A simple and sensitive analytical method for the determination of antimony in environmental and biological samples.

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.     

Analysis of anions by solid-state spot-tests

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.     

Fine-hyperfine structures ofc\bar c andb\bar b systems in a non-relativistic Hulthen plus linear potentialsystems in a non-relativistic Hulthen plus linear potential

The heavy mesons of the charmonium and upsilon family are described in an alternative static potential model chosen in a combination of Hulthen and linear potential. We find that the quark-confining potential in the form of an equal admixture of vector and scalar parts successfully explains the fine-hyperfine structures of \(c\bar c\) and \(b\bar b\) systems in a flavour-independent manner. The leptonic decay widths of the vector mesons ofψ and γ families are calculated taking into account the Poggio-Schnitzer correction. We obtain some of the bound states of the yet-to-be observed \(t\bar t\) system for thet-quark mass ranging from 50 to 200 GeV.     

Aqueous polymerization of methacrylamide

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.     

Thermal analysis of polysiloxanes, aromatic polyimide and their blends

Low molecular weight poly(dimethylsiloxane) and poly(methylphenylsiloxane) were synthesized and blended with polyimide (PI) at its precursor poly(amic acid) stage. FTIR analysis has proven the retention of polysiloxanes in polyimide after the ultimate curing of blends. Differential scanning calorimetric analysis was performed on polysiloxanes to elucidate the structures present in polymers while thermogravimetric analysis (TGA) was performed on polysiloxanes, polyimide as well as their blends to evaluate the thermal stability and to analyze the effect of polysiloxane incorporation in blends. Blends have shown synergistic improvement as compared to neat polyimide.     

Spectrophotometric determination of thiourea in microgram quantities

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%.

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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.

     

One-Pot Convenient and High Yielding Synthesis of Dithiocarbamates

Summary. A convenient and high yielding method for the synthesis of diverse dithiocarbamates having various substituents including alkyl, aryl, heteroaryl, and alkylaryl at the thiol chain or at the amine chain or at both thiol and amine chains were developed by the one-pot reaction of mercaptans, amines, and bis(benzotriazolyl)methanethione in presence of amidine base under mild reaction conditions.     

Dispersion characteristics of broadside coupled dielectric image guide at millimeter wave frequencies

Dispersion characteristics and wave impedance for the even and odd modes of the broad side coupled dielectric image guides are computed by using mode matching techniques. Dispersion curves for broadside image guide are plotted for various dielectric materials and dimensional parameters as a function of frequency. Normalized electric field for dominant electric field component E of TM even and odd modes for various half spacings between two dielectric slabs of broadside coupled image guide have been plotted. Polysterene ( r=2.56) and Stycast ( r=3.4) have been used as dielectric materials in fabricating broadside coupled image guide. This broadside coupled dielectric guide is very convenient as compared to the other dielectric guides. Since in case of broadside coupled image guide the dielectric slab can be bonded to the side metallic walls using some low loss adhesive material, while in other coupled dielectric guides the dielectric slab have to be supported by some low dielectric constant material (Eccofoam with r=1.02) to maintain the proper distance of side metallic walls from the dielectric slab. Since this structure is symmetrical, this configuration can be analysed in terms of even and odd mode phase velocities. The difference in these even and off mode phase velocities can be used to determine the coupling between coupled dielectric slab. Various couplers in this configuration can be realised.     

Volumetric studies and thermodynamics of viscous flow of hydroxamic acids in acetone + water solvent at temperatures 303.15 and 313.15 K

Densities ρ and viscosities η of two hydroxamic acids, N-phenyl-2-chlorobenzo- and N-o-tolyl-4-chlorobenzo-, have been determined as a function of their concentration in aqueous acetone solution at temperatures 303.15 and 313.15 K. Apparent molar volumes, standard-state partial molar volumes and relative viscosities have been calculated. The viscosity data have been analyzed using Jones-Dole equation. The activation thermodynamic parameters of viscous flow have been evaluated using Feakins equation. These were obtained to throw light on the mechanism of viscous flow. Thermodynamic interactions in solutions have been studied in terms of a number of excess functions calculated from the experimental data. The effect of hydroxamic acid concentration and temperature on these parameters has been discussed. The results were interpreted in the light of solute-solvent interactions in aquo-organic media.     

Kinetics and mechanism of oxidation of cyclopentanone by N-bromosuccinimide

N-bromosuccinimide oxidation of cyclopentanone in acidic media in presence of mercuric acetate has been made. A zero order dependance to N-bromosuccinimide and a first order dependence to cyclopentanone and hydrogen ion concentration has been observed. Ionic strength, mercuric acetate and succinimide has negligible effect while methanol addition has a positive effect. Various rate parameters have been computed and 1,2-cyclopentanedione identified as the end product. A suitable mechanism in confirmity with the above observations has been proposed.With 2 Figures