Enhancing photocathodic protection with Bi quantum dots and ZIF-8 nanoparticle co-sensitized TiO2nanotubes.

Since hole trapping agents do not persist in the marine environment, it is more practical to test metal protection in 3.5 wt% NaCl solution so that the photocathodic protection (PCP) technique can be effectively applied in an actual marine environment. In this paper, Bi quantum dots (QDs) and ZIF-8 nanoparticles (NPs) were successfully deposited on TiO2by hydrothermal and impregnation methods. The PCP performances of ZIF-8/Bi/TiO2composites in the marine environment without hole trapping agents were evaluated, and compared with the performances of pure TiO2, Bi/TiO2and ZIF-8/TiO2. The electrochemical impedance spectrum (EIS) fitting results demonstrate that theRctvalue of the ZIF-8/Bi/TiO2composite coupled with 316 stainless steel (SS) decreased from 7678 Ω cm2to 519.3 Ω cm2in 3.5 wt% NaCl solution, which is a decrease of about 14.8-fold compared with TiO2under the same conditions. This indicates that the deposition of Bi QDs and ZIF-8 NPs on TiO2nanotubes can improve the electron transport efficiency, which in turn slows down the rate of corrosion of 316 SS and significantly improves the PCP performance. This is not only attributable to the Schottky junction and heterojunction structures formed by Bi QDs and ZIF-8 NPs with TiO2, but also to the surface plasmon resonance effect of Bi QDs and the N-Ti-O bond structure formed between ZIF-8 and TiO2, leading to a lower electron-hole recombination efficiency and a higher electron transfer efficiency.

Effective Removal of Tetracycline from Water Using Copper Alginate @ Graphene Oxide with In-Situ Grown MOF-525 Composite: Synthesis, Characterization and Adsorption Mechanisms.

For nanomaterials, such as GO and MOF-525, aggregation is the main reason limiting their adsorption performance. In this research, Alg-Cu@GO@MOF-525 was successfully synthesized by in-situ growth of MOF-525 on Alg-Cu@GO. By dispersing graphene oxide (GO) with copper alginate (Alg-Cu) with three-dimensional structure, MOF-525 was in-situ grown to reduce aggregation. The measured specific surface area of Alg-Cu@GO@MOF-525 was as high as 807.30 m2·g-1, which is very favorable for adsorption. The synthesized material has affinity for a variety of pollutants, and its adsorption performance is significantly enhanced. In particular, tetracycline (TC) was selected as the target pollutant to study the adsorption behavior. The strong acid environment inhibited the adsorption, and the removal percentage reached 96.6% when pH was neutral. Temperature promoted the adsorption process, and 318 K adsorption performance was the best under experimental conditions. Meanwhile, 54.6% of TC could be removed in 38 min, and the maximum adsorption capacity reached 533 mg·g-1, far higher than that of conventional adsorption materials. Kinetics and isotherms analysis show that the adsorption process accords with Sips model and pseudo-second-order model. Thermodynamic study further shows that the chemisorption is spontaneous and exothermic. In addition, pore-filling, complexation, π-π stack, hydrogen bond and chemisorption are considered to be the causes of adsorption.

Geniposide attenuates cadmium­induced oxidative stress injury via Nrf2 signaling in osteoblasts.

Geniposide, as a type of iridoid glycoside, has antioxidative capacity. However, the mechanism underlying the effect of geniposide in cadmium (Cd)­induced osteoblast injury remains only partly elucidated. In the present study, Cell Counting Kit­8 (CCK­8) was used to determine MC­3T3­E1 cell viability. Flow cytometry was used to determine the rate of apoptosis and levels of reactive oxygen species (ROS). Oxidative stress­related factors were assessed using enzyme­linked immunosorbent method (ELISA). Quantitative real­time polymerase chain reaction (qPCR) and western blotting were used to evaluate apoptosis­ and bone formation­related genes and nuclear factor erythroid 2­related factor (Nrf2) signaling. It was demonstrated that geniposide increased the viability of the Cd­treated MC­3T3­E1 cells. Geniposide decreased apoptosis and ROS accumulation compared to these parameters in the Cd group. Geniposide attenuated oxidative stress­related factors, malondialdehyde and lactate dehydrogenase and increased antioxidant key enzyme superoxidase dismutase (SOD). The expression levels of Bax, Bcl­2 and survivin were modulated by geniposide. Additionally, the mRNA and protein expression of the receptor activator of NF­κB ligand (RANKL) and osterix were significantly increased, while osteoprotegerin was decreased by geniposide treatment compared to the Cd groups. Geniposide also enhanced Nrf2, heme oxygenase­1 (HO­1) and NAD(P)H quinone dehydrogenase 1 (NQO1) expression. The present study identified a potential agent for the treatment of Cd­induced osteoblast injury.