Simon P. Ringer

Bio: Simon P. Ringer is an academic researcher from University of Sydney. The author has contributed to research in topics: Atom probe & Microstructure. The author has an hindex of 71, co-authored 578 publications receiving 21195 citations. Previous affiliations of Simon P. Ringer include Monash University, Clayton campus & National Cheng Kung University.

Carbon Nanomaterials in Biosensors: Should You Use Nanotubes or Graphene?

Abstract: From diagnosis of life-threatening diseases to detection of biological agents in warfare or terrorist attacks, biosensors are becoming a critical part of modern life. Many recent biosensors have incorporated carbon nanotubes as sensing elements, while a growing body of work has begun to do the same with the emergent nanomaterial graphene, which is effectively an unrolled nanotube. With this widespread use of carbon nanomaterials in biosensors, it is timely to assess how this trend is contributing to the science and applications of biosensors. This Review explores these issues by presenting the latest advances in electrochemical, electrical, and optical biosensors that use carbon nanotubes and graphene, and critically compares the performance of the two carbon allotropes in this application. Ultimately, carbon nanomaterials, although still to meet key challenges in fabrication and handling, have a bright future as biosensors.

Atom Probe Microscopy

Abstract: Preface Acknowledgements List of Acronyms and Abbreviations List of Terms List of Non-SI Units and Constant Values PART I Fundamentals 1. Introduction 2. Field Ion Microscopy 2.1 Principles 2.1.1 Theory of field ionisation 2.1.2 'Seeing' atoms - field ion microscopy 2.1.3 Spatial resolution of the FIM 2.2 Instrumentation and Techniques for FIM 2.2.1 FIM instrumentation 2.2.2 eFIM or digital FIM 2.2.3 Tomographic FIM Techniques 2.3 Interpretation of FIM Images 2.3.1 Interpretation of the image in a pure material 2.3.2 Interpretation of the image for alloys 2.3.3 Selected applications of the FIM 2.3.4 Summary 3 From Field Desorption Microscopy to Atom Probe Tomography 3.1 Principles 3.1.1 Theory of field evaporation 3.1.2 'Analysing' atoms one-by-one: atom probe tomography 3.2 Instrumentation and Techniques for APT 3.2.1 Experimental setup 3.2.2 Field desorption microscopy 3.2.3 High voltage pulsing techniques 3.2.4 Laser pulsing techniques 3.2.5 Energy compensation techniques Part II Practical aspects 4. Specimen Preparation 4.1 Introduction 4.1.1 Sampling issues in microscopy for materials science and engineering 4.1.2 Specimen requirements 4.2 Polishing methods 4.2.1 The electropolishing process 4.2.2 Chemical polishing 4.2.3 Safety Considerations 4.2.4 Advantages and limitations 4.3 Broad ion beam techniques 4.4 Focused ion beam techniques 4.4.1 Cut-away methods 4.4.2 Lift-out methods 4.4.3 The final stages of FIB preparation 4.4.4 Understanding and minimising ion beam damage and other artefacts 4.5 Deposition methods 4.6 Methods for organic materials 4.6.1 Polymer microtips 4.6.2 Self-assembled monolayers 4.6.3 Cryopreparation 4.7 Other Methods 4.7.1 Dipping 4.7.2 Direct growth of suitable structures 4.8 Specimen geometry issues 4.8.1 Influence of specimen geometry on atom probe data 4.8.2 Stress states and specimen rupture 4.9 A guide to selecting an appropriate specimen preparation method 5. Experimental protocols in Field Ion Microscopy 5.1 Step-by-step procedures for FIM 5.2 Operational space of the field ion microscope 5.2.1 Imaging gas 5.2.2 Temperature 5.2.3 The best image field 5.2.4 Other parameters 5.2.5 Summary 6. Experimental protocols 6.1 Specimen alignment 6.2 Aspects of mass spectrometry 6.2.1 Detection of the ions 6.2.2 Mass spectra 6.2.3 Formation of the mass spectrum 6.2.4 Mass resolution 6.2.5 Common artefacts 6.2.6 Elemental identification 6.2.7 Measurement of the composition 6.2.8 Detectability 6.3 Operational space 6.3.1 Flight path 6.3.2 Temperature / Pulse fraction 6.3.3 Selecting the pulsing mode 6.3.4 Pulse rate 6.3.5 Detection rate 6.4 Specimen failure 6.5 Data quality assessment 6.5.1 Field desorption map 6.5.2 Mass spectrum 6.5.3 Multiple events 6.5.4 Discussion 7. Tomographic reconstruction 7.1 Projection of the ions 7.1.1 Estimation of the electric field 7.1.2 Field distribution 7.1.3 Ion trajectories 7.1.4 Point projection 7.1.5 Radial projection with angular compression 7.1.6 Discussion 7.2 Reconstruction 7.2.1 General considerations 7.2.2 Bas et al. protocol 7.2.3 Geiser et al. protocol 7.2.4 Gault et al. protocol 7.2.5 Reflectron-fitted instruments 7.2.6 Summary and discussion 7.3 Calibration of the parameters 7.3.2 Discussion 7.3.3 Limitations of the current procedure 7.4 Common artefacts 7.4.2 Correction of the reconstruction 7.5 Perspectives on the reconstruction in atom probe tomography 7.5.1 Advancing the reconstruction by correlative microscopy 7.5.2 In correlation with simulations 7.5.3 Alternative ways to exploit existing data 7.6 Spatial resolution in APT 7.6.1 Introduction 7.6.2 Means of investigation 7.6.3 Definition 7.6.4 On the in-depth resolution 7.6.5 On the lateral resolution 7.6.6 Optimisation of the spatial resolution 7.7 Lattice rectification PART III Applying atom probe techniques for materials science 8. Analysis techniques for atom probe tomography 8.1 Characterising the Mass Spectrum 8.1.1 Noise Reduction 8.1.2 Quantifying Peak Contributions via Isotope Natural Abundances 8.1.3 Spatially dependent identification of mass peaks 8.1.4 Multiple Detector Event Analyses 8.2 Characterising the chemical distribution 8.2.1 Quality of atom probe data 8.2.2 Random comparators 8.3 Grid-based counting statistics 8.3.1 Voxelisation 8.3.2 Density 8.3.3 Concentration analyses 8.3.4 Smoothing by delocalisation 8.3.5 Visualisation techniques based on iso-concentration and iso-density 8.3.6 One-dimensional profiles 8.3.7 Grid-based frequency distribution analyses 8.4 Techniques for describing atomic architecture 8.4.1 Nearest neighbour distributions 8.4.2 Cluster Identification Algorithms 8.4.3 Detection Efficiency Influence on Nanostructural Analyses 8.5 Radial Distribution 8.5.1 Radial distribution and pair correlation functions 8.5.2 Solute Short Range Order Parameters 8.6 Structural Analyses 8.6.1 Fourier Transforms for APT 8.6.2 Spatial Distribution Maps 8.6.3 Hough Transform 9. Atom probe microscopy and materials science 9.1 Compositional analysis 9.2 Defects/ dislocations 9.3 Solid solutions / clustering 9.4 Precipitates 9.5 Ordering reaction 9.6 Spinodal decomposition 9.7 Interface/boundaries/layers 9.8 Amorphous materials 9.9 Atom probe crystallography Appendices A. Appendix - chi2 distribution B. Appendix - Polishing chemicals and conditions C. File formats used in APT POS EPOS RNG RRNG ATO ENV PoSAP Cameca root files - RRAW, RHIT, ROOT D. Appendix - Image Hump Model Predictions E. Appendix - Essential Crystallography for APT Bravais lattices Notation Structure factor (F) rules for BCC, FCC, HCP Interplanar spacings (dhkl) Interplanar angles (phi) F. Stereographic Projections and commonly observed desorption maps Stereographic projection for the most commonly found structures and orientations Face-centred cubic Body-centred cubic Diamond cubic Hexagonal close-packed G. Periodic tables H. Kingham Curves I. List of elements and associated mass to charge ratios J. Possible element identity of peaks as a function of their location in the mass spectrum

Carbon nanotubes for biological and biomedical applications

Abstract: Ever since the discovery of carbon nanotubes, researchers have been exploring their potential in biological and biomedical applications. The recent expansion and availability of chemical modification and bio-functionalization methods have made it possible to generate a new class of bioactive carbon nanotubes which are conjugated with proteins, carbohydrates, or nucleic acids. The modification of a carbon nanotube on a molecular level using biological molecules is essentially an example of the 'bottom-up' fabrication principle of bionanotechnology. The availability of these biomodified carbon nanotube constructs opens up an entire new and exciting research direction in the field of chemical biology, finally aiming to target and to alter the cell's behaviour at the subcellular or molecular level. This review covers the latest advances of bio-functionalized carbon nanotubes with an emphasis on the development of functional biological nano-interfaces. Topics that are discussed herewith include methods for biomodification of carbon nanotubes, the development of hybrid systems of carbon nanotubes and biomolecules for bioelectronics, and carbon nanotubes as transporters for a specific delivery of peptides and/or genetic material to cells. All of these current research topics aim at translating these biotechnology modified nanotubes into potential novel therapeutic approaches.

Nanostructural hierarchy increases the strength of aluminium alloys

Abstract: Increasing the strength of metallic alloys while maintaining formability is an interesting challenge for enabling new generations of lightweight structures and technologies. In this paper, we engineer aluminium alloys to contain a hierarchy of nanostructures and possess mechanical properties that expand known performance boundaries-an aerospace-grade 7075 alloy exhibits a yield strength and uniform elongation approaching 1 GPa and 5%, respectively. The nanostructural architecture was observed using novel high-resolution microscopy techniques and comprises a solid solution, free of precipitation, featuring (i) a high density of dislocations, (ii) subnanometre intragranular solute clusters, (iii) two geometries of nanometre-scale intergranular solute structures and (iv) grain sizes tens of nanometres in diameter. Our results demonstrate that this novel architecture offers a design pathway towards a new generation of super-strong materials with new regimes of property-performance space.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

Fast parallel algorithms for short-range molecular dynamics

Abstract: Three parallel algorithms for classical molecular dynamics are presented. The first assigns each processor a fixed subset of atoms; the second assigns each a fixed subset of inter-atomic forces to compute; the third assigns each a fixed spatial region. The algorithms are suitable for molecular dynamics models which can be difficult to parallelize efficiently—those with short-range forces where the neighbors of each atom change rapidly. They can be implemented on any distributed-memory parallel machine which allows for message-passing of data between independently executing processors. The algorithms are tested on a standard Lennard-Jones benchmark problem for system sizes ranging from 500 to 100,000,000 atoms on several parallel supercomputers--the nCUBE 2, Intel iPSC/860 and Paragon, and Cray T3D. Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems. For large problems, the spatial algorithm achieves parallel efficiencies of 90% and a 1840-node Intel Paragon performs up to 165 faster than a single Cray C9O processor. Trade-offs between the three algorithms and guidelines for adapting them to more complex molecular dynamics simulations are also discussed.

Phd by thesis

Abstract: Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Principles of nanoparticle design for overcoming biological barriers to drug delivery

Abstract: Biological barriers to drug transport prevent successful accumulation of nanotherapeutics specifically at diseased sites, limiting efficacious responses in disease processes ranging from cancer to inflammation. Although substantial research efforts have aimed to incorporate multiple functionalities and moieties within the overall nanoparticle design, many of these strategies fail to adequately address these barriers. Obstacles, such as nonspecific distribution and inadequate accumulation of therapeutics, remain formidable challenges to drug developers. A reimagining of conventional nanoparticles is needed to successfully negotiate these impediments to drug delivery. Site-specific delivery of therapeutics will remain a distant reality unless nanocarrier design takes into account the majority, if not all, of the biological barriers that a particle encounters upon intravenous administration. By successively addressing each of these barriers, innovative design features can be rationally incorporated that will create a new generation of nanotherapeutics, realizing a paradigmatic shift in nanoparticle-based drug delivery.