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111.
Molecular ME‐ToF‐SIMS yield as a function of DHB matrix layer thicknesses obtained from brain sections coated by sublimation/deposition techniques 下载免费PDF全文
Martin Körsgen Andreas Pelster Simeon Vens‐Cappell Oliver Roling Heinrich F. Arlinghaus 《Surface and interface analysis : SIA》2016,48(1):34-39
Time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) can be used to image biological samples with nanometer‐scale resolution, albeit with the drawback that it often cannot detect large molecular signals. One way to increase secondary ion molecular yield is to chemically modify the surface in the so‐called matrix‐enhanced SIMS (ME‐SIMS) approach, which is based on embedding analyte molecules in low‐weight organic matrices. In this study, a solvent‐free sample preparation technique was employed using sublimation/deposition for coating a mouse brain section with a thin layer of a 2,5‐dihydroxybenzoic acid (DHB) matrix. Using this preparation technique, signal enhancements of up to a factor of 18 could be detected. It was found that the matrix layer thickness plays an important role in the efficiency of yield enhancement. Also, a complex influence of the matrix layer on various signals was observed. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
112.
We develop a convergence theory for identifying parameters in a general class of nonau- tonomous nonlinear evolution equations. An application of this theory to a nonlinear reaction diffusion equation is presented. 相似文献
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Marina Levenshtein Simeon Reich 《Nonlinear Analysis: Theory, Methods & Applications》2009,70(12):4145-4150
We approximate fixed points of holomorphic and ρ-nonexpansive self-mappings of the Hilbert ball using both continuous and discrete schemes. 相似文献
116.
We study the convergence of an iterative algorithm for finding common fixed points of finitely many Bregman firmly nonexpansive
operators in reflexive Banach spaces. Our algorithm is based on the concept of the so-called shrinking projection method and
it takes into account possible computational errors. We establish a strong convergence theorem and then apply it to the solution
of convex feasibility and equilibrium problems, and to finding zeroes of two different classes of nonlinear mappings. 相似文献
117.
We establish a Julia-Carathéodory theorem and a boundary Schwarz-Wolff lemma for hyperbolically monotone mappings in the open
unit ball of a complex Hilbert space.
The second author was partially supported by the Fund for the Promotion of Research at the Technion and by the Technion VPR
Fund-B. and G. Greenberg Research Fund (Ottawa). 相似文献
118.
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K Golemanov S Tcholakova N Denkov E Pelan SD Stoyanov 《Langmuir : the ACS journal of surfaces and colloids》2012,28(33):12071-12084
Saponins are a wide class of natural surfactants, with molecules containing a rigid hydrophobic group (triterpenoid or steroid), connected via glycoside bonds to hydrophilic oligosaccharide chains. These surfactants are very good foam stabiliziers and emulsifiers, and show a range of nontrivial biological activities. The molecular mechanisms behind these unusual properties are unknown, and, therefore, the saponins have attracted significant research interest in recent years. In our previous study (Stanimirova et al. Langmuir2011, 27, 12486-12498), we showed that the triterpenoid saponins extracted from Quillaja saponaria plant (Quillaja saponins) formed adsorption layers with unusually high surface dilatational elasticity, 280 ± 30 mN/m. In this Article, we study the shear rheological properties of the adsorption layers of Quillaja saponins. In addition, we study the surface shear rheological properties of Yucca saponins, which are of steroid type. The experimental results show that the adsorption layers of Yucca saponins exhibit purely viscous rheological response, even at the lowest shear stress applied, whereas the adsorption layers of Quillaja saponins behave like a viscoelastic two-dimensional body. For Quillaja saponins, a single master curve describes the data for the viscoelastic creep compliance versus deformation time, up to a certain critical value of the applied shear stress. Above this value, the layer compliance increases, and the adsorption layers eventually transform into viscous ones. The experimental creep-recovery curves for the viscoelastic layers are fitted very well by compound Voigt rheological model. The obtained results are discussed from the viewpoint of the layer structure and the possible molecular mechanisms, governing the rheological response of the saponin adsorption layers. 相似文献
120.