LaDAlY型沸石表面羟基和酸性的研究

应用红外光谱和NH₃-TPD法对LaDAlY型沸石的表面羟基和酸性进行了研究,从将La³⁺离子引入NH₄Y和DAlY后表面羟基的变化中探讨了La³⁺离子在NH₄Y和DAlY中的分布,吡啶吸附及脱附的红外光谱表明,在DAlY中引入La³⁺后B酸和L中心数均减少;NH₃-TPD的结果表明,在DAlY中引入La³⁺离子后,其弱酸中心的强度稍有增加,而强酸中心的强度基本不变,酸中心数一般减少,其结果与吡啶-IR结果一致。     

12-钨磷酸及其盐的酸性与催化性能的研究

红外法研究结果表明12-钨磷酸Fe³⁺、Mg²⁺和Na⁺盐都具有L酸点和B酸点。用Benesi法测得10种12-钨磷酸盐的酸强度顺序为(Al³⁺、Fe³⁺、La³⁺、Cu²⁺、Cd²⁺>Zn²⁺>(Ca²⁺、Mg²⁺>(Na⁺、Li⁺,其酸量与抗衡阳离子的离子势和电负性大体成线性关系。还看出酸量与所含结晶水量有关。催化剂的酸量与其对异丙醇脱水反应和丁烯-1异构化反应的催化活性的关系表现出不同的特征,这可用“体相型”和“表面型”催化作用的不同特点来解释。     

La3+-NaY型沸石的水热交换反应

作者根据在100℃、180℃时La³⁺-NaY型沸石交换反应等温线的测定和十三种单一稀土(Ln)元素在180℃时的交换度与相应Ln³⁺离子水合焓关系的研究以及在不同温度下交换反应速率常数、反应级数与交换反应表观活化能的测定,比较系统地研究了La³⁺-NaY型的水热交换反应,从而比较有据地提出这类交换反应的机理。     

低量La3+掺杂S-TiO2光催化剂的制备、表征及其光催化活性

采用溶胶-凝胶-浸渍法制备了La³⁺/S-TiO₂纳米光催化剂,通过XRD、BET、XPS、UV-Vis等手段进行了表征.以甲基橙溶液为光催化降解反应的模型化合物,考察了光催化剂的活性,探讨了低量La³⁺掺杂对TiO₂纳米粒子光催化活性的影响机制.实验结果表明:S改性TiO₂后明显提高了TiO₂纳米粒子的光催化活性,而La³⁺掺杂S-TiO₂后,进一步提高了TiO₂纳米粒子的光催化活性,La³⁺的最佳掺杂量(相对于TiO₂的质量分数)为0.369%;La³⁺/S-TiO₂(ω(La³⁺)=0.369%)为纳米光催化剂时,甲基橙的脱色率达到92.4%(光照120min);XRD和BET分析表明,低量La³⁺掺杂抑制了TiO₂由锐钛矿向金红石的转变,阻碍了TiO₂晶粒的生长,提高了TiO₂的比表面积;XPS分析表明,S、La³⁺掺杂可以导致粉体的表面羟基含量增加,掺杂S以S⁶⁺形式置换TiO₂晶格中的Ti⁴⁺;UV-Vis分析表明,光催化剂La³⁺/S-TiO₂比纯TiO₂具有较强的紫外光吸收性能.与纯TiO₂相比,La³⁺掺杂TiO₂纳米粒子光催化氧化活性的提高应归因于La³⁺掺杂增加了表面羟基含量,增大了比表面积,增强了样品表面的紫外光吸收能力.     

Lu(La)2O3微米晶中提高Bi3+离子下转换蓝光发光性能的研究

采用尿素沉淀法制备一系列Bi³⁺/La³⁺共掺Lu₂O₃和Bi³⁺/Lu³⁺共掺La₂O₃微米晶。在掺杂Bi³⁺离子的Lu₂O₃微米晶中,C₂位点的Bi³⁺离子可以将吸收的能量转移给S₆位点的Bi³⁺离子。同时,在Lu₂O₃:1%Bi³⁺,0～5%(摩尔分数,下同)La³⁺微米晶中,372和337 nm(C₂和S₆位点的Bi³⁺离子)紫外光的激发下,Bi³⁺离子的发射峰强度随着La³⁺离子掺杂浓度的增加而增加,掺杂5%La³⁺时与不掺杂La     

4-(二乙氨基)水杨醛缩4-氨基安替比林席夫碱的合成及荧光性质

合成了4-(二乙氨基)水杨醛缩4-氨基安替比林席夫碱，通过红外光谱、核磁共振谱、元素分析等对其结构进行了表征。利用分子荧光仪对其与Zn²⁺、Ni²⁺、Co²⁺、Pb²⁺、Cd²⁺、La³⁺、Ce³⁺、Sr²⁺、Ag⁺、Ru³⁺等金属离子作用前后的荧光性质进行了检测。检测结果表明，加入不同的金属离子后，该希夫碱的荧光发射波长略有变化，但荧光强度发生了不同程度的改变，其中Ru³⁺与希夫碱作用后的荧光强度显著增强。     

高特异性的La3+靶向多肽探针及其在细胞和斑马鱼成像中的应用

研究报道了一种新型多肽探针(TPE-Glu-Glu-Pro-Gly-Glu-Glu-NH₂),该多肽探针单独存在时没有荧光，稀土元素镧离子(La³⁺)加入后，与多肽探针特异性结合，限制了四苯乙烯(TPE)分子内的旋转，导致溶液产生强的荧光信号。该探针具有特异性，16种常见金属的存在也几乎不影响其对La³⁺的靶向检测。我们研究发现，谷氨酸在多肽探针结合La³⁺的过程中发挥重要作用，减少谷氨酸个数会影响其特异性识别。滴定和Job工作曲线结果表明，该多肽探针与La³⁺结合比为1∶2,结合常数为1.29×10¹⁰(L/mol)²。计算机模拟结果表明，La³⁺与多肽探针酰胺键的氧和谷氨酸羧基中羟基的氧结合。该探针可以高灵敏检测水溶液和唾液中的La³⁺,检测限分别为0.12μmol/L和0.32μmol/L。该高灵敏、高特异性多肽探针具有良好的生物相容性，可以用于细胞和斑马鱼中La³⁺     

La3+掺杂CaFe2O4材料的制备及室温检测超低浓度甲醛

采用静电纺丝法成功制备了La³⁺掺杂CaFe₂O₄材料。通过X射线衍射、扫描电子显微镜和X射线光电子能谱对La³⁺掺杂CaFe₂O₄材料的结构和形貌进行了表征。随后,研究了La³⁺的掺杂量(质量分数)对CaFe₂O₄气敏性能的影响。研究表明,3%La³⁺掺杂CaFe₂O₄材料在室温下对100μL·L^-1甲醛的响应最高(R_a/R_g=14.1)。更为重要的是,对甲醛的最低检测限低至0.1 nL·L^-1,并且响应/恢复时间仅为4.3 s/8.4 s。     

N,N′-二甲基-N,N′-二辛基-4-氧庚二酰胺萃取镧的研究

为了研究不同的酰胺夹醚化合物对萃取镧的性能，本文使用N,N′-二甲基-N,N′-二辛基-4-氧庚二酰胺(DMDOOHA)为萃取剂，以1-甲基-3-丁基咪唑六氟磷酸盐离子液体([C₄mim⁺][PF₆^-])为稀释剂，研究其在水相中萃取La³⁺的行为，考察了萃取时间，pH,萃取剂的的浓度、及温度对萃取分配比的影响。实验表明，萃取剂在离子液体[C₄mim⁺][PF₆^-]中对La³⁺的具有强烈的萃取能力。机理研究表明，在([C₄mim⁺][PF₆^-]体系中，萃取剂与La³⁺可能形成3∶1配合物。萃取过程为热力学自发的过程。     

色层法检测王冠化合物对稀土元素的络合能力

本文应用反相纸色层法和静态吸附平衡法检测了王冠化合物与稀土离子之间的络合能力和水相阴离子类型对络合能力的影响。所用的王冠化合物有:B-15-C-5,DB-18-C-6,四氢呋喃丙酮四聚体,DB-18-C-6-甲醛缩聚物和B-15-C-5-甲醛缩聚物。得到如下主要结果:1.不同王冠化合物的络合能力顺序是;B-15-C-5>DB-18-C-6》四氢呋喃丙酮吗聚体,另B-15-C-5-甲醛缩聚物>DB-18-C-6-甲醛缩聚物。2.稀土离子络合能力的顺序是:Sm³⁺Er³⁺=La³⁺(反相纸色层法),Er³⁺>Eu³⁺>La³⁺(吸附平衡法)。3.与不同阴离子缔合的离子对的稳定性顺序是:苦味酸根>三氯代乙酸根>磺基水杨酸根》Cl^-、NO₃^-、ClO₄^-及SO₄⁼。     

金属离子在冠醚化合物为载体的液膜体系中传输的研究

液膜分离是近年才发展起来的一种新分离技术^[1]。早在1968年Tosteson^[2]就已观察到冠醚化合物在人造膜中对K⁺、Na⁺离子的选择性与天然大环化合物在细胞膜中的作用具有共同之处。Cussler^[3]曾测定了DB-18-C-6为载体的液膜中一些金属离子的传输通量。Lamb^[4]比较了以DB-18-C-6、DT-18-C-6及DKP-18-C-6为载体的氯仿液膜中Pb²⁺/Na⁺、Pb²⁺/Ca²⁺、Pb²⁺/Fe³⁺、Pb²⁺/Zn²⁺的选择比。     

Determination of stability constants for rare earth elements and fulvic acids extracted from different soils

Fulvic acids (FAs) were extracted by alkali extraction from different soil samples in China, then purified using resins and characterized by Fourier transform infrared spectroscopy. The complexing ability of FAs was investigated by measuring the stability constants of rare earth elements (REEs) (La³⁺, Ce³⁺, Sm³⁺, Gd³⁺, Y³⁺) with FAs by the ion exchange technique. The results indicated that maximum binding ability forY³⁺ (4.414.44) was higher than other REEs (La³⁺, Ce³⁺, Sm³⁺, Gd³⁺) (0.721.03). There were two types of binding sites in the functional groups of fulvic acids. The complexing reaction followed two steps. The stability constants (K₁ and K₂) of REEs with FAs were calculated from experimental data by division of Scatchard plots into two straight-line segments. Y³⁺ (log K₁=5.72±0.05, log K₂=4.83±0.01) also has higher stability constants than the other four REEs (log K₁=4.37±0.16, log K₂=3.62±0.28).     

稀土离子跨人血红细胞膜的荧光法研究

采用Fura-2荧光浓度指示剂对红细胞的稀土跨膜作用进行了系列研究.结果表明,稀土离子不能通过完整的红细胞膜进入细胞内.通过与离子载体实验相对照,发现细胞ATP耗竭后,低浓度的稀土离子(5×10^-6mol/L)不能跨膜进入ATP-耗竭红细胞.KCl去极化及加入电压依赖性钙通道刺激剂Bay-K8644对稀土离子的跨膜也没有促进作用.在Ca²⁺内流正常的情况下,低浓度稀土离子(5×10^-6mol/L)对钙离子内流无影响.增大稀土离子浓度到5×10^-4mol/L,用显微镜观察此时红细胞已开始溶血.在模拟胞内离子组分的缓冲液中(pH=7.05),比较了La³⁺,Eu³⁺和Ca²⁺对Fura-2的敏感程度.此条件下Fura-2对La³⁺和Eu³⁺的检测限分别为10-12和10-14mol/L,对Ca²⁺的检测限为10-8mol/L,并测得Fura-2-La³⁺(Eu³⁺)的络合比为1∶1,表观离解常数为1.7×10^-12和4.95×10^-14mol/L,表明用此法检测稀土离子跨膜行为相当灵敏有效.     

La~(3+)掺杂NiCo层状双金属氢氧化物纳米片的合成及其电化学性能

稀土离子La~(3+)掺杂的NiCo层状双金属氢氧化物纳米片具有高的超级电容器性能,比容量达到1115 F/g(1A/g)、倍率性能为517 F/g(30 A/g)。研究表明,La~(3+)离子掺杂不改变NiCo层状双金属氢氧化物晶体结构,但会显著影响其电子和离子传导特性,从而改变其电化学性能。根据离子电负性标度,La~(3+)(1.327)和Co~(2+)(1.377)离子的电负性值最接近,掺杂La~(3+)会优先取代Co~(2+)离子位置。由于La~(3+)离子的尺寸作用(106 pm),使得最优掺杂比例较小仅为0.26%,电化学结果表明较少的La~(3+)掺杂比例依然会显著调节NiCo层状双金属氢氧化物的电子/离子输运性质。     

Effect of La on heat production by mitochondria isolated from hybrid rice

The effect of lanthanum on mitochondria isolated from hybrid rice Fengyou 559 (Oryza sativa L.) was investigated. Through in vivo culture, low-dose La³⁺ promoted, but higher dose La³⁺, restrained mitochondrial heat production. However, through in vitro incubation, La³⁺ manifested only inhibitory action on mitochondrial energy turnover, the concentration required for 50% and 100% inhibition being 50.9 and 230.2 μM (57.6 nmol/mg protein), respectively. In addition, La³⁺, like Ca²⁺, induced rice mitochondrial swelling and decreased membrane potential (Δψ), which was inhibited by the specific permeability transition inhibitor cyclosporine A (CsA). The induction approached a constant limitation while mitochondrial metabolism was completely prevented by La³⁺, and microscopy observation showed a high disruption of inner mitochondrial membrane in this state. These results demonstrated that lanthanum influenced rice mitochondria in vivo and in vitro via different action pathways, and the latter involved the opening of rice mitochondrial permeability.     

Influence of La3+ on the Phase Behavior and the Pluidity of Phospholipid Bilayers

The influence of La³⁺ on the phase behavior and the fluidity of the negatively charged phospholipid dipalmitoylphosphatidylglycerol(DPPG) bilayers was studied by differential scanning calorimetry (DSC) and FT-Raman spectroscopy. La³⁺, induced a phase separation of DPPG bilayers, and formed three peaks. La³⁺ increased the phase transition temperature of the new peaks, broadened the half width of the DSC signal, and stabilized a gel phase relative to a crystalline phase of DPPG bilayers. La³⁺ was shown to increase interchain order and intermolecular ordering of the lipid lattice, and decreased the fluidity of DPPG bilayers.     

Density functional studies of the reactivity in the C–F bond activation of fluoromethane by bare lanthanum monocation

The potential energy surface and reaction mechanism corresponding to the reaction of lanthanum monocation with fluoromethane, which represents a prototype of the activation of C–F bond in fluorohydrocarbons by bare lanthanide cations, have been investigated for the first time by using density functional theory. A direct fluorine abstraction mechanism was revealed, namely after coordination of CH₃F to La⁺, electron transfer from La⁺ to the fluorine takes place, which favours the homolytic cleavage of the C–F bond to form LaF⁺ species and methyl radical. The related thermochemistry data involved in reaction of La⁺+CH₃F were determined, which can act as a guide for further experimental researches. The electron-transfer reactivity of the reaction was analyzed by using a state correlation diagram, in which a strongly avoided crossing behaviour on the transition state region was shown. The calculated state split energy between the ground and excited state on the transition state is 18.01 kcal mol⁻¹. The reaction of La⁺ with CH₃F was concluded to process in the adiabatic potential surface. The present results support the reaction mechanism inferred early from experimental data.