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Papers by Christian Roy

International Endodontic Journal, 2001

AimThe bactericidal effect of four antimicrobial agents was investigated against single‐species b... more AimThe bactericidal effect of four antimicrobial agents was investigated against single‐species biofilms derived from a range of root canal isolates.MethodologySingle‐species biofilms of Prevotella intermedia, Peptostreptococcus micros, Streptococcus intermedius, Fusobacterium nucleatum and Enterococcus faecalis were generated on membrane filter discs and subjected to 15 min or 1 h incubation with 5 p.p.m. colloidal silver, 2.25% sodium hypochlorite (NaOCl), 0.2% chlorhexidine, 10% iodine or phosphate buffered saline (PBS) as a control. The antimicrobial activity of the agents was neutralized and the bacterial cells were harvested from the discs by vortexing, serially diluted in reduced transport fluid, plated on fastidious anaerobe agar containing 5% horse blood, incubated anaerobically and colony‐forming units calculated.ResultsIodine and NaOCl were more effective than chlorhexidine except against P. micros and P. intermedia where they were all 100% effective. Iodine and NaOCl eli...

Wood Science and Technology, 1992

Springer eBooks, 1993

Vacuum pyrolysis of biomass such as wood yields approximately 50% by weight of oil, 15% pyrolytic... more Vacuum pyrolysis of biomass such as wood yields approximately 50% by weight of oil, 15% pyrolytic water, 10% gas and 25% charcoal (wt. %, air-dry feedstock basis). Past studies indicated that the pyrolysis oils typically contain 5–10% non-polar hydrocarbons, 5–10% low molecular weight organic acids, 5–10% sugars, 10–25% oxygenated cyclic compounds with moderate polarity and potential economic values such as phenol and vanillin, 30–45% high polar and high molecular weight compounds and 15–30% water.

CRC Press eBooks, Jun 14, 2005

Brazilian Journal of Microbiology, May 28, 2020

Pyroligneous acid (PA) was evaluated as a potential alternative to therapeutic antibiotics in pou... more Pyroligneous acid (PA) was evaluated as a potential alternative to therapeutic antibiotics in poultry. Antimicrobial activity of PA was studied at acidic pH (2.0) and neutral pH (7.0) of the liquid against Salmonella enterica and Lactobacillus acidophilus. Acidic PA gave a MIC value of 0.8% (v/v) and 1.6% (v/v), and neutralized PA gave a MIC value of 1.6% (v/v) and 3.2% (v/v) against S. enterica and L. acidophilus respectively. Acidic PA was evaluated at different concentrations in a simulated poultry digestive tract and cecal fermentation to study its effect on the cecal microflora and fermentation profile. PA at a concentration of 1.6% (v/v) completely inhibited S. enterica and was also found to have a similar effect on lactobacilli count as compared with the control (p = 0.17). Additionally, PA at this concentration was found not to have a significant effect on acetic acid production after 24 h of cecal fermentation (p = 0.20). Open in a separate windowGraphical abstract

Thermochimica Acta, Aug 1, 1999

Abstract In thermal analysis, the apparatus commonly used to quantitatively measure enthalpy chan... more Abstract In thermal analysis, the apparatus commonly used to quantitatively measure enthalpy change is the DSC while the DTA equipment is used for qualitative measurements. In this work a new method, called the “mass-difference baseline method”, is proposed to attempt to use DTA for quantitative measurement. The presented method employs the DTA curve derived from a small mass sample as the baseline for a large mass sample using the same material. Such an approach diminishes the asymmetric heat transfer problem attributed to the “apparatus effect” and “sample influence”, thus greatly improving the linearity between the DTA curve and enthalpy change. The theoretical basis of this method is presented and discussed in this paper. The method has been tested for the determination of the enthalpy change of graphite and elastomers over a large temperature range from 30°C to 600°C. Compared with DSC, one important advantage of this method is that it allows enthalpy measurement to be carried out in an open system allowing a sample mass loss during the measurement. For example, during the measurement of elastomers, intensive decomposition and 70% of the sample mass loss occur. The DTA quantitative measurement successfully determines the heat capacity changes as well as the heat of reaction and heat of evaporation, which all occur during the enthalpy changes of the material subjected to decomposition. However, the accuracy of this method is still not high enough for high accurate enthalpy measurement.

Thermochimica Acta, Oct 1, 1996

A novel approach involving the use of DTA to measure quantitatively the enthalpy change during ru... more A novel approach involving the use of DTA to measure quantitatively the enthalpy change during rubber atmospheric pyrolysis was developed and applied to tire rubbers: NR (natural rubber), SBR (styrene-butadiene rubber) and BR (butadiene rubber). Based on a new method of baseline determination, this approach detects precisely the overall enthalpy change during rubber pyrolysis, which consists of a linear heat

Rubber Chemistry and Technology, May 1, 1993

Polymer Degradation and Stability, 2001

Polymer Degradation and Stability, Jun 1, 2001

Chemical engineering research & design, May 1, 2000

Acs Symposium Series, Sep 30, 1988

Canadian Journal of Chemical Engineering, Apr 1, 1988

The gasification of biomass derived char obtained via vacuum and atmospheric pyrolysis of Populus... more The gasification of biomass derived char obtained via vacuum and atmospheric pyrolysis of Populus tremuloides has been studied in the ranges of 725–960°C and 0.1 to 6 MPa. CO2 was used as the oxidizing gas.The results show that char reactivity is influenced by the preheating rates and that pressure effects are significant between 850°C and 950°C. A correlation based on the expression: df/dt = k0{exp(‐E/RT)}(1 ‐ f)afβPyCO2 was used to fit the experimental data.In general, vacuum pyrolysis derived char showed a higher reactivity than atmospheric pyrolysis chars. An explanation based on a higher oxygen content of the vacuum pyrolysis char is suggested.

Springer eBooks, 1988

A process for the pyrolysis under vacuum of biomass and waste materials has been under developmen... more A process for the pyrolysis under vacuum of biomass and waste materials has been under development since 1978 in Canada. Background data regarding the yields and qualities of the pyrolysis products derived from materials such as wood, bark, agricultural residues, peat, municipal solid wastes, activated sludges and scrap tires, have been obtained at the bench scale level. A Process Development Unit having a feedthrough capacity of up to 25 kg h-1 and using a multiple hearth furnace reactor has been designed and built. The objectives of the P.D.U. were twofold. First, the Unit was used to determine engineering data such as the overall thermal efficiency and the heat requirement for the reactions. Second, the configuration and mechanical operation of the reactor had to be tested before its scale-up for the pilot plant phase of the project (150 kg h-1).

Journal of Wood Chemistry and Technology, Jan 12, 2002

... Extraction of betulin by vacuum pyrolysis of birch bark. Auteur(s) / Author(s). PAKDEL Hoosha... more ... Extraction of betulin by vacuum pyrolysis of birch bark. Auteur(s) / Author(s). PAKDEL Hooshang (1) ; MURWANASHYAKA Jean Népo (1) ; ROY Christian (1 2) ; Affiliation(s) du ou des auteurs / Author(s) Affiliation(s). ... Pirólisis. ; Extracción. ; Corteza(vegetal). ; Betula papyrifera. ; ...

Journal of Chromatography A, Sep 1, 1980

Canadian Journal of Chemical Engineering, Feb 1, 1997

Chemical Engineering Science, Jun 1, 1995

... Therefore when m, mm = const (7) dm dmst (8) dt dt where dms dt, the rate of evaporation, is ... more ... Therefore when m, mm = const (7) dm dmst (8) dt dt where dms dt, the rate of evaporation, is assumed to be equal to the rate of weight loss of ... the heat generation or consumption of pyrolysis can be de rived, yielding cT l t3 (rkOT" k T + zz zJ + (1 e)plq (10) where e Po Ceg(OT Ot ...

Fuel Processing Technology, Jul 1, 1979

Abstract The technical vocabulary used to describe the chemical transformations of fuels is criti... more Abstract The technical vocabulary used to describe the chemical transformations of fuels is critically revised with the objective of establishing a simple and coherent classification. The criterion used for such classification is based on the unique and specific chemical nature of each of the transformations. Thus three distinct categories are defined: thermal decomposition reactions, oxidation reactions and reduction reactions. The scope of application of these categories as well as their subdivisions are also discussed.

Journal of Chromatographic Science, Sep 1, 1981

International Endodontic Journal, 2001

AimThe bactericidal effect of four antimicrobial agents was investigated against single‐species b... more AimThe bactericidal effect of four antimicrobial agents was investigated against single‐species biofilms derived from a range of root canal isolates.MethodologySingle‐species biofilms of Prevotella intermedia, Peptostreptococcus micros, Streptococcus intermedius, Fusobacterium nucleatum and Enterococcus faecalis were generated on membrane filter discs and subjected to 15 min or 1 h incubation with 5 p.p.m. colloidal silver, 2.25% sodium hypochlorite (NaOCl), 0.2% chlorhexidine, 10% iodine or phosphate buffered saline (PBS) as a control. The antimicrobial activity of the agents was neutralized and the bacterial cells were harvested from the discs by vortexing, serially diluted in reduced transport fluid, plated on fastidious anaerobe agar containing 5% horse blood, incubated anaerobically and colony‐forming units calculated.ResultsIodine and NaOCl were more effective than chlorhexidine except against P. micros and P. intermedia where they were all 100% effective. Iodine and NaOCl eli...

Wood Science and Technology, 1992

Springer eBooks, 1993

Vacuum pyrolysis of biomass such as wood yields approximately 50% by weight of oil, 15% pyrolytic... more Vacuum pyrolysis of biomass such as wood yields approximately 50% by weight of oil, 15% pyrolytic water, 10% gas and 25% charcoal (wt. %, air-dry feedstock basis). Past studies indicated that the pyrolysis oils typically contain 5–10% non-polar hydrocarbons, 5–10% low molecular weight organic acids, 5–10% sugars, 10–25% oxygenated cyclic compounds with moderate polarity and potential economic values such as phenol and vanillin, 30–45% high polar and high molecular weight compounds and 15–30% water.

CRC Press eBooks, Jun 14, 2005

Brazilian Journal of Microbiology, May 28, 2020

Pyroligneous acid (PA) was evaluated as a potential alternative to therapeutic antibiotics in pou... more Pyroligneous acid (PA) was evaluated as a potential alternative to therapeutic antibiotics in poultry. Antimicrobial activity of PA was studied at acidic pH (2.0) and neutral pH (7.0) of the liquid against Salmonella enterica and Lactobacillus acidophilus. Acidic PA gave a MIC value of 0.8% (v/v) and 1.6% (v/v), and neutralized PA gave a MIC value of 1.6% (v/v) and 3.2% (v/v) against S. enterica and L. acidophilus respectively. Acidic PA was evaluated at different concentrations in a simulated poultry digestive tract and cecal fermentation to study its effect on the cecal microflora and fermentation profile. PA at a concentration of 1.6% (v/v) completely inhibited S. enterica and was also found to have a similar effect on lactobacilli count as compared with the control (p = 0.17). Additionally, PA at this concentration was found not to have a significant effect on acetic acid production after 24 h of cecal fermentation (p = 0.20). Open in a separate windowGraphical abstract

Thermochimica Acta, Aug 1, 1999

Abstract In thermal analysis, the apparatus commonly used to quantitatively measure enthalpy chan... more Abstract In thermal analysis, the apparatus commonly used to quantitatively measure enthalpy change is the DSC while the DTA equipment is used for qualitative measurements. In this work a new method, called the “mass-difference baseline method”, is proposed to attempt to use DTA for quantitative measurement. The presented method employs the DTA curve derived from a small mass sample as the baseline for a large mass sample using the same material. Such an approach diminishes the asymmetric heat transfer problem attributed to the “apparatus effect” and “sample influence”, thus greatly improving the linearity between the DTA curve and enthalpy change. The theoretical basis of this method is presented and discussed in this paper. The method has been tested for the determination of the enthalpy change of graphite and elastomers over a large temperature range from 30°C to 600°C. Compared with DSC, one important advantage of this method is that it allows enthalpy measurement to be carried out in an open system allowing a sample mass loss during the measurement. For example, during the measurement of elastomers, intensive decomposition and 70% of the sample mass loss occur. The DTA quantitative measurement successfully determines the heat capacity changes as well as the heat of reaction and heat of evaporation, which all occur during the enthalpy changes of the material subjected to decomposition. However, the accuracy of this method is still not high enough for high accurate enthalpy measurement.

Thermochimica Acta, Oct 1, 1996

A novel approach involving the use of DTA to measure quantitatively the enthalpy change during ru... more A novel approach involving the use of DTA to measure quantitatively the enthalpy change during rubber atmospheric pyrolysis was developed and applied to tire rubbers: NR (natural rubber), SBR (styrene-butadiene rubber) and BR (butadiene rubber). Based on a new method of baseline determination, this approach detects precisely the overall enthalpy change during rubber pyrolysis, which consists of a linear heat

Rubber Chemistry and Technology, May 1, 1993

Polymer Degradation and Stability, 2001

Polymer Degradation and Stability, Jun 1, 2001

Chemical engineering research & design, May 1, 2000

Acs Symposium Series, Sep 30, 1988

Canadian Journal of Chemical Engineering, Apr 1, 1988

The gasification of biomass derived char obtained via vacuum and atmospheric pyrolysis of Populus... more The gasification of biomass derived char obtained via vacuum and atmospheric pyrolysis of Populus tremuloides has been studied in the ranges of 725–960°C and 0.1 to 6 MPa. CO2 was used as the oxidizing gas.The results show that char reactivity is influenced by the preheating rates and that pressure effects are significant between 850°C and 950°C. A correlation based on the expression: df/dt = k0{exp(‐E/RT)}(1 ‐ f)afβPyCO2 was used to fit the experimental data.In general, vacuum pyrolysis derived char showed a higher reactivity than atmospheric pyrolysis chars. An explanation based on a higher oxygen content of the vacuum pyrolysis char is suggested.

Springer eBooks, 1988

A process for the pyrolysis under vacuum of biomass and waste materials has been under developmen... more A process for the pyrolysis under vacuum of biomass and waste materials has been under development since 1978 in Canada. Background data regarding the yields and qualities of the pyrolysis products derived from materials such as wood, bark, agricultural residues, peat, municipal solid wastes, activated sludges and scrap tires, have been obtained at the bench scale level. A Process Development Unit having a feedthrough capacity of up to 25 kg h-1 and using a multiple hearth furnace reactor has been designed and built. The objectives of the P.D.U. were twofold. First, the Unit was used to determine engineering data such as the overall thermal efficiency and the heat requirement for the reactions. Second, the configuration and mechanical operation of the reactor had to be tested before its scale-up for the pilot plant phase of the project (150 kg h-1).

Journal of Wood Chemistry and Technology, Jan 12, 2002

... Extraction of betulin by vacuum pyrolysis of birch bark. Auteur(s) / Author(s). PAKDEL Hoosha... more ... Extraction of betulin by vacuum pyrolysis of birch bark. Auteur(s) / Author(s). PAKDEL Hooshang (1) ; MURWANASHYAKA Jean Népo (1) ; ROY Christian (1 2) ; Affiliation(s) du ou des auteurs / Author(s) Affiliation(s). ... Pirólisis. ; Extracción. ; Corteza(vegetal). ; Betula papyrifera. ; ...

Journal of Chromatography A, Sep 1, 1980

Canadian Journal of Chemical Engineering, Feb 1, 1997

Chemical Engineering Science, Jun 1, 1995

... Therefore when m, mm = const (7) dm dmst (8) dt dt where dms dt, the rate of evaporation, is ... more ... Therefore when m, mm = const (7) dm dmst (8) dt dt where dms dt, the rate of evaporation, is assumed to be equal to the rate of weight loss of ... the heat generation or consumption of pyrolysis can be de rived, yielding cT l t3 (rkOT" k T + zz zJ + (1 e)plq (10) where e Po Ceg(OT Ot ...

Fuel Processing Technology, Jul 1, 1979

Abstract The technical vocabulary used to describe the chemical transformations of fuels is criti... more Abstract The technical vocabulary used to describe the chemical transformations of fuels is critically revised with the objective of establishing a simple and coherent classification. The criterion used for such classification is based on the unique and specific chemical nature of each of the transformations. Thus three distinct categories are defined: thermal decomposition reactions, oxidation reactions and reduction reactions. The scope of application of these categories as well as their subdivisions are also discussed.

Journal of Chromatographic Science, Sep 1, 1981