杂多酸盐K_4H[SiMO_(11)VO_(40)]·18H_2O 1和K_4H_2[PMo_9V_3O_(40)]·18H_2O 2的晶体结构

杂多酸是种类多,应用广的重要的无机化合物。其中有一类是12-系列化合物Z,(XM_(12-n)M_n′O_(40))·mH_2O,中心离子X可以是过渡元素或非过渡元素;M常是Mo、W;M′为V_(5+)、Mn_(2+)、CO_(2+)等;n=0,1,2…;Z为H~+或一价阳离子;y=1,2,…。它们同其相应氧化型化合物比较具有引人注目的特性,但迄今尚未见到还原型化合物晶体结构文章,只是

K_4H_2[PMo_9V_3O_(40)]·10H_2O的合成及其晶体结构

采用低温技术,用 X 射线单晶衍射法测定了标题化合物的结构.晶体属 P4/mnc 空间群,a=12.515(3),c=17.636(7),Z=2.用788个独立可观测反射精修所有结构参数得 R=0.061.钼钒磷杂多酸阴离子中,PO_4四面体是无序的,P—O 键长1.54.M(Mo,V)是6配位,M—O 键长1.62—2.48.K 是7配位,K—O 键长2.84—3.10.

TWO SPECIFIC CAUSES OF CELL MORTALITY IN FREEZE-THAW CYCLE OF YOUNG THALLI OF PORPHYRA YEZOENSIS (BANGIALES, RHODOPHYTA)1

Porphyra yezoensis Ueda is an important marine aquaculture crop with single-layered gametophytic thalli. In this work, the influences of thallus dehydration level, cold-preservation (freezing) time, and thawing temperature on the photosynthetic recovery of young P. yezoensis thalli were investigated employing an imaging pulse-amplitude-modulation (PAM) fluorometer. The results showed that after 40 d of frozen storage when performing thallus thawing under 10 degrees C, the water content of the thalli showed obvious effects on the photosynthetic recovery of the frozen thalli. The thalli with absolute water content (AWC) of 10%-40% manifested obvious superiority compared to the thalli with other AWCs, while the thalli thawed at 20 degrees C showed very high survival rate (93.10%) and no obvious correlation between thallus AWCs and thallus viabilities. These results indicated that inappropriate thallus water content contributed to the cell damage during the freeze-thaw cycle and that proper thawing temperature is very crucial. Therefore, AWC between 10% and 40% is the suitable thallus water content range for frozen storage, and the thawing process should be as short as possible. However, it is also shown that for short-term cold storage the Porphyra thallus water content also showed no obvious effect on the photosynthetic recovery of the thalli, and the survival rate was extremely high (100%). These results indicated that freezing time is also a paramount contributor of the cell damage during the freeze-thaw cycle. Therefore, the frozen nets should be used as soon as time permits.

He, Ne and Ar isotopic composition of Fe-Mn crusts from the western and central Pacific Ocean and implications for their genesis

The noble gas nuclide abundances and isotopic ratios of the upmost layer of Fe-Mn crusts from the western and central Pacific Ocean have been determined. The results indicate that the He and Ar nuclide abundances and isotopic ratios can be classified into two types: low He-3/He-4 type and high He-3/He-4 type. The low He-3/He-4 type is characterized by high He-4 abundances of 191x10(-9) cm(3.)STP(.)g(-1) on average, with variable He-4, Ne-20 and Ar-40 abundances in the range (42.8-421)x10(-9) cm(3.)STP(.)g(-1), (5.40-141)x10(-9)cm(3.)STP(.)g(-1), and (773-10976)x10(-9) cm(3.)STP(.)g(-1), respectively. The high He-3/He-4 samples are characterized by low He-4 abundances of 11.7x10(-9) cm(3.)STP(.)g(-1) on average, with He-4, Ne-20 and Ar-40 abundances in the range of (7.57-17.4)x10(-9) cm(3.)STP(.)g(-1), (110.4-25.5)x10(-9) cm(3.)STP(.)g(-1) and (5354-9050)x10(-9) cm(3.)STP(.)g(-1), respectively. The low He-3/He-4 samples have He-3/He-4 ratios (with RIRA ratios of 2.04-2.92) which are lower than those of MORB (R/R-A=8 +/- 1) and Ar-40/Ar-36 ratios (447-543) which are higher than those of air (295.5). The high He-3/He-4 samples have He-3/He-4 ratios (with R/R-A ratios of 10.4-12.0) slightly higher than those of MORB (R/R-A=8 +/- 1) and Ar-40/Ar-36 ratios (293-299) very similar to those of air (295.5). The Ne isotopic ratios (Ne-20/Ne-22 and Ne-21/Ne-22 ratios of 10.3-10.9 and 0.02774-0.03039, respectively) and the Ar-38/Ar-36 ratios (0.1886-0.1963) have narrow ranges which are very similar to those of air (the Ne-20/Ne-22, Ne-21/Ne-22, Ar-38/Ar-36 ratios of 9.80, 0.029 and 0.187, respectively), and cannot be differentiated into different groups. The noble gas nuclide abundances and isotopic ratios, together with their regional variability, suggest that the noble gases in the Fe-Mn crusts originate primarily from the lower mantle. The low He-3/He-4 type and high He-3/He-4 type samples have noble gas characteristics similar to those of HIMU (High U/Pb Mantle)- and EM (Enriched Mantle)-type mantle material, respectively. The low He-3/He-4 type samples with HIMU-type noble gas isotopic ratios occur in the Magellan Seamounts, Marcus-Wake Seamounts, Marshall Island Chain and the Mid-Pacific Seamounts whereas the high He-3/He-4 type samples with EM-type noble gas isotopic ratios occur in the Line Island Chain. This difference in noble gas characteristics of these crust types implies that the Magellan Seamounts, Marcus-Wake Seamounts, Marshall Island Chain, and the Mid-Pacific Seamounts originated from HIMU-type lower mantle material whereas the Line Island Chain originated from EM-type lower mantle material. This finding is consistent with variations in the Pb-isotope and trace element signatures in the seamount lavas. Differences in the mantle surce may therefore be responsible for variations in the noble gas abundances and isotopic ratios in the Fe-Mn crusts. Mantle degassing appears to be the principal factor controlling noble gas isotopic abundances in Fe-Mn crusts. Decay of radioactive isotopes has a negligible influence on the nuclide abundances and isotopic ratios of noble gases in these crusts on the timescale of their formation.

祁连山海北高寒湿地40～80cm土壤温度状况观测分析

海北高寒湿地土壤水分达超饱和状态,土体热容量大,因而地温在随时间进程中变化平稳,日、年较差较小. 年内季节冻土并不深厚,多维持于1 m 左右,小于高山草甸土分布区. 由于50 cm 层次年平均地温仅为1. 2 ℃,暖季的6～9 月平均为2. 8 ℃左右. 因此,按温度诊断特点来看,该类型高寒湿地土在中国土壤分类中属寒冷性土壤温度状况,仍为正常有机土.

长石及其伴生矿物的~(40)Ar/~(39)Ar法对比研究

~(40)Ar-~(39)Ar法是继K-Ar法后发展起来的一个新的年代学分支，自1962年Sigurgeirssion正式提出~(40)Ar-~(39)Ar计时理论以来，经C. M. Merrihue, G. Turner, G. B. Dalrymple, M. A. Lanphere, I. McDougall, J. G. Mitchell等人的不断改造和完善，现已发展成为一门较为成熟的学科。~(40)Ar-~(39)Ar法以其独特的优点而倍受地质学家的偏爱，其中阶段加热技术是~(40)Ar-~(39)Ar法得以广泛应用的关键，它不仅可以提供一般的年代学资料，同时，还提供诸如样品的受热历史、过剩Ar、封闭温度以及岩体的隆起速率等许多信息。近十年来，对这一领域的研究，无论是在理论方面，还是在实验技术方面，都取得了可喜的进展。