An efficient utilization of chromium-containing vanadium tailings: Extraction of chromium by soda roasting-water leaching and preparation of chromium oxide.

Chromium-containing vanadium tailings (CCVT), an industrial waste, were utilized to extract chromium efficiently by soda roasting-water leaching process and for the preparation of highly pure chromium oxide. The effect of extraction of chromium under different roasting and leaching conditions were analyzed using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The maximum chromium extraction rate of 91.51% was obtained when soda (Na2CO3) and CCVT were mixed in a molar ratio (n (Na2CO3)/n (Cr2O3)) of 8, roasted at 900 °C and maintained for 120 min. Then, the roasted product was leached in water at 60 °C for 60 min with a liquid-solid mass ratio (L/S) of 10. During soda roasting, the chromium-containing phase (Fe0.6Cr0.4)2O3 combines with Na2CO3 to form Na2CrO4, which was then transferred into the leaching liquid, post water leaching. The by-products such as NaFeTiO4, Na2CaSiO4, and Na0.68Fe0.68Si0.32O2 were left in the leaching residue which was called chromium tailings (CT). 87.40% chromium oxide was recovered from the unpurified leaching liquid after reduction and precipitation by adding Na2S, followed by roasting the deposit. This process not only relieved the potential threat of the industrial waste CCVT to the environment but also realized the recovery of the valuable element chromium.

Arabidopsis MAPKKK18 positively regulates drought stress resistance via downstream MAPKK3.

Mitogen-activated protein kinase (MAPK) cascades are conserved and vital signaling components in the responses to various ambient stresses. Here, we report the identification of MAPKKK18, a drought resistance associated MAPK kinase kinase in Arabidopsis. The mapkkk18 knockout mutants displayed hypersensitivity to drought stress, whereas overaccumulation of MAPKKK18 in transgenic Arabidopsis plants significantly enhanced the resistance to drought. Expression pattern analysis revealed that the inducible expression of MAPKKK18 by osmotic stress was ABA and the canonical ABA signaling pathway dependent. Furthermore, MAPKKK18 mainly exerted its regulatory roles via downstream MAPKK3. These findings uncovered important roles for MAPKKK18 in drought resistance and expanded our understanding of the MAPK pathways in modulating abiotic stress responses.

An efficient utilization of high chromium vanadium slag: Extraction of vanadium based on manganese carbonate roasting and detoxification processing of chromium-containing tailings.

A novelty roasting method with manganese carbonate (MnCO3) as additive was carried out to separate and recover vanadium from high chromium vanadium slag (HCVS) efficiently. Vanadium tailings containing chromium was detoxified by carbon reduction and smelting to form Fe-Cr alloy. The whole process of HCVS utilization was analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). 89.37% of vanadium and 0.10% of chromium was leached when MnCO3 was added to HCVS at the mole ratio of MnO in MnCO3 and V2O3 in HCVS (n(MnO)/n(V2O3)) of 2.0 and heating at 850 °C for 120 min, then leached under the pH value at 2.5. 99.19% of vanadium was precipitated by (NH4)2SO4 and V2O5 with a purity of 99.28% was prepared. More than 84% of manganese addictive was recovered after manganese precipitation by carbonization with CO2 discharged from manganese carbonate roasting, which could be used as the raw addictive for roasting. The wastewater after vanadium and manganese extraction could be circulated as leaching medium. Three circulation routes realized the closed-circuit circulation of raw materials and products, saving the production costs and avoiding the environmental pollution. Fe-Cr alloy with 67.35% of Fe and 13.28% of Cr was obtained from chromium-containing vanadium tailings, which could be returned to the steelmaking process.

Effect of propofol on mitochondrial ATP content and ATPase activity in hippocampus of rats with cerebral ischemia-reperfusion injury.

OBJECTIVE: Study on the influence of the cerebral Ischemia-reperfusion Injury (IRI) on mitochondrial adenosine triphosphate (ATP) content and ATPase activity in hippocampus of rats, as well as the protective effect of propofol on IRI in rats. METHODS: A total of 40 male SD rats were randomly divided into 5 groups: sham operation group (Group A), ischemia reperfusion control group (Group B) and ischemic reperfusion with propofol pretreatment group (C group). Group C was further divided into three sub groups according to the different doses of propofol: Group C1 (50 mg/kg), Group C2 (100 mg/kg) and Group C3 (150 mg/kg). The rats from Groups B and C were applied for the IRI model preparation by blockage of the blood flow in arteria carotis communis. For the Groups A, arteria carotis communis were separated without blockage of the blood flow. Before preparation of IRI model for rats in Group C, different doses of propofol were intraperitoneally injected into the rats. For rats in Groups A and B, only saline solution with same volume was intraperitoneally injected at the same time. The ultra-structures of mitochondria in hippocampus of rats were observed under transmission electron microscope, and the mitochondrial degeneration rate was counted. The contents of ATP were determined by HPLC and the ATPase activity was characterized by ATPase activity assay kit. RESULTS: (1) Mitochondria in the hippocampus from Groups B and C showed different degrees of ultrastructural damage and more significant mitochondrial degeneration than those from Group A. The degree of damage and the rate of degeneration were in the order of B > C1 > C2 > C3 and the difference was statistically significant (P < 0.01). (2) The contents of ATP and the ATPase activity in hippocampus from Groups B and C were significantly lower than those of Group A, while these indices from Group C were significantly higher than those in the B group, and the sequence was C3 > C2 > C1, indicating that the ATP content and ATPase activity were significantly correlated with the dose of propofol, and the difference was statistically significant (P < 0.05). CONCLUSION: In summary, the contents of ATP and ATPase activity in hippocampus of rats can be decreased by cerebral IRI. The structure and function of the impaired mitochondria in IRI rats could be significantly improved by propofol, and the improvement effect is related to the dose of propofol.