EFFECTS OF SECONDARY AIR INJECTION ON GAS-SOLID FLOW BEHAVIOR IN CIRCULATING FLUIDIZED BEDS

Effects of secondary air injection on the hydrodynamics such as solid holdup and gas-solid flow behavior were investigated in a circulating fluidized bed. The gas velocity in the riser, the ratio of secondary air velocity to that of primary air, and the solid circulating rate were chosen as operating variables. Fluid cracking catalyst(FCC) with a density of 1840 kg/m³ and a mean diameter of 74 um was employed as the solid phase. The secondary air was fed to the riser radially or tangentially at the wall of the column. Pressure drop fluctuations in the riser were measured and analyzed by adopting the stochastic method to characterize the effects of secondary air injection on the gas-solid flow behavior in the bed.

It has been found that the injection of secondary air into the riser can increase the solid holdup in the riser considerably, and that the tangential injection of secondary air is more effective for the increasing the solid holdup than the radial injection. However, the gas-solid flow behavior has been found to become less persistent with the injection of secondary air; the resultant flow behavior is more complex when the air is injected tangentially than radially. The solid holdups in the primary as well as secondary zones of the riser have been well correlated in terms of not only operating variables but also fractal dimension of the pressure fluctuations.     

Effect of Milling Conditions on the Strength of Alumina–Silicon Carbide Nanocomposites

Processing effects of wet ball-milling on the microstructure and fracture strength of Al₂O₃/5 vol% SiC nanocomposites were investigated. Homogeneous microstructure and a high fracture strength of 1200 MPa could be achieved under the milling condition of relatively low wear contents of Al₂O₃ grinding media, maintaining the homogeneity of the ball-milled powders. The fracture strength decreased with increasing wear content. Degradation of fracture strength was caused by abnormal grain growth related to wear particles from the Al₂O₃ balls.     

THE EFFECT OF CRAWFISH PROTEASES ON INACTIVATION AND THE HYDROLYTIC CLEAVAGE OF PECTIC ENZYMES1

Four proteases (CP‐I, ‐II, ‐111 and ‐IV) were isolated and purified from hepatopancreas of crawfish. Based upon their activities with known inhibitors, they resembled trypsin. All were cross‐reactive with polyclonal antibodies raised against CP‐II, indicating they shared structural components. Each of these was able to inactivate orange peel pectinesterase, tomato pectinesterase and pectate lyase C at room temperature under nondenaturing conditions. Using matrix‐assisted‐laser‐desorption time of flight mass spectrometry (MALDl‐TOF MS), an analysis of peptides generated during proteolysis of pectate lyase C from Erwinia chrysenthemi showed similar peptide patterns for the four crawfish proteases, indicating a common specificity for each isozyme. However, the cleavage patterns were different from those obtained by the action of bovine trypsin on pectate lyase C. These studies indicate the four proteases from the hepatopancreas of crawfish are isozymes which may be used for the inactivation of pectinolytic enzymes.     

Electrochemical oxidation of some basic alcohols on multiwalled carbon nanotube–platinum composites

Some composites of multiwalled carbon nanotubes, which were chemically treated in acidic and/or hydrogen peroxide solution, and platinum nanoparticles were prepared by the simple reduction in glycerol solution. Carboxylated and/or hydroxyl MWNTs were structurally analysed using X-ray photoelectron spectroscopy. In addition, the MWNT?CPt composites were characterized by XRD and TEM in detail. The electrochemical oxidation of some basic alcohols, which was catalyzed by the MWNT?CPt composites, was analysed by cyclic voltammetry. Their catalytic activities were studied with cyclic voltammograms of alcohols.     

Quantum nonlocality for a mixed entangled coherent state

Quantum nonlocality is tested for an entangled coherent state, interacting with a dissipative environment. A pure entangled coherent state violates Bell's inequality regardless of its coherent amplitude. The higher the initial nonlocality, the more rapidly quantum nonlocality is lost. The entangled coherent state can also be investigated in the framework of 2 X 2 Hilbert space. The quantum nonlocality persists longer in 2 X 2 Hilbert space. When it decoheres it is found that the entangled coherent state fails the nonlocality test, which contrasts with the fact that the decohered entangled state is always entangled.     

Synthesis and thermoelectric/electrical characterization of electrodeposited SbxTey thin films

Sb_xTe_y films were potentiostatically electrodeposited from acidic nitric baths at room temperature by controlling the applied potential. Near-stoichiometric Sb₂Te₃ thin films were obtained at applied potentials between ?0.15 and ?0.30 V vs. saturated calomel electrode (SCE). Post-annealing in a reducing environment resulted in an improvement in the crystal structure without the evaporation of the Te element. This result was indicated by a significant reduction in the electrical resistance and decrease in the FWHM of the main diffraction peaks. The power factor (σS²) increased from 44.2 to 372.1 μW/m K² after annealing at 473 K.