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81.
A thermosyphon loop is analyzed in this study by use of numerical and experimental techniques. A rectangular loop was constructed
using copper pipe and the sections which were heated or cooled were designed as concentric tube heat exchangers. Hot or cold
water was circulated outside of these sections, and both the surface temperatures and heat transferred to and from the loop
were measured. Within the numerical study both the momentum and energy equations were also solved using a SIMPLEX algorithm.
Numerical results were obtained for laminar flow within the circuit when there was uniform wall temperature in the vertically
heated and cooled sections of the thermosyphon. The two-dimensional numerical model provided results which agree with those
found experimentally from the thermosyphon loop. In addition, a simulation model was constructed using a correlation included
both the Grashof and Prandtl numbers to evaluate heat transfer through a thermosyphon loop. 相似文献
82.
Hüseyin Ünver Mustafa Yıldız Nazan Ocak Tahsin Nuri Durlu 《Journal of chemical crystallography》2008,38(2):103-108
Abstract Schiff base 3-[(2-morpholinoethylimino)methyl]benzene-1,2-diol has been synthesized from the reaction of 4-(2-aminoethyl)morpholine
with 2,3-dihydroxybenzaldehyde. The title compound has been characterized by elemental analysis, IR, 1H-NMR, 13C-NMR and UV–visible techniques. The structure of the compound also has been examined crystallographically. For the compound
exist as dominant form of enol-imines in both the solutions and solid state. The crystal structure has been solved by direct
methods and refined by full-matrix least squares. The title compound crystallize in the monoclinic space group P21/n with a = 12.085(1), b = 8.256(1), c = 13.650(1) ?, β = 108.56(1)°, V = 1291.1(2) ?3, D
x
= 1.288 g cm−3, respectively (R
1 = 0.0336 and wR
2 = 0.0922 for 2117 reflections [I > 2σ(I)].
Index abstract Intramolecular hydrogen bonding is important on the tautomeric properties and the type of aldehyde plays a vital role of the
enol-imine and keto-amine properties of the Schiff base ligand.
相似文献
83.
Tahsin J. Chow 《中国化学会会志》1996,43(1):101-107
The titled compounds are synthesized through multi-step sequences involving consecutive [n4s + n2s] cycloadditions of norbornadiene with two units of chlorinated cyclopentadiene. A dyotropic double hydrogen migration was observed between two closely located double bonds during the process of aromatization of a cyclohexadiene moiety. A hydroxyl group is introduced onto either of the two methylene bridges in order to provide products suitable for solvolytic analyses. 相似文献
84.
Tetracyclic triterpenoids from the leaves of Azadirachta indica and their insecticidal activities 总被引:1,自引:0,他引:1
Siddiqui BS Afshan F Gulzar T Sultana R Naqvi SN Tariq RM 《Chemical & pharmaceutical bulletin》2003,51(4):415-417
A new tetranortriterpenoid, meliatetraolenone [24,25,26,27-tetranor-apotirucalla-(apoeupha)-6alpha-O-methyl, 7alpha-senecioyl(7-deacetyl)-11alpha,12alpha,21,23-tetrahydroxy-21,23-epoxy-2,14,20(22)-trien-1,16-dione] (1) was isolated from the methanolic extract of fresh leaves of Azadirachta indica along with the known compound odoratone (3) which was hitherto unreported from this source. Their structures have been elucidated by spectral studies including 2D NMR. The insecticidal activities of 1 as well as those of odoratone (3) are reported. 1 and odoratone both showed mortality on fourth instar larvae of mosquitoes (Anopheles stephensi) with LC(50) values of 16 and 154 ppm, respectively. 相似文献
85.
A new tetracyclic triterpenoid zeeshanol [25,26,27-trinor-apotirucalla-(apoeupha)-6alpha-, 21-dihydroxy, 7alpha-acetoxy, 1,14,22-tri-en-3, 16-dione] (1) along with a known constituent desfurano-6alpha-hydroxyazadiradione (2) have been isolated from the methanolic extract of the leaves of Azadirachta indica. The structure and the relative configurations of 1 were determined by the spectroscopic method (1H- and 13C-NMR, IR, and MS) and 2D-NMR experiments. 相似文献
86.
Djamal Gacemi Juliette Mangeney Karine Blary Jean-Francois Lampin Thibault Laurent Tahsin Akalin Paul Crozat Fanqi Meng 《Applied Physics A: Materials Science & Processing》2012,109(4):993-995
We investigate surface plasmon waves propagating on planar Goubau lines, so-called Goubau modes, using a guided-wave terahertz spectroscopy system based on a freely positionable electrooptic probe. We show the radial nature of the Goubau mode and its confinement around the Goubau line over a few tenths of microns (??/10). 相似文献
87.
The present study investigated effect of different amplitude levels (40, 70 and 100%), sonication temperatures (40, 50 and 60 °C) and exposure times (3, 7 and 11 min) on steady shear properties; apparent viscosity (η), shear stress (σ), consistency coefficient (K), flow behavior index (n) and dynamic shear properties; storage modulus (G′), loss modulus (G″), complex viscosity (η∗), complex modulus (G∗) and loss tangent (tan δ) values of glucomannan based salep solution (SS) and salep drink (SD) samples. In addition, the steady and dynamic shear properties were optimized using ridge analysis in terms of amplitude level, sonication temperature and exposure times levels. Increasing amplitude level and sonication time decreased considerably the η, σ, K, G′, G″ and η∗ values of salep dispersions (SS and SD samples). However, sonication temperature did not have a remarkable effect on these properties. 相似文献