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11.
12.
Levenback BJ Sehgal CM Wood AK 《The Journal of the Acoustical Society of America》2012,131(1):540-549
Antivascular ultrasound consisting of low-intensity sonication in the presence of circulating microbubbles of an ultrasound contrast agent has been demonstrated to disrupt blood flow in solid cancers. In this study a mathematical framework is described for the microbubble-induced heating that occurs during antivascular ultrasound. Biological tissues are modeled as a continuum of microbubble-filled vasculature, cells, and interstitial fluids with compressibility equal to the sum of the compressibility of each component. The mathematical simulations show that the absorption of ultrasound waves by viscous damping of the microbubble oscillations induced significant local heating of the tissue vasculature. The extent and the rate of temperature increase not only depends on the properties of the microbubbles and the sonication parameters but is also influenced markedly by the blood flow. Slow flow conditions lead to higher tissue temperatures due to a stronger interaction between microbubbles and ultrasound and reduced heat dissipation. Because tumors have slower blood flow than healthy tissue, the microbubble-induced ultrasound antivascular therapy is likely to affect cancerous tissue more extensively than healthy tissue, providing a way to selectively target the vasculature of cancers. 相似文献
13.
G.W. Griffin D.C. Lankin N.S. Bhacca H. Terasawa R.K. Sehgal 《Tetrahedron letters》1982,23(27):2753-2756
Oxaziridines are proposed as intermediates in the photoinduced cycloadditions of electron deficient nitrones to dipolarophiles. 相似文献
14.
Akihisa?Kaneko Pankaj?Sehgal Hidekazu?DoeEmail author 《Colloid and polymer science》2012,290(4):323-330
The pH dependence of an anionic surfactant, sodium N-dodecanoylsarcosinate (SLAS), has been studied by measuring interfacial tension, fluorescence, dynamic light scattering,
etc., in aqueous solutions with phosphate and borate buffers. The interfacial tension (γ) of SLAS decreases remarkably with a pH decrease and is constant at pH > 7.3. The observed values for the critical micelle
concentration (cmc) and the surfactant concentration at which its γ value is reduced by 20 mN/m from that of pure water (C
20) decrease with a pH decrease, while those also become constant at pH > 6.5 and >7.3, respectively. On the other hand, the
interfacial excess of SLAS increases at pH < 7.3. These interfacial behaviors have been further investigated by the addition
of Tl+ which replaces Na+ of SLAS. The observed γ values of LAS− with the different counter cations are in the order of H+ < Tl+ < Na+. In order to reveal aggregation properties of SLAS, the aggregation number (N
agg), the micropolarity, the hydrodynamic radius (R
h) of micelle, and the fluorescence anisotropy of Rhodamine B (r) have been evaluated at various pHs. The N
agg value shows a decreasing tendency with a pH increase. The I
1/I
3 ratio and the R
h values do not strongly depend on pH. The r value decreases until pH 7 and remains constant at pH > 7.0. These interfacial and micelle properties have been discussed
in detail considering the electrostatic interaction and the molecular structures of the hydrophilic headgroup. 相似文献
15.
A series of nitroimidazoles were subjected to hydroxymethylations under a variety of conditions. Hydroxymethylation of 1-(2-hydroxyethyl), 1-(2-acetoxyethyl), and 1-(2-chloroethyl) substituted 5-nitroimidazoles with paraformaldehyde in dimethyl sulfoxide yielded the respective 2-hydroxymethyl analogs (5–7). However, attempts to hydroxymethylate 1-(2-hydroxyethyl), 1-(2-acetoxyethyl), 1-(2-cyanoethyl) substituted 4-nitroimidazoles and 1-(2-hydroxyethyl)-2-nitroimidazole were unsuccessful. Treatment of 1-(2-acetoxyethyl)-5-nitro-2-imidazolecar-baldehyde(10) with hydroxylamine-O-sulfonic acid afforded a mixture of corresponding 2-carbonitrile (12) and 2-(N-hydroxy)carboximidamide (13). Hydrolysis of 10 with ethanolic hydrochloric acid yielded 8-ethoxy-5,6-dihydro-3-nitro-8H-imidazo[2,1-c] [1,4]oxazine (11) which, on subsequent reaction with hydroxylamine-O-sulfonic acid, afforded 1-(2-hydroxyethyl)-5-nitroimidazole-2-(N-hydroxy)carboximidamide (15). Reaction of 4(5)-nitroimidazole with chloropropionitrile produced a mixture of the isomeric 1-(2-cyanoethyl) substituted 4- and 5-nitroimidazoles. Treatment of 2,4(5)-dinitroímidazole with chloropropionitrile afforded a mixture of 4(5)-chloro-5(4)-nitroimidazole and 1-(2-cyanoethyl)-4-nitro-5-chloroimidazoIe. Reaction of nitroimidazoles with acrylonitrile in the presence of Triton B yielded the corresponding 1-(2-cyanoethyl) substituted derivatives. 相似文献
16.
17.
18.
Raj K. Sehgal Sisir K. Sengupta R. Karl Dieter 《Journal of heterocyclic chemistry》1985,22(3):665-667
A single step synthesis of 2-deaminoactinomycin D ( 3a ) and 2-deamino-2-nitroactinomycin D ( 2a ) arising from actinomycin D ( 1a, AMD ) is reported. Structural confirmation was made by nmr, ir and chemical conversion to known materials. 相似文献
19.
We examine the effects of higher-order corrections on the universality between νμ and νe in the Weinberg-Salam model. The leading correction to neutral current amplitudes is an apparent difference in the values of sin2θ as measured by νμ and νe beams. The difference is . 相似文献
20.
Surinder K. Sehgal 《Journal of Number Theory》1974,6(2):124-127