Laser-assisted decontamination—A wavelength dependent study

We present here the experimental results on cleaning of radioactive dielectric particulates, loosely deposited on stainless steel, by coherent light of 1064 nm wavelength and its three harmonics occurring at 532 nm, 355 nm and 266 nm, derived from an Nd-YAG laser. For the initial few exposures, the decontamination factor has been found to be highest when exposed to 1064 nm radiation. With increasing number of exposures, however, the radiation with reducing wavelength assumes a more important role as a cleaning agent. The observation of almost no cleaning with 1064 nm and much reduced cleaning with its harmonics when the contamination is deposited on a transparent substrate confirms the dominant role played by metal substrate towards expelling the loose particulates from its surface.     

Enhanced sensitivity for the differential pulse polarographic determination of Mo(VI) based on adsorption catalytic current

A differential pulse polarographic (DPP) method based on the adsorption catalytic current in a medium containing chlorate and 8-hydroxyquinoline (oxine) is suggested for the determination of molybdenum(VI). Experimental conditions such as pH and the composition of supporting electrolyte have been optimized to get a linear calibration graph at trace levels of Mo(VI). The sensitivity for molybdenum can be considerably enhanced by this method. The influence of possible interferences on the catalytic current has been investigated. The sensitivity of the method is compared with those obtained for other DPP methods for molybdenum. A detection limit of 1.0 × 10^–8 mol/L has been found.     

Vinyl Polymerisation

The ternary system Poly (methyl methacrylate) Fraction 1/Fraction 2/n-butyl bromide has been studied. A viscometric method is proposed for the estimation of the individual polymer concentration in the two conjugate phases in equilibrium.     

Synthesis and characterization of poly benzoylpropionamides

Linear polyamides having viscosities in the range of 0.12–0.41 dl/g have been prepared from bisbenzoyl propionic acids and aromatic diamines by low temperature solution polycondensation in 80–85% yield. Their solubility characteristics were studied in various solvents e.g. DMF, DMAC, HMPT, H₂SO₄. These polyamides are amorphous in nature; their densities range from 1.2 to 1.8 g/cm³. Their thermal properties were examined by TGA and DTA. The two stage decomposition phenomenon observed in TGA is in agreement with the DTA results. The integral procedural decomposition temperatures were calculated and found to exceed 250 in almost all cases.     

Partial molar volumes of monovalent ions in ethanolamine and water + ethanolamine mixtures at 25°C

Precise densities for sodium of chloride, bromide and iodide and potassium iodide in ethanolamine and water+ethanolamine mixtures (15, 30, 50, 60, 70, 80 and 90 mass% ethanolamine) up to a maximum salt molality of 0.15 mol-kg⁻¹ are reported from measurements at 25°C using a vibrating tube densimeter. The electrolyte apparent molar volumes were calculated and extrapolated to infinite dilution using the Masson equation to yield the limiting electrolyte partial molar volumes. The limiting ionic partial molar volumes V _ion ^o were estimated using Mukerjee's method. A correspondence principle proposed earlier for predicting ionic entropies could be used for the estimation of V _ion ^o for rubidium and cesium salts. The estimates of the contributions from geometric and the electrostrictive effects to V _ion ^o are also reported. The variations in these contributions with the change in solvent composition are discussed in terms of the changes in the solvent structure.     

Photopolymerization initiated by charge–transfer complex. X. Photopolymerization of methyl methacrylate with the use of isoquinoline–sulphur dioxide charge–transfer complex

Aqueous polymerization of methyl methacrylate in visible light was studied using isoquinoline–sulphur dioxide (IQ–SO₂) charge–transfer complex as the photoinitiator. Analysis of kinetic and other data indicate that the polymerization proceed via a radical mechanism and the termination is dependent on the initiator concentration. Chain–termination via degradative chain (initiator) transfer appears to be predominant here.     

Halogen exchange reactions of silicon tetrafluoride with phosphorus trichloride and phosphoryl chloride

Silicon tetrafluoride undergoes halogen exchange reactions with both phosphorus trichloride and phosphoryl chloride at temperatures of 500–600°C yielding mixed chlorofluorides of silicon and phosphorus. It is interesting to note that, at these high temperatures, PCl₃ undergoes complete exchange to form PF₃ while POCl₃ reacts only with partial substitution, the major products being phosphorus chloride difluoride and silicon trichloride fluoride.     

A New Method for the Preparation of Sulphuryl Chloro Fluoride

It has been observed that a suspension of sodium fluoride in boiling acetonitrile could be used for the preparation of fluorine compounds such as silicon tetrafluoride [1], thiophosphoryl fluoride [2], sulphur tetrafluoride [3,4], and fluorocyclophosphazenes [5]. This method, when adopted for the fluorination of sulphuryl chloride [6], it is observed that a mixture of sulphuryl fluoride and sulphuryl chloro fluoride is obtained. On the other hand, when lead fluoride is substituted for sodium fluoride, pure sulphuryl chloro fluoride is evolved. Based on this observation, a new method has been standardised for the preparation of a pure sample of sulphuryl chlorofluoride by fluorinating sulphuryl chloride by lead fluoride in acetonitrile medium.     

Studies on conformation—I Preparation and stereochemistry of some 4-piperidinols

The reduction of a number of 4-piperidones by different methods afforded epimeric pairs of 4-piperidinols. Methods of formation, isomerization studies and the degree of adsorption on alumina indicate their conformation. The stereochemical course of the reductions is discussed.