Evaluation of Fe3O4-MnO2@RGO magnetic nanocomposite as an effective persulfate activator and metal adsorbent in aqueous solution.

A reduced graphene oxide (RGO) supported Fe3O4-MnO2 nanocomposite (Fe3O4-MnO2@RGO) was successfully prepared for catalytic degradation of oxytetracycline (20 mg/L) by potassium persulfate (PS) and adsorption removal of mixture of Pb2+, Cu2+, and Cd2+ ions (each 0.2 mM) in the synchronous scenario. The removal efficiencies of oxytetracycline, Pb2+, Cu2+, and Cd2+ ions were observed as high as 100%, 99.9%, 99.8%, and 99.8%, respectively, under the conditions of [PS]0 = 4 mM, pH0 = 7.0, Fe3O4-MnO2@RGO dosage = 0.8 g/L, reaction time = 90 min. The ternary composite exhibited higher oxytetracycline degradation/mineralization efficiency, greater metal adsorption capacity (Cd2+ 104.1 mg/g, Pb2+ 206.8 mg/g, Cu2+ 70.2 mg/g), and better PS utilization (62.6%) than its unary and binary counterparts including RGO, Fe3O4, Fe3O4@RGO, and Fe3O4-MnO2. More importantly, the ternary composite had good magnetic recoverability and excellent reusability. Notably, Fe, Mn, and RGO could play a synergistic role in the improvement of pollutant removal. Quenching results indicate that surface bounded SO4•- was the major contributor to oxytetracycline decomposition, and the -OH groups on the composite surface shouldered a significant role in PS activation. The results indicate that the magnetic Fe3O4-MnO2@RGO nanocomposite has a good potential for removing organic-metal co-contaminants in waterbody.

HIF-2α is indispensable for regulatory T cell function.

Hypoxia-inducible factor 1α (HIF-1α) and HIF-2α are master transcription factors that regulate cellular responses to hypoxia, but the exact function in regulatory T (Treg) cells is controversial. Here, we show that Treg cell development is normal in mice with Foxp3-specific knockout (KO) of HIF-1α or HIF-2α. However, HIF-2α-KO (but not HIF-1α-KO) Treg cells are functionally defective in suppressing effector T cell-induced colitis and inhibiting airway hypersensitivity. HIF-2α-KO Treg cells have enhanced reprogramming into IL-17-secreting cells. We show crosstalk between HIF-2α and HIF-1α, and that HIF-2α represses HIF-1α expression. HIF-1α is upregulated in HIF-2α-KO Treg cells and further deletion of HIF-1α restores the inhibitory function of HIF-2α-KO Treg cells. Mice with Foxp3-conditional KO of HIF-2α are resistant to growth of MC38 colon adenocarcinoma and metastases of B16F10 melanoma. Together, these results indicate that targeting HIF-2α to destabilize Treg cells might be an approach for regulating the functional activity of Treg cells.

Systematic studies on Yb x Bi1-x VO4:Tm3+ solid solutions: experiments and DFT calculations on up-conversion photoluminescence properties.

Compound solid solutions have attracted intensive attention due to their adjustable structure, electronic structure, and optical properties. Despite tremendous advances in compound solid solution preparations, combining a rare metal compound and a bismuth compound with the same crystal phase by forming a compound solid solution is still challenging but fascinating. For example, RE1-x Bi x VO4 with a zircon-type structure exhibits tunable band gaps and photoluminescence performance with varying RE compositions. Herein, Yb1-x Bi x VO4 solid solutions with continuous monophasic phase prepared by a facile synthesis strategy that is combined with co-precipitation and hydrothermal methods are reported. By doping a small amount of Tm3+, Yb x Bi1-x VO4 solid solutions can achieve a broad range up-conversion photoluminescence from UV-light to NIR-light. Combined with DFT calculations, the underlying mechanism of experimental observations is explained. In these up-conversion processes, the existence of Tm3+ is an essential factor. In particular, the NIR-to-UV up-conversion photoluminescence of Yb x Bi0.98-x VO4: 2 mol% Tm3+ solid solution is very interesting and a worthy phenomenon for further studies. As such, designing compound solid solutions may provide a new avenue for controllable up-conversion efficiencies in semiconductor nanocrystals and also a novel insight into the rational tunable up-conversion process for applications in biological labeling and imaging.