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Py-FeO2, Py-FeOOH and ε-FeOOH are important components of mantle and core-mantle boundary. Their physical evolution characteristics at high temperature and high pressure are important for understanding the composition, structure and dynamic process of mantle. The crystal structures and elastic properties of Py-FeO2 and Py-FeOOH at 0-350 GPa and ε-FeOOH at 0-170 GPa were calculated by first principles in this study. The Py-FeO2 and Py-FeOOH belong to the cubic crystal system, their lattice constants decrease gradually with increasing pressure. The ε-FeOOH belongs to orthorhombic crystal system, and its lattice constants decrease with increasing pressure, however, a and b axes bump up at 33 GPa, while c axis swoop at 33 GPa. The cell densities of Py-FeO2, Py-FeOOH and ε-FeOOH increase with pressure, and the relative cell density among these three phases is Py-FeO2 > Py-FeOOH > ε-FeOOH. The bulk moduli of Py-FeO2, Py-FeOOH and ε-FeOOH increase linearly with pressure, and the shear moduli of Py-FeO2 and Py-FeOOH increase linearly with pressure, but the shear modulus of ε-FeOOH mutates at 33 GPa. Py-FeO2 has the highest bulk modulus, and Py-FeOOH and ε-FeOOH have almost the same bulk modulus at high pressures. In addition, Py-FeO2 has the largest shear modulus, and ε-FeOOH has the smallest shear modulus. The compression wave velocities of Py-FeO2, Py-FeOOH and ε-FeOOH decrease gradually with the increasing pressure, while the shear wave velocities of Py-FeO2 increase gradually with the increasing pressure. The shear wave velocity of Py-FeOOH decreases with the increasing depth in the range of 0-2 000 km, and the variation is small in the range of 2 000-6 000 km (5.8 km/s < vs < 6.0 km/s). The shear wave velocities of ε-FeOOH mutate at 33 GPa (about 900 km depth). The wave velocity of ε-FeOOH is the lowest, while that of Py-FeO2 is the highest. Based on comprehensive theoretical calculations, it is found that Py-FeO2 and Py-FeOOH have the high density and low wave velocity characteristics, which are consistent with the properties of the mantle ultra-low velocity zone (ULVZs). Py-FeO2 and Py-FeOOH may enrich and sink to the core-mantle boundary after formation, becoming the source of the ULVZs. The hydrogen bond symmetry of ε-FeOOH under 33 GPa may affect the crystal structure of ε-FeOOH, the atomic interactions of ε-FeOOH, and then the elastic properties and seismic wave velocity of ε-FeOOH. [ABSTRACT FROM AUTHOR]

Objective This study aimed to evaluate the color stability of tetracycline teeth restored with ceramic veneers of different thicknesses combined with different resin cement systems after aging. Methods Twenty patients with tetracycline teeth, including two maxillary central incisors, were selected clinically. The patients were randomly divided into four groups and restored with 0.5 and 0.75 mm ceramic veneers by using a veneer adhesive system, either with lightcured or dual-cured reaction. The color difference (ΔE) values after cementation and 1, 6, 12, and 24 months of use were obtained by quantification of L*, a*, and b* values with a colorimeter. The results were analyzed statistically with twoway ANOVA and Student's t test. Results The ΔE values of ceramic veneers detected after aging were less than 2.25. The 0.5 mm groups exhibited greater color change than the 0.75 mm-thick veneers (P<0.05). No significant difference was found on the color change of dual- or light-cured resin cements. Conclusion Resin cements and veneer thickness influence the color of ceramic veneers after aging. Cementation of veneers with either dual- or light-cured resin cements does not affect the long-term color stability of tetracycline teeth differently. [ABSTRACT FROM AUTHOR]

The thiourea-intercalated kaolinite (TlJ-Kaol) was prepared by a three-step reaction and then was incorporated into polypropylene (PP) to prepare the flame-retardant compounds by melt blending. The flammable characteristics and mechanical properties were evaluated by limiting oxygen index, cone calorimetry and universal test machine. The results indicated that the peak heat release rate of the composite containing 1.5 wt% of TU-Kaol decreased significantly from 1474kW/m² to 1100 kW/m² compared to pure PP, whereas their tensile strength increased from 35.3 MPa to 39.8 MPa. [ABSTRACT FROM AUTHOR]

Circular RNAs (circRNAs) are a new class of non-coding RNAs, which have been confirmed to regulate insect gene expression and immune response through multiple manners such as competing endogenous RNA (ceRNA) regulatory network. Currently, function of circRNA in honey bee immune response remains unclear. In this study, PCR and Sanger sequencing were performed to validate the back splicing (BS) site of ame&#95;circ&#95;000115 (in short ac115). RT-qPCR was used to detect the expression profile of ac115 in larval guts of Apis mellifera ligustica stressed by Ascosphaera apis . Dual-luciferase reporter gene assay was conducted to verify the binding relationship between ac115 and ame-miR-13b. Interference of ac115 in larval guts was carried out by feeding specific siRNA, followed by determination of the effect of ac115 interference on expression of six genes relevant to host immune response. The results confirmed the existence of BS site within ac115. Compared with the un-inoculated group, the expression of ac115 in 4-day-old larval gut of the A . apis -inoculated group was up-regulated with extreme significance ( P < 0.000 1), while that in 5- and 6-day-old larval guts were significantly up-regulated ( P < 0.05). The brightness of specific band for ac115 in 4-, 5- and 6-day-old larval guts of the siRNA-circ&#95;000115-fed group gradually became weak, whereas that of the siRNA-scrambl-fed group was pretty high without obvious variation. Compared with that of the siRNA-scramble-fed group, the expression of ac115 in 4-day-old larval gut of the siRNA-circ&#95;000115-fed group was significantly down-regulated ( P < 0.05), whereas that of the 5- and 6-day-old larval guts were down-regulated with extreme significance ( P < 0.001). Ame-miR-13b was truly existed and expressed in A . m . ligustica larval guts, and there was true binding relationship between ac115 and ame-miR-13b. Compared with that of the siRNA-scramble-fed group, the expression of antimicrobial peptide genes hymenoptaecin and abaecin in 6-day-old larval gut of the siRNA-circ&#95;000115-fed group was significantly up-regulated ( P < 0.05), while that of ecdysone receptor ( Ecr ) was down-regulated with extreme significance ( P < 0.01). These results indicate that ac115 is truly expressed in A . m . ligustica larval guts, BS site truly exists within ac115, and effective interference of ac115 in A . m . ligustica larval guts can be achieved via feeding siRNA. Moreover, ac115 potentially regulates Ecr expression through adsorption of ame-miR-13b and expression of hymenoptaecin and abaecin using a non-ceRNA manner, further participating in host stress-response.