Jerome B. Johnson, Ph.D., is Research Professor (Ret.) at the Institute of Northern Engineering and Senior Advisor to the Alaska Center for Energy and Power, both at the University of Alaska, Fairbanks. Johnson founded and directed the Alaska Hydrokinetic Energy Research Center, chaired the US Technical Advisory Group for International Electrotechnical Commission (IEC) Technical Committee 114, setting standards for characterizing river hydrokinetic energy potential; Assistant Editor of the J. Glaciology; participating scientist on NASA Mars Polar Lander and Mars Exploration Rovers missions and for JPL’s Mars thermal drill design. He led national and international project teams in conducting problem-specific applied research for NASA, the U.S. Army, Michelin Tire Company, U.S Department of Energy, Honeybee Robotics, Alaska Department of Energy, Department of Interior, Cornell University, and Johns Hopkins University. Awards include Haley Space Flight Award, NASA MER Mission Group Award, ERDC-CRREL Employee Hall of Fame, Army Research and Study Fellowship, Alaska Innovators Hall of Fame, UAF Innovators Hall of Fame, and NASA Langley Director’s Group award for the Asteroid Robotic Redirect Mission Concept Study. He holds four patents, licensed to three companies. Johnson is a fellow of the National Academy of Inventors. Johnson co-founded Coupi, Inc., a company focused on improving products and manufacturing through complex simulation and visualization technology. He has published in 140+ journals and books.
Characterizing punch sticking propensity of pharmaceutical powders using a calibrated mechanistic DEM elastic-plastic model simulation
Abstract Empirical studies demonstrate that pharmaceutical powder punch sticking is influenced by adhesion between active pharmaceutical ingredients (API) and excipients, and the ratio of API to excipient particle size (i.e., specific surface area). Increased adhesion of API to excipients and a smaller particle size ratio reduces punch sticking risk and severity . We characterize the punch sticking propensity of pharmaceutical powders that include sticking risk and severity. We develop a new plastic contact model, with contact bridge bond formation and breakage, based on a similarity analysis  to create a hybrid local contact model by coupling plasticity with the Hertzian elastic contact model. The model is calibrated using compaction loading/unloading data, tensile strength, and punch API sticking weight data for API, excipient, and formulated powders. Sticking risk increases as the punch adhesion force required to pull API from a formulated powder during compaction decreases. Sticking severity increases with higher API sticking weight per compaction cycle. Punch sticking risk is a function of powder cohesion/adhesion properties and powder formulation while punch sticking severity is a function both powder and formulation properties and their interaction with punch surfaces. Characterizing punch sticking using a mechanistic model allows examination of the individual roles that powder cohesion/adhesion, ratio of API to excipient particle size, and interaction of API with punch surfaces have on sticking risk and severity. Mechanistic model simulation of punch sticking allows a wide range of powder formulation combinations and punch designs to be assessed for punch sticking risk and severity without the time and cost of an extensive testing program.
 M. Capece, “The Role of Particle Surface Area and Adhesion Force in the Sticking Behavior of Pharmaceutical Powders,” J. Pharm. Sci., p. 3803-3813, Aug. 2019, doi: 10.1016/j.xphs.2019.08.019.  S. Paul and C. C. Sun, “Modulating Sticking Propensity of Pharmaceuticals Through Excipient Selection in a Direct Compression Tablet Formulation,” Pharm. Res., vol. 35, no. 6, p. 113, Jun. 2018, doi: 10.1007/s11095-018-2396-3.  S. Garner, J. Strong, and A. Zavaliangos, “Study of the die compaction of powders to high relative densities using the discrete element method,” Powder Technol., vol. 330, pp. 357– 370, May 2018, doi: 10.1016/j.powtec.2018.02.015