Urban sprawl has impacted increasingly on water environment quality in watersheds. Based on water environmental response, the simulation and prediction of expanding threshold of urban building land could provide an alternative reference for urban construction planning. Taking three watersheds (i.e., Yundang Lake at complete urbanization phase, Maluan Bay at peri-urbanization phase and Xinglin Bay at early urbanization phase) with 2009-2012 observation data as example, we calculated the upper limit of TN and TP capacity in three watersheds and identified the threshold value of urban building land in watersheds using the regional nutrient management (ReNuMa) model, and also predicted the water environmental effects associated with the changes of urban landscape pattern. Results indicated that the upper limit value of TN was 12900, 42800 and 43120 kg, while that of TP was 340, 420 and 450 kg for Yundang, Maluan and Xinglin watershed, respectively. In reality, the environment capacity of pollutants in Yundang Lake was not yet satura-ted, and annual pollutant loads in Maluan Bay and Xinglin Bay were close to the upper limit. How-ever, an obvious upward trend of annual TN and TP loads was observed in Xinglin Bay. The annual pollutant load was not beyond the annual upper limit in three watersheds under Scenario 1, while performed oppositely under Scenario 3. Under Scenario 2, the annual pollutant load in Yundang Lake was under-saturation, and the TN and TP in Maluan Bay were over their limits. The area thresholds of urban building land were 1320, 5600 and 4750 hm2 in Yundang Lake, Maluan Bay and Xinglin Bay, respectively. This study could benefit the regulation on urban landscape planning.城市扩张影响流域水环境质量.从水环境响应出发,模拟预测流域范围内城市建设用地的扩张阈值,可为城市建设用地规划提供客观依据.本文选取完全城市化的筼筜湖流域、半城市化的马銮湾流域和城市化起步阶段的杏林湾流域作为对比研究对象,结合2009—2012年实测数据,运用区域污染物管理模型(ReNuMa),计算3个流域水体污染物总氮(TN)和总磷(TP)环境容量上限,确定流域内城市建设用地面积阈值,并预测城市景观格局演变产生的水环境效应.结果表明: 筼筜湖、马銮湾和杏林湾的TN年负荷上限值分别为12900、42800和43120 kg,TP年负荷上限值分别为340、420和450 kg;现实情境下,筼筜湖水体污染物环境容量尚未饱和,马銮湾与杏林湾的污染物年负荷均接近上限值,杏林湾的TN和TP年负荷存在明显的上升趋势;3个流域污染物年负荷均在模拟情境1下未超标、情境3下超标,情境2下,筼筜湖污染物年负荷均未超标,而马銮湾TN与TP年负荷均处于超标;筼筜湖、马銮湾和杏林湾流域的城市建设用地面积阈值分别为1320、5600和4750 hm2,并据此提出景观格局调整对策建议.
Abstract All‐solid‐state lithium batteries (ASSLBs) are highly promising as next‐generation energy storage devices owing to their potential for great safety and high energy density. This work demonstrates that composite solid polymer electrolyte with vertically‐aligned card‐house structure can simultaneously improve the high rate and long‐term cycling performance of ASSLBs. The vertical alignment of laponite nanosheets creates fast and uniform Li + ion transport channels at the nanosheets/polymer interphase, resulting in high ionic conductivity of 8.9 × 10 −4 S cm −1 and Li + transference number of 0.32 at 60 °C, as well as uniformly distributed solid electrolyte interphase. Such electrolyte is characterized by high mechanical strength, low flammability, excellent structural stability and stable ion transport channels. In addition, the ASSLB cell with the electrolyte and LiFePO 4 cathode delivers a high discharge specific capacity of 124.8 mAh g −1 , which accounts for 85.6% of its initial capacity after 500 cycles at 1C. The reasonable design through structural control strategy by interconnecting the vertically‐aligned nanosheets open a way to fabricate high performance composite solid polymer electrolytes.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
A set of strained-layer GexSi1-x/Si multiple quantum wells has been investigated by electroreflectance (ER) spectroscopy. In the ER spectra we have observed transitions in the quantum wells associated with the critical points E0, E1, as well as E'0. The transitions of E0 and E'0, which are very weak in the bulk material, are apperently enhanced in quantum wells.
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