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•Understanding river contamination requires details of geomorphological functions.•A combined geomorphic and physicochemical survey provides this context.•Different trace elements ...followed distinct geomorphic patterns in a river.•Identifying specific hotspots can inform targeted remediation methods.
River morphology plays a vital role in the transport of substance within them. However, our understanding of how natural and artificial morphologies redistribute different potentially toxic elements in acid mine drainage (AMD)-contaminated rivers remains poor. In this study, we linked morphological river features and physicochemical sediment characteristics to trace the redistribution of various potentially toxic elements and elucidate their implications for remediating rivers prone to AMD pollution. A dense network of sediment/soil samples was collected from different river morphological units, such as channels, dam reservoirs, pools, floodplain sandbars and wetlands in an AMD-impacted river. The analyses showed that the contaminant levels in channel generally decreased downstream from the headwater mine site, however, local fluctuations in certain areas were observed due to the trapping effect of various dams along the river. The As and Pb concentrations were higher at floodplain sandbars, while river channels exhibited higher Cd and Zn contamination. The concentrations and geochemical fractions of As, Cd, Cu, Pb and Zn in sediment/soil cores from sandbar and river channel also varied. Additionally, structural equation modeling analysis indicated that spatial variations in contaminant distributions were directly affected by physicochemical properties (such as the soil/sediment Fe, Zn, and S concentrations, and pH), which are indirectly affected by river morphology. The diverse morphology of the river redistributed AMD-derived contaminants and could be used to identify contamination hotspots. Our analyses suggested that the feasibility and efficiency of previously proposed countermeasures varied for contaminants in different geomorphological units. In river channels, As uptake from sediments by aquatic plants may be less efficient than Cd, Cu, and Zn uptake due to its lower bioavailability. Moreover, vegetation prevented contaminant enriched soil particle erosion more than it aided in the phytoremediation of As- and Pb-contaminated sandbars. Thus the finding of this study provide a theoretical foundation for further studies on the transport and storage of AMD-derived contaminants in similar rivers, along with the development of targeted remediation methods.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In order to improve ground control of the longwall mining, ground response and mining-induced stress in the longwall panel of a kilometer-deep coal mine are investigated in this study. Field ...measurements on abutment stress, roof displacement, and fracture development indicate that the region influenced by the longwall mining reaches 150 m ahead of the longwall face. Failure scope of the coal seam, where mining-induced fractures are well developed, ranges from 10 to 13 m inward the face line. Vertical stress concentration coefficient reaches 2.2. Based on the field measurements, a numerical model is moreover developed and utilized to examine the response of the principal stress to the longwall mining. The concentration coefficient, peak point location, and influence scope of the principal stress gradually become stable with an increase in face advancement. Regarding the major principal stress, the concentration coefficient and influence scope are 2.4 and 152 m, respectively, and the peak point locates 13 m inward the face line, which are consistent with the field measurements. With respect to the minor principal stress, the referred coefficient and scope are 1.5 and 172 m, respectively, and its peak point location is 21 m ahead of the face line. The major principal stress in the coal seam rotates from vertical to horizontal direction in the vertical plane parallel with face advance direction. The maximum rotation angle reaches 20°. The minor principal stress first rotates into the referred vertical plane and then it rotates from horizontal to vertical direction at the same speed with the major principal stress in the same plane. Rotation angle of the principal stress in roof strata is greatly enlarged, the rotation trace of which is influenced by the longwall mining and vertical distance above the seam. Based on the relation between rotation trace of the principal stress and face advance direction, the influence of stress rotation on the stability of roof structure is discussed.
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DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UILJ, UKNU, UL, UM, UPUK
Chromobox 4 (CBX4) is a core component of polycomb-repressive complex 1 with important roles in cancer biology and tissue homeostasis. Aberrant expression of CBX4 has been implicated in several human ...malignancies. However, its role and underlying mechanisms in the tumorigenesis of lung adenocarcinoma (LUAD) have not been defined in vivo. Here, we found that expression of CBX4 was frequently up-regulated in human LUAD samples and correlated with poor patient survival. Importantly, genetic ablation of CBX4 greatly dampened lung tumor formation and improved survival in the KrasG12D/P53L/L (KP) autochthonous mouse model of LUAD. In addition, CBX4 depletion significantly inhibited proliferation and anchorage-independent growth of KP mouse embryonic fibroblasts. Moreover, ectopic CBX4 expression clearly promoted proliferation and anchorage-independent growth in both human and mouse LUAD cells, whereas silencing of CBX4 exerted opposite effects. Mechanistically, CBX4 promoted growth of LUAD cells through activation of the Wnt/β-catenin pathway. Furthermore, expression levels of CBX4 were positively correlated with β-catenin in human LUAD samples. In conclusion, our data suggest that CBX4 plays an oncogenic role via the Wnt/β-catenin pathway and could serve as a potential therapeutic target in LUAD.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In order to understand the instability characteristics of surrounding rock in the process of deep roadway excavation, a three-dimensional numerical model was established by FLAC3D to systematically ...analyze the influence of roadway surrounding rock stability under different in situ stress distribution forms, and the environmental coefficient of mining-induced stress η was defined, the larger the environmental coefficient of mining-induced stress is, the larger the surrounding rock stress environment is, and the range where the η coefficient is greater than 0.2 is called with the destruction-danger zone. When the initial vertical stress is maximum principal stress and minimum principal stress, by comparing the roadway along the middle ground stress direction and minimum or maximum in-situ stress direction, the variation characteristics of displacement, failure zone and failure hazard zone of roadway surrounding rock are obtained, which provides theoretical basis for the treatment of disaster accidents such as roadway surrounding rock instability and rock burst caused by deep high in-situ stress.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Gegen Qinlian Decoction (GQD), a well-documented traditional Chinese Medicine (TCM) formula, was reported with convincing anti-diabetic effects in clinical practice. However, the precise antidiabetic ...mechanism of GQD remains unknown. In this study, the anti-hyperglycemic and/or lipid lowering effects of GQD were demonstrated in high-fat diet with a low dose of streptozotocin induced diabetic Sprague-Dawley rats and insulin resistance (IR)-3T3-L1 adipocytes. GQD treatment increased expression and activity levels of both PPARγ and PPARα in adipocytes, which transcriptionally affected an ensemble of glucose and lipid metabolic genes
in vivo
and
in vitro
. The results clearly indicated that GQD treatment intervened with multiple pathways controlled by concomitantly downstream effects of adipocytic PPARγ and PPARα, to influence two opposite lipid pathways: fatty acid oxidation and lipid synthesis. Antagonist GW9662 decreased the mRNA expression of
Pparγ
and target genes
Adpn
and
Glut4
whereas GW6471 decreased the mRNA expression of
Pparα
and target genes
Cpt-1α
,
Lpl
,
Mcad
,
Lcad
,
Acox1, etc
. Nuclear location and activity experiments showed that more PPARγ and PPARα shuttled into nuclear to increase its binding activities with target genes. GQD decreased the phosphorylation level of ERK1/2 and/or CDK5 to elevate PPARγ and PPARα activities in IR-3T3-L1 adipocytes through post-translational modification. The increase in p-p38MAPK and SIRT1 under GQD treatment may be attributed to partially reduce PPARγ adipogenesis activity and/or activate PPARα activity. Compared with the rosiglitazone-treated group, GQD elevated
Cpt-1α
expression, decreased diabetic biomarker
Fabp4
expression, which produced an encouraging lipid profile with triglyceride decrease partially from combined effects on upregulated adipocytic PPARγ and PPARα activities. These results suggested that GQD improved diabetes by intervening a diverse array of PPARγ and PPARα upstream and downstream signaling transduction cascades, which jointly optimized the expression of target gene profiles to promote fatty acid oxidation and accelerate glucose uptake and utilization than PPARγ full agonist rosiglitazone without stimulating PPARα activity. Thus, GQD showed anti-diabetic/or antihyperglycemic effects, partially through regulating adipocytic PPARα and PPARγ signaling systems to maintaining balanced glucose and lipid metabolisms. This study provides a new insight into the anti-diabetic effect of GQD as a PPARα/γ dual agonist to accelerate the clinical use.
UHRF2 has been implicated as a novel regulator for both DNA methylation (5mC) and hydroxymethylation (5hmC), but its physiological function and role in DNA methylation/hydroxymethylation are unknown. ...Here we show that in mice, UHRF2 is more abundantly expressed in the brain and a few other tissues. Uhrf2 knock-out mice are viable and fertile and exhibit no gross defect. Although there is no significant change of DNA methylation, the Uhrf2 null mice exhibit a reduction of 5hmC in the brain, including the cortex and hippocampus. Furthermore, the Uhrf2 null mice exhibit a partial impairment in spatial memory acquisition and retention. Consistent with the phenotype, gene expression profiling uncovers a role for UHRF2 in regulating neuron-related gene expression. Finally, we provide evidence that UHRF2 binds 5hmC in cells but does not appear to affect the TET1 enzymatic activity. Together, our study supports UHRF2 as a bona fide 5hmC reader and further demonstrates a role for 5hmC in neuronal function.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Dicranopteris is a common fern distributed throughout tropical and subtropical regions of the world. It often forms a mat-like understory, especially in open areas. A forest floor dominated by ...Dicranopteris plays an important role in ecosystem dynamics, but is often overlooked in ecological research. We conducted an experiment by removing overstory or understory Dicranopteris to compare their effects on soil microclimate, litter decomposition, soil decomposer food web and ecosystem nutrient cycling. Results of our field study showed that removal of a Dicranopteris-dominated understory leads to increased soil temperature and reduced soil moisture, subsequently, altering the components of the soil food web (microbial community, nematode and microarthropod densities) and reducing ecosystem processes of litter decomposition. When present, Dicranopteris forms a dense understory layer in subtropical and tropical regions, which is favorable for sustaining soil microclimates and acts as the major driver of soil biota and ecological processes in intensive forest ecosystems.
► Understory removal changed soil decomposer communities and litter decomposition. ► Understory removal increased soil temperature and reduced soil moisture. ► The effects of understory removal were more pronounced than canopy tree removal. ► Soil microclimates change may be responsible for changes of other measured variables. ► Dicranopteris-dominated understory is a major driver of intensive forest ecosystem.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Geometric flows have been successfully used for surface modeling and designing, largely because they are inherently good at controlling geometric shape evolution. Variational image segmentation ...approaches, on the other hand, detect objects of interest by deforming certain given shapes. This motivates us to revisit the minimal partition problem for segmentation of images, and propose a new geometric flow-based formulation and solution to it. Our model intends to derive a mapping that will evolve given contours or piecewise-constant regions toward objects in the image. The mapping is approximated by B-spline basis functions, and the positions of the control points are to be determined. Starting with the energy functional based on intensity averaging, we derive a Euler-Lagrange equation and then a geometric evolution equation. The linearized system of equations is efficiently solved via a special matrix-vector multiplication technique. Furthermore, we extend the piecewise-constant model to a piecewise-smooth model which effectively handles images with intensity inhomogeneity.
In the field of heat manipulation, active thermal cloaks based on thermoelectric chips (TECs) have received much less attention than passive thermal cloaks based on metamaterials. This work focuses ...on active thermal cloaks and explores in-depth their mechanism of heat flow regulation. For a two-dimensional circular object located in a rectangular background plate with uniform temperature gradient, the theoretical design of an active cloak was realized by analytically solving for the target temperature field. A parameter study was conducted numerically for the designed thermal cloak. The results show that the object-to-background thermal conductivity ratio (m) is the key parameter that determines the working mode of the cloak. When m < 1, the TECs work in a heating mode with less power consumption; when m > 1, the TECs work in a chilling/heat pump mode with higher power consumption. If the change of a certain parameter increases the heat flow regulation, it will also cause performance degradation and an increase of the thermal cloak’s power consumption, especially when m is greater than 1. Improvement can be achieved by increasing the number of TECs (N), but the impact of N diminishes rapidly beyond a certain value. The systematic study in this work reveals the high flexibility and wide adaptability of the TE-chip-based thermal cloak in heat flow regulation.
•Theoretical methods are developed for determining the input current of TECs in active thermal cloaks.•Two working modes of the TECs are clarified: variable heat conductor and chiller/heat pump.•A method is proposed to estimate the range of heat flow regulation for TE-chip-based thermal cloaks.•If space permits, increasing the number of TECs benefits both energy usage and cloak performance.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Properties of wall pressure beneath a transitional hypersonic boundary layer over a 7
∘
half-angle blunt cone at angle of attack 6
∘
are studied by Direct Numerical Simulation. The wall pressure has ...two distinct frequency peaks. The low-frequency peak with
f
≈10−50 kHz is very likely the unsteady crossflow mode based on its convection direction, i.e. along the axial direction and towards the windward symmetry ray. High-frequency peaks are roughly proportional to the local boundary layer thickness. Along the trajectories of stationary crossflow vortices, the location of intense high-frequency wall pressure moves from the bottom of trough where the boundary layer is thin to the bottom of shoulder where the boundary layer is thick. By comparing the pressure field with that inside a high-speed transitional swept-wing boundary layer dominated by the z-type secondary crossflow mode, we found that the high-frequency signal originates from the Mack mode and evolves into the secondary crossflow instability.
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