Application of DEM modified with enlarged particle model to simulation of bead motion in a bead mill

We applied the discrete element method （DEM） of simulation modified by an enlarged particle model to simulate bead motion in a large bead mill. The stainless-steel bead mill has inner diameter of 102 mm and mill length of 198 mm. The bead diameter and filling ratio were fixed respectively at 0.5 mm and 85%. The agitator rotational speed was changed from 1863 to 3261 rpm. The bead motion was monitored experimentally using a high-speed video camera through a transparent mill body. For the simulation, enlarged particle sizes were set as 3-6 mm in diameter. With the DEM modified by the enlarged particle model, the motion of enlarged particles in a mill was simulated.The velocity data of the simulated enlarged particles were compared with those obtained in the experiment. The simulated velocity of the enlarged particles depends on the virtual frictional coefficient in the DEM model. The optimized value of the virtual frictional coefficient can be determined by considering the accumulated mean value. Results show that the velocity of the enlarged particles simulated increases with an increase in the optimum virtual frictional coefficient, but the simulated velocity agrees well with that determined experimentally by optimizing the virtual frictional coefficient in the simulation. The computing time in the simulation decreases with increased particle size.     

Enantioselective copper-catalyzed 1,4-addition of dialkylzincs to enones using a novel N,N,P–Cu(II) complex

Enantioselective copper-catalyzed 1,4-additions of dialkylzincs to enones were carried out in the presence of 1 mol % of Cu(OTf)₂ and 2.5 mol % of an N,N,P-ligand possessing a tert-butyl group at the adjacent position of the nitrogen of pyridine to afford the corresponding 1,4-adducts in up to 98% ee.     

An anthracene-based Cd fluorescent chemosensor with a 4,7-bis(2-hydroxyethyl)-9-hydroxy-1,4,7-triazanonyl group as a highly selective chelator to Cd over Zn

We have developed a Cd²⁺ fluorescent chemosensor with high selectivity as well as sensitivity by tethering a 4,7-bis(2-hydroxyethyl)-9-hydroxy-1,4,7-triazanonyl chelator to anthracene. This sensor features the ability to discriminate Cd²⁺ from Zn²⁺ to a high degree (K_dZn/K_dCd = 560) in a pH 7.2 buffer.     

Observation of bubble layer formed on hydrogen and oxygen gas-evolving electrode in a magnetic field

The evolution of hydrogen and oxygen gasses in a 0.36-M KOH electrolyte was observed in a magnetic field, and the void fraction was calculated by a hydrodynamic model. Both gasses evolving on a platinum working electrode formed a bubble layer which increased the ohmic resistance. In addition to natural convection, magnetohydrodynamic (MHD) convection in a magnetic field improved the electrolytic conductivity by supplying a fresh solution (pumping effect) and removing gas bubbles. The MHD convection reduced the void fraction of hydrogen gas more than that of oxygen, which can be explained by the poor wettability of the oxygen evolving electrode.     

Epoxidation of Allylic Alcohols with Hydrogen Peroxide Catalyzed by [PMO12O40]3-[C5H5N+(CH2)15CH3]3

Applicatims a Mo- and W-based heteropoly acids (HPA) as a catalyst in the oxidation of olefins have extensively been investigated¹. However, a patent work is only attempted concerning the evoxidatim of olefins with H₂0₂ by HPA²⁾ since the oxirane ring is cleaved because of a strong acidity of HPA itself. Herein, an effective epoxidatim of some allylic alcohols with H₂0₂ by a new Mo-species (MPCP), which was prepared from 12-molybdatophosphoric acid (H₃PMo₁₂0₄₀) and cetylpyridinium chloride (C₅H₅N (CH₂), ₁₅CH₃- C1^-) under two-phase conditions using chloroform as an organic solvent, is described.     

Phase behaviour of thermotropic banana-shaped compounds under pressure

The phase behaviour of two achiral bent core banana-shaped compounds, the hexyloxy (compound I) and decyloxy (compound II) members of the 1,3-phenylene bis[N-(2-hydroxy-4-n-alkoxybenzylidene)-4′-aminobenzoate] series was investigated under hydrostatic pressures up to 300?MPa using high pressure differential thermal analysis and light transmission methods. The reversible transition sequence crystal (Cr₁)–B₁ phase–isotropic liquid (I), observed at room pressure for compound I, remains in the pressure region up to c 70?MPa. At higher pressures a pressure-induced crystalline phase (Cr_i) appears between the Cr₁ and B₁ phases, its temperature region becoming wider with increasing pressure. The temperature vs. pressure phase diagram shows a triple point of 72.9?MPa and 160.3°C for the Cr₁, Cr_i and B₁ phases, indicating the lower limit of pressure for the Cr_i phase. In compound II the reversible transition sequence crystal (Cr₁)–B₂ phase–I is seen over the whole pressure region, and the temperature range of the B₂ phase remains unaltered. It is concluded that both the B₁ and B₂ banana phases are stable over the whole pressure region studied.     

Alternating copolymers of hexafluoroisobutylene with vinyl trifluoroacetate and vinyl pentafluorobenzoate

Copolymerizations of hexafluoroisobutylene (HFIB) with vinyl pentafluorobenzoate (VPFB) and vinyl trifluoroacetate (VTFA) were carried out in bulk using perfluorodibenzoyl peroxide as the radical initiator. The copolymers obtained were characterized by proton and fluorine NMR spectroscopy. The monomer reactivity ratios in the polymerization of HFIB with VPFB were r₁ (HFIB) = 0, r₂ (VPFB) = 0.373, and r₁r₂ = 0. The results indicated that these copolymers have alternating structures. Similarly, the copolymers of HFIB and VTFA also showed alternating structures. The films of HFIB‐co‐VPFB were prepared by casting THF solution of polymers. Films obtained were flexible and transparent. The refractive indices of copolymers were 1.4549, 1.4490, and 1.4438 at 532, 633, and 839 nm, respectively. The average T_gs of HFIB‐co‐VTFA and HFIB‐co‐VPFB were 52 and 71 °C, respectively. From these results, the T_g of the hypothetical HFIB homopolymer is postulated to be in between 70 and 90 °C, which may be useful in the assessment of T_gs of HFIB copolymers with other vinyl monomers. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012