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As flowing film gravity concentrators, spiral separators are extensively used in the processing of numerous minerals. Appropriate design of their cross-sectional geometries has been known as an eff...

The liquid film in a spiral separator undergoes an evolution from unsteady to steady flow with increasing trough length. Understanding the process of the flow field evolution is a prerequisite for revealing the mechanism of particle segregation. In this study, a numerical investigation of the flow field evolution in a spiral separator with the cross-sectional profile of cubic parabola is conducted. The distribution profiles of the liquid film thickness, surface tangential velocity, and net radial flux along the trough length are used to characterize the stability of the liquid film shape, primary flow, and secondary flow, respectively. The results indicate that the flow field characteristics at the inner and middle troughs will reach a stable state earlier than that of the outer trough with the increase in trough length. Before reaching a fully developed steady state, the instability of the flow field characteristics at the outer trough exhibits damped oscillations. The instability of the flow field in the first turn is mainly caused by the collision between the fluid and the outer trough sidewall, which leads to large fluctuations in the flow field characteristics at the outer trough. Moreover, the unbalanced inward and outward flows generated from the collision may be the primary reason for the formation of the secondary flow. After the first turn, the flow field characteristics have approximately stabilized, but a certain transitional trough length is still required to reach a fully developed steady state. The secondary flow shows poorer stability compared with the liquid film shape and primary flow. These observations provide insight into the physics of the fluid flow in a spiral separator.

The solid particle suspension inside a flotation machine is significantly dependent on the flow field, particularly the flow hydrodynamics characteristics near the bottom of the flotation machine. In this study, a laser Doppler anemometer (LDA) was utilized to investigate the influence of the impeller diameter and the impeller off-bottom clearance of a flotation machine on the flow velocity distribution characteristics near its bottom. The results showed that centripetal, centrifugal, and transitional spiral ascending vortexes were generated for different cases of the impeller variables. The impeller diameter and the off-bottom clearance were found to have a significant and interactive influence on the flow pattern, radial and axial velocities, velocity vector distribution, and axial fluctuating root mean square (RMS) velocity characteristics. When the centripetal flow was generated with a large impeller diameter and a small off-bottom clearance, the vortex stability was improved, the low-velocity distribution area was reduced near the bottom center, and the high axial RMS velocity distribution area was extended and became more consistent. The latter provided an advantageous condition for the momentum transfer between the liquid flow and the solid particles, as well as the airflow. However, the axial RMS velocity in the centrifugal flow formed in other cases of the impeller variables was less than that in the centripetal flow. Although the increase in the impeller off-bottom clearance contributed to increasing the velocity magnitude, this is certainly disadvantageous to the service life of the impeller blades, as expected from the high-velocity area extension. These results may provide a reference for the impeller design and optimization of a KYF (Kuang Yuan Flotation) flotation machine, as well as a basis for further investigation on the behavior of the dispersed phases inside a flow field.

Introduction EsA was reported to have the effect of modulating immune response, cell proliferation and apoptosis as well as anti-inflammatory effects in acute and chronic experimental models. However, the effects of EsA on LN remain poorly understood. To investigate the roles of EsA in LN, the effects of EsA were tested on BXSB mice, a SLE model, in which male SB/Le mice and female C57BL/6 mice were hybridized through recombinant inbred species. Material and methods Twenty four BXSB mice were divided into three groups. After 4 weeks, blood samples, urine samples and kidney tissues were collected. Measurement of cytokine levels was carried out using sandwich ELISA reagent kits. Apoptotic scores were obtained with a TUNEL assay. PCNA and Caspase-3 mRNA was detected using the In Situ Hybridization Detection Kit. Results The results demonstrated that compared with the control group, EsA administration markedly controlled urine protein excretion, improved renal function, alleviated kidney damage and promoted the apoptosis of glomerular intrinsic cells and renal tubular epithelial cells in animals of the treated group (p < 0.05). Meanwhile, EsA reduced the serum IL-6 and TNF-α levels (p < 0.05), inhibited the expression of PCNA and promoted the expression of caspase-3, Fas and FasL in animals of the treated group (p < 0.05). The effects of EsA on BXSB mice were similar to dexamethasone. Conclusions All these findings indicated that EsA might play significant roles in the treatment of BXSB mice through modulation of inflammatory cytokines, inhibition of renal cell proliferation and induction of apoptosis. The special targets of EsA in lupus nephritis are worth further exploration.

The effects of linear falling ramp reset pulse related to addressing operation in an alternating current plasma display panel (AC PDP) were studied. The wall charge waveforms were measured by the electrode balance method in a 12-inch coplanar AC PDP. The wall charge waveforms show the relationship between the slope ratio of the falling ramp reset pulse and the wall charges at the end of the falling ramp reset pulse which influences the addressing stability. Then the effects of the slope ratio of the linear falling ramp reset pulse on the addressing voltage and addressing time were investigated. The experimental results show that the minimum addressing voltage increases with the increase of the slope ratio of the falling ramp reset pulse, and so does the minimum addressing time. Based on the experimental results, the optimization of the addressing time and the slope ratio of the falling ramp pulse is discussed.

Using measured capacitance—voltage curves and current—voltage characteristics for the AlGaN/AlN/GaN heterostructure field-effect transistors with different gate lengths and drain-to-source distances, the influence of drain bias on the electron mobility is investigated. It is found that below the knee voltage the longitudinal optical (LO) phonon scattering and interface roughness scattering are dominant for the sample with a large ratio of gate length to drain-to-source distance (here 4/5), and the polarization Coulomb field scattering is dominant for the sample with a small ratio (here 1/5). However, the above polarization Coulomb field scattering is weakened in the sample with a small drain-to-source distance (here 20 μm) compared with the one with a large distance (here 100 μm). This is due to the induced strain in the AlGaN layer caused by the drain bias.

Atomic layer deposition of an Al2O3 dielectric on ultrathin graphite is studied in order to investigate the integration of a high k dielectric with graphite-based substrates. Electron beam irradiation on the graphite surface is followed by a standard atomic layer deposition of Al2O3. Improvement of the Al2O3 layer deposition morphology was observed when using this radiation exposure on graphite. This result may be attributed to the amorphous change of the graphite layers during electron beam irradiation.

Ni/Au Schottky contacts with thicknesses of either 50 A/50 A or 600 A/2000 A were deposited on strained Al0.3Ga0.7N/GaN heterostructures. Using the measured C-V curves and I-V characteristics at room temperature, the calculated density of the two-dimensional electron-gas (2DEG) of the 600 A/2000 A thick Ni/Au Schottky contact is about 9.13 × 1012 cm−2 and that of the 50 A/50 A. thick Ni/Au Schottky contact is only about 4.77 × 1012 cm−2. The saturated current increases from 60.88 to 86.34 mA at a bias of 20 V as the thickness of the Ni/Au Schottky contact increases from 50 A/50 A to 600 A/2000 A. By self-consistently solving Schrodinger's and Poisson's equations, the polarization charge sheet density of the two samples was calculated, and the calculated results show that the polarization in the AlGaN barrier layer for the thick Ni/Au Schottky contact is stronger than the thin one. Thus, we attribute the results to the increased biaxial tensile stress in the Al0.3 Ga0.7N barrier layer induced by the 600 A/2000 A thick Ni/Au Schottky contact.