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Establishment of the primordial follicle (PF) pool is pivotal for the female reproductive lifespan; however, the mechanism of primordial folliculogenesis is poorly understood. Here, the transcription factor SP1 was shown to be essential for PF formation in mice. Our results showed that SP1 is present in both oocytes and somatic cells during PF formation in the ovary. Knockdown of Sp1 expression, especially in pregranulosa cells, significantly suppressed nest breakdown, oocyte apoptosis, and PF formation, suggesting that SP1 expressed by somatic cells functions in the process of primordial folliculogenesis. We further demonstrated that SP1 governs the recruitment and maintenance of Forkhead box L2-positive (FOXL2+) pregranulosa cells using an Lgr5 -EGFP-IRES- Cre ERT2 (Lgr5 - KI) reporter mouse model and a FOXL2+ cell-specific knockdown model. At the molecular level, SP1 functioned mainly through manipulation of NOTCH2 expression by binding directly to the promoter of the Notch2 gene. Finally, consistent with the critical role of granulosa cells in follicle survival in vitro , massive loss of oocytes in Sp1 knockdown ovaries was evidenced before puberty after the ovaries were transplanted under the renal capsules. Conclusively, our results reveal that SP1 controls the establishment of the ovarian reserve by regulating pregranulosa cell development in the mammalian ovary. [ABSTRACT FROM AUTHOR]

Fe-Fe3C@C composites are successfully synthesized via a facile pyrolysis process. Experimental results indicate that Fe-Fe3C nanoparticles are closely parceled among amorphous carbon and exhibit a core–shell structure. The obtained materials display excellent microwave absorption performance with an optimal reflection loss of − 35.6 dB at 17.2 GHz, and an effective absorbing bandwidth of 4 GHz (from 12.4 to 16.4 GHz) with the coating thickness of 2 mm. The magnetic loss derived from Fe core and dielectric loss on carbon materials as well as a good impedance matching are believed to play decisive roles for this favorable microwave absorbing properties. The composites are considered to be good candidates for microwave absorption applications. [ABSTRACT FROM AUTHOR]

In recent literary writings of Liaoning Province, the novel "Daobingguo" is a "big one", and a good story about the local history and culture. As its writer, Teng Zhen-fu, in dialogues with the editor, told of his thoughts in writing the book, including its theme, characters, local culture, historical truth, artistic authenticity, rural history, realistic significance, and the training sessions for future writers in Liaoning Province. From the dialogues, it can be seen that Mr. Teng shoulders a strong responsibility and a sense of duty, showing his good will for the local culture and literary implication. Furthermore, he is confident in traditional Chinese culture and its role in modern society. [ABSTRACT FROM AUTHOR]

A novel class of high-entropy pyrochlore ceramics (HEPCs) with multiple heavy and light rare-earth elements at the A site were successfully synthesized via solid-state reaction. Both the XRD patterns and Raman spectroscopy demonstrated the single pyrochlore structure feature of seven kinds of HEPCs. Electron microscopic images revealed the typical morphology and the homogeneous distribution of all rare-earth elements. It can be concluded that the significance of configuration entropy in the HEPC system has promoted the tervalent lanthanide nuclides to form a single pyrochlore structure. This work is expected to provide guidance for the further design of high-entropy pyrochlore/fluorite ceramics. [ABSTRACT FROM AUTHOR]

Meiotic initiation of germ cells at 13.5 dpc (days post-coitus) indicates female sex determination in mice. Recent studies reveal that mesonephroi-derived retinoic acid (RA) is the key signal for induction of meiosis. However, whether the mesonephroi is dispensable for meiosis is unclear and the role of the ovary in this meiotic process remains to be clarified. This study provides data that RA derived from fetal ovaries is sufficient to induce germ cell meiosis in a fetal ovary culture system. When fetal ovaries were collected from 11.5 to 13.5 dpc fetuses, isolated and cultured in vitro, germ cells enter meiosis in the absence of mesonephroi. To exclude RA sourcing from mesonephroi, 11.5 dpc urogenital ridges (UGRs; mesonephroi and ovary complexes) were treated with diethylaminobenzaldehyde (DEAB) to block retinaldehyde dehydrogenase (RALDH) activity in the mesonephros and the ovary. Meiosis occurred when DEAB was withdrawn and the mesonephros was removed 2 days later. Furthermore, RALDH1, rather than RALDH2, serves as the major RA synthetase in UGRs from 12.5 to 15.5 dpc. DEAB treatment to the ovary alone was able to block germ cell meiotic entry. We also found that exogenously supplied RA dose-dependently reduced germ cell numbers in ovaries by accelerating the entry into meiosis. These results suggest that ovary-derived RA is responsible for meiosis initiation. J. Cell. Physiol. 228: 627-639, 2013. © 2012 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Carbide solid solutions show diverse oxidation behaviors at 1000–1400 °C in water vapor. (Ti,Nb,Ta,Hf,Zr)C and (Ti,Nb,Ta,Hf)C exhibit parabolic or near-parabolic oxidation kinetics, while the oxidations of (Ti,Nb,Ta) and (Ti,Nb)C are mainly controlled by linear oxidation kinetics. The oxidation kinetics of (Ti,Nb,Ta,Hf,Zr)C shows a tendency of transition from parabolic to linear oxidation rate law with increasing temperature. On the contrary, a tendency of transition from linear to parabolic rate law with increasing temperature was observed in (Ti,Nb)C, which exhibits the highest oxidation resistance at investigated temperatures. The presence of dense Nb-doped TiO 2 oxidation layer is responsible for the high oxidation resistance. • Compositional influence on oxidation behaviors of metal carbide solid solutions in 1000–1400 °C water vapor was investigated. • Diverse oxidation behaviors were observed for different carbide solutions. • Binary (Ti,Nb)C shows optimized oxidation resistance among all carbides solid solutions investigated. [ABSTRACT FROM AUTHOR]

The properties of rare-earth (RE) monosilicates can be regulated by solid solution engineering based on the mixture rule. The combination and number of RE principals are critical factors for better performances. In the present study, four single-phase equimolar multicomponent RE-monosilicate solid solutions including (Dy 1/3 Er 1/3 Yb 1/3) 2 SiO 5 , (Ho 1/3 Er 1/3 Yb 1/3) 2 SiO 5 , (Y 1/4 Er 1/4 Tm 1/4 Lu 1/4) 2 SiO 5 and (Dy 1/4 Er 1/4 Tm 1/4 Yb 1/4) 2 SiO 5 were synthesized by solid-state reaction and hot-pressing method. The microstructures, thermal and mechanical properties, and corrosion resistance to high-temperature water vapor were systematically investigated. Compared to the single-principal and ternary RE-monosilicates, the quaternary RE-monosilicates exhibited lower thermal conductivity of 1.32 Wm−1K−1 at 400 °C, matched thermal expansion coefficients (3.3 × 10−6/oC ∼ 5.8 × 10−6/oC from 200 °C to 1000 °C) with SiC, and much lower weight loss during water vapor corrosion. The results indicate that the increase of the RE element number can promote the grain growth, lower the thermal conductivity and thermal expansion coefficient, and enhance corrosion resistance. [ABSTRACT FROM AUTHOR]