Activation and structural and adsorption features of activated carbons with highly developed micro-, meso- and macroporosity

Three sets of activated carbons (ACs) were prepared with the same precursor but activated differently (by CO₂ or water vapour) with various burn-off levels. The ACs demonstrate increased deviation of the pore shape from the slitshaped model with increasing burn-off and contributions of pores of different sizes depending on the activation type. Significant re-arrangement of adsorption complexes, especially of the Van der Waals type characteristic for nonpolar or weakly polar adsorbates (H₂, CH₄, CH₂Cl₂, CHCl₃), occurs in both micropores and mesopores of ACs with decreasing temperature. The behaviour of their mixtures with water and DMSO can strongly differ from that of individual adsorbates.     

Effect of temperature and a weakly polar organic medium on water localization in slit-like pores of various sizes in microporous activated carbon

The joint adsorption of water and methane in pores of the synthetic carbon adsorbent with specific surface area of 3463 m²/g was studied by ¹H NMR spectroscopy. It was shown that during adsorption of water and methane in pores of activated carbon AC86 under conditions of low surface filling the adsorbate molecules are localized not only in micropores, but in mesopores as well, and are revealed in the spectra as several signals with different values of the chemical shift. A substantial drop in the magnetic shielding effect of the carbon surface was detected upon a reduction in temperature; this is explained by the presence of two energy minima on the curves of the adsorption potential energy (close to the walls and in the center of pores) and allows the migration of adsorbed molecules from the walls to the center of pores, which are characterized by a lower shielding effect.     

(HET) Arylation of substituted acetonitriles. 1. Synthesis of 2-amino-3-(benzimidazol-2-yl)pyrrolo [2,3,b]-quinoxalines

It was shown that hetarylation of benzimidazol-2-ylacetonitriles by 2,3-dichloro-quinoxaline proceeds at the methylene group. The reaction of 2-chloro-3-[-cyano--(benzimidazol-2-yl) methylene]-3,4-dihydroquinoxalines formed with primary amines leads to 1-R-2-amino-3-(benzimidazol-2-yl)pyrrolo [2,3-b] quinoxalines.Translated from Khimiya Geterotsikli-cheskikh Soedinenii, No. 8, pp. 1119–1123, August, 1988.     

Development of Software for Simulating and Analyzing the Dynamics of Charged-Particle Beams in Synchrotrons and Beam Lines

The paper considers software for the simulation and analysis of transverse dynamics of charged particle beams in synchrotrons and beam lines. It calculates the transverse beam dynamics in synchrotrons and beam lines based on the linear model, the structural functions of synchrotrons and beam lines, the beam acceptance and emittance, and the orbit correction. The software is capable of calculating the orbit-correction quality distributions and reconstructing the transport matrix parameters from the response matrices.     

Heteroarylation of acetonitriles. 3. Heteroarylation of pyridin-2-yl and quinolin-2-ylacetonitriles by chloroquinoxalines

It has been shown that -chloroquinoxalines heteroarylate pyridin-2-yl and quinolin2-ylacetonitriles primarily at the methylene group. A method has been developed for synthesizing 1-R-2-amino-3-heteroarylpyrrolo[2,3-b]quinoxalines permitting the preparation of compounds containing the pyridine and quinoline nuclei.For Communication 2, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 85–87, January, 1990.     

铁镍钴矩磁合金的铁心损耗

本文研究了经过纵向磁退火的铁镍钴合金带的铁心损耗,发现P/f-f曲线具有明显的反常行为。用180°畴壁移的反常涡流损耗理论模型做了解释。并提出一些减小损耗的可能途径。     

Structural characteristics of activated carbons and ibuprofen adsorption affected by bovine serum albumin

Structural characteristics of a series of MAST carbons were studied using scanning electron microscopy images and the nitrogen adsorption isotherms analyzed with several models of pores and different adsorption equations. A developed model of pores as a mixture of gaps between spherical nanoparticles and slitlike pores was found appropriate for MAST carbons. Adsorption of ibuprofen [2-(4-isobutylphenyl)propionic acid] on activated carbons possessing different pore size distributions in protein-free and bovine serum albumin (BSA)-containing aqueous solutions reveals the importance of the contribution of mesopores to the total porosity of adsorbents. The influence of the mesoporosity increases when considering the removal of the drug from the protein-containing solution. Cellulose-coated microporous carbon Norit RBX adsorbs significantly smaller amounts of ibuprofen than uncoated micro/mesoporous MAST carbons whose adsorption capability increases with increasing mesoporosity and specific surface area, burnoff dependent variable. A similar effect of broad pores is observed on adsorption of fibrinogen on the same carbons. Analysis of the ibuprofen adsorption data using Langmuir and D'Arcy-Watt equations as the kernel of the Fredholm integral equation shows that the nonuniformity of ibuprofen adsorption complexes diminishes with the presence of BSA. This effect may be explained by a partial adsorption of ibuprofen onto protein molecules immobilized on carbon particles and blocking of a portion of narrow pores.     

交直流叠加磁化下恒导磁薄片的反常涡流损耗

本文利用一致畴转模型分析了在交直流叠加磁化下恒导磁薄片的低频涡流损耗。指出涡流损耗的反常不仅壁移,而且同样存在于畴转。其原因是畴转过程中畴内磁导率是张量,从而比经典模型增加了一项“侧向涡流”。导出了转动涡流损耗反常系数η_r的表达式;并将结果在某些应用领域中作了推广,得出了相应的结论。     

高合金钢光谱分析准确度改进试验

在我国钢铁厂中,高合金钢的光谱分析受到准确度的限制,没有普遍展开。通过对两种有代表性的高合金钢,即P18高速钢及Я1不锈钢的试验,证明用摄谱方法采取种种改进以后,高合金钢的分析约可达到最小的百分均方误差1％左右。文中对某些工厂的先进经验曾加以介绍。对于高合金钢的准确度问题曾予讨论。