排序方式: 共有46条查询结果,搜索用时 15 毫秒
31.
Martin Lindberg Andris Vaivads Savvas Raptis Per-Arne Lindqvist Barbara L. Giles Daniel Jonathan Gershman 《Entropy (Basel, Switzerland)》2022,24(6)
We use Magnetospheric Multiscale (MMS) data to study electron kinetic entropy per particle across Earth’s quasi-perpendicular bow shock. We have selected 22 shock crossings covering a wide range of shock conditions. Measured distribution functions are calibrated and corrected for spacecraft potential, secondary electron contamination, lack of measurements at the lowest energies and electron density measurements based on plasma frequency measurements. All crossings display an increase in electron kinetic entropy across the shock being positive or zero within their error margin. There is a strong dependence of on the change in electron temperature, , and the upstream electron plasma beta, . Shocks with large have large . Shocks with smaller are associated with larger . We use the values of , and density change to determine the effective adiabatic index of electrons for each shock crossing. The average effective adiabatic index is . 相似文献
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The reaction between benzaldehyde and ethyl cyanoacetate is investigated in 1,3-dialkylimidazolium salts as solvents. The impact of both ions in these ionic liquids on the yield of the condensation reaction product is examined. Potentiometric titrations are employed for quantitative analyses of the best ionic liquids, revealing these to be 1,3-dialkylimidazolium dimethyl phosphates. 相似文献
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A previously published nuclear magnetic resonance (NMR) spectroscopic imaging method for mapping static magnetic fields has been modified, replacing the gradient echo sequence with an asymmetric spin echo sequence. The purpose of the modification is to reinforce the technique and make it useable even in conditions in which the gradient echo sequence cannot be operated. The modification performed was verified by an experiment performed on a low-field NMR scanner. The rough and fine errors due to the long time of measurement were corrected during the processing of the measured images. An optimization procedure was used to correct the fine errors. The map of the static magnetic field acquired using the new technique was compared to the map calculated from the phase images and both were compared to the result measured using a magnetometer. The verification confirmed the legitimacy of the modification and suitability of the novel technique. Some alternatives to the measured data processing have been suggested, shortening the global time of the measurement. 相似文献
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Inside Cover: Spectroscopic Characterization and Reactivity of Triplet and Quintet Iron(IV) Oxo Complexes in the Gas Phase (Angew. Chem. Int. Ed. 11/2016)
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36.
Andris Zicmanis Galina Vavilina Svetlana Drozdova Peteris Mekss Maris Klavins 《Central European Journal of Chemistry》2007,5(1):156-168
Alkylation of indole salts in different ionic liquids is reported. Ionic liquids increase the alkylation reaction rate of
ambident indole anion and reduce the effects of counter ions and/or additives, the alkylation reaction rates being independent
of the presence of small amounts of protic solvents or water.
相似文献
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We present in situ measurements in a space plasma showing that thin current sheets the size of an ion inertial length exist and are abundant in strong and intermittent plasma turbulence. Many of these current sheets exhibit the microphysical signatures of reconnection. The spatial scale where intermittency occurs corresponds to the observed structures. The reconnecting current sheets represent a type of dissipation mechanism, with observed dissipation rates comparable to or even dominating over collisionless damping rates of waves at ion inertial length scales (x100), and can have far reaching implications for small-scale dissipation in all turbulent plasmas. 相似文献
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Kalnina I Zvagule T Gabruseva N Kirilova J Kurjane N Bruvere R Kesters A Kizane G Kirilovs G Meirovics I 《Journal of fluorescence》2007,17(6):633-638
ABM (3-aminobenzanthrrone derivative) developed at the Riga Technical University, Riga, Latvia) has been previously shown
as a potential probe for determination of the immune state of patients with different pathologies .The fist study (using probe
ABM) of peripheral blood mononuclear cells (PBMC) membranes of 97 Chernobyl clean-up workers from Latvia was conducted in
1997. Now we repeatedly examine the same (n = 54) individuals in dynamics. ABM spectral parameters in PBMC suspension, fluorescence
anisotropy and blood plasma albumin characteristics were recorded. In 1997 screening showed 5 different patterns of fluorescence
spectra, from which in 2007 we obtained only two. These patterns of spectra had never been previously seen in healthy individuals
or patients with tuberculosis, multiple sclerosis, rheumatoid arthritis, etc., examined by us. Patterns of ABM fluorescence
spectra are associated with membrane anisotropy and conformational changes of blood plasma albumin. We observed that in dynamics
1997–2007 the lipid compartment of the membrane became more fluid while the lipid-protein interface became more rigid. The
use of probe ANS and albumin auto-fluorescence allowed show conformational alterations in Chernobyl clean-up workers blood
plasma. It is necessary to note that all investigated parameters significantly differ in observed groups of patients. These
findings reinforce our understanding that that the cell membrane is a significant biological target of radiation. The role
of the membrane in the expression and course of cell damage after radiation exposure must be considered. So ten years dynamic
of PBMC membrane characteristics by ABM (spectral shift and anisotropy indexes) in Chernobyl clean-up workers reveal progressive
trend toward certain resemblance with those of chronic B-cell lymphoid leukemia. 相似文献
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Vladimir V. Chernyshev Sanita Petkune Andris Actins Raimonds Auzins Dmitry I. Davlyatshin Pavel V. Nosyrev Yurii A. Velikodny 《Acta Crystallographica. Section C, Structural Chemistry》2013,69(3):299-302
Afobazole {systematic name: 2‐[2‐(morpholin‐4‐yl)ethylsulfanyl]‐1H‐benzimidazole} is a new anxiolytic drug and Actins, Auzins & Petkune [(2012). Eur. Patent EP10163962] described four polymorphic modifications. In the present study, the crystal structures of two monoclinic polymorphs, 5‐ethoxy‐2‐[2‐(morpholin‐4‐ium‐4‐yl)ethylsulfanyl]‐1H‐benzimidazol‐3‐ium dichloride, C15H23N3O2S2+·2Cl−, (II) and (IV), have been established from laboratory powder diffraction data. The crystal packing and conformation of the dications in (II) and (IV) are different. In (II), there are channels in the [001] direction, which offer atmospheric water molecules an easy way of penetrating into the crystal structure, thus explaining the higher hygroscopicity of (II) compared with (IV). 相似文献
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