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Copyright of Natural Gas Geoscience is the property of Natural Gas Geoscience and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chinese Journal of Inorganic Analytical Chemistry / Zhongguo Wuji Fenxi Huaxue is the property of Beijing Research Institute of Mining & Metallurgy Technology Group and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Aiming at the problem that it is difficult to recover valuable zinc from industrial solid wastes such as zinc oxide tailings and Grain slags, this paper prepares high-purity zinc oxide micro powder by using carbothermal reduction and oxidation method with local industrial zinc-containing solid wastes as raw materials. The thermodynamic process of the reaction between zinc silicate and carbon reduction in the zinc-containing slag was analyzed by a combination of thermodynamic calculations and experimental studies through HSC Chemistry. The effects of carbon allocation, roasting temperature, roasting time and CaF2 on zinc yield during zinc silicate reduction were discussed, and the results showed that the catalytic effect was most significant at 1000 ℃~1100 ℃ when CaF2 was used as a catalyst. The optimum process conditions were obtained: the zinc yield reached 97.44% at a temperature of 1100 °C, a holding time of 40 min, a carbon content of 20 wt% and a CaF2 addition of 5 wt%. Structural and compositional analyses of the volatilized product showed that the physical phase was hexagonal zinc oxide crystals with a particle size of 2~4 um and a purity of 99.47%. [ABSTRACT FROM AUTHOR]

In order to overcome the dilemma of insufficient effective sample number for subsurface microcrack depth in the lapping of brittle materials with fixed abrasives and achieve accurate prediction, a co-training SVR was used to construct the prediction model. The effects of different labeled training set partitioning methods on the mean square error of the test set were compared. Then the predictive performance of supervised learning PSO-SVR model was compared with that of the model. Finally, brittle materials such as microcrystalline glass and calcium fluoride, which were not included in the labeled training set, were taken as processing objects for lapping and angular polishing experiments to examine crack depth values. The examined subsurface microcrack depths of four groups were compared with the predicted values of the co-training SVR model. The results show that the co-training SVR model under the separate partitioning method has a smaller mean square error. Compared with the PSO-SVR model, the mean square error and the mean absolute percentage error of the co-training SVR model are reduced by 9% and 17%, respectively. The prediction error of the model for the four groups of verification experiments is between 1.2% and 13.8%. The above results show that the co-training SVR model can predict the subsurface microcrack depth accurately when lapping brittle materials with fixed abrasives. [ABSTRACT FROM AUTHOR]

This paper summarizes the sources, hazards and current disposal research status of calcium fluoride sludge, a typical sludge in photovoltaic industry, and analyzes the feasibility of various disposal methods, points out the advantages and disadvantages of each research technology, and points out that the corresponding disposal process can be selected according to the actual s让uation. In add让ion, the future development direction of the treatment and resource utilization of calcium fluoride sludge was evaluated, prospected and suggested. [ABSTRACT FROM AUTHOR]

Taking the stone coal vanadium mine in Shangnan County, Shaanxi Province as the research object, the vanadium extraction effects of direct acid leaching, oxidative acid leaching and activated acid leaching were studied, and the leaching law and activation leaching mechanism of vanadium-containing minerals during the acid leaching process were analyzed. The results show that: under the conditions of sulfuric acid concentration of 250 g/L, liquid-solid ratio of 5 mL/g, and temperature of 90°C, the leaching rate of vanadium is only 48.55% after leaching for 12 h; After acid leaching for 9 h, the leaching rate of vanadium increased to 61.42%; adding 9% calcium fluoride, only activating leaching for 6 h, the leaching rate of vanadium could reach 92.90%. Process mineralogy research shows that: in the activated acid leaching process, calcium fluoride reacts with sulfuric acid to generate hydrofluoric acid, which promotes the destruction of vanadium-containing mineral structure by sulfuric acid, and participates in the reaction of vanadium-containing mica, promoting the formation of vanadium-containing minerals. Leaching of vanadium in minerals; the leaching rates of vanadium in vanadium-containing mica, vanadium-titanium ore, limonite, and vanadium sulfide are 98.47%, 42.22%, 98.09%, and 89.70%, respectively, compared with oxidative acid leaching. 31.77, 26.90, 18.01, 89.70 percentage points compared with oxidative acid leaching, respectively. [ABSTRACT FROM AUTHOR]

The resistance of calcium fluoride crystals to γ-irradiation is one of the key properties for its application in space. In this paper, the effect of trace La impurities on the γ-irradiation induced color center of calcium fluoride crystals was reported. The calcium fluoride crystals with trace La impurities were studied by absorption spectroscopy and electron paramagnetic resonance (EPR). The results show that the irradiated calcium fluoride crystals produce multiple color center absorption bands, and the absorption band increases with the increase of irradiation dose and the concentration of La impurities. EPR confirms that the formation of this absorption band is caused by the F color center in the calcium fluoride crystal. The presence of La3+ affect the stability and spectral position of the F centers in calcium fluoride crystals. Possible mechanisms for the presence of La3+ and F centers in calcium fluoride crystals are proposed. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Test & Measurement Technology is the property of Publishing Center of North University of China and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of the Chinese Society of Rare Earths is the property of Editorial Department of Journal of the Chinese Society of Rare Earths and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Imaging Science & Photochemistry is the property of Imaging Science & Photochemistry Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chinese Journal of Inorganic Analytical Chemistry / Zhongguo Wuji Fenxi Huaxue is the property of Beijing Research Institute of Mining & Metallurgy Technology Group and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A silicon sensor auxiliary electrode was successfully synthesized by evenly coating CaF2+SiO2 powder on the surface of ZrO2(MgO) solid electrolyte and roasting at 1400 ℃ for 30 min in high purity Ar atmosphere. The effects of preparing conditions on the composition,crystal phase and morphology of the formed auxiliary electrode membrane after calcination were systematically investigated by X-ray diffraction,scanning electron microscopy and energy dispersive spectrometry. It is shown that SiO2 solid particles,CaO·MgO·2SiO2 solid solution and ZrSiO4 are the main components of the formed auxiliary electrode layer and no CaF2 exists in the layer. In addition,the influences of phase transformation on the film adhesive property and silicon sensor performance were also discussed. The as-prepared silicon sensor which is used to detect silicon content in molten iron at 1450 ℃ shows a better performance.When the silicon content ranges from 0.5% to 1.5% in liquid iron,the testing result based on this silicon sensor with a response time of 10 s and a steady time more than 20 s agrees well with the value based on the chemical analysis method.

Objective: To study the effect of excessive fluoride on calcium overload and apoptosis in cultured rat ameloblasts in vitro., Methods: Logarithmic-phase ameloblasts (HAT-7) were treated with 0, 0.4, 0.8, 1.6, 3.2, and 6.4 mmol · L(-1) sodium fluoride (NaF) solution. Cell activities were detected by using a Cell Counting Kit 8 (CCK-8) assay after 48 h of treatment. The effect of fluoride on cell apoptosis was analyzed by using flow cytometry. Excessive fluoride-induced calcium concentration and calreticulin expression changes in ameloblasts were detected by using laser scanning confocal microscopy, Western blot analysis, and real-time quantitative polymerase chain reaction., Results: NaF inhibited ameloblast activity at 1.6, 3.2, and 6.4 mmol · L(-1) (dose-dependent) after 48 h of induction. The Ca2+ fluorescence intensity of HAT-7 cells incubated with 1.6 and 3.2 mmol · L(-1) NaF was higher than that in the control group. The fluoride-induced early-stage apoptosis of ameloblasts after 48 h of induction and the early-stage apoptosis rate was positively correlated with fluoride concentration. Calreticulin mRNA expression in HAT-7 cells was higher than that in the control group after 48 h of incubation with 0.8, 1.2, and 1.6 mmol · L(-1) NaF., Conclusion: Excessive fluoride-induced calcium overload in ameloblasts and further caused endoplasmic reticulum stress-mediated apoptosis.

The present study was carried out on dental enamel to describe surface changes in the scanning electron microscope and crystallites changes in the high-resolution transmitted electron microscope as related to treatments of topical applied ion supplemented acidulated phosphate fluoride (APFI) gel and artificial caries agent demineralization in vitro, which imitated in vivo with pH- cycling condition. Our data suggest that topical application of APFI gel produce some CaF2 spheres on the surface of enamel and some fluoride-containing apatites in dental enamel. The latter are considered as result of F- and CaHPO4 or hydroxyapatites. The essence of chemical reactions are discussed. The results confirm that enamel treated with APFI gel becomes more resistant to artificial caries agent and electron radiation damage.