John Mackie - Academia.edu (original) (raw)

Papers by John Mackie

This paper presents the results of dichloromethane (DCM) decomposition to polymers utilising diel... more This paper presents the results of dichloromethane (DCM) decomposition to polymers utilising dielectric barrier discharge under non-oxidative reaction conditions. The conversion levels, mass balance, reaction mechanism and polymer characterisation in relation to DCM reaction are presented in this paper. Reaction pathways describing the decomposition of DCM and subsequent formation of the major products are outlined. Speculation of the mechanism of formation of CHCl3 and C2HCl3 are supported by quantum chemical calculations. In addition, the effect of introducing methane in the reaction feed on the conversion level of DCM and the polymer structure is also examined in this paper.

Chromosoma, 1981

Chromatin organization and transcriptional activity in the macronucleus of the ciliate Paramecium... more Chromatin organization and transcriptional activity in the macronucleus of the ciliate Paramecium primaurelia have been studied by electron microscopic examination of spread chromatin preparations. Under spreading conditions which inhibit the activity of endogenous nucleases and proteases, various morphologically distinct types of chromatin are seen: (1) Largely condensed chromatin in the form of 30-40 nm supranucleosomal globules which aggregate to form knobbly 40-60 nm fibres and unravel into 12 nm nucleosomal filaments; (2) In rapidly growing cells, extended chromatin arranged groups of 4-8 adjacent nucleofilaments, each bearing numerous and very densely packed lateral fibrils. These fibrils are 20 nm thick, have a smooth outline and extend to lengths of up to 3 micron. Such transcripts are grouped in units along the chromatin axis and are apparently organized in register in adjacent filaments; (3) In starved cells, extended nucleofilaments bearing only occasional RNP fibrils. These various morphological characteristics are discussed in terms of macronuclear transcriptional activity and the polyploid nature of macronuclei.

J Phys Chem a, 1999

... 9, CF 3 + CF 2 = CF 3 −CF 2, 13.0, 0, 0.0, 15.4, 0, 214.5, estd. 10, CH 2 F−CF 3 = CH 2 F + C... more ... 9, CF 3 + CF 2 = CF 3 −CF 2, 13.0, 0, 0.0, 15.4, 0, 214.5, estd. 10, CH 2 F−CF 3 = CH 2 F + CF 3, 17.0, 0, 373.6, 13.6, 0, −0.3, estd. 11, CH 2 F−CF 3 = HF + CHF:CF 2, 13.4, 0, 296.2, 11.2, 0, 180.3, 4. 12, 2CH 2 F = CH 2 F−CH 2 F, 13.5, 0, 0.0, 17.3, 0, 351.4, estd. ...

Chemical Engineering Journal, 2016

Fire Safety Science, 2007

Fires provide optimum conditions to produce polychlorinated dibenzo-p-dioxins and polychlorinated... more Fires provide optimum conditions to produce polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/F) as well as polychlorinated biphenyls (PCB). In this study, we deploy the density functional theory (DFT) to simulate the production of PCB, and polychlorinated dibenzofurans (PCDF), which are formed in fires from the precursor chlorobenzene in preference to polychlorinated dibenzo-p-dioxins (PCDD). We demonstrate that, combinations of chlorobenzene with chlorophenyl radicals generate PCB compounds through an exothermic reaction of 18.7 kcal/mol. H on the pivot bond could be self-expulsed through an energy barrier of 21.7 kcal/mol to produce 2,2'dichlorobiphenyl. Combinations of chlorobenzene and chlorophenoxy radicals, formed in early stages of the oxidation of chlorobenzene, afford 16 different precursors for PCDFs. All these reactions are endothermic, between 18.3 to 38.8 kcal/mol at 298 K, with activation enthalpies higher by 3-10 kcal/mol than the reaction enthalpies.

Fire Safety Science, 2011

Several varieties of linseed oil are commercially available, and they have been used for many app... more Several varieties of linseed oil are commercially available, and they have been used for many applications especially in decorative furniture finishing and as an oil painting medium. The addition of metallic driers to the linseed oil is a common practice, as it improves the drying rate of the paint. Several cases of fires have been reported, often involving rags soaked with linseed oil which have not been disposed of properly, and it is generally agreed that metal salts in the linseed oil play an important role in the spontaneous ignition of the oil. This paper investigates several types of linseed oil sold in the market and their tendency to cause self-heating of cotton which has been impregnated with linseed oil obtained from various sources.

The Journal of organic chemistry, Jan 6, 2015

Nitrosation reactions span a diverse range of applications, from biochemistry to industrially imp... more Nitrosation reactions span a diverse range of applications, from biochemistry to industrially important processes. This study examines nitrosation of aminothiones in acidic solutions and re-evaluates currently accepted diffusion limits and the true nature of the nitrosating agent for nitrous acid initiated reactions. Experimental measurements from stopped-flow UV/vis spectrophotometry afforded derivation of equilibrium constants and reaction enthalpies. Apparent Keq corresponds to 559-382 M(-2) for thioacetamide (TA, 15-25 °C) and 12600-5590 M(-2) for thiourea (TU, 15-35 °C), whereas the reaction enthalpies amount to -27.10 ± 0.05 kJ for TA and -29.30 ± 0.05 kJ for TU. Theoretical calculations via a thermochemical cycle agree well with reaction free energies from experiments, with errors of -2-4 kJ using solvation method SMD in conjunction with hybrid meta exchange-correlation functional M05-2X and high-accuracy multistep method CBS-QB3 for gas-phase calculations. The kinetic rates ...

Fire Safety Science, 2011

ABSTRACT This study presents an investigation into the gas phase thermal decomposition of captafo... more ABSTRACT This study presents an investigation into the gas phase thermal decomposition of captafol, a sulfenimide fungicide which consists of a thiotetrachloroethyl (-SCCl 2CHCl 2) group bonded to a tetrahydrophthalimide (C 6H 8(CO) 2N-) moiety. The experiments were performed on a bench type apparatus, under conditions representing both under and well-ventilated non-flaming fires. The analyses of gaseous species relied on Fourier transform infra-red spectroscopy (FTIR) and micro gas chromatography (μGC), resulting in the identification and quantification of 11 gaseous products; among them, phosgene, thiophosgene and hydrogen cyanide. Gas chromatography - quadrupole mass spectrometry (GC-QMS) was employed to analyse the condensed products and volatile organic compounds (VOC), while a GC equipped with an ion trap mass spectrometer (GC-ITMS) was used to quantify polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F). The GC-QMS analysis determined several VOC toxicants; viz., trichloroethylene, tetrachloroethylene, benzonitrile and chlorinated benzenes. At higher temperature (600 °C), the oxidation of captafol led to the formation of mono- to hepta-CDD/F congeners including the most toxic 2,3,7,8-TCDD. In addition, the experimental results were compared to those of the other two sulfenimide fungicides, captan and folpet, both of which contain the thiotrichloromethyl (-SCCl 3) moiety rather than the thiotetrachloroethyl group of captafol. It appears that the thiotetrachloroethyl group in captafol is responsible for the difference in the toxic pollutants formed, particularly influencing the distribution and yields of PCDD/F congeners. Combined with quantum chemical calculations, the results presented in this article provide an insightful understanding of fire chemistry of the sulfenimide fungicides, especially the pathways to the formation of major toxicants during the oxidative thermal decomposition of captafol.

In this paper we study the effect of adding methane as an additive to 1,2-dichloroethane (EDC) in... more In this paper we study the effect of adding methane as an additive to 1,2-dichloroethane (EDC) in non thermal plasma treatment using a cylindrical dielectric barrier discharge (DBD) reactor to yield commercially important products. EDC is primarily used in vinyl chloride production. However, EDC is listed as a priority pollutant by the US EPA and has been identified as a human carcinogen. Hence its treatment has high significance. In contrast to majority of research on EDC, the present research is focussed on the non oxidative treatment of EDC at atmospheric pressure using a DBD to beget commercially important products such as vinyl chloride and polyvinyl chloride. The addition of CH4 reduced the concentration of structural defects, notably unsaturation in the polymer backbone chain as compared to the polymer, which was obtained from EDC treatment in absence of additives.

The reaction of HFC-134a (CF3CH2F) in an argon bath gas has been studied using a dielectric barri... more The reaction of HFC-134a (CF3CH2F) in an argon bath gas has been studied using a dielectric barrier discharge non-thermal plasma at atmospheric pressure. Oxygen and nitrogen have been excluded in the reaction. It has been found that CF3CH2F can be converted into a non-crosslinked polymer under the reaction conditions studied. Other products include CHF3, CH2F2, C2H3F, C3H3F5, H2, HF and an oligomeric product fraction. The discharge characteristics of argon diluted CF3CH2F has been discussed, which is in the transition region between filamentary and homogeneous glow. The conversion of CF3CH2F ranges from 52% to 82 % for the applied voltage range of 13.4 – 15 kV (peak-peak) and input energy density range of 2 - 12 kJ/L. A simplified reaction mechanism has been proposed. Gel permeation chromatography analysis show two fractions with top molecular weights (Mp) of 2400 and 105,000 g/mol respectively, produced at an input energy density of 8 kJ/l.

RSC Adv., 2015

ABSTRACT Nitrosation reactions and subsequent decomposition of S-nitroso (RSNO+) species remain i... more ABSTRACT Nitrosation reactions and subsequent decomposition of S-nitroso (RSNO+) species remain important in many biochemical processes as well as in industrial applications such as chemical gassing of emulsion explosives. This paper develops kinetic mechanisms of gas formation pathways in the decomposition of RSNO+ species, particularly S-nitrosothioacetamide and S-nitrosothiourea, providing new kinetic and thermodynamic constants. At pH levels of 1 and below, decomposition proceeds exclusively via NO formation pathways. With decreasing acidity, molecular nitrogen formation emerges as an equally important product of S-nitrosothiourea, while NO remains the only product for S-nitrosothioacetamide. Theoretical calculations for reaction enthalpies further elucidate the gas formation pathways and proposed mechanisms, fitted to experimental data, afford kinetic rate constants. In both species, the S–N bonds split homolytically with activation energies of 70.9 and 118 kJ mol-1 for S-nitrosothioacetamide and S-nitrosothiourea, respectively. The electron donating effect of methyl substitution in S-nitrosothioacetamide engenders lower activation energies with the bimolecular reaction of RSNO+ and RS occurring within the diffusion controlled regime at an activation energy of 17.6 kJ mol-1. For S-nitrosothiourea, a further bimolecular reaction of two RSNO+ molecules occurs irreversibly with an activation energy of 84.4 kJ mol-1.

Proceedings of the Sixth International Seminar on Fire and Explosion Hazards, 2011

ABSTRACT This paper examines the effect of methane on the reaction of 1, 2-dichloroethane in a no... more ABSTRACT This paper examines the effect of methane on the reaction of 1, 2-dichloroethane in a non-thermal plasma in a double dielectric barrier discharge (DBD) reactor, under non oxidative conditions and at atmospheric pressure. Commercially important products such as vinyl chloride and polyvinyl chloride were produced. The addition of CH4 to the feed stream reduces the concentration of unsaturation in the polymeric material.

Journal of Molecular Structure: THEOCHEM, 2010

... 1 A DFT Study on the Self-Coupling Reactions of the Three Isomeric Semiquinone Radicals Abdal... more ... 1 A DFT Study on the Self-Coupling Reactions of the Three Isomeric Semiquinone Radicals Abdallah Alsoufi1, Mohammednoor Altarawneh1, Bogdan Z. Dlugogorski2*, Eric M. Kennedy2 and John C. Mackie2* 1Chemical ... [15] R. Asatryan, A. Davtyan, L. Khachatryan, B ...

This paper presents the results of dichloromethane (DCM) decomposition to polymers utilising diel... more This paper presents the results of dichloromethane (DCM) decomposition to polymers utilising dielectric barrier discharge under non-oxidative reaction conditions. The conversion levels, mass balance, reaction mechanism and polymer characterisation in relation to DCM reaction are presented in this paper. Reaction pathways describing the decomposition of DCM and subsequent formation of the major products are outlined. Speculation of the mechanism of formation of CHCl3 and C2HCl3 are supported by quantum chemical calculations. In addition, the effect of introducing methane in the reaction feed on the conversion level of DCM and the polymer structure is also examined in this paper.

Chromosoma, 1981

Chromatin organization and transcriptional activity in the macronucleus of the ciliate Paramecium... more Chromatin organization and transcriptional activity in the macronucleus of the ciliate Paramecium primaurelia have been studied by electron microscopic examination of spread chromatin preparations. Under spreading conditions which inhibit the activity of endogenous nucleases and proteases, various morphologically distinct types of chromatin are seen: (1) Largely condensed chromatin in the form of 30-40 nm supranucleosomal globules which aggregate to form knobbly 40-60 nm fibres and unravel into 12 nm nucleosomal filaments; (2) In rapidly growing cells, extended chromatin arranged groups of 4-8 adjacent nucleofilaments, each bearing numerous and very densely packed lateral fibrils. These fibrils are 20 nm thick, have a smooth outline and extend to lengths of up to 3 micron. Such transcripts are grouped in units along the chromatin axis and are apparently organized in register in adjacent filaments; (3) In starved cells, extended nucleofilaments bearing only occasional RNP fibrils. These various morphological characteristics are discussed in terms of macronuclear transcriptional activity and the polyploid nature of macronuclei.

J Phys Chem a, 1999

... 9, CF 3 + CF 2 = CF 3 −CF 2, 13.0, 0, 0.0, 15.4, 0, 214.5, estd. 10, CH 2 F−CF 3 = CH 2 F + C... more ... 9, CF 3 + CF 2 = CF 3 −CF 2, 13.0, 0, 0.0, 15.4, 0, 214.5, estd. 10, CH 2 F−CF 3 = CH 2 F + CF 3, 17.0, 0, 373.6, 13.6, 0, −0.3, estd. 11, CH 2 F−CF 3 = HF + CHF:CF 2, 13.4, 0, 296.2, 11.2, 0, 180.3, 4. 12, 2CH 2 F = CH 2 F−CH 2 F, 13.5, 0, 0.0, 17.3, 0, 351.4, estd. ...

Chemical Engineering Journal, 2016

Fire Safety Science, 2007

Fires provide optimum conditions to produce polychlorinated dibenzo-p-dioxins and polychlorinated... more Fires provide optimum conditions to produce polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/F) as well as polychlorinated biphenyls (PCB). In this study, we deploy the density functional theory (DFT) to simulate the production of PCB, and polychlorinated dibenzofurans (PCDF), which are formed in fires from the precursor chlorobenzene in preference to polychlorinated dibenzo-p-dioxins (PCDD). We demonstrate that, combinations of chlorobenzene with chlorophenyl radicals generate PCB compounds through an exothermic reaction of 18.7 kcal/mol. H on the pivot bond could be self-expulsed through an energy barrier of 21.7 kcal/mol to produce 2,2'dichlorobiphenyl. Combinations of chlorobenzene and chlorophenoxy radicals, formed in early stages of the oxidation of chlorobenzene, afford 16 different precursors for PCDFs. All these reactions are endothermic, between 18.3 to 38.8 kcal/mol at 298 K, with activation enthalpies higher by 3-10 kcal/mol than the reaction enthalpies.

Fire Safety Science, 2011

Several varieties of linseed oil are commercially available, and they have been used for many app... more Several varieties of linseed oil are commercially available, and they have been used for many applications especially in decorative furniture finishing and as an oil painting medium. The addition of metallic driers to the linseed oil is a common practice, as it improves the drying rate of the paint. Several cases of fires have been reported, often involving rags soaked with linseed oil which have not been disposed of properly, and it is generally agreed that metal salts in the linseed oil play an important role in the spontaneous ignition of the oil. This paper investigates several types of linseed oil sold in the market and their tendency to cause self-heating of cotton which has been impregnated with linseed oil obtained from various sources.

The Journal of organic chemistry, Jan 6, 2015

Nitrosation reactions span a diverse range of applications, from biochemistry to industrially imp... more Nitrosation reactions span a diverse range of applications, from biochemistry to industrially important processes. This study examines nitrosation of aminothiones in acidic solutions and re-evaluates currently accepted diffusion limits and the true nature of the nitrosating agent for nitrous acid initiated reactions. Experimental measurements from stopped-flow UV/vis spectrophotometry afforded derivation of equilibrium constants and reaction enthalpies. Apparent Keq corresponds to 559-382 M(-2) for thioacetamide (TA, 15-25 °C) and 12600-5590 M(-2) for thiourea (TU, 15-35 °C), whereas the reaction enthalpies amount to -27.10 ± 0.05 kJ for TA and -29.30 ± 0.05 kJ for TU. Theoretical calculations via a thermochemical cycle agree well with reaction free energies from experiments, with errors of -2-4 kJ using solvation method SMD in conjunction with hybrid meta exchange-correlation functional M05-2X and high-accuracy multistep method CBS-QB3 for gas-phase calculations. The kinetic rates ...

Fire Safety Science, 2011

ABSTRACT This study presents an investigation into the gas phase thermal decomposition of captafo... more ABSTRACT This study presents an investigation into the gas phase thermal decomposition of captafol, a sulfenimide fungicide which consists of a thiotetrachloroethyl (-SCCl 2CHCl 2) group bonded to a tetrahydrophthalimide (C 6H 8(CO) 2N-) moiety. The experiments were performed on a bench type apparatus, under conditions representing both under and well-ventilated non-flaming fires. The analyses of gaseous species relied on Fourier transform infra-red spectroscopy (FTIR) and micro gas chromatography (μGC), resulting in the identification and quantification of 11 gaseous products; among them, phosgene, thiophosgene and hydrogen cyanide. Gas chromatography - quadrupole mass spectrometry (GC-QMS) was employed to analyse the condensed products and volatile organic compounds (VOC), while a GC equipped with an ion trap mass spectrometer (GC-ITMS) was used to quantify polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F). The GC-QMS analysis determined several VOC toxicants; viz., trichloroethylene, tetrachloroethylene, benzonitrile and chlorinated benzenes. At higher temperature (600 °C), the oxidation of captafol led to the formation of mono- to hepta-CDD/F congeners including the most toxic 2,3,7,8-TCDD. In addition, the experimental results were compared to those of the other two sulfenimide fungicides, captan and folpet, both of which contain the thiotrichloromethyl (-SCCl 3) moiety rather than the thiotetrachloroethyl group of captafol. It appears that the thiotetrachloroethyl group in captafol is responsible for the difference in the toxic pollutants formed, particularly influencing the distribution and yields of PCDD/F congeners. Combined with quantum chemical calculations, the results presented in this article provide an insightful understanding of fire chemistry of the sulfenimide fungicides, especially the pathways to the formation of major toxicants during the oxidative thermal decomposition of captafol.

In this paper we study the effect of adding methane as an additive to 1,2-dichloroethane (EDC) in... more In this paper we study the effect of adding methane as an additive to 1,2-dichloroethane (EDC) in non thermal plasma treatment using a cylindrical dielectric barrier discharge (DBD) reactor to yield commercially important products. EDC is primarily used in vinyl chloride production. However, EDC is listed as a priority pollutant by the US EPA and has been identified as a human carcinogen. Hence its treatment has high significance. In contrast to majority of research on EDC, the present research is focussed on the non oxidative treatment of EDC at atmospheric pressure using a DBD to beget commercially important products such as vinyl chloride and polyvinyl chloride. The addition of CH4 reduced the concentration of structural defects, notably unsaturation in the polymer backbone chain as compared to the polymer, which was obtained from EDC treatment in absence of additives.

The reaction of HFC-134a (CF3CH2F) in an argon bath gas has been studied using a dielectric barri... more The reaction of HFC-134a (CF3CH2F) in an argon bath gas has been studied using a dielectric barrier discharge non-thermal plasma at atmospheric pressure. Oxygen and nitrogen have been excluded in the reaction. It has been found that CF3CH2F can be converted into a non-crosslinked polymer under the reaction conditions studied. Other products include CHF3, CH2F2, C2H3F, C3H3F5, H2, HF and an oligomeric product fraction. The discharge characteristics of argon diluted CF3CH2F has been discussed, which is in the transition region between filamentary and homogeneous glow. The conversion of CF3CH2F ranges from 52% to 82 % for the applied voltage range of 13.4 – 15 kV (peak-peak) and input energy density range of 2 - 12 kJ/L. A simplified reaction mechanism has been proposed. Gel permeation chromatography analysis show two fractions with top molecular weights (Mp) of 2400 and 105,000 g/mol respectively, produced at an input energy density of 8 kJ/l.

RSC Adv., 2015

ABSTRACT Nitrosation reactions and subsequent decomposition of S-nitroso (RSNO+) species remain i... more ABSTRACT Nitrosation reactions and subsequent decomposition of S-nitroso (RSNO+) species remain important in many biochemical processes as well as in industrial applications such as chemical gassing of emulsion explosives. This paper develops kinetic mechanisms of gas formation pathways in the decomposition of RSNO+ species, particularly S-nitrosothioacetamide and S-nitrosothiourea, providing new kinetic and thermodynamic constants. At pH levels of 1 and below, decomposition proceeds exclusively via NO formation pathways. With decreasing acidity, molecular nitrogen formation emerges as an equally important product of S-nitrosothiourea, while NO remains the only product for S-nitrosothioacetamide. Theoretical calculations for reaction enthalpies further elucidate the gas formation pathways and proposed mechanisms, fitted to experimental data, afford kinetic rate constants. In both species, the S–N bonds split homolytically with activation energies of 70.9 and 118 kJ mol-1 for S-nitrosothioacetamide and S-nitrosothiourea, respectively. The electron donating effect of methyl substitution in S-nitrosothioacetamide engenders lower activation energies with the bimolecular reaction of RSNO+ and RS occurring within the diffusion controlled regime at an activation energy of 17.6 kJ mol-1. For S-nitrosothiourea, a further bimolecular reaction of two RSNO+ molecules occurs irreversibly with an activation energy of 84.4 kJ mol-1.

Proceedings of the Sixth International Seminar on Fire and Explosion Hazards, 2011

ABSTRACT This paper examines the effect of methane on the reaction of 1, 2-dichloroethane in a no... more ABSTRACT This paper examines the effect of methane on the reaction of 1, 2-dichloroethane in a non-thermal plasma in a double dielectric barrier discharge (DBD) reactor, under non oxidative conditions and at atmospheric pressure. Commercially important products such as vinyl chloride and polyvinyl chloride were produced. The addition of CH4 to the feed stream reduces the concentration of unsaturation in the polymeric material.

Journal of Molecular Structure: THEOCHEM, 2010

... 1 A DFT Study on the Self-Coupling Reactions of the Three Isomeric Semiquinone Radicals Abdal... more ... 1 A DFT Study on the Self-Coupling Reactions of the Three Isomeric Semiquinone Radicals Abdallah Alsoufi1, Mohammednoor Altarawneh1, Bogdan Z. Dlugogorski2*, Eric M. Kennedy2 and John C. Mackie2* 1Chemical ... [15] R. Asatryan, A. Davtyan, L. Khachatryan, B ...