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.

Comparison of Raman spectra in characterizing gibbsite, bayerite, diaspore and boehmite

Abstract: High-quality Raman spectra were used for the characterization of alumina phases of gibbsite, bayerite, diaspore and boehmite. The Raman spectrum of gibbsite shows four strong, sharp bands at 3617, 3522, 3433 and 3364 cm in the hydroxyl stretching region. The spectrum of bayerite shows seven bands at 3664, 3652, 3552, 3542, 3450, 3438 and 3420 cm. Five broad bands at 3445, 3363, 3226, 3119 and 2936 cm and four broad and weak bands at 3371, 3220, 3085 and 2989 cm-1 are present in the Raman spectrum of the hydroxyl stretching region of diaspore and boehmite. The hydroxyl stretching bands are related to the surface structure of the minerals. The Raman spectra of bayerite, gibbsite and diaspore are complex whereas the Raman spectrum of boehmite shows only four bands in the low-wavenumber region. These bands are assigned to deformation and translational modes of the alumina phases. A comparison of the Raman spectrum of bauxite with those of boehmite and gibbsite showed the possibility of using Raman spectroscopy for on-line processing of bauxites that contain a mixture of alumina phases.

Porous Clays and Pillared Clays-Based Catalysts. Part 2: A review of the Catalytic and Molecular Sieve Applications

Abstract: Metal oxide pillared clay (PILC) possesses several interesting properties, such as large surface area, high pore volume and tunable pore size (from micropore to mesopore), high thermal stability, strong surface acidity and catalytic active substrates/metal oxide pillars. These unique characteristics make PILC an attractive material in catalytic reactions. It can be made either as catalyst support or directly used as catalyst. This paper is a continuous work from Kloprogge's review (J.T. Kloprogge, J. Porous Mater. 5, 5 1998) on the synthesis and properties of smectites and related PILCs and will focus on the diverse applications of clay pillared with different types of metal oxides in the heterogeneous catalysis area and adsorption area. The relation between the performance of the PILC and its physico-chemical features will be addressed.

Test liquids for quantitative MRI measurements of self-diffusion coefficient in vivo

Abstract: A range of liquids suitable as quality control test objects for measuring the accuracy of clinical MRI diffusion sequences (both apparent diffusion coefficient and tensor) has been identified and characterized. The self-diffusion coefficients for 15 liquids (3 cyclic alkanes: cyclohexane to cyclooctane, 9 n-alkanes: n-octane to n-hexadecane, and 3 n-alcohols: ethanol to 1-propanol were measured at 15-30 degrees C using an NMR spectrometer. Values at 22 degrees C range from 0.36 to 2.2 10(-9) m(2)s(-1). Typical 95% confidence limits are +/-2%. Temperature coefficients are 1.7-3.2% degrees C. T1 and T2 values at 1.5 T and proton density are given. n-tridecane has a diffusion coefficient close to that of normal white matter. The longer n-alkanes may be useful T2 standards. Measurements from a spin-echo MRI sequence agreed to within 2%.

The Arab Spring and Social Media Audiences English and Arabic Twitter Users and Their Networks

Abstract: Although popular media narratives about the role of social media in driving the events of the 2011 “Arab Spring” are likely to overstate the impact of Facebook and Twitter on these uprisings, it is...