Microstructures and bond strengths of the calcium phosphate coatings formed on titanium from different simulated body fluids

Calcium phosphate (Ca-P) coatings were deposited on Ti substrates by a biomimetic method from m-SBF and 10× SBF, respectively. Comparative study of microstructures and bond strengths of the Ca-P coatings deposited from those different SBFs was carried out. Effect of the surface roughness of the substrates on the bond strength of the Ca-P coatings was also studied. Scanning electron microscopy (SEM), X-ray diffractometry (XRD), Fourier transformed infrared spectroscopy (FTIR), inductive coupled plasma spectrometry (ICP) and thermogravimetry (TG) were used to characterize the Ca-P coatings. The bond strengths between the coatings and Ti substrates were measured using an adhesive strength test. Results indicated that the ionic concentrations of the SBFs and the surface roughness of the substrate had a significant influence on the formation, morphology and bond strength of the Ca-P precipitates. The induction period of time to deposit a complete Ca-P layer from the m-SBF is much longer, but the Ca-P coating is denser and has higher bond strength than that formed from the 10× SBF. The Ti with a surface roughness of R_a 0.64 µm and R_z 2.81 µm favoures the formation of a compact Ca-P coating from the m-SBF with the highest bond strength of approximately 15.5 MPa.

Lateral strength of zero bond masonry walls subjected to wind loads

Masonry walls are usually laid with the individual masonry units along a course overlapping units in the course below. Commonly, the perpend joints in the course occur above the mid-points of the units below to form a ‘half-bond’ or above a third point to form a ‘third-bond’. The amount of this overlap has a profound influence on the strength of a wall supported on three or four sides, where lateral pressures from wind cause combined vertical and horizontal flexure. Where masonry units are laid with mortar joints, the torsional shear bond resistance between the mortar and overlapping units largely determines the horizontal flexural strength. If there is zero bond strength between units, then the horizontal flexural strength is derived from the frictional resistance to torsion on the overlapping bed-faces of the units. This thesis reports a theoretical and experimental investigation into the frictional properties of overlapping units when subjected to combinations of vertical and horizontal moments and vertical axial compression. These basic properties were used to develop a theory to predict the lateral strength of walls supported on two, three or four sides. A plastic theory of behaviour was confirmed by experiment. The theory was then used to determine maximum unbraced panel sizes for particular boundary conditions. Design charts were developed to determine temporary bracing requirements for panels during construction.

Predicting the resistance of fired clay bricks to salt attack

The salt attack of Fired Clay Bricks (FCBs) causes surface damage that is aesthetically displeasing and eventually leads to structural damage. Methods for determining the resistances of FCBs to salt weathering have mainly tried to simulate the process by using accelerating aging tests. Most research in this area has concentrated on the types of salt that can cause damage and the damage that occurs during accelerated aging tests. This approach has lead to the use of accelerated aging tests as standard methods for determining resistance. Recently, it has been acknowledged that are not the most reliable way to determine salt attack resistance for all FCBs in all environments. Few researchers have examined FCBs with the aim of determining which material and mechanical properties make a FCB resistant to salt attack. The aim of this study was to identify the properties that were significant to the resistance of FCBs to salt attack. In doing so, this study aids in the development of a better test method to assess the resistance of FCBs to salt attack. The current Australian Standard accelerated aging test was used to measure the resistance of eight FCBs to salt attack using sodium sulfate and sodium chloride. The results of these tests were compared to the water absorption properties and the total porosity of FCBs. An empirical relationship was developed between the twenty-four-hour water absorption value and the number of cycles to failure from sodium sulfate tests. The volume of sodium chloride solution was found to be proportional to the total porosity of FCBs in this study. A phenomenological discussion of results led to a new mechanism being presented to explain the derivation of stress during salt crystallisation of anhydrous and hydratable salts. The mechanical properties of FCBs were measured using compression tests. FCBs were analysed as cellular materials to find that the elastic modules of FCBs was equivalent for extruded FCBs that had been fired a similar temperatures and time. Two samples were found to have significantly different elastic moduli of the solid microstructure. One of these samples was a pressed brick that was stiffer due to the extra bond that is obtained during sintering a closely packed structure. The other sample was an extruded brick that had more firing temperature and time compared with the other samples in this study. A non-destructive method was used to measure the indentation hardness and indentation stress-strain properties of FCBs. The indentation hardness of FCBs was found to be proportional to the uniaxial compression strength. In addition, the indentation hardness had a better linear correlation to the total porosity of FCBs except for those samples that had different elastic moduli of the solid microstructure. Fractography of exfoliated particles during salt cycle tests and compression tests showed there was a similar pattern of fracture during each failure. The results indicate there were inherent properties of a FCB that determines the size and shape of fractured particles during salt attack. The microstructural variables that determined the fracture properties of FCBs were shown to be important variables to include in future models that attempt to estimate the resistance of FCBs to salt attack.

Understanding property cycles in a residential market

Purpose – This paper aims to review property cycle theory and the relevance of the larger body of knowledge about cycles with reference to the housing market. It also aims to highlight the lack of research into property cycles in the residential sector on a suburb or smaller region basis, as well as the potential for increased knowledge about cycles to assist to avoid housing stress.

Design/methodology/approach – The paper conducts a literature review of previous cycle research and encourages the use of cycle theory. It discusses the established body of knowledge about business cycles and the office market sector, as well as investigating levels of housing affordability and how detailed knowledge about property cycles can assist to decrease housing affordability in residential areas, which will eventually experience a downturn.

Findings – It is argued that an increased level of certainty about cycle behaviour in particular suburbs will give households a higher level of confidence when considering whether and when to enter the market. Property cycle research has the potential to assist low-income homeowners to better understand the characteristics of cycles and associated risks in each residential.

Research limitations/implications – This is a conceptual paper and has conducted a review of cycle research and housing affordability in certain countries. Some areas or countries may be affected to varying degrees by property cycles and levels of housing affordability.

Practical implications – In extended periods of high volatility it is argued that a better understanding of housing cycles will allow more homeowners to avoid negative equity and the stress associated with repossessions. Property cycles are unavoidable although there is typically relatively little information available in the open market about the timing and amplitude of cycles in individual areas.

Originality/value – This paper is unique as it highlights the potential for property cycles to be used to avoid housing stress in the residential market. Traditionally cycle research is used to increase returns and avoid downturns in the office and/or business sectors.

Cycles of genocide, stories of denial : Atom Egoyan's Ararat

This article focuses on Atom Egoyan's Ararat and explores how, through a convoluted narrative structure, Egoyan grapples with denial of the Armenian Genocide and the consequences of those denials for present generations—both Turkish and Armenian—illuminated in the film as an extension of the genocide. Egoyan uses a film-within-a-film to move beyond a popular definition of genocide as mass killing alone and links the understanding of stories, truths, and perspectives in everyday life to the dehumanizing acts of genocide. Employing the philosopher Emmanuel Levinas’ ethical theory of the Other (the ethical) and philosophical understandings of ontology (dehumanization) to illuminate the genocide and its ongoing denial, this article contends that Egoyan's focus on the generations of genocide survivors points to the ethical responsibility to one another that underlies everyday lives and sits at the heart of what is absent in the acts of genocide.

Influence of deformation-induced heating on the bond strength of rolled metal multilayers

The bond strength of various metal multilayers produced by cold rolling of metal foils with different thermal conductivity was investigated. Results indicated that the metallic multilayer system with low thermal conductivity exhibited relative high bond strength while high thermal conductivity metal system may fail to be roll-bonded together. The relationship between the deformation-induced localized heating and the bond strength were discussed.

Effects of deformation-induced heating on bond strength of rolled metal multilayer

The bond strength of various metal multilayers produced by cold rolling of metal foils with different thermal conductivity was investigated. Results indicated that under the same conditions of deformation and surface preparation, the metallic multilayer system with low thermal conductivity exhibited relative high bond strength while high thermal conductivity metal system may fail to be roll-bonded together. The relationship between the deformation-induced localized heating and the bond strength were discussed. The deformation-induced localized heating in the low thermal conductivity metal multilayer systems may provide opportunities for achieving a successful accumulative roll bonding or a “cold roll/heat treatment/cold roll” process to synthesize metallic multilayer materials.

Are business cycles stationary fluctuations around a deterministic trend? empirical evidence from 79 developing countries

There is a large literature that tests the univariate time series properties of the real output series following the seminal work of Nelson and Plosser (1982). Whether or not real output is characterized by a unit root process has important implications. A unit root in real output, for instance, is inconsistent with the notion that business cycles are stationary fluctuations around a deterministic trend. In this paper, we investigate the univariate time series properties of real output for 79 developing countries using the conventional augmented Dickey and Fuller (1979) unit root test, the Zivot and Andrews’ (1992) one structural break unit root test, and the Lumsdaine and Papell (1997) two structural breaks unit root test. Our main finding is that, for 40 countries, real output is stationary around a trend. This indicates that business cycles are stationary fluctuations around a deterministic trend for only 51% of the developing countries in our sample.

Drought-rainfall cycles as potential environmental drivers of fowl plague and Newcastle disease uutbreaks in Australian poultry

Climatic conditions in Australia are erratic and characterised by periods of intense rainfall followed by periods of intense drought. This has considerable impact on the population dynamics and ecology of many Australian species of waterfowl, which are thought to form the reservoir of avian influenza viruses (AIV) but may also be important carriers (and possibly reservoirs) of other diseases (e.g. bursal disease, Newcastle disease). During the wet, waterfowl numbers increase with many serologically naive juveniles entering the population. During the subsequent period of drought, bird densities increase in the few remaining wetlands. We hypothesise that it is during this period of increasing densities of naive birds that the population’s viral prevalence of some infectious diseases may increase dramatically. Indeed, there exists a remarkable and suggestive coincidence between outbreaks of fowl plaque and Newcastle disease in Australian poultry farms and the periods of drought following a very wet period. In other words, we suspect a link between increased risk for disease outbreaks in poultry farms and the hypothesised high in the prevalences of the viruses causing these diseases in waterfowl. Given that poultry farms may provide ideal conditions for development of high-pathogenic strains, there is also a reciprocal risk for wildlife involved during these periods.