Wendy Duncan | St Louis College Of Pharmacy (original) (raw)

Papers by Wendy Duncan

Small group, self-directed problem-based learning is often arranged so that a faculty tutor is a ... more Small group, self-directed problem-based learning is often arranged so that a faculty tutor is a member of each group. Courses with limited faculty resources use learning groups that are tutorless. For such situations, the students are trained and empowered to manage such "processing skills" as problem solving, change management, group process, critical thinking and self-directed, interdependent learning skills. Our experience has been primarily with such tutorless groups. The processing issues have completely different priorities for tutorless groups than one encounters with tutored groups. In tutorless groups, the issues are frustration because not everyone appears to do their fair share of the work, attendance, building trust and reliability, personal differences in learning and the need to be accountable by writing reflective journals. In tutored and tutorless groups ten additional issues are listed. Suggestions are given on how to cope with each of the fifteen issues.

Pharmaceutical Research, 1996

Purpose. The objective of our work was to evaluate the elastic modulus through ultrasonic testing... more Purpose. The objective of our work was to evaluate the elastic modulus through ultrasonic testing of poly(methyl methacrylate-co-methacrylic acid) (PMMA/coMAA), a viscoelastic polymer similar to the commercial Eudragit®, to calculate this modulus, assuming a regular arrangement of interacting groups, and ultimately, assess the accuracy of microindentation as a means of evaluating elasticity in very small samples. Methods. Knoop indentation testing was performed on cast samples using a Tukon testing apparatus. Solid density and pulse echo testing employing a damped 15 MHz transducer served to quantify the elastic moduli. Using the Hoy method of calculation for molar attraction constants, and assuming pairwise addition, the modulus was calculated and compared with typical experimental values for amorphous and crystalline polymers. Results. Acoustic testing resulted in an average elastic modulus value of 5.67 ± 0.2 GPa for this copolymer, which concurs with literature values for PMMA. Acoustically derived experimental moduli when normalized and plotted against calculated values, resulted in a relationship, E/(1 − 2υ) = 17.0 (E coh + χcΔHm)/V + 6.9, similar to that predicted in theory. Conclusions. Indentation contact modeling does not adequately describe the real recovery under indentation. In contrast, acoustic testing of pharmaceutical materials affords a simple, reproducible means of characterizing moduli without impairing structural integrity. Acoustically derived moduli further afford insight into the intermolecular interactions, as expressed by the interaction energy terms.

Journal of Adhesion Science and Technology, 1993

... Eng. Commun. 33, 255 (1985). 9. EI Vargha-Butler, TK Zubovits, HA Hamza and AW Neumann, J. Di... more ... Eng. Commun. 33, 255 (1985). 9. EI Vargha-Butler, TK Zubovits, HA Hamza and AW Neumann, J. Dispersion Sci. Technol. ... Ind. 35, 719 (1973). 52. M. De Lourdes Costa and A. Baszkin, J. Pharm. Pharmacol. ... 17, 374 (1921). 60. MJ Groves and MH Alkan, J. Pharm. Pharmacol. ...

Colloids and Surfaces B-biointerfaces, 1995

Langmuir, 1993

The behavior of the piezoelectric acoustic wave sensor of the thickness-shear-mode type in variou... more The behavior of the piezoelectric acoustic wave sensor of the thickness-shear-mode type in various liquids has been characterized by the network analysis method. Models for this system based only on bulk liquid parameters fail to explain the behavior of the device with respect to series resonant frequency. Use of sensors with controlled surface free energy of the metal electrodes has been employed to demonstrate the importance of the liquid-solid interface in determining the response of the device. The contribution of the effects of surface roughness on the sensor response is discussed. Additionally, a previously-published four-layer model is successful in predicting the trends in values for the series resonant frequency for a set of mixed water-methanol solutions.

Journal of The American Pharmacists Association, 2007

... Wendy Duncan–Hewitt, PhD, is Dean of Pharmacy, St. ... E-mail: somma@pitt.edu Disclosure: Dr.... more ... Wendy Duncan–Hewitt, PhD, is Dean of Pharmacy, St. ... E-mail: somma@pitt.edu Disclosure: Dr. Somma McGivney is a fac-ulty consultant to the Rite Aid ... Acknowledgments: To Teresa McKaveney and Erik Rueter of the University of Pitts-burgh School of Pharmacy for assistance ...

Analyst, 1991

... Review. Analyst, 1991, 116, 881 - 890, DOI: 10.1039/AN9911600881. Thickness-shear-mode acoust... more ... Review. Analyst, 1991, 116, 881 - 890, DOI: 10.1039/AN9911600881. Thickness-shear-mode acoustic wave sensors in the liquid phase. A review Michael Thompson, Arlin L. Kipling, Wendy C. Duncan-Hewitt, Ljubinka V. Rajakovi and Biljana A. avi -Vlasak. ...

Objectives. To identify instructional and assessment problems leading to pharmacy students&#3... more Objectives. To identify instructional and assessment problems leading to pharmacy students' failure to retain pharmacokinetics abilities into the experiential year and develop an instructional methodology and abilities-based assessment tool to address the problem. Methods. Pharmacokinetic instructional methods were assessed and an abilities-based assessment tool was developed and utilized as a requirement for curricular progression. Both the instructional meth- odology and

Journal of Pharmaceutical Sciences, 1999

The present investigation was undertaken to examine the basic unit of densification: the particle... more The present investigation was undertaken to examine the basic unit of densification: the particle–particle indentation. The true interparticle contact area that is established during densification ultimately determines the quality of the tablet compact. By examining the interfacial contact between mutually indenting viscoelastic particles, the process of contact evolution may be represented in mathematical form through extension of the classical Hertzian elastic contact description to encompass material viscoelastic terms. In this way, the time-dependent response of materials to applied loads may be addressed explicitly. The effects of rates of applied loading and maximum load levels were also considered. This analysis was based on viscoelastic stress data collected using an instrumented Instron analyzer during the densification of PMMA/coMMA, a pharmaceutical polymeric coating material. A crossed cylinder matrix compaction geometry was used to simulate the geometry of two mutually indenting spherical particles. Numerical and graphical solutions delineating the relationship between contact area evolution and the prescribed loading force are presented. This particle–particle description of the contacting interface serves as a unit basis for describing the entire powder bed. The powder bed may ultimately be modeled as a collection of these particles in contact.

Pharmaceutical Research, 1989

The deformation kinetics of sucrose crystals were evaluated using the Vickers microindentation te... more The deformation kinetics of sucrose crystals were evaluated using the Vickers microindentation technique. A (100) face of a crystal of sucrose was indented for varying lengths of time at temperatures ranging from 23 to 103°C, and the deformation kinetics analysis proposed by Verrall et al. (1) was employed to calculate the strain rate and stress from the indentation time and the size of the indentation. Two kinetic parameters, the activation volume and the activation energy, were calculated from the experimental data and compared to those of other materials on normalized scales. The results suggest that the deformation kinetics of sucrose resemble those of ice, the crystal lattice of which is highly hydrogen-bonded, similar to that of sucrose.

 In the "Information Age," the profession of Engineering needs "critical thinkers" and "complex ... more  In the "Information Age," the profession of Engineering needs "critical thinkers" and "complex problem-solvers." Since most entering graduate students do not possess these abilities, it should be the responsibility of graduate programs to mentor their growth in addition to teaching them disciplinary knowledge and skills, but this is seldom done. Given that the desired abilities have a cognitive basis, we hypothesize that decisions about appropriate educational methods are best made by considering the development of graduate students' intellectual complexity.

Colloids and Surfaces, 1989

ABSTRACT

Pharmaceutical Research, 1994

The anisotropy of acetaminophen hardness was demonstrated using both Vickers and Knoop indentatio... more The anisotropy of acetaminophen hardness was demonstrated using both Vickers and Knoop indentation hardness measurements. Based on a model of Knoop hardness anisotropy proposed by Brookes et al. (1), it was concluded that plastic flow in acetaminophen crystals occurs primarily as a result of slip in the (010)(001) system. This conclusion was corroborated with the results of the Vickers indentation tests. The apparent brittleness of acetaminophen was rationalized because only one slip system appeared to be operative. Under these conditions generalized plastic flow cannot occur, since this requires the operation of at least five independent slip systems (2). The high stress concentrations that result from flow lead to fracture. Therefore acetaminophen is more precisely classified as being semiductile. When a material deforms plastically as a result of slip in only one slip system, considerable crystal realignment can occur during compaction. This in turn can facilitate capping during decompression and ejection, since the cleavage plane, (010), would become aligned with the direction of highest tensile stress.

Analytical Chemistry, 1992

... Sugawara, KF; Weetall. HH; Schucker, G. D. Anal. Chem. 1874, Marshal, MA; Mottola, HA Anal. .... more ... Sugawara, KF; Weetall. HH; Schucker, G. D. Anal. Chem. 1874, Marshal, MA; Mottola, HA Anal. ... Liquids Incorporating Interfacial Slip and Liquid Structure Wendy C. Duncan-Hewitt* Faculty of Pharmacy, University of Toronto, 19 Russell Street, Toronto, Ontario, M5S 1Al Canada ...

Journal of Materials Science Letters, 1989

Journal of Pharmaceutical Sciences, 1990

A model is presented which uses the hardness and elastic moduli of brittle crystals, determined u... more A model is presented which uses the hardness and elastic moduli of brittle crystals, determined using the Vickers microindentation test, to predict the uniaxial compaction behavior of compacts. A general approach first developed in the materials science field to predict the densification of particulate matter under hydrostatic loading was followed. Modifications to account for the effects of particle geometry and the closed-die loading conditions were considered. The model predicted the densification behavior of sucrose and adipic acid. It did not predict the densification of acetaminophen as well; however, the discrepancy between the experimental and predicted values may arise either from error associated with the evaluation of the elastic modulus using the microindentation test or from error in calculating the relative density of compacts which were observed to have partially laminated. The effects of error both in the hardness value and in the ratio of punch to die-wall stress on the predictive capability of the model were also discussed briefly.

Pharmaceutical Research, 1989

The brittleness of pharmaceutical crystals influences their ability to form compacts of acceptabl... more The brittleness of pharmaceutical crystals influences their ability to form compacts of acceptable quality. While many macroscopic methods are available to elucidate the fracture behavior of materials, the porosity, inhomogeneity, and anisotropy of pharmaceutical compacts render it difficult to interpret the results of these tests. Microindentation techniques may be used to evaluate both the flow and the fracture characteristics of small crystals, so that it is not necessary to test compacts. The flow and fracture behavior of sucrose, the model substance used in this study, were anisotropic. The fracture surface energy, derived from the average fracture toughness value, is of the same order of magnitude as the surface free energy, indicating that sucrose fractures in a brittle manner.

 Experiments with a variety of teaching techniques to improve meaningful learning often are ofte... more  Experiments with a variety of teaching techniques to improve meaningful learning often are often only partially successful, leaving many students struggling with the abstract and complex knowledge of the engineering disciplines. We hypothesize that decisions about appropriate teaching methods are best made b y considering the development of students' intellectual complexity using the "Crux Developmental Model" (CDM) synthesized from a number of disparate theories in the educational, developmental, and complexity literatures. The CDM and its application were assessed and improved over a three-year cycle in the context of a Science and Engineering Camp for teenagers. Our results supported the hypothesis that the CDM: (1) provides a rational method of selecting developmentally appropriate activities to teach specific skills and content, and; (2) provides a tool for customizing learning activities to maximize growth. According to the developmental model, the teenage participants in camp are working at the beginning of the same developmental transition that undergraduates are completing. Thus, we conclude this paper by proposing how the results of this study can be generalized to the undergraduate experience. Index Terms  cognitive complexity, curriculum planning, entering students, guided design, intellectual development, teaching methods.

Small group, self-directed problem-based learning is often arranged so that a faculty tutor is a ... more Small group, self-directed problem-based learning is often arranged so that a faculty tutor is a member of each group. Courses with limited faculty resources use learning groups that are tutorless. For such situations, the students are trained and empowered to manage such "processing skills" as problem solving, change management, group process, critical thinking and self-directed, interdependent learning skills. Our experience has been primarily with such tutorless groups. The processing issues have completely different priorities for tutorless groups than one encounters with tutored groups. In tutorless groups, the issues are frustration because not everyone appears to do their fair share of the work, attendance, building trust and reliability, personal differences in learning and the need to be accountable by writing reflective journals. In tutored and tutorless groups ten additional issues are listed. Suggestions are given on how to cope with each of the fifteen issues.

Pharmaceutical Research, 1996

Purpose. The objective of our work was to evaluate the elastic modulus through ultrasonic testing... more Purpose. The objective of our work was to evaluate the elastic modulus through ultrasonic testing of poly(methyl methacrylate-co-methacrylic acid) (PMMA/coMAA), a viscoelastic polymer similar to the commercial Eudragit®, to calculate this modulus, assuming a regular arrangement of interacting groups, and ultimately, assess the accuracy of microindentation as a means of evaluating elasticity in very small samples. Methods. Knoop indentation testing was performed on cast samples using a Tukon testing apparatus. Solid density and pulse echo testing employing a damped 15 MHz transducer served to quantify the elastic moduli. Using the Hoy method of calculation for molar attraction constants, and assuming pairwise addition, the modulus was calculated and compared with typical experimental values for amorphous and crystalline polymers. Results. Acoustic testing resulted in an average elastic modulus value of 5.67 ± 0.2 GPa for this copolymer, which concurs with literature values for PMMA. Acoustically derived experimental moduli when normalized and plotted against calculated values, resulted in a relationship, E/(1 − 2υ) = 17.0 (E coh + χcΔHm)/V + 6.9, similar to that predicted in theory. Conclusions. Indentation contact modeling does not adequately describe the real recovery under indentation. In contrast, acoustic testing of pharmaceutical materials affords a simple, reproducible means of characterizing moduli without impairing structural integrity. Acoustically derived moduli further afford insight into the intermolecular interactions, as expressed by the interaction energy terms.

Journal of Adhesion Science and Technology, 1993

... Eng. Commun. 33, 255 (1985). 9. EI Vargha-Butler, TK Zubovits, HA Hamza and AW Neumann, J. Di... more ... Eng. Commun. 33, 255 (1985). 9. EI Vargha-Butler, TK Zubovits, HA Hamza and AW Neumann, J. Dispersion Sci. Technol. ... Ind. 35, 719 (1973). 52. M. De Lourdes Costa and A. Baszkin, J. Pharm. Pharmacol. ... 17, 374 (1921). 60. MJ Groves and MH Alkan, J. Pharm. Pharmacol. ...

Colloids and Surfaces B-biointerfaces, 1995

Langmuir, 1993

The behavior of the piezoelectric acoustic wave sensor of the thickness-shear-mode type in variou... more The behavior of the piezoelectric acoustic wave sensor of the thickness-shear-mode type in various liquids has been characterized by the network analysis method. Models for this system based only on bulk liquid parameters fail to explain the behavior of the device with respect to series resonant frequency. Use of sensors with controlled surface free energy of the metal electrodes has been employed to demonstrate the importance of the liquid-solid interface in determining the response of the device. The contribution of the effects of surface roughness on the sensor response is discussed. Additionally, a previously-published four-layer model is successful in predicting the trends in values for the series resonant frequency for a set of mixed water-methanol solutions.

Journal of The American Pharmacists Association, 2007

... Wendy Duncan–Hewitt, PhD, is Dean of Pharmacy, St. ... E-mail: somma@pitt.edu Disclosure: Dr.... more ... Wendy Duncan–Hewitt, PhD, is Dean of Pharmacy, St. ... E-mail: somma@pitt.edu Disclosure: Dr. Somma McGivney is a fac-ulty consultant to the Rite Aid ... Acknowledgments: To Teresa McKaveney and Erik Rueter of the University of Pitts-burgh School of Pharmacy for assistance ...

Analyst, 1991

... Review. Analyst, 1991, 116, 881 - 890, DOI: 10.1039/AN9911600881. Thickness-shear-mode acoust... more ... Review. Analyst, 1991, 116, 881 - 890, DOI: 10.1039/AN9911600881. Thickness-shear-mode acoustic wave sensors in the liquid phase. A review Michael Thompson, Arlin L. Kipling, Wendy C. Duncan-Hewitt, Ljubinka V. Rajakovi and Biljana A. avi -Vlasak. ...

Objectives. To identify instructional and assessment problems leading to pharmacy students&#3... more Objectives. To identify instructional and assessment problems leading to pharmacy students' failure to retain pharmacokinetics abilities into the experiential year and develop an instructional methodology and abilities-based assessment tool to address the problem. Methods. Pharmacokinetic instructional methods were assessed and an abilities-based assessment tool was developed and utilized as a requirement for curricular progression. Both the instructional meth- odology and

Journal of Pharmaceutical Sciences, 1999

The present investigation was undertaken to examine the basic unit of densification: the particle... more The present investigation was undertaken to examine the basic unit of densification: the particle–particle indentation. The true interparticle contact area that is established during densification ultimately determines the quality of the tablet compact. By examining the interfacial contact between mutually indenting viscoelastic particles, the process of contact evolution may be represented in mathematical form through extension of the classical Hertzian elastic contact description to encompass material viscoelastic terms. In this way, the time-dependent response of materials to applied loads may be addressed explicitly. The effects of rates of applied loading and maximum load levels were also considered. This analysis was based on viscoelastic stress data collected using an instrumented Instron analyzer during the densification of PMMA/coMMA, a pharmaceutical polymeric coating material. A crossed cylinder matrix compaction geometry was used to simulate the geometry of two mutually indenting spherical particles. Numerical and graphical solutions delineating the relationship between contact area evolution and the prescribed loading force are presented. This particle–particle description of the contacting interface serves as a unit basis for describing the entire powder bed. The powder bed may ultimately be modeled as a collection of these particles in contact.

Pharmaceutical Research, 1989

The deformation kinetics of sucrose crystals were evaluated using the Vickers microindentation te... more The deformation kinetics of sucrose crystals were evaluated using the Vickers microindentation technique. A (100) face of a crystal of sucrose was indented for varying lengths of time at temperatures ranging from 23 to 103°C, and the deformation kinetics analysis proposed by Verrall et al. (1) was employed to calculate the strain rate and stress from the indentation time and the size of the indentation. Two kinetic parameters, the activation volume and the activation energy, were calculated from the experimental data and compared to those of other materials on normalized scales. The results suggest that the deformation kinetics of sucrose resemble those of ice, the crystal lattice of which is highly hydrogen-bonded, similar to that of sucrose.

 In the "Information Age," the profession of Engineering needs "critical thinkers" and "complex ... more  In the "Information Age," the profession of Engineering needs "critical thinkers" and "complex problem-solvers." Since most entering graduate students do not possess these abilities, it should be the responsibility of graduate programs to mentor their growth in addition to teaching them disciplinary knowledge and skills, but this is seldom done. Given that the desired abilities have a cognitive basis, we hypothesize that decisions about appropriate educational methods are best made by considering the development of graduate students' intellectual complexity.

Colloids and Surfaces, 1989

ABSTRACT

Pharmaceutical Research, 1994

The anisotropy of acetaminophen hardness was demonstrated using both Vickers and Knoop indentatio... more The anisotropy of acetaminophen hardness was demonstrated using both Vickers and Knoop indentation hardness measurements. Based on a model of Knoop hardness anisotropy proposed by Brookes et al. (1), it was concluded that plastic flow in acetaminophen crystals occurs primarily as a result of slip in the (010)(001) system. This conclusion was corroborated with the results of the Vickers indentation tests. The apparent brittleness of acetaminophen was rationalized because only one slip system appeared to be operative. Under these conditions generalized plastic flow cannot occur, since this requires the operation of at least five independent slip systems (2). The high stress concentrations that result from flow lead to fracture. Therefore acetaminophen is more precisely classified as being semiductile. When a material deforms plastically as a result of slip in only one slip system, considerable crystal realignment can occur during compaction. This in turn can facilitate capping during decompression and ejection, since the cleavage plane, (010), would become aligned with the direction of highest tensile stress.

Analytical Chemistry, 1992

... Sugawara, KF; Weetall. HH; Schucker, G. D. Anal. Chem. 1874, Marshal, MA; Mottola, HA Anal. .... more ... Sugawara, KF; Weetall. HH; Schucker, G. D. Anal. Chem. 1874, Marshal, MA; Mottola, HA Anal. ... Liquids Incorporating Interfacial Slip and Liquid Structure Wendy C. Duncan-Hewitt* Faculty of Pharmacy, University of Toronto, 19 Russell Street, Toronto, Ontario, M5S 1Al Canada ...

Journal of Materials Science Letters, 1989

Journal of Pharmaceutical Sciences, 1990

A model is presented which uses the hardness and elastic moduli of brittle crystals, determined u... more A model is presented which uses the hardness and elastic moduli of brittle crystals, determined using the Vickers microindentation test, to predict the uniaxial compaction behavior of compacts. A general approach first developed in the materials science field to predict the densification of particulate matter under hydrostatic loading was followed. Modifications to account for the effects of particle geometry and the closed-die loading conditions were considered. The model predicted the densification behavior of sucrose and adipic acid. It did not predict the densification of acetaminophen as well; however, the discrepancy between the experimental and predicted values may arise either from error associated with the evaluation of the elastic modulus using the microindentation test or from error in calculating the relative density of compacts which were observed to have partially laminated. The effects of error both in the hardness value and in the ratio of punch to die-wall stress on the predictive capability of the model were also discussed briefly.

Pharmaceutical Research, 1989

The brittleness of pharmaceutical crystals influences their ability to form compacts of acceptabl... more The brittleness of pharmaceutical crystals influences their ability to form compacts of acceptable quality. While many macroscopic methods are available to elucidate the fracture behavior of materials, the porosity, inhomogeneity, and anisotropy of pharmaceutical compacts render it difficult to interpret the results of these tests. Microindentation techniques may be used to evaluate both the flow and the fracture characteristics of small crystals, so that it is not necessary to test compacts. The flow and fracture behavior of sucrose, the model substance used in this study, were anisotropic. The fracture surface energy, derived from the average fracture toughness value, is of the same order of magnitude as the surface free energy, indicating that sucrose fractures in a brittle manner.

 Experiments with a variety of teaching techniques to improve meaningful learning often are ofte... more  Experiments with a variety of teaching techniques to improve meaningful learning often are often only partially successful, leaving many students struggling with the abstract and complex knowledge of the engineering disciplines. We hypothesize that decisions about appropriate teaching methods are best made b y considering the development of students' intellectual complexity using the "Crux Developmental Model" (CDM) synthesized from a number of disparate theories in the educational, developmental, and complexity literatures. The CDM and its application were assessed and improved over a three-year cycle in the context of a Science and Engineering Camp for teenagers. Our results supported the hypothesis that the CDM: (1) provides a rational method of selecting developmentally appropriate activities to teach specific skills and content, and; (2) provides a tool for customizing learning activities to maximize growth. According to the developmental model, the teenage participants in camp are working at the beginning of the same developmental transition that undergraduates are completing. Thus, we conclude this paper by proposing how the results of this study can be generalized to the undergraduate experience. Index Terms  cognitive complexity, curriculum planning, entering students, guided design, intellectual development, teaching methods.