Vitaly Nagy - Academia.edu (original) (raw)
Papers by Vitaly Nagy
Journal of the Chemical Society, 1991
Acidic properties of several compounds with aminoxyl-based spin labels were found to be abnormall... more Acidic properties of several compounds with aminoxyl-based spin labels were found to be abnormally strong when compared with those of diamagnetic analogues. Analysis of this phenomenon in terms of both Taft constants and Hinze–Jaffe–Huheey group electronegativities enabled us to attribute it to the strong electron-acceptor effect of the aminoxyl group that results in high electronegativity of aminoxyl-containing substituents. Quantitative estimates of this effect for two spin labels were obtained. Group electronegativity of imidazoline-based spin label is close to that of the -CF3 substituent, while the electron-acceptor effect of piperidine-based spin label is intermediate between those of -CHF2 and -CH2F groups. The strong electron-acceptor effect of aminoxyl spin labels should be taken into account when using them in biological and other studies.
Analytica Chimica Acta, Jul 1, 1981
Solvent Extraction and Ion Exchange, 1997
ABSTRACT It is demonstrated that the electronegativity of metals extracted in the form of diethyl... more ABSTRACT It is demonstrated that the electronegativity of metals extracted in the form of diethyldithiocarbamates affects the extraction constants in two ways, namely, through its influence on the chelate stability and the partition constants. The corresponding interrelations can be used to predict extraction constants from any of the following three characteristics: the Klopman electronegativity of the metal, the chelate partition constant, or the chelate stability constant.
CRC critical reviews in analytical chemistry, 1987
... USSR Oleg M. Petrukhin DI Mendeleev Institute of Chemical Technology Moscow, USSR; and Analyt... more ... USSR Oleg M. Petrukhin DI Mendeleev Institute of Chemical Technology Moscow, USSR; and Analytical Department VI Vernadskii Institute of Geochemistry and Analytical Chemistry USSR Academy of Sciences Moscow, USSR ...
Analytica Chimica Acta, Feb 1, 1997
Fresenius Journal of Analytical Chemistry, Dec 1, 1992
Summary. A method is proposed for the elimination of the systematic errors of quantitative electr... more Summary. A method is proposed for the elimination of the systematic errors of quantitative electron paramagnetic resonance (EPR) spectrometric analysis resulting from the nonuniformity of microwave and modulation fields in the resonator. The errors are especially significant by a non-destructive analysis of solids when the samples are large and the sample to be analyzed differs from the reference one in shape and size. The method involves preliminary experimental characterization of the real configuration of the fields in a specific resonator on the basis of the set of signals recorded by approximately 500 different positions of a tiny sample in the resonator. The dependence of intensity of the 'point' sample signal on the sample coordinates can be expressed by an analytical function, and the correction factor can be obtained by means of integration of this function over the shapes of the two samples. In most cases the method enables an analyst to reduce the values of the systematic errors mentioned down to the level typical for random errors. The analytical description of the configuration of intraresonator fields is also beneficial for the solution of various methodological problems.
Trends in Analytical Chemistry, Jun 1, 1983
Analytica Chimica Acta, 1986
... BREZHNEV and PV KOVTUNENKO Mendeleev Institute of Chemical Technology, 125820 Moscow (USSR) (... more ... BREZHNEV and PV KOVTUNENKO Mendeleev Institute of Chemical Technology, 125820 Moscow (USSR) (Received 15th August 1985) SUMMARY A rapid (12 min) nondestructive method based on electron spin resonance is described for the determination of manganese in ...
Analytica Chimica Acta, Feb 1, 1997
Solvent Extraction and Ion Exchange, Aug 1, 1997
ABSTRACT Predicting the effectiveness of liquid-liquid extraction of metal chelates and choosing ... more ABSTRACT Predicting the effectiveness of liquid-liquid extraction of metal chelates and choosing optimal extraction reagents requires several characteristics of the components of the extraction system to be taken into consideration. This paper provides an analysis of the factors that affect the value of the partition constant of a chelate and the possibilities to predict the value of the partition constant from the nature of the metal ion, the structure of the chelating reagent, and the organogenic elements, one might have expected these techniques to be capable to predict the partition constants of chelates as well. However, the problem of determining the increments of metals turned out to be very difficult even in the case of relatively simple complexes. An analysis of the partition constants of coordinatively-saturated metal acetylacetonates has shown that the values depend on a large number of parameters, some of which are correlated. The central metal atom modifies the donor properties of the heteroa...
Applied Magnetic Resonance, Feb 1, 1994
Many of the errors in EPR concentration measurements result from the inability of an analyst to u... more Many of the errors in EPR concentration measurements result from the inability of an analyst to use the reference sample that is identical to the sample to be analyzed in a number of substantial respects. Generally, it is not correct to compare directly the intensities of the signals from two samples that contain different paramagnetic centers, or are different in
Applied Radiation and Isotopes, Aug 1, 1996
... relative amplitude at the first minimum was taken to be 1.000 792 Vitaly Yu. Nagy and Marc F.... more ... relative amplitude at the first minimum was taken to be 1.000 792 Vitaly Yu. Nagy and Marc F. Desrosiers 22650 Alanine ~ 22550 422500 ~ 22450 .m ~ 22400 22350 II i ~ i I 50 100 1 0 200 Time after irradiation, h 24800 ~ 24700 i24600 ~.24500 E < 24400 Ruby io '1oo 26o ...
Analytica Chimica Acta, Feb 1, 1997
Critical Reviews in Analytical Chemistry, 1987
Analyst, 1990
Chelating reagents whose molecules contain both a luminescent fragment and a spin label near a ch... more Chelating reagents whose molecules contain both a luminescent fragment and a spin label near a chelating group are suggested for use in the spectrofluorimetric determination of metal ions. In solutions of such reagents, considerable intramolecular quenching of the fluorescence of the luminescent fragment by the adjacent paramagnetic spin label was observed. The proposed method is based on the change in the degree of luminescence quenching resulting from the alteration of the conformation of the reagent molecule during chelation and a consequent change in the distance between the luminescent group and the spin label. Measurement of the change in the fluorescence intensity of the reagent solution by addition of the metal ions to be determined makes it possible to achieve detection limits of 10–9M.
Medical Physics, Jun 1, 2011
Purpose: To demonstrate the suitability of the use of alanine dosimeters as a supplement or alter... more Purpose: To demonstrate the suitability of the use of alanine dosimeters as a supplement or alternative to TG51 as an acceptable secondary calibration method for high energy photons beams from a medicallinear accelerator. Methods: Alanine dosimiters were irradiated at three radiation treatment facilities and compared to dose/mu determined by TG51 using ionization chambers calibrated at ADCL. The ionization chamber was positioned in a Scanditronix Wellhoffer water phantom with dimensions 42 cm × 36 cm × 36 cm and at a dept of 5.0 cm. The volume of the ionization chamber was 0.6 cc. A polystyrene holder containing two alanine dosimeters was placed at the same point. Each alanine dosimeter is cylindrical in shape with a diameter of 5 mm and a length of 3 mm (volume = 0.25 cc). Ten sets of alanine detectors (20) were irradiated to 20 Gy in sequential exposures. An independent ionization chamber was used to normalize the exposures for any variation in accelerator output for every measurement. For one beam energy the alanine detectors were returned to a national standards laboratory for conversion to dose based on the same primary standard used for ionization chambers. The remaining dosimeters was evaluated on a Bruker EMX EPR spectrometer at the Armed Forces Radiobiology Research Institute which is directly traceable to NIST based on calibrated alanine dosimeters. Results: The average normalized dose per mu for all data is within expected experimental uncertainty. The uncertainty of each measurement technique is believed to be approximately 2% and will be discussed in detail. Conclusion: Analysis of the intercomparison measurements establishes that the alanine dosimeters are a valid method to establish the dose per mu for a medicallinear accelerator that is traceable to the primary standard at a national standards laboratory in the same manner as used in TG51.
Mikrochimica Acta, May 1, 1985
Radiation Physics and Chemistry, 2000
Radiation Physics and Chemistry, Mar 1, 2002
Journal of the Chemical Society, 1991
Acidic properties of several compounds with aminoxyl-based spin labels were found to be abnormall... more Acidic properties of several compounds with aminoxyl-based spin labels were found to be abnormally strong when compared with those of diamagnetic analogues. Analysis of this phenomenon in terms of both Taft constants and Hinze–Jaffe–Huheey group electronegativities enabled us to attribute it to the strong electron-acceptor effect of the aminoxyl group that results in high electronegativity of aminoxyl-containing substituents. Quantitative estimates of this effect for two spin labels were obtained. Group electronegativity of imidazoline-based spin label is close to that of the -CF3 substituent, while the electron-acceptor effect of piperidine-based spin label is intermediate between those of -CHF2 and -CH2F groups. The strong electron-acceptor effect of aminoxyl spin labels should be taken into account when using them in biological and other studies.
Analytica Chimica Acta, Jul 1, 1981
Solvent Extraction and Ion Exchange, 1997
ABSTRACT It is demonstrated that the electronegativity of metals extracted in the form of diethyl... more ABSTRACT It is demonstrated that the electronegativity of metals extracted in the form of diethyldithiocarbamates affects the extraction constants in two ways, namely, through its influence on the chelate stability and the partition constants. The corresponding interrelations can be used to predict extraction constants from any of the following three characteristics: the Klopman electronegativity of the metal, the chelate partition constant, or the chelate stability constant.
CRC critical reviews in analytical chemistry, 1987
... USSR Oleg M. Petrukhin DI Mendeleev Institute of Chemical Technology Moscow, USSR; and Analyt... more ... USSR Oleg M. Petrukhin DI Mendeleev Institute of Chemical Technology Moscow, USSR; and Analytical Department VI Vernadskii Institute of Geochemistry and Analytical Chemistry USSR Academy of Sciences Moscow, USSR ...
Analytica Chimica Acta, Feb 1, 1997
Fresenius Journal of Analytical Chemistry, Dec 1, 1992
Summary. A method is proposed for the elimination of the systematic errors of quantitative electr... more Summary. A method is proposed for the elimination of the systematic errors of quantitative electron paramagnetic resonance (EPR) spectrometric analysis resulting from the nonuniformity of microwave and modulation fields in the resonator. The errors are especially significant by a non-destructive analysis of solids when the samples are large and the sample to be analyzed differs from the reference one in shape and size. The method involves preliminary experimental characterization of the real configuration of the fields in a specific resonator on the basis of the set of signals recorded by approximately 500 different positions of a tiny sample in the resonator. The dependence of intensity of the 'point' sample signal on the sample coordinates can be expressed by an analytical function, and the correction factor can be obtained by means of integration of this function over the shapes of the two samples. In most cases the method enables an analyst to reduce the values of the systematic errors mentioned down to the level typical for random errors. The analytical description of the configuration of intraresonator fields is also beneficial for the solution of various methodological problems.
Trends in Analytical Chemistry, Jun 1, 1983
Analytica Chimica Acta, 1986
... BREZHNEV and PV KOVTUNENKO Mendeleev Institute of Chemical Technology, 125820 Moscow (USSR) (... more ... BREZHNEV and PV KOVTUNENKO Mendeleev Institute of Chemical Technology, 125820 Moscow (USSR) (Received 15th August 1985) SUMMARY A rapid (12 min) nondestructive method based on electron spin resonance is described for the determination of manganese in ...
Analytica Chimica Acta, Feb 1, 1997
Solvent Extraction and Ion Exchange, Aug 1, 1997
ABSTRACT Predicting the effectiveness of liquid-liquid extraction of metal chelates and choosing ... more ABSTRACT Predicting the effectiveness of liquid-liquid extraction of metal chelates and choosing optimal extraction reagents requires several characteristics of the components of the extraction system to be taken into consideration. This paper provides an analysis of the factors that affect the value of the partition constant of a chelate and the possibilities to predict the value of the partition constant from the nature of the metal ion, the structure of the chelating reagent, and the organogenic elements, one might have expected these techniques to be capable to predict the partition constants of chelates as well. However, the problem of determining the increments of metals turned out to be very difficult even in the case of relatively simple complexes. An analysis of the partition constants of coordinatively-saturated metal acetylacetonates has shown that the values depend on a large number of parameters, some of which are correlated. The central metal atom modifies the donor properties of the heteroa...
Applied Magnetic Resonance, Feb 1, 1994
Many of the errors in EPR concentration measurements result from the inability of an analyst to u... more Many of the errors in EPR concentration measurements result from the inability of an analyst to use the reference sample that is identical to the sample to be analyzed in a number of substantial respects. Generally, it is not correct to compare directly the intensities of the signals from two samples that contain different paramagnetic centers, or are different in
Applied Radiation and Isotopes, Aug 1, 1996
... relative amplitude at the first minimum was taken to be 1.000 792 Vitaly Yu. Nagy and Marc F.... more ... relative amplitude at the first minimum was taken to be 1.000 792 Vitaly Yu. Nagy and Marc F. Desrosiers 22650 Alanine ~ 22550 422500 ~ 22450 .m ~ 22400 22350 II i ~ i I 50 100 1 0 200 Time after irradiation, h 24800 ~ 24700 i24600 ~.24500 E < 24400 Ruby io '1oo 26o ...
Analytica Chimica Acta, Feb 1, 1997
Critical Reviews in Analytical Chemistry, 1987
Analyst, 1990
Chelating reagents whose molecules contain both a luminescent fragment and a spin label near a ch... more Chelating reagents whose molecules contain both a luminescent fragment and a spin label near a chelating group are suggested for use in the spectrofluorimetric determination of metal ions. In solutions of such reagents, considerable intramolecular quenching of the fluorescence of the luminescent fragment by the adjacent paramagnetic spin label was observed. The proposed method is based on the change in the degree of luminescence quenching resulting from the alteration of the conformation of the reagent molecule during chelation and a consequent change in the distance between the luminescent group and the spin label. Measurement of the change in the fluorescence intensity of the reagent solution by addition of the metal ions to be determined makes it possible to achieve detection limits of 10–9M.
Medical Physics, Jun 1, 2011
Purpose: To demonstrate the suitability of the use of alanine dosimeters as a supplement or alter... more Purpose: To demonstrate the suitability of the use of alanine dosimeters as a supplement or alternative to TG51 as an acceptable secondary calibration method for high energy photons beams from a medicallinear accelerator. Methods: Alanine dosimiters were irradiated at three radiation treatment facilities and compared to dose/mu determined by TG51 using ionization chambers calibrated at ADCL. The ionization chamber was positioned in a Scanditronix Wellhoffer water phantom with dimensions 42 cm × 36 cm × 36 cm and at a dept of 5.0 cm. The volume of the ionization chamber was 0.6 cc. A polystyrene holder containing two alanine dosimeters was placed at the same point. Each alanine dosimeter is cylindrical in shape with a diameter of 5 mm and a length of 3 mm (volume = 0.25 cc). Ten sets of alanine detectors (20) were irradiated to 20 Gy in sequential exposures. An independent ionization chamber was used to normalize the exposures for any variation in accelerator output for every measurement. For one beam energy the alanine detectors were returned to a national standards laboratory for conversion to dose based on the same primary standard used for ionization chambers. The remaining dosimeters was evaluated on a Bruker EMX EPR spectrometer at the Armed Forces Radiobiology Research Institute which is directly traceable to NIST based on calibrated alanine dosimeters. Results: The average normalized dose per mu for all data is within expected experimental uncertainty. The uncertainty of each measurement technique is believed to be approximately 2% and will be discussed in detail. Conclusion: Analysis of the intercomparison measurements establishes that the alanine dosimeters are a valid method to establish the dose per mu for a medicallinear accelerator that is traceable to the primary standard at a national standards laboratory in the same manner as used in TG51.
Mikrochimica Acta, May 1, 1985
Radiation Physics and Chemistry, 2000
Radiation Physics and Chemistry, Mar 1, 2002