Calculation of activation volumes of thermal conversions of trimethylsilyl(cumyl) peroxide by the spline approximation method

The overall rate constants k_s of thermal conversions of trimethylsilyl(cumyl) peroxide (TMSCP) at pressures P up to 10 kbar are separated into components taking into account the ratios of the corresponding products: the rate constants of radical decomposition k_d and the rate constant of rearrangement k _r. Spline approximation of experimental dependences of lnk on P is used to determine the continuous dependence of the activation volume V^# on P in the solvents cyclohexane, anisole, toluene, n-nonane, isopropylbenzene, and tert-butylbenzene. The dependences of V_s^#, V_d^#, V_r^# on P are synchronous and nonordinary, and their nature significantly depends on the choice of a solvent. Spline approximation of experimental dependences of the TMSCP concentrations on the reaction time in isopropylbenzene at various P is used to find differential constants k_s , which generally increase with the reaction time, especially in the pressure interval 5–10 kbar.Translated from Kinetika i Kataliz, Vol. 45, No. 6, 2004, pp. 836–841.Original Russian Text Copyright © 2004 by Zhulin, Rudakov, Antonovskii.     

Reaction of the superacid HGeCl3 with aromatic compounds. 5. Hydrogermylation of benzene,toluene, m-xylene,and mesitylene at high pressure

Conclusion Trichlorogermane under pressure can effect the noncatalytic hydrogermylation of aromatic multiple bonds in benzene and its simpler methyl derivatives with the preferential formation of the corresponding bisgermyl derivatives of cyclohexene. The reaction is accelerated by the introduction of methyl groups into the molecule in agreement with the electrophilic nature of trichlorogermane, and the considerable accelerating effect of high pressure can be considered as evidence of a slow stage in this process, proceeding via a molecular mechanism.For communication 4, see [1].For the preliminary communication, see [2].Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 882–886, April, 1987.The authors wish to thank M. Ya. Botnikov for assistance in carrying out the GLC-mass spectrometry studies.     

Large‐area Ag nanorod array substrates for SERS: AAO template‐assisted fabrication,functionalization, and application in detection PCBs

Highly ordered arrays of thiolated β‐cyclodextrin (HS‐β‐CD) functionalized Ag‐nanorods (Ag‐NRs) with plasmonic antennae enhancement of electrical field have been achieved for encapsulation and rapid detection of polychlorinated biphenyls (PCBs). The large‐area ordered arrays of rigid Ag‐NRs supported on copper base were fabricated via porous anodic aluminum oxide (AAO) template‐assisted electrochemical deposition. The inter‐nanorod gaps between the neighboring Ag‐NRs were tuned to sub‐10 nm by thinning the pore‐wall thickness of the AAO template using diluted H₃PO₄. The nearly perfect large‐area ordered arrays of Ag‐NRs supported on copper base render these systems excellent in surface‐enhanced Raman scattering (SERS) performance with uniform electric field enhancement, as testified by the SERS spectra and Raman mappings of rhodamine 6 G. Furthermore, the Ag‐NRs were functionalized with HS‐β‐CD molecules so as to capture the apolar PCB molecules in the hydrophobic cavity of the CD. Compared to the ordinary undecorated SERS substrates, the HS‐β‐CD modified Ag‐NR arrays exhibit better capture ability and higher sensitivity in rapid detection of PCBs. Copyright © 2012 John Wiley & Sons, Ltd.     

Numerical simulation on mixing dynamics of flexible filamentous particles in the transverse section of a rotary drum

Flexible filamentous particles are a special kind of particles and play a significant role in many industrial processes.The mixing dynamics of flexible filamentous particles in the transverse section of a rotary drum were analyzed numerically in two dimensions.First,a chain model of slender bodies was introduced for particle dynamic studies,and each individual particle as well as each segment of the particle was tracked during the process.Then,the bulk movement of particles in the transverse section of a rotary drum was explored numerically and mixing dynamics of the particles were further investigated with visual representation.To quantify the quality of mixing,the mixing rates were investigated to determine the mixing extent of particles in the rotary drum.Furthermore,the effects of rotational velocity,flight height and filling degree on mixing dynamics were examined in detail.Moreover,the numerical results were compared with experimental data,and reasonable agreements were obtained.The numerical analyses provide valuable insights into the mixing dynamics of flexible filamentous particles.     

Orientation of cylindrical particles in gas–solid circulating fluidized bed

The orientation of cylindrical particles in a gas–solid circulating fluidized bed was investigated by establishing a three-dimensional Euler–Lagrange model on the basis of rigid kinetics, impact kinetics and gas–solid two-phase flow theory. The resulting simulation indicated that the model could well illustrate the orientation of cylindrical particles in a riser during fluidization. The influences of bed structure and operation parameters on orientation of cylindrical particles were then studied and compared with related experimental results. The simulation results showed that the majority of cylindrical particles move with small nutation angles in the riser, the orientation of cylindrical particles is affected more obviously by their positions than by their slenderness and local gas velocities. The simulation results well agree with experiments, thus validating the proposed model and computation.