The biofilm characteristics and enhanced performance of a marine microbial-electrolysis-cell-based biosensor under positive anodic potential

Microbial fuel cells have already been used as biosensors to monitor assimilable organic carbon(AOC).However,their signal production from AOC is known to be completely suppressed by dissoved oxygen(DO).In this study,two identical microbial electrolysis cell(MEC)based biosensors were inoculated with marine sediment and operated at two different anodic potentials,namely-300 mV and+250 mV relative to Ag/AgCl.The MEC biosensor operated under positive anodic potential conditions had electrochemically active microbial communities on the anode,including members of the Shewanellaceae,Pseudoalteromonadaceae,and Clostridiaceae families.However,the strictly anaerobic members of the Desulfuromonadaceae,Desulfobulbaceae and Desulfobacteraceae families were found only in the negative anodic potential MEC biosensor.The positive anodic potential MEC biosensor showed several other advantages as well,such as faster start-up,significantly higher maximum current production,fivefold improvement in the AOC detection limit,and tolerance of low dissolved oxygen,compared to those obtained from the negative anodic potential MEC biosensor.The developed positive anodic potential MEC biosensor can thus be used as a real-time and inexpensive detector of AOC concentrations in high saline and low DO seawater.

Regeneration of activated carbon adsorbed EDTA by electrochemical method

Activated carbon after saturated adsorption of EDTA was used as particle electrode in a three-dimensional electrode reactor to treat EDTA-containing wastewater.Electrochemical method was used to regenerate activated carbon after many times of electrolysis.Based on the analysis of infrared spectra of activated carbon after adsorption and repeated electrolysis,EDTA was degraded into glycine,and then non-catalytic activated associated complex was formed with N—H bond on the activated carbon.The catalytic ability of the activated carbon vanished and the EDTA degradation efficiency was dropped.Activated carbon could be effectively regenerated by electrochemical method in the three-dimensional reactor.Effects of electric current,conductivity and pH on activated carbon regeneration were investigated,and the optimum conditions were concluded as follows：100-300 mA of current intensity,1.39 mS/cm of electric conductivity,60 min of electrolysis time and pH 6.0-8.0.Under the optimized conditions,the activity of the activated carbon can be recovered and the residual total organic carbon（TOC） was below 10 mg/L（the initial TOC was 200 mg/L） in the three-dimensional electrode reactor.

Chemical etching process of copper electrode for bioelectrical impedance technology

In order to obtain bioelectrical impedance electrodes with high stability, the chemical etching process was used to fabricate the copper electrode with a series of surface microstructures. By changing the etching processing parameters, some comparison experiments were performed to reveal the influence of etching time, etching temperature, etching liquid concentration, and sample sizes on the etching rate and surface microstructures of copper electrode. The result shows that the etching rate is decreased with increasing etching time, and is increased with increasing etching temperature. Moreover, it is found that the sample size has little influence on the etching rate. After choosing the reasonable etching liquid composition （formulation 3）, the copper electrode with many surface microstructures can be obtained by chemical etching process at room temperature for 20 rain. In addition, using the alternating current impedance test of electrode-electrode for 24 h, the copper electrode with a series of surface microstructures fabricated by the etching process presents a more stable impedance value compared with the electrocardiograph （ECG） electrode, resulting from the reliable surface contact of copper electrode-electrode.

Decomposition mechanism of pentlandite during electrochemical bio-oxidation process

Electrochemical measurements were carried out to elucidate decomposition mechanism of pentlandite using modified powder microelectrode with Acidithiobacillus ferrooxidans attached or without on the mineral powder surface.Cyclic voltammetry（CV） results show that at a low potential of about-0.2 V（vs SCE）,the pentlandite was transformed to an intermediated phase like Fe4.5-yNi4.5-xS8-z when Fe and Ni ions were evacuated from mineral lattice;when the potential was changed from-0.2 V to 0.2 V,the unstable violarite（Fe3Ni3S4） and FeNi2S4 were formed which was accompanied by element sulfur formed on the mineral surface;when the potential increased over 0.2 V,the unstable intermediated phase decomposed entirely;at a higher potential of 0.7 V,the evacuated ferrous ion was oxidized to ferric ion.The presence of Acidithiobacillus ferrooxidans made the oxidation peak current increase with initial peak potential negatively moving,and the bacteria also contributed to the sulfur removing from mineral surface,which was demonstrated by the reduction characteristic at potential ranging from-0.75 to-0.5 V.Leaching experiments and electrochemical results show that the solution acidity increasing when pH2 may impede the oxidation process slightly.

Multi-channel neural signal stimulating module and in-vivo experiments

The module for function electrical stimulation （FES） of neurons is designed for the research of the neural function regeneration microelectronic system, which is an in-body embedded micro module. It is implemented by using discrete devices at first and characterized in vitro. The module is used to stimulate sciatic nerve and spinal cord of rats and rabbits for in-vivo real-time experiments of the neural function regeneration system. Based on the module, a four channel module for the FES of neurons is designed for 12 sites cuff electrode or 10 sites shaft electrode. Three animal experiments with total five rats and two rabbits were made. In the in-vivo experiment, the neural signals including spontaneous and imitated were regenerated by the module. The stimulating signal was used to drive sciatic nerve and spinal cord of rats and rabbits, successfully caused them twitch in different parts of their bodies, such as legs, tails, and fingers. This testifies that the neural function regeneration system can regenerate the neural signals.

Integrated circuit for single channel neural signal regeneration

Based on the 4-channel neural signal regeneration system which is realized by using discrete devices and successfully used for in-vivo experiments on rats and rabbits, a single channel neural signal regeneration integrated circuit （IC）is designed and realized in CSMC ＇ s 0. 6 μm CMOS （ complementary metal-oxide-semiconductor transistor ） technology. The IC consists of a neural signal detection circuit with an adjustable gain, a buffer, and a function electrical stimulation （FES） circuit. The neural signal regenerating IC occupies a die area of 1.42 mm × 1.34 mm. Under a dual supply voltage of ±2. 5 V, the DC power consumption is less than 10 mW. The on-wafer measurement results are as follows： the output resistor is 118 ml）, the 3 dB bandwidth is greater than 30 kHz, and the gain can be variable from 50 to 90 dB. The circuit is used for in-vivo experiments on the rat＇ s sciatic nerve as well as on the spinal cord with the cuff type electrode array and the twin-needle electrode. The neural signal is successfully regenerated both on a rat＇ s sciatic nerve bundle and on the spinal cord.

Mushroom Pulp Tissue-Based Membrane-Ferrocene-Modified L-Tyrosine Biosensor

A new approach for assembling amperometric mushroom pulp tissue based membrane electrode for determination of L tyrosine analysis is proposed. Ferrocene is used as a mediator of electron transfer between tyrosinase in mushroom tissue and a graphite electrode. The optimal operation conditions are studied. The linear response range of the biosensor is 2 0×10 -4 to 4 5×10 -3 mol·L -1 with response time of less than 5 min and lifetime of at least 30 d. The biosensor can be applied to practical sample analysis.

In Situ Growth of 3D Hierarchical ZnO@Ni_xCo_(1-x)(OH)_y Core/Shell Nanowire/Nanosheet Arrays on Ni Foam for High-Performance Aqueous Hybrid Supercapacitors

In this study, we designed and synthesized a novel battery-type electrode featuring three-dimensional(3D) hierarchical ZnO@Ni_xCo_(1-x)(OH)_y core/shell nanowire/nanosheet arrays arranged on Nifoam substrate via a two-step protocol including a wet chemical process followed by electro-deposition. We then characterized its composition, structure and surface morphology by X-ray diff raction, energy-dispersive X-ray spectrometry(EDS), X-ray photoelectron spectroscopy, scanning electron microscopy(SEM), transmission electron microscopy, EDS elemental mapping. Our electrochemical measurements show that the ZnO@Ni_(0.67)Co_(0.33)(OH)_y electrode material exhibited a noticeably high specific capacity of as much as 255(mA ·h)/g at 1 A/g. Additionally, it demonstrated a superior rate capability, as well as an excellent cycling stability with 81.6% capacity retention over 2000 cycles at 5 A/g. This sample delivered a high energy density of 64 W·h/kg and a power density of 250 W/kg at a current density of 1 A/g. With such remarkable electrochemical properties, we expect the 3D hierarchical hybrid electrode material presented in this work to have promising applications for the next generation of energy storage systems.

Inocula selection in microbial fuel cells based on anodic biofilm abundance of Geobacter sulfurreducens

Microbial fuel cells （MFCs） rely on microbial conversion of organic substrates to electricity. The optimal perfor- mance depends on the establishment of a microbial community rich in electrogenic bacteria. Usually this micro- bial community is established from inoculation of the MFC anode chamber with naturally occurring mixed inocula. In this study, the electrochemical performance of MFCs and microbial community evolution were eval- uated for three inocula including domestic wastewater （DW）, lake sediment （LS） and biogas sludge （BS） with varying substrate loading （Lsub） and external resistance （Rext） on the MFC. The electrogenic bacterium Geobacter sulfurreducens was identified in all inocula and its abundance during MFC operation was positively linked to the MFC performance. The IS inoculated MFCs showed highest abundance （18% ± 1%） of G. sulfurreducens, maximum current density [Imax = （690 ± 30） mA.m 2] and coulombic efficiency （CE = 29% ±1%） with acetate as the substrate./max and CE increased to （1780 ± 30） mA.m-2 and 58%± 1%, respectively, after decreasing the Rext from 1000 Ωto 200 Ω, which also correlated to a higher abundance ofG. sulfurreducens （21% ±0.7%） on the MFC anodic biofilm. The data obtained contribute to understanding the microbial community response to Lsub and Roy, for of timizing electricity eneration in MFCs.

Polyaniline-graphite composite film glucose oxidase electrode

A novel polyaniline-graphite composite film glucose oxidase （PGCF GOD） electrode was developed. The PGCF was synthesized by cyclic voitammetry method in 0.5 mol/L H2SO4 solution containing 1 g/L graphite powder and 0.2 mol/L aniline. The PGCF GOD electrode was prepared by doping GOD into the composite film. The morphology of the PGCF and the response property of the PGCF GOD electrode were investigated by scanning electron microscopy and electrochemical measurement, respectively. The results show that the PGCF has a porous and netty structure and the PGCF GOD electrode has excellent response property such as high sensitivity and short response time. Influences of pH value, temperature, glucose concentration and potential on the response current of the electrode were also discussed. The sensor has a maximum steady-state current density of 357.17μA/cm2 and an apparent Michaelis-Menten constant of 16.57 mmol/L. The maximum current response of the enzyme electrode occurs under the condition ofpH 5.5, 0.8 V and 65℃.

Preparation of LiFePO_4 for lithium ion battery using Fe_2P_2O_7 as precursor

In order to obtain a new precursor for LiFePO4, Fe2P2O7 with high purity was prepared through solid phase reaction at 650 ℃ using starting materials of FeC2O4 and NH4H2PO4 in an argon atmosphere. Using the as-prepared Fe2P2O7, Li2CO3 and glucose as raw materials, pure LiFePO4 and LiFePO4/C composite materials were respectively synthesized by solid state reaction at 700 ℃ in an argon atmosphere. X-ray diffractometry and scanning electron microscopy（SEM） were employed to characterize the as-prepared Fe2P2O7, LiFePO4 and LiFePO4/C. The as-prepared Fe2P2O7 crystallizes in the Cl space group and belongs to β-Fe2P2O7 for crystal phase. The particle size distribution of Fe2P2O7 observed by SEM is 0.4-3.0 μm. During the Li^＋ ion chemical intercalation, radical P2O7^4- is disrupted into two PO4^3- ions in the presence of O^2-, thus providing a feasible technique to dispose this poor dissolvable pyrophosphate. LiFePO4/C composite exhibits initial charge and discharge capacities of 154 and 132 mA·h/g, respectively.

Power production enhancement with polyaniline composite anode in benthic microbial fuel cells

In this study,conductive polymer polyaniline(PANI)is employed to modify the anodes of benthic microbial fuel cells(BMFC).Four electrochemical methods are used to synthesize the polyaniline anodes;the results show that the PANI modification,especially the pulse potential method for PANI synthesis could obviously improve the cell energy output and reduce the anode internal resistance.The anode is modified by PANI doped with Fe or Mn to further improve the BMFC performance.A maximum power density of 17.51 mW/m2 is obtained by PANI-Fe anode BMFC,which is 8.1 times higher than that of control.The PANI-Mn anode BMFC also gives a favorable maximum power density(16.78 mW/m2).Fe or Mn modification has better effect in improving the conductivity of polyaniline,thus improving the energy output of BMFCs.This work applying PANI composite anode into BMFC brings new development prospect and could promote the practical application of BMFC.

Combined Novel Gate Level Model and Critical Primary Input Sharing for Genetic Algorithm Based Maximum Power Supply Noise Estimation

A gate level maximum power supply noise （PSN） model is defined that captures both IR drop and di/dt noise effects. Experimental results show that this model improves PSN estimation by 5.3% on average and reduces computation time by 10.7% compared with previous methods. Furthermore,a primary input critical factor model that captures the extent of primary inputs＇ PSN contribution is formulated. Based on these models,a novel niche genetic algorithm is proposed to estimate PSN more effectively. Compared with general genetic algorithms, this novel method can achieve up to 19.0% improvement on PSN estimation with a much higher convergence speed.

Oxidation of chalcopyrite in air-equilibrated acidic solution: Inhibition with phenacyl derivatives

The effects of 4-(2-hydroxyphenyl)-2-(morpholin-4-yl)-1,3-thiazole(Pr02), 1-(3,5-dibromo-2-hydroxyphenyl)-1-oxoethan-2-yl-N,N-diethyldithiocarbamate(Pr04) and 1-(5-bromo-2-hydroxy-3-methylphenyl)-1-oxoethan-2-yl-Oethyl xanthate(Pr06) on the aqueous oxidation of chalcopyrite(CuFeS2) in air-equilibrated solution at a temperature of 25 ℃ and a pH of 2.5 were studied. The effects were investigated by using potentiodynamic polarization, electrochemical impedance spectroscopy(EIS), scanning electron microscopy coupled with energy dispersive X-ray(SEM/EDX) analysis, aqueous batch experiments, Fourier transform infrared(FTIR) spectroscopy, Raman scattering and quantum chemical calculations. It is found that the anodic current densities decrease in the order of EtOH > Pr02 > Pr04 > Pr06. These results, along with those of the EIS measurements, show that Pr02, Pr04 and Pr06 are effective anodic inhibitors of chalcopyrite aqueous oxidation. Both Raman scattering and FTIR spectroscopy indicate that the elemental sulfur, polysulfide and ferric oxyhydroxides that form on the surface of the mineral are not responsible when it comes to the aqueous oxidation inhibition of chalcopyrite. Quantum chemical calculations show that the adsorption of the tested compounds on the chalcopyrite surface is energetically favorable and so, it can explain the inhibiting effects that were observed.

Rapid Regeneration of Chelated Iron Desulfurization Solution Using Electrochemical Reactor with Rotating Cylindrical Electrodes

A new electrochemical reactor with rotating cylindrical electrodes was designed and used to increase the regeneration efficiency of chelated iron desulfurization solution.The influence of operating parameters,such as the rotation speed of electrode,voltage,and inlet air and liquid flow rates,on the regeneration rate was investigated.Compared with the traditional tank-type reactor,the regeneration rate with the new electrochemical reactor was increased significantly.Under the optimum conditions,the regeneration rate was increased from 45.3%to 84.8%.Experimental results of continuous operation indicated that the new electrochemical regeneration method had some merits including higher regeneration efficiency,smaller equipment size and good stability in operation.

Regeneration of Al-doped LiNi_(0.5)Co_(0.2)Mn_(0.3)O_(2) cathode material by simulated hydrometallurgy leachate of spent lithium-ion batteries

A uniform Al-doped LiNi_(0.5)Co_(0.2)Mn_(0.3)O_(2) cathode material was prepared using a coprecipitation method to take advantage of the positive effect of Al on regenerated NCM(Ni,Co,Mn)cathode materials and ameliorate cumbersome and high-cost impurity removal processes during lithium-ion battery recycling.When the Al^(3+) content in the leachate was 1 at.%with respect to the total amount of transition metals(Ni,Co,and Mn),the produced Al-doped NCM cathode material increased concentrations of lattice oxygen and Ni^(2+).The initial specific capacity at 0.1C was 167.4 mA·h/g,with a capacity retention of 79.1%after 400 cycles at 1C.Further,this Al-doped sample showed improved rate performance and a smaller electrochemical impedance.These findings provide a reference for developing industrial processes to resynthesize cathode materials with improved electrochemical performance by incorporating Al^(3+) impurities produced during lithium-ion battery recycling.

Stochastic Thermodynamics of Mesoscopic Electrochemical Reactions

In this work, we discussed the stochastic thermodynamics of mesoscopic electron transfer reactions between ions and electrodes. With a relationship between the reaction rate con- stant and the electrode potential, we find that the heat dissipation βq equals to the dynamic irreversibility of the reaction system minus an internal entropy change term. The total en- tropy change Ast is defined as the summation of the system entropy change As and the heat dissipation/βq such that △st=△s＋βq. Even though the heat dissipation depends linearly on the electrode potential, the total entropy change is found to satisfy the fluctuation theo- rem 〈e-△st 〉=1, and hence a second law-like inequality reads （△st）≥0. Our study provides a practical methodology for the stochastic thermodynamics of electrochemical reactions, which may find applications in biochemical and electrochemical reaction systems.

Promising Graphene Modified Electrode Using Layer-by-Layer Method for Microbial Biofilm Connection

In order to enhance the power output of microbial fuel cell as well as its stability, the development of a new type of anode is essential. The purpose of this work is to modify a stainless steel foam, using the layer-by-layer self-assembly technique, with rGO （reduced grapbene oxide） and PEI （polyethyleneimine）. The efficiency of this kind of modification has been investigated to determine the supply of graphene in term of electricity generation and stability. Under an applied voltage, which is used to form an electroactive biofilm, the modified stainless steel foam （SSF/（PE1/rGO）5） exhibited a current 50 times higher than the blank anode. The roughness of the SSF/（PEI/rGO）5 observed by SEM （scanning electron microscopy） is more favorable to attach more bacteria on it. Also, graphene improved the stability of the electrode as no response where observed for the blank anode after 18 days meanwhile the SSF/（PEI/rGO）5 was still running after 54 days.

The preparation of high performance carbon electrode in electrochemical oxygen generator

The electrochemical oxygen generator has been popularized for its virtues, such as high oxygen concentration output, electricity saving, easy operation and maintenance. The key part of electrochemical oxygen generator is carbon electrode used as the cathode. The preparation of high performance carbon electrode was introduced in this paper. The properties of carbon electrode was tested. The electrochemical oxygen generator using carbon electrode as the cathode was prepared. The oxygen concentration and flow of this machine is hi,yher thnn ｜hal of others in china.