Prof. Serena M. Best

Department of Materials Science and Metallurgy，Cambridge, UK

Biologically inspired scaffolds for tissue repair and regeneration

Biography

Serena Best is Professor of Materials Science and a Fellow of St. John’s College. She is Deputy Head of the Department of Materials Science and Metallurgy and together with Prof. Ruth Cameron she directs the Cambridge Centre for Medical Materials. She is a Fellow of the Royal Academy of Engineering (FREng), President of the Institute of Materials, Minerals and Mining (IOM3) and a Fellow of the Societies Associated with Biomaterials Science and Engineering (FBSE). She was awarded both the Chapman Medal and the Kroll Medal for her work in biomaterials field. She is Editor of the Journal of Materials Science: Materials in Medicine and has been invited to act as a specialist on both national and international panels.

Abstract

Biomaterial scaffolds support tissue regeneration and play a key role in repair strategies for the human body. With the move from tissue repair- to cell-mediated tissue reconstruction and regeneration, there is an increasing need for the design of appropriate scaffolds to deliver these cells to diseased or injured tissue.  We are developing understanding and evidence of a number of key variables in the design of three dimensional porous architectures to ensure optimised cell infiltration and attachment. Our materials of choice are calcium phosphates and collagen.

Calcium phosphates have been used in orthopaedic surgery and hard tissue replacement for more than 40 years due to their similarity with the chemical composition of bone mineral. Hydroxyapatite (Ca₁₀(PO₄)₆(OH)₂) has been of particular interest due to the ability to control composition by making chemical substitutions in the crystal lattice, which encourage more rapid bone attachment. The biological response of the incorporation of substitutents such as carbonate, silicate and zinc ions in the hydroxyapatite structure is now well established. It is understood that small changes in elemental- and phase “impurity” content can influence the behaviour of osteoblasts in cell culture and that these can be optimised for the most beneficial clinical outcome.

Collagen is a highly versatile and bioactive natural macromolecule and understanding of the physics behind the production of lyophilised porous collagen scaffolds through ice crystal formation has allowed the design of processing conditions for a range of pore morphologies to mimic natural tissue and encourage cell migration. The importance of pore structure and morphology have begun to be understood for soft tissue applications, but the nature of the pore interconnections is not always considered in sufficient detail. Choice of scaffold biochemistry also allows us to balance scaffold “activity” and mechanical performance.

This talk will cover the recent work that has been undertaken to optimise the structure and properties of scaffolds for a range of clinical applications in both hard and soft tissue repair. 

Prof. Scott X. Mao

Department of Mechanical and Materials Science, University of Pittsburgh, USA

In-situ transmission electron microscopy on monatomic metallic glasses processing and deformation mechanism

Biography

Professor Scott X. Mao is William Kepler Whiteford Professor in Department of Mechanical Engineering and Materials Science, University of Pittsburgh. He obtained his Ph.D in Tohuku University in 1988, and he worked in MIT and Harvard University as post-doctor and visiting faculty. He was chair of mechanical behavior of materials committee in TMS/ASM and has received a number of research excellence awards from TMS and Chancellor Award. Dr. Mao has published over 200 papers with H index of 54 and given over one hundred invited talks in the area of (1) Monatomic metallic glass formation from pure metals through in-situ ultrafast liquid quenching under TEM; (2) deformation/twinning, phase transformation processes under in-situ transmission electron microscope; (3) in-situ TEM on grain boundary mediated plasticity on nanocrystalline materials; (4) in-situ electrochemical lithiation process in lithium-ion battery including Nature, Science, Nature Materials. Currently he is editor of Advance in Metallurgical and Material Engineering, associate editor for Advances in Materials Research, Guest-editor for Material Science & Engineering International Journal.

Abstract                                                                              

I will talk on the overview of recently-developed in-situ heat treatment, in-situ electrochemical lithiation (lithium ion battery) and in-situ nanomechanics under high resolution transmission electron microscope with focus on interface-mediated phases transformation and deformation.  Then focus will be placed on in-situ TEM on vitrification of single-element metallic liquids which is notoriously difficult. True laboratory demonstration of the formation of monatomic metallic glass has been lacking.  An experimental approach to vitrify monatomic metallic liquids by achieving an unprecedentedly high liquid-quenching rate of 10¹⁴ Ks. Melts of pure refractory body-centred cubic tantalum and vanadium are successfully vitrified through liquid/solid interface driven process. With in situ transmission electron microscopy observation, we investigated the formation condition of the monatomic metallic glasses as obtained. The availability of monatomic metallic glasses, being the simplest glass formers, offers unique possibilities for studying the structure and property relationships of glasses. The ultrahigh cooling rate makes it possible to explore the fast kinetics and structural behavior of supercooled metallic liquids within the nanosecond to picosecond regimes. The deformation of the disordered structure is compared with its ordered crystal structure in terms of STZ and dislocation processes under in-situ transmission electron microscope.

Prof. Guangwen Zhou

Department of Mechanical Engineering& Materials Science and Engineering Program，State University of New York

Atomic-Scale Mechanism of Unidirectional Oxide Growth

Biography

Guangwen Zhou is a distinguished professor of "hundred talents program" in Hunan province. He obtained bachelor's degree, master's degree and doctor's degree in Xiangtan University, Beijing University of technology and University of Pittsburgh in 1993, 1996 and 2003 respectively. Currently, he is an associate professor (tenured position) at the state University of New York. In 2013, he was selected into "hundred talents program" in Hunan province. He has been engaged in the research of material oxidation mechanism for a long time.

Abstract

A fundamental knowledge of the unidirectional growth mechanisms is required for precise control on size, shape, and thereby functionalities of nanostructures. Using transmission electron microscopy that spatially and temporally resolves CuO nanowire growth during the oxidation of copper, here we provide direct evidence of the correlation between unidirectional crystal growth and bicrystal boundary diffusion. Based on atomic scale observations of the upward growth at the nanowire tip and oscillatory downward growth of atomic layers on the nanowire sidewall, we clearly show that bicrystal boundary diffusion is the mechanism by which Cu atoms are delivered from the nanowire root to the tip. Together with density-functional theory calculations, we further show that the asymmetry in the corner-crossing barriers promotes the unidirectional oxide growth by hindering the transport of Cu atoms from the nanowire tip to the sidewall facets. We expect broader applicability of our results in manipulating the growth of nanostructured oxides by controlling the bicrystal boundary structure that favors anisotropic diffusion for unidirectional, one-dimensional crystal growth for nanowires or isotropic diffusion for two-dimensional platelet growth.

Prof. Ze Zhang

School of Materials Science and Engineering, Zhejiang University

In-situ Electron Microscopy Study of Advanced Material under High Temperature and Load

Biography

Prof. Ze Zhang got his Ph.D on 1987 from the Institute of Metal Research, Chinese Academy of Sciences and worked as a research professor from 1991- 2003 in an Electron Microscopy Center of Chinese Academy of Science. He was a professor of Beijing University of Technology on 2003-2010, and is a professor of Zhejiang University from 2010.

His research interests focused on electron microscopy study of advanced materials. He was one of the earlier researchers worked on quasicrystals in 1980s. In recent years, Prof. Zhang together with his research team has developed an advanced microscopy technique, with which in-situ external field can be introduced into the microscope retaining the atomic resolution. They successfully apply this advanced technique on in-situ electron microstructure study of the size effects of structural materials, especially on abnormal elasticity and strength of Ni-, Fe-, Cu-, Au-, Zr-, and some alloys. Some new phenomena and laws are dug out with regard to the relation between special properties and structure evolution. Moreover, the mechanism of the unusual transformation in nano-scale for the classic metal materials is revealed.

Prof. Zhang was elected as a member of Chinese Academy of Sciences on 2001. He serves as the chair of Academic Committee board of Zhejiang University since 2012. He is the author of more than 350 papers published on international peer reviewed journals including Nature, Science, Nature Materials, JACS, PRL, etc. These papers have been cited more than 7500. He is a chief scientist of national basic research program of China, the president of China Association for instrumental Analysis, and the president of Asia Pacific Electron Microscopy Association since 2012.