Influence of iron promoter on catalytic properties of Rh-Mn-Li/SiO2 for CO hydrogenation

The effect of iron promoter on the catalytic properties of Rh-Mn-Li/SiO2 catalyst in the synthesis Of C-2 oxygenates from syngas was investigated by means of the following techniques: CO hydrogenation reaction, temperature-programmed reduction (TPR), temperature-programmed desorption and reaction of adsorbed CO (CO-TPD and TPSR) and pulse adsorption of CO. The results showed that the addition of iron promoter could improve the activity of the catalysts. Unexpectedly, the yield of C-2 oxygenates increased greatly from 331.6 up to 457.5 g/(kg h) when 0.05% Fe was added into Rh-Mn-Li/SiO2 catalyst, while no change in the selectivity to C-2 oxygenates was observed. However, the activity and selectivity Of C-2 oxygenates were greatly decreased if the Fe amount exceeded 1.0%. The existence of a little iron decreased the reducibility of Rh precursor, while the reduction of Fe component itself became easier. CO uptake decreased with increasing the quantity of Fe addition. This phenomenon was further confirmed by CO-TPD results. The CO-TPD and TPSR results showed that only the strongly adsorbed CO could be hydrogenated, while the weakly adsorbed CO was desorbed. We propose that Fe is highly dispersed and in close contact with Rh and Mn; such arrangements were responsible for the high yield Of C-2 oxygenates. (C) 2002 Elsevier Science B.V. All rights reserved.

Theoretical study on the ClO/ClO- system electron-transfer reactivity by the golden-rule

The structures, properties and electron transfer reactivity of the ClO/ClO- coupling system are studied in this paper at ab initio (UHF and UMP2) levels and the Density Functional Theory (DFT: UB3LYP, UB3P86, UB3PW91) levels employing 6311 + G(3df) basis set and on the basis of the Golden-rule of the time-dependent perturbation theory. Investigations indicate that the results obtained using the UB3LYP method employing 6-311 + G(3df) basis set is in excellent agreement with the experiment. For this coupling system, six stable coupling modes have been found which correspond to six different encounter complexes and denote six different electron transfer mechanism: four O-O directly linked structures (one collinear: D-h, one anti-parallel: C-s, two twist: C-2) and two Cl-O linked structures (cis- and anti- C-s structures). The activation energies, the stabilization energies and the electronic coupling matrix elements have also been calculated for the electron transfer reactions via these six different mechanism at the UB3LYP/6-311 + G(3df) level, and then the electron transfer rates are determined at the same level. The most favorable coupling mode to the electron transfer is the anti-parallel mechanism. The averaged electron transfer rate is about 5.58 X 10(11) M-1 s(-1). It is also implied that the B3LYP method can give more reasonable results for the electron transfer reactivity of this system. (C) 2003 Elsevier B.V. All rights reserved.

黄河源区退化高寒草地土壤种子库:种子萌发的数量和动态

对青藏高原黄河源区不同退化程度高寒草地的土壤种子库土样用土壤分析筛进行浓缩,并以萌发法分析土壤种子库萌发种子数量和动态.结果表明,孔径0.25~2 mm的土壤分析筛分离土样中萌发种子可达萌发种子总量的85%~97%,而小于0.25 mm的土样中未发现种子.因此,用0.25 mm孔径大小的土壤筛对高寒草地土壤种子库土样进行大规模浓缩是一种方便、可靠的方法.4种不同退化程度高寒草地(A:未退化草甸;B:轻度退化草甸;C:中度退化草甸;D:重度退化草甸)的土壤种子库在实验室条件下萌发的种子数量分别为:A 1 194~3 744粒/m2,平均2 421.3粒/m2;B 5 376~1 0912粒/m2,平均7 786.7粒/m2;C 2 304~1 3216粒/m2,平均8 695.5粒/m2;D 4 768~12 352粒/m2,平均8 125.9粒/m2.除样地A外,其它3个样地的可萌发种子数量差异不大.单子叶植物种子在培养到d 10左右开始萌发,双子叶植物在5~7 d内开始萌发,前者3 wk后基本不再萌发,后者5 wk左右停止萌发.4个样地土壤种子库种子萌发主要集中在第2~3周,并表现出近似单峰型格局.图1表3参39

混合培养中巨大芽孢杆菌对氧化葡萄糖酸杆菌的作用

为查明维生素C二步发酵混合培养中巨大芽孢杆菌与氧化葡萄糖酸杆菌间的关系,通过生长曲线测定、静息细胞实验及摇瓶发酵实验研究了巨大芽孢杆菌对氧化葡萄糖酸杆菌生长和产生2酮基L古龙酸作用的影响;采用超滤分离、凝胶层析及聚丙烯酰胺凝胶电泳技术对巨大芽孢杆菌胞外液中具有促进氧化葡萄糖酸杆菌产酸作用的活性物质进行了分离和纯化.结果表明,大菌胞内液和胞外液均可促进小菌生长,大菌胞外液中具有该作用的组分分子量在100KDa以上;大菌胞外液具有促进小菌转化L山梨糖生成2酮基L古龙酸的作用,其胞内液无该作用;大菌胞外液中具有该活性作用的组分为30～50KDa和大于100KDa两个部分.其中30～50KDa范围的大菌胞外液中的活性组分为一种蛋白质,其表观分子量约为35KDa,由一种亚基构成,且该蛋白含金属铁和锌元素

芘在土壤中的共代谢降解研究

高分子量多环芳烃 (PAHs)的降解通常以共代谢方式进行 .研究比较了高分子量多环芳烃代表种类芘作为唯一C源和能源的降解过程和有共代谢底物存在下芘的降解过程 ,结果表明 ,2 5d后前者中芘的降解率5 7% ,而后者中芘的降解率为 80 % .且有共代谢底物存在下 ,芘在降解过程中半衰期缩短 ;水杨酸 ,邻苯二甲酸 ,琥珀酸钠能作为共代谢底物提高芘的降解率 ,琥珀酸钠效果最好 .芘和低分子量多环芳烃之间也有共代谢关系 ,菲促进了芘的降解 ,但萘未出现同样的结果 .此外 ,这阐明了共代谢原理和适宜作高分子量多环芳烃共代谢底物的物质 .

水分处理对沙地樟子松幼苗膜脂过氧化作用及保护酶活性影响

通过盆栽控水实验,模拟科尔沁沙地由东至西50年的年均降水量及最大、最小年降水量下的土壤水势,分析了不同水分处理(土壤水势分别为-16.18、-5.09和-4.50bars,即A、B和C处理)对樟子松2年生幼苗膜脂过氧化产物[丙二醛(MDA)、脂膜相对透性(RC)和超氧阴离子自由基(O2.-)产生速率]、渗透调节物质[可溶性糖(SS)、可溶性蛋白(SP)和脯氨酸(Pro)]和膜保护酶(SOD酶和POD酶)的影响。不同水分处理对樟子松幼苗针叶内的保护酶、渗透调节物质及膜脂过氧化的作用影响显著。随着土壤水势的降低,幼苗的SOD酶呈现微下降再升高的趋势;POD酶活性呈逐渐升高的趋势;幼苗的渗透调节物质(SS、SP和Pro)的含量均呈现上升趋势;3种水分处理的可溶性糖和可溶性蛋白含量上升的幅度最大,A处理分别是C处理的1.8倍和2.4倍,脯氨酸的含量持续积累;随干旱胁迫加重,MDA、RC和O2.-产生速率均有明显上升趋势,以O2.-产生速率上升幅度最大。这表明,樟子松幼苗通过体内的生理生化机制,尤其是增加渗透调节物质的含量,实现对干旱胁迫较强的忍耐性和较好的适应性。A处理针叶内的自由基大量积累和膜脂过氧化程度加重,对植物造成不可逆的损伤。

感觉门控的跨半球现象及其在吗啡成瘾过程中的应用研究

本论文的实验研究部分主要包括"正常被试同侧和对侧大脑半球通路听觉诱发电位门控的机制研究"和"吗啡依赖的建立和戒断过程中大鼠海马感觉门控（Sensorygating）的动态变化"。第一部分为了探讨感觉门控发生的神经生物学机制，在第一部分实验中，我们着重研究了感觉门控在同侧和对侧大脑半球的发生机制。感觉门控反映了大脑对听觉信息的加工处理过程。双声听诱发电位抑制模式在实验研究和临床方面已经广泛被用来评估感觉门控能力。当两个相同的声音刺激以500ms的时间间隔先后给予双耳时，第二个声音的听诱发电位P50成份的幅度会明显地受到第一个声音的抑制，这就是通常所说的P50抑制或是声诱发电位门控抑制。然而当这两个相同的声音刺激先后（也是500ms间隔）以相同方向（同侧）和不同方向（对侧）给予单侧耳朵时，感觉门控功能（表现为PSO前抑制和N100前抑制）是否能在同侧和对侧大脑半球之间发生是不清楚的。在本实验中，双耳双声刺激，同侧单耳双声刺激（包括左耳双声和右耳双声两种）和对侧单耳双声刺激（包括先右耳后左耳和先左耳后右耳两种）五种模式分别给予25个健康的正常被试者。同时在正常被试者的前额叶皮层（左侧和右侧）和颖叶皮层（左侧和右侧）四个脑区分别记录听觉诱发电位进而来评估P50和N100成份的抑制。实验结果显示：（1）P50和N100抑制（表现为T／C抑制比）在四个记录脑区和五种刺激模式下都没有性别之间的明显差异。（2）统计分析结果显示P50和N功O成份前抑制功能（表现为T／C抑制比）在四个记录的脑区没有明显差别。（3）五种不同的声音刺激模式对P50抑制功能（表现为T／C抑制比）具有显著性作用。具体表现为：在双侧双耳声刺激模式和同侧单耳双声刺激模式下，第二个声音诱发的P50成份的诱发电位幅度明显地受到第一个声音的抑制，即P50抑制发生；当相同的两个声音以对侧单耳双声刺激模式给予被试时，第二个声音诱发的PSO幅度很少受到第一个声音抑制，即P50抑制不发生。（4）正常被试声诱发电位N100成份在五种不同的声音刺激模式下都表现出正常的门控抑制（表现为T／C抑制比）并且相互之间没有统计学上的显著性差别。因此与P50成份不同，在对侧单耳双声刺激条件下较晚成份N100仍然具有正常的感觉门控能力。以上结果表明了，在标准的双耳双声刺激条件下N100成份具有和P50成份相似的门控抑制能力。另外，感觉门控（包括P50和N100抑制）能够在同侧大脑半球之间发生，这个结果意味着决定感觉门控的听觉通路可能以与调控双耳双声相似的方式调控同侧声音刺激。另一方面，较早成份P50抑制不能在对侧大脑半球之间发生，而与之相关的听觉通路却能够调控较晚成份N100抑制在对侧大脑半球之间发生。这可能是由于大脑半球之间的交叉联系在较长的时间里允许更多的听觉信息到达对侧半球而导致的。当前的实验结果可能反映了感觉门控在两侧大脑半球之间发生的某些特征。第二部分感觉门控可以"过滤"一些无关刺激进入以保护大脑免受干扰性信息的影响。听觉诱发电位抑制是常用来评估感觉「丁控能力的一种方法。由于感觉门控机制与边缘系统多巴胺的活动密切相关，并且门控能力很可能反映了吗啡成瘾过程中大脑状态。因此，在第二部分实验中，我们观察了在吗啡依赖的建立和戒断过程中吗啡对大鼠海马感觉门控（N4O成份）的影响作用。在实验中通过连续六天十二次（每天两次，间隔12小时）的盐酸吗啡腹腔注射使大鼠建立吗啡依赖，随后停止吗啡注射使大鼠处于自发的戒断阶段。在吗啡依赖的建立和戒断过程中检测海马感觉门控。而且，多巴胺DZ受体的拮抗剂氟派吮醇（haloPeridoD被用来检测多巴胺在吗啡弓｝起的海马感觉「1控变化中的作用。我们的结果显示出：（1）与对照组相比吗啡实验组在吗啡依赖的建立过程中海马感觉门控能力明显地被干扰；（2）氟派陡醇预处理作用会部分地恢复或逆转这个受损的（降低的）海马门控；（3）并且在连续地三天吗啡注射后，海马感觉门控受到损伤，表明了吗啡对海马门控的慢性作用；（4）与吗啡依赖阶段的结果相反，在吗啡戒断的第五天和第六天，吗啡实验组大鼠表现出明显提高的感觉门控。在吗啡依赖的建立和戒断过程中分别观察到的降低的和提高的海马感觉门控可能与海马结构的多巴胺神经传递活动有关。该实验结果与药物（包括吗啡）成瘾过程中多巴胺的神经传递活动的变化是一致的，同时也又进一步证明了多巴胺对感觉门控具有调控作用。最后，在吗啡成瘾过程中海马感觉门控的这种显著变化有力地表明了海马参与吗啡成瘾并暗示了海马与阿片类物质之间的相互作用。

Rare-earth-metal mixed hydride/aryloxide complexes bearing mono(cyclopentadienyl) ligands. Synthesis, CO2 fixation, and catalysis on copolymerization of CO2 with cyclohexene oxide

Hydrogenolysis of mono(cyclopentadienyl)-ligated rare-earth-metal bis(alkyl) complexes Cp'Ln-(CH2SiMe3)2(THF) (Ln = Y (1a), Dy (1b), Lu (1c); Cp' = C5Me4SiMe3) with PhSiH3 afforded the mixed hydride/alkyl complexes [Cp'Ln(mu-H)(CH2SiMe3)(THF)](2) (Ln = Y (2a), Dy (2b), Lu (2c)). The overall structure of complexes 2a-c is a C-2-symmetric dimer containing a planar symmetric Ln(2)H(2) core at the center of the molecule. Deprotonation of ArOH (Ar = C6H2-Bu-t(2)-2,6-Me-4) by the metal alkyl group of 2a-c led to formation of the mixed hydride/aryloxide derivatives [Cp'Ln(mu-H)(OAr)](2) (Ln = Y (3a), Dy (3b), Lu (3c)), which adopt the dimeric structure through hydride bridges with trans-accommodated terminal aryloxide groups.

Highly efficient white organic light-emitting devices based on a multiple-emissive-layer structure

Characteristics of white organic light-emitting devices based on phosphor sensitized fluorescence are improved by using a multiple-emissive-layer structure, in which a phosphorescent blue emissive layer is sandwiched between red and green&yellow ones. In this device, bis[(4,6-difluorophenyl)-pyridinato-N,C-2] (picolinato), bis(2,4-diphenyl-quinoline) iridium (III) acetylanetonate, fac bis (2-phenylpyridine) iridium, and 5,6,11,12-tetraphenylnaphthacene are used as blue, red, green, and yellow emitters, respectively.

Efficient white organic light-emitting diodes using europium complex as the red unit

Efficient white organic light-emitting diodes (WOLEDs) using europium complex as the red unit are presented. The WOLEDs were fabricated by using the structure of indium tin oxide (ITO)/N, N'-di(naphthalene-1-yl)-N, N'-diphenyl-benzidine (NPB)/4,4-N, N-dicarbazolebiphenyl (CBP) : bis(2,4-diphenylquinolyl-N, C-2) iridium (acetylacetonate) ((PPQ)(2)Ir(acac)) : Eu (III) tris(thenoyltrifluoroacetone) 3,4,7,8-tetramethyl-1,10-phenanthroline (Eu(TTA)(3)(Tmphen))/NPB/2-methyl-9,10-di(2-naphthyl)anthracene (MADN) : p-bis (p-N, N-di-phenyl-aminostyryl)benzene (DSA-Ph)/9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP)/tris(8-hydroxyquinoline) aluminium (Alq3)/LiF/Al.

Red-Emitting Polyfluorenes Grafted with Quinoline-Based Iridium Complex: "Simple Polymeric Chain, Unexpected High Efficiency"

A series of red-light emitting electrophosphorescent polyfluorenes (PFs) with varying content of a quinoline-based iridium complex, (PPQ)(2)Ir(acac) (bis(2,4-diphenylquinolyl-N,C-2') iridium(acetylacetonate)), in the side chain are synthesized by Suzuki polycondensation. Because of the efficient Forster energy transfer from the PF main chain to (PPQ)(2)Ir(acac) and direct charge trapping on the complex, the electroluminescent emission from PF is nearly completely quenched, even though the amount of iridium complex I incorporated into the polymers is as low as 1 mol %. Based on a single-layer device configuration, a luminous efficiency of up to 5.0 cd A(-1) with a luminance of 2000 cd m(-2) and Commission Internationale de L'Eclairage coordinates of (0.63, 0.35) (x, y) is realized, which is far superior to that of previously reported red-light emitting PFs containing benzothiazole- and isoquinoline-based iridium complexes.

Harvesting Excitons Via Two Parallel Channels for Efficient White Organic LEDs with Nearly 100% Internal Quantum Efficiency: Fabrication and Emission-Mechanism Analysis

By incorporating two phosphorescent dyes, namely, iridium(III)[bis(4,6-difluorophenyl)-pyridinato-N,C-2']picolinate (Flrpic) for blue emission and bis(2-(9,9-diethyl-9H-fluoren-2-yl)-1-phenyl-1 H-benzoimidazol-N,C-3) iridium(acetylacetonate) ((fbi)(2)Ir(acac)) for orange emission, into a single-energy well-like emissive layer, an extremely high-efficiency white organic light-emitting diode (WOLED) with excellent color stability is demonstrated. This device can achieve a peak forward-viewing power efficiency of 42.5 lm W-1, corresponding to an external quantum efficiency (EQE) of 19.3% and a current efficiency of 52.8 cd A(-1). Systematic studies of the dopants, host and dopant-doped host films in terms of photophysical properties (including absorption, photoluminescence, and excitation spectra), transient photoluminescence, current density-voltage characteristics, and temperature-dependent electroluminescence spectra are subsequently performed, from which it is concluded that the emission natures of Flrpic and (fbi)(2)Ir(acac) are, respectively, host-guest energy transfer and a direct exciton formation process. These two parallel pathways serve to channel the overall excitons to both dopants, greatly reducing unfavorable energy losses.

Achieving highly efficient white organic light-emitting diodes with reduced efficiency roll-off

A highly efficient and colour-stable three-wavelength white organic light-emitting diode with the structure of indium tin oxide (ITO)/MoO3/N,N'-diphenyl-N,N'-bis (1-naphthylphenyl)-1,1'-biphenyl-4,4'-diamine (NPB)/4,4'-N,N'-dicarbazole-biphenyl (CBP): bis(2,4-diphenylquinolyl-N,C-2') iridium( acetylacetonate) (PPQ)(2)Ir(acac)/NPB/p-bis(p-N,N-diphenyl-aminostyryl)benzene (DSA-Ph):2-methyl-9,10-di(2-naphthyl) anthracene (MADN)/tris (8-hydroxyquinoline) aluminum (AlQ): 10-(2-Benzothiazolyl)-2,3,6,7-tetrahydro-1,1,7,7-tetramethyl-1H,5H,11H-(1)-benzopyropyrano(6,7-8-i,j)quinolizin-11-one (C545T)/AlQ/LiF/Al is fabricated and characterized. A current efficiency of 12.3 cdA(-1) at an illumination-relevant brightness of 1000 cd m(-2) is obtained, which rolls off slightly to 10.3 cdA(-1) at a rather high brightness of 10 000 cd m(-2). We attribute this great reduction in the efficiency roll-off to the wise management of singlet and triplet excitons between emissive layers as well as the superior charge injection and diffusion balance in the device.

Nonconjugated Carbazoles: A Series of Novel Host Materials for Highly Efficient Blue Electrophosphorescent OLEDs

A series of carbazole derivatives was synthesized and their electrical and photophysical properties were investigated. It is shown that the triplet energy levels of these hosts are higher than that of the most popular blue phosphorescent material iridium(III) bis[(4,6-difluorophenyl)pyridinato-N,C-2'] picolinate (FIrpic) and the most extensively used phosphorescent host material 4,4'-N,N'-dicarbazole-biphenyl (CBP). These new host materials also showed good thermal stability and high glass transition temperatures (T-g) ranging from 78 to 115 degrees C as the linkage group between the carbazoles was altered. Photophysical measurements indicate that the energy transfer between these new hosts and FIrpic is more efficient than that between CBP and FIrpic. Devices incorporating these novel carbazole derivatives as the host material doped with FIrpic were fabricated with the configurations of ITO/NPB (40 nm)/host:FIrpic (30 nm)/BCP (15 nm)/AlQ (30 nm)/LiF (1 nm)/Al (150 nm). High efficiencies (up to 13.4 cd/A) have been obtained when 1,4-bis (4-(9H-carbazol-9-yl)phenyl)cyclohexane (CBPCH) and bis(4-(9H-carbazol-9-yl)phenyl) ether (CBPE) were used as the host, respectively.

3D 异金属Bi(III)-Pr(III)配位聚合物的合成、晶体结构和热稳定性

在水溶液中合成了双金属配位聚合物({[(NO3)(H2O)3Pr(μ4-Hedta)Bi-(NO3)2].2H2O}2)n,并通过元素分析、红外光谱和X射线单晶衍射等手段进行了表征.该配合物为单斜晶系,P2(1)/n空间群,a=1.26831(18)nm,b=0.82189(12)nm,c=2.3755(3)nm,β=105.055(2)°,R=0.0429,V=2.3913(6)nm3,Z=4.Bi(Ⅲ)-Pr(Ⅲ)间通过配阴离子Hedta3-中4个羧基的桥联作用构建配合物的3D结构.TG-DSC结果表明,该配合物热分解经历脱水、配体分解以及盐分解过程,残余物为Bi-Pr-O的三元复合氧化物.