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941.
Anode electrodes play a key role in generating electricity from microbial fuel cells (MFCs) because they directly affect microbial activities. This communication reports the preparation of nitrogen-doped carbon nanotubes with a bamboo-like nanostructure (Bamboo-NCNTs) by catalytic pyrolysis of ethylene diamine and application of the Bamboo-NCNTs as anode-modifying materials in MFCs. The Bamboo-NCNTs significantly improved performance of an MFC in current production and power output, and reduced internal resistance of the anode compared with conventional CNTs-modified and unmodified anodes. The improved performance could be attributed to the increased active sites induced by multiple joint structures and enhanced biocompatibility originated from nitrogen dopant. 相似文献
942.
采用AA3连续流动元素分析仪对不同冰冻时间的标准水样和自然水样的总氮含量进行了测定。结果表明.供试水样在-20℃条件下冰冻30d的总氮浓度稳定,但自然水样较标准水样波动幅度大。 相似文献
943.
通过分光光度法测定了亚硝酸盐氮的含量,并从培养条件优化和游离氨抑制作用两方面考察了河底活性淤泥对水体中亚硝酸盐氮的生物降解情况;在最佳条件下,河水中亚硝酸盐氮的降解在2天内降解率可达83.7%. 相似文献
944.
The elution by characteristic points (ECP) method is a very rapid and precise method for determination of the phase system equilibrium of phase systems in broad solute concentration ranges. Thus, the method is especially suitable for rapid characterization of high efficient separation systems. One important source of error, the effects by the post-loop dispersion, was eliminated in a recent investigation. In this study, the systematic error caused by the selection of the integration starting point at concentration equal to 0 is eliminated. This is done by developing and validating a new procedure for isotherm data generation; the ECP-slope method. The method generates raw slope data of the adsorption isotherm instead of raw adsorption data by integrations as the classical ECP does. Both numerical and experimental data were used for the comparison of the classical ECP approach with the slope-ECP method. 相似文献
945.
A. Stathopoulos P. Klonos P. Pissis J.C. Rodriguez Hernández J.L. Gómez Ribelles 《European Polymer Journal》2010,46(1):101-59
This work probes the hydration properties and molecular dynamics of hybrid poly(hydroxyethyl-co-ethyl acrylate)/silica hydrogels. Two series of hybrid copolymers were prepared by simultaneous polymerization and silica preparation by sol-gel method, the first with hydroxyethyl acrylate/ethyl acrylate (HEA/EA) composition at 100/0, 90/10, 70/30, 50/50, 30/70, 10/90 and fixed silica content at 20 wt.%, and the second with fixed HEA/EA organic composition at 70/30 and 0, 5, 10 and 20 wt.% of silica. The hydration properties of these systems were studied at 25 °C by exposure to several controlled water vapor atmospheres (water activities 0-0.98) in sealed jars and by immersion in distilled water. Finally, the molecular dynamics of the hydrated hybrids at several levels of hydration was probed with Thermally Stimulated Depolarization Currents (TSDC) in the temperature interval between −150 and 20 °C. The results indicate that a critical region of silica content between 10 and 20 wt.% exists, above which silica is able to form an inorganic network. This silica network prevents the expansion of water clusters inside the hydrogels and subsequently the total stretching of the polymer network without obstructing the water sorption at the first stages of hydration from the dry state. As concerns the copolymer composition, the presence of EA reduces water sorption and formation of water clusters affecting directly to the hydrophilic regions. The TSDC thermograms reveal the presence of a single primary main broad peak denoted as αcop relaxation process, which is closely related to the copolymer glass transition, and of a secondary relaxation process denoted as βsw relaxation, which originates from the rotational motions of the lateral hydroxyl groups with attached water molecules. The single αcop implies structural homogeneity at the nanoscale in HEA-rich samples (xHEA > 0.5), while for high EA content (xEA ? 0.5) phase separation is detected. Both relaxation processes show strong dependence on water content and organic phase composition. 相似文献
946.
Leonid Asnin Fabrice Gritti Krzysztof Kaczmarski Georges Guiochon 《Journal of chromatography. A》2010,1217(3):264-275
Using elution chromatography, we studied the adsorption mechanism of the Naproxen enantiomers on the chiral stationary phase (S,S)-Whelk-O1, from buffered methanol–water solutions. We propose an adsorption mechanism that assumes monolayer adsorption of the more retained enantiomer and the associative adsorption of the less retained one. The effects of the mobile phase composition on the adsorption of Naproxen are discussed. The combination of an elevated column temperature and of the use of an acidic mobile phase led to the degradation of the column and caused a major loss of its separation ability. The use of a moderately acidic mobile phase at temperature slightly above ambient did not produce rapid severe damages but, nevertheless, hampered the experiments and caused a slow gradual deterioration of the column. 相似文献
947.
Tilman Barz Verena Löffler Harvey Arellano-Garcia Günter Wozny 《Journal of chromatography. A》2010,1217(26):4267-4277
In this work, parameters of the steric mass-formalism SMA are optimally ascertained for a reliable determination of the adsorption isotherms of β-lactoglobulin A and B under non-isocratic conditions. For this purpose, static batch experiments are used in contrast to the protocols based on different experimental steps, which use a chromatographic column. It is shown that parameters can already be determined for a small number of experiments by using a systematic procedure based on optimal model-based experimental design and an efficient NLP-solver. The in different works observed anti-Langmuir shape of the isotherm for small concentrations of β-lactoglobulin A was corroborated. Moreover, we also found indications for a porosity variation with changing protein concentrations. 相似文献
948.
Rodrigo S. Bitzer Ana Maria Rocco Paulo Sérgio Santos Carlos A.L. Filgueiras 《Journal of organometallic chemistry》2006,691(9):2005-2013
The reaction between cis-[Mo(CO)4(piperidine)2] and 2,3,5,6-tetrakis(α-pyridyl)pyrazine (TPP) in the 3:1 (Mo:TPP) stoichiometric ratio afforded the organobimetallic compound {[Mo(CO)4]2(μ-TPP)} (1) in 89% yield. This complex has been characterized by elemental and thermogravimetric analyses, vibrational (FT-IR and FT-Raman) and electronic spectroscopy, and 1H and 13C-CP/MAS NMR spectroscopy. NMR data have revealed that TPP coordinates to each metal at two adjacent pyridine nitrogen atoms, according to a rare bis-bidentate chelating mode. The cyclic voltammogram of 1 in DMF has shown an irreversible metal-based oxidation at +0.77 V versus SCE. A DFT/B3LYP study of two plausible molecular structures for 1 has been carried out in vacuum using the LACV3P(d,p) and LACV3P++(d,p) basis sets. This theoretical study has pointed to the structure with the Mo(CO)4 moieties on opposite sides with respect to the pyrazine ring (trans isomer - C2h symmetry) as the most stable one. The vibrational frequencies of the trans structure have been calculated at the B3LYP/LACV3P(d,p) level and compared with the FT-IR and FT-Raman spectra of 1. An excellent agreement between experimental and calculated frequencies was obtained. 相似文献
949.
Yohan D.M. Champouret 《Tetrahedron》2006,62(1):79-89
The new tin reagents, 2-(n-Bu3Sn)-6-{C(R)OCH2CH2O}-C5H3N, (R=H a, Me b), have been employed in Stille-type cross-coupling reactions with a range of oligopyridylbromides generating, following a facile deprotection step, a series of formyl- and acetyl-functionalised oligopyridines. Condensation reactions with 2,6-diisopropylaniline has allowed access to families of novel sterically bulky multidentate N,N,N,N (tetradentate), N,N,N,N,N (pentadentate), N,N,N,N,N,N (sexidentate) and N,N,N,N,N,N,N (heptadentate) nitrogen donor ligands. This work represents a straightforward and rapid synthetic route for the preparation of oligopyridylimines, which are expected to act as useful components for the self-assembly of polymetallic complexes. 相似文献
950.