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571.
Khalid Hadi Ryo Ichimura Nozomu Hashimoto Osamu Fujita 《Proceedings of the Combustion Institute》2019,37(3):2935-2942
The present study aims to clarify the effects of turbulence intensity and coal concentration on the spherical turbulent flame propagation of a pulverized coal particle cloud. A unique experimental apparatus was developed in which coal particles can be dispersed homogeneously in a turbulent flow field generated by two fans. Experiments on spherical turbulent flame propagation of pulverized coal particle clouds in a constant volume spherical chamber in various turbulence intensities and coal concentrations were conducted. A common bituminous coal was used in the present study. The flame propagation velocity was obtained from an analysis of flame propagation images taken using a high-speed camera. It was found that the flame propagation velocity increased with increasing flame radius. The flame propagation velocity increases as the turbulence intensity increases. Similar trends were observed in spherical flames using gaseous fuel. The coal concentration has a weak effect on the flame propagation velocity, which is unique to pulverized coal combustions in a turbulent field. These are the first reports of experimental results for the spherical turbulent flame propagation behavior of pulverized coal particle clouds. The results obtained in the present study are obviously different from those of previous pulverized coal combustion studies and any other results of gaseous fuel combustion research. 相似文献
572.
The Vlasov–Maxwell equations were numerically solved to calculate the ion‐beam flux from the plasma of argon and the plasma of mixtures of argon and neon. Some experiments were performed to measure the ion beam from the Amirkabir plasma focus (APF) device. The calculations have shown that the argon ion‐beam flux peaked up to 1.928 × 1030 ions m?2 s?1 at the optimum pressure of 1.866 mbar while the neon‐argon mixture's ion‐beam flux reached a maximum of 4.301 × 1030 ions m?2 s?1 for 15% neon admixture at the optimum pressure of 1.866 mbar. The calculated kinetic energy of the ion beam has shown a maximum value of 708.7 J for the mixture of 85% argon‐15% neon at the mentioned optimum pressure. 相似文献
573.
Seyed Ahmad Sangsefedi Soheil Sharifi Hadi Rastegar Moghaddam Rezaion Afshin Azarpour 《Journal of fluorescence》2018,28(3):815-825
The enhancement of the nonlinear properties of materials is an interesting topic since it has many applications in optical devices and medicines. The Z-scan technique was used to study the values of the two-photon absorption (β), second-order molecular hyperpolarizability (γR), third-order susceptibility (χR), and nonlinear refractive index (n2) of Alizarin Red S in different media using a continuous-wave diode-pump laser radiation at 532 nm. For Alizarin Red S in a droplet, the β, n2, χR, and γR were estimated at the order of 10?7 cm2/W and 10?12 cm/W, 10?3 m3 W?1 s?1 and 10?24 m6 W?1 s?1, respectively. The results indicated that the values of β and n2 reduced, whereas the values of χR and γR were enhanced when the solvent was changed from droplet to water, DMF, and dimethyl sulfoxide due to the change in the solvent’s dielectric constant (ε). Moreover, the values of β were enhanced by an increase in the concentration of the surfactant in the aqueous solution. The absorption spectra of Alizarin Red S in the aqueous solution was observed at 428 nm, and a few red shifts in the absorption spectra were observed with a reduction in the dielectric constant of the medium. The same effect was observed in the absorption spectra of Alizarin Red S in the droplet when the bulk dielectric constant reduced. The dielectric constant can affect the fluorescence spectra of Alizarin Red S when the solution is changed from water to dimethyl sulfoxide. The dipole moments of Alizarin Red S in the different media were studied using the quantum perturbation theory. 相似文献
574.
575.
Benzyltriphenylphosphonium peroxymonosulfate could be used for selective oxidation of aromatic and aliphatic sulfides and thiols to their corresponding sulfoxides and disulfides under nonaqueous and aprotic conditions without catalyst. 相似文献
576.
α-Phenylthio-, a α-phenylsulfono- and α-phenylseleno-cyclohexananone have the prefered conformation with the substituent axial whereas the α-phenoxy and α-phenylsulfoxo-cyclohexanones have the substituent equatorial. 相似文献
577.
Harun Akkus Amirullah M. Mamedov Ali Kazempour Hadi Akbarzadeh 《Central European Journal of Physics》2008,6(1):64-75
The electronic structure, linear, and non-linear optical properties of ferroelectric-semiconductor SbSBr are investigated
in the non-polar (paraelectric) and polar (ferroelectric) phase, using the density functional methods in the generalized gradient
approximation. The electronic band structure obtained shows that SbSBr has an indirect forbidden gap of 2.16 and 2.21 eV in
the paraelectric and ferroelectric phase, respectively. The linear photon-energy dependent dielectric functions and some optical
functions, such as absorption and extinction coefficients, refractive index, energy-loss function, reflectivity, and optical
conductivity in both phases and photon-energy dependent second-order susceptibilities in the ferroelectric phase are calculated.
Moreover, some important optical parameters, such as the effective number of valence electrons and the effective optical dielectric
constant, are calculated in both phases.
相似文献
578.
Lioe H Barlow CK O'Hair RA 《Journal of the American Society for Mass Spectrometry》2009,20(2):238-246
Low-energy collision-induced dissociation (CID) of acetylcholine (ACh) yields only two fragment ions: the dominant C(4)H(7)O(2)(+) ion at m/z 87, arising from trimethylamine loss; and protonated trimethylamine at m/z 60. Since the literature is replete with conflicting mechanisms for the loss of trimethylamine from ACh, in this article density functional theory (DFT) calculations are used to assess four competing mechanisms: (1) Path A involves a neighboring group attack to form a five-membered ring product, 2-methyl-1,3-dioxolan-2-ylium cation; (2) Path B is a neighboring group attack to form a three-membered ring product, 1-methyl-oxiranium ion; (3) Path C involves an intramolecular elimination reaction to form CO protonated vinylacetate; and (4) Path D is a 1,2-hydride migration reaction forming CH(2)-protonated vinylacetate. At the MP2/6-311++G(2d,p)//B3-LYP/6-31+G(d,p) level of theory path A is the kinetically favored pathway, with a transition-state energy barrier of 37.7 kcal mol(-1) relative to the most stable conformer of ACh. The lowest energy pathway for the formation of protonated trimethylamine was also calculated to proceed via path A, involving proton transfer within the ion-molecule complex intermediate, with the exocylic methyl group being the proton donor. To confirm the site of proton transfer, low-energy CID of acetyl-d(3)-choline (d(3)-ACh) was carried out, which revealed loss of trimethylamine and the formation of Me(3)ND(+). 相似文献
579.
Samira Saeednia Parvaneh Iranmanesh Hadi Amiri Rudbari Leyla Saeednia 《高分子科学杂志,A辑:纯化学与应用化学》2016,53(4):227-236
Single crystal of a new one-dimensional copper organic coordination polymer, 1D-CuOCP, [Cu(HL)NO3]n (1) (H2L = [2-[1-(2-hydroxy-propylimino)-ethyl]-phenol]) and its nanostructure, have been synthesized by slow evaporation of methanol solution of compound (1) and sonochemical process respectively. Nanostructure of the complex was characterized by X-ray powder diffraction (XRD), FT-IR spectroscopy and scanning electron microscopy (SEM) and the structure of compound 1 was determined by single-crystal X-ray diffraction. Thermal stability of compound 1 in its nanosize form has also been studied by thermal gravimetric analysis (TGA). The effect of concentration of initial reagents on size and morphology of nanostructured compound 1 has been examined. The brightness of this study is to use the nanostructure of 1D-CuOCP as precursor to prepare single phase CuO nanoparticles via a solid-state decomposition procedure. Characterization methods confirmed that CuO nanoparticles with an average diameter of 40 nm were obtained from direct calcination of the precursor at 500°C under air. 相似文献
580.
Graphene Oxide/ZnO Nano Composite for Sensitive and Selective Electrochemical Sensing of Levodopa and Tyrosine Using Modified Graphite Screen Printed Electrode 下载免费PDF全文
Determination of levodopa and tyrosine as two important species for treatment of Parkinson's disease is described. A novel electrochemical sensor involving graphene oxide/ZnO nanorods (GR/ZnO) nano composite and the graphite screen‐printed electrodes (GSPE) was developed for the simultaneous detection of levodopa and tyrosine. The screen‐printed electrodes with several advantages, including low cost, versatility and miniaturization were employed. On the other hand, the graphene oxide/ZnO nanorods nano composite was casted on the surface of GSPE to obtain GR/ZnO/SPE. The proposed nano sensor has excellent performance such as high sensitivity, good selectivity and analytical application in real samples. The combination of graphene oxide/ZnO nanorods nano composite with the screen‐printed electrode is favorable for amplifying electrochemical signals. Under optimized conditions square wave voltammetry (SWV) exhibited linear dynamic ranges from 1.0×10?6 to 1.0×10?3 M and 1.0×10?6 to 8.0×10?4 M with detection limits of 4.5×10?7 M and 3.4×10?7 M for levodopa and tyrosine respectively. 相似文献