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101.
Radoslaw Sobczynski Hubert Lange Stanislaw Kurowski 《Plasma Chemistry and Plasma Processing》1988,8(1):101-110
The dynamics of the formation and decay of excited hydrogen during a pulse discharge in methane at a pressure of 200 Pa and energy density of 0.05 J/cm3 has been studied. The population of hydrogen in the n=2 state was monitored by the laser absorption method. The time constant of the decay of the excited hydrogen was measured to be 95±15 ns. The concentration of free electrons reached a maximum value of 7×1014 cm–3, and the time constant of their recombination was 220±50 ns. The formation of appreciable amounts of atomic hydrogen in the ground state during the discharge, H(n=1)>1016 cm–3, was estimated on the basis of a kinetic model.Notation
absorption coefficient
-
wave number, cm–1
-
c
velocity of light
-
e
electron charge
-
m
e
mass of electron
-
A
mn
Einstein coefficient
-
F
mn
collisional deexcitation rate constant
-
S
m
ionization rate constant
-
f
24
oscillator strength
-
n
e
electron concentration
-
n
H(n=2,3,4)
excited-state hydrogen concentration
-
v
e
electron velocity
-
q
mn
excitation cross-section
- (q
mnve)
excitation rate constants
-
T
e
electron temperature
-
E (t)
electrical field strength
-
j
current density
-
t
ei
–1
electron-ion collision frequency
- 2,m
two-body recombination rate constant
- 3,m
three-body recombination rate constant 相似文献
102.
E.M. Dutkiewicz J. Suchanicz V. Bovtun K. Konieczny P. Czaja K. Kluczewska 《Phase Transitions》2016,89(7-8):823-828
ABSTRACTThermal expansion, Raman and dielectric properties of the lead-free (1?x)Na0.5Bi0.5TiO3-xSrTiO3 (x = 0, 0.08 and 0.1) ceramic solid solutions, fabricated by the conventional solid-state reaction method, were investigated. The Sr-doping results in an increase of the dielectric permittivity, broadening of the permittivity maximum, enhancement of the relaxation near depolarization temperature, broadening of the Raman bands and shift of all anomalies toward lower temperatures. The observed effects are attributed to an increase of the degree of cationic disorder and enhancement of the relaxor-like features. Anomalies in the thermal expansion strain were observed at the temperatures corresponding to the dielectric anomalies but not related to any phase transitions. These anomalies are supposed to follow changes of the averaged unit cell volume in the temperature interval of tetragonal and rhombohedral phase coexistence. 相似文献
103.
104.
Synchronous luminescence analysis was performed in order to identify aromatic compounds in solvent extracts of Baltic amber. The investigated extracts were obtained, for comparisons, as products of extraction by various techniques and solvents. Methylene chloride and ethanol were applied independently for extraction at the ambient temperature (conservative extraction), as well as at the temperature of solvent boiling (extraction in Soxhlet apparatus). Ethanol, as the solvent, was also used for extraction in an ultrasonic bath and for the decoction process. The extraction, by techniques mentioned, of the analysed amber has resulted in products generally containing the same groups of aromatics: mainly naphthalenes, phenanthrenes and anthracenes. Among phenanthrenes, in all samples the retene was also identified, being one of the characteristic links of the diagenetic chain of chemical transformations of vegetal precursors. The identification of a series of individual compounds made, using the synchronous luminescence technique, was verified by the record of conventional emission and excitation spectra. Presented identified compounds were also confirmed by the results of GC-MS analysis. The luminescence analysis was also performed comparatively for fossil resin from Galicia, Spain (Cretaceous) older than Baltic amber (Tertiary, Eocene). The obtained preliminary results of synchronous luminescence analysis suggest the possibility of diversification in this manner of fossil resins of various ages by characterisation of aromatisation degree and alkyl substitution of aromatic rings. It is since well known that aromatisation progress is an indicator of a natural process of maturation of fossil organic matter. However, a greater number of samples should be taken to further testify to the investigations. 相似文献
105.
Krzysztof Waskiewicz Rafal Gabanski Radoslaw Motyka Mieczyslaw Lapkowski Jerzy Suwinski Jerzy Zak 《Journal of Electroanalytical Chemistry》2008,617(1):27-37
The group of 1,4-dialkoxy-2,5-bis[2-(thien-2-yl)ethenyl]benzene stereoisomers was synthesized in which methoxy- and ethoxy-groups were used as alkoxy-substituents. These isomers were characterized as solution species both electrochemically and spectroscopically. As expected, these compounds, having a stilben like structure, are the subject of photoisomerization, which is described and discussed. It is demonstrated how electrochemical process may cause isomerization of the double CC bonds in that group of compounds. An attempt of using electrochemical methods to monitor the process of photoisomerization of these compounds is presented. Mechanism of the oxidatively induced electrochemical isomerization has been proposed and discussed. The electrochemical isomerization mechanism is verified by digital simulation, which allowed estimating basic kinetic parameters of the processes. 相似文献
106.
Marzenna Klimaszewska Sabina Grska Grzegorz apienis Beata Kaleta Sandra Grska Marta Kaszowska Maciej Dawidowski Andrzej Gamian Radoslaw Zagodon Andrzej Grski Jadwiga Turo 《Molecules (Basel, Switzerland)》2021,26(17)
We previously described the biosynthesis, isolation, and immunosuppressive activity of the selenium-containing polysaccharide fraction isolated from the mycelial culture of Lentinula edodes. Structural studies have shown that the fraction was a protein-containing mixture of high molar mass polysaccharides α- and β-glucans. However, which of the components of the complex fraction is responsible for the immunosuppressive activity non-typical for polysaccharides of fungal origin has not been explained. In the current study, we defined four-polysaccharide components of the Se-containing polysaccharide fraction determined their primary structure and examined the effect on T- and B-cell proliferation. The isolated Se-polysaccharides, α-1,4-glucan (Mw 2.25 × 106 g/mol), unbranched β-1,6-d-glucan, unbranched β-1,3-d-glucan and β-1,3-branched β-1,6-d-glucan (Mw 1.10 × 105 g/mol), are not typical as components of the cell wall of L. edodes. All are biologically active, but the inhibitory effect of the isolated polysaccharides on lymphocyte proliferation was weaker, though more selective than that of the crude fraction. 相似文献
107.
Danyal Turkoglu Joshua Burke Radoslaw Lewandowski Lei R. Cao 《Journal of Radioanalytical and Nuclear Chemistry》2012,291(2):321-327
A thermal neutron beam facility has been designed and implemented at the Ohio State University Research Reactor. A project
is underway to construct a large vacuum chamber such that the facility could have neutron depth profiling and neutron radiography
capabilities as intended. The neutron beam is extracted from the reactor through a neutron collimator emplaced in Beam Port
#2. The neutron spectrum entering the neutron collimator was unfolded from foil activation analysis results and also simulated
with a full reactor core model in the MCNP Monte Carlo code. The neutron collimator uses polycrystalline bismuth as a gamma
ray filter and single-crystal sapphire as a fast neutron filter. The beam is defined by multiple 3.0 cm diameter apertures
made of borated aluminum. Characterization of the beam was performed using foil activation to find the flux and a low-budget
neutron imaging apparatus to see the beam profile. The modulation transfer function was calculated to offer insight into the
resolution of the imaging system and the collimation of the beam. The neutron collimator delivers the filtered thermal neutron
beam with a ~4 cm diameter and a thermal equivalent flux of (1.27 ± 0.03) × 107 n/(cm2s) at 450 kW power at the end of the collimator. 相似文献
108.
Radoslaw Kwapiszewski Karina Kwapiszewska Jörg P. Kutter Zbigniew Brzozka 《Analytica chimica acta》2015
Lysosomal storage diseases are chronic, progressive and typically have a devastating impact on the patient and the family. The diagnosis of these diseases is still a challenge, however, even for trained specialists. Accurate diagnostic methods and high-throughput tools that could be readily incorporated into existing screening laboratories are urgently required. 相似文献
109.
The aim of this paper is to present an analysis of securitization processes using simulation and optimization methods. We discuss the main risk factors that may affect profitability of the process. These risk factors are interest rates and mortgage prepayments. We combine latest risk factor models to create a consistent framework to analyze and improve securitization processes. We then show that making ad hoc securitization decisions may be far less efficient than by solving optimization problems. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
110.
W. Czaja I. Zschokke-Gränacher 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》1966,17(3):470-470
Ohne Zusammenfassung 相似文献