两种TVD格式在跨音透平叶栅流场计算中的应用

两种ＴＶＤ格式在跨音透平叶栅流场计算中的应用黄伟光，刘建军（中国科学院工程热物理研究所北京１０００８０）关键词跨音速透平，Ｅｕｌｅｒ方程，ＴＶＤ格式１引言现代高负荷透平大都工作在跨音范围，研究发展能准确预测跨音速透平叶栅内部流场的激波位置与强度以及叶...     

具有超高阳离子染料去除能力的磺酸功能化球形共价有机框架

通过三醛基间苯三酚(TFP)与2,2′-联苯胺二磺酸(BDSA)的席夫碱反应, 合成了β-酮烯胺连接的磺酸功能化球形共价有机框架(TFP-BDSA COF). 所得阴离子型TFP-BDSA可迅速吸附如亚甲基蓝(MLB)、 结晶紫(CV)和罗丹明B(RhB)等阳离子染料, 而对如甲基橙(MO)和荧光素钠(FS)等阴离子染料则难以吸附, 该COF可实现基于电荷模式的阴离子、 阳离子染料的分离. TFP-BDSA对阳离子染料的吸附动力学均遵循拟二级吸附动力学模型, 吸附过程符合Langmuir吸附模型, 其对MLB, CV和RhB的最大吸附容量分别高达1116, 1429和1638 mg/g. 与其它COFs材料相比, TFP-BDSA对CV和RhB的吸附容量最高. 该工作可为开发功能COFs材料实现对废水中有机污染物的快速吸附和有效去除提供参考.     

Method development of combining pressurized liquid extraction and off-line HPLC fractionation with a porous graphite carbon column for the analysis of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in environmental samples

A method was developed for analysis of PCDD/Fs in fly ash and soil samples by using the combination of pressurized liquid extraction (PLE) and off-line HPLC fractionation with a porous graphite carbon (PGC) column, followed by analysis using HRGC/HRMS. The samples were automatically extracted by PLE. A multi-layer silica column was used for the preliminary cleanup. Then off-line fractionation was applied for the separation of PCDD/Fs and the collected PCDD/Fs fraction was analyzed by HRGC/HRMS. The use of solvent back-flushing at 70°C successfully solved the carry-over problem of PGC column. The procedure of single extraction and cleanup provided advantages of high automation and significant reduction of solvent and time compared to conventional methods. The method was validated by certified materials of fly ash and industrial sandy soil, and applied for the analysis of fly ash samples collected from three two-ton medical waste incinerators in Beijing and one farm soil sample collected in the vicinity of the incinerators.     

环糊精衍生物涂渍毛细管柱的制备及分离性能

以3种环糊精衍生物分别涂覆在毛细管内壁制得气相色谱毛细管柱,以正十二烷为溶质,测得理论塔板数均在2800/m以上,柱效较高。研究了它们对一系列苯系物位置异构体的分离性能,探讨了硝基氯苯、硝基苯胺和苯二胺等化合物在不同柱上的拆分机理。底物分子和固定相之间的弱相互作用(如氢键、偶极相互作用和π-π堆积作用)等直接影响毛细管柱对底物的分离性能。对于苯二胺的位置异构体,在全对氯苯异氰酸酯化β-CD涂覆的毛细管柱(ACD)上的分离因子为1.88,在多叠氮β-CD衍生物涂覆的毛细管柱(NMCD)上的分离因子为1.41,但在单叠氮β-CD衍生物涂覆的毛细管柱(NSCD)上无法分开;对于硝基氯苯,在NMCD柱和ACD柱上的分离因子相近(前者为1.13/1.11;后者为1.08/1.15),在NSCD柱上则无分离趋势;对于硝基苯胺,在NMCD柱上无分离趋势。同时,苯环上不同取代基间电子效应则影响了异构体在气相色谱中出峰顺序。     

Geometric stability and adsorption property of hydroxyl group on graphene sheets

The stable geometrics and adsorption behaviors of hydroxyl (OH) groups on graphene sheets are investigated using the first-principles calculations. The single hydroxyl adatom has small adsorption energy and diffusion barrier on pristine graphene. The binding strength of the hydroxyl group increases with the coverage, and the aggregations of the hydroxyl groups reduce the structural bucking of graphene sheet. On the graphene with single vacancy (SV-graphene), the large trapping zones mean the adsorbed OH would be easily trapped at the vacancy site. The hydroxyl groups prefer to aggregate on graphene surfaces and form the water molecule, leaving the epoxy group on pristine graphene or oxygen dopant in SV-graphene, which is used to constitute the structural model of oxidized graphene. These results would provide us a useful reference to understand the atomic structure and adsorption property of functional groups on graphene sheets.     

The formation of H2S on metal-modified graphene under hydrogen environments

The adsorption behaviors of H₂S, SH, and S on Co-embedded graphene surface (Co-graphene) are investigated using the first-principles calculations. It is found that the adsorbed SH and S species on Co-graphene are strongly stabilized than that of the H₂S molecule. Besides, the chemisorbed SH and S can lead to dramatic changes in the electronic structure and magnetic property of Co-graphene system by the transferred electrons, and the electronic transport behavior of Co-graphene exhibits high sensitivity for detecting SH and S. Moreover, the deposited S-based species would be converted into H₂S molecule by the hydrogenation reaction. Compared to the hydrogen molecule, the presence of hydrogen atoms can more easily inhibit the formation of sulfur deposition on Co-graphene surface, which provides valuable guidance on designing graphene-based catalysis as electrode in fuel cells.     

3D Tungsten Trioxide Nanosheets as Optoelectronic Materials for On-chip Quantification of Global Antioxidant Capacity

The photoelectrochemical properties of semiconductors mainly depend on the size and shape of the corresponding nanoparticles. Herein, 3D WO₃ nanosheets were controllably synthesized with the aid of polyethyleneimine, which presents enhanced photocurrent responses. Based on this excellent photoelectrochemical property, a photoelectrochemical chip was prepared by lithography technology for the smart monitoring of the antioxidant capacity(AC) in red wine and exhibits a series of advantages inclu-ding rapid response time, high sensitivity, and long-lasting stability. The mechanism of the present photoelectrochemical sensing was explored and shows a single electron transfer reaction. Furthermore, only 200 μL of samples are required for one testing, which demonstrates that the present photoelectrochemical chip can be potentially integrated with a portable commercial device(such as a mobile phone) for further research and development of food and drug supervision.     

An Anomalous Electron Configuration Among 3d Transition Metal Atoms

Physical properties of materials are mainly determined by valence electron configurations, where different valence shells would induce divergent phenomena. In compounds containing Sc²⁺, 3d electron occupancy is expected, the same as other transition metal atoms like Ti³⁺. But this situation still awaits experimental verification in inorganic materials. Here, we selected ScS to measure the valence electron density and orbital population of Sc²⁺ through delicate quantitative convergent-beam electron diffraction. With the absence of 3d orbital features around Sc-atom sites and the nearly bare population of t_2g orbital, the unintuitive occupation of 4s orbital in Sc²⁺ is concluded. It should be the first time to report such a special electron configuration in a transition metal compound, in which 4s rather than 3d orbital is preferred. Our findings reveal the distinct behavior of Sc and probable ways to modulate material properties by controlling electron orbitals.     

Dendrimer与表面活性剂相互作用的研究进展

聚酰胺-胺(PAMAM)是目前最具应用前景的树枝状大分子(Dendrimer),它与表面活性剂相互作用后能够形成聚集体,这种聚集体能有效地改变体系的微观环境和物理化学性质。本文综述了小分子表面活性剂与Dendrimer相互作用研究方面所取得的进展,重点讨论了阴离子表面活性剂和阳离子表面活性剂与Dendrimer混合体系中溶液的疏水环境、浊度以及形成聚集体中值粒径等物理化学性质的变化,在此基础上,讨论了Dendrimer与小分子表面活性剂相互作用在机理方面所取得的研究进展,为进一步扩大Dendrimer的应用领域提供参考。