The role of coke in the deactivation of Mo/MCM-22 catalyst for methane dehydroaromatization with CO2

The effect of space velocity on reaction performance and coke deposition over 6Mo/MCM-22 catalyst in methane dehydro-aromatization (MDA) with CO2 were studied. The characterization of catalysts reacted at different space velocity after the same amount of methane feed by TG, TPO and Benzene/NH3-TPD techniques suggested that the inert coke maybe responsible for the deactivation of catalyst because of its blockage effect for pore system.

红松针叶的凋落及其分解速率研究

在长白山森林生态系统研究中 ,对红松 (Pinus koraiensis)针叶凋落情况及其分解过程进行研究 ,表明 ,红松针叶一般可存活 3～ 4 a,调查中存活最长的为 6a。红松针叶的寿命与光照密切相关 ,在针叶密集及透光不足的地方针叶寿命较短。红松针叶凋落后 ,在林地上分解较快 ,一般 4 a后其干重保持率为 1 6.6%。模拟实验证明 ,红松针叶的分解率与海拔和植被类型密切相关。在海拔低的红松阔叶林下 ,因气温高 ,分解较快 ;在海拔较高的云冷杉红松林和岳桦林中分解速度变慢 ;在高山苔原带分解最慢

沿海防护林体系生态环境效益及评价技术

本文是“八五”国家科技攻关专题“沿海防护林体系生态经济效益及其评价技术”的阶段性研究成果，在国内首次系统地阐明了沿海防护林体系的中尺度气象效应、区域性气候效应、降盐改土效应、海堤林带的固土护堤效应和沿海农田林网的抗灾保产效应。

一种测量林窗面积的改良方法:等角椭圆扇形法

目前测量林窗面积较精确的方法为:测量从林窗中心沿8或16个罗盘方向到林窗林冠边缘的距离,再将林窗近似成等角8或16边形估测其面积(本文称这类方法为等角多边形法)。研究表明,等角8或16边形法均会低估林窗面积,本文提出一种改良方法:等角椭圆扇形法,野外测量与前者相同,计算时将相邻距离间的部分近似为椭圆扇形,以所有椭圆扇形面积之和估测林窗面积。用配对t检验对等角多边形法和等角椭圆扇形法的林窗面积进行比较,结果表明:(1)等角16边形法与等角8或4边形法存在极显著差异(P<0.001),比后两者,分别高10.96%和61.66%,这表明等角条边形法均会低估林窗面积;(2)等角椭圆扇形16分法比等角16边形法大10.16%,且二者之间存在极显著差异(P<0.001),因此,等角16边形法的测量值位于等角椭圆扇形16分法和等角8边形法之间;由(1)和(2)可推断等角椭圆扇形16分法比等角8边形法更准确;(3)等角椭圆扇形8分法与等角椭圆扇形16分法没有显著差异(P=0.715),但与等角8边形法存在显著差异(P<0.05),因此,等角椭圆扇形8分法比等角8边形法更准确。另外,本文的两个等角8边形法(基于两组不同罗盘方位的测量距离)求得的林窗面积之间存在极显著差异(P<0.01),而两个等角椭圆扇形8分法之间却没有差异(P=0.778),这表明等角椭圆扇形8分法的结果更稳定。

l-序列的采样元素分布及k-错线性复杂度

证明了极大周期FCSR序列的任意采样序列在一个周期内0,1元素分布几乎平衡,利用这一分布性质研究了连接数为强2-素数的l-序列的k-错线性复杂度,结果显示这类l-序列具有非常稳定的线性复杂度。

水热微乳液法合成BaLiF_3:Er~(3+)纳米微粒及表征

采用水/CTAB/正丁醇/正辛烷体系微乳液法及水热技术制备了BaLiF3∶Er3+纳米微粒。利用X射线衍射(XRD)、环境扫描电镜(ESEM)和红外荧光光谱等手段对所制备产物进行了表征。X射线衍射数据表明,所制备微粒与JCPDS标准卡片18-715吻合很好,利用谢乐公式计算所制备产物平均粒径在98.45 nm左右,与环境扫描电镜观察结果基本相同。BaLiF3∶Er3+纳米微粒的红外发射图谱由4个峰构成,最强峰位于1540 nm处,属于Er3+的f→f跃迁。

稀土钐离子与微过氧化物酶-11的相互作用初探

近年来,含稀土元素钐的药物研究已见报道犤1,2犦。但倪嘉缵等的研究犤3犦表明,Sm3+进入生物体内后可在肝细胞中分布、沉积,从而使肝细胞内细胞色素浓度降低。因此从分子水平研究Sm3+与某些生物分子的相互作用机理是十分必要的。众所周知,过氧化物酶能清除生物体内产生的过氧自由基,对机体具有抗逆、抗衰老的功效犤4,5犦。而微过氧化酶-11(MP-11)具有与过氧化物酶相同的活性中心和相似的生物活性犤6犦,因此,本文用循环伏安法、紫外-可见(UV-vis)吸收光谱以及圆二色(CD)谱技术研究了作为过氧化酶模型化合物的MP-11与Sm3+的相互作用。1实验部分MP-11购自美国Sigma公司,SmCl3按文献合成犤7犦。其他试剂均为分析纯,溶液均用三次蒸馏水配制。循环伏安测量在美国EG&G公司的M273恒电位仪上采用三电极系统进行,玻碳电极为工作电极,饱和甘汞电极为参比电极,铂丝为对电极。测量前用高纯氮除氧30min,在实验中用氮气保护。UV-Vis吸收光谱在岛津UV-265型紫外-可见分光光度计上进行,收集差光谱数据。CD谱在JASCOJ-715型圆二色谱仪上进行。MP-11和SmCl3的混合溶液配制后平衡1h,然后...

由联苯酚双肉桂酸酯制备光控取向膜

通过光敏小分子的光交联反应制备了光控取向膜 ,研究了光照时间对取向膜红外二向色性的影响及光照角度对预倾角的影响 ,并在偏光显微镜下观察了液晶的排列织构。结果表明 ,光照 15 min时 ,红外二向色性比值 D达最大 ,液晶排列最均匀。光照角度对该膜的预倾角影响不大。

Thermal influence on excimer-laser-induced electrical conductivity on polyimide film surfaces

The thermal influence on the electrical conductivity of polyimide film surfaces induced by KrF-laser irradiation was investigated, The formation of conducting phases was demonstrated to be highly temperature sensitive, as evidenced by strong dependence of the electrical conductivity on repetition rate and ambient temperature. XPS and Raman studies showed that the efficiency of the formation of conducting phases could be enhanced by the increase of temperature on irradiated polyimide film surfaces. After the disruption of polymeric chain, the carbon-enriched clusters remained on the irradiated polyimide film surfaces organized into polycrystalline graphite-like clusters responsible for electrical conductivity. The resulting dangling bonds from the decomposition process of polyimide acted as centers for the rearrangement of carbon-enriched clusters. It is suggested that the motion of radicals was promoted with increasing the temperature. Therefore the formation of polycrystalline graphite-like clusters benefited from high remaining temperature on the irradiated polyimide film surfaces. These results revealed that thermal influence played a dominant role on the formation of conducting phases.

Spectroscopic study of the photophysical properties of rare earth ions encapsulated: Water soluble functional calixresorcin[4]arene

A novel macrocyclic compound-water soluble functional calixresorcin[4]arenes-tetra para sulfo-phenylmethyl-calixresorcin[4]are was synthesized for the first time. The photophysical properties of terbium and europium ions encapsulated in the macrocyclic ligand were studied in detail. The triplet state energy of the calixresorcin[4]arene was determined to be 24400 cm(-1) by the low temperature phosphorescence spectrum and it was found that it can sensitize both terbium ion and europium ion. The possible energy transfer process between the functional calixresorcin[4]arene and the encapsulated Tb3+ and Eu3+ was discussed. The luminescence quantum efficiency of Tb3+- calixresorcin[4]arene was calculated.

Studies on the electrochemical reduction of cyanocobinamide

It was found that cyanocobinamide (CN-Cbi) can be reduced at about -0.50V. The reduction process has an EC mechanism, i.e. the electrochemical reduction of CN-Cbi is accompanied by a decyanation of CN-Cbi. The electrochemical characteristics of CN-Cbi and vitamin B-12 were compared.

DETERMINATION OF AMINOPYRINE AND ITS METABOLITE BY CAPILLARY ELECTROPHORESIS ELECTROCHEMICAL DETECTION

An electrochemical pretreatment regime for a cylindrical carbon fibre microelectrode was optimized for the determination of aminopyrine (AM) and its metabolite 4-aminoantipyrine (AAN) by capillary electrophoresis (CE)-electrochemical detection (ED). Under optimized conditions, a response of high sensitivity and stability was obtained for AM and AAN at a detection voltage as low as 0.9 V following CE-ED, by which AM and AAN were separated satisfactorily. The calibration graph was linear over three orders of magnitude and the limits of detection for AM and AAN were in the femtomole range.

谷胱甘肽与稀土离子作用的~(13)C NMR研究

本文利用顺磁稀土离子的诱导化学位移变化的性质,研究了多官能团配体谷胱甘肽(GSH)与稀土的配位作用.在水溶液中GSH通过分子两端的羧基负离子与稀土形成遥爪配位结构.谷氨酸端和甘氨酸端羧基与Eu~(3+)的配位稳定常数分别为12.5±0.1L/mol和100.0±0.5L/mol.从~(13)C化学位移的pH变化曲线求得谷氨酸端和甘氨酸端羧基解离的pK_a值分别为2.20±0.02和3.50±0.04.对Dy~(3+)、Ho~(3+)、Er~(3+)、Tm~(3+)和 Yb~(3+)作用下,GSH的~(13)C位移数据分析表明,配体与这些离子形成同构的配合物,分子两端羧基均可能以双齿形式与稀土配位.