底物浓度影响微生物燃料电池性能和生物生长的模拟研究

建立了含有悬浮微生物、电极上生物量、可溶性化学底物和中介体的微生物燃料电池(MFC)数学模型。通过底物降解、生物增长和电流产生过程的模拟,考察了生物量和底物随时间的变化规律,底物质量浓度对生物量、底物降解和电流的影响。结果表明,当溶液中初始微生物量很少时,随着MFC反应的进行,生物主要富集在电极上,溶液中生物生长缓慢;MFC中的生物生长经历延滞期、对数期和平稳期,底物分解经历缓慢、快速和消耗殆尽3个阶段。底物质量浓度小于等于250 mg/L时,生物延滞期时间、底物缓慢分解阶段时间、生物生长到达平稳时间、底物消耗殆尽的时间和电流到达最大值所需的时间随着底物质量浓度的增加而缩短。底物质量浓度大于250 mg/L时,生物延滞期时间、底物缓慢分解阶段时间、生物生长到达平稳时间、底物消耗殆尽的时间和电流到达最大值所需的时间随着底物质量浓度的增加而增加。     

微波污泥上清液为燃料的微生物燃料电池内阻分布

实验采用单室无膜悬浮阴极微生物燃料电池（MFC）,考察了微波污泥上清液为燃料的MFC（MSMFC）的内阻组成。研究表明,当未投加氯化钠时,MSMFC内阻为486．13Ω。当投加100mmol／L的氯化钠时,内阻迅速下降为207．18Ω。而投加量进一步增加时,内阻变化不明显。当阳极面积从4cm2增加到8cm2时,MSMFC内阻从387．34Ω迅速下降到293．96n。而当阳极面积增加到24cm。时,MSMFC内阻变化不明显。但当阳极面积增加到60cm2时,MSMFC内阻下降了38．4％。当阴极面积从24．87cm2增加到49．74cm2时,MSMFC内阻减少了40．4％（从545．72Ω减少到220．56Q）。MSMFC中阳极内阻占主要部分,其次为阴极内阻,电解液电阻最小。随着阴阳极面积比的增加,阴阳极电阻比例减少,说明控制阴阳极面积比可以调整系统内阻的分配。     

Pre-concentration of naturally occurring radionuclides and the determination of (212)Pb from fresh waters

A novel technique has been developed for determining the ²¹²Pb activity of fresh waters. This is of interest to environmental monitoring programmes that utilise gross α-activity methods to screen for anthropogenic radionuclides. The contribution from ²¹²Pb varies, and is difficult to experimentally measure due to its relatively short half-life (t_½ = 10.6 h) and low environmental activity (<0.1 Bq l⁻¹). The use of a three-stage technique that encompasses a unique form of pre-concentration, separation and analysis by liquid scintillation counting allows a lower detection limit of 0.006 Bq l⁻¹ with a chemical yield of 92.5 ± 5.6%. The measurement can be obtained within 7 h of sample collection, and is calculated using the radioactive decay of ²¹²Bi. Other naturally occurring radionuclides may also be extracted using the pre-concentration stage of the technique, with efficiencies above 90% at a range of pH values.     

固相萃取-高效液相色谱-质谱联用法用于地表水中类固醇激素测定

建立了固相萃取-高效液相色谱-质谱联用法对雌三醇、氟哌噻吨、炔雌醇、雄烯二酮、雌二醇、雌酚酮、睾酮共7种类固醇激素的检测方法。样品经C18萃取小柱富集净化,采用内标法定量时,方法的检出限为0.66～1.95 ng/L,R0.998,回收率为78.5%～94.6%,相对标准偏差为1.1%～7.7%。采用该方法对上海市地表水进行测定,在2个采样点中检出雌酚酮(1.88 ng/L)和雄烯二酮(1.48 ng/L)。     

Divestment discourse: war,justice, morality and money

The fossil fuel divestment movement has been a vibrant novel development in climate change politics in recent years, particularly in North America. Here, the character of the discourse used to promote divestment as a strategy is explored. The divestment discourse is shown to rest on four overlapping narratives, those of war and enemies, morality, economics and justice. All four are clearly discernible in statements from movement activists, in coverage of divestment campaigns by major news sources and in the movement’s aims, objectives and strategies covered in alternative media. The war narrative, with the formulation of fossil fuel companies as enemies to be overcome to ensure survival, is the dominant narrative. By polarising climate action and identifying an antagonist against which to mobilise, divestment discourse has articulated climate change as an explicitly political phenomenon, in contrast to the primarily consensus and collaboration-based approaches that have predominated in climate politics.     

A two-dimensional analytical model of PEMFC with dead-ended anode

ABSTRACT

When the proton exchange membrane fuel cell (PEMFC) works in the mode of dead-ended anode (DA), the water and the nitrogen in the cathode flow channel will diffuse, and accumulate, to the anode flow channel resulting in fuel starvation on the anode side as well as the performance degradation of PEMFC, which has an important impact on the durability and working state of PEMFC. Because the PEMFC performance is closely related to the cathode working parameters, in order to study the influence of the cathode working parameters on the performance of the PEMFC with DA, a two-dimensional analytical model of PEMFC with DA is established in this article, and the parameters in the model are corrected by experiments. The effects of humidity, stoichiometric ratio and working pressure of cathode gas on the performance of PEMFC with DA are studied by model and experiment, as well as the effects of these working parameters on the accumulation process and distribution of water vapor and nitrogen on the anode side, and the relative performance of PEMFC with DA under different cathode working parameters is obtained. This model is of great significance to guide the practical work of the PEMFC with DA.     

高水分垃圾焚烧热回收和烟气净化系统的合理布置

用热平衡计算分析了高水分生活垃圾在焚烧前干燥脱水对系统热效率的影响 ,并比较了用不同介质干燥湿垃圾时热回收系统的效率和对烟气净化系统布置的要求。计算表明 :系统产生的可供有效利用的蒸汽量总是随垃圾干燥后应用基水分的降低而上升。采用排烟作为干燥介质时系统热效率也随应用基水分的降低而上升 ;而采用热空气作干燥介质时 ,计算热效率有轻微的下降。采用垃圾干燥应对烟气净化系统进行合理布置。     

某型飞机压力加油控制盒电磁兼容设计

介绍了某型飞机压力加油控制盒,阐述了该型飞机压力加油控制盒采用滤波技术对电磁兼容优化设计的方法和原理,并对原始设计和优化设计的控制盒电源线传导发射（CE102）的试验结果进行了分析比较。     

城市大气污染物对PEMFC性能的影响

论述了城市空气污染物(即阴极气体杂质)对质子交换膜燃料电池(PEMFC)性能的影响。提出了燃料电池汽车(FCV)进入商业化应用时即将面临的一个急待研究的课题。文中综述了CO、CO2、硫化物、碳氢化合物(HC)、氮氧化物(NOx)、NH3、卤素离子(X-)、酸沉降物以及大气颗粒物等对PEMFC性能的影响,同时对解决阴极气体杂质影响的途径进行了分析。