ABSTRACT
In order to enhance the degree of binding reaction of TiO2 in titanium-containing ceramic glazes and prevent the reaction of its transformation into rutile to eliminate the yellowing phenomenon of the glaze surface, an apatite-TiO2 composite opacifier (ATO) was prepared through the mechanical grinding of hydroxyapatite and anatase TiO2. The properties, opacification mechanism, and yellowing inhibition of the prepared ceramic glazes were studied. The results show that the ATO is characterized by a uniform coating of TiO2 on the surface of the apatite and the formation of close chemical bonding between the apatite and TiO2. The ceramic glaze surface when using an ATO has a white appearance and excellent opacification performance. When an ATO was used, the L*, a*, and b* values of the glaze were 89.99, -0.85, and 3.37, respectively, which were comparable to those of a ZrSiO4 glaze (L*, a*, and b* were 88.24, -0.02, and 2.29, respectively). The opacification of the glaze was slightly lower than that of the TiO2 glaze (L* value was 92.13), but the appearance changed from yellow to the white of the TiO2 glaze (b* value was 9.18). The ceramic glaze layer when using an ATO mainly consists of titanite, glass phase, and a small amount of quartz, and the opacification mechanism is the crystallization of the generated titanite. ATOs can play an active role in solving the critical problem that arises when TiO2 replaces ZrSiO4 as an opacifier.
ABSTRACT
Synthetic perovskite powder (SPP) was synthesized by the solid-phase method using metatitanic acid (TiO2ïnH2O) and calcium carbonate (CaCO3) as raw materials, and its structure, morphology, pigment properties and application in architectural coatings were studied. When TiO2ïnH2O and CaCO3 were mixed and ground at a molar ratio of TiO2: CaO = 1:1, and then calcined at 900-1100 °C, SPP with a single perovskite phase was obtained. The characterization results displayed that the unit particle size of SPP was 50-150 nm, the aggregate size was 1-2 µm, and its particles were well dispersed. The SPP also had a whiteness of 90.5%, and an oil absorption of 35.03 g/100g. The hiding power of SPP was 24.02 g/m2, which was 81.6% of pure TiO2 hiding power (19.60 g/m2). When adding SPP to prepare a building exterior wall coating, the contrast ratio of the coating film was 0.92, which met the requirements of the Chinese national standard GB/T 9755-2014 and was equivalent to adding rutile titanium dioxide. Thus, perovskite synthesized from TiO2ïnH2O and CaCO3 by the solid-phase method significantly improved the pigment properties of TiO2 in the same proportion.
ABSTRACT
We established the mouse model of fluoride (68â¯mgâ¯F ion/L deionized water) exposure for 90 days, 120 days and 150 days, and applied diverse methods as behavioral models of anxiety and depression, and analyzed the levels of the anxiety- and depression-like related genes like BDNF1, BDNF4, 5-HT1A, VGLUT, GAD67, and VGAT in the mouse hippocampus. In the mice exposed to NaF for 120 days, compared to the control group, chalky opacity was observed on the enamel of teeth; the results of anxiety-like behavior, like elevated zero maze, light/dark exploration test, novel object recognition test and emergence test were significantly altered, however in the mice exposed for 150 days, only the elevated zero maze and emergence test were significantly altered. Also, the results of depression-like behavior were significantly altered in the 120 days treated mice. Exposure to NaF for 120 days significantly decreased the mRNA expression levels of the BDNF4 with a concomitant increase in the 5-HT1A compared to the control mice. Especially the mRNA expression levels of GAD67 and VGAT were significantly decreased in all the three NaF treated groups. However, no significant changes were observed in the mRNA expression levels of the VGLUT compared to the control mice. In summary, we speculated that fluoride exposure had adverse effects on nervous system, inducing an imbalance between excitation and inhibition, which resulted in abnormal behavior and depression.
