial barrier function.