D. Phil. Materials

Oxford University, 1996

M.Sc. Electronics

Nottingham University, 1989

B.Sc. Physics

Nottingham University, 1988

Mailing address:

Materials Science and Engineering Department

607 Taylor Road

Rutgers - The State University of New Jersey

Piscataway, New Jersey 08854

The primary theme of my research is understanding the nanomechanical behavior of materials.  I am particularly interested in the mechanics of nanocontacts and how mechanical behavior is affected by local variations in structure and chemistry. The studies span a wide range of materials from traditional metals and ceramics to biological tissues and organic crystals.

My background is in the physical sciences and my group uses a wide variety of physical characterization techniques to study nanomaterials. The instruments used include scanning probe microscopes (SPMs), nanoindentation systems, electron microscopes (TEM & SEM) and micro-Raman spectrometers. All of these instruments are available commercially, but frequently modifications and adaptations of the instruments are used to examine specific effects, for instance, the relationship between mechanical deformation and electrical properties or the effects of hydration on surface mechanical properties.

The research activities in my group can be split into the following four areas (follow the links below for relevant publications). In addition to these areas we are becoming increasingly involved in studies of organic crystals used in pharmaceutical and electronic applications:

Mechanics and geometry of nanoasperity contacts

When two surfaces are first brought into contact the interface between the surfaces consists of a series of individual nanoasperity contacts. The behavior of these nanoasperity contacts under mechanical loading is important in many processes including friction, wear, lubrication, thermal conduction and electrical conduction. We have been performing highly controlled experimental studies of the effects of surface chemistry, surface forces and kinetics on the mechanics and geometry of nanoasperity contacts. The experimental investigations are supported by analytical and numerical modeling. (publications)

Nanomechanics of dental tissues and dental materials

The oral cavity is a hostile environment where large variations in pH and temperature occur simultaneously with abrasive processes such as mastication and erosion due to fluid flow. Given these extreme conditions it is amazing that dental tissues such as enamel are able to survive without serious damage for as long as 70 years or more, especially given that dental enamel is not able to regenerate itself. In our research we have been studying the properties of healthy enamel, carious lesions and salivary pellicle. The research has shown the dramatic effect of chemical agents such as tannins, fluorides and organic acids on the nanomechanics of the tooth’s surface. (publications)

Effect of genetics on the nanomechanics, chemistry and structure of bone

Bone is a nanocomposite consisting of apatite crystals in a protein matrix. The protein is predominantly collagen, but there are many other non-collagenous bone proteins present including osteopontin, osteocalcin and fibrillin 1 & 2. We are examining the role of these proteins in determining the bone’s properties by studying bones from mice with specific single genes removed by genetic manipulation (knockout mouse models) and comparing these to their wildtype, background matched controls. The results show that each of the proteins is important in determining the bone’s properties, but their roles are very different. (publications)

Physical properties of nanocomposite ceramics, semiconductors and metals

The mechanical, electrical and thermal properties of many materials are intimately linked to each other and in addition they often show a strong dependence on the material’s structure. We have been studying these properties and their dependence on structure for many years and have identified a number of important phenomena including phase transformations, dislocation nucleation, rapid diffusion based reactions and mechanical failure at interfaces. (publications)