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441.
Tehseen Aman Shamma Firdous Islam Ullah Khan Asrar Ahmad Kazi 《Mikrochimica acta》2001,137(3-4):121-126
Phenytoin sodium reacts with o-nitrobenzoic acid in alkaline media after heating for 10 minutes at 70 °C, to give a red coloured
complex having maximum absorbance at 510 nm. The reaction is selective for phenytoin sodium with 0.01 mg/10 mL as visual limit
of quantitation and provides a basis for a new spectrophotometric determination. The colour reaction obeys Beer’s law from
0.01 mg to 3 mg/10 mL of phenytoin sodium and the relative standard deviation is 0.29%. The quantitative assessment of tolerable
amounts of other drugs is also studied.
Received May 2, 2000. Revision May 11, 2001. 相似文献
442.
Brian Herman Pawel Wodnicki Seongwook Kwon Ammasi Periasamy Gerald W. Gordon Nupam Mahajan Xue Feng Wang 《Journal of fluorescence》1997,7(1):85-91
Time-resolved fluorescence lifetime microscopy (TRFLM) allows the combination of the sensitivity of fluorescence lifetime
to environmental parameters to be monitored in a spatial manner in single living cells, as well as providing more accurate,
sensitive, and specific diagnosis of certain clinical diseases and chemical analyses. Here we discuss two applications of
TRFLM: (1) the use of nonratiometric probes such as Calcium Crimson, for measuring Ca2+; and (2) quantification of protein interaction in living cells using green and blue fluorescent protein (GFP and BFP, respectively)
expressing constructs in combination with fluorescence resonance energy transfer microscopy (FRET). With respect to measuring
Ca2+ in biological samples, we demonstrate thatintensity-based measurements of Ca2+ with single-wavelength Ca2+ probes such as Calcium Crimson may falsely report the actual Ca2+ concentration. This is due to effects of hydrophobicity of the local environment on the emission of Calcium Crimson as well
as interaction of Calcium Crimson with proteins, both of which are overcome by the use of TRFLM. The recent availability of
BFP (P4-3) and GFP (S65T) (which can serve as donor and acceptor, respectively) DNA sequences which can be attached to the
carboxy-or amino-terminal DNA sequence of specific proteins allows the dual expression and interaction of proteins conjugated
to BFP and GFP to be monitored in individual cells using FRET. Both of these applications of TRFLM are expected to enhance
substantially the information available regarding both the normal and the abnormal physiology of cells and tissues. 相似文献
443.
Infrared absorption spectra of N,N′-dimethyl formamide in the absence and presence of water, rhodamine 6G and water–rhodamine 6G mixture are reported. Assignment of observed bands has been made on the basis of density functional theory calculations and available assignments in the literature. Certain bands show changes in their positions and intensities when water is added to N,N′-dimethylformamide. This is due to hydrogen bonding interaction between these molecules. Similar changes are also observed for dimethylformamide and Rh6G mixture to a lesser extent. The presence of Rh6G in a dimethylformamide–water mixture reverses these spectral changes due to preferential solvation of Cl? by water molecules. Solvation reduces or nullifies the hydrogen bonding between dimethylformamide and water in the mixture. 相似文献
444.
445.
K. R. P. M. Rao Frank E. Huggins Vikram Mahajan Gerald P. Huffman V. U. S. Rao 《Hyperfine Interactions》1994,93(1):1745-1749
Mössbauer spectroscopy studies of iron catalysts from a Fischer-Tropsch (FT) Pilot Plant run at different time-on-stream periods were carried out. Magnetite Fe3O4 was found to be active for the water-gas-shift (WGS) reaction which accompanies the FT synthesis reaction over Fe-based catalysts. A correlation between the ratio of the occupancy of octahedral sites to the tetrahedral sites in magnetite to the WGS activity was found. Cation-deficient magnetite gave higher WGS activity as compared to the stoichiometric phase. 相似文献
446.
Ultrasonic attenuation has been measured in the intermediate state of high purity single crystals of indium of different sizes over the frequency range 10–30 MHz. Oscillations in the temperature dependence of attenuation of longitudinal ultrasound have been observed and are discussed here in the light of a recent theory. 相似文献
447.
448.
Mahajan MP Zhang S Tsige M Taylor PL Rosenblatt C 《Journal of colloid and interface science》1999,213(2):592-595
The paramagnetic fluid composed of manganese chloride tetrahydrate dissolved in water was used to form bridges held between two parallel collinear rods. Magnetic levitation was used to control the effective gravity felt by the bridges. Their stability was studied as a function of Bond number and volume of the supported liquid. Data are compared with theoretical predictions for liquid bridges as well as with experimental results, where available. Copyright 1999 Academic Press. 相似文献
449.
450.
G. R. Mahajan V. K. Rao P. R. Natarajan 《Journal of Radioanalytical and Nuclear Chemistry》1989,137(3):219-227
The stability constants of the complex of Pu/III/ with a humic acid at pH 2.9 and 5.0 were measured using solvent-extraction technique. The organic extractant was dinonyl naphthalene sulphonic acid in sodium form /NaD/ in benzene while the humate aqueous phase had a constant ionic strength of 0.5M /NaClO4/. The total carboxylate capacity of the humic acid was determined by direct potentiometric titration to be 6.201 Meq g–1. The apparent pKa increased as the degree of ionization // increased. The 1g 1 values of the complex of Pu/III/ with humic acid have been determined to be 2.8 and 3.11 at pH 2.9 and 5.0, respectively. 相似文献