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Metformin, a first-line drug for type-2 diabetes, plays a potentially protective role in preventing Alzheimer's disease (AD), but its underlying mechanism is unclear. In this study, Aβ25-35 -treated SH-SY5Y cells were used as a cell model of AD to investigate the neuroprotective effect of metformin, as well as its underlying mechanisms. We found that metformin decreased the cell apoptosis rate and death, ratio of Bcl-2/Bax, and expression of NR2A and NR2B, and increased the expression of LC3 in Aβ25-35 -treated SH-SY5Y cells. Metformin also reduced intracellular and extracellular Glu concentrations, as well as the intracellular concentration of Ca2+ and ROS in Aβ25-35 -treated SH-SY5Y cells. These findings suggest that metformin inhibits Aβ25-35 -treated SH-SY5Y cell death by inhibiting apoptosis, decreasing intracellular Ca2+ and ROS by reducing neurotoxicity of excitatory amino acids, and by possibly reversing autophagy disorder via regulating autophagy process.

The wasted sludge from ferrous ion-dependent nitrate removal (FeNiR) process is potential to be re-used as adsorbent to remove industrial pollutants. After pretreatment, the adsorption efficiency of FeNiR wasted sludge to reactive red X-3B, minocycline hydrochloride and Cr6+ was 88.95%, 90.08%, and 95.97%. The optimal initial pH to adsorb reactive red X-3B, minocycline hydrochloride, and Cr6+ was 2, 4, 2, while the optimal adsorbent dosage was 0.3 g, 0.8 g, and 1.0 g, and the optimal temperature was 50 °C, 30 °C, and 50 °C. The adsorption process follows the pseudo-secondary adsorption kinetics model, indicating the chemical adsorption dominates the adsorption process. The analysis of adsorption thermodynamic shows that all three adsorption reactions proceed spontaneously. From the results of the scanning electron microscope (SEM) and Brunner-Emmett-Teller (BET) analysis, the FeNiR wasted sludge after pretreatment is porous that endows the wasted sludge physical adsorption ability. The Fourier transform infrared (FTIR) analysis shows that the chemical bonds, including the hydroxyl group of Fe3O4, the Fe-O, and the α-FeOOH in the iron encrustation play more important roles in the adsorption process. Being used as adsorbent to treat industrial wastewater is a promising way to re-use the wasted sludge and decreases the cost of FeNiR process.

Phosphorous (P) recovery from industrial wastewaters solves both P deficiency and P pollution problems. A sequencing batch iron-air fuel cell was set up to recover P from synthetic wastewater containing 0.6 g-P/L Na2HPO4. In the cell, ferrous iron goes into the liquor from iron-anode to precipitate soluble P and form vivianite. Electrons travel from iron-anode to air-cathode through external circuit thus to generate energy. During 3 months' continuous operation, the P removal efficiency stably achieved at around 97.6%, and the average output voltage of cell was 404 mV. After long time operation, performance degradation of iron-air fuel cell was observed due to the electrode passivation caused by the accumulation of P precipitate on the iron-anode surface. The precipitate layer on the iron-anode impeded, but it did not block the mass transfer of ferrous iron to the anode liquor. The cell still worked with 25% decrease of output voltage, 86% decrease of current density, 87% decrease of power density and 9 times increase of internal resistance. Further analyses by XRD, FITR and Mossbauer illustrated that vivianite was the main component in both precipitates on the iron-anode surface and at the bottom of anode chamber with respective content of 66% and 30%. Vivianite on the iron-anode surface was a preferable choice due to higher content for P recovery. The iron-air fuel cell system could be a feasible option for achieving the multiple goals of P pollution control, resource recovery as vivianite, and energy generation, thereby contributing to the sustainable development of wastewater treatment.

Solvothermal reactions of CuX2 (X = NO3, Cl, Br, I) with tetra-pyridyl-functionalized calix[4]arene at 130 °C afforded four novel coordination polymers, {[(CuNO3)2L]·MeOH}n (1), [(CuCl2)L0.5]n (2), [(Cu3Br3)L]n (3), and [(Cu3I3)L]n (4), where L = 25,26,27,28-tetra[(3-pyridylmethyl)oxy]calix[4]arene. All the products were characterized by infrared spectroscopy, thermogravimetric analysis, single-crystal X-ray diffraction, and powder X-ray diffraction. Crystal structure analysis reveals that 1 holds a one-dimensional (1D) double-chain constructed by mononuclear [Cu(NO3)] units and L linkers, while 2 features a 1D chain and its bowl-shaped L ligands work as linkers to connect the dinuclear [Cu2Cl4] units. Compounds 3 and 4 bear similar two-dimensional networks, in which each trinuclear [Cu3Br3]/[Cu3I3] unit works as a three-connecting node to connect its six equivalents by sharing L ligands. These results demonstrate that different anions have a significant effect on the final structure formation. Compounds ...

Iron encrustation was deduced as the bottleneck for ferrous ion dependent nitrate removal (FeNiR) process development. To avoid the formation of iron encrustation, co-substrate cultivation (molar ratio of nitrate, ferrous sulfate and acetate at 8:20:1) was adopted. The FeNiR rate remained at 0.51 kg-N/(m3·d) for 40 days, the death rate of cells slowed down, and the specific FeNiR activity of sludge kept at 0.73 mg-N /(g VSS·h). Both facultative heterotrophic denitrifier and obligate heterotrophic denitrifier existed but the latter was deduced as the main contributor. A “barrier” around obligate heterotrophic denitrifier was observed. Cells inside the “barrier” were without iron encrustation. With insufficient organics, the nitrate was reduced to nitrite biologically and the nitrite travelled outside the “barrier” and reacted with ferrous ion chemically to accomplish FeNiR. With acetate as co-substrate, the formation of iron encrustation was efficiently avoided and a high and stable FeNiR efficiency was achieved.

In order to improve the fe rrous ion-dependent ni trate r emoval (FeNiR) process, hexametaphosphate chelated ferrous ion was used as substrate to replace the free ferrous ion. With hexametaphosphate chelated ferrous ion as substrate, the influent pH was adjusted to 6.8, and as a result a higher effluent pH (7.2) was detected. The v olumetric r emoval r ate (VRR) of nitrate kept at 0.42 ± 0.03 kg-N/(m3∙d) for 48 days and the corresponding nitrogen removal efficiency was 94.39 ± 4.57%. After 88 days of cultivation, FeNiR granules became small because of the oligotrophic substrate. The transmission electron microscope (TEM) analysis showed that less iron encrustation was formed on the surface or in the periplasm of FeNiR cells. The linear curve of the living cell percentage versus time showed that the death rate of FeNiR cells with chelated ferrous ion as substrate was much lower than that with free ferrous ion as substrate (0.4210 vs 0.9221). Without iron encrustation, both the FeNiR activity and al kaline p hosphatase (ALP) activity of FeNiR cells kept at high level and thus the efficiency of the FeNiR reactor kept stable and high. With hexametaphosphate chelated ferrous ion as substrate, the pH in bulk liquid was high (pH = 7.2) resulting in the high FeNiR rate, and less iron encrustation was formed around cells ensuring the stability of high FeNiR rate. Therefore, using hexametaphosphate chelated ferrous ion as substrate was an efficient way to improve the FeNiR process.

Electricigenic respiration is a new microbial metabolism discovered recently in an anaerobic environment lacking common electron receptors such as oxygen and others, in which some bacteria utilize extracellular electron transfer system. One electricigen, Klebsiella oxytoca d7, was isolated and confirmed its ability of electricigenic respiration in previous study, but its process and mechanism from intracellular respiratory chain to extracellular electron acceptors were not clear. In this paper, a microbial fuel cell (MFC) of this pure bacterium was constructed, and the main mechanism of electron transfer via the electron transfer mediators (ETMs) during electricity generation process of the bacterium was explored. The results show the ETMs can only be generated with the circuit on, and its contribution to the total electricity generation was much greater than that when the carbon source was insufficient. The redox potential of the ETMs of the K. oxytoca d7 was about −250 mV. The electrons were intercepted during the transfer from NADH to coenzyme Q and flow to the extracellular electron acceptors. The site of electron interception in the ETMs was only dependent on the redox potential of the ETMs secreted by the electricigens. Electrons were transferred from carriers in intracellular respiratory chain and with slightly higher redox potential than ETMs to ETMs. Normally the contribution of extracellular electron transfer mediated by ETMs to the total electricity generation amounted to more than 60%, indicating the process directly affected the conversion of organic substance in anode chamber and the electricity generation performance of the MFC.