ChemInform Abstract: Aromatic Metal‐Centered Monocyclic Boron Rings: Co@B‐8 and Ru@B‐9.

Co@B^‐₈, Ru@B^‐₉, Co@B₈, and Ru@B₉ clusters are characterized by photoelectron spectroscopy and DFT calculations.     

Turbulent boundary layer at the border of geomagnetic trap

A new phenomenon was discovered on the basis of analysis of the Interball project data. A hot plasma flow is thermalized through the formation of “long-operating” vortex streets and local discontinuities and solitons in a distributed region over polar cusps. Plasma percolation through the structured boundary and secondary reconnection of fluctuating magnetic fields in a high-latitude turbulent boundary layer account for the main part of solar wind plasma inflow into the magnetospheric trap. Unlike local shocks, the ion thermalization is accompanied by the generation of coherent Alfvén waves on the scales ranging from ion gyroradius to the radius of curvature of the averaged magnetic field, as well as by the generation of diamagnetic bubbles with a demagnetized heated plasma inside. This “boiling” plasma has a frequency region where the spectrum is different from the Kolmogorov law (with slopes 1.2 and 2.4 instead of 5/3 or 3/2). The fluctuation self-organization in the boundary layer (synchronization of three-wave decays) was observed on certain frequency scales.     

CT-Scanning Analysis of the Inner Structure of Ancient Egyptian Mummy

Crystallography Reports - A detailed analysis of the inner structure and specific features of mummification and decoration of ancient Egyptian mummy from the Pushkin State Museum of Fine Arts,...     

New π-Conjugated Ferrocenyl-Substituted Heterocyclic Systems Containing Electron-Deficient Aromatic Nitrogen Heterocycles

A series of ferrocenyl-substituted methyl ketones and chalcones were synthesized and converted to unsymmetrical 4,6-disubstituted pyrimidin-2-amines and 2-(1H-pyrrol-1-yl)pyrimidines in which the ferrocene fragment is separated from the pyrimidine ring by π-deficient (pyridine) or π-excessive (thiophene) heterocycle. The forbidden band gap of the obtained compounds was determined on the basis of their UV spectra (\(E_{\text{g}}^{\text{opt}}\) = 1.75?2.36 eV), and their electrochemical properties were studied. The presence of a thiophene ring between the ferrocene and pyrimidine fragments reduces the redox potential of the ferrocene fragment (20?30 mV), whereas pyridine spacer between the ferrocene and pyrimidine fragment increases the redox potential of the ferrocene fragment by more than 100 mV.     

Structure and spectra of 1,3-dioxanes. II. Microwave spectrum, structural parameters, and ab initio calculations of 2-methyl-1,3-dioxane

The microwave spectra of five isotopomers with the ¹³C and ¹⁸O natural abundance isotopes of the 2-methyl-1,3-dioxane molecule (22–50 GHz) were studied. Rotational transitions of a and c types with 4 ≤ J ≤ 12 were identified. The rotational constants and the substitution r _s and effective r _o structural parameters of the molecule were determined. Ab initio calculations on 2-methyl-1,3-dioxane were performed with molecular structure optimization. The results of quantum-chemical calculations at different levels are compared with experimental data.     

流体力学半径对估算胶体微球聚集速率常数的影响

胶体粒子聚集速率常数实验值远低于理论值一直是被普遍关注的问题.聚集速率常数的理论推导是基于粒子的几何半径来考虑的,但决定粒子扩散速率及聚集速率的应该是粒子的流体力学半径(大于几何半径),因而它是使聚集速率常数实验值低于理论值的因素之一.影响流体力学半径的因素很多,其中,带电粒子在溶液中因表面存在双电层,会明显增大流体力学半径,造成聚集速率减慢.而双电层的厚度又随溶液中离子强度的不同而改变.本工作在聚集速率的公式中引入了修正因子,即几何半径与其流体力学半径之比,以修正由于用几何半径代替流体力学半径带来的误差.其中几何半径和流体力学半径可以分别用扫描电镜(SEM)和动态光散射(DLS)来测定.以两种粒径的聚苯乙烯带电微球为例,考察了在不同离子强度下,该误差的大小.结果发现,对于半径为30 nm的微球,用流体力学半径计算的慢聚集速率常数比理论值偏低约8%.该误差随离子强度增加而减少.对于快聚集情况,流体力学半径对聚集速率基本没有影响.     

Codimerization of quadricyclane withendo,exo-hexacyclo[9.2.1.02,10.03,8.04,6.05,9]tetradec-12-ene catalyzed by the Pd(PPh3)4 complex

endo,exo-Hexacyclo[9.2.0^2,10.0^3,8.0^4,6.0^5,9]tetradec-12-ene (1) undergoes cyclocodimerization with quadricyclane (Q) in the presence of the Pd(PPh₃)₄ complex to giveexo,exo,endo,exo-decacyclo[9.9.1.0^2,10.0^3,8.0^4,6.0^5,9.0^12,20.0^13,18.0^14,16.0^15,19]heneicosane (2) andendo,exo,endo,exo-decacyclo[9.9.1.0^2,10.0^3,8.0^4,6.0^5,9.0^12,20.0^13,18.0^14,16.0^15,19]heneicosane (3) in a ratio of 10 7 (yield up to 26 %). Simultaneously, homocyclotrimerization of Q occurs to give three known C₂₁ hydrocarbons (4–6). The yields of compounds2 and3 and the selectivity of the process depend considerably on the reaction conditions and the molar ratio of1 and Q. Compounds2 and3 that were obtained were characterized by¹³C NMR spectra.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1983–1985, November, 1994.