Single on-chip gold nanowires for electrochemical biosensing of glucose

The development of glucose diagnostic devices with low detection limits is of key importance in diabetes-related research. New highly sensitive sensors are required for non-invasive detection of glucose in bodily fluids, other than blood, and an electrochemical sensor based on a single gold nanowire for rapid, reliable and quantitative detection of low glucose concentrations (10 μM-1 mM), is presented in this paper. Single gold nanowire devices are fabricated at silicon chip substrates using a hybrid electron beam-photolithography approach. Critical dimensions of the nanowires are characterised using a combination of scanning electron and atomic force microscopies. Fabricated nanowire devices are characterised by direct electrical probing and cyclic voltammetry to explore functionality. The voltammetric detection of glucose was performed using ferrocene monocarboxylic acid as an oxidising mediator in the presence of glucose oxidase. The biosensor can be applied to the quantification of glucose in the range of 10 μM-100 mM, with an extremely high sensitivity of 7.2 mA mM(-1) cm(-2) and a low detection limit of 3 μM (S/N = 3). The sensor demonstrated high selectivity towards glucose with negligible interference from other oxidizable species including uric acid, ascorbic acid, mannose, fructose, salicylic acid (Aspirin) and acetaminophen (Paracetamol).     

Lattice model of glasses

Glass-forming liquids have been extensively studied in recent decades, but there is still no theory that fully describes these systems, and the diversity of treatments is in itself a barrier to understanding. Here we introduce a new simple model that (possessing both liquid-crystal and glass transition) unifies different approaches, producing most of the phenomena associated with real glasses, without loss of the simplicity that theorists require. Within the model we calculate energy relaxation, nonexponential slowing phenomena, the Kauzmann temperature, and other classical signatures. Moreover, the model reproduces a subdiffusive exponent observed in experiments of dense systems. The simplicity of the model allows us to identify the microscopic origin of glassification, leaving open the possibility for theorists to make further progress.     

An experimental study of a turbulent vortex ring: a three-dimensional representation

This paper presents a reconstruction of the three-dimensional velocity field of a turbulent vortex ring by means of Taylor’s hypothesis. Stereoscopic PIV is used to acquire three velocity component information on a plane. The accuracy of the Taylor’s hypothesis for this particular flow pattern is first discussed, and the three-dimensional velocity and vorticity information are then presented. This study also introduces an azimuthally averaging method in order to give a mean structure in cylindrical coordinates from a single realization and from which turbulent stresses and production can be estimated. The azimuthally averaged quantities are then compared with the ensemble-averaged results from the previous planar (two-dimensional and stereoscopic) PIV experiments.     

A simple route to 6- and 7-fluoro-substituted naphthalene-1-carboxylic acids

A simple one-pot method for the synthesis of 6-fluoro- and 6,7-difluoro-1-naphthoic acid is described. 6-Fluoro-1-naphthoic acid can be converted into 7-fluoro-1-naphthoic acid in three straightforward steps.     

Anomalous muonium relaxation rates in quartz at high temperatures

Muonium spin relaxation measurements of the \alpha‐, \beta‐, and \gamma‐tridymite phases of quartz have been carried out over a temperature range from 300 to 1250 K. Anomalous relaxation rate increases are observed which may result either from resonance coupling between the other impurity ions and defects in the lattice and the diffusing muonium, or may result from phonon interactions with the muonium quadrupole moment. This revised version was published online in August 2006 with corrections to the Cover Date.     

Hierarchical models of interacting diffusions: Multiple time scale phenomena,phase transition and pattern of cluster-formation

Summary The purpose of this paper is to explore the connection between multiple space-time scale behaviour for block averages and phase transitions, respectively formation of clusters, in infinite systems with locally interacting components. The essential object is the associated Markov chain which describes the joint distribution of the block averages at different time scales. A fixed-point and stability property of a particular dynamical system under a renormalisation procedure is used to explain this pattern of cluster formation and the fact that the longtime behaviour is universal in entire classes of evolutions.     

A plasma klystron for generating ultra-short electron bunches

A technique for producing ultra-short electron bunches (e.g., ⩽100 fs) from a continuous electron beam using a short plasma wave section and a drift space is explored. The bunches are a fraction of a plasma wavelength long and are spaced by a plasma wavelength, making them of interest for injection into plasma accelerators or for driving a klystron-like structure to produce infrared radiation     

Effects of cycloheximide on liquid-holding recovery from ultraviolet radiation damage in yeast cells

Abstract. The role of protein synthesis in liquid-holding recovery from ultra-violet radiation damage in synchronized Saccharomyces cerevisiae cells has been studied using cycloheximide as a specific inhibitor of cytoplasmic protein synthesis. Liquid-holding recovery from UV-induced budding delay is completed within a few hours and is not inhibited by the presence of cycloheximide. Liquid-holding recovery from lethal UV damage is unaffected by cycloheximide for liquid-holding times less than about 12 h. For longer times recovery is inhibited, with survival enhancement eliminated after about 48 h. Periods greater than 48 h of liquid-holding in the presence of cycloheximide result in survival less than that obtained with immediate plating, but the same concentration of cycloheximide is not toxic to unirradiated cells.