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71.
A comparative study of the polymorphic transformations in ammonium and the alkali metal perchlorates has been made using differential thermal analysis. Certain correlations have been attempted between the observed trends in the transformation temperatures and available crystallographic and thermodynamic data. The transformation in the case of sodium perchlorate shows pronounced second-order effects. Considerable hysteresis is observed in the transformations in ammonium, potassium, rubidium and caesium perchlorates. Doping of ammonium perchlorate with ammonium phosphate is seen to result in an upward shift in the transformation temperature and an increase in the thermal hysteresis. Prior mechanical and thermal treatment is also seen to result in a broadening of the hysteresis loops in the case of ammonium and potassium perchlorates. The results are explained in terms of contrapolarization effects and the production of strain in the material as a result of prior treatment. 相似文献
72.
Norma R. de Tacconi Krishnan Rajeshwar Reynaldo O. Lezna 《Journal of Electroanalytical Chemistry》2001,500(1-2)
The voltammetric and electrochromic behavior of two types of indium(III) hexacyanoferrate(II/III) (InHCF) films, potentiodynamically grown either on polycrystalline Au or on tin-doped indium oxide (ITO) support electrodes, are described. A new spectral feature was seen at ca. 475 nm for the InHCF films grown on Au under extended potential window (EPW) conditions, in addition to the dominant 420 nm feature described by previous authors. The 420 nm band is the sole electrochromic feature in films grown under restricted potential window (RPW) conditions. The InHCF films were also grown in the presence of TiO2 particles in the deposition bath. The resultant InHCF–TiO2 composite films showed distinctly different photoelectrochemical responses for the EPW and the RPW counterparts. X-ray phoelectron spectroscopy data showed a higher TiO2 particle uptake for the EPW films relative to their RPW counterparts, under otherwise identical growth conditions. A second film configuration built up by InHCF derivatization of a pre-formed In–TiO2 film, yielded decidedly inferior photoresponses. Mechanistic reasons for this are presented as is evidence for the dominance of two distinct forms of InHCF under the EPW growth conditions. 相似文献
73.
74.
Photobiology and Ecophysiology of Rice Field Cyanobacteria 总被引:4,自引:0,他引:4
75.
R. Nottenburg K. Rajeshwar V. Pai Verneker J. Dubow 《Journal of Physics and Chemistry of Solids》1980,41(3):271-277
A.C. electrical conductivity of pottasium perchlorate (KP) has been measured in the temperature range 25–325°C at frequencies ranging from 50–500 Hz using an automated technique. Three regions with activation energies. 1.08 ± 0.02, 0.66 ± 0.01 and 0.39 ± 0.04eV are observed in ln(σT) vs 1/T plots at frequencies < - 50 Hz. Dielectric loss measurements on KP samples doped with CrO42? and SO42? ions show the presence of impurity-vacancy complexes with reorientation energies of 0.99 ±0.02 and 1.07 ± 0.01 eV respectively. The results are interpreted in terms of a defect model which highlights the role of various conduction and relaxation mechanisms in the a.c. electrical properties of the material. 相似文献
76.
Mathiazhakan Kuttiraja Ayed Dhouha Rajeshwar Dayal Tyagi 《Applied biochemistry and biotechnology》2018,184(4):1332-1346
The objective of this research was to investigate the kinetics of lipid production by Yarrowia lipolytica SKY7 in the crude glycerol-supplemented media with and without the control of pH. Lipid and citric acid production were improved with the pH control condition. There was no significant difference observed in the biomass concentration with or without the pH control. In the pH-controlled experiments, the biomass and lipid concentration reached 18 and 7.78 g/L, (45.5% w/w), respectively, with lipid yield (Yp/s) of 0.179 g/g at 60 h of fermentation. The lipid production was directly correlated with growth and the process was defined as growth associated. After 60 h of fermentation, the lipid degradation was noticed in the pH-controlled reactor whereas it occurred after 84 h in the pH-uncontrolled reactor. Apart from lipid, citric acid was produced as the major extracellular product in both fermentations but the much lower concentration in uncontrolled pH. Based on the experimental results, it is evident that controlling the pH will enhance the lipid production by 15% compared to pH-uncontrolled fermentation. 相似文献
77.
Rajeshwar Reddy Sagyam Pratap Reddy Padi Mahesh Reddy Ghanta Himabindu Vurimidi 《Journal of heterocyclic chemistry》2007,44(4):923-926
78.
G. Rajeshwar Reddy T. Ram Reddy R. Gangadhara Chary Suju C. Joseph Soumita Mukherjee Manojit Pal 《Tetrahedron letters》2013
We report a faster and greener approach for the synthesis of dihydroisoindolo[2,1-a]quinazoline-5,11-dione derivatives of potential pharmacological interest via a β-CD mediated MCR in water under microwave irradiation. 相似文献
79.
G. Krishnaiah B. Sandeep D. Kondhare K.C. Rajanna J. Narendar Reddy Y. Rajeshwar Rao P.K. Zhubaidha 《Tetrahedron letters》2013,54(7):703-706
Transesterification of β-ketoesters with various alcohols has been studied under conventional and non-conventional conditions using desktop chemicals such as Mn(II) salts as catalysts. These methods offered transesterification of β-ketoesters in good yields with dramatic rate accelerations and reduced reaction times. The developed protocols under nonconventional methods such as sonication and microwave irradiation are highly promising compared with the existing procedures. 相似文献
80.