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121.
Semi theoretical models have been proposed to account for the mechanism of membrane oscillations involving, electrokinetic phenomena in systems where (i) concentration difference deltaC is finite and deltaP is varying but the current is fixed, and (ii) deltaC=0, pressure difference deltaP is fixed across the membrane and imposed current is fixed. The formalism leads to the van der Pol equation in both cases. Computer simulation has also been attempted, which indicates oscillations in the former case. 相似文献
122.
A model iodophenyl imidazole ribonucleoside has been synthesized to study biodistribution properties in laboratory animals. The key intermediate 5-amino-1-(2,3,5-tri-O-acetyl-β-D-ribofuranosyl)imidazole-4-[N-(p-iodophenyl)carboxamide] ( 5 ) was synthesized by coupling N-succinimidyl-5-amino-1-(2,3,5-tri-O-acetyl-β-D-ribofuranosyl)imidazole-4-carboxylate ( 4 ) and p-iodoaniline. Deacetylation of the intermediate compound gave 5-amino-1-β-D-ribofuranosylimidazole-4-[N-(p-iodophenyl)]carboxamide ( 6 ). Ring annulation via diazotization of 5 gave 7-(2,3,5-tri-O-acetyl-β-D-ribofuranosyl)imidazo[4,5-d]-v-triazin-[3-N-(p-iodophenyl)]-4-one ( 7 ). Subsequent deacetylation of 7 afforded 7-β-D-ribofuranosylimidazo[4,5-d]-v-triazin-[3-N-(p-iodophenyl)]-4-one ( 8 ). The radiolabeled compounds, [125I] 5 and [125I] 6 were prepared in a manner similar to the corresponding unlabeled compounds except that p-[125I]iodoaniline was used for coupling with 4 . Biodistribution studies of iodine-125-labeled 5 and 6 were performed in female Fischer rats and tumor bearing nude mice. Compound 6 showed uptake in the brain and proliferating tissues such as tumor and bone-marrow. 相似文献
123.
The authors present six general integral formulas (four definite integrals and two contour inegrals) for theH-function of several complex variables, which was introduced and studied in a series of earlier papers by H. M. Srivastava and R. Panda (cf., e.g., [25] through [29]; see also [14] through [18], [20], [24], [32], [34], [35], [37], and [38]). Each of these integral formulas involves a product of the multivariableH-function and a general class of polynomials with essentially arbitrary coefficients which were considered elsewhere by H. M. Srivastava [21]. By assigning suiatble special values to these coefficients, the main results (contained in Theorems 1, 2 and 3 below) can be reduced to integrals involving the classical orthogonal polynomials including, for example, Hermite, Jacobi [and, of course, Gegenbauer (or ultraspherical), Legendre, and Tchebycheff], and Laguerre polynomials, the Bessel polynomials considered by H. L. Krall and O. Frink [9], and such other classes of generalized hypergeometric polynomials as those studied earlier by F. Brafman [3] and by H. W. Gould and A. T. Hopper [8]. On the other hand, the multivariableH-functions occurring in each of our main results can be reduced, under various special cases, to such simpler functions as the generalized Lauricella hypergeometric functions of several complex variables [due to H. M. Srivastava and M. C. Daoust (cf. [22] and [23])] which indeed include a great many of the useful functions (or the products of several such functions) of hypergeometric type (in one and more variables) as their particular cases (see,e. g., [1], [10] and [39]). Many of the aforementioned applications of our integral formulas (contained in Theorems 1, 2 and 3 below) are considered briefly. Further usefulness of some of these consequences of Theorems 1 and 2 in terms of the classical orthogonal polynomials is illustrated by considering a simple problem involving the orthogonal expansion of the multivariableH-function in series of Jacobi polynomials. It is also shown how these general integrals are related to a number of results scattered in the literature. 0261 0262 V 相似文献
124.
IR relative integrated intensities and half-widths of rocking (R) and wagging (W) bands of water in MnCl2 · 2H2O and CoCl2 · 2H2O are presented at 300 K and 120 K. Departure of observed intensity into DW/DR from those predicted by the fixed dipole model is attributed to anisotropic dynamic changes in dipole during these oscillations. A quantity representing the variation of this anisotropy between W and R oscillations is computed and its origin is discussed. An increase by 20% to 50% in both DW and DR on lowering the temperature has also been discussed. 相似文献
125.
P. Richards T. Prach S. C. Srivastava G. E. Meinken 《Journal of Radioanalytical and Nuclear Chemistry》1981,65(1-2):47-50
Preliminary results are described of a123Xe filled device to serve as a combination123I generator/iodination kit.123X was produced in the Brookhaven Linac Isotope Producer (BLIP) by the reaction127I(p, 5n)123Xe. The device consists of a small glass ampoule containing an internal glass breakseal and a flanged neck on which was crimped
a multi-injection type septum. The ampoule contained a hydrogen sulfide atmosphere to assure that the iodine generated from
the decay of the xenon was in the form of iodide. Following an adequate period for123Xe to decay (this period can be used for shipment), a needle is forced through the septum breaking the seal and residual gases
are pumped off. The123I in the form of iodide can then be rinsed from the ampoule with any desired solvent or reagent added directly to the device
to carry out an iodination in an enclosed environment. Preliminary results of both iodine recovery and iodinations have been
promising.
This research was supported by the US Department of Energy under Contract No. DE-ACO2-76CH0016. 相似文献
126.
S. P. Agrawal R. C. Aggrawal T. N. Srivastava 《Fresenius' Journal of Analytical Chemistry》1959,171(2):91-95
Summary p-Cresotic acid and its nitro, bromo, sulfo, acetyl, benzoyl and hydrazine derivatives and 5-methyl salicylic-o-aeetic acid have been used for the estimation of thorium and zirconium. The precipitates obtained have in all cases been ignited and weighed as oxides. These reagents have been found under suitable experimental conditions to effect the separation of Th as well as Zr from cerite earths. 相似文献
127.
A solid state copper(II) ion sensor is reported based on the application of electropolymerized undoped (neutral) polycarbazole
(PCz) and polyindole (PIn) modified electrodes. The new sensor shows high selectivity to Cu2+ ions with a detection limit of 10–5 M. PCz and PIn are formed respectively by the anodic oxidation of 50 mM carbazole and 5 mM indole monomers in dichloromethane
containing 0.1 M tetrabutylammonium perchlorate on a platinum electrode using a single compartment cell. Potentiostatic polymerization
of both the monomers are carried out at 1.3 V and 1.0 V vs. Ag/AgCl, respectively. Perchlorate ions were electrochemically
removed from the polymer films by applying – 0.2 V vs. Ag/AgCl. Polymer-coated electrodes are incubated in 1 M KCl solution
for 8 h followed by incubation in distilled water for 2 h before using as a metal ion sensor. The undoped PCz and PIn electrodes
were found to be highly selective and sensitive for Cu2+ ions with little selectivity for Pb2+ and negligible response towards Ag+, Hg2+, Cu+, Ni2+, Co2+, Fe2+, Fe3+ or Zn2+. Potentiometric responses for Cu2+ ions are recorded for both the sensor electrodes together with a double-junction Ag/AgCl reference electrode. Calibration
curves for Cu2+ are reported for both ion sensors. The polymer-modified electrodes were found to be stable for several weeks.
Electronic Publication 相似文献
128.
Summary First and second order resistance coefficients between membrane matrix and permeant for the permeation of methanol, acetone and methyl ethyl ketone through pyrex and quartz membranes have been evaluated from the experimental data on electroosmotic effects. Analysis of the data shows that-the following non-linear relationP =R
11
J
v
+R
12
I +R
122
I
2[1] exists between pressure difference,P, and the fluxes and a linear relation =R
21
J
v
+R
22
I [2] expresses the dependence of potential difference,, on the fluxes. The first order cross resistance coefficients have been found to obey theOnsager's reciprocity relation. An attempt has been made to explain the occurrence of higher order resistance coefficients in terms of electrokinetic character of the membrane, permeant interface.
With 2 figures and 2 tables 相似文献
Zusammenfassung Die Widerstandskoeffizienten 1. und 2. Ordnung zwischen einer Membranmatrix und dem permeierenden Stoff wurden für die Permeation von Methanol, Aceton und Methyläthylketon durch Pyrex- und Quarz-Membranen auf Grund elektroosmotischer Effekte bestimmt. Die Auswertung gibt die nichtlineare BeziehungP =R 11 J v +R 12 I +R 122 I 2 [1] zwischen der Druckdifferenz und dem Fließen; die lineare Beziehung =R 21 J v +R 22 I [2] beschreibt die Abhängigkeit der Potentialdifferenz vom Fließen. Die gekreuzten Widerstandskoeffizienten 1. Ordnung gehorchen dem ReziprozitätsgesetzOnsager. Das Vorkommen von Widerstandskoeffizienten höherer Ordnung wird versuchsweise auf den elektrokinetischen Charakter der Membran-Grenzfläche zurückgeführt.
With 2 figures and 2 tables 相似文献
129.
The reaction of SiBr4(g) with H2(g) in the temperature range 900–1143 K has been studied by a mass spectrometric method. Second and third law reaction enthalpies were obtained for SiBr4(g) + H2(g) = SiHBr3(g) + HBr(g), SiHBr3(g) + H2(g) = SiH2Br2(g) + HBr(g), and SiH2Br2(g) + H2(g) = SiH3Br(g) + HBr(g). From the heats of reaction, third-law ΔH£298 values of ?72.5 ± 1, ?43.2 ± 1.5 and ?15.3 ± 0.5 kcal/mole were obtained for SiHBr3(g), SiH2Br2(g), and SiH3Br(g), respectively. 相似文献
130.
K. C. Srivastava 《中国化学会会志》1974,21(3):163-166
A new, sensitive spectrophotometric method for the determination of palladium(II) with methylthymol blue has been developed. The palladium methylthymol blue complex has an absorption maximum at 530 nm. The colour reaction has a sensitivity of 0.005 µg of palladium/cm2 and obeys Beer's Law over the range 0.4 to 3.24 ppm of palladium. The effects of concentration of perchloric acid, reagent, heating, stability of colour and diverse ions have been investigated. The ratio of metal: ligand in the complex is 1:1 and the formation constant was calculated to be 1.18×104. 相似文献