Graphene oxide (GO) sheets exhibit superior adsorption capacity for removing organic dye pollutants from an aqueous environment. In this paper, the facile preparation of GO/polyethylenimine (PEI) hydrogels as efficient dye adsorbents has been reported. The GO/PEI hydrogels were achieved through both hydrogen bonding and electrostatic interactions between amine-rich PEI and GO sheets. For both methylene blue (MB) and rhodamine B (RhB), the as-prepared hydrogels exhibit removal rates within about 4 h in accordance with the pseudo-second-order model. The dye adsorption capacity of the hydrogel is mainly attributed to the GO sheets, whereas the PEI was incorporated to facilitate the gelation process of GO sheets. More importantly, the dye-adsorbed hydrogels can be conveniently separated from an aqueous environment, suggesting potential large-scale applications of the GO-based hydrogels for organic dye removal and wastewater treatment.

New reduced graphene oxide-based silver nanoparticle-containing composite hydrogels were successfully prepared in situ through the simultaneous reduction of GO and noble metal precursors within the GO gel matrix. The as-formed hydrogels are composed of a network structure of cross-linked nanosheets. The reported method is based on the in situ co-reduction of GO and silver acetate within the hydrogel matrix to form RGO-based composite gel. The stabilization of silver nanoparticles was also achieved simultaneously within the gel composite system. The as-formed silver nanoparticles were found to be homogeneously and uniformly dispersed on the surface of the RGO nanosheets within the composite gel. More importantly, this RGO-based silver nanoparticle-containing composite hydrogel matrix acts as a potential catalyst for removing organic dye pollutants from an aqueous environment. Interestingly, the as-prepared catalytic composite matrix structure can be conveniently separated from an aqueous environment after the reaction, suggesting the potentially large-scale applications of the reduced graphene oxide-based nanoparticle-containing composite hydrogels for organic dye removal and wastewater treatment.

Peer victimization can have a profound effect on children’s wellbeing and is a known risk factor for depression in childhood. Migrant children experience peer victimization at higher rates than non-migrant peers; however, limited research has examined psychological factors that may serve to reduce depression risk for this group. In particular, no studies have yet investigated whether resilience, including personal characteristics, and a strong social support network, may moderate the relationship between peer victimization and depressive symptoms for migrant children. This study utilized a latent interaction model to examine the effect of resilience on the relationship between peer victimization and depressive symptoms among 721 rural-to-urban migrant children in Beijing, China. Results indicated that peer victimization was positively associated with depressive symptoms. Resilience was found to be a protective factor for depressive symptoms and also mitigated the effects of peer victimization on depressive symptoms. Exploratory analyses suggest that enrollment in private migrant schools may be linked with poorer psychosocial outcomes for Chinese migrant children. Strengthening the internal resilience and social supports for all migrant children may be an effective strategy to lower their risk for depression. Implications for intervention are discussed.

We have connected a borondipyrromethene (BODIPY) donor to the 5' position of a tetramethylrhodamine (TMR) acceptor to form a high efficiency (over 99%) intramolecular fluorescence resonance energy transfer (FRET) cassette, BODIPY-rhodamine platform (BRP). While the good spectral overlap between the emission of BODIPY and the absorption of TMR was one favorable factor, another feature of this FRET system was the rigid and short biphenyl spacer that favored efficient through-bond energy transfer. More importantly, in this system, the 2'-carboxyl group of the rhodamine unit was preserved for the further modifications, which was as convenient as those carbonyl groups on the original rhodamines without connection to donors. For this reason, BRP is clearly differentiated from the previous ratiometric sensors based on donor rhodamine systems. To illustrate its value as a versatile platform, we introduced typical Hg(2+) receptors into BRP, through convenient one-pot reactions on the 2'-carboxyl group, and successfully developed two ratiometric sensors, BRP-1 and BRP-2, with different spirocyclic receptors that recognized Hg(2+) on different reaction mechanisms. Upon excitation at a single wavelength (488 nm), at which only BODIPY absorbed, both of the FRET sensors exhibited clear Hg(2+)-induced changes in the intensity ratio of the two strong emission bands of BODIPY and rhodamine. It should be noted that these ratiometric Hg(2+) sensors exhibited excellent sensitivity and selectivity Hg(2+), as well as pH insensitivity, which was similar to the corresponding 'turn-on' rhodamine sensors. While both ratiometric probes were applicable for Hg(2+) imaging in living cells, BRP-1 exhibited higher sensitivity and faster responses than BRP-2. Our investigation indicated that on a versatile platform, such as BRP, a large number of highly efficient ratiometric sensors for transition-metal ions could be conveniently developed.