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991.
Liping Chen Sanguo Hong Xiaoping Zhou Zhengping Zhou Haoqing Hou 《Catalysis communications》2008,9(13):2221-2225
Novel Pd-carrying composite carbon nanofibers based on polyacrylonitrile were prepared by electrospinning and carbonization process. The catalytic activities of the composite nanofibers were tested with a Sonogashria coupling reaction of iodobenzene and phenylacetylene in liquid-phase. Transmission electron microscope and X-ray diffraction analyzer were used to characterize the nanofibers and the metal nanoparticles on the fibers; gas chromatograph and nuclear magnetic resonance spectroscopy were used to characterize the product of the testing reaction. The results first showed that the catalyst not only had a high catalytic activity, but also had good leaching-resistance, retrieval and reusability for the Sonogashira reaction. 相似文献
992.
PTFE-F-PbO2 电极在H2SO4溶液中的析氧行为 总被引:1,自引:0,他引:1
F-PbO2 electrode and polytetrafluoroethylene (PTFE) doped F-PbO2 electrode (PTFE-F-PbO2) were prepared on a plexiglas sheet substrate by a series of procedure including chemical and electrochemical depositions. The electrochemical activities of these two electrodes for oxygen evolution (OE) reaction were examined by electrochemical tests. In comparison with F-PbO2, PTFE-F-PbO2 electrode exhibited larger active surface area and higher oxygen vacancy deficiency, which resulted in its higher electrocatalytic activity for OE. In addition, both exchange current density and activation energy of the electrodes for OE were calculated in terms of active surface area. The values of exchange current density and activation energy in 0.5 mol·L^-1 H2SO4 aqueous solution were 1.125×10^ -3 mA·cm^-2 and 18.62 kJ·mol^-1 for PTFE-F-PbO2, and 8.384×10^-4 mA·cm^- 2 and 28.98 kJ·mol^-1 for F-PbO2, respectively. Because these values are calculated on the basis of the active surface areas of the electrodes, the enhanced activity of PTFE-F-PbO2 can be attributed to an increase in oxygen vacancy deficiency of PbO2 due to doping by PTFE. The influence of PTFE adulteration on the activity of PbO2 film electrode for OE was investigated in detail in this study. 相似文献
993.
Aniruddha S. Deshpande Ramdas B. Khomane Bhalchandra K. Vaidya Renuka M. Joshi Arti S. Harle Bhaskar D. Kulkarni 《Nanoscale research letters》2008,3(6):221-229
Sulfur nanoparticles were synthesized from hazardous H2S gas using novel biodegradable iron chelates in w/o microemulsion system. Fe3+–malic acid chelate (0.05 M aqueous solution) was studied in w/o microemulsion containing cyclohexane, Triton X-100 and n-hexanol as oil phase, surfactant, co-surfactant, respectively, for catalytic oxidation of H2S gas at ambient conditions of temperature, pressure, and neutral pH. The structural features of sulfur nanoparticles have
been characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), energy dispersive spectroscopy (EDS),
diffused reflectance infra-red Fourier transform technique, and BET surface area measurements. XRD analysis indicates the
presence of α-sulfur. TEM analysis shows that the morphology of sulfur nanoparticles synthesized in w/o microemulsion system
is nearly uniform in size (average particle size 10 nm) and narrow particle size distribution (in range of 5–15 nm) as compared
to that in aqueous surfactant systems. The EDS analysis indicated high purity of sulfur (>99%). Moreover, sulfur nanoparticles
synthesized in w/o microemulsion system exhibit higher antimicrobial activity (against bacteria, yeast, and fungi) than that
of colloidal sulfur. 相似文献
994.
利用钛酸正四丁酯水解制备了几种不同浓度的TiO2胶体,在降解甲基橙后发现,R(乙醇与水物质的量比)值为1/50的0.01mol/L TiO2胶体降解效果最好。在不同的pH值、反应温度、搅拌速度下制备了同时掺杂铁离子和铜离子的R值为1/50的0.01mol/L TiO2胶体,通过光降解甲基橙,发现pH值、反应温度、搅拌速度和掺杂离子浓度对TiO2胶体的形态、掺杂效果和光催化活性均有影响。对比纯TiO2胶体的光降解甲基橙效果发现,掺杂铁离子和铜离子的TiO2光催化剂在pH值2.0、低搅拌速度、室温情况下,具有更好的光催化活性。 相似文献
995.
In this paper, the surfactant dodecylcysteine hydrochloride was synthesised. The surface parameters of the synthesised surfactant
were studied using a surface tension technique. The surface parameters show a good surface activity of the prepared surfactant
in aqueous solution. The self-assembling behaviour of the synthesised surfactant comparing with that of cysteine compound
on the prepared gold nanoparticles was confirmed using transmission electron microscope (TEM) measurements. The effect of
self-assembling of this surfactant on the size of gold nanoparticles was studied using TEM images. The antitumour activity
of the prepared surfactant without and with the gold nanoparticles was investigated. The results show that the antitumour
activity of the prepared surfactant was enhanced with the presences of the gold nanoparticles.
相似文献
E. M. S. AzzamEmail: |
996.
Marcelo C. Murguía Laura M. Machuca María C. Lurá María I. Cabrera Ricardo J. Grau 《Journal of surfactants and detergents》2008,11(3):223-230
A series of new N-acetylated non-ionic and cationic gemini surfactants (3a–f) having dimeric structures derived from primary and tertiary amines with variably long tails (C8–C12–C18) were synthesized. In addition, N-acetylated monomeric analogues 6a and 6b were prepared and their antifungal potency and surface properties were also determined. Critical micelle concentration (CMC),
effectiveness of surface tension reduction (γCMC), surface excess concentration (Γ), and area per molecule at the interface (A) were also determined and the resulting values indicate that the cationic series is characterized by good surface-active
and self-aggregation properties. For the first time, all surfactants were tested to evaluate their antifungal properties using
the method for the broth macrodilution test (M27-A2, NCCLS). Four microbial strains were used to perform the study: Candida parapsilosis (ATCC 22019), C. albicans (ATCC 64548), and a wild-type strain of C. parasilosis and Saccharomyces cerevisiae (ATCC 9763). The antimicrobial activity was measured by yeast growth inhibition expressed as minimum inhibitory concentration
(MIC) values. Results were compared to those obtained for their monomeric analogues and for a commercially available reference
compound (Fluconazole). Gemini 3b, 3e and 3f were found to be the most potent compounds. The results show S. cerevisiae as the most sensitive strain. In contrast, the wild strain of C. parapsilosis was resistant.
相似文献
Ricardo J. Grau (Corresponding author)Email: |
997.
Cerovský V Hovorka O Cvacka J Voburka Z Bednárová L Borovicková L Slaninová J Fucík V 《Chembiochem : a European journal of chemical biology》2008,9(17):2815-2821
A novel antimicrobial peptide designated melectin was isolated from the venom of the cleptoparasitic bee Melecta albifrons. Its primary sequence was established as H-Gly-Phe-Leu-Ser-Ile-Leu-Lys-Lys-Val-Leu-Pro-Lys-Val-Met-Ala-His-Met-Lys-NH(2) by Edman degradation and ESI-QTOF mass spectrometry. Synthetic melectin exhibited antimicrobial activity against both gram-positive and -negative bacteria and it degranulated rat peritoneal mast cells, but its hemolytic activity was low. The CD spectra of melectin measured in the presence of trifluoroethanol and sodium dodecyl sulfate showed a high content alpha-helices, which indicates that melectin can adopt an amphipathic alpha-helical secondary structure in an anisotropic environment such as the bacterial cell membrane. To envisage the role of the proline residue located in the middle of the peptide chain on biological activity and secondary structure, we prepared several melectin analogues in which the Pro11 residue was either replaced by other amino acid residues or was omitted. The results of biological testing suggest that a Pro kink in the alpha-helical structure of melectin plays an important role in selectivity for bacterial cells. In addition, a series of N- and C-terminal-shortened analogues was synthesized to examine which region of the peptide is related to antimicrobial activity. 相似文献
998.
999.
1000.