Abstract: The Soil and Water Assessment Tool (SWAT) model was evaluated for estimation of continuous daily flow based on limited flow measurements in the Upper Oyster Creek (UOC) watershed. SWAT was calibrated against limited measured flow data and then validated. The Nash‐Sutcliffe model Efficiency (NSE) and mean relative error values of daily flow estimations were 0.66 and 15% for calibration, and 0.56 and 4% for validation, respectively. Also, further evaluation of the model’s estimation of flow at multiple locations was conducted with parametric paired t‐test and nonparametric sign test at a 95% confidence level. Among the five main stem stations, four stations were statistically shown to have good agreement between predicted and measured flows. SWAT underestimated the flow of the fifth main stem station possibly because of the existence of complex flood control measures near to the station. SWAT estimated the daily flow at one tributary station well, but with relatively large errors for the other two tributaries. The spatial pattern of predicted flows matched the measured ones well. Overall, it was concluded from the graphical comparisons and statistical analyses of the model results that SWAT was capable of reproducing continuous daily flows based on limited flow data as is the case in the UOC watershed. 相似文献
The shape memory behavior of PLLA (poly(l-lactide)) and chitosan/PLLA composites was studied. PLLA and chitosan were compounded to fabricate novel materials which
may have biodegradability and biocompatibility. Chitosan does not significantly affect the glass and melting transition temperature
of the PLLA. Both the pure PLLA and chitosan/PLLA composites showed shape memory effect arising from the viscoelastic properties
of PLLA comprised of semi crystalline structures. The shape recovery ratio of the chitosan/PLLA composites decreased significantly
with increasing chitosan contents due to the incompatibility between PLLA and chitosan. Phase separation structures of the
composites were observed by using atomic force microscopy. To obtain good shape memory effect, the chitosan content should
be below 15 wt%. 相似文献
<正>1.Editor's note On 30 November 2016,the Brookings-Tsinghua Center for Public Policy(BTC),Caixin Video,and Columbia Global Centers(Beijing)jointly hosted a Seminar on the Future of Global Governance and Climate Change Action in a Changing Political Landscape.Leading experts on China's environmental policy and climate 相似文献
European forestry is facing many challenges, including the need to adapt to climate change and an unprecedented increase in forest damage. We investigated these challenges in a Norway spruce-dominated mountain region in Central Europe. We used the model Sibyla to explore forest biomass production to the year 2100 under climate change and under two alternative management systems: the currently applied management (CM), which strives to actively improve the forest’s adaptive capacity, and no management (NM) as a reference. Because biodiversity is thought to have mostly positive effects on the adaptive capacity of forests and on the quality of ecosystem services, we explored how climate change and management affect indicators of biodiversity. We found a differential response across the elevation-climatic gradient, including a drought-induced decrease in biomass production over large areas. With CM, the support of non-spruce species and the projected improvement of their growth increased tree species diversity. The promotion of species with higher survival rates led to a decrease in forest damage relative to both the present conditions and NM. NM preserved the high density of over-matured spruce trees, which caused forest damage to increase. An abundance of dead wood and large standing trees, which can increase biodiversity, increased with NM. Our results suggest that commercial spruce forests, which are not actively adapted to climate change, tend to preserve their monospecific composition at a cost of increased forest damage. The persisting high rates of damage along with the adverse effects of climate change make the prospects of such forests uncertain. 相似文献
我国本土水生生物稀有鮈鲫(Gobiocypris rarus Ye et Fu,1983年)是一种优良的试验用鱼,具备成为模式生物必要条件。本文总结了稀有鮈鲫生物生态学研究情况,分析了稀有鮈鲫在多个应用领域与模式生物斑马鱼、青鳉存在的不足和差距,同时借鉴发达国家推动模式生物的实践经验,提出了针对性建议。 相似文献
苏丹红是一种人工合成偶氮染料,可引起肝脏及泌尿系统等多个脏器的肿瘤,但苏丹红对生殖系统的毒性研究较少。本研究以昆明小鼠为受试对象,探讨苏丹红I对小鼠卵巢组织Caspase-3和Ki-67表达的影响。将24只昆明小鼠随机分为:对照组、低剂量(60 mg·kg~(-1))、中剂量(120 mg·kg~(-1))、高剂量(240 mg·kg~(-1))4组,6只/组。胃灌4周,4周末处死。HE染色观察各组卵巢组织病理变化,免疫组化法检测卵巢组织Caspase-3和Ki-67表达,Real time PCR检测卵巢组织Caspase-3和Ki-67 m RNA表达,Western blotting检测卵巢组织中Ki-67及Caspase-3蛋白表达。与对照组比较,实验组卵巢中Caspase-3阳性细胞率显著升高(P0.05),而Ki-67阳性细胞率显著降低(P0.05),Real time PCR及Western blotting结果与免疫组化法结果一致。本实验发现苏丹红染毒后颗粒细胞的Caspase-3表达增加,且Caspase-3表达呈剂量依赖性,但Ki-67表达受到抑制。 相似文献
This paper studied the biofilm properties and corrosion behavior of sulfate reducing bacteria (SRB) on stainless steel 316L (SS316L) surface in circulating cooling water system with and without additives including hydroxy ethyl fork phosphonic acid (HEDP), dodecyl dimethyl benzyl ammonium chlotide (1227) and NaClO. Biochemical technique, electrochemical technology, X-ray photoelectron spectroscopy (XPS) and scanning electron microscope (SEM) were used. The results show that the extracellular polymeric substance (EPS) in biofilm attached on the SS316L surface mainly contain proteins and polysaccharides, the contents are 98 ug·cm-2 and 635ug·cm-2, respectively. The polysaccharides were cut by 1227 about 80%, while 55% by NaClO. The proteins were reduced by NaClO about 53%, while only 30% by 1227. The potentiodynamic polarization shows that the corrosion potential of SS316L was enhanced from -0.495 V to -0.390 V by the chemical additives, delaying the occurrence of the corrosion. And the corrosion rate was also reduced from 5.19 × 10-3 mm·a-1 to 2.42 × 10-3 mm·a-1. But NaClO still caused pitting corrosion after sterilizing the bacteria, while 1227 can form a protective film on the surface of SS316L. Though HEDP contribute to the bacteria activity, it can enhance the breakdown potential. XPS results confirmed that 1227 can change the value of C:O in the biofilm attached on metal surface, and NaClO can eliminate the existence of amidogen. This study would provide some recommendations for the selection of chemical additives in the thermal power plant.