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1.
Julia K Pruns Jens-Peter Vietzke Manfred Strassner Claudius Rapp Ulrich Hintze Wilfried A K?nig 《Rapid communications in mass spectrometry : RCM》2002,16(3):208-211
A new solvent-free sample preparation method using silver trifluoroacetate (AgTFA) was developed for the analysis of low molecular weight paraffins and microcrystalline waxes by laser desorption/ionization time-of-flight mass spectrometry (LDI-TOFMS). Experiments show that spectral quality can be enhanced by dispersing AgTFA directly in liquid paraffins without the use of additional solvents. This preparation mixture is applied directly to the MALDI probe. Solid waxes could be examined by melting prior to analysis. The method also provides sufficiently reproducible spectra that peak area ratios between mono- and bicyclic alkane peaks indicated variations in the cycloalkane content of paraffin samples. Dehydrogenation of hydrocarbons observed during the desorption/ionization process was studied by analysis of alkane standards. 相似文献
2.
The versatile behavior of a trihydrazidophosphoradamantane allowing the synthesis of a variety of neutral, mono- or di-cationic water-soluble molecules of potential interest for biphasic catalysis is reported. 相似文献
3.
Er-Si-O crystalline compounds, which exhibit superlattice structures and sharp and strong Er-related 1.54 μm photoluminescence (PL) spectra at room temperature have been formed by self-assembling growth mechanism. Oxidation of the starting materials which have Si and Er at an atomic ratio of 2:1 are prepared and then oxidation and succeeding high-temperature annealing in Ar above 1250 °C cause a self-assembled superlattice-structured Er-Si-O crystalline compounds. The control of the ratio of Si and Er, as well as the following oxidation and annealing processes, is found to be sensitive to the crystalline properties, PL spectra and electrical properties. In this study, Er-Si-O crystalline thin films are formed on Si substrates by sol-gel and MOMBE methods, and their crystalline properties such as crystalline orientation and concentration ratio of Er, Si and O are investigated. Crystalline Er-Si-O films of high orientation are successfully grown on Si(1 0 0) and its inclined surface. The PL and excitation spectra, fluorescence decay and the electrical properties are found to be strongly related to the crystalline properties. Excess O causes a broader 1.54 μm PL spectra, slower fluorescence decay, lower carrier-mediated excitation and higher resistivity. A precise control of O is found to be necessary to grow superlattice-structured Er-Si-O compounds, which are semiconducting and are excitable via carrier-mediated excitation mechanism. 相似文献
4.
In this paper we construct an example of a word metric on an infinite cyclic subgroup. This example shows that subexponential
distortion does not obstruct non-trivial growth of connected radii. This answers a question of Gromov [6]. The constructed
metric has other pathological properies. Specifically, its asymptotic cone depends on the choice of ultrafilter and scaling
sequence.
The work has been partially supported by the Swiss National Science Foundation. 相似文献
5.
We build a metric space which is homeomorphic to a Cantor set but cannot be realized as the attractor of an iterated function system. We give also an example of a Cantor set K in R3 such that every homeomorphism f of R3 which preserves K coincides with the identity on K. 相似文献
6.
Milan Medved? 《Journal of Mathematical Analysis and Applications》2002,267(2):643-650
A criterion for the nonexplosion of solutions to semilinear evolution equations on Banach spaces is proved. The result is obtained by applying a modification of the Bihari type inequality to the case of a weakly singular nonlinear integral inequality. 相似文献
7.
K. Yatsu T. Cho H. Higaki M. Ichimura K. Ishii Y. Ishimoto M. K. Islam A. Itakura I. Katanuma J. Kohagura Y. Nakashima T. Saito Y. Takemura Y. Tatematsu M. Yoshida M. Yoshikawa 《Czechoslovak Journal of Physics》2002,52(10):1143-1148
GAMMA 10 experiments have advanced in high density experiments after the last EPS Workshop where we reported high density
plasma production by using an ion cyclotron range of frequency heating at a high harmonic frequency and neutral beam injection
in the central cell. Recently a high density plasma was obtained with much improved reproducibility than before and without
degradation of diamagnetic signal. The high density plasma was attained by adjusting the spacing of the conducting plates
installed in the anchor transition regions. Dependencies of particle confinement time, ion energy confinement time and plasma
confining potential on plasma density were obtained for the first time in the high density region.
Presented at 5th Workshop “Role of Electric Fields in Plasma Confinement and Exhaust”, Montreus, Switzerland, June 23–24,
2002. 相似文献
8.
We consider the one-dimensional steady-state semiconductor deviceequations modelling a pnpn device. There are two relevant scalingsof the equations corresponding to small and large applied voltages.In both scalings, the semiconductor equations can be consideredas singularly perturbed. It turns out that the small-voltagescaling breaks down for current values between two saturationcurrents. In that interval, the large-voltage scaling has tobe employed. For both scalings, we derive the first-order termsof an asymptotic expansion and show that the reduced problemhas a solution. An example verifies that the current-voltagecurves obtained have the expected qualitative structure. 相似文献
9.
Could simple intraannular-arm macrocyclic systems exist in enantiopure stable forms? The effective synthesis of two representative compounds of such a class, their resolution into enantiomers, and experiments justifying their stability toward racemization are presented. 相似文献
10.
The measuring elements of both dry‐ and wet‐type gas meters are composed of a diaphragm and rotary drum. In this article an explanation on the principle of measuring and the structure of the gas meter for each of these two types was discussed. Such applications were made as follows: synthetic rubber was used for the measuring diaphragm, engineering plastic was employed instead of metal for the measuring drum, and poly(butylene terephthalate) (PBT) was used for the casing, respectively. As a result, an improvement in the gas resistance performance and productivity, which led to a lighter weight, more compactness and a lower cost of productions was achieved. Also the influence of the solubility of the measured gas to the plastic on the measured valve was discussed. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献