Study on Electrokinetic Remediation of Cadmium-contaminated Soil

In order to improve electrokinetic remediation efficiency of cadmium-contaminated soil,the effects of electric field intensity,remediation time and electrolyte on removal rate of total Cd in Cd-contaminated soil by electrokinetic remediation were studied through the preparation of Cd-contaminated soil and the construction of electrokinetic remediation equipment. The results showed that under the same condition,with the electric field intensity increasing from 2. 5 to 3 V/cm,the total Cd removal rate increased by 10. 62%,and with the increase of the electric field intensity from 3 to 3. 5 V/cm,the removal rate increased by 1. 87%;when the remediation time was prolonged from 72 to 96 h,the removal rate of total Cd increased by 6. 68%,and with the remediation time prolonged from 96 to120 h,the removal rate of total Cd increased by 8. 75%; and with the remediation time prolonged from 120 to 144 h,the removal rate of total Cd only increased by1. 07%. Compared with citric acid as the electrolyte,the acetic acid group improved the remediation efficiency by 12. 14% and the total energy consumption by62. 13%,while the hydrochloric acid group improved the remediation efficiency by 18. 04% and the total energy consumption by 187. 9%. Comprehensively from total Cd removal rate and energy consumption,the remediation effect was the best under the electric field intensity of 3 V/cm and the electrokinetic time of 120 h with acetic acid as the electrolyte,which achieved a total Cd removal rate of 41. 95%.

BOUNDARY BLOW-UP RATE OF THE LARGE SOLUTION FOR AN ELLIPTIC COOPERATIVE SYSTEM

In this article we consider positive large solution of cooperative systems of the form -△u1=λ1u1 + a1u1u2^q1 -b1(x)u1^p1+1,-△u2=λ2u2 + a2u1^q2u2 -b2(x)u2^p2+1 in a bounded smooth domainΩ■ R^N(λi ∈ R, ai, bi>0, 0 < qi < pj, i, j ∈{1, 2}, i ≠ j), Based on the construction of certain sup and sub-solution, we show existence, uniqueness and blow-up rate of the large solution.

The BBC News Hunter:A Novel Crawler for BBC News

In order to distinguish and extract the topic information from other interferential information on the BBC news website for the study in social computing,the BBC News Hunter was proposed in this paper.The whole system consists of 6 subsystems,respectively named:UI,Control,Download,Analysis,Storage and Log.Numerical experiments show that satisfactory results can be obtained from the BBC news website,whose average accuracy as well as efficiency are acceptable.

Burden levels of polychlorinated dibenzo-p-dioxins, dibenzofurans, and polychlorinated biphenyls in typical edible meat animals

The concentrations and distributions of polychlorinated dibenzo-p-dioxins(PCDDs), polychlorinated dibenzofurans(PCDFs), and polychlorinated biphenyls(PCBs) in the whole blood and meat of eight typical edible animals(chicken, donkey, horse, cattle, rabbit, sheep, duck,and pig) were illustrated. Total concentrations of polychlorinated dibenzo-p-dioxins and dibenzofurans(PCDD/Fs) and PCBs(on a basis of liquid volume) in animal bloods were 142-484 pg/L and 46-62 ng/L, respectively. Total concentrations of PCDD/Fs and PCBs(on a basis of dry weight(dw) and lipid weight(lw)) in animal meat samples were 0.47-1090 pg/g dw(0.47-4513 pg/g lw) and 7.2-23 ng/g dw(10-776 ng/g lw), respectively. TEQs for both PCDD/Fs and PCBs in animal blood and meat samples were(67 ± 27) pg/L and(5.3 ± 14) pg/g dw(24± 56 pg/g lw), respectively. Besides, the dietary intakes of PCDD/Fs and PCBs were also estimated. Chicken and pig contributed more TEQs than other animals. Chicken contributed the most(95%) with high toxicity, followed by pig(3.4%) with high consumption. The dietary intake of chicken might pose risks to consumers who prefer to eat chicken products, who should comprehensively consider the essential nutrients and contaminants in food during dietary intake.

Heterogeneous Deformation Behaviors of an Inertia Friction Welded Ti_(2)AlNb Joint:an In‑situ Study

A defect-free Ti_(2)AlNb joint has been obtained by the inertia friction welding(IFW)technology.The weld zone(WZ)is composed of B2 grains refined by discontinuous dynamic recrystallization and enhanced by grain refinement strengthening.And the average microhardness decreases by about 30 HV from the WZ to the base metal.In-situ SEM analysis reveals that the heterogeneous structure of the joint causes strong strain partitioning during tensile deformation.The microcrack initiation occurs at the interface of the initial B2 phases and B2/O boundaries.Owing to stress concentration,the multi-slip bands and cracks tend to generate in the heat-affected zone(HAZ),causing a premature fracture.

神经内镜辅助显微镜切除颅咽管瘤的临床研究

目的探讨神经内镜辅助显微镜技术在颅咽管瘤手术中的作用和价值。方法回顾性收集胜利油田中心医院神经外科和头颈血管外科自2015年1月至2017年11月收治的42例行神经内镜辅助显微镜切除的颅咽管瘤患者作为神经内镜辅助组,收集自2013年1月至2014年12月收治的45例行单纯经显微镜切除的颅咽管瘤患者作为单纯显微镜组,通过对2组患者的肿瘤切除率、术后并发症发生率及术后复发率进行比较,从而评价手术效果。结果神经内镜辅助组的肿瘤全切除率97.62%,术后血管痉挛发生率7.14%;单纯显微镜组的肿瘤全切除率80.00%,术后血管痉挛发生率22.22%,2组比较差异均具有统计学意义(P<0.05)。2组患者的术中垂体柄保留率、术后并发症(颅神经损伤、电解质紊乱、脑脊液漏、腺垂体功能减退、尿崩、颅内感染、死亡)发生率及术后复发率比较,差异均无统计学意义(P>0.05)。结论神经内镜辅助显微镜切除颅咽管瘤既能提高肿瘤全切除率又能降低并发症发生率,提高手术疗效。

Enhanced activation of peroxydisulfate by strontium modified BiFeO3 perovskite for ciprofloxacin degradation

A series of Sr-doped BiFeO3 perovskites(Bi1-xSrxFeO3,BSFO)fabricated via sol-gel method was applied as peroxydisulfate(PDS)activator for ciprofloxacin(CIP)degradation.Various technologies were used to characterize the morphology and physicochemical features of prepared BSFO samples and the results indicated that Sr was successfully inserted into the perovskites lattice.The catalytic performance of BiFeO3 was significantly boosted by strontium doping.Specifically,Bi0.9Sr0.1FeO3(0.1 BSFO)exhibited the highest catalytic performance for PDS activation to remove CIP,where 95%of CIP(10 mg/L)could be degraded with the addition of 1 g/L 0.1 BSFO and 1 mmol/L PDS within 60 min.Moreover,0.1 BSFO displayed high reusability and stability with lower metal leaching.Weak acidic condition was preferred to neutral and alkaline conditions in 0.1 BSFO/PDS system.The boosted catalytic performance can be interpreted as the lower oxidation state of Fe and the existence of affluent oxygen vacancies generated by Sr doping,that induced the formation of singlet oxygen(^1O_(2))which was confirmed as the dominant reactive species by radical scavenging studies and electron spin resonance(ESR)tests.The catalytic oxidation mechanism related to major ^1O_(2) and minor free radicals was proposed.Current study opens a new avenue to develop effective A-site modified perovskite and expands their application for PDS activation in wastewater remediation.

Cadmium tolerance and accumulation in fifteen wetland plant species from cadmium-polluted water in constructed wetlands

Variations in cadmium （Cd） tolerances and accumulations among fifteen wetland plant species in moderately （0.5mg.L-1） and heavily （1.0mg-L 1） Cd- polluted wastewaters were investigated in constructed wetlands. Cd removal efficiencies from the wastewaters were more than 90%, and 23.5% and 16.8% of the Cd in the water accumulated in wetland plants for 0.5 and 1.0 mg - U1 Cd treatments, respectively. The variations among the plant species were 29.4-fold to 48.7-fold in plant biomasses, 5.4-fold to 21.9-fold in Cd concentrations, and 13.8-fold to 29.6-fold in Cd accumulations. The plant species were also largely diversified in terms of Cd tolerance. Some species were tolerant of heavy Cd stress, and some others were sensitive to moderate Cd level. Four wetland plant species were selected for the treatment of Cd-polluted wastewater for their high Cd accumulating abilities and relative Cd tolerances. Plant Cd quantity accumulations are correlated positively and significantly （P 〈 0.05） with plant biomasses and correlated positively but insignificantly （P 〉 0.05） with plant Cd concentra- tions. The results indicate that the Cd accumulation abilities of wetland plant species are determined mainly by their biomasses and Cd tolerances in growth, which should be the first criteria in selecting wetland plant species for the treating Cd-polluted wastewaters. Cd concentration in the plants may be the second consideration.

An intelligent algorithm for coherent sound source localization based on a strong tracking filter

Background noise is inevitable when sensor arrays are used for aeroacoustic measurements in wind tunnels. The direct removal of background noise, however, would affect the measurement accuracy. In particular, the existing array signal processing algorithms are either invalid or inefficient for removing the noise that is coherent with the signal of interest. In this paper, an intelligent algorithm is developed to localize the coherent sound sources and background noise in real time by iteratively checking the collected data from the array. The proposed method can automatically adjust the suboptimal fading factor to extract useful information as much as possible in residual sequence. This algorithm is tested in simulations and then demonstrated in an experiment.Compared to the two existing methods, the results indicate that the new method has a good phase-shift tracking ability and rapid estimation-error convergence speed, and can achieve an acceptable performance even for low-cost acoustic sensors. Overall, the proposed method should assist array beamforming and hence benefit aeroacoustic measurement.

A viral propagation model with a nonlinear infection rate and free boundaries

In this paper we put forward a viral propagation model with a nonlinear infection rate and free boundaries and investigate the dynamical properties.This model is composed of two ordinary differential equations and one partial differential equation,in which the spatial range of the first equation is the whole space R,and the last two equations have free boundaries.As a new mathematical model,we prove the existence,uniqueness and uniform estimates of the global solution,and provide the criteria for spreading and vanishing,and the long time behavior of the solution components u,v and w.Comparing this model with the corresponding ordinary differential systems,the basic reproduction number R_(0) plays a different role.We find that when R_(0)≤1,the virus cannot spread successfully;when R_(0)>1,the successful spread of the virus depends on the initial value and varying parameters.