The effects of pigments on the photostability of polyethylene

The affect of carbon black and various colourizing pigments on the ultraviolet (UV) stability of high and low density polyethylene (HDPE and LDPE) was determined using a novel method for the analysis of oxygen uptake profiles. Samples were exposed to 0.27 Wm⁻² (measured at 340 nm) UV irrdiation at 25.0±0.1° C in air at 1.0 atm. The usefulness of this method of assessment of UV stability is demonstrated. The method also enables the rapid collection of data that enable the comparison of the relative photostabilities of experimental and commercial formulations containing pigments and stabilizing additives. The results show that carbon black is an effective UV screening agent for HDPE when added at levels as low as 0.05% (wt/wt) and that increased photoprotection is achieved with increasing concentration of carbon black, up to 5% (wt/wt), above which there is no further significant increase in photostability. LDPE containing ultramarine blue pigment (Na₇Al₆Si₆O₂₄S₃) exhibits relatively poor photostability, whereas ferric oxide (Fe₂O₃) and chrome orange (PbCrO₄.PbO) pigments are better photostabilizers for this material. Cadmium sulphide (CdS) was found to photosensitize LDPE. A compound containing 0.10% (wt/wt) carbon black, 0.12% (wt/wt) titanium dioxide (TiO₂) and 1.78% (wt/wt) phthalocyanine green (C₃₃H₂N₈Cl₁₄Cu) is an effective formulation for the stabilization of LDPE. Formulations of LDPE containing ultramarine blue-TiO₂ or ferric oxidecarbon black combinations absorb heat on exposure and this may affect their photostability.     

Human tracking using 3D surface colour distributions

A likelihood formulation for detailed human tracking in real-world scenes is presented. In this formulation, the appearance, modelled using feature distributions defined over regions on the surface of an articulated 3D model, is estimated and propagated as part of the state. The benefit of such a formulation over currently used techniques is that it provides a dense, highly discriminatory object-based cue that applies in real world scenes. Multi-dimensional histograms are used to represent the feature distributions and an on-line clustering algorithm, driven by prior knowledge of clothing structure, is derived that enhances appearance estimation and computational efficiency. An investigation of the likelihood model shows its profile to be smooth and broad while region grouping is shown to improve localisation and discrimination. These properties of the likelihood model ease pose estimation by allowing coarse, hierarchical sampling and local optimisation.     

Introduction

Journal of Fusion Energy -     

Gelcast Tooling: Net Shape Casting and Green Machining

Gelcasting is an advanced powder forming process. It is most commonly used to form ceramic or metal powders into complex, near-net shapes. Turbine rotors, gears, nozzles, and crucibles have been successfully gelcast in silicon nitride, alumina, nickel-based superalloy, and several steels. Gelcasting can also be used to make blanks that can be green machined to near-net shape and then high fired. Green machining has been successfully applied to both ceramic and metal gelcast blanks. Recently, we have used gelcasting to make toolinj; for metal casting applications. Most of the work has centered on H13 tool steel. We have demonstrated an ability to gelcast and sinter H13 to near net shape for metal casting tooling. We have also been successful in green machining gelcast blanks using a three-axis CNC milling machine.     

Manipulation of smoking urges and affect through a brief-imagery procedure: Self-report, psychophysiological, and startle probe responses.

The extent to which sentence imagery elicits effects comparable to those produced by long narratives was investigated. Smokers imagined sentences with varying affective content and that either contained or were devoid of smoking cues. Physiological responses were monitored, and smokers rated their urges and affect. Startle responses were also collected as an index of negative affect processing. Smoking-cue sentences produced augmented urges and startle responding. Smoking material also elevated negative affect during imagery of positive affect sentences. The affect manipulation produced changes in self-reported affect and facial electromyography consistent with the affective valence of the sentences. This procedure is similar to narrative imagery in the manipulation of smoking urges and affect under laboratory conditions. Results support the hypothesis that smoking urges enhance negative affect processing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Adult recollections of childhood abuse: Cognitive and developmental perspectives.

This research was conducted, as part of American Psychological Association Working Group on the Investigation of Memories of Childhood Abuse (see record 2000-13581-002), to address concerns about cases in which an individual has no memory for a traumatic experience, enters therapy, and emerges sometime later with an elaborate memory. The article summarizes research on human memory, focusing on the literature in cognitive and developmental psychology. The authors provide a broad overview of memory and its development by making use of a conceptual framework for thinking about the flow of information within the memory system. They then focus on 3 topics: (1) a developmental perspective and its relevance for considering questions of adults attempting to remember things from the distant past; (2) suggestibility, memory distortions, and the extent to which misleading information may degrade memory performance; and (3) distinguishing between reality and fantasy, and monitoring the sources of information. The report concludes with a treatment of the importance of determining boundary conditions for some of the effects that are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Ohmic contacts to n-type GaN

Ohmic contacts to n-GaN using Ag, Au, TiN, Au/Ti, Au/Mo/Ti, and Au/Si/Ti have been studied. The Fermi level of GaN appears to be unpinned, and metals and compounds with work functions less than the electron affinity resulted in ohmic contacts. Reactively sputter deposited TiN was ohmic as deposited. However, Au/Ti, Au/Mo/Ti, and Au/Si/Ti required heat treatments to form ohmic contacts, with the best being an RTA at 900°C. Ag and Au were shown to diffuse across the GaN surface at T>500°C; therefore, they are unstable, poor ohmic contact metallizations as single metals. The other contact schemes were thermally stable up to 500°C for times of 30 min.     

Fusion Power by Magnetic Confinement Program Plan

This report has been available previously only as Volume I of a 5-volume U.S. Energy Research and Development Administration Report ERDA-76/110 (1976). It was the first comprehensive U.S fusion development plan. It treats the technical, schedular and budgetary projections for the development of fusion power using magnetic confinement. It provided the basis for the U. S. fusion facility and funding commitments during the latter half of the 1970's and is published now to archive its historical significance.     

Statistics and the Question of Standards

This is a written version of a memorial lecture given in honor of Churchill Eisenhart at the National Institute of Standards and Technology on May 5, 1995. The relationship and the interplay between statistics and standards over the past centuries are described. Historical examples are presented to illustrate mutual dependency and development in the two fields.