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771.
A novel nanocomposite (TNTs-FeS) was developed by anchoring ferrous sulfide (FeS) nanoparticles immobilized on titanate nanotubes (TNTs) by hydrothermal method to remove U(VI) and Re(VII) from aqueous solution, and the removal mechanism and efficiency were examined. The experimental results showed that the TNTs can effectively improve the dispersibility and stability of FeS. The environmental conditions, including initial solution pH, initial concentration, equilibrium time, and dosage, played an important role in the remediation process, which can affect the immobilization efficiency significantly. The maximum quantity removal of U(VI) and Re(VII) was 291.67 and 226.23 mg/g at pH of 6.0 and 12.0. The adsorption kinetics and the equilibrium isotherms of U(VI) and Re(VII) all fitted well with the pseudo-second-order model (R2>0.99) and the Freundlich model (R2>0.99). The main mechanism of removal by TNTs-FeS was electrostatic attraction, chemical reduction, and surface complexation. Thus, TNTs-FeS composites exhibited a high potential to remove U(VI) and Re(VII) heavy metal ions from the surface and groundwater. 相似文献
772.
In this paper, we consider the semilocal convergence of multi-point improved super-Halley-type methods in Banach space. Different from the results of super-Halley method studied in reference Gutiérrez, J.M. and Hernández, M.A. (Comput. Math. Appl. 36,1–8, 1998) these methods do not require second derivative of an operator, the R-order is improved and the convergence condition is also relaxed. We prove a convergence theorem to show existence and uniqueness of the solution. 相似文献
773.
Nakata K Okubo A Shimazu K Yamakata A Ye S Osawa M 《Langmuir : the ACS journal of surfaces and colloids》2008,24(8):4352-4357
Surface-enhanced infrared absorption spectroscopy (SEIRA) was used to examine the adsorption state of nitrogen monoxide (nitric oxide, NO) and the reduction of the adsorbed species. The SEIRA spectra gave two distinct bands at 1723-1733 and 1575-1607 cm-1 with an additional weak band at 1656-1676 cm-1 at 0.20 V, the frequencies of which are slightly dependent on the surface coverage. The former two bands are attributed to the on-top and bridged NO, respectively. While the on-top NO stably remained on the surface in the potential range of 0.05 -0.60 V, the bridged NO decreased in its intensity with increasing electrode potential. The reduction of the adsorbed NO obeys first-order kinetics with respect to the adsorbed NO. The rate constants are 2.24 +/- 0.03 and 0.24 +/- 0.09 s-1 at -0.10 V for the on-top and bridged NO, respectively. Tafel slopes obtained from the potential dependence of the rate constant indicate that the rate-determining step is the first electron-transfer process. 相似文献
774.
Superoxide Dismutase-Loaded PLGA Nanoparticles Protect Cultured Human Neurons Under Oxidative Stress
Reddy MK Wu L Kou W Ghorpade A Labhasetwar V 《Applied biochemistry and biotechnology》2008,151(2-3):565-577
The objective of our study was to investigate the neuroprotective efficacy of superoxide dismutase (SOD), loaded in poly(D,L-lactide co-glycolide; PLGA) nanoparticles (NPs), in cultured human neurons challenged with hydrogen peroxide (H(2)O(2))-induced oxidative stress. We hypothesized that the protected and sustained intracellular delivery of SOD encapsulated in NPs would demonstrate better neuroprotection from oxidative stress than either SOD or pegylated SOD (PEG-SOD) in solution. SOD-NPs (approximately 81 +/- 4 nm in diameter, 0.9% w/w SOD loading) released the encapsulated SOD in an active form with 8.2% cumulative release during the first 24 h, followed by a slower release thereafter. The results demonstrated that PLGA-NPs are compatible with human neurons, and the neuroprotective effect of SOD-NPs is dose-dependent, with efficacy seen at >100 U SOD, and less significant effects at lower doses. Neither SOD (25-200 U) nor PEG-SOD (100 U) in solution demonstrated the neuroprotective effect under similar conditions. The neuroprotective effect of SOD-NPs was seen up to 6 h after H(2)O(2)-induced oxidative stress, but the effect diminished thereafter. Confocal microscopic studies demonstrated better intracellular neuronal uptake of the encapsulated model protein (fluorescein isothiocyanate-labeled BSA) than the protein in solution. Thus, the mechanism of efficacy of SOD-NPs appears to be due to the stability of the encapsulated enzyme and its better neuronal uptake after encapsulation. 相似文献
775.
776.
离子液体与绿色化学:为了今天还是为了未来? 总被引:5,自引:0,他引:5
离子液体因绿色化学的兴起而成名。本文结合作者自己8年来的研究工作评述了离子液体特别是在化学合成、化学反应领域的最新进展。主要分4个方面:离子液体改变了载体/模版的概念;离子液体研究促进了液相反应的研究;离子液体推动了相分离技术的进步;离子液体推动了绿色化学的发展。 相似文献
777.
Meng Q Kou Y Ma X Liang Y Guo L Ni C Liu K 《Langmuir : the ACS journal of surfaces and colloids》2012,28(11):5017-5022
Peptide amphiphiles are capable of self-assembly into a diverse array of nanostructures including ribbons, tubes, and vesicles. However, the ability to select the morphology of the resulting structure is not well developed. We examined the influence of systematic changes in the number and type of hydrophobic and hydrophilic amino acids on the self-assembly of amphiphilic peptides. Variations in the morphology of self-assembled peptides of the form X(6)K(n) (X = alanine, valine, or leucine; K = lysine; n = 1-5) are investigated using a combination of transmission electron microscopy and dynamic light scattering measurements. The secondary structures of the peptides are determined using circular dichroism. Self-assembly is controlled through a combination of interactions between the hydrophobic segments of the peptide molecules and repulsive forces between the charged segments. Increasing the hydrophobicity of the peptide by changing X to a more lipophilic amino acid or decreasing the number of hydrophilic amino acids transforms the self-assembled nanostructures from vesicles to tubes and ribbons. Changes in the hydrophobicity of the peptides are reflected in changes in the critical micelle concentration observed using pyrene probe fluorescence analysis. Self-assembled materials formed from cationic peptide amphiphiles of this type display promise as carriers for insoluble molecules or negatively charged nucleic acids in drug or gene delivery applications. 相似文献
778.
Ying‐Qian Liu Wei Dai Jing Tian Liu Yang Gang Feng Xing‐Wen Zhou Liang Kou Yong‐Long Zhao Wen‐Qun Li Lin‐Hai Li Hong‐Yu Li 《Heteroatom Chemistry》2011,22(6):687-691
Continuing our search for natural product based compounds for the control of Brontispa longissima larvae, eight spin‐labeled camptothecin derivatives 7a–h and the intermediate 2 were first tested for their insecticidal activities against fifth‐instar larvae of Brontispa longissima. Among all the tested compounds, especially compounds 7a and 2 showed promising insecticidal activities with the corrected mortality rates of 69.55% and 74.07% against fifth‐instar larvae of B. longissima, respectively. The different insecticidal activity ranges of these compounds indicated that the variation of the structures of l ‐amino acids in these compounds markedly affected the activity profiles of this compound class, and some important SAR information has been revealed from it. © 2011 Wiley Periodicals, Inc. Heteroatom Chem 22:687–691, 2011; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.20734 相似文献
779.
The high electrically conductive carboxyl‐functionalized multiwalled carbon nanotubes (COOH‐MWCNTs) were used to combine with nonconducting polyimide (PI) to generate a PI/COOH‐MWCNTs membrane. PI served as a matrix to entrap COOH‐MWCNTs and hemoglobin (Hb). COOH‐MWCNTs can improve the conductivity of the composite. The direct electrochemistry measurement indicated that the PI/COOH‐MWCNTs composite enhanced the immobilization of Hb significantly. Besides, the Hb/PI/COOH‐MWCNTs/GCE biosensor possessed excellent electrocatalytic activity for the detection of nitrite. Therefore, PI is a good matrix for Hb immobilization and it has application in sensor construction. This work is promising in the development of sensitive biosensors based on PI/COOH‐MWCNTs composite film. 相似文献
780.
Inamoto K Hasegawa C Hiroya K Kondo Y Osako T Uozumi Y Doi T 《Chemical communications (Cambridge, England)》2012,48(23):2912-2914
The coupling reaction of aryl iodides with arylboronic acids to give biaryl compounds can be efficiently performed without adding a transition metal catalyst. The key to success is the use of dimethyl carbonate as a solvent. This finding provides a new strategy for constructing a biaryl linkage. 相似文献