同位镀锑方波溶出伏安法测定痕量铅、镉

采用同位镀锑膜法修饰玻碳电极(GCE),用方波溶出伏安法(SWSV)对痕量铅、镉同时进行了测定.在最优的实验条件下,Pb、Cd分别在-0.5,-0.78 V(vs Ag/AgCl)附近产生灵敏的溶出峰,当Pd、Cd的质量浓度分别在5~110μg·L-1范围内时,峰电流与质量浓度呈良好的线性关系,检出限分别为1.2μg·L-1和0.8μg·L-1.利用该法测定大米中的镉,相对标准偏差在2.6%~3.5%,并与电感耦合等离子体发射光谱法(ICP-AES)做了对比,测定结果良好.     

铕离子掺杂类普鲁士蓝复合铋膜电极阳极溶出法测定痕量锌

采用预镀铋电化学沉积法制备了铕离子掺杂类普鲁士蓝复合铋膜电极,建立了阳极溶出伏安法测定痕量锌的新方法.结果表明,锌在0.03 mol.L-1的酒石酸钠(pH=4.5)溶液中可得到灵敏的阳极溶出峰;最佳实验条件下,于-1.4 V富集120 s后,锌的溶出峰电流与其浓度在10~540μg.L-1(r=0.99987)范围内呈良好的线性关系,检出限为1.38μg.L-1(S/N=3),相对标准偏差为0.94%(n=8).该法可用于奶制品和药品中锌含量的测定,回收率为99.3%~101.2%.     

城市固体废物焚烧炉飞灰中重金属酸溶出研究

对城市固体废物(MSW)焚烧炉飞灰中Cu,Pb和Zn 3种重金属的酸溶出过程进行了研究,结果显示在选用的3种不同浓度的酸中,只有浓度为0.5 mol/L的酸对3种重金属的溶出较理想.研究表明采用0.5 mol/L的酸对飞灰溶解搅拌约3 h后便可溶出大约50%~80%的Zn、40%~55%的Pb和50%左右的Cu,同时一些易溶金属如Mg,Ca和Al也大量溶出,但Fe和Si在飞灰中相对稳定,溶出量相对较少.飞灰经过酸处理后基本上可以满足填埋要求.     

同位镀铋/过氧化聚乙酰苯胺/玻碳电极溶出伏安法测定食用盐中痕量镉和铅(英文)

提出了一种新颖的同位镀铋膜过氧化聚乙酰苯胺修饰的玻碳电极(Bi/over-oxidized PNAANI/GCE)方波溶出伏安法(SWASV)同时检测食用盐中Cd(Ⅱ)和Pb(Ⅱ)的方法.过氧化聚乙酰苯胺膜具有良好的阳离子选择通透性,大大改善了修饰电极检测重金属时的灵敏度和选择性.同位镀铋膜可以作为汞膜的替代物,用于提高修饰电极对Cd(Ⅱ)和Pb(Ⅱ)的富集能力.Cd(Ⅱ)和Pb(Ⅱ)的分析曲线均覆盖了两个线性范围:0.2～3.0μg·L-1和3.0～33μg·L-1,在富集时间为300s时,Cd(Ⅱ)和Pb(Ⅱ)检测限分别为0.015μg·L-1和0.029μg·L-1.此外,这种修饰电极还具有很高的稳定性和抗干扰性能.最后,该修饰电极被成功地应用于食用盐样品中Cd(Ⅱ)和Pb(Ⅱ)的同时测定.     

铅在氧化石墨烯-纳米氧化镍修饰玻碳电极上的电化学行为

用氧化石墨烯-氧化镍纳米复合膜修饰玻碳电极,制备了电化学传感器.用循环伏安法研究了铅在该电极上的电化学行为,建立了差分脉冲溶出伏安法测定痕量铅的电化学分析法,详细优化了氧化石墨烯的用量、富集电位、富集时间、电聚圈数、底液的pH值等测定条件.研究结果表明:在优化条件下,Pb2+的浓度在1×10-7～1×10-6mol/L的范围内与溶出峰电流呈良好的线性关系,检出限为1×10-8mol/L.将该方法用于水样中Pb2+的测定,回收率为96.5%～104.2%.     

极谱法连续测定痕量铅和镉

研究了Pb2+和Cd2+与KCI-酒石酸钠-三乙醇胺-明胶体系的二次导数极谱波.在pH=4.5的HAc-NaAc介质中,Pb2+和Cd2+分别于-0.46V和-0.64V电位处产生一良好的极谱波.峰电流与Pb2+和Cd2+的浓度分别在1×10-5～3×10-1 g·L-1和5×10-5～6×10-3 g·L-1范围内呈线性关系.Pb2+和Cd2+的检出限分别为1×10-7 g·L-1和5×10-7 g·L-1.本法准确、简便、快速、选择性高.已直接用于饮料中铅和镉的连续测定,同时也对酒及面粉样品进行了测定,回收率分别为99.9%～100.1%和97.0%～104.8%.     

水溶性碳纳米管增敏方波溶出伏安法测定痕量铅

对以羧基化水溶性碳纳米管(CNT)作增敏剂,用方波溶出伏安法测定水样中痕量铅进行了研究.结果表明:在1 mol/L的盐酸底液中,Pb2 在-0.46 V左右出现灵敏溶出锋,峰电流在Pb2 浓度为2.0×10-9～1.0×10-8 mol/L 时呈现良好的线性关系,回归方程A(μA)=9.6656 0.6407 c(10-9 mol/L),相关系数为0.9985.检出限为1.0×10-10 mol/L,回收率为96%～104%.该方法适用于痕量铅的测定,灵敏度高,效果良好.     

超声波辅助L-丙氨酸对钾长石促释性能研究

以钾长石为原料,用正交实验对L-丙氨酸在超声波辅助下对钾长石促释性能的影响进行研究,实验表明,磷酸浓度对钾长石中钾的溶出率影响最大,L-丙氨酸浓度、超声波时间、反应温度对钾溶出率的影响依次降低.实验条件下优水平的工艺条件为磷酸浓度为60%,有机酸L-丙氨酸浓度为1.0 mol·L~(-1),超声波时间为3h,总反应时间24 h,反应温度为40℃.在此条件下钾的溶出率可达34.99%.     

有机-无机杂化复合铋膜电极溶出伏安法测痕量镉、铅离子

将铋和聚苯胺共沉积在玻碳电极上制备了杂化膜,然后在杂化膜上沉积一层铋膜,制备了一种新颖的电化学传感器——有机-无机杂化复合铋膜电极(HCBiFE),用于痕量重金属离子Cd(Ⅱ)和Pb(Ⅱ)的检测(0.1mol/L醋酸缓冲溶液,pH 4.7).优化了镀膜条件、离子测试参数.在1～90 μg·L-1的浓度范围内,两离子溶出峰电流与浓度呈现出良好的线性关系,富集时间120 s时,Cd(Ⅱ)和Pb(Ⅱ)的检测限分别低至0.2,0.5μg·L-1.该复合膜具有很好的稳定性和重现性,能够抗机械剥蚀、不易脱落,对50 μg·L-1的Cd(Ⅱ)和Pb(Ⅱ)连续测定50次,相对标准偏差分别为4.3％,6.1％.30 d后,该复合膜电极对Cd(Ⅱ)和Pb(Ⅱ)溶出峰电流分别下降3.2％,4.9％,表明该复合膜电极性能稳定,有望应用于环境水体的现场监测.     

演马矿煤矸石矿井填充对地下水环境的影响

对演马矿煤矸石进行浸泡和淋溶实验,研究了煤矸石矿井填充对地下水环境的影响.实验测定淋溶液中矿化度最高为6.80 g.L-1,高锰酸盐指数为7.50 mg.L-1,锰指数为2.30 mg.L-1;浸泡试验溶出液中pH值、高锰酸盐指数、氟离子(F-)超过地下水3类标准.结果表明,对地下水产生影响的主要污染因子为矿化度、氟离子、高锰酸盐.锌、锰、铜等重金属溶出率随时间增长较快,但不超标.这表明可以用煤矸石进行矿井填充,以解决煤矸石的污染.     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the