The highly selective catalytic hydrogenation of CO_(2)to CO over transition metal nitrides

Three transition metal-like facet centered cubic structured transition metal nitrides,γ-Mo_(2)N,β-W_(2)N andδ-NbN,are synthesized and applied in the reaction of CO_(2)hydrogenation to CO.Among the three nitride catalysts,theγ-Mo_(2)N exhibits superior activity to target product CO,which is 4.6 and 76 times higher than the other two counterparts ofβ-W_(2)N andδ-NbN at 600℃,respectively.Additionally,γ-Mo_(2)N exhibits excellent stability on both cyclic heating-cooling and high space velocity steady state operation.The deactivation degree of cyclic heating-cooling evaluation after 5 cycles and long-term stability performance at 773 and 873 K in 50 h are all less than 10%.In-situ XRD and kinetic studies suggest that theγ-Mo_(2)N itself is able to activate both of the reactants CO_(2)and H_(2).Below 400℃,the reaction mainly occurs at the surface ofγ-Mo_(2)N catalyst.CO_(2)and H_(2)competitively adsorbe on the surface of catalyst and CO_(2)is the relatively stronger surface adsorbate.At a higher temperature,the interstitial vacancies of theγ-Mo_(2)N can be reversibly filled with the oxygen from CO_(2)dissociation.Both of the surface and bulk phase sites ofγ-Mo_(2)N participate in the high temperature CO_(2)hydrogenation pathway.

Berberine enhances the anti-hepatocellular carcinoma effect of NK92-MI cells through inhibiting IFN-gamma-mediated PD-L1 expression

Background and aims:Berberine is one of the most promising clinically tested natural alkaloids,and immunotherapy using natural killer(NK)cells is a potentially effective treatment for hepatocellular carcinoma(HCC).This study aims to elucidate the effect of berberine on the anti-HCC effect of NK92-MI cells.Materials and methods:Human HCC SMMC-7721 and Hep3B cells were co-incubated with NK92-MI cells,berberine(60 or 80 mmol/L),or their combination for 36 h.To evaluate the killing effect of NK92-MI cells on HCC cells,the release of lactate dehydrogenase(LDH)in HCC cells was measured.The anti-tumor effects of berberine,NK92-MI cells,and their combinations were evaluated by MTS,EdU,Tunel,and Western blot assays.A male BALB/c nude mouse subcutaneous tumor model was used to investigate the anti-HCC effect of berberine and NK92-MI cells in vivo.Results:The LDH assay showed that berberine enhanced the cytotoxicity of NK92-MI cells on HCC cells.The combination of berberine and NK92-MI cells demonstrated more obvious anti-HCC effect than did the berberine or NK92-MI single treatment in inhibiting cell proliferation and inducing apoptosis both in vitro and in vivo.Mechanistically,the expression of programmed cell death-ligand 1(PD-L1)in HCC cells was upregulated after co-culture with NK-92MI cells.PD-L1 expression was knocked down,thereby inhibiting the proliferation and promoting apoptosis of HCC cells,and inhibited by berberine that blocked the secretion of interferon gamma(IFN-g),thereby enhancing the anti-tumor effect of NK92-MI cells.Conclusions:Current data show that the immunomodulatory role of berberine is to enhance the cytotoxic effect of NK92-MI cells and inhibit tumor immune escape by reducing the expression of PD-L1.Our study provides a rationale for the clinical application of berberine in combination with NK cells for the treatment of HCC.