Three important factors influencing directly the dissolved oxygen (DO) of river including the outflow, the water temperature and the pH, were used as input parameters to set up a BP neural network based on Levenberg-M...Three important factors influencing directly the dissolved oxygen (DO) of river including the outflow, the water temperature and the pH, were used as input parameters to set up a BP neural network based on Levenberg-Marquant algorithm. The neural network model was proposed to evaluate DO in water. The model contains two parts: firstly, the learning sample is unified; secondly, the neural network is used to train the unified samples to ensure the best node number of hidden layer. The proposed model is applied to assessing the DO concentration of the Yellow River in Lanzhou city. The evaluation result is compared with that by the neural network method and the reported result in Lanzhou city. The comparison result indicates that the performance of the neural network model is practically feasible in the assessment of DO. At the same time, the linear interpolation method can add the number of network's learning sample to improve the prediction precision of the network.展开更多
Cyclic voltammetry was used to investigate the reaction of erythromycin （EM） with dissolved oxygen on gold nanopartiele-modified electrodes prepared via electrodeposition. A well-defined reduction peak at -0.420 V a...Cyclic voltammetry was used to investigate the reaction of erythromycin （EM） with dissolved oxygen on gold nanopartiele-modified electrodes prepared via electrodeposition. A well-defined reduction peak at -0.420 V and a reoxidation peak at -0.055 V were observed. With the addition of EM into the NaOH solution containing dissolved oxygen, the oxidation peak at -0.055 V was still indiscernible. However, a new oxidation peak at 0.200 V appeared, which suggests the interaction between EM and dissolved oxygen. Therefore, this method can be used for the analysis of EM in tablets. The present method is simple, reproducible, and does not require complex analytical instruments.展开更多
碳纤维用做溶氧型海水电池(DO-SWB,Dissolved Oxygen-Seawater Battery)正极材料已取得商业化应用,但海水中溶解氧浓度低和材料氧还原反应(ORR,oxygen reduction reaction)活性低制约着电池功率密度的提高,炭材料的氮掺杂近年来备受关...碳纤维用做溶氧型海水电池(DO-SWB,Dissolved Oxygen-Seawater Battery)正极材料已取得商业化应用,但海水中溶解氧浓度低和材料氧还原反应(ORR,oxygen reduction reaction)活性低制约着电池功率密度的提高,炭材料的氮掺杂近年来备受关注。本工作以苯胺为氮源,采用一步法在苯胺(An,Aniline)和硫酸混合液中对聚丙烯腈碳纤维(PAN-CF,Polyacrylonitrile-based Carbon Fiber)进行电化学处理,调控工艺条件制备掺氮电极。采用扫描电镜(SEM,Scanning Electron Microscope)、拉曼光谱(Raman,Raman spectrum)和X射线光电子能谱(XPS,Xray Photoelectron Spectroscope)进行表征,结合电化学测试方法对电极表面特征及ORR活性评价,并对作用机理分析。电化学改性使碳纤维表面产生缺陷并生成吡啶类官能团,有效调控了炭材料的电子结构,增加了电极表面活性位点的数量,改善了氧的吸附和电荷转移能力,使掺氮后电极具有优良的ORR性能。其中,最佳性能电极ORR起始电位为-0.12 V vs SCE,在-0.4 V vs SCE下比电流密度达510 mA/g,作为溶氧型海水电池正极具有可期的应用前景。展开更多
文摘Three important factors influencing directly the dissolved oxygen (DO) of river including the outflow, the water temperature and the pH, were used as input parameters to set up a BP neural network based on Levenberg-Marquant algorithm. The neural network model was proposed to evaluate DO in water. The model contains two parts: firstly, the learning sample is unified; secondly, the neural network is used to train the unified samples to ensure the best node number of hidden layer. The proposed model is applied to assessing the DO concentration of the Yellow River in Lanzhou city. The evaluation result is compared with that by the neural network method and the reported result in Lanzhou city. The comparison result indicates that the performance of the neural network model is practically feasible in the assessment of DO. At the same time, the linear interpolation method can add the number of network's learning sample to improve the prediction precision of the network.
基金Project(2005037207) supported by Postdoctoral Science Foundation of China
文摘Cyclic voltammetry was used to investigate the reaction of erythromycin （EM） with dissolved oxygen on gold nanopartiele-modified electrodes prepared via electrodeposition. A well-defined reduction peak at -0.420 V and a reoxidation peak at -0.055 V were observed. With the addition of EM into the NaOH solution containing dissolved oxygen, the oxidation peak at -0.055 V was still indiscernible. However, a new oxidation peak at 0.200 V appeared, which suggests the interaction between EM and dissolved oxygen. Therefore, this method can be used for the analysis of EM in tablets. The present method is simple, reproducible, and does not require complex analytical instruments.
文摘碳纤维用做溶氧型海水电池(DO-SWB,Dissolved Oxygen-Seawater Battery)正极材料已取得商业化应用,但海水中溶解氧浓度低和材料氧还原反应(ORR,oxygen reduction reaction)活性低制约着电池功率密度的提高,炭材料的氮掺杂近年来备受关注。本工作以苯胺为氮源,采用一步法在苯胺(An,Aniline)和硫酸混合液中对聚丙烯腈碳纤维(PAN-CF,Polyacrylonitrile-based Carbon Fiber)进行电化学处理,调控工艺条件制备掺氮电极。采用扫描电镜(SEM,Scanning Electron Microscope)、拉曼光谱(Raman,Raman spectrum)和X射线光电子能谱(XPS,Xray Photoelectron Spectroscope)进行表征,结合电化学测试方法对电极表面特征及ORR活性评价,并对作用机理分析。电化学改性使碳纤维表面产生缺陷并生成吡啶类官能团,有效调控了炭材料的电子结构,增加了电极表面活性位点的数量,改善了氧的吸附和电荷转移能力,使掺氮后电极具有优良的ORR性能。其中,最佳性能电极ORR起始电位为-0.12 V vs SCE,在-0.4 V vs SCE下比电流密度达510 mA/g,作为溶氧型海水电池正极具有可期的应用前景。
