The Sdnp, n f 3 = 1 series of barium converging ! o both !he 5d,,, and Sd,,, limits were studied in a heat-pipe system in a one-step pulsed uv laser excitation from the atomic ground state. Strong interscries and continuum interactions were observed and experimental evidence of interaction with 6p7s J = I levels was found. A comparison of the observed defect method is presented. The agreement is satisfactory in view of the complexity of the calculations. spmr?. with rPPc!ra ca!a.!atPd 8" cigc"chmne!
Copolymer hydrogels were prepared by ␥-radiation copolymerization of N-vinyl-2-pyrrolidone (NVP) and methylmethacrylate (MMA) or acrylonitrile (AN). The effect of NVP/MMA and NVP/AN compositions and irradiation dose on the gel fraction yield in the prepared hydrogels was determined. It was found that as the content of NVP increased, the gel fraction yield decreased. The increase in irradiation dose resulted in increasing the crosslinked network structure and, consequently, the gel percentage increased. The thermal stability and swelling properties were also investigated as a function of comonomer composition. The nitrile groups (-CN) in the prepared copolymer were converted into their respective amidoxime groups by treating with NH 2 OH-hydrochloride. Such a process resulted in improving both the swelling behavior and adsorption capacity. Characterization and some selected properties of the prepared hydrogels were studied and accordingly the possibility of its practicable use in the treatment of industrial waste dyes was determined. The thermodynamic parameters for the adsorption process were calculated. The effect of treatment time, pH of feed solution, effect of initial feed concentration, and temperature on the dye uptake was also investigated. The maximum uptake for investigated dyes was higher for treated NVP/AN hydrogel than that for untreated NVP/AN and NVP/MMA ones.
This paper reports on a structural phase transition in sodium hydrogen carbonate, NaHCO, as revealed by the investigations of some electrical and thermal parameters.Measurements of d.c. electric conductivity (a) and relative premittivity ( E ) of polycrystalline samples of NaHCO, as a function of temperature in the interval 300 c T < 400K reveal the existence of a structural phase transition around 365 K.Differential thermal analysis (DTA) and thermogravimetric analysis (TGA) were also performed in the same temperature range. The (DTA) results confirm the existence of a structural phase transition at r 3 6 5 K whereas the (TGA) results show the absence of any actual loss in weight in the transition temperature region.The data are correlated to the crystal structure including the hydrogen bonding system.
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