نتایج جستجو برای: chemical models
تعداد نتایج: 1262564 فیلتر نتایج به سال:
We have undertaken a 330–360 GHz molecular line survey of the halo gas surrounding the hot core associated with G34.26+0.15. In contrast to our molecular line survey of the hot core itself, where 338 lines from at least 38 species were detected, only 18 lines from 9 species were detected in the halo. The lines are mainly single transitions of simple di-atomic and triatomic molecules. Lower limi...
Convolutamydine A has been shown to develop a significant antinociceptive effect. Here we demonstrated that new analogues (5-iodo-3-(2-oxopropyl)-3-hydroxy-2-oxindole (5-Iisa), 5-fluoro-3-(2-oxopropyl)-3-hydroxy-2-oxindole (5-Fisa), 5-chloro-3-(2-oxopropyl)-3-hydroxy-2-oxindole (5-Clisa) and 5-methyl-3-(2-oxopropyl)-3-hydroxy-2-oxindole (5-Meisa)), at 0.1-10mg/kg doses, have significant periphe...
For the quantitative understanding of complex chemical reaction mechanisms, it is, in general, necessary to accurately determine the corresponding free energy surface and to solve the resulting continuous-time reaction rate equations for a continuous state space. For a general (complex) reaction network, it is computationally hard to fulfill these two requirements. However, it is possible to ap...
We report on the first far–IR detection of H 2 D + , using the Infrared Space Observatory, in the line of sight toward Sgr B2 in the galactic center. The transition at λ=126.853 µm connecting the ground level of o-H 2 D + , 1 1,1 , with the the 2 1,2 level at 113 K, is observed in absorption against the continuum emission of the cold dust of the source. The line is broad, with a total absorptio...
We present a clear detection of CH 2 in absorption towards the molecular cloud complexes Sagittarius B2 and W49 N using the ISO Long Wavelength Spectrometer. These observations represent the first detection of its low excitation rotational lines in the interstellar medium. Towards Sagittarius B2, we detect both ortho and para transitions allowing a determination of the total CH 2 column density...
We present observations of molecular high-energy radiation probes and report the first detections of CO + toward W3 IRS5, a source containing ultracom-pact HII regions. UV radiation and X-rays from the central objects may enhance molecules due to photodissociation and ionization processes. To study the effects on the immediate YSO environment, we are developing time-and depth-dependant chemical...
We have extensively mapped a sample of dense molecular clouds (L1512, TMC-1C, L1262, Per7, L1389, L1251E) in lines of HC3N, CH3OH, SO and C18O. We demonstrate that a high degree of chemical differentiation is present in all of the observed clouds. We analyse the molecular maps for each cloud, demonstrating a systematic chemical differentiation across the sample, which we relate to the evolution...
Many chemical models of dense interstellar clouds predict that the majority of gas-phase elemental nitrogen should be present as N(2), with an abundance approximately five orders of magnitude less than that of hydrogen. As a homonuclear diatomic molecule, N(2) is difficult to detect spectroscopically through infrared or millimeter-wavelength transitions. Therefore, its abundance is often inferr...
Stable isotope-labeling methods, coupled with novel techniques for detecting fast-relaxing NMR signals, now permit detailed investigations of paramagnetic centers of metalloproteins. We have utilized these advances to carry out comprehensive assignments of the hyperfine-shifted (13)C and (15)N signals of the rubredoxin from Clostridium pasteurianum (CpRd) in both its oxidized and reduced states...
It is not common to consider the role of uncertainties in the rate coefficients used in interstellar gasphase chemical models. In this paper, we report a new method to determine both the uncertainties in calculated molecular abundances and their sensitivities to underlying uncertainties in the kinetic data utilized. The method is used in hot core models to determine if previous analyses of the ...
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