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1.
Spectral data during a chelatometric titration were utilized for determining an equivalence point of the titration. Three-dimensional titration data were analyzed by fitting to a theoretical equation that was derived from equilibrium equations among a metal ion, an indicator and EDTA. The equation with optimized parameters successfully explained the three-dimensional titration data. This method was applied to EDTA titration systems of zinc, cadmium and lead with xylenol orange (XO) as an indicator. These systems were analyzed while taking the formation of 1:1 and 2:1 metal-indicator complexes into account. By this method, an accurate equivalence point was determined as well as stability constants and molar absorption spectra of metal-indicator complexes in each titration system. Moreover, the comparability among the concentrations of the metal standard solutions prepared from pure metals (Zn, Pb, and Cd) was also confirmed by the proposed evaluation method. 相似文献
2.
S. C. Tiwari 《Foundations of Physics Letters》2006,19(1):51-62
Advances in gauge theories and unified theories have not thrown light on the meaning of electron. The problem of the origin
of electronic charge is made precise, new insights gained from Weyl space are summarized, and the origin of charge in terms
of fractional spin is suggested. A new perspective on the abelian Chern-Simons theory is presented to explain charge. 相似文献
3.
4.
The analytical potential of water as an eluent in thin layer chromatographic separation of various anions on plain adsorbent layers (silica gel "G" alumina, and cellulose) as well as on beds containing different combinations of silica gel, alumina, or cellulose has been investigated. In addition to some important separation of anions, microgram separation of IO−4 from milligram quantities of IO−3, Bro−3, MoO2−4, and Fe (CN)3−6 has been realized. The effect on pH of the sample in the separation of IO−4 from accompanying ions has also been studied. The limits of detection and dilution limits of anions on alumina thin layers have been determined. NO−2 in artificial seawater has been detected. The effect of CaCl2, MgCl2, and NaHCO3 on some ternary separations of analytical importance has been examined. 相似文献
5.
Kishore K Tiwari Girdhar L Mundhara Manish K Rai Vinay K Gupta 《Analytical sciences》2006,22(2):259-262
The results of a study and application of leucocrystal violet for the determination of antimony in parts per million levels is described here. The proposed method is based on the reaction of antimony(III) with acidified potassium iodate to liberate iodine. The liberated iodine selectively oxidizes leucocrystal violet to crystal violet dye. The formed dye shows maximum absorbance at 590 nm. The color system obeys Beer's law in the concentration range from 0.4 - 3.6 microg antimony per 25 ml of final solution. The molar absorptivity and Sandell's sensitivity were found to be 7.32 x 10(5) l mol(-1) cm(-1) and 0.0016 microg cm(-2), respectively. All variables were studied in order to optimize the reaction. The proposed method is satisfactorily applicable for the analysis of antimony in various environmental and biological samples. The method is simple, highly sensitive, accurate and reliable. 相似文献
6.
Trituration and capillary solid-state spot-tests for 25 anions with a number of organic and inorganic reagents have been examined. A comparative study of the corresponding reactions in solution has also been made. Incorporation of a glass-wool plug in the capillary improves the selectivity. Schemes are presented for possible use of the technique. 相似文献
7.
J. S. Shukla R. K. Tiwari 《Journal of polymer science. Part A, Polymer chemistry》1981,19(6):1517-1524
The aqueous polymerization of methacrylamide (I) initiated by KBrO3–thioglycolic acid (TGA) has been studied at 30 ± 0.2°C in nitrogen. The rate is given by K[M]1.19 [thioglycolic acid]1 [KBrO3]0.53 for 10–15% conversion. Activation energy was found to be 53.96 kJ/mole (12.92 kcal/mole) in the investigated range of temperature 30–45°C. The role of addition of a series of aliphatic alcohols and some salts was also determined. The kinetics of polymerization was followed iodometrically. 相似文献
8.
Kundu S Pal A Ghosh SK Nath S Panigrahi S Praharaj S Pal T 《Inorganic chemistry》2004,43(18):5489-5491
Ligands with a beta-diketone skeleton have been employed for the first time as reductant to produce ligand stabilized gold nanoparticles of different shapes from aqueous HAuCl(4) solution. Evolution of stable gold nanoparticles follows first order (k approximately equal to 10(-2) min(-1)) kinetics with respect to Au(0) concentration. Growth of particles of different shapes (spherical or triangular or hexagonal) goes hand in hand under the influence of different beta-diketones, which have excellent capping and reducing properties. Chlorine insertion was observed to take place in the beta-diketone skeleton. 相似文献
9.
Summary Copper(II) forms a stable colourless complex with thiourea. This property has been utilized to develop a Spectrophotometric method for the determination ofg quantities of thiourea. The complex absorbs in ultraviolet region and the determinations are carried out at 250 nm. The method permits the determination of thiourea from 10–60g with error not exceeding ± 1.0%.
Zusammenfassung Kupfer(II) bildet mit Thioharnstoff eine farblosa Komplexverbindung, die sich auf Grund ihrer Absorption bei 250 nm zur spektrophotometrischen Bestimmung von Mikrogrammengen Thioharnstoff eignet. 10 bis 60g Thioharnstoff lassen sieh mit einem Fehler von höchstens ± 1,0% bestimmen.相似文献
10.
Heat transfer in unsteady MHD channel flow (of an incompressible viscous and electrically conducting fluid) under oscillatory pressure gradient when the channel surfaces are conducting and moving with time-dependent velocities has been analysed. The velocity, magnetic field and temperature distributions have been obtained and their numerical results are shown graphically.Symbols
u
velocity
-
H
o
applied magnetic field
-
H
x
induced magnetic field
-
T
temperature
-
T
1
*
,T
2
*
temperatures of the upper and lower planes
-
density
-
p
pressure
-
kinematic viscosity
-
magnetic diffusivity
-
electrical conductivity of the fluid
-
A
*
characteristic velocity
-
L
characteristic length
-
e
magnetic permeability of the fluid
-
C
p
specific heat
-
coefficient of viscosity
-
k
thermal conductivity
-
1,
2
permeabilities of the planes
-
1,
2
conductivities of the planes
-
1,
2
conductance ratios of the planes
-
Pr
Prandtl number (=C
p
/k)
-
E
Eckert number
-
M
Hartmann number (=
e
H
o
L/)
-
R
e
Reynolds number (=LA
*/)
-
R
m
magnetic Reynolds number (=
e
LA
*)
-
S
Pr.E(=S) 相似文献