A method for developing design diagrams for ceramic and glass materials using fatigue data

The service lifetime of glass and ceramic materials can be expressed as a plot of time-to-failure versus applied stress whose plot is parametric in percent probability of failure. This type of plot is called a design diagram. Confidence interval estimates for such plots depend on the type of test that is used to generate the data, on assumptions made concerning the statistical distribution of the test results, and on the type of analysis used. This report outlines the development of design diagrams for glass and ceramic materials in engineering terms using static or dynamic fatigue tests, assuming either no particular statistical distribution of test results or a Weibull distribution and using either median value or homologous ratio analysis of the test results

Structure and morphology of nanocomposites

Since the pioneering work on nylon/clay nanocotnposites performed by Toyota in the early 1990's, where improvements in mechanical properties of the nylon polymer were reported, there has been a great deal of research focussed on blends of thermoplastic polymers and nanoparticles. However, there has been relatively little work exploring the incorporation of nanoparticles into thermosetting polymers. Of the work that has been conducted, full exfoliation, or separation of the nanoparticles required for mechanical and fire retardancy property enhancements, has been very difficult to achieve. Low resin viscosity and the application of ultrasonic vibration are known to be key factors in facilitating exfoliation in thermosetting nanocomposites. The Quickstep process is an out-of autoclave technique that utilises balanced pressure and liquid heating and cooling to cure composite components. As a result, cure cycle times are reduced, from several hours to just a few minutes. The Quickstep process is a recent Australian innovation and there are currently three Quickstep plants worldwide, located at Deakin University, Toyota, Japan and the University of Manchester, UK. Quickstep Technology has the potential to produce commercially ready thermosetting nanocomposites, by curing the matrix together with the nano-clay particles. The combination of rapid temperature ramp rates, leading to low resin viscosity, and the use of vibration through the fluid filled bladder, give the process a unique approach to manufacturing these materials. Results from sample characterisation and mechanical tests will be presented, to compare the mechanical properties of the thermoset nanocomposites to conventional composites. These mechanical properties will be correlated with various morphologies produced by modifying the processing parameters

Comment on ``Nonuniversal Exponents in Interface Growth''

Recently, Newman and Swift[T. J. Newman and M. R. Swift, Phys. Rev. Lett. {\bf 79}, 2261 (1997)] made an interesting suggestion that the strong-coupling exponents of the Kardar-Parisi-Zhang (KPZ) equation may not be universal, but rather depend on the precise form of the noise distribution. We show here that the decrease of surface roughness exponents they observed can be attributed to a percolative effect

Site Analysis for Seismic Soil Liquefaction Potential

Field penetration data and cyclic laboratory test data are presented for evaluating the seismically induced soil liquefaction potential at a waterfront site. Dynamic split-spoon penetration recordings and three types of quasistatic friction cone probings were made. The friction cones were the standard mechanical cone, the electric cone, and the piezometric cone. The latter penetrometer has a porous element near the tip which permits measurement of pore water pressures generated during penetration. By interrupting penetration, the rate of pore pressure dissipation can be recorded, so an estimate of soil permeability can also be derived. Undisturbed samples were taken using an Osterberg piston sampler, and the specimens were subjected to cyclic triaxial testing in the laboratory. The field sounding techniques were in agreement; however, they indicated a recently deposited sensitive silty sand to have a liquefaction resistance approximately one-half that based upon cyclic triaxial testing. The question arises as to whether the liquefaction resistance as determined by laboratory testing is more appropriate herein, or whether behavior suggested by the penetration test results more realistically predicts the response of this type of soil to an actual earthquake

Near-Infrared, Adaptive Optics Observations of the T Tauri Multiple-Star System

With high-angular-resolution, near-infrared observations of the young stellar object T Tauri at the end of 2002, we show that, contrary to previous reports, none of the three infrared components of T Tau coincide with the compact radio source that has apparently been ejected recently from the system (Loinard, Rodriguez, and Rodriguez 2003). The compact radio source and one of the three infrared objects, T Tau Sb, have distinct paths that depart from orbital or uniform motion between 1997 and 2000, perhaps indicating that their interaction led to the ejection of the radio source. The path that T Tau Sb took between 1997 and 2003 may indicate that this star is still bound to the presumably more massive southern component, T Tau Sa. The radio source is absent from our near-infrared images and must therefore be fainter than K = 10.2 (if located within 100 mas of T Tau Sb, as the radio data would imply), still consistent with an identity as a low-mass star or substellar object.Comment: 11 pages, 3 figures, submitted to ApJ

Handbook of Life Course Health Development

This handbook synthesizes and analyzes the growing knowledge base on life course health development (LCHD) from the prenatal period through emerging adulthood, with implications for clinical practice and public health. It presents LCHD as an innovative field with a sound theoretical framework for understanding wellness and disease from a lifespan perspective, replacing previous medical, biopsychosocial, and early genomic models of health. Interdisciplinary chapters discuss major health concerns (diabetes, obesity), important less-studied conditions (hearing, kidney health), and large-scale issues (nutrition, adversity) from a lifespan viewpoint. In addition, chapters address methodological approaches and challenges by analyzing existing measures, studies, and surveys. The book concludes with the editors’ research agenda that proposes priorities for future LCHD research and its application to health care practice and health policy

Cellular Uptake and Internalization of Hyaluronan-based Doxorubicin and Cisplatin Conjugates

Background Hyaluronan (HA) is a ligand for the CD44 receptor which is crucial to cancer cell proliferation and metastasis. High levels of CD44 expression in many cancers have encouraged the development of HA-based carriers for anti-cancer therapeutics. Purpose The objective of this study was to determine whether HA conjugation of anticancer drugs impacts CD44-specific HA-drug uptake and disposition by human head and neck cancer cells. Methods The internalization and cellular disposition of hyaluronan-doxorubicin (HA-DOX), hyaluronan-cisplatin (HA-Pt), and hyaluronan-cyanine7 (HA-Cy7) conjugates were investigated by inhibiting endocytosis pathways, and by inhibiting the CD44–mediated internalization pathways that are known to mediate hyaluronan uptake in vitro. Results Cellular internalization of HA was regulated by CD44 receptors. In mouse xenografts, HA conjugation significantly enhanced tumor cell uptake compared to unconjugated drug. Discussion The results suggested that the main mechanism of HA-based conjugate uptake may be active transport via CD44 in conjunction with a clathrin–dependent endocytic pathway. Other HA receptors, hyaluronan–mediated motility receptor (RHAMM) and lymphatic vessel endothelial hyaluronan receptor (LYVE-1), did not play a significant role in conjugate uptake. Conclusions HA conjugation significantly increased CD44 mediated drug uptake and extended the residence time of drugs in tumor cells

Dewetting of Glassy Polymer Films

Dynamics and morphology of hole growth in a film of power hardening viscoplastic solid (yield stress ~ [strain-rate]^n) is investigated. At short-times the growth is exponential and depends on the initial hole size. At long-times, for n > 1/3, the growth is exponential with a different exponent. However, for n < 1/3, the hole growth slows; the hole radius approaches an asymptotic value as time tends to infinity. The rim shape is highly asymmetric, the height of which has a power law dependence on the hole radius (exponent close to unity for 0.25 < n < 0.4). The above results explain recent intriguing experiments of Reiter, Phys. Rev. Lett, 87, 186101 (2001).Comment: 4 pages, 5 figures, RevTe

Soluble Infinite-Range Model of Kinetic Roughening

A modified Kardar-Parisi-Zhang (KPZ) equation is introduced, and solved exactly in the infinite-range limit. In the low-noise limit the system exhibits a weak-to-strong coupling transition, rounded for non-zero noise, as a function of the KPZ non-linearity. The strong-coupling regime is characterised by a double-peaked height distribution in the stationary state. The nonstationary dynamics is quite different from that of the stationary state.Comment: 13 pages, revtex, 1 postscript figur