Whole‑genome transcriptome and DNA methylation dynamics of pre‑implantation embryos reveal progression of embryonic genome activation in buffaloes

Background During mammalian pre-implantation embryonic development(PED),the process of maternal-to-zygote transition(MZT)is well orchestrated by epigenetic modification and gene sequential expression,and it is related to the embryonic genome activation(EGA).During MZT,the embryos are sensitive to the environment and easy to arrest at this stage in vitro.However,the timing and regulation mechanism of EGA in buffaloes remain obscure.Results Buffalo pre-implantation embryos were subjected to trace cell based RNA-seq and whole-genome bisulfite sequencing(WGBS)to draw landscapes of transcription and DNA-methylation.Four typical developmental steps were classified during buffalo PED.Buffalo major EGA was identified at the 16-cell stage by the comprehensive analy-sis of gene expression and DNA methylation dynamics.By weighted gene co-expression network analysis,stage-spe-cific modules were identified during buffalo maternal-to-zygotic transition,and key signaling pathways and biological process events were further revealed.Programmed and continuous activation of these pathways was necessary for success of buffalo EGA.In addition,the hub gene,CDK1,was identified to play a critical role in buffalo EGA.Conclusions Our study provides a landscape of transcription and DNA methylation in buffalo PED and reveals deeply the molecular mechanism of the buffalo EGA and genetic programming during buffalo MZT.It will lay a foundation for improving the in vitro development of buffalo embryos.

Highly efficient and stable perovskite solar cells with strong hydrophobic barrier via introducing poly(vinylidene fluoride)additive

Perovskite solar cells(PSCs)have become the promising next-generation photovoltaic devices due to their excellent photoelectric performances,and the power conversion efficiencies(PCEs)have experienced unprecedented rapid increase in recent years.However,to realize the practical application of PSCs,high performance and long-term stability are required and the preparation of high-quality perovskite film is the key.Herein,we adopt a simple and effective method to prepare high-quality perovskite films by introducing the poly(vinylidene fluoride)(PVDF)polymer additive with abundant hydrophobic F.As the growth template,the PVDF promotes the growth of perovskite crystal,improves the crystallinity and film morphology,thus reducing defect density and inhibiting carrier recombination.The results show that the photovoltaic performances of the perovskite device with PVDF are meaningfully improved,and a high PCE of 21.42%is achieved with an improvement of 10.87%,More importantly,the PVDF-based perovskites display greatly enhanced humidity and heat stability due to the protection of strong hydrophobic barrier from F and PVDF long chain.Aging at 45%±5%relative humidity(RH)for 2400 h and 850 C for300 h,respectively,the unsealed PVDF devices can maintain over 90%of the initial PCE.It indicates that suitable polymer additives can improve the film quality to acquire high-performance and stable PSCs and lay a foundation to design new perovskite light absorption layer with different polymers for the further development of PSCs.

新型高稳定二维/三维钙钛矿材料:引入铵阳离子对钙钛矿太阳电池性能的影响（英文）

钙钛矿太阳电池因其快速增长的效率而引起了广泛关注,但不稳定性极大的影响了它的实际应用.这里,我们首次将小尺寸的NH_4^+引入三维钙钛矿中,制备了新型的二维/三维混合钙钛矿材料.特别地,与文献报道的二维钙钛矿不同的是,新型的二维/三维混合钙钛矿是首个显示光学性能红移和带隙减少的.当n=9时,电池显示出优越的光伏性能,效率达到了18.25%,且具有可忽略的迟滞.封装的电池在标准的AM 1.5G光照下放置1000小时后,效率没有明显降低.在高湿度条件下老化1000小时,未封装的电池保持了90%的初始效率.这些发现为发展新型钙钛矿材料提供了指导,有助于获得高效稳定的二维钙钛矿太阳电池.

温和溶液法制备三元硫化物Ag_8SnS_6作为吸光材料在薄膜太阳电池中的应用（英文）

吸光材料是薄膜太阳电池进一步应用的重要因素.三元硫化物Ag8SnS6(ATS)拥有诸多优秀的光电性质.然而,关于ATS在吸光材料方面的应用鲜有报道.因此,本文通过使用一种退火温度低于250°C的温和溶液法制备ATS吸光材料并将其应用于薄膜太阳电池.在优化之后,基于ATS的薄膜太阳电池展现出了具有潜力的光伏性能以及可再现的0.25%光电转化效率.更重要的是,基于ATS的器件展现出了卓越的长期稳定性,在超过1000小时的老化测试后器件仍然还有90%的初始效率.本研究不仅揭示了含量丰富、低毒且化学性质稳定的ATS作为吸光材料的潜力,也为薄膜太阳电池中新型吸光材料的研究提供了全新的视角.