甲烷—空气燃烧中NOx生成的简化模型研究

用特征值－特征向量法对甲烷－空气燃烧时ＮＯＸ生成的化学反应机理进行了简化，得到了仅由１５个基元以应组成的简化反应模型。对比计算结果表明，该模型能在较宽燃空比内与全面模型很好吻合，因而可望用于燃烧过程数值模拟时对ＮＯＸ生成的预测     

XPS,AFM, ATR and TPD evidence for terraced,dihydrogen terminated, 1×1 (100) silicon

Heating (100) silicon at high temperature (say, higher than 850 °C) in H₂, cooling to 670–700 °C in the same ambient, and quenching to room temperature in N₂ results in environmentally robust, terraced 1 × 1 (100) SiH₂. Evidence for this conclusion is based on angle‐resolved x‐ray photoelectron spectroscopy, atomic force microscopy, infrared absorption spectroscopy in the attenuated total reflection mode, thermal programmed desorption, and reflection high‐energy electron diffraction. Copyright © 2005 John Wiley & Sons, Ltd.     

Summary of ISO/TC 201 standard: XXI. ISO 21270:2004—Surface chemical analysis—X‐ray photoelectron and Auger electron spectrometers—Linearity of intensity scale

This International Standard specifies two methods for determining the maximum count rate for an acceptable limit of divergence from linearity of the intensity scale of Auger and x‐ray photoelectron spectrometers. It also includes methods to correct for intensity non‐linearities so that a higher maximum count rate can be employed for those spectrometers for which the relevant correction equations have been shown to be valid. Copyright © 2004 John Wiley & Sons, Ltd.     

Investigation of gas chromatographic interaction mechanism on permethylated cyclodextrins by molecular modelling

Summary The capillary gas chromatographic retention behavior of -pinene and tricyclene has been investigated on stationary phases of different polarities. On all but one of the columns employed, tricyclene eluted before -pinene; only permethylated -cyclodextrins dissolved in moderately polar polisiloxanes gave a reversed elution order. The intermolecular interactions which caused the unexpected retention behavior were investigated in detail, applying methods of computer simulation. To achieve this, we have developed a calculation algorithm on the basis of molecular mechanical optimizations and programmed it in a macro. This makes it possible to systematically investigate a given configuration space in which all the possible interactions can take place. It was shown that permethylated -cyclodextrin as host molecule for both guest molecules offers an optimum cavity size. As a result the number of energetically favorable contacts between host and guest molecules as well as the strength of the interactions in this stationary phase were larger. As a consequence the elution order, normally only influenced by the vapor pressure of the compounds at a given temperature, was changed. Nonspecific interactions played an especially important role for these kinds of substances.     

Solubility enhancement of triflumizole by host-guest interaction with β-cyclodextrin

Summary The solubility enhancement of triflumizole, a systemic fungicide, by -cyclodextrin inclusion complexation was investigated by electron absorption spectroscopy. The respective association constant determined by different methods was estimated to 470±20M ^–1 in aqueous solution. A model for the host-guest complexation was deduced by molecular calculations.

---

Löslichkeitsverbesserung von Triflumizole durchHost-Guest-Complexierung mit -Cyclodextrin

Zusammenfassung Die Löslichkeitsverbesserung des systemischen Fungizids Triflumizole durch Komplexierung mit -Cyclodextrin wurde mittels Elektronenabsorptionsspektroskopie untersucht. Die entsprechende Stabilitätskonstante wurde durch verschiedene Methoden erfaßt und betrug im wäßrigen Medium 470±20M ^–1. Ein Model für denHost-Guest-Complex wurde durch Molekülrechnungen erstellt.

     

Asymmetric michael addition of aromatic thiols to 2-cyclohexenone and maleic acid esters via formation of crystalline cyclodextrin complexes

The asymmetric Michael addition of aromatic thiols to 2-cyclohexenone and maleic acid esters has been carried out by utilizing their crystalline cyclodextrin complexes suspended in water. The best chiral induction, 30% enantiomeric excess (ee), was achieved in combinations of 2-cyclohexenone and octyl maleate with the crystalline -cyclodextrin complex of benzenethiol (method A) to afford (S)-3-phenylthiocyclohexanone and (S)-octyl-2-phenylthiosuccinate, respectively, whereas the reaction of benzenethiol with 2-cyclohexenone included in -cyclodextrin (method B) inversely induced the chiral recognition to give the (R)-adduct with 4–9% ee.     

Vibrational spectra and structure of “staircase” carbonyl π-complexes of transition metals

FTIR spectra have been studied for staircase cyclopentadienyl complexes containing two or three metal carbonyl fragments bound by the metal-carbon bond Cp(CO)₂Fe-CpmMn(CO)₃ (1), Cp(CO)₂Fe-CpmFe(CO)₂CH₂Ph (2), Cp(CO)₂Fe-Cpm(CO)₂Fe-CpmMn(CO)₃ (3), Cp(CO)₂Mo-Cpm(CO)₂Fe-CpmMn(CO)₃ (4), Cp(CO)₃W-Cpm(CO)₂Fe-CpmMn(CO)₃ (5), Cp(CO)₂Fe-Cpm(CO)₂Fe-BmCr(CO)₃ (6), Cr(CO)₃Bm-CpmFe(CO)₂CH₂Ph (7), where Cp = ₅-C₅H₅, Cpm = ¹⁵-C₅H₄, Bm = ¹⁶-C₆H₅. Temperature-dependent FTIR spectra were measured inn-pentane solutions over a wide temperature range and in the low-temperature solid matrices of argon and nitrogen. Rotamers, formed due to rotation about the metal-carbon -bond, were found in solutions and matrices. A molecular mechanics calculation of1 proved the possibility of such rotation.Translated fromIzyestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1952–1956, November, 1994.The authors are grateful to the Russian Foundation for Basic Research (project code No 93-03-18592) and to the International Science Foundation (project code No MEQ000).     

Phase separation of poly(γ-benzyl L-glutamate) to liquid crystal and isotropic solution in various helicogenic solvents

Solvent effects on the phase separation of poly(-benzyl L-glutamate) to liquid crystal and isotropic solution have been observed in various helicogenic solvents. The temperature-composition phase diagrams have been determined for each solution. The critical concentrations, ₂ ^* , at which the phase separation occours have been compared in various solvents. In dimethylformamide in which the polymer is molecularly dispersed, the observed ₂ ^* value has agreed with that calculated by Flory's theory. In some solvents in which the polymer aggregates in a head-to-tail mode such as chloroform, the observed ₂ ^* values have been considerably small. It is assumed that the polymer aggregates behave as longer particles than the original particles. In dioxane in which the polymer aggregates highly both in a head-to-tail and a side-by-side modes, the ₂ ^* value has been a little larger than that in chloroform. In this case the relationship between the aggregation and the liquid crystal formation is so complicated that further investigation is necessary. In aromatic solvents such asm-cresol that dissolves the polymer almost molecularly, the ₂ ^* is smaller than that in dimethylformamide. Therefore, the intermolecular interactions between the phenyl groups in the side groups of the polymer and those in solvent molecules must be considered.The author is grateful to Mr. K. Sano and Mr. M. Watanabe for their observation of the liquid crystal formation.     

Lamiaceae carbohydrates. 1. Pectinic substances and hemicelluloses from <Emphasis Type="Italic">Mentha x piperita</Emphasis>

Pectinic substances from the aerial part of Mentha x piperita were isolated and characterized and found to be a mixture of β-(1→4)-glucogalactan (MPG) and two α-(1→4)-rhamnopolygalacturonans (MPP′-1 and MPP′-2). It was shown that the pectin and its components exhibited membrane-stabilizing, antiatherogenic, and antioxidant activity. Hemicelluloses from M. piperita were a lignocarbohydrate complex. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 411–416, September–October, 2007.