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141.
Liuhua ChenLihua Gan Mingxian LiuRong Fan Zijie XuZhixian Hao Longwu Chen 《Applied Surface Science》2011,257(11):5070-5076
The effect of tryptophan on the membrane stability was studied by using three artificial biological membranes including liposome, Langmuir monolayer and solid supported bilayer lipid membrane (s-BLM) as models. All the results indicate that the penetration of tryptophan can destabilize different artificial biological membranes. The diameter of liposome and the leakage of calcein from liposome increased with the increase of tryptophan concentration because the penetration of tryptophan was beneficial for dehydrating the polar head groups of lipids and the formation of fusion intermediates. π-A isotherms of lecithin on the subphase of tryptophan solution further confirm that tryptophan can penetrate into lipid monolayer and reduce the stability of lipid monolayer. When the concentration of tryptophan increased from 0 to 2 × 10−3 mol L−1, the limiting molecular area of lecithin increased from 110.5 to 138.5 Å2, but the collapse pressure of the monolayer decreased from 47.6 to 42.3 mN m−1, indicating the destabilization of lipid monolayer caused by the penetration of tryptophan. The resistance spectra of s-BLM demonstrate that the existence of tryptophan leads to the formation of some defects in s-BLM and the destabilization of s-BLM. The values of electron-transfer resistance and double layer capacitance respectively decreased from 5.765 × 106 Ω and 3.573 × 10−8 F to 1.391 × 106 Ω and 3.340 × 10−8 F when the concentration of tryptophan increased from 0 to 2 × 10−3 mol L−1. Correspondingly, the breakdown voltage of s-BLM decreased from 2.51 to 1.72 V. 相似文献
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Trabecular bone with its porous structure is an important compressive load bearing member. Different structural factors such
as porosity, non-homogeneous deformation, varying trabeculae thickness, connectivity, and nanoscale (10 nm to 1 μm) to macroscale
(~0.1 mm to 10 mm) composition hierarchy determine the failure properties of trabecular bone. While the above factors have
important bearing on bone properties, an understanding of how the local nanoscale properties change at different macroscale
compressive strain levels can be important to develop an understanding of how bone fails. In the present work, such analyses
are performed on bovine femoral trabecular bone samples derived from a single animal. Analyses focus on measuring nanoindentation
elastic moduli at three distinct levels of compressive strains in the bone samples: (1) when the samples are not loaded; (2)
after the samples have been loaded to a strain level just before apparent yielding and the macroscale compression test is
stopped; and (3) after the samples have been compressed to a strain level after apparent yielding and the macroscale compression
test is stopped. Nanoindentation elastic modulus values are two orders of magnitude higher than the macroscale compressive
elastic modulus values of all samples. A high variability in macroscale compressive elastic modulus values is observed because
of porous architecture and small sample size. Nanoindentation elastic modulus values show a progressive reduction with increase
in the extent of macroscale compressive deformation. Apparent yielding has a significant effect on this trend. The decrease
in nanoindentation modulus value for all samples accelerates from approximately 20% before yielding to approximately 60% after
yielding in comparison to the nanoindentation modulus values at 0% strain level. The level of variation in the predicted nanoindentation
modulus values is the lowest for uncompressed samples (~16–18%). However, with increase in the extent of compression, the
level of variation increases. It varied between 50% and 90% for the samples tested after yielding showing a widespread heterogeneity
in local nanoscale structural order after apparent yielding. Scanning electron microscope (SEM) observations suggest that
apparent yielding significantly destroys local nanoscale structural order. However, quantitative results suggest that a significant
residual nanoscale stiffness varying from 5 GPa to 8 GPa among different samples still remains for possible repair facilitation. 相似文献
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In this paper, photovoltaic characteristics of ITO/PEDOT:PSS/SubPc:Rubrene (mixed ratio R by weight)/C60/Bphen/Ag organic solar cells (OSCs) are analyzed in detail. The intrinsic properties of a SubPc:rubrene doped layer on device performance were discussed based on theoretical analysis of the experimental OSCs. The ratio R was 0, 0.25, 0.5, and 0.75,1, respectively. The results showed that when R was 0.75 performing the best, which owned the highest short circuit current (J sc ) 6.61 mA/cm2 and highest power conversion efficiency (PCE) 2.44%, the FF was 41% and the open circuit current (V oc ) was 0.905 V. The suitable HOMO level, absorption capacity, carrier transport ability and exciton diffusion length (L D ) of organic material are very important for the performance of the device. 相似文献
147.
An efficient and convenient approach for the construction of various (E)-β-iodovinyl sulfones has been developed through potassium persulfate/tetrabutylammonium iodide-facilitated reaction of sulfonylhydrazides with alkynes. The products were obtained in good to excellent yields. The salient features of this reaction are the applications of a new iodine source, environmentally benign, safer solid oxidant, and shorter reaction time. 相似文献
148.
In this paper, a new optimization strategy is put forward which locates as many potential unimodal regions as possible in the search space. The potential optima can be further explored by a global optimization method for searching in the identified unimodal regions. The proposed strategy was evaluated by the optimization of test functions. The results obtained by this approach are comparable with those achieved by variable step size generalized simulated annealing (VSGSA) and a genetic algorithm (GA). Finally, we used this strategy in a clustering analysis of a tobacco data set. 相似文献
149.
Eckhart E Gan KK Gwon C Hart T Honscheid K Hufnagel D Kagan H Kass R Pedlar TK Thayer JB Von Toerne E Wilksen T Zoeller MM Muramatsu H Richichi SJ Severini H Skubic P Dytman SA Mueller JA Nam S Savinov V Chen S Hinson JW Lee J Miller DH Pavlunin V Shibata EI Shipsey IP Cronin-Hennessy D Lyon AL Park CS Park W Thorndike EH Coan TE Gao YS Liu F Maravin Y Stroynowski R Artuso M Boulahouache C Bukin K Dambasuren E Khroustalev K Mountain R Nandakumar R Skwarnicki T Stone S Wang JC Mahmood AH 《Physical review letters》2002,89(25):251801
We report on a search for charmless hadronic B decays to the three-body final states K(0)(S)h(+)pi(-), K(+)h(-)pi(0), K(0)(S)h(+)pi(0) (h(+/-) denotes a charged pion or kaon), and their charge conjugates, using 13.5 fb(-1) of integrated luminosity produced near sqrt[s]=10.6 GeV, and collected with the CLEO detector. We observe the decay B-->K0pi(+)pi(-) with a branching fraction (50(+10)(-9)(stat.)+/-7(syst.))x10(-6) and the decay B-->K(*+)(892)pi(-) with a branching fraction (16(+6)(-5)(stat.)+/-2(syst.))x10(-6). 相似文献
150.