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181.
182.
Here, we construct infinitely many number fields of any given degree d>1 whose class numbers have many prime factors. 相似文献
183.
Scott D. Noblitt Florian M. Schwandner Susanne V. Hering Jeffrey L. Collett Jr. Charles S. Henry 《Journal of chromatography. A》2009,1216(9):1503-1510
A sensitive and selective separation of common anionic constituents of atmospheric aerosols, sulfate, nitrate, chloride, and oxalate, is presented using microchip electrophoresis. The optimized separation is achieved in under 1 min and at low background electrolyte ionic strength (2.9 mM) by combining a metal-binding electrolyte anion (17 mM picolinic acid), a sulfate-binding electrolyte cation (19 mM HEPBS), a zwitterionic surfactant with affinity towards weakly solvated anions (19 mM N-tetradecyl,N,N-dimethyl-3-ammonio-1-propansulfonate), and operation in counter-electroosmotic flow (EOF) mode. The separation is performed at pH 4.7, permitting pH manipulation of oxalate's mobility. The majority of low-concentration organic acids are not observed at these conditions, allowing for rapid subsequent injections without the presence of interfering peaks. Because the mobilities of sulfate, nitrate, and oxalate are independently controlled, other minor constituents of aerosols can be analyzed, including nitrite, fluoride, and formate if desired using similar separation conditions. Contact conductivity detection is utilized, and the limit of detection for oxalate (S/N = 3) is 180 nM without stacking. Sensitivity can be increased with field-amplified sample stacking by injecting from dilute electrolyte with a detection limit of 19 nM achieved. The high-sensitivity, counter-EOF operation, and short analysis time make this separation well-suited to continuous online monitoring of aerosol composition. 相似文献
184.
Dr. Florian Ratz 《Monatshefte für Chemie / Chemical Monthly》1904,25(7):687-744
Ohne Zusammenfassung 相似文献
185.
William R. Dolbier Jr. Yian Zhai Wei Xu Will Wheelus Florian Dulong Efram Goldberg Ion Ghiviriga Merle A. Battiste 《Journal of fluorine chemistry》2008,129(12):1133-1138
When 4-nitro-AF4 is treated with nucleophiles such as alkoxides and cyanide, a novel ring opening, cyclophane destroying reaction is observed whereby, via an SNAr mechanism, the nucleophile attacks the bridgehead aryl carbon vicinal to the nitro group with subsequent aryl-CF2 bond cleavage. 相似文献
186.
187.
Raymond Langer Johannes Lotz Liming Cai Florian vom Lehn Klaus Leppkes Uwe Naumann Heinz Pitsch 《Proceedings of the Combustion Institute》2021,38(1):777-785
Many studies apply sensitivity analysis to explore the impact of reaction kinetic parameters on model predictions. The importance of thermochemical and transport data is often assumed to be relatively low. While this is true for specific combustion properties of hydrocarbons, the role of thermochemical and transport data in combustion processes of nitrogen-containing molecules remains to be investigated. Thus, this work applies adjoint sensitivity analysis to the complete set of parameters in combustion models, i.e., kinetics, thermodynamics, and transport data. This integral approach increases the number of parameters considered in the sensitivity analysis drastically. Compared to forward sensitivity analysis, the adjoint approach is very efficient for a large number of parameters, and analysis with several thousand parameters can be performed in seconds. Nitrogen oxide formation in methane/air flames and laminar burning velocities of ammonia/air flames are considered as prediction targets. Sensitivity analysis results for kinetic, thermochemical, and transport data are compared by jointly considering all appearing parameter uncertainties. The comparison reveals that, due to their importance for the equilibrium constants of elementary reactions, the optimization potential of thermodynamic properties is often similarly high as that of the kinetics parameters. Transport parameters are found to be of the lowest priority for the model development due to their low uncertainties, even though high sensitivities are determined for several of them. More specifically, the analysis for the laminar burning velocities of ammonia/air flames reveals a high optimization potential for parameters in the N2-amine chemistry, including the molar heat capacities of N2H2, N2H3, and NH. Interestingly, analyses with different mechanisms reveal strongly diverging results, especially regarding the importance of reactions with OH, which is uncommon when considering the combustion of hydrocarbons. 相似文献
188.
189.
Imines in the Titanium Coordination Sphere – Transformation of Imidoyl Chlorides to Nitrilium Ions 下载免费PDF全文
In the reaction of TiCl4 in benzene as solvent with the imidoyl chloride p‐Tolyl(Cl)C=NPh ( 1 ) the abstraction of the chloride substituent is observed, leading to the nitrilium salt [p‐Tolyl–C≡N–Ph]+[Ti2Cl9]– ( 2 ) in quantitative yield. The highly electrophilic salt 2 is characterized by IR‐ and NMR spectroscopy. The observed band for the C≡N stretching mode of 2 clearly indicates the formation of a nitrilium ion. Especially a characteristic line broadening of the 13C{1H}‐NMR signals related to carbon atoms next to the nitrogen is observed. By 15N,1H‐HMBC NMR experiments it is shown that the nitrogen signal of 2 is significantly shifted to high‐field in relation to nitriles and imines. The molecular structure of 2 was confirmed by single‐crystal X‐ray diffraction. The C≡N bond length and the linearity of the C–C≡N–C unit in 2 confirm the triple bond character of this bond. 相似文献
190.
Classic telecommunication methods and Internet services are converging. For this reason Telecommunication companies are looking
for new ways to include their services in Web 2.0 applications. A strong candidate for the telecommunication infrastructure
of the future is the IP Multimedia Subsystem (IMS), an all IP telecommunication core network. In the last few years a new
kind of application has increasingly gained popularity: they are known as widgets. Widgets are small but fancy applications
based on Web technologies that are very easy to develop. This paper describes a new approach to combining widgets with telecommunication
features, such as Voice over IP calls or messaging, using IMS. Our solution includes a new abstraction layer with interfaces
for the different telecommunication capabilities. Moreover, we implemented a widget engine that makes these telecommunication
interfaces available to its widgets. Our solution allows the rapid development of new IMS client applications and a short
time-to-market. The combination of other Web 2.0 services with IMS features becomes an exploitable opportunity. 相似文献