乳山湾底质中硫化物和氧化-还原电位的分布与变化

2004年6、8和10月分别对乳山湾东流区共进行了3个航次的调查。调查结果表明,乳山湾东流区属于弱还原环境,表层沉积物中硫化物的含量基本呈北侧高、南侧低的趋势,而氧化-还原电位则呈北侧低、南侧高变化趋势。硫化物的垂直分布基本表现为随深度的增加而增加,氧化-还原电位的垂直分布基本表现为随深度的增加而降低。但是,由于受到贝类养殖的影响,出现了较多的例外情况。硫化物含量和氧化-还原电位随季节的变动较明显,硫化物含量8月最高,6月次之,10月最低;而氧化-还原电位则10月最高,6月次之,8月最低。贝类养殖对沉积环境中硫化物与氧化-还原电位有明显影响,养殖区硫化物的含量高于非养殖区,而氧化-还原电位则低于非养殖区。

成都地区青年人群中血浆和红细胞还原/氧化型谷胱甘肽的含量及其氧化-还原电位的分布

目的 :测量谷胱甘肽还原型和氧化型在血浆内和红细胞内的含量 ,探讨GSH/GSSG及其氧化还原电位在健康人群的分布情况。方法 :在组织内谷胱甘肽荧光测量法的基础上 ,加以改进 ,对血浆和红细胞内的GSH/GSSG进行测定 ,并计算出GSH/GSSH的氧化还原电位。同时 ,探讨了冷冻保存和去蛋白处理对血浆和红细胞内GSH和GSSG的影响。结果 :改进后的方法具重复性好 ;准确性高 ,回收率在 98.7%和 97.5 % ;标准曲线呈明显线性等良好的测定效率。用本法对 42名年青年健康志愿者的新鲜血浆和红细胞液的谷胱甘肽进行测定 ,结果为 :血浆内GSH的范围为 8.64± 1 .40 μmol/L ,GSSG的范围为 1 .0 8± 0 .2 4μmol/L ,GSH/GSSG的比值为1 0 .2 7± 1 .5 4;红细胞内GSH的范围为 6.81± 1 .3 8μmol/LRBC ,红细胞内GSSG的范围为 0 .77± 0 .3 9μmol/LR BC ,GSH/GSSG的比值为 9.0 2± 3 .61。血浆GSH/GSSG的氧化还原电位为Eh =-2 1 3 .9mV± 4.94mV ;RBC液的Eh =-2 2 1 .4mV± 3 .1 6mV ,血浆内和红细胞内的GSH/GSSG比值以及电位值都呈正态分布。血浆和红细胞在 -80℃条件下保存后对GSH和GSSG的测定有一定影响 (p <0 .0 5 )。结论 :本文建立的GSH/GSSG测定方法具有良好的重复性、准确性 ;

植物黄酮对白血病细胞HL-60氧化-还原电位影响

目的观察植物黄酮3′,4′,5′,7′-四羟黄酮(luteolin)和3′-甲氧基,3,7,4′-三羟黄酮(geraldol)对白血病细胞HL-60氧化-还原电位的影响。方法四甲基偶氮噻唑蓝(MTT)法检测细胞活力变化;邻苯二醛(POT)比色法测定胞内还原型谷胱甘肽(GSH)和氧化型谷胱甘肽(GSSG)水平,计算GSH/GSSG及氧化-还原电位。结果10μmol/L的luteolin或Geraldol作用0h时细胞氧化-还原电位为-(295.5±31.2)mV,随后逐渐升高,分别作用4和2h后达到-(278.6±28.7)和-(279.6±26.3)mV,与对照组比较,差异有统计学意义(P<0.05);10μmol/LNAC干预能够降低luteolin和geraldol对HL-60细胞的增殖抑制效应,干预后其24h增殖抑制率分别由(25.4±1.8)%,(21.8±1.5)%降低至(16.8±1.1)%,(12.1±1.0)%,差异有统计学意义(P<0.05)。结论luteolin和ger-aldol能够明显升高HL-60细胞的氧化-还原电位,降低其GSH水平,可能在其抗肿瘤机制中发挥作用。

超氧化物阴离子自由基对菌斑牙面氧化还原电位的影响

目的：验证牙菌斑中超氧化物阴离子自由基与菌斑氧化还原电位的关系。方法：①测试菌斑氧化还原电位。②利用ＳＯＤ作为干扰因素观察氧化还原电位的变化。结果：菌斑电位低于非菌斑牙面电位，为负电位。菌斑加ＳＯＤ后使菌斑电位升高。结论：菌斑负电位与超氧化物阴离子自由基有关，自由基可能是菌斑负电位形成的主要因素。

污水氧化还原电位及总固体含量的在线监测初探

污水的氧化还原电位及总固体含量是化学需氧量及生物需氧量的基础,关系着污水处理工艺条件选择,制约污水处理效果,影响处理时间及絮凝剂用量,尽管其基础数据非常重要但目前尚未实现在线监测。研究对比了去极化测定法和铂电极直接测定法在污水氧化还原电位测定中的优劣,并实验验证了泥浆密度计在测定污水总固体含量中的可行性。试验发现:测定污水氧化还原电位时两种方法的准确度和测定时效均较为理想,但去极化法响应时间短,可作为其在线测定的优选方法。污水固形物含量测定中,泥浆密度计所测结果与常规测定情况切合度较高,也能够实现原位在线测定,符合在线监测的要求。所选择的去极化测定法和泥浆密度计法均具有测量准确,简便易操作的优点,可作为在线监测的优选方案。

栲胶法脱硫过程中电位变化的研究

采用氧化还原电位法,分别考察了氧化栲胶(Teos)制备过程及Teos次氮基三乙酸络合铁、TeosMnSO4和TeosNaVO33种栲胶脱硫液在整个脱硫过程中电位的变化关系。结果表明:氧化栲胶制备过程中原料液电位随反应时间进行而增加,制备完毕,电位基本不变;脱硫液电位随pH的增加而线性降低;在氧化再生过程中脱硫液电位随氧化的进行先缓慢增加然后经过一个突跃后趋向平缓;在析硫过程中脱硫液电位均与H2S浓度的对数成线性关系,超硫容时电位下降速度变大。可以利用电位法来指导脱硫生产。

Influence of transition metal modification of oxide-derived Cu electrodes in electroreduction of CO_2

The modification of oxide-derived Cu electrode with Ni, Zn, and Au was examined to improve the catalytic activity of COz electroreduction. The experimental results showed that Ni modification increased the Faraday efficiency of the formation of formic acid and n-propanol. The Faraday effi- ciency relating to the formation of the liquid products was as high as 34.3% at -1.5 V versus the saturated calomel electrode reference potential. In contrast, modification with Zn reduced the for- mic acid formation efficiency but enhanced the alcohol formation efficiency. Finally, modification with Au suppressed the selectivity toward the formation of both formic acid and alcohols.

Nitrite Accumulation during the Denitrification Process in SBR for the Treatment of Pre-treated Landfill Leachate

The nitrite accumulation in the denitrification process is investigated with sequencing batch reactor （SBR） treating pre-treated landfill leachate in anoxic/anaerobic up-flow anaerobic sludge bed I（UASB）. Nitrite accumulates obviously at different initial nitrate concentrations （64.9,54.8,49.3 and 29.5 mg·L^-1 ） and low temperatures, and the two break points on the oxidation-reduction potential （ORP） profile indicate the completion of nitrate and nitrite reduction. Usually, the nitrate reduction rate is used as the sole parameter to characterize the denitrification rate, and nitrite is not even measured. For accuracy, the total oxidized nitrogen （nitrate ＋ nitrite） is used as a measure, though details characterizing the process may be overlooked. Additionally, batch tests are conducted to investigate the effects of C/N ratios and types of carbon sources on the nitrite accumulation during the denitrification. It is observed that carbon source is sufficient for the reduction of nitrate to nitrite, but for further reduction of nitrite to nitrogen gas, is deficient when C/N is below the theoretical critical level of 3.75 based on the stoichiometry of denitrification. Five carbon sources used in this work, except for glucose, may cause the nitrite accumulation. From experimental results and cited literature, it is concluded that Alcaligene species may be contained in the SBR activated-sludge system.

Grey relational analysis on the relation between marine environmental factors and oxidation-reduction potential

The effects of marine environmental factors-temperature （T）, dissolved oxygen （DO）, salinity （S） and pH--on the oxidation-reduction potential （ORP） of natural seawater were studied in laboratory. The results show an indistinct relationship between these four factors and the ORE but they did impact the ORP. Common mathematical methods were not applicable for describing the relationship. Therefore, a grey relational analysis （GRA） method was developed. The degrees of correlation were calculated according to GILA and the values of T, pH, DO and S were 0.744, 0.710, 0.692 and 0.690, respectively. From these values, the relations of these factors to the ORP could be described and evaluated, and those of T and pH were relatively major. In general, ORP is influenced by the synergic effect of T, DO, pH and S, with no single factor having an outstanding role.

Kinetics and Modeling of Chemical Leaching of Sphalerite Concentrate Using Ferric Iron in a Redox-controlled Reactor

This work presents a study for chemical leaching of sphalerite concentrate under various constant Fe3+ concentrations and redox potential conditions. The effects of Fe3+ concentration and redox potential on chemical leaching of sphalerite were investigated. The shrinking core model was applied to analyze the experimental results. It was found that both the Fe3+ concentration and the redox potential controlled the chemical leaching rate of sphalerite. A new kinetic model was developed, in which the chemical leaching rate of sphalerite was proportional to Fe3+ concentration and Fe3+ /Fe2+ ratio. All the model parameters were evaluated from the experimental data. The model predictions fit well with the experimental observed values.

Effect of Sludge Retention Time on Nitrite Accumulation in Real-time Control Biological Nitrogen Removal Sequencing Batch Reactor

In this study,four sequencing batch reactors(SBR),with the sludge retention time(SRT)of 5,10,20 and 40 d,were used to treat domestic wastewater,and the effect of SRT on nitrite accumulation in the biological nitrogen removal SBR was investigated.The real-time control strategy based on online parameters,such as pH,dissolved oxygen(DO)and oxidation reduction potential(ORP),was used to regulate the nitrite accumulation in SBR. The model-based simulation and experimental results showed that with the increase of SRT,longer time was needed to achieve high level of nitritation.In addition,the nitrite accumulation rate(NAR)was higher when the SRT was relatively shorter during a 112-day operation.When the SRT was 5 d,the system was unstable with the mixed liquor suspended solids(MLSS)decreased day after day.When the SRT was 40 d,the nitrification process was significantly inhibited.SRT of 10 to 20 d was more suitable in this study.The real-time control strategy combined with SRT control in SBR is an effective method for biological nitrogen removal via nitrite from wastewater.

On-line Monitoring for Phosphorus Removal Process and Bacterial Community in Sequencing Batch Reactor

For efficient energy consumption and control of effluent quality, the cycle duration for a sequencing batch reactor (SBR) needs to be adjusted by real-time control according to the characteristics and loading of waste-water. In this study, an on-line information system for phosphorus removal processes was established. Based on the analysis for four systems with different ecological community structures and two operation modes, anaerobic-aerobic process and anaerobic-anaerobic process, the characteristic patterns of oxidation-reduction potential (ORP) and pH were related to phosphorous dynamics in the anaerobic, anoxic and aerobic phases, for determination of the end of phosphorous removal. In the operation mode of anaerobic-aerobic process, the pH profile in the anaerobic phase was used to estimate the relative amount of phosphorous accumulating organisms (PAOs) and glycogen accumulat-ing organisms (GAOs), which is beneficial to early detection of ecology community shifts. The on-line sensor val-ues of pH and ORP may be used as the parameters to adjust the duration for phosphorous removal and community shifts to cope with influent variations and maintain appropriate operation conditions.

Effect of Return Sludge Pre-concentration on Biological Phosphorus Removal in a Novel Oxidation Ditch

A pilot-scale,pre-anoxic-anaerobic oxidation ditch was used in this study to treat municipal wastewater with limited carbon source.A novel return activated sludge(RAS) pre-concentration tank was adopted for improv-ing the phosphorus removal efficiency and the effects of RAS pre-concentration ratio were studied.Under the opti-mal operational condition,the suspended total phosphorus(STP) and the total phosphorus(TP) removal efficiencies were around 58.9% and 63.9% respectively and the effluent-P was lower than 0.8 mg·L-1.The reason is that with the optimal RAS pre-concentration ratio,nitrate is completely removed with endogenous carbon source and the secondary phosphorus release is strictly restrained in the pre-anoxic tank.Therefore,the anaerobic phosphorus release and the carbon source uptake by phosphorus accumulation organisms(PAOs) in the sludge,which are ex-tremely important to the phosphorus removal process,can be fully satisfied.Furthermore,the oxidation-reduction potential is proved to be suitable for controlling the RAS pre-concentration ratio due to influent fluctuation and varied conditions.The novel modified system is also beneficial for PAO accumulation.

Influence of L-Cysteine Concentration on Oxidation-reduction Potential and Biohydrogen Production

The effects of L-cysteine concentration on biohydrogen production by Enterobacterium Bacterium M580 were investigated in batch cultivation.The experimental results showed that L-cysteine could enhance the cell growth,hydrogen production rate and hydrogen yield when its concentration was less than 500 mg·L-1,while it had negative effects when its concentration was higher than 500 mg·L-1.The hydrogen production was the highest 1.29 mol·mol-1(H2/glucose) when 300 mg·L-1L-cysteine was added into the culture,and the yield was 9.4% higher than that in the control.The oxidation-reduction potential(ORP) ,which was influenced by L-cysteine,also affected hydrogen production.The ORP values were in the range-300 mV to-150 mV when the L-cysteine concentration was higher than 500 mg·L-1.Although the ORP in this range was favorable for hydrogen production,it was not suitable for the biomass growth.Hence,less hydrogen was produced.When the L-cysteine concentration was lower than 500 mg·L-1,the ORP was more suitable for both biomass growth and hydrogen production.In addition,at least 91%glucose was consumed when L-cysteine was added to the culture media,compared to the 97.37% consumption without L-cysteine added.

Bioleaching of chalcopyrite with Acidianus manzaensis YN25 under contact and non-contact conditions

In order to investigate the contributions of contact and non-contact cells of Acidianus manzaensis(A.manzaensis) YN25 to the bioleaching of chalcopyrite,three experiments were carried out in the modified shake flasks.The redox potential,pH,cell density,copper and iron ions in the solution were monitored,and the morphological feature and chemical composition of the leached residues were analyzed.The highest leaching efficiency of Cu and Fe was reached in the experiment where the A.manzaensis YN25 could contact the surface of the chalcopyrite.There was no precipitation of jarosite in the leached residues of three experiments,but there was elemental sulfur in the leached residues when the cells could not contact the chalcopyrite.From these results,it is apparent that the leaching of the chalcopyrite is the cooperative action of the contact and non-contact A.manzaensis YN25.

Derivation of the Equation Nernst-Aibassov in a Magnetic Field

The influence of magnetic field on the redox potentials of the Nernst equation. The author offered the new formula Nernst equation in a magnetic field. Our proposed formula takes into account the influence of the magnetic field on the redox processes.

La-doped TiO_(2) nanorods toward boosted electrocatalytic N_(2)-to-NH_(3)conversion at ambient conditions

Electrochemical N_(2) reduction provides a green and sustainable alternative to the Haber-Bosch technology for NH_(3 )synthesis.However,the extreme inertness of N_(2) molecules is a formidable challenge,which requires the development of an active electrocatalyst to drive the N_(2) reduction reaction(NRR)for NH_(3) production at ambient conditions.Herein,we demonstrate the development of La-doped TiO_(2) nanorods as an efficient NRR electrocatalyst for ambient NH3 synthesis.The optimized La-TiO_(2) catalyst offers a large NH_(3) yield of 23.06 pg h1 mgcat 1 and a high Faradaic efficiency of 14.54%at-0.70 V versus reversible hydrogen electrode in 0.1 M L1CIO_(4),outperforming most La-and Ti-based catalysts reported before.Significantly,it also demonstrates high electrochemical stability and its activity decay is negligible after 48 h test.The mechanism is further revealed by density functional theory calculations.

Iron-incorporated nitrogen-doped carbon materials as oxygen reduction electrocatalysts for zinc-air batteries

The application of electrocatalysts for the oxygen reduction reaction(ORR) is vital in a variety of energy conversion technologies. Exploring low-cost ORR catalysts with high activity and long-term stability is highly desirable, although it still remains challenging. Herein, we report a facile and reliable route to convert ZIF-8 modified by Fe-phenanthroline into Fe-incorporated and N-doped carbon dodecahedron nanoarchitecture(Fe-NCDNA), in which carbon nanosheets are formed in situ as the building blocks with uniform Fe-N-C species decoration. Systematic electrochemical studies demonstrate that the as-synthesized Fe-NCDNA electrocatalyst possesses highly attractive catalytic features toward the ORR in terms of activity and durability in both alkaline and neutral media. The Zn-air battery with the optimal Fe-NCDNA catalyst as the cathode performs impressively, delivering a power density of 184 m W cm^–2 and a specific capacity of 801 m Ah g^–1;thus, it exhibits great competitive advantages over those of the Zn-air devices employing a Pt-based cathode electrocatalyst.

Phytoremediation of PAH-Contaminated Sediments by Potamogeton Crispus L. with Four Plant Densities

In order to investigate the effect of plant density ofPotamogeton crispus L. on the remediation of sedi- ments contaminated by polycyclic aromatic hydrocarbons, a 54-day experiment with four plant densities （642, 1 604, 2 567 and 3 530 plants/m^2） was conducted. The results showed higher plant density with slower plant growth rate. Surface area per plant was the most sensitive root parameter to plant density. At the end of the 54-day experi- ment, planting P. crispus enhanced the dissipation ratios of phenanthrene and pyrene in sediments by 6.5%-26,2% and 0.95%-13.6%, respectively. The dissipation increment increased with increasing plant density. Plant uptake accounted for only a small portion of the dissipation increments. Furthermore, P. crispus could evidently improve sediment redox potentials, and strong positive correlations between root surface area and the redox potential as well as between the redox potentials and the dissipation ratios of phenanthrene and pyrene were obtained, indicating that the oxygen released by the roots ofP. crispus might be the main mechanism by which P. crispus enhanced the dis- sipation of PAHs in sediments.