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61.
The interaction of two parallel plane jets of different velocities is studied by flow visualization and PIV measurement to
examine the influence of velocity ratio on the development ofjets in the initial region. It is found that the parallel plane
jets develop toward the high velocity side and the jet width is reduced with a decrease in the jet velocity ratio. Corresponding
to the variation of mean velocity field to the velocity ratio, the magnitudes of turbulence intensities, Reynolds stress and
static pressure are weakened in the merging region of the jets and their peak locations of the properties are shifted to the
high velocity side. These results indicate that the interaction of two parallel jets is weakened with a decrease in the velocity
ratio of the jets. 相似文献
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The hexane extract of dried fruits of Piper longum on fractionation afforded a new alkamide, isodihydropiperlonguminine and two phenyl propanoic acid derivatives. The structures of these compounds are established based on spectroscopic evidence and synthesis. 相似文献
66.
Archiv der Mathematik - We investigate the class number one problem for a parametric family of real quadratic fields of the form $$\mathbb {Q}( \sqrt{m^2+4r})$$ for certain positive integers m and r. 相似文献
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M. Ramesh B. Raju M. George K. Srinivas V. Jayathirtha Rao K. Bhanuprakash R. Srinivas 《Journal of mass spectrometry : JMS》2012,47(7):860-868
The electrospray ionization collisionally activated dissociation (CAD) mass spectra of protonated 2,4,6‐tris(benzylamino)‐1,3,5‐triazine (1) and 2,4,6‐tris(benzyloxy)‐1,3,5‐triazine (6) show abundant product ion of m/z 181 (C14H13+). The likely structure for C14H13+ is α‐[2‐methylphenyl]benzyl cation, indicating that one of the benzyl groups must migrate to another prior to dissociation of the protonated molecule. The collision energy is high for the ‘N’ analog (1) but low for the ‘O’ analog (6) indicating that the fragmentation processes of 1 requires high energy. The other major fragmentations are [M + H‐toluene]+ and [M + H‐benzene]+ for compounds 1 and 6, respectively. The protonated 2,4,6‐tris(4‐methylbenzylamino)‐1,3,5‐triazine (4) exhibits competitive eliminations of p‐xylene and 3,6‐dimethylenecyclohexa‐1,4‐diene. Moreover, protonated 2,4,6‐tris(1‐phenylethylamino)‐1,3,5‐triazine (5) dissociates via three successive losses of styrene. Density functional theory (DFT) calculations indicate that an ion/neutral complex (INC) between benzyl cation and the rest of the molecule is unstable, but the protonated molecules of 1 and 6 rearrange to an intermediate by the migration of a benzyl group to the ring ‘N’. Subsequent shift of a second benzyl group generates an INC for the protonated molecule of 1 and its product ions can be explained from this intermediate. The shift of a second benzyl group to the ring carbon of the first benzyl group followed by an H‐shift from ring carbon to ‘O’ generates the key intermediate for the formation of the ion of m/z 181 from the protonated molecule of 6. The proposed mechanisms are supported by high resolution mass spectrometry data, deuterium‐labeling and CAD experiments combined with DFT calculations. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
69.
Biswanath Das Yallamalla Srinivas Chithaluri Sudhakar Parigi Raghavendar Reddy 《Helvetica chimica acta》2011,94(7):1290-1295
The stereoselective synthesis of the naturally occurring dihydropyranone rugulactone has been accomplished starting from 3‐phenylpropan‐1‐ol employing Maruoka allylation and ring‐closing metathesis as the key steps. 相似文献
70.
An efficient and mild method for tetrahydropyranylation of alcohols and their detetrahydropranylation using NH4Cl is described. This protocol provides a useful alternative tetrahydropyranylation of alcohols and their deprotection at different pH. 相似文献