Chemical equilibrium analysis and CFD simulation of coal combustion and NOx formation

A full two-fluid model of reacting gas-particle flows with an algebraic unified second-order moment (AUSM) turbulence-chemistry model is used to simulate Beijing coal combustion and NOx formation. The sub-models are the k-epsilon-kp two-phase turbulence model, the EBU-Arrhenius volatile and CO combustion model, the six-flux radiation model, coal devolatilization model and char combustion model. The blocking effect on NOx formation is discussed. In addition, the chemical equilibrium analysis is used to predict NOx concentration at different temperature. Results of CID simulation and chemical equilibrium analysis show that, optimizing air dynamic parameters can delay the NOx formation and decrease NOx emission, but it is effective only in a restricted range. In order to decrease NOx emission near to zero, the re-burning or other chemical methods must be used.

Structure identification of a prenylflavonol glycoside from Epimedium koreanum by electrospray ionization tandem mass spectrometry

A novel prenylflavonol glycoside, named acetylicariin, has been isolated from the aerial parts of Epimedium koreanum Nakai. The structure has been identified by electrospray ionization multi-stage tandem mass spectrometry (ESI-MSn) and other chemical evidence, which has been elucidated as 8-prenylkaempferol-4'-methoxyl-3-O-alpha-L-rhamnopyranosyl-7-O-beta-D-(2''-O-acetyl)glucopyranoside.

九寨沟核心景区湖泊硅藻的组成及其密度与环境因子的关系

九寨沟自然保护区地处四川盆地北部岷山山脉南段，属川西高原气候中的暖温带。保护区内分布着118 个串珠状排列的高山湖泊，核心景区共有湖泊20 个（组），集中在海拔2000 米到3000 米之间。水资源是九寨沟的灵魂，保护水生生态系统是九寨沟生态旅游可持续发展的立足之本。本研究以九寨沟湿地生物多样性保护项目为依托，于2007 年5 月～2008 年4 月对九寨沟核心景区湖泊水体硅藻植物进行调查，分析了其密度与环境因子的相互关系，旨在为九寨沟湖泊生态系统保护提供科学依据和基础资料。主要有以下几点结论： （1）九寨沟硅藻植物丰富，调查统计为2 纲6 目10 科35 属159 种（包括变种和变型），水体硅藻中真性浮游种类较少，着生种类多，羽纹纲的脆杆藻属、舟形藻属、桥弯藻属、异极藻属、曲壳藻属的种类最多，常为优势属组成湖泊硅藻群落，只在长海是小环藻属占绝对优势。 （2）九寨沟水体中硅藻细胞密度不大，多在4×104～30×104 个/L，长海最高，五花海最低。在年变化上，不同的湖泊水体中硅藻的生长高峰季节不尽相同，在夏季、秋末和冬末春初均有可能出现高密度。在空间上，整体看来密度与海拔有一定的正相关，但由于水温不是单一主导因素，密度受多种环境因子影响，在海拔梯度上呈现一定的波浪状变化。 （3）影响九寨沟湖泊水体硅藻细胞密度较重要的环境因子是海拔、水温和pH。硅藻细胞密度年变化幅度大的湖泊水体，年平均细胞密度大。因此，环境因素不太稳定的湖泊水体，更可能出现高的硅藻细胞密度。11 月份响应于水量剧烈的减少，细齿菱形藻大量出现在五彩池成为优势种群，造成水体硅藻细胞密度的大幅增加。 （4）九寨沟湖泊水体水质几乎达到国家地表水I 类标准，但是，硅藻商指数以及代表多样性的Cairns 指数计算的结果不能反映水质的情况，这是由于水质状况不是决定九寨沟湖泊水体中硅藻生存的种类和数量的主要因素。因此在用各种指数分析水质的时候，都应该先判断计算该指数的参数是否主要由水质状况决定，然后再综合理化性质等其他指标分析和比较。 （5）人类的活动对九寨沟湖泊水生态系统有一定的影响。一方面，在低海拔景点人类活动的干扰比海拔高处相对要大，干扰引起低海拔景点湖泊硅藻Cairns指数较高；另一方面，旺季的影响比淡季大，水体中出现了典型富营养种类。因此，应加强低海拔景点和旺季的管理，并限制淡季的人类活动以保证九寨沟生态系统的自我恢复。 Jiuzhaigou nature reserve is located in north Sichuan, at the south section of Minshan Mountain, having a warm temperate climate which belongs to West Sichuan plateau climate. It includes 118 mountain lakes, and 20 of them between 2000 and 3000 altitude degree constitute the core area of Jiuzhaigou. The water is Jiuzhaigou's soul, so it is the basis of sustainable tourism development of Jiuzhaigou to protect the water ecological environment. Research depends on Jiuzhaigou wetland biodiversity protection program in this paper, invested the diatom plants in 17 lakes at the core area from May 2007 to April 2008. The composition and the correlation of diatom density and the environment were studied, which could provide scientific and basic information for the protection of the ecological environment of Jiuzhaigou. The main conclusions were: 1 The diatom species were in abundance, investigation showed that there were 159 species belong to 10 families and 35 genera. Most diatoms were benthos, euplankton were less. Genera Fragilaria, Navicula, Cymbella, Gomphonema and Achnanthes had the most species, which always were the dominant genera. Only in The Long Lake genus Cyclotella possessed a predominant status. 2 The diatom cell density was not very high, always between 4×104 cell/L and 30×104 cell/L, highest in The Long Lake and lowest in The Colorful Lake. In one year's time, diatom in different lakes had different growth type. The maximum could be in summer, late autumn and late winter early spring. The cell density showed a positive correlation to altitude in the whole, but fluctuated in details along altitude because of comprehensive influence by many environmental factors. 3 Altitude, water temperature and pH were the more important factors to determine the cell density. There was a positive correlation between the range of cell density in one year and the average cell density. So high annual cell average density probably will appear in lakes which has an unstable environmental condition. The boom of Denticula elegans in The Jade-Colored Lake in November was corresponding to the large decrease in water quantity. 4 The water quality of Jiuzhaigou was near the National Surface Water Standard rank I, but the Diatom Quotient and the Cairns Index didn't reflect the water quality accordingly. It was because the water quality wasn't the most important factor here which determined the species number and species quantity, so the index based on these items would not reflect it. Therefore, it is recommended that, when we use indices to evaluate the water quality, we should know first whether the water quality is the main determinative factor inflects the items used to compute the indices, and then combined with other chemical indices to analyze and do comparison. 5 The tourists' activities had influenced the water ecosystem of Jiuzhaigou. On the one hand, disturbance was relatively high at the lower altitude, it resulted in higher Cairns index; on the other hand, influence in high season was more severe than in low season, some typical species indicating eutrophication were observed in the water. It is suggested that the management at lower altitude and in high season must be strengthen, and less people activity in low season is necessary to fulfill the recovery of the water ecosystem.

Synthesis and Crystal Structure of a New 3D Copper B-Paradodecatungstate Compound: [Na-2(H2O)(8)][Na-8(H2O)(20)][Cu(en)(2)][W12O42] center dot 3H(2)O

A new polyoxotungstate complex [Na-2(H2O)(8)][Na-8(H2O)(20)][Cu(en)(2)][W12O42] center dot 3 H2O (1) (en = ethylenediamine) has been synthesized in aqueous solution and characterized by elemental analysis, IR spectroscopy and TG analysis, together with a single crystal X-ray diffraction study. In compound 1, the Cu(en)(2)(2+) complex cation links the [W12O42](12-) anions to form a I D chain, and the ID chains are further interconnected with Na-8(H2O)(20)(8+) and Na-2(H2O)(8)(2+) cations to construct a new 3D framework.

1,1 '-di(tert-butyl)metallocenium cations. The x-ray crystal structures of [M((C5H4Bu)-Bu-t)(2)]PF6 (M = Fe, Co) and [Co((C5H4Bu)-Bu-t)(2)](2)CoCl4

The hexafluorophosphate salts [Fe((C5H4Bu)-Bu-t)(2)]PF6 (1) and [Co((C5H4Bu)-Bu-t)(2)]PF6 (2) crystallize in isotypic structures with centrosymmetric cations which have a staggered (transoid) conformation of the exactly parallel ring Ligands (conformational angle tau = 180 degrees). The tetrachlorocobaltate salt, [CO((C5H4Bu)-Bu-t)(2)](2)CoCl4 (3), contains one almost eclipsed (tau = 140.4 degrees) and one almost staggered (tau = 101.4 degrees) cobaltocenium cation; in both cases, the cyclopentadienyl ring planes are slightly inclined (by alpha = 5.4 degrees and 4.1 degrees, respectively) to give more room to the tert-butyl substituents which are bent away from the metal in all three complexes 1 - 3.

Syntheses and reactions of heterometallic complexes of nickel and copper with tetrathiotungstates. The molecular structures of [Ph(4)P](2)[S2W(mu-S)(2)Ni(S-2)] and W(mu-S)(4)Cu-2(PPh(3))(4)center dot py

Reaction of [Ph(4)P]2WS4 With NiCl2 in methanol solution in the presence of NaOCH3 leads to the formation of [Ph(4)P](2) [S2W(mu-S)(2)Ni(S-2)] (I) A Similar reaction between (NH4)(2)WS4 and NiCl2 under O-2 atmosphere in the presence of Ph(4)PCl or (n)Bu(4)NCl affords [Ph(4)P](2)([(S-2)W(O)(mu-S)(2)]Ni-2] (IIa) and [(n)Bu(4)N](2)([(S-2)W(O)(mu-S)(2)]Ni-2} (IIb) Under argon the same reaction gives [Ph(4)P](2)[Ni(WS4)(2)] (IIIa) and [(n)Bu(4)N](2)[Ni(WS4)(2)] (IIIb). [Ph(4)P](2)[Ni(WOS3)(2)] (IV) and [Ph(4)P](2)[Ni(WO2S2)(2)] (V) can be prepared from the reaction of [Ph(4)P]2WOS3 and [Ph(4)P]2WO2S2 with NiCl2. Treatment of (NH4)(2)WS4 with CuCl in the presence of PPh(3) in boiling pyridine produces W(mu-S)(4)Cu-2(PPh(3))(3) (VI), which can further react with excess PPh(3) to give W(mu-S)(4)Cu-2(PPh(3))(4) . py (VII). Complex I crystallizes in the space group P2(1)/n with the cell parameters: a = 20.049(4), b = 17.010(4), c = 14.311(7) Angstrom; beta = 110.24(3)degrees and Z = 4; R = 0.058 for 4267 independent reflections. The structural study confirms that complex I contains two terminal sulfide ligands, two bridging sulfide ligands, a side-on disulfide ligand, and a planar central W(mu-S)(2)Ni four membered ring. Complex VII crystallizes in the space group C2/c with the cell parameters: a = 26.436(8), b = 20.542(6), c = 19.095(8) Angstrom; beta = 125.00(3)degrees and Z = 4; R = 0.080 for 3802 independent reflections. The structural study reveals a perfect linear arrangement of the three metal atoms Cu-W-Cu.

Isolation, characterization and crystal structure of natural eremophilenolide from Ligularia sagitta

A new eremophilenolide 1beta, 10beta-epoxy-6beta-acetoxy-3beta-angeloyloxy-8beta-hydrox y-eremophil-7(11)-en-8, 12alpha-olide (1), together with liguhodgsonal (2), esculetin (3) and beta-sitosterol (4), was isolated from the aerial parts of Ligularia sagitta. The structure of the new constituent (1) was elucidated by spectroscopic methods and confirmed by single-crystal X-ray diffraction.