Search

Baseflow is an essential component of total surface runoff that is widely considered one of the most influential factors regarding water quality via nonpoint source (NPS) pollution. Previously, many researchers and policy makers have directed their efforts toward surface runoff pollution, largely ignoring nutrient delivery via baseflow. Taking a typical agriculture-intensive basin of northern China as an example, this study explored the spatiotemporal characteristics of baseflow and pollution load in relation to NPS pollution. Baseflow was quantified using digital filtering techniques, and the results together with observed pollution data were used to validate a physically based hydrological model, i.e., the Soil and Water Assessment Tool. Then, the spatial and temporal distribution characteristics of NPS and baseflow pollution were investigated using the modeling results. Results indicated that baseflow contribution to total runoff accounted for more than 70% during the studied years (2016–2018), and 84.15% of the basin area showed non-point source pollution dominated by baseflow pollution; both baseflow and its pollution load were greater in the nonflood seasons (spring, autumn, and winter) than in the flood season (summer); the spatial distribution of baseflow total nitrogen and total phosphorus pollution intensity showed higher values in the east and lower values in the west; the scaling effects of baseflow and its pollution load was found with increasing basin area. The results of our study highlighted the necessity for management of pollution load via baseflow in the river basin and provided reference information for improvement of NPS pollution management in other similar basins. • Baseflow and pollution load were explored in an agriculture-intensive basin. • Both baseflow and pollution load were greater in the nonflood seasons than in the flood season (summer). • Importance of the role of baseflow and its pollution load increases with basin area. [ABSTRACT FROM AUTHOR]

Baseflow is an essential component of total surface runoff that is widely considered one of the most influential factors regarding water quality via nonpoint source (NPS) pollution. Previously, many researchers and policy makers have directed their efforts toward surface runoff pollution, largely ignoring nutrient delivery via baseflow. Taking a typical agriculture-intensive basin of northern China as an example, this study explored the spatiotemporal characteristics of baseflow and pollution load in relation to NPS pollution. Baseflow was quantified using digital filtering techniques, and the results together with observed pollution data were used to validate a physically based hydrological model, i.e., the Soil and Water Assessment Tool. Then, the spatial and temporal distribution characteristics of NPS and baseflow pollution were investigated using the modeling results. Results indicated that baseflow contribution to total runoff accounted for more than 70% during the studied years (2016–2018), and 84.15% of the basin area showed non-point source pollution dominated by baseflow pollution; both baseflow and its pollution load were greater in the nonflood seasons (spring, autumn, and winter) than in the flood season (summer); the spatial distribution of baseflow total nitrogen and total phosphorus pollution intensity showed higher values in the east and lower values in the west; the scaling effects of baseflow and its pollution load was found with increasing basin area. The results of our study highlighted the necessity for management of pollution load via baseflow in the river basin and provided reference information for improvement of NPS pollution management in other similar basins. • Baseflow and pollution load were explored in an agriculture-intensive basin. • Both baseflow and pollution load were greater in the nonflood seasons than in the flood season (summer). • Importance of the role of baseflow and its pollution load increases with basin area. [ABSTRACT FROM AUTHOR]

As sodium-ion batteries (SIBs) attract more attention, various host materials allowing Na-ions insertion/extraction are being developed. Among them, Prussian blue analogues (PBAs), as typical metal organic frameworks, are regarded as promising cathodes for SIBs because of their open frame structure and simple synthesis process. However, the presence of [Fe(CN) 6 ] vacancies and crystal water in PBA framework usually induce poor electrochemical performance. Herein, high quality Na-rich monoclinic nickel hexacyanoferrate Na 1.95 Ni[Fe(CN) 6 ] 0.89 ·2.87H 2 O with nanocubes morphology (NiHCF–NCs) has been prepared through a simple diethylenetriaminepentaacetic acid disodium (Na 2 DTPA)-assisted coprecipitation strategy. Benefiting from inhibiting defects and low-strain sodium storage mechanism, as-obtained NiHCF–NCs exhibits superior electrochemical properties in terms of high capacity (81.3 mAh g−1), excellent rate capability (64.5 mAh g−1 at 4000 mA g−1), and outstanding cycle performance (97.1% capacity retention over 2000 cycles). Moreover, full-cell assembled with NiHCF–NCs cathode and NaTi 2 (PO 4) 3 @C anode presents competitive behaviors of good rate capability and ultra-long cycle lifespan over 5000 cycles, greatly promoting the development of SIBs in practical application. [Display omitted] • Na 2 DTPA-assisted coprecipitation method for high quality Na-rich PBA material. • Controlled crystallization process induces excellent sodium storage performance. • The low strain during charge/discharge process for high stability of PBA material. • The sodium-ion battery delivers outstanding cycle life over 5000 cycles. [ABSTRACT FROM AUTHOR]

In the context of low-carbon economy and sustainable development, industrial by-products are being gradually converted into green building materials. The effect of groundwater on the properties of modified desulfurization gypsum must be examined to increase its application in shotcrete supporting structures in underground engineering. In this study, triaxial compression tests with permeability measurements were carried out for modified desulfurization gypsum by simulating underground engineering conditions. The peak strength, permeability-deformation curves, and permeability-stress curves were obtained. The results showed that an increase in pore water pressure promoted internal crack propagation and enhanced the connectivity between cracks. This decreased the specimen strength and increased the initial permeability. As axial deformation and circumferential deformation increased, the variation in the permeability showed five stages: decline, gradual rise, rapid rise, rapid decline, and gradual decline. The permeability was more sensitive to circumferential deformation compared to axial deformation. The critical impermeability strength and abrupt permeability were defined according to the permeability-stress curves. These parameters can be used to evaluate the seepage problems in shotcrete supporting structures in underground engineering. [ABSTRACT FROM AUTHOR]

With the increased water content in heavy oil gathering pipelines and application of cold transportation methods, understanding adhesion behavior in heavy oil/water/pipeline wall systems has greatly gained in importance. Here, a combined experimental and molecular dynamics (MD) simulation was used to investigate the effect of the heavy oil composition and molecular structures on adhesion. The capacity of heavy oil adhesion and the effect of adding asphaltene molecules to the heavy oil were studied experimentally. MD simulation systems with different asphaltene concentrations were established based on the NPT and NVT ensembles. The results showed that the addition of asphaltene increases the adhesion of heavy oil by as much as 16.60–83.35%. The center of mass, mean square displacement, and radial distribution function of heavy oil droplets were also analyzed, which indicated that the viscosity and thickness of the heavy oil adhesion layer were also affected by the asphaltene content. The functional groups in asphaltene molecules promote the adhesion of oil droplets and inhibit the adhesion of the water phase. Further, asphaltene aggregates are formed by face-to-face stacking, which severely impedes heavy oil flow assurance. The results from this study greatly contribute to understanding the mechanisms of heavy oil adhesion during cold transportation. • Experiments of heavy oil with different asphaltene contents were implemented. • Designed MD simulations to study the heavy oil adhesion under cold transportation. • Effect of asphaltene molecules on the adhesion behaviors was investigated. • The interaction of resin and asphaltene molecules were summarized. • Clarified the adhesion mechanism of heavy oil cold transportation. [ABSTRACT FROM AUTHOR]

This article has been retracted. Please see the Retraction Notice for more detail: https://doi.org/10.1186/s12943-020-01206-5 [ABSTRACT FROM AUTHOR]

Highlights: [•] Enhancement of ATP supply by using xylose carbon source. [•] The high NAD(H) can improve the xylose consumption rate. [•] Fermentation of corn stalk hydrolysate to produce succinate was studied. [ABSTRACT FROM AUTHOR]

AFP111 is a spontaneous mutant of Escherichia coli with mutations in the glucose-specific phosphotransferase system, pyruvate formate lyase system, and fermentative lactate dehydrogenase system, created to reduce byproduct formation and increase succinic acid accumulation. In AFP111, conversion of xylose to succinic acid only generates 1.67 ATP per xylose, but requires 2.67 ATP for xylose metabolism. Therefore, the ATP produced is not adequate to accomplish the conversion of xylose to succinic acid in chemically defined medium. An E. coli mutant was obtained by atmospheric and room-temperature plasmas and metabolic evolution strategies, which had the ability to use xylose and improve the capacity of cell growth. The concentration of ATP in the mutant was 1.33-fold higher than that in AFP111 during xylose fermentation. In addition, under anaerobic fermentation with almost 80 % xylose from corn stalk hydrolysate, a succinic acid concentration of 21.1 g l was obtained, with a corresponding yield of 76 %. [ABSTRACT FROM AUTHOR]

Summary: The hallmark of a virus is its capsid, which harbors the viral genome and is formed from protein subunits, which assemble following precise geometric rules. dsRNA viruses use an unusual protein multiplicity (120 copies) to form their closed capsids. We have determined the atomic structure of the capsid protein (P1) from the dsRNA cystovirus Φ8. In the crystal P1 forms pentamers, very similar in shape to facets of empty procapsids, suggesting an unexpected assembly pathway that proceeds via a pentameric intermediate. Unlike the elongated proteins used by dsRNA mammalian reoviruses, P1 has a compact trapezoid-like shape and a distinct arrangement in the shell, with two near-identical conformers in nonequivalent structural environments. Nevertheless, structural similarity with the analogous protein from the mammalian viruses suggests a common ancestor. The unusual shape of the molecule may facilitate dramatic capsid expansion during phage maturation, allowing P1 to switch interaction interfaces to provide capsid plasticity. [ABSTRACT FROM AUTHOR]

After the investigations of experiments and Derjaguin-Landau-Verwey-Overbeek (DLVO) theory, the adhesion energy model was proposed to solve the discrimination of the minimum oil-gathering temperature of transportation (adhesion temperature, AT). The results of AT were in good agreement with the experimental results (error values around 0.1 °C–1.2 °C). And a 100-day cooling transportation test was conducted safely, indicating that the model was suitable for engineering application. It was found that the oil droplets were adhered to the initial adhesion layer on the pipeline wall by the dominant contribution of van der Waals (VDW) energy. In contrast, the electric double layer (EDL) energy can resist the coalescence between oil droplets and the initial adhesion layer. And the effects of different temperatures, oil droplet particle sizes, and salinity on the DLVO interaction energy were also analyzed. Furthermore, the effect of DLVO energy on the adhesion of heavy oil was obtained by combining the relationship between adhesion mass and AT. [Display omitted] • An adhesion energy model of heavy oil was proposed based on DLVO theory. • A cold transportation test for 100 days was conducted using adhesion temperature. • VDW interaction can promote adhesion, while EDL interaction can resist adhesion. • Temperature, salinity, and droplet size can affect VDW and EDL interactions. [ABSTRACT FROM AUTHOR]

Developing catalysts with high activity, durability, and water resistance for ozone decomposition is crucial to regulate the pollution of ozone in the troposphere, especially in indoor air. To overcome the shortcomings of metal oxide catalysts with respect to their durability and water resistance, Fe-Co double-atom catalyst (DAC) is proposed as a novel catalyst for ozone decomposition. Here, through a systematic study using density functional theory (DFT) calculations and microkinetic modeling, the adsorption and catalytic decomposition of O 3 on Fe-Co DAC have been examined based on adsorption configuration, orbital hybridization, and electron transfer. Based on Eley-Rideal (E-R) and Langmuir-Hinshelwood (L-H) reaction mechanisms, the mechanisms of ozone decomposition on Fe-Co DAC were explored by analyzing reaction paths and energy variations. To confirm the water-resistant of Fe-Co DAC, competitive adsorption behavior between O 3 and dominant environmental gases was discussed through ab initio molecular dynamic (AIMD) simulation. The dominant reaction mechanism of ozone decomposition is L-H and the rate-determining step is the desorption of the first oxygen molecule from the surface of Fe-Co DAC which has an energy barrier of 0.78 eV. Due to this relatively low energy barrier and high turnover frequency (TOF), the optimal operation window of catalytic O 3 decomposition on Fe-Co DAC is <500 K suggesting that catalytic decomposition of O 3 on Fe-Co DAC can occur at room temperature. This theoretical study provides new insights for designing novel catalysts for ozone decomposition and fundamental guidance for subsequent experimental research. [Display omitted] • A novel Fe-Co double-atoms catalyst for O 3 decomposition. • Fe-Co DACs with high low-temperature activity and strong water-resistant. • Reaction mechanism in atomic level and microkinetic modeling. [ABSTRACT FROM AUTHOR]

• The effect of early-age loading on the mechanical properties of concrete is related to meso-structure. • The mechanical properties of concrete deteriorate with the increase of early-age loading. • The pore structure characteristics of concrete were obtained by nuclear magnetic resonance. • A constitutive behavior which can reflect the initial compaction stage is established. To explore the influence of early-age loading on the mechanical properties and internal structures of concrete, loads equivalent to 10%, 25%, and 40% of the concrete current compressive strength were applied to 1 day and 3 days specimens. The results of mechanical properties and mesoscopic scanning tests show that the development of uniaxial compression damage of concrete affected by early-age loading is divided into three stages. With an increase in early-age loading, the elastic modulus decreased and the Poisson's ratio first increased and then decreased. When the loading was 10% of current compressive strength of specimens, the number of macropores and cracks would decrease, and the subsequent mechanical properties of concrete would not be affected considerably. A continuous increase in early-age loading, the proportion of mesopores and cracks increased considerably, the cementitious structure loosened, and the mechanical properties of concrete deteriorated in the subsequent stage. By analyzing the relationship between the total deformation and the deformation of primary flaws and skeleton, the concept of void strain ratio was proposed. Accordingly, a constitutive behavior that reflects the nonlinear characteristic of primary flaws compaction stage during uniaxial compression process was established, the theoretical calculation is in good agreement with the experimental results. [ABSTRACT FROM AUTHOR]

After surface adhesion apparatus (SAA) experiments, the mass of oil sticking to wall was found to increase slightly in high-temperature region (70-60 °C), while this mass was increased immediately in low-temperature region (35-25 °C). The contact angle and interfacial tension (IFT) of oil droplets were measured, and the work of adhesion and cohesion were cauculated, indicating that the process of oil sticking to pipeline wall includes the adhesion region and cohesion region. However, the work of adhesion does not change with temperature, but the work of cohesion is positively correlated with temperature. Consisting with this, the Results of the work of adhesion and cohesion using molecular simulation (MD) are the same with experiments and the van der Waals (VDW) interaction of polar substances is the main drive force of adhesion. The polar molecules on iron surface are aggregated at 0.5–2.0 nm along the X and Y directions and close to the iron surface at 0.5–1.0 nm along the Z direction. The polar substances in heavy oil are located on the near-iron plate side and the heteroatoms (i.e., N and S) formed adhesive joints in the processes of oil sticking to wall, especially N element. [Display omitted] • A new method for predicting the wall sticking occurrence temperature of heavy oil. • Processes of wall sticking of heavy oil include the adhesion and cohesion region. • The N and S atoms are the bonding joints between heavy oil and pipe wall. [ABSTRACT FROM AUTHOR]

Herein, further SAR studies of lead compound NSC746457 (Shen, J.; Woodward, R.; Kedenburg, J. P.; Liu, X. W.; Chen, M.; Fang, L. Y.; Sun; D. X.; Wang. P. G. J. Med. Chem. 2008 , 51 , 7417 − 7427) were performed, including the replacement of the trans-styryl moiety with a 2-substituted benzo-hetero aromatic ring and the introduction of a substituent onto the central methylene carbon. A promising chiral lead, S-(E)-3-(1-(1-(benzo[d]oxazol-2-yl)-2-methylpropyl)-1H-1,2,3-triazol-4-yl)-N-hydroxyacrylamide (12, NK-HDAC-1), was discovered and showed about 1 order of magnitude more potency than SAHA in both enzymatic and cellular assays. For the in vitro safety tests, NK-HDAC-1 was far less toxic to nontransformed cells than tumor cells and showed no significant inhibition activity against CYP-3A4. The pharmaceutical properties (LogD, solubility, liver micrsomal stability (t1/2), plasma stability (t1/2), and apparent permeability) strongly suggested that NK-HDAC-1 might be superior to SAHA in bioavailability and in vivo half-life. [ABSTRACT FROM AUTHOR]

The camptothecins, which target the intranuclear enzyme topoisomerase I, have advanced to the forefront of several areas of developmental chemotherapy of cancers. In the present study, we investigated the potential anti-human ovarian cancer effects of NSC606985, a novel and rarely studied camptothecin analog, and its combination with cisplatin (CDDP). Human ovarian cancer cell line COC1 cells were treated with different nanomolar of NSC606985 with or without CDDP, and cell growth and apoptosis were evaluated, respectively, by MTT assay and annexin-V assay on flow cytometry. Chou-Talalay analysis was used to evaluate combined effect of NSC606985 and CDDP. Western blot was used to detect protein kinase Cdelta (PKCdelta), caspase-3 and hypoxia-inducible factor-1alpha (HIF-1alpha) proteins. Our results showed that NSC606985 at nanomolar concentration induced apoptosis with the activation of PKCdelta in COC1 cells. Especially, NSC606985 presented the significant combined effects on COC1 cells in terms of growth inhibition and apoptosis induction. In addition, NSC606985 significantly antagonized the accumulation of HIF-1alpha stabilized by hypoxia or hypoxia-mimetic agent. These results suggest that NSC606985 and its combination with CDDP present the therapeutic potential on ovarian cancer, and deserve further preclinical and clinical studies. [ABSTRACT FROM AUTHOR]

• Proposed integrated flood risk identification, analysis, and diagnosis framework. • Characterized spatial-temporal dependent forecast uncertainties by Copula function. • Discovered the underestimation of risk when neglecting spatial-temporal dependences. • Constructed scenario-based risk diagnosis model to examine causes of risk. Uncertainties in flood forecasts that result from error propagation in meteorological–hydrological simulation processes present spatial and temporal dependences that are the principal sources of risk to real-time flood control in a multireservoir system. Risk analysis models that neglect such dependences potentially yield biased results regarding flood control operations. To enhance the accuracy of flood risk analysis and inform decision making regarding real-time flood control for a multireservoir system, this study proposed an integrated flood risk identification, analysis, and diagnosis model framework that incorporates the multidimensional dependences of forecast uncertainties. The framework includes an uncertainty identification model that uses the copula function to characterize the joint probability function of the mixed dependent uncertainties. It also incorporates a real-time flood risk analysis module that couples simulation and optimization to convert the complex multiobjective operation under uncertainty into a tractable model capable of flexibly evaluating individual and joint flood risks. The third component is a risk diagnosis module that calculates risk contributions using conditional probability, and identifies stable and vulnerable reservoirs within the system to alter operational decisions toward risk reduction. Methodologies were verified through application to a mixed four-reservoir system in the Pi River Basin, China. The principal findings were as follows. (1) Positive-dominated dependences of forecast uncertainties were identified because of error propagation through the meteorological and rainfall–runoff forecasts within the spatial and temporal continuity connection, and the copula function accurately described and quantified the multidimensional temporal and spatial dependences of the uncertainties. (2) In neglecting the spatial dependences of forecast uncertainties, the joint flood risk of the reservoir system was underestimated; in ignoring high-order temporal dependences, individual flood risk was underestimated owing to biased estimation in error variance. (3) Systematic reorganization of the operational strategies of diagnosed stable and vulnerable reservoirs could provide guidance for reduction and homogenization of flood risks. The proposed framework could be used to improve the accuracy of flood risk analysis and support reliable real-time flood control operation of a multireservoir system. [ABSTRACT FROM AUTHOR]

• Tilted-CAIPI PSF-EPI enables practical scan for sagittal spinal cord DTI. • Highly accelerated PSF-EPI maintains anatomical fidelity even with metal implants. • Water/fat separation using the intrinsic signals of PSF-EPI is effective. • The axial DTI metrics from PSF-EPI are similar to those using ZOOM-EPI. Diffusion tensor imaging (DTI) of the spinal cord is technically challenging due to the size of its structure and susceptibility-induced field inhomogeneity, which impedes clinical applications. This study aimed to achieve high-fidelity spinal cord DTI with reasonable SNR and practical acquisition efficiency. Particularly, a distortion-free multi-shot EPI technique, namely point-spread-function encoded EPI (PSF-EPI), was adopted for diffusion imaging of the cervical spinal cord (CSC). The shot number can be reduced to six for sagittal scans through titled-CAIPI acceleration and partial Fourier undersampling, consequently rendering this technique beneficial in clinics. Fifteen healthy volunteers and seven patients with metallic implants underwent sagittal scans using tilted-CAIPI PSF-EPI at 3T. Unsuppressed fat signals were further removed by retrospective water/fat separation using the intrinsic chemical-shift encoded signals. Compared with multi-shot interleaved EPI method, highly accelerated PSF-EPI method provided evidently improved distortion reduction and higher consistency with anatomical references even with metallic implants. Additionally, axial DTI scans using PSF-EPI were also evaluated quantitatively, and the measured DTI metrics are similar to those obtained from the zonal oblique multi-slice EPI (ZOOM-EPI) method and reported values. The high anatomical consistency, practical scan time and quantitative reliability indicate PSF-EPI's clinical potential for CSC diffusion imaging. [ABSTRACT FROM AUTHOR]

• The video-based multi-view two-dimensional echocardiograms analysis framework. • Automatically organize the five views and diagnose the congenital heart disease. • Powerful baselines to explore the key-frame-based and video-based multi-view diagnose. • A depthwise separable convolution-based efficient multi-channel CNN architecture. • Four video aggregation schemes are developed to process video frames. Congenital heart disease (CHD) is the most common birth defect and the leading cause of neonate death in China. Clinical diagnosis can be based on the selected 2D key-frames from five views. Limited by the availability of multi-view data, most methods have to rely on the insufficient single view analysis. This study proposes to automatically analyze the multi-view echocardiograms with a practical end-to-end framework. We collect the five-view echocardiograms video records of 1308 subjects (including normal controls, ventricular septal defect (VSD) patients and atrial septal defect (ASD) patients) with both disease labels and standard-view key-frame labels. Depthwise separable convolution-based multi-channel networks are adopted to largely reduce the network parameters. We also approach the imbalanced class problem by augmenting the positive training samples. Our 2D key-frame model can diagnose CHD or negative samples with an accuracy of 95.4%, and in negative, VSD or ASD classification with an accuracy of 92.3%. To further alleviate the work of key-frame selection in real-world implementation, we propose an adaptive soft attention scheme to directly explore the raw video data. Four kinds of neural aggregation methods are systematically investigated to fuse the information of an arbitrary number of frames in a video. Moreover, with a view detection module, the system can work without the view records. Our video-based model can diagnose with an accuracy of 93.9% (binary classification), and 92.1% (3-class classification) in a collected 2D video testing set, which does not need key-frame selection and view annotation in testing. The detailed ablation study and the interpretability analysis are provided. The presented model has high diagnostic rates for VSD and ASD that can be potentially applied to the clinical practice in the future. The short-term automated machine learning process can partially replace and promote the long-term professional training of primary doctors, improving the primary diagnosis rate of CHD in China, and laying the foundation for early diagnosis and timely treatment of children with CHD. [ABSTRACT FROM AUTHOR]

Most heavy metal exposure and pollution results from multiple industrial activities, including metal processing in refineries, and microelectronics. These issues pose a great threat to human health, ecological balance, and even societal stability. During 2012–2017, China, in particular, faced the challenge of 23 heavy metals accidents, six of which were extraordinarily serious accidents. Accidental environmental pollution is rarely caused by a single heavy metal, but rather by heavy metal mixtures. To address the need for a joint exposure risk assessment for heavy metal mixed pollution accidents at the watershed scale, a Copula-based exposure risk dynamic simulation model was proposed. A coupled hydrodynamic and accidental heavy metal exposure model is constructed for an hourly simulation of the exposure fate of heavy metals from each risk source once accidental leakage has occurred. The Copula analysis was introduced to calculate the dual heavy metal joint exposure probability in real time. This method was applied to an acute Cr6+-Hg2+ joint exposure risk assessment for 43 electroplating plants in nine sub-watersheds within the Dongjiang River downstream basin. The results indicated seven risk sources (i.e., S1, S4, H18, H23, H27–H28, and H34) that presented relatively high exposure risk to their surrounding sub-watersheds. Spatially, the acute exposure risk level was highest in the tributary basin (sub-watershed XW) than in the mainstream (sub-watershed DW2) and the river network (sub-watershed RW) of the lower reaches of the Dongjiang River. This research highlights an effective probabilistic approach for performing a joint exposure risk analysis of heavy metal mixed pollution accidents at the watershed scale. • A Copula-based exposure risk dynamic simulation model is proposed. • Dual heavy metal join exposure probabilities can be estimated in real time using Copula analysis. • Acute Cr6+-Hg2+ exposure risk level of the tributary is the highest in the Dongjiang River downstream watershed. • This method proves to be useful for the water pollution exposure risk control and management. [ABSTRACT FROM AUTHOR]