As an alternative for depleting fossil fuel energy, hydrogen economy desires low-cost and efficient hydrogen production from water splitting. In order to explore a cheap, abundant, active, and durable catalyst for the electrocatalytic hydrogen evolution reaction (HER), two-dimensional (2D) ceria nanosheets are produced through a thermal decomposition exfoliation method from CeCO 3 OH with a layer-stacked structure. The additional cobalt dopant promotes formation of oxygen vacancies in ceria nanosheets and, in turn, optimizes hydrogen binding/water dissociation and increases the active sites. As a result, the 2D Codoped CeO 2 nanosheets exhibit an excellent catalytic performance in alkaline HER such that the overpotential is as low as 132 and 215 mV to deliver a high current density of 100 and 500 mA cm −2 , respectively, outperforming Pt. Such 2D Co-doped CeO 2 nanosheets are also durable HER electrocatalysts, as the activity loss during an extended period of operation is nearly negligible.
The utilization of nonprecious metal electrocatalysts for water-splitting may be the ultimate solution for sustainable and clean hydrogen energy. MXene, an emerging two-dimensional material, exhibits many unique properties such as possible metal-like conductivity, hydrophilic surface, and rich chemistry, rendering a group of promising catalysts and catalyst support materials. In this study, exfoliated Ti3C2 MXenes serve as a substrate to perpendicularly grow uniform mesoporous NiCoP nanosheets through an in situ interface-growth strategy and subsequent phosphorization. The obtained Ti3C2@mNiCoP materials with a stable hierarchical sandwich structure possess excellent conductivity, large surface area, and uniform mesopores with high pore volume. With these beneficial properties, the Ti3C2@mNiCoP material exhibits superior overall water-splitting performance compared with that of its building-block counterparts, matching the state-of-the-art water-splitting electrocatalysts.
Hydrogen economy is one of the most promising candidates to replace the current energy system on depleting fossil fuels. As a clean and sustainable way to produce hydrogen, electrocatalytic water splitting attracts ever-increasing interest from the research community. Although the wide application of platinum group metal (PGM) catalysts is limited because of the scarcity and high cost toward hydrogen evolution reaction (HER), the non-PGM electrocatalysts usually suffer from unsatisfactory activity and poor durability. In this work, we report an active and durable V-doped Ni5P4 electrocatalyst that can be used for all-pH HER. Particularly, V–Ni5P4 has an HER activity that is comparable to that of Pt in preferred alkaline media, with overpotentials as low as 13 mV and 295 mV at current densities of 10 and 1000 mA cm–2, respectively. The low-cost V–Ni5P4 that enables ultrahigh current density (i.e., at the level of A cm–2) would be of great interest to the hydrogen production industry.
Many differences exist between human immature and mature natural killer (NK) cells, but their respective molecular signatures and transcriptional regulators are relatively unknown. To gain new insights into the diversity and developmental regulation of human NK cells, we used data from high-resolution microarrays with independent verification to describe a comprehensive comparative analysis between immature decidual NK (idNK) cells with a Eur. J. Immunol. 2014. 44: 2771-2784 activity [6,7]. Our previous work showed that most dNK cells belong to the CD27 − CD11b − subset, which has an immature phenotype, displays developmental potential in response to IL-15, and increases cytotoxic potential in response to insulin-like growth factor 1 (IGF-1) [8,9]. Several exogenous cytokines are involved in NK-cell development and function, including IL-2, IL-15, and IL-21, and novel endogenous cytokines have more recently been found, including bone morphogenetic protein 4 (BMP4) and IGF-1 [9][10][11]. Although many transcription factors (TFs) have been identified to affect NK-cell differentiation or function in mice, including ID2, NFIL3 (E4BP4), EOMES, ETS-1, and T-bet, little is known about human NK-cell transcriptional regulators [12][13][14]. Since the molecular signature of NK cells has been well-described in mice [15], we sought to compare the results from mouse models to humans to see if developmental mechanisms are conserved.Using human whole-genome microarray data sets with subsequent verification, we provide novel molecular descriptions for human immature and mature NK cells; most importantly, our findings offer new insights into the transcriptional regulators that govern NK-cell development and function. Our study thus provides a valuable resource for further investigations into NK-cell biology. Results idNK cells exhibit immature characteristics compared with mpNK cellsNK cells in the peripheral blood account for a small fraction of total lymphocytes (ß10%) and are composed of two different subsets: the predominant CD56 dim CD16 + mature subset (ß95%) and the much smaller CD56 bright CD16 − immature subset (ß5%).In contrast, NK cells are the dominant lymphocyte in the decidua during normal pregnancy, comprising up to ß70% of the total lymphocytes and approximately 90% of dNK cells were of the CD56 bright CD16 − immature phenotype [6,16] (Fig. 1A and B, and Supporting Information Fig. 1A and C). T-bet regulates the terminal maturation and function of murine NK cells during the final stage of development [17]. ID2 is expressed in NK-cell progenitors and regulates their early developmental processes [13,18]. To further confirm that dNK cells are more immature than pNK cells, we analyzed T-bet and ID2 expression. Interestingly, we found that dNK cells were mostly T-bet − , while >90% of the pNK cells were T-bet + ( Fig. 1A and B). Additionally, western blot analysis showed that ID2 was exclusively expressed by dNK cells (Fig. 1C). Furthermore, we detected many known cell-surface markers related to NK-cell maturation. C...
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