确保层浇质量的新设计

设计两套独立的浇注系统，配以带有隔板的双直浇口杯，采用“调包”浇注工艺，能确保层浇及有效地控制流经各层的金属液重。多年生产实践表明，该工艺简单、易行、可靠，可行性、可操作性强，铸件质量显著提高；该工艺措施对生产高大、复杂、质量要求较高的铸件有较大的参考和借鉴价值。

Security Risk Analysis on the Nutrients and Heavy Metals of Biogas Slurry in Agricultural Application

[Objective] This study was to provide scientific basis for the security application of biogas slurry in agriculture through the analysis on the security risk of nu- trients and heavy metals of biogas slurry in agricultural application. [Method] The components of the slurry produced by the anaerobic digestion of straws and manures were systematically analyzed. Different types of biogas slurry with different concentrations were used to conduct the germination test. [Result] The types and proportions of raw materials, and alkali pretreatment affected the compositions and nature of the biogas slurry. Alkali pretreatment could reduce the contents of heavy metals and improved the contents of nitrogen, phosphorous, organic matter and available components. The contents of heavy metals in the biogas slurry were as follows： Cd of 8.76 μg/kg, Cr of 52μg/kg, Pb of 210 μg/kg, Hg of 0.512 μg/kg, As of 140μg/kg, and the contents of Cu and Zn were the highest among the heavy metals, respectively, 279 and 680 μg/kg. All the contents were under the limit standards of the urban wastes for agricultural use. The germination tests of the seeds verified that the slurry with the concentration of lower than 5% could accelerate the germination, while the salt stress could inhibit the growth of seedlings in the slurry. [Conclusion] When the dung are uses as the raw materials for fermentation, appropriate control should be conducted on the feeding proportion or the heavy metals should be pre-removed; when the slurry is used as the liquid fertilizer to apply in the farmland, the dilution or desalting treatment should be conducted at first.

Effects of Biogas Slurry Irrigation on Heavy Metal Contents in Soils

[Objective] This study aimed to investigate the effects of biogas slurry irri- gation on heavy metal contents in soils. [Method] A pot experiment was carried out to investigate the effects of biogas slurry irrigation on the accumulation of heavy metals in soils by measuring the contents of Cu, Zn, Pb, Cr and Cd in different soil layers. [Result] The results showed that original and 30-fold biogas slurry increased the contents of Cu, Zn, Pb, Cd and Cr in soils; Cr might partially reach an exces- sive level in a short term. Biogas slurry irrigation increased the downward migration velocity of Cu and reduced the downward migration velocity of Zn in soils. [Conclu- sion] Biogas slurry irrigation influences the contents of heavy metals, and long-term application of biogas slurry will lead to the accumulation of heavy metals in soils.

Effect of Organic Materials on Speciation of Copper inSoil Solution

Incubation of two soils, a red soil derived from granodiorte and a fluvo-aquic soil from alluvial deposit,with rice straw, Chinese milk vetch and pig manure under submerged condition were conducted to study thespecies of Cu in soil solutions as affected by the organic materials. The organic materials increased totalsoluble Cu by raising dissolved organic carbon (DOC) in soil solution when the solution pH values were belowthe range in which Cu deposited quickly. When the solution pH rose to this range, the increase of DOCdid not raise total soluble Cu. Total soluble Cu in all the treatments dropped with incubation time. Afteradding organic materials labile Cu dropped with incubation time and decreased sharply in the pH range ofCu precipitation. Addition of organic materials enhanced slowly labile Cu but depressed the ratio of labileCu to total soluble Cu. Slowly labile Cu decreased with incubation time. Stepwise multiple linear regressionanalysis showed that total soluble Cu was positively correlated with Eh and DOC (P=0.0025), labile Cuwas negatively correlated with pH (P=0.011 8), and slowly labile Cu was positively correlated with Eh andDOC (P=0.002 2). Both the labile and slowly labile Cu were correlated with total soluble Cu at extremelysignificant levels.

Retention of clay-solidified grouting curtain to Cd^(2+), Pb^(2+) and Hg^(2+) in landfill of municipal solid waste

The effects of components and their ratio of grouts on anti-seepage capability of clay-solidified grouting curtain and its permeability of heavy metal cations were investigated by permeating experiments, using reactive solute transport model to study the permeation of heavy metals (Cd2+, Pb2+ and Hg2+). The study of permeating for different mixture ratios of cement and clay indicates that hydraulic conductivity of clay-solidified grouting curtain with different ratios of solid to liquid or with the same ratio of solid to liquid but with different ratios of cement to clay is changed. The laboratory simulation test results also show that precipitates produced in heavy metal cation migration process in curtain block up water flowing passage which makes the hydraulic conductivity of the solution-permeated curtain decrease with the leakage time. The permeation velocities for different heavy metal cations vary with ionic concentration, exchange capacity and ion radius etc. The test results indicate that the permeation rapidity order of heavy metals cations in clay-solidified grouting curtain is Hg2+>Pb2+ in the same experimental circumstance. In addition, permeability for different mixture ratios and antisepsis capabilities of clay-solidified grouting curtain were studied in tests.

Removal of Pb^(2+) and Cd^(2+) by adsorption on clay-solidified grouting curtain for waste landfills

Pb2+ and Cd2+ in leachate were adsorbed on clay-solidified grouting curtain for waste landfills with equilibrium experiment. The cation exchange capacity was determined with ammonium acetate. And the concentration of heavy metal cations in leachate was determined with atomic absorption spectrophotometer. Their equilibrium isotherms were measured, and the experimental isotherm data were analyzed by using Freundlich and Langmuir models. The results show that the adsorption capacities of the heavy metal cations are closely related to the compositions of clay-solidified grouting curtain, and the maximum adsorption appears at the ratio of cement to clay of 2∶4 in the experimental conditions. At their maximum adsorption and pH 5.0, the adsorption capacities of Pb 2+ and Cd 2+ are 16.19mg/g and 1.21mg/g. The competitive adsorption coefficients indicate that the adsorption of clay-solidified grouting curtain for Pb2+ is stronger than that for Cd 2+ . The adsorption process conforms to Freundlich’s model with related coefficient higher than 0.996.

Biosorption of Cr(Ⅳ),Cr(Ⅲ),Pb(Ⅱ) and Cd(Ⅱ) from Aqueous Solutions by Sargassum wightii and Caulerpa racemosa Algal Biomass

Heavy metal pollution is one of the most important environmental problems today.Biosorption is an innovative tech-nology that employs biological materials to accumulate heavy metals from waste water through metabolic process or physicochemi-cal pathways of uptake.Even though several physical and chemical methods are available for removal of heavy metals,currently many biological materials such as bacteria,algae,yeasts and fungi have been widely used due to their good performance,low cost and large quantity of availability.The aim of the present study is to explore the biosorption of toxic heavy metals,Cr（VI）,Cr（III）,Pb（II） and Cd（II） by algal biomass obtained from algae Sargassum wightii（brown） and Caulerpa racemosa（green）.Biosorption of algal biomass was found to be biomass concentration-and pH-dependent,while the maximal biosorption was found at pH 5.0 and with the metal concentration of 100 mg L-1.S.wightii showed the maximal metal biosorption at the biomass concentration of 25 g L-1,followed by C.racemosa with the maximal biosorption at 30 g L-1.S.wightii showed 78% biosorption of Cr（VI）,Cr（III）,Pb（II） and Cd（II） ions.C.racemosa exhibited 85% biosorption of Cd（II） and Cr（VI）,and 50% biosorption of Cr（III） and Pb（II）.The results of our study suggest that seaweed biomass can be used efficiently for

Selective removal of heavy metal ions from aqueous solutions with surface functionalized silica nanoparticles by different functional groups

The industrial silica fume pretreated by nitric acid at 80 °C was re-used in this work. Then, the obtained silica nanoparticles were surface functionalized by silane coupling agents, such as(3-Mercaptopropyl) triethoxysilane(MPTES) and(3-Amincpropyl) trithoxysilane(APTES). Some further modifications were studied by chloroaceetyl choride and 1,8-Diaminoaphalene for amino modified silica. The surface functionalized silica nanoparticles were characterized by Fourier transform infrared(FI-IR) and X-ray photoelectron spectroscopy(XPS). The prepared adsorbent of surface functionalized silica nanoparticles with differential function groups were investigated in the selective adsorption about Pb2+, Cu2+, Hg2+, Cd2+ and Zn2+ions in aqueous solutions. The results show that the(3-Mercaptopropyl) triethoxysilane functionalized silica nanoparticles(SiO2-MPTES) play an important role in the selective adsorption of Cu2+ and Hg2+, the(3-Amincpropyl) trithoxysilane(APTES) functionalized silica nanoparticles(SiO2-APTES) exhibited maximum removal efficiency towards Pb2+ and Hg2+, the 1,8-Diaminoaphalene functionalized silica nanoparticles was excellent for removal of Hg2+ at room temperature, respectively.

Facile fabrication of spherical flower-like Mg(OH)2 and its fast and efficient removal for heavy metal ions

Spherical flower-like Mg(OH)_(2) was fabricated from MgSO_(4) effluent and its adsorption performance for heavy metal ions was evaluated.The appropriate fabrication conditions are as follows:Mg^(2+)/NH4OH molar ratio of 1:0.5,temperature of 120°C and time of 1 h at Mg^(2+)concentration of 2 mol/L.Spherical flower-like Mg(OH)_(2) composed of ultra-thin sheets exhibits an excellent adsorption ability for Ni^(2+),Cu^(2+),Zn^(2+),Pb^(2+),Fe^(3+)and Co^(2+),and the adsorption reaches the equilibrium in 6 min.The maximum adsorption capacities of the studied heavy metal ions onto Mg(OH)_(2) at 20°C are 58.55,85.84,44.94,485.44,625.00 and 27.86 mg/g,respectively.The adsorption is well fitted by the Langmuir model,indicating that the adsorption is monolayer.The adsorption kinetics follows the pseudo-second-order model.Chemisorption is the operative mechanism.Spherical flower-like Mg(OH)_(2) is a qualified candidate for heavy metal ions removal.

Heavy metals accumulation effect in rabbit body fluids after smoking

Concentration of heavy metals in blood and urine of rabbit after inhaling three different kinds of cigarette was studied through the animal passive smoking pattern. The samples were prepared by nitric acid solution digestion and determination of seven kinds of heavy metals including Hg, Se, Sn, Pb, Cd, Ni and Cr was performed by inductively coupled plasma-atomic emission spectrometry （ICP-AES）. The ICP-AES method was established with good precision and accuracy, relative standard deviation （n=6） was between 2.9% and 5.9%, and the recovery was in the range of 95.0%-104.2%. Concentration of six heavy metals increases in some extent in blood and urine after period of smoking and the increasing of heavy metals in blood and urine all shows time dependence. Significantly higher heavy metal levels are observed in the blood and urine of the cigarette inhaling rabbits in the exposed group. The concentration of six kinds of heavy metals in the blood of the rabbit increases after 16 weeks exposing to cigarette smoking. Three times of rig, ten times of Se and trace amount ofPb, Cd, Ni and Cr are detected in the blood after 16 weeks of smoking. For urine samples, about three times of Hg, two times of Se, five times of Pb and trace amount of Cd are detected after 16 weeks of inhalation of cigarette. Comparatively, higher concentration of heavy metals are detected after inhaling of Nise cigarette.

Determination of heavy metal ion in landfill leachate with solvent extracting ＆ fluorescence quenching method

Add the masking agent and biscyclohexanoneoxalyldihydraone into the diluted clarificd liquid of the landfill leachate which was treatmented by digestion and centrifugal filtration to complexate all heavy metal ion in the trcatmented liquid, and extracted using CHCl3 many time, then it were demasking and decomposing respectively, and adjusted different pH and formed Me^n＋-PAN coordination compound when these metal ion reaction with PAN. The Fluoresence quenching of Rh6G （λex/λem=543mn/558nm） when the metal ion coordination compound was add into the Rh6G solution step by step, the quenching intensity was directly proportional to the concentration of the metal ion in the certain range. So a new method of fast and simple for determination of trace metal ion in landfill lcachate was established to determine metal ion in sample of different landfill leachate in Three Gorge Water Reservoir, and comparison the classic assay method with satisfactory results.

Autonomous convergence and divergence of the self-powered soft liquid metal vehicles

Conventional rigid machines, even biological systems in nature, generally do not own the capabilities like autonomous convergence or divergence. Here, such extraordinary behavior was demonstrated for the first time with the liquid metal vehicle. This synthetic soft machine fueled with an aluminum flake could initiate its autonomous locomotion in an opentop circular channel containing NaOH solution, like a running vehicle. If cutting a large machine into several smaller separately running vehicles, each of them still resumes its traveling state along the original track and chases each other. If the volumes of such dispersive vehicles were close to each other and they were all squeezed in the channel, the vehicles would move syn-chronously with oscillation. Otherwise, such self-motion would become desynchronized with interval between the inequable vehicles decreased gradually. If their volumes were significantly different, and the smaller vehicles were not squeezed in the channel, the faster vehicle would overtake the slower ones, until they finally coalesced seamlessly. The assembled vehicle could deform itself along with change of its velocity. This finding may shedlight on future researches on smart material, fluid mechanics and soft matter to self-fueled machine and biomimics. It would also offer opportunities for constructing self-reconfigurable soft robots.