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1

Flotation behavior and adsorption mechanism of sodium lauroamphoacetate to cassiterite

Chen Y., Lv H., Tong X., Xie X.

Physicochemical Problems of Mineral Processing

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2018

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Vol. 54, iss. 2

386--394

EN

The flotation behavior and adsorption mechanism of cassiterite using sodium lauroamphoacetate (SLA) as a collector were investigated by adsorption tests, micro-flotation tests, zeta potential measurements, Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analysis. Adsorption test results indicated that the adsorption of SLA on the cassiterite surface increased continually with the increase of SLA concentration. Micro-flotation test results demonstrated that SLA had a stronger collecting ability to cassiterite than salicylhydroxamic acid (SHA) and sodium oleate (NaOL) in the pH range of 2-12, and showed a higher selectivity in the separation of cassiterite-quartz than in cassiterite-clinochlore. The zeta potential measurement results indicated that the isoelectric point (IEP) of cassiterite minerals changed from pH 3.9 to 3.4, suggesting the adsorption of SLA on cassiterite surface. The FTIR spectra and XPS analysis further confirmed that SLA chemically adsorbed on cassiterite surface.

2

Fast and effective extraction for equivalent shunt resistances of triple-junction concentrator solar cells

Lv H, Dai J, Sheng F, Liu W, Ma X, Cheng C, Lv Q

Optica Applicata

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2015

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Vol. 45, nr 2

227--235

EN

Fast and effective extraction of equivalent shunt resistance for each subcell of GaInP/GaInAs/Ge triple-junction concentrator solar cells is presented. The two-diode model of single junction was introduced to establish the equivalent circuit of triple-junction solar cells. The current-voltage characteristic of the triple-junction solar cells was measured under AM1.5D spectrum, C = 576 and T = 303 K. Equivalent shunt resistance of each subcell was extracted from its estimated current-voltage curve. The estimated current-voltage curve of the triple-junction solar cells shows a good agreement with the experimental data in 0.31% deviation. The degradation in the equivalent shunt resistance for Ge subcell was intentionally introduced to indicate the mechanism of current-matching operation for different subcells, with the maximum output power of the triple-junction solar cells deteriorating from 3.5 to 3.17 W. The results can offer performance analysis and optimum design of photovoltaic applications.

3

Temporal pattern prevails over spatial variability in phytoplankton communities from a subtropical water supply reservoir

Lv H., Yang J., Liu L.

Oceanological and Hydrobiological Studies

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2013

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Vol. 42, No. 4

420--430

EN

Phytoplankton species are dominant components in reservoir ecosystems, yet little is known about their variability and dynamics, especially along the depth continuum. This study examined vertical and horizontal differences in phytoplankton communities in a typical subtropical deep reservoir (i.e. Dongzhen Reservoir) from 2011 to 2012. Phytoplankton communities separated into four groups based on the biomass data, indicating that temporal differences in the community structure were greater than spatial differences. Autumn communities had the highest diversity measured by the Shannon-Wiener index (2.47±0.07), while summer communities had the lowest diversity (0.46±0.09). Both winter and spring communities were dominated by diatoms (90.4±1.7%), while cyanobacteria dominated in summer communities during our sampling period. In spring and summer, however, the three surface communities characterized by high biomass were most similar to each other, indicating that vertical variation was significantly higher than horizontal differences. Furthermore, Cylindrospermopsis raciborskii accounted for over 96% of the total phytoplankton biomass in the summer surface water. The redundancy analysis (RDA) illustrated that the temporal factor (summer), the spatial factor (depth), and nutrients (nitrite and nitrate nitrogen, ammonium nitrogen, phosphate phosphorus) were significant variables affecting the dynamics of phytoplankton communities. High temperature with stable thermal stratification might have been the cause of C. raciborskii dominance in Dongzhen Reservoir in summer. Regular and long-term monitoring of dominant species is urgently needed for water quality protection and sustainable reservoir management.

4

Small-signal circuit modeling for a semiconductor optical amplifier monolithically integrated with a sampled grating distributed Bragg reflector laser

Lv H., Li Z., Yang T., Huang C.

Optica Applicata

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2012

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Vol. 42, nr 1

55-68

EN

In this paper, a small-signal equivalent circuit model of a semiconductor optical amplifier (SOA) monolithically integrated with a sampled grating distributed Bragg reflector (SGDBR) laser is presented. To take into account the wavelength dependence of the circuit parameters of our model, the extraction of parameters has been performed by fitting the circuit model including parasitic effect with measured S-parameters of the integrated device for different operating wavelengths of the SGDBR laser. The optical frequency chirp caused by the current modulation of the SOA section has been simulated by the obtained small-signal circuit model.