The effects of magnetic fields (MFs) on the corrosion of 304 stainless steel (SS304) caused by oil-field sulfate-reducing bacteria (SRB) were investigated. Experimental data showed that the MF lowered the population of planktonic SRB by almost 4 orders of magnitude and delayed the formation of SRB biofilms on the SS304 coupons. The mass losses and surface images of the coupons indicated that the application of an MF considerably reduced the pitting corrosion of SS304. EDX and XPS analyses of the coupon surfaces demonstrated that the main corrosion products without an MF and with 2 and 4 mT MFs were FeS, FeO, and Fe2O3, respectively. The application of MFs could be an environmentally friendly method for mitigating microbiologically influenced corrosion (MIC) on SS304.

•CuO@MnAl NSs have been fabricated by co-precipitation and hydrothermal approach.•MnAl layered doubled hydroxide can be used to wrap n-type CuO nanoparticles.•MnAl layered doubled hydroxide serves as p-type semiconductive material.•CuO@MnAl NSs electrode demonstrates excellent electrochemical performance towards the nonenzymatic sensing of H2O2.•Real-time monitoring of H2O2 from blood serum, urine and secreted by live tumorigenic and normal cells.Structurally integrated metal oxide intercalated layered double hydroxide (LDH) nanospheres (NSs) hybrid material has been of considerable current interest because of their unique structure and synergistic combination of multi- functional properties of nanocomposites. In this work, we report a new type of MnAl LDH wrapped CuO (CuO@MnAl LDHs) NSs by anchoring CuO nanoparticles (NPs) with MnAl LDHs via a facile co-precipitation and hydrothermal approach, and explore its practical application as high-efficient electrocatalyst towards H2O2 reduction for biological application. Our findings demonstrate that the integration of n-type spinel of CuO and p-type semiconductive channels of MnAl LDHs can accelerate electron transfer at breakdown voltage of p-n junction. Owing to the synergistic effect of the high surface area of CuO NPs, superb intercalation features of semiconductive MnAl LDHs for encapsulating NSs, and their intrinsic p-n junction characteristics, CuO@MnAl NSs have exhibited excellent electrocatalytic activity towards the reduction of H2O2. When implemented in electrochemical sensor system, the CuO@MnAl NSs modified electrode displays high nonenzymatic sensing performances towards H2O2 including a broad linear range 6 μM–22 mM, a low detection limit of 0.126 μM, good selectivity and long term stability, which can be exploited for in vitro detection of H2O2 in human serum and urine samples, as well as real-time tracking H2O2 secreted from different human live cells.

•MnO2–graphene paper has been fabricated by one-step electrochemical method.•MnO2–graphene paper serves as high-performance flexible electrode for nonenzymatic electrochemical sensing of hydrogen peroxide.•MnO2–graphene paper electrode has been used for real-time tracking hydrogen peroxide secretion by live cells.Recent progress in flexible and lightweight electrochemical sensor systems requires the development of paper-like electrode materials. Here, we report a facile and green synthesis of a new type of MnO2 nanowires–graphene nanohybrid paper by one-step electrochemical method. This strategy demonstrates a collection of unique features including the effective electrochemical reduction of graphene oxide (GO) paper and the high loading of MnO2 nanowires on electrochemical reduced GO (ERGO) paper. When used as flexible electrode for nonenzymatic detection of hydrogen peroxide (H2O2), MnO2–ERGO paper exhibits high electrocatalytic activity toward the redox of H2O2 as well as excellent stability, selectivity and reproducibility. The amperometric responses are linearly proportional to H2O2 concentration in the range 0.1–45.4 mM, with a detection limit of 10 μM (S/N = 3) and detection sensitivity of 59.0 μA cm−2 mM−1. These outstanding sensing performances enable the practical application of MnO2–ERGO paper electrode for the real-time tracking H2O2 secretion by live cells macrophages. Therefore, the proposed graphene-based nanohybrid paper electrode with intrinsic flexibility, tailorable shapes and adjustable properties can contribute to the full realization of high-performance flexible electrode material used in point-of-care testing devices and portable instruments for in-vivo clinical diagnostics and on-site environmental monitoring.

The microbiologically influenced corrosion behaviors of the 3A21 aluminum alloy in Wuhan (Hubei Province, China) municipal potable water containing wild-type total culturable bacteria (TCB) at different temperatures were investigated by mass loss and surface morphology analysis. When the water was inoculated with sulfate-reducing bacteria (SRB), laboratory results showed that SRB inhibited the mass loss-based rate of corrosion of the Al alloy coupons at 30 °C but accelerated the corrosion rate by 2- and 4.6-fold at 45 and 60 °C, respectively. It was also found that the presence of aerobic iron-oxidizing bacteria (IB) significantly reduced the corrosion rate at 45 °C. The average corrosion rate in water inoculated with enriched TCB was the highest, and it decreased at higher temperatures. At 60 °C, SRB were found to be the dominant bacteria in the water with TCB and in the water with IB.