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Proton exchange membrane fuel cells (PEMFCs) possess high energy and low power densities, while supercapacitors are characterized by high power and low energy densities. A hybrid PEMFC/supercapacitor device (HPSD) with high energy and power densities was proposed and fabricated for the first time using a reduced graphene oxide/Nafion/Pt electrode in this study. The reduced graphene oxide (rGO) was a capacitive material, and Pt was used as the electrocatalyst. Nafion ionomers adsorbed onto the rGO sheets surface and connected the rGO sheets and the electrolyte (Nafion membrane), thus increasing the utilization rate and specific capacitance of rGO. During the half-cell tests, the rGO/Nafion/Pt electrode exhibited better pulse discharge and galvanostatic discharge performance than the conventional Nafion/Pt electrode. Due to the unique synergy of electrochemical reaction current and capacitance current during the discharge process, the HPSD exhibited a higher power density (26.2 kW kg−1) than the PEMFC (23.9 kW kg−1). The energy density (12.7 kWh kg−1) exhibited by HPSD was close to that of the PEMFC (13.5 kWh kg−1). Therefore, the concept of HPSD is to create a new method for developing next-generation electrochemical devices with high energy and power densities. • A hybrid PEMFC/supercapacitor device (HPSD) was proposed and fabricated. • The HPSD possesses high energy (12.7 kWh kg−1) and power densities (26.2 kW kg−1). • The reduced graphene oxide/Nafion/Pt electrode was used to fabricated the HPSD. • Reduced graphene oxide (rGO) was capacitive material, and Pt was electrocatalyst. • Nafion ionomers could connect the rGO sheets and the electrolyte (Nafion membrane). [ABSTRACT FROM AUTHOR]

We present an efficient second- or fourth-order finite difference direct numerical simulation (DNS) solver using pencil-like domain decomposition parallel strategy, with the ability to handle different boundary conditions. The viscous term is treated implicitly, partial implicitly, or explicitly. The runtimes for different viscous treatments and different boundary conditions are evaluated quantitatively, which can help us to get a fast computational speed for specific flow cases. FFT-based method is used for solving Pressure Poisson equation, and alternating direction implicit approach is adopted for Helmholtz equations during the implicit viscous treatment. The numerical results achieve good match with those obtained from spectral methods. In addition, the resulting solver exhibits quite good parallel efficiency, and demonstrates good computational speedup and versatility than other pencil-like DNS solvers reported in the literature. The source code is freely available at https://github.com/GongZheng-Justin/Channel3d. [ABSTRACT FROM AUTHOR]

Polyaniline (PANI) has long been explored as a promising organic cathode for Li-ion batteries. However, its poor electrochemical utilization and cycling instability cast doubt on its potential for practical applications. In this work, we revisit the electrochemical performance of PANI in nonaqueous electrolytes, and reveal an unprecedented reversible capacity of 197.2 mAh g−1 (244.8 F g−1) when cycled in a wide potential range of 1.5 to 4.4 V vs. Li+/Li. This ultra-high capacity derives from 70% -NH- transformed to =NH+- during deep charging/discharging process. This material also demonstrates a high average coulombic efficiency of 98%, an excellent rate performance with 73.5 mAh g−1 at 1800 mA g−1, and retains 76% of initial value after 100 cycles, which are among the best reported values for PANI electrodes in battery applications. [ABSTRACT FROM AUTHOR]

Traditional dense microporous layers (MPLs) are suitable for low-temperature proton exchange membrane fuel cells (PEMFCs), but they greatly hinder mass transport in high-temperature PEMFCs. Here, we report a novel cathode MPL based on reticulated polyaniline nanowires that were grown on carbon paper via in-situ electropolymerization. The maximum power density of the high-temperature PEMFC based on the new MPL was 476 mW/cm2, which was 36% higher than that based on a conventional MPL. Oxygen gain tests and electrochemical impedance spectroscopy showed that the new MPL accelerated oxygen transfer due to its unique pore size distribution, which ultimately improved the performance of the HT-PEMFC. Image 1 • Reticulated polyaniline nanowires are used as a new microporous layer (MPL). • The novel MPL accelerates oxygen transfer due to its unique pore size distribution. • The peak power density of HT-PEMFC based on the new MPL is 476 mW/cm2. • The peak power density of HT-PEMFC based on traditional MPL is 350 mW/cm2. • The performance improvement of HT-PEMFC is evidenced by EIS and oxygen gain tests. [ABSTRACT FROM AUTHOR]

Summary: Microporous layers (MPLs) have a crucial effect on the performance of direct methanol fuel cells (DMFCs). High polytetrafluoroethylene (PTFE) loading is normally adopted to remove water in a conventional cathode MPL based on carbon black, which hinders oxygen transport and increases ohmic resistance. In this study, we report a novel cathode MPL based on polypyrrole nanowires, which were grown on hydrophobic carbon paper via in situ electropolymerization. Compared with carbon black, the unique structure of polypyrrole nanowires allows for less PTFE content to obtain similar hydrophobicity. The maximum power density of a DMFC based on the novel MPL (20 wt% PTFE) is 101.1 mW cm−2, which is about 1.3 times that based on a traditional MPL (40 wt% PTFE, 79.4 mW cm−2). This improvement can be ascribed to increased oxygen transfer and decreased ohmic resistance, which were evidenced by oxygen gain and electrochemical impedance spectroscopy. [ABSTRACT FROM AUTHOR]

[Display omitted] • Nafion doped polyaniline/graphene oxide composites are synthesized for the first time and used as the electrode materials of supercapacitors. • Polyaniline utilization rate and electrochemical surface area are improved by Nafion doping in the Nafion membrane-based supercapacitors. • Graphene oxide can enhance the electrochemical stability of polyaniline in the Nafion doped polyaniline/graphene oxide composites. • Flexible supercapacitor shows 300F g−1 at bent condition, which is the maximum value among reported Nafion membrane-based supercapacitors. • After 1000 cycles, the capacitance retention rate of the composites is 83.0%, which is higher than that of Nafion doped polyaniline (72.1%). Nafion membrane possesses good ionic conductivity and excellent mechanical stability, which can be used as electrolyte and separator of flexible supercapacitor. However, due to its solid-state structure, it is difficult for the Nafion membrane to permeate in solid-state electrode, which reduces electrochemical surface area, and increases interface resistance. The electrode materials need to be carefully designed to solve the above issues. In this study, Nafion doped polyaniline/graphene oxide composites were designed and synthesized as electrode materials to fabricate flexible supercapacitors based on Nafion membrane. The polyaniline utilization rate and the electrochemical surface area are improved by Nafion doping. In addition, the electrostatic interaction between polyaniline and Nafion can reduce the interface resistance. Graphene oxide can enhance the polyaniline electrochemical stability. The specific capacitances of flexible supercapacitor are 309 and 300F g−1 under flat and bent conditions (at 1 A/g), respectively, which are the maximum values among reported Nafion membrane-based supercapacitors. After 1000 cycles, the capacitance retention rate of supercapacitor with Nafion membrane is 87.2%, which is higher than that with H 2 SO 4 electrolyte (83.0%). Therefore, the Nafion membrane-based flexible supercapacitor has widespread applications in electronic products because of its high performance and good cycling stability. [ABSTRACT FROM AUTHOR]

After fertilization, mouse embryos go through preimplantation development to give rise to blastocyst. Two key molecular events, zygotic genome activation (ZGA) and the first cell lineage specification, are essential for the process. Recent advances in low-input epigenomics profiling techniques allow the analysis of these events at a molecular level, which revealed a critical role of epigenetic and chromatin reprogramming in ZGA and the first cell lineage specification. Additionally, the establishment of an in vitro embryonic stem cell (ESC) to two-cell embryo-like conversion system have also contributed to the molecular understanding of preimplantation development. In this review, we summarize recent advances in epigenetic regulation of mouse preimplantation development, point out the remaining questions, and propose strategies to tackle these questions. [ABSTRACT FROM AUTHOR]

• Contaminant concentration distribution uncertainties are studied. • Additional longitudinal displacement is a key indicator. • Concentration distribution is affected by the lateral position of initial release. Solute transport in wetland flows is an important process to understand for agricultural practices, providing essential information to assist in decision making and regulation for both cases of agricultural water contamination and agricultural pollution. Recent study has suggested that in the application of the one-dimensional Taylor dispersion model for solute concentration distribution in wetlands, uncertainties can arise even when contaminants are initially released at the same streamwise location. In this paper, we present an analytical study of instantaneous point-source release of solute in a wetland flow dominated by bank wall effects. The movement of the solute centroid and the long-term asymptotic Taylor dispersion coefficient are determined by the Aris concentration moment method, which are required for quantifying the streamwise distribution of the mean concentration and the transverse concentration distribution profiles. It is shown that the additional longitudinal displacement serves as a key indicator revealing the uncertainties of concentration distribution caused by different lateral positions of the contaminant release. More indicators including the lateral concentration distribution and the relative difference of the concentration are analyzed in detail. With given physical parameters, simple applications are provided to illustrate the streamwise transport of the solute plume centroid and the evolution of the additional longitudinal displacement affected by the bank wall effects. [ABSTRACT FROM AUTHOR]

This study aimed to develop novel temperature-sensitive liposomes loading paclitaxel (PTX-TSL) and evaluate them in vitro to improve the delivery efficiency and targeting of PTX. K237 peptide was conjugated to the terminal NHS of 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[hydroxyl succinimidyl (polyethylene glycol)-(DSPE-PEG-NHS), and K237-modified PTX-TSL (K237-PTX-TSL) was prepared using a film dispersion method. K237-TSL encapsulation with calcein was synthesized and used to determine the cellular uptake of TSL. The morphology of K237-PTX-TSL was observed using a transmission electron microscope. The particle size and potential were measured using a laser particle size analyzer. The phase transition temperature was detected using the differential scanning calorimetry. The Cell Counting Kit-8 assay and flow cytometry were used to evaluate the effects of K237-PTX-TSL on the proliferation and cell cycle of cell lines SKOV-3 and human umbilical vein endothelial cell (HUVEC). The encapsulation efficiency of K237-PTX-TSL was 94.23% ± 0.76%. The particle diameter was 88.3 ± 4.7 nm. K237-PTX-TSL showed a fast release profile at 42 °C, while it was stable at 37 °C. PTX-TSL combined with hyperthermia significantly inhibited the cell proliferation of SKOV-3 cells and HUVECs due to increased cell arrest in the G2/M phase. The half-minimal inhibitory concentration value of K237-PTX-TSL on SKOV-3 cells and HUVECs was 13.61 ± 1.81 and 5.54 ± 0.95 nmol/L, respectively, which were significantly lower than those with PTX-TSL (p < 0.01). K237 modification could increase the targeting efficiency of TSL to cancer cells and vascular endothelial cells, thus resulting in higher cytotoxicities compared with PTX-TSL, which might be a potential formulation for targeting cancer therapy. [ABSTRACT FROM AUTHOR]

This work elucidated the intrinsic mechanism underlying the influence of K 2 HPO 4 on PSA production and molecular weight (MW) stability. Among the different potassium salts mixed with K 2 HPO 4 in the initial medium, those with buffering capacity were favorable for PSA production. In the bioreactor culture with pH control, adding an appropriate concentration of K 2 HPO 4 could enhance PSA production. A dual-phase pH control strategy with ammonia water and KOH could also increase the yield and maintain the MW stability of PSA. Zeta potential test, UV/circular dichroism spectra, and transmission electric microscopy were utilized to explore the configuration of K 2 HPO 4 –PSA complex. The results from this study can serve a good basis for the industrial-scale production of PSA with stable MW. [ABSTRACT FROM AUTHOR]

Catalyst layers (CLs) with spatially ordered structure can improve mass transport of reactants/products, which is essential for the high performance of polymer electrolyte membrane fuel cells (PEMFCs). In this study, aligned polyaniline (PANI) nanorods grown on gas diffusion layers by in situ polymerization are used as supports for platinum to fabricate ordered CLs. The length and diameter of the PANI nanorods can be controlled by optimizing the reaction temperatures or the aniline concentrations during the in situ polymerization process. With the optimized aligned PANI nanorods as supports of cathode, the mass specific power density of the PEMFC reaches 2.5 kW g Pt −1 , which is 21% higher than that of the conventional PEMFC without PANI. This improvement can be attributed to the reduced oxygen transport resistance revealed by oxygen gain and electrochemical impedance spectroscopy. [ABSTRACT FROM AUTHOR]

Summary When there is a sudden and uniform release of contaminant over the depth of wetland, the centroid of resulted solute cloud will travel downstream at the cross-sectional mean velocity of the flow. However, if the initial release is not uniform, there will be an additional longitudinal displacement of the centroid, which is important for predicting the concentration distribution but cannot be revealed by the classical one-dimensional Taylor dispersion model. For the most typical case of an initial point source release at the free-water-surface of the wetland, an idealized case modeling accidental leakage of toxic chemicals in waters, in the present paper we analytically deduce the longitudinal displacement by the method of concentration moment. The result is then incorporated in the analytical solutions of concentration distribution, which are further verified by our numerical simulations. The effects of the longitudinal displacement on the concentration distribution are analyzed in detail. It is shown that without considering the displacement, for vertical planes close to the edges of the contaminant cloud, the analytical solution can over- or under-estimate the vertical distribution of concentration for over 20% of the maximum concentration in the plane even at a large dimensionless time of t ∗ = 5 . The longitudinal displacement is shown to decrease with the increase of the important damping factor α , which characterizes the effects of vegetation in wetlands. A simple application is given at the end of this paper to illustrate the evolution of the additional longitudinal displacement. [ABSTRACT FROM AUTHOR]

Understanding solute transport process is of fundamental significance for industrial and natural processes such as mixing and separation. Since detailed information for the transverse concentration distribution is required for associated applications, compared with the sole consideration of the cross-sectional mean concentration in previous studies, the present paper analytically explores the complete spatial concentration distribution in packed tube flow by the proposed two-scale perturbation analysis (Z. Wu, G.Q. Chen, Journal of Fluid Mechanics, 740 (2014) 196–213.). With modification on the zeroth-order concentration up to the first-order, the deduced analytical solution gives a good prediction for the longitudinal distribution of mean concentration as well as the transverse distribution, according to comparisons with new results of numerical simulation. Importantly we show in the paper that instead of being uniformly distributed in the cross-section as expected in traditional view, the transverse concentration is highly non-uniform when Taylor dispersion model is applicable. Representing the complicated flow conditions for packed tube flow, the unique dimensionless parameter as a damping factor affects the complete spatial concentration distribution in two ways: cause the contraction of the solute concentration cloud, and the flattening of the concentration contours. [ABSTRACT FROM AUTHOR]

Summary Study on contaminant transport in wetland flows is of fundamental importance. Recent investigation on scalar transport in laminar tube flows (Wu and Chen, 2014. J. Fluid Mech., 740: 196-213.) indicates that the vertical concentration difference in wetland flows may be remarkable for a very long time, which cannot be captured by the extensively applied one-dimensional Taylor dispersion model. To understand detailed information for the vertical distribution of contaminant in wetland flows, for the first time, the present paper deduces an analytical solution for the multi-dimensional concentration distribution by the method of mean concentration expansion. The solution is verified by both our analytical and numerical results. Representing the effects of vegetation in wetlands, the unique dimensionless parameter α can cause the longitudinal contraction of the contaminant cloud and the change of the shape of the concentration contours. By these complicated effects, it is shown unexpectedly that the maximum vertical concentration difference remains nearly unaffected, although its longitudinal position may change. Thus the slow-decaying transient effect (Wu and Chen, 2014. J. Hydrol., 519: 1974-1984.) is shown also apply to the process of contaminant transport in wetland flows. [ABSTRACT FROM AUTHOR]

Diabetes is the most common and complex metabolic disorder, and one of the most important health threats now. MicroRNAs (miRNAs) are a group of small non-coding RNAs that have been suggested to play a vital role in a variety of physiological processes, including glucose homeostasis. In this study, we investigated the role of miR-185 in diabetes. MiR-185 was significantly downregulated in diabetic patients and mice, and the low level was correlated to blood glucose concentration. Overexpression of miR-185 enhanced insulin secretion of pancreatic β-cells, promoted cell proliferation and protected cells from apoptosis. Further experiments using in silico prediction, luciferase reporter assay and western blot assay demonstrated that miR-185 directly targeted SOCS3 by binding to its 3’-UTR. On the contrary to miR-185’s protective effects, SOCS3 significantly suppressed functions of β-cell and inactivated Stat3 pathway. When treating cells with miR-185 mimics in combination with SOCS3 overexpression plasmid, the inhibitory effects of SOCS3 were reversed. While combined treatment of miR-185 mimics and SOCS3 siRNA induced synergistically promotive effects compared to either miR-185 mimics or SOCS3 siRNA treatment alone. Moreover, we observed that miR-185 level was inversely correlated with SOCS3 expression in diabetes patients. In conclusion, this study revealed a functional and mechanistic link between miR-185 and SOCS3 in the pathogenesis of diabetes. MiR-185 plays an important role in the regulation of insulin secretion and β-cell growth in diabetes. Restoration of miR-185 expression may serve a potentially promising and efficient therapeutic approach for diabetes. [ABSTRACT FROM AUTHOR]

This paper develops an algorithm for computing spatially-distributed monthly potential evaporation (PE) over a mountainous region, the Lhasa River basin in China. To develop the algorithm, first, correlation analysis of different meteorological variables was conducted. It was observed that PE is significantly correlated with vapour pressure and temperature differences between the land surface and the atmosphere. Second, the Dalton model, which was developed based on the mass transfer mechanism, was modified by including the influence of the related meteorological variables. Third, the influence of elevation on monthly temperature, vapour pressure and wind velocity was analysed, and functions for extending these meteorological variables to any given altitude were developed. Fourth, the inverse distance weighting method was applied to integrate the extended meteorological variables from five stations adjacent to and within the Lhasa River basin. Finally, using the modified Dalton model and the integrated meteorological variables, we computed the spatially-distributed monthly PE. This study indicated that spatially-distributed PE can be obtained using data from sparse meteorological stations, even if only one station is available; the results show that in the Lhasa River basin PE decreases when elevation increases. The new algorithm, including the modified model and the method for spatially extending meteorological variables can provide the basic inputs for distributed hydrological models. Editor Z.W. Kundzewicz [ABSTRACT FROM AUTHOR]

Metabolism and ageing are intimately linked. Compared with ad libitum feeding, dietary restriction consistently extends lifespan and delays age-related diseases in evolutionarily diverse organisms. Similar conditions of nutrient limitation and genetic or pharmacological perturbations of nutrient or energy metabolism also have longevity benefits. Recently, several metabolites have been identified that modulate ageing; however, the molecular mechanisms underlying this are largely undefined. Here we show that ?-ketoglutarate (?-KG), a tricarboxylic acid cycle intermediate, extends the lifespan of adult Caenorhabditis elegans. ATP synthase subunit ? is identified as a novel binding protein of ?-KG using a small-molecule target identification strategy termed drug affinity responsive target stability (DARTS). The ATP synthase, also known as complex V of the mitochondrial electron transport chain, is the main cellular energy-generating machinery and is highly conserved throughout evolution. Although complete loss of mitochondrial function is detrimental, partial suppression of the electron transport chain has been shown to extend C. elegans lifespan. We show that ?-KG inhibits ATP synthase and, similar to ATP synthase knockdown, inhibition by ?-KG leads to reduced ATP content, decreased oxygen consumption, and increased autophagy in both C. elegans and mammalian cells. We provide evidence that the lifespan increase by ?-KG requires ATP synthase subunit ? and is dependent on target of rapamycin (TOR) downstream. Endogenous ?-KG levels are increased on starvation and ?-KG does not extend the lifespan of dietary-restricted animals, indicating that ?-KG is a key metabolite that mediates longevity by dietary restriction. Our analyses uncover new molecular links between a common metabolite, a universal cellular energy generator and dietary restriction in the regulation of organismal lifespan, thus suggesting new strategies for the prevention and treatment of ageing and age-related diseases. [ABSTRACT FROM AUTHOR]

Pidotimod is a synthetic dipeptide with biological and immunological activity in innate immune responses. It has been reported that pidotimod could promote functional maturation of dendritic cells, but little is known about the regulation of macrophages. Recent studies have demonstrated that M1 or M2 polarized macrophages are of great importance for responses to microorganism infection or host mediators. The aim of this study was to determine the effectiveness of pidotimod on mouse bone marrow-derived macrophage polarization and its function. The results showed that pidotimod had no influence on M1-polarized macrophage. While interestingly, a significant increase of M2 marker gene expression (Arg1, Fizz1, Ym1, MR) was observed ( p < 0.01) in IL-4-induced M2 macrophage treated with pidotimod. In addition, cell surface expression of mannose receptor was dramatically enhanced using fluorescence activated cell sorter (FACS) analysis. Furthermore, the function of M2 macrophage was also determinated. The results showed that the supernatant of pidotimod-treated M2 macrophage could increase the migration ( p < 0.05) and enhance the wound closure rate ( p < 0.05) of MLE-12 cells. Collectively, it could be concluded that pidotimod significantly facilitated IL-4-induced M2 macrophage polarization and improves its function. [ABSTRACT FROM AUTHOR]

Abstract: The distributed basin model (DBM) has become one of the most effective tools in river basin studies. In order to overcome the efficiency bottleneck of DBM, an effective parallel-computing method, named temporal-spatial discretization method (TSDM), is proposed. In space, TSDM adopts the sub-basin partitioning manner to the river basin. Compared to the existing sub-basin-based parallel methods, more computable units can be supplied, organized and dispatched using TSDM. Through the characteristic of the temporal-spatial dual discretization, TSDM is capable of exploiting the river-basin parallelization degree to the maximum extent and obtaining higher computing performance. A mathematical formula assessing the maximum speedup ratio (MSR) of TSDM is provided as well. TSDM is independent of the implementation of any physical models and is preliminarily tested in the Lhasa River basin with 1-year rainfall-runoff process simulated. The MSR acquired in the existing traditional way is 7.98. Comparatively, the MSR using TSDM equals to 15.04 under the present limited computing resources, which appears to still have potential to keep increasing. The final results demonstrate the effectiveness and applicability of TSDM. [Copyright &y& Elsevier]

Abstract: River coding method for drainage networks plays an very important role in the physical simulation of river basins. In this study we developed a new river coding method named Multi-tree Coding Method (MCM), which has the following features: (1) it is established on a topological pattern reflecting the dendriform structure of drainage networks; (2) the multi-tree code can be effectively managed by the database to perform convenient topological search toward drainage networks using Structured Query Language (SQL); (3) the multi-tree code does not exhibit digital overflow problems in the computer, thus any resolution and scale drainage networks can easily be coded; and (4) it supports high-efficient search process. A river reach can be directly positioned in a drainage network under MCM, without the complex search process from all river reaches. This feature has great potential to improve the computational performance of basin models. We demonstrate here the efficiency and practicality of MCM by testing it in the Yalu Tsangpo river basin, Tibet. A drainage network with 140,745 digital reaches was extracted from the digital elevation model (DEM), and the multi-tree codes of all river reaches were obtained. [Copyright &y& Elsevier]

Abstract: This paper presents a real time prediction approach for floods caused by failure of natural dams due to overtopping. The approach adopts the observed outflow data of the preceding failure process for calibrating a simulation model, and the calibrated model is then implemented to predict the remaining failure process and flood characteristics. A widely used parametric model of dam failure is adopted in consideration of practicability and computational simplicity. The problems raised by interrelation among the model parameters and impeding the model calibration are analytically identified, and a simple but effective solution method is proposed. The approach was examined through two idealized cases where there exist no model inadequacy and measurement errors. Its effectiveness of and applicability to predicting the peak discharge and the time to peak of various outflows were exhibited. The real world case of Tangjiashan Quake Lake in China was further analyzed. The outflow peak discharge and the time to peak were reasonably predicted with one and a half hours ahead, demonstrating its potential for practical applications. Multistage features of the breach growth in nature may lower its performance due to raising difficulties in the identification of reasonable predictions. Future work of improving the model adequacy and observation accuracy would enhance its applicability to natural environments. [Copyright &y& Elsevier]

Abstract: Restricted computing power has become one of the primary factors obstructing advancement in basin simulations for majority of hydrological models. Parallel computing is one of the most available approaches to solve this problem. Using binary-tree theory, we present in this study a common parallel computing framework based on the message passing interface (MPI) protocol for modeling hydrological processes of river basins. A practical and dynamic spatial domain decomposition method, based on the binary-tree structure of the drainage network, is proposed. This framework is computationally efficient, and is independent of the type of physical models chosen. The framework is tested in the Chabagou river basin of China, where two years of runoff processes of the entire basin were simulated. Results demonstrate that the system may provide efficient computing performance. However, primarily because of the constraint of the binary-tree structure for drainage network, this study finds that unlimited enhancement of computing efficiency is impossible to realize. [Copyright &y& Elsevier]

A kinetic model was presented for dilute solid-liquid two-phase flows with inelastic collisions by modeling the inelastic collisions with the revised BGK model (Santos and Astillero, 2005) and particle turbulence interactions with the Fokker-Planck operator. The formulated model kinetic equation was solved with the Chapman-Enskog method and the obtained approximate solution was further adopted to derive the constitutive relationships for the conservation equations of the particle phase. The new constitutive relationships would be suitable for the study on dilute solid-liquid two-phase flows such as sediment-laden flows in open channels or rivers. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive analysis of suspended sediment transport in open channels under various flow conditions through a kinetic-model-based simulation. The kinetic model, accounting for both sediment-turbulence and sediment-sediment interactions, successfully represents experimentally observed diffusion and transport characteristics of suspended sediments with different densities and sizes. Without tuning any model coefficients, the nonmonotonic concentration distribution and the noticeable lag velocity with a negative value close to the wall are reasonably reproduced. Examination of flow conditions typical of suspension dominated rivers shows that the conventional method may overestimate or underestimate unit suspended-sediment discharge, depending on the Rouse number, sediment size, as well as shear velocity. The error may be less than 20% for dp<0.5 mm and might exceed 60% for dp>1.0 mm under typical flow conditions where shear velocity ranges from 1.0 to 12.5 cm/s and flow depth ranges from 1.0 to 5.0 m. [ABSTRACT FROM AUTHOR]

Diffusion coefficient of natural sediments and effects of lift force and gradient in particle velocity fluctuations were investigated through using a closed kinetic model. Comparison against experimental data of Einstein & Chien (1955) validated the model. The diffusion coefficient εyy of medium and large sediments distinctly exceeds fluid eddy viscosity νft, while εyy of fine sediments approximately equals νft. In the measured region of 0.03

Hutchinson–Gilford progeria syndrome (HGPS) is a rare and fatal disease manifested by premature aging and aging‐related phenotypes, making it a disease model for aging. The cellular machinery mediating age‐associated phenotypes in HGPS remains largely unknown, resulting in limited therapeutic targets for HGPS. In this study, we showed that mitophagy defects impaired mitochondrial function and contributed to cellular markers associated with aging in mesenchymal stem cells derived from HGPS patients (HGPS‐MSCs). Mechanistically, we discovered that mitophagy affected the aging‐associated phenotypes of HGPS‐MSCs by inhibiting the STING‐NF‐ĸB pathway and the downstream transcription of senescence‐associated secretory phenotypes (SASPs). Furthermore, by utilizing UMI‐77, an effective mitophagy inducer, we showed that mitophagy induction alleviated aging‐associated phenotypes in HGPS and naturally aged mice. Collectively, our results uncovered that mitophagy defects mediated the aging‐associated markers in HGPS, highlighted the function of mitochondrial homeostasis in HGPS progression, and suggested mitophagy as an intervention target for HGPS and aging. [ABSTRACT FROM AUTHOR]

The shaft friction in clay is essential to bearing capacity of pipe piles. Reasonable selection of design methods and parameters is very important for offshore piles. This paper focuses on the current popular vertical load design methods based on undrained strength for pipe piles, especially for offshore piles. Based on the database, the accuracy and reliability of various pile design methods based on undrained strength su in clay were reviewed. The small-scale model tests were conducted to evaluate su-based methods. For the shortcomings of small-diameter piles in the database, a field test of full-scale offshore pile was carried out and analysed. By comparing the calculated and the measured capacity for each method, the reliability of various design methods is evaluated for large-diameter piles. For the design methods based on undrained strength, it demonstrates the importance and reliability of the determination of undrained strength parameters. In view of the vertical loading conditions of offshore large-diameter steel pipe piles, reasonable suggestions for design methods and parameters determination are given. [ABSTRACT FROM AUTHOR]

The shaft friction in clay is essential to bearing capacity of pipe piles. Reasonable selection of design methods and parameters is very important for offshore piles. This paper focuses on the current popular vertical load design methods based on undrained strength for pipe piles, especially for offshore piles. Based on the database, the accuracy and reliability of various pile design methods based on undrained strength su in clay were reviewed. The small-scale model tests were conducted to evaluate su-based methods. For the shortcomings of small-diameter piles in the database, a field test of full-scale offshore pile was carried out and analysed. By comparing the calculated and the measured capacity for each method, the reliability of various design methods is evaluated for large-diameter piles. For the design methods based on undrained strength, it demonstrates the importance and reliability of the determination of undrained strength parameters. In view of the vertical loading conditions of offshore large-diameter steel pipe piles, reasonable suggestions for design methods and parameters determination are given. [ABSTRACT FROM AUTHOR]

Image-based grain sizing has been used to measure grain size more efficiently compared with traditional methods (e.g., sieving and Wolman pebble count). However, current methods to automatically detect individual grains are largely based on detecting grain interstices from image intensity which not only require a significant level of expertise for parameter tuning but also underperform when they are applied to suboptimal environments (e.g., dense organic debris, various sediment lithology). We proposed a model (GrainID) based on convolutional neural networks to measure grain size in a diverse range of fluvial environments. A dataset of more than 125 000 grains from flume and field measurements were compiled to develop GrainID. Tests were performed to compare the predictive ability of GrainID with sieving, manual labeling, Wolman pebble counts (Wolman, 1954) and BASEGRAIN (Detert and Weitbrecht, 2012). When compared with the sieving results for a sandy-gravel bed, GrainID yielded high predictive accuracy (comparable to the performance of manual labeling) and outperformed BASEGRAIN and Wolman pebble counts (especially for small grains). For the entire evaluation dataset, GrainID once again showed fewer predictive errors and significantly lower variation in results in comparison with BASEGRAIN and Wolman pebble counts and maintained this advantage even in uncalibrated rivers with drone images. Moreover, the existence of vegetation and noise have little influence on the performance of GrainID. Analysis indicated that GrainID performed optimally when the image resolution is higher than 1.8 mm pixel -1 , the image tile size is 512×512 pixels and the grain area truncation values (the area of smallest detectable grains) were equal to 18–25 pixels. [ABSTRACT FROM AUTHOR]

• Polyaniline morphology can be tuned by changing polymerization current density. • Polyaniline nanowire arrays increase ECSA with hydrogel polymer electrolyte (HPE). • Polyaniline nanowire arrays show a specific capacitance of 373.6 F g−1. • Performance of PANI-0.3 with HPE is comparable to that with aqueous electrolyte. • Flexible supercapacitor can light a LED under flat, folded and twisted conditions. High electrochemical surface area (ECSA) is the precondition for high performance of flexible supercapacitors, but remains a considerable obstacle. Because of the lower fluidity of hydrogel polymer electrolyte (HPE, generally utilized to fabricate flexible supercapacitors) than aqueous electrolyte (AE, used in traditional supercapacitors), it is difficult to infill a porous electrode with HPE completely, leading to a low ECSA between electrode materials and HPE. In this work, the structures of the polyaniline nanowires are designed to increase the ECSA. In comparison with nanowire network structure, the patulous structure of the polyaniline nanowire arrays is beneficial to increase the ECSA. The polyaniline nanowire arrays show a specific capacitance of 373.6 F g−1 at 0.1 A g−1 with the HPE, which is comparable to that with the AE at 0.1 A g−1 (376.6 F g−1). Flexible supercapacitors based on the polyaniline nanowire arrays exhibit similar performances under flat, folded, and twisted conditions, demonstrating their high potential application in flexible electrochemical energy storage devices. [ABSTRACT FROM AUTHOR]

Drainage basins are fundamental units of Earth's surface, describing how flows accumulate across landscapes. They are direct expressions of how tectonics and climatic forces alter Earth's surface morphology. Here, we measure the width‐to‐length ratios (WLRs) of 386,931 drainage basins (average area ∼157 km2), covering all continents except Antarctica and Greenland. Global variations in WLRs are correlated with climatic aridity, whole‐basin slope, and local topographic roughness. Basins in arid landscapes tend to be narrower, potentially reflecting a higher prevalence of surface runoff and therefore a stronger slope‐parallel component of the transporting flow. Local topographic roughness is associated with wider basins, potentially reflecting greater dispersion of flow directions. Conversely, whole‐basin topographic gradients, potentially reflecting gradients in uplift, are associated with narrower basins. However, steeper basins are also often rougher, so revealing the effects of whole‐basin slope requires correcting for the confounding effects of roughness variations. Plain Language Summary: Drainage basins are essential features that help us understand how water accumulates and flows across Earth's landscapes. In this study, we examined the width‐to‐length ratios of 386,931 drainage basins from all continents except Antarctica and Greenland. We found that basins tend to be narrower in more arid climates. We also observed that, all else equal, basins with greater local roughness tend to be wider, and those with steeper whole‐basin slopes tend to be narrower. Our results thus indicate that on the global scale, basin shapes are strongly influenced by topographic roughness, whole‐basin slope and climatic aridity. Our findings hold across different basin scales, encompassing smaller basins with a mean area of approximately 157 km2 to larger basins with a mean area of around 1,000 km2. These results advance our understanding of global patterns of basin shapes and the tectonic and climatic drivers behind them. Key Points: Globally, basins with greater topographic roughness tend to be wider, and those with steeper whole‐basin slopes tend to be narrowerIn arid regions (aridity index <0.65), basins tend to widen as climate becomes more humidBasin shape is strongly correlated with topographic roughness, whole‐basin slope and climatic aridity on a global scale [ABSTRACT FROM AUTHOR]

The middle Yellow River basin is known for its extremely high rate of erosion and sedimentdelivery and for the dramatic decrease in sediment yield over the last 20-30 years. Asuspended sediment rating curve (SRC, assumed to be Qs = aQb) describes the relationshipbetween water discharge (Q) and suspended sediment discharge (Qs) in a river, and theserelationships and their spatial and temporal variations could be used to interpret and indicatethe effect of climate change and human activities on sediment yield. The purpose of thisstudy was to examine how parameter values characterizing SRC, i.e. the exponent(b) and coefficient (a), were related to river basin characteristics, and to find outhow these SRC parameters varied from a period of poor vegetation cover priorto 1970 to a period with much improved vegetation cover since 2000. The SRCparameters were firstly estimated with the least square technique using log-transformeddaily data for 70 hydrologic gauging stations in the middle Yellow River basin.Precipitation, temperature, flow duration (the percentage of the number of days with theflows above 25% of the mean discharge), flow peakedness (the ratio of averageannual peak discharges to the mean discharge), drainage area, basin relief, and thepercentage of area with a slope &#x003E; 15˚ were used to characterize each of the 70river basins. The exponent b for the middle Yellow River basin ranged from 1.5and 3.3 for the 70 stream gauging stations. Correlation analysis showed that thecoefficient a was mainly negatively correlated with the long-term mean Q, basinrelief, drainage area, the annual mean precipitation and temperature, while a waspositively correlated with the flow peakedness, and the exponent b was most stronglycorrelated with flow duration. The SRC exponent b has significantly decreased from theperiod before 1970 with poor vegetation cover to the period since 2000 with muchimproved vegetation cover, while the SRC coefficient a has not changed muchbetween the two contrasting periods, this indicated the erosive power of streams havedecreased generally in the middle Yellow River region since 2000. The impact ofhuman activities on SRC parameters needed to be analyzed for further research. [ABSTRACT FROM AUTHOR]

Suspended load brings about density stratification which limits turbulence and lateral mixing process. Hereafter, the river adjusts its meandering procedure in a different way compared to no suspended load. Generally, suspended load has a wide range of sediment transport capacity depending on the flow velocity and diameter. Higher concentration suspended load affects the flow density obviously. The inertia effect is considered by adopting hydrostatic equations without Boussinesq approximation. This study compares simulations with and without stratification and inertia effect respectively. For low suspension concentration, stratification effect advances secondary flow. For higher suspension concentration, inertia effect suppresses secondary flow and would change rotation direction. Stratification effect slows down meandering speed while inertia effect changes meandering development trend. [ABSTRACT FROM AUTHOR]

Hydraulic roughness height is a key parameter for velocity prediction. There are not yet firmconclusions about whether characteristic particle size (D84, D90...) or the standarddeviation of bed elevation is better indicator for the hydraulic roughness of gravel-bedstreams. A data set of 1713 flume experiments and 515 field measurements wasused to test whether or the standard deviation was a better predictor of the streamvelocity, and to explore possible reasons for the difference between the two roughnessmeasures. Tests were performed using 4 well-known flow resistance equations,based on either flow depth or a dimensionless discharge as independent variables.Results showed that the standard deviation of bed elevation was consistently a betterpredictor of the velocity than D84 in terms of the root-mean square error. In addition,Ferguson equation with the standard deviation as hydraulic roughness shows bestoverall performance in velocity prediction. In particular, when using dimensionlessdischarge as the input variable, logarithmic matching equation with the standarddeviation as hydraulic roughness is recommended for its explicit form. The data set wasseparated into two sub-sets with or without typical bed forms or large wood debris.The results showed that the existence of bed forms and large wood debris could bethe reason why the standard deviation outperformed as a measure of hydraulicroughness for velocity predictions. Characteristic size measures the grain roughnessonly, whilst variations in bed elevation combine the effect of surface roughness andthat of some large flow resistance elements such as bed forms and wood debris. [ABSTRACT FROM AUTHOR]

The excellent bonding performance between polyester fibers and rubber is key to the high elasticity and fatigue resistance of rubber composite materials. Here, the modified polyester staple fiber (MPET) was obtained by microwave irradiation and surface modification with γ-aminopropyltriethoxysilane (KH550). The results revealed that KH550 reacted with the carboxyl groups on the surface of PET and thus adhered to the fiber surface, which was beneficial in improving compatibility with rubber. When reinforcing natural rubber (NR), MPET combined with the NR molecular chain flexibility due to the rigidity of its own main chain structure. This synergy resulted in the formation of inter-chain entanglements, contributing to a reduction in internal energy dissipation and heat generation within the composite. As the MPET dosage is augmented, the maximum torque of the NR compound during the mixing process exhibits an upward trend. In parallel, the cured NR rubber experiences a gradual reduction in both tensile strength and elongation at break, accompanied by a progressive increase in hardness. Furthermore, a notable elevation in tear strength is observed. This observed trajectory accentuates the intricate interplay between the dosage of MPET and the mechanical attributes of the NR rubber composite. The results of Rubber Processing Analyzer (RPA), Dynamic Mechanical Analysis (DMA) and Scanning Electron Microscope (SEM) indicate that the interfacial bonding between MPET and NR shows promising prospects as rigid short fibers for reinforcing non-polar rubber. [ABSTRACT FROM AUTHOR]

Summary: Star copolymers with good film‐forming and mechanical properties were in situ synthesized for fabricating proton exchange membranes. The monomers of 3,4‐diaminobenzoic acid were first grafted onto glycidyl‐polyhedral oligomeric silsesquioxane (G‐POSS) cores and then propagated to the poly(2,5‐benzimidazole) (ABPBI) chains. The introduction of the star copolymer improves the movement of the ABPBI polymer chains, resulting in a lower internal viscosity and larger free volume that favor increased membrane flatness and absorbilities of water and phosphoric acid molecules, respectively. It was found that the star copolymers with 1.0 wt% of incorporated POSS (ABPBI‐1.0POSS) had the best balance of the acid retentivity and film‐forming property as well as mechanical properties that are desirable for proton exchange membranes without PA loss operating at high temperatures. The enhanced cell performance characteristics obtained using the ABPBI‐1.0POSS‐based membranes indicate that star copolymers are promising materials for use in high‐temperature proton exchange membrane fuel cells. [ABSTRACT FROM AUTHOR]

Sediment saltation in a rough-wall turbulent boundary layer was simulated with a coupled model with large eddy simulation and a discrete element model. The aim is to quantify the saltation process using eddy-resolving fluid simulations and Lagrangian particle tracking. The four-way coupling approach in this work considered the fluid–particle, particle–particle, and particle–wall interactions. Five simulations were performed. For comparison, one simulation with the flow field replaced by a simple log-law profile was also performed. The simulated saltation trajectory, velocity, and collision angles were analysed and we found: (1) Turbulent fluctuation and random collision with the bed are two controlling factors for particle trajectory. Without turbulent fluctuation, the loss of saltation information is severer in the streamwise direction than in other directions. In the spanwise direction, bed collision plays a comparable role to turbulent fluctuation. (2) Particle velocities in the streamwise and vertical directions follow skew-normal distributions. (3) Turbulent fluctuations make the incidence angle wider and slightly enhance the correlation between the incidence and reflection angles. [ABSTRACT FROM AUTHOR]

Expression of vascular endothelial growth factor (VEGF) and transforming growth factor-β1 (TGF-β1) in atherosclerosis animal model of type 2 diabetes mellitus treated with simvastatin was investigated. Clean grade mature Sprague Dawley (SD) rats were divided into three groups: Normal control (n=10), model (n=13) and treatment group (n=13); lowdose simvastatin was administered. The changes of VEGF and TGF-β1 levels were analyzed by tail vein blood sampling. The relationship between levels of VEGF, TGF-β1 and treatment time was analyzed. The expression level of VEGF in the treatment group after 4 and 8 weeks of intervention was lower compared with the model group (P<0.05). The expression level of TGF-β1 in the treatment group after 8 weeks of intervention was higher than that in the model group (P<0.05). The expression level of VEGF in the treatment group after 8 weeks of intervention was lower than that after 1 week of intervention (P<0.05). The expression level of TGF-β1 was increased in the model group after 8 weeks of intervention compared with 1 week before and after the intervention (P<0.05). The expression level of TGF-β1 in the treatment group at 2, 4 and 8 weeks after intervention were significantly higher than that before intervention (P<0.05). The expression of TGF-β1 increased after 4 and 8 weeks after intervention compared with 1 week after intervention (P<0.05). The expression of VEGF was negatively correlated with TGF-β1 expression in the treatment group; negative correlation was found between VEGF and treatment time. There was a positive correlation between TGF-β1 and treatment time. VEGF and TGF-β1 may be involved in the development of type 2 diabetes (T2MD) atherosclerosis (AS). Simvastatin may play a therapeutic role in T2MD AS by downregulating VEGF and upregulating the expression of TGF-β1. [ABSTRACT FROM AUTHOR]

Direct numerical simulations at two friction Reynolds numbers (550 and 1000) have been performed to explore the statistical behaviors of wall-attached motions (WAMs) in open- and closed-channel flows (OCFs and CCFs). To fully capture the largest energetic WAMs, superlarge domain sizes are employed (24–48 π h along streamwise direction with h being the height of OCFs). Based on the analysis of linear coherence spectrum, both geometric and kinematic characteristics of WAMs are investigated. Results revealed that obvious peaks could be found in spanwise coherence spectra of u (streamwise velocity) and w (spanwise velocity) at a wavelength close to 2h. Both the coherence and energy spectra density value of OCFs are greater than those of CCFs at large wavelengths, indicating that OCFs are more wall-attached. Within y/h = 0.2–0.7, the diagnosed streamwise and spanwise wavelengths of WAMs increase roughly linearly with increasing vertical position y. In the upper region (y / h > 0.7), the diagnosed wavelengths in OCFs are smaller than those in CCFs. In addition, the inclination angle of u fluctuates around 14° within y / h = 0.4–0.6, and angles of CCFs are slightly larger than those in OCFs when y / h > 0.6. Regarding kinematic behavior, contribution fractions of WAMs to total turbulent intensity in OCFs are always larger than those in CCFs. Additionally, the wall-attached behaviors of u were found to be more sensitive to Reynolds number than w. [ABSTRACT FROM AUTHOR]

We present a high order finite difference solver, ParaTC, for the direct numerical simulations of turbidity currents with canonical turbulent channel configuration (periodic boundary conditions in the horizontal directions and non-periodic in vertical direction). Uniform meshes are adopted in streamwise and spanwise directions, while stretched grids can be used in wall-normal direction. In order to improve the parallel efficiency, we propose a new 2D pencil-like parallel configuration with totally 6 different pencil arrangements. A parallel Thomas algorithm is also included to further reduce the communication overhead when solving tridiagonal equations. In addition, we perform an optimal search method in the initializing stage to find the fastest Poisson solver scheme among four alternatives for a specific mesh configuration. The runtime ratio between traditional pencil-like Poisson solver and present solver is about 1.5. An approximate linear strong scaling performance is achieved, and the weak scaling performance is also improved. Three benchmark simulations are preformed, and the statistics are compared with those extracted from the simulations by the spectral method, and good agreements are achieved. The source code is freely available at https://github.com/GongZheng-Justin/ParaTC. [ABSTRACT FROM AUTHOR]

Summary The present paper provides a systematical analysis for concentration distribution of Taylor dispersion in laminar open channel flow, seeking fundamental understandings for the physical process of solute transport that generally applies to natural rivers. As a continuation and a direct numerical verification of the previous theoretical work (Wu, Z., Chen, G.Q., 2014. Journal of Hydrology, 519: 1974–1984.), in this paper we attempt to understand that to what extent the obtained analytical solutions are valid for the multi-dimensional concentration distribution, which is vital for the key conclusion of the so-called slow-decaying transient effect. It is shown that as a first estimation, even asymptotically, the longitudinal skewness of the concentration distribution should be incorporated to predict the vertical concentration correctly. Thus the traditional truncation of the concentration expansion is considered to be insufficient for the first estimation. The analytical solution by the two-scale perturbation analysis with modifications up to the second order is shown to be a most economical solution to give a reasonably good prediction. [ABSTRACT FROM AUTHOR]

[Display omitted] • NGO nanoparticles were embedded into SPI polymers through in-situ synthesis. • In-situ synthesis was more favorable for NGO dispersion and well-constructed interface compared to physical blending. • The fracture strength of NGO-SPI composite membrane was approximately 61 MPa. To mitigate the severe degradation of mechanical properties and stability of highly sulfonated proton exchange membranes (PEMs) caused by the sulfonic acid groups, amino-functionalized graphene oxide (AGO) was embedded into sulfonated polyimide (SPI) for the in-situ synthesis of a composite proton exchange membrane. The introduction of AGO nanoparticles facilitated the enhancement of the crystallinity of the composite membrane, with the well-constructed interface and dispersion. The resulting AGO-SPI composite membrane exhibited high mechanical strength and stability. The fracture strength of AGO-SPI composite membrane was approximately 61 MPa, which was 1.85 times higher than that of pure SPI. Meanwhile, the weight loss of AGO-SPI composite membrane in Fenton's reagent was only 2.11 %. Additionally, at 90 °C/98 % RH, the proton conductivity of AGO-SPI composite membrane reached 50.1 mS cm−1, which was 3.53 times higher than that of pristine SPI. The results suggest the promising application prospects of the proton exchange composite membrane. [ABSTRACT FROM AUTHOR]

The major limitation of conventional sulfonated polymer proton-exchange membranes (PEMs) is their strong reliance on water molecules for proton conduction, causing a significant reduction in proton conductivity under low-humidity conditions. In this study, a one-dimensional ionogel (IL@Sep) confined within sepiolite (Sep) nanorods was prepared using ionic liquid (1-butyl-3-methylimidazolium trifluoromethanesulfonate) and supercritical CO 2. Subsequently, IL@Sep was blended with a Nafion solution, and electrospinning was used to fabricate the composite fiber PEM suitable for low-humidity environments. The results revealed that the electrospun (ES)-Nafion/IL@Sep composite fiber membrane exhibited significantly enhanced mechanical properties, water absorption, and proton conductivity. At an IL@Sep content of 2 wt%, the Nafion/2IL@Sep membrane exhibited a proton conductivity of 231 mS cm−1 at 80 °C/98 % relative humidity (RH) and 113 mS cm−1 at 80 °C/40 % RH. Moreover, the single-cell assembled with this composite membrane exhibited good gas tightness and achieved a peak power density of 779 mW cm−2 at 60 °C/80 % RH, which was ∼1.45 times that of the Nafion 212 membrane single-cell. This study indicates that electrospinning-assisted ionogel-modified ES-Nafion/IL@Sep composite fiber membranes have potential suitability for use in proton-exchange membrane fuel cells under varying humidity conditions. [Display omitted] • Sep-encapsulated ILs (IL@Sep) were prepared using supercritical CO 2. • Nafion/2IL@Sep membrane-based single-cell achieved a peak power density of 779 mW cm−2 at 60 °C/80 %. • The composite membrane's improved performance was due to the axial alignment of IL@Sep within the Nafion nanofibers. [ABSTRACT FROM AUTHOR]

The extraction of high-resolution geomorphic information from remote sensing images is a key technology for supporting mountain river research. Extracting small rivers (width < 90 m) from complex backgrounds based on satellite images remains a challenging issue. In this research, we propose an improved random forest (RF) algorithm, RF-ANN (artificial neural network), by using neural networks and thermal infrared data for the extraction of river surfaces. We also develop an automated river width extraction (ARWE) method based on the central axis transformation algorithm and centerline automatic correction algorithm for the automatic extraction of the river widths across the whole basin. We chose the Huangfuchuan River Basin on the Loess Plateau, China, as a case study area. Chinese GF-1 and ZY-3 satellite images were implemented as the primary data source. We extracted the bankfull river surface and river widths of the Huangfuchuan River by using these two improved methods. The results show that the RF-ANN method has a total river surface extraction accuracy of 94.7%, and the extracted river surfaces cover more than 85% of the order 3 DEM river network. By implementing high-resolution DEM and thermal infrared data, RF-ANN effectively eliminates the disturbance of shadows of mountains and other features, which ensures the high accuracy of the extracted widths. It was verified that the maximum and minimum river widths that can be extracted in the Huangfuchuan River Basin are 297.4 m and 6.1 m, respectively. The overall error of river width extraction is 0.97 m, which is less than half of the pixel length of remote sensing images. The R2 and root mean square error (RMSE) of the estimated river width values are 0.99 and 1.49, respectively. For tiny rivers with widths narrower than 10 m, the error of river width extraction is 10.9%. The error of thin rivers whose widths range from 10 to 30 m is 4.9%. For small rivers ranging from 30 to 90 and rivers wider than 90 m, the error is 1.1% and 0.6%, respectively. The new approach provides an effective method for extracting the surface and width of mountain rivers in topographically complex regions by using high-resolution satellite images, which may provide a database for estimating river carbon emissions and related research in fluvial morphology and water resource management. [ABSTRACT FROM AUTHOR]

Abstract: A novel method for measuring effective diffusion coefficient of porous materials is developed. The oxygen concentration gradient is established by an air-breathing proton exchange membrane fuel cell (PEMFC). The porous sample is set in a sample holder located in the cathode plate of the PEMFC. At a given oxygen flux, the effective diffusion coefficients are related to the difference of oxygen concentration across the samples, which can be correlated with the differences of the output voltage of the PEMFC with and without inserting the sample in the cathode plate. Compared to the conventional electrical conductivity method, this method is more reliable for measuring non-wetting samples. [Copyright &y& Elsevier]

• Dry riverbeds make the CO 2 emissions from intermittent rivers in arid areas equally important as from perennial rivers. • Combination of hydrological modeling, remote sensing and in-situ measurements improve the river CO 2 emission estimation. • Flow duration and dry riverbed area should be considered in estimating CO 2 emissions from intermittent river systems. Intermittent rivers in semiarid and arid regions, constituting over half of the world's rivers, alternate the carbon cycle interactions among the biosphere, hydrosphere, and atmosphere. Inadequate quantification of flow duration and river water surface area, along with overlooked CO 2 emissions from dry riverbeds, result in notable inaccuracies in global carbon cycle assessments. High-resolution remote sensing images combined with intensive field measurements and hydrological modelling were used to estimate and extract the flow duration, river water surface area and dry riverbed area of Huangfuchuan, an intermittent river watershed that acts as a major tributary of the Yellow River in semiarid Northwest China. CO 2 emission rates and partial pressures in water and air across the watershed were in-situ measured. In 2018, the flow duration of Huangfuchuan increased from less than 5 days in the first-order tributary to 150 days in the sixth-order mainstream. River water surface area estimated by remote sensing extraction plus the hydrodynamic model simulation varied from 3.9 to 88.6 km2 under 5 %–95 % discharge frequencies. CO 2 emissions from the water-air interface and dry riverbed in 2018 were estimated at 582.3 × 103 and 355.2 × 103 ton, respectively. The estimated total annual emission (937.5 × 103 ton) aligns closely with the range of emissions (67.3 × 103–1377.2 × 103 ton) calculated for the water-air interface alone, derived using DEM river length and hydraulic geometry method. This similarity can be attributed to the overestimation of flow duration and flow velocity, as well as the over- or under-estimation of river water surface area and slope. The new method proposed in this study has large potential to be applied in estimating CO 2 emissions from data-scarce intermittent rivers located in mountainous regions and provides a standardized solution in the estimation of CO 2 emission. Results of this research reveal the spatiotemporal distribution of CO 2 emissions along an intermittent river system and highlight the substantial role of dry riverbed in carbon cycle. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • IL@HNTs were prepared utilizing supercritical fluid technology. • Proton conductivity of SPEEK/6IL@HNTs was above 20 mS/cm at −10–90 °C. • SPEEK/6IL@HNTs single-cell achieved 732 mW/cm2 at 60 °C. • IL@HNTs alignment in polymer fibers boosted composite membrane performance. The most fatal drawback of traditional sulfonated polymer proton-exchange membranes (PEMs) is their heavy dependence on water molecules to conduct protons, which causes a sharp decrease in their proton conductivity in low-humidity environments. Here, composite membranes were fabricated by electrostatically spinning halloysite nanotube-encapsulated ionic-liquids (IL@HNTs) incorporated into sulfonated poly(ether ether ketone) (SPEEK) (SPEEK/IL@HNTs). Using electrospinning, one-dimensional IL@HNTs ionogels with good water absorption were axially and uniformly aligned along the fiber filament direction. This formed long-range uninterrupted proton conduction pathways that greatly improved the proton conductivity of the composite membrane under various humidity environments. The axially-aligned structure facilitated crystallization, which improved the mechanical properties and thermal stability of the composite membrane. The SPEEK/6IL@HNTs membrane exhibited a through-plane proton conductivity of 139.2 mS cm−1 at 90 °C/98 % RH, representing a significant increase compared with the intrinsic SPEEK membrane. The SPEEK/6IL@HNTs membrane demonstrated a maximum power density of 732 mW cm−2, which exceeded that of the Nafion115 membrane (328 mW cm−2) by a factor of 2.2. It exhibited a single-cell performance equivalent to that of the Nafion212 membrane (723 mW cm−2), demonstrating that this provides a feasible approach to operating fuel cells in low-humidity environments without additional humidification. [ABSTRACT FROM AUTHOR]