Developing highly efficient hydrogen evolution reaction (HER) catalysts in alkaline media is considered significant and valuable for water splitting. Herein, it is demonstrated that surface reorganization engineering by oxygen plasma engraving on electocatalysts successfully realizes a dramatically enhanced alkaline HER activity. Taking CoP nanowire arrays grown on carbon cloth (denoted as CoP NWs/CC) as an example, the oxygen plasma engraving can trigger moderate CoOx species formation on the surface of the CoP NWs/CC, which is visually verified by the X‐ray absorption fine structure, high‐resolution transmission electron microscopy, and energy‐dispersive spectrometer (EDS) mapping. Benefiting from the moderate CoOx species formed on the surface, which can promote the water dissociation in alkaline HER, the surface reorganization of the CoP NWs/CC realizes almost fourfold enhanced alkaline HER activity and a 180 mV decreased overpotential at 100 mA cm−2, compared with the pristine ones. More interestingly, this surface reorganization strategy by oxygen plasma engraving can also be effective to other electrocatalysts such as free‐standing CoP, Co4N, O‐CoSe2, and C‐CoSe2 nanowires, which verifies the universality of the strategy. This work thus opens up new avenues for designing alkaline HER electrocatalysts based on oxygen plasma engraving.

In this study, by using dicobalt phosphide nanoparticles as precatalysts, we demonstrated that electrochemical activation of metallic precatalysts in alkaline media (comparing with directly electrochemical activation in neutral media) could significantly promote the OER catalysis in neutral media, specifically realizing a 2-fold enhanced activity and meanwhile showing a greatly decreased overpotential of about 100 mV at 10 mA cm. Compared directly with electrochemical activation in neutral media, the electrochemical activation in harsh alkaline media could easily break the strong Co-Co bond and promote active species generation on the surface of metallic CoP, thus accounting for the enhancement of neutral OER activity, which is also evidenced by HRTEM and the electrochemical double-layer capacitance measurement. The activation of electrochemical oxidation of metallic precatalysts in alkaline media enhanced neutral OER catalysis could also be observed on CoP nanoparticles and NiP nanoparticles, suggesting this is a generic strategy. Our work highlights that the activation of electrochemical oxidation of metallic precatalysts in alkaline media would pave new avenues for the design of advanced neutral OER electrocatalysts.

Mesenchymal stem cells (MSCs) are adult multipotent cells found in bone marrow, adipose tissue, and other adult tissues. MSCs improve regeneration of injured tissues in vivo, but the mechanisms remain unclear. Typically, MSCs are cultured under ambient or normoxic conditions (21% O2 ). However, the physiological niches of MSCs have much lower oxygen tension. When used as a therapeutic tool to repair tissue injuries, MSCs cultured in standard conditions must adapt from 21% O2 in culture to <1% O2 in ischemic tissue. We have examined the effects of hypoxia preconditioning (1% O2 ) in human adipose derived mesenchymal stem cells (AD-MSCs) to discover the conditions that best enhance their tissue regenerative potential. We demonstrate that AD-MSCs respond positively to hypoxia compared with normoxia preconditioning, show decreased apoptosis even in severe microenvironmental conditions (such as a low-serum medium), and an increased expression of the angiogenic factors, vascular endothelial growth factor and basic fibroblast growth factor. Human umbilical vein endothelial cells have higher vitality and lower apoptosis when cultured in medium taken from hypoxia-preconditioned AD-MSCs, as well as significantly increased capillary-like structures with this medium on Matrigel. The data suggest that hypoxia preconditioned AD-MSCs can improve tissue regeneration.

Our objective was to explore the mechanism of cell-assisted adipose transplantation by using freshly isolated human stromal vascular fraction (SVF) cells and to observe the dynamic changes of the graft after transplantation. The SVF was isolated from human liposuction aspirates, and 0.5 ml adipose tissue was mixed with 1 × 10 6 SVF cells or culture medium then injected to nude mice subcutaneously. At 1,4,7,14,30, 60, and 90 days after transplantation, samples were harvested for 1) general observation and retention rate; 2) whole-mount stain; 3) H&E stain; 4) immunohistochemical staining for S100, CD68, and CD34; 5) ELISA for VEGF and bFGF; 6) peroxisome proliferator-activated receptor-g (PPARg) fluorescence in situ hybridization. The retention rate in the experiment group was markedly higher than that in the control group. Whole-mount stain shows most of the cells in the center of the graft could not survive the ischemia until day 14. Histology showed new vessels on the surface of the graft at 3 days. However, in the control group, fewer newly formed vessels were detected until day 7. In the late stage of transplantation, gradual fibrosis was found in the graft, and the tissue was divided into a grid-like structure. A large number of round neonatal adipocytes with big nuclei in the center were found surrounding the new vessels, which were S100 and CD34 positive and CD68 negative. In the late stage of transplantation, most of the neonatal adipocytes were human PPARg positive. Moreover, the SVF group showed a higher level of VEGF and bFGF. SVF assisting adipose transplantation could increase the retention rate of the graft through promoting adipose tissue regeneration via secretion of growth factors, promotion of angiogenesis, and increasing the density of mesenchymal stem cells.

Autologous fat tissue has been used as a potential filler for soft-tissue defects, despite unpredictable clinical outcomes and low graft survival. Co-transplantation of adipose-derived stem cells (ASCs) is an alternative therapeutic approach to effectively enhance the survival and quality of transplanted fat tissue by increasing neovascularization. Nevertheless, the mechanisms by which ASCs exerted their angiogenic effects remain obscure. ASCs can secrete several angiogenic growth factors, for example vascular endothelial growth factor, hepatocyte growth factor and basic fibroblast growth factor. Hypoxic conditions may promote the proliferation of ASCs and their secretion. However, the differentiation of ASCs into endothelial cells (ECs), pericytes and smooth muscular cells in vivo has not been confirmed. The role of ASCs early after aspirated fat transplantation may be to induce new vessels from the recipient region to grow around and into the graft by releasing significant amounts of angiogenic growth factors rather than to differentiate into ECs, pericytes or smooth muscular cells forming new vessels, an effect that might be enhanced by hypoxia.

Polymerized high internal phase emulsions as highly porous adsorption materials have received increasing attention and wide applications in separation science in recent years due to their remarkable merits such as highly interconnected porosity, high permeability, good thermal and chemical stability, and tailorable chemistry. In this review, we attempt to introduce some strategies to utilize polymerized high internal phase emulsions for separation science, and highlight the recent advances made in the applications of polymerized high internal phase emulsions for diverse separation of small organic molecules, carbon dioxide, metal ions, proteins, and other interesting targets. Potential challenges and future perspectives for polymerized high internal phase emulsion research in the field of separation science are also speculated at the end of this review.

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Optimum perfusion may be the key to the endurance, and hence survival, of autologous adipose tissue transportation. Stromal vascular fraction (SVF) cell therapy can greatly improve the survival of fat grafts by enhancing angiogenesis. However, SVF cells are poorly retained in later stages of SVF-assisted adipose tissue transplant. Therefore, it hardly defines the angiogenic effect through long-term transportation. Adipose tissue suffers from acute hypoxia in the early stage of transportation, leading to the recruitment of macrophages. M2 macrophages enhance angiogenesis in adipose transplantation by acting as an angiogenic signal source, promoting tip cell migration and assisting tip cell fusion. Furthermore, the angiogenic and anti-inflammatory micro-environment in the graft created by M2 macrophages may stimulate the transformation of infiltrating macrophages to M2 macrophages. These M2 macrophages may enhance the long-term retention of graft through angiogenesis. Based on these observations, we postulate that the long-term angiogenic effect of SVF cells may be achieved through the facilitation of the M2 macrophages.