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Considering the dilemma of obtaining economic and high-performance composites based on non-polar and main-chain-saturated ethylene propylene diene monomer rubber (EPDM), we proposed an effective and universal filler modification and nanocomposite preparation method. Specifically, the montmorillonite (MMT) surface was coated with polydopamine (PDA) to obtain DMMT, which was confirmed by XRD, XPS, FTIR, and TGA. After compounding DMMT gel with the solid EPDM via the gel compounding method, a silane coupling agent, vinyltrimethoxysilane, was introduced to construct covalent interactions between rubber and filler. Compared with the unmodified MMT filler EPDM, the EPDM/DMMT nanocomposite showed much fewer filler aggregates in the matrix. The highest tensile strength of the composites reached 6.5 MPa with 10 phr DMMT, almost 200% higher than that of pure EPDM. [ABSTRACT FROM AUTHOR]

Today, impingement cooling structures with dimples can effectively ease the burden of turbine blades. This paper investigates the effect of dimple diameter and depth on the heat transfer of the target surface on a laminar-cooled turbine blade with a cross-flow and dimple numerically to find the mechanism behind it so that the dimple can be better used in turbine cooling. The commercial software ANSYS 19.2 and a baseline (BSL) turbulence model is used during the numerical computation. In this paper, the cross-flow Reynolds number varies from 15,000 to 60,000, while the jet Reynolds number remains at 30,000. When the cross-flow Reynolds number changes, due to the location change in vortexes generated inside or around the dimple, the two dimple parameters affect heat transfer differently. When the cross-flow Reynolds number is lower than the jet Reynolds number, dimples with smaller diameters and depths lead to better heat transfer performance. When the cross-flow Reynolds number exceeds the jet Reynolds number, dimples with bigger diameters and depths result in better heat exchange performance. The results also indicate that, while the dimple diameters remain constant, the rise of the cross-flow Reynolds number enhances the heat transfer of the dimple structure. [ABSTRACT FROM AUTHOR]

This paper proposes a new pneumatic modular joint to address the problem of balancing compliance and load-bearing capacity for soft robots. The joint possesses characteristics that allow for omnidirectional deformation and dynamically adjustable stiffness. In this study, mathematical models were established to describe the deformation and stiffness variability of the joint. Corresponding relationships between gas pressure and deformation and magnetic field strength and module stiffness were derived through numerical analysis. Finite element simulations were conducted to investigate the changes in pressure and deformation under different stiffness conditions and the changes in magnetic field strength and joint stiffness under various deformation states. Finally, experimental validation was performed to verify the theoretical calculations and simulation results, demonstrating excellent coupling characteristics between stiffness and compliance for the proposed joint. [ABSTRACT FROM AUTHOR]

Cascade damming can shape land surfaces; however, little is known about the specific impacts of dam construction on watershed land cover changes. Therefore, we developed a framework in which remote sensing, transition patterns, and landscape metrics were coupled to measure the impact of dam construction on watershed land cover changes and landscape patterns in the Longmen–Su (L–S) Creek, a small headwater watershed in Southeast China. During the transition and post-impact periods of dam construction, the land cover in the L–S Creek watershed underwent dynamic changes within the affected area. Changes in land cover were dominated by a surge in water and buildup and a decrease in woodland and cropland areas; bareland also increased steadily during construction. Woodlands and croplands were mainly flooded into water areas, although some were converted to bareland and built-up areas owing to the combined impact of dam construction and urbanization. By linking land cover changes with landscape patterns, we found that land use changes in water were significantly associated with landscape fragmentation and heterogeneity in the impacted zone. Our research demonstrates how damming can change land cover locally and may provide a basis for sustainable land management within the context of the extensive development of cascade hydropower dams. [ABSTRACT FROM AUTHOR]

Stainless steels (SSs) easily suffer localized corrosion damage, such as pitting corrosion, in mixed solutions of acetic acid and sodium chloride. Currently, few works have been focused on the early stages of the pitting corrosion (metastable pitting corrosion) process of SSs in a chloride-HAc mixture solution. In this work, the effects of acetic acid (HAc) and its concentration on metastable pitting corrosion and the uniform corrosion of 304 SS in 0.6 mol/L NaCl solution were investigated by a slow-scanning potentiodynamic polarization test, scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The results show that the uniform corrosion rate of 304 SS increases after HAc addition but, with an increase in HAc concentration, the corrosion rate decreases. In the presence of HAc, the metastable pitting potential (Em) and stable pitting potential (Eb) move negatively, but the number of metastable pits notably decreases. HAc has a promoting action on the growth rate of the metastable pits and facilitates the transition from metastable pits to stable pits. The influence of HAc is related to a decrease in solution pH and the chemical adsorption of HAc. [ABSTRACT FROM AUTHOR]

Watershed ecological compensation is an important economic tool for solving the protection–development conflict. However, establishing a sound ecological compensation plan for rational water resource use at the watershed scale remains challenging. Monthly water samples were collected between April 2019 and July 2020 at 28 points to analyze the spatiotemporal variation in water quality in the Taoxi Creek watershed, which is important for local water security. The Soil and Water Assessment Tool was used to simulate water supply, demand, and spatial flow at the watershed scale. Water quality restoration cost was integrated with ecosystem service flow to quantify the watershed ecological compensation. The ecological compensation using water quality restoration cost based on pollutant treatment cost and water quality target level was CNY 11.9 million (USD 188 million). Taoxi Creek was identified as the major supplier of water ecosystem services for downstream residents, and the ecological compensation based on ecosystem service flow was CNY 18.9–47.2 million (USD 3.0–7.5 million). Combining both calculations, the watershed should annually receive CNY 30.8–59.1 million (USD 4.9–9.3 million) of economic compensation from downstream ecosystem beneficiaries. This study provides a scientific basis for improving the ecological compensation scheme in the Taoxi Creek watershed and a reference for ecological compensation formulation in other watersheds. [ABSTRACT FROM AUTHOR]

In this work, a small amount of carbon nanotubes (CNTs) was used to partially replace the silica in ethylene-propylene-diene monomer (EPDM) to prepare EPDM composites via mechanical blending. The mechanical properties, thermal-oxidative aging properties and thermal stability of the composites were systematically investigated. The results showed that with the increase of CNTs content, the Shore A hardness and stress at 100% strain of the composites increased, while the elongation at break decreased. With the aging time increasing, the aging coefficient and elongation at break of composites decreased while hardness increased due to the raise of crosslinking density. In addition, evidences were found to demonstrate the improved aging resistance by adding CNTs in the EPDM composites, including the less change in Shore A hardness, the smaller change ratio of elongation at break and the lower aging coefficient. When the content of CNTs reached 10 phr, the aging coefficient of the EPDM composite aged for 168 h was nearly twice that of the composite without CNTs, and the thermal stability of the EPDM composite with CNTs was improved as demonstrated by thermal analysis. [ABSTRACT FROM AUTHOR]

In spite of many anti-cancer drugs utilized in clinical treatment, cancer is still one of the diseases with the highest morbidity and mortality worldwide, owing to the complexity and heterogeneity of the tumor microenvironment. Compared with conventional 2D tumor models, 3D scaffolds could provide structures and a microenvironment which stimulate native tumor tissues more accurately. The extracellular matrix (ECM) is the main component of the cell in the microenvironment that is mainly composed of three-dimensional nanofibers, which can form nanoscale fiber networks, while the decellularized extracellular matrix (dECM) has been widely applied to engineered scaffolds. In this study, pig kidney was used as the source material to prepare dECM scaffolds. A chemical crosslinking method was used to improve the mechanical properties and other physical characteristics of the decellularized pig kidney-derived scaffold. Furthermore, a human breast cancer cell line (MCF-7) was used to further investigate the biocompatibility of the scaffold to fabricate a tumor model. The results showed that the existence of nanostructures in the scaffold plays an important role in cell adhesion, proliferation, and differentiation. Therefore, the pig kidney-derived matrix scaffold prepared by decellularization could provide more cell attachment sites, which is conducive to cell adhesion and proliferation, physiological activities, and tumor model construction. [ABSTRACT FROM AUTHOR]

Cold atoms trapped and guided in hollow-core photonic crystal fibers provide a scalable diffraction-free setting for atom–light interactions for quantum technologies. However, due to the mismatch of the depth and spatial extension of the trapping potential from free space to the fiber, the number of cold atoms in the fiber is mainly determined by the loading process from free space to waveguide confinement. Here, we provide a numerical study of the loading dynamics of cold atoms into a hollow-core photonic crystal fiber. We use the Monte Carlo method to simulate the trajectories of an ensemble of cold atoms from free space trapping potential to optical potential inside a hollow-core fiber and calculate the temperature, loading efficiency, and geometry of the ensemble. We also study the noise sources that cause heating and a loss of atoms during the process. Our result could be used to design and optimize the loading process of cold atoms into a hollow-core fiber for cold atom experiments. [ABSTRACT FROM AUTHOR]