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91.
Panarin YP Nagaraj M Sreenilayam S Vij JK Lehmann A Tschierske C 《Physical review letters》2011,107(24):247801
The mesomorphic properties of an achiral bent-core liquid crystal derived from 4-cyanoresorcinol are studied by polarizing optical microscopy, x-ray diffraction, and second harmonic electro-optic response. It shows a novel sequence of four nontilted or orthogonal smectic phases on cooling: SmA-SmAP(R)-SmAP(X)-SmAP(A). Here SmAP(X) is the new orthogonal polar uniaxial smectic phase. The electric-field-induced transformations in the SmAP(X) phase give rise to two biaxial states separated by a uniaxial one. The second harmonic electro-optic response in this phase is interpreted in terms of the polar interaction with the electric field. A comparison of the experimental results with the next-nearest-neighbor model for the structure of the SmAP(X) phase shows it to be an SmAP(α) phase. 相似文献
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Three-dimensional free-standing metal micro-objects were created using Laser Chemical Vapor Deposition (LCVD) of aluminum from aluminum-trihydride-trimethylamine. A dense grid of thin lines (about 10 µm diameter) was deposited on a pre-formed polycarbonate substrate. The substrate was removed by dissolving it in a suitable solvent after ablating an unsoluble by-product by UV excimer laser pulses. The result is a free-standing three-dimensional aluminum grid micro-structure. 相似文献
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97.
S. Lehmann G. Geipel H. Foerstendorf G. Bernhard 《Journal of Radioanalytical and Nuclear Chemistry》2008,275(3):633-642
In this study, the secondary uranium(VI) silicate minerals boltwoodite, sodium boltwoodite and uranophane were synthesized.
Sodium boltwoodite was successfully obtained by the following new reaction procedure. Their analytical characterization was
carried out by means of inductively coupled plasma mass spectrometry and atomic absorption spectroscopy, scanning electron
microscopy, X-ray powder diffraction, differential thermal analysis combined with thermogravimetry and infrared spectroscopy.
Furthermore, the fluorescence behaviour was measured using time-resolved laser fluorescence spectroscopy. Herewith, the fluorescence
properties of the three silicious uranyl phases were determined at room temperature. 相似文献
98.
Summary A gas-liquid separator is presented, which is adapted to the special conditions of metalorganic speciation analysis by HPLC-hydride AAS. 相似文献
99.
Mathias Wind Ingo Feldmann Norbert Jakubowski Wolf D Lehmann 《Electrophoresis》2003,24(7-8):1276-1280
Laser ablation inductively coupled plasma-mass spectrometry (ICP-MS) with (31)P detection has been used for spotting of phosphoproteins after one-dimensional polyacrylamide gel electrophoresis (1-D PAGE) and membrane transfer. By analyzing a mixture of myoglobin, alpha-casein and reduced fibrinogen it is demonstrated that phosphoproteins are specifically recognized by this method. A special washing step was found to be necessary to remove phosphate noncovalently bound to proteins. The (31)P signal was found to contain quantitative information both with respect to relative and absolute amounts of phosphorus present in phosphoproteins. Normalizing the (31)P signal from a single laser ablation trace by the total amount of phosphoprotein applied to the gel, a detection limit of 5 pmol of phosphorus is estimated. 相似文献
100.
W. Brandt T. Lehmann T. Hofmann R. L. Schowen A. Barth 《Journal of computer-aided molecular design》1992,6(2):159-174
Summary By theoretical conformational investigations of substrates and nonsubstrates of the enzyme dipeptidyl-peptidase IV (DP IV) as well as dipeptide-esters using the ECEPP83 method we determined the structure of peptides recognized and cleaved by the enzyme. From a comparison of all possible structures for the substrates with conformations not possible in nonsubstrates we concluded that a single conformation explains substrate specificities of DP IV. This conformation is characterized by the following dihedral angles: {ie159-1}, {ie159-2}, {ie159-3}, {ie159-4}, and {ie159-5}. The conclusions were supported by comparisons of molecular electrostatic potentials calculated with the molecular graphics program HAMOG. 相似文献