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841.
Markus Ostermann Achim Berger Christian Mans Christoph Simons Stephanie Hanning Anton Janßen Martin Kreyenschmidt 《Accreditation and quality assurance》2011,16(10):515-522
The Federal Institute for materials research and testing (BAM) in cooperation with the Fachhochschule Münster has developed
a new certified polymeric reference material, BAM-H010. The reference material consists of acrylonitrile–butadiene–styrene
terpolymer (ABS) and has been doped with different contents of the elements Br, Cd, Cr, Hg and Pb. The monitoring of these
elements is demanded in the EU directive 2002/95/EG, commonly referred to as RoHS. We have shown that the uncertainty contribution
of the thermal long-term stability (u
stability) is negligible compared to the contribution to the uncertainty caused by the method used for the characterization of the
elemental content and the batch inhomogeneity (u
homogeneity). The stability of the ABS material during exposure of the samples with hard X-radiation leads to a degradation of the ABS
matrix with either long- or short-chain products. 相似文献
842.
Najbjerg H Afseth NK Young JF Bertram HC Pedersen ME Grimmer S Vogt G Kohler A 《The Analyst》2011,136(8):1649-1658
We investigated the applicability of FTIR-spectroscopy as a high throughput screening method for detection of biochemical changes in intact liver cells in bulk upon fatty acid exposure. HepG2 cells adapted to serum free (HepG2-SF) growth were exposed to four different fatty acids, three octadecenoic acids, differing in cis/trans-configuration or double bond position (oleic acid, elaidic acid and vaccenic acid) as well as palmitic acid in three days. High throughput FTIR spectroscopic measurements on dried films of intact cells showed spectra with high signal-to-noise ratio and great reproducibility. When applying principal component analysis (PCA) a clear discrimination between fatty acid exposures was observed. Higher levels of triacylglycerides were accumulated in cells exposed to elaidic acid than when exposed to the other fatty acids; the least accumulation appeared to be in cells exposed to palmitic acid. An increased absorption at ~966 cm(-1) corresponding to trans-double bond was detected upon elaidic acid exposure but not upon vaccenic acid exposure. Instead, upon vaccenic acid exposure two new absorption bands were observed at 981 and 946 cm(-1) due to the presence of double bond conjugation. Raman spectroscopy on single cells, with and without treatment by vaccenic acid, confirmed the presence of conjugation. By fatty acid composition analysis, the conjugation was further specified to be conjugated linoleic acid (CLA) isomers. Thus, instead of being preserved as a monounsaturated fatty acid, vaccenic acid was converted into CLA in HepG2 cells. The results demonstrate the applicability of high-throughput FTIR spectroscopy as an explorative method in in vitro systems from which biologically relevant hypotheses can be generated and further investigated. 相似文献
843.
Lieb D Zahl A Wilson EF Streb C Nye LC Meyer K Ivanović-Burmazović I 《Inorganic chemistry》2011,50(18):9053-9058
Water exchange on a molecular, purely inorganic cobalt-based water oxidation catalyst, [Co(4)(II)(H(2)O)(2)(α-P(1)W(9)O(34))(2)](10-) (1), in the catalytically relevant pH region (pH 6-10) is studied using (17)O-NMR spectroscopy and ultrahigh-resolution electrospray ionization mass spectrometry. The results are compared with those of the inactive [Co(II)(H(2)O)(1)Si(1)W(11)O(39)](6-) (2), which is stable in the same pH region. The results obtained provide mechanistic details of the elementary reaction step related to the water oxidation on homogeneous metal oxide catalysts under catalytically relevant conditions. It is shown that the structural integrity of 1 and 2 is maintained, no deprotonation of the aqua ligands on the Co(II) centers occurs, and the water exchange does not undergo any mechanistic changeover at the catalytic pH conditions. We have demonstrated that the water exchange process is influenced by the cluster environment surrounding the water binding sites and is fast enough to not be rate-limiting for the water oxidation catalysis. 相似文献
844.
Achim Blumensath 《Mathematical Logic Quarterly》2011,57(4):409-431
We study tree‐like decompositions of models of a theory and a related complexity measure called partition width. We prove a dichotomy concerning partition width and definable pairing functions: either the partition width of models is bounded, or the theory admits definable pairing functions. Our proof rests on structure results concerning indiscernible sequences and finitely satisfiable types for theories without definable pairing functions. © 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim 相似文献
845.
846.
We investigate leading order deviations from general relativity that violate the Einstein equivalence principle in the gravitational standard model extension. We show that redshift experiments based on matter waves and clock comparisons are equivalent to one another. Consideration of torsion balance tests, along with matter-wave, microwave, optical, and M?ssbauer clock tests, yields comprehensive limits on spin-independent Einstein equivalence principle-violating standard model extension terms at the 10(-6) level. 相似文献
847.
We report on the coherent combination of two chirped pulsed fiber lasers. The beams coming from two 100?μm core diameter ytterbium-doped rod-type fibers were coupled in a Mach-Zehnder-type interferometer by means of a polarization beam splitter. Active stabilization of the interferometer was achieved by using a piezo-mounted mirror driven by a H?nsch-Couillaud polarization detection system. Pulses with 120?μJ energy and a compressed duration of 800?fs were obtained. This, compared with the 66?μJ coming from each single amplifier, results in a combining efficiency as high as 91%. 相似文献
848.
G. V. Danilyan J. Klenke Yu. N. Kopach V. A. Krakhotin V. V. Novitsky V. S. Pavlov P. B. Shatalov 《Physics of Atomic Nuclei》2014,77(6):677-681
The results of an experiment devoted to searches for effects of rotation of fissioning nuclei in the angular distributions of prompt neutrons and gamma rays originating from the polarized-neutron-induced fission of 233U nuclei are presented. The effects discovered in these angular distributions are opposite in sign to their counterparts in the polarized-neutron-induced fission of 235U nuclei. This is at odds with data on the relative signs of respective effects in the angular distribution of alpha particles from the ternary fission of the same nuclei and may be indicative of problems in the model currently used to describe the effect in question. The report on which this article is based was presented at the seminar held at the Institute of Theoretical and Experimental Physics and dedicated to the 90th anniversary of the birth of Yu.G. Abov, corresponding member of Russian Academy of Sciences, Editor in Chief of the journal Physics of Atomic Nuclei. 相似文献
849.
Bifunctional DNA Architectonics: Three‐Way Junctions with Sticky Perylene Bisimide Caps and a Central Metal Lock 下载免费PDF全文
M. Sc. Claudia Stubinitzky Andrea Bijeljanin Linda Antusch Dr. Daniel Ebeling Priv. Doz. Dr. Hendrik Hölscher Prof. Dr. Hans‐Achim Wagenknecht 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(38):12009-12014
A new type of a bifunctional DNA architecture based on a three way junction is developed that combines the structural motif of sticky perylene bisimide caps with a tris‐bipyridyl metal ion lock in the center part. A clear stabilizing effect was observed in the presence of Fe3+, Ni2+ and Zn2+ by the formation of corresponding bipyridyl complexes in the branching part of the DNA three way junctions. The dimerization of the 5′‐terminally attached perylene diimides (PDI) chromophores by hydrophobic interactions can be followed by significant changes in the UV/Vis absorption and steady‐state fluorescence. The PDI‐mediated DNA assembly occurs at temperatures below the melting temperature and is not influenced by the metal‐ion bipyridyl locks in the central part. The corresponding AFM images revealed the formation of higher‐ordered structures as the result of DNA assemblies mediated by the PDI interactions. 相似文献
850.
Karsten Kuepper Manfred Neumann Ahmed Jasim M. Al-Karawi Amrita Ghosh Stephan Walleck Thorsten Glaser Pierre Gouzerh Achim Müller 《Journal of Cluster Science》2014,25(1):301-311
The present investigation refers to nanostructured mixed metal oxides—more specifically to iron–molybdenum oxides most simply obtained by addition of iron(III) chloride to an aqueous solution of sodium molybdate acidified with acetic acid. The immediately obtained yellow non-crystalline solid consists of highly symmetrical icosahedral {Mo72Fe30} motifs which is proven by IR, Raman, 57Fe Mössbauer and XP spectra. This remarkable result is obtained in spite of the immediate precipitation of the mentioned compound and even from an inhomogeneous mixture of the educts. This again proves the high formation tendency of spherical clusters. The procedure offers in principle the option to encapsulate species present in solution. 相似文献