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2.
Rajeev K. Thakur C. Villette J.M. Aubry G. Delaplace 《Colloids and surfaces. A, Physicochemical and engineering aspects》2007,310(1-3):55-61
Formulation–composition map is an interesting tool to predict the nature of an emulsion, stability, viscosity and nevertheless to decide the mixing protocol of its ingredients. Information based on optimum formulation (environmental conditions at which the affinity of an emulsifier for oil and for aqueous phase is same), which is depicted through hydrophilic–lipophilic deviation (HLD) concept, is necessary to make a formulation–composition map of an emulsion. In order to apply this concept in food emulsions, it is necessary to determine characteristic constants of each component of the system, i.e. the aqueous phase, the oil phase and the emulsifier at equilibrium. In this work formulation–composition map of a sunflower oil–water–lecithin system, based on the knowledge of phase behavior of lecithin at equilibrium and emulsification, was made. The shape of inversion line on formulation–composition map was not the classical stair type rather an almost vertical inversion line at water-fraction (fw) near 0.20 was observed. It was supposed to be linked to the viscosity of oil phase which was 50 times the viscosity of aqueous phase. Additionally, emulsions were of oil-in-water (O/W) type for fw higher than 0.20, but their viscosity and the drop size behavior with respect to salt concentration as formulation variable did not show the existence of transitional inversion line on formulation–composition map. Such map in advance can certainly facilitate the guidelines for dynamic emulsification. 相似文献
3.
A. N. Thakur 《Journal of Radioanalytical and Nuclear Chemistry》1997,215(2):161-167
Neutron induced -ray spectra from various geological samples were analyzed to evaluate the usefulness of continuum spectra in deriving the chemical composition information. A fast Fourier transform technique has been used to estimate the signal content of selected energy bands of the continuum spectra. Monte Carlo calculations have been performed using the major -ray energy sources (due to Fe, Ca, Si and Al) to generate the corresponding detected -ray spectra. The experimental spectra are compared to the simulated spectra to check the consistency of the signal distribution between the peak and the continuum. The continuum above and below a chosen -ray line is calculated to find what fraction of the lower energy continuum is due to that line. The accuracy of the relative elemental concentrations determined by this method is confirmed through comparison with laboratory elemental analysis of the samples. It is found that using the continuum could greatly increase the sensitivity and precision of the measurement of elemental concentrations determined from -ray spectra of thick target sources, for spectra having peaks of poor statistical significance. However, for thin target sources or spectra with very good statistics in their peaks, this method may not be very advantageous. 相似文献
4.
The extraction behaviour of thorium(IV) from aqueous nitric acid employing 3-phenyl-4-benzoyl-5-isoxazolone (HPBI) in the presence of tri-n-octyl phosphine oxide (TOPO) as well as tri-n-butyl phosphate (TBP) in xylene medium was investigated. The extraction constant (log k(ex)) for the binary organic phase species Th(PBI)(4) was determined to be 8.26 which is by far the largest amongst the corresponding values known for other beta-diketones. The overall extraction constant (log K) for the ternary species Th(PBI)(4) TBP and Th(PBI)(4).2TOPO were estimated to be 14.96 and 20.96 respectively. An inverse correlation of the adduct formation constant (log K(s)) with the pK(a) of the beta-diketones, 2-thenoyltrifluoroacetone, 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone and HPBI, was observed. The steric as well as the electronic effects of adduct formation have been discussed. Analytical application of HPBI for the separation of (234)Th radiotracer from natural uranium (99.3% (238)U) has been suggested. 相似文献
5.
Das DD Mahapatra R Pradhan J Das SN Thakur RS 《Journal of colloid and interface science》2000,232(2):235-240
Removal of hexavalent chromium from aqueous medium by using activated cow dung carbon was studied. Cow dung was carbonized and activated by treating with concentrated H(2)SO(4) followed by heating for 24 h at 120 degrees C. The extent of adsorption was studied as a function of pH, contact time, amount of adsorbent, concentration of adsorbate, and temperature. At lower pH (<3.5), the prepared sorbent was capable of removing approximately 90% Cr(VI) at 5 ppm concentration from aqueous synthetic solution. The dynamics of migration of the sorbate ions from the bulk onto the sorbent surface was studied and the results obtained under various experimental conditions were found to follow standard adsorption isotherms. The reaction kinetics was found to be of first order. Copyright 2000 Academic Press. 相似文献
6.
C.S. Hoad R.W. Matthews M.M. Thakur D.G. Gillies 《Journal of organometallic chemistry》1977,124(3):c31-c36
Thallium-205, carbon-13 and proton NMR spectra have been determined for some monomethylthallium(III) derivatives CH3TlX2 (X anion) permitting comparison of NMR parameters in the series CH3TlX2, (CH3)2TlX, (CH3)3Tl. 相似文献
7.
Colorimetric method for the determination of captafol (difolatan) in commercial formulations and residues on grains and apples. 总被引:1,自引:0,他引:1
A simple and rapid colorimetric method for the microdetermination of captafol (difolatan), based on its reaction with a dithiocarbamate, has been developed. The bright yellow colour which develops instantaneously on mixing the fungicide with the reagent is stable for at least 12 h. The method has been successfully adapted to the determination of captafol in its formulated products and residues on grains and apples. 相似文献
8.
N-Methylaminothioformyl-N'-phenylhydroxylamine forms a 1:2 (metal:ligand) greenish yellow complex with cobalt(II). This complex has maximum absorption at 470 nm with a molar absorptivity of 1.65 x 10(4) 1.mole(-1).cm(-1). Beer's law is obeyed over the concentration range 6 x 10(-6)-6 x 10(-5)M. The effect of diverse ions is described. 相似文献
9.
Spectrophotometric Determination of Rhenium(IV) with Thiocyanate,TX-100 and N,N′-Diphenylbenzamidine
A spectrophotometric method to determine rhenium(IV) at trace level is based on the extraction of Re(IV)-SCN? complex in sulphuric acid media with N,N′-diphenylbenzamidine(DPBA) in presence of a non-ionic surfactant triton X-100 (TX-100) in chloroform. The complex shows maximum absorbance at 435 nm with amolar absorptivity value of 4.24 × 104 L mol?1 cm?1 at an acidity range 3.5-6.5 M H2SO4. The method followed Beer's Law for the system Re(IV)-SCN?(TX-100)-DPBA upto 4.0 μg Re(IV) mL?1. The detection limit of the method is 5 ppb. None of the tested foreign ions, except molybdenum(VI), interfere with the determination of rhenium. The interference due to molybdenum could effectively be removed by prior precipitation with oxine. The effect of various analytical parameters on the extraction of the metal are discussed. 相似文献
10.
A simple and sensitive field detection and spectrophotometric method for determination of copper described herewith is based on the formation of a red coloured species of copper(II) with 1-[pyridyl-(2)-azo]-naphthol-(2) (PAN), TX-100 and N,N'-diphenylbenzamidine (DPBA) at pH range 7.8-9.4. The red coloured Cu(II)-PAN-(TX-100)-DPBA complex in chloroform shows maximum absorbance at 520 nm with molar absorptivity value of 1.14x10(5) l mol(-1) cm(-1). The detection limit of the method is 2 ng ml(-1) organic phase. The system obeys Beer's law up to 0.6 mug Cu(II) ml(-1) in organic solution. Most of the common metal ions generally found associated with copper do not interfere. The repeatability of the method was checked by finding relative standard deviation (RSD) (n=10) value for solutions each containing 0.2 mug ml(-1) of Cu(II) and the RSD value of the method was found to be 1.5%. The validity of the method has been satisfactorily examined for the determination of copper in soil and airborne dust particulate samples. 相似文献