Optimization of the sputter-deposited platinum cathode for a direct methanol fuel cell

The electrodes prepared by a sputtering method were evaluated as the cathodes for direct methanol fuel cells (DMFCs). Pt loading below 0.25 mg cm⁻² achieved higher mass activities than that of 0.5 mg cm⁻² prepared by the paste method, which was general conventional method. However, an increase in Pt loading reduced the catalyst activity for the oxygen reduction reaction (ORR). This result may suggest an increase in only electrochemically inactive Pt. Pt utilization efficiency can be found about ten times higher at Pt loading of 0.04 mg cm⁻². Moreover, addition of Nafion to sputter-deposited Pt cathodes is found possible to improve the catalyst activity for the ORR, but the excess Nafion over the optimum condition reduces the active sites.     

Hydrogen Yield from Low Temperature Steam Reforming of Ethanol

Low temperature steam reforming of ethanol in the temperature range of 200–360°C was studied to maximize the production of H₂. The optimum reaction conditions in presence of a suitable catalyst can produce mainly the desired products H₂ and CO₂. Cu/Al₂O₃ catalysts with six different concentrations ranging from 0 to 10 wt.% Mn, were prepared, characterized and studied for the ethanol-steam reforming reaction. Maximum ethanol conversion of 60.7% and hydrogen yield of 3.74 (mol H₂ / mol ethanol converted) were observed at 360°C for catalyst with 2.5 wt.% Mn loading.     

Oil and fat hydrolysis with lipase fromAspergillus sp.

Hydrolysis of olive oil, soybean oil, mink fat, lard, palm oil, coconut oil, and a hydrogenated, hardened oil with lipase from anAspergillus sp. has been studied. The lipase had high specific activity (60,000 U/g) and did not show any positional specificity. The lipase proved to be a more effective catalyst than Lipolase fromA. oryzae, with an optimal activity at 37°C and pH 6.5–7.0. It was activated by Ca²⁺ but inactivated by organic solvents such as isopropanol and propanone. All substrates examined could be hydrolyzed to corresponding fatty acids with this enzyme at concentrations of 5–30 U/meq with yields of 90–99% in 2–24 h. The degree of hydrolysis was almost logarithmically linear with reaction time and occurred in two stages. The lipase was stable and could be repeatedly recycled for hydrolysis.     

Low-temperature catalytic combustion of methane over MnO x –CeO2 mixed oxide catalysts: Effect of preparation method

The effect of preparation method on MnO _x –CeO₂ mixed oxide catalysts for methane combustion at low temperature was investigated by means of BET, XRD, XPS, H₂-TPR techniques and methane oxidation reaction. The catalysts were prepared by the conventional coprecipitation, plasma and modified coprecipitation methods, respectively. It was found that the catalyst prepared by modified coprecipitation was the most active, over which methane conversion reached 90% at a temperature as low as 390 °C. The XRD results showed the preparation methods had no effect on the solid solution structure of MnO _x –CeO₂ catalysts. More Mn⁴⁺ and richer lattice oxygen were found on the surface of the modified coprecipitation prepared catalyst with the help of XPS analysis, and its reduction and BET surface area were remarkably promoted. These factors could be responsible for its higher activity for methane combustion at low temperature.     

沉积Ag的TiO_2纳米管的制备及其光催化性能的研究

采用电化学阳极氧化法制备了管长约为1.48μm,管径约为87 nm的Ti O2纳米管,然后采用光还原沉积法在不同浓度的AgNO3溶液中制备了沉积单质Ag的Ti O2纳米管.利用SEM,XRD和XPS对Ag-Ti O2纳米管进行了表征,并以罗丹明B溶液为目标降解物评价了其光催化活性.结果表明:Ag微粒是以稳定的单质形式存在,Ag-Ti O2纳米管的光催化活性随着AgNO3溶液浓度的增大而呈增大的趋势,当AgNO3浓度达到0.08 mol/L时其活性达到最大值,而后随着浓度的增大活性反而下降.     

取代苯甲酸对植物生长调节活性的拓扑QSAR研究

应用分子图形学技术计算了13种取代苯甲酸的新型分子连接性指数(mXtv)及电性拓扑指数(En).基于向前逐步回归方法,建立了取代苯甲酸对植物生长的调节活性(pC)与4Xpcv、E16、E40的最佳相关模型,其相关系数为0.947,显示高度拟合性与强的预测能力.该模型经Jackknife法检验,具有可靠性与稳健性.     

Characterization of NOM and THM formation potential in eutrophic reservoir water

Resin adsorption technique with XAD-8 and XAD-4 was used to characterize the raw water from Erlong reservoir in Jilin province of China. The NOM chemical composition sequences of four organic fractions in the raw water,from high to low,are fulvic acid (FA) fraction,hydrophilic non-acid (HPINA) fraction,hydrophilic acid (HPIA) fraction,and humic acid (HA) fraction. Experimental results show that FA is the main precursor of THMFP among the four organic fractions. However,HA or hydrophobic acid exhibits the highest chlorination activity in forming THMs. It is also found that the value of FI/DOC or SUVA and the specific THMFP have better positive correlation. It is implied that certain source water has unique nature of NOM and DBPs.     

Inhibitory effect of Cr（Ⅵ） on activities of soil enzymes

To evaluate the influence of various Cr(VI) concentrations (0.05, 0.25, 0.50, 1.00 and 2.00 g/kg) on the activity of soil enzymes, the activities of catalase, polyphenol oxidase, dehydrogenase, alkaline phosphatase in soils were investigated in the incubation experiment with a period of 35 d. The results indicate that all the tested Cr(VI) concentrations significantly inhibit dehydrogenase activity by over 70% after 35 d. The activity of alkaline phosphatase is slightly inhibited during the whole experiment except for on the day 7. Cr(VI) has no obvious effect on the activity of catalase in soil. On the contrary, Cr(VI) stimulates the activity of polyphenol oxidase. The results suggest that dehydrogenase activity can be used as an indicator for assessing the severity of chromium pollution. Foundation item: Projects(2006AA06Z374, 2007AA021304) supported by the National High-Tech Research and Development Program of China; Project(2008SK2007) supported by the Key Program of Science and Technology of Hunan Province, China     

金属离子对红球菌腈水合酶活力的影响

不同金属离子对红球菌（Rhodococcus sp．）TCCC 28001的生长及其腈水合酶的酶活有着不同程度的影响．菌株TCCC 28001产生的腈水合酶是钴型,且Co^2＋对该腈水合酶诱导激活的最适浓度为10×10^-5mol／L．选择酵母粉中含有且含量波动较大的5种金属离子,考察了在添加10×10^-5 mol／L Co^2＋诱导激活下,5种金属离子对酶活的影响．结果表明：Fe^2＋,Mn^2＋,Mo^6＋,Cu^2＋4种金属离子具有促进作用,Zn^2＋产生轻微抑制作用．6×10^-5mol／L Fe^2＋的促进效果显著,使菌株TCCC 28001的酶活从453U／mL增加到1941U／mL,提高了328％．     

以电炉还原渣重构转炉钢渣的组成与性能

掺加电炉还原渣重构转炉钢渣的组成和结构制备了高胶凝活性的钢渣。采用化学全分析、XRD、SEM等手段分析了钢渣重构前后的组成、水化产物形貌,并进行了力学性能试验。结果表明:重构钢渣矿物组成以活性硅酸二钙、硅酸三钙和七铝酸十二钙等胶凝矿物为主。当电炉还原渣掺量分别为10%和20%、煅烧温度分别为1 350℃和1 250℃时,重构钢渣水泥的活性指数分别为102.9%和104.0%。掺重构钢渣水泥28 d龄期水化产物与普通硅酸盐水泥的相似,但浆体结构更为致密。