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51.
Justin C. TokashBruce E. Logan 《International Journal of Hydrogen Energy》2011,36(16):9439-9445
There is great interest in hydrogen evolution in bioelectrochemical systems, such as microbial electrolysis cells (MECs), but these systems require non-optimal near-neutral pH conditions and the use of low-cost, non-precious metal catalysts. Here we show that molybdenum disulfide (MoS2) composite cathodes have electrochemical performance superior to stainless steel (SS) (currently the most promising low-cost, non-precious metal MEC catalyst) or Pt-based cathodes in phosphate or perchlorate electrolytes, yet they cost ∼4.5 times less than Pt-based composite cathodes. At current densities typical of many MECs (2-5 A/m2), the optimal surface density with MoS2 particles on carbon cloth was 25 g/m2, achieving 31 mV less hydrogen evolution overpotential than similarly constructed Pt cathodes in galvanostatic tests with a phosphate buffer. At higher current densities (8-10 A/m2) the MoS2 catalyst had 82 mV less hydrogen evolution overpotential than the Pt-based catalyst. MoS2 composite cathodes performed similarly to Pt cathodes in terms of current densities, hydrogen production rates and COD removal over several batch cycles in MEC reactors. These results show that MoS2 can be used to substantially reduce the cost of cathodes used in MECs for hydrogen gas production. 相似文献
52.
Precombustion chambers (PCCs) are an ignition technology for large bore, natural gas engines enabling increased combustion stability while extending the lean limit of operation. A PCC is a small chamber, typically 1–2% of the clearance volume, in which a near-stoichiometric mixture of fuel and air is ignited by a standard spark plug. After the mixture in the PCC is ignited, its pressure rises and expels a flame jet of hot gas mixture into the main chamber. The amount of energy a typical PCC produces is roughly one million times that of a conventional spark plug. In this work the role that the PCC plays in the formation of oxides of nitrogen (NOx) is investigated. Previous research indicates that the PCC is responsible for a significant part of engine-out NOx, especially near the lean limit of engine operation. Experimental results are presented from a large bore lean-burn 2-stroke cycle engine. The data shows that the PCC is responsible for a significant part of engine-out NOx emissions. However, the PCC NOx does not form in the PCC. Rather it forms within the gas jet after it penetrates into the main chamber combustion gases. 相似文献
53.
Rudrappa T Bonsall J Gallagher JL Seliskar DM Bais HP 《Journal of chemical ecology》2007,33(10):1898-1918
Phragmites australis is considered the most invasive plant in marsh and wetland communities in the eastern United States. Although allelopathy
has been considered as a possible displacing mechanism in P. australis, there has been minimal success in characterizing the responsible allelochemical. We tested the occurrence of root-derived
allelopathy in the invasiveness of P. australis. To this end, root exudates of two P. australis genotypes, BB (native) and P38 (an exotic) were tested for phytotoxicity on different plant species. The treatment of the
susceptible plants with P. australis root exudates resulted in acute rhizotoxicity. It is interesting to note that the root exudates of P38 were more effective
in causing root death in susceptible plants compared to the native BB exudates. The active ingredient in the P. australis exudates was identified as 3,4,5-trihydroxybenzoic acid (gallic acid). We tested the phytotoxic efficacy of gallic acid on
various plant systems, including the model plant Arabidopsis thaliana. Most tested plants succumbed to the gallic acid treatment with the exception of P. australis itself. Mechanistically, gallic acid treatment generated elevated levels of reactive oxygen species (ROS) in the treated
plant roots. Furthermore, the triggered ROS mediated the disruption of the root architecture of the susceptible plants by
damaging the microtubule assembly. The study also highlights the persistence of the exuded gallic acid in P. australis’s rhizosphere and its inhibitory effects against A. thaliana in the soil. In addition, gallic acid demonstrated an inhibitory effect on Spartina alterniflora, one of the salt marsh species it successfully invades.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
54.
Justin Salminen Peter Blomberg Jarno Mäkinen Lea Räsänen 《American Institute of Chemical Engineers》2015,61(9):2739-2748
Mining and metals processing are not invisible activities and are heavy industries, which require energy, water, chemicals, and land area. Recently more emphasis is given to environmental and societal aspects in mining and processing. Development of good practices with improved resource efficiency, new recovery methods and sustainability thinking are increasingly required. This work shows pH titration method for acid mine drainage (AMD) water incorporated with aqueous thermodynamic model for selective metals precipitation from complex solution. Also two examples on gold recovery methods from aqueous streams are shown: biosorption using fungal matter and solvent extraction using a task‐specific ionic liquid. By understanding chemical thermodynamics and natural phenomena, there is a better chance of developing solutions for environmental problems and new industrial processes. © 2015 American Institute of Chemical Engineers AIChE J, 61: 2739–2748, 2015 相似文献
55.
Polybrominated diphenyl ethers in the sediments of the Great Lakes. 3. Lakes Ontario and Erie 总被引:2,自引:0,他引:2
Song W Ford JC Li A Sturchio NC Rockne KJ Buckley DR Mills WJ 《Environmental science & technology》2005,39(15):5600-5605
Sediment cores were taken in 2002 in Lakes Ontario and Erie at four locations. A total of 48 sediment samples were characterized, dated using 210Pb, and analyzed for 10 congeners of polybrominated diphenyl ethers (PBDEs) including BDE209 as well as 39 congeners of polychlorinated biphenyls (PCBs). The surficial concentrations of nine tri- through hepta-BDE congeners (sigma9PBDE) are 4.85 and 6.33 ng g(-1), at sampling sites ON40 and ON30 in Lake Ontario, and 1.83 and 1.95 ng g(-1) at ER37 and ER09 in Lake Erie, respectively, based on dry sediment weight. The surficial BDE209 concentrations are 242 and 211 ng g(-1) at ON40 and ON30 and 50 and 55 ng g(-1) at ER37 and ER09. The sigma(9-) PBDEs fluxes to the sediment around 2002 are 147 and 195 pg cm(-2) year(-1) at ON40 and ON30 and 136 and 314 pg cm(-2) year(-1) at ER37 and ER09, respectively. The fluxes of BDE209 are 6.5 and 7.3 ng cm(-2) year(-1) at ON30 and ON40 and 3.7 and 8.9 ng cm(-2) year(-1) at ER37 and ER09, respectively. Dramatic increases in PBDE concentrations and fluxes upward toward the sediment surface and the present time are evident at both locations in Lake Ontario, while PCBs concentrations peak in the middle of sediment cores around the dated time of 1970s and 1960s. For both locations of Lake Erie, the increasing trends of both PBDEs and PCBs from the bottom to the surficial segments were distorted by sediment mixing. BDE209 is the most abundant congener among PBDEs in the sediments, constituting about 96 and 91% of the total PBDEs on mass basis in Lakes Ontario and Erie, respectively. 相似文献
56.
Noshin Omar Hamid Gualous Justin Salminen Grietus Mulder Ahmadou Samba Yousef Firouz Mohamed Abdel Monem Peter Van den Bossche Joeri Van Mierlo 《Journal of Applied Electrochemistry》2014,44(4):509-522
This paper represents an assessment of the main ageing phenomena in electrical double-layer capacitors (EDLCs). In this study the cycle life of the EDLC cells with a rated capacitance of 1,600 F has been investigated at different ambient temperatures and current rates. From the experimental results we can observe that the impact of the high ambient temperature is significant on the cycle life of the cells. Moreover, the results also show the negative impact of the current rate. The internal resistance tests showed that the increase of the resistance is much higher than the decrease of the capacitance. Thus, the ageing of the EDLC during cycling was clearly non-linear. Further the EIS measurements indicated the higher increase of the imaginary part of the impedance at low frequencies during cycling, which indicates the capacitance fade. 相似文献
57.
58.
Given a collection of parameterized multi-robot controllers associated with individual behaviors designed for particular tasks,this paper considers the problem ... 相似文献
59.
60.
Robert Toth Justin Ribault John Gentile Dan Sperling Anant Madabhushi 《Computer Vision and Image Understanding》2013,117(9):1051-1060
In this work we present an improvement to the popular Active Appearance Model (AAM) algorithm, that we call the Multiple-Levelset AAM (MLA). The MLA can simultaneously segment multiple objects, and makes use of multiple levelsets, rather than anatomical landmarks, to define the shapes. AAMs traditionally define the shape of each object using a set of anatomical landmarks. However, landmarks can be difficult to identify, and AAMs traditionally only allow for segmentation of a single object of interest. The MLA, which is a landmark independent AAM, allows for levelsets of multiple objects to be determined and allows for them to be coupled with image intensities. This gives the MLA the flexibility to simulataneously segmentation multiple objects of interest in a new image.In this work we apply the MLA to segment the prostate capsule, the prostate peripheral zone (PZ), and the prostate central gland (CG), from a set of 40 endorectal, T2-weighted MRI images. The MLA system we employ in this work leverages a hierarchical segmentation framework, so constructed as to exploit domain specific attributes, by utilizing a given prostate segmentation to help drive the segmentations of the CG and PZ, which are embedded within the prostate. Our coupled MLA scheme yielded mean Dice accuracy values of .81, .79 and .68 for the prostate, CG, and PZ, respectively using a leave-one-out cross validation scheme over 40 patient studies. When only considering the midgland of the prostate, the mean DSC values were .89, .84, and .76 for the prostate, CG, and PZ respectively. 相似文献