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Articles 1 - 4 of 4
Full-Text Articles in Physical Sciences and Mathematics
The Rapid Formation Of Functional Monolayers On Silicon Under Mild Conditions, Simone Ciampi, Erwann Luais, Michael James, Moinul Choudhury, Nadim Darwish, J Gooding
The Rapid Formation Of Functional Monolayers On Silicon Under Mild Conditions, Simone Ciampi, Erwann Luais, Michael James, Moinul Choudhury, Nadim Darwish, J Gooding
Michael C James
We report on an exceedingly mild chemical functionalization of hydrogen-terminated Si(100) with unactivated and unprotected bifunctional α,ω-dialkynes. Monolayer formation occurs rapidly in the dark, and at room temperature, from dilute solutions of an aromatic-conjugated acetylene. The method addresses the poor reactivity of p-type substrates under mild conditions. We suggest the importance of several factors, including an optimal orientation for electron transfer between the adsorbate and the Si surface, conjugation of the acetylenic function with a π-system, as well as the choice of a solvent system that favors electron transfer and screens Coulombic interactions between surface holes and electrons. The passivated …
Afromontane Foragers Of The Late Pleistocene: Site Formation, Chronology And Occupational Pulsing At Melikane Rockshelter, Lesotho, Brian Stewart, Genevieve Dewar, Mike Morley, Robyn Inglis, Mark Wheeler, Zenobia Jacobs, Richard Roberts
Afromontane Foragers Of The Late Pleistocene: Site Formation, Chronology And Occupational Pulsing At Melikane Rockshelter, Lesotho, Brian Stewart, Genevieve Dewar, Mike Morley, Robyn Inglis, Mark Wheeler, Zenobia Jacobs, Richard Roberts
Richard G Roberts
This paper provides a preliminary chronostratigraphic and palaeoenvironmental framework for the Late Pleistocene archaeological sequence at Melikane Rockshelter in mountainous eastern Lesotho. Renewed excavations at Melikane form part of a larger project investigating marginal landscape use by Late Pleistocene foragers in southern Africa. Geoarchaeological work undertaken at the site supports in-field observations that Melikane experienced regular, often intensive, input of groundwater via fissures in the shelter’s rear wall. This strong hydrogeological connection resulted in episodic disturbances of the sedimentary sequence, exacerbated by other processes such as bioturbation. Despite this taphonomic complexity, a robust chronology for Melikane has been developed, based …
Theoretical Probing Of The Phenomenon Of The Formation Of The Outermost Surface Layer Of A Multi-Component Particle, And The Surface Chemical Composition After The Rapid Removal Of Water In Spray Drying, Mark Nelson, Harvinder Sidhu, X.D. Chen
Theoretical Probing Of The Phenomenon Of The Formation Of The Outermost Surface Layer Of A Multi-Component Particle, And The Surface Chemical Composition After The Rapid Removal Of Water In Spray Drying, Mark Nelson, Harvinder Sidhu, X.D. Chen
Associate Professor Mark Nelson
Spray drying is a primary process for the manufacture of powders, which satisfy a vast array of societal demands in the areas of nutrition, health and medicine. The functionality of a spray-dried product begins with its incorporation into water (wetting followed by dispersion) Therefore, as its surface chemical composition and structure determine its first contact with water (that is, its hydrophilic nature), these are of prime concern. Laboratory studies on this first layer, which is in the order of several nm in depth from the surface, have been extensive but there is still a lack of a fundamental quantitative explanation …
Amyloid Fibril Formation By Bovine Milk Alpha(S2)-Casein Occurs Under Physiological Conditions Yet Is Prevented By Its Natural Counterpart, Alpha(S1)-Casein, David Thorn, Heath Ecroyd, M Sunde, Stephen Poon, John Carver
Amyloid Fibril Formation By Bovine Milk Alpha(S2)-Casein Occurs Under Physiological Conditions Yet Is Prevented By Its Natural Counterpart, Alpha(S1)-Casein, David Thorn, Heath Ecroyd, M Sunde, Stephen Poon, John Carver
Heath Ecroyd
The calcified proteinaceous deposits, or corpora amylacea, of bovine mammary tissue often comprise a network of amyloid fibrils, the origins of which have not been fully elucidated. Here, we demonstrate by transmission electron microscopy, dye binding assays, and X-ray fiber diffraction that bovine milk alpha(s2)-casein, a protein synthesized and secreted by mammary epithelial cells, readily forms fibrils in vitro. As a component of whole alpha(s)-casein, alpha(s2)-casein was separated from alpha(s1)-casein under nonreducing conditions via cation-exchange chromatography. Upon incubation at neutral pH and 37 degrees C, the spherical particles typical of alpha(s2)-casein rapidly converted to twisted, ribbon-like fibrils similar to 12 …