Graphene is a material with unique properties that can be exploited in electronics, catalysis, energy, and bio-related fields. Although, for maximal utilization of this material, high-quality graphene is required at both the growth process and after transfer of the graphene film to the application-compatible substrate. Chemical vapor deposition (CVD) is an important method for growing high-quality graphene on non-technological substrates (as, metal substrates, e.g., copper foil). Thus, there are also considerable efforts toward the efficient and non-damaging transfer of quality of graphene on to technologically relevant materials and systems. In this review article, a range of graphene current transfer techniques are reviewed from the standpoint of their impact on contamination control and structural integrity preservation of the as-produced graphene. In addition, their scalability, cost- and time-effectiveness are discussed. We summarize with a perspective on the transfer challenges, alternative options and future developments toward graphene technology.
The American Society for Histocompatibility and Immunogenetics HLA common and well‐documented (CWD) catalog, CWD 2.0.0 catalog and European Federation for Immunogenetics (EFI) CWD catalog have been published, which are useful for improving the accuracy of HLA genotyping in laboratories. Here, we studied the Chinese HLA CWD catalog. A total of 812 211 unrelated volunteer donors from the China Marrow Donor Program (CMDP) were analyzed. Six hundred seventy‐six alleles at the HLA‐A, ‐B, ‐C, ‐DRB1, and ‐DQB1 loci were defined as CWD alleles in the Chinese population, including 159 common and 517 well‐documented alleles. The distribution of HLA alleles in the Chinese CWD catalog is different from that in the EFI CWD catalog. Thirty‐two percent (215/676) of CWD alleles in the Chinese CWD catalog are shared with those in the EFI CWD catalog. Fifty‐six percent (380/676) of alleles in the Chinese CWD catalog are not found in the EFI CWD catalog, while 655 alleles in the EFI CWD catalog are neither common nor well‐documented alleles in the Chinese CWD catalog. The Chinese CWD catalog described in this study may help to improve high‐resolution histocompatibility testing for CMDP‐accredited laboratories in China. However, to accommodate an increasing number of HLA alleles, this Chinese CWD catalog should be regularly updated.
The electroreduction of carbon dioxide (CO2RR) to CH4 stands as one of the promising paths for resourceful CO2 utilization in meeting the imminent “carbon‐neutral” goal of the near future. Yet, limited success has been witnessed in the development of high‐efficiency catalysts imparting satisfactory methane selectivity at a commercially viable current density. Herein, a unique category of CO2RR catalysts is fabricated with the yolk–shell nanocell structure, comprising an Ag core and a Cu2O shell that resembles the tandem nanoreactor. By fixing the Ag core and tuning the Cu2O envelope size, the CO flux arriving at the oxide‐derived Cu shell can be regulated, which further modulates the *CO coverage and *H adsorption at the Cu surface, consequently steering the CO2RR pathway. Density functional theory simulations show that lower CO coverage favors methane formation via stabilizing the intermediate *CHO. As a result, the best catalyst in the flow cell shows a high CH4 Faraday efficiency of 74 ± 2% and partial current density of 178 ± 5 mA cm−2 at −1.2 VRHE, ranking above the state‐of‐the‐art catalysts reported today for methane production. These findings mark the significance of precision synthesis in tailoring the catalyst geometry for achieving desired CO2RR performance.
SOX2 is a key regulator of multiple types of stem cells, especially embryonic stem cells (ESCs) and neural progenitor cells (NPCs).Understanding the mechanism underlying the function of SOX2 is of great importance for realizing the full potential of ESCs and NPCs. Here, through genome-wide comparative studies, we show that SOX2 executes its distinct functions in human ESCs (hESCs) and hESC-derived NPCs (hNPCs) through cell type-and stage-dependent transcription programs. Importantly, SOX2 suppresses non-neural lineages in hESCs and regulates neurogenesis from hNPCs by inhibiting canonical Wnt signaling. In hESCs, SOX2 achieves such inhibition by direct transcriptional regulation of important Wnt signaling modulators, WLS and SFRP2. Moreover, SOX2 ensures pluripotent epigenetic landscapes via interacting with histone variant H2A.Z and recruiting polycomb repressor complex 2 to poise developmental genes in hESCs. Together, our results advance our understanding of the mechanism by which cell type-specific transcription factors control lineage-specific gene expression programs and specify cell fate.
Limited core transcription factors and transcriptional cofactors have been shown to govern embryonic stem cell (ESC) transcriptional circuitry and pluripotency, but the molecular interactions between the core transcription factors and cofactors remains ill defined. Here, we analyzed the protein-protein interactions between Oct4, Sox2, Klf4, and Myc (abbreviated as OSKM) and a large panel of cofactors. The data reveal both specific and common interactions between OSKM and cofactors. We found that among the SET1/MLL family H3K4 methyltransferases, Set1a specifically interacts with Oct4 and this interaction is independent of Wdr5. Set1a is recruited to and required for H3K4 methylation at the Oct4 target gene promoters and transcriptional activation of Oct4 target genes in ESCs, and consistently Set1a is required for ESC maintenance and induced pluripotent stem cell generation. Gene expression profiling and chromatin immunoprecipitation-seq analyses demonstrate the broad involvement of Set1a in Oct4 transcription circuitry and strong enrichment at TSS sites. Gene knockout study demonstrates that Set1a is not only required for mouse early embryonic development but also for the generation of Oct4-positive inner cell mass. Together our study provides valuable information on the molecular interactions between OSKM and cofactors and molecular mechanisms for the functional importance of Set1a in ESCs and early development. STEM CELLS 2016;34:565-580
SIGNIFICANCE STATEMENTIn this study we demonstrated that Set1a specifically interacts with Oct4 and this interaction is independent of Wdr5. Set1a is critically important for ESC transcriptional circuitry controlled by Oct4 and is required for ESC self-renewal and pluripotency as well as efficient induction of pluripotent stem cells. Furthermore, Set1a is required for mouse early embryonic development and strikingly the generation of Oct4-positve inner cell mass.
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