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101.
102.
Ekaterina P. Altova Anatolii N. Rykov Natalja Vogt Igor F. Shishkov 《Mendeleev Communications》2021,31(1):81-83
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103.
S. Raeder N. Stöbener T. Gottwald G. Passler T. Reich N. Trautmann K. Wendt 《Spectrochimica Acta Part B: Atomic Spectroscopy》2011,66(3-4):242-247
The long-lived radio isotope 237Np is generated within the nuclear fuel cycle and represents a major hazard in the final disposal of nuclear waste. Related geochemical research requires sensitive methods for the detection of ultratrace amounts of neptunium in environmental samples. Resonance ionization mass spectrometry (RIMS) has proven to be one of the most sensitive methods for the detection of plutonium. A precondition for the application of RIMS to ultratrace analysis of neptunium is the knowledge of an efficient and selective scheme for optical excitation and ionization. Therefore, a multitude of medium to high-lying atomic levels in neptunium was located by applying in-source resonance ionization spectroscopy. By using excitation via six previously known first excited, intermediate levels of odd parity, a set of twelve so far unknown high-lying levels of even parity were identified and studied further for their suitability in resonant excitation/ionization schemes. Autoionizing resonances for efficient ionization of neptunium atoms were subsequently accessed spectroscopically. Altogether five resonance ionization schemes were investigated and characterized concerning their saturation behavior and relative efficiency. Applying a calibrated sample, an overall efficiency of 0.3% was determined. 相似文献
104.
Xiaolong Li Yueming Wang Thomas Allgurén Klas Andersson Jost O.L. Wendt 《Proceedings of the Combustion Institute》2021,38(3):4309-4316
The focus of this paper is on effects of chlorine and sulfur on coal ash deposition rates, under practically relevant but systematically controlled combustion conditions. This problem is important, not so much for coal, but to understand and predict deposition rates for biomass combustion where chlorine contents can be high. To this end, ash deposition rates on a controlled temperature surface were measured for controlled amounts of chlorine and sulfur added to a pulverized coal, doped with potassium and burned in a 100 kW rated combustion rig. Previous work with 35 tests on 11 coal, biomass and petroleum coke fuels burned under a range of operating conditions had strongly suggested that the deposition rate of the tightly bound inside deposits was independent of the ash aerosol composition, and depended only on PM1 in the flue gas. The loosely bound outside deposition rate was dependent primarily on the total alkali content in the flue gas. The new results using chlorine added to the fuel (in the form of ammonium chloride) required these previous conclusions to be drastically revised. They showed that chlorine, not alkali alone, had large effects on the deposition rate of the inside deposits, which now were orders of magnitude higher than without chlorine addition, and did not fit previous (multi-fuel) correlations with PM1. Sulfur addition, together with chlorine, did not affect deposition rates much, although it did lower the chlorine content of the deposit. These results are interpreted in terms of the ash aerosol size segregated composition, which was also measured, and potential sulfation reactions within the deposit. 相似文献
105.
Natalja Kurjane Tija Zvagule Jelena Reste Zanna Martinsone Ilona Pavlovska Inese Martinsone Ivars Vanadzins 《Journal of nanoparticle research》2017,19(9):320
Currently, nanoparticles are widely present in the environment and are being used in various industrial technologies. Nanoparticles affect immune functions, causing different immune responses. The aim of the current study was to evaluate several cytokines, interleukin (IL)-1b, IL-6, IL-8, tumour necrosis factor-a (TNF-α), interferon-γ, adhesive molecule sICAM-1, macrophage inhibitory protein 1a (MIP1a) and secretory immunoglobulin A, in nasal lavage fluid and in the peripheral blood of healthy subjects exposed to workplace nanoparticles. Thirty-six employees from three different environments were examined: 12 from a metalworking company, 12 from a woodworking company and 12 office workers. The nanoparticles in the different workplaces were detected in the air in the immediate vicinity of the employees. The particle number concentration and surface area values were significantly higher in the workplaces of the metal- and woodworking industries, but concentrations of mass were lower (the measurements were performed by an electrical low-pressure impactor ELPI+). Energy dispersive X-ray spectroscopy (EDS, an attachment to a high-resolution SEM) was used to provide elemental analysis or chemical characterization of the dust particles in a low-vacuum field-free mode operating at a potential of 15 kV spot 3.0. The technique used provided quantitative and spatial analyses of the distribution of elements through mapping (two to three parallel measurements) and point analysis (four to five parallel measurements). Samples from the metal industry contained more ultramicroscopic and nanometric particles, e.g. toxic metals such as Zn, Mn and Cr, and fewer microscopic dust particles. The nasal lavage and peripheral blood were taken at the beginning and the end of the working week, when immune indices were measured. Our data showed a statistically significant increased level of the pro-inflammatory cytokine TNF-α in serum in both exposed groups compared with office workers as well as a higher level of TNF-α in workers from the woodworking company compared with the metalworking employees. We found an elevated level of IL-6 in the exposed groups as well as an elevated level of IL-8 in the nasal lavage in woodworking employees after work. 相似文献
106.
A study on the systematic of the atomic ionization potentials for both, the lanthanide and actinide elements have been performed. The existing experimental basis, predominantly relying on results from resonance ionization spectroscopy, has been extended by novel laser spectroscopic investigations on the elements Au, Dy, Pr and Pa. Conclusive results of suitable precision for the ionization potentials could be obtained except for Pa, due to the complexity of its atomic spectrum. Nevertheless, a consistent interpretation of the observed trends for the ionization potentials of lanthanides and actinides was attempted. The series of lanthanides depicts the two well-known, completely smooth, linear trends above and below half-shell closure, from which an expectation value for the missing ionization potential of the all radioactive element promethium of IP Pm= 44985(140) cm ?1 was derived. In contrast, the lighter members of the actinide series below the half-filled shell exhibit a significant deviation from predictions, which are ascribed dominantly to relativistic influences affecting the energetic position of the multitude of low-lying configurations. With the assumption of removal of a 6d electron during the ionization process agreement between theory and experiment and a smooth, even though not linear behavior, is obtained also in this region of the Periodic Table. This new interpretation could help to better predict similar trends and systematics for elements heavier than the actinides. Particularly relevant in this respect are the super-heavy elements, which are produced only in minuscule atom numbers and thus were not accessible for any atomic physics study yet. 相似文献
107.
Benefiting from the continuous laser developments, resonance ionization can be applied for a variety of experiments on radioactive
isotopes, e.g. as a laser ion source for producing pure beams of short-lived isotopes at on-line facilities. In this paper
the application of a compact set-up for resonance ionization mass spectrometry for ultra-trace analysis of the long-lived
isotope Ca-41 is described. With this set-up a purely optical selectivity of 3×109 and an overall detection efficiency of 1.2(4)×10−5 are demonstrated. 相似文献
108.
Yuri V. Vishnevskiy Natalja Vogt Vitaliy I. Korepanov Arkadii A. Ivanov Lev V. Vilkov Vladimir V. Kuznetsov Nina N. Mahova 《Structural chemistry》2009,20(3):435-442
The molecular structure of N-chlorosuccinimide has been studied by GED method at the nozzle temperature of 116 °C. Vibrational corrections to the r
a parameters, Δ(r
a − r
e), have been calculated using the scaled quadratic and cubic force constants from B3LYP/6-31G(df,p) calculations. The force
field scaling has been carried out using the IR and Raman spectra of the solid N-chlorosuccinimide. The molecular skeleton and the bond conformation around nitrogen were found to be planar within large experimental
errors. The equilibrium geometrical parameters derived from the experimental data assuming C
2v
molecular symmetry and those from MP2(fc)/6-311G(3df,2pd) calculations are in a good agreement. 相似文献
109.
In the present research, the performance of three sample injection devices in a portable capillary electrophoresis (CE) instrument was examined. These were the so-called cross-sampler, horizontal injection channel and vertical injection channel. All the three showed a good reproducibility of migration times (the relative standard deviation (RSD) was 4.3% in the case of the cross-sampler, 6.0% in the case of the horizontal injection channel and 1.7% in the case of the vertical channel). However, the reproducibility of peak areas was not sufficient. Hence, this study was mainly focused on qualitative analysis. The cross-sampler injection device was used in the portable CE instrument to analyse the composition of degradation products of chemical warfare agents (CWA). For the analysis of CWA degradation products simple procedures for the extraction of phosphonic acids from different surfaces, such as soil, concrete and granite blocks, tile floor, were developed. 相似文献
110.