Curtin University

About: Curtin University is a education organization based out in Perth, Western Australia, Australia. It is known for research contribution in the topics: Population & Zircon. The organization has 14257 authors who have published 48997 publications receiving 1336531 citations. The organization is also known as: WAIT & Western Australian Institute of Technology.

Fracture properties of geopolymer paste and concrete

Abstract: Geopolymers are an emerging type of cementitious material purported to provide an environmentally friendly alternative to Portland cement-based concrete. This paper reports the results of experimental research on fracture properties (fracture energy and brittleness) of fly ash based geopolymer concrete and paste with various mix parameters. The characteristic length of the geopolymer concrete was approximately three times less than that of ordinary Portland cement (OPC) concrete, due to an increase in tensile splitting strength of about 28%, a decrease in elastic modulus of about 22% and a decrease in fracture energy of about 24%. The difference in characteristic length is similar to that reported between high-strength and normal-strength OPC concretes, indicating that the geopolymer concrete exhibits higher brittleness than its OPC counterpart. This trend was found to be consistent between pastes and concretes, implying that the difference between geopolymer and OPC concrete is due to the type of matrix formation (geopolymerisation or hydration). For geopolymer concretes made with different mix parameters, fracture properties are closely correlated to their compressive strength.

How rewarding is technical analysis? Evidence from Singapore stock market

Abstract: This paper focuses on the role of technical analysis in signalling the timing of stock market entry and exit. Test statistics are introduced to test the performance of the most established of the trend followers, the Moving Average, and the most frequently used counter-trend indicator, the Relative Strength Index. Using Singapore data, the results indicate that the indicators can be used to generate significantly positive return. It is found that member firms of Singapore Stock Exchange (SES) tend to enjoy substantial profits by applying technical indicators. This could be the reason why most member firms do have their own trading teams that rely heavily on technical analysis.

Metal complexes as a promising source for new antibiotics.

Abstract: There is a dire need for new antimicrobial compounds to combat the growing threat of widespread antibiotic resistance. With a currently very scarce drug pipeline, consisting mostly of derivatives of known antibiotics, new classes of antibiotics are urgently required. Metal complexes are currently in clinical development for the treatment of cancer, malaria and neurodegenerative diseases. However, only little attention has been paid to their application as potential antimicrobial compounds. We report the evaluation of 906 metal-containing compounds that have been screened by the Community for Open Antimicrobial Drug Discovery (CO-ADD) for antimicrobial activity. Metal-bearing compounds display a significantly higher hit-rate (9.9%) when compared to the purely organic molecules (0.87%) in the CO-ADD database. Out of 906 compounds, 88 show activity against at least one of the tested strains, including fungi, while not displaying any cytotoxicity against mammalian cell lines or haemolytic properties. Herein, we highlight the structures of the 30 compounds with activity against Gram-positive and/or Gram-negative bacteria containing Mn, Co, Zn, Ru, Ag, Eu, Ir and Pt, with activities down to the nanomolar range against methicillin resistant S. aureus (MRSA). 23 of these complexes have not been reported for their antimicrobial properties before. This work reveals the vast diversity that metal-containing compounds can bring to antimicrobial research. It is important to raise awareness of these types of compounds for the design of truly novel antibiotics with potential for combatting antimicrobial resistance.

Development and Application of a Diagnostic Instrument to Evaluate Grade-11 and -12 Students' Concepts of Covalent Bonding and Structure Following a Course of Instruction.

Abstract: This article initially outlines a procedure used to develop a written diagnostic instrument to identify grade-11 and -12 students' misconceptions and misunderstandings of the chemistry topic covalent bonding and structure. The content to be taught was carefully defined through a concept map and propositional statements. Following instruction, student understanding of the topic was identified from interviews, student-drawn concept maps, and free-response questions. These data were used to produce 15 two-tier multiple-choice items where the first tier examined content knowledge and the second examined understanding of that knowledge in six conceptual areas, namely, bond polarity, molecular shape, polarity of molecules, lattices, intermolecular forces, and the octet rule. The diagnostic instrument was administered to a total of 243 grade-11 and -12 chemistry students and has a Cronbach alpha reliability of 0.73. Item difficulties ranged from 0.13 to 0.60; discrimination values ranged from 0.32 to 0.65. Each item was analyzed to ascertain student understanding of and identify misconceptions related to the concepts and propositional statements underlying covalent bonding and structure.

Palaeoproterozoic assembly of the North China Craton

Abstract: The basement of the North China Craton consists of the Eastern and Western blocks, separated by the Central Zone. Both the Eastern and Western blocks are dominated by late Archaean tonalitic–trondhjemitic–granodioritic gneiss complexes interdigitated with minor supracrustal rocks metamorphosed at ~2.5 Ga, with anticlockwise P–T paths. The Central Zone is composed of reworked late Archaean components and Palaeoproterozoic juvenile crustal materials that underwent regional metamorphism at ~1.85 Ga, with clockwise P–T paths involving isothermal decompression as a result of collision between the Eastern and Western blocks, which resulted in the final assembly of the North China Craton.