Queensland University of Technology

About: Queensland University of Technology is a education organization based out in Brisbane, Queensland, Australia. It is known for research contribution in the topics: Population & Context (language use). The organization has 14188 authors who have published 55022 publications receiving 1496237 citations. The organization is also known as: QUT.

Visible-Light-Driven Oxidation of Organic Contaminants in Air with Gold Nanoparticle Catalysts on Oxide Supports

Abstract: One of the great challenges in catalysis is to devise new catalysts that have high activity when illuminated by visible light. Solving this challenge will allow us to use sunlight, an abundant and clean low-cost energy source, to drive chemical reactions. Visible light (wavelength l> 400 nm) constitutes around 43% of solar energy, and the energy of sunlight to the Earth is about 10000 times more than the current energy consumption of the world. Many approaches have been proposed to develop visible light photocatalysts, including doping TiO2 with metal ions or metal atom clusters, [4,5] incorporating nitrogen and carbon into TiO2, and employing other metal oxides or polymetallates as catalyst materials. 5,8] Research has been mainly concentrated on semiconductor oxides. Sulfides have also been studied, but they are not suitable catalysts because of their poor chemical stability. However, searching for catalysts that can work under visible light should not be limited to semiconductor materials with band-gap structure, but can be extended to other materials, such as gold nanoparticles. It can be said that glaziers in medieval forges were the first nanotechnologists who produced colors with gold nanoparticles of different sizes, although they had little understanding of the modern day principles which have become a hot topic in the last two decades. In recent years there have been numerous studies on the optical properties of gold nanoparticles. Gold nanoparticles absorb visible light intensely because of the surface plasmon resonance (SPR) effect. The electromagnetic field of incident light couples with the oscillations of conduction electrons in gold particles, resulting in strong-field enhancement of the local electromagnetic fields near the rough surface of gold nanoparticles. The enhanced local field strength can be over 500 times larger than the applied field for structures with sharp apices, edges, or concave curvature (e.g. nanowires, cubes, triangular plates, and nanoparticle junctions). The SPR absorption may cause rapid heating of the nanoparticles. Gold nanoparticles supported on metal oxides are efficient catalysts for important oxidation process, including selective oxidation of hydrocarbons and oxidation of various volatile organic compounds (VOCs), such as CO, CH3OH, and HCHO at moderately elevated temperatures. Therefore, the combination of the SPR absorption and the catalytic activity of gold nanoparticles presents an important opportunity: if the heated gold nanoparticles could activate the organic molecules on them to induce oxidation of the organic compounds, then oxidation on gold catalysts can be driven by visible light at ambient temperature. Moreover, the SPR is a local effect, limited to the noble metal particles, so that the light only heats gold nanoparticles, which generally account for a few percent of the overall catalyst mass. This leads to significant saving in energy consumption for catalyzing organic compound oxidation. To verify the possibility of driving the VOC oxidation with visible light at room temperature, we prepared gold particles supported on various oxide powders. ZrO2 and SiO2 powders were first chosen as supports, because their band gaps are circa 5.0 eV and circa 9.0 eV, respectively, which are much larger than the energies of the photons of visible light (less than 3.0 eV). Thus, the light cannot excite electrons from the valence band to the conduction band. It is also impossible for the gold nanoparticles on ZrO2 to reduce the band gaps of ZrO2 enough for visible light photons to be absorbed and excite electrons in ZrO2. Thus, the catalytic activity is not caused by the same mechanism as occurs in semiconductor photocatalysts, but is due to the SPR effect of gold nanoparticles. The changes in the concentrations of the reactant (HCHO, 100 ppm) and product (CO2), when gold supported on ZrO2 was used as the catalyst, are depicted in Figure 1a. The initial concentration of HCHO in the glass vessel was 100 ppm. HCHO content decreased by 64% in two hours under the irradiation of six light tubes of blue light (with wavelength between 400 and 500 nm and the irradiation energy determined to be 0.17 Wcm 2 at the position of glass slides coated with the gold catalysts), and the CO2 content in the vessel increased accordingly. These results confirm that the oxidation of formaldehyde to carbon dioxide proceeds to a large extent at ambient temperature. The turnover frequency was calculated as being about 1.2 = 10 3 molecules of [*] Dr. X. Chen, Prof. H.-Y. Zhu, Z.-F. Zheng School of Physical and Chemical Sciences Queensland University of Technology Brisbane, Qld 4001 (Australia) Fax: (+61)7-3864-1804 E-mail: hy.zhu@qut.edu.au

Genome-wide associations for birth weight and correlations with adult disease

Abstract: Birth weight (BW) has been shown to be influenced by both fetal and maternal factors and in observational studies is reproducibly associated with future risk of adult metabolic diseases including type 2 diabetes (T2D) and cardiovascular disease1. These life-course associations have often been attributed to the impact of an adverse early life environment. Here, we performed a multi-ancestry genome-wide association study (GWAS) meta-analysis of BW in 153,781 individuals, identifying 60 loci where fetal genotype was associated with BW (P < 5 × 10−8). Overall, approximately 15% of variance in BW was captured by assays of fetal genetic variation. Using genetic association alone, we found strong inverse genetic correlations between BW and systolic blood pressure (Rg = −0.22, P = 5.5 × 10−13), T2D (Rg = −0.27, P = 1.1 × 10−6) and coronary artery disease (Rg = −0.30, P = 6.5 × 10−9). In addition, using large -cohort datasets, we demonstrated that genetic factors were the major contributor to the negative covariance between BW and future cardiometabolic risk. Pathway analyses indicated that the protein products of genes within BW-associated regions were enriched for diverse processes including insulin signalling, glucose homeostasis, glycogen biosynthesis and chromatin remodelling. There was also enrichment of associations with BW in known imprinted regions (P = 1.9 × 10−4). We demonstrate that life-course associations between early growth phenotypes and adult cardiometabolic disease are in part the result of shared genetic effects and identify some of the pathways through which these causal genetic effects are mediated.

Representation results for defeasible logic

Abstract: The importance of transformations and normal forms in logic programming, and generally in computer science, is well documented. This paper investigates transformations and normal forms in the context of Defeasible Logic, a simple but efficient formalism for nonmonotonic reasoning based on rules and priorities. The transformations described in this paper have two main benefits: on one hand they can be used as a theoretical tool that leads to a deeper understanding of the formalism, and on the other hand they have been used in the development of an efficient implementation of defeasible logic.