稀土杂多化合物在溶液中的￣（183）W核磁共振表征

~（１８３）Ｗ核磁共振研究确认，Ｌａ（ＡｓＷ_（１１））_２、Ｌａｍ（Ａｓ_２Ｗ_（１７））_２在溶液中仍保持其四方反棱柱的Ｃ_３结构，Ｌａ（ＳｉＷ_９ＭＯ_２）_２阴离子中，２个Ｍｏ原子取代了２个等价的Ｗ原子，在穴状杂多阴离子ＬｎＡｓ_４Ｗ_（１０）和ＬｎＳｂ_９Ｗ_（２１）中，稀土离子占据中心Ｓ_１位置，ＳｉＷ_９与稀土离子生成（ＬｎＯ）_３（ＳｉＷ_９）_２型杂多阴离子。

Dawson结构杂多阴离子~（183）W NMR谱的研究──“极位”W原子~（183）W NMR谱化学位移值的预测

本文研究了Ｄａｗｓｏｎ结构取代原子数与相应的１８３ＷＮＭＲ谱中“极位’Ｗ原子的化学位移值间的关系，预测广α－１，２－［Ｐ２Ｗ１６Ｎｂ２Ｏ６２］８－α－１－２，３－［Ｐ２Ｗ１５ＭｏＮｂ２Ｏ６２］８－“极位”Ｗ原子１８３ＷＮＭＲ谱化学位移们，结果α－１，２－［Ｐ２Ｗ１６Ｎｂ２Ｏ６２］８－中与取代Ｎｂ相连“极位”Ｗ原子的化学位移值为－８８ｐｐｍ，与取代Ｎｂ书对称“极位”Ｗ原了的化学位移值为－１４４．７ｐｐｍ，与取代Ｎｂ不对称“极位”Ｗ原子的化学位移值为－１３０．５ｐｐｍ，α－１－２，３－［Ｐ２Ｗ１５ＭｏＮｂ２Ｏ６２］８－中与取代Ｍｏ对称“极位”Ｗ原子的化学位移值为－１３４．７ｐｐｍ，与取代Ｎｂ对称“极位”Ｗ原子的化学位移值为－１４５．６ｐｐｍ．

Dawson结构钨铌磷杂多配合物~(183)W NMR谱的研究

过渡金属离子取代的杂多钨酸盐,具有金属叶啉的类似结构,在烯烃环氧化反应中具有比金属叶啉更优异的催化活性和选择性,特别重要的是其抗氧化性能强,在烯烃基质存在下比金属叶啉稳定,催化寿命持久,并称其为无机金属叶啉,因而引起人们的极大关注.

掺W对Bi系中高Tc超导相的影响

自Maeda发现高Tc超导体BiSrCaCuO以来,引起了人们广泛兴趣;由于它有较高的超导转变温度(Tc>100K),无剧毒、价廉和自高温冷却到室温无结构相变等特点,Bi系是一很有实用前景的高Tc超导体;已经确定Bi系中含有三个超导相(2201,2212,2223相),但是迄今要制得较纯的2223高Tc相还有一定困难,无疑这对它的基础研究和实用开发都受到了限制,因此制备更纯的Bi系2223相具有重要的意义。

Extraction behavior of Mo and W as homologs of Sg with α-benzoinoxime

Solvent extraction of molybdenum and tungsten as homologues of Sg with a-benzoinoxime from HCl solutions has been investigated. The extraction equilibration was achieved at 20s for Mo and W. Molybdenum was almost quantitatively extracted from 0.001 to 4M HCl solutions, and the extraction yields decreased at higher and lower acid concentrations due to the formation of anionic oxychloride complex and anionic species MO42-, respectively. The extraction yield of W was lower than that of Mo during the whole range of acid concentration. The composition of the extracted species was determined by using the slope method in present experiment. The elemental analysis, IR and 1H NMR spectra of the extracted species suggest that the extracted complex contain one MoO22+or WO22+ groups bonded with two a-benzoinoxime molecules.

A simple and low-cost airlift photobioreactor for microalgal mass culture

A simple, low-cost, and efficient airlift photobioreactor for microalgal mass culture was designed and developed. The reactor was made of Plexiglas, and composed of three major parts: outer tube, draft tube and air duct. The fluid-dynamic characteristics of the airlift reactor were studied. The system proved to be well suited to the mass cultivation of a marine microalga, Chlorella sp. In batch culture, the biomass volumetric output rate of 0.21 g l(-1) d(-1) was obtained at the superficial gas velocity of 4 mm s(-1) in the draft tube.

Outer wave number spectrum and statistical distribution of apparent wave number vector

Based on the ray theory and Longuet-Higgins's linear,model of sea waves, the joint distribution of wave envelope and apparent wave number vector is established. From the joint distribution, we define a new concept, namely the outer wave number spectrum, to describe the outer characteristics of ocean waves. The analytical form of the outer wave number spectrum, the probability distributions of the apparent wave number vector and its components are then derived. The outer wave number spectrum is compared with the inner wave number spectrum for the average status of wind-wave development corresponding to a peakness factor P = 3. Discussions on the similarity and difference between the outer wave number spectrum and inner one are also presented in the paper. (C) 2002 Elsevier Science Ltd. All rights reserved.

湘西沃溪Au-Sb-W矿床中白钨矿Sm-Nd和石英Ar-Ar定年

利用白钨矿对金属矿床进行了Sm-Nd同位素定年. 研究结果表明, 湘西沃溪Au-Sb-W矿床中白钨矿的Sm, Nd含量较高, Sm/Nd值较大. 在147Sm/144Nd-143Nd/144Nd图解中, 浸染状白钨矿样品呈良好的线性分布, 其对应的等时线年龄为402±6 Ma, εNd(t)值为−30.7. 该矿两个石英样品的40Ar-39Ar年龄谱均呈“马鞍型”, 样品的最小视年龄、坪年龄和等时线年龄基本一致, 其最小视年龄(420±20和414±19 Ma)与白钨矿的Sm-Nd同位素数据相当吻合. 白钨矿的Sm-Nd年龄和石英Ar-Ar年龄均表明沃溪矿床形成于加里东晚期, 这与湖南雪峰山地区的构造演化和一些金锑钨矿床的同位素年代数据相吻合. 白钨矿的初始εNd值异常低, 远低于湖南元古宇地层的相应值, 成矿流体中的Nd很可能来自下伏的更老的陆壳基底. 对该矿成矿时间的厘定和对其成矿物源的制约为进一步认识其矿床成因奠定了基础.