Ivan P. Parkin

Bio: Ivan P. Parkin is an academic researcher from University College London. The author has contributed to research in topics: Chemical vapor deposition & Thin film. The author has an hindex of 84, co-authored 952 publications receiving 33999 citations. Previous affiliations of Ivan P. Parkin include King's College London & Open University.

Mechanochemistry: opportunities for new and cleaner synthesis

Abstract: The aim of this critical review is to provide a broad but digestible overview of mechanochemical synthesis, i.e. reactions conducted by grinding solid reactants together with no or minimal solvent. Although mechanochemistry has historically been a sideline approach to synthesis it may soon move into the mainstream because it is increasingly apparent that it can be practical, and even advantageous, and because of the opportunities it provides for developing more sustainable methods. Concentrating on recent advances, this article covers industrial aspects, inorganic materials, organic synthesis, cocrystallisation, pharmaceutical aspects, metal complexes (including metal–organic frameworks), supramolecular aspects and characterization methods. The historical development, mechanistic aspects, limitations and opportunities are also discussed (314 references).

Band alignment of rutile and anatase TiO2

Abstract: The most widely used oxide for photocatalytic applications owing to its low cost and high activity is TiO2. The discovery of the photolysis of water on the surface of TiO2 in 19721 launched four decades of intensive research into the underlying chemical and physical processes involved2, 3, 4, 5. Despite much collected evidence, a thoroughly convincing explanation of why mixed-phase samples of anatase and rutile outperform the individual polymorphs has remained elusive6. One long-standing controversy is the energetic alignment of the band edges of the rutile and anatase polymorphs of TiO2 (ref. 7). We demonstrate, through a combination of state-of-the-art materials simulation techniques and X-ray photoemission experiments, that a type-II, staggered, band alignment of ~ 0.4 eV exists between anatase and rutile with anatase possessing the higher electron affinity, or work function. Our results help to explain the robust separation of photoexcited charge carriers between the two phases and highlight a route to improved photocatalysts.

Robust self-cleaning surfaces that function when exposed to either air or oil

Abstract: Superhydrophobic self-cleaning surfaces are based on the surface micro/nanomorphologies; however, such surfaces are mechanically weak and stop functioning when exposed to oil. We have created an ethanolic suspension of perfluorosilane-coated titanium dioxide nanoparticles that forms a paint that can be sprayed, dipped, or extruded onto both hard and soft materials to create a self-cleaning surface that functions even upon emersion in oil. Commercial adhesives were used to bond the paint to various substrates and promote robustness. These surfaces maintained their water repellency after finger-wipe, knife-scratch, and even 40 abrasion cycles with sandpaper. The formulations developed can be used on clothes, paper, glass, and steel for a myriad of self-cleaning applications.

Self-cleaning coatings

Abstract: This review summarises the key topics in the field of self-cleaning coatings, concentrating on the materials that have been used in commercial applications and recent research that aims to improve these materials. Hydrophobic and hydrophilic coatings are discussed, and the various mechanisms of self-cleaning are described and related to the material properties of the coatings. Although several multinational companies have released products incorporating self-cleaning coatings, there remains much potential in this field.

Antimicrobial surfaces and their potential in reducing the role of the inanimate environment in the incidence of hospital-acquired infections

Abstract: Environmental surfaces and their role in the epidemiology of hospital-acquired infections (HAIs) have become an area of great scientific interest, particularly in light of the much publicised cases of infections due to methicillin-resistant Staphylococcus aureus (MRSA) and Clostridium difficile in UK hospitals. This feature article sets out to examine the role of surfaces and the inanimate environment in the spread of HAIs, and looks at various antimicrobial techniques being researched to reduce microbial contamination of surfaces. Preventative measures such as coatings which reduce initial microbial adhesion to surfaces will be considered alongside actively antimicrobial measures which inactivate microorganisms already adherent to a surface. The principal focus of this feature article will be given to light-activated antimicrobial surfaces such as the photocatalyst TiO2 and surfaces with embedded photosensitisers. Surfaces which release antimicrobial compounds or metal ions such as silver and copper are also examined, alongside materials which kill microbes upon contact. The widespread research and development of these antimicrobial surfaces is of great importance in maintaining acceptable levels of hygiene in hospitals and will help to fight the spread of HAIs via the contamination of inanimate surfaces in the healthcare environment.

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.