The lunch-debates at the RACAB

What is it?

The lunch-debates at the Royal Academy of Sciences and Arts of Barcelona (RACAB) are public gatherings that combine gastronomy with scientific and cultural outreach. These sessions are designed as a space for dialogue and reflection where experts and attendees share ideas on current issues in science and knowledge. It is a unique initiative to debate topics of academic interest in a relaxed and historic environment in the heart of Barcelona.
 

Tuesday, November 3rd, 2026

Schedule: 1:30 PM

Price: €30 per person, VAT included

Speaker: Dr. Josep A. Planell i Estany.

Member of the Technology Section of the RACAB (Royal Academy of Sciences and Arts of Barcelona)

Title: "High-Temperature Superconductivity: History of a Modern Odyssey"
Language of debate: Catalan

Abstract:

Bones constitute the skeleton of the human body. They not only provide bodily structure and allow locomotion and general mobility, but they also act as an organ and perform functions such as the generation of white and red blood cells, act as a reservoir for calcium and minerals, and participate in regulating the body's homeostasis. Bone is also a type of tissue that presents two main morphologies: cortical or compact bone and trabecular or spongy bone. It is a tissue that is supplied by blood vessels and is innervated. It is a tissue with the capacity to regenerate and features bone-forming cells – osteoblasts –, bone-resorbing cells – osteoclasts –, and bone-mineralizing cells – osteocytes –. Bone has a structure that can be considered similar to that of a composite material: a fibrous collagen matrix reinforced by calcium phosphate nanocrystals – non-stoichiometric hydroxyapatite –.

The geometry of the different bones adapts to the mechanical function to be performed, in order to optimize the mechanical characteristics that bones possess as a material. When analyzing the constitution of bones in different species, it is observed that the degree of mineralization is a variable that allows adaptation to different needs. As a material, bones behave elastically, although they also exhibit a certain degree of viscoelasticity. In this sense, the proportion of the three main elements that constitute them (mineral phase, organic phase, and water) is highly relevant. They exhibit higher mechanical resistance to compression than to tension, without having good behavior under shear stress. For a given applied mechanical stress, the degree of mineralization and the orientation of the collagen fibers will be the variables that determine crack propagation and tissue fracture. Bone regeneration is in many cases linked to the state of mechanical stresses to which it is subjected.

In summary, bone is both an organ and a tissue with a high degree of complexity that structures our organism. Its replacement with metals and alloys, as is often done in clinical practice, requires reflecting on the long-term behavior of the bone-substrate-implant assembly.