Abstrat: The talk will be split into 2 parts

Part 1: “Carrying the Hooke legacy forward: A measure of stress at the nanoscopic scale”
The need to bridge mechanical, chemical, and crystallographic phenomena into a unified treatment of solid matter has been the main driving force in developing the so-called “continuum theory”. The possibility of working out constitutive equations, which form a most essential joint among different laws of nature, is indeed where the continuum theory has gained much of persuasion among scientists and technologists. However, this is definitely inadequate when we attempt to develop modern technologies at the nanometer scale, which flourish because of their discrete, multiphysics, and multiscale nature. While the basics of mechanics, chemistry, and crystallography are yet thought within compartmentalized and sectionalist enclaves, modern scientists have recently realized the need of a unified approach down to the scale of the single nanometer, and newly conceived the computational discipline of “multiphysics”. A typical case of continuum theory breakdown is represented by the concept of stress at the nanometer scale. In this presentation, an experimental approach to nanomechanics in the scanning electron microscope is shown. The electron beam is among the finest and most flexible fingertips available for probing solid matter. When the electron beam impacts a solid, emission of cathodoluminescence light is observed. The origin of light might be of different nature, namely bandgap, intra-band gap from defective clusters, or luminescent impurity clusters. However, whatever the physical origin of light, a common characteristic is the relation-ship of its wavelength on mechanical strain/stress. In this presentation, we describe cathodoluminescence-based nano-scale stress assessments and show hyperspectral images of light wavelength and intensity, which give direct access to the trace of the stress tensor and concentration of luminescent clusters, respectively. The method is front-runner in spatial resolution and in measurement precision of the stress magnitude. Moreover, in the case of light emission from defective or doped clusters, information becomes also available of their concentration, thus locating local off-stoichiometric drifts.

Part 2: “Silicon nitride: A bioceramic with a gift”
In the closing decades of the 20^th century, silicon nitride (Si₃N₄) was extensively developed for high-temperature gas-turbine applications. Technologists attempted to take advantage of its superior thermal and mechanical properties to improve engine reliability and fuel economy. Yet, this promise was never realized in spite of the worldwide research, which was conducted at that time. Notwithstanding this disappointment, its use in medical applications in the early 21^st century has been an unexpected gift. While retaining all of its engineered mechanical properties, it is now recognized for its peculiar surface chemistry. When immersed in an aqueous environment, the slow elution of silicon and nitrogen from its surface enhances healing of soft and osseous tissue, inhibits bacterial biofilm formation, and eradicates viruses. These benefits permit it to be used in a wide array of different disciplines inside and outside of the human body including orthopedics, dentistry, virology, agronomy, and environmental remediation. Given the global public health threat posed by mutating viruses and bacteria, silicon nitride offers a valid and straightforward alternative approach to fighting these pathogens. However, there is a conundrum behind these recent discoveries: How can this unique bioceramic be both friendly to mammalian cells while concurrently lysing invasive pathogens? This unparalleled characteristic can be explained by the pH-dependent kinetics of two ammonia species – NH₄⁺ and NH₃ – both of which are leached from the wet Si₃N₄ surface.

Biosketch: Giuseppe Pezzotti is Vice President of the Kyoto Institute of Technology and Director of the International Center since the year 2017, and a full tenured professor and leader of the Ceramic Physics Laboratory since the year 2000. He graduated summa cum laude in mechanical engineering from Rome University “La Sapienza”, Italy, in 1984 and holds three doctoral degrees in materials engineering (ceramic materials; Osaka University), solid state physics (quantum mechanics; Kyoto University), and medical sciences (orthopedics; Tokyo Medical University), all obtained in Japan, the country where he has lived the past 32 years. Fluent in Japanese, and capable to read and write it at a nearly native level, he was one of the first foreign nationals to obtain a tenured full professor position in a Japanese Government University and is now the first and only western-born Vice President in a National Japanese University. From 2002 to 2012, Professor Pezzotti served as the director of the Research Institute for Nanoscience at the Kyoto Institute of Technology. From 2005 to 2015, he has been an adjunct professor at the Department of Orthopaedic Research of Loma Linda University, Loma Linda, California. Since 2009, he obtained an Invited Professorship from the Department of Medical Engineering of Osaka University, from 2010 to 2017 he has been a Visiting Professor at the Department of Molecular Cell Physiology of Kyoto Prefectural University of Medicine, since 2016 he is a Guest Professor at the Department of Orthopedics of the Tokyo Medical University, and since 2018 he serves as an Adjunct Professor at the Department of Immunology of the Kyoto Prefectural University of Medicine. Prof. Pezzotti has published about 660 scientific papers, 1 book as a single author, 13 book chapters, and holds 11 patents, including a world patent regarding nanoscale stress microscopy in the scanning electron microscope. He has so far licensed his intellectual properties to more than 20 major industrial firms around the world and served as their consultant. His book entitled “Advanced Materials for Joint Implants” (published in 2013) has quickly become a landmark for scientists and medical doctors working in the field of joint arthroplasty. In 2013, Professor Pezzotti became a Fellow of the Academy of Science (Bologna Institute) in appreciation of his advanced studies of Raman spectroscopy, linking quantum mechanics to medical sciences. In 2015 and 2016, the City of Kyoto awarded him with a City Prize for two years consecutively for his contribution to developing and progressing the internationalization of the City of Kyoto. In 2017, he has been awarded of the prestigious Prize for Scientific Research of the Ministry of Education of Japan (MEXT) for his invention of the nanoscale stress microscope and his fundamental contribution to the Japanese industrial world