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51.
In order to determine the characteristics of the peristaltic transport of shear thinning non-Newtonian materials, the motion of a third-order fluid in a planar channel having walls that are transversely displaced by an infinite, harmonic traveling wave of large wavelength and negligibly small Reynolds number was analyzed using a perturbation expansion in terms of a variant of the Deborah number. Within the range of validity of this analysis, we found the pumping rate of a shear-thinning fluid is less than that for a Newtonian fluid having a shear viscosity the same as the lower-limiting viscosity of the nonNewtonian material. Also, the space of variables for which trapping of a bolus of fluid occurs is reduced for the shear-thinning fluid investigated here. 相似文献
52.
Saleha S. Khan Afsar Khan Amir Ahmed Viqar U. Ahmad Umar Farooq Saima Arshad Sadia Bader Aqib Zahoor Imran N. Siddiqui Bilge Sener Nurgun Erdemoglu 《Helvetica chimica acta》2010,93(10):2070-2074
From the aerial parts of Zygophyllum fabago, two new monosodium salts of sulfated derivatives of ursolic acid, along with two known quinovic acid glycosides were isolated. The structures of the new compounds were determined as (3β,4α)‐3,23,30‐trihydroxyurs‐20‐en‐28‐al 3,23‐di(sulfate) sodium salt (1 : 1) ( 1 ) and of (3β,4α)‐3,23,28‐trihydroxyurs‐20‐en‐30‐yl β‐D ‐glucopyranoside 3,23‐di(sulfate) sodium salt (1 : 1) ( 2 ) with the molecular formula C30H47NaO10S2 and C36H59NaO15S2, respectively. The structures of the known compounds were 3‐O‐(2‐O‐sulfo‐β‐D ‐quinovopyranosyl)quinovic acid 28‐β‐D ‐glucopyranosyl ester ( 3 ) and 3‐O‐(β‐D ‐glucopyranosyl)quinovic acid 28‐β‐D ‐glucopyranosyl ester ( 4 ) (quinovic acid=(3β)‐3‐hydroxyurs‐12‐ene‐27,28‐dioic acid). The structures of all these compounds were determined by using 1D‐ and 2D‐NMR spectroscopic techniques. 相似文献
53.
Effect of dicationic gemini surfactants C16H33(CH3)2N+-(CH2)
s
-N+(CH3)2C16H33, 2Br− (where s = 4, 5, 6) on the reaction of ninhydrin with L-isoleucine has been investigated spectrophotometrically as a function of [gemini],
[L-isoleucine], [ninhydrin], and pH. The reaction follows first- and fractional-order kinetics, respectively, in [L-isoleucine]
and [ninhydrin]. The gemini surfactant micellar media are found more effective for the reaction than their conventional monomeric
counterpart CTAB. Furthermore, whereas typical rate constant (k
ψ) increase and leveling-off regions are observed with CTAB and geminis, the latter produce a third region of increasing k
ψ at concentrations ≥ 60 cmc’s. 1H NMR studies reveal that this unusual third-region effect of the geminis is due to changes in their micellar morphologies.
Quantitative kinetic analysis has been performed on the basis of modified pseudo-phase model. 相似文献
54.
55.
Siddiqui Madiha M. Nagargoje Amol A. Akolkar Satish V. Sangshetti Jaiprakash N. Khedkar Vijay M. Pisal Parshuram M. Shingate Bapurao B. 《Research on Chemical Intermediates》2022,48(3):1199-1225
Research on Chemical Intermediates - A simple and efficient protocol has been developed for the synthesis of new1,2,3-triazole-2,3-dihydroquinazolin-4[1H]-one (DHQ) conjugates(6a?j) via... 相似文献
56.
In view of the attributed medicinal properties of beta-carboline alkaloids, some new O-acyl derivatives of beta-carboline alkaloid--harmol, were prepared and tested for possible antimycobacterial activity against Mycobacterium tuberculosis H37Rv. 相似文献
57.
Electrolytic Macrocyclizations: Scalable Synthesis of a Diazonamide‐Based Drug Development Candidate 下载免费PDF全文
Dr. Hui Ding Patrick L. DeRoy Christian Perreault Dr. Alexandre Larivée Dr. Arshad Siddiqui Dr. Charles G. Caldwell Susan Harran Prof. Dr. Patrick G. Harran 《Angewandte Chemie (International ed. in English)》2015,54(16):4818-4822
An electrochemical method to synthesize the core macrolactam of diazonamides is described. Large ring‐forming dehydrogenation is initiated by anodic oxidation at a graphite surface. The reaction requires no tailoring of the substrate and occurs at ambient temperature in aqueous DMF in an undivided cell open to air. This unique chemistry has enabled a concise, scalable preparation of DZ‐2384; a refined analog of diazonamide A slated for clinical development as a cancer therapeutic. 相似文献
58.
59.
Technetium-99 is preconcentrated from acidified seawater containing a trace of bromine by adsorbing it as the pertechnetate ion on the anion exchanger Duolite A101D. After elution with 4 M nitric acid, it is purified from other radionuclides by scavenging with hydrous iron(III) oxide and extracting from 5 M sodium hydroxide medium into methyl ethyl ketone. The organic phase is then evaporated and technetium is electrodeposited from oxalic acid medium onto a bronze disc and counted with a low background β-counter. Overall recovery is > 90% and the precision is ±0.2 pCi l-1 at a technetium level of 0.6–1.0 pCi l-1. Concentrations of the radionuclide in the central Irish Sea were found to lie in the range 0.4–2 pCi l-1. The same analytical scheme can be used for determining the element in nitric acid digests of marine algae. 相似文献
60.
Analysis of regular and irregular acoustic streaming patterns in a rectangular enclosure 总被引:1,自引:0,他引:1
This study reports an experimental investigation of the non-linear phenomena of regular (classical) and irregular streaming patterns generated in an air-filled rigid-walled square channel subjected to the acoustic standing waves of different frequencies and intensities. The interaction of acoustic waves and thermoviscous fluids is responsible for these phenomena. The resonator’s walls are maintained at isothermal condition. Synchronized particle image velocimetry (PIV) technique has been used to measure the streaming velocity fields. The experimental results show that at a given excitation frequency, regular streaming flow patterns are observed up to a certain value of the excitation amplitude. As the amplitude increases beyond this limit, the regular streaming is distorted to an irregular flow structure. The regular and irregular streaming are classified in terms of streaming Reynolds number . It is found that for Res2<50, classical streaming flow patterns are established and then deform to irregular and complex shapes as Res2 exceeds 50. 相似文献