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991.
W. Tang L.L. Liu S. Tian L. Li Y.B. Yue Y.P. Wu S.Y. Guan K. Zhu 《Electrochemistry communications》2010,12(11):1524-1526
Crystalline nanoparticles of LiCoO2 are prepared by a sol–gel method at 550 °C and characterized by X-ray diffraction. Their electrochemical behaviors were characterized by cyclic voltammograms, capacity measurement and cycling performance. Results show that the reversible capacity of the nano-LiCoO2 can be up to 143 mAh/g at 1000 mA/g and still be 133 mAh/g at 10,000 mA/g (about 70C) in 0.5 mol/l Li2SO4 aqueous electrolyte. In addition, their cycling behavior is also very satisfactory, no evident capacity fading during the initial 40 cycles. These data present great promise for the application of aqueous rechargeable lithium batteries. 相似文献
992.
Low and high molecular weight fucoidans (F(5-30K) and F(>30K)) were chemically modified through the addition of sulfate groups, and the effect of oversulfation on the in vitro anticancer activity was investigated. After the addition of sulfate groups, a considerable increase of 35.5 to 56.8% was observed in the sulfate content of the F(5-30K) fraction, while the sulfate content of the F(>30K) fraction increased to a lesser extent (from 31.7 to 41.2%). Significant differences in anticancer activity were observed between the oversulfated F(5-30K) and F(>30K) fractions, with activities of 37.3-68.0% and 20.6-35.8%, respectively. This variation in the anticancer activity of oversulfated fucoidan derivatives was likely due to differences in their sulfate content. The results suggest that the molecular conformation of these molecules is closely related to the extent of sulfation in the fucan backbones and that the sulfates are preferably substituted when the fucoidan polymers are in a loose molecular conformation. 相似文献
993.
Chan Yao Li-Kai Yan Wei Guan Chun-Guang Liu Ping Song Zhong-Min Su 《Journal of Cluster Science》2010,21(2):69-80
The second-order nonlinear optical (NLO) properties of Keggin-type organosilicone derivatives [PW11O39(RSi)2O]3− are investigated by time-dependent density functional theory (TDDFT). Our results indicated that the length of conjugated
chain R has a crucial effect on the charge transfer (CT). The direction of CT alters with the end-cap-substituted electron
donating or accepting moieties (NH2 or NO2), until the chain length reach a certain length, as the CT originates from the heteropolyanion to organosilicone moiety along
the chain, further chain lengthening leaves this behavior invariant. The derivatives with long chain substitution and end-cap-substituted
electron acceptor (NO2) display excellent second-order NLO responses. The system 18 with the relevant long conjugated polyphenylethynyl chain and
end-cap-substituted electron acceptor (NO2) has the largest β
0 value, 4538.1 × 10−30 esu. The present investigation provides important insight into the characteristic of CT and NLO properties of Keggin-type
organosilicone derivatives. 相似文献
994.
A protocol using (207)Pb NMR of solid lead nitrate was developed to determine the temperature of magic-angle spinning (MAS) NMR probes over a range of nominal set temperatures and spinning speeds. Using BioMAS and FastMAS probes with typical sample spinning rates of 8 and 35 kHz, respectively, empirical equations were devised to predict the respective sample temperatures. These procedures provide a straightforward recipe for temperature calibration of any MAS probe. 相似文献
995.
Linsen Li Min Guan Guohua Cao Yiyang Li Yiping Zeng 《Applied Physics A: Materials Science & Processing》2010,99(1):251-254
We report highly efficient and stable organic light-emitting diodes (OLEDs) with MoO3-doped perylene-3, 4, 9, 10-tetracarboxylic dianhydride (PTCDA) as hole injection layer (HIL). A green OLED with structure
of ITO/20 wt% MoO3: PTCDA/NPB/Alq3/LiF/Al shows a long lifetime of 1012 h at the initial luminance of 2000 cd/m2, which is 1.3 times more stable than that of the device with MoO3 as HIL. The current efficiency of 4.7 cd/A and power efficiency of 3.7 lm/W at about 100 cd/m2 have been obtained. The charge transfer complex between PTCDA and MoO3 plays a decisive role in improving the performance of OLEDs. 相似文献
996.
Hai-Yan Zhang Zhen-Xian Du Bao-Qin Liu Yan-Yan Gao Xin Meng Yifu Guan Wei-Wei Deng Hua-Qin Wang 《Experimental & molecular medicine》2009,41(5):362-369
TNF-related apoptosis-inducing ligand (TRAIL) has been proposed as a promising cancer therapy that preferentially induces apoptosis in cancer cells, but not most normal tissues. However, many cancers are resistant to TRAIL by mechanisms that are poorly understood. In this study, we showed that tunicamycin, a naturally occurring antibiotic, was a potent enhancer of TRAIL-induced apoptosis through downregulation of survivin. The tunicamycin-mediated sensitization to TRAIL was efficiently reduced by forced expression of survivin, suggesting that the sensitization was mediated at least in part through inhibition of survivin expression. Tunicamycin also repressed expression of cyclin D1, a cell cycle regulator commonly overexpressed in thyroid carcinoma. Furthermore, silencing cyclin D1 by RNA interference reduced survivin expression and sensitized thyroid cancer cells to TRAIL; in contrast, forced expression of cyclin D1 attenuated tunicamycin-potentiated TRAIL-induced apoptosis via over-riding downregulation of survivin. Collectively, our results demonstrated that tunicamycin promoted TRAIL-induced apoptosis, at least in part, by inhibiting the expression of cyclin D1 and subsequent survivin. Of note, tunicamycin did not sensitize the differentiated thyroid epithelial cells to TRAIL-induced apoptosis. Thus, combined treatment with tunicamycin and TRAIL may offer an attractive strategy for safely treating resistant thyroid cancers. 相似文献
997.
To analyze the effect of redox state changes on the second-order nonlinear optical (NLO) responses of organoimido-functionalized Keggin-type heteropolyanions, the excitation properties and static second-order polarizabilities of fully oxidized state, the first and second reduced states were calculated by means of the time-dependent density functional theory (TDDFT) method combined with the sum-over-states (SOS) formalism. The incorporation of extra electrons causes significant enhancement in the second-order NLO activity. The reduced complexes show more than three times the efficiency of fully oxidized state. Moreover, the NLO activities for PW11ReVNPh system can also be modified by controlling the spin multiplicity. The high spin state (3 3) has twice larger β vec value than the low spin state (1 3). The characteristic of the charge-transfer transition corresponding to the dominant contributions to the β vec values indicates that metal-centered redox processes influence the intramolecular donor or acceptor character, which accordingly leads to the variations in the computed β values. Owing to the reversible and manipulable redox processes, these kinds of the POM-based hybrid complexes could comprise a promising family of three-state redox-switchable molecular device combining chromic, magnetic, and NLO output. 相似文献
998.
A new online concentration method, namely pressure‐assisted field‐enhanced sample injection (PA‐FESI), was developed and compared with FESI for the analysis of water‐soluble vitamins by CZE with UV detection. In PA‐FESI, negative voltage and positive pressure were simultaneously applied to initialize PA‐FESI. PA‐FESI uses the hydrodynamic flow generated by the positive pressure to counterbalance the reverse EOF in the capillary column during electrokinetic sample injection, which allowed a longer injection time than usual FESI mode without compromising the separation efficiency. Using the PA‐FESI method, the LODs of the vitamins were at ng/mL level based on the S/N of 3 and the RSDs of migration time and peak area for each vitamin (1 μg/mL) were less than 5.1%. The developed method was applied to the analysis of water‐soluble vitamins in corns. 相似文献
999.
A new C-glucoside, 3,4-epoxy-5-hydroxymethyl benzoate 2-C-β-glucoside (1), together with a known alkaloid, 1H-indole-3-carbaldehyde (2), were isolated from the whole plant of Commelina communis L. The structures of these compounds were determined by 1D, 2D NMR and MS techniques.
Published in Khimiya Prirodnykh Soedinenii, No. 1, pp. 51–52, January–February, 2009. 相似文献
1000.
A high-performance liquid chromatographic method has been developed for the simultaneous analysis of the flavonols myricitrin (1), avicularin (2), and juglanin (3) in rat plasma and urine after oral administration of the total flavonoids from Polygonum aviculare. Samples were prepared by solid-phase extraction then separated on a C18 reversed-phase column by use of a mobile-phase gradient prepared from methanol and aqueous formic acid solution. The flow rate was 1 mL min?1. Detection was performed at 254 nm. The calibration range was 11–1,100 μg mL?1 for both 2 and 3 in plasma; in urine the calibration ranges for 1, 2, and 3 were 32–1,600, 11–1,100, and 22–1,100 μg mL?1, respectively. Intra-day and inter-day RSD were less than 4.33 and 3.62% for 2 and 3, respectively, in plasma, and no more than 4.03 and 2.22% for all the analytes in urine. The analytical sensitivity and selectivity of the assay enabled successful application to pharmacokinetic studies of flavonols 1–3 in rats. 相似文献