Microstructure and mechanical properties of Fe/NbC composite layer prepared by in-situ reaction

NbC ceramic surface-reinforced steel matrix composites were prepared by an in-situ reaction method at different temperatures(1,050℃,1,100℃and 1,150℃)for different times(1 h,2 h and 3 h).The phase constitution,microstructure and fracture morphology of NbC ceramic surface-reinforced steel matrix composites were analyzed by XRD,SEM and EDS,and the effects of the in-situ reaction temperature and time on the mechanical properties were systematically studied.The results indicate that the NbC reinforcement layer is formed through the reaction between Nb atoms and carbon atoms diffused from the steel matrix to the Nb plate.The thickness of this reinforcement layer increases as the reaction time prolongs.Additionally,an increase in reaction temperature results in a thicker reinforcement layer,although the rate of increase gradually decreases.The relationship among the thickness of the Nb C reinforcement layer,the reaction time and temperature was established by data fitting.The optimal tensile performance is achieved at 1,100℃for 1 h,with a tensile strength of 228 MPa.It is also found that the defects between the reinforcement layer and the steel matrix are related to reaction temperature.At 1,100℃,these defects are minimal.Fracture mostly occurs in the NbC reinforced layer of the composites,and the fracture mode is characterized by typical intergranular brittle fracture.

Extraction of vanadium from vanadium slag by high pressure oxidative acid leaching

To extract vanadium in an environment friendly manner, this study focuses on the process of leaching vanadium from vanadium slag by high pressure oxidative acid leaching. Characterizations of the raw slag, mineralogy transformation, and the form of leach residues were made by X-ray diffraction, scanning electron microscopy, and energy dispersive X-ray spectroscopy. The result shows that the vana-dium slag is composed of major phases of fayalite, titanomagnetite, and spinel. During the high pressure oxidative acid leaching process, the fayalite and spinel phases are gradually decomposed by sulfuric acid, causing the release of vanadium and iron in the solution. Meanwhile, unreacted silicon and titanium are enriched in the leach residues. With the initial concentration of sulfuric acid at 250 g·L^-1, a leaching tem-perature of 140℃, a leaching time of 50 min, a liquid-solid ratio of 10：1 mL·g^-1, and oxygen pressure at 0.2 MPa, the leaching rate of vana-dium reaches 97.69%.

Dopamine Agonists Exert Nurrl-inducing Effect in Peripheral Blood Mononuclear Cells of Patients with Parkinson＇s Disease

Background： Nurrl plays an essential role in the development, survival, and function maintenance ofmidbrain dopaminergic （DA） neurons, and it is a potential target for Parkinson＇s disease （PD）. Nurrl mRNA can be detected in peripheral blood mononuclear cells （PBMCs）, but whether there is any association of altered Nurrl expression in PBMC with the disease and DA drug treatments remains elusive. This study aimed to measure the Nurrl mRNA level in PBMC and evaluate the effect of Nurrl expression by DA agents in vivo and in vitro. Methods： The mRNA levels of Nurrl in PBMC of four subgroups of 362 PD patients and 193 healthy controls （HCs） using real-time polymerase chain reaction were measured. The nonparametric Mann-Whitney U-test and Kruskal-Wallis test were performed to evaluate the differences between PD and HC, as well as the subgroups of PD. Multivariate linear regression analysis was used to evaluate the independent association of Nurrl expression with Hoehn and Yahr scale, age, and drug treatments. Besides, the Nurrl expression in cultured PBMC was measured to determine whether DA agonist pramipexole affects its mRNA level. Results： The relative Nurrl mRNA levels in DA agonists treated subgroup were significant higher than those in recent-onset cases without any anti-PD treatments （de novo） （P 〈 0.001 ） and HC groups （P 〈 0.010）, respectively. Furthermore, the increase in Nurr I mRNA expression was seen in DA agonist and L-dopa group. Multivariate linear regression showed DA agonists, L-dopa, and DA agonists were independent predictors correlated with Nurrl mRNA expression level in PBMC. In vitlv, in the cultured PBMC treated with 10 μmol/L pramipexole, the Nurrl mRNA levels were significantly increased by 99.61%, 71.75%, 73.16% in 2, 4, and 8 h, respectively （P 〈 0.001 ）. Conclusions： DA agonists can induce Nurrl expression in PBMC, and such effect may contribute to DA agonists-mediated neuroprotection on DA neurons.

Pressure leaching of converter vanadium slag with waste titanium dioxide

The process of pressure leaching the converter vanadium slag with waste titanium dioxide without roasting was studied. Mineralogy analysis indicates that the con- verter vanadium slag contains mainly three mineral phases： magnetite, titanium magnetite, and silicate phase. Vana- dium is in combination with iron, titanium, manganese, aluminum, and silicon. The impacts of leaching tempera- ture, leaching time, stirring speed, liquid-to-solid ratio, and initial leaching agent concentration were investigated on the waste titanium dioxide leaching process. The results indi- cate that under the optimal conditions, the vanadium and the iron leaching rates are 96.85 % and 93.50 %, respectively, and the content of titanium is 12.6 % in the residue. The main mineral phases for the residues under the optimal operation conditions are quartz, ilmenite, anatase, and sili- cate phase, and the residues can be reused as the extraction of titanium raw materials for titanium dioxide production technology by the sulfate method.