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W. Schr?n A. Detcheva B. Dre?ler K. Danzer 《Fresenius' Journal of Analytical Chemistry》1998,361(2):106-109
Direct solid sampling graphite furnace AAS (SS-GF-AAS) provides an advantageous alternative to the conventional AAS which
requires wet digestion of the samples. This method is suitable for trace element determination in calcium fluoride and other
fluoride-containing samples. Matrix effects were studied by using calibration standards, certified reference materials with
different matrices and by means of three-dimensional calibration. 3D calibration is suitable for selection of calibration
samples for more reliable analyses. Cu, Pb, Cd, Zn, and Fe were determined by means of calibration with variation of sample
weight using certified reference materials and suitable fluoride-containing calibration samples.
Received: 25 July 1997 / Revised: 15 December 1997 / Accepted: 20 December 1997 相似文献
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Ivanisevic A McCumber KV Mirkin CA 《Journal of the American Chemical Society》2002,124(40):11997-12001
We describe a new combinatorial method for studying the exchange between solution adsorbates and nanoscale features within libraries generated via dip-pen nanolithography. Four different compounds, 1-octadecanethiol, 16-mercaptohexadecanoic acid, ferrocene (11-mercaptoundecyl), and ferrocene (11-mercapto-1-oxoundecyl), are studied on amorphous and single-crystal gold substrates. This series of adsorbates allows us to compare the exchange properties of patterns of nanoscale features as a function of composition, feature size, and type of underlying substrate. Moreover, these properties can be compared and contrasted with bulk SAM properties. The novel strategy provides not only a method for initiating site-specific exchange processes but also a way of extracting kinetic information about the rate of such processes in situ. 相似文献
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Angle-Resolved X-ray Photoelectron Spectroscopy (ARXPS) was used to examine amino acid bonding and oxide removal on InAs(1 0 0) surfaces. Five amino acids were studied, including cysteine, lysine, aspartic acid, glutamic acid and arginine. Observations on the ability of specific functional groups to prevent oxide formation were made by examining the thickness of oxide films on the functionalize surfaces. Amino acids that possessed more than one functional group having resonance were shown to most effectively affect oxide formation. The influence of these groups on the electronic structure of InAs(1 0 0) provides insight into how multifunctional passivation strategies could be beneficial, as well as showing how biological molecules might affect detection when InAs(1 0 0) is used as a platform. 相似文献
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Analytical and Bioanalytical Chemistry - 相似文献
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Bruch’s membrane is a layer composed of collagen fibers located just beneath the retina. This study validates a strategy used
to map the morphological and adhesion characteristics of collagen fibers in Bruch’s membrane. Atomic force microscopy tips
were functionalized with different chemical groups and used to map the hydrophilic and hydrophobic regions on the surface
of the eye tissue. The largest adhesion forces were observed when tips functionalized with NH2 groups were used. The trend in the adhesion forces was rationalized based on the distribution of different functional groups
in the triple-helical structure of the collagen fibers. The results of this study can be used to design more effective strategies
to treat eye diseases such as age-related macular degeneration. 相似文献
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Problems occurring during operation of a 2-D LC-MS system for separation and identification of neuropeptides, such as contamination of the used salts and column bleed, are described. When using polysulfoethyl aspartamide, which is widely used as a strong cation exchange stationary phase in the first dimension, interfering peaks were observed in the second-dimension reversed-phase chromatograms. The observed peaks, found to be caused by column bleeding, had abundance above the threshold value and influenced the quality of the analyses. The origin of the peaks was verified and appropriate measures are proposed. Additionally, peaks caused by polyethylene glycols (PEGs), covering approximately 5 min of feasible chromatographic time in every fraction, were observed. The commercial ammonium formate salts used to prepare the first-dimension mobile phase were found to contain PEG impurities, and in subsequent work the salt solutions were prepared from formic acid and ammonia to avoid any additional contaminations. 相似文献
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Surfaces functionalized with polystyrene particles and polyelectrolytes were used to investigate the morphological and adhesion properties of composite substrates. Atomic force microscopy (AFM) studies showed that surfaces with non-homogeneous topography have non-homogeneous adhesion properties. In addition, the homogeneity of the adhesion properties is dependent upon the chemical species used to functionalize the surface. Force volume (FV) imaging was utilized to map the adhesion of the fabricated substrates with high-resolution. The FV studies revealed that the hydrophobicity of the surface is not uniform despite the fact that the surface was functionalized with the same polyelectrolyte. The analysis methodology we report here opens the possibility to design better surfaces for future tissue engineering applications. 相似文献
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Inorganic materials have become an increasingly researched topic due to their applications in many areas especially health care. One major problem with them is the effect that their surface coatings have on cells. The same coatings that are meant to increase biocompatibility can actually invoke cytotoxicity. This tutorial review focuses on the various types of coatings and how their properties, such as electrostatic charge and hydrophobicity, affect the observed toxicity. The theorized mechanisms by which the coatings induce toxicity are also presented. Finally, the prospects for the future of this field are discussed. 相似文献