Adsorption of oxytetracycline from aquaculture wastewater by modified carbon nanotubes: kinetics,isotherms and thermodynamics

Abstract

In the present study, lanthanum modified carbon nanotubes (La-CNTs) were prepared by the impregnation method and used as adsorbents to remove oxytetracycline (OTC) from aquaculture wastewater. La-CNTs were characterized by SEM, EDS, XRD, BET analysis. The effects of adsorbent dosage, concentration of OTC, adsorption time, pH and interfering ions on the adsorption of OTC by La-CNTs were investigated. The optimum adsorbent dosage, OTC concentration, adsorption equilibrium time and pH for OTC adsorption by La-CNTs are 0.03?g, 20?mg/L, 180?min and 7, respectively. The outcome of the kinetics studies showed a significant linear correlation between the experimental results and the quasi-second-order kinetics model. As an adsorption isotherm model, the Langmuir model showed a very good consistency with the adsorption of OTC by La-CNTs, as the maximum adsorption quantity reached 117.23?mg/g. Through the thermodynamic analysis showed that the adsorption of OTC by La-CNTs was an endothermic process of entropy increase, which occurs spontaneously. The predominant forces promoting this adsorption were van der Waals force, π-π electron donor-acceptor interaction, and electrostatic interaction.     

基于单服务器的群上幂指数安全外包计算方案

随着云计算的快速发展和大数据时代的到来,如何将一些耗时的计算任务安全地外包给不完全可信的公共云服务器引起了广泛关注.基于单服务器模型,提出了一个新的具有隐私保护的群域上的幂指数运算安全外包方案GEXP(outsourcing power exponent on a group field),能够有效避免双服务器模型存在的共谋攻击问题.与已有方案相比,方案GEXP能够以100%的概率检测出云服务器返回的错误计算结果,确保了用户对外包计算结果的可完全验证.此外,给出了方案GEXP在现有广泛研究的云存储数据完整性验证的具体应用.     

边缘计算环境下应用驱动的网络延迟测量与优化技术

互联网、移动计算、物联网技术的进步推动了人-机-物环境的深度融合,催生了一大批面向边缘用户的网络搜索、在线社会网络、电子商务、视频监控、智能助理等类型的边缘计算应用.边缘计算应用具有规模巨大、服务质量敏感等特性,对延迟性能提出迫切需求,然而,由于用户访问请求跨边缘网络、广域网、数据中心异构环境,“长尾延迟”问题导致边缘用户的体验质量严重下降.首先综述边缘计算应用的系统架构特征,然后分析长尾延迟的产生原因,分类介绍网络延迟测量的主要理论和方法,并归纳对长尾延迟的优化技术,最后提出在线优化运行环境的思想以及面临的挑战.     

小区集中供热系统循环水泵电耗实测分析

对6个小区集中供热系统的17台循环水泵的电耗、实际运行效率、循环流量进行了实测,分析了造成小区集中供热系统输配能耗较高的原因,结合实例计算了各种能耗损失的大小和所占比例,给出了小区集中供热系统实际需求耗电量指标.     

Stability analysis of closed-loop water system

Aiming at closed-loop water system, by the method that shutting certain subcircuit, and solving the piping network, computing flow deviation of other subcircuits, then analyzing the rules of variation of stability with various factors, following conclusions are obtained: When reducing the resistance in main pipes, increasing resistance of subcircuits, system stability can be improved. Centralized regulation by changing power has no influence on system stability; centralized regulation by changing resistances will decrease system stability. Pump characteristics curve influences system stability, stability of the flat characteristic is superior to the steep one. For direct return system (DRS), the stability of subcircuit which is farthest from the heat source is the worst. For reverse return system (RRS), the stability of subcircuit in the middle of the pipe-network has the worst stability. Overall, stability of RRS is inferior to that of DRS.     

一组采用四星形接线10kV TV故障原因分析

介绍了10kV系统中一组采用四星形接线的TV发生爆炸经过,通过分析其爆炸的原因提出了解决措施.     

Corrosion behaviour of Al1.3CrFeNi chemically complex alloy

In this study, corrosion behaviour of double-phase Al_1.3CrFeNi chemically complex alloy was investigated, including hot corrosion and electrochemical corrosion. Hot corrosion behaviour of Al_1.3CrFeNi alloy was explored in molten 75 wt-% Na₂SO₄?+?25 wt-% NaCl salt. The result revealed that the corrosion kinetic curve of Al_1.3CrFeNi alloy followed the exponential rate rule through mass loss measurement. In addition, it prevented that the formed corrosion layer had obvious stratification including external granular Al₂O₃ and inner porous Cr₂O₃ when corrosion time was up to 100?h. Besides, it should be noted that the Al_1.3CrFeNi alloy was sensitive to the molten salt containing chlorine, which makes the alloy surface leave voids and bring about acceleration of corrosion. Meanwhile, electrochemical corrosion resistance of Al_1.3CrFeNi alloy in NaCl solution with different concentrations (0.6, 1.0 and 2.0?mol?L^?1) was investigated at room temperature. The results revealed that Al_1.3CrFeNi alloy showed superior corrosion resistance in NaCl solution due to the existence of Al and Cr which aid the formation of protective oxide layer.     

Distortions and tensile properties of 15-5PH steel cylinders with EBW and heat treatment

15-5PH steel is one of the martensitic precipitation-hardened stainless steels, which is extensively applied in the aero shafts, and electron beam welding is a significant procedure to manufacture the parts. To verify the dimension accuracies and properties, EBW with oscillation was employed on the cylinders of 15-5PH steel. The welding distortions were measured, and the microstructures and tensile properties of the joints were investigated. The weld appearances of the cylinders were smooth, and the morphology was parallel. After EBW, the shrinkages of the cylinders were above ?0.22?mm, and the welding distortions were ?0.66 to ?1.1‰, and the straightnesses were less than 1‰ due to the distortions. The martensites and a few austenites were in the welds of the cylinders after heat treatment, and the microhardnesses in the welds were 445 HV0.2, which were bigger and more homogeneous than those of the as-welded. The tensile strength and yield strength of the joints were respectively 1300 and 1150?MPa, which were higher than those of the as-welded joints, and the elongation rate of the joints was 10%. The microstructures and properties of the cylinders conformed to the aero shafts, which was attributed to the microstructure transformation with oscillation EBW and heat treatment.     

Kinome-Wide Profiling Identifies Human WNK3 as a Target of Cajanin Stilbene Acid from Cajanus cajan (L.) Millsp.

Pigeon Pea (Cajanus cajan (L.) Millsp.) is a common food crop used in many parts of the world for nutritional purposes. One of its chemical constituents is cajanin stilbene acid (CSA), which exerts anticancer activity in vitro and in vivo. In an effort to identify molecular targets of CSA, we performed a kinome-wide approach based on the measurement of the enzymatic activities of 252 human kinases. The serine-threonine kinase WNK3 (also known as protein kinase lysine-deficient 3) was identified as the most promising target of CSA with the strongest enzymatic activity inhibition in vitro and the highest binding affinity in molecular docking in silico. The lowest binding affinity and the predicted binding constant pKi of CSA (−9.65 kcal/mol and 0.084 µM) were comparable or even better than those of the known WNK3 inhibitor PP-121 (−9.42 kcal/mol and 0.123 µM). The statistically significant association between WNK3 mRNA expression and cellular responsiveness to several clinically established anticancer drugs in a panel of 60 tumor cell lines and the prognostic value of WNK3 mRNA expression in sarcoma biopsies for the survival time of 230 patients can be taken as clues that CSA-based inhibition of WNK3 may improve treatment outcomes of cancer patients and that CSA may serve as a valuable supplement to the currently used combination therapy protocols in oncology.