A novel process of chlorinating roasting followed by chlorinating leaching to extract platinum and gold from copper anode slimes was proposed in this research. Results of thermodynamic analysis and ...experimental research showed that the platinum was chlorinated into PtCl2 while the gold existed in the form of metallic Au during the roasting process. With the copper anode slime being directly leached using a traditional process, the Pt recovery rate was low and came to 80.72%. After the roasting process with sodium chloride and concentrated sulfuric acid in oxygen atmosphere, the recovery rate of Pt increased to a value around 95%. Moreover, with excessive addition of concentrated sulfuric acid, more H2O (g) was generated and the formation of Cl2 (g) decreased due to the transition from HCl (g) and Cl2 (g), as a result of which the Pt recovery rate decreased. In addition, this chlorinating roasting had little effect on the Au recovery due to its difficulty to be chlorinated.
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•The passive current for amorphous steel increased with temperature distinctly.•Reduction of Cr2O3 in the passive film of amorphous steel was observed.•Direct evidence of the ...heterogeneous passive film on 316 LSS was provided.•The initiation and growth of the pits for the amorphous steel were inhibited.
Temperature dependence of corrosion behaviour in simulated wet storage conditions for spent nuclear fuels were investigated systematically by comparing SAM2X5 amorphous steel and 316 L SS. Results indicated that with elevating temperature, the passive current for the amorphous steel increased distinctly but without pitting corrosion. The sensitivity of the passive current with temperature for the amorphous steel was related to the reduction of Cr2O3 content and altered semiconductor characteristics for its passive film, and the prominent pitting resistance at higher temperatures was associated with the remarkably inhibited pit initiation by the uniform passive film and the suppressed stable growth of metastable pits.
•New model for solute transport in deformable medium with dynamic hydraulic conductivity and degree of saturation•The Dynamic hydraulic conductivity model (Model Kp) results in less excess pore ...pressure build up, faster soil deformation and slightly slower solute transport.•The Dynamic degree of saturation model (Model Srp) does not affect to peak excess pore pressure but would accelerate contaminant migration.•Dynamic K and dynamic Sr are coupled effects and can not be simply added up. To correctly consider dynamic effects for both simultaneously, Model Kp+Srp is applicable.
The effects of the pore pressure related dynamic hydraulic conductivity and dynamic degree of saturation on the consolidation-induced solute transport in deformable unsaturated soils are investigated. The storage equation and solute transport equations are revised to account for the dependence of these two soil parameters on pore pressures. Three dynamic models were conducted for dynamic hydraulic conductivity, dynamic degree of saturation, and both. Compared with the conventional model, the simulation results showed that both hydraulic conductivity and degree of saturation increased near the soil surface where pore pressure exceeded air-entry value. Dynamic hydraulic conductivity results in a slightly slower solute transport while dynamic degree of saturation accelerates the migration of contaminants. Including both dynamic effects produced limited differences in solute concentration, while consolidation results were affected significantly. Although dynamic degree of saturation has some influences on consolidation-induced solute transport, the correlation of the dynamic path is less significant. The air-entry value is an important parameter to determine when soil parameters become dynamic, and it affects the soil consolidation process in certain extent. This study provides new methods to incorporate in-homogeneous soil parameters, which are not only spatiotemporal variables, but also dynamic variations with pore pressure.
Soil permeability is one of key factors in the prediction of the wave-induced seabed response, which needs to be considered in the design of foundation around marine installations. Most previous ...studies in the field treated the soil permeability as a constant or varying in spacial domain, although it depends on numerous soil parameters. In this study, the soil permeability is considered as a function of pore-water pressures as reported in the literature. With this new feature, the governing equations will become non-linear differential equations. Numerical examples demonstrate the considerable influence of dynamic soil permeability on the wave-induced pore pressure and effective stresses. It is concluded that the conventional model with constant soil permeability under-estimates the liquefaction potential.
•New conceptual model for wave–seabed–pipe interactions around a submarine pipeline with dynamic soil permeability.•Effects of dynamic soil permeability on the wave-induced pore pressures and effective normal stresses are insignificant.•The conventional model with a constant permeability underestimates the wave-induced liquefaction potential around a submarine pipeline.
We statistically investigate the spectral scalings of magnetic fluctuations at the upstream and downstream regions near the Venusian bow shock and perform a differentiation by shock geometry. Based ...on the Venus Express data, 115 quasi-parallel (
Q
‖
) bow shock crossings and 303 quasi-perpendicular (
Q
⊥
) bow shock crossings are selected. The statistical results suggest that the bow shock tends to modify the upstream spectra flatter to 1/
f
noise in the magnetohydrodynamics (MHD) regime and steeper to turbulence in the kinetic regime after the magnetic fluctuations crossing the bow shock, and this modification for the
Q
‖
and
Q
⊥
bow shocks is basically consistent. However, the upstream spectral scalings are associated with the shock geometry. The changes of the spectral scalings of magnetic fluctuations near the
Q
‖
bow shocks are not as significant as near the
Q
⊥
bow shock crossings. That might result from the fluctuations generated by the backstreaming ions which can escape across the
Q
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bow shock into the foreshock. Our results suggest that the energy cascade and dissipation near Venus can be modified by the Venusian bow shock, and the
Q
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bow shock plays an important role on the energy injection and dissipation in the solar wind interaction with Venus. The large dispersion of spectral scalings indicates that this fluctuation environment is complicated, and the shock geometry is not the only key factor in the fluctuations across the Venusian bow shock. Other possible factors in the shock modification to the upstream fluctuations will be explored in future.
► Interspecies correlation estimation (ICE) models were used to predict toxicity data for zinc in China. ► There were no significant differences between the ICE- and the measured-based SSDs and HC5s. ...► The most sensitive species to zinc were invertebrates, especially crustaceans. ► A combination of measured and ICE-derived data will prove useful to derive water quality criteria.
Species sensitivity distributions (SSDs) are usually used in the development of water quality criteria and require a large number of toxicity values to define a hazard level to protect the majority of species. However, some toxicity data for certain chemicals are limited, especially for endangered and threatened species. Thus, it is important to predict the unknown species toxicity data using available toxicity data. To address this need, interspecies correlation estimation (ICE) models were developed by US EPA to predict acute toxicity of chemicals to diverse species based on a more limited data set of surrogate species toxicity data. Use of SSDs generated from ICE models allows for the prediction of protective water quality criteria, such as the HC5 (hazard concentration, 5th percentile). In the present study, we tested this concept using toxicity data collected for zinc. ICE-based-SSDs were generated using three surrogate species (common carp (Cyprinus carpio), rainbow trout (Oncorhynchus mykiss), and Daphnia magna) and compared with the measured-based SSD and corresponding HC5. The results showed that no significant differences were observed between the ICE- and the measured-based SSDs and HC5s. Furthermore, the examination of species placements within the SSDs indicated that the most sensitive species to zinc were invertebrates, especially crustaceans. Given the similarity of SSD and HC5s for zinc, the use of ICE to derive potential water quality criteria for diverse chemicals in China is proposed. Further, a combination of measured and ICE-derived data will prove useful for assessing water quality and chemical risks in the near future.
Disks of a eutectic Cu–Ag alloy were processed by high-pressure torsion (HPT) up to 20 revolutions to reveal the microstructural evolution and mechanical properties. Both the Cu and Ag phases were ...thinned continuously with increasing numbers of revolutions. After 20 revolutions, the alternating Cu and Ag phases were significantly refined and became fibrous with dimensions as thin as 5
nm. The strain hardening behavior of the Cu–Ag alloy was characterized after different numbers of HPT revolutions, and a saturation microhardness was attained. It is shown that the tensile fracture mode changed from necking to fully brittle shearing with increasing numbers of revolutions, and some shear offsets with sizes of ∼5–20
μm were observed on the fracture surfaces. Based on the abnormal saturation microhardness value of the eutectic alloy, the strengthening mechanisms of various Cu–Ag alloys are discussed.
The associations between long-term risk of hepatocellular carcinoma (HCC) and spontaneous seroclearance of HBV e antigen (HBeAg), HBV DNA and HBV surface antigen (HBsAg) have never been examined by a ...prospective study using serially measured seromarkers. This study aimed to assess the importance of spontaneous HBeAg, HBV DNA and HBsAg seroclearance in the prediction of HCC risk.
This study included 2946 HBsAg seropositive individuals who were seronegative for antibodies against HCV and free of liver cirrhosis. Serial serum samples collected at study entry and follow-up health examinations were tested for HBeAg, HBV DNA and HBsAg. Cox proportional hazards models were used to calculate the HRs of developing HCC after seroclearance of HBV markers.
The HR (95% CI) of developing HCC after seroclearance of HBeAg, HBV DNA and HBsAg during follow-up was 0.63 (0.38 to 1.05), 0.24 (0.11 to 0.57) and 0.18 (0.09 to 0.38), respectively, after adjustment for age, gender and serum level of alanine aminotransferase at study entry. High HBV DNA levels at the seroclearance of HBeAg (mean±SD, 4.35±1.64 log10 IU/mL) may explain the non-significant association between HBeAg seroclearance and HCC risk. Among HBeAg seronegative participants with detectable serum HBV DNA at study entry, the lifetime (30-75-years-old) cumulative incidence of HCC was 4.0%, 6.6% and 14.2%, respectively, for those with seroclearance of both HBV DNA and HBsAg, seroclearance of HBV DNA only, and seroclearance of neither.
Spontaneous seroclearance of HBV DNA and HBsAg are important predictors of reduced HCC risk.
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