Synthesis of 7H-tetrazolo[1,5-c]pyrrolo[3,2-e]pyrimidines and their reductive ring cleavage to 4-aminopyrrolo[2,3-d]pyrimidines

Some new 7,9-disubstituted 7H-1,2,3,4-tetrazolo[1,5-c]pyrrolo[3,2-e]pyrimidines 5 have been synthesized either by diazotization of 4-hydrazino-5,7-disubstituted-7H-pyrrolo[2,3-d]pyrimidines 4 obtained by hydrazinolysis of 4-chloro-5,7-disubstituted-7H-pyrrolo[2,3-d]pyrimidines 3 or via a substitution reaction between 3 and sodium azide. 5,7-Disubstituted-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-ones 2 were obtained by cyclocondensation of 2-amino-3-cyano-1,4-disubstituted pyrroles 1 with formic acid which on chlorination using phosphorus oxychloride afforded 3 . A novel route for the synthesis of 4-amino-5,7-disubstituted-7H-pyrrolo[2,3-d]pyrimidines 6 by the reductive ring cleavage of 5 has been reported.     

Towards the synthesis of perfluoroalkylated derivatives of Xantphos

An analogue of Xantphos incorporating four perfluoroalkyl groups has been prepared and successfully used as a ligand in the rhodium-catalysed hydroformylation of 1-octene in toluene. A number of perfluoroalkylated xanthene backbones have also been synthesised, but their conversion into preferentially perfluorocarbon solvent soluble Xantphos-type ligands, suitable for catalysis in fluorocarbon solvents, has not been successful.     

Products of similar matrices

Let and be matrices of determinant over a field , with or . We show that if is not a scalar matrix, then is a product of matrices similar to . Analogously, we conjecture that if and are elements of a semisimple algebraic group over a field of characteristic zero, and if there is no normal subgroup of containing but not , then is a product of conjugates of . The conjecture is verified for orthogonal groups and symplectic groups, and for all semisimple groups over local fields. Thus, in a connected, semisimple Lie group with finite center, the only conjugation-invariant subsemigroups are the normal subgroups.

     

Detection and assessment of co‐association in inhalable drug particles using aerosol time‐of‐flight mass spectrometry

Aerosol Time‐of‐Flight Mass Spectrometry (AToFMS) was used to examine co‐association between two inhaled drugs, fluticasone propionate (FP) and salmeterol xinofoate (SX), in fine aerosolised particles emitted from Seretide®/Advair® inhaled combination products. Principal Component Analysis (PCA) was used to identify fragmentation patterns indicative of either pure or co‐associated particles (particles containing both drugs). A third component of the particles emitted from dry powder inhalers (DPIs), lactose, gave only a very weak mass spectral signal and no interpretable data was acquired for this compound; however, it was not found to interfere with the detection of the two drug substances. High levels of co‐association were found in the emitted doses from both pressurised metered dose inhaler (pMDI) and dry powder inhaler (DPI) products. Copyright © 2008 John Wiley & Sons, Ltd.     

Hyperfine structure induced isotopic effects in krypton resonance ionization mass spectrometry

A time-of-flight mass spectrometer combined with a pulsed laser system has been used for determination of krypton isotope ratios of air samples containing 10⁶-10⁷ krypton atoms. A three-color, doubly resonant ionization scheme employing a 116.48 nm transition from the ground into the first 4s²4p⁵(²P°_1/2)5s J = 1 excitation level has been applied. The magnitude of a hyperfine splitting of this level has been estimated for ⁸¹Kr, ⁸³Kr and ⁸⁵Kr isotopes. Hyperfine structure induced isotopic effects have been investigated under different saturation conditions and found to be negligible when the first and the second transitions are strongly saturated.     

4‐Chloro‐N‐(4‐cyano‐2‐nitro­phenyl)‐3‐nitro­benz­amide

The structure of the title compound, C₁₄H₇ClN₄O₅, comprises two nearly coplanar phenyl rings connected via an amido moiety.     

An X-ray absorption spectroscopy study of the local environment of iron in degradable iron–phosphate glasses

Degradable iron–phosphate glasses with the composition of (CaO)_0.30–(Na₂O)_0.20?x–(Fe₂O₃)_x–(P₂O₅)_0.50, x = 0.01–0.05, were studied by Fe K-edge X-ray absorption spectroscopy (both near-edge, XANES, and extended, EXAFS). The addition of up to 5 mol% iron oxide is known to enhance the durability of the phosphate glass while maintaining biocompatibility. The results from the two techniques used here both show that iron is in the Fe(III) oxidation state and has octahedral coordination. This suggests that Fe is cross-linking the phosphate chains and therefore strengthening the network structure, resulting improved chemical durability of the glasses.     

电容式感测技术在饮水机设计中的应用

电容式感测技术为研发业者提供一个与使用者互动的全新方式,这种方法解决许多传统问题,包括机械式按压杆或使用电磁阀控制值的按钮开关.在饮水机内部设计中采用电容式感测技术.不仅展现出电容式感测技术所带来的强大可靠性,并显示出由控制器所操控的电容式感测技术还可支持传统功能,为顾客提供更多的价值,并降低平时维修的费用.     

DSP内核-VLIW与SIMD珠联璧合

DSP在手机、音乐播放器和其他消费品中的应用,直接关系着系统的功能与价格.在适当的价位上,DSP必需提供足够的功能满足当前需求,并且有充裕的可扩展性和空间,以便设计人员对硬件无需大动干戈,便能为系统添加新功能或强化现有功能.     

Compact Clifford–Klein Forms of Homogeneous Spaces of SO(2, n)

A homogeneous space G/H is said to have a compact Clifford–Klein form if there exists a discrete subgroup of G that acts properly discontinuously on G/H, such that the quotient space \G/H is compact. When n is even, we find every closed, connected subgroup H of G = SO(2, n), such that G/H has a compact Clifford–Klein form, but our classification is not quite complete when n is odd. The work reveals new examples of homogeneous spaces of SO(2, n) that have compact Clifford–Klein forms, if n is even. Furthermore, we show that if H is a closed, connected subgroup of G = SL(3, R), and neither H nor G/H is compact, then G/H does not have a compact Clifford–Klein form, and we also study noncompact Clifford–Klein forms of finite volume.