单细胞视角下铅的体内代谢与检测

在全球工业需求和储能需求持续增加的背景下,铅污染仍然是当前主要的环境问题之一。持续的铅暴露导致了复杂的体内毒理效应,其临床治疗效果受限于铅检测技术的缺乏与铅动力学研究的不足。单细胞水平上铅的检测技术,可以揭示动力学相关的细胞机制,从微观角度考量细胞异质性对人体内铅运输和铅分布的影响。分析了铅污染现状并归纳了铅暴露源特征,总结了单细胞水平上铅代谢与检测方面的研究进展。细胞机制与细胞异质性对完善铅的动力学模型和理解有关机制的作用不容忽视。单细胞检测技术作为有效的研究工具,包括流式细胞技术、质谱流式细胞技术以及基于电感耦合等离子体质谱的单细胞电感耦合等离子体质谱技术、电感耦合等离子体飞行时间质谱技术和激光烧蚀-电感耦合等离子体质谱技术等,需要更加标准化与体系化的检测方案。基于生物数学模型与单细胞检测技术的发展,单细胞视角下铅的动力学研究有望进一步细化与完善。

铅暴露的环境健康风险评估模型的本土化研究

我国现阶段重金属污染引发的群体事件频繁发生,其中铅污染事件尤为突出和严重。铅污染暴露对儿童健康损害的严重性、不可逆性以及铅污染后果的积累性和潜伏性特点,使得铅暴露的环境健康风险评估对中国的铅污染防治具有重要意义。目前,国际上最常用的铅污染暴露的儿童健康风险评估模型是美国EPA开发的IEUBK模型。为使IEUBK模型在中国得到更好的应用,本文首先对美国IEUBK模型系统做出如下本土化:1鉴于中国儿童的饮食结构、生活习惯及暴露参数等方面与欧美儿童存在的差异,对IEUBK模型暴露模块中的膳食模块和土壤-灰尘模块的数学模型进行改进;2探讨IEUBK模型中生理毒物代谢多隔室模型的高速精确的迭代算法。即针对生理毒物代谢多隔室模型的线性特征,通过离散化方法转化为线性方程组,引进中间变量,设计出了不需要进行高阶矩阵计算、存贮量较小、计算速度快且大样本模拟计算时优点明显的模型求解的一次迭代算法;3根据改进后的模型算法,编制模型的底层代码程序,并优化设计出友好的IEUBK模型系统中文输入界面。接着,对本土化IEUBK模型系统进行测试,测试结果表明:模型迭代算法的计算快速、结果准确,输入界面友好。然后,对本土化IEUBK模型进行实证分析,实证结果显示:本土化IEUBK模型的血铅预测值与血铅实测值的统计学差异并不显著。因此,本土化的IEUBK模型可在中国推广应用。最后,本文探讨了本土化的IEUBK模型系统的进一步改进方向及其在中国环评、环境标准制定及环境诉讼等方面的应用。

铅暴露对人体健康风险评价的模型综述

铅是一种在暴露环境下,可以通过手口途径或者皮肤接触而进入人体,从而对人体许多组织器官都产生毒性作用的重金属,其对儿童的危害尤为突出.我国对暴露在铅环境下人体健康的风险评价研究起步较晚,基于血铅指标的铅污染土壤风险评估方法导则仍在探讨建立中.而国外已经存在一些较为成熟的用于成人及儿童的铅暴露吸收和生物动力学模型,其中被广泛接受和使用的是成人血铅模型(ALM)以及儿童在铅中的综合暴露吸收生物动力学模型(IEUBK).前者描述了关于非居住区土壤中铅暴露物对成人风险的评估,且重点针对污染土壤的铅暴露物所导致的孕妇体内胎儿的血铅浓度进行评估;后者则重点预测6—84个月的儿童在铅的综合暴露下的健康风险.本文旨在通过对这些模型进行对比总结,从而提出可用于我国铅污染风险评估的理论依据及指导方法.

Direct leaching of molybdenum and lead from lean wulfenite raw ore

A direct alkaline leaching process was proposed to extract molybdenum and lead from low-grade wulfenite ore containing 2.87%Mo and 9.39%Pb.The results show that increasing temperature and alkali concentration enhances the extraction of Mo and Pb,and more than 99.7%of Mo and 64.6%of Pb are extracted under conditions of 75℃,L/S of 2:1,leaching time of 1.0 h,initial NaOH concentration of 80 g/L and stirring speed of 100 r/min.The alkaline leaching of molybdenum follows a chemical reaction control mechanism with activation energy of 46.3 kJ/mol.Lead in the residue is recovered by hydrochloric acid leaching.99.8%of lead is leached under the conditions of 80℃,[MnO2]/[Pb]molar ratio of 1.3:1,sodium chloride concentration of 40 g/L,and hydrochloric acid concentration of 3 mol/L,and a product of crystallized PbCl2 with purity higher than 99.5%is obtained after cooling.

Recovery of lead and silver from zinc acid-leaching residue via a sulfation roasting and oxygen-rich chlorination leaching method

A large amount of acid-leaching residue is produced during the conventional Zn hydrometallurgy process,and this residue has a large concentration of a variety of valuable metals.The purpose of this study was to evaluate the ability of a procedure that entails the use of sulfation roasting,water leaching,and chlorination leaching(blowing oxygen technique)to recover Pb and Ag,followed by cooling crystallization and the replacement of Ag with lead sheet,to realize the full recovery of all valuable metals from zinc acid-leaching residue;consequently,good results were achieved.The best results were obtained under the following conditions:a sulfuric acid at 70%of the raw material quality,roasting temperature of 300°C and roasting time of 2 h,followed by the process of leaching the roasted residue for 1 h by applying a water-to-solid ratio of 5꞉1 at room temperature.The recovery rates of Zn and Fe were 98.69%and 92.36%,respectively.The main parameters of the chlorine salt leaching system were as follows:Cl−concentration of 300 g/L,Fe3+concentration of 25 g/L,acid concentration of 2 mol/L,liquid-to-solid ratio of 9 mL:1 g,temperature of 90℃,and leaching time of 0.5 h;this leaching process was followed by filtration separation.These conditions resulted in high extents of leaching for Pb and Ag(i.e.,98.87%and 96.74%,respectively).Finally,the kinetics of the process of Ag leaching using Cl−ions in an oxygen-rich medium was investigated.It was found that the leaching process was controlled by the diffusion of the product layers,and the activation energy was 19.82 kJ/mol.

Synthesis of modified D401 chelating resin and its adsorption properties for Pb^(2+)

A novel chelating resin with sulfonic group was synthesized by chemical modification of D401 resin with sulphonation reaction and characterized by FT-IR spectrometry. The adsorption properties of the novel chelating resin for Pb2+ were studied by batch adsorption, and the adsorption process was analyzed from thermodynamics and kinetics aspects. The adsorption mechanism of Pb2+ on the modified D401 chelating resin was discussed by FT-IR spectrometry. Experimental results show that in the Pb2+ concentration range of 200-400 mg/L, the adsorption capacities of the modified D401 chelating resin for Pb2+ increase by 77%-129%, and Langmuir isothermal adsorption model is more suitable for the equilibrium adsorption data. Adsorption is an endothermic process that runs spontaneously. Kinetic analysis shows that the adsorption rate is mainly governed by liquid film diffusion. The best pH value under adsorption condition is 4-5. The saturated resin can be regenerated by 3 mol/L nitric acid, and the adsorption capacity remains stable after five consecutive adsorption-desorption cycles. The maximal static saturated adsorption capacity of the resin is 206 mg/g at 333 K in the Pb2+ concentration range of 200-400 mg/L. The modified D401 chelating resin is an efficient adsorbent for the removal of Pb2+ from its single-metal ion solution.

Adsorption of lead and cadmium ions from aqueous solutions using manganoxide minerals

Removal of lead and cadmium ions from aqueous solutions by adsorption process was investigated. Low cost and locally available natural mineral of manganoxide mineral was used as an adsorbent. The kinetics of adsorption process data was examined using the pseudo-first-order, pseudo-second-order kinetics and the intra-particle diffusion models. The rate constants of adsorption for all these kinetics models were calculated and compared. The adsorption kinetics was best described by the pseudo second-order model. The Langmuir and Freundlich adsorption isotherm models were applied to the experimental equilibrium data at different temperatures. The experimental data well fitted to Langmuir isotherm model. The maximum adsorption capacities of manganoxide mineral for lead and cadmium ions were calculated from the Langmuir isotherm and were 98 and 6.8 mg/g, respectively. Thermodynamic parameters such as the change of Gibbs free energy, enthalpy and entropy of adsorption were also calculated and it was found that the lead and cadmium uptake reactions by manganoxide mineral were endothermic and spontaneous in nature. Therefore, manganoxide mineral can be used as adsorbents for lead and cadmium ions removal processes as an alternative natural mineral among the others.

Adsorption Kineties of Pb￣(2+) and Cu￣(2+) on Variable Charge Soils andMinerals V .Effects of Temperature and Ionic Strength￣*1

The study results of the effects of temperature and ionic strength on the adsorption kineties of Pb￣2+ and Cu￣2+ bylatosol, red soil and kaolinte coated with Mn oxide showed that Pb￣2+ and Cu￣2+ adsorption by all samples, as awhole, increased with missing temperature. Temperature also increased both values of X_m (the amount of ionadsorbed at equilibrium) and k (kinetica constant) of Pb￣2+ and Cu￣2+. The activation energies of Pb￣2+ adsorption werekaolin-Mn >red soil>goethite and those of Cu￣2+ were latosol> red soil > kaolin-Mn >goethite. For a given singlesample the activation energy of Cu￣2+ was greater than that of Pb￣2+. Raising ionic strength decreased the adsorptionof Pb￣2+ and Cu￣2+ by latosol, red soil and kaolinite coated with Mn oxide but increased Pb￣2+ and Cu￣2+ adsorption bygoethite. The contrary results could be explained by the different changes in ion forms of Pb￣2+ or Cu￣2+ and in surfacecbarge characteristics of latosol, red soil, kaolin-Mn and goethite. Increasing supporting electrolyte concentration in-creased X_m and k in goethite systems but decreased X_m and k in kaolin-Mn systems. All the time-dependent data fit-ted the surface second-order equation very well.

Optimization of operating parameters and kinetics for chloride leaching of lead from melting furnace slag

The feasibility and kinetics of lead recovery from the slag of traditional lead melting furnace using chloride leaching were investigated.The effects of operating parameters such as leaching time,NaCl concentration,FeCl3concentration,liquid/solid ratio,stirring rate,temperature,and particle size on recovery of lead were studied and the optimization was done through the response surface methodology(RSM)based on central composite design(CCD)model.The optimum conditions were achieved as follows:leaching time60min,80°C,stirring rate800r/min,NaCl concentration200g/L,FeCl3concentration80g/L,liquid/solid ratio16,and particle size less than106μm.More than96%of lead was effectively recovered in optimum condition.Based on analysis of variance,the reaction temperature,liquid/solid ratio,and NaCl concentration were determined as the most effective parameters on leaching process,respectively.Kinetics study revealed that chloride leaching of galena is a first-order reaction and the diffusion through solid reaction product and chemical reaction control the mechanism.The activation energy of chloride leaching of galena was determined using Arrhenius model as27.9kJ/mol.

Effect of Heavy Metals on Phosphorus Retention by Typic Udic Ferrisols: Equilibrium and Kinetics

A study was conducted to examine the effect of heavy metals (Cu,Pb, Zn and Cd in combination or alone) on the equilibrium andkinetics of phosphorus (P) retention in typic udic ferrisols by usingboth equilibrium and flow techniques. Fourteen soil samples withvarying artificial contamination of Cu, Pb, Zn and Cd were prepared.Heavy metal pollution led to increases in retention capacity andmaximum buffering capacity (MBC) of soil P. The rate of P retentionwas also increased and the time to reach equilibrium was advanced byheavy metals addition.

Adsorption Kinetics of Pb^(2+) and Cu^(2+) on Variable Charge Soils and Minerals:Ⅰ.Technique

A new technique for studying the adsorption kinetics of heavy metals,Pb^2+ and Cu^2+,on variable charge surfaces was established with two selective electrodes and microcomputer control system.Feasibility of the technique,including interference of other ions (mainly Fe^3+ and Al^3+),response time of electrodes,and the pH range of testing,was studied.Comparision with the most widely used miscible displacement technique,which was considered insufficient in studying 30-minute rapid reactions,at present time showed that the new technique was more advantageous in testing in situ,easy to operate,and economic.

An Improved Nonlinear Dynamic Inversion Method for Altitude and Attitude Control of Nano Quad-Rotors under Persistent Uncertainties

Nonlinear dynamic inversion(NDI)has been applied to the control law design of quad-rotors mainly thanks to its good robustness and simplicity of parameter tuning.However,the weakness of relying on accurate model greatly restrains its application on quad-rotors,especially nano quad-rotors(NQRs).NQRs are easy to be influenced by uncertainties such as model uncertainties(mainly from complicated aerodynamic interferences,strong coupling in roll-pitch-yaw channels and inaccurate aerodynamic prediction of rotors)and external uncertainties(mainly from winds or gusts),particularly persistent ones.Therefore,developing accurate model for altitude and attitude control of NQRs is difficult.To solve this problem,in this paper,an improved nonlinear dynamic inversion(INDI)method is developed,which can reject the above-mentioned uncertainties by estimating them and then counteracting in real time using linear extended state observer(LESO).Comparison with the traditional NDI(TNDI)method was carried out numerically,and the results show that,in coping with persistent uncertainties,the INDI-based method presents significant superiority.

Adsorption Kinetics of Pb^(2+) and Cu^(2+) on Variable Charge Soils and Minerals: Ⅲ. Adsorption Kinetics of Pb^(2+) Within 30 Minutes

The adsorption kinetics of Pb^2+ on different soils and minerals with variable charges was studied by the two ion-selective electrode technique at different pH and concentrations.The results showed that more than 95% of adsorption on all the samples occurred during the first 5 minutes.All adsorption time-dependent data could fit the surface second-order equation very well.The values of Xm were goethite>kaolinite,and latosol>red soil at the same initial reaction concentration.The values of k were kaolinite>>goethite,and latosol>red soil at the same reaction pH and initial concentration.The higher the suspension pH,the faster the adsorption occurred.The meaning of Xm got by the two ion-selective electrode technique(one kind of batch technique) was different from that by the miscible displacement technique in that the former was only the equilibrium adsorption amount at a definite concentration and pH,but the latter was almost equal to the adsorption capacity at a definite pH with much less influence of concentration.One Pb^2+ was supposed to occupy two adsorption sites as the adsorption mechanism is concerned.

Adsorption Kinetics of Pb^(2+) and Cu^(2+) on Variable Charge Soils and Minerals: Ⅱ. Equations for Describing Experimental Data

Different mathematical methods, including linearization, differential, integration and nonlinear least squares approximation (Newton-Marquardt method), were used to fit different kinetic equations, such as zero-order, first-order (i. e, membrane diffusion), second-order, parabolic-diffusion, Elovich, two-constant equations, to the experimental data of Pb2+ and Cu2+ adsorption on variable charge soils and kaolinite. Assuming each M2+ occupied two adsorption sites, two more equations, the so-called surface second-order equation and third-order equation were derived and compared with the above equations according to the fitting results, which showed that the second-order equation and surface second-order equation, being one equation in different expressions under some conditions, were better than the other equations in describing the Pb2+ and Cu2+ adsorption kinetics, and the latter was the best.

Interaction Kinetics between Sn-Pb Solder Droplet and Au/Ni/Cu Pad

The interracial phenomena of the Sn-Pb solder droplet on and needle-like AuSn4 are formed at the interface after Au/Ni/Cu pad are investigated. A continuous AuSn2 the liquid state reaction （soldering）. The interracial reaction between the solder and Au layer continues during solid state aging with AuSn4 breaking off from the interface and felling into the solder. The kinetics of Au layer dissolution and diffusion into the solder during soldering and aging is analyzed to elucidate intermetallic formation mechanism at the solder/Au pad interface. The concentration of Au near the solder/pad interface is identified to increase and reach the solubility limit during the period of liquid state reaction. During solid state reaction, the thickening of Au-Sn compound is mainly controlled by element diffusion.

Modeling and Measurements of Heat Transfer Phenomena in Two-Phase PbSn Alloy Solidification in an External Magnetic Field

The main aim of this work is to study numerically the influence of an external magnetic field on the solidification processes of two-component materials. Based on the continuum model of two-phase flow a mathematical model for the directional solidification of a binary alloy in a magnetic field is presented. The model includes mass, momentum, energy and species mass conservation equations written in compressible form and additional relationships describing the temperature-solute coupling. The geometry under study is a cylindrical mold with adiabatic walls and cooled bottom. The macroscale transport in the solidification of alloys is governed by the progress of the two-phase mushy zone, which is treated by means of a porous medium approach. The volume fraction of liquid and solid phases, respectively, is calculated from a 2D approximation of the phase diagram. The results of calculation are compared with experimental data.