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81.
R. Parthasarathy Ravi V. Prasad P. R. Sarode K. J. Rao 《Journal of Chemical Sciences》1982,91(3):201-205
The exafs of Co2+ has been studied in rare earth cobaltites and in sulphate and borate glasses. It has been found that the environment of Co2+ ions is very similar in these cases. It appears feasible to study local structures in glasses using probe ion exafs.
Communication No. 151 from the Solid State and Structural Chemistry Unit. 相似文献
82.
Summary Reactions of titanium(IV) isopropoxide with ethyl 1-hydroxycyclohexylacetate, ethyl 2-hydroxy-2-arylpropionate, ethyl 2-hydroxy-2-arylbutyrate and ethyl 2-hydroxy-2-arylhydrocinnamate have been studied in dry benzene in different molar ratios under strictly anhydrous conditions. The Ti(OPr-i)4-nLn type compounds, where L = hydroxy ester and n = 1 to 4, have been isolated and characterised by elemental analysis, molecular weight, i.r. and n.m.r. spectral studies. These products may be distilled unchanged under reduced pressure.Reprints of this are not available. 相似文献
83.
Rao CN Kundu AK Seikh MM Sudheendra L 《Dalton transactions (Cambridge, England : 2003)》2004,(19):3003-3011
Electronic phase separation is increasingly getting recognized as a phenomenon of importance in understanding the magnetic and electron transport properties of transition metal oxides. The phenomenon dominates the rare-earth manganates of the formula Ln(1-x)A(x)MnO(3)(Ln = rare earth and A = alkaline earth) which exhibit ferromagnetism and metallicity as well as charge-ordering, depending on the composition, size of A-site cations and external factors such as magnetic and electric fields. We discuss typical phase separation scenarios in the manganates, with particular reference to Pr(1-x)Ca(x)MnO(3)(x= 0.3-0.4), (La(1-x)Ln(x))(0.7)Ca(0.3)MnO(3)(Ln = Pr, Nd, Gd and Y) and Nd(0.5)Sr(0.5)MnO(3). Besides discussing the magnetic and electron transport properties, we discuss electric field effects. Rare-earth cobaltates of the type Pr(0.7)Ca(0.3)CoO(3) and Gd(0.5)Ba(0.5)CoO(3) also exhibit interesting magnetic and electron transport properties which can be understood in terms of phase separation. 相似文献
84.
P. S. Verma T. Venkateshwar Rao A. Jayaraman P. S. N. Murthy G. C. Joshi 《Fresenius' Journal of Analytical Chemistry》1994,348(11):742-744
The Fe(III)-EDTA complex reacts with sulfide ion in a fast electron transfer reaction, oxidising the latter to elemental sulfur and getting itself reduced to Fe(II). The reaction has been developed for the quantitative estimation of sulfide ion by titration against the Fe(III)-EDTA complex, measuring the redox potential of the system. Repeated use of a given quantity of the complex solution by the process of regeneration has been demonstrated. The possibility of its practical application in liquid phase oxidation processes of recovering sulfur from H2S is emphasized. 相似文献
85.
S. Prabhakara Rao M. Santappa 《Journal of polymer science. Part A, Polymer chemistry》1968,6(1):95-107
Graft polymers from poly(vinyl chloride) (PVC) and chlorinated rubber (CIR) with side chains of poly(methyl methacrylate) (PMMA), poly(methyl acrylate) (PMA), or poly(ethyl methacrylate) (PEMA) were synthesized. For this purpose, a vinyl monomer was polymerized in the presence of small quantities of PVC or CIR with benzoyl peroxide as catalyst. The graft polymers were separated from both homopolymers by precipitation with methanol from methyl ethyl ketone solutions of the reaction products and the grafting efficiency was calculated. The graft polymers were characterized by infrared spectra, elemental analysis, NMR, and osmometric or light-scattering determinations. From the results it is concluded that the PVC or CIR molecules contain side chains of PMMA, PMA, or PEMA. The graft polymers showed higher molecular weights, and the values of second virial coefficient for these polymers were much different from those of the starting polymers. 相似文献
86.
The reaction of titanium isopropoxide with a Schiff base ligand containing an isobutenyl linker leads to double stranded dinuclear titanium(IV)-Schiff base complexes through self-assembly with concomitant formation of intramolecular mu-oxo bridges upon hydrolysis. 相似文献
87.
Photoacoustic spectroscopy of solids and surfaces 总被引:1,自引:0,他引:1
After briefly reviewing the theory and instrumentation, results from a variety of experiments carried out by the authors on
the photoacoustic spectroscopy of solids and surfaces by employing an indigenous spectrometer are discussed in the light of
the recent literature. Some of the important findings discussed are, phase angle spectroscopy, anomalous behaviour of monolayers,
unusual frequency dependence in small cell volumes, spectra of a variety of solids including amorphous arsenic chalcogenides,
photoacoustic detection of phase transitions and determination of surface areas and surface acidities of oxides. Recent developments
such as piezoelectric photoacoustic spectroscopy, depth profiling and subsurface imaging are also presented.
Contribution No. 124 from the Solid State and Structural Chemistry Unit. 相似文献
88.
A sensitive and rapid method for the determination of trace levels of titanium in polyolefin polymers using square wave voltammetry is discussed. It involves ashing, acid digestion of polymer samples and determination of titanium(IV) by catalytic reduction using square wave voltammetric (SWV) technique. A well defined peak of titanium(IV) in Britton-Robinson buffer solution containing EDTA and KBrO(3) is observed in the potential range of -0.10 to -0.40 vs. Ag/AgCl. Calibration graphs were linear in the range 0.05-0.25 microg/ml for titanium. Effects of pH and concentration of bromate, EDTA and buffer constituents are studied for the optimization of experimental conditions. Interference from other concomitants present in the polymer matrix are studied. Low density polyethylene (LDPE) obtained by tubular process was used for preparing the synthetic standards in order to optimize the experimental conditions and good recoveries (99-101%) were obtained. The method was extended to different polyolefin samples and the results obtained for the titanium content compared with those obtained by UV/Vis spectrophotometry. Statistical evaluation showed no significant bias between the two methods. SWV is found suitable for the estimation of Ti in the range 1-50 microg/g in polyolefin polymers with a RSD < 2.0%. 相似文献
89.
Anil P. Phadnis Bharati Sinha Bhagbat Nanda Sarita A. Patwardhan J. Venkatesh Rao Ravindra N. Sharma 《Monatshefte für Chemie / Chemical Monthly》1989,120(6-7):581-586
Summary A series of 8-proparglyoxy-3,7-dimethyl-2,6-octadienyl and 8-propargyloxy-3,7-dimethyl-6-octenyl ethers were prepared from 8-hydroxygeranyl and 8-hydroxycitronellyl ethers, respectively. Almost all compounds showed high toxicity toCulex quinquefaciatus larvae at 1 mgl–1 dose level.
Gegen Mücken aktive Produkte, 4. Mitt.: Synthese und biologische Aktivität von 8-Propargyloxy-3,7-dimethyl-2,6-octadienyl/6-octenyl-ethern
Zusammenfassung Eine Reihe von 8-Propargyloxy-3,7-dimethyl-2,6-octadienyl- und 8-propargyloxy-3,7-dimethyl-6-octenyl-ethern wurden aus 8-Hydroxygeranyl- bzw. 8-Hydroxycitronellyl-ethern hergestellt. Fast alle Verbindungen zeigten hoch Toxizität gegenüber Larven vonCulex quinquefaciatus in einer Dosierung von 1 mgl–1.相似文献
90.
Fe(3+) ions in alkali lead tetraborate glasses--an electron paramagnetic resonance and optical study
Chakradhar RP Sivaramaiah G Rao JL Gopal NO 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2005,62(1-3):51-57
Glass systems of composition 90R(2)B(4)O(7)+9PbO+1Fe(2)O(3) (R=Li, Na and K) and 90Li(2)B(4)O(7)+(10-x)PbO+xFe(2)O(3) (x=0.5, 1, 3, 4, 5, 7 and 9 mol %) have been investigated by means of electron paramagnetic resonance (EPR) and optical absorption techniques. The EPR spectra exhibit three resonance signals at g approximately 6.0, 4.2 and 2.0. The resonances at g approximately 6.0 and 4.2 are attributed to Fe(3+) ions in rhombic and axial symmetry sites, respectively. The g approximately 2.0 resonance signal is due to two or more Fe(3+) ions coupled together with dipolar interaction. The EPR spectra of 1 mol % of Fe(2)O(3) doped in lithium lead tetraborate glass samples have been studied at different temperatures (123-433 K). The intensity of g approximately 4.2 resonance signal decreases and the intensity of g approximately 2.0 resonance signal increases with the increase of temperature. The line widths are found to be independent of temperature. The EPR spectra exhibit a marked concentration dependence on iron content. A decrease in intensity for the resonance signal at g approximately 4.2 with increase in iron content for more than 4 mol % has been observed in lithium lead tetraborate glass samples and this has been attributed to the formation of Fe(3+) ion clusters in the glass samples. The paramagnetic susceptibility (chi) is calculated from the EPR data at various temperatures and the Curie constant (C) has been evaluated from 1/chi versus T graph. The optical absorption spectrum of Fe(3+) ions in lithium lead tetraborate glasses exhibits three bands characteristic of Fe(3+) ions in an octahedral symmetry. The crystal field parameter D(q) and the Racah interelectronic repulsion parameters B and C have also been evaluated. The value of interelectronic repulsion parameter B (825 cm(-1)) obtained in the present work suggests that the bonding is moderately covalent. 相似文献