pH值对Ca2+、La3+和Al3+与拟南芥钙调素竞争结合作用的影响

利用Tb3+荧光光谱,通过Tb·CaM系统的特征光谱在加入Ca2+、La3+和Al3+前后荧光强度的改变,研究了pH值对Ca2+、La3+和Al3+与拟南芥钙调素 (CaM)竞争结合作用的影响.结果表明,在中性条件下,金属离子与Tb·CaM系统中Tb3+的竞争能力强弱顺序为:La3+＞Ca2+＞Al3+,与钙调素的结合力为:Tb3+＞ La3+＞Ca2+＞Al3+.在pH值等于4.5的酸性条件下,Ca2+、La3+和Al3+与Tb3+的竞争结合能力较中性条件下弱,同时,稀土在酸性条件下的竞争结合力大于Ca2+和Al3+,Al3+与CaM竞争结合能力在酸性条件下大于Ca2+.竞争实验的结果从分子水平上证实了金属离子可取代Ca·CaM中的Ca2+与钙调素产生竞争性结合,模拟Ca2+ 4·CaM的行为,且pH值对金属离子与钙调素竞争结合力产生一定影响,揭示了胞外钙调素在酸性和金属离子浓度较高的生理条件下生物效应可能的分子机制.     

铽及其掺杂对苯二甲酸冠醚配合物的合成与荧光性能研究

合成了铽及掺荧光惰性镧、钆、钇的铽冠醚对苯二甲酸配合物。通过元素分析、摩尔电导及红外光谱推测出了配合物的组成;实验结果表明,半径大的稀土离子与18冠6的氧原子直接配位,而半径小的稀土离子则通过水分子配位;对苯二甲酸作为桥连配体连接两个稀土冠醚配合物。测定了配合物的荧光激发光谱和发射光谱,表明铽配合物发出较强的荧光。探讨了配合物中的传能过程,结果表明,配体能较好地将吸收的能量传递给T b3+,不发光稀土离子(L a3+、G d3+和Y3+)对发光稀土离子(T b3+)具有很强的敏化作用,比较这三个含有惰性稀土离子的配合物,发现L a3+的敏化作用最强。     

La(Ⅲ)对质粒pUC18复制拷贝数的影响

稀土应用的日益增长将会对生物的遗传产生深远的影响。生物的遗传离不开DNA的复制,由于染色体DNA非常巨大和复杂,难以直接研究稀土离子对其复制的影响。本研究以细菌染色体之外的遗传因子——质粒为对象,研究L a3+对质粒DNA复制拷贝数的影响。结果表明:在不同浓度L a3+存在下,质粒在宿主细胞中复制的拷贝数不同;因培养时间相同,因此质粒在宿主细胞中复制的平均速率不同。由于质粒复制与染色体DNA复制使用相同的酶系,因而可初步推断不同浓度的L a3+对染色体DNA复制的平均速率有同样的影响。     

稀土生物效应机理研究进展

本文探讨了国内外对稀土生物效应所进行的广泛研究及其所取得的一些结果。在稀土农用方面、稀土离子在非细胞溶液体系中和生物大分子互相作用的行为、稀土元素在动植物细胞的定位、稀土元素和脂质体与细胞膜膜脂关系的一些研究结果、稀土离子对质膜 ATPase活性研究的一些结果以及稀土元素对细胞信使物质含量及传导的影响等诸方面进行了总结。以期在细胞和分子水平上探讨稀土元素的生物效应及可能的生理作用 ,为稀土在农业上的进一步广泛应用奠定理论基础。     

荧光法研究稀土与血清白蛋白相互作用的进展

综述了荧光法在研究稀土离子及其配合物与血清白蛋白的相互作用的应用.荧光法有助于小分子与其他蛋白的结合作用的研究;同时对全面阐述血清白蛋白结合各类小分子的机理具有重要意义.     

稀土离子对大肠杆菌tRNA~(Leu)氨酰化反应的影响

金属离子不但对ｔＲＮＡ分子结构起稳定性作用，且为氨酰化反应所必需。稀土离子可以取代ｔＲＮＡ分子中与结构功能有关的固有的镁离子，较低浓度的稀土离子和镁离子一样参与氨酰化反应，金属离子浓度提高时稀土对氨酰化反应的激活作用不如镁，对于脱镁ｔＲＮＡ分子稀土离子的这种作用更为明显。稀土离子对氨酰化反应的影响可归因于其与ＡＴＰ及ｔＲＮＡ的强配位作用引起ＡＴＰ稳定性及ｔＲＮＡ分子构象发生某种改变所致。     

具有生物标记功能基团的稀土配合物的合成与荧光性质研究

设计合成了均苯三甲酸单缩N-羟基琥珀酰亚胺单缩乙二醇酯双功能螯合剂(TEN)及其与稀土离子形成的配合物,通过元素分析、稀土滴定确定了配合物的组成为:RE(TEN)2.[OH].mH2O.nNH3,[RE=Eu3+,Tb3+;TEN=C15H13O9N]。配合物的红外光谱表明,配体TEN中的一个羧基与稀土离子配位。荧光光谱实验表明,两种稀土配合物的荧光强度较高,有明显的特征荧光。配合物中的N-羟基琥珀酰亚胺具有与生物分子连接的能力,因此合成的配合物在生物标记功能材料方面具有潜在的应用前景。     

纳滤膜对稀土离子的动态吸附行为及截留特性

采用经碳纳米管改性的亲水化纳滤膜浓缩提取稀土浸出液中的稀土离子,探究纳滤膜表面对La3+、Nd3+、Pr3+、Ce3+和Y3+5种稀土离子吸附动力学行为,考察稀土离子半径的大小对纳滤膜吸附性能和截留性能的影响.结果表明,Freundlich吸附方程比Langmuir方程能更好地描述稀土离子在纳滤膜表面上的动态吸附行为,用Freundlich吸附方程拟合后的结果相关度系数R2能达到0.999以上;在初始浓度为5×105 μg/L,温度为25 ℃,运行压力为0.6 MPa的实验条件下,纳滤膜对稀土离子的浓缩提取过程中,初始阶段的截留机理取决于纳滤膜表面的吸附作用和膜孔的机械筛分效应,膜面吸附达到平衡后以膜孔的机械筛分效应为主,此时La3+、Nd3+、Pr3+、Ce3+和Y3+的截留率分别为94.21 %、81.25 %、85.80 %、89.90 %和81.18 %,表明经碳纳米管改性的亲水化纳滤膜能高效浓缩截留稀土浸出液中的稀土离子.      

稀土生物无机化学(Ⅱ)

三、稀土离子作为结构探针稀土离子可用于研究Ca~(+2)、Mg~(+2)等金属离子与生物大分子作用的结构探针。因为稀土离子与Ca~(+2)有相似的离子半径,在生物体系中一般能与Ca~(+2)结合在相同的位置上,从而引起稀土离子的光学和磁学参数的变化,通过磁共振或萤光光谱的测量,可深入了解Ca~(+2)的结构情况。关于稀土离子作为结构探针巳发表过评论文章,这里仅举几例加以说明。     

氨基酸对La(Ⅲ)与黄河沉积物相互作用的影响

研究了La3+离子在黄河水中与沉积物的相互作用特性及谷氨酸和酪氨酸对吸附作用的影响。结果表明,黄河水中La3+与沉积物相互作用的吸附等温线是一种台阶型的二级交换等温线,用分级离子交换等温式求出了平衡常数K1和K2。氨基酸对La3+与沉积物相互作用有明显影响,低浓度的氨基酸使La3+与沉积物的交换吸附作用增强;酪氨酸对镧与沉积物的相互作用的促进较谷氨酸大。     

风化壳淋积型稀土矿浸出液沉淀浮选溶液化学分析

通过对风化壳淋积型稀土矿浸出液沉淀浮选进行溶液化学研究,探讨了体系pH、沉淀剂及浮选剂对沉淀浮选的影响.结果表明,风化壳淋积型稀土矿浸出液杂质可通过优先沉淀浮选以氢氧化物或焦磷酸盐或聚磷酸沉淀形式全部有效除去,最后将优先沉淀浮选除杂后浸出液中和提高pH值,再用沉淀浮选方法有效提取稀土.     

Study on Anticoagulation Factor I from Agkistrodon Acutus Venom by Rare Earth Ion Probes

Ｓｎａｋｅｖｅｎｏｍｓｃｏｎｔａｉｎｃｏｍｐｌｅｘｐｒｏｔｅｉｎｓｗｈｉｃｈｐｏｓｓｅｓｓｖａｒｉｏｕｓｂｉｏｌｏｇｉｃａｌａｃｔｉｖｉｔｉｅｓ ,ｉｎ ｃｌｕｄｉｎｇａｃｌａｓｓｔｈａｔａｆｆｅｃｔｓｃｏａｇｕｌａｔｉｏｎｓｙｓｔｅｍｗｉｔｈｃｏａｇｕｌａｎｔｏｒａｎｔｉｃｏａｇｕｌａｎｔａｃｔｉｖｉｔｉｅｓ .Ａｎａｎｔｉｃｏａｇｕｌａｎｔｆａｃｔｏｒ (ＡＣＦ)ｗａｓｐｒｅｖｉｏｕｓｌｙｉｓｏ ｌａｔｅｄｆｒｏｍｔｈｅｖｅｎｏｍｏｆＡｇｋｉｓｔｒｏｄｏｎａｃｕｔｕｓｆｒｏｍｓｏｕｔｈｅｒｎＡｎｈｕ…     

Significant enhancement of blue photoluminescence intensity of Dy~(3+) modified Sr_6Ca_4(PO_4)_6F_2:Eu~(2+) phosphors

Blue-emitting phosphors Sr_6 Ca_4(PO_4)_6 F_2:Eu~(2+)(SCPF:Eu~(2+)),Sr_6 Ca_4(PO_4)_6 F_2:Eu~(2+),Dy~(3+)(SCPF:Eu~(2+),Dy~(3+))and Sr_6 Ca_4(PO_4)_6 F_2:Eu~(2+),Dy~(3+),Si~(4+)(SCPF:Eu~(2+),Dy~(3+),Si~(4+)) with apatite structure were successfully synthesized by traditional solid-state reaction under reducing atmosphere.Eu~(2+),Dy~(3+) and Si4+ions occupy the corresponding sites of Sr~(2+),Ca~(2+) and P~(5+).Strong broad blue photo luminescence band is exhibited in SCPF:Eu~(2+),Dy~(3+) phosphor ranging from 400 to 550 nm centered at 455 nm and Dy~(3+) ions are vital in creating traps.Emission intensity of Eu~(2+),Dy~(3+) co-doped SCPF:0.02 Eu~(2+),0.02 Dy~(3+) is about 1.8 times that of SCPF:0.02 Eu~(2+) and electron trap centers serve as energy transporting media.To further elucidate the formation and effect of the specific defect on the luminescence of SCPF:0.02 Eu~(2+),0.02 Dy~(3+) phosphor,the thermoluminescence properties,decay curves and thermal stability studies were performed while the Si~(4+)-P~(5+) charge compensated pho sphor SCPF:0.02 Eu~(2+),0.02 Dy~(3+),0.02 Si~(4+) was prepared as a contrast.All the results of present work indicate that Dy~(3+) co-doping can obviously enhance photoluminescence intensity of SCPF:0.02 Eu~(2+) by the electron traps generated by non-equivalence replacement of Dy~(3+)-Ca~(2+).     

Studies on the Voltammetric Behaviors of Rare Earth Ions-Amino Acids

The voltammetric behaviors of rare earth ions-amino acids were studied.The reduction potential of Eu~(3+)was shifted positively and the peak separation of the cathodic and anodic peaks in cyclic voltammogram de-creased when a certain amino acid was added to Eu~(3+) solution.Experimental results showed that Eu~(3+) was re-duced by way of forming complexes with amino acids which were adsorbed on mercury electrode surface.Whenhistidine and formaldehyde existed simultaneously in the solution containing Eu~(3+),a well-defined reversiblecatalytic prewave of Eu~(3+) was obtained.Meanwhile,the reduction current of formaldehyde increased greatlywith the addition of histidine.The mechanism was studied.Several other rare earth ions and amino acids werealso studied preliminarily.     

Eu3+、Tb3+、Dy3+与L-脯氨酸、甘氨酸、L-丙氨酸四元固态配合物的荧光光谱研究

对在水中合成的稀土元素(Eu 、Tb 、Dy)与L-脯氨酸(L-Pro)、甘氨酸 (Gly)、L-丙氨酸(L-Ala)四元固态配合物的荧光光谱进行了研究.结果表明铕、铽配合物的荧光强度均较其相应的盐高(铕高出4.5倍,铽高出9倍);四元配合物的荧光强度较三元配合物有不同程度的提高;四元配合物中,铽的荧光强度较铕的荧光强度高出近11倍.同时对上述实验结果进行了解释.     

Optical performance study of Sr_2ZnSi_2O_7:Eu~(2+),Dy~(3+), SrAl_2O_4:Eu~(2+),Dy~(3+) and Y_2O_2S:Eu~(3+),Mg~(2+),Ti~(4+) ternary luminous fiber

In this study, down-conversion fluorescent powder of Sr_2ZnSi_2O_7:Eu~(2+),Dy~(3+), SrAl_2O_4:Eu~(2+),Dy~(3+) and Y_2O_2S:Eu~(3+),Mg~(2+),Ti~(4+), which were the common three primary colors materials with long afterglow, were synthesized by high temperature solid state method. The blends of rare earth(RE) luminescent materials have been of interest to reinvest the luminescent characteristics of polyethylene terephtahalate(PET) luminous fiber. The scanning electron microscopy(SEM) and an inversion fluorescence microscope were used to characterize the surface morphology and the dispersion of inclusion. Through analysis of microcosmic morphology, three typical dispersions of luminescent particles were summarized. The X-ray diffraction indicated that the phase structure of fiber samples and crystal structure of luminescence materials kept complete after prilling and spinning. From the fluorescence spectra and CIE 1931 coordinates, it could be found that different combinations of luminous fibers were desired to obtain divers colors emission luminous fiber. And the fiber samples were a light sensation which could induct different excitation wavelengths and convert it down to different colors. The afterglow decay curve and its differential curve were summarized indicating the three decay stages. The decay curve and decay rate curve showed that the contents of Sr_2ZnSi_2O_7:Eu~(2+),Dy~(3+), SrAl_2O_4:Eu~(2+),Dy~(3+) and Y_2O_2S:Eu~(3+),Mg~(2+),Ti~(4+) had obvious influence on the afterglow of fiber samples.     

Precipitation-dissolution behaviors of rare earth ions in H_3PO_4-Ca(H_2PO_4)_2 solutions

In order to achieve deeper understanding of rare earth elements(REEs) behaviors during phosphate rock processing with H_3PO_4. The solubility of REEs in Ca(H_2PO_4)_2-H_3PO_4 solutions with various concentrations of Ca(H_2PO_4)_2 at different temperatures were tested. The results demonstrate that REEs solubility decreases sharply with the increasing concentration of Ca(H_2PO_4)_2. Equations between [REE~(3+)] and [H~+],[H~+] and [Ca~(2+)] in Ca(H_2PO_4)_2-H_3PO_4 solutions were built based on the precipitation-dissolution equilibrium of rare earth phosphates and the ionization equilibrium of H_3PO_4. According to the equations, the decreasing mechanism of REEs solubility caused by elevated concentration of Ca(H_2PO_4)_2 was determined. The mechanism can be illustrated as that the elevated concentration of [H_2 PO_4~-] decreases the concentration of hydrogen ion by retarding the ionization process of H_3PO_4 and directly promotes the precipitation of rare earth phosphates. Furthermore, it can be easy deduced that similar effect would be caused by the other cation impurities(Fe~(3+), Al~(3+), etc.) on REEs solubility based on the mechanism. In addition, superimposed reduction effect on REEs solubility caused by the elevated concentration of Ca(H_2PO_4)_2 and the elevated temperature is found. This superimposed effect leads to a super low solubility of REEs in Ca(H_2PO_4)_2-H_3PO_4 solution. On the basis of the experimental study, outlooks and suggestions for further development of REEs recovery method are given.     

The trivalent cerium-induced cell death and alteration of ion flux in sweetpotato [Ipomoea batatas(L.) Lam]

The rare earth element cerium(Ce) in its several forms is extensively utilized in various fields, including nano-technology, agriculture, and the food industry. Due to its increasing unregulated usage, Ce is now a potential source of pollution and toxicity due to its excessive environmental accumulation. Unfortunately, analysis of the toxic effects of Ce in plants is still in its early stages. Herein, we investigated the effects of Ce3+ treatment on development-related indicators in sweetpotato. We found that a low concentration(10 mg/L) slightly improved oxidation resistance, while a high concentration(20-80 mg/L)negatively affected development and photosynthesis and triggered increases in reactive oxygen species(ROS) production, antioxidant enzyme activities, and malondialdehyde(MDA) content. Moreover,elevation and efflux of cytosolic Ca~(2+) and caspase-l-like activity were induced by high-concentration Ce~(3+) treatment. Finally, cell viability decreased as Ce3+ concentration increased. These results suggest that(1) a high Ce3+ concentration(20-80 mg/L) inhibits development and photosynthesis of sweetpotato and induces oxidative damage followed by lipid peroxidation in the root,(2) a caspase-l-like protease is induced by cytosolic Ca~(2+) and ROS overproduction to cause programmed cell death in the root, and(3) a high concentration of Ce3+ could trigger a hypothetical cell death pathway, wherein Ce3+induces ROS production followed by cytosolic Ca~(2+) elevation, which activates caspase-l-like activity,which in turn leads to programmed cell death in the root of sweetpotato.     

溶胶-凝胶法制备YAG:Ho~(3+),Yb~(3+)纳米晶

以稀土氧化物和硝酸铝为原料,采用溶胶-凝胶法合成了YAG:1%Ho~(3+),1%Yb~(3+)纳米晶,并通过正交试验法确定其干凝胶的合成条件.采用DTA-TG、XRD及TEM对干凝胶的合成过程、纳米晶的晶相组成及形貌进行了研究,表明干凝胶经1 200 ℃煅烧后形成了结晶完全的YAG相,无中间相产生.吸收光谱和上转换发射光谱分析表明,Yb~(3+)在材料的发光过程中具有传递能量的作用,Ho~(3+)在跃迁过程中发射出中心波长为650 nm的红色上转换荧光及540 nm的绿色上转换荧光.     

稀土对生物机体剂量效应机理的研究进展

综述了稀土元素对生物机体剂量效应的机理 ,从稀土对细胞质膜、细胞周期及细胞凋亡、Ca M水平调节的作用到对蛋白质、DNA的影响等不同层次和水平进行了探讨 ,以期为稀土在生物学领域的进一步广泛应用奠定理论基础