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Bioleaching is regarded as an essential technology to treat low grade minerals, with the distinctive superiorities of lower-cost and environment-friendly compared with traditional pyrometallurgy method. However, the bioleaching efficiency is unsatisfactory owing to the passivation film formed on the minerals surface. It is of particular interest to know the dissolution and passivation mechanism of sulfide minerals in the presence of microorganism. Although bioleaching can be useful in extracting metals, it is a double-edged sword. Metallurgical activities have caused serious environmental problems such as acid mine drainage (AMD). The understanding of some common sulfide minerals bioleaching processes and protection of Amd environment is reviewed in this article.

Bioleaching experiments combined with X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and scanning electron microscopy (SEM) were conducted to investigate three kinds of bornites from different regions leached by moderately thermophilic mixed bacteria of Leptospirillum ferriphilum YSK, Acidithiobacillus caldus D1 and Sulfobacillus thermosulfidooxidans ST. The results of bioleaching experiments showed that the leaching efficiency and the redox potential were significantly increased. The copper extraction efficiencies of three kinds of bornite maintained rapid growth until around the 12th day and no longer increased after the 18th reaching 83.7%, 96.5% and 86.6%, respectively. The XRD results of the leaching residue indicated that three kinds of bornites all produced jarosite in the late stage of leaching, and the leaching residues from of Daye Museum and Yunnan Geological Museum contained a mass of elemental sulfur. XPS analysis and scanning electron microscopy experiments showed that the surface of mineral particles was jarosite and the copper in the leaching residue was almost dissolved.

The phase transformation of chalcopyrite and the effect of its phase status on bacterial leaching were studied. Under the protection of high-purity argon, different temperatures (203, 382 and 552 °C) were applied to natural chalcopyrite to complete the phase change. In addition, the chalcopyrite was bioleached before and after the phase change. The results show that the chalcopyrite heated at 203 and 382 °C remained in the α phase, whereas the chalcopyrite changed from α to β phase at 552 °C. The leaching rates of chalcopyrite after the phase transitions at 203, 382 and 552 °C were 32.9%, 40.5% and 60.95%, respectively. Further, the crystal lattice parameters of chalcopyrite increased and lattice energy decreased, which were the fundamental reasons for the significant increase in leaching rate. Electrochemical experiments demonstrated that with increasing annealing temperature, the polarization resistance decreased and corrosion current density increased. The higher the oxidation rate was, the higher the leaching rate was.

The leaching of chalcopyrite under different redox potentials was studied with a redox potential controlling device based on microcontroller technology. The leaching test was carried out in a 500 mL flask with 4 g pure chalcopyrite and 200 mL sulfuric acid. The additional total Fe concentration was 0.1 mol/kg, and the initial pH was 0.7. Chalcopyrite leaching tests with initial redox potential of 400 mV and 600 mV (vs. Ag/AgCl, the same below) and controlled redox potential of 350 mV, 400 mV, 450 mV, 500 mV, and 600 mV were carried out at a temperature of 60 °C and a stirring speed of 300 rpm. The results showed that the dissolution of chalcopyrite could not be hindered until the granular intermediates (S0 and Sn2−) accumulated to a certain amount on the chalcopyrite surface. The main passivating species in chalcopyrite dissolution may be iron-deficient polysulfides. At 400 mV, the chalcopyrite passivation by polysulfides was overcome by the galvanic effect between pyrite and chalcopyrite, and the chalcopyrite was rapidly oxidized with Cu leaching rate reaching up to 32% in 7 h, while it was only 15% in the other experimental groups. However, at 450–500 mV, pyrite was oxidized and the galvanic effect between chalcopyrite and pyrite was destroyed, leading to a significant decrease in Cu leaching rate. When the redox potential was 600 mV, the dissolution of metal-deficient polysulfides was promoted, thus, the passivation was weakened.

Chalcopyrite (CuFeS2) is the most abundant copper-containing resource in the earth and is also widely distributed in solid wastes and secondary resources. Biohydrometallurgy (bioleaching) is considered as a promising minerals processing and extractive metallurgy technology because of its environmental and economic advantages over the conventional beneficiation-pyrometallurgy process, and the bioleaching of chalcopyrite is always a challenge because chalcopyrite can be easily passivated in bioleaching. Hence, it is important to understand the dissolution process and passivation mechanism of chalcopyrite in bioleaching. In this paper, the dissolution process and passivation mechanism of chalcopyrite bioleaching have been summarized and discussed according to previous publications. The reported possible passivating species are mainly S-containing species consisting of polysulfide (Sn2−), elemental sulfur (S0) and insoluble sulfate (SO42−). The effects of physicochemical properties of chalcopyrite and multiple factors on the dissolution and passivation mechanism of chalcopyrite bioleaching have been summarized. We particularly discussed the role of redox potential in chalcopyrite bioleaching and its controlling techniques.

This study investigated a potential method for the removal of arsenic from enargite leach solution containing 5.86 g/L As(V) by precipitation of magnesium ammonium arsenate (MAA). The experimental ...

Theoretically, controlling redox potential to a relatively low value and inhibiting jarosite formation on the chalcopyrite surface would be an effective strategy to accelerate the bioleaching of chalcopyrite. In this work, using limonite as seed crystals, the effects of the goethite precipitation process on the bioleaching of chalcopyrite were studied for the first time. The bioleaching results showed that the addition of limonite controlled the redox potential in an appropriate range and promoted chalcopyrite dissolution through the removal of ferric (Fe3+) ions. X-ray diffraction and scanning electron microscope analyses indicate that limonite significantly induced the goethite precipitation process and inhibited the production of jarosite. We conclude that promoting the goethite precipitation process with limonite is an effective strategy in accelerating the bioleaching process of chalcopyrite.

Alkaline leaching is a promising treatment to extract arsenic from enargite. This study investigates the feasibility of leaching enargite concentrate in the presence of pyrite in alkaline solution with sodium hydroxide only. Single factor and orthogonal experiments were performed to determine the effect of sodium hydroxide concentration, temperature, leaching time and liquid-to-solid ratio on enargite dissolution and to optimize leaching conditions. The results indicate that sodium hydroxide concentration has the greatest effect on arsenic dissolution from enargite, while the liquid-to-solid ratio has the smallest effect. Finally, over 99% of arsenic was removed using optimal conditions. Characterization of the leach residue by XRD and SEM-EDS analyses showed that enargite was converted into non‑arsenic copper sulfides such as anilite (Cu7S4), geerite (Cu8S5) and djurleite (Cu31S16). This research is applicable to solving problems related to arsenic pollution.

To investigate the correlation between CD44v6 and cyclooxygenase-2(COX-2) expression and recurrence and deterioration of pleomorphic adenoma of parotid gland.Immunohistochemistry was used to detect the expression of CD44v6 and COX-2 in 19 normal parotid tissues, 25 primary pleomorphic adenomas, 15 first recurrent pleomorphic adenoma, 15 second recurrent pleomorphic adenoma and 13 cancer in pleomorphic adenomas. The correlation between CD44v6 and COX-2 and the recurrence and deterioration of pleomorphic adenomas was evaluated using SPSS 15.0 software package.The positive expression rate of CD44v6 in normal parotid gland, primary pleomorphic adenoma, first recurrent pleomorphic adenoma, second recurrent pleomorphic adenoma and cancer was 5.26%, 44.00%, 60.00%, 93.37% and 100.00%, respectively;and the positive expression rate of COX-2 was 10.53%, 40.00%, 63.33%, 93.37% and 100.00%, respectively. There was significant difference in the positive expression intensity of CD44v6 and COX-2 among the groups (P0.05). The positive expression rate and intensity of CD44v6 and COX-2 in normal parotid gland tissue were significantly lower than those in other groups (P0.05). There was no significant difference in the positive expression rate and intensity of CD44v6 between primary pleomorphic adenoma and first recurrent pleomorphic adenoma (P0.05). There was no significant difference in the expression intensity of COX-2 between the two groups (P0.05), but the positive expression rate of COX-2 between the two groups was not significant(P0.05). The positive expression rate and intensity of CD44v6 and COX-2 in the second recurrent pleomorphic adenoma were significantly higher than those in the first recurrent pleomorphic adenoma(P0.05), but there was no significant difference between the two groups(P0.05). CD44v6 in the second recurrent pleomorphic adenoma and cancer was significantly higher than that in the first recurrent pleomorphic adenoma(P0.05). There was no significant difference in the expression rate and intensity of COX-2 (P0.05).CD44v6 and COX-2 may play an important role in promoting occurrence, invasion, recurrence and deterioration of pleomorphic adenoma through synergistic action.

The hydrophobic flocculation flotation of rutile fines in the presence of styryl phosphonic acid (SPA) was investigated by flotation tests, zeta-potential measurement, optical microscope observation, laser-based particle size analysis, adsorption measurements and DLVO theory. The flotation tests indicated that rutile fines could be flocculated by SPA, and pH, shear force (stirring speed) and stirring time played significant roles in flocculation. The isoelectric point (IEP) and zeta-potential in whole range all moved to negative values as SPA was added according to the results from zeta-potential measurement. It was demonstrated that the primary reason for above was chemical adsorption. The laser-based particle size results showed the particle size at a stirring speed of 1800 r/min and 1000 mg/L SPA was the largest in all experiments. Furthermore, using the optical microscope observation and flotation tests, it was important for flotation of rutile fines to produce the flocculant. In the light of above-mentioned facts, floc flotation of rutile fines could be induced in the form of chemical adsorption by SPA to increase particle size. The data calculated from DLVO theory also indicated that chemical adsorption was the main reason for the formation of flocculant.

The adsorption behavior and mechanism of Bi(III) ions on the rutile–water interface were investigated through micro-flotation, Zeta potential measurement, adsorption amount measurement and X-ray photoelectron spectroscopy (XPS). According to the results of micro-flotation, Bi(III) ions could largely improve the rutile flotation recovery (from 62% to 91%), and they could increase the activating sites and reduce the competitive adsorption between nonyl hydroxamic acid negative ions and OH− ions, which determined that Bi(III) ions were capable of activating rutile flotation. The adsorption of Bi(III) ions onto the rutile surface led to the shift of Zeta potential into the positive direction, which was good for the adsorption of nonyl hydroxamic acid anions. In addition, the results of XPS indicated that the chemical environment around Ti atom had not changed before and after the adsorption of Bi(III) ions. Based on the adsorption mechanism of Bi(III) ions, it was deduced that firstly Bi(III) ions occupied the vacancies of the original Ca2+, Mg2+ and Fe2+ ions on the rutile surface; secondly Bi(III) ions covered on the rutile surface in the form of hydroxides.

This study explores the influences of external iron ions on the dissolution behavior of covellite minerals at different temperatures. External iron ions can significantly accelerate covellite dissolution. The copper extraction of acid covellite leaching was less than 5%, while the addition of external iron ions (ferric or ferrous ions, Fe3+/Fe2+) effectively enhanced covellite dissolution. Covellite copper extraction with 0.1 mol/L Fe2+ was 25% at 303 K and 40% at 318 K after 18 days, and for leaching systems with 0.1 mol/L Fe3+, it was approximately 40% at 303 K and 60% at 318 K. The dissolution process of covellite with external iron ions can be divided into two stages. The dissolution kinetics at the first stage are controlled by the chemical reaction between iron ions and covellite, as the generated elemental sulfur has not yet blocked the covellite surface. Compared with ferrous ions, ferric ions further increase the dissolution rate of covellite, which is also suggested by the scanning electron microscopy analysis results. Additionally, Fe3+ accelerates the release of copper ions by effectively reducing the particle size of covellite. In the second stage (copper extraction >40%), the reaction kinetics shift to the mixed control of the surface chemical reaction with iron ions and diffusion due to the accumulation of an elemental sulfur layer on the surface. Although Fe2+ cannot directly oxidize covellite, the electron exchange between Fe2+ and oxygen is improved through the covellite mineral, which is attributed to its metallic properties. Then, the ferric ions generated in the above process gradually corrode covellite. In addition, the temperature rise can significantly accelerate the oxidation reaction process of iron ions with covellite by forming a more porous corrosive structure. Finally, leaching bacteria (Acidithiobacillus caldus and Leptospirillum ferriphilum) are proved to boost copper extraction from covellite by transforming Fe2+ into Fe3+ and eliminating surface elemental sulfur passivation. However, dense passivation layers inevitably form on the covellite surface at the end of bioleaching, which passivates the subsequent dissolution process.

Chemical element analysis and X-ray diffraction (XRD) analysis showed that the two chalcopyrite minerals were of high purity. A mixed culture of moderately thermophiles was used for chalcopyrite bioleaching at 45°C and the copper recovery of chalcopyrite (a) and chalcopyrite (b) was 66.1% and 21.4%, respectively, after 19 days of leaching. Bioleaching behavior of the two different chalcopyrite samples was studied through comparing the lattice parameter and grain size of chalcopyrite. It was shown that lattice parameter and grain size are not the key factors affecting the leaching of chalcopyrite. The corrosion current density of chalcopyrite (a) calculated through Tafel curves was 1.149 μA/cm2, while that of chalcopyrite (b) was only 0.5696 μA/cm2. The higher corrosion current density suggested that chalcopyrite (a) can be more easily dissolved than chalcopyrite (b).

Zhong-Ming Huang, He Xiao, Zhi-Gang Ji, Wei-Gang Yan, Yan-Sheng Zhang Department of Urology, Peking Union Medical College Hospital, Chinese Academy of Medical Science and Peking Union Medical College, Beijing 100730, China Background: To evaluate the evidence available on the effects and safety of tension-free vaginal tape (TVT) versus transobturator tape (TOT) for female stress urinary incontinence therapy based on randomized controlled trials (RCTs). Methods: PubMed, Cochrane, Embase, Wanfang, China National Knowledge Infrastructure, and Weipu database were searched up to July 2017 to identify relevant studies, including qualified RCT and quite-RCT and literature sources. Relative risks (RRs), mean difference (MD), and 95% CI were calculated in our review. Result: Twenty-eight RCTs were involved in the meta-analysis with 2,505 patients in the TVT group and 2,477 patients in the TOT group. The aggregated results indicated that TOT significantly decreased the operative time (MD, −1.27; 95% CI: −1.77 to −0.76) and hospital stay (MD, −0.62; 95% CI: −1.08 to −0.17) when compared with TVT. Besides, the complications (RR, 0.86; 95% CI: 0.64–1.16) and blood loss (MD, −0.29; 95% CI: −0.71 to 0.14) were decreased in TOT but with no statistical significance; the change of VAS score (MD, 0.07; 95% CI: −0.05 to 0.19), IIQ-7 score (MD, 0.06; 95% CI: −0.03 to 0.15), and UDI-6 score (MD, 0.15; 95% CI: −0.19 to 0.48) were larger in TOT group than in TVT group, but still, with no statistical significance. However, there was no significant difference of cure rate (RR, 1.00; 95% CI: 0.96–1.04) and satisfied rate (RR, 1.00; 95% CI: 0.96–1.04) between the 2 groups. Conclusion: TOT may have more valid effects than TVT in operative time and hospital stay. Besides, TOT method showed fewer complications and blood loss than TVT, but there was no significant difference between them. The scores of VAS, incontinence impact questionnaire short form-7 (IIQ-7), and urogenital distress inventory short form-6 (UDI-6) were higher in TOT than TVT, but still no significant difference was observed. However, more studies with higher quality and larger sample size that are multicentric and have longer follow-up in the form of RCTs are warranted to confirm the current findings. Keywords: TVT, TOT, SUI, meta-analysis, randomized controlled trial

The composition of passive layer of chalcopyrite was investigated by X-ray photoelectron spectroscopy (XPS), accompanied with cyclic voltammetry (CV). The leaching experiment shows that the extraction rates of Cu with leaching for 30 d by sterile control and microorganisms are 4.0% and 21.5%, respectively. In comparison, 3.8% and 10.5% Fe are leached by sterile control and microorganisms, respectively. The results of XPS studies suggest that Fe atoms dissolve preferentially from the chalcopyrite lattice, and disulfide (S 2 2− ), polysulfide (S n 2- ) and elemental sulfur (S 0 ) are identified on the chalcopyrite surfaces leached by sterile control and microorganisms. Additionally, sulfate (SO 4 2- ) is detected on the chalcopyrite surfaces leached by microorganisms, and most of it probably originates from jarosite. The analysis of CV results reveals that metal-deficient sulfide (Cu 1- x Fe 1- y S 2- z , y > x ) and elemental sulfur (S 0 ) passivate the surface of chalcopyrite electrode. The elemental sulfur and/or jarosite coating on the chalcopyrite surface may have impact on the leaching process; however, the disulfide, polysulfide or metal-deficient sulfide plays a more key role in the chalcopyrite leaching.

Chalcopyrite (CuFeS2) and marmatite [(Zn, Fe) S] are associated together most of the time in the raw ores and flotation concentrates. In this work, the interactions between chalcopyrite and marmatite during bioleaching by moderately thermophilic bacteria were investigated by electrochemical measurements and bioleaching experiments. In the initial stage of bioleaching of mixture of chalcopyrite and marmatite, the dissolution of marmatite was preferential, and was significantly accelerated with the addition of chalcopyrite because of the galvanic effect and catalytic effect of Cu2+ ions, while the dissolution of chalcopyrite was inhibited mainly due to the galvanic effect before the accomplishment of marmatite dissolution. Chalcopyrite dissolves fast when the dissolution of marmatite is finished, and small amount of marmatite cannot inhibit the final copper extraction of chalcopyrite if leaching time was long enough. Therefore, stepwise or selective bioleaching was feasible in processing mixture of chalcopyrite and marmatite to avoid complex flotation process in separating chalcopyrite and marmatite.

Additive Gauss white noise is one of the most commonly observed interferences in practical engineering applications. This paper proposed an algorithm for the adaptive determination of the optimal wavelet decomposition level based on Jarque-Bera test in efforts to solve the filtering problem of additive white Gaussian noise signal. By, The optimal decomposition level of wavelet is determined by testing the white noise which was realized by calculating skewness (S) and kurtosis (K) of the parameters. With signal-to-noise ratio (SNR) as the measurement index, simulation results show that the presented algorithm have higher accuracy, and better filtering effect on low SNR signals compared with nonparametric test methods.

The grown conditions of Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans were investigated, and then experiments were conducted to research the bioleaching behaviors of crude ore of copper sulfide and hand-picked concentrates of chalcopyrite by Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans. The experimental results show that the bacteria grow best when the temperature is (30±1) °C and the pH value is 2.0. The bacteria concentration is 2.24×107 mL−1 in this condition. It is found that the copper extraction yield is affected by the inoculum size and the pulp density and the extraction yield increases as the inoculum size grows. The bioleaching rates reach their highest point in sulfide copper and chalcopyrite with a pulp density of 5% and 10%, respectively. Column flotation experiments of low-grade copper sulfide ores show that the bioleaching recovery reaches nearly 45% after 75 days.

Accidental collisions between overheight trucks and bridge superstructures have occurred frequently in recent years. These collisions dramatically affect the safety of bridge structures and traffic systems in metropolitan areas. Frequent collision-induced bridge damages have highlighted the importance of scientific research in this field. In this study, considering the inherent difficulties of full-scale laboratory testing, the FEM is used to simulate the collision procedure. The finite-element (FE) results indicate that collisions between overheight trucks and bridge superstructures induce two types of failure modes, global damage and local damage, which need to be incorporated into bridge design guidelines. The numerical results also reveal that the collision forces are mainly influenced by the parameters associated with overheight trucks. To reduce computational costs and facilitate engineering application, a simplified model for calculating the collision forces is also proposed. The predictions of the simplified model, although slightly conservative, are in good agreement with the FE results.

The electrochemical behavior of massive chalcopyrite in presence of Acidithiobacillus caldus, Acidithiobacillus ferrooxidans, Leptospirillum ferrooxidans and Sulfobacillus thermosulfidooxidans has been studied by cyclic voltammetry. The effect of Fe2+ and Cu2+ ion addition on the electrochemical behavior of massive chalcopyrite in bioleaching system were also investigated. The voltammograms illustrated that current densities of peaks were obviously increased with adding Fe2+ into the electrolyte. A series of anodic peaks were observed at more than 0 V when adding Fe2+ and Cu2+ ions, and these peaks are similar to the peaks of the step oxidation of chalcocite, thus proving that the formation of intermediate CuS2. Especially, the 9 g/L Fe2+ and 1.5 g/L Cu2+ were added. Therefore, appropriate ferrous and cupric ions concentration could enhance the formation of intermediate CuS2 leading to accelerate dissolution of chalcopyrite.

Fault diagnostic strategy profoundly influences diagnostic efficiency and cost. Diagnostic strategy optimization is a Non-Polynomial optimizing problem, which is a hard one. Applying conventional methods to resolving it, there are some difficulties: more complex to implementing algorithm, more time to diagnosing and more difficult to attaining global optimum. Particle swarm algorithm (PSA) is a new intelligent optimization algorithm, and applied to optimizing diagnostic strategy. Function of all-in cost is constructed by state probability, isolating matrix and test cost, serving as objective function. Test sequences are directly put into particle codes. Particle speeds are transformed to learning probability towards the best one in the swarm. Given proper parameters in PSA, the method can search the global optimum in a little time. At last, an example shows the approach is feasible and effective.

In order to discuss the particle-bubble interaction during the electro-flotation of cassiterite, the recovery of cassiterite with different particle sizes was investigated, and the collision mechanism between the cassiterite particles and H2 bubbles was explored. The flotation tests were carried out in a single bubble flotation cell. The results show that cassiterite particles

The bioleaching behavior of copper and nickel from a low-grade nickel, copper, and cobalt-bearing sulfide ore was investigated. A recovery of 94% Ni, 62% Co and 70% Cu was achieved in 68 days of flask leaching including 18 days of acid pre-leaching and 50 days of bioleaching. However, a recovery of 46% Ni, 39% Co and 13% Cu was achieved in 139 days of column leaching including 19 days of acid pre-leaching and 120 days of bioleaching which indicates that nickel and cobalt have the same leaching behavior. Potassium, sodium and iron(III) ions in the leach solution formed jarosite within the ore bed with some nickel and copper ions incorporated into the jarosite precipitates thereby diminishing the overall metal recovery. Magnesium was preferentially leached by acid from the gangue minerals leaving a magnesium depleted silicate skeleton, but discrepancies in the residue analysis indicate that magnesium re-deposits into the silicate skeleton during bioleaching.

This work investigates the heap bioleaching of a low-grade nickel sulfide ore containing rather high levels of olivine, chlorite and antigorite (MgO 30–35%) present in the main gangue minerals. A 500-ton heap bioleaching system was developed and the microorganisms used in the test were a mixture of mesophiles, Acidithiobacillus ferrooxidans ( DQ321745 ), Acidithiobacillus thiooxidans ( EF059760 ) and Leptospirillum ferrooxidans (DSM2391). The inoculum used was obtained from a three-stage progressive scale-up (from 25 L to 500 L and finally to 10 m 3 ) culture. Industrial grade concentrated sulfuric acid and acid wastewater (pH 0.0–0.3) produced from off-gas treating during the smelting process were also used during bioleaching. A nickel (84.6%) and cobalt (75.0%) extraction was achieved after 350 days of heap leaching, including 80 days of acid pre-leaching and 270 days of bioleaching. The economical feasibility model predicted that the process was feasible.

Different polyaniline (PANI) micro/mesostructures have been synthesized by one-pot polymerization of aniline using hydrogen peroxide (H2O2) as oxidant and Fe3+ as catalyst under hydrothermal conditions. Well-defined PANI hollow spheres with relatively uniform sizes and controllable shell thickness can be prepared in case of low concentrations of monomer and oxidant. The oxidation−reduction reaction between the benzenoid unit and O2 is a driving force for the formation of hollow spheres. This approach provides a unique route for the preparation of well-defined PANI hollow spheres in the absence of any sacrificial templates and organic surfactants and can be potentially extended to synthesize other polymer hollow spheres.

In this work, the monitoring of bacterial and chemical dissolution of massive bornite was performed using cyclic voltammetry (CV); the mineral surface was examined using scanning electron microscopy (SEM) and the elements were indentified by Energy Dispersive X-ray Analysis (EDXA). The electrolyte employed for the electrochemical tests was the medium used for bioleaching the electrodes (3.0 g•dm-3 (NH4)2•SO4, 0.5 g•dm-3K2HPO4, 0.5 g•dm-3 MgSO4•7H2O and 0.1 g•dm-3 Ca(NO3)2).The results showed differences in voltagramms carried out by Acidithiobacillus ferrooxidans and Acidithiobacillus caldus: In bioleached electrodes tested in the presence of Acidithiobacillus ferrooxidans, the anodic and cathodic current signals were larger than with Acidithiobacillus caldus The analysis of CV results allowed attributing the different peaks observed in both the direct and reverse potential scanning to the oxidation of bornite to a secondary copper mineral(chalcocite and covellite) and its reduction via different non stoichiometric copper sulphides intermediaries. Surface evidences were produced by SEM, and chemical elements evidences were also investigated by EDAX.

The effects of several variables on the column bioleaching of copper sulphide ore have been investigated. The copper ore contained chalcopyrite as the main sulfide minerals and bornite and chalcocite as the minor minerals. The experiment was carried out using bench-scale column leach reactors designed in Key Lab of Biometallurgy of Ministry of Education, which were inoculated with the pure mesophile bacteria (Acidithiobacillus ferrooxidans) and thermophile bacteria (Sulfobacillus), respectively, and the mixed bacteria which contain both iron- and sulfur-oxidizing bacteria. The results show that the mixed cultures were more efficient than the pure cultures alone and the maximum copper recovery 53.64% was achieved using the mixed cultures after 85 days. The leaching rate of chalcopyrite tended to increase with the increased dissolved ferric iron concentration. The effect of particle size on the rate of the copper leaching was also investigated, and it was shown that the copper bioleaching rate decreases as the amount of fines increase, which limits the permeability, thus decreases leaching rate. Jarosite and elemental sulphur formed in the column were characterized by the X-ray and EDS.

This work investigates the bioleaching of Jinchuan low grade nickel-bearing sulfide ore containing rather high levels of olivine, chlorite and antigorite (MgO 30–35%) present in the main gangue minerals using a mixed mesophiles which are composed of Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans. It aims to test the technical feasibility to recover valuable metals from Jinchuan low-grade nickel-bearing sulfide ore by bioleaching process. The tolerance of the mixed bacteria to Mg 2+ could be improved markedly from 10 g/L to 25 g/L after nearly 2 years adaptation. A nickel recovery of 91% and a cobalt recovery of 81% were achieved in 312 days column leaching process including 60 days acid pre-leaching stage and 252 days bioleaching stage.

Jinchuan low grade nickel (0.4%–0.6% Ni, mass fraction) sulfide mineral ore contains a remarkably high content of magnesia (30%–35% MgO, mass fraction) present in the main gangue minerals. Bioleaching was performed to investigate the feasibility to process the mineral due to its relative simplicity, eco-friendly operation and low capital cost requirements. The mixed mesophiles were enriched from acid mine drainage samples collected from several acid mines in China. Considering that the magnesia is easily extracted by acid solution and the excessive Mg 2+ will exceed the tolerance of the mixed mesophiles, three effective means were used to reduce the disadvantage of magnesia during the bioleaching operation. They were adaptation of the mixed mesophiles to improve the tolerance; pre-leaching to remove most leachable magnesia and periodic bleeds of a portion of the pregnant leaching solution to control the level of Mg 2+ based on the tolerance of the mixed mesophiles. An extraction of nickel (90.3%) and cobalt (88.6%) was successfully achieved within a 300 d leaching process from the Jinchuan low grade nickel sulfide mineral ore using a column reactor at ambient temperature.

The bioleaching of marmatite in shaken flasks was studied. After leaching for 29 days, the leaching ratio of zinc was 91%. Three kinds of bacteria, mixture-based bacteria, 9K-based bacteria and sulfur-based bacteria were used in marmatite leaching, of which the mixture-based bacteria have the best leaching result while the sulfur-based bacteria have the worst. By analyzing the leaching residue using SEM and EDXA, the marmatite leaching mechanism was discussed.

Self-incompatibility (SI) is a genetic mechanism of self/non-self pollen recognition to prevent self-fertilization in many flowering plants and, in most cases, this is controlled by a multi-allelic S-locus. S-RNase and S-locus F box (SLF) proteins have been shown to be the female and male determinants of gametophytic self-incompatibility (GSI), respectively, in the Solanaceae, Scrophulariaceae and Rosaceae. Nevertheless, it is thought that additional factors are required for the SI response. Herein, we constructed a mature anther cDNA library from a self-incompatible Petunia hybrida Vilm. line of the S3S3 haplotype. Using AhS2-RNase from Antirrhinum hispanicum as a bait for yeast two-hybrid screening, we found that petunia germinating pollen (PGP) S/D3 was capable of interacting physically with the bait. However, the interaction lacked haplotype specificity. The PGPS/D3 gene is a single copy gene that is expressed in tissues such as the style, ovary, pollen, and leaf. The PGPS/D3::GFP (green fluorescence protein) construct was detected in both the membrane and cytoplasm. The implications of these findings in the operation of S-RNase-based SI are discussed. (Managing editor: Li-Hui Zhao)

Artemisinin is a new effective antimalarial drug extracted from the medicinal plant Artemisia annua L. There is a great interest in enhancing the production of artemisinin by means of transgenic plants. In this work, experiments with different combinations of hormone concentration were performed to obtain higher frequency of shoot and root induction. In particular, the factors influencing A. tumefaciens-mediated transformation of A. annua were explored to optimize the transformation system, which included A. tumefaciens strain, plant genotype, preculture period, composition of infection bacterium suspension, methods of co-cultivation, and co-cultivation period. Finally, a system of high efficiency of genetic transformation and regeneration of A. annua was established.

Compositional dependence of the Neel transition temperature, TN, structural stability, magnetic properties, and anomaly of resistivity, ρ, have been investigated in γ-Fe–Mn–Al–Cr–Si–C alloys. In the Fe–(20–32.5 at.%)Mn-based alloys, an increase in Mn, Al, Cr or C content will inhibit the γ→e→α′ martensitic transformation and lower the e martensitic transformation temperature Ms or deformation-induced martensitic transformation temperature Md, while an increase in Si content promotes the γ→e martensitic transformation and increases the Ms and Md temperature. Manganese raises TN, decreases the susceptibility, χ, and slightly increases the anomaly of electrical resistivity, ρ. The temperature dependence of χ for Fe–Mn binary alloys shows a break at TN and χ becomes almost independent of temperature above TN. The effects of Cr on χ versus T and ρ versus T are similar to that of Mn but lowering TN. With increasing Al or Si content, TN decreases markedly; above TN, the magnetic state of the alloys changes from Pauli-paramagnetism to the Curie–Weiss behavior, and the anomalous ρ increases rapidly, leading to a negative temperature coefficient below TN. An empirical formula has been developed to express the compositional dependence of TN in γ-Fe–Mn–Al–Cr–Si alloys. The alloying elements that lower TN are in increasing order of severity, Cr, Al, Si and C. Manganese is the only element which both raises TN and decreases χ and Ms. Adding up to 10 at.% Al to Fe–Mn based alloys strongly stabilizes the γ phase and retains antiferromagnetism down to 4 K. Increasing the Ni content of Fe–Cr–Ni steels improves their stability relative to the α′ martensitic transformation but induces a transition from the paramagnetic γ-phase to the ferromagnetic one at very low temperatures. Alloying Fe–Mn based alloys with Al and Cr exhibits an excellent combination of FCC structural stability, corrosion resistance and antiferromagnetism down to liquid helium temperature. The present results are valuable for the design of cryogenic non-magnetic steels and certain functional Fe–Mn based alloys.

As part of the efforts to understand isoflavonoid metabolism in Pueraria lobata at the molecular level, the cDNAs encoding two divergent 4-coumarate : coenzyme A ligases (4CLs, designated Pl4CL1 and Pl4CL2, respectively) were isolated from P. lobata roots. Sequence analysis revealed that Pl4CL1 had an N-terminal extension of twenty-one amino acid residues compared to Pl4CL2. Phylogenetic analysis showed that Pl4CL1 and Pl4CL2 fell into angiosperm Class II and Class I, respectively. Through in vitro biochemical assays, both Pl4CLs were found to have the capacity to utilize 4-coumarate and trans-cinnamate as substrates, while neither of them could convert sinapate. Pl4CL2 had a broader substrate specificity than Pl4CL1. The affinity of Pl4CL1 for 4-coumarate was 2.6-fold higher than that of Pl4CL2 (with the Km values of 3.5 µM and 9.1 µM, respectively). Combining the dataset including gene expression profiles, metabolites measurements, and biochemical properties, our results indicated that Pl4CL1, just as other angiosperm Class II 4CLs, might play a role in isoflavone biosynthesis in P. lobata, while Pl4CL2 belongs to angiosperm Class I, and may function as a housekeeping enzyme concerning lignification.

Bioleaching of chalcopyrite and bornite in the presence of Acidithiobacillus ferrooxidans was carried out to investigate the influences between each other during bioleaching. Bioleaching results indicated that bornite accelerated the dissolution of chalcopyrite, and chalcopyrite also accelerated the dissolution of bornite, it could be described as a synergistic effect during bioleaching, this synergistic effect might be attributed to the galvanic effect between chalcopyrite and bornite, and to the relatively low solution potential as the addition of bornite. Significantly amount of elemental sulfur and jarosite formed on the minerals surface might be the main passivation film inhibiting the further dissolution, and the amount of elemental sulfur significantly increased with the addition of bornite. Results of electrochemical measurements indicated that the oxidation and reduction mechanisms of chalcopyrite and bornite were similar, the addition of bornite or chalcopyrite did not change the oxidative and reductive mechanisms, but increased the oxidation rate.

Background As the main medicinal powder for drawing out pus and removing necrotic tissue in external therapies of traditional Chinese surgery, Sheng Powder has made great contributions to the treatment of inflammatory wounds and has the unique bactericidal and decay-discharging function that can not be replaced by antibiotics. However, Sheng Powder has toxicity because it contains mercury. So far, there is no clinical research on the standards of dose and usage of Sheng Powder and there is a lack of objective and quantitative criteria for operating standards and monitoring of toxicity and side effects. Therefore, the authors choose Jiuyi Powder, one of the most commonly used Sheng Powder, to evaluate the safety of its external use, and form a standardization program for clinical implementation. Methods and design This study is a nonrandomized, nonblinded, self-controlled case study. There will be two key stages in the study. In stage one, 10 patients with plasma cell mastitis will be enrolled. The patients will receive continuous external application of Jiuyi Powder with a fixed dose (160 mg/d). Blood mercury and urine mercury levels will be dynamically tested at different time intervals, and the observation of pharmacokinetic parameters will be conducted after Jiuyi Powder has been absorbed by the surface of the wound. In stage two, 30 patients with each of the four conditions including postoperative wounds of head or facial surgeries, plasma cell mastitis, anal fistula and chronic absorption ulcer of the shank will be enrolled, respectively. According to the dose of 1.5 mg/cm(2), Jiuyi Powder will be externally applied to the wound surface for 14 d. On the basis of the first-phase study, the test time will be chosen and the toxicity outcome will be detected to evaluate the safety of external application of Jiuyi Powder and to establish recommendations for standardized clinical use. Discussion The purpose of this study is to evaluate the safety of the external application of Jiuyi Powder through a two-stage study. The pharmacokinetic parameters of external application of Jiuyi Powder at the clinical dose range, the changes in blood and urinary mercury levels and related safety indexes will be observed on different wounds located in different positions externally. The evaluation of whether Jiuyi Powder could be a routine medication for drawing out pus and removing necrotic tissue in inflammatory and refractory wounds will be stated. Trial registration number ChiCTR-TNC-11001366.

Recently, accidents of collision between over‐high trucks and bridge superstructures happen frequently, which threaten the safety of bridges and city traffic seriously. However, the research on this problem is still very lack in China. Based on the high‐precision finite element (FE) simulation, this paper discusses the mechanism and damage modes of bridge superstructures impacted by over‐high trucks. The influences of different bridges and different trucks are discussed.

The bioleaching of chalcopyrite in shake flasks was investigated by using pure Acidithiobacillus ferrooxidans and mixed culture isolated from the acid mine drainage in Yushui and Dabaoshan Copper Mine in China, marked as YS and DB, respectively. The mixed culture consisted mainly of Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans, and Leptospirillum spp. (Leptospirillum ferriphilum and Leptospirillum ferrooxians). The results show that the mixed culture is more efficient than the pure Acidithiobacillus ferrooxidans because of the presence of the sulfur-oxidizing cultures that positively increase the dissolution rate and the recovery of copper from chalcopyrite. The pH value decreases with the decrease of chalcopyrite leaching rate, because of the formation of jarosite as a passivation layer on the mineral surface during bioleaching. In the bioleaching using the mixed culture, low pH is got from the sulfur oxidizing inhibiting, the formation of jarosite. The copper extraction reaches 46.27% in mixed culture and 30.37% in pure Acidithiobacillus ferrooxidans after leaching for 75 d.