The synthesis and characterization of two new ruthenium diporphyrazines is reported. The ruthenium (III) chloride in cyclotetramerization reaction with 5,6-diphenylpyrazine-2,3- dicarbonitrile or 1,2-dicyanobenzene resulted the green and blue diporphyrazinato counterparts respectively. The obtained diporphyrazines will to our knowledge be useful photosensitizers.
Zirconia stabilized by addition of bismuth oxide was prepared by co precipitation process from metal oxide chlorides using sodium hydroxide. The dried gels produced pure phase ZrO2-Bi2O3 powders on calcination at 800ºC for the co precipitated powders. The phase evolution was studied and it was found that the delay in obtaining isomorphous ZrO2-Bi2O3 in the co precipitated powders owed to the crystallization of an impure phase BiOCl. This phase was detected in all the calcined co precipitated powders. However, the existence of ZrO2 as a separate phase was noticed as a common feature. The characterization and structural evaluation of the synthesized powder were carried out by means of Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA), X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Energy dispersive X- ray Spectroscopy (EDS). Thermal analysis revealed that weight loss arising from evaporation of bound water occurred below 150ºC for all the samples and the sintering temperature was 700ºC. The phase transformation from amorphous ZrO2 to crystalline ZrO2 occurred above 600ºC while that from amorphous Bi2O3 to crystalline Bi2O3 occurred above 700ºC. The crystallite sizes of the synthesized powders were in the range of 8-33nm. SEM micrographs showed a uniform morphology for the calcined powders and revealed nearly spherical powder particles with sizes in the range of 63-101µm. EDS confirmed Zirconia as the major component in all calcined co precipitated powder sample except the sample containing 75.53% Bi.
The compound semiconductors of zinc-blende structures (ZBS) are the promising materials for numerous experimental and theoretical investigations. These investigations are the consequences of efforts devoted to understand the interesting crystal properties and interaction mechanism exhibited by these compounds. In this paper we have developed our computed phonon dispersion curve for GaAs along three symmetry directions [q, 0, 0]; [q, q, 0] and [q, q, q] in K-space have been found to be in excellent agreement with the measured inelastic neutron scattering data. We also report Debye temperature variation, two-phonon IR/Raman spectra and anharmonic elastic properties. It is concluded that VTSM is adequately capable of describing the complete crystal dynamic study of zinc-blende structure crystals satisfying well.
Aims: 222Rn, a radioactive inert gas is a large component of the natural radiation that humans are exposed to, can pose a threat to the public health when it accumulates in poorly ventilated residential and occupational settings. About half of the total radiation effective dose to the general public is due to the irradiation of the lungs by alpha particles following the inhalation of 222Rn decay products. In this outlook, a comprehensive estimate of the natural inhalation dose requires both 222Rn and 220Rn levels in the indoor atmosphere. Place and Duration of Study: Quite a large number of measurements have been carried out during the period 2007 to 2011. About 300 dwellings of different types of construction in ten different locations of Bangalore city, India were chosen on the basis of construction, age of the building, nature of walls, floorings, rooms and different volume of dwellings for the present study to see the effective dose rates due to indoor 222Rn, 220Rn and their progeny levels during different seasons of the year. Methodology: The concentration of gamma active radio nuclides viz., 226Ra, 232Th and 40K in soil samples were determined by gamma spectrometry method by employing an HPGe spectrometer. The activity of radon in water samples were determined using emanometry method. The emanometry setup is calibrated at BARC, Mumbai. Solid State Nuclear Track Detector based dosimeters were used for the measurement of 222Rn and 220Rn and this is a good technique to study the long-term measurements. Results: The estimated concentration of 222Rn and 220Rn for the environment of Bangalore, India varied from 17.2 ± 1.2 to 85.8 ± 2.3 Bqm–3 and 8.3 ± 1.2 to 38.3 ± 5.4 Bqm-3 with a mean of 32.2 ± 1.6 and 21.4 ± 1.0 Bqm-3, respectively. It is alarming that the dwellers of lower volume and granite floorings receive relatively a higher dose rate and the result shows significant radiological risk. Volumetric variations of indoor 222Rn, 220Rn and their progeny levels reveals higher concentrations in lower volume room compared to higher volume room at all the monitored locations. Conclusion: The investigation shows no significant radiological risks for the inhabitants and is well within the limits prescribed by UNSCEAR. Further, it is recommended that the lower volume houses should have good ventilation and the dwellings should be granite free flooring, to reduce the effective dose rate. More detailed studies on the evaluation of public exposure from the natural radiation; particularly the exposure from 220Rn and their progeny should be planned and performed in this region and in the country.