Low-rate ferrate dosing damages the microbial biofilm structure through humic substances destruction and facilitates the sewer biofilm control.

The microbial activities in sewer biofilms are recognized as a major reason for sewer pipe corrosion, malodor, and greenhouse gas emissions. However, conventional methods to control sewer biofilm activities were based on the inhibitory or biocidal effect of chemicals and often required long exposure time or high dosing rates due to the protection of sewer biofilm structure. Therefore, this study attempt to use ferrate (Fe(VI)), a green and high-valent iron, at low dosing rates to damage the sewer biofilm structure so as to enhance sewer biofilm control efficiency. The results showed the biofilm structure started to crush when the Fe(VI) dosage was 15 mg Fe(VI)/L and the damage enhanced with the increasing dosage. The determination of extracellular polymeric substances (EPS) showed that Fe(VI) treatment at 15-45 mgFe/L mainly decreased the content of humic substances (HS) in biofilm EPS. This is because the functional groups, such as C-O, -OH, and C=O, which held the large molecular structure of HS, were the primary target of Fe(VI) treatment as suggested by 2D-Fourier Transform Infrared spectra. As a result, the coiled chain of EPS maintained by HS was turned to extended and dispersed and consequently led to a loosed biofilm structure. The XDLVO analysis suggested that both the microbial interaction energy barrier and secondary energy minimum were increased after Fe(VI) treatment, suggesting that the treated biofilm was less likely to aggregate and easier to be removed by the shear stress caused by high wastewater flow. Moreover, combined Fe(VI) and free nitrous acid (FNA) dosing experiments showed for achieving 90% inactivation, the FNA dosing rate could be reduced by 90% with the exposure time decreasing by 75% at a low Fe(VI) dosing rate and the total cost was substantially decreased. These results suggested that applying low-rate Fe(VI) dosing for sewer biofilm structure destruction is expected to be an economical way to facilitate sewer biofilm control.

Electrocatalytic Hydrogenation Boosts Reduction of Nitrate to Ammonia over Single-Atom Cu with Cu(I)-N3C1 Sites.

The conversion of nitrate to ammonia can serve two important functions: mitigating nitrate pollution and offering a low energy intensity pathway for ammonia synthesis. Conventional ammonia synthesis from electrocatalytic nitrate reduction reactions (NO3RR) is often impeded by incomplete nitrate conversion, sluggish kinetics, and the competition of hydrogen evolution reactions. Herein, atomic Cu sites anchored on micro-/mesoporous nitrogen-doped carbon (Cu MNC) with fine-tuned hydrophilicity, micro-/mesoporous channels, and abundant Cu(I) sites were synthesized for selective nitrate reduction to ammonia, achieving ambient temperature and pressure hydrogenation of nitrate. Laboratory experiments demonstrated that the catalyst has an ammonia yield rate per active site of 5466 mmol gCu-1 h-1 and transformed 94.8% nitrate in wastewater containing 100 mg-N L-1 to near drinking water standard (MCL of 5 mg-N L-1) at -0.64 V vs RHE. Extended X-ray absorption fine structure (EXAFS) and theoretical calculations showed that the coordination environment of Cu(I) sites (Cu(I)-N3C1) localizes the charge around the central Cu atoms and adsorbs *NO3 and *H onto neighboring Cu and C sites with balanced adsorption energy. The Cu(I)-N3C1 moieties reduce the activation energy of rate-limiting steps (*HNO3 → *NO2, *NH2 → *NH3) compared with conventional Cu(II)-N4 and lead to a thermodynamically favorable process to NH3. The as-prepared electrocatalytic cell can run continuously for 84 h (14 cycles) and produce 21.7 mgNH3 with only 5.64 × 10-3 kWh energy consumption, suitable for decentralized nitrate removal and ammonia synthesis from nitrate-containing wastewater.

Multi-component removal of Pb(II), Cd(II), and As(V) over core-shell structured nanoscale zero-valent iron@mesoporous hydrated silica.

The application of nanomaterials for the removal of heavy metals has received a great deal of attention because of their high efficiencies in the environment. But it is difficult to remove multiple heavy metals simultaneously with high efficiency and stability. Herein, the core-shell structured nanoscale zero-valent iron (nZVI) encapsulated with mesoporous hydrated silica (nZVI@mSiO2) were prepared for efficient removal of heavy metals including Pb(II), Cd(II), and metalloid As(V). The material prepared uniformly with a high surface area (147.7 m2 g-1) has a nZVI core with the particle size of 20-60 nm and a modified dendritic mesoporous shell of 19 nm. 0.15 g L-1 of the optimal material exhibited an extraordinary performance on removing Cd(II) and the maximum adsorption capacity for Pb(II), Cd(II), and As(V) reached 372.2 mg g-1, 105.2 mg g-1, and 115.2 mg g-1 with a pH value at 5.0, respectively. The dissolved iron during the reaction showed that the mesoporous silica (mSiO2) played an important role in enhancing the stability of nZVI. In addition, the competitive relationship between the coexistence of two heavy metals was discussed and it was found that the removal efficiency of the material for both was improved when Cd(II) and As(V) were removed synergistically.

Enhanced degradation of micropollutants over iron-based electro-Fenton catalyst: Cobalt as an electron modulator in mesochannels and mechanism insight.

Heterogeneous electro-Fenton (hetero-EF) process is an emerging alternative for effective oxidation of recalcitrant micropollutants, but it is hampered by limited hydroxyl radical (•OH) generation and low stability on the iron-based cathodes. Herein, we demonstrate an enhanced hetero-EF performance via modulation of iron electronic structure in an ordered mesoporous carbon (OMC). By tuning the cobalt incorporation, the highly-dispersed iron-cobalt (FeCo) nanoalloys in mesochannels (Fe0.5Co0.5@OMC) show a 3-fold increase in •OH yield compared with Fe@OMC, achieving degradation efficiency with 92% of sulfamethazine (SMT) and 99% of rhodamine B (RhB), and the corresponding total organic carbon (TOC) removal with 66% of SMT and 85% of RhB within 2 h in neutral pH, respectively. Experimental results and density functional theory (DFT) calculations demonstrate that iron incorporated with cobalt reduces energy barrier for facile generation of H2O2 and •OH from O2 through direct electron transfer, along with decreased overpotential. Meanwhile, cobalt doping promotes H2O2 decomposition by accelerated Fe(II)/Fe(III) cycle and Co(II)/Co(III) redox. Furthermore, spatially confined and half-embedded structure endows the nanocatalyst (8 nm) excellent durability within a wide pH value range and good stability in cycle tests. A plausible reaction mechanism and degradation pathway for SMT are proposed. Moreover, the superiority of Fe0.5Co0.5@OMC cathode is maintained in simulated wastewater, suggesting an enormous potential in practical wastewater treatment.

The effects of metformin on autophagy.

Metformin is the first-line option for treating newly diagnosed diabetic patients and also involved in other pharmacological actions, including antitumor effect, anti-aging effect, polycystic ovarian syndrome prevention, cardiovascular action, and neuroprotective effect, etc. However, the mechanisms of metformin actions were not fully illuminated. Recently, increasing researches showed that autophagy is a vital medium of metformin playing pharmacological actions. Nevertheless, results on the effects of metformin on autophagy were inconsistent. Apart from few clinical evidences, more data focused on kinds of no-clinical models. First, many studies showed that metformin could induce autophagy via a number of signaling pathways, including AMPK-related signaling pathways (e.g. AMPK/mTOR, AMPK/CEBPD, MiTF/TFE, AMPK/ULK1, and AMPK/miR-221), Redd1/mTOR, STAT, SIRT, Na+/H+ exchangers, MAPK/ERK, PK2/PKR/AKT/ GSK3ß, and TRIB3. Secondly, some signaling pathways were involved in the process of metformin inhibiting autophagy, such as AMPK-related signaling pathways (AMPK/NF-κB and other undetermined AMPK-related signaling pathways), Hedgehog, miR-570-3p, miR-142-3p, and MiR-3127-5p. Thirdly, two types of signaling pathways including PI3K/AKT/mTOR and endoplasmic reticulum (ER) stress could bidirectionally impact the effectiveness of metformin on autophagy. Finally, multiple signal pathways were reviewed collectively in terms of affecting the effectiveness of metformin on autophagy. The pharmacological effects of metformin combining its actions on autophagy were also discussed. It would help better apply metformin to treat diseases in term of mediating autophagy.

Effects of mindfulness-based stress reduction on anxiety symptoms in young people: A systematic review and meta-analysis.

In this study, we evaluated the efficacy of mindfulness-based stress reduction (MBSR) for young people with anxiety symptoms. We used many databases, including PubMed, PsycINFO, Web of Science, EMBASE, CINAHL and Cochrane Library (from inception to May 2019). We included randomized controlled trials (RCTs) comparing MBSR with various control conditions, including didactic lecture course, health education, treatment as usual, didactic seminar and cognitive behavioral program in young people with anxiety symptoms. Finally, we selected fourteen studies comprising 1489 participants comparing with control conditions. The meta-analysis suggested that MBSR significantly reduced anxiety symptoms compared to control conditions at post-treatment (Standardized Mean Difference, SMD = -0.14, 95% CI -0.24 to -0.04). However, the effect of MBSR on anxiety symptoms in young people may be affected by different intervention duration, especially the significance in a short-term intervention (less than 8 weeks). In addition, the meta-analysis indicated publication bias for anxiety symptoms. Using the trim-and-fill method, we found the adjusted standardized mean difference, which indicated that MBSR was still significantly superior to the other control conditions. The sensitivity analysis showed that the result was reliable. Current evidence indicates MBSR has superior efficacy compared with control conditions in treating young people with anxiety symptoms. Based on this, we suggest there is a significant effect of MBSR on young people with anxiety symptoms, especially the effects of long-term intervention for future studies.