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排序方式: 共有214条查询结果,搜索用时 15 毫秒
81.
Nitromethane pyrolysis in shock tubes and a micro flow reactor with a controlled temperature profile
Olivier Mathieu Nabiha Chaumeix Yoshimichi Yamamoto Said Abid Claude-Etienne Paillard Takuya Tezuka Hisashi Nakamura Clayton R. Mulvihill Eric L. Petersen 《Proceedings of the Combustion Institute》2021,38(1):1007-1015
Nitromethane has many applications, such as in racing, as a gasoline fuel additive, and as a monopropellant. Despite a large number of studies and the small size of the molecule, the combustion chemistry of nitromethane is still not well understood. To improve models, the pyrolysis of nitromethane (CH3NO2) was investigated experimentally in shock tubes and in a micro flow reactor with a controlled temperature profile (MFR), under dilute conditions. Several spectroscopic diagnostics were used in the shock tubes to follow the concentration time histories of CO, H2O (both using IR laser absorption), and CH3NO2 (UV light absorption). A quadrupole mass spectrometer was used to measure CH3NO2, NO2, CH4, C2H4, and C2H2 at various temperatures with the MFR. These unique experimental results were compared to modern, detailed kinetics models from the literature, and no mechanism was able to reproduce these data over the wide range of conditions investigated. Predictions for the CO and H2O levels were generally inaccurate, and the CH4, C2H4, and C2H2 predictions were poor in most cases for the MFR data. Importantly, all models largely differ in their predictions. A numerical analysis was performed to identify ways to improve the next generation of nitromethane models. Results indicate that nitromethane decomposition needs to be improved below 1050 K, and that hydrocarbon-NOx interactions still need to be further investigated. 相似文献
82.
Muhammad Junaid Iqbal Khan Zarfishan Kanwal Masood Yousaf Hamid Ullah Javed Ahmad Abid Latif Yong-Han Shin Ata Ur Rahman Khalid 《理论物理通讯》2021,73(3):35701-147
The development of new materials,having exceptional properties in comparison to existing materials is highly required for bringing advancement in electronic and optoelectronic technologies.Keeping this fact,we investigated structural,electronic,and optical properties of zincblende GaN doped with selected Zn concentrations(6.25%,12.50%,and 18.70%),using the first-principle calculations based on density functional theory with GGA+U.We conducted the entire study using the WIEN2K code.In this study,we calculated various significant parametric quantities such as cohesive energies,formation energies,bulk moduli,and lattice constants along with the study of optical and electronic properties by substituting Ga atoms with Zn atoms in 1×2×2 supercell.The structural stability is confirmed by studying the phonon dispersion curves which suggest that Zn:GaN material is stable against the 6.25%and 18.70%Zn concentrations while for 12.50%,it shows instability.The Hubbard values U=0,2,4,6 eV were added to GGA and the electronic properties were improved with the U=6 eV.Optical absorption was blue shifted while the refractive index and dielectric constant were increased with increasing the Zn concentrations.Electronic properties are enhanced due to the prime contribution of cations(Zn)3ri states.The optical and electronic properties are further discussed in detail in the entire study. 相似文献
83.
Dammak T Fourati N Abid Y Boughzala H Mlayah A Minot C 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2007,66(4-5):1097-1101
Single crystals of L-histidine oxalate were obtained by slow evaporation of an aqueous solution at room temperature. The grown crystals have been subjected to X-ray diffraction (XRD), Infrared, and Raman spectroscopy. The title compound crystallises in the non-centrosymmetric space group P2(1)2(1)2(1,) the crystal cohesion is achieved by relatively strong hydrogen bonds, so that the NH3 groups show significant distortion with respect to the tetrahedral symmetry. Raman and infrared spectra of the title compound were recorded in the frequency range 300-3200 and 400-4000 cm-1, respectively. To obtain a reliable assignment of the observed spectral lines, we have calculated the geometry and the frequencies of the vibrational modes of histidine cation and the oxalate anion using the semi empirical PM3 method. 相似文献
84.
F Boukattaya A Stanovych P Setzer S Abid H Ammar MS Pearson-Long P Bertus 《Chemical communications (Cambridge, England)》2012,48(69):8655-8657
The double addition of Grignard (alkyl, aryl, alkenyl, alkynyl) reagents to acyl cyanohydrins was performed under unusually smooth conditions with a concomitant O-N acyl transfer, providing a very simple and general access to α,α,α-trisubstituted amides. 相似文献
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88.
B. Dipierro M. Abid 《The European Physical Journal B - Condensed Matter and Complex Systems》2012,85(2):69
Using linear instability theory and nonlinear dynamics, the Rayleigh-Taylor instability
of variable density swirling flows is studied. It is found that the flow topology could be
predicted, when the instability sets in, using a function χ dependent on
density and axial and azimuthal velocities. It is shown that even when the inner
axial-flow is heavier than the outer one (a favorable case for the development of the
Rayleigh-Taylor instability thanks to the centrifugal force) the instability is not
necessarily Rayleigh-Taylor-dominated. It is also shown that when the Rayleigh-Taylor
instability develops, it is helical. 相似文献
89.
An organic-inorganic hybrid perovskite (C4H9NH3)4Pb3I4Br6 was synthesized and studied by X-ray diffraction, Raman and infrared spectroscopies, optical transmission and photoluminescence. The title compound, abbreviated (C4)4Pb3I4Br6, crystallises in a periodic two-dimensional multilayer structure with P21/a space group. The structure is built up from alternating inorganic and organic layers. Each inorganic layer consists of three sheets of PbX6 (X=I, Br) octahedra. Raman and infrared spectra of the title compound were recorded in the 100-3500 and 400-4000 cm−1 frequency ranges, respectively. An assignment of the observed vibration modes is reported. Optical transmission measurements, performed on thin films of (C4)4Pb3I4Br6, revealed two absorption bands at 474 and 508 nm. Photoluminescence measurements have shown a green emission peak at 519 nm. 相似文献
90.
A subgroup H of a finite group G is said to be s-semipermutable in G if it is permutable with every Sylow p-subgroup of G with (p, |H|) = 1. We say that a subgroup H of a finite group G is S-semiembedded in G if there exists an s-permutable subgroup T of G such that TH is s-permutable in G and T ∩ H ≤ H s ¯ G , where H s ¯ G is an s-semipermutable subgroup of G contained in H. In this paper, we investigate the influence of S-semiembedded subgroups on the structure of finite groups. 相似文献