氧化条件下NOx催化的甲烷均相部分氧化

考察了没有固体催化剂时NOx对甲烷气相氧化的促进作用.实验结果表明，即使在强氧化条件下（O2/CH4=5），NOx对甲烷部分氧化制一氧化碳仍然有明显的催化活性.在CH4-O2体系中加入0.005％～0.2％的NO后，反应温度可降低200-300 ℃.在反应产物中还可观察到甲醛和乙烯，通过改变反应条件可以控制它们的相对浓度.     

Crystal and Molecular Structure of (BzlMe3N) 2 + [Fe2OCl6]2-

The crystal and molecular structure of (BzlMe₃N) ₂ ⁺ [Fe₂OCl₆]^2- has been determined. The asymmetric unit contains two benzyltrimethylammonium cations and two half x872/xxlarge956.gif" alt="mgr" align="MIDDLE" BORDER="0">-oxo-bis(trichloro-iron(III)) anions. The bridging x872/xxlarge956.gif" alt="mgr" align="MIDDLE" BORDER="0">-oxygen atoms of these anions are located over crystallographic symmetry elements. Therefore, the two anions resulting from the symmetry operations correspond to two different conformers presenting x872/xxlarge8220.gif" alt="ldquo" align="MIDDLE" BORDER="0">angularx872/xxlarge8221.gif" alt="rdquo" align="MIDDLE" BORDER="0"> and x872/xxlarge8220.gif" alt="ldquo" align="MIDDLE" BORDER="0">linearx872/xxlarge8221.gif" alt="rdquo" align="MIDDLE" BORDER="0"> dispositions of the Fe-O-Fe bond angle. Mössbauer spectrum consists of two asymmetric lines that are adequately simulated by two equally populated quadrupole doublets associated with the two iron sites.     

2-Methylthio-4,5,6,7-tetrahydro-1,2,4-triazolo[1,5-<Emphasis Type="Italic">a</Emphasis>]pyrimidin-5- and -7-Ones

The cyclocondensation of methylcinnamates and arylidene derivatives of Meldrumx/xxlarge8217.gif" alt="rsquo" align="BASELINE" BORDER="0">s acid with 3-amino-5-methylthio-1,2,4-triazole in DMF gives 2-methylthio-4,5,6,7-tetrahydro-1,2,4-triazolo[1,5-a]-pyrimidin-5-ones. The reaction involving arylidene derivatives of Meldrumx/xxlarge8217.gif" alt="rsquo" align="BASELINE" BORDER="0">s acid or its synthetic equivalents in ethyl acetate with a catalytic amount of pyridine gives a mixture of 2-methylthio-4,5,6,7-tetrahydro-1,2,4-triazolo[1,5-a]pyrimidin-5- and -7-ones.__________Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 246&#x2013;251, February, 2005.     

Synthesis and crystal structure ofN,N′-DicyclohexylpiperazineN,N′-dioxide octahydrate

N,Nx310465151263k86/xxlarge8242.gif" alt="prime" align="BASELINE" BORDER="0">-DicyclohexylpiperazineN,Nx310465151263k86/xxlarge8242.gif" alt="prime" align="BASELINE" BORDER="0">-dioxide octahydrate, C₁₆H₄₆N₂O₁₀,M _r=426.55, monoclinic, space groupC2/m (No. 12),a=12.961(4),b=11.533(4),c=7.907(1) Å, x310465151263k86/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">=98.37(2)^o,V=1169.3(6) ų,Z=2. The structure was solved by the direct method and refined toR=0.045 for 1192 observed MoK _{x310465151263k86/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">} reflections. TheN,Nx310465151263k86/xxlarge8242.gif" alt="prime" align="BASELINE" BORDER="0">-dioxide molecule occupies a site of symmetry 2/m. The piperazine ring takes the chair form with the two N&#x2013;O bonds oriented axially in atrans configuration. Hydrogen bonding between the water molecules, as well as between theN-oxide groups and water molecules, gives rise to a puckered layer composed of edge-sharing four-membered, five-membered, six-membered, and eight-membered rings. Adjacent layers are cross-linked by theN,Nx310465151263k86/xxlarge8242.gif" alt="prime" align="BASELINE" BORDER="0">-dicyclohexylpiperazine moieties lying between them, thereby generating a x310465151263k86/xxlarge8216.gif" alt="lsquo" align="BASELINE" BORDER="0">sandwichx310465151263k86/xxlarge8217.gif" alt="rsquo" align="BASELINE" BORDER="0"> structure consolidated by covalent and hydrogen bonding. Supplementary Data relating to this article are deposited with the British Library as Supplementary Publication No. SUP 82062 (8 pages).     

Synthesis of 4,4′-bis(4-aminophenoxy)benzophenone and polyimides based on this compound

Synthesis of 4,4x432/xxlarge8242.gif" alt="prime" align="BASELINE" BORDER="0">-bis(4-aminophenoxy)benzophenone was performed starting from chloral. Various polyimides were obtained by reactions of 4,4 x432/xxlarge8242.gif" alt="prime" align="BASELINE" BORDER="0">-bis(4-aminophenoxy)benzophenone with aromatic tetracarboxylic acid dianhydrides. Some of the polyimides obtained are crystalline compounds.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 673&#x2013;676, March, 1996.     

Repleteness and regular lattice measures

Let X be an abstract set and L a lattice of subsets of X. To each lattice regular measure µ, we associate two induced measures x0531p5/10998_2005_Article_BF02280662_TeX2GIFIE1.gif" alt="&#xa;$$\hat \mu $$&#xa;" align="middle" border="0"> and x0531p5/10998_2005_Article_BF02280662_TeX2GIFIE2.gif" alt="&#xa;$$\tilde \mu $$&#xa;" align="middle" border="0"> on suitable lattices of the Wallman space IR(L) and another measure µx0531p5/xxlarge8242.gif" alt="prime" align="BASELINE" BORDER="0"> on the spaceIR^{x0531p5/xxlarge963.gif" alt="sgr" align="BASELINE" BORDER="0">}(L). We will investigate the reflection of smoothness properties of p onto x0531p5/10998_2005_Article_BF02280662_TeX2GIFIE3.gif" alt="&#xa;$$\hat \mu $$&#xa;" align="middle" border="0"> , x0531p5/10998_2005_Article_BF02280662_TeX2GIFIE4.gif" alt="&#xa;$$\tilde \mu $$&#xa;" align="middle" border="0"> and µx0531p5/xxlarge8242.gif" alt="prime" align="BASELINE" BORDER="0">; and try to set some new criterion for repleteness and measure repleteness.     

Fluctuation-dominated kinetics in the a+b→0 reaction between immobile particles

We consider the accumulation of immobile particles landing on a one-dimensional lattice and annihilating via the A + B x3q162k078707313/xxlarge8594.gif" alt="rarr" align="BASELINE" BORDER="0"> 0 bimolecular reaction. Here we focus on short-range interactions with cutoff. We investigate through computer simulations both the kinetics of the particles' accumulation and also their spatial distribution. The relation between the exponents describing the growth of the particles' concentration and the correlation length of their distribution shows that the kinetics of accumulation is fluctuation-dominated.This work is dedicated to Prof. George H. Weiss.     

A mini transmissionγ-ray Compton polarimeter and measurements of the sign of magnetic moments of radioactive nuclei

A mini transmissionxxlarge947.gif" alt="gamma" align="MIDDLE" border="0">-ray Compton polarimeter was developed for the measurement of the sign of magnetic moments of radioactive nuclei with low-temperature nuclear orientation. The signs of the magnetic moments of the following isotopes were determined:¹⁹³Os [xxlarge956.gif" alt="mgr" align="MIDDLE" border="0">=+0.7297(16)xxlarge956.gif" alt="mgr" align="MIDDLE" border="0"> _N];^191m Ir [xxlarge956.gif" alt="mgr" align="MIDDLE" border="0">=+6.20(9)xxlarge956.gif" alt="mgr" align="MIDDLE" border="0"> _N];¹⁹²Ir [xxlarge956.gif" alt="mgr" align="MIDDLE" border="0">=+1.924(10)xxlarge956.gif" alt="mgr" align="MIDDLE" border="0"> _N];¹⁹⁴Ir [xxlarge956.gif" alt="mgr" align="MIDDLE" border="0">=+0.39(1)xxlarge956.gif" alt="mgr" align="MIDDLE" border="0"> _N];^195m Pt [xxlarge956.gif" alt="mgr" align="MIDDLE" border="0">=&#x2013;0.605(15)xxlarge956.gif" alt="mgr" align="MIDDLE" border="0"> _N].Dedicated to Prof. Dr. P. Kienle on the occasion of his 60th birthday     

Microstructural and physicochemical study of the buried Fe/AlGaAs(100) interface by transmission electron microscopy and x‐ray emission spectroscopy

Among the magnetic metal/semiconductor contacts, the Fe/GaAs system has been widely studied owing to its potential applications in electronic devices. In contrast, there are not many studies concerning the Fe/Al_xGa_1?xAs contact, and in particular there are no reports concerning the changes induced in the interfacial zone by the presence of Al. In this work, thin polycrystalline iron films were deposited by ion beam sputtering at room temperature on a 300 nm thick Al_0.25Ga_0.75As layer grown by molecular beam epitaxy onto GaAs(001). X‐ray diffraction analysis showed that the iron films are polycrystalline, and indications of a (002) texture of the film were observed. The fine scale analysis of the interface was achieved by high‐resolution transmission electron microscopy (HRTEM) observations, the results of which are compared with the physicochemical information obtained from electron‐induced x‐ray emission spectroscopy, by analysing the Al 3p valence states at the Fe/Al_xGa_1?xAs interface. The HRTEM experiments on cross‐section samples indicate that the interfacial zone between iron and AlGaAs is limited to <1.5 nm in thickness. X‐ray emission spectroscopy showed the presence of Al atoms in an FeAl‐like environment at the interface, and the existence of wrong bonds and point defects. The estimated width of the perturbed interface (2.0 ± 0.5 nm) is in agreement with the HRTEM results. Copyright © 2003 John Wiley & Sons, Ltd.     

Electronic Structures, (d-p)π Conjugation Effects, and Spectroscopic Properties of Polyoxometalates: M6O19 2− (M=Cr, Mo, W)

The electronic structures and bonding of isopoly oxometalates M₆O₁₉ ^2&#x2013; (M=Cr, Mo, W) have been investigated by using ab initio and relativistic density functional methods. We have discussed the role of the central oxygen atom and the (d-p)x49ywqtk/xxlarge960.gif" alt="pgr" align="BASELINE" BORDER="0"> conjugation interactions between the metal and bridging oxygen atoms. It is found that there exist 12 three-centered two-electron (d-p-d)x49ywqtk/xxlarge960.gif" alt="pgr" align="BASELINE" BORDER="0"> bonds for the three M₄(x49ywqtk/xxlarge956.gif" alt="mgr" align="MIDDLE" BORDER="0">-O)₄ planar rings in M₆O₁₉ ^2&#x2013; ions and these hexametalates are considered to have quasi-aromaticity. The (d-p)x49ywqtk/xxlarge960.gif" alt="pgr" align="BASELINE" BORDER="0"> conjugation effects play essential role in stabilizing these cluster compounds, and the reduced (d-p)x49ywqtk/xxlarge960.gif" alt="pgr" align="BASELINE" BORDER="0"> conjugation effects account for the instability of the isopoly oxochromate ion, Cr₆O₁₉ ^2&#x2013;. The vibrational spectra and electronic spectra of M₆O₁₉ ^2&#x2013; ions are evaluated and assigned theoretically and the calculated spectra are in fairly good agreement with the measured experimental results.