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991.
The study examined the adsorption of Pb(Ⅱ) ions from aqueous solution onto chitosan, chitosan-GLA and chitosan-alginate beads.Several important parameters influencing the adsorption of Pb(Ⅱ) ions such as initial pH, adsorbent dosage and different initial concentration of Pb(Ⅱ) ions were evaluated. The mechanism involved during the adsorption process was explored based on ion exchange study and using spectroscopic techniques. The adsorption capacities obtained based on non-linear Langmuir isotherm for chitosan, chitosan-GLA and chitosan-alginate beads in single metal system were 34.98, 14.24 and 60.27 mg/g, respectively. However,the adsorption capacity of Pb(Ⅱ) ions were reduced in the binary metal system due to the competitive adsorption between Pb(Ⅱ) and Cu(Ⅱ) ions. Based on the ion exchange study, the release of Ca~(2+), Mg~(2+), K~+ and Na~+ ions played an important role in the adsorption of Pb(Ⅱ) ions by all three adsorbents but only at lower concentrations of Pb(Ⅱ) ions. Infrared spectra showed that the binding between Pb(Ⅱ) ions and the adsorbents involved mostly the nitrogen and oxygen atoms. All three adsorbents showed satisfactory adsorption capacities and can be considered as an efficient adsorbent for the removal of Pb(Ⅱ) ions from aqueous solutions. 相似文献
992.
993.
隔油-共沉淀-Fenton预处理制药废水 总被引:1,自引:0,他引:1
采用隔油-共沉淀-Fenton法对含有大量的苯、甲苯、铝及苯甲酮的制药废水进行处理。经隔油处理,COD由147 490.8 mg/L降至139 518.4 mg/L,后通过调节pH值来去除大部分的铝离子,pH=7时效果最佳,COD大约降至10 000 mg/L。Fenton最佳氧化条件为:pH为7,H2O2的投加量为1.6 g/L,H2O2和Fe2+的投加量比为14,反应去除时间为5 h,在此条件下COD降为840 mg/L,去除效率为91.6%;Fenton氧化预处理后废水的可生化性也得到较大提高。 相似文献
994.
详细论述了光纤布拉格光栅的传感机制和光纤光栅温度传感及其感温火灾报警工作原理,以及感温光纤光栅报警器在油库原油储罐消防报警中的应用. 相似文献
995.
城市供水水质监管机制存在的问题及对策研究 总被引:1,自引:0,他引:1
为了保障城市供水水质安全卫生,分析多层面水质监管存在的问题和原因,提出具体对策:构建职责明确的企业自检、行业监测、行政监督制度,实现监管独立;打破信息孤岛,建立跨部门的水源水质监测防治委员会;实行水质产权化管理;建立纵向和横向信息沟通网络平台;建立饮用水断面水质指标评价体系和面向公众的水质指标综合评价体系;优化自备井和二次供水监管主体;建立社区用水协会,形成供水部门、公众和监管主体三位一体的信息渠道。 相似文献
996.
Measurement of flow speed in the channels of novel threadlike structures on the surfaces of mammalian organs 总被引:1,自引:0,他引:1
There have been several reports on novel threadlike structures (NTSs) on the surfaces of the internal organs of rats and rabbits
since their first observation by Bonghan Kim in 1963. To confirm this novel circulatory function, it is necessary to observe
the flow of liquid through the NTS as well as the structurally corroborating channels in the NTS. In this article, we report
on the measurement of the flow speed of Alcian blue solution in the NTSs on the organ surfaces of rabbits, and we present
electron microscopic images depicting the cribrous cross-section with channels. The speed was measured as 0.3 ± 0.1 mm/s,
and the flow distance was up to 12 cm. The flow was unidirectional, and the phase contrast microscopic images showed that
the NTSs were strongly stained with Alcian blue. The ultrastructure of the NTSs revealed by cryo-scanning electron microscopy
and high-voltage electron microscopy showed that (1) there were cell-like bodies and globular clumps of matter inside the
sinus of the channel with thin strands of segregated zones which is a microscopic evidence of the liquid flow, (2) the sinuses
have wall structures surrounded with extracellular matrices of collagenous fibers, and (3) there exists a cribriform structure
of sinuses. To understand the mechanism for the circulation, a quantitative analysis of the flow speed has been undertaken
applying a simplified windkessel model. In this analysis, it was shown that the liquid flow through the NTSs could be due
to peristaltic motion of the NTS itself.
Baeckkyoung Sung and Min Su Kim contributed equally to this work. 相似文献
997.
Feigning death is a method of self-defense employed among a wide range of prey species when threatened by predator species. This paper reports on death-feigning behavior by the fire ant, Solenopsis invicta, during intraspecific aggression among neighboring fire ant workers. Days-old workers responded to aggression by death feigning, weeks-old workers responded by fleeing and months-old workers responded by fighting back. By feigning death, days-old workers were four times more likely to survive aggression than older workers. From a proximate perspective, retaliation by young workers against aggressive older workers is certain to fail. With their relatively soft exoskeleton, young workers would be prone to injury and death and unable to execute an effective attack of biting or stinging older workers with harder exoskeletons. From an ultimate perspective, death feigning allows young workers to survive and contribute to brood care and colony growth, both of which are essential to queen survival and fitness. 相似文献
998.
999.
MiSeon Lee GeunAe Park MinJi Park JongYoon Park JiWan Lee SeongJoon Kim 《环境科学学报(英文版)》2010,22(6):826-833
This study evaluated the reduction e ect of non-point source pollution by applying best management practices (BMPs) to a 1.21 km2
small agricultural watershed using a SWAT (Soil andWater Assessment Tool) model. Two meter QuickBird land use data were prepared
for the watershed. The SWAT was calibrated and validated using daily streamflow and monthly water quality (total phosphorus (TP),
total nitrogen (TN), and suspended solids (SS)) records from 1999 to 2000 and from 2001 to 2002. The average Nash and Sutcli e
model e ciency was 0.63 for the streamflow and the coe cients of determination were 0.88, 0.72, and 0.68 for SS, TN, and TP,
respectively. Four BMP scenarios viz. the application of vegetation filter strip and riparian bu er system, the regulation of Universal
Soil Loss Equation P factor, and the fertilizing control amount for crops were applied and analyzed. 相似文献
1000.
In the present study,a physically-based hydraulic modeling tool and a data-driven approach using artificial neural networks (ANNs) were evaluated for their ability to simulate the fate and transport of microorganisms in a water system.To produce reliable data,a pipe network was constructed and a series of experiments using a fecal coliform indicator (Escherichia coli 15597) was conducted.For the physically-based model,morphological (pipe size,link length,slope,etc.) and hydraulic (flow rate) conditions were used as input variables,and for ANNs,water quality parameters (conductivity,pH,and turbidity) were used.Both approaches accurately described the fate and transport of microorganisms (physically-based model: correlation coefficient (R) in the range of 0.914 – 0.977 and ANNs: R in the range of 0.949 – 0.980),with the exception of one case at a low flow rate (q = 31.56 cm 3 /sec).This study also indicated that these approaches could be complementarily utilized to assess the vulnerability of water facilities and to establish emergency plans based on hypothetical scenarios. 相似文献