环己酮肟在改性氧化锆催化剂上的Beckmann重排反应Ⅱ．影响重排反应的若干因素

环己酮肟在改性氧化锆催化剂上的Ｂｅｃｋｍａｎｎ重排反应Ⅱ．影响重排反应的若干因素程时标徐柏庆唐守平蒋山蔡天锡王祥生（大连理工大学化工学院化学系，大连１１６０１２）关键词氧化硼，氧化锆，负载型催化剂，环己酮肟，Ｂｅｃｋｍａｎｎ重排反应，己内酰胺前文［１...     

Secondary succession and its effects on soil moisture and nutrition in abandoned old-fields of hilly region of Loess Plateau, China

Floristic composition, community structure and soil moisture and nutrient contents in abandoned fields of different ages were analyzed to clarify the regenerative aspects of succession as a tool for vegetation restoration. The results indicated that secondary succession in this region can be interpreted as an auto-succession: there are main changes in species-relative abundance and species turnover. Annual or biennial species (e.g. Artemisia scoparia), acted as pioneers and strongly dominated the early stages. Then, they underwent a progressive decline, while forbs (e.g. Artemisia sacrorum) and grasses (e.g. Xanthium sibiricum) had their peak abundance at intermediate stages. Dwarf shrubs (e.g. Lespedeza dahurica) and short rhizome grass (e.g. Bothriochloa ischaemum) appeared at mid-succession stage and gradually increased in abundance during succession, becoming dominant at late stages. The first axis of detrended correspondence canonical analysis arranged the sites according to their fallow time, indicating a successional sere. The second axis, associated with diverging pathways of regeneration, correlated with topographic factors and soil moisture and nutrition. Structural divergence between plots increased as succession went on, attained the highest at the mid-succession stage, decreased at the late stage.

Soil moisture and available phosphorus content decreased steadily with field age after their abandonment, whereas pools of organic matter, total and available nitrogen, potassium and total phosphorus increased with field age. The pace and direction of recovery of native vegetation and natural soil properties in these abandoned fields resembled classic old-field succession, which is a form of secondary succession that often serves as a template for guiding restoration efforts. Interface between the abandoned field soil and plant system was crucial to the above process. Our current study supported the generally accepted hypothesis in the succession literature.     

Identification of Hydroxyl on Ni(111)

Hydroxyl (OH) is identified and characterized on the Ni(111) surface by high‐resolution electron energy loss spectroscopy. We find clear evidence of stretching, bending, and translational modes that differ significantly from modes observed for H₂O and O on Ni(111). Hydroxyl may be produced from water by two different methods. Annealing of water co‐adsorbed with atomic oxygen at 85 K to above 170 K leads to the formation of OH with simultaneous desorption of excess water. Pure water layers treated in the same fashion show no dissociation. However, the exposure of pure water to 20 eV electrons at temperatures below 120 K produces OH in the presence of adsorbed H₂O. In combination with temperature‐programmed desorption studies, we show that the OH groups recombine between 180 and 240 K to form O and immediately desorbing H₂O. The lack of influence of co‐adsorbed H₂O at 85 K on the O? H stretching mode indicates that OH does not participate in a hydrogen‐bonding network.     

A new ent-labdane eiterpenoid lactone from Andrographis paniculata

A new ent-labdane diterpenoid lactone with a new natural product was isolated from Andrographis paniculata. Their structures were elucidated on the basis of spectral evidences including 2D NMR.     

Trace determination of hexabromocyclododecane diastereomers in water samples with temperature controlled ionic liquid dispersive liquid phase microextraction

A novel temperature controlled ionic liquid dispersive liquid phase microextraction(TCIL-DLPME) coupled with rapid resolution liquid chromatography-electrospray tandem mass spectrometry(RRLC-ESI-MS-MS) has been developed for the enrichment and determination of three hexabromocyclododecane diastereomers(HBCDs) in water samples.Green solvent ionic liquid(IL) was used as extraction solvent instead of toxic organic solvents.This technique also avoided the usage of dispersive solvent.Some important parameters that might affect the extraction efficiency were optimized.Under the optimum conditions,good linear relationship,sensitivity and reproducibility were obtained.All the limits of detection for the three diastereomers were 0.1 ng/ mL.The linear range was obtained in the range of 1-100 ng/mL for the total amount of three HBCD diastereomers.It was satisfactory to analyze real environmental water samples with the recoveries ranging from 77.2%to 99.3%.The main advantage of the method is toxic organic solvent-free.     

新型氨基甲酸乙酯人工抗原的分析表征方法研究

采用1-(3-二甲氨基丙基)-3-乙基碳二亚胺方法合成氨基甲酸乙酯(Ethyl carbamate,EC)新型人工抗原.将衰减全反射红外光谱法(ATR-FTIR)应用于人工合成抗原的表征分析,并结合荧光光谱分析EC人工抗原的偶联效果以及载体蛋白质分子的二级结构变化;通过质谱结合紫外光谱、电泳方法进行人工抗原的系统表征,计算新型人工抗原中半抗原分子与载体蛋白质分子的偶联比.结果表明:合成路线合理,成功获得了氨基甲酸乙酯新型人工抗原.人工抗原分子的α-螺旋、β-折叠和β-转角结构与载体蛋白质分子相比含量发生变化,人工抗原的荧光相图满足线性型态变迁关系,符合“二态模型”.氨基甲酸乙酯人工抗原分析表征的红外衰减全反射方法、基质辅助激光解析飞行时间质谱法获得的检测结果与其它光谱方法、电泳方法表征结果一致,获得人工抗原的偶联比为15∶1～19∶1,EC新型人工抗原免疫小鼠抗血清的效价为1∶25600.     

Isolation and identification of nondestructive desulfurization bacterium

A nondestructive desulfurization microorganism has been isolated. The metabolism product analyses show that the strain can be a kind of biocatalyst to oxidize dibenzothiophene (DBT) into 2-hydroxydiphenyl (HBP), therefore the sulfur in DBT is removed selectively. The 16SrRNA information, cell wall analysis, physical, biochemical properties and morphological properties suggest that the isolated strain is Rhodococcus erythropolis. The strain can grow in the basal salts medium (BSM) that DBT concentration is no more than 10 mmol/L, and the optimal DBT concentration for growth is 1 mmol/L, however, the optimal DBT concentration for desulfurization is 0.5 mmol/L. The further research shows that the strain can also desulfur some other or-ganosulfur-containing compounds such as thianaphthene, phenyl sulfide and 4,6-dimethyldiben-zothiophene (4,6-DMDBT).     

聚硅氧烷热稳定性研究进展

综述了聚硅氧烷的热老化机理、影响其热稳定性的因素和提高其热稳定性的途径。聚硅氧烷的热老化反应主要包括热解聚和热氧化两个反应。氧气、水或醇、酸、碱或残留催化剂、硅油、机械外力、填料、聚硅氧烷的链端基等都会影响聚硅氧烷的热稳定性。提高聚硅氧烷热稳定性的途径主要有改变聚硅氧烷的分子结构以及在体系中添加热稳定剂。     

硫酸铁铵催化合成肉桂酸酯

利用十二水合硫酸铁铵为催化剂,使肉桂酸与醇类发生酯化反应合成了肉桂酸甲酯、肉桂酸乙酯、肉桂酸正丙酯、肉桂酸正丁酯、肉桂酸异丁酯、肉桂酸正戊酯和肉桂酸异戊酯,测定了各种酯的沸点（或熔点）折光率、元素组成和IR。     

茂金属化合物对苯乙烯丁二烯嵌段共聚物SBS催化加氢的研究

合成了一系列茂金属催化剂（C5H4R)2TiCl2[R=H(1),Me(2),C6H11(3)]和（C5H4R)2TiAr2[R=H,Ar=C6H5(4),p-MeC6H4(5),m-MeC6H4(6);R=Me,Ar=C6H5(7),p-MeC6H4(8);R=C6H11,Ar=C6H5(9),p-MeC6H4(10)],研究了这些催化剂对苯乙烯丁二烯嵌段共聚物SBS的催化加氢,考察了催化剂种类、用量及催化剂各组分之间的比例对加氢效果的影响,得到了较佳的条件,可使聚合物加氢度达到98%以上,钛催化剂用量为0.001-0.003mmol/g聚合物。