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FFH scientific research papers database
FFH database search (1991-2024):
1681.
Dojčinović, M; Mitrović, M; Martić, M; Vučelić, V; Vučelić, D
Sorption characteristics of paper produced from sepiolite Journal Article
In: Journal of the Serbian Chemical Society, vol. 66, no. 6, pp. 385-396, 2001.
@article{Dojčinović2001385,
title = {Sorption characteristics of paper produced from sepiolite},
author = {M Dojčinović and M Mitrović and M Martić and V Vučelić and D Vučelić},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035536378&partnerID=40&md5=bfacfe02f541dde26574ed743d56245d},
year = {2001},
date = {2001-01-01},
journal = {Journal of the Serbian Chemical Society},
volume = {66},
number = {6},
pages = {385-396},
abstract = {Paper laboratory-produced from sepiolite, Goleš-Serbia was studied to determine its sorption characteristics for nitric oxides, water vapor, and ammonia. The paper adsorbed high percentages of nitric oxides and ammonia was stoichiometrically chemisorbed on paper saturated with NO 2 and H 2 O. Infrared spectroscopy showed that the sorption of nitric oxides and ammonia does not destroy the crystal lattice of sepiolite, which was confirmed by XRD-analysis. Sorption of both nitric oxides and ammonia occurred by zeolitic water inside the structural channels of sepiolite. Pressure swing adsorption (PSA) or temperature swing adsorption (TSA) cycles can be repeated many times, in the case of NO x and NH 3 .},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Paper laboratory-produced from sepiolite, Goleš-Serbia was studied to determine its sorption characteristics for nitric oxides, water vapor, and ammonia. The paper adsorbed high percentages of nitric oxides and ammonia was stoichiometrically chemisorbed on paper saturated with NO 2 and H 2 O. Infrared spectroscopy showed that the sorption of nitric oxides and ammonia does not destroy the crystal lattice of sepiolite, which was confirmed by XRD-analysis. Sorption of both nitric oxides and ammonia occurred by zeolitic water inside the structural channels of sepiolite. Pressure swing adsorption (PSA) or temperature swing adsorption (TSA) cycles can be repeated many times, in the case of NO x and NH 3 .
1682.
Sužnjević, D; Erceg, M; Vučelić, D
In: Microchemical Journal, vol. 69, no. 1, pp. 59-71, 2001.
@article{Sužnjević200159,
title = {Indirect method for quantitative determination of bovine serum albumin and transferin by anodic stripping voltammetry with a rotating glassy carbon electrode},
author = {D Sužnjević and M Erceg and D Vučelić},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035063512&doi=10.1016%2fS0026-265X%2801%2900067-4&partnerID=40&md5=5d5cb41d98ebcbf9985f274bfc9db477},
doi = {10.1016/S0026-265X(01)00067-4},
year = {2001},
date = {2001-01-01},
journal = {Microchemical Journal},
volume = {69},
number = {1},
pages = {59-71},
abstract = {The present study was carried out in order to investigate whether the interaction of multifunctional transport proteins, bovine serum albumin (BSA) and transferin (TF), with some metal (ME) ions, such as Hg(II) and Cu(II), in buffered solution (pH 8.0), may serve as a base for indirect quantitative determination of both proteins. For this purpose anodic stripping voltammetry with a rotating glassy carbon electrode was applied. A sufficient sensitivity on the presence of protein in solution containing Me-ions was obtained only by using a mercury dissolution signal (peak) observed at 0.1 V vs. SCE. Quantities of BSA less than 5 × 10 -7 M were determined with a S.D. ± 5% (n = 10) for a concentration of 3 × 10 -7 M, and for TF the concentration less than 1.5 × 10 -7 M could be determined with S.D. ± 4% (n = 10) for a concentration of 1 × 10 -7 M. © 2001 Elsevier Science B.V.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The present study was carried out in order to investigate whether the interaction of multifunctional transport proteins, bovine serum albumin (BSA) and transferin (TF), with some metal (ME) ions, such as Hg(II) and Cu(II), in buffered solution (pH 8.0), may serve as a base for indirect quantitative determination of both proteins. For this purpose anodic stripping voltammetry with a rotating glassy carbon electrode was applied. A sufficient sensitivity on the presence of protein in solution containing Me-ions was obtained only by using a mercury dissolution signal (peak) observed at 0.1 V vs. SCE. Quantities of BSA less than 5 × 10 -7 M were determined with a S.D. ± 5% (n = 10) for a concentration of 3 × 10 -7 M, and for TF the concentration less than 1.5 × 10 -7 M could be determined with S.D. ± 4% (n = 10) for a concentration of 1 × 10 -7 M. © 2001 Elsevier Science B.V.
1683.
Radotić, K; Tasić, M; Jeremić, M; Budimlija, Z; Simić-Krstić, J; Polzović, A; Božović, Z
Fractal analysis of STM images of photochemical polymer of coniferyl alcohol Journal Article
In: General Physiology and Biophysics, vol. 20, no. 1, pp. 33-42, 2001.
@article{Radotić200133,
title = {Fractal analysis of STM images of photochemical polymer of coniferyl alcohol},
author = {K Radotić and M Tasić and M Jeremić and Z Budimlija and J Simić-Krstić and A Polzović and Z Božović},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035292390&partnerID=40&md5=d4980c4072328ab1b864871e220d4dba},
year = {2001},
date = {2001-01-01},
journal = {General Physiology and Biophysics},
volume = {20},
number = {1},
pages = {33-42},
abstract = {Fractal analysis was applied to images of photochemical lignin polymer obtained using scanning tunneling microscope. We studied the polymer obtained in vitro by ionic mechanism through UV radiation - induced polymerization. The analysis showed the regularity of the lignin-like polymer at different levels of organization. At the 95% confidence level, there was no significant difference in the fractal dimension between images representing different organizational levels of photochemical lignin. That means that lignin produced in in vitro conditions by photochemical mechanism of synthesis, has a fractal structural organization. The obtained values of the fractal dimension are in good agreement with the theoretically predicted value for the polyaddition and polycondensation mechanism of polymerization, known as the bulk model.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Fractal analysis was applied to images of photochemical lignin polymer obtained using scanning tunneling microscope. We studied the polymer obtained in vitro by ionic mechanism through UV radiation - induced polymerization. The analysis showed the regularity of the lignin-like polymer at different levels of organization. At the 95% confidence level, there was no significant difference in the fractal dimension between images representing different organizational levels of photochemical lignin. That means that lignin produced in in vitro conditions by photochemical mechanism of synthesis, has a fractal structural organization. The obtained values of the fractal dimension are in good agreement with the theoretically predicted value for the polyaddition and polycondensation mechanism of polymerization, known as the bulk model.
1684.
Vuckovic, M; Mentus, S V; Janata, E; Milosavljevic, B H
Fast dimerisation of the triparaquat radical dication Journal Article
In: Physical Chemistry Chemical Physics, vol. 3, no. 19, pp. 4310-4315, 2001.
@article{Vuckovic20014310,
title = {Fast dimerisation of the triparaquat radical dication},
author = {M Vuckovic and S V Mentus and E Janata and B H Milosavljevic},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035720010&doi=10.1039%2fb103926c&partnerID=40&md5=aa2115d6c3c7799cb765e0bc671efee3},
doi = {10.1039/b103926c},
year = {2001},
date = {2001-01-01},
journal = {Physical Chemistry Chemical Physics},
volume = {3},
number = {19},
pages = {4310-4315},
abstract = {The one-electron reduction of 2,4,6-tris(N-methylpyridinium-4-yl)pyridine trication, triparaquat, TPQ3+, synthesized in the form of the perchlorate salt, was studied by cyclic voltammetry on a platinum disc electrode. It was found that the reduction peak is centered at -880 mV (vs. SCE) at 500 mV s-1 scanning rate. The subsequent oxidation takes place at +75 mV, indicating an irreversible process, but no changes in the solution content were found after the oxidation. The blue colored reduction product reacts anomalistically slowly with oxygen with a second-order rate constant of (0.65 ± 0.01) mol-1 dm3 s-1. EPR experiments showed that the reduction product in ethanol solution does not possess an unpaired electron. A low temperature gamma radiolysis experiment revealed that the spectral peak maximum of the reduction product of TPQ3+ solubilized in PVA film is shifted ∼200 nm with respect to that obtained in aqueous solution at room temperature. Pulse radiolysis experiments proved that this seemingly inconsistent set of data was a consequence of the very fast dimerisation process 2TPQ2+·⇋(TPQ)24+ (kdim = 1.4 × 109 mol-1 dm3 s-1). Cyclic voltammetry experiments on a mercury electrode revealed that the second reduction step corresponds to the dimer reduction. The third and fourth reduction steps were irreversible and initiated further chemical reactions of triparaquat, which was consistent with the data obtained by the prolonged steady state gamma radiolysis.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The one-electron reduction of 2,4,6-tris(N-methylpyridinium-4-yl)pyridine trication, triparaquat, TPQ3+, synthesized in the form of the perchlorate salt, was studied by cyclic voltammetry on a platinum disc electrode. It was found that the reduction peak is centered at -880 mV (vs. SCE) at 500 mV s-1 scanning rate. The subsequent oxidation takes place at +75 mV, indicating an irreversible process, but no changes in the solution content were found after the oxidation. The blue colored reduction product reacts anomalistically slowly with oxygen with a second-order rate constant of (0.65 ± 0.01) mol-1 dm3 s-1. EPR experiments showed that the reduction product in ethanol solution does not possess an unpaired electron. A low temperature gamma radiolysis experiment revealed that the spectral peak maximum of the reduction product of TPQ3+ solubilized in PVA film is shifted ∼200 nm with respect to that obtained in aqueous solution at room temperature. Pulse radiolysis experiments proved that this seemingly inconsistent set of data was a consequence of the very fast dimerisation process 2TPQ2+·⇋(TPQ)24+ (kdim = 1.4 × 109 mol-1 dm3 s-1). Cyclic voltammetry experiments on a mercury electrode revealed that the second reduction step corresponds to the dimer reduction. The third and fourth reduction steps were irreversible and initiated further chemical reactions of triparaquat, which was consistent with the data obtained by the prolonged steady state gamma radiolysis.
1685.
Cvjetićanin, N D; Šašić, S
Raman spectroscopic study of lithium and sodium perchlorate association in propylene carbonate-water mixed solvents Journal Article
In: Journal of Raman Spectroscopy, vol. 31, no. 10, pp. 871-876, 2000.
@article{Cvjetićanin2000871,
title = {Raman spectroscopic study of lithium and sodium perchlorate association in propylene carbonate-water mixed solvents},
author = {N D Cvjetićanin and S Šašić},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033647452&doi=10.1002%2f1097-4555%28200010%2931%3a10%3c871%3a%3aAID-JRS584%3e3.0.CO%3b2-5&partnerID=40&md5=1953439d2bbaa0b4bb883561486ce80a},
doi = {10.1002/1097-4555(200010)31:10<871::AID-JRS584>3.0.CO;2-5},
year = {2000},
date = {2000-01-01},
journal = {Journal of Raman Spectroscopy},
volume = {31},
number = {10},
pages = {871-876},
abstract = {Raman spectra of 1 M solutions of LiClO4 and NaClO4 in propylene carbonate (PC) with different amounts of water added (H2O/cation mole ratio = 0-55.5) were recorded in the spectral region 880-980 cm-1. Principal component analysis, a statistical method and deconvolution were applied in investigating the association in these solutions. The results indicate the existence of a band at the high-wavenumber side of the v1 band of free perchlorate anion. As established by deconvolution, the position of the band is at 938-940 cm-1. This band is attributed to monodentate contact ion pairs and is present in the solutions of perchlorates in pure PC and with a minimum amount of water added. The presence of monodentate contact ion pairs was established by deconvolution of the Raman spectrum of a 1 M solution of Mg(ClO4)2 in pure PC, but at very low concentration. (C) 2000 John Wiley and Sons, Ltd.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Raman spectra of 1 M solutions of LiClO4 and NaClO4 in propylene carbonate (PC) with different amounts of water added (H2O/cation mole ratio = 0-55.5) were recorded in the spectral region 880-980 cm-1. Principal component analysis, a statistical method and deconvolution were applied in investigating the association in these solutions. The results indicate the existence of a band at the high-wavenumber side of the v1 band of free perchlorate anion. As established by deconvolution, the position of the band is at 938-940 cm-1. This band is attributed to monodentate contact ion pairs and is present in the solutions of perchlorates in pure PC and with a minimum amount of water added. The presence of monodentate contact ion pairs was established by deconvolution of the Raman spectrum of a 1 M solution of Mg(ClO4)2 in pure PC, but at very low concentration. (C) 2000 John Wiley and Sons, Ltd.
1686.
Marković, J M Dimitrić; Petranović, N A; Baranac, J M
A spectrophotometric study of the copigmentation of Malvin with caffeic and ferulic acids Journal Article
In: Journal of Agricultural and Food Chemistry, vol. 48, no. 11, pp. 5530-5536, 2000.
@article{DimitrićMarković20005530,
title = {A spectrophotometric study of the copigmentation of Malvin with caffeic and ferulic acids},
author = {J M Dimitrić Marković and N A Petranović and J M Baranac},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033662193&doi=10.1021%2fjf000038v&partnerID=40&md5=f2180aee44efab9cbbe65fb0d8ba5301},
doi = {10.1021/jf000038v},
year = {2000},
date = {2000-01-01},
journal = {Journal of Agricultural and Food Chemistry},
volume = {48},
number = {11},
pages = {5530-5536},
abstract = {The process of copigmentation of the anthocyanin molecule malvidin 3,5-diglucoside with two organic monocarboxylic phenolic acids, caffeic and ferulic acids, was studied via their absorption electronic spectra. The dependence of the copigmentation process on the pH of the medium, molecular concentration, and temperature was established. The process of copigmentation was observed at two pH values: 2.50 and 3.65. The stoichiometric ratio was 1:1 at both pH values. The copigmentation was characterized by approximately equal values of the equilibrium constant, K, within each of the pH values. The temperature was found to be a significant factor that determines the thermodynamic conditions of the copigmentation process, because the process is spontaneous (ΔG°< 0), and results in entropy loss (ΔS°< 0) at both pH values.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The process of copigmentation of the anthocyanin molecule malvidin 3,5-diglucoside with two organic monocarboxylic phenolic acids, caffeic and ferulic acids, was studied via their absorption electronic spectra. The dependence of the copigmentation process on the pH of the medium, molecular concentration, and temperature was established. The process of copigmentation was observed at two pH values: 2.50 and 3.65. The stoichiometric ratio was 1:1 at both pH values. The copigmentation was characterized by approximately equal values of the equilibrium constant, K, within each of the pH values. The temperature was found to be a significant factor that determines the thermodynamic conditions of the copigmentation process, because the process is spontaneous (ΔG°< 0), and results in entropy loss (ΔS°< 0) at both pH values.
1687.
Radić-Perić, J; Markićević, M
The formation of boron, silicon and calcium containing molecular species in a graphite furnace in Ar/O2 mixtures Journal Article
In: Journal of the Serbian Chemical Society, vol. 65, no. 3, pp. 181-193, 2000.
@article{Radić-Perić2000181,
title = {The formation of boron, silicon and calcium containing molecular species in a graphite furnace in Ar/O2 mixtures},
author = {J Radić-Perić and M Markićević},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034382834&partnerID=40&md5=638be224292623be04edbde8e37d0934},
year = {2000},
date = {2000-01-01},
journal = {Journal of the Serbian Chemical Society},
volume = {65},
number = {3},
pages = {181-193},
abstract = {The composition of the Ar/O2/C gas system in the presence of traces of either B, Si or Ca was calculated under the assumption of thermal equilibrium in the temperature range 500-5500 K. The mole concentration of oxygen was taken to be 1-4 %. Two sets of calculations were carried out. In the first one the presence of solid phase (graphite) was ignored and the calculations were performed for a single-phase (gas) system, at variable ratios C/O (0.5, 0.96, 1 and 2). In the second set of calculations the presence of solid carbon (graphite) was taken into account and the composition of the gas system in equilibrium with solid carbon, at p = 1 atm, was determined. The results presented show that the equilibrium composition, particularly the concentration of different compounds involving the trace elements, is very sensitive to the amounts, and the ratio of the amounts of oxygen and carbon. Increasing the O/C ratio results in increasing partial pressures of molecular and atomic oxygen, which favours the formation of oxides of the trace elements and moves their atomization temperatures to higher values. On the other hand, increasing the C/O ratio (C/O >1) favours atomization, but also carbide formation in the lower-temperature region. It was found that, over a relatively wide temperature interval (1000 < T < 3500 K), the composition of the Ar/O2/C/X (X = B, Si, Ca) system, with comparable amounts of oxygen and carbon (C/O = 1), does not significantly depend on the presence of the solid phase. The results of calculations enable a reasonable interpretation of numerous experiments carried out on similar systems.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The composition of the Ar/O2/C gas system in the presence of traces of either B, Si or Ca was calculated under the assumption of thermal equilibrium in the temperature range 500-5500 K. The mole concentration of oxygen was taken to be 1-4 %. Two sets of calculations were carried out. In the first one the presence of solid phase (graphite) was ignored and the calculations were performed for a single-phase (gas) system, at variable ratios C/O (0.5, 0.96, 1 and 2). In the second set of calculations the presence of solid carbon (graphite) was taken into account and the composition of the gas system in equilibrium with solid carbon, at p = 1 atm, was determined. The results presented show that the equilibrium composition, particularly the concentration of different compounds involving the trace elements, is very sensitive to the amounts, and the ratio of the amounts of oxygen and carbon. Increasing the O/C ratio results in increasing partial pressures of molecular and atomic oxygen, which favours the formation of oxides of the trace elements and moves their atomization temperatures to higher values. On the other hand, increasing the C/O ratio (C/O >1) favours atomization, but also carbide formation in the lower-temperature region. It was found that, over a relatively wide temperature interval (1000 < T < 3500 K), the composition of the Ar/O2/C/X (X = B, Si, Ca) system, with comparable amounts of oxygen and carbon (C/O = 1), does not significantly depend on the presence of the solid phase. The results of calculations enable a reasonable interpretation of numerous experiments carried out on similar systems.
1688.
Blagojević, S; Pejič, N; Anić, S; Kolar-Anić, L
Belousov-Zhabotinsky oscillatory reaction. Kinetics of malonic acid decomposition Journal Article
In: Journal of the Serbian Chemical Society, vol. 65, no. 10, pp. 709-713, 2000.
@article{Blagojević2000709,
title = {Belousov-Zhabotinsky oscillatory reaction. Kinetics of malonic acid decomposition},
author = {S Blagojević and N Pejič and S Anić and L Kolar-Anić},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034345792&partnerID=40&md5=49942eb239e1b5782d744c9e64b9affa},
year = {2000},
date = {2000-01-01},
journal = {Journal of the Serbian Chemical Society},
volume = {65},
number = {10},
pages = {709-713},
abstract = {The kinetics of the Belousov-Zhabotinsky (BZ) oscillatory reaction was analyzed. With this aim, the time evolution of a reaction mixture composed of malonic acid, bromate, sulfuric acid and cerium(III) was studied at 298 K. Pseudo-first order kinetics with respect to malonic acid as the species undergoing decomposition with a corresponding rate constant},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The kinetics of the Belousov-Zhabotinsky (BZ) oscillatory reaction was analyzed. With this aim, the time evolution of a reaction mixture composed of malonic acid, bromate, sulfuric acid and cerium(III) was studied at 298 K. Pseudo-first order kinetics with respect to malonic acid as the species undergoing decomposition with a corresponding rate constant
1689.
Dondur, V; Marković, S; Mitrović, M; Dimitrijević, R
vol. 352, 2000.
@conference{Dondur2000105,
title = {Synthesis of Ni-spinel/aluminosilicate composite ceramics mixed at nanoscale level by using zeolite precursors},
author = {V Dondur and S Marković and M Mitrović and R Dimitrijević},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034546101&partnerID=40&md5=9463fca3bc93c6b03883013f61acd601},
year = {2000},
date = {2000-01-01},
journal = {Materials Science Forum},
volume = {352},
pages = {105-110},
abstract = {Thermally induced phase transformation of Ni-exchanged LTA, FAU, GIS and MOR zeolites were studied in the temperature range from room to 1500 °C. All investigated zeolite frameworks collapsed into amorphous intermediate products after heating between 800-900 °C. Prolonged heating of the intermediate products obtained from the Ni-exchanged zeolites over 900 °C, induces recrystallization of Ni-spinel phase (cubic-NiAl2O4) in all cases whereas silicate part recrystallizes into Ni-stuffed derivative phase of cristobalite (at Ni-GIS and Ni-MOR zeolite) or stay amorphous. Phase composition of ceramic products were studied by XRPD, SEM and IR techniques.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
Thermally induced phase transformation of Ni-exchanged LTA, FAU, GIS and MOR zeolites were studied in the temperature range from room to 1500 °C. All investigated zeolite frameworks collapsed into amorphous intermediate products after heating between 800-900 °C. Prolonged heating of the intermediate products obtained from the Ni-exchanged zeolites over 900 °C, induces recrystallization of Ni-spinel phase (cubic-NiAl2O4) in all cases whereas silicate part recrystallizes into Ni-stuffed derivative phase of cristobalite (at Ni-GIS and Ni-MOR zeolite) or stay amorphous. Phase composition of ceramic products were studied by XRPD, SEM and IR techniques.
1690.
Živković, P; Pješčić, J; Mentus, S
Corrosion behaviour of an AlZnSnSrGa alloy in aqueous solutions of NaCl and Na2SO4 Journal Article
In: Journal of the Serbian Chemical Society, vol. 65, no. 1, pp. 73-81, 2000.
@article{Živković200073,
title = {Corrosion behaviour of an AlZnSnSrGa alloy in aqueous solutions of NaCl and Na2SO4},
author = {P Živković and J Pješčić and S Mentus},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034344608&partnerID=40&md5=3179741d713e9942c688c7d0731fa779},
year = {2000},
date = {2000-01-01},
journal = {Journal of the Serbian Chemical Society},
volume = {65},
number = {1},
pages = {73-81},
abstract = {The alloy composed of Al(95.53%), Zn(2.85%), Sn(0.515%), Ga(0.1%) and Sr(0.009%), with the weight percents in the parentheses, was prepared by melting, using Al(99.84%), a product of the Aluminium Plant-Podgorica, as the base material. The corrosion behaviour of this alloy was tested in relation to the behaviour of the base metals, by both open curcuit potential and polarization resistance methods, in aqueous solutions of both NaCl and Na2SO4, the concentration of which varied within the range 0.00051-0.51 mol dm-3. Over the whole salt concentration ranges, the corrosion parameters indicate that the corrosion rate of the alloy is significantly higher than the rate of the base material. For instance, for the concentration range 0.00051-0.51 mol dm-3, the stationary open circuit potentials, related to SCE, in NaCl solutions were -1.200 to -1.460 V for the alloy and -0.693 to -0.920 V for Al, while in Na2SO4 solutions, the stationary open circuit potentials were - 1.190 to -1.465 V for the alloy and -0.780 to -0.860 V for Al. At the same time, the corrosion current density in NaCl solutions varied within 11-89 μA cm-2 for the alloy and 0.35-0.80 for Al, while in Na2SO4 solutions it amounted to 5.7-52 μA cm-2 for the alloy and 0.28 - 0.88 μ cm-2 for Al.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The alloy composed of Al(95.53%), Zn(2.85%), Sn(0.515%), Ga(0.1%) and Sr(0.009%), with the weight percents in the parentheses, was prepared by melting, using Al(99.84%), a product of the Aluminium Plant-Podgorica, as the base material. The corrosion behaviour of this alloy was tested in relation to the behaviour of the base metals, by both open curcuit potential and polarization resistance methods, in aqueous solutions of both NaCl and Na2SO4, the concentration of which varied within the range 0.00051-0.51 mol dm-3. Over the whole salt concentration ranges, the corrosion parameters indicate that the corrosion rate of the alloy is significantly higher than the rate of the base material. For instance, for the concentration range 0.00051-0.51 mol dm-3, the stationary open circuit potentials, related to SCE, in NaCl solutions were -1.200 to -1.460 V for the alloy and -0.693 to -0.920 V for Al, while in Na2SO4 solutions, the stationary open circuit potentials were - 1.190 to -1.465 V for the alloy and -0.780 to -0.860 V for Al. At the same time, the corrosion current density in NaCl solutions varied within 11-89 μA cm-2 for the alloy and 0.35-0.80 for Al, while in Na2SO4 solutions it amounted to 5.7-52 μA cm-2 for the alloy and 0.28 - 0.88 μ cm-2 for Al.
1691.
Miljanić, S S; Stjepanović, N N; Trtica, M S
An attemp to use a pulsed CO2 laser for decontamination of radioactive metal surfaces Journal Article
In: Journal of the Serbian Chemical Society, vol. 65, no. 5-6, pp. 445-450, 2000.
@article{Miljanić2000445,
title = {An attemp to use a pulsed CO2 laser for decontamination of radioactive metal surfaces},
author = {S S Miljanić and N N Stjepanović and M S Trtica},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034355246&partnerID=40&md5=14087cbc880fa123b19c90f7581951d0},
year = {2000},
date = {2000-01-01},
journal = {Journal of the Serbian Chemical Society},
volume = {65},
number = {5-6},
pages = {445-450},
abstract = {There is a growing interest in laser radioactive decontamination of metal surfaces. It offers advantages over conventional methods: improved safety, reduction of secondary waste, reduced waste volume, acceptable cost. The main mechanism of cleaning by lasers is ablation. A pulsed TEA CO2 laser was used in this work for surface cleaning in order to show that ablation of metal surfaces is possible even at relatively low pulse energies, and to suggest that it could be competitive with other lasers because of much higher energy efficiencies. A brief theoretical analysis was made before the experiments. The laser beam was focused using a KBr-lens onto a surface contaminated with 137Cs (β-, t1/2 = 30.17 y). Three different metals were used: stainless steel, copper and aluminium. The ablated material was pumped out in an air atmosphere and transferred to a filter. The presence of activity on the filter was shown by a germanium detector-multichannel analyzer. The activity levels were measured by a GM counter. The calculated decontamination factors and collection factors showed that ablation occurs with a relatively high efficiency of decontamination. This investigation suggests that decontamination using a CO2 laser should be seriously considered.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
There is a growing interest in laser radioactive decontamination of metal surfaces. It offers advantages over conventional methods: improved safety, reduction of secondary waste, reduced waste volume, acceptable cost. The main mechanism of cleaning by lasers is ablation. A pulsed TEA CO2 laser was used in this work for surface cleaning in order to show that ablation of metal surfaces is possible even at relatively low pulse energies, and to suggest that it could be competitive with other lasers because of much higher energy efficiencies. A brief theoretical analysis was made before the experiments. The laser beam was focused using a KBr-lens onto a surface contaminated with 137Cs (β-, t1/2 = 30.17 y). Three different metals were used: stainless steel, copper and aluminium. The ablated material was pumped out in an air atmosphere and transferred to a filter. The presence of activity on the filter was shown by a germanium detector-multichannel analyzer. The activity levels were measured by a GM counter. The calculated decontamination factors and collection factors showed that ablation occurs with a relatively high efficiency of decontamination. This investigation suggests that decontamination using a CO2 laser should be seriously considered.
1692.
Vukojević, V; Anić, S; Kolar-Anić, L
Investigation of dynamic behavior of the bray-liebhafsky reaction in the CSTR. Determination of bifurcation points Journal Article
In: Journal of Physical Chemistry A, vol. 104, no. 46, pp. 10731-10739, 2000.
@article{Vukojević200010731,
title = {Investigation of dynamic behavior of the bray-liebhafsky reaction in the CSTR. Determination of bifurcation points},
author = {V Vukojević and S Anić and L Kolar-Anić},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034319627&doi=10.1021%2fjp001165x&partnerID=40&md5=d327f07efe72f6c8f211e9aa34ce6a23},
doi = {10.1021/jp001165x},
year = {2000},
date = {2000-01-01},
journal = {Journal of Physical Chemistry A},
volume = {104},
number = {46},
pages = {10731-10739},
abstract = {Experimental results obtained by operating the Bray-Liebhafsky (BL) reaction in the CSTR are presented. The dynamic behavior of the BL reaction is examined at several operation points in the concentration phase space, by varying different parameters, the specific flow rate, temperature, and mixed inflow concentrations of the feed species, one at a time. Different types of bifurcation leading to simple periodic orbits, supercritical and subcritical Hopf bifurcations, saddle node infinite period bifurcation (SNIPER), saddle loop infinite period bifurcation, and jug handle bifurcation, are observed. Moreover, complex dynamic behavior, including transition from simple periodic oscillations to complex mixed-mode oscillations and chaos, and bistability are also discovered. © 2000 American Chemical Society.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Experimental results obtained by operating the Bray-Liebhafsky (BL) reaction in the CSTR are presented. The dynamic behavior of the BL reaction is examined at several operation points in the concentration phase space, by varying different parameters, the specific flow rate, temperature, and mixed inflow concentrations of the feed species, one at a time. Different types of bifurcation leading to simple periodic orbits, supercritical and subcritical Hopf bifurcations, saddle node infinite period bifurcation (SNIPER), saddle loop infinite period bifurcation, and jug handle bifurcation, are observed. Moreover, complex dynamic behavior, including transition from simple periodic oscillations to complex mixed-mode oscillations and chaos, and bistability are also discovered. © 2000 American Chemical Society.
1693.
Mićić, M; Jeremić, M; Radotić, K; Leblanc, R M
In: Journal of Colloid and Interface Science, vol. 231, no. 1, pp. 190-194, 2000.
@article{Mićić2000190,
title = {A comparative study of enzymatically and photochemically polymerized artificial lignin supramolecular structures using environmental scanning electron microscopy},
author = {M Mićić and M Jeremić and K Radotić and R M Leblanc},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034332642&doi=10.1006%2fjcis.2000.7136&partnerID=40&md5=c9db28861457411023eb1578d6d0ed8c},
doi = {10.1006/jcis.2000.7136},
year = {2000},
date = {2000-01-01},
journal = {Journal of Colloid and Interface Science},
volume = {231},
number = {1},
pages = {190-194},
abstract = {Environmental scanning electron microscopy images of the self-assembled structures of enzymatically (DHP) and photochemically polymerized (PCP) artificial lignin are herein presented. Differences in the structural organization between DHP and PCP polymer at the supramolecular level were reported. Based on topological information, we proposed a hypothesis about possible new physiological roles of lignin in live plant cells and the ecological significance of possible in-vivo photochemical lignin polymerization. (C) 2000 Academic Press.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Environmental scanning electron microscopy images of the self-assembled structures of enzymatically (DHP) and photochemically polymerized (PCP) artificial lignin are herein presented. Differences in the structural organization between DHP and PCP polymer at the supramolecular level were reported. Based on topological information, we proposed a hypothesis about possible new physiological roles of lignin in live plant cells and the ecological significance of possible in-vivo photochemical lignin polymerization. (C) 2000 Academic Press.
1694.
Pavlović, M S; Kuzmanović, M M; Pavelkić, V M; Marinković, M
The role of demixing effect in analyte emission enhancement by easily ionized elements in d.c. plasma Journal Article
In: Spectrochimica Acta - Part B Atomic Spectroscopy, vol. 55, no. 8, pp. 1373-1384, 2000.
@article{Pavlović20001373,
title = {The role of demixing effect in analyte emission enhancement by easily ionized elements in d.c. plasma},
author = {M S Pavlović and M M Kuzmanović and V M Pavelkić and M Marinković},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034245715&doi=10.1016%2fS0584-8547%2800%2900242-1&partnerID=40&md5=58f46c2c7457eb85a61183bf19a18318},
doi = {10.1016/S0584-8547(00)00242-1},
year = {2000},
date = {2000-01-01},
journal = {Spectrochimica Acta - Part B Atomic Spectroscopy},
volume = {55},
number = {8},
pages = {1373-1384},
abstract = {The effect of easily ionized elements (EIE) in d.c. plasma (DCP) has been modeled and experimentally investigated. The introduction of the EIEs in the U-shaped DCP decreases a 'potential barrier' due to an internal radial electric field, which allows the partially ionized analyte better entry into the hot plasma zone and produces enhancement of the analyte spectral emission. Compared to the equilibrium concentration, the increased electron concentration in the fringe region due to large radial gradients is accounted for in the model. By comparing model predictions to experimental data, the validity of the model is tested. The main features of the effect, the large enhancement at small addition of EIE and almost equal enhancement of ion and atom line intensities, are fairly well described by the model. The results are believed to be applicable to the inverted Y-shaped DCP. The effect in the inductively coupled plasma (ICP) has been briefly discussed from the point of view of the proposed model. © 2000 Elsevier Science B.V. All rights reserved.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The effect of easily ionized elements (EIE) in d.c. plasma (DCP) has been modeled and experimentally investigated. The introduction of the EIEs in the U-shaped DCP decreases a 'potential barrier' due to an internal radial electric field, which allows the partially ionized analyte better entry into the hot plasma zone and produces enhancement of the analyte spectral emission. Compared to the equilibrium concentration, the increased electron concentration in the fringe region due to large radial gradients is accounted for in the model. By comparing model predictions to experimental data, the validity of the model is tested. The main features of the effect, the large enhancement at small addition of EIE and almost equal enhancement of ion and atom line intensities, are fairly well described by the model. The results are believed to be applicable to the inverted Y-shaped DCP. The effect in the inductively coupled plasma (ICP) has been briefly discussed from the point of view of the proposed model. © 2000 Elsevier Science B.V. All rights reserved.
1695.
Mioč, U B; Marković, J M Dimitrić; Baranac, J M
A study of the IR spectra of copigments formed by malvin chloride with flavones Journal Article
In: Journal of the Serbian Chemical Society, vol. 65, no. 4, pp. 245-253, 2000.
@article{Mioč2000245,
title = {A study of the IR spectra of copigments formed by malvin chloride with flavones},
author = {U B Mioč and J M Dimitrić Marković and J M Baranac},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034396355&partnerID=40&md5=b2900820101c119784a1381f3e8409d7},
year = {2000},
date = {2000-01-01},
journal = {Journal of the Serbian Chemical Society},
volume = {65},
number = {4},
pages = {245-253},
abstract = {Research into the essence of the process of copigmentation of anthocyan molecules was continued by applying IR spectroscopy, in an attempt to elucidate the formation mechanism of copigment molecules between malvin chloride and several variously substituted flavones. Analysis of the IR spectra of the formed copigments revealed that the process of copigmentation is achieved via the formation of hydrogen bonds. The strength of the formed hydrogen bonds was correlated with the equilibrium constants of the processes of copigmentation of these molecules. The found correlation was in accordance with the supposed mechanism of the copigmentation reaction.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Research into the essence of the process of copigmentation of anthocyan molecules was continued by applying IR spectroscopy, in an attempt to elucidate the formation mechanism of copigment molecules between malvin chloride and several variously substituted flavones. Analysis of the IR spectra of the formed copigments revealed that the process of copigmentation is achieved via the formation of hydrogen bonds. The strength of the formed hydrogen bonds was correlated with the equilibrium constants of the processes of copigmentation of these molecules. The found correlation was in accordance with the supposed mechanism of the copigmentation reaction.
1696.
Petković, J; Mladenović, I; Vukelić, N; Mojović, M; Bačić, G
Lanthanide doped alkaline metal sulphates as candidates for EPR dosimetry Journal Article
In: Journal of the Serbian Chemical Society, vol. 65, no. 10, pp. 743-754, 2000.
@article{Petković2000743,
title = {Lanthanide doped alkaline metal sulphates as candidates for EPR dosimetry},
author = {J Petković and I Mladenović and N Vukelić and M Mojović and G Bačić},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034345791&partnerID=40&md5=219016ccd4976028a647e58a380331b4},
year = {2000},
date = {2000-01-01},
journal = {Journal of the Serbian Chemical Society},
volume = {65},
number = {10},
pages = {743-754},
abstract = {The applicability of lanthanide doped alkaline metal sulphates as a new type of dosimeters for EPR dosimetery of ionizing radiation has been investigated in an attempt to obtain a dosimeter with better characteristics than the commonly used alanine dosimeter. Irradiation of samples doped with different lanthanides (Y, Ln, Gd) showed that the best sensitivity is obtained using dosimeters doped with Y 2 (SO 4 ) 3 . Different procedures for manufacturing dosimeters were studied and an optimum procedure was established. The time stability of the EPR signal of the irradiated Y 2 (SO 4 ) 3 dosimeter was investigated using a 15 N-PDT standard and no fading of the EPR signal was observed over at least two weeks. The dose dependence of alanine and Y 2 (SO 4 ) 3 doped K 3 Na(SO 4 ) 2 dosimeters irradiated in the range 20 Gy - 200 kGy was analysed using a combination of 1-hit and 2-hit mechanisms of free radicals creation.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The applicability of lanthanide doped alkaline metal sulphates as a new type of dosimeters for EPR dosimetery of ionizing radiation has been investigated in an attempt to obtain a dosimeter with better characteristics than the commonly used alanine dosimeter. Irradiation of samples doped with different lanthanides (Y, Ln, Gd) showed that the best sensitivity is obtained using dosimeters doped with Y 2 (SO 4 ) 3 . Different procedures for manufacturing dosimeters were studied and an optimum procedure was established. The time stability of the EPR signal of the irradiated Y 2 (SO 4 ) 3 dosimeter was investigated using a 15 N-PDT standard and no fading of the EPR signal was observed over at least two weeks. The dose dependence of alanine and Y 2 (SO 4 ) 3 doped K 3 Na(SO 4 ) 2 dosimeters irradiated in the range 20 Gy - 200 kGy was analysed using a combination of 1-hit and 2-hit mechanisms of free radicals creation.
1697.
Petranović, N; Minić, D; Sabo, T J; Doković, D
Kinetic and thermodynamic studies of facial and meridional uns-cis-[Co(eddp)gly] complexes Journal Article
In: Journal of Thermal Analysis and Calorimetry, vol. 59, no. 3, pp. 807-814, 2000.
@article{Petranović2000807,
title = {Kinetic and thermodynamic studies of facial and meridional uns-cis-[Co(eddp)gly] complexes},
author = {N Petranović and D Minić and T J Sabo and D Doković},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033748798&partnerID=40&md5=c0a835661c228b1dec521d48be94b05c},
year = {2000},
date = {2000-01-01},
journal = {Journal of Thermal Analysis and Calorimetry},
volume = {59},
number = {3},
pages = {807-814},
abstract = {Thermal properties of facial and meridional uns-cis-[Co(eddp)gly]·0.5H2O complexes were investigated by means of DSC and TG techniques. It was shown that the processes of thermal decomposition of these complexes are multi-step degradation processes, which can also be well separated into individual steps, depending on the molecular symmetry. Thus, the process of thermal degradation of the meridional isomer of the above complex consists of 4 well-separated steps in the temperature interval from 100 to 500°C. The corresponding kinetic and thermodynamic parameters of this process were determined, and a possible mechanism is discussed.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Thermal properties of facial and meridional uns-cis-[Co(eddp)gly]·0.5H2O complexes were investigated by means of DSC and TG techniques. It was shown that the processes of thermal decomposition of these complexes are multi-step degradation processes, which can also be well separated into individual steps, depending on the molecular symmetry. Thus, the process of thermal degradation of the meridional isomer of the above complex consists of 4 well-separated steps in the temperature interval from 100 to 500°C. The corresponding kinetic and thermodynamic parameters of this process were determined, and a possible mechanism is discussed.
1698.
Kuntić, V; Malešev, D; Radović, Z; Vukojević, V
Spectrophotometric investigation of the complexing reaction between rutin and titanyloxalate anion in 50% ethanol Journal Article
In: Monatshefte fur Chemie, vol. 131, no. 7, pp. 769-777, 2000.
@article{Kuntić2000769,
title = {Spectrophotometric investigation of the complexing reaction between rutin and titanyloxalate anion in 50% ethanol},
author = {V Kuntić and D Malešev and Z Radović and V Vukojević},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0008626740&doi=10.1007%2fs007060050024&partnerID=40&md5=cc9535955abb0cae8040dbd0a1229660},
doi = {10.1007/s007060050024},
year = {2000},
date = {2000-01-01},
journal = {Monatshefte fur Chemie},
volume = {131},
number = {7},
pages = {769-777},
abstract = {In the present work, rutin (3,3′,4′,5,7-pentahydrohyflavone-3-rhamnoglucoside) was determinated via a complexing reaction with a titanyloxalate anion. K2(TiO(C2O4)2] and rutin react in 50% ethanol forming a 1:2 complex in a pH range from 4.00 to 11.50, in which the TiO(C2O4)2-2 ion is linked to rutin through the 4-carbonyl and 5-hydroxyl group. The thermodynamic stability constant log β02 of the complex is determined to 10.80 at pH = 6.50. The change of the standard Gibbs free energy ΔG0 amounts to -61 kJ · mol-1, indicating that the process of complex formation is spontaneous. The optimal conditions for the spectrophotometric determination of microconcentrations of rutin are at pH = 6.40 and λ = 430 nm, where the complex shows an absorption maximum with a molar absorption coefficient a430 = (60±2) · 103 dm3 · mol-1 · cm-1. The method is applied rutin determination from tablets.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
In the present work, rutin (3,3′,4′,5,7-pentahydrohyflavone-3-rhamnoglucoside) was determinated via a complexing reaction with a titanyloxalate anion. K2(TiO(C2O4)2] and rutin react in 50% ethanol forming a 1:2 complex in a pH range from 4.00 to 11.50, in which the TiO(C2O4)2-2 ion is linked to rutin through the 4-carbonyl and 5-hydroxyl group. The thermodynamic stability constant log β02 of the complex is determined to 10.80 at pH = 6.50. The change of the standard Gibbs free energy ΔG0 amounts to -61 kJ · mol-1, indicating that the process of complex formation is spontaneous. The optimal conditions for the spectrophotometric determination of microconcentrations of rutin are at pH = 6.40 and λ = 430 nm, where the complex shows an absorption maximum with a molar absorption coefficient a430 = (60±2) · 103 dm3 · mol-1 · cm-1. The method is applied rutin determination from tablets.
1699.
Mioč, U B; Todorović, M R; Uskoković-Marković, S M; Nedić, Z P; Bošnjaković, N S
A spectroscopic investigation of 12-tungstophosphoric acid alkali salts Journal Article
In: Journal of the Serbian Chemical Society, vol. 65, no. 5-6, pp. 399-406, 2000.
@article{Mioč2000399,
title = {A spectroscopic investigation of 12-tungstophosphoric acid alkali salts},
author = {U B Mioč and M R Todorović and S M Uskoković-Marković and Z P Nedić and N S Bošnjaković},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034360716&partnerID=40&md5=6b306e2be7e8f0b4af729f9210ea32c7},
year = {2000},
date = {2000-01-01},
journal = {Journal of the Serbian Chemical Society},
volume = {65},
number = {5-6},
pages = {399-406},
abstract = {In this paper the latest results of our continuing investigation of heteropoly acids and their salts are reported. Specially attention was paid to the influence of cations on the dynamic equilibrium of protonic species, as well as on the structure of the host lattice itself, i.e., the Keggin anions. The investigations were done by IR and Raman spectroscopy within the range of 1200-40 cm -1 .},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
In this paper the latest results of our continuing investigation of heteropoly acids and their salts are reported. Specially attention was paid to the influence of cations on the dynamic equilibrium of protonic species, as well as on the structure of the host lattice itself, i.e., the Keggin anions. The investigations were done by IR and Raman spectroscopy within the range of 1200-40 cm -1 .
1700.
Bogunović, L J; Mioč, U B; Jovanović, B Ž; Juranić, I O
Infrared study of some 2-substituted-6-hydroxy-4-pyrimidine carboxylic acids. Correlation with MO-calculations Journal Article
In: Journal of the Serbian Chemical Society, vol. 65, no. 5-6, pp. 371-379, 2000.
@article{Bogunović2000371,
title = {Infrared study of some 2-substituted-6-hydroxy-4-pyrimidine carboxylic acids. Correlation with MO-calculations},
author = {L J Bogunović and U B Mioč and B Ž Jovanović and I O Juranić},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034363411&partnerID=40&md5=3f56af5189ee9f5b648138924f99728e},
year = {2000},
date = {2000-01-01},
journal = {Journal of the Serbian Chemical Society},
volume = {65},
number = {5-6},
pages = {371-379},
abstract = {The IR spectra of a series of 2-substituted-6-hydroxy-4-pyrimidine carboxylic acids (substituent = OH, SH, CH 3 , CH 3 S and NH 2 ) were studied from the aspect of the influence of the subsitutent on the polarizability of some bonds, keto-enol tautomerism and hydrogen bond formation. The spectra were taken using solids due to the low solubility of the acids. Theoretical calculations were done using the MNDO-AM1 semiempirical molecular-orbital method. The stabilities of various tautomers were calculated simulating the dielectric continuum using the COSMO facility of the MOPAC program package. Theoretical calculations were made for all the possible tautomers of the 2-substituted-6-hydroxy-4-pyrimidine carboxylic acids. For the most stable isomers, the vibrational spectra were calculated. For the majority of the compounds the most stable isomer was identified having the structure 2-Y-6-oxo-4-carboxy-3H-pyrimidine. Besides this structure, for the 2-amino-, and 2-methyl-derivatives the zwitterionic forms have very similar stability. The 2-hydroxy compound is most stable as the 2,6-dioxo-1H, 3H isomer. The calculated vibrations for the compounds with a single stable structure correlate very well with the experimental frequencies. For the 2-methyl- and 2-amino-compounds the correlation is considerably less satisfactory. The most probable reason for this deviation is the existence of two or more tautomets in equilibrium. The correlation of the measured frequencies and the pK a values of the acids, indicate that the same tautomers exist in the solid state and in the solution.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The IR spectra of a series of 2-substituted-6-hydroxy-4-pyrimidine carboxylic acids (substituent = OH, SH, CH 3 , CH 3 S and NH 2 ) were studied from the aspect of the influence of the subsitutent on the polarizability of some bonds, keto-enol tautomerism and hydrogen bond formation. The spectra were taken using solids due to the low solubility of the acids. Theoretical calculations were done using the MNDO-AM1 semiempirical molecular-orbital method. The stabilities of various tautomers were calculated simulating the dielectric continuum using the COSMO facility of the MOPAC program package. Theoretical calculations were made for all the possible tautomers of the 2-substituted-6-hydroxy-4-pyrimidine carboxylic acids. For the most stable isomers, the vibrational spectra were calculated. For the majority of the compounds the most stable isomer was identified having the structure 2-Y-6-oxo-4-carboxy-3H-pyrimidine. Besides this structure, for the 2-amino-, and 2-methyl-derivatives the zwitterionic forms have very similar stability. The 2-hydroxy compound is most stable as the 2,6-dioxo-1H, 3H isomer. The calculated vibrations for the compounds with a single stable structure correlate very well with the experimental frequencies. For the 2-methyl- and 2-amino-compounds the correlation is considerably less satisfactory. The most probable reason for this deviation is the existence of two or more tautomets in equilibrium. The correlation of the measured frequencies and the pK a values of the acids, indicate that the same tautomers exist in the solid state and in the solution.
2001
Dojčinović, M; Mitrović, M; Martić, M; Vučelić, V; Vučelić, D
Sorption characteristics of paper produced from sepiolite Journal Article
In: Journal of the Serbian Chemical Society, vol. 66, no. 6, pp. 385-396, 2001.
@article{Dojčinović2001385,
title = {Sorption characteristics of paper produced from sepiolite},
author = {M Dojčinović and M Mitrović and M Martić and V Vučelić and D Vučelić},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035536378&partnerID=40&md5=bfacfe02f541dde26574ed743d56245d},
year = {2001},
date = {2001-01-01},
journal = {Journal of the Serbian Chemical Society},
volume = {66},
number = {6},
pages = {385-396},
abstract = {Paper laboratory-produced from sepiolite, Goleš-Serbia was studied to determine its sorption characteristics for nitric oxides, water vapor, and ammonia. The paper adsorbed high percentages of nitric oxides and ammonia was stoichiometrically chemisorbed on paper saturated with NO 2 and H 2 O. Infrared spectroscopy showed that the sorption of nitric oxides and ammonia does not destroy the crystal lattice of sepiolite, which was confirmed by XRD-analysis. Sorption of both nitric oxides and ammonia occurred by zeolitic water inside the structural channels of sepiolite. Pressure swing adsorption (PSA) or temperature swing adsorption (TSA) cycles can be repeated many times, in the case of NO x and NH 3 .},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Paper laboratory-produced from sepiolite, Goleš-Serbia was studied to determine its sorption characteristics for nitric oxides, water vapor, and ammonia. The paper adsorbed high percentages of nitric oxides and ammonia was stoichiometrically chemisorbed on paper saturated with NO 2 and H 2 O. Infrared spectroscopy showed that the sorption of nitric oxides and ammonia does not destroy the crystal lattice of sepiolite, which was confirmed by XRD-analysis. Sorption of both nitric oxides and ammonia occurred by zeolitic water inside the structural channels of sepiolite. Pressure swing adsorption (PSA) or temperature swing adsorption (TSA) cycles can be repeated many times, in the case of NO x and NH 3 .
Sužnjević, D; Erceg, M; Vučelić, D
In: Microchemical Journal, vol. 69, no. 1, pp. 59-71, 2001.
@article{Sužnjević200159,
title = {Indirect method for quantitative determination of bovine serum albumin and transferin by anodic stripping voltammetry with a rotating glassy carbon electrode},
author = {D Sužnjević and M Erceg and D Vučelić},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035063512&doi=10.1016%2fS0026-265X%2801%2900067-4&partnerID=40&md5=5d5cb41d98ebcbf9985f274bfc9db477},
doi = {10.1016/S0026-265X(01)00067-4},
year = {2001},
date = {2001-01-01},
journal = {Microchemical Journal},
volume = {69},
number = {1},
pages = {59-71},
abstract = {The present study was carried out in order to investigate whether the interaction of multifunctional transport proteins, bovine serum albumin (BSA) and transferin (TF), with some metal (ME) ions, such as Hg(II) and Cu(II), in buffered solution (pH 8.0), may serve as a base for indirect quantitative determination of both proteins. For this purpose anodic stripping voltammetry with a rotating glassy carbon electrode was applied. A sufficient sensitivity on the presence of protein in solution containing Me-ions was obtained only by using a mercury dissolution signal (peak) observed at 0.1 V vs. SCE. Quantities of BSA less than 5 × 10 -7 M were determined with a S.D. ± 5% (n = 10) for a concentration of 3 × 10 -7 M, and for TF the concentration less than 1.5 × 10 -7 M could be determined with S.D. ± 4% (n = 10) for a concentration of 1 × 10 -7 M. © 2001 Elsevier Science B.V.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The present study was carried out in order to investigate whether the interaction of multifunctional transport proteins, bovine serum albumin (BSA) and transferin (TF), with some metal (ME) ions, such as Hg(II) and Cu(II), in buffered solution (pH 8.0), may serve as a base for indirect quantitative determination of both proteins. For this purpose anodic stripping voltammetry with a rotating glassy carbon electrode was applied. A sufficient sensitivity on the presence of protein in solution containing Me-ions was obtained only by using a mercury dissolution signal (peak) observed at 0.1 V vs. SCE. Quantities of BSA less than 5 × 10 -7 M were determined with a S.D. ± 5% (n = 10) for a concentration of 3 × 10 -7 M, and for TF the concentration less than 1.5 × 10 -7 M could be determined with S.D. ± 4% (n = 10) for a concentration of 1 × 10 -7 M. © 2001 Elsevier Science B.V.
Radotić, K; Tasić, M; Jeremić, M; Budimlija, Z; Simić-Krstić, J; Polzović, A; Božović, Z
Fractal analysis of STM images of photochemical polymer of coniferyl alcohol Journal Article
In: General Physiology and Biophysics, vol. 20, no. 1, pp. 33-42, 2001.
@article{Radotić200133,
title = {Fractal analysis of STM images of photochemical polymer of coniferyl alcohol},
author = {K Radotić and M Tasić and M Jeremić and Z Budimlija and J Simić-Krstić and A Polzović and Z Božović},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035292390&partnerID=40&md5=d4980c4072328ab1b864871e220d4dba},
year = {2001},
date = {2001-01-01},
journal = {General Physiology and Biophysics},
volume = {20},
number = {1},
pages = {33-42},
abstract = {Fractal analysis was applied to images of photochemical lignin polymer obtained using scanning tunneling microscope. We studied the polymer obtained in vitro by ionic mechanism through UV radiation - induced polymerization. The analysis showed the regularity of the lignin-like polymer at different levels of organization. At the 95% confidence level, there was no significant difference in the fractal dimension between images representing different organizational levels of photochemical lignin. That means that lignin produced in in vitro conditions by photochemical mechanism of synthesis, has a fractal structural organization. The obtained values of the fractal dimension are in good agreement with the theoretically predicted value for the polyaddition and polycondensation mechanism of polymerization, known as the bulk model.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Fractal analysis was applied to images of photochemical lignin polymer obtained using scanning tunneling microscope. We studied the polymer obtained in vitro by ionic mechanism through UV radiation - induced polymerization. The analysis showed the regularity of the lignin-like polymer at different levels of organization. At the 95% confidence level, there was no significant difference in the fractal dimension between images representing different organizational levels of photochemical lignin. That means that lignin produced in in vitro conditions by photochemical mechanism of synthesis, has a fractal structural organization. The obtained values of the fractal dimension are in good agreement with the theoretically predicted value for the polyaddition and polycondensation mechanism of polymerization, known as the bulk model.
Vuckovic, M; Mentus, S V; Janata, E; Milosavljevic, B H
Fast dimerisation of the triparaquat radical dication Journal Article
In: Physical Chemistry Chemical Physics, vol. 3, no. 19, pp. 4310-4315, 2001.
@article{Vuckovic20014310,
title = {Fast dimerisation of the triparaquat radical dication},
author = {M Vuckovic and S V Mentus and E Janata and B H Milosavljevic},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0035720010&doi=10.1039%2fb103926c&partnerID=40&md5=aa2115d6c3c7799cb765e0bc671efee3},
doi = {10.1039/b103926c},
year = {2001},
date = {2001-01-01},
journal = {Physical Chemistry Chemical Physics},
volume = {3},
number = {19},
pages = {4310-4315},
abstract = {The one-electron reduction of 2,4,6-tris(N-methylpyridinium-4-yl)pyridine trication, triparaquat, TPQ3+, synthesized in the form of the perchlorate salt, was studied by cyclic voltammetry on a platinum disc electrode. It was found that the reduction peak is centered at -880 mV (vs. SCE) at 500 mV s-1 scanning rate. The subsequent oxidation takes place at +75 mV, indicating an irreversible process, but no changes in the solution content were found after the oxidation. The blue colored reduction product reacts anomalistically slowly with oxygen with a second-order rate constant of (0.65 ± 0.01) mol-1 dm3 s-1. EPR experiments showed that the reduction product in ethanol solution does not possess an unpaired electron. A low temperature gamma radiolysis experiment revealed that the spectral peak maximum of the reduction product of TPQ3+ solubilized in PVA film is shifted ∼200 nm with respect to that obtained in aqueous solution at room temperature. Pulse radiolysis experiments proved that this seemingly inconsistent set of data was a consequence of the very fast dimerisation process 2TPQ2+·⇋(TPQ)24+ (kdim = 1.4 × 109 mol-1 dm3 s-1). Cyclic voltammetry experiments on a mercury electrode revealed that the second reduction step corresponds to the dimer reduction. The third and fourth reduction steps were irreversible and initiated further chemical reactions of triparaquat, which was consistent with the data obtained by the prolonged steady state gamma radiolysis.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The one-electron reduction of 2,4,6-tris(N-methylpyridinium-4-yl)pyridine trication, triparaquat, TPQ3+, synthesized in the form of the perchlorate salt, was studied by cyclic voltammetry on a platinum disc electrode. It was found that the reduction peak is centered at -880 mV (vs. SCE) at 500 mV s-1 scanning rate. The subsequent oxidation takes place at +75 mV, indicating an irreversible process, but no changes in the solution content were found after the oxidation. The blue colored reduction product reacts anomalistically slowly with oxygen with a second-order rate constant of (0.65 ± 0.01) mol-1 dm3 s-1. EPR experiments showed that the reduction product in ethanol solution does not possess an unpaired electron. A low temperature gamma radiolysis experiment revealed that the spectral peak maximum of the reduction product of TPQ3+ solubilized in PVA film is shifted ∼200 nm with respect to that obtained in aqueous solution at room temperature. Pulse radiolysis experiments proved that this seemingly inconsistent set of data was a consequence of the very fast dimerisation process 2TPQ2+·⇋(TPQ)24+ (kdim = 1.4 × 109 mol-1 dm3 s-1). Cyclic voltammetry experiments on a mercury electrode revealed that the second reduction step corresponds to the dimer reduction. The third and fourth reduction steps were irreversible and initiated further chemical reactions of triparaquat, which was consistent with the data obtained by the prolonged steady state gamma radiolysis.
2000
Cvjetićanin, N D; Šašić, S
Raman spectroscopic study of lithium and sodium perchlorate association in propylene carbonate-water mixed solvents Journal Article
In: Journal of Raman Spectroscopy, vol. 31, no. 10, pp. 871-876, 2000.
@article{Cvjetićanin2000871,
title = {Raman spectroscopic study of lithium and sodium perchlorate association in propylene carbonate-water mixed solvents},
author = {N D Cvjetićanin and S Šašić},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033647452&doi=10.1002%2f1097-4555%28200010%2931%3a10%3c871%3a%3aAID-JRS584%3e3.0.CO%3b2-5&partnerID=40&md5=1953439d2bbaa0b4bb883561486ce80a},
doi = {10.1002/1097-4555(200010)31:10<871::AID-JRS584>3.0.CO;2-5},
year = {2000},
date = {2000-01-01},
journal = {Journal of Raman Spectroscopy},
volume = {31},
number = {10},
pages = {871-876},
abstract = {Raman spectra of 1 M solutions of LiClO4 and NaClO4 in propylene carbonate (PC) with different amounts of water added (H2O/cation mole ratio = 0-55.5) were recorded in the spectral region 880-980 cm-1. Principal component analysis, a statistical method and deconvolution were applied in investigating the association in these solutions. The results indicate the existence of a band at the high-wavenumber side of the v1 band of free perchlorate anion. As established by deconvolution, the position of the band is at 938-940 cm-1. This band is attributed to monodentate contact ion pairs and is present in the solutions of perchlorates in pure PC and with a minimum amount of water added. The presence of monodentate contact ion pairs was established by deconvolution of the Raman spectrum of a 1 M solution of Mg(ClO4)2 in pure PC, but at very low concentration. (C) 2000 John Wiley and Sons, Ltd.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Raman spectra of 1 M solutions of LiClO4 and NaClO4 in propylene carbonate (PC) with different amounts of water added (H2O/cation mole ratio = 0-55.5) were recorded in the spectral region 880-980 cm-1. Principal component analysis, a statistical method and deconvolution were applied in investigating the association in these solutions. The results indicate the existence of a band at the high-wavenumber side of the v1 band of free perchlorate anion. As established by deconvolution, the position of the band is at 938-940 cm-1. This band is attributed to monodentate contact ion pairs and is present in the solutions of perchlorates in pure PC and with a minimum amount of water added. The presence of monodentate contact ion pairs was established by deconvolution of the Raman spectrum of a 1 M solution of Mg(ClO4)2 in pure PC, but at very low concentration. (C) 2000 John Wiley and Sons, Ltd.
Marković, J M Dimitrić; Petranović, N A; Baranac, J M
A spectrophotometric study of the copigmentation of Malvin with caffeic and ferulic acids Journal Article
In: Journal of Agricultural and Food Chemistry, vol. 48, no. 11, pp. 5530-5536, 2000.
@article{DimitrićMarković20005530,
title = {A spectrophotometric study of the copigmentation of Malvin with caffeic and ferulic acids},
author = {J M Dimitrić Marković and N A Petranović and J M Baranac},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033662193&doi=10.1021%2fjf000038v&partnerID=40&md5=f2180aee44efab9cbbe65fb0d8ba5301},
doi = {10.1021/jf000038v},
year = {2000},
date = {2000-01-01},
journal = {Journal of Agricultural and Food Chemistry},
volume = {48},
number = {11},
pages = {5530-5536},
abstract = {The process of copigmentation of the anthocyanin molecule malvidin 3,5-diglucoside with two organic monocarboxylic phenolic acids, caffeic and ferulic acids, was studied via their absorption electronic spectra. The dependence of the copigmentation process on the pH of the medium, molecular concentration, and temperature was established. The process of copigmentation was observed at two pH values: 2.50 and 3.65. The stoichiometric ratio was 1:1 at both pH values. The copigmentation was characterized by approximately equal values of the equilibrium constant, K, within each of the pH values. The temperature was found to be a significant factor that determines the thermodynamic conditions of the copigmentation process, because the process is spontaneous (ΔG°< 0), and results in entropy loss (ΔS°< 0) at both pH values.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The process of copigmentation of the anthocyanin molecule malvidin 3,5-diglucoside with two organic monocarboxylic phenolic acids, caffeic and ferulic acids, was studied via their absorption electronic spectra. The dependence of the copigmentation process on the pH of the medium, molecular concentration, and temperature was established. The process of copigmentation was observed at two pH values: 2.50 and 3.65. The stoichiometric ratio was 1:1 at both pH values. The copigmentation was characterized by approximately equal values of the equilibrium constant, K, within each of the pH values. The temperature was found to be a significant factor that determines the thermodynamic conditions of the copigmentation process, because the process is spontaneous (ΔG°< 0), and results in entropy loss (ΔS°< 0) at both pH values.
Radić-Perić, J; Markićević, M
The formation of boron, silicon and calcium containing molecular species in a graphite furnace in Ar/O2 mixtures Journal Article
In: Journal of the Serbian Chemical Society, vol. 65, no. 3, pp. 181-193, 2000.
@article{Radić-Perić2000181,
title = {The formation of boron, silicon and calcium containing molecular species in a graphite furnace in Ar/O2 mixtures},
author = {J Radić-Perić and M Markićević},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034382834&partnerID=40&md5=638be224292623be04edbde8e37d0934},
year = {2000},
date = {2000-01-01},
journal = {Journal of the Serbian Chemical Society},
volume = {65},
number = {3},
pages = {181-193},
abstract = {The composition of the Ar/O2/C gas system in the presence of traces of either B, Si or Ca was calculated under the assumption of thermal equilibrium in the temperature range 500-5500 K. The mole concentration of oxygen was taken to be 1-4 %. Two sets of calculations were carried out. In the first one the presence of solid phase (graphite) was ignored and the calculations were performed for a single-phase (gas) system, at variable ratios C/O (0.5, 0.96, 1 and 2). In the second set of calculations the presence of solid carbon (graphite) was taken into account and the composition of the gas system in equilibrium with solid carbon, at p = 1 atm, was determined. The results presented show that the equilibrium composition, particularly the concentration of different compounds involving the trace elements, is very sensitive to the amounts, and the ratio of the amounts of oxygen and carbon. Increasing the O/C ratio results in increasing partial pressures of molecular and atomic oxygen, which favours the formation of oxides of the trace elements and moves their atomization temperatures to higher values. On the other hand, increasing the C/O ratio (C/O >1) favours atomization, but also carbide formation in the lower-temperature region. It was found that, over a relatively wide temperature interval (1000 < T < 3500 K), the composition of the Ar/O2/C/X (X = B, Si, Ca) system, with comparable amounts of oxygen and carbon (C/O = 1), does not significantly depend on the presence of the solid phase. The results of calculations enable a reasonable interpretation of numerous experiments carried out on similar systems.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The composition of the Ar/O2/C gas system in the presence of traces of either B, Si or Ca was calculated under the assumption of thermal equilibrium in the temperature range 500-5500 K. The mole concentration of oxygen was taken to be 1-4 %. Two sets of calculations were carried out. In the first one the presence of solid phase (graphite) was ignored and the calculations were performed for a single-phase (gas) system, at variable ratios C/O (0.5, 0.96, 1 and 2). In the second set of calculations the presence of solid carbon (graphite) was taken into account and the composition of the gas system in equilibrium with solid carbon, at p = 1 atm, was determined. The results presented show that the equilibrium composition, particularly the concentration of different compounds involving the trace elements, is very sensitive to the amounts, and the ratio of the amounts of oxygen and carbon. Increasing the O/C ratio results in increasing partial pressures of molecular and atomic oxygen, which favours the formation of oxides of the trace elements and moves their atomization temperatures to higher values. On the other hand, increasing the C/O ratio (C/O >1) favours atomization, but also carbide formation in the lower-temperature region. It was found that, over a relatively wide temperature interval (1000 < T < 3500 K), the composition of the Ar/O2/C/X (X = B, Si, Ca) system, with comparable amounts of oxygen and carbon (C/O = 1), does not significantly depend on the presence of the solid phase. The results of calculations enable a reasonable interpretation of numerous experiments carried out on similar systems.
Blagojević, S; Pejič, N; Anić, S; Kolar-Anić, L
Belousov-Zhabotinsky oscillatory reaction. Kinetics of malonic acid decomposition Journal Article
In: Journal of the Serbian Chemical Society, vol. 65, no. 10, pp. 709-713, 2000.
@article{Blagojević2000709,
title = {Belousov-Zhabotinsky oscillatory reaction. Kinetics of malonic acid decomposition},
author = {S Blagojević and N Pejič and S Anić and L Kolar-Anić},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034345792&partnerID=40&md5=49942eb239e1b5782d744c9e64b9affa},
year = {2000},
date = {2000-01-01},
journal = {Journal of the Serbian Chemical Society},
volume = {65},
number = {10},
pages = {709-713},
abstract = {The kinetics of the Belousov-Zhabotinsky (BZ) oscillatory reaction was analyzed. With this aim, the time evolution of a reaction mixture composed of malonic acid, bromate, sulfuric acid and cerium(III) was studied at 298 K. Pseudo-first order kinetics with respect to malonic acid as the species undergoing decomposition with a corresponding rate constant},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The kinetics of the Belousov-Zhabotinsky (BZ) oscillatory reaction was analyzed. With this aim, the time evolution of a reaction mixture composed of malonic acid, bromate, sulfuric acid and cerium(III) was studied at 298 K. Pseudo-first order kinetics with respect to malonic acid as the species undergoing decomposition with a corresponding rate constant
Dondur, V; Marković, S; Mitrović, M; Dimitrijević, R
vol. 352, 2000.
@conference{Dondur2000105,
title = {Synthesis of Ni-spinel/aluminosilicate composite ceramics mixed at nanoscale level by using zeolite precursors},
author = {V Dondur and S Marković and M Mitrović and R Dimitrijević},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034546101&partnerID=40&md5=9463fca3bc93c6b03883013f61acd601},
year = {2000},
date = {2000-01-01},
journal = {Materials Science Forum},
volume = {352},
pages = {105-110},
abstract = {Thermally induced phase transformation of Ni-exchanged LTA, FAU, GIS and MOR zeolites were studied in the temperature range from room to 1500 °C. All investigated zeolite frameworks collapsed into amorphous intermediate products after heating between 800-900 °C. Prolonged heating of the intermediate products obtained from the Ni-exchanged zeolites over 900 °C, induces recrystallization of Ni-spinel phase (cubic-NiAl2O4) in all cases whereas silicate part recrystallizes into Ni-stuffed derivative phase of cristobalite (at Ni-GIS and Ni-MOR zeolite) or stay amorphous. Phase composition of ceramic products were studied by XRPD, SEM and IR techniques.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
Thermally induced phase transformation of Ni-exchanged LTA, FAU, GIS and MOR zeolites were studied in the temperature range from room to 1500 °C. All investigated zeolite frameworks collapsed into amorphous intermediate products after heating between 800-900 °C. Prolonged heating of the intermediate products obtained from the Ni-exchanged zeolites over 900 °C, induces recrystallization of Ni-spinel phase (cubic-NiAl2O4) in all cases whereas silicate part recrystallizes into Ni-stuffed derivative phase of cristobalite (at Ni-GIS and Ni-MOR zeolite) or stay amorphous. Phase composition of ceramic products were studied by XRPD, SEM and IR techniques.
Živković, P; Pješčić, J; Mentus, S
Corrosion behaviour of an AlZnSnSrGa alloy in aqueous solutions of NaCl and Na2SO4 Journal Article
In: Journal of the Serbian Chemical Society, vol. 65, no. 1, pp. 73-81, 2000.
@article{Živković200073,
title = {Corrosion behaviour of an AlZnSnSrGa alloy in aqueous solutions of NaCl and Na2SO4},
author = {P Živković and J Pješčić and S Mentus},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034344608&partnerID=40&md5=3179741d713e9942c688c7d0731fa779},
year = {2000},
date = {2000-01-01},
journal = {Journal of the Serbian Chemical Society},
volume = {65},
number = {1},
pages = {73-81},
abstract = {The alloy composed of Al(95.53%), Zn(2.85%), Sn(0.515%), Ga(0.1%) and Sr(0.009%), with the weight percents in the parentheses, was prepared by melting, using Al(99.84%), a product of the Aluminium Plant-Podgorica, as the base material. The corrosion behaviour of this alloy was tested in relation to the behaviour of the base metals, by both open curcuit potential and polarization resistance methods, in aqueous solutions of both NaCl and Na2SO4, the concentration of which varied within the range 0.00051-0.51 mol dm-3. Over the whole salt concentration ranges, the corrosion parameters indicate that the corrosion rate of the alloy is significantly higher than the rate of the base material. For instance, for the concentration range 0.00051-0.51 mol dm-3, the stationary open circuit potentials, related to SCE, in NaCl solutions were -1.200 to -1.460 V for the alloy and -0.693 to -0.920 V for Al, while in Na2SO4 solutions, the stationary open circuit potentials were - 1.190 to -1.465 V for the alloy and -0.780 to -0.860 V for Al. At the same time, the corrosion current density in NaCl solutions varied within 11-89 μA cm-2 for the alloy and 0.35-0.80 for Al, while in Na2SO4 solutions it amounted to 5.7-52 μA cm-2 for the alloy and 0.28 - 0.88 μ cm-2 for Al.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The alloy composed of Al(95.53%), Zn(2.85%), Sn(0.515%), Ga(0.1%) and Sr(0.009%), with the weight percents in the parentheses, was prepared by melting, using Al(99.84%), a product of the Aluminium Plant-Podgorica, as the base material. The corrosion behaviour of this alloy was tested in relation to the behaviour of the base metals, by both open curcuit potential and polarization resistance methods, in aqueous solutions of both NaCl and Na2SO4, the concentration of which varied within the range 0.00051-0.51 mol dm-3. Over the whole salt concentration ranges, the corrosion parameters indicate that the corrosion rate of the alloy is significantly higher than the rate of the base material. For instance, for the concentration range 0.00051-0.51 mol dm-3, the stationary open circuit potentials, related to SCE, in NaCl solutions were -1.200 to -1.460 V for the alloy and -0.693 to -0.920 V for Al, while in Na2SO4 solutions, the stationary open circuit potentials were - 1.190 to -1.465 V for the alloy and -0.780 to -0.860 V for Al. At the same time, the corrosion current density in NaCl solutions varied within 11-89 μA cm-2 for the alloy and 0.35-0.80 for Al, while in Na2SO4 solutions it amounted to 5.7-52 μA cm-2 for the alloy and 0.28 - 0.88 μ cm-2 for Al.
Miljanić, S S; Stjepanović, N N; Trtica, M S
An attemp to use a pulsed CO2 laser for decontamination of radioactive metal surfaces Journal Article
In: Journal of the Serbian Chemical Society, vol. 65, no. 5-6, pp. 445-450, 2000.
@article{Miljanić2000445,
title = {An attemp to use a pulsed CO2 laser for decontamination of radioactive metal surfaces},
author = {S S Miljanić and N N Stjepanović and M S Trtica},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034355246&partnerID=40&md5=14087cbc880fa123b19c90f7581951d0},
year = {2000},
date = {2000-01-01},
journal = {Journal of the Serbian Chemical Society},
volume = {65},
number = {5-6},
pages = {445-450},
abstract = {There is a growing interest in laser radioactive decontamination of metal surfaces. It offers advantages over conventional methods: improved safety, reduction of secondary waste, reduced waste volume, acceptable cost. The main mechanism of cleaning by lasers is ablation. A pulsed TEA CO2 laser was used in this work for surface cleaning in order to show that ablation of metal surfaces is possible even at relatively low pulse energies, and to suggest that it could be competitive with other lasers because of much higher energy efficiencies. A brief theoretical analysis was made before the experiments. The laser beam was focused using a KBr-lens onto a surface contaminated with 137Cs (β-, t1/2 = 30.17 y). Three different metals were used: stainless steel, copper and aluminium. The ablated material was pumped out in an air atmosphere and transferred to a filter. The presence of activity on the filter was shown by a germanium detector-multichannel analyzer. The activity levels were measured by a GM counter. The calculated decontamination factors and collection factors showed that ablation occurs with a relatively high efficiency of decontamination. This investigation suggests that decontamination using a CO2 laser should be seriously considered.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
There is a growing interest in laser radioactive decontamination of metal surfaces. It offers advantages over conventional methods: improved safety, reduction of secondary waste, reduced waste volume, acceptable cost. The main mechanism of cleaning by lasers is ablation. A pulsed TEA CO2 laser was used in this work for surface cleaning in order to show that ablation of metal surfaces is possible even at relatively low pulse energies, and to suggest that it could be competitive with other lasers because of much higher energy efficiencies. A brief theoretical analysis was made before the experiments. The laser beam was focused using a KBr-lens onto a surface contaminated with 137Cs (β-, t1/2 = 30.17 y). Three different metals were used: stainless steel, copper and aluminium. The ablated material was pumped out in an air atmosphere and transferred to a filter. The presence of activity on the filter was shown by a germanium detector-multichannel analyzer. The activity levels were measured by a GM counter. The calculated decontamination factors and collection factors showed that ablation occurs with a relatively high efficiency of decontamination. This investigation suggests that decontamination using a CO2 laser should be seriously considered.
Vukojević, V; Anić, S; Kolar-Anić, L
Investigation of dynamic behavior of the bray-liebhafsky reaction in the CSTR. Determination of bifurcation points Journal Article
In: Journal of Physical Chemistry A, vol. 104, no. 46, pp. 10731-10739, 2000.
@article{Vukojević200010731,
title = {Investigation of dynamic behavior of the bray-liebhafsky reaction in the CSTR. Determination of bifurcation points},
author = {V Vukojević and S Anić and L Kolar-Anić},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034319627&doi=10.1021%2fjp001165x&partnerID=40&md5=d327f07efe72f6c8f211e9aa34ce6a23},
doi = {10.1021/jp001165x},
year = {2000},
date = {2000-01-01},
journal = {Journal of Physical Chemistry A},
volume = {104},
number = {46},
pages = {10731-10739},
abstract = {Experimental results obtained by operating the Bray-Liebhafsky (BL) reaction in the CSTR are presented. The dynamic behavior of the BL reaction is examined at several operation points in the concentration phase space, by varying different parameters, the specific flow rate, temperature, and mixed inflow concentrations of the feed species, one at a time. Different types of bifurcation leading to simple periodic orbits, supercritical and subcritical Hopf bifurcations, saddle node infinite period bifurcation (SNIPER), saddle loop infinite period bifurcation, and jug handle bifurcation, are observed. Moreover, complex dynamic behavior, including transition from simple periodic oscillations to complex mixed-mode oscillations and chaos, and bistability are also discovered. © 2000 American Chemical Society.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Experimental results obtained by operating the Bray-Liebhafsky (BL) reaction in the CSTR are presented. The dynamic behavior of the BL reaction is examined at several operation points in the concentration phase space, by varying different parameters, the specific flow rate, temperature, and mixed inflow concentrations of the feed species, one at a time. Different types of bifurcation leading to simple periodic orbits, supercritical and subcritical Hopf bifurcations, saddle node infinite period bifurcation (SNIPER), saddle loop infinite period bifurcation, and jug handle bifurcation, are observed. Moreover, complex dynamic behavior, including transition from simple periodic oscillations to complex mixed-mode oscillations and chaos, and bistability are also discovered. © 2000 American Chemical Society.
Mićić, M; Jeremić, M; Radotić, K; Leblanc, R M
In: Journal of Colloid and Interface Science, vol. 231, no. 1, pp. 190-194, 2000.
@article{Mićić2000190,
title = {A comparative study of enzymatically and photochemically polymerized artificial lignin supramolecular structures using environmental scanning electron microscopy},
author = {M Mićić and M Jeremić and K Radotić and R M Leblanc},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034332642&doi=10.1006%2fjcis.2000.7136&partnerID=40&md5=c9db28861457411023eb1578d6d0ed8c},
doi = {10.1006/jcis.2000.7136},
year = {2000},
date = {2000-01-01},
journal = {Journal of Colloid and Interface Science},
volume = {231},
number = {1},
pages = {190-194},
abstract = {Environmental scanning electron microscopy images of the self-assembled structures of enzymatically (DHP) and photochemically polymerized (PCP) artificial lignin are herein presented. Differences in the structural organization between DHP and PCP polymer at the supramolecular level were reported. Based on topological information, we proposed a hypothesis about possible new physiological roles of lignin in live plant cells and the ecological significance of possible in-vivo photochemical lignin polymerization. (C) 2000 Academic Press.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Environmental scanning electron microscopy images of the self-assembled structures of enzymatically (DHP) and photochemically polymerized (PCP) artificial lignin are herein presented. Differences in the structural organization between DHP and PCP polymer at the supramolecular level were reported. Based on topological information, we proposed a hypothesis about possible new physiological roles of lignin in live plant cells and the ecological significance of possible in-vivo photochemical lignin polymerization. (C) 2000 Academic Press.
Pavlović, M S; Kuzmanović, M M; Pavelkić, V M; Marinković, M
The role of demixing effect in analyte emission enhancement by easily ionized elements in d.c. plasma Journal Article
In: Spectrochimica Acta - Part B Atomic Spectroscopy, vol. 55, no. 8, pp. 1373-1384, 2000.
@article{Pavlović20001373,
title = {The role of demixing effect in analyte emission enhancement by easily ionized elements in d.c. plasma},
author = {M S Pavlović and M M Kuzmanović and V M Pavelkić and M Marinković},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034245715&doi=10.1016%2fS0584-8547%2800%2900242-1&partnerID=40&md5=58f46c2c7457eb85a61183bf19a18318},
doi = {10.1016/S0584-8547(00)00242-1},
year = {2000},
date = {2000-01-01},
journal = {Spectrochimica Acta - Part B Atomic Spectroscopy},
volume = {55},
number = {8},
pages = {1373-1384},
abstract = {The effect of easily ionized elements (EIE) in d.c. plasma (DCP) has been modeled and experimentally investigated. The introduction of the EIEs in the U-shaped DCP decreases a 'potential barrier' due to an internal radial electric field, which allows the partially ionized analyte better entry into the hot plasma zone and produces enhancement of the analyte spectral emission. Compared to the equilibrium concentration, the increased electron concentration in the fringe region due to large radial gradients is accounted for in the model. By comparing model predictions to experimental data, the validity of the model is tested. The main features of the effect, the large enhancement at small addition of EIE and almost equal enhancement of ion and atom line intensities, are fairly well described by the model. The results are believed to be applicable to the inverted Y-shaped DCP. The effect in the inductively coupled plasma (ICP) has been briefly discussed from the point of view of the proposed model. © 2000 Elsevier Science B.V. All rights reserved.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The effect of easily ionized elements (EIE) in d.c. plasma (DCP) has been modeled and experimentally investigated. The introduction of the EIEs in the U-shaped DCP decreases a 'potential barrier' due to an internal radial electric field, which allows the partially ionized analyte better entry into the hot plasma zone and produces enhancement of the analyte spectral emission. Compared to the equilibrium concentration, the increased electron concentration in the fringe region due to large radial gradients is accounted for in the model. By comparing model predictions to experimental data, the validity of the model is tested. The main features of the effect, the large enhancement at small addition of EIE and almost equal enhancement of ion and atom line intensities, are fairly well described by the model. The results are believed to be applicable to the inverted Y-shaped DCP. The effect in the inductively coupled plasma (ICP) has been briefly discussed from the point of view of the proposed model. © 2000 Elsevier Science B.V. All rights reserved.
Mioč, U B; Marković, J M Dimitrić; Baranac, J M
A study of the IR spectra of copigments formed by malvin chloride with flavones Journal Article
In: Journal of the Serbian Chemical Society, vol. 65, no. 4, pp. 245-253, 2000.
@article{Mioč2000245,
title = {A study of the IR spectra of copigments formed by malvin chloride with flavones},
author = {U B Mioč and J M Dimitrić Marković and J M Baranac},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034396355&partnerID=40&md5=b2900820101c119784a1381f3e8409d7},
year = {2000},
date = {2000-01-01},
journal = {Journal of the Serbian Chemical Society},
volume = {65},
number = {4},
pages = {245-253},
abstract = {Research into the essence of the process of copigmentation of anthocyan molecules was continued by applying IR spectroscopy, in an attempt to elucidate the formation mechanism of copigment molecules between malvin chloride and several variously substituted flavones. Analysis of the IR spectra of the formed copigments revealed that the process of copigmentation is achieved via the formation of hydrogen bonds. The strength of the formed hydrogen bonds was correlated with the equilibrium constants of the processes of copigmentation of these molecules. The found correlation was in accordance with the supposed mechanism of the copigmentation reaction.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Research into the essence of the process of copigmentation of anthocyan molecules was continued by applying IR spectroscopy, in an attempt to elucidate the formation mechanism of copigment molecules between malvin chloride and several variously substituted flavones. Analysis of the IR spectra of the formed copigments revealed that the process of copigmentation is achieved via the formation of hydrogen bonds. The strength of the formed hydrogen bonds was correlated with the equilibrium constants of the processes of copigmentation of these molecules. The found correlation was in accordance with the supposed mechanism of the copigmentation reaction.
Petković, J; Mladenović, I; Vukelić, N; Mojović, M; Bačić, G
Lanthanide doped alkaline metal sulphates as candidates for EPR dosimetry Journal Article
In: Journal of the Serbian Chemical Society, vol. 65, no. 10, pp. 743-754, 2000.
@article{Petković2000743,
title = {Lanthanide doped alkaline metal sulphates as candidates for EPR dosimetry},
author = {J Petković and I Mladenović and N Vukelić and M Mojović and G Bačić},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034345791&partnerID=40&md5=219016ccd4976028a647e58a380331b4},
year = {2000},
date = {2000-01-01},
journal = {Journal of the Serbian Chemical Society},
volume = {65},
number = {10},
pages = {743-754},
abstract = {The applicability of lanthanide doped alkaline metal sulphates as a new type of dosimeters for EPR dosimetery of ionizing radiation has been investigated in an attempt to obtain a dosimeter with better characteristics than the commonly used alanine dosimeter. Irradiation of samples doped with different lanthanides (Y, Ln, Gd) showed that the best sensitivity is obtained using dosimeters doped with Y 2 (SO 4 ) 3 . Different procedures for manufacturing dosimeters were studied and an optimum procedure was established. The time stability of the EPR signal of the irradiated Y 2 (SO 4 ) 3 dosimeter was investigated using a 15 N-PDT standard and no fading of the EPR signal was observed over at least two weeks. The dose dependence of alanine and Y 2 (SO 4 ) 3 doped K 3 Na(SO 4 ) 2 dosimeters irradiated in the range 20 Gy - 200 kGy was analysed using a combination of 1-hit and 2-hit mechanisms of free radicals creation.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The applicability of lanthanide doped alkaline metal sulphates as a new type of dosimeters for EPR dosimetery of ionizing radiation has been investigated in an attempt to obtain a dosimeter with better characteristics than the commonly used alanine dosimeter. Irradiation of samples doped with different lanthanides (Y, Ln, Gd) showed that the best sensitivity is obtained using dosimeters doped with Y 2 (SO 4 ) 3 . Different procedures for manufacturing dosimeters were studied and an optimum procedure was established. The time stability of the EPR signal of the irradiated Y 2 (SO 4 ) 3 dosimeter was investigated using a 15 N-PDT standard and no fading of the EPR signal was observed over at least two weeks. The dose dependence of alanine and Y 2 (SO 4 ) 3 doped K 3 Na(SO 4 ) 2 dosimeters irradiated in the range 20 Gy - 200 kGy was analysed using a combination of 1-hit and 2-hit mechanisms of free radicals creation.
Petranović, N; Minić, D; Sabo, T J; Doković, D
Kinetic and thermodynamic studies of facial and meridional uns-cis-[Co(eddp)gly] complexes Journal Article
In: Journal of Thermal Analysis and Calorimetry, vol. 59, no. 3, pp. 807-814, 2000.
@article{Petranović2000807,
title = {Kinetic and thermodynamic studies of facial and meridional uns-cis-[Co(eddp)gly] complexes},
author = {N Petranović and D Minić and T J Sabo and D Doković},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0033748798&partnerID=40&md5=c0a835661c228b1dec521d48be94b05c},
year = {2000},
date = {2000-01-01},
journal = {Journal of Thermal Analysis and Calorimetry},
volume = {59},
number = {3},
pages = {807-814},
abstract = {Thermal properties of facial and meridional uns-cis-[Co(eddp)gly]·0.5H2O complexes were investigated by means of DSC and TG techniques. It was shown that the processes of thermal decomposition of these complexes are multi-step degradation processes, which can also be well separated into individual steps, depending on the molecular symmetry. Thus, the process of thermal degradation of the meridional isomer of the above complex consists of 4 well-separated steps in the temperature interval from 100 to 500°C. The corresponding kinetic and thermodynamic parameters of this process were determined, and a possible mechanism is discussed.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Thermal properties of facial and meridional uns-cis-[Co(eddp)gly]·0.5H2O complexes were investigated by means of DSC and TG techniques. It was shown that the processes of thermal decomposition of these complexes are multi-step degradation processes, which can also be well separated into individual steps, depending on the molecular symmetry. Thus, the process of thermal degradation of the meridional isomer of the above complex consists of 4 well-separated steps in the temperature interval from 100 to 500°C. The corresponding kinetic and thermodynamic parameters of this process were determined, and a possible mechanism is discussed.
Kuntić, V; Malešev, D; Radović, Z; Vukojević, V
Spectrophotometric investigation of the complexing reaction between rutin and titanyloxalate anion in 50% ethanol Journal Article
In: Monatshefte fur Chemie, vol. 131, no. 7, pp. 769-777, 2000.
@article{Kuntić2000769,
title = {Spectrophotometric investigation of the complexing reaction between rutin and titanyloxalate anion in 50% ethanol},
author = {V Kuntić and D Malešev and Z Radović and V Vukojević},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0008626740&doi=10.1007%2fs007060050024&partnerID=40&md5=cc9535955abb0cae8040dbd0a1229660},
doi = {10.1007/s007060050024},
year = {2000},
date = {2000-01-01},
journal = {Monatshefte fur Chemie},
volume = {131},
number = {7},
pages = {769-777},
abstract = {In the present work, rutin (3,3′,4′,5,7-pentahydrohyflavone-3-rhamnoglucoside) was determinated via a complexing reaction with a titanyloxalate anion. K2(TiO(C2O4)2] and rutin react in 50% ethanol forming a 1:2 complex in a pH range from 4.00 to 11.50, in which the TiO(C2O4)2-2 ion is linked to rutin through the 4-carbonyl and 5-hydroxyl group. The thermodynamic stability constant log β02 of the complex is determined to 10.80 at pH = 6.50. The change of the standard Gibbs free energy ΔG0 amounts to -61 kJ · mol-1, indicating that the process of complex formation is spontaneous. The optimal conditions for the spectrophotometric determination of microconcentrations of rutin are at pH = 6.40 and λ = 430 nm, where the complex shows an absorption maximum with a molar absorption coefficient a430 = (60±2) · 103 dm3 · mol-1 · cm-1. The method is applied rutin determination from tablets.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
In the present work, rutin (3,3′,4′,5,7-pentahydrohyflavone-3-rhamnoglucoside) was determinated via a complexing reaction with a titanyloxalate anion. K2(TiO(C2O4)2] and rutin react in 50% ethanol forming a 1:2 complex in a pH range from 4.00 to 11.50, in which the TiO(C2O4)2-2 ion is linked to rutin through the 4-carbonyl and 5-hydroxyl group. The thermodynamic stability constant log β02 of the complex is determined to 10.80 at pH = 6.50. The change of the standard Gibbs free energy ΔG0 amounts to -61 kJ · mol-1, indicating that the process of complex formation is spontaneous. The optimal conditions for the spectrophotometric determination of microconcentrations of rutin are at pH = 6.40 and λ = 430 nm, where the complex shows an absorption maximum with a molar absorption coefficient a430 = (60±2) · 103 dm3 · mol-1 · cm-1. The method is applied rutin determination from tablets.
Mioč, U B; Todorović, M R; Uskoković-Marković, S M; Nedić, Z P; Bošnjaković, N S
A spectroscopic investigation of 12-tungstophosphoric acid alkali salts Journal Article
In: Journal of the Serbian Chemical Society, vol. 65, no. 5-6, pp. 399-406, 2000.
@article{Mioč2000399,
title = {A spectroscopic investigation of 12-tungstophosphoric acid alkali salts},
author = {U B Mioč and M R Todorović and S M Uskoković-Marković and Z P Nedić and N S Bošnjaković},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034360716&partnerID=40&md5=6b306e2be7e8f0b4af729f9210ea32c7},
year = {2000},
date = {2000-01-01},
journal = {Journal of the Serbian Chemical Society},
volume = {65},
number = {5-6},
pages = {399-406},
abstract = {In this paper the latest results of our continuing investigation of heteropoly acids and their salts are reported. Specially attention was paid to the influence of cations on the dynamic equilibrium of protonic species, as well as on the structure of the host lattice itself, i.e., the Keggin anions. The investigations were done by IR and Raman spectroscopy within the range of 1200-40 cm -1 .},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
In this paper the latest results of our continuing investigation of heteropoly acids and their salts are reported. Specially attention was paid to the influence of cations on the dynamic equilibrium of protonic species, as well as on the structure of the host lattice itself, i.e., the Keggin anions. The investigations were done by IR and Raman spectroscopy within the range of 1200-40 cm -1 .
Bogunović, L J; Mioč, U B; Jovanović, B Ž; Juranić, I O
Infrared study of some 2-substituted-6-hydroxy-4-pyrimidine carboxylic acids. Correlation with MO-calculations Journal Article
In: Journal of the Serbian Chemical Society, vol. 65, no. 5-6, pp. 371-379, 2000.
@article{Bogunović2000371,
title = {Infrared study of some 2-substituted-6-hydroxy-4-pyrimidine carboxylic acids. Correlation with MO-calculations},
author = {L J Bogunović and U B Mioč and B Ž Jovanović and I O Juranić},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034363411&partnerID=40&md5=3f56af5189ee9f5b648138924f99728e},
year = {2000},
date = {2000-01-01},
journal = {Journal of the Serbian Chemical Society},
volume = {65},
number = {5-6},
pages = {371-379},
abstract = {The IR spectra of a series of 2-substituted-6-hydroxy-4-pyrimidine carboxylic acids (substituent = OH, SH, CH 3 , CH 3 S and NH 2 ) were studied from the aspect of the influence of the subsitutent on the polarizability of some bonds, keto-enol tautomerism and hydrogen bond formation. The spectra were taken using solids due to the low solubility of the acids. Theoretical calculations were done using the MNDO-AM1 semiempirical molecular-orbital method. The stabilities of various tautomers were calculated simulating the dielectric continuum using the COSMO facility of the MOPAC program package. Theoretical calculations were made for all the possible tautomers of the 2-substituted-6-hydroxy-4-pyrimidine carboxylic acids. For the most stable isomers, the vibrational spectra were calculated. For the majority of the compounds the most stable isomer was identified having the structure 2-Y-6-oxo-4-carboxy-3H-pyrimidine. Besides this structure, for the 2-amino-, and 2-methyl-derivatives the zwitterionic forms have very similar stability. The 2-hydroxy compound is most stable as the 2,6-dioxo-1H, 3H isomer. The calculated vibrations for the compounds with a single stable structure correlate very well with the experimental frequencies. For the 2-methyl- and 2-amino-compounds the correlation is considerably less satisfactory. The most probable reason for this deviation is the existence of two or more tautomets in equilibrium. The correlation of the measured frequencies and the pK a values of the acids, indicate that the same tautomers exist in the solid state and in the solution.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The IR spectra of a series of 2-substituted-6-hydroxy-4-pyrimidine carboxylic acids (substituent = OH, SH, CH 3 , CH 3 S and NH 2 ) were studied from the aspect of the influence of the subsitutent on the polarizability of some bonds, keto-enol tautomerism and hydrogen bond formation. The spectra were taken using solids due to the low solubility of the acids. Theoretical calculations were done using the MNDO-AM1 semiempirical molecular-orbital method. The stabilities of various tautomers were calculated simulating the dielectric continuum using the COSMO facility of the MOPAC program package. Theoretical calculations were made for all the possible tautomers of the 2-substituted-6-hydroxy-4-pyrimidine carboxylic acids. For the most stable isomers, the vibrational spectra were calculated. For the majority of the compounds the most stable isomer was identified having the structure 2-Y-6-oxo-4-carboxy-3H-pyrimidine. Besides this structure, for the 2-amino-, and 2-methyl-derivatives the zwitterionic forms have very similar stability. The 2-hydroxy compound is most stable as the 2,6-dioxo-1H, 3H isomer. The calculated vibrations for the compounds with a single stable structure correlate very well with the experimental frequencies. For the 2-methyl- and 2-amino-compounds the correlation is considerably less satisfactory. The most probable reason for this deviation is the existence of two or more tautomets in equilibrium. The correlation of the measured frequencies and the pK a values of the acids, indicate that the same tautomers exist in the solid state and in the solution.