表面镉（Ⅱ）离子印迹聚合物的制备及其应用

利用离子印迹技术制备了镉（II）离子印迹聚合物,并对其吸附性能进行了详细研究。以镉（II）离子为模板,以3-氨基丙基-三乙氧基硅烷为功能单体,在纳米TiO2/SiO2表面聚合形成镉（II）印迹聚合物。实验结果表明,与非印迹的聚合物相比较,该印迹聚合物对镉（II）离子具有较好的识别性和选择性。镉（II）印迹聚合物与非印迹聚合物的吸附量分别是42.56mg·g^-1和13.95mg·g^-1。该法的检出限为0.11ng·mL-1,相对标准偏差为1.79%。将该印迹聚合物用于环境和生物样品中的镉（II）的分离富集和测定,结果令人满意。     

土壤腐殖质对重金属离子吸附-解吸作用的研究探讨

从土壤腐殖质对重金属离子的吸附作用、解吸作用和吸附机制三方面,综述了近期的研究状况和最新进展,并对今后的研究方向进行分析,以促进吸附-解吸作用研究的继续深入开展。     

飞行时间二次离子质谱在生物材料和生命科学中的应用(下)

随着仪器性能的不断提高,飞行时间二次离子质谱(TOF-SIMS)在材料表面化学分析中起着越来越重要的作用。TOF-SIMS的主要测试功能包括表面质谱、化学成像及深度剖析,本工作对TOF-SIMS的化学成像及深度剖析2种功能在生物材料和生命科学中的应用做了简单综述,重点介绍了TOF-SIMS成像技术在生物芯片制备工艺中的应用和TOF-SIMS成像和深度剖析技术对生物分子在细胞和生物体组织上空间分布的表征方法;另外,对生物样品的低温制备方法,样品表面添加基质以增强信号强度的实验手段,使用团簇一次离子源提高分子二次离子产额和利用对样品损伤小的C60离子源为轰击源做深度剖析等实验做了简单的介绍;最后,对TOF-SIMS在生物生命材料领域的应用做了展望。     

黄河水中固体粒子与Cu、Pb、Zn、Cd相互作用的离子交换率E(%)-pH曲线的研究

采用离子交换法和原子吸收分光光度法研究了黄河游水体中固体粒子(表层沉积物〕与铅、铜、锌、镉液-固界面的相互作用,及各种环境因素对颗粒表面吸附作用的影响,绘制了离子交换率E(％)-pH曲线。实验结果为:1)铜、铅、锌、镉均以一价络离子形式在固体粒子表面进行阳离子交换反应;2)pH值是控制金属离子向固相迁移的主要因素,且E(％)随pH升高而增大。在天然黄河水pH范围(8.0-8.5)内,四种金属离子的E(％)可达80-100％;3)E(％)-pH曲线会随金属离子浓度的增高而向高pH方向移动,表明E(％)下降;4)随固体粒子浓度增大,E(％)就会增高,使E(％)-pH曲线向小pN方向移动;5)固体粒子的粒度增大也会使离子交换率下降;6)加入一定浓度的甘氨酸会使镉离子交换率E(％〕增大。     

防生物污损生物肽改性金属材料的研究现状

在讨论生物对材料污损机理的基础上,分析了通过表面改性降低材料表面能的方法及表面能对生物吸附、脱附的影响。综述了利用生物肽改性金属材料的研究现状,重点介绍了利用生物肽对不锈钢进行改性,及改性对其电子逸出功、硬度、表面能等的影响,为利用改性金属材料低表面能的特性实现防生物污损的研究提供参考。     

复合电沉积初始阶段预吸附的惰性颗粒对金属离子沉积的影响研究

研究了复合电沉积初始阶段预吸附的TiO2颗粒对金属镍离子电沉积的影响,首次观察到在复合电沉积初始阶段预吸附的TiO2颗粒导致镍离子异常成核和快速生长的现象.提出了逐步电沉积方法,结合循环伏安曲线和电化学阻抗谱等电化学方法,研究了预吸附TiO2颗粒对镍离子沉积的影响作用.结果表明预吸附的TiO2颗粒能够增加阴极表面的活性位点密度,并减小阴极表面的电荷转移阻抗,从而加快吸附原子的电结晶步骤.结合上述研究建立了预吸附惰性颗粒影响金属离子沉积的物理模型.本研究提供了一种金属离子快速沉积和纵向生长的可能,对于揭示复合电沉积过程中惰性颗粒与金属离子的共沉积机理和行为具有重要意义.     

盐溶液条件对边界润滑添加剂在带电表面吸附行为的影响

为揭示盐溶液条件对边界润滑添加剂聚醚接枝聚羧酸盐(Poly(carboxylate ether),PCE)吸附行为的影响,利用表面力仪在一种商业PCE的多种水溶液中直接测量带电云母表面之间的法向作用力.力一距离测量表明PCE从0.1 mol/L K2SO4溶液中微弱地吸附于云母表面,其边界吸附薄膜(厚度约50 (A))在相当于三四个大气压的载荷条件下即从两表面间完全挤出.解吸附之后,PCE能立即实现相同的再吸附.在相同离子强度的0.1 mol/L Ca(NO3)2溶液中,PCE却不吸附于云母表面.但是,在低浓度的5 mmol/L Ca(NO3)2溶液中,PCE在云母表面建立厚度约40 (A)的牢固边界吸附层.二价Ca2+离子能桥接两PCE边界吸附层,而单价的K+离子不能.二价阳离子桥接吸附机理只能在有限的离子浓度范围内发生.     

生物柴油-柴油混合燃料润滑性能研究

对比研究菜籽油为原料制取的生物柴油与石化柴油混合后组成的混合燃料与纯石化柴油的润滑性能。在摩擦磨损测试机上,考察2种燃料作为润滑剂时摩擦副的磨损失重;采用体式显微镜观察摩擦副表面纹理;采用铁谱显微镜分析润滑油油样。结果表明:生物柴油的加入使混合燃料中含有较多的氧和极性团,表现出较好的油性和湿润性,有利于裸露金属表面氧化膜和物理吸附膜的生成,使得混合燃料具有优于石化柴油的润滑性能。     

蛋膜固相萃取-石墨炉原子吸收光谱法测定酵母粉中的痕量镉

本文研究了蛋膜固相萃取-石墨炉原子吸收光谱法测定酵母粉中痕量镉的方法,实验中对蛋膜吸附镉的性能、洗脱剂的选择、洗脱液用量和干扰离子的影响等进行了探讨。结果表明在0.1～2.0mol/L氨水介质中,蛋膜能完全吸附镉。吸附的金属离子可以用0.48mol/L盐酸2mL完全洗脱下来。方法的检出限为0.0037ng/mL,回收率为97.8%～102%。该方法操作简单,准确性好,灵敏度高,适用于酵母粉和食品中痕量镉的分析,能获得满意的结果。     

一种新型改良剂对稻田土壤镉污染的修复效应研究

目前,我国农田土壤镉污染问题严重,选用合适的改良剂修复镉污染土壤是一种常用的修复方法。本研究以生物碳与赤泥结合作为土壤改良剂,选取黄泥田土壤,通过水稻盆栽试验研究改良剂添加对土壤中水稻糙米镉累积及水稻生长的影响,确定改良剂对土壤镉的稳定化效果,明确镉污染土壤修复的适宜赤泥施用量。实验研究表明:添加改良剂可以有效减少水稻糙米中Cd的含量,水稻糙米Cd含量随赤泥施用量的增加而减少。黄泥田土壤中,当改良剂使用量为五节芒生物炭添加量5g·kg-1、赤泥施用量5g·kg-1土时,水稻糙米Cd含量为0.17mg·kg-1,与空白对照处理(0.54mg·kg-1)相比减少了68.5%,达到了国家粮食卫生标准(GB2715-2005)。施用一定量的改良剂可以促进水稻生长。当改良剂施用量超过一定范围后,水稻生长又会受到抑制。考虑水稻生长效果及土壤修复效果,建议在黄泥田污染土壤上的适宜改良剂施用量为五节芒生物炭添加量5g·kg-1、赤泥施用量5g·kg-1。     

赤泥对水稻植株各部位镉含量及水稻生物量的影响

随着稻田镉污染日益严重,镉在稻田中的不断富集,直接影响水稻生长和稻米品质。本实验主要通过测定水稻各部位镉的含量以及成熟期水稻株高、穗长、千粒重等指标,分析施用赤泥对水稻植株各部位镉富集以及水稻生物量的影响。结果表明,镉在水稻植株各部位的分布为根〉茎〉〉叶〉籽实。施用赤泥可减少镉在水稻各部位的累积,并能起到促进水稻生长的作用。在本实验中按7500kg赤泥／hm2土施用赤泥可以较好地减少水稻植株对镉的吸收。     

Application of ion-beam etching techniques to the fine structure of biological specimens as examined with a field emission SEM at low voltage

The term “etching,” in electron microscopy, refers to the removal of specimen surface layers and includes chemical, electrolytic, and ion-beam methods. The ion-beam etching process is used to remove layers of a target material by bombarding it with ionized gas molecules. Recently, the method has been applied to the field of biological specimens; however, the practical procedures for such organic materials have not been developed. In the present study, we used an apparatus in which a beam of argon ions is collimated and focused by electrostatic lenses onto an appropriate target. We demonstrated the optimum conditions to observe biological specimens that were treated with osmium tetroxide and tannic acid. The specimens were examined uncoated at low accelerating voltage using a field emission scanning electron microscope. According to our experiments, when a biological specimen was observed under high-resolution conditions at over 50,000x magnification, the optimum condition of ion-beam etching consisted of an accelerating voltage of E = 1 keV and an ion-beam dose of It = 360 ～ 400 μA. min, depending on parts of the specimens. In order to decrease overetching, we had to choose factors such as E = 1 ～ 2 keV and It = 500 μA. min.     

The delamination theory of wear and the wear of a composite surface

The delamination theory of wear postulates that there is a “nonworkhardening” soft surface layer which deforms continuously due to the instability of dislocations, and that the low speed sliding wear of metals is caused by the subsurface crack nucleation and propagation nearly parallel to the surface. A corollary of the theory is that when hard metal surfaces are plated with a soft metal to reduce the coefficient of friction and the wear rate, the soft metal layer must be thinner than a critical thickness so as to prevent the accumulation of dislocations in the plated layer and the formation of the delaminated layer. This corollary was investigated by plating annealed AISI 1018 steel with cadmium. The wear rate of the steel specimen plated with 0.1 μm cadmium on both of the contacting surfaces was three orders of magnitude smaller than the unplated specimen when they were tested in argon. In the case of thicker coatings, the cadmium layer wears by the delamination process which occurs within the plated layer. The very thin cadmium plate is also effective in reducing wear in inert oil, but not effective in an oxidizing atmosphere. The coefficient of friction of the 0.1 μm Cd plated steel was less than the unplated steel under all test conditions.     

Cadmium distribution and toxicity in tissues of small rodents.

The aim of the present paper is to discuss the accumulation and distribution of cadmium (Cd) in the various tissues of animals, the interactions of cadmium with other elements, and the damage to tissues caused by this metal. Cadmium is not physiologically or biochemically essential to an organism. It is absorbed via the gastrointestinal tract and lungs and accumulated in various tissues, mainly the kidneys and liver. The distribution of cadmium between various tissues depends on many endogenous and exogenous factors. Cadmium is bound to a low-molecular-weight protein, metallothionein (MT), and to high-molecular-weight proteins. This metal has a great affinity to thiol groups. Cadmium binds also to O- and N-containing ligands. The distribution of cadmium between organs differs markedly depending on the chemical form of administered Cd and the duration of exposure. Acute exposure results in a different distribution pattern throughout the body than does chronic exposure. Long-term exposure to high doses of cadmium may cause biochemical and functional changes in some critical organs. Cadmium can influence the absorption and distribution of essential elements and can replace them in enzymes. Metallothionein and glutathione play important roles in the transport of metals and in detoxification processes. Reported findings are mainly the results of experiments on laboratory animals. The lack of data concerning the localization of cadmium in various tissues of wild species is noticeable and there is a great need for such data.     

Distribution of exogenous heavy metals in the hepatocytes of calves: a morphometric study

The objective of this study was to evaluate the presence of heavy metals in the hepatocytes of the animals fed a cadmium-supplemented diet and also receiving zinc and/or selenium in the injection form. The experiment involved four groups of calves (6-8, both sexes) receiving the heavy metals in various combinations for 95 days. Electron micrographs of liver cells were prepared and statistically evaluated using Student's t-test. A modified morphometric apparatus was used for morphometric examination. Exogenous cadmium showed marked accumulation in the hepatocytes. If, however, the cadmium diet was combined with zinc or selenium administration the amount of the reduction product was much lower.     

交替曝气两级生物滤池除磷工艺挂膜启动研究

为克服传统BAF工艺生物除磷效果差的缺点,开发了厌氧／好氧交替BAF生物除磷工艺。在水温为25～28℃的条件下,采用3阶段“闷曝阶段、小流量逐渐增加负荷连续进水阶段、交替曝气阶段”的方式启动交替曝气两级生物滤池反应器,前2阶段主要是培养好氧异养菌,第3阶段是培养驯化除磷微生物。试验结果表明,经前2阶段后,COD去除率为76．09％;第3阶段结束时,TP去除率为72．31％,COD去除率达到80％以上。本反应器挂膜启动完成时间为14d。     

Preparation of fetal rat brains for light and electron microscopy

To study cellular shapes, growth patterns, and fine structure during early stages of CNS development in rat embryos, preparative procedures were evaluated and modified to meet two criteria: (1) Coronal semithin sections should reveal undeformed telencephalic hemispheres that were symmetrically expanded on both sides of midline structures and were surrounded by contiguous mesenchyme. (2) In electron micrographs, cells should have intact, undistorted surface membranes, evenly distributed nucleoplasm and well preserved cytoplasmic organelles. To meet these criteria, 378 fetuses with a gestational age of 11–20 days (E11–E20) were used to test and modify procedures for anesthesia, embryo removal and handling, dissection, fixation, dehydration, and embedding of the embryonic CNS. Most specimens were in an early stage of development (E11–E13), which, in case of the neopallial wall, is the preneural period. The tests produced methods that met the above criteria and identified the most common artifacts and their causes. Deformities of the cerebral hemispheres and separations between the brain and its coverings were usually caused by trauma during embryo removal and during handling before fixation. Changes in cellular volumes, especially swelling during fixation and dehydration, were the most important causes of histological artifacts. The procedures and methods that consistently produced the best light and electron microscopic preservation of the E11–E13 rat CNS are described. Fixation was best when the brains were treated with glutaraldehyde and s-collidine buffer, followed by osmium tetroxide in s-collidine buffer. A surprisingly beneficial effect of sodium chloride in the dehydrating alcohol was noted.     

304奥氏体不锈钢高温拉伸变形时的锯齿流变行为

对304奥氏体不锈钢进行拉伸试验,研究了其在高温拉伸变形过程中的锯齿流变行为。结果表明:当应变速率在2×10-4～2×10-3s-1范围内,试验钢发生动态应变时效的温度为773～973K;出现了A、A+B和E三种锯齿波和负的应变速率敏感系数;锯齿形成的有效激活能为212.8kJ.mol-1;铬和锰等置换型溶质原子与运动位错的交互作用使试验钢出现动态应变时效,导致锯齿流变行为的产生。     

Different membrane modifications revealed by atomic force/lateral force microscopy after doping of human pancreatic cells with Cd, Zn, or Pb

The interaction of the cytotoxic metals cadmium, zinc, and lead with pancreatic cells was studied by atomic force/lateral Force microscopy (AFM/LFM), an approach that provides both topographic (with nanometer scale lateral resolution) and chemical information on the membrane. Different morphological modifications of the overall cell shape and roughness took place as consequence of 100 muM metal-dependent treatment. Furthermore, after exposure to Cd(Cl(2)) and Zn(Cl(2)), but not Pb(Cl(2)), the LFM images revealed several areas of the cell's surface showing lateral friction contrasts that have been interpreted as marker of different alterations of the cell physiology induced by the metal loading. Thus, the coupling of LFM detection to topographic AFM characterization allows to distinguish, through a nondestructive and surface characterising approach, between different metal-induced cytotoxic effects on cells. In this framework, the role of the LFM as an important tool to discriminate between different alteration of a biological system has to be highlighted.     

The steady state wear behaviour of pearlitic rail steel under dry rolling-sliding contact conditions

The present study is aimed at studying the onset of steady state wear behaviour of pearlitic rail steel. Wheel-rail contact is simulated by a rolling-sliding line contact. The results show that steady state wear rate prevails after a certain number of rolling-sliding cycles. The effect of strain hardening and uni-directional plastic strain accumulation on the wear behaviour has also been studied. It has been shown that the start of the steady state wear rate coincides with the cessation of plastic strain accumulation and additional strain hardening. The ratchetting failure mechanism has been employed to explain this coincidence.