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- Author or Editor: P. Thomas x
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Abstract
The mechanism and stability of dimethylol urea (DMU) to polycondensation were investigated using thermogravimetric analysis coupled with mass spectroscopy (TG-MS) for evolved gas analysis and a non-isothermal model-free induction period kinetic analysis using three temperature functions; the Arrhenius function and two non-Arrhenian functions. The polycondensation was observed to occur through a two-step process of condensation followed by elimination of formaldehyde during structural rearrangement as has been reported in the literature. The rate equations for each temperature function were evaluated and extrapolated to room (23 °C) and refrigerator (4 °C) temperature to estimate the length of the induction period for the onset of polycondensation for storage life prediction. Based on experience, estimates of the length of the induction periods and, hence, storage life, were most realistically predicted by the non-Arrhenian temperature functions.
Abstract
The use of supplementary cementitious materials (SCM) is a well established practice worldwide in the manufacture of Portland cement (PC)-based construction materials. While utilisation of industrial by-products has been successful, the potential of mining wastes is yet to receive adequate attention in the context of construction materials. In an expanded form perlite, which is a naturally occurring, hydrated volcanic siliceous glass, is an ideal material as a lightweight aggregate for use in a wide range of construction materials including concrete. The mining and processing of the grades of perlite required for the production of lightweight aggregate results in the creation of a fine grained waste which currently has no economic value. This paper reports preliminary data on the utilisation of waste perlite fines as a SCM in calcium silicate-based construction material and discusses the potential of this mining waste to reduce the environmental impact of the production of conventional cement-based construction materials.
Abstract
In this research, we report the preparation of doped PMo Keggin heteropolyacids where Mo is partially replaced by V, Bi, and Bi–V. These catalysts were characterized by means of ICP-AES analysis, 31P-NMR, UV–visible spectra, FT-IR spectra, thermal analysis, and textural properties. In addition, the activities of the synthesized catalysts were evaluated in the selective oxidation of sulfides to sulfoxides/sulfones. The incorporation of V, Bi and Bi–V into the structure of H3PMo12O40 increases the catalytic activity. The two most active catalysts, those with V and V–Bi were supported on aminopropyl-functionalized silica (SiO2NH2) and they were found to be and efficient heterogeneous catalysts for the selective oxidation of diphenylsulfide to the corresponding sulfoxide/sulfone.
Abstract
Fluorine surface contamination and depth profiles were studied using the19F(p, p'
)19F resonance reaction. Fluorine implanted silicon samples as well as ZrNb plates and Cr–Al layers after a HF-treatment have been examined. The resonance strengths of the narrow 1088 keV resonance were estimated.
Abstract
Hydrogen surface contamination and depth profiles can be measured by the resonant nuclear reactions1H(19F, 
)16O and1H(15N,
)12C. The method was applied to study hydrogen-implanted silicon, amorphous silicon layers and silicon oxide films produced by anodic oxidation.
Abstract
Whole body nitrogen has been measured absolutely in male volunteers and patients by in-vivo neutron activation analysis using whole body hydrogen as an internal standard. The 10.8 MeV and 2.2 MeV prompt gamma rays from nitrogen and hydrogen respectively give a result reproducible to 4% for a dose of 100 mRem. Whole body potassium measured by whole body counting natural40K and whole body nitrogen have been correlated in normal adult males and patients. In the normals the correlation coefficient was 0.96 with coefficient of variation 4%. In the patients these parameters were 0.92 and 8% in 140 measurements. The ratio of N/K increased significantly as the degree of clinical wasting progressed.
Summary Cold pressed linseed oil and paints prepared using the inorganic pigments; lead white and red lead, were characterized using non-isothermal differential scanning calorimetry (DSC) in an air atmosphere to determine the effect of the pigment on the oxidative polymerisation of the drying oil medium. For each paint sample, the onset temperature for oxidation was reduced from 166°C to the range 50 to 60°C when a heating rate of 5 K min-1 was used. In order to determine the rate of drying, the non-isothermal experiments were carried out using a range of heating rates. A change in the mechanism oxidative polymerization was observed as the heating rate was increased.
Summary Many of Sydney’s heritage buildings and monuments were built as a result of the first European settlement in the 1800s. These buildings not only display the richness of the Australian culture, but also capture the architectural and historical values of its past. Although many of these buildings still appear to be strong and sound, many signs of deterioration have been detected in recent years. Conservators from various disciplines such as science, architecture and engineering are working closely together to develop suitable solutions to stop or at least slow down the degradation process of these precious buildings. This study demonstrates the usefulness of thermal analysis in determining the weathering mechanisms of marble and sandstone taken from two of Sydney’s landmarks, the Captain Arthur Phillips Monument at Sydney’s Botanic Gardens and Sydney’s St Mary’s Cathedral. This paper reports the findings of the weathering behaviours of both marble and sandstone samples determined using thermal analysis techniques.
Abstract
Quantitative measurement of fission and activation products resulting from neutron irradiation of fissile materials is of interest for applications in environmental monitoring, nuclear waste management, and national security. Based on established separation processes involving co-precipitation, solvent extraction, and ion-exchange and extraction chromatography, we have optimized a proposed sequence of separation steps to allow for the timely quantification of analytes of interest. We have recently evaluated this scheme using an irradiated sample to examine the adequacy of separations for measurement of desired analytes by gamma spectrometry. Here we present the radiochemical separations utilized and the yields and purity obtained.
Background
Internet gaming disorder (IGD) was introduced in the DSM-5 as a way of identifying and diagnosing problematic video game play. However, the use of the diagnosis is constrained, as it shares criteria with other addictive orders (e.g., pathological gambling).
Aims
Further work is required to better understand IGD. One potential avenue of investigation is IGD’s relationship to the primary reinforcing behavioral functions. This study explores the relationship between duration of video game play and the reinforcing behavioral functions that may motivate or maintain video gaming.
Methods
A total of 499 video game players began the online survey, with complete data from 453 participants (85% white and 28% female), were analyzed. Individuals were placed into five groups based on self-reported hours of video gaming per week, and completed the Video Game Functional Assessment – Revised (VGFA-R).
Results
The results demonstrated the escape and social attention function were significant in predicting duration of video game play, whereas sensory and tangible were not significant.
Conclusion
Future implications of the VGFA-R and behaviorally based research are discussed.
