Initial stages of plasma electrolytic oxidation of titanium

The initial stages of oxide growth on titanium are examined in a recently developed commercial alkaline pyrophosphate/aluminate electrolyte of interest for plasma electrolytic oxidation of light metal alloys. Constant current anodizing was employed, with resultant films examined by scanning and transmission electron microscopies and Rutherford backscattering spectroscopy. The initial film is relatively uniform and composed of TiO₂, with low concentrations of aluminium and phosphorus species incorporated from the electrolyte. With increase in voltage the film breaks down locally, and regions of original and modified film develop simultaneously, with the latter occupying more of the surface as the voltage rises. Porous regions due to dielectric breakdown also become increasingly evident. At 240 V, sparking commences, and the surface reveals extensive, relatively uniform porosity, with the coating now containing much enhanced concentrations of aluminium and phosphorus species compared with the coating at lower voltages. The films develop at low efficiency due to generation of oxygen. The oxygen is produced within the original film material and at sites of dielectric breakdown. The former type of film develops a two-layered morphology, with an outer layer of amorphous TiO₂ and an inner layer with numerous fine and course cavities. The cavities are due to the generation of oxygen that may be associated with the formation of anatase in the inner layer.     

Influence of current density on transport numbers in anodic oxide films on an anodized Al–5.7at.%W alloy

The ionic transport numbers in barrier anodic films, formed on an Al–5.7at.%W alloy in 0.1 M sodium tungstate electrolyte at 293 K, have been measured for current densities from 0.1 to 1000 mA cm⁻². For this purpose, a xenon marker was ion implanted with a fluence of 1.5 × 10¹⁵ ions cm⁻² into a film formed to 10 V on the alloy, which was then further anodized to 150 V. The position of the marker layer in the final film was determined by transmission electron microscopy and Rutherford backscattering spectroscopy. The cation transport number was 0.38, with no dependence upon current density to an accuracy of 10%.     

Influences of changes in mechanical properties of an overcored sample on the far-field stress calculation

The concentration factors for the determination of far-field stresses have been calculated based on three-dimensional FLAC^3D simulated results. FLAC^3D is an explicit finite difference computer program. Three-dimensional numerical simulations have been conducted using FLAC^3D to determine the influence of altered overcored sample parameters on the far-field stress calculation. Both Young's modulus and Poisson's ratio are known to change during overcoring in highly stressed rock as a result of stress-relief damage. Modification factors have been proposed to take into account the influence of the reduction in Young's modulus on the far-field stress calculation. The influence of change in Poisson's ratio has also been analyzed. A method of determining a Young's modulus value suitable for use in the far-field stress calculation is described and the influence of reduction in Young's modulus of an overcored sample on the determination of the stress ratio (SR) in the RPR method is analyzed. Using the proposed modification, the in situ stresses for the Atomic Energy of Canada Limited's Underground Research Laboratory are re-calculated based on 21 deep doorstopper measurements. The re-calculation shows an increase in the trend of stress magnitudes versus depth in the URL.     

Book reviews

Wetlands of the American Midwest: a historical geography of changing attitudes

Hugh Prince

Chicago, IL, University of Chicago Press, 1997, 395 pp., ISBN 0-226-68283-8

The Mughal Garden: interpretation, conservation and implications

M. Hussain, A. Rehman & J.L. Westcoat Jr (Eds)

Lahore, Ferozsons (Pvt.) Ltd, 1996, 210 pp., US$69.95 h.b., ISBN 969-0-01299-1

Cofrestr o Dirweddau o Ddiddordeb Hanesyddol Eithriadol yng Nghymru Register of Landscapes of Outstanding Historic Interest in Wales

Richard Kelly

Cardiff, Cadw: Welsh Historic Monuments, 1998, xxxvi +139 pp., ISBN 1-85760-007-X

Landscape Design Trust Monographs No. 1: Geoffrey Jellicoe

Sheila Harvey (Ed.)

Reigate, Landscape Design Trust, 1998, 176 pp., £20.00 pb., ISBN 0-9518377-3-7

Social Formation and Symbolic Landscape (2nd edn)

Denis E. Cosgrove

Wisconsin, University of Wisconsin Press, 1998, 332 pp., ph., ISBN 0-299-15514-5

The Papers of Frederick Law Olmsted: Supplementary Series Volume 1- Writings on Public Parks, Parkways and Park Systems

Charles E. Beveridge & Carolyn F. Hoffman (Eds)

Baltimore, MD John Hopkins University Press, 1997, 643 pp. £41.50 hb., ISBN 0-8018-5532-2

Terminal Architecture

Martin Pawley

London, Reaction Books, 1998, 223 pp., ph., ISBN 1-86189-018-4

Archeticture: ecstasies of space, time and the human body

David Farrell Krell

Albany, NY, State University of New York Press, 1997, xv + 224 pp., ph., ISBN 0-7914-3410-9     

Fabrication of high-aspect ratio Si pillars for atom probe ‘lift-out’ and field ionization tips

A process for fabricating high-aspect ratio (∼1:20), micron-sized Si [0 0 1] pillars using mechanical and chemical size reduction is presented. A dicing saw was used for mechanically patterning an array of square pillars with side lengths of >20 μm. These pillars were then reduced in size using an aqueous NaOH and KOH solution heated to 100 °C. The chemical etch reduces the pillar size within the time range amenable for focus ion beam milling and/or attachment for atom probe ‘lift-out’ specimens. The pillars can be formed with either a flat top surface or into <100 nm tip points for direct field ionization.     

未来信息安全真正的威胁:间谍软件

2005年,间谍软件将取代通过大量散发邮件到处传播的蠕虫病毒,成为各企业所面临的最大麻烦和安全威胁.间谍软件自身的发展远比它的定义更新快得多,来自间谍软件的威胁将使大量散发垃圾邮件的蠕虫病毒显得微不足道.通过邮件得以大量传播的蠕虫病毒之所以会造成麻烦,是因为相对于拦截这些病毒的杀毒软件更新而言,它们传播的速度更快。     

Pre-slaughter transport, AMP-activated protein kinase, glycolysis, and quality of pork loin

Numerous studies have revealed that pre-slaughter stress, like transport, increases the occurrence of pale, soft, and exudative (PSE) pork meat. The molecular mechanism underlying this phenomenon, however, is poorly defined. In this study, we investigated the effects of pre-slaughter transport and subsequent rest on energy metabolism, AMP-activated protein kinase (AMPK) activation, and glycolysis in postmortem pork loin. Results indicated that pre-slaughter transport accelerated ATP depletion, which led to lower energy status in postmortem muscle immediately post-exsanguination when compared with control. The lower energy status led to AMPK activation within 1h postmortem, subsequently increasing glycolysis, leading to rapid glycolysis and high incidence of PSE meat. Allowing pigs to rest after transport restored energy status in muscle ante-mortem. Higher energy status then prevented premature and rapid AMPK activation in postmortem muscle and lessened the negative effects of pre-slaughter transport on meat quality. AMPK regulated glycolysis in postmortem muscle, at least partially, through phosphorylation and activation of phosphofructose kinase-2, since fructose-2,6-diphosphate content, an allosteric activator of phosphofructose kinase-1, was well correlated with AMPK activation and glycolytic rate. This suggests that AMPK is a potential molecular target for the control of PSE incidence in pork.     

Influence of grating parameters on the linewidths of external-cavity diode lasers

We investigate experimentally the influence of the grating reflectivity, grating resolution, and diode facet antireflection (AR) coating on the intrinsic linewidth of an external-cavity diode laser built with a diffraction grating in a Littrow configuration. Grating lasers at 399, 780, and 852 nm are determined to have typical linewidths between 250 and 600 kHz from measurements of their frequency noise power spectral densities. The linewidths are little affected by the presence of an AR coating on the diode facet but narrow as the grating reflectivity and grating resolution are increased, with the resolution exerting a greater effect. We also use frequency noise measurements to characterize a laser mount with improved mechanical stability.     

Magnetohelioseismology

The helioseismic investigation of the solar interior to elucidate the behaviour of the Sun's magnetic field and the interior's role in the solar interior is considered. Such study may be called magnetohelioseismology (from the Greek roots magnetis, helios and seismos).