Fourth-derivative spectrophotometric determination of neodymium in mixed rare earths with methyl thymol blue and cetylpyridinium chloride

A sensitive and selective method is described for the determination of neodymium in mixed rare earths using fourth-derivative spectrophotometry. The method is based on the absorption spectra of 4f electron transitions of the complex of neodymium with methyl thymol blue and cetylpyridinium chloride. The influence of various instrumental parameters and reaction conditions for maximum colour development are investigated. The calibration curve is linear over the range 0–3.5 g ml^–1 neodymium. The relative standard deviation for determination of 1.4 g ml^–1 neodymium (n = 7) is 1.6%. The detection limit (signal-to-noise ratio = 3) is 0.2 g ml^–1.     

二(2,4,4-三甲基戊基)膦酸萃取分离稀土元素(Ⅲ)的研究

本文研究了二(2,4,4-三甲基戊基)磷酸(Cyanex 272)的煤油溶液在不同介质(HCI,HNO_3)中对三价混合稀土的萃取分离性能.观测了平衡水相酸度对萃取平衡的影响,由酸度曲线求出相邻元素的平均分离系数,并考察了酸度对反萃取平衡的影响.比较了HCI和HNO_3介质中,Cyanex 272对混合稀土(Ⅲ)的萃取性能.     

Aluminum Lon Removal from Monoaluminum Ovotransferrin by Pyrophosphate

The rates at which aluminum was removed from the N- and C-terminal monoaluminum ovotransferrins by pyrophosphate were evaluated by UV difference spectra in 0.01 mol/L Hepes, pH=7.4 and at 37℃. Pesudo first-order rate constants as a function of pyrophosphate concentration were measured. The results indicate that the pathways of aluminum removal are different. For the N-terminal binding site, aluminum removal follows simple saturation kinetics, while the removal of aluminum from the C-terminal binding site reverts to the combination of saturation and first-order kinetics. The saturation component is consistent with a rate-limiting conformational change in the protein as has been reported. We propose that the first-order kinetics mechanism is attributed to a pre-equilibrium process. The rate constants of saturation kinetics are accelerated from both terminals with the addition of 0.1 mol/L chloride to the monoaluminum ovotransferrin solutions, whereas the rates of the first-order kinetics are decreased for the C-terminal binding site. The effect of chloride ionic strength causes a continuing increase on kobs for the N- and C-terminal binding sites. Moreover, the kinetics behavior of the N-terminal is more easily affected by chloride than that of the C-terminal. In the experiment presumably the N-terminal site is apparently kinetically more labile than the C-terminal site.     

茂基稀土胺化物与异氰酸正己酯的反应-{(MeC5H4)2Yb[OC(NPh2)N(n-hexyl)]}2的合成及表征

茂基稀土胺化物(MeCp)2YbNPh2(THF)与异氰酸正己酯(n-HexylNCO)按11摩尔比反应, 分离出产物{(MeC5H4)2Yb[OC(NPh2)N(n-hexyl)]}2. 产物经元素分析和核磁共振表征, 并测定了其晶体结构. 配合物属三斜晶系, R-3空间群, 晶胞参数为a=2.9533(11) nm, b=2.9533(11) nm, c=1.5873(6) nm, V=11.9896(80) nm3, Z=9, Dc=1.562 mg·m-3, μ=3.536 mm-1 (Mo Kα), F(000)=5670, R=0.034, Rw=0.064. 该化合物具有二个对称氧桥的双分子结构, 并存在着由氮原子向中心金属镱分子内配位而形成的三环骨架, 中心金属镱的配位数是九, 整个分子呈中心对称.     

凝胶型聚合物电解质的电导率与温度的关系

凝胶型聚合物电解质的电导率与温度的关系孙晓光，林云青，齐力，景遐斌，王佛松（中国科学院长春应用化学研究所长春１３００２２）关键词凝胶电解质，离子电导率，活化能无定形聚合物电解质电导与温度的依赖关系一般可用Ｖｏｇｅｌ－Ｔａｍｍａｎ－Ｆｕｌｃｈｅｒｃ（Ｖ...     

Study on EPR Spectra of Three Gadolinium Complexes With Noncyclic Polyether Schiff Bases

The EPR spectra of three new gadolinium complexes with noncyclic polyether Schiff bases in powder and those of these complexes in organic solvents were investigated at different temperatures. It was observed that EPR spectra of nine and four peaks of Gd(Ⅲ) complexes in polycrystalline powder and freezing samples appeared at low temperature respectively for the first time. The interpretations of these results obtained on the basis of spin Hamiltonian of s = 7/2 system are satisfactory. The correlations of EPR feature between crystal-field strength in complexes and local symmetry around Gd3+ ions were revealed. The crystal-field parameters b20 and the asymmetry parameters λ' of complexes were estimated. A series of interesting regularity and new results were obtained.     

三角波交流示波极谱的研究(Ⅰ)——示波极谱图的性质

用三角波电流代替正弦波电流,进行交流示波极谱滴定,所得示波极谱图与正弦波结果相似。对一些离子的滴定表明,两法所得结果均在定量分析允许误差范围以内。报道了三角波交流示波极谱图的一些性质。     

Melamine cyanurate-microencapsulated red phosphorus flame retardant unreinforced and glass fiber reinforced polyamide 66

A novel microencapsulated red phosphorus (RP) was prepared through the molecular self-assembly of melamine cyanurate (MCA). Compared with the conventional encapsulated RP, MCA-encapsulated RP (MERP) shows simpler and more environment-friendly preparation process higher thermal stability and lower moisture absorption. With MERP filled in unreinforced polyamide 66 (PA66) and glass fiber (GF) reinforced PA66, flame retardant materials with satisfactory flame retardancy and mechanical performance can be obtained. The influence of the MCA/RP ratio on the flame retardancy as well as the condensed phase of MERP flame retardant PA66 was investigated to reveal the nitrogen-phosphorus (N-P) synergistic flame retarding effects between MCA and RP.     

NMR SPECTROSCOPIC STUDY ON COPOLYMER OF ETHYLENE-NORBORNENE

A series of ethylene-norbornene copolymers were synthesised using VO (OEt) Cl_2/Al_2Et_3Cl_3 catalytic system and their structure was characterized by ~1H-NMR, ~1H-~1HCOSY NMR and ~(13)C-NMR. Assignments of NMR spectra were given and discussed indetail.     

Complete 1H and 13C NMR assignments of four new steroidal glycosides from a gorgonian coral Junceella juncea

Four new cholest-type steroidal glycosides, junceellosides A-D, isolated from the EtOH/CH(2)Cl(2) extracts of the South China Sea gorgonian coral Junceella juncea, were identified. Complete assignments of the (1)H and (13)C NMR chemical shifts for these compounds were achieved by means of one- and two-dimensional NMR techniques, including (1)H-(1)H COSY, HSQC, HMBC and NOESY spectra.