Margaret Libonati Leahy

Dr. Libonati wanted to be a physician from an early age, but she knew that she could not afford to attend college right after high school so she decided to attend nursing school with plans to work her way through college and then medical school. After graduating from St. Joseph’s Nursing School she enrolled as a chemistry major in the Chestnut Hill College Pre-Med program. At the end of her second year she learned that Jefferson Medical College was planning to accept women for the first time. She soon became one of the first women in Jefferson’s Class of 1965. After graduating from Jefferson Dr. Libonati had a rotating internship at Philadelphia General Hospital and then a two year residency in Anesthesia as part of the PGH-Penn program. She then accepted a clinical fellowship in London where she worked at St. Thomas Hospital and Great Ormond Street Hospital in Pediatrics. After returning to the United States she began a fellowship at the University of Pennsylvania before becoming an assistant professor at the University of Colorado. In 1972 Dr. Libonati moved back to Philadelphia to work first at the University of Pennsylvania Hospital as an Assistant Professor and then at Wills Eye Hospital and Children’s Hospital of Philadelphia.https://jdc.jefferson.edu/oral_histories/1005/thumbnail.jp

Understanding the structure-property relationship in cortical bone to design a biomimetic composite

Bone is a hot topic for researchers, interested in understanding the structure-related properties of the tissue and the effect of aging, disease and therapies on that. A thorough understanding of the mechanical behavior of bone can be helpful to medical doctors to predict the fracture risk, but it can also serve as a guideline for engineers for the design of de novo biomimetic materials. In this paper, we show a complete characterization of cortical bone under static loading (i.e. tensile, compressive, three-point bending) and we carried out tests in presence of a crack to determine the fracture toughness. We performed all the tests on wet samples of cortical bone, taken from bovine femurs, by following the ASTM standards designed for metals and plastics. We also performed microscopic observations, to get an insight into the structure-property relationship. We noted that the mechanical response of bone is strictly related to the microstructure, which varies depending on the anatomical position. This confirms that the structure of bone is optimized, by nature, to withstand the different types of loads generally occurring in different body areas. The same approach could be followed for a proper biomimetic design of new composites

An aspect of the object habit: Pliny the Elder, audience and politics

This paper looks at an aspect of the ‘object habit’ by considering the motivations behind an ancient technical text, Pliny the Elder’s Natural History. The text is an ‘encyclopaedia’ of knowledge covering a vast range of subjects and approaches by studying objects including things found in nature and worked by man. For Pliny, these phenomena shared enough to be considered together while presenting an inventory of the resources in the Roman world and thus controlled by the emperor Titus (AD 79–81), to whom the work is addressed. The collection of knowledge for Pliny is a political act. The Natural History’s collapse of distinctions between objects, animate or inanimate, worked by man or in a natural state, as well as its insistence on political motivations for collecting objects and knowledge, serve as starting place for considering the ‘object habit’ and the impact of politics on collecting. Two examples are discussed: a Benin ‘bronze’ at a Cambridge college, and three giraffes gifted to the superpowers of nineteenth-century Europe

'A selection of minor antiquities': a multi-sited view on collections from excavations in Egypt

This article draws upon the ‘Artefacts of Excavation’ (2014–17) project, which is investigating the worldwide distribution of finds from British-led excavations in Egypt between 1880 and 1980. The departure point for the present article is the earliest phase of these distributions. The potential for multi-sited ethnographic approaches to illuminate the history and significance of such collections is explored. It is argued that, through such analyses, it is possible to chart shifting tensions in the status of objects as they were collected, circulated and re-evaluated between the field and the museum. The article concludes by suggesting that multi-sited frameworks may also be able to re-animate ‘orphaned’ archaeological collections, some of which could be at risk from commercial sale

A review of thermographic techniques for damage investigation in composites

The aim of this work is a review of scientific results in the literature, related to the application of thermographic techniques to composite materials. Thermography is the analysis of the surface temperature of a body by infrared rays detection via a thermal-camera. The use of this technique is mainly based on the modification of the surface temperature of a material, when it is stimulated by means of a thermal or mechanical external source. The presence of defects, in fact, induces a localized variation in its temperature distribution and, then, the measured values of the surface temperature can be used to localize and evaluate the dimensions and the evolution of defects. In the past, many applications of thermography were proposed on homogeneous materials, but only recently this technique has also been extended to composites. In this work several applications of thermography to fibres reinforced plastics are presented. Thermographic measurements are performed on the surface of the specimens, while undergoing static and dynamic tensile loading. The joint analysis of thermal and mechanical data allows one to assess the damage evolution and to study the damage phenomenon from both mechanical and energetic viewpoints. In particular, one of the main issues is to obtain information about the fatigue behaviour of composite materials, by following an approach successfully applied to homogenous materials. This approach is based on the application of infrared thermography on specimens subjected to static or stepwise dynamic loadings and on the definition of a damage stress, D, that is correlated to the fatigue strength of the material. A wide series of experimental fatigue tests has been carried out to verify if the value of the damage stress, D, is correlated with the fatigue strength of the material. The agreement between the different values is good, showing the reliability of the presented thermographic techniques, to the study of composite damage and their fatigue behaviour

Problemas atuais da juticultura amazônica.

No presente trabalho, os autores procuraram expor os problemas atuais que entravam o desenvolvimento da juticultura amazônica, ressaltando a importância marcante da produção das fibras desta tiliácea como fonte da manutenção do mercado interno brasileiro de matéria prima necessária ao abastecimento do parque nacional de aniagem. Os problemas considerados, no trabalho em questão, foram: 1) problemas de ordem agrícola, 2) problemas de ordem sócio-econômica. Procurou-se, também, de forma sintética, expor a situação do mercado nacional e as possibilidades de exportação. Como conclusão, os autores admitem a necessidade urgente e prioritária de se estimular econômicamente o juticultor a fim de que se possa posteriormente mostrar que a quantidade e qualidade do produto depende em grande parte dos problemas culturais e tecnológicos.Separata da Pesquisa Agropecuária Brasileira, v. 1, p. 1-6, 1966

Design and characterization of a biomimetic composite inspired to human bone

Many biological materials are generally considered composites, made of relatively weak constituents and with a hierarchical arrangement, resulting in outstanding mechanical properties, difficult to be reached in man-made materials. An example is human bone, whose hierarchical structure strongly affects its mechanical performance, toughness in particular, by activating different toughening mechanisms occurring at different length scales. At microscale, the principal toughening mechanism occurring in bone is crack deflection. Here, we study the structure of bone and we focus on the role of the microstructure on its fracture behaviour, with the goal of mimicking it in a new composite. We select the main structural features, the osteons, which play a crucial role in leading to crack deflection, and we reproduce them in a synthetic composite. The paper describes the design, manufacturing and characterization of a newly designed composite, whose structure is inspired to the Haversian structure of cortical bone, and that of a classic laminate developed for comparative reasons. We conclude with a critical discussion on the results of the mechanical tests carried out on the new composite and on the comparative laminate, highlighting strengths and shortcomings of the new biomimetic material

Studio del comportamento meccanico dell'osso corticale

Questo lavoro è incentrato sullo studio del comportamento meccanico dell’osso, ed in particolare a frattura, al fine di individuare elementi chiave della struttura ossea da riprodurre in un materiale bio-ispirato ex novo. L’osso è generalmente considerato un composito, caratterizzato da una struttura gerarchica a più livelli, dove ogni componente gioca un ruolo fondamentale nel determinare la risposta meccanica. Pertanto, per poter riprodurre le sue caratteristiche è necessario studiare attentamente la struttura e come questa influenza le performance finali. In questo lavoro sono state eseguite prove sperimentali su provini di osso corticale, prelevati dalla diafisi di un femore bovino. I campioni sono stati adeguatamente conservati in soluzione salina al fine di preservare le caratteristiche del materiale, intrinsecamente legate alla sua igroscopicità. Le prove sono state eseguite in accordo alle normative ASTM per materiali metallici e plastici, seguendo l’approccio più comunemente usato in letteratura. I risultati ottenuti dalle prove trovano riscontro con quanto presente in letteratura. Particolarmente utili ai fini dello studio del legame tra struttura e proprietà sono risultate le osservazioni al microscopio, che hanno consentito di individuare i vari componenti microstrutturali e i meccanismi di danneggiamento del materiale stesso

A multiscale XFEM approach to investigate the fracture behavior of bio-inspired composite materials

In the setting of emerging approaches for material design, we investigate the use of the extended finite element method (XFEM) to predict the behavior of a newly designed bone-inspired fiber-reinforced composite and to elucidate the role of the characteristic microstructural features and interfaces on the overall fracture behavior. The outcome of the simulations, showing a good agreement with the experimental results, reveals the fundamental role played by the heterogeneous microstructure in altering the stress field, reducing the stress concentration at the crack tip, and the crucial role of the interface region (i.e. cement line) in fostering the activation of characteristic toughening mechanisms, thus increasing the overall flaw tolerance of the composite