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Most mechanical oil leaks and industrial oily wastewater are in complex and harsh environments. Hence, developing a simple and efficient method to store oil or separating oil–water contaminants has become an ongoing challenge. Hierarchically porous polyetheimide (HPPEI) is a promising competitive candidate due to the combination of functional designability, featuring multilayer pores, and the excellent properties of PEI. Herein, HPPEI (micro‐ and nano‐) is developed by fused deposition modeling (FDM) printing, which enables customizable uniform pores, and green and cost‐effective supercritical CO2 foaming method. HPPEI exhibits remarkable oil content and oil adsorption rate, attributed to the nanopores functioning as "windows." Nanopores alter the adsorption mode from the "individual adsorption" of PPEI to "interconnected adsorption," accompanied by an increased storage capacity, and enhanced the overall adsorption rate due to strong capillary effect and higher adsorption rate. HPPEI modified with hydrophobic nano fumed silica (HN─SiO2), demonstrates outstanding hydrophobicity and lipophilicity features selective oil adsorption and oil–water separation, and retains excellent hydrophobic even at high temperatures and in acidic and alkaline environments. This material is expected to provide a strategy for energy conservation: selective oil adsorption from oily wastewater in harsh environments and then the oily material is utilized for lubrication areas, avoiding material waste. [ABSTRACT FROM AUTHOR]

Breach geometry is one essential feature for flood modelling in the channel–levee–floodplain system. It is hard to accurately predict the breach geometry because of its high uncertainty. However, due to the fact that breach geometry direct impacts the flow through the breach, the water surface profile in the channel and the flood hazard factors within the floodplain are changed with the breach geometry. To explore the impacts of breach width (one feature of the breach geometry) on the channel–levee–floodplain system, we took the Cinan Feiyou Flood Control Protection Area (CNFY-FCPA) in the middle reach of the Huaihe River Basin as the study area. We constructed a coupled 1D-2D hydrodynamic model to simulate the flooding with a series of breach-width scenarios. According to the simulation results of the models, we quantitatively analyzed the impacts of breach width on the inflow through the breach, fluvial flood process, and flood hazard factors in the CNFY-FCPA. The results indicate that (i) the relationship between the peak discharge (and inflow volume) and breach width was approximate to an S-shaped curve, while the peak discharge, inflow volume, and duration per unit width decreased with the wider breach; (ii) the breach caused a decrease in the water surface profile along the entire river sections; and (iii) while the breach width exceeded a certain width, the inundation area was nearly stable without changing with wider breach. The certain width was not the same in different rivers of 300 m in the Yinghe River and of 500 m in the Huaihe River. The research results can provide a scientific basis for flood-control and disaster-reduction decision making. [ABSTRACT FROM AUTHOR]

It is challenging to enhance the stress‐free two‐way shape memory (stress‐free TWSM) effect to obtain a wide range of response temperatures. Herein, a polycaprolactone (PCL)/poly(ω‐pentadecalactone) (PPDL) is photocured under UV light irradiation in the solvent of 1,1,2‐trichloroethane (TCA), to obtain a series of cross‐linked polyesters (CPES). Controlling solvent content (SC) which is removed after the polymerization allows the yielded CPES to perform a regulatable thermodynamic and stress‐free TWSM properties. High SC is beneficial to reduce the degree of chain overlap (C/C*) of PPDL chain segments in the PCL‐based CPES network, then causes the cocrystallization of PCL and PPDL and yielding an additional melting‐transitions (Tm). An enhanced stress‐free TWSM is obtained in high SC samples (CPES‐15‐90), reflected in the attainment of a wide range of response temperature, which means a wider service temperature. The enhancement is reflected in higher reversible strain of high SC samples compared with the samples prepared with low SC when varying high trigger temperature (Thigh). Even at high Thigh, the high SC sample still has reversible strain. Therefore, controlling SC strategy for photocuring copolyester not only provides a new preparation approach for high‐performance shape memory (SM) polymers, but also offers new condensed polymer structure to explore. [ABSTRACT FROM AUTHOR]

The development of smart lubricating materials with lasting lubrication and outstanding wear resistance while achieving speed response is of great significance in the field of bearing cage applications but has proven to be challenging. Herein, polyimide (PI) molding powder containing two kinds of PI with different rigidities is synthesized in situ to fabricate a two‐scale porous polyimide (PPI) by (cold and hot) isostatic pressing. The unique two‐scale porous structure originates from the bimodal particle size distribution of the PI molding powder. The oil stored in the two‐scale PPI is gradually thrown out as the rotation speed increases, which makes the two‐scale PPI suitable for bearing cages with a wider rotation speed range and realize persistent and stable oil supply under different speeds. The porosity of PPI decreases with increasing pressure during hot isostatic pressing, but the effect of temperature on the porosity is not obvious. Moreover, the two‐scale PPI maintains good mechanical properties, and its ring tension is as high as 22.3 MPa. Due to the high oil content (>15%) and excellent oil retention rate (93.3%, at 3000 rpm for 180 min), the two‐scale oil‐containing PPI exhibits a stable low friction coefficient (≈0.096) and ultralow wear rate (≈0.68×10−6mm3 (Nm)−1). [ABSTRACT FROM AUTHOR]

With the challenges of arid transboundary river water management among Central Asian countries, it is important to evaluate the water stress and propose practicable climate adaptation strategies. This study used the Syr Darya Basin (SDB) in a Central Asia data scarce region as the study area and, conducted the first quantified analysis of the spatiotemporal characteristics of water supply and requirements at the basin and irrigation district scale; identified its driving mechanisms based on systematic monitoring data concerning reservoir regulation and complex crop structure from 2000 to 2018; and a climate change scenario combined with a crop restructuring scenario was applied to evaluate water conservation effects and propose a climate adaptation strategy from 2019 to 2030. The results showed that runoff increased by 7.45 billion m3 but the water withdrawal decreased by 3.42 billion m3 after reservoir regulation in the basin during 2000–2018. Due to the unified water allocation, it was challenging to conduct and usually exceeded the plan by 0.4–8.5 %. The total crop water requirement (TCWR) mainly derived from cotton (61.5 %), winter wheat (12.1 %) and rice (13.9 %) increased by 3.15 billion m3 (+30.7 %) and the influence of crop area (380 million m3/a) was greater than that of climate (130 million m3/a). The wind speed (27.5 %) and rice area (19.2 %) also significantly contributed to the TCWR variation. The contradiction between water supply and requirement resulted in water scarcity in the basin. From 2019–2030, the water conservation effect of winter wheat (+20 %) under the restructuring scenarios reached 28.7 mm, which helped relieve water stress under the scenario of a 0.51–0.91 °C increase. Thus, priority planting of a winter wheat rotation and low water consuming crops is a practicable approach for coping with water scarcity and adapting to climate change in arid transboundary rivers of Centra Asia. [Display omitted] • A crop restructuring scenario was proposed to adapt to future climate change. • Increasing wind speed and rice area contributed the most to the water stress. • Priority development of winter wheat rotation is practical for water conservation. [ABSTRACT FROM AUTHOR]