Conditions for the suppression of spatial harmonics at a two-frequency acoustooptic interaction in the Raman-Nath mode

It is demonstrated that the diffraction of a plane light wave by an acoustic wave of fundamental frequency in the Raman-Nath mode with admixture of the second acoustic harmonic may be accompanied by a considerable change in the higher diffraction orders with numbers ±2, ±3, etc. Conditions for the selective suppression of the orders are obtained in the weak and strong interaction modes. Results of a numerical simulation are presented.     

Effect of the Nature of Coke-Forming Species on the Crystallographic Characteristics and Catalytic Properties of Metal–Filamentous Carbon Catalysts in the Selective Hydrogenation of 1,3-Butadiene

The particle morphology and surface structure of nickel metal in metal–filamentous carbon catalysts were found to depend on the nature of coke-forming species used in the synthesis of catalysts. Metal carbonization with hydrocarbons that are characterized by high thermodynamic stability results in the formation of well-cut metal particles the surface of which is formed by (110) facets. Selective hydrogenation reactions of diene and acetylene hydrocarbons to olefins are typical of these catalysts. In the catalytic decomposition of hydrocarbons with relatively low thermodynamic stability, metal particles become irregular in shape, and their surface is formed by (111) facets. In this case, the reactions of full hydrogenation of olefin, diene, and acetylene hydrocarbons to corresponding alkanes take place. These data are consistent with the found dependence of the catalytic properties of catalysts on the character of the exterior faceting of active metal particles.     

Research on naphthyridines. 10. Synthesis and ionization constants of 10-alkylaminobenzo[b]-1,8-naphthyridines

10-Alkylaminobenzo[b]-1,8-naphthyridines were synthesized by cyclization of 2-arylaminonicotinic acid alkylamides by means of phosphorus oxychloride. The pK_al values of the 10-alkylaminobenzo[b]-1,8-naphthyridines, which range from 8.74 to 8.50, were determined by potentiometric titration in anhydrous ethanol.See [1] for communication 9.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 799–801, June, 1979.     

Kinetics of photoreduction of 9,10-phenanthrenequinone in the presence of amines and polymethylbenzenes

A study of the kinetics of photoreduction of 9,10-phenanthrenequinone in the presence of hydrogen donors (para-substituted N,N-dimethylanilines and polymethylbenzenes) showed that plots of the quantum yield of photoreduction (_H) and apparent reaction rate constant (k _H) vs. oxidation potential of hydrogen donors are extreme. In the presence of amines, k _H and _H increase, as a whole, whereas they decrease in the presence of polymethylbenzenes. In coordinates _H-G _e (G _e is the change in the free energy of electron transfer) for pairs quinone-H donor, _H increases with G _e approaching to zero. For the amine series, this effect is mainly in the exothermic region of G _e (G _e < 0). For the series of polymethylbenzenes, this increase is observed in the endothermic region (G _e > 0).__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2381–2385, November, 2004.     

Study of the mechanism of base induced dehydrobromination of trans-β-bromostyrene

Observation that rates of dehydrobromination of trans-β-bromostyrene (1) and the Hofmann degradation of tetrabutyl ammonium cation depend on strength of base in different ways and that treatment of 1 with base results in fast abstraction of the β-proton imply the possibility that the dehydrobromination of 1 could proceed via α-elimination and Ph migration. In order to clarify this question, β-¹³C-labeled 1 was obtained and subjected to PTC dehydrobromination which proceeds without migration of Ph. The obtained results are consistent with an irreversible E1cB mechanism.     

Photoreduction of o-benzoquinones in the presence of p-bromo-N,N-dimethylaniline

Photoreduction of o-benzoquinones in the presence of p-bromo-N,N-dimethylaniline under irradiation ( > 500 nm) affords the corresponding pyrocatechols and hydroxyphenyl ethers. The latter are unstable and, in turn, decompose in the dark reaction to pyrocatechols. The ratio between pyrocatechol and hydroxyphenyl ether formed upon the photoreaction is determined by the structure of o-quinone, namely, the presence and bulk of substituents in positions 3 and 6 of the ring. The yield of pyrocatechol is maximal (60—65%) if the substituents are the same (H and H, Bu^t and Bu^t) or insignificantly differ (Prⁱ and Bu^t), regardless of its bulk.     

基于联合变换相关器的像移测量仿真分析

对基于联合变换相关器的像移测量数学原理进行了说明,介绍了面阵CCD的安装位置以及输入图像的获取方法,分析了低信噪比输入图像、相对转动位移对测量精度的影响。应用MATLAB对输入图像进行傅里叶变换得到联合功率谱,对二值化处理的功率谱进行傅里叶变换得到相关输出,用质量中心算法计算出像移量。分析得出,输入图像信噪比大于5dB,测量均方误差小于0.05像素;输入图像相对转动位移在0.1°的范围内,转动位移对测量精度和峰噪比的影响可以忽略不计。综合分析表明像移测量均方误差小于0.05像素。     

Non-equilibrium carbothermic reduction of magnesium at the treatment of agglomerated particles “magnesium oxide–carbon” in the plasma jet

Theoretical estimations are made in order to support the possibility of the non-equilibrium carbothermic reduction of magnesium after the plasma treatment of agglomerated particles-decamicron mechano-composites which consist of uniformly mixed reacting nano- and sub-micron insertions of magnesium oxide and soot with the preset stoichiometric composition. Experimental results are presented to confirm the practical attainability of the process.     

Influence of the preparation method of precipitated Fe?Mn catalysts on their properties in CO hydrogenation

Studies of the properties of precipitated Fe–Mn catalysts in CO hydrogenation have revealed that samples precipitated from iron and manganese nitrates by sodium carbonate are more selective to olefins than those precipitated by ammonia. Difference in the catalytic properties is due to the different phase compositions of the catalysts.

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青蒿素转化成异氢化青蒿酸及有关反应

本文报道从青蒿素经六步反应转化成异氢化青蒿酸。青蒿素经酸处理得失碳倍半萜内酯3,3经硷水解再酯化生成α,β-不饱和酮酯5,然后由Wittig反应得共轭双烯酯6,用RaneyNi(W_2)催化氢化生成异氢化青蒿酸酯7,最后经硷水解得到异氢化青蒿酸8。